diff options
| author | Roger Frank <rfrank@pglaf.org> | 2025-10-15 05:28:39 -0700 |
|---|---|---|
| committer | Roger Frank <rfrank@pglaf.org> | 2025-10-15 05:28:39 -0700 |
| commit | abdaef1816e25a596cb8c5a78ef1ad0cee97d4eb (patch) | |
| tree | 78eec1d3fa977dc539e938eb0ce297fa6cbcf406 | |
| -rw-r--r-- | .gitattributes | 3 | ||||
| -rw-r--r-- | 6970-8.txt | 11697 | ||||
| -rw-r--r-- | 6970-8.zip | bin | 0 -> 257044 bytes | |||
| -rw-r--r-- | 6970.txt | 11697 | ||||
| -rw-r--r-- | 6970.zip | bin | 0 -> 256981 bytes | |||
| -rw-r--r-- | LICENSE.txt | 11 | ||||
| -rw-r--r-- | README.md | 2 | ||||
| -rw-r--r-- | old/7brd110.txt | 11666 | ||||
| -rw-r--r-- | old/7brd110.zip | bin | 0 -> 262597 bytes | |||
| -rw-r--r-- | old/8brd110.txt | 11666 | ||||
| -rw-r--r-- | old/8brd110.zip | bin | 0 -> 262646 bytes |
11 files changed, 46742 insertions, 0 deletions
diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/6970-8.txt b/6970-8.txt new file mode 100644 index 0000000..14ba224 --- /dev/null +++ b/6970-8.txt @@ -0,0 +1,11697 @@ +Project Gutenberg's The History of a Mouthful of Bread, by Jean Mace + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The History of a Mouthful of Bread + And its effect on the organization of men and animals + +Author: Jean Mace + +Posting Date: September 3, 2012 [EBook #6970] +Release Date: November, 2004 +First Posted: February 18, 2003 + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK THE HISTORY OF A MOUTHFUL OF BREAD *** + + + + +Produced by Juliet Sutherland, Charles Franks and the +Online Distributed Proofreading Team. + + + + + + + + + + +THE HISTORY OF A MOUTHFUL OF BREAD: +And Its Effect on the Organization of Men and Animals. + +BY JEAN MACÉ. + +Translated Prom the Eighth French Edition, By Mrs. Alfred Gatty. + + + + +EXTRACTS FROM THE PREFACE TO THE ENGLISH EDITION. + +The volume of which the following pages are a translation, has been +adopted by the _University Commission at Paris_ among their prize +books, and has reached an eighth edition. Perhaps these facts speak +sufficiently in its favor; but as translator, and to some extent editor, +I wish to add my testimony to the great charm as well as merit of the +little work. I sat down to it, I must own, with no special predilection +in favor of the subject as a suitable one for young people; but in the +course of the labor have become a thorough convert to the author's +views that such a study--perhaps I ought to add, so pursued as he has +enabled it to be--is likely to prove a most useful and most desirable +one. + +The precise age at which the interest of a young mind can be turned +towards this practical branch of natural history is an open question, +and not worth disputing about. It may vary even in different +individuals. The letters are addressed to a _child_--in the original +even to a _little girl_--and most undoubtedly, as the book stands, it is +fit for any child's perusal who can find amusement in its pages: while +to the rather older readers, of whom I trust there will be a great many, +I will venture to say that the advantage they will gain in the subject +having been so treated as to be brought within the comprehension and +adapted to the tastes of a child, is pretty nearly incalculable. The +quaintness and drollery of the illustrations with which difficult +scientific facts are set forth will provoke many a smile, no doubt, and +in some young people perhaps a tendency to feel themselves treated +_babyishly_; but if in the course of the babyish treatment they find +themselves almost unexpectedly becoming masters of an amount of valuable +information on very difficult subjects, they will have nothing to +complain of. Let such young readers refer to even a popular +Encyclopaedia for an insight into any of the subjects of the +twenty-eight chapters of this volume--"The Heart," "The Lungs," "The +Stomach," "Atmospheric Pressure,"--no matter which, and see how much +they can understand of it without an amount of preliminary instruction +which would require half-a-year's study, and they will then thoroughly +appreciate the quite marvellous ingenuity and beautiful skill with +which M. Macé has brought the great leading anatomical and physical +facts of life out of the depths of scientific learning, and made them +literally comprehensible by a child. + + * * * * * + +There is one point (independent of the scientific teaching) and that, +happily, the only really important one, in which the English translator +has had no change to make or desire. The religious teaching of the +book is unexceptionable. There is no strained introduction of the +subject, but there is throughout the volume an acknowledgment of the +Great Creator of this marvellous work of the human frame, of the daily +and hourly gratitude we owe to Him, and of the utter impossibility of +our tracing out half his wonders, even in the things nearest to our +senses, and most constantly subject to observation. M. Macé will help, +and not hinder the humility with which the Christian naturalist lifts +one veil only to recognise another beyond. + +It will be satisfactory to any one who may be inclined to wonder how +a lady can feel sure of having correctly translated the various +scientific and anatomical statements contained in the volume, to know +that the whole has been submitted to the careful revision of a medical +friend, to whom I have reason to be very grateful for valuable +explanations and corrections whenever they were necessary. In the same +way the chapter on "Atmospheric Pressure," where, owing to the +difference between French and English weights and measures, several +alterations of illustrations, etc., had to be made, has received similar +kind offices from the hands of a competent mathematician. + + * * * * * + +MARGARET GATTY. + +Ecclesfield, June, 1864. + + + + +NOTE TO THE AMERICAN EDITION. + +In May '66, the seventeenth edition of this work was on sale in Paris. +The date of Mrs. Gatty's preface, it will be observed, is June '64, +and at that time, the eighth French edition only had been reached. +That it should be a popular book and command large sale wherever it +is known, will not surprise any one who reads it: the only remarkable +circumstance about it is, that it should not have been republished +here long ere this. Even this may probably be accounted for, on the +supposition that the title under which the translation was published +in England, was so unmeaning--conveying not the slightest idea of the +contents of the book--that none of our publishers even ventured to +hand it over to their "readers" to examine. + +The author's title, _The History of a Mouthful of Bread_, while +falling far short of giving a clear notion of the entire scope of the +work, is shockingly diluted and meaningless, when translated _The +History of a Bit of Bread!_ + +To the translation of Mrs. Gatty, which is in the main an excellent +one, for she has generally seized upon the idea of the author and +rendered it with singular felicity, it may be very properly objected +that she has taken some liberties with the text when there was any +conflict of opinion between herself and her author, and has given her +own ideas instead of his, which is, probably, what she refers to when +she calls herself "to some extent editor." + +The reader of this edition will, in all these cases, find the thought +of the author and not that of his translator; for the reason that a +careful examination of the original has convinced the publisher that +in every instance the author was to be preferred to the translator, +to say nothing of the right an author may have to be faithfully +translated. + +Besides making these restorations, the copy from which this edition +was printed has been carefully compared with the last edition of the +author and a vast number of corrections made, and in its present shape +it is respectfully submitted and dedicated to every one (whose name +is legion, of course) who numbers among his young friends a "_my +dear child_" to present it to. + + + + + +CONTENTS. + +I.--INTRODUCTION + +FIRST PART MAN. + +II.--THE HAND +III.--THE TONGUE +IV.--THE TEETH +V.--THE TEETH (_continued_) +VI.--THE TEETH (_continued_) +VII.--THE THROAT +VIII.--THE STOMACH +IX.--THE STOMACH (_continued_) +X.--THE INTESTINAL CANAL +XI.--THE LIVER +XII.--THE CHYLE +XIII.--THE HEART +XIV.--THE ARTERIES +XV.--THE NOURISHMENT OF THE ORGANS +XVI.--THE ORGANS +XVII.--ARTERIAL AND VENOUS BLOOD +XVIII.--ATMOSPHERIC PRESSURE +XIX.--THE ACTION OF THE LUNGS +XX.--CARBON AND OXYGEN +XXI.--COMBUSTION +XXII.--ANIMAL HEAT +XXIII.--ACTION OF THE BLOOD UPON THE ORGANS +XXIV.--THE WORK OF THE ORGANS +XXV.--CARBONIC ACID +XXVI.--ALIMENTS OF COMBUSTION +XXVII.--ALIMENTS OF NUTRITION (_continued_)--NITROGEN OR AZOTE +XXVIII.--COMPOSITION OF THE BLOOD + + +SECOND PART. + +ANIMALS. + +XXIX.--CLASSIFICATION OF ANIMALS +XXX.--MAMMALIA (_Mammals_) +XXXI.--MAMMALIA. (_Mammals_)--_continued_ +XXXII.--MAMMALIA--_continued_ +XXXIII.--MAMMALIA--_continued_ +XXXIV.--AVES. (_Birds_) +XXXV.--REPTILIA. (_Reptiles_) +XXXVI.--PISCES. (_Fishes_) +XXXVII.--INSECTA. (_Insects_) +XXXVIII.--CRUSTACEA--MOLLUSKA. (_Crustaceans and Mollusks_) +XXXIX.--VERMES--ZOOPHYTA. (_Worms and Zoophytes_) +XL.--THE NOURISHMENT OF PLANTS +CONCLUSION + + + +I. + +INTRODUCTION. + +I am going to tell you, my dear child, something of the life and nature +of men and animals, believing the information may be of use to you in +after-life, besides being an amusement to you now. + +Of course, I shall have to explain to you a great many particulars +which are generally considered very difficult to understand, and which +are not always taught even to grown-up people. But if we work together, +and between us succeed in getting them clearly into your head, it will +be a great triumph to me, and you will find out that the science of +learned men is more entertaining for little girls, as well as more +comprehensible, than it is sometimes supposed to be. Moreover, you +will be in advance of your years, as it were, and one day may be +astonished to find that you had mastered in childhood, almost as a +mere amusement, some of the first principles of anatomy, chemistry, +and several other of the physical sciences, as well as having attained +to some knowledge of natural history generally. + +I begin at once, then, with the _History of a Mouthful of Bread_, +although I am aware you may be tempted to exclaim, that if I am going +to talk only about that, I may save myself the trouble. You know all +about it, you say, as well as I do, and need not surely be told how +to chew a bit of bread-and-butter! Well, but you must let me begin at +the very beginning with you, and you have no notion what an incredible +number of facts will be found to be connected with this chewing of a +piece of bread. A big book might be written about them, were all the +details to be entered into. + +First and foremost--Have you ever asked yourself _why_ people eat? + +You laugh at such a ridiculous question. + +"Why do people eat? Why, because there are bonbons, and cakes, and +gingerbread, and sweetmeats, and fruit, and all manner of things good +to eat." Very well, that is a very good reason, no doubt, and you may +think that no other is wanted. If there were nothing but soup in the +world, indeed, the case would be different. There might be some excuse +then for making the inquiry. + +Now, then, let us suppose for once that there _is_ nothing in the +world to eat but soup; and it is true that there are plenty of poor +little children for whom there is nothing else, but who go on eating +nevertheless, and with a very good appetite, too, I assure you, as +their parents know but too well very often. Why do people eat, then, +even when they have nothing to eat but soup? This is what I am going +to tell you, if you do not already know. + +The other day, when your mamma said that your frock "had grown" too +short, and that you could not go out visiting till we had given you +another with longer sleeves and waist, what was the real cause of this +necessity? + +What a droll question, you say, and you answer--"Because I had grown, +of course." + +To which I say "of course," too; for undoubtedly it was you who had +outgrown your frock. But then I must push the question further, and +ask--How had you grown? + +Now you are puzzled. Nobody had been to your bed and pulled out your +arms or your legs as you lay asleep. Nobody had pieced a bit on at the +elbow or the knee, as people slip in a new leaf to a table when there +is going to be a larger party than usual at dinner. How was it, then, +that the sleeves no longer came down to your wrists, or that the body +only reached your knees? Nothing grows larger without being added to, +any more than anything gets smaller without having lost something; you +may lay that down as a rule, once for all. If, therefore, nothing was +added to you from without, something must have been added to you from +within. Some sly goblin, as it were, must have been cramming into your +frame whatever increase it has made in arms, legs, or anything else. +And who, do you think, this sly goblin is? + +Why, my dear, it is _yourself!_ + +Ay! Bethink you, now, of all the bread-and-butter, and bonbons, and +gingerbread, and cakes, and sweetmeats, and even soup and plain food +(the soup and plain food being the most useful of all) which you have +been sending, day by day, for some time past, down what we used to +call "the red lane," into the little gulf below. What do you think +became of them when they got there? Well, they set to work at once, +without asking your leave, to transform themselves into something else; +and gliding cunningly into all the holes and corners of your body, +became there, each as best he might, bones, flesh, blood, etc., +etc. Touch yourself where you will, it is upon these things you lay +your hand, though, of course, without recognizing them, for the +transformation is perfect and complete. And it is the same with +everybody. + +Look at your little pink nails, which push out further and further +every morning; examine the tips of your beautiful fair hair, which +gets longer and longer by degrees; coming out from your head as grass +springs up from the earth; feel the firm corners of your second teeth, +which are gradually succeeding those which came to you in infancy; you +have _eaten_ all these things, and that no long time ago. + +Nor are you children the only creatures who are busy in this way. There +is your kitten, for instance, who a few months ago was only a tiny bit +of fur, but is now turning gradually into a grown-up cat. It is her +daily food which is daily becoming a cat inside her--her saucers of +milk now, and very soon her mice, all serve to the same end. + +The large ox, too, of whom you are so much afraid, because you cannot +as yet be persuaded what a good-natured beast he really is, and how +unlikely to do any harm to children who do none to him--that large ox +began life as a small calf, and it is the grass which he has been +eating for some time past which has transformed him into the huge mass +of flesh you now see, and which by-and-by will be eaten by man, to +become man's flesh in the same manner. + +But, further, still: Even the forest trees, which grow so high and +spread so wide, were at first no bigger than your little finger, and +all the grandeur and size you now look upon, they have taken in by the +process of eating. "What, _do trees eat?_" you ask. + +Verily, do they; and they are, by no means, the least greedy of eaters, +for they eat day and night without ceasing. Not, as you may suppose, +that they crunch bonbons, or anything else as you do; nor is the process +with them precisely the same as with you. Yet you will be surprised +hereafter, I assure you, to find how many points of resemblance exist +between them and us in this matter. But we will speak further of this +presently. + +Now, I think you must allow that there are few fairytales more +marvellous than this history of bread and meat turning into little +boys and girls, milk and mice turning into cats, and grass into oxen! +And I call it a _history_, observe, because it is a transformation +that never happens suddenly, but by degrees, as time goes on. + +Now, then, for the explanation. You have heard, I dare say, of those +wonderful spinning-machines which take in at one end a mass of raw +cotton, very like what you see in wadding, and give out at the other +a roll of fine calico, all folded and packed up ready to be delivered +to the tradespeople. Well, you have within you, a machine even more +ingenious than that, which receives from you all the bread-and-butter +and other sorts of food you choose to put into it, and returns it to +you changed into the nails, hair, bones and flesh we have been talking +about, and many other things besides; for there are quantities of +things in your body, all different from each other, which you are +manufacturing in this manner all day long, without knowing anything +about it. And a very fortunate thing this is for you: for I do not +know what would become of you if you had to be thinking from morning +to night of all that requires to be done in your body, as your mother +has to look after and remember all that has to be done in the house. +Just think what a relief it would be to her to possess a machine which +should sweep the rooms, cook the dinners, wash the plates, mend torn +clothes, and keep watch over everything without giving her any trouble; +and, moreover, make no more noise or fuss than yours does, which has +been working away ever since you were born without your ever troubling +your head about it, or probably even knowing of its existence! Just +think of this and be thankful. + +But do not fancy you are the only possessor of a magical machine of +this sort. Your kitten has one also, and the ox we were speaking of, +and all other living creatures. And theirs render the same service to +them that yours does to you, and much in the same way; for all these +machines are made after one model, though with certain variations +adapted to the differences in each animal. And, as you will see +by-and-by, these variations exactly correspond with the different sort +of work that has to be done in each particular case. For instance, +where the machine has grass to act upon, as in the ox, it is differently +constructed from that in the cat which has to deal with meat and mice. +In the same way in our manufactories, though all the spinning-machines +are made upon one model, there is one particular arrangement for those +which spin cotton, another for those which spin wool, another for flax, +and so on. + +But, further: + +You have possibly noticed already, without being told, that all animals +are not of equal value; or, at least, to use a better expression, they +have not all had the same advantages bestowed on them. The dog, for +instance, that loving and intelligent companion, who almost reads your +thoughts in your eyes, and is as affectionate and obedient to his master +as it were to be wished all children were to their parents--this dog +is, as you must own, very superior, in all ways, to the frog, with its +large goggle eyes and clammy body, hiding itself in the water as soon +as you come near it. But again, the frog, which can come and go as it +likes, is decidedly superior to the oyster, which has neither head nor +limbs, and lives all alone, glued into a shell, in a sort of perpetual +imprisonment. + +Now the machine I have been telling you about is found in the oyster +and in the frog as well as in the dog, only it is less complicated, +and therefore less perfect in the oyster than in the frog; and less +perfect again in the frog than in the dog; for as we descend in the +scale of animals we find it becoming less and less elaborate--losing +here one of its parts, there another, but nevertheless remaining still +the same machine to all intents and purposes; though by the time it +has reached its lowest condition of structure we should hardly be able +to recognize it again, if we had not watched it through all its +gradations of form, and escorted it, as it were, from stage to stage. + +Let me make this clear to you by a comparison. + +You know the lamp which is lit every evening on the drawing-room table, +and around which you all assemble to work or read. Take off first the +shade, which throws the light on your book--then the glass which +prevents it smoking--then the little chimney which holds the wick and +drives the air into the flame to make it burn brightly. Then take away +the screw, which sends the wick up and down; undo the pieces one by +one, until none remain but those absolutely necessary to having a light +at all--namely, the receptacle for the oil and the floating wick which +consumes it. + +Now if any one should come in and hear you say, "Look at my lamp," +what would he reply? He would most likely ask at once, "What lamp?"--for +there would be very little resemblance to a lamp in that mere ghost +of one before him. + +But to you, who have seen the different parts removed one after another, +that wick soaked in oil (let your friend shake his head about it as +he pleases) will still be the lamp to you, however divested of much +that made it once so perfect, and however dimly it may shine in +consequence. + +And this is exactly what happens when the machine we are discussing +is examined in the different grades of animals. The ignoramus who has +not followed it through its changes and reductions cannot recognize +it when it is presented to him in its lowest condition; but any one +who has carefully observed it throughout, knows that it is, in point +of fact, the same machine still. + +This, then, is what we are now going to look at together, my dear +little girl. We will study first, piece by piece, the exquisite machine +within ourselves, which is of such unceasing use to us as long as we +do not give it more than a proper share of work to perform. Do you +understand? We will see what becomes of the mouthful of bread which +you place so coolly between your teeth, as if when that was done nothing +further remained to be thought about. We will trace it in its passage +through every part of the machine, from beginning to end. It will +therefore be simply only the _History of a Mouthful of Bread_ I +am telling you, even while I seem to be talking of other matters; for +to make that comprehensible I shall have to enter into a good many +explanations. + +And when you have thoroughly got to understand the history of what you +eat yourself, we will look a little into the history of what other +animals eat, beginning by those most like ourselves, and going on to +the rest in regular succession downwards. And while we are on the +subject, I will say a word or two on the way in which vegetables eat, +for, as you remember, I have stated that they do eat also. + +Do you think this is likely to interest you, and be worth the trouble +of some thought and attention? + +Perhaps you may tell me it sounds very tedious, and like making a great +fuss about a trifle; that you have all your life eaten mouthfuls of +bread without troubling yourself as to what became of them, and yet +have not been stopped growing by your ignorance, any more than the +little cat, who knows no more how it happens than you do. + +True, my dear; but the cat is only a little cat, and you are a little +girl. Up to the present moment you and she have known, one as much as +the other on this subject, and on that point you have therefore had +no superiority over her. But she will never trouble herself about it, +and will always remain a little cat. You, on the contrary, are intended +by God to become something more in intelligence than you are now, and +it is by learning more than the cat that you will rise above her in +this respect. To learn, is the duty of all men, not only for the +pleasure of curiosity and the vanity of being called learned, but +because in proportion to what we learn we approach nearer to the destiny +which God has appointed to man, and when we walk obediently in the +path which God himself has marked out for us, we necessarily become +better. + +It is sometimes said to grown-up people, that it is never too late to +learn. To children one may say that it is never too early to learn. +And among the things which they may learn, those which I want now to +teach you have the double merit of being, in the first place amusing, +and afterwards, and above all, calculated to accustom you to think of +God, by causing you to observe the wonders which He has done. Sure am +I that when you know them you will not fail to admire them; moreover +I promise your mother that you will be all the better, as well as +wiser, for the study. + + + + +FIRST PART.--MAN. + +LETTER II. + +THE HAND. + +At the foot of the mountains, from whence I write to you, my dear +child, when we want to show the country to a stranger, we commence by +making him climb one of the heights, whence he may take in at a glance +the whole landscape below, all the woods and villages scattered over +the plain, even up to the blue line of the Rhine, which stretches out +to the distant horizon. After this he will easily find his way about. + +It is to the top of a mountain equally useful that I have just led +you. It has cost you some trouble to climb with me. You have had to +keep your eyes very wide open that you might see to the end of the +road we had to go together. Now then, let us come down and view the +country in detail. Then we shall go as if we were on wheels. + +And now let us begin at the beginning: + +Well, doubtless, as the subject is eating, you will expect me to begin +with the mouth. + +Wait a moment; there is something else first. But you are so accustomed +to make use of it, that you have never given it a thought, I dare say. + +It is not enough merely that one should have a mouth; we must be able +to put what we want within it. What would you do at dinner, for +instance, if you had no hands? + +The hand is then the first thing to be considered. + +I shall not give you a description of it; you know what it is like. +But what, perhaps, you do not know, because you have never thought +about it, is, the reason why your hand is a more convenient, and +consequently more perfect, instrument than a cat's paw, for instance, +which yet answers a similar purpose, for it helps the cat to catch +mice. + +Among your five fingers there is one which is called the thumb, which +stands out on one side quite apart from the others. Look at it with +respect; it is to these two little bones, covered over with a little +flesh, that man owes part of his physical superiority to other animals. +It is one of his best servants, one of the noblest of God's gifts to +him. Without the thumb three-fourths (at least) of human arts would +yet have to be invented; and to begin with, the art not only of carrying +the contents of one's plate to one's mouth, but of filling the plate +(a very important question in another way) would, but for the thumb, +have had difficulties to surmount of which you can form no idea. + +Have you noticed that when you want to take hold of anything (a piece +of bread, we will say, as we are on the subject of eating), have you +noticed that it is always the thumb who puts himself forward, and that +he is always on one side by himself, whilst the rest of the fingers +are on the other? If the thumb is not helping, nothing remains in your +hand, and you don't know what to do with it. Try, by way of experiment, +to carry your spoon to your mouth without putting your thumb to it, +and you will see what a long time it will take you to get through a +poor little plateful of broth. The thumb is placed in such a manner +on your hand that it can face each of the other fingers one after +another, or all together, as you please; and by this we are enabled +to grasp, as if with a pair of pincers, whatever object, whether large +or small. Our hands owe their perfection of usefulness to this happy +arrangement, which has been bestowed on no other animal, except the +monkey, our nearest neighbor. + +I may even add, while we are about it, that it is this which +distinguishes the hand from a paw or a foot. Our feet, which have other +things to do than to pick up apples or lay hold of a fork, our feet +have also each five fingers, but the largest cannot face the others; +it is not a thumb, therefore, and it is because of this that our feet +are not hands. Now the monkey has thumbs on the four members +corresponding to our arms and legs, and thus we may say that he has +hands at the end of his legs as well as of his arms. Nevertheless, he +is not on that account better off than we are, but quite the contrary. +I will explain this to you presently. + +To return to our subject. You see that it was necessary, before saying +anything about the mouth, to consider the hand, which is the mouth's +purveyor. Before the cook lights the fires the maid must go to market, +must she not? And it is a very valuable maid that we have here: what +would become of us without her? + +If we were in the habit of giving thought to everything, we should +never even gather a nut without being grateful to the Providence which +has provided us with the thumb, by means of which we are able to do +it so easily. + +But however well I may have expressed it, I am by no means sure, after +all, that I have succeeded in showing you clearly, how absolutely +necessary our hand is to us in eating, and why it has the honor to +stand at the beginning of the history of what we eat. + +It still appears to you, I suspect, that even if you were to lose the +use of your hands you would not, for all that, let yourself die of +hunger. + +This is because you have not attended to another circumstance, which +nevertheless demands your notice--namely, that from one end of the +world to the other, quantities of hands are being employed in providing +you with the wherewithal to eat. + +To go on further: Have you any idea how many hands have been put in +motion merely to enable you to have your coffee and roll in the morning? +What a number, to be sure, over this cup of coffee (which is a trifle +in comparison with the other food you will consume in the course of +the day); from the hand of the negro who gathered the coffee crop to +that of the cook who ground the berries, to say nothing of the hand +of the sailor who guided the ship which bore them to our shores. Again, +from the hand of the laborer who sowed the corn, and that of the miller +who ground it into flour, to the hand of the baker who made it into +a roll. Then the hand of the farmer's wife who milked the cow, and the +hand of the refiner who made the sugar; to say nothing of the many +others who prepared his work for him, and I know not how many more. + +How would it be, then, if I were to amuse myself by counting up all +the hands that are wanted to furnish-- + + The sugar-refiner's manufactory, + The milkmaid's shed, + The baker's oven, + The miller's mill, + The laborer's plough, + The sailor's ship? + +And even now is there nothing we have forgotten? Ah, yes! the most +important of all the hands to you;--the hand which brings together +for your benefit the fruits of the labor of all the others--the hand +of your dear mother, always active, always ready, that hand which so +often acts as yours when your own is awkward or idle. + +Now, then, you see how you might really manage to do without those two +comparatively helpless little paws of yours (although there is a thumb +to each), without suffering too much for want of food. With such an +army of hands at work, in every way, to furnish provision for that +little mouth, there would not be much danger. + + +But cut off your cat's fore paws--oh dear! what am I saying? Suppose, +rather, that she has not got any, and then count how many mice she +will catch in a day. The milk you give her is another matter, remember. +Like your cup of coffee, that is provided for her by others. + +Believe me, if you were suddenly left all alone in a wood, like those +pretty squirrels who nibble hazel-nuts so daintily, you would soon +discover, from being thus thrown upon your own resources, that the +mouth is not the only thing required for eating, and that whether it +be a paw or a hand, there must always be a servant to go to market for +Mr. Mouth, and to provide him with food. + +Happily, we are not driven to this extremity. We take hold of our +coffee-biscuit between the thumb and forefinger, and behold it is on +its road--Open the mouth, and it is soon done! + +But before we begin to chew, let us stop to consider a little. + +The mouth is the door at which everything enters. Now, to every +well-kept door there is a doorkeeper, or porter. And what is the office +of a well-instructed porter? Well, he asks the people that present +themselves, who they are, and what they have come for; and if he does +not like their appearance, he refuses them admittance. We too, then, +to be complete, need a porter of this sort in our mouths, and I am +happy to say we have one accordingly. I wonder whether you know him? +You look at me quite aghast! Oh, ungrateful child, not to know your +dearest friend! As a punishment, I shall not tell you who he is to-day. +I will give you till to-morrow to think about it. + +Meanwhile, as I have a little time left, I will say one word more about +what we are going to look at together. It would hardly be worth while +to tell you this pretty story which we have begun, if from time to +time we were not to extract a moral from it. And what is the moral of +our history to-day? + +It has more than one. + +In the first place it teaches you, if you never knew it before, that +you are under great obligations to other people, indeed to almost +everybody, and most of all perhaps to people whom you may be tempted +to look down upon. This laborer, with his coarse smock-frock and heavy +shoes, whom you are so ready to ridicule, is the very person who, with +his rough hand, has been the means of procuring for you half the good +things you eat. That workman, with turned-up sleeves, whose dirty black +fingers you are afraid of touching, has very likely blackened and +dirtied them in your service. You owe great respect to all these people, +I assure you, for they all work for you. Do not, then, go and fancy +yourself of great consequence among them--you who are of no use in any +way at present, who want everybody's help yourself, but as yet can +help nobody. + +Not that I mean to reproach you by saying this. Your turn has not come +yet, and everybody began like you originally. But I do wish to impress +upon you that you must prepare yourself to become some day useful to +others, so that you may pay back the debts which you are now +contracting. + +Every time you look at your little hand, remember that you have its +education to accomplish, its debts of honor to repay, and that you +must make haste and teach it to be very clever, so that it may no +longer be said of you, that you are of no use to anybody. + +And then, my dear child, remember that a day will come, when the revered +hands that now take care of your childhood--those hands which to-day +are yours, as it were--will become weak and incapacitated by age. You +will be strong, then, probably, and the assistance which you receive +now, you must then render to her, render it to her as you have received +it--that is to say, with your hands. It is the mother's hand which +comes and goes without ceasing about her little girl now. It is the +daughter's hand which should come and go around the old mother +hereafter--her hand and not another's. + +Here again, my child, the mouth is nothing without the hand. The mouth +says, "I love," the hand proves it. + + + +LETTER III. + +THE TONGUE. + +Now, about this doorkeeper, or porter, as we will call him, of the +mouth. I do not suppose you have guessed who he is; so I am going to +tell you. + +The porter who keeps the door of the mouth is _the sense of taste_. + +It is he who does the honors of the house so agreeably to proper +visitors, and gives such an unscrupulous dismissal to unpleasant +intruders. In other words, it is by his directions that we welcome so +affectionately with tongue and lips whatever is good to eat, and spit +out unhesitatingly whatever is unpleasant. + +I could speak very ill of this porter if I chose; which would not be +very pleasant for certain little gourmands that I see here, who think +a good deal too much of him. But I would rather begin by praising him. +I can make my exceptions afterwards. + +In the history I am going to give you, my dear child, there is one +thing you must never lose sight of, even when I do not allude to it; +and that is, that everything we shall examine into, has been expressly +arranged by God for the good and accommodation of our being in this +world; just as a cradle is arranged by a mother for the comfort of her +baby. We must look upon all these things, therefore, as so many +presentsfrom the Almighty himself; and abstain from speaking ill of +them, were it only out of respect for the hand which has bestowed them. + +Moreover, there is a very easy plan by which we may satisfy ourselves +of the usefulness and propriety of these gifts--namely, by considering +what would become of us if we were deprived of any one of them. + +Suppose, for instance, that you were totally deficient in the sense +of taste, and that when you put a piece of cake into your mouth, it +should create no more sensation in you than when you held it in your +hand? + +You would not have thought of imagining such a case yourself, I am +aware; for it never comes into a child's head to think that things can +be otherwise than as God has made them. And in that respect children +are sometimes wiser than philosophers. Nevertheless, we will suppose +this for once, and consider what would happen in consequence. + +Well, in the first place, you would eat old mouldy cake with just the +same relish as if it were fresh; and this mouldy cake, which now you +carefully avoid because it is mouldy, is very unwholesome food, and +would poison you were you to eat a great deal of it. + +I give this merely as an instance, but it is one of a thousand. And +although, with regard to eatables, you only know such as have been +prepared either in shops or in your mamma's kitchen, still you must +be aware there are many we ought to avoid, because they would do no +good in our stomachs, and that we should often be puzzled to distinguish +these from others, if the sense of taste did not warn us about them. +You must admit, therefore, that such warnings are not without their +value. + +In short, it is a marvellous fact that what is unfit for food, is +_almost always_ to be recognized as it enters the mouth, by its +disagreeable taste; a further proof that God has thought of everything. +Medicines, it is true, are unpleasant to the taste, and yet have to +be swallowed in certain cases. But we may compare them to +chimney-sweepers, who are neither pretty to look at, nor invited into +the drawing-room; but who, nevertheless, are from time to time let +into the grandest houses by the porters--though possibly with a +grimace--because their services are wanted. And in the same way +medicines have to be admitted sometimes--despite their +unpleasantness--because they, too, have to work in the chimney. Taste +does not deceive you about them, however; they are not intended to +serve as food. If any one should try to breakfast, dine, and sup upon +physic he would soon find this out. + +Besides, I only said _almost_ always, in speaking of unwholesome +food making itself known to us by its nasty taste; for it is an +unfortunate truth that men have invented a thousand plans for baffling +their natural guardian, and for bringing thieves secretly into the +company of honest people. They sometimes put poison, for instance, +into sugar--as is too often done in the case of those horrible green +and blue sugar plums, against which I have an old grudge, for they +poisoned a friend whom I loved dearly in my youth. Such things as these +pass imprudently by the porter, who sees nothing of their real +character--Mr. Sugar concealing the rogues behind him. + +Moreover, we are sometimes so foolish as not to leave the porter time +to make his examination. We swallow one thing after another greedily, +without tasting; and such a crowd of arrivals, coming in with a rush, +"forces the sentry," as they say; and whose fault is it, if, after +this, we find thieves established in the house? + +But animals have more sense than we have. + +Look at your kitten when you give her some tit-bit she is not acquainted +with--how cautiously and gently she puts out her nose, so as to give +herself time for consideration. Then how delicately she touches the +unknown object with the tip of her tongue, once, twice, and perhaps +three times. And when the tip of the tongue has thus gone forward +several times to make observations (for this is the great post of +observation for the cat's porter as well as for ours), she ventures +to decide upon swallowing, but not before. If she has the least +suspicion, no amount of coaxing makes any difference to her; you may +call "puss, puss," for ever; all your tender invitations are useless, +and she turns away. + +Very good; here then is one little animal, at least, who understands +for what end she has received the sense of taste, and who makes a +reasonable use of it. Very different from some children of my +acquaintance, who heedlessly stuff into their mouths whatever comes +into their hands, without even taking the trouble to taste it, and who +would escape a good many stomach-aches, if nothing else, if they were +as sensible as Pussy. + +This is the really useful side of _the sense of taste_; but its +agreeable side, which is sufficiently well known to you, is not to be +despised either, even on the grounds of utility. + +You must know, between ourselves, that eating would be a very tiresome +business if we did not taste what we are eating; and I can well imagine +what trouble mammas would have in persuading their children to come +to dinner or tea, if it were only a question of working their little +jaws, and nothing further. What struggles--what tears! And setting +aside children, who are by no means always the most disobedient to the +will of a good GOD, how few men would care to stop in the midst of +their occupations, to go and grind their teeth one against another for +half-an-hour, if there were not some pleasure attached to an exercise +not naturally amusing in itself? Ay, ay, my dear child, were it not +for the reward in pleasure which is given to men when they eat, the +human race, who as a whole do not live too well already, would live +still worse. And it is necessary that we should be fed, and well fed +too, if we would perform properly here below the mission which we have +received from above. + +Yes, "reward" was the word I used. Now it seems absurd to you, perhaps, +that it should be necessary to reward a man for eating a good dinner? +Well, well, GOD has been more kind to him, then, than you would be. +To every duty imposed by Him upon man, He has joined a pleasure as a +reward for fulfilling it. How many things should I not have to say to +you on this subject, if you were older? For the present, I will content +myself with making a comparison. + +When a mother thinks her child is not reasonable enough to do, of her +own accord, something which it is nevertheless important she should +do, as learning to read, for instance, or to work with her needle, +&c., she comes to the rescue with rewards, and gives her a plaything +when she has done well. And thus GOD, who had not confidence enough +in man's reason to trust to it alone for supplying the wants of human +nature, has placed a plaything in the shape of pleasure after every +necessity; and in supplying the want, man finds the reward. + +You will hardly believe that what I have here explained to you so +quietly by a childish comparison, has been, and alas! still is, the +subject of terrible disputes among grown-up people. If hereafter they +reach your ears, remember what I have told you now, viz., that the +pleasure lodged in the tongue and its surroundings, is a plaything, +but a plaything given to us by GOD; and that we must use it accordingly. + +If a little girl has had a plaything given to her by her mother, would +she think to please her by breaking it or throwing it into a corner? +No, certainly not: she would know that in so doing she would be going +directly against her mother's intentions and wishes. Nevertheless she +would amuse herself with it in play hours, with an easy conscience, +and, if she is amiable, she will remember while she does so, that it +comes to her from her mother, and will thank her at the bottom of her +heart. + +It is the same with man, of whose playthings we are speaking. + +But, moreover, this little girl (it is taken for granted that she is +a good little girl) will not make the plaything the business of her +whole day, the object of all her thoughts; she will not forget +everything for it, she will leave it unhesitatingly when her mamma +calls her. Neither will she wish to be alone in her enjoyments, but +will gladly see her little friends also enjoy similar playthings, +because she thinks that what is good for her must be good for others +too. + +It is thus that man should do with his playthings; but, alas! this is +what he does not by any means always do with them, and hence a great +deal has been said against them. Little girls, in particular, are apt +to fail on this point, and that is how the dreadful word _gluttony_ +came to be invented. For the same reason, also, people get punished +from time to time; such punishments being the consequence of the misuse +I speak of. + +If people who call to see your mamma were, instead of going straight +up stairs to her, to establish themselves at the lodge with the porter, +and stay there chatting with him, do you think she would be much +flattered by their visits? And yet this is exactly what people do who, +when eating, attend only to the porter. He is so pleasant, this porter; +he says such pretty things to you, that you go on talking to him just +as if he were the master of the house, who, meanwhile, has quite gone +out of your head. + +You heap sugar-plums upon sugar-plums, cakes upon cakes, sweetmeats +upon sweetmeats--everything that pleases the porter, but is of no use +whatever to the master of the house. And then what happens? The master +gets angry sometimes, and no wonder. Mr. Stomach grows weary of these +visits, which are of no use to him. He rings all the bells, makes no +end of a noise in the house, and forces that traitor of a porter who +has engrossed all his company, to do penance. You are ill--your mouth +is out of order--you have no appetite for anything. The mamma has taken +away the plaything which has been misused, and when she gives it back, +there must be great care taken not to do the same thing over again. + +I have thought it only right, my dear child, in telling you the history +of eating, to give to this little detail of its beginning, a place +proportioned to your interest in it. You see by what I have said, that +you are not altogether wrong in following your taste; but neither must +it be forgotten that this part of the business is not in reality the +most important; that a plaything is but a plaything, and that the +porter is not the master of the house. + +Now that we have made our good friend's acquaintance, we will wish him +farewell, and I will presently introduce you to his companions of the +antechamber, who are ranged on the two sides of the door, to make the +toilettes for the visitors who present themselves, and to put them in +order for being received in the drawing-room. You will see there some +jolly little fellows, who are also very useful in their way, and whose +history is no less curious. They are called TEETH. + + + +LETTER IV. + +THE TEETH. + +When you were quite little, my dear child, and still a nursling, you +had nothing behind your lips but two little rosy bars, which were of +no service for gnawing an apple, as they were not supplied with teeth. +You had no need of these then, since nothing but milk passed your lips, +neither had your nurse bargained for your having teeth to bite with. +You see that God provides for everything, as I have already said, and +shall often have occasion to point out to you. + +But by degrees the little infant grew into a great girl, and it became +necessary to think of giving her something more solid than milk to +eat; and for this purpose she required teeth. Then some little germs, +which had lain dormant, concealed within the jaws, awoke one after +another, like faithful workmen when they hear the striking of the +clock. Each set to work in his little cell, and with the help of some +phosphorus and some lime, it began to make itself a kind of white +armour, as hard as a stone, which grew larger from day to day. + +You know what lime is; that sort of white pulp which you have seen +standing in large troughs where the masons are building houses, andwhich +they use in making mortar; it is with this that your little +masons build your teeth. + +As to phosphorus, I am afraid you may never have seen any; but you may +have heard it spoken of. It is sold at the druggist's in the form of +little white sticks, about as thick as your finger; they have a +disagreeable, garlicky smell, and are obliged to be kept in jars of +water, because they seize every opportunity of taking fire; so I advise +you, if ever you do see any phosphorus, not to meddle with it--for in +burning, it sticks closely to the skin, and there is the greatest +difficulty in the world in extinguishing it, and the burns it makes +are fearful. I give you this caution, because phosphorus possesses a +very curious property, which might attract little girls. Wherever it +is rubbed, in the dark, on a door, or on a wall, it leaves a luminous +trail of a very peculiar appearance, which has been called +phosphorescent, from the name of the substance which produces it. And +in this way one can write on walls in letters of fire, to the terror +of cowards. Now, come; if you will promise to be very wise, and only +to make the experiment when your mamma is present, I will teach you +how to make phosphorescent lights without having to go to the +druggist's! There is a small quantity of phosphorus in lucifer matches, +which their garlicky smell proves. Rub them gently in the dark on a +bit of wood, and you will see a ray of light which will shine for some +moments. But mind, you must not play at that game when you are alone; +it is a dangerous amusement, and one hears every day of terrible +accidents caused by disobedient children playing with lucifer matches. +And while we are on the subject, let me warn you against putting them +into your mouth. Phosphorus is a poison, and such a powerful one that +people poison rats with bread-crumb balls in which it has been +introduced. + +"Oh dear me! and that poison makes part of our teeth?" + +Exactly so, and it even forms part of all our bones, and of the bones +of all animals; the best proof of which is, that the phosphorus of +lucifer matches has been procured out of bones from the slaughter-house. +One could make it from the teeth of little girls if one could get +enough of them. + +Now I see what puzzles you, and well it may. You are asking yourself +how those little tooth-makers, the gums, get hold of this terrible +phosphorus, which is set on fire by a mere nothing, and which we dare +not put into our mouths; where do they find the lime which I also +protest is not fit to eat, and yet of which we have stores from our +heads to our feet? + +It is very surprising, too, to think of its being forthcoming in the +jaws just when it is wanted there. + +You begin to perceive that there are many things to be learnt before +we come to the end of our history, and that we find ourselves checked +at every step; now listen, for we are coming to something very +important. + +In distant country-seats, where people are thrown entirely upon their +own resources, they must be provided beforehand with all that is +requisite for repairing the building; and there is, accordingly, a +person called a steward, who keeps everything under lock and key, and +distributes to the workmen whatever materials they may require. Thus, +the steward gives tiles to the slater, planks to the carpenter, colors +to the painter, lime and bricks to the mason--the very same lime that +we have in our teeth--in fact, he has got everything that can be wanted +in his storehouse, and it is to him that every one applies in time of +need. + +Now our body also is a mansion, and has its steward too. But what a +steward--how active! what a universal genius I how inefficient by +comparison are the stewards of the greatest lords! He goes, he comes, +he is everywhere at once; and this really, and not as we use the phrase +in speaking of a merely active man: for the _being everywhere at +once_ is in this case, a fact. He keeps everything, not in a +storehouse, but what is far better, in his very pockets, which he +empties by degrees as he goes about, distributing their contents without +ever making a mistake, without stopping, without delaying; and returns +to replenish his resources in a ceaseless, indefatigable course, which +never flags, night nor day. And you can form no idea how many workmen +he has under his orders, all laboring without intermission, all +requiring different things--not one of them pausing, even for a +joke!--not even to say--"Wait a moment;"--they do not understand what +waiting means: he must always keep giving, giving, giving. By and by +we shall have a long account to give of this wonderful steward, whose +name, be it known, if you have not already guessed it, is Blood. + +It is he who, one fine day when he was making his round of the jaws, +found those little germs I spoke of, awake and eager for work; and he +began at once to start them with materials. He knew that phosphorus +and lime were what they needed: he drew phosphorus and lime therefore +out of his pockets,--and, to be very exact, some other little matters +too,--but these were the most important; but I cannot stop to tell you +everything at once. + +Now, where did the blood obtain this phosphorus and lime? + +I expected you to ask this, but if you want everything explained as +we go along, we shall not get very far. In fact, if I answer all your +questions I shall be letting out my secret too soon, and telling you +the end of my story almost before it is begun. + +So be it, however; perhaps you will feel more courage to go on, when +you know where we are going. + +The steward of a country-house distributes tiles, planks, paint, bricks, +lime; but none of these things are his own, as you know; he has received +them from his master: and, in the same way, our steward has nothing +of his own: everything he distributes comes from the master of the +house, and as I have already told you, this master is the stomach. As +fast as the steward distributes, therefore, must the master renew the +stores--and renew them all, for unless he does this, the work would +stop. In proportion as the blood gives out on all sides the contents +of his pockets, the stomach must replenish them, and fill them with +everything necessary, or there would be a revolution in the house. +Now, as there can be nothing in the stomach but what has got into it +by the mouth, it behooves us to put into the mouth whatever is needed +for the supply of our numerous workmen; and this is why we eat. + +I perceive that I have plunged here into an explanation out of which +I shall not easily extricate myself, for I can guess what you are going +to say next. When you began to cut your teeth, you had eaten neither +phosphorus nor lime, as nothing but milk had entered your mouth. + +That is true. Neither then, nor since then, have you eaten those things, +and what is more, I hope you never will. And yet both must have got +into your mouth, for without them your teeth could never have grown. +How are we to get out of this puzzle? + +Suppose now, for a moment, that instead of phosphorus and lime, +thelittle workmen in your jaws had asked the blood for sugar to make the +teeth with. Fortunately this is only a supposition; otherwise I should +be in great fear for the poor teeth: they would not last very long. +Suppose, further, that instead of your eating the lump of sugar which +was destined to turn into a tooth, your mamma had melted it in a glass +of water, and had given it to you to drink; you could not say you had +eaten sugar, and yet the sugar would really have got into your stomach, +and there would be nothing very wonderful if the stomach had found it +out and given it to the blood, and the blood had carried it off to the +place where it was wanted. Now, allowing that the lump of sugar was +very small, and the glass of water very large, the sugar might have +passed without your perceiving it, and yet the tooth would have grown +all the same, and without the help of a miracle. + +And this is how it was. In the milk which you drank as a baby there +were both phosphorus and lime, though in very small quantities. There +were many other things besides; everything of course that the blood +required for the use of its work-people, because at that time the +stomach was only receiving milk, and yet all the work was going on as +usual. + +And therefore, my dear child, whenever in the course of our studies, +you hear me describe such and such a thing as being within us, say +quietly to yourself, "that also was in the milk which nourished me +when I was a baby." + +Of course, the same things are in what you eat now; only now they come +in a form more difficult to deal with, and the labor of detaching them +from the surrounding ingredients is much greater. The whole business +indeed of this famous machine which we are studying consists in +unfastening the links which hold things together, and in laying aside +what is useful, to be sent to the blood divested of the refuse. The +stomach was too feeble in your infancy to have encountered the work +it has to do now. It is for this reason that God devised for the benefit +of little children that excellent nourishment--milk--which contains, +all ready for use, every ingredient the blood wants; and is almost, +in fact, blood ready made. + +Only think, my child, what you owe to her who gave you this nourishment! +It was actually her blood she was giving you; her blood which entered +into your veins, and which wrought within you in the wonderful way +which I have been describing. Other people gave you sugar-plums, kisses, +and toys; but she gave you the teeth which crunched the sugar-plums, +the flesh of the rosy cheeks which got the kisses, and of the little +hands which handled the toys. If ever you can forget this, you are +ungrateful indeed! + +Now, beware of going on to ask me how we know that there are so many +sorts of things in milk, or I shall end by getting angry. Question +after question; why, you might drive me in this way to the end of the +world, and we should never reach the point we are aiming at. We have +already traveled far away from the teeth, concerning which I wanted +to talk to you at this time, but our lesson is nearly over and we have +scarcely said a word about them! One cannot learn everything at once. +Upon the point in question you must take my word; and as you may +believe, I would not run the risk of being contradicted before you, +by those who have authority on the subject. + +Let it suffice you, for to-day, to have gained some idea of the manner +in which the materials which constitute our bodies are manufactured +within us. We have got at this by talking of the teeth; to-morrow, it +may be the saliva, the next day something else. What I have now told +you will be of use all the way through, and I do not regret the time +we have given to the subject. If you have understood that well; the +time has not been lost. + + + +LETTER V. + +THE TEETH _(continued.)_ + +My thoughts return involuntarily to the subject I last explained to +you, my dear child, and I find that I have a great deal to say about +it still. + +You see now, I hope, that we have something else to consult besides +a dainty taste when we are eating; and that if we are to work to any +good purpose we must think a little about this poor blood; who has so +much to do, and who often finds himself so much at fault, when we send +him nothing but barley-sugar and biscuits for his support. It is not +with such stuff as that, as you may well imagine, that he can be enabled +to answer satisfactorily to the constant demands of his little workmen, +and we expose him to the risk of getting into disgrace with them, if +we furnish him with no better provisions. + +And who is the sufferer? Not I who am giving you this information, +most certainly. + +Now, when children hesitate about eating plain food, and fly from beef +to rush at dessert, they act as a man would do who should begin to +build by giving his workmen reeds instead of beams, and squares of +gingerbread instead of bricks. A pretty house he would have of +it;--just think! + +On the contrary, what your mother asks you to eat, my dear little +epicure, is sure to be something which contains the indispensable +supplies for which your blood is craving; for people knew all about +this by experience long before they could explain the why and the +wherefore. But now that you are so much better informed than even the +most learned men were a century ago, pouting and wry faces at table +are no longer excusable, and I should be sadly ashamed of you if I +should hear you continued to make them. + +And this is what I was more particularly thinking of just now, when +I took up my pen again. No doubt it is very amusing to be able to look +clearly into one's frame, and see what goes on inside, but the amusement +anything affords is the least important part of it; you have begun to +find this out already, and you will find it out more and more every +day. What seems to me one of the great advantages of the study we have +begun together is, that at every step you take you will meet with the +most practical and useful instruction, as well as the most unanswerable +reasons for doing what your parents ask you to do every day. + +To obey without knowing why is certainly possible, and may be done +happily enough. But we obey more readily and easily when we understand +the reason for doing so; and a duty which one can satisfy oneself +about, forces itself upon one as a sort of necessity. And what can +throw a stronger light on our duties than a thorough acquaintance with +ourselves? + +It is upwards of two thousand two hundred years ago (and that is not +yesterday, you must own!) since one of the greatest minds of the +world--Socrates--never forget that name--taught his disciples, as a +foundation precept, this apparently simple maxim, "Know thyself." He +meant this, it is true, in a much higher sense than we are aiming at +in these conversations of ours, but his rule is so practical, that +although you have only as yet taken a mere peep into one small corner +of self-knowledge, you find, if I am not much mistaken, that your heart +has beaten once or twice rather faster than it did before. Was I wrong, +in saying from the beginning, that we become better as we grow in +knowledge? Is it not true that you have felt more tenderly than ever +towards her who nourished you with her milk, since I explained to you +the value of milk; and that you have kissed your mother's hand all the +more lovingly since you heard my history of the hand? To tell you the +truth, if you had not done so, I should have been dissatisfied both +with you and myself. + +And wait! While we are talking thus, another thought has come into my +head about hands and nurses, which I must tell you of. + +There is something of the nurse, my child, in those who take the best +fruits of their intellect and heart, and transform them, as it were, +into milk, in order that your infant soul may receive a nourishment +it will be able to digest without too much effort. In this way their +very soul enters into you, and it is but fair that you should reward +them as they deserve. Young as you are, too, you have a recompense in +your power: one more acceptable even than Academic prizes--of which +it is indispensable not to be too avaricious--you can give them your +love. + +Besides, it is not only hands but heads that are at work for you, and +of these many more than you suppose; and your debt of gratitude is as +much due to the one as to the other. + +Perhaps my first letter may have led you to suppose that I was inclined +to laugh at what I called learned men; and they are perhaps a little +to blame for not thinking often enough about little girls; but +nevertheless these men are of the greatest use to them in an indirect +way. You owe them much, therefore, and without them could have known +nothing of what I am teaching you. It is very grand for us, is it not, +to know that there is phosphorus and lime in our teeth? But it took +generations of learned men, and investigations and discoveries without +end, and ages of laborious study, to extract from nature this secret +which you have learnt in five minutes. And whatever others you may +learn hereafter, remember that it is the same story with all. While +profiting, therefore, at your ease, by all these conquests of science, +I would have you hold in grateful recollection those who have gained +them at so much cost to themselves: almost always at the expense of +their fortune, sometimes at the peril of their lives. + +There they are, observe, a little knot of men with no sort of outward +pretension. They speak a language which scares children away. They +weigh dirty little powders in apothecaries' scales; steep sheets of +copper in acid-water; and watch air-bubbles passing through bent glass +tubes, some of which are as dangerous as cannon balls. They scrape old +bones, and slice scraps no bigger than a pin's head. They keep theireyes +fixed for hours upon things they are examining through microscopes +of a dozen glasses, and when you go to see what they are looking at, +you find nothing at all. To see them at work, in what they call their +laboratories, you would say that they were a set of madmen. But at the +end, it is found, some fine day, that they have changed the face of +the earth; have worked revolutions before which emperors and kings bow +in respect; have enriched nations by millions at a time; have revealed +to the human race, divine laws of which it had hitherto been ignorant; +finally, have furnished the means of teaching little boys and girls +some very curious things, which will make them more agreeable as well +as reasonable. And this is a benefit not to be despised, since these +children are destined one day to become fathers and mothers, and so +to govern the next generation; and the better they themselves are +instructed, the better this will be done. + +But now let us go back to the poor teeth, whom we seem to have forgotten +altogether. However, we knew very well that they would not run away +meantime. + +I told you before that it was their business to dress and prepare +whatever was presented to them, but the reception they bestow is not +one which would suit every body's taste, for it consists in being made +mince-meat of And in order to do their work in the best way possible +they divide their labor; some cut up, others tear, and others pound. + +First, there are those flat teeth in front of the two jaws, just below +the nose. Touch yours with the tip of your finger; you will find that +they terminate in sharp-edged blades, like knives. These are called +_incisors,_ from the Latin word _incidere,_ which means to cut, and it +is with them we bite bread and apples, where the first business is to +cut. It is with the same teeth that lazy little girls bite their thread, +when they will not take the trouble to find their scissors; and, by the +by, this is a very bad trick, because by rubbing them one against +another in this manner we wear them out, and, as you will soon discover, +worn-out teeth never grow again. + +The next sort are those little pointed teeth, which come after the +_incisors,_ on each side of both jaws. You will easily find them; +and if you press against them a little, you will feel their points. +If we call the first set the knives of the mouth, we may call these +its forks. They serve to pierce whatever requires to be torn, and they +are called _canine_ teeth, from the Latin word _canis_, a dog, because +dogs make great use of them in tearing their food. They place their paws +upon it, and plunging the canine teeth into it, pull off pieces by a +jerk of the head. Look into the mouth of papa's dog: you will recognize +these teeth by their rather curved points. They are longer than the +rest, and are called fangs. I do not know, after all, why they have +chosen to name these teeth _canine_, as all carnivorous animals have the +same fangs, and in the lion, the tiger, and many other species, they are +much more developed and sharper than in the dog. In cats they are like +little nails. However, the name is given, and we cannot alter it. + +The last teeth, which are placed at the back of the jaw, are called +molars, from the Latin word _mola_, which means a millstone. + +You must be prepared to meet with several Latin words as we go on; but +never mind; this will give you the opportunity of learning a little +Latin, and so of keeping your brother in order, if he ever looks down +upon you because he is learning Latin at school. Formerly, all learned +men wrote in Latin, and as they ruled supreme in all such subjects as +those we are discussing, they gave to everything such names as they +pleased, without consulting the public, who did not just then trouble +their heads about the matter. Now they give Greek names, which can +hardly be called an improvement; but if they ever wish to attract the +attention of little girls they must translate their hard words into +our own language. + +To return to our grinders: they perform the same office as a miller's +millstone; that is to say, they grind everything that comes in their +way. These teeth have flat, square tops, with little inequalities on +the surface, which you can feel the moment you lay your finger on them. +These are the largest and strongest of the three sets, and with them +we even crack nuts, when we prefer the risk of breaking our teeth to +the trouble of looking for the nut-crackers! + +Now, I will answer for it that you cannot explain to me why we always +place what is hard to break between the _molars,_ and never employ +the _incisors_ in the work? And yet everybody does this alike--from +the child to the grown-up man--and all equally without thinking of +what they are doing. + +I will tell you the reason, however, if you will first tell me why, +when you are going to snip off the tip of your thread (which offers +very little resistance), you do it with the point of your scissors; +whereas you put any tough thing which is likely to resist strongly (a +match, for instance) close up to their hinge; particularly if you have +no scruple about spoiling the scissors, by the way! + +If you were a grown-up lad, and I were teaching you natural philosophy, +I should have here a fine opportunity for explaining what is called +_the theory of the lever_. But I think _the theory of the lever_ would +frighten you; so we must get out of the difficulty in some other way. + +I find, however, that I have been joking so much as I went along, that +I have but little space left, and feel quite ashamed of myself. We +seem quite unlucky over these teeth. + +I have already been scolded by people who are not altogether wrong in +accusing me of losing my time in chattering, first of one thing and +then of another. They complain that by thus nibbling at every blade +of grass on the way-side we shall never get to the end of our journey; +and there is some truth in what they say. Still, I will whisper to you +in excuse that I thought we might play truant a little bit while we +were on familiar ground, where naturally you were sure to feel a +particular interest in everything. The hand, the tongue, the +teeth--these are all old friends of yours--and I thought you would +like to hear all about them. By-and-bye we shall be in the little black +hole, and then we shall get on much more rapidly. + + + +LETTER VI. + +THE TEETH _(continued)._ + +I left off at the _molars_, which are the teeth one selects to +crack nuts with; and if I remember rightly, we talked about different +ways of cutting with scissors. + +Let us look at the subject from a distance, that we may understand it +more clearly. Let us imagine a horse drawing a heavy cart slowly along. +Ask it to gallop, and it will answer, "With all my heart! but you must +give me a lighter carriage to draw." And now fancy another flying over +the ground with a gig behind it. Ask it to exchange the gig for the +cart, and it will say, "Yes; but then I shall have to go slowly." + +Whereby you see that with the same amount of strength to work with, +one has the choice of two things: either of conquering a great +resistance slowly, or a slight one quickly. + +And it is partly on this account, dear child, that I teach you so +gradually; for young heads, fresh to the work, are less easily drawn +along than others, and have but a certain amount of strength. + +Hitherto all has been clear as the day. Now take your scissors in your +left hand; hold the lower ring of the handle firmly between your thumb +and closed hand, so that the blade shall remain straight and immovable: +then with your other hand cause the upper ring to go up and down, and +watch the blade as it moves. The whole of it moves at once, and is put +in motion by the same power--viz., your right hand. But the point makes +a long circuit in the air, while the hinge end makes only a very little +one--indeed, moves almost imperceptibly: and, as you may imagine, a +different sort of effort is required from the motive power (your hand) +according as resistance is made at the point or at the hinge. The point +goes full gallop: it is the horse in the gig; the light work is for +him. The hinge moves slowly; it is the cart-horse, and takes the heavy +labor. + +I hope I have made you understand this, for it explains the cracking +of our nut, though you may not suspect it. Move your scissors once +more in the same way. Now, you have before you the pattern of the two +jaws on one side of your face, from the ear to the nose; the upper +one, which never moves (as you may convince yourself by placing a +finger on your upper lip when you either speak or eat), and the lower +one which goes up and down. Two pairs of scissors set points to points +give you the whole jaw. The _incisors_ are at the points, they +gallop up and down, and are worthless for doing hard work; the +_molars_ are at the hinges, and move slowly; and if anything tough +has to be dealt with, it comes to them as a matter of course; hence +they are the nutcrackers. You must own that it is pleasant to reflect +thus upon what we are doing every day, and the next time you see a +stonemason moving stones of twenty times his own weight with his iron +bar, ask your papa to explain to you the principle of the lever. After +what I have told you, you will understand it very readily, or at least +enough of it to satisfy your mind. + +But, besides this power of moving up and down, the lower jaw possesses +another less obvious one, by means of which it goes from right to left. +This is precisely what naughty children make use of when they grind +their teeth: not that I mean this remark for you, for I have a better +opinion of you than to suppose you do such things. Those who make such +bad use of their jaws deserve to lose the power of ever moving them +thus, and then they would find themselves sadly at a loss how to chew +their bread--for their _molars_ would be of but little service +to them in such a case; as it is chiefly by this second action of the +jaw that the food is pounded. Try to chew a bit of bread by only moving +your jaw up and down, and you will soon tire of the attempt. + +One word more to complete my description of the teeth: that portion +of them which is in the jaw is called the _root_; and the _incisors_, +which cannot work hard because, like the gig-horses, they have but +little resisting power, possess only small and short roots; whereas the +_canines,_ whose duty it is to tear the food sideways, would run the +risk of being dragged out and left sticking in the substances they are +at work upon, if they were not well secured; these, therefore, have +roots which go much deeper into the jaw, and in consequence of this they +give us more pain than the others when the dentist extracts them: those +famous _eye-teeth_, which so terrify people on such occasions, are the +_canines_ of the upper jaw, and lie, in fact, just below the eye. + +The _molars_ meanwhile would be in danger of being shaken in the +sideway movement, while chewing: so they do as you would do if you +were pushed aside. Now you would throw out your feet right and left +in order to steady yourself, and thus the molars, which have always +two roots, throw them out right and left for the same purpose. Some +have three, some four, and they require no less for the business they +have to do. + +Above the root comes what is called the crown; that is the part of the +tooth which is exposed to the air; the part which does the work, and +which bears the brunt of all the rubbing. Now, however hard it may be, +it would soon end in being worn out by all this fun if it were not +covered by a still harder substance, which is called _enamel_. +The _enamel_ which forms the coating of china plates, and which +you can easily distinguish by examining a broken plate, will give you +a very exact idea of it. It is this enamel which gives the teeth the +polish and brilliancy we so much admire, and it is desirable to be +very careful of it, not out of vanity, though there is no objection +to a little vanity on the subject, but because the enamel is +the protector of the teeth, and when that is destroyed, you may say +good-bye to the teeth themselves. All acids eat into the enamel, as +vinegar or lemon-juice does into marble; and one of the best means of +preserving this protecting armor of the teeth is never to eat the unripe +windfalls of fruit, which I have seen unreasonable children pick up in +orchards and devour so recklessly. They give sufficient warning, by +their acidity, that they are not fit for food, and when this warning is +neglected, they take their revenge by corroding the enamel of the +teeth; not to speak of the disturbance which they afterwards cause in +the poor stomach. + +I said that without this coating of enamel, the teeth would be +prematurely worn out, the reason of which is, that the teeth have not +the property of growing again, as the nails and hair have. When those +little germs of which I spoke when we began to describe the teeth, +have finished their work, they perish and fall out, like masons who, +when they have built the house, take their departure forever. + +But the "forever" wants explanation. For such stern conditions would +fall hard on very little children, who, not having come to their reason, +cannot be expected to understand the great value of their teeth, and +take all the care they need of them. So to them _a second_ chance +is given. + +Your first teeth, the _milk-teeth_, as they are called, count for +nothing: they are a kind of specimen, just to serve while you are very +young. + +When you are approaching what is called the age of reason, (and this +word implies a great deal, my dear child,) the real teeth, the teeth +which are to serve you for life, begin to whisper among themselves, +"Now, here is a little girl who is becoming reasonable, and who will +soon, or else never, be fit to take charge of her teeth." No sooner +said than done: other masons set to work in other cells, placed under +the first set, and as the permanent teeth keep growing and growing, +they gradually push out the milk-teeth, which were only keeping their +places ready for them till they came. + +This is just your case at present, and you now understand your +responsibility, and how necessary it is to preserve those good teeth +which have placed so generous a confidence in your care of them, and +which, once gone, can never be replaced. + +You have no loss by the exchange; you had twenty-four at first, you +will now have twenty-eight. Twenty-eight, did I say? nay, you will +have thirty-two; but the last four will come later still. The last +_molars_ on each side, above and below, in both jaws, will not +make their appearance till you are grown up. They are a fastidious and +timid set, and will not run any risks; and they are called +_wisdom-teeth_, because they do not appear till we are supposed +to have arrived at years of discretion. Some people do not cut them +before they are thirty, and you will agree that, if they have not +become wise by that time, they have but a very poor chance of ever +being so! + +There is much more still to be said about the teeth; but I think I +have told you quite enough to teach you the importance of these little +bony possessions of yours, which children do not always value as they +deserve, and whose safety they endanger as carelessly as if they had +fresh supplies of them ready in their pockets. If so many skilful +contrivances have been devised for enabling us to masticate our food +properly, it is clear that this process is not an unimportant one. +Those, therefore, who swallow a mouthful after two or three turns, +forget that they are thereby forcing the stomach to do the work the +teeth have neglected to do, and this is very bad economy, I can assure +you. You will see hereafter, when we speak about animals, that by a +marvellous compensation of nature, the power of the stomach is always +great in proportion to the _in_efficiency of the teeth, and that +by the same rule, it is weakest when the jaws are best furnished. Now, +no jaw is more completely furnished than the human one; it is clear, +then, that it should do its own work and not leave it to be done by +those who are less able: and the little girl who, in order to finish +her dinner more quickly, shirks the use of her teeth, and sends food, +half chewed, into her stomach, is like a man who, having two servants, +the one strong and vigorous, the other feeble and delicate, allows the +first to dawdle at his ease, and puts all the hard work on the other. +He would be very unjust in so doing, would he not? And as injustice +always meets with its reward, his work is sure to be badly done. + +Now, the work in question consists in reducing what we eat into a sort +of pulp or liquid paste, from which the blood extracts at last whatever +it requires. But the teeth may bite and tear the materials as they +please, they can make nothing of them but a powder, which would never +turn into a pulp, if during their labors they were not assisted by an +indispensable auxiliary. To make pap for infants what do we add to the +bread after it is cut in little bits? Without being a very clever cook, +you will know that it is water which is wanted. And thus, to assist +us in making pap for the blood, Providence has furnished us with a +number of small spongy organs within the mouth, which are always filled +with water. These are called _salivary glands_. This water oozes +out from them of itself, on the least movement of the jaw, which presses +upon the sponges as it goes up and down. The name of this water, as +I need scarcely tell you, is _saliva_. + +When I call it water, it is not merely from its resemblance; _saliva_ is +really pure water with a little _albumen_ added. Do not be afraid of +that word--it is not so alarming as it appears to be. It means simply +the substance you know as the _white of egg_. There is also a little +soda in the water, which you know is one of the ingredients of which +soap is made. And this explains why the saliva becomes frothy, when the +cheeks and tongue set it in motion in the mouth while we are talking; +just as the whites of egg, or soapy water, become frothy when whipped up +or beaten in a basin. + +But the albumen and the soda have not been added to the saliva, in our +case, merely to make it frothy; that would have been of very little +use. They give to the water a greater power to dissolve the food into +paste, and thus to begin that series of transformations by which it +gradually becomes the fine red blood which shows itself in little drops +at the tip of your finger when you have been using your needle +awkwardly. + +When once minced up by the teeth and moistened by the saliva, the food +is reduced to a state of pulp, and having nothing further to do in the +mouth, is ready to pass forward. But getting out of the mouth on its +journey downwards is not so simple an affair as getting into it by the +_front door_, as it did at first. Swallowing is in fact a complicated +action, and not to be explained in half a dozen words, and I think we +have already chatted enough for to-day. I only wish I may not have tired +you out with these interminable teeth! But you may expect something +quite new when I begin again. + + + +LETTER VII. + +THE THROAT. + +You remember a certain door-keeper, or porter, of whom we have already +spoken a good deal, who resides in the mouth--the sense of taste, I +mean? + +Well, it is a porter's business to sweep out the entrance to a house, +and you may always recognize him in the courtyard by his broom. + +And accordingly our porter too has a broom specially placed at his +service, namely, the tongue; and an unrivalled broom it is--for it is +self-acting, never wears out, and makes no dust--qualities we cannot +succeed in obtaining in any brooms of our own manufacture. + +When the time has come for the pounded mouthful (described in the last +chapter) to travel forward (the teeth having properly prepared it), +the broom begins its work; scouring all along the gums, twisting and +turning right and left, backwards and forwards, up and down; picking +up the least grains of the pulp which have been manufactured in the +mouth; and as the heap increases, it makes itself into a shovel--another +accomplishment one would scarcely have expected it to possess. What +it gathers together thus, rolls by degrees on its surface into a ball, +which at last finds itself fixed between the palate and the tongue in +such a manner that it cannot escape; at which moment the tongue presses +its tip against the upper front teeth, forms of itself an inclined +plane, and--but stop! we are getting on too fast. + +At the back of the mouth, (which is the antechamber, as we said before,) +is a sort of lobby, separated from the mouth by a little fleshy +tongue_let_, suspended to the palate, exactly like those tapestry +curtains which are sometimes hung between two rooms, under which one +is enabled to pass, by just lifting them up. + +If this lobby led only from the mouth to the stomach, the act of +swallowing would be the simplest thing in the world; the tongue would +be raised, the pounded ball would glide on, would pass under the +curtain, and then good-bye to it. Unfortunately, however, the architect +of the house seems to have economized his construction-apparatus here. +The lobby serves two purposes; it is the passage from the mouth to the +stomach, as well as from the nose to the lungs. + +The air we breathe has its two separate doors there--one opening +towards the nose, the other towards the lungs; through neither of which +is any sort of food allowed to pass. But, as you may imagine, the food +itself knows nothing of such spiteful restraints, and it is a matter +of perfect indifference to it through which of the doors it passes. +Not unlike a good many children who, though they are reasonable +creatures, will push their way into places where they have been +forbidden to go; and who can expect a pulpy food-ball to be more +reasonable than a child? It was necessary, therefore, so to arrange +matters that there should be no choice on the subject; that when the +food-ball got into the lobby it should find no door open but its own, +namely, that which led to the stomach. And that is exactly what is +done. + +You have not, perhaps, remarked that in the act of swallowing, something +rises and contracts itself at the same moment in your throat, producing +a kind of internal convulsion which jerks whatever is inside. People +do not think about it when they are eating, because it is an involuntary +action, and their attention is otherwise engaged. + +But try to swallow when there is nothing in your mouth, and you will +perceive what I mean at once. + +Now, imagine our lobby at the back of the throat as a small closet, +with a doorway in its wall, half-way up, the doorway being closed by +a curtain. In the ceiling is a hole, which leads to the nose; in the +floor two large tubes open out; the front one leading to the lungs, +the one behind, to the stomach. + +Now swallow, and I will tell you what happens. The curtain rises up +and clings to the ceiling, and thus the passage to the nose is stopped +up. The lung-tube rises along the wall, and hides itself under the +door, contracting itself, and making itself quite small, as if it +wished to leave plenty of room for the mouthful of food which is about +to pass over it; and, for still greater security, at the very moment +it rises, it pushes against a small trap-door which shuts up its mouth. +No other road remains, therefore, but through the tube which leads to +the stomach; the pulpy mouthful drops straight therein, without risk +of mistake, and when it is once there, everything readjusts itself as +before. + +These are very ingenious contrivances, and I will venture to say that +if we would but study the wonders of the marvellous and varied machinery +which is constantly at work in our behalf within us, we should be much +better employed than in learning things from which no practical good +can be derived. Moreover, we should be ashamed to trust, like the lower +animals, only to our instinct, (which, after all, is much less developed +in us than in them,) for blindly escaping the thousand chances of +destruction that beset a structure so fragile and delicate in its +contrivances as the human body. Besides, it is not only our own +machinery that is entrusted to us, we are liable to be responsible for +that of others, whose development it is our duty to guard and watch; +and how can we do this with a safe conscience, if we are ignorant of +the construction, the action, the laws of all sorts which the great +Artificer has, so to speak, made use of in forming our bodies? + +When you, in your turn, are a mother, you dear little rogue, who sit +there opening wide your bright eyes, and not comprehending a word of +what I am saying, you will be glad that you were taught when you were +little, how your own little girl ought to be managed. You will find +a hundred opportunities of making good use, in her behalf, of what you +and I are learning together, and in the meantime there is no reason +why you should not yourself profit by the knowledge you have gained. + +I am quite sure, for instance, that in repeating to your child the +simple rule of politeness, with which everybody is acquainted, "_Never +talk when you are eating_," you will be very careful to add, "_and +especially when you are swallowing_," for reasons I am about to detail. + +When we want to speak we have to drive the air from the lungs into the +mouth, and our words are sounds produced by this air as it passes +through. This is the reason why I advise you to go on gently, and make +the proper stops in reading aloud: to _take breath_, in fact, as +it is called; otherwise, breath would all at once fail you, and you +would be obliged to stop short in the middle of a sentence and wait +like a simpleton till you had refilled the lungs with air by breathing. +It was for this purpose, also, and not for mere economy's sake, as you +may have thought, that the little cross-road of four doors has been +placed at the back of the mouth, enabling it to communicate at pleasure +with either the lungs or the stomach. It is a dangerous passage for +food-parcels making their way to the stomach; but if you could +substitute for it, as it may have occurred to you to do lately, a +simple tube going directly to the stomach,--behold! you would find +yourself dumb;--a serious misfortune, eh? for a little girl! But come, +I am quizzing too much, so console yourself. I know many grown-up +people who would be at least as sorry as yourself. + +To return to our subject. We have said that, in order to guard against +accidents, the lung-tube is closed at the moment we are about to +swallow. But if by any unlucky chance the air is coming up from the +lungs at the same moment, it must have a free passage. Its tube cannot +help returning to its place; the little trap-door which shuts up the +opening opens whether or no, and then adieu to all the precautions of +good Mother Nature! The mouthful when it drops, falls outside of its +proper tube--that is to say, into the other, which is exactly in front +of it, and we find that we have _swallowed the wrong way_. + +You know what happens in such a case. You cough and cough till you are +torn to pieces, till you grow scarlet, or even blue in the face; till +you lose your breath; till your body trembles; till your eyes start +out of their sockets. Let who will be there, there is no resource but +to hide your face in your handkerchief. The tube, which was only made +for the passage of air, on finding an intruder forcing an entrance, +does its utmost to drive it back through the door. Then the lungs, +which would be destroyed by its getting to them, come to the assistance +of the faithful servant who is struggling for their protection: they +agitate themselves violently, and send forth gusts of air which drive +all before them. Thence arises the cough, and by this means at last +the enemy is thrust out of the mouth, like dust before the wind. And +it is only when the passages are cleared that the storm subsides. But +the commotion is no laughing matter, I assure you; for if one had +swallowed a little _too far_ the wrong way, or if the substance +swallowed had been too heavy for the air-tube, aided by the lungs, to +eject within a certain time, death would have ensued: instances of +which are by no means unknown. Nature does nothing in vain; this is +no case of a man frightened by a mouse. When you find your whole being +concentrating its efforts to one point, and betraying such distress, +at an accident apparently so trifling, you may be sure there is danger, +and real danger too; and if you doubt it, that makes no +difference--happily for you. + +Now you have learned why little girls should not attempt to talk and +swallow at the same time, and, I may add, still less laugh; for +laughingis a kind of somersault, performed by the lungs, and is always +accompanied by the ejectment of a great deal more breath than is +necessary in speaking, so that the jerks it occasions derange still +more the wise provisions made to protect life whenever we swallow +anything, and therefore we are more apt to swallow the wrong way while +laughing than while speaking. + +Need I say that we ought equally to guard against making others laugh +or talk; or exciting, or frightening them, while they are swallowing; +in short, avoid doing anything to create a sudden shock which might +suddenly force the air out of their lungs, and cause them in the same +manner to swallow the wrong way? Politeness requires this from us, and +what I have now said will fix the lesson still more strongly on your +mind. What would become of you if you were to see a person die in your +presence in consequence of some foolish joke, however apparently +innocent? + +Not to conclude with so painful a picture, I will, before we part, +give you the right names of the _curtain_, the _lobby_ or _closet_, and +the _tubes_ of which we have been speaking. + +The curtain is called the _Soft Palate_. + +The lobby, the _Pharynx_. + +The tube which leads to the stomach, the _Aesophagus_. + +The tube leading to the lungs, the _Larynx_. + +The opening of this tube is the _Glottis_, and the little trap-door +which closes it when one swallows, is the _Epiglottis_. + +You must excuse my attempting to explain the meanings of all these +names; it would take me too long to do so. After all, the mere names +are nothing. If I have succeeded in making you understand how all the +different parts act, you may call them what you like. + +Here we will rest. We are now on our way to where we shall see the +large apartments, and be introduced to the master, that head of the +house, whom no one can approach without so many ceremonies. + + + +LETTER VIII. + +THE STOMACH. + +Once in the _oesophagus_ (you remember this is the name of the tube +which leads to the stomach), the mouthful of food has nothing to do but +to proceed on its way. All along this tube there is a succession +of small elastic rings, [Footnote: Properly, _contractile circular +fibres_.] which contract behind the food to force it forward, and +widen before it to give it free passage. They thus propel it forward, +one after another, till it reaches the entrance to the stomach, into +which the last ring pushes it, closing upon it at the same time. + +Have you ever observed a worm or a leech in motion? You see a successive +swelling up of the whole surface of its body, as the creature gradually +pushes forward, just as if there was something in its inside rolling +along from the tail to the head. Such is precisely the appearance which +the _oesophagus_ would present to you, as the food passes down it, if +you had the opportunity of seeing it in action; and this has been called +_the vermicular movement_, in consequence of its resemblance to the +movement of a worm. + +Here I wish to draw your attention to the very important fact, that +this movement is in one respect of a quite different nature from that +of your thumb when you take hold of a bit of bread, or that of your +jaw when you bite with your teeth, or of your tongue, &c., when you +swallow. All these actions belong to yourself, to a certain extent; +they are voluntary, and under your own guidance; that is, you may +perform them or not, as you choose. There is a constant connexion +between you and them, and you knew what I meant at once as I named +each of them in succession. But in speaking of this other movement we +enter upon another world, of which you know nothing. Here is the black +hole of which I spoke. The little rings of the _oesophagus_ perform +their work by themselves, and you have no power in the matter. Not +only do they move independently of you, but were you to take it into +your head to stop them, it would be about as wise a proceeding as if +you were to talk to them. We will speak hereafter, in another place, +of these impertinent servants, who do not recognise your authority, +and with whom we shall have constantly to do, throughout what remains +to be said on the subject of eating. The truth is, your body is like +a little kingdom, of which you have to be the queen, but queen of the +frontiers only. The arms, the legs, the lips, the eyelids, all the +exterior parts, are your very humble servants; at your slightest bidding +they move or keep still: your will is their law. But in the interior +you are quite unknown. There, there is a little republic to itself, +ruling itself independently of your orders, which it would laugh at, +if you attempted to issue them. + +This republic, to make use of another metaphor, is the kitchen of the +body. It is there they make blood, as they know how; putting it to all +sorts of uses for your advantage, it is true, but without your consent. +You are in the position of the lady of a house whose servants have +shut the door of the kitchen in her face that they may carry on their +business after their own fashion, leaving only the housemaid and +coachman at her command. It may be humiliating, perhaps, to be thus +only partially mistress at home; but what can you do, my little +demi-queen? I will tell you: make up your mind to govern the subjects +under your orders as wisely as possible; and, as to the rest, be content +with the only resource left you: viz., that of looking in at the window +of the kitchen to see what goes on there! + +The stomach is the head cook: the president of the internal republic. +He has charge of the stoves; the whole weight of affairs is on his +hands, and he provides for the interests of all. Aesop taught us this, +long ago, in his fable of "The Belly and Members." [Footnote: La +Fontaine's translation is quoted in the French original, where the +name of the fable is "_Messer Gaster_," a more correct title than our +own. _Gaster_ is a Greek word signifying stomach; and it is strictly +_the stomach_ which is _meant_ in the fable. From this comes, too, the +medical term _gastritis_, the name of a disease of the stomach.--TR.] It +is a very good fable, and was wisely appealed to once by a Roman Consul +to appease a disturbance in the State. But the application was not quite +fair in one respect; and since I have started the subject, I will +satisfy myself by explaining to you where it was wrong. The time will +not be wasted, for this fable has furnished information to a great many +people about the economy of their insides, and possibly to you; and I +should like you to know the exact truth of all the particulars alluded +to. Whether Aesop understood them all, I cannot pretend to say; but the +application by the old Roman to the quarrel between the big-wig senators +and the people was on one point decidedly unjust; for there was, as far +as facts are concerned, something to be said on behalf of the stomach, +which Consul Menenius seems not to have thought of. + +When you come to this part of the Roman history you will learn that +the Roman Senate was a large and fat stomach, which did, it is true, +furnish good nourishment to the other members of the State, but kept +the best share for itself. We may say this now without risk of offence, +it having been dead for so long a time. Our stomach is the leanest, +slightest, frailest part of our body. It is master in the sense in +which it is said in the Gospel, "Let him that is first among you be +the servant of the others." It receives everything, but it gives +everything back, and keeps nothing, or almost nothing, for itself. +Between ourselves, Consul Menenius, the advocate of the Senate, had +no business to talk to the poor wretches at Rome of any comparison +between their government and so careful an administrator of the public +good as a human stomach. He should have taken his subject of comparison +from the families of geese or ducks--animals which have no teeth. These +have strong, well-grown stomachs--true Roman senators--whose stoutness +is in proportion to the work given them to do. But man provides his +with work already prepared by chewing, supposing him to have had the +sense to chew it, of course. It was not from a comparison with man, +therefore, that Menenius ought to have got his boasted apologue, which +was but a poor jest on the subject. + +You did not expect, my dear, to come in for a lesson on Roman History +in a discussion on the stomach. But the study of nature is connected +with everything else, though without appearing to be so, and I was not +sorry to give you, incidentally, this proof of the unexpected light +which it throws, as we go along, upon a thousand questions which appear +perfectly foreign to it. Look, for example, at this old fable cited +by Menenius. For the two thousand years and upwards that it has been +in circulation, troops of historians, poets, orators, and writers of +all kinds, have passed it forward from one to the other, without having +troubled themselves to investigate the laws of nature in connection +with the stomach; therefore, not one, that I am aware of, has observed +this small error, so trifling in appearance, so important in reality, +which nevertheless is obvious to the first young naturalist who thinks +the matter over. + +But enough of the Romans. Let us return to our master--the head cook, +if you choose to call him so. + +I was telling you just now that he managed the stoves, and you may +have thought that I was merely using similes, as I am apt to do. But +not so: it is quite true that he cooks; and so now tell me, if you +can, whence he gets his fire to cook with, or rather, to speak more +correctly, who gives it to him? + +Now you are quite puzzled, so I must help you out. + +In the mansion we were talking about some time ago, to whom would anyone +who wanted to light a fire, apply for wood? + +I think you can answer this yourself, for you cannot have forgotten +our famous steward, who gives everything to everybody. But, you will +wonder, I dare say, how the blood can carry wood in his pockets. +Wood? Ay, and real wood too, as we shall soon see: but it is not wood +we are talking about now. The blood has something more to the purpose +than wood in his pockets, for he has heat ready made. So when the +stomach wishes to set to work, it appeals to the blood, which comes +running from all parts of the body, and heats it so effectually that +everything within is really and actually cooked. This is why one feels +a sort of slight shudder down the back when the stomach has a great +deal to do at once, for the blood being called for in a hurry, comes +rushing along in great gushes, and carries with it the heat from the +other parts of the body. + +It is for this reason, too, that it is so dangerous to bathe when the +stomach is at work cooking, because the cold of the water drives +suddenly back all the blood which has accumulated around the little +saucepan, and this causes such a shock in the body that people often +die of it. + +Do not ask me, to-day, where this heat of the blood comes from; we +will speak of that hereafter. But I may tell you at once that our dear +steward is not a bit cleverer in this matter than other people, and +obtains his heat, like the humblest mortal, by burning his wood. Do +not puzzle yourself to find out how. Enough that he burns it as we do, +and by a similar process. + +Well, in one way or another, the master cook has his fire at command. +You know also, already, what it is he has to get cooked; namely, the +pulpy stew, which has begun in the mouth by chewing, and which it is +his business now to finish perfectly. Now see what a cook does who has +got her stew over the fire. She turns and turns it again and again, +and shakes the saucepan from time to time, that the ingredients may +be more thoroughly mixed up together; and this is precisely what is +done by the stomach; for all the time that the cooking is going on, +he swells and contracts himself alternately, after the fashion of those +rings of the _oesophagus_ we were talking about, tossing and tumbling +the food from one side to another, so as to knead it, as it were. + +Again, the cook adds water to her stew from time to time to keep it +moist; and so the stomach pours constantly upon his stew a liquid, +which contains a great deal of water, and which flows in from a quantity +of little holes, sunk in his delicate coats. + +What more? + +The cook puts in a little salt: and this the stomach takes care not +to forget either, for he is a cook who understands his business. In +the liquid of which I am speaking, there is, if not exactly salt as +one sees it at table, at all events the most active part of salt, that +which possesses in the highest degree the property of reducing +everything we eat to a paste; and this is the real reason why we find +all food so insipid which has not been seasoned with salt. As salt +contains a principle essential to the work to be done by the stomach, +some method had to be devised to induce us to provide him with it, and +this method the porter up above has hit upon. He makes a face if we +offer him anything without a little salt on it, as much as to say--"How +can you expect them to cook you properly down below, my good friend, +if you don't bring them proper materials?" + +Upon which hint men have always acted from the beginning; and as far +as we can trace history back, we find them mixing salt with their food, +though without knowing the real reason why. It is the same, too, with +the lower animals. They know nothing of the matter either, but this +does not prevent their having a natural relish for salt, as any one +will tell you who has the charge of cattle; for their stomachs require +for their cooking the very same seasoning as our own, and therefore +their porter above has received the same orders. + +Salt is not the only thing, however, that exists in that liquid in the +stomach. Learned men, after making minute researches, have found in +it another equally powerful material, which is also found in milk. +Therefore cheese, which contains this material as well as salt, is +quite in its place at the end of dinner. It furnishes reinforcements +for the stomach in cooking, and this is why you so often hear people +say that a little cheese helps the digestion. + +The _digestion_! Yes, that is the word I ought to have begun with. +It is the real name of all this cooking; an operation after which I +would defy you to recognise the nice little cakes you have eaten, any +better than your mamma can trace her pretty rosy-cheeked apples in the +jelly which she left on the fire two hours ago. The stomach, as you +see, is very busy quite as long a time as that, and if we have to be +very careful (as I pointed out before) not to disturb him too suddenly +in his work after dinner, it is also important that we should not, +while at dinner, give him more work to do than he is capable of doing. +Although he is the master, he is but a puny fellow, as I have already +pointed out; nevertheless, he works conscientiously, because he knows +that the life of the whole body depends upon his exertions. Some people +even say that in spite of his leanness he strips himself, at each +digestion, of his interior skin, which he sacrifices to his work, and +the fragments of which tend to increase and improve the stew which is +entrusted to his care. Think of this, my dear, whenever a greedy fit +comes over you, and recollect that such a disinterested public +functionary deserves some consideration. Besides, there is serious +danger, quite apart from any question of injustice, in overwhelming +him with work. If your legs are wearied out, you have it in your power +to lie in bed. If your arm is in pain, you can keep it at rest. But +your stomach is like those poor people who have to support their +families by the labor of each day. He, too, labors for others: he has +no right to rest, no right to be ill, therefore; and when he begins +to fail, woe betide you--you will have enough of it. + +Children who have learnt nothing may laugh at all this, but you, my +dear, are beginning to know something, and "science constrains," +_i.e._ it has its claims and requirements. It requires you, to-day, not +to be greedy, to-morrow, something else, and so on, continually, until +you have become quite reasonable and wise. I am sorry for you if this +vexes you, but it was your own wish to learn, and _science constrains_. +Indeed, I will whisper to you in confidence that this is the best excuse +people who are unwilling to learn have to offer for refusing. They do +not know what learning may lead to, and what a pity it would be if they +could no longer be greedy, or ill-natured, or selfish. What would become +of us all in such a case? + + + +LETTER IX. + +THE STOMACH--_(continued)_. + +We made a very long story of the stomach last time, my dear child; +and, after all, I see that there was one thing I forgot to tell +you--viz., what it is like. + +Have you ever seen a bagpiper, I wonder? A man who carries under his +arm a kind of large dark brown bag, which he fills with air by blowing +into it, and out of which he presently forces the same air into a +musical pipe by pressing it gently with his elbow. If you never saw +such a thing, it is a pity; first, because the bagpipe was the national +instrument of our ancestors the Gauls, and is religiously preserved +as such by the Scotch Highlanders and the peasants of Brittany--(two +remnants of that illustrious race, whose history I recommend to your +careful perusal some day); secondly, and it is this fact which has the +greatest interest for us just now, because that large bag, which is +the principal part of the instrument, gives you a very exact idea of +your stomach; for in fact it really and truly _is_ a stomach itself, and +moreover, the stomach of an animal whose interior formation resembles +yours very, very much. + +And who do you suppose is this audacious animal, which presumes to +have an inside so like that of a pretty little girl? Really, I am half +ashamed to name him, for fear you should be angry with me for doing +so. It is--it is the pig! The resemblance is not exactly a flattering +one to you, perhaps, but we are all alike, and it would be worse than +foolish to grumble at being created as we are. Moreover, there is one +difference; the pig, who thinks of nothing but eating, has a very much +larger stomach than we have, which is some consolation, at any rate. + +Place the palm of your right hand on what is called the pit of the +stomach, turning the ends of the fingers towards the heart; your hand +will nearly cover the space usually occupied by the stomach, and you +may figure it to yourself as a rounded and elongated bag, bigger above +than below, making a very decided bend inside as it descends from the +heart downward; something like one of those long French pears, called +"Bon-chretiens," if it were bent in the middle, and the big end of it +were placed next the heart. As for the exact size of the bag, there +is no telling it, for it depends upon circumstances. It is a very +convenient bag in that respect; just such a one as you would like to +have in your frock for a pocket; only there would be a danger of your +being tempted to put too many things into it. For as you fill it, it +expands, and enlarges itself like an indian-rubber ball, which, though +only the size of an egg to begin with, becomes as big as your head if +you blow hard into it. Then, as it gets empty, it recovers itself, +diminishing gradually in size in plait-like contractions. + +When people remain too long without eating, they have, as they say, +twinges in the stomach. This is because the stomach, becoming by degrees +quite empty, and contracting more and more, the surrounding parts which +were sustained by it, lose their support, and strain at their ligaments, +which now have all the weight to bear. Careless people, who do not +think of such things, are reminded by the twinging pains that it is +time to eat, just as a careless servant is called to order by the bell +of which his master has pulled the string. + +In your case, my dear child, such warnings are soon attended to, and +you have not always even to wait till they come. But there are hundreds +of miserable beings who are warned to no purpose, who cannot obey the +master when he calls for his rations, because they have nothing to +give him; and when this forced disobedience lasts too long, they end +by dying of it. In cases like these, when human beings thus cruelly +perish, the stomach is found to be contracted till it is scarcely +bigger than one's finger. + +On the other hand, a man once died suffocated from excess of food, +after one of those great public dinners, which last four, six, or more +hours--one can scarcely say correctly how long--and the doctors who +examined him found his stomach so prodigiously enlarged that it alone +occupied more than one-half of his inside. As you perceive, therefore, +the stomach has, properly speaking, no fixed size. Its size depends +upon what there is in it. It is like those men whose manners go up and +down with their fortunes; who seem very grand people when their pockets +are well filled, but become very small ones when their purses are +empty. There is, nevertheless, this difference between them, that such +men are fools, because they are men, and not _bags_; whereas the +stomach is a sensible bag, fulfilling with intelligence the duties of +its character as a bag. It is very fortunate for us that it is ready +to change its size, according to the caprices of our appetite; and +dressmakers would do well if they could get a hint from it how to +improve their style of pockets, which certainly cannot have cost their +inventors any very great effort of imagination! + +The way in which this extraordinary pocket empties itself is not less +curious than the rest. As long as digestion is going on, the stomach +is firmly closed at each end; at the upper one by the last ring of the +_aesophagus_, and at the lower by another ring of the same kind, +only stronger; the watchful guardian of the passage which leads to the +intestines. This ring is called the _pylorus_. + +For once, here is a name which agrees with our method of describing +the human machine, and I have much pleasure in translating it to you, +although it is a Greek word. _Pylorus_ is the Greek for a porter; +and our ring is indeed a porter like the one of which we have already +said so much, and which I called last time the _porter up above_, +in anticipation of his colleague below. + +The porter up above presides at the entrance; the one below at the +exit, and both for the same purpose, namely, to _taste._ [Footnote: +It would be absurd to say so in the common acceptation of the term; +but according to No. 1 of Mr. Mayo's "Classification of the impressions +produced by substances taken into the fauces," viz., _"Where +sensations of_ touch _alone are produced, as by rock-crystal, +sapphire, or ice,"_ the word taste may be applied to the +discriminating faculty of the _Pylorus_.--TR.] + +It may well astonish you, that you should have in your inside a taster +who is not accountable to you; who experiences sensations of which you +know nothing, and cannot even form an idea. Yet thus it is. The +_pylorus_ actually tastes the paste which is in the stomach, and +if it is not to his taste, that is to say, if the work of digestion +has not sufficiently transformed it for use, he keeps the door +relentlessly closed. + +The porter up above has a thousand different tastes. He makes his bow +to meringues, and admits wings of chickens. Fries, roasts, stews, +things tender or crisp, sweet and salt, oily, greasy, or sour; amongall +kinds he has friends whom he welcomes in succession; and it is +well for us that he does so, for we share in all his pleasures. + +The porter below, who works for himself alone, obscure and unknown +down in his black hole, the porter below, I say, has but one taste, +knows but one friend--a gray-looking paste, semi-liquid, with a very +peculiar unsavoury smell, disagreeable enough to any one but himself, +which is called the _chyme_, I scarcely know why, but it is what +everything one eats turns into, without exception, be it delicate or +coarse by nature. The great lord's truffle-stuffed pullet makes, as +nearly as possible, the same _chyme_ as the charcoal-burner's black +bread; and though the palate of the former may be better treated +than that of the latter, the _pylori_ can enjoy but one and the +selfsame sauce. Equality is soon restored in this case, therefore, as +you see. + +To be free to pass through then, the contents of the stomach must be +reduced to the condition of _chyme,_ the only substance which finds +favor with the _pylorus:_ and as, in the endless varieties of food which +go to form our nutriment, some sorts turn into _chyme_ much more quickly +than others, it follows, that by the aid of its discriminating tact +(which is not easy to elude) the _pylorus_ allows some to pass, while it +turns back others, until all in succession are converted into chyme. For +example, in the case of a mouthful of bread and meat swallowed at once, +the bread passes away on its travels long before the meat has done +dancing attendance in the stomach, awaiting that transformation without +which the _pylorus_ will never allow it to slip through. + +This ought to make you seriously reflect on the danger of carelessly +swallowing things, which, by their nature, are not susceptible of being +converted into _chyme,_ particularly if they are too large to +hide in the general paste, as a cherry-stone will sometimes do, so +mixed up with other food as to pass unperceived by the _pylorus,_ +over whose decisions we have no control, remember. It bangs the door +to, be assured, in the very face of anything obnoxious without +hesitation, and the poor stomach would find itself condemned to retain +them for an indefinite period, unless by dint of prayers and +supplications they should contrive to soften the stern guardian, who +may at last get accustomed to their approach, and, perhaps, in a weak +moment, allow them to pass as contraband goods; like a custom-house +officer on a foreign frontier who will occasionally shut his eyes to +a country friend's packet of tobacco. But the poor stomach has had to +suffer a martyrdom meantime, while the dispute was pending, and before +the intruder has been winked at by the porter. + +I shall remember all my life the history of a peach-stone, which was +related to me in 1831. I was at the time a youngster at the Stanislaus +College, and (aided perhaps by the Revolution of July, which had +recently occurred), it was just then discovered to be a proper thing +to set about teaching the laws of nature to children. Consequently, +for the first time in the history of schools, a professor of natural +history was added to the instructors of Latin and Greek. I leave you +to judge how we opened our ears to his lessons. When we arrived in the +course of our new studies at the _pylorus,_ of which we had none +of us ever heard before, our professor, in warning us, as I have done +you, of the dangers of imprudent gluttony, related, as an instance, +the case of a lady who had inadvertently swallowed a peach-stone. For +two years she suffered agonies in her stomach without any cessation +or relief. The luckless peach-stone, repelled by the walls of the +stomach, which its very touch irritated, was incessantly thrown against +the entrance of the _pylorus,_ but in vain. As to turning itself +into _chyme,_ such a thing was not to be thought of, it was far +too hard a substance for that. Round and round it went, causing in its +relentless course such renewed suffering to the poor patient, that she +was visibly sinking from day to day. + +The doctors, finding all their treatment of no avail, began to despair +of her life, when one fine day she was suddenly, and as if by +enchantment, relieved of her tormentor. The peach-stone had bribed the +porter, with whom, in the course of the two years, it had scraped up +a sort of friendship. It had cleared the terrible barrier, had been +allowed to slip out, and the lady was saved; but it was only just in +time. + +I do not know, my dear, that this story, which is certainly well +calculated to cure you of any fancy for swallowing peach-stones, +willmake as much impression on you as it did on me five-and-twenty years +ago. The idea of telling it to you occurred to me quite by chance. It +has carried me back to the time when, as is now the case with you, the +mysteries which lie hidden in our internal organization were beginning +to be revealed to my mind; and you will one day know with what delight +one recalls the remembrance of these first dawnings of the intellectual +life--that delightful infancy of the growing mind--more rich in +recollections, and more interesting a thousand fold than the infancy +of the body. I have allowed myself the little treat of this episode, +and if I have had the good fortune to amuse you at all during our +progress, you must not cavil at this piece of self-indulgence. +And now we have done just what the peach-stone did; we, too, have +passed the barrier, and are out of the stomach, but still we have not +yet come to the end of our tale. + + + +LETTER X. + +THE INTESTINAL CANAL. + +I venture to hope, my dear child, that more and more light is dawning +upon your mind, as we gradually proceed on our little journey. You +must by this time have some idea how the food, which has been masticated +and softened in the mouth, cooked, kneaded, and decomposed in the +stomach, and transformed into a soft, semi-transparent kind of paste, +will soon be ready to mix with the blood, in order to repair the waste +that the life-stream is continually undergoing in its ceaseless course +through all parts of the body. + +You have perhaps thought it a sad degradation for a truffle-stuffed +fowl to turn to _chyme._ But when you consider that by this means +it becomes part and parcel of a human body, the change is not to be +despised. It was necessary, to begin with, that materials destined to +the honor of being incorporated into our frame, should break the links +which bound them to the condition of fowl and vegetable, and thus be +free to engage in new relations; just as a man who wishes to be +naturalized in a new country must first break the ties which hold him +to the old one. Those articles of food we were speaking of lately, +which are so stiff and ceremonious, and want so much coaxing before +they change into _chyme,_ which, moreover, we call _indigestible_ +because they tire the stomach so much more than the rest, are merely +those whose component parts being held together by more solid ties than +usual, continue obstinately in the same state as at first, and will not +consent to that dissolution which is the first condition of their +glorious transformation. + +Moreover, the transformation which has been described to you now, you +will henceforth meet with everywhere; wherever, that is to say, and +as far as, you choose to pursue the study of nature. God works by one +grand and simple rule so far as we can discover. He destroys to +reconstruct, builds up what is to be, out of the ruins of what has +been, creates life by death, if I may so express myself, and thus, +what takes place in our stomachs on a small scale goes on on a large +one in the universe. + +Social communities, like everything else, are subject to this universal +law, and it is not always an advantage to them when they refuse to be +digested in the great stomach of the age! + +While we are on this subject, and to show you how wonderfully this +little history of eating, told in this familiar style, applies right +and left, let us reflect on the causes which have produced a great and +mighty nation in one country (as in France), while in another (as in. +Germany), a far more numerous and even more intellectual population +has failed to rise to anything like the same distinction. The +explanation is not difficult. In the one case, the petty tribes among +which the land was originally divided consented to mix, and dissolve, +and be digested as it were together, in order to revive again for a +more glorious career; while in the other, the aboriginal societies +have adhered stiffly to their distinctive characters, and failing to +submit to the regenerating process, cling together in indigested +portions, rather than assimilate into one great whole. + +However, we must return to the _pylorus_ or we shall be getting +into a difficulty! What I am now going to offer you though, is rather +hard of digestion, but it will not do to provide sweet pastry only for +your brain; it will be more wholesome for it to have something a little +more solid to bite at from time to time. + +The _pylorus_, then, as has been shown, makes way for all sorts +of aliments when they have been converted into _chyme; i.e._, +when they have lost their original form and individuality. They are +dead to their first life, therefore; now the question is, how are they +to be revived into the new one? + +Behind the _pylorus_ extends a long conduit or tube--so long as to be +sometimes seven times the length of the whole body, but doubled up +backwards and forwards a number of times, so as to form a large bundle, +which fills the whole cavity of the belly--or as we also call it, the +_abdomen_. This bundle or packet is known to everybody as _the +intestines_, and it is divided into two portions: the _small +intestine_--that is, the slenderer, finer portion which begins at the +_pylorus_, and forms all the doublings of the packet, and the _large +intestine_, which is shorter and thicker also, as its name implies, and +keeps to some extent separate, though it is in reality only a +continuation of the other. This starts at the base of the _abdomen_, +near the right side, goes up in a straight line to the height of the +stomach, below which it passes, making a large bend in front of the +small intestine; after which it descends on the left side to the lower +part of the trunk, where it terminates. + +You will perhaps inquire how the _chyme_ continues to make its way +through all these manifold twists of the intestines; but do not trouble +yourself; it has only to let itself go. That _vermicular movement_ which +we noticed in the _oesophagus_ and in the _stomach_ is found here also. +It reigns, so to speak, from one end of our internal eating-machine to +the other; which eating-machine, by the way, we will now call by its +proper scientific name--_the intestinal canal_; and it is by that +movement the food is carried forward from the first moment it leaves the +mouth, and helped through all its journeyings, till it reaches the +termination of the large intestine. + +If your body were made of glass, so that you could look through it to +watch the intestine at work, it would appear to you like an enormous +worm coiled up into a bundle, heaving and moving with all its rings +at once. You never suspected there was such a movement within you; yet +it has been going on there continually ever since you were born, and +will not cease till you die. Your internal machinery never goes to +sleep, not even when you are sleeping yourself. It is a workshop in +constant operation, providing night and day for your necessities; and +in this respect the inner man sets a first-rate example to the outer +one! You will recollect what I said to you the other day about the +internal republic, and the provinces which are under your sole +government. It would be very disgraceful for the kingdom to be doing +nothing while the republic is working so hard; and a queen who +understands her office will make it a point of honor to banish idleness +from her household; in the houses of her neighbors this word is unknown. + +The _chyme_ once launched into this moving tube, is in no danger +of remaining stationary there; the fear is, of its passing on too +quickly, as you will soon see. But this danger has been provided +against. Along the whole course of its journey, though chiefly at the +commencement, it encounters at intervals certain elastic fleshy valves +which interrupt its progress, and do not allow it to pass till it has +accumulated in sufficient force to push them before it, and so escape. +In consequence of which it is always being checked in its advance; and +during these stoppages a most important work goes on upon it at leisure. + +You must understand first, that the substances of which our food is +composed, and which are afterwards decomposed in the stomach, are not +all invited to enter the blood. Our aliments are something like the +stones which the gold-seekers of California reduce to powder in order +to extract therefrom the hidden particles of gold they contain. The +gold of our food is that portion of it which the blood is able to +appropriate to his own advantage; the rest he rejects as refuse. And +this explains why a small slice of meat nourishes you more than a whole +plateful of salad. Meat is a stone absolutely full of gold, while the +salad has only a few veins of it here and there, and by far the greater +part of the material it sends to the intestines, has, in consequence, +to be thrown away. + +Now it is in the first portion of the small intestine, the part known +by the Latin name _duodenum,_ which signifies twelve (because it +is about the length of twelve finger-breadths), that the division takes +place between the parts which go to nourish the blood, and those which +are useless refuse. It is an important operation as you may suppose, +and were the _chyme_ to pass rapidly through the small intestine +the gold would run the risk of being carried off with the refuse. + +After the delay in the stomach, the food-substances make another halt +in the _duodenum,_ which, being very thin and slender, would have +great difficulty in containing them at the time of their grand entry, +an hour or two after a meal, were it not that it possesses the property +of expanding itself to such an extent, that it swells out on grand +occasions to the usual size of the stomach itself, so that it has +sometimes been considered as a second stomach. And no doubt the +operation which takes place in it gives it a claim to the appellation, +for thereby the finishing stroke is put to the work previously begun +in the stomach, and one may fairly say that, but for this last touch, +very little would be accomplished at all. + +Above the _duodenum_, and hid behind the stomach, is a kind of sponge, +similar in nature to those we have already observed in the mouth. To +this has been given the somewhat ridiculous name of _pancreas_; I call +it ridiculous because it is derived from two Greek words which signify +_all flesh_; whereas the _pancreas_, which is a sponge of the same +description as the salivary glands, presents the appearance of a grayish +granulous mass which is not fleshy at all. Whatever be its name, +however, our sponge communicates with the _duodenum_ through a small +tube, by means of which it pours into the _chyme_, as it accumulates, a +copious supply of a fluid exactly like the _saliva_ of the mouth. + +Just by the place where the tube from the _pancreas_ empties itself into +the _duodenum_, another tube arrives bringing also a fluid, but of a +different sort. This last comes from the liver, where there is a +manufactory of _bile_--an unpleasant yellowish-green liquid, the name of +which you have no doubt heard before, and which plays a very important +part in the transformation of the aliments. + +These new agents, the bile and the liver, are far too important to be +passed over in a few words; I reserve them, therefore, for my next +letter. Meantime, not to leave you longer in suspense, I may say that +the separation between the gold and the refuse in the _chyme_ takes +place as soon as the latter has received the two liquids furnished +by the liver and the _pancreas_. If you ask in what manner the +division is accomplished, I confess, to my shame, that I am not able +to explain it! What takes place there is a chemical process, and +hereafter I shall have occasion to explain the meaning of that phrase. +But the Great Chemist has not in this instance seen fit to divulge to +man the secret of the work. + +Indeed, you must prepare yourself beforehand, my dear child, to meet +with many other mysteries besides this, if we pursue to the end our +study of this flesh and bone which constitute the body of man. And +here I recall what Camille Desmoulins is reported to have said about +St. Just, viz., that he carried his head as high as if it were a +consecrated Host. + +[Footnote: The young Protestant reader who has never lived +in a Catholic country, will perhaps need to be told, that what +is here called Consecrated Host, is the sacramental wafer, or communion +bread of the church. In French called _hostie_, in Italian, _ostia_. + +In all their religious processions, which are very frequent, the host +is carried by the priest highest in authority, in a glass box placed +on a staff about four feet long, which he holds before him and so far +elevated that he has to look up to it. Over his head a richly +embroidered canopy of satin is always carried by several men; and while +these are passing, all good Catholics uncover the head and bend the +knee, wherever they may be. + +It is the custom also for the priest to be called to administer the +sacrament to any one about to die, on which occasion he always walks +under this canopy, dressed in his priestly robes, carrying the host +and preceded by some boys, ringing a bell, when the same ceremony is +observed. In passing a regiment or company of soldiers, the column is +halted, wheeled into line, and with arms presented, the whole line, +officers and men, kneel before it, and the priest usually turns and +offers a benediction. When he goes in the evening to the house of the +dying, it is customary for the people to go out upon the balconies +with lighted lamps and kneel while the host is being carried by.] + +You will read about these two men by-and-by in history. Meantime I +will not bid you do exactly the same as St. Just, because you would be +laughed at; but in one point of view he was not altogether wrong. The +human body is, in very truth, a temple in which the Deity maybe said +to reside, not inactively, not veiling his presence, but living and +moving unceasingly, watching on our behalf over the mysterious +accomplishment of the everlasting laws which equally guide the +_chyme_ in its workings through our frames, and direct the sun +in its course through the heavens. We mortals eat, but it is God who +brings nourishment out of our food. + + + +LETTER XI. + +THE LIVER. + +I fear you will be getting a little weary, my dear, of dwelling so long +on this intestinal tube, where things which looked so well on one's +plate become so transformed that they cannot be recognized, and where +there is nothing to talk about but _chyme_, and _bile_, and the +_pancreas,_ and all sorts of things neither pleasant to the eye nor +agreeable to the ear. + +But what is to be done? It is always the same story with useful things. +The people by whose labor you live in this world, are by no means the +handsomest to look at, and so it is in the little world we carry about +in our bodies. + +Never mind! Keep up your heart. We are getting to the end. We shall +very soon be following the nourishing portion of our food, on its +journey to the blood, and you will find yourself in new scenes. + +First, though, let us say a few words about the liver--the +bile-manufacturer; and to begin with, I will describe the place he +occupies in our interior. + +The interior of the human body is divided into two large compartments, +placed one above the other; the _chest_ and the _abdomen_. These are two +distinct apartments, each containing its own particular class of +tenants: the upper one being occupied by the heart and the lungs (the +respective offices of which I will presently explain to you); while in +the lower are the stomach, the intestines, and all the other machinery +which assists in the process of digestion. These two stories of +apartments are separated as those of our houses are, by a floor placed +just above the pit of the stomach. This floor is a large thin, flat +muscle, stretched like canvas, right across the body; and it is called +the _diaphragm_--another hard word! Never mind; but do your best to +recollect it, for we shall have great need of it when we come to the +lungs. If you had been born in Greece, you would have no difficulty with +the word, for it is Greek for _separation_. It means, in fact, a +_separating partition_, or, as I called it just now, _a floor._ All this +is preparatory to telling you that the liver is hooked to the diaphragm +in the abdomen. It is a very large mass and fills up, by itself alone, +all the right side of the lower compartment, from the top downwards, to +where the bones end which protect the abdomen on each side, and which +are called _the short ribs._ Place your hand there, and you will find +them without difficulty. + +Large as the liver is, it hangs suspended to a mere point of the +diaphragm, and shakes about with even the slightest movement of the +body. It is partly on this account that many people do not like to +sleep lying on the left side, especially after a good dinner, because +in this position the liver weighs upon and oppresses the stomach, like +a stout gentleman asleep in a coach who falls upon and crushes his +companion at every jolt of the vehicle. The liver within you produces, +then, the same effect that a cat, lying on the pit of your stomach +would do, and the result is that you have the nightmare. + +The liver is of a deep-red color. It is an accumulation of excessively +minute atoms, which, when united, form a somewhat compact mass, and +within each of which there is a little cell, invisible to the naked +eye, where an operation of the highest importance to our existence is +mysteriously carried on. It appears a very simple one, it is true, yet +hitherto it has baffled all attempts at explanation. Listen, however; +the subject is well worthy your careful attention, whether it can be +explained or not, and we must look back to take it up from thebeginning. + +I told you about the thousand workmen constantly busied in every part +of our bodies, who call on the blood without ceasing for "more, more." +You will remember further that it is to enable the blood to supply +these constant demands, that we require food. + +This being understood, it is not difficult to see why we grow; the +difficulty is, rather, to explain why we do not continue to grow. + +Consider, for instance, the quantity of food you have eaten during the +last year. Picture to yourself all the bread, meat, vegetables, fruits, +cakes, &c., piled upon a table. Put a whole year's milk into a large +earthenware pan, all the sweetmeats into a large jar, all the soup +into a great tureen, and see what a huge heap you will have collected +together. Then try to recollect how much you have increased in size +with all this nourishment, which has entered your body. But reckoning +in this way--even supposing the little workmen had used only a half +or even a third of the materials in question, and rejected the rest +as refuse--you would have to stoop in order to get in at the door; and +as for your papa, whose heap must have been bigger than yours, his +case would be desperate indeed; and yet he has not grown at all! + +This is very curious, and I dare say you have never thought about it +before. + +Do you know the story of a certain lady called Penelope, who was the +wife of Ulysses, a very celebrated king of whom the world has talked +for the last 3000 years--thanks to a poet called Homer, who did him +the honor of making him his hero! The husband of Penelope had left her +for a long time to go to the wars, and as he did not return, people +tried to persuade her to marry again. For peace and quiet's sake, she +promised to do so when she should have finished a piece of cloth she +was weaving, at which she worked all day long. They thought to get +hold of her very soon, but her importunate lovers were disappointed; +for the faithful wife, determined to await the return of her husband, +unwove every night the portion she had woven during the day; and I +leave you to judge what progress the web made in the course of a year! + +Now, every part of our bodies is a kind of Penelope's web, with this +difference--that here the web unravels at one end as fast as the work +progresses at the other. As the little masons put new bricks to the +house on one side, the old ones crumble away on another--in this manner +the work might go on forever without the house becoming bigger; while, +on the other hand, the house is always being rebuilt. People who are +fond of building, as some are, would quite enjoy having such a mansion +as this on hand! + +At your early age, my love, fewer bricks drop out than are added, and +this is why you grow from year to year. At your papa's age, just the +same number perish and are replaced; and therefore he continues the +same size, although in the course of the year he swallows three times +his own weight of food. But when I say this, do not suppose it is an +offensive remark, or that I think him either too little a man, or too +great an eater; seeing that there are 365 days in the year, and that +a quart of water weighs two pounds: I need not say more! + +But the next question is, what becomes of all the refuse which this +perpetual destruction produces? + +What becomes of it? Have you forgotten our steward who looks after +everything? He is a more active fellow than I have represented him! +To the office of purveyor-general he adds that of universal scavenger. +But in the latter department he obtains help. Wherever he passes along, +troops of little scavengers press forward, like himself always busy; +and while he holds out a new brick to the mason as he hurries by, the +little scavenger slips out the old one and conveys it away. The history +of these scavengers is a very curious one, and we shall have to speak +about it a little further on. They are minute pipes, _i.e. ducts_, +spread all over the body, which they envelope as if with fine net work. +They all communicate together, and end by emptying the whole of their +contents into one large canal, which, in its turn, empties itself into +the great stream of the blood. Imagine all the drains of a great town +flowing into one large one, which should empty itself into the river +on which the town was built, and you will have a fair idea of the whole +transaction. What the river would in such a case be to the town, the +blood is to the body--the universal scavenger, as I said before. But +you will ask further, What does the blood do with all this?--a question +which brings us back once more to the liver. + +You must have seen, just now, that the pockets of our dear steward +would be rapidly overloaded, were he to keep constantly filling them +with the old worn-out materials which the builders rejected, unless +he had some means of emptying them as he went along. Accordingly, a +wise Providence has furnished the body, on all sides, with clusters +of small chambers or cells, in which the blood deposits, as he goes +by, all the refuse he has picked up, and which makes its exit from the +body sometimes in one way, sometimes in another. Now, the cells of the +liver are among these refuse-chambers. One may even consider them as +some of the most important ones. When the blood has run its course +through the lower compartment, I mean the _abdomen_, it collects +from all directions and rushes into a large canal called the _portal +vein_, which conveys it to the liver. As soon as this canal has +entered the liver, it divides and subdivides itself in every direction, +like the limbs and branches of a tree diverging from the trunk; and +very soon the blood finds itself disseminating through an infinity of +small canals or pipes, whose ultimate extremities, a thousand times +finer than the finest hairs of your head, communicate with the tiny +cells of the liver. There, each of the imperceptible little drops, +thus carried into these imperceptibly minute cell-chambers, rids +itself--but no one knows how--of a part of the sweepings it has carried +along with it. Which done, the little drops thread their way back +through other canals as fine as the first, and which go on uniting +more and more to each other, like the branches of a tree on their way +to the trunk--forming at last one large canal, through which the blood +escapes from the liver, once more relieved from its weight of rubbish, +and ready to recommence its work. + +You are going to ask me, "What is all this to me--this history of the +blood and its sweepings? It was the bile you undertook to tell me +about, that liquid you spoke of as so necessary for the transformation +of the food: we were to get out of the intestinal tubes by the help +of the bile, you promised me." + +Well, my little impatient minx, it is the history of the bile that I +have been relating to you, and what is most remarkable about it is +this. You have perhaps heard of those wholesale ragpickers, who +makelarge fortunes by collecting out of the mud and dirt of the streets, +the many valuable things which have been dropped there? Well, the liver +is the master-ragpicker of the body. He fabricates, out of the refuse +of the blood, that bile which is so valuable in the economy of the +human frame. This bile is neither more nor less than the deposit left +by the little drops of blood in the innumerable minute liver-cells. +See what an ingenious arrangement, and in what a simple way two objects +are effected by one operation! + +Now you have learnt the genealogy of the bile, and the double office +of the liver, which benefits the blood by what it takes from it, +benefits the _chyme_ by what it gives it, and is an economist at +the same time--since it only gives back what it has received. This was +what I particularly wished to explain to you: the rest you will easily +learn. + +The bile does not make a long stay in the little cells, it also escapes, +by canals similar to those which carry off the blood, after +itspurification; and which in a similar way unite by degrees together, +until at length they terminate in a single canal, communicating with +a little bag placed close against the liver, where the bile accumulates +between the periods of digestion--so forming a stock on hand, ready +to pour at once into the _duodenum_ when the latter calls for its +assistance. The next time the cook cleans out a fowl, ask her to show +you the little greenish bladder which she calls the gall and which she +takes such care not to burst, because it contains a bitter liquid +which, if spilt upon it, would quite ruin the flavor of the fowl. Such, +precisely, is the bag which holds the bile. Moreover, it is close by +the liver of the fowl that you will find it placed: and you can convince +yourself in a moment by it, that the little provision I tell you of +is always stored away therein. + +We have also within us a multitude of minute electric telegraphs, which +transmit intelligence of all that occurs from one part of the body to +another, in a more wonderful manner even than the telegraphs of man's +making; later we shall see how they work. By their means the little +bag by the liver is made aware in the twinkling of an eye of the +entrance of the _chyme_ into the _duodenum,_ and forthwith the bile +returns for some distance by the canal which brought it, and then +branches off into a larger one which opens into the _duodenum._ + +The liver, on getting this intelligence, sets to work more diligently +than ever, and the bile flows in streams into the _duodenum,_ where it +mixes as it arrives with the current which comes from the _pancreas._ +Thus combined, the two liquids flow over the _chyme,_ which they +saturate on all sides; and here, as I have said, the work of the +intestinal canal ends. What is serviceable for the blood is separated +from the useless refuse, and nothing remains but to get it out of the +intestines. It is true that in their character of tubes these are closed +on all sides. But do not trouble yourself: a means of escape is +prepared. + +Before we part, however, I must apologize for something. I have not +described to you what the bile consists of, or what kind of refuse the +blood leaves in the liver; nevertheless, as you take an interest in +this much-neglected book of nature, you ought to know these things. + +It is, however, very difficult to lead you by the hand through so many +wonder*, where the secrets of nature are all in operation at once, and +to explain each as soon as we meet with it. They combine, and progress +together like the waves of the sea, where one breath suffices to agitate +the whole mass. + +When we have talked about the lungs, we will have another word to say +about the liver. + + + +LETTER XII. THE CHYLE. + +To-day we have to begin by making acquaintance with a new term. I would +willingly have spared you this, if I could, for the word is neither +a pretty, nor a well-chosen one, but we cannot get on without it. + +You are aware now that the learned, unknown sponsors, who gave names +to the different parts of the body, bestowed the odd-enough one of +_chyme_ on that pasty substance which passes out of the stomach when the +cooking is over. We have said quite enough about it, and you know enough +of it I am sure. Well! the people seem to have had quite a fancy for the +word _chyme_, for they adopted it again, with only a very slight +alteration, when they wanted to specify separately the quintessence of +the _chyme_ (the useful part that is), which has to unite with the +blood, and which we have been speaking of as the _gold_ of the +aliments--this then they called _chyle_. I give you the name as I +received it, but have no responsibility in the matter. + +In concluding the last chapter I said we were sure to find there was +a plan for extracting the best part of the _chyme_, viz. the _chyle_, +from the intestinal canal; and a very simple one it is. A complete +regiment of those little scavengers lately described, are drawn up in +battle-array along the whole length of the small intestine, but +especially round about the _duodenum._ There, a thousand minute pipes +pierce in all directions through the coat of the intestine, and suck, +like so many constantly open mouths, the drops of _chyle_ as fast as +they are formed. They are called _chyliferous vessels_ or chyle-bearers, +just as we might call hot-air stoves _caloriferous_ or heat-bearers--from +the Latin word _fero,_ which means to carry or bear. I mentioned +before that there were, within the intestine, certain elastic valves +which obstruct the progress of the _chyme,_ and oblige it to be +constantly stopping. There are in fact so many of these, and the skin +which lines the intestinal canal is so folded and plaited, that if it +were stretched out at full length on a big table, it would cover at +least as large a surface as that other skin, with which you are so well +acquainted, which entirely clothes the body outside. + +Now, the _chyliferous vessels_ we have been speaking of insinuate +themselves into all the plaits and folds alluded to, and thus they +reach at last the very centre of the _chymous_ paste, and not a single +drop of _chyle_ can escape them. They do their work so well, that the +separation is effected long before the paste reaches the large +intestine; and when that has forced its way through the door which +guards the entrance, and which prevents its ever returning again, the +_chyle_ is already far off on its mission. It has threaded its way along +the little pipes, and, always creeping nearer and nearer, is on the +high-road to the heart, where it is anxiously expected. + +And what becomes of the rest? There is nothing further to be said about +it, but that it shares the fate of everything else which, having +answered its purpose in its place, is no longer wanted and must be got +rid of. Thus in works where iron-stone smelting is carried on, the +refuse that remains after the ore is extracted, though available for +road-making or other purposes, is thrown out of the manufactory as a +useless incumbrance there. + +Our history requires us to follow the fate of that golden aliment the +_chyle,_ which is now in a condition to support the life of the body, +and every drop of which will turn into blood--the blood which beats at +our hearts, nourishes our limbs, and sets at work the fibres of our +brain. + +I ought to tell you first that the _chyle,_ when it leaves the +intestine, is very like milk. It is a white, rather fatty juice, having +the appearance, when you look closely at it, of a kind of _whey,_ +in which a crowd of globules, or little balls if you prefer it, +infinitesimally small, are swimming about. Some people, whose curiosity +nothing can check, have put the tips of their tongue to it; so I am +able to tell you, if you care for the information, that it has rather +a saltish taste. + +At this point it is what may be called new-born blood, and to carry +on the metaphor, blood whose education has yet to be completed. All +the elements of blood are there already, but in confusion and +intermingled, so that they cannot yet be recognised. A wonderful fact, +and one of which I have no explanation to offer you, because among the +many mysteries which are silently going on within us is this, that the +education of the new-born blood begins entirely of itself in the vessels +which are carrying it along. During their very journey, the confused +elements are setting themselves in order and forming into groups. In +short the _chyle,_ when it comes out of the chyliferous vessels, +is already much more like blood than when it entered them, and yet one +cannot account for the change. It is changed, however; its whiteness +has already assumed a rosy tinge, and if it is exposed to the air it +may be seen turning slightly red, as if to give notice to the observer +of what it is about to become. + +You know that all our scavengers uniting together deposit their +sweepings in one large canal, which is called the _thoracic duct._ +The _chyle_ scavengers arrive there just like the rest, and there +our poor friend finds himself confounded for a moment with all the +dross of the body, as sometimes happens to men who devote themselves +to the public good. But the crisis passes in an instant. A little +further off, the _thoracic duct_ pours its whole contents together +into a large vein situated close to the heart, and the blood has no +difficulty in recognising and appropriating what belongs to him. + +Here, my dear little scholar, we conclude the first part of our story. +To eat is to nourish oneself; that is, to furnish all parts of the +body with the substances necessary to them for the proper performance +of their functions. The mouth receives these substances in their crude +condition, the intestinal canal prepares them for use, and the blood +distributes them. + +After the history of the _preparation,_ comes naturally that of the +_distribution._ + +The first is called the DIGESTION. It is the history of the _chyle,_ +which begins between the thumb and forefinger while as yet invisible, +hid in the thousand prisons of our different sorts of food, and ends in +the _thoracic duct_, when, disengaged from all previous bonds, purified +and refined by the ordeals of its intestinal life, it leaps into the +blood, carrying with it a renewal of life and power. + +The second history is that of the CIRCULATION. It is the history of +the _Blood,_ that indefatigable traveler, who is constantly +_circulating_ or describing a circle (the Latins called it _circulus_) +through the body; by which I mean that it is continually retracing its +steps, coming out of the heart to return to it, re-entering it only to +leave it again, and so on without intermission, until the hour of death. + +The history of the _Digestion_, which we have just gone through, +goes on quietly from one end to the other without any complication. + +That of the _Circulation_, which we are about to begin, is mixed +up with another history, from which it cannot be kept separate while +the description is going on, although the two histories are in reality +quite distinct from each other. The blood describes two circles, to +speak correctly: 1st. A wide one, which extends from the extremities +of the body to the heart, and back again from the heart to the +extremities. 2d. A more contracted one, which goes from the heart to +the lungs, and back from the lungs to the heart. Whilst circulating +in the lungs, it encounters the air we breathe; and here takes place, +between it and the air, one of the most curious transactions imaginable, +without which the blood would not be able to nourish the body even for +five minutes. This is called RESPIRATION, or the act of breathing. + +Digestion, circulation, respiration, the three histories together form +but one--that of NUTRITION, or the act of nourishing; in other words, +of supporting life. This is what I called _eating_ at first, that +I might not mystify you at the beginning with hard words. But now that +we are growing learned ourselves, we must accustom ourselves to the +terms in use among learned people, especially when they are not more +formidable than those I have just taught you. + +Our next subject for consideration, then, Will be the circulation; and +we will begin with the heart, since that is to the circulation what +the stomach is to the digestion--viz., master of the establishment. +He is a very important person, this heart, as I hardly need tell you. +Even ignorant people speak respectfully of him, and I am sure beforehand +that his history will interest you very much. + +Do you feel as I do, my dear child? I am quite happy at having brought +you thus far on our journey, and at being able to take a rest with you +at the gateway of the new country into which we are about to enter, +like travelers sitting down upon a boundary frontier. What a distance +we have come, since the day when I took you by the hand to conduct you +inside this little body, of which you were making use without knowing +anything about it! How many things we have learned already, and how +many more remain to be learned, of which you have at present no idea! +I assure you I should be almost afraid myself of what is before us +yet, if I did not rely upon my own strong desire to instruct you, and +the tender affection I bear to you. Believe me, the greatest of +constraining powers is love; and when I get bewildered in the midst +of some difficult explanation which will not come out clearly, I have +only to place before me those laughing eyes of yours, where sleeps a +soul that must soon awaken to consciousness, in order to make the +daylight come into my own! + +Must I add, too, that I am not working for you only? We are all placed +in this world to help each other, and in striving to bring down light +into your intellect, and good sentiments into your heart, I am thinking +also of those to whom you, in your turn, may render the same good +service hereafter, provided I have the happiness of succeeding now +with you. This ought to be so, ought it not? You should resolve to be +numbered one day among those who have not lived altogether for +themselves, but who have given the world something worth having as +they passed through it. To-day's labor will have been well employed +if, later on, it turns out that this history of the _chyle_ has +not been told you in vain! + + + +LETTER XIII. + +THE HEART. + +There was once upon a time a banker, a millionaire, who could reckon +his wealth not by millions only, but by hundreds of millions and more; +who was, in fact, so tremendously rich that he did not know what to +do with his money--a difficulty in which nobody had ever been before. + +This man took it into his head to build a palace infinitely superior +to anything that had hitherto been seen. Marbles, carpets, gildings, +silk hangings, pictures, and statues--in fact, the whole mass of +common-place luxuries as one sees them even in the grandest royal +abodes, fell short of his magnificent pretensions. He was an intelligent +man, and thoroughly understood the respect due to his riches; and the +common fate of kings seemed to him far too shabby for the entertainment +of his dynasty, which he looked upon as very superior to all the +families of crowned heads in the world. In consequence he sent to the +four quarters of the globe for the most illustrious professors, the +most skilful engineers, the cleverest and most ingenious workmen in +every department; and giving them unlimited permission as to +expenditure? ordered them to adorn his palace with all the wonders of +science and human industry. + +Science, and human industry, and unlimited means--what will they not +accomplish? No wonder that nothing was talked of for a hundred miles +around but the magic building--of which, by the way, I do not venture +to give you a description, because it would carry me too far away. Let +it suffice to say, that never Emperor of China, Caliph of Bagdad, or +Great Mogul had such a habitation as our banker, and for a very good +reason--he was twenty times as rich as any such gentry as I have named +ever were in their lives. + +When all was finished one trifling flaw was discovered: the place was +not supplied with water. A spring-seeker, who was summoned to the +premises, could only discover a small subterranean watercourse, a sort +of zigzag pipe, formed by nature, between two beds of clay, in which +the rain of the neighborhood collected as in a sort of reservoir. The +water was neither very clear nor very plentiful, as you may imagine; +and the professor appointed to examine it, having begun by tasting it, +made a horrible face, and declared there was no use in proceeding any +further; for it had a stagnant flavor which would not be agreeable to +my lord. + +To the amazement of every body, my lord jumped for joy when he heard +this unpleasant news. It was proposed to him to fetch water from a +river which flowed a few miles' distance off; but he would hear of +nothing of the sort. What he wanted was something new, unexpected, +impossible--that was his object throughout. He took a pen and drew up +at a sitting the following programme, which caused our poor professors +to open their eyes in dismay:-- + +1st. We will use the water on the premises. + +2ndly. It shall flow night day and in all parts of the palace at once. + +3rdly. There shall be plenty of it, and it shall be good. + +The professors looked at each other for some time without speaking, +and the gravest of them, whose fortunes and characters had been long +ago established, suggested that they should simply give my lord and +his money the slip, and so teach him to make fools of people another +time! + +But the youngsters, less easily discouraged, cried out against this +with one accord. They declared that the honor of science was at stake, +and that they ought to return impudence for impudence, by executing +to the letter the impertinent programme! At length, after much +discussion and many propositions made against all hope, and thrown +aside one after the other as impracticable, a sudden inspiration crossed +the brain of an engineer who had not yet spoken; and the following is +what he proposed:-- + +What prevented the water from being sweet and fit to drink, was the +want of movement and air. What had to be done, therefore, was to erect +a pump, but a pump provided with numberless small pipes, extending to +the watercourse in all directions, and so arranged that by means of +them it should be able to draw up the water from all the corners and +windings where it lay stagnating, and then forcing it forward into a +pipe terminating in a rose, like that of a watering-pot, whence it +should gush out to fall down in fine rain, into a reservoir in the +open air. From thence another action of the pump was to bring it back +well aerated, to send it once more into a large pipe with numerous +lesser ramifications, which should convey it into every corner of the +palace. + +Up to this point all seemed practicable, but the hardest part had not +yet come. The great difficulty was how to supply this enormous +consumption with so slender a runnel of water as the one at their +disposal. But our engineer had provided for this by a stroke of genius. + +Under each of the taps (always kept open), which were dispersed all +over the palace, he would place a small cistern, from the bottom of +which should go a pipe communicating with the body of the force-pump +which drew up the water from the original watercourse. By which means +the water which ran from the taps would be taken up again and go back +to feed the reservoir in the open air; whence it would again return +to supply the taps; and so on and on, the same water continually keeping +the game alive, as people call it. Have you not sometimes seen at a +circus or theatre a large army represented by a hundred supernumeraries, +who file in close columns before the audience, going out at one side +of the stage and coming in at the other, following close at each other's +heels indefinitely? By a similar artifice the engineer would change +his meagre little runnel into an inexhaustible fountain. The water +drawn up from the watercourse by each stroke of the pump would fully +compensate for what was used in its passage through the palace by the +inhabitants. Lastly, as it might sometimes happen that the said +inhabitants washed their hands under the taps, the water on its return +to the cisterns, was to pass through a series of small filters, in +order to cleanse it from any impurity it might have contracted by the +way. Always flowing, always limpid, it would soon lose every trace of +its original source, and might defy comparison with the water of any +river in the world! + +A unanimous buzz of congratulations welcomed this plan, at once so +simple and so bold, and our professors thought their troubles were +over, but they were not at the end of their difficulties yet. When it +came to the actual erection of the machine, (naturally a most +complicated one, as it had to set a-going a quintuple system of +pipes--pipes from the water-course to the pump, pipes from the pump +to the reservoir, pipes from the reservoir to the pump, from the pump +to the taps, and from the taps to the pump again,)--our banker, who +had got amused and excited as they went on, conducted them to a small +dark closet, only a few square feet in size, concealed in a corner of +the large apartments, and informed them with a laugh that he had no +other place to offer them. Besides which, he made them understand that +on account of its situation, there could be no question of furnaces +or boilers being set up there (he detested equally coal-smoke, fires, +and explosions)--nor of workmen employed about the machine (it would +not be decent to have them going up and down the front staircase)--nor +above all, of the frightful brake-wheels always screeching and +grinding, the unwieldy pistons rising and falling with a noise +sufficient to give one the headache. He himself slept near the little +dark closet, and the slightest noise was fatal to his repose. Having +explained all this, the rich man curtly made his bow and retired. + +For once our professors owned themselves beaten. They had come forward +quite proud of their invention, and now they were received, not with +ecstasies of delight, but with fresh demands, more ridiculous even +than the first. They were decidedly being mystified, and were preparing +in consequence to pack up and begone, furious, and swearing by all +their gods that they would never again expose science to see itself +disgraced by a purse-proud vulgarian's scorn; when, lo! happily, a +good fairy, the special friend of learned men, came passing by that +way. She raised her enchanted wand with the tip of her finger, and all +at once a little girl dressed in rags appeared in the midst of our +astonished professors. Without giving them time to recover themselves, +the child put her hand into the little patched waist of her dress, and +drew forth a rounded object, about the size of her closed fist from +which hung a quantity of tubes spreading in all directions. + +"See!" cried she; "here is the machine your banker demands of you." + +Picture to yourself a small closed bag, narrowing to a point at the +end, and separated within into two very distinct compartments by a +fleshy partition which went across the inside from the top to the +bottom. Such was the object held up by the little girl. Prom each of +these compartments issued a thick tube, ramifying into endless smaller +ones; and they were moreover each surmounted by a sort of pouch, into +which ran another tube, of the same description as the first. Each of +these four portions (the two compartments and their pouches) was in +constant but independent motion, distending and contracting alternately; +and by carefully examining the noiseless play of this singular machine, +(the walls of which were, by the magic power of the fairy, rendered +transparent to the bystanders,) the learned assembly were very soon +enabled to convince themselves, that it fulfilled all the +monstrousconditions exacted of them by the fantastic millionaire. + +All was in movement together, I told you; but let us begin at one end. +The right-hand compartment and its pouch represented the first pump; +the pump employed to draw, by the same stroke, the water from the +stagnant channel, and that from the taps. It was perfectly easy to +distinguish the two systems of pipes, and how they united together at +the small pouch on their arrival. When this was distended, a vacuum +was created inside, which was instantly filled by the liquid from the +tube which ran into it, (do not ask me why or how; I will explain that +presently). When it contracted again, the liquid which had just entered +was not able to get back, being prevented from so doing by a very +ingenious and simple contrivance, which requires a brief explanation. + +Take off the lock from your chamber-door, which opens inside; then, +standing outside, push against it with your shoulder, and you will get +in without any difficulty. But when you are in, try to push the door +open again with your shoulder in order to get outside into the passage, +and you will find that you will not be able to pass through, and this +simply because it does not open on that side. + +Which was exactly what happened to the liquid in the pouch! + +The door between the tube and the pouch only opened inwardly, and the +liquid finding itself pressed on all sides in proportion as the pouch +contracted more and more, and unable to return, was obliged at last +to make its way through another similar door which led to the large +compartment below. Here the same game recommenced. The compartment +which had distended itself to receive it, contracted in its turn, and +the liquid finding the road again barred behind it, had no choice but +to force its way through the tube which led to the air-reservoir. + +Here commenced the work of the second pump,--the pump of the left +compartment. The little pouch, when distended, was filled by the liquid +from the reservoir, and then forced it forward into the large +compartment below, always by means of the same process. This compartment +again drove it, by a powerful contraction, into the large conducting +tube charged with the office of its general distribution throughout +the body. At the end of all which, it returned once more into the +right-hand pump as before, to pursue the same course again, &c., &c. + +Thus, as you see, the whole mechanism turned upon two little points +of detail, of the simplest description possible; namely, first, on the +entrance-doors only opening on one side; and secondly, on the elastic +covers of the pouches and compartments distending and contracting +spontaneously. It was the prettiest thing in the world to see this +unpretending-looking little bag working thus, quite naturally, without +a suspicion that it was solving a problem which so many men, proud of +their science, had given up as hopeless. Certainly here was a machine +which made no noise! Once installed in its dark closet, it would have +been necessary to place your hand upon it to find out that it moved +at all. My lord could certainly sleep beside it without disturbance. + +"How much do you want for it?" said they to the poor little beggar +girl. "Name your price; have no fear; we will pay you anything you +wish." + +"I cannot give it to you," replied the child; "I need it too much +myself: IT IS MY HEART. Now that you have seen it, make another like +it, if you can." And she disappeared. + +It is said that the engineer, who longed to see his idea carried out, +tried hard to construct a similar machine with gutta-percha and iron +wires, and to set it in motion by electricity. But history does not +tell us that he succeeded, and we have yet to ask ourselves whether +the richest man in the world, aided by the wisest men in the world, +could ever provide himself with a miracle of wonder, such as the, +ragged child had received as a free gift from the hands of a gracious +Creator. + + + +LETTER XIV. + +THE ARTERIES. + +If you have thoroughly understood the story I last told you, my child, +it will have revealed to you the whole mystery of the _circulation +of the blood,_ and you are at the present moment wiser than all the +learned men of antiquity and the middle ages, for they had none of +them the faintest surmise of the truth. + +It may, perhaps, seem odd to you that men should have existed for +upwards of five thousand years without making inquiry into a matter +which so closely concerned them, and which was so easy to find out. +Is it not almost incredible that so many hearts should have beaten for +so long a period without any of their owners having felt a wish to +know exactly _why?_ Yet so it is. The action of the heart and the +flow of the blood have not been understood for much more than two +hundred years, and the man whose name is attached to this great +discovery richly deserves that we should say a few words about him. + +He was called Harvey. He was an Englishman; physician to King Charles +I., who was beheaded in 1648; and when he first ventured publicly to +teach that the blood was constantly circulating from one end of the +human body to the other, perpetually returning and retracing its steps, +a great scandal was created in the world. He was called a fool,--an +impertinent innovator,--a madman. His words shattered old doctrines, +and he only received for his reward all the petty annoyances which men +are apt to lavish so freely upon any one who tells them something new; +because--do you see?--it is so disagreeable to be disturbed in one's +habits and preconceived ideas. + +Harvey is not the only one in the history of mankind who has committed +the sin of being right in defiance of the opinions of his age. It is +true posterity takes account afterwards of the labors of genius, and +inscribes a fresh name upon her list. But one must pay for this glory +in one's lifetime. One cannot have everything at once. + +This is an old story, my child, but always new nevertheless; and for +my own part it is, I own, one of my pleasures to amuse myself by +reflecting how much cause for laughter three-fourths of the great men +of the present day are providing for the little girls who shall be +alive two centuries hence. Time is a great avenger, and puts many +things and men in their proper places. + +Let us pause here a moment while we are speaking of Harvey. I should +be curious to know what any one of the courtiers of Charles I., bedecked +in feathers, ribbons and laces, would have said to the valet who would +have placed the excellent Harvey, with his insane invention, above his +most gracious majesty, the lord and king of all Great Britain! And yet +what is his most gracious majesty to you to-day? What do you owe to +him? in what does he interest you? While you can never hear the name +of Harvey pronounced without remembering that you are under many +obligations to him! A thousand years hence, when society shall have +made the great progress which may reasonably be expected, the name of +Harvey will be familiar to every one who owns a heart, while that of +Charles I. will be only a vanished shadow; a souvenir lost in the maze +of history. + +Our debt of remembrance paid, let us return to the heart--the little +closed bag which labors so prettily. We must now inquire the real names +of whatever has figured in our story. + +The two great compartments are called _ventricles,_ the two small +pouches _auricles,_ and they are also distinguished as being on the +right or left side;--_right ventricle, left ventricle, right auricle, +left auricle._ + +The inner doors on which depends all the action of the machine, are +called _valvelets._ By-and-bye, when the pump and the steam-engine +are explained to you, you will meet again with these treacherous doors, +which never allow what has once entered to go back again; but then we +shall call them _valves._ + +The air-reservoir, I need scarcely tell you, is the _lung,_ to +which the blood goes to put itself in contact with the air. + +The subterranean watercourse, of which I hope we have talked long +enough, is _the small intestine,_ in which the _chyle_ collects; and +the tubes which run into it are, of course, the _chyliferous vessels,_ +the only channels by which anything reaches the heart which has not +previously gone out from it. + +The tubes of distribution, which run out from the machine in all +directions, are called with us _arteries_; the return tubes, which +bring back the water to the machine, are called _veins._ + +Finally, we have not exactly the _filters_ employed to clear the +water from the impurities contracted as it goes along, for no such +thing exists in us. There are in our case the refuse-chambers of which +I have already spoken, in connexion with the liver, where the blood +disembarrasses itself of any useless materials, and from which it comes +out with clean pockets, so to speak, reverting to the comparison of +which we have already availed ourselves. + +As you see, then, everything comes round again; and the bright idea +which our professors hit upon in order to satisfy the caprice of the +banker is exactly carried out in your own body, only a thousand times +more perfectly than could have been done by them all, even with all +their science added to all his money. + +I mentioned that the shrewdest of the party boasted about making an +artificial heart. But, let me tell you, there is one thing I would +have defied him to imitate, by any expedient he could devise, and that +is the inimitable construction of the _arteries_ and _veins,_ and the +incomprehensible delicacy of their innumerable ramifications. + +Let us talk a little about these marvellous tubes, and begin with the +arteries, which have the most important part to play. + +Did you ever see a doctor try the pulse of his patient? Take hold of +your own wrist and search a little above the thumb. You will soon find +the place and feel something beating against your finger. There is an +artery which passes there, and the little beating you feel is the +rebound of the pulsations, of your heart. Every time that the left +_ventricle,_ by contracting itself, chases the blood into the arteries, +these, of which the tissue is very elastic, become distended all at +once, and then contract again, repeating the process whenever a fresh +gush of blood arrives, so that their movement is exactly regulated by +the movement of the heart. It is true the two movements are in a +contrary direction; that is to say, the artery becomes distended, while +the heart contracts, and contracts when the heart enlarges itself; but +that makes no difference to the doctor. What he wants to know is, with +what force and rapidity the heart of the patient beats, and I will +explain why. It is an interesting point in the history of circulation. + +When you were very little--very little indeed, my dear child--your +heart beat from 130 to 140 times in a minute. Afterwards the beats +sank to 100 per minute; then to fewer still. At present I cannot tell +you the precise number: perhaps, about ninety. When you are a grown-up +young lady, it will beat about eighty times in the minute; when you +are a mother, about seventy-three times; when a grandmother (if such +a blessing be granted you), only from fifty to sixty times, perhaps +even fewer. People tell of an old man of eighty-four whose heart beat +only twenty-nine times in the sixty seconds. + +Observe that in all my calculations I have taken special care to prefix +the word _about_ to the numbers mentioned. And this because, in +point of fact, the heart is a capricious creature, which has no exact +rules to go by. It changes its pace on every occasion--fear, joy, every +emotion which agitates the soul, quickens or retards its movements; +and derangements of health may be detected by its pulsations, which +are infinitely varied in character. In fever, for instance, which is +nothing but a race of the blood at full speed, the hearts of grown-up +people beat as quickly as those of little children; sometimes, indeed, +more quickly still. In certain maladies it goes with great sudden +leaps, like a galloping horse; in others it trots in little jerks; +while in some cases it moves slowly and wearily, and its throbs are +so weak that one can scarcely feel them. + +These pulsations, then, afford important revelations to the doctor. +The heart is for him a gossiping confidant, who lets out the secrets +of illnesses, however closely they may fancy themselves hidden in the +remote depths of the body. When the doctor lays his finger on the +patient's pulse, it is precisely the same thing to him as if he had +laid it on his heart, only with this difference, that the one is much +less difficult to do, and much sooner done than the other. + +The artery of the wrist is in fact a small heart, not only because it +follows all the movements of the large one, but because it carries +forward the work which the other begins, and assists also in propelling +the blood to the furthest extremities of the limbs, driving it on in +its turn at each of its own contractions. Imagine a fire-engine, whose +pipes should take up and drive forwards along their whole length the +water which is thrown upon the fire, and you will have some idea of +the marvellous machine which is at work in our behalf within us. Nor +are you to suppose that the wrist-artery is a specially privileged +one, because it has been chosen to hold intercourse with physicians. +All the others are equally serviceable; and if they cannot all be +used for "feeling the pulse," it is because they are generally more +deeply buried in the flesh, where it is not easy to reach them. + +Observe your mother when she is packing a trunk, and you will see that +whatever she is most afraid maybe spoiled, she is most careful to put +in the middle, so that it may be least exposed to accidents. And this +is what a kind Providence has done with the arteries, which have the +utmost cause to dread accidents; whilst the veins, which are much +better able to bear rough usage, are allowed to wander about freely +just under the skin. But when the bones happen to take up a great deal +of room, and come near the skin themselves, as is the case in the +wrist, the artery is forced, whether he likes it or not, to venture +to the surface, and then we are able to put our fingers upon him. + +And there are others in the same sort of situation; the artery of the +foot for instance. But only just think how far from agreeable it would +be to have to take off your shoe and present your foot to the doctor! + +The artery which passes to the temple, just by the ear, is another +affair. That would answer the purpose very well in fact, and I even +advise you to make use of it when you want to feel your own pulse. It +is more easily found than the other even, and its pulsations are still +more easily perceptible. Nevertheless, when all is said and done, it +is better for the doctor to take his patient by the hand than by the +head. Merely as a matter of good manners. + +I will now make you acquainted with the principal arteries, and the +manner in which they distribute the blood through the body. + +The whole of the blood driven out by the left ventricle at each of its +contractions, passes into one large canal called the _aorta_. The +_aorta_ as it goes away at first ascends; then bends back in a curve; +and from this curve, which is called the _arch of the aorta_ (from its +shape) diverge right and left, certain branch-pipes which carry the +blood into the two arms and on each side of the head; and which are, in +fact, the beginning, or upper end, of those whose pulsations we feel +with our fingers in the two wrists and at the temples. + +The supply to the upper part of the body being secured, the _aorta_ +begins to descend. But now imagine of what importance it must be, that +this head-artery--the foster-father of the whole body--should be +sheltered from every accident. The _aorta_ once divided, death is +inevitable; you might as well have your head cut off at once; and +thus it has been fixed in the best--that is to say, the safest--place. +Of course you know what is meant by the _backbone_ or _spine_, called +also the _vertebral column_, in consequence of its being made like a +sort of column composed of a series of small bones fastened together, +which are named _vertebræ_. Touch it and feel how solid it is, and how +few dangers there can be for anything placed behind it. Well, that is +the rampart which has been given to the _Aorta_. As this descends, it +slips behind the heart and takes up its place in front of the _vertebral +column_ which it follows all the way down the back, just to the top of +the loins. There it is, so to speak, almost unassailable; in fact hardly +any cases are known of the _Aorta_ being wounded; to get at it, it would +be necessary to bestow one of those blows which used to be given in the +time of the Crusades, which cut the body in two. There was an end of the +_Aorta_, as of every thing else then; it was unfortunately not worth +talking about any longer! + +The next time you see a fish on the table, ask to be shown the large +central bone. It is the fish's _vertebral column_, and it will give you +an idea of your own, for it is constructed on the same plan. You will +perceive a blackish thread running all along it--that is _the aorta_. + +As it descends, the _aorta_ sends off on its passage a great number of +arteries which carry the blood into all parts of the body. Arrived at +the loins it forms a fork; dividing into two great branches, which +continue their descent, one on each side the body, down to the very +extremities of the two feet. + +As you perceive, dear child, this is not very difficult to remember. +A large fork, whose two points are at the tips of the feet, the handle +of which curves at the top like the crook of a crozier; from this curve +come four branches, which pass into the two arms and to the two sides +of the head--and this is the whole story. But of course, it would be +another affair were I to enter into the detail of all the ramifications. +Here it is that all engineers, past, present, and future, are baffled, +defeated and outdone! Choose any place you please upon your body, and +run the finest needle you can find into it what will issue from the +puncture? + +"Thanks for the proposal," you say; "I have no occasion to try the +experiment, to discover that blood will come out." + +You say that very readily, young lady; but have you ever asked yourself, +what is implied by your being so sure before hand that you can bring +blood from any part of your body if you choose to prick it, though +never so slightly? It implies that there is not on your whole frame +a spot the size of a needle's point, which has not its own little canal +filled with blood; for if there were such a one, there at any rate the +needle would pass in without tearing the canal, and causing the blood +to flow out. And now count the number of places from the top to the +bottom of your dear little self, on which one could put the point of +a needle, and even when you have counted them all, do not fancy you +have arrived at the number of the tiny tubes of blood. Compared to +these, your needle is a coarse stake, and tears not one but a thousand +of these little tubes in its passage. + +That seems to you rather a strong expression, does it not? But let me +make good my boldness. A needle's point is very fine, I admit; but a +person who could not see it without spectacles must have very poor +sight. Whereas the last subdivisions of the blood-tubes are so +attenuated, that the best eyes in the world, your own included, cannot +distinguish them. You are astonished at this, and yet it is nothing +compared to what follows. + +No doubt you have heard of the microscope,--that wonderful instrument +by which you may see objects a thousand, a hundred thousand, a million +times, if necessary, larger than they really are. With the microscope, +therefore, as a matter of course, we can see a good many of those tiny +canals which elude our unaided sight. But, alas! we discover at the +same time that these are by no means the last subdivisions. The canals +invisible to our naked eyes subdivide themselves again into others, +and these into others again, and so it goes on, till at last--the man +at the microscope can see no more, but the subdivisions still continue. + +You were ready to exclaim, at my talking of thousands of canals being +torn by a needle in passing through; but had I even said millions, it +may be doubted whether I should have spoken the whole truth. + +Besides, when you consider the office of the blood, you can easily +understand that if there were a single atom of the body left unvisited +by him, that atom could never be nourished. Do I say nourished? I have +made here a supposition altogether inadmissible; it could have no +existence at all, since it is the blood only which produces it. + +These imperceptible canals of blood have been called _capillaries_, +from the Latin word, _capillus_, which means a hair; because the +old learned men, who had no suspicion of the wonders hereafter to be +revealed by the microscope, could think of no better way of expressing +their delicacy, than by comparing them to hairs. Very likely they +thought even this a great compliment, but your delicate fair hairs, +fine as they are, are absolute cables--and coarse cables too, believe +me, compared to the _capillary vessels_ which extend to every portion +of your body. + +Observe further, that each of these arterial _capillaries_ is +necessarily composed (being the continuation of the large ones) of +three coats enclosed one within the other, which can be perfectly +distinguished in arteries of a tolerable size; add to this that within +these coats there is blood, and in the blood some thirty substances +we know of, not to speak of those we do not know; and then you will +begin to form some notion of the marvels collected together in each +poor little morsel of your body, however minute a one you may picture +to yourself. + + + +LETTER XV. + +THE NOURISHMENT OF THE ORGANS. + +When I said formerly that our dear and wonderful steward the blood, +was everywhere at once, you little suspected the prodigies involved +in that _everywhere_. But you will have a glimpse of them now, when I +tell you it is at the extremities of the _capillary arteries_ that he +carries on his distribution of goods, and accomplishes a mysterious act +of nutrition; a wonder much greater even than that of which we have just +spoken. Here, indeed, the question is no longer mechanical divisions, +whose delicacy, surprising as it may be, is yet within our powers of +comprehension. What is more surprising still, what moreover we cannot +comprehend at all, is the delicate sensitiveness of tact--I would almost +say of instinct--with which each one of the million millions of tiny +atoms of which our body is composed, draws out of the blood--the common +food of all--exactly that aliment which is necessary to it, leaving the +rest to his neighbor, and this without ever making a mistake. + +You have never thought about this; for children go on living at their +ease, as if it was the simplest thing in the world to do; never +suspecting even that their life is a continued miracle, and never, of +course, therefore, feeling bound to be grateful to the Author of that +miracle. And alas! how many hundreds of people live and die children +in that respect. + +But what would happen, I should like to know, if the eye took to seizing +upon the food of the nail, if the hairs stopped on the way what was +intended for the muscles, if the tongue absorbed what ought to go to +the teeth, and the teeth what ought to go to the tongue! Yet what +prevents their doing so? Can you tell me? They all drink alike out of +the same cup. The same blood goes to furnish them all. The substances +that it brings to the eye are the same as those which it brings to the +nail; and nevertheless the eye takes from it that which makes an eye, +and the nail that which makes a nail. + +How is this done, do you think? that is the question. + +When the doctors reply to this, that each organ has its peculiar +sensibility, which makes it recognize and imbibe from the blood one +particular substance and no other, they are strangely mistaken if they +flatter themselves that they have really answered anything. They have +done nothing but reproduce the question in other words, for it is +precisely that sensibility which requires explanation, and to tell us +that it exists, does not explain much, you must own. If you were to +ask why you had got a headache, and some one were to reply that it was +because your head ached, you would not be much the wiser I fancy. + +Each of our organs, then, may be considered as a distinct being, having +its separate life, and its particular likings. These organs behave +towards the blood like men who recognize some friend in a crowd, and +proceed to seize him by the arm; and when I told you just now that +they never made a mistake, I spoke of their regular course of action +in ordinary circumstances. Like men, they also make mistakes sometimes, +in certain cases; and take one substance for another, or do not +recognize the one they are in need of; an unanswerable proof that at +other times they exercise a sort of discernment, and do not act by a +sort of fatality, as one might be tempted to believe. Look at the +bones, for instance. They are composed of _gelatine_ (which cooks +serve up under the name of meat-jelly, but which would be more properly +called bone-jelly), and of phosphate of lime, a kind of stone of which +we have spoken before, if I remember rightly, and from which they get +all their solidity. Originally, the substance of the bone is entirely +gelatinous, and the phosphate of lime deposits itself therein by +degrees, as time goes on, and always in greater abundance as we advance +in age. + +Properly the bones borrow only gelatine and phosphate of lime from the +blood. But when they come to be broken, their texture or _tissue_ +inflames in the fractured place; and then it changes its tastes, if +I may so express myself; and, lo and behold, extracts from the blood +that which forms certain little fleshy shoots, which unite together +from the two sides of the fracture, and so mend the broken bone. Here is +one exception to the rule. + +Again, in certain diseases, the bones suddenly quarrel with the +phosphate of lime; they will not hear of it any longer, they will not +accept a fresh supply; and as the old wears out by degrees, by reason +of the continual destruction of which I spoke the other day, the bones +become more and more enfeebled, and soon can no longer support the +body. A second exception this. + +Finally, when old age comes on, the bones end by being so much +encumbered with phosphate of lime, that they have no room to admit the +fresh supply which keeps coming to them in the blood. What becomes of +it then? It goes to seek its fortune elsewhere; and there are charitable +souls, who forgetting their instinctive antipathies, consent to give +it hospitality, though much to the prejudice of the poor old man +himself, who is no longer served so well as formerly, by the incautious +servants who have allowed themselves to be thus fatally beguiled; but +no one consults him. It is the arteries especially, and sometimes +the muscles, which take this great liberty, and it is not unusual among +old people to meet with these fairly _ossified_--that is to say, +changed into bone, thanks to the phosphate of lime with which they +have consented to burden themselves. This is a third exception, and +I will spare you any others. + +What may we infer from all this, my dear child? Well, two things. +First, that we know nothing at all about the whole affair; a fact which +at once places us on a footing with the most learned philosophers in +the world. Secondly, that our body is a perpetual miracle; a miracle +which eats and drinks and walks, and which we must not look down upon +for so doing: for God dwells therein. I should have to come back to +this at every turn, if I wanted to fathom everything I have to tell +you about. Each tip of hair which you grow, is an incomprehensible +prodigy which would puzzle us for ever, if we did not call to our aid +those eternal laws which have made us what we are, and to which it is +very just our spirits should submit, since we could not exist for one +second were they to cease from making themselves obeyed in our bodies. + +Reflect on this, my dear little pupil. Young as you may be, you can +already understand from it, that there is above you something which +demands your respect. The good God, to whom your mother makes you pray +every night, on your knees, with folded hands, is not so far off as +you might perhaps suppose. He is not a being of the fancy, secluded +in the depths of that unknown space which men call Heaven, in order +to give it a name. If His all-powerful hand reaches thus into the +innermost recesses of your body, His voice speaks also in your heart, +and to what it says you must listen. + + + +LETTER XVI. + +THE ORGANS. + +Contrary to my custom, my dear child, I made use, in the last chapter, +of a new word, without giving an explanation of it. + +I spoke to you of _our organs_, and we have not yet ascertained what an +_organ_ is. + +You probably knew what I meant, because it is a word which is used in +conversation and pretty well understood by everybody. But I am bent +upon giving you a more exact idea of it, for the trouble will be well +bestowed. If I did not do this at once it was because there is a good +deal to tell about, and that would have carried me too far away from +my subject. + +_Organ_, comes from the Greek word _organon_, and means _instrument_. It +was used particularly to signify instruments of music, so much so that +our word "organ" comes from it. Our bodily organs then, are +_instruments_, or _tools_ if you like it better, which have been given +to us, wherewith to perform all the acts of life; and as there is not +one part of the body which is not of use to us for some purpose or +other, our body is, in point of fact, from head to foot a compound of +_organs_. Thus the hand is the tool which we make use of to lay hold of +anything--so an _organ_; the eye is the instrument of sight--so an +_organ_; the heart is the machine which causes the blood to circulate--so +an organ; the liver fabricates the bile--it is an organ therefore; +the bones are the framework which support the weight of the body--so +organs; the muscles are the power which sets the bones in movement--organs +also, therefore; the skin is the armor which protects them--so an +organ: in fact everything within us is an organ. If there was any corner +of our body which was not an organ, it would be useless to us, and we +should not, therefore, have received it, because God makes nothing +without a use. + +Here lies the secret of that great miracle which is called life. I do +not know whether you will be able to understand me thoroughly, but +open your ears, as if some one was going to explain addition to you; +this is not more difficult. + +Life is in reality the total of an addition sum. Each one of our organs +is a distinct being which has its particular nature and special office; +its separate life consequently; and our individual life is the sum +total of all these lesser lives, independent one of the other, but +which nevertheless blend together by a mysterious combination, into +one common life, which is everywhere and nowhere at the same time. It +follows from this, that the more organs a being has, the greater is +the sum total; the more, consequently, is life developed in him. +Remember this when we begin to study life in the lower animals. In +proportion as you find the number of _organs_ diminish, you will +find life diminishing in power, until we arrive at beings who have, +as it were, only one organ apparent, and whose life is so insignificant, +that we have some difficulty in giving an account of it, and are saying +the utmost that can be said in calling it life at all. + +But this comparison of life to the total of an addition sum, is too +dry; and, although it has its appropriate side, yet it might give you +a false idea of life; which is what always happens when one tries to +solve inscrutable questions and hidden mysteries by a matter-of-fact +illustration. + +Let us try for something more to the purpose. + +I told you that the Greek word _organon_ was applied especially +to instruments of music. Well, let us consider our organs as so many +musical instruments. You have, probably, sometimes been at a concert. +Each of the instruments in the orchestra performs its own part, does +it not? The little flute pipes through all its holes; the double-bass +pours thunder from its chords: the violin sighs with his; the cymbals +clash; the Chinese bells dance to their own tinkling; all go at it in +their own fashion, each independently of the other. And yet, when the +orchestra is in good tune together, and well played, you hear but one +sound; and to you the result of all these various noises, each of which +would have no meaning alone, is music composed by some great artist +whom you do not see. It is no longer a flute, a double-bass, or a violin +which you hoar; it is a symphony of Beethoven's, an oratorio of Haydn's, +or Mozart's overture to _Don Juan_. + +Life is just like this. All the instruments are playing together, and +there is but one music; music written by God. + +But wait! when I say _life is just like this_, let us come to an +understanding. Life is _some_thing like it, that is all, for as +to telling you what life is, I shall not attempt it. I know nothing +about it, do you see, though that is a painful confession to have to +make to a pupil; but in this case it does not distress me, and you are +welcome to hunt the world through for a master, who in this matter +does know anything. I could make a hundred other comparisons, but +theywould all fail in some point or other. Shall I tell you where this +one fails? In an orchestra there is always a musician by the side of +the instrument. Now with us we see the instrument well enough, but we +cannot see the musician. + +You are inclined to ask me, perhaps, why I am wasting so much paper +to-day in talking to you about organs, instead of going on tranquilly +with our little history of the circulation. But I told you just now +that the secret of life lies in the organs, and before entering upon +the history of life, I ought to have begun with them. It is there all +the books begin which treat of the subject we are studying together, +and if you had one in your hands at this moment, it would teach you +that all creatures whatsoever are divided into those which have organs +and those which have none--that is, into _organic_ and _inorganic_ +beings [Footnote: A lump of iron is the same throughout. Each of its +parts has the same properties and the same uses. It has no organs, it is +an _inorganic_ being. A rose tree has flowers, which are differently +made from its leaves, and serve a different use: a root which sucks up +the precious food of the earth; a bark which is of a different nature +from the wood, and serves a different purpose. It has organs; it is an +_organic being_: all animals and vegetables are _organic beings_.] (_in_ +stands here for _not_, as _in_complete means not complete). + +This is, in fact, the starting point for the study of nature, and there +are many other things besides which I ought to have told you before +I began. But we went straight ahead, without looking at what we were +leaving behind, satisfied with turning aside from time to time to pay +our debts. + +And while I am making my confession, I ought to tell you all. You would +probably only have listened to me with half an ear, if I had begun at +the beginning. There is a proverb which says--"The appetite comes with +eating." I do not advise you to follow this proverb too closely at +dinner, for it might mislead you sadly. But it is always true when +applied to learning; it is what one knows already that gives one a +taste for learning more. If I have been making you bite at the organs +to-day, which is rather a tough morsel, it was because I fancied that +your appetite had begun to come. Was I wrong? + +Let us now return to the blood which nourishes the organs. + + + +LETTER XVII. + +ARTERIAL AND VENOUS BLOOD. + +It is at the extremity of the capillary arteries, as we have said, +that the incomprehensible prodigy of the nourishment of our organs is +accomplished. This done, the next thing is for the blood to return to +its starting-point; and here recommence those infinitesimally minute +wonders of which we have already spoken. Close upon the capillary +_arteries_ follow the capillary _veins_, equally fine and imperceptible +as the others. These take possession of the blood everywhere at once, +without allowing it a moment's respite, and it is thenceforth on its +road of return, travelling back again to the heart. + +Where do the veins begin? where do the arteries end? No one can say +precisely, since the last ramifications of each elude the eye of man, +however much it may be aided by the admirable instruments which his +genius has invented. Nevertheless, although no one has ever ascertained +the fact by sight, there is one thing I can tell you--namely, that our +minute veins are a continuation of our minute arteries, and that it +is the same canal which as it lengthens out turns from an artery into +a vein, without any interruption; the substances destined for the +nourishment of the organs passing through its walls, as moisture passes +through our skin when we perspire. + +But if nobody has seen this, say you, how can they know it for a fact? + +Let me explain. In man, and in the animals which come nearest to man +in structure, it has never been seen; but it has been seen elsewhere. +This requires a little explanation, and you will not regret my giving +it hereafter. It has its interest, I assure you. + +When you put your hand on your throat, how does it feel to you? +_Warm_, does it not? And when you take hold of a kitten or a bird, +how do they feel? _warm_ in the same way. Now, then, can you tell +me whence comes this warmth? But to save time I will answer the question +myself. It comes from their and your _blood_, which is itself warm, and +we shall soon see why. You have no idea of all the curious facts wrapt +up in that little phrase, "You are warm-blooded;" your blood is warm. +But it has not got warm of itself; bear that well in mind. + +Now if you touch a frog, a lizard, or a fish, how do they feel to you? +Cold, of course, you answer. But I ask why? A question you will answer +in the same way as the other. Because their blood is cold, they are +"cold-blooded." + +Precisely; and while you are about it you may add that, if their blood +be cold, it is because it has not been warmed as yours is. Do not be +impatient, we shall make all this clear at the proper time and place. + +Now in the cold-blooded animals, such as serpents, frogs, tortoises, +lizards, fishes, and others, the blood circulates as it does in us, +and what is more, it does so, thanks to a machinery very similar to +our own. But, as you may imagine, a machine which produces warmth must +be constructed in a more perfect manner than a machine which produces +no warmth; and to speak truth, without flattering you, there is a +little difference between you and a frog, and it seems natural enough +that the body of a frog should be more clumsy in structure than yours. + +It is the old story of the poor man being not so well lodged as the +rich; but putting aside rich and poor, who are all human beings alike, +let us take one of those lovely dolls who walk, and move their arms +and head, and say papa! and mamma! and compare it with a cheap bazaar +doll which you can get for a penny. Both are made, in the main, in one +way. Each has two arms, two legs, a mouth, a nose, eyes, &c.; but what +a difference in the details of the two! and what infinitely more pains +have been bestowed on one than on the other! + +Well, cold-blooded animals are, so to speak, _penny doll_ animals, +by comparison with ourselves. Like us they have arteries and veins, +but there is not near so much workmanship in them; and that marvellous +delicacy of the capillary extremities, which in man and in the +warm-blooded animals drives the close observer to despair, does not +exist to trouble us in these others. It is true that with the naked +eye we are still unable to see everything, even in them; but with the +help of the microscope the whole is laid open to us--the extremities +of the arteries and the extremities of the veins; and it was here that +what I was telling you of, just now, was observed and discovered,--namely, +that the end of the artery changes into a vein, without any +interruption in the tube. It was these very observations upon fishes and +frogs, which eventually gained the day in favor of Harvey's ideas on the +circulation of the blood, at which the learned men of his own age had +laughed so much. He was dead by that time it is true, as has happened +but too often in such cases, but do not let us pity him too much! He who +has had the rare good-fortune to lay hold of a new truth, and launch it +into the world, is sufficiently recompensed in advance. If he also +craves after the flattering voice of man's approbation, and the toylike +pleasure of personal triumph, he is after all but a child, unworthy of +the great part God has given him the privilege of playing. + +A child, did I say? Then how rude you must have thought me, dear child! +And as a punishment, you are perhaps going to remind me that I have +once more fallen into my old bad habit of wandering away from my +subject. Never mind, I am going to return to it at once. + +How can one distinguish--you will ask me--an artery from a vein, so +as to be able to determine which is a vein and which an artery? + +In many ways, I reply. First of all, an artery, as I told you lately, +is composed of three coats, of which the principal, _i.e._. the +inner one, is tough and elastic, whereby the artery is enabled to force +the blood forward in its turn, but which is also the reason of arterial +cuts being so dangerous; for in such cases the wounded tube remains +wide open; being held so by the stiffer inner coat; and thus the blood +is allowed to run out indefinitely. Now this inner coat is wanting in +the veins, whose walls sink in together when a cut is made in them, +so that it is much easier to stop the flow of the blood in them. + +Furthermore, the veins are furnished inside at intervals with little +doors, similar to those we noticed at the entrance of the _auricles_ and +_ventricles_ of the heart. You remember those important _valvelets_, on +which depends so much of the mechanism; which permit the blood to pass +in one direction, but will not allow it to return back in the +other?--well, the little doors of the veins, which are also called +_valvelets_, do exactly the same work. They open in the direction of the +heart, to allow the blood to pass on, but it finds them fast closed if +it wants to go back; so that as soon as it has forced one passage there +is no longer any hope of its return, and thus by degrees it gets nearer +and nearer to the heart without any possibility of escape. There is +nothing similar to this in the arteries, which the blood traverses in a +single bound from the impetus it receives from the heart. + +Finally--and this is most important--the blood which is found in the +veins is no longer the same as that which fills the heart. + +No longer the same? you exclaim--have we then two sorts of blood in +our bodies? Most certainly, my dear child; but you would not have +suspected it; for when you accidentally prick or cut yourself, or when +your nose bleeds, it is always the same sort of blood that comes +out--that fine red liquid which everybody knows so well by sight. This +is because the blood flows at once from the small arteries and small +veins, and what you see is a mixture of the two. The same mixture +issues from all wounds, whether small or great, and on this account +people are unanimous in declaring that blood is red; a statement which +is not true of either arterial or venous blood, separately. The last +is black, as you might convince yourself if you had courage enough, +and should happen to be in the room with any one who was going to be +bled,--a rare event, happily, in these enlightened days. + +In such a case it is always a vein which is opened, the reason of which +you will understand, after what I said of the danger of cutting the +arteries. You would there, fore see a reddish black jet of liquid spout +from under the lancet; much blacker than red, however--that is +_venous_ blood. When, on the other band, an artery has been accidentally +cut, what comes out is quite different. It is a rosy, frothy fluid, +almost like milk and carmine dissolved in it, which has been whipped up +with a stick; this is called _arterial_ blood. + +Nothing is more simple, as you perceive, than to distinguish an artery +from a vein; you have only to ascertain what is inside of it. When the +blood goes out to our organs to nourish them, it is _arterial_; when it +is returning back after having nourished them, it has become _venous_. +But what--you will ask--is it going to do now at the heart, towards +which it is on its road? It is going to seek there a fresh impetus which +shall send it once more into the lungs, where it will again become +_arterial_, _i. e._ and once more capable of affording nourishment to +the organs. Therein lies the whole secret, and the why and the wherefore +of the CIRCULATION. + +This is easily said, dear child; but suppose that you do not comprehend +it? Well, you need not be ashamed. There is no possibility of +comprehending it until one has learnt what RESPIRATION is--so here we +are stopped short. + +To-morrow, then, when we will begin with the study of this third part +of the History of Nutrition; and if the first two have amused you, I +feel pretty sure you will not find this last one dull. + + + +LETTER XVIII. + +ATMOSPHERIC PRESSURE. + +When we have been laboring very hard, my dear child, and want to rest +for a minute, we say, _Let us take breath_; because breathing is +an action which takes place of itself, requiring neither effort nor +attention on our part. + +But, if it takes place of itself, it does not explain itself; +consequently, when I say to you, _Now, let us take breath_, this +is not a signal for my having a rest, for I have undertaken to explain +Respiration to you. + +If you were a German, I would remind you of what so often happens when +you put a fork into a dish of sour-krout. You want to lay hold of a +little bit merely, but the strips of cabbage-leaf are twisted one +within the other, and hang together in spite of you, so that +withoutintending it you get hold of a whole plateful at once. + +Now this Respiration affair is something like the sour-krout +story--begging your pardon for the comparison. I should have liked to +give you only a small plateful--a child's plateful--of it; but I feel +the explanations coming, hanging one upon the other; and, whether I +will or no, I must treat you like a grown-up person, and we must give +up for once the nice little doll's dinners with which we began. + +In my opinion, you will lose nothing by the change if you will but pay +attention; for about that soft little breath of yours, which is always +coming and going over your pretty lips, there are many more things to +be learnt than you have heard of yet. As I said just now, you will +find you have got hold of a plateful all at once. A good appetite to +you! + +To prevent confusion we will divide the subject into two parts. I shall +explain to you first, _How we breathe?_--a very curious question, +as you will see. And afterwards we will examine, _Why we breathe?_--which +is still more interesting. + +First, I must tell you that air is heavy, and very heavy too; a thousand +times more so than you may suppose. The air we breathe, through which +we move backwards and forwards, that air is _some_thing, remember, +although we do not see it; and when there is a wind, that is to say, +when the air is in motion, like a stream of water running down a hill, +we are forced to acknowledge its being something, for we see it throw +down the largest trees and carry along the biggest ships. But without +going so far out of the way for examples, try--you who run so well--to +run for two minutes against a strong wind: and then you shall tell me +whether the air is something or nothing. But if it be something it +must have weight, for all substances have; paper as well as lead; with +this sole difference, that the weight of lead is greater in proportion +to its size than that of paper. Now a sheet of paper is very light, +is it not? and you would be puzzled perhaps to say what it weighs. But +many sheets of paper placed one upon the other, end by forming a thick +book which has its undeniable weight; and if some one were to heap +upon your head a pile of large books, like those you see on your papa's +shelves, the end might be that you would be crushed to death. + +In the same way, a small amount of air is by no means heavy; but you +can conceive that a great quantity of it gathered together may end by +weighing a great deal. Now get well into your head the fact, that we, +here, on the surface of the earth, are at the bottom of an immense +mass of air, extending to somewhere about forty or fifty miles above +our heads. Let us say forty to make more sure, for learned men have +not yet been able to calculate the precise height to a nicety; and for +my own part, I think we have done wonders to get so near the mark even +as this. But can you picture to yourself the distance which forty miles +high really is? I will help you to form some idea. + +One mile contains 5,280 feet, and your papa is six feet high. One mile +high would therefore be 880 times as high as your papa, But this is +a mere nothing--only one mile's height. In forty miles there would be +no less than 211,200 feet; and setting papas aside, of whom it would +take 35,200, one on the top of the other, to go so far into the sky, +let us think of the height of the tallest buildings you know; church +and cathedral towers for instance. Now the towers of many parish +churches are 150 feet high; the towers of York Minister not 300. At +that rate it would take 1,408 ordinary parish church-towers, or upwards +of 704 York Minster towers, piled one above the other, to reach to the +end of the forty miles of air above our heads. I leave you to judge +what would be the weight of a mass of paper piled up as high as that. +You may safely grant then, that this mass or pile, or if you like it +better, this _column_ of air (for that is the proper expression), +must be of considerable weight; as is still further made certain by +the fact of its having been weighed, so that I can even name the weight +to you if you wish to hear it. Bear in mind too, that the weight of +a column of air will be in proportion to its _superficial extent_--to +its breadth and width, that is; for, as you may suppose, a column as +large in extent as one of the towers of York Minster will weigh a good +deal more than one the size of a single brick. + +But wait; here is a book on the table which will serve me for a measure, +and as you will probably find the same on your mamma's table, you can +follow my measurement. It is a French Grammar. The back is seven inches +long and four and a quarter wide. That is, there are four and a quarter +rows, each seven inches long. In other words, the back contains +nearly--and let us call it quite, for convenience' sake--thirty inches +side by side. Thirty _square inches_ as it is called. Measure your +mamma's copy and you will see. Now, can you guess the weight of the +column of air forty miles high which this volume supports? Upwards +of four cwt.; 450 lbs., that is to say. If you want to be very exact, +here is the rule. Air presses on all bodies at the rate of fifteen +pounds to every square inch; so now you can make the calculation for +yourself. + +But I suspect you had no idea you were so strong; for I see you tossing +up the book, heavily laden as it is, like a feather. + +Comfort yourself. There is no magic in the matter. If a very strong man +were to push you on one side, could you resist him? Certainly not. But +if another man of equal strength were to push you at the same time on +the other side, what would happen? Well, you would remain quietly in +your place, without troubling yourself more about one than the other, +the two forces mutually destroying each other. And this is the case +here. While the air above your book is weighing down upon it with a +force of 450 lbs., the air below it presses against it underneath with +an equal weight, and this destroys the effect of the other. From 450 +lbs. take 450 lbs., and nothing remains. Your grammar has nothing to +carry after all, and you may toss it about as you please, without +deserving much credit for the effort. + +"What are you telling me?" you inquire. "If I put a stone on the top +of my head, I can feel its weight easily enough; but if I put my hand +on the top of the stone I no longer feel anything. How can the air +below the stone press against it? And talking of columns--how pleasant +it would be, for instance, if the people who go up the Monument were +to have the weight of it on their heads when they get to the top!" + +Well said, little one. And your objection reminds me of an argument +which distracted my head as a lad, when I first heard the pressure of +air explained by a good fellow who did not trouble himself to be quite +as exact as you and I are in our discussions. I was told that the +surface of the body, or the skin of a large man, measured sixteen feet +square, which is equal to the surface of a table four feet long and +four broad. Now, you know that in four feet there are forty-eight +inches, and on the surface of the table are forty-eight rows, with +forty-eight inches in each, or 2,304 square inches; so that a man's +surface is 2,304 square inches, and the weight his body supports is +34,560 lbs., or upwards of fifteen tons--always at the rate of fifteen +pounds to every square inch, you understand. Now, I was constantly +asking myself how it happened that in entering a house one never seemed +to get rid of this almost fabulous weight, since the roof of the house +must naturally interpose itself between the air-column of forty miles +high and the man who would then only have some few feet of air above +his head. The roof would support the rest, that was clear. From whence, +then, came the 34,560 lbs. which seemed to weigh as heavily as before; +since, whether on the threshold of the door, while still under shelter +of the roof, or two steps outside in the open air, under the tremendous +column forty miles high, one never felt a bit lighter, not even to the +extent of the weight of a single sheet of paper? This was a difficulty +from which I could never extricate myself. + +I found out the answer to the riddle afterwards, and a very simple one +it is. + +Air does not, in point of fact, _weigh down_ like a solid fifty +pounds' weight, which has no impulse but to descend, and has nothing +to do with anything above it. It _presses against_ rather, like +a spring, which, having been compressed, tries to resume its natural +position with a force equal to that which holds it back. Ask some one +to show you the spring of a watch, and you will understand this better. +Each atom of air is a spring of matchless elasticity, which nothing +can break, which never wears out, which one can always compress, if +one employs force sufficient, and which is always ready to expand +indefinitely, in proportion as the compressing power is withdrawn. + +Now, consider the column of air outside the door, where there is a +pile of such springs forty miles high. The lower ones have to bear up +all their comrades, which press upon them with their united weight, +and these make desperate efforts to repulse the tremendous pressure, +and to spread out in their turn. They endeavor to escape in every +direction--to the right, to the left, above, below; but caught between +the earth, which will not give way, and the compact mass of all the +columns of air which surrounds the earth in every direction, and of +which the lower part is equally compressed everywhere, they struggle +unceasingly, but in vain; indefatigable, but powerless. You live in +the midst of those little wrestlers, and naturally bear the punishment +of the injury done to them. They press against you as against every +thing else--before, behind, on all sides--with a force equal to thatwith +which they are themselves compressed, or I would say, equal to +the weight by which they are so horribly squeezed and contracted: so +that, in fact, you bear this weight not only on your head and shoulders, +as you might at first suppose, but also all along your body and limbs, +under your arms, under your chin, in the hollow of your nostrils, +everywhere. + +Now we will suppose you to enter the house; and what do you find there? +Outer air, which on its part has got in by the door, the window, and +every little crevice in the wall. The column outside the roof no longer +presses upon it, but what is the gain of that? + +It was compressed when it got in, and the little springs will struggle +as a matter of course, quite as much on this side of the door as on +the other. The protecting roof has so little power that were it not +itself protected by the air outside, the pressure of which keeps it +in its place, the air within would shiver it into a thousand fragments +in its efforts to get loose. + +You laugh; but wait till I explain myself further. I will take the +case of a miniature house to make the matter pleasanter to you; one +fifteen feet long, fifteen feet wide, and with a flat roof, the most +economical plan as regards space. Fifteen feet are five yards, and as +the multiplication table tells us that five times five make twenty-five, +our roof will in this case be twenty-five square yards (_i. e._ +225 square feet) in superficial extent, or _area_; it is not much, +and you will find few as small. + +Would you like to calculate the force with which the millions and +thousand millions of little spring imps imprisoned under that poor +unfortunate roof would press against it? We settled before that the +quantity of them brought to bear upon a square inch had the power to +push at the rate of fifteen pounds. Were they to push against a square +yard (a surface 1296 times greater than the square inch) it would +therefore be 19,440 lbs. This being so for one square yard, calculate +for twenty-five square yards, and you will have the amount of pressure +against our roof--viz. 486,000 lbs--merely that! And now tell me what +cottage roof in the world was ever built so as to be able to stand +against such a weight? + +Perhaps though, you can scarcely appreciate the amount of heaviness, +486,000 lbs. Well, 486,000 lbs. is nearly 217 tons; and one of those +railway trucks that you see laden with coals at the stations can carry, +perhaps, from eight to ten tons, without breaking down. Say ten tons +as an outside estimate, and then think of piling the contents of +twenty-one such trucks on your roof, and yet you would still be short +of the weight of air which is bearing down upon it. I need scarcely +say now that were you to take away the air from within the roof, theair +without would smash both it and the whole cottage flat, as a giant +at a fair strikes an egg flat with one blow of his fist. To show you +how in another way: take a moderate sized column or pillar, such as +you see sometimes in a nobleman's grounds, of about the weight of the +twenty-one tons, and set it up like a chimney on the roof of our +cottage, then walk away to a little distance and watch what will happen! + +There, little Miss Laugher! have you at last learned to value the +weight of the air, or _atmospheric pressure_ as it is more properly +called; since it is the force with which the atmosphere presses against +rather than weighs upon everything on the surface of the globe? It is +no joke, as you perceive, and it affords plenty of subject +forreflection. I have still to prove to you that I have not been making +fun of you with my calculations, and that the weight of air upon a +square inch is really what I have said--viz., fifteen pounds. + +Now, there is a very simple way by which we might get to know your +strength, and tell its amount in figures, if one chose; namely, by +putting a weight on your arms--a heap of books, if you please--and +keep adding and adding to it, until those poor little arms were unable +to bear any more. Then weighing what they had borne, whether we should +find it to be ten or thirty pounds--I cannot guess how much it might +be at this distance--one might safely say, without fear of mistake, +"The strength of this young lady is equal to ten, twenty, or thirty +pounds"--in other words, "she represents a weight of ten, twenty, or +thirty pounds" and by a similar plan people have ascertained the +strength of the air--that is, the weight which it represents. They +have weighed what it is capable of carrying. + +I told you lately that the whole surface of the earth was covered by +an immense army of little imps--otherwise called little air-springs, +which, compressed by the giant mass of their comrades above, all of +whom they have to carry on their backs, are always trying to protect +themselves, by pushing back everything which comes across them. Imagine +the bottom of a well. Our imps are permanently installed there as a +matter of course, and face to face with the water they push against +it, each one doing his best, on all points at once. As the pressure +is equal everywhere therefore, and always the same, there are no signs +of it to be seen. + +Now insert in the water the end of a tube closed below by a cork which +exactly fits the interior, but which can be moved up and down in the +tube by means of a bar of iron or wood which runs through it. This is +called a _piston_, I may as well tell you as we go on. + +When the piston rises in the tube, it drives before it, as it goes, +the air which was already there; and which cannot slip away down the +sides because the piston fits so closely to them all the way along. +The result of this is, that just underneath the piston there is a place +in the water to which the air cannot reach, and at that place the water +has no pressure upon it at all. + +Now see what happens. Pressed upon heavily by the air in every other +part and place, like a mouse hunted by a cat, who finds at last a hole +through which to escape, the poor water darts at this and ascends the +tube close after the piston. + +So far so good; but if the tube is very long, and the piston rises +rather high;--at thirty-three or thirty-four feet above the level of +the water it has to continue its ascent alone. The water parts company, +stopping quietly behind, half-way up the tube. + +"What is the meaning of this?" you will ask. + +It means that the force which presses on the well-water all round the +tube, and thus drives it up, has done all it can, and that our little +air-imps refuse to supply any more. The water which rises in the tube +has a weight of its own of course, and with this weight it presses, +as it is fair it should, on the water below. In proportion as the +piston rises, the column of water which follows it gets bigger and +bigger, and naturally its weight increases at the same time. At last +there comes a moment when this weight becomes such that its pressure +on the water below is equal to that with which the air-imps are pressing +on the water in the well. Thenceforth they may push as they please; +no more water will go up. They are in the same position now that they +were before, when their comrades (afterwards driven out by the piston) +were pressing upon the same point, which had only a moment's freedom; +and this water column of thirty-three or thirty-four feet holds them +in check, to exactly the same extent as the gay fellows whose place +it has taken. + +Nothing is easier now than to calculate, even to a few grains almost, +the force of the pressure of air. One can get at the weight of water, +thank goodness! and it has been ascertained that our water-column will +weigh fifteen pounds if the tube is a square inch in size. You will +comprehend after this that it might be any size you may please to +imagine, without there being the slightest alteration in the height +of the column. The larger it is, the heavier will be the column of +water on the one hand; but on the other, the greater will be the number +of air-imps turned out; so it comes to the same thing in the end. + +If you should feel any doubt about the correctness of this reasoning, +you have only to try the experiment over again, in a well, filled with +mercury for instance. Ask to be shown some pure mercury, which is also +called _Quicksilver_, because one wants to express melted silver, +apt to be constantly on the move; it is often to be met with in houses. +Mercury weighs thirteen and a half times more than water: according +to our calculations, therefore, it would take thirteen and a half times +less of it than of water to bring our little air-imps to reason. And +this is just what you will find happens; you will see the column of +mercury stop short exactly at the moment when it has attained the +orthodox weight of fifteen pounds; that is to say, at a height of +twenty-eight inches. + +On the other hand, take some ether. You know that delicate spirit, +which smells so strong, which makes your hand feel cold if it is put +upon it, and which we give to sick people to inhale. Ether weighs +one-quarter less than water. In a well of ether you would therefore +see something quite different, and your column would rise without being +asked, to something like forty-three feet, exactly up to the point of +weighing--like the others--fifteen pounds to every square inch. Air +will not be replaced with less. + +That, then, is the measure of its strength, or our scales are deceitful. + + + +LETTER XIX. + +THE ACTION OF THE LUNGS. + +I hope I have told you enough, my dear child, to enable you fully to +estimate the force with which air presses upon everything on the surface +of the earth, and consequently upon our own bodies among the rest. + +If you understand this, nothing is easier than to understand how air +comes and goes in our lungs. + +When the cook wants to light her fire with two or three hot coals, +what does she do? + +She takes the bellows and blows it, does she not? + +But if she has no bellows at hand, what does she do? You answer at +once, she blows it herself with all the strength of her lungs. + +By which it would seem--does it not?--that we are a sort of living +bellows, being able, in case of necessity, to act as a substitute for +the wood and leather ones of common use. And if we really possess the +power of doing the work of a bellows, may not this be because we have +within us some little machine of the nature of a bellows? + +Exactly; and this fact gives me the opportunity of making you understand +the action of the lungs by explaining that of the bellows, which is +in everybody's hands, but which three-fourths of the people use, without +troubling themselves to inquire how it is made or acts. + +"A bellows, as you know, is composed of two pieces of board, capable +of being separated and brought together again at will, and united by +a piece of leather so shaped and arranged that it doubles up when the +boards close, the intermediate space forming a firmly-closed box, the +size of which increases or diminishes at every movement of the boards. + +"We take the bellows down to use it, and there are the boards, lying +flat upon each other, the box between them quite small. Is there +anything inside, do you think? + +"Nothing," you answer; "the bellows is empty." + +Do you think so really, my child? Do you think a tumbler is empty, +then, when you have drunk out its contents; and that jelly pots are +empty when all the jelly is eaten? There are not so many empty things +in the world, I assure you, as you suppose. You forget the air--that +monster who is always wanting to stretch himself out, and pushes against +everything he meets. He is an unceremonious gentleman, who takes +possession of every vacant place; as fast as you put a spoonful on +your plate, he takes up the room of the jelly which has been removed, +and at each mouthful you swallow, he slips into the place of the water +which goes away. When you think the glass and pot are empty, they are, +in reality, full of air. You cannot see it; but it is there, you may +rely upon it. + +There is air, then, in the bellows-box, because there is air in every +place where there is nothing else to dispute possession with it. The +quantity is small in this case, no doubt, because the box is small and +cannot hold much. + +But now, look! I separate the boards, and the box, which was small, +becomes large. For once, then, here is a box which must be partially +empty; for it has just, as if by magic, made a space in itself in which +positively there cannot be anything, since there was nothing there +beforehand. + +Ay! but look down at the centre of the upper board. You see a little +hole there, do you not, and below the little hole a small piece of +leather, which seems to close it up? That is a _valve_, one of those +doors, such as we noticed before in the heart, and such as are to be +found, moreover, in most houses, which let people through on one side +but not on the other. This one opens when it is pushed from without, but +lets nothing out which has once got in. Now, the air outside, as I said +before, is always pushing against everything. He pushes as a matter of +course, therefore, against the valve, and as there is nothing behind it +to resist the pressure, in proportion as room is made inside the box, he +enters and fills it with himself. + +But presently some one begins to close the bellows, and he finds himself +caught between the boards; on which these invite him to begone, with +the same sort of politeness displayed by the police, when the hour of +departure comes in a place of public exhibition; when, _i.e._, +they spread out on all sides, and force the crowd before them till +they have found the road to the door. But the air cannot get back by +the way it came in, the door being shut. As, however, it must go out +somewhere, whether it likes it or not, it passes through the tube at +the end of the box (the _nozzle_ of the bellows), and comes out +thence with a rush upon the fire. When it is once gone the bellows can +be distended again, and the process be repeated as before indefinitely. + +And this is just what goes on inside ourselves. Your chest, my child, +is a box which expands and contracts alternately; making a place for +the air by the first effort, and then driving it out by the second. +It is neither more nor less than a bellows, but of a simpler +construction than that used by the cook. The exit pipe serves also for +a door of entrance, and there is but one board instead of two. + +The _exit pipe_ is the _larynx_, of which we spoke before, +when we were talking of swallowing the wrong way, and which communicates +with the air outside, through the nose and mouth at the same time, +allowing us to breathe through either one or the other as we like. + +As to the _board_, I said a few words about it when I was describing the +liver. It is the _diaphragm_--that separating partition--that floor +which is placed between the two stories or divisions of the body--the +belly and the chest. + +But here especially the infinite superiority of the works of God over +the miserable inventions of man comes out in all its grandeur. + +A bellows which was to have the honor of keeping up within us that +miraculous fire--the pre-eminently sacred fire--which we call Life, +required something more than a common board for its foundation. And +accordingly this, of which I am now going to give you a detailed +history, is as marvellous as it is admirable. I fancy that when you +have read my account, you will no longer turn up your nose at the vile +word _diaphragm_. + +Let us first take a peep at the construction of the bellows. + +On each side of the _vertebral column_, from the neck to the loins, +spring twelve long bones, one below the other, bent in the form of bows; +these are called the _ribs_. The first seven pairs of ribs rest, and as +it were, unite, in front, upon a bone called the _sternum_, which you +can trace with your finger down to the pit of the stomach, at which +point the finger sinks in, for there is no more _sternum_, and the last +five ribs on each side no longer unite with those of the opposite one. +For which reason they are called _false ribs_. On the other hand they +are joined to each other at the ends by means of a strip or band of a +substance sufficiently strong, but at the same time flexible, and +somewhat elastic, which is called _cartilage_ or _gristle_. The next +time you see a roasting piece of veal on the table, look well at it, and +you will see at the end a white substance which crackles under your +teeth; that is _gristle_. + +This forms the framework of our bellows, which you may picture to +yourself as a kind of cage, widening towards the bottom and going to +a point at the top, for the arches formed by the upper ribs are smaller +than the others. The whole terminates in a sort of ring, through which +pass, together, the _oesophagus_ and the _trachea_. + +The space between the ribs is occupied by muscles which reach from one +to the other, and the whole framework or cage is shut in below by the +_diaphragm_, that marvellous board whose history I have promised to +relate. + +The _diaphragm_, as I told you some time ago, is a large muscle, thin +and flat, stretched like a cloth between the chest and the _abdomen_. It +is fastened by an infinity of little threads called _fibres_, to the +lower edge of the cage I have just been describing, and it looks at +first sight as if it must be incapable of moving, since it is fixed in +one invariable manner all round the body. + +It moves nevertheless, but not in the same way as the boards of our +bellows. + +Ask your brother to hold two corners of your pocket-handkerchief; take +hold of the other two yourself, and turn the handkerchief so as to +face the wind. The four corners remain in their place, do they not? +but the middle, inflated by the wind, curves and swells out in front +like a ship's sail, which itself is only an immense hand kerchief after +all. Then draw the handkerchief tightly towards you, each to your own +side, and it will recover itself and become flat again. Loosen it a +little and it will curve and swell out again in the middle, and this +maneuver you can go through as often as you choose. + +Which very maneuver the _diaphragm_ is continually performing, of and by +itself. + +In its natural position it bulges upwards in the middle, like a cloth +swollen out by the wind, and thus occupies a portion of the chest at +the expense of the lungs. When air has to be admitted, its _fibres_ +tighten and bring it flat again, as you and your brother brought the +handkerchief flat just now by tightening it. + +The whole space previously occupied by the arch of the _diaphragm_ +is thus given up to the lungs, which, being elastic, instantly stretch +themselves out to it; while air, running in through the nose and mouth, +fills up in proportion the empty place (_vacuum_) created by the +extension of the lungs, exactly as in the case of the bellows. + +But soon the fibres of the _diaphragm_ relax. It rises up again into its +old position, driving back the lungs as it does so; and the air finding +there is now no room for it, goes out by the same way the other came in. +I say _the other_, observe, because the air that goes out is no longer +the same as when it came in; and this is the secret of _why we breathe_; +while the up and down movement of the _diaphragm_ is the explanation of +_how we breathe_. + +As you perceive, then, the mechanism of these bellows of ours, is of +the most simple, and consequently of the most ingenious character, and +leaves far behind it anything we have ever imagined. + +Are you disappointed? Do you feel inclined to exclaim, "Is this all?" +to ask where are the wonders I promised you? to protest that I may +talk as I please about the inflating and flattening of a +pocket-handkerchief? _you_ can see nothing so marvellous in the +matter; nothing worth making your mouth water for. + +A little patience, Mademoiselle! Hitherto we have talked only of the +machine; but there is a goblin inside it, and our fairy tale is going +to begin again. + +There are in some families certain old servants who belong to the +house, more, it may be said, than their masters, in some ways. They +educate the children, and they serve them till death; they live for +them alone, and know so well what they have to do, both by day and +night, that there is no need to give them any orders. Nay, not only +is it unnecessary to give them directions--it is for the most part +labor in vain. They are so completely at home in their business, that +they will go nobody's way but their own. If you wish them to alter +their habits they may obey you for an instant, but it is only to return +into the old groove directly after; for they know better than you do +what you want. + +I was very little when I first read in the story-books of my day, some +bitter complaints of the disappearance of this race of old-fashioned +servants of the good old times. And you very likely may have seen it +said that they are no longer to be met with. Yet there will always be +some, depend upon it, in families, who know how to make and to keep +them. Good old times or not, they have never been found in any other +but these cases. + +Still, _I_ have just such a one as I have described--even I who +am talking to you--and so has your mamma; and what is more, you have +one yourself; and what is more still, everybody else has one. This +servant of the good old times, who will never disappear (and this is +more than one can promise of any other) is the _Diaphragm!_ When +you came into the world, my dear child, and were merely a poor little +lump of flesh, without strength, intelligence, or will; incapable of +giving any orders whatever to those organs of yours, of whose existence +you were not even aware, your _diaphragm_ quietly began his duties, +without leave or inquiry from you, and with your first _breath_ your +life began. Since which he has always gone on, whether you attended +to him or not, and his last effort will be your last sigh. + +When you go to sleep, careless of all that is to happen, until you +awake again, that servant of yours, indefatigable at his post, labors +for you still, and the light breath which half opens your rosy little +lips as it passes through them; that light breath which your happy +mother watches with such pleasure, is his work. Midnight strikes--one +o'clock--two; all around you are buried in sleep--but he is awake +still. Were it otherwise--were he to go to sleep when you do, you +would never awake again! + +This protector of each instant, this faithful guardian of your life, +is, nevertheless, subject to you as a servant to his master. Attend +to him, and he will obey your orders. You can make him go at a great +pace, or slowly, as you choose; or stop him altogether, if the fancy +takes you to do so: but this not for long. The servant of the good old +times is obstinate in the performance of his duties. He will yield to +you in trifles; but do not try to force him over serious matters. I +have read somewhere of a desperate young fellow, chained down in a +dungeon, who killed himself by holding his breath; but I never quite +believed it. Mr. Diaphragm would not allow any one to carry rebellion +so far as that. + +But we have not finished yet, and you do not yet know how appropriate +is the comparison I am making. + +Should any misfortune, any grief, any trifling annoyance even, befall +his master, a good servant suffers with him, and as much as he does; +sometimes even more. Occasionally the master is comforted, while he +remains still disturbed. + +"And the diaphragm?" you ask. + +The diaphragm does precisely the same, my dear child. Yours, especially, +shares in all your griefs to such an extent that, truth to say, he is +not always quite reasonable. The other day when your mamma did not +want to take you into the country with her, he was so sorry for you +that he went into perfect convulsions, and you sobbed and sobbed till +she was obliged to say, "Come, then, you naughty child;" whereupon you +embraced your mamma, and were quite happy again, while he remained +still unappeased, and your poor little chest was shaken more than once +afterwards by his last convulsions. + +Sobbing, you must know, is merely a convulsion--a great shake of the +diaphragm--which is the reason of its causing such a heaving of the +chest. + +It is the same with respect to joy. The joy of the master makes the +servant dance, and so the diaphragm too! Its little internal jumps +are, then, what we call laughter--a thing you are well acquainted with. +Put your hand on your chest next time you laugh (and I hope it will +be soon) and you will feel how it dances--thanks to the diaphragm which +jumps for joy whenever it finds you in good humor. + +Please to observe further, that nothing of all this is done to order. +He starts of himself, poor fellow, without waiting to ask if you will +ever know anything about it; and, in truth, you have known nothing +about it up to the present moment. + +What say you to the diaphragm now, my child? Does not the very name +please you? You scarcely expected to find there--under your lungs--so +good a servant, one so attached to your person, so strongly resembling +in all points the best specimens we know among men. And still we have +not done. I have reserved as a finale for you a new point of resemblance +which will make you open your eyes very wide indeed. + +The old servant is sometimes cross and grumbling. If anything is going +against his grain in the house he has no scruple in saying so; and his +mode of speaking is sometimes rather rude. Nor is it of any use to get +impatient and impose silence on him; he will listen to nothing--it is +his privilege. But let some unforeseen accident happen to his master, +let him see him deeply affected, and in a moment all his anger is over. +He sets himself silently to work again, recalled to order twenty times +sooner by his master's emotion than by his utmost impatience. + +You ask what I am coming to now? My dear child, what I have just told +you is the history of the _hiccup_--the history of the hiccup, neither +more nor less. + +I must first tell you, however, that the _diaphragm_ keeps up +intimate relations with his neighbor below--the stomach. Every time +he rises in the breast the stomach rises behind him; and not only the +stomach, but also its companions, the intestines. All the officials +employed in the business of digestion travel regularly with him; coming +down as well as going up in company. Put your hand upon your abdomen +and breathe strongly and you will feel the rebound of all the movements +of the diaphragm. + +Now, when matters are going on wrongly inside, when too much work has +been imposed on the officials, or work they dislike, or else when they +have been disturbed in their labors, it will sometimes happen that the +_diaphragm_ takes part with his comrades in the abdomen. He gets +angry then, and shakes his master, who cannot help himself a bit. You +must be very well acquainted with these attacks, which are very +fatiguing when they last long. One begs pardon and resists him in vain; +he does as he pleases, without stopping to listen, turning everything +upside down; and do you know the only efficacious plan for calming him +at once? It was a constant source of wonder to me when I was little. +A sudden fright, a start unexpectedly caused by a friendly hand slipping +secretly behind, and laying hold of one, was all-sufficient; disarmed +by the agitation you have undergone, the naughty, stubborn muscle +forgives you, and you are cured. + +Having dwelt so long on the truly wonderful resemblance between the +proceedings of two sorts of beings, whom no one that I know of ever +thought of comparing together before, I will now, my dear child, give +you the key to all these comparisons, which seem so whimsical at first, +but are so striking in reality, and which come to my pen of their own +accord, as it were, in the midst of the explanations I have undertaken +to give you. Many people who would not themselves care for them, will +declare that they are too hard for a little girl to follow. But for +my own part, I find that the eye can take in a mountain as easily as +a fly, and that it is not more difficult to lay hold of great ideas +than of little ones. It is short-sighted people, not children, who +cannot see far before them. Who made the heavens and the earth? God, +your catechism tells you. The same God made both; did he not? We do +not acknowledge two. And if it be the self-same God who made everything, +the hand of the universal Maker will be found everywhere; and from the +highest to the lowest portion of His work the same mind will manifest +itself under a thousand different forms. Not only, either, is each man +separately, one by one, the work of God. The whole human race, taken +in the mass, is also His creation; and the laws by which human +society--that great body of the human race--seeks to regulate itself +for the preservation of its existence, are undoubtedly the same as +those which overruled the organization of our individual bodies. It +is not very astonishing, then, if we find, in the life of human society +around us, details corresponding with each detail of the life of the +human body, or, at any rate, closely resembling them. What would really +be astonishing, would be that mankind as a whole should be differently +constituted from man as an individual, and that human society should +have other appointed conditions of well-being than those of each of +its members. + +So, while I am on the subject, I should like to advise those who wishto +apply themselves to what is called _politics_--that is to say, social +life--to begin their studies of the body social, by studying the body +human, first. They will learn more from it than from the newspapers! + +But you have nothing to do with all this. For the present, take notice +of one thing only; viz., that the hand of the same God has passed over +everything, and that there is neither much presumption nor much merit +in tracing points of comparison between the different parts of His +work. These comparisons are not a mere play of the mind; they really +exist ready made in the very foundations of things. + +Now let us come down a little from these heights and return to our +friends the lungs. I have not spoken about them for some time, and I +have not yet told you how they are constructed. + +I wish I could show you some, but the cook will do so, if you would +like to see them. The _lights_ with which she feeds the cat and +the dog are the lungs of some animal. + +Take up a piece in your hand, and you will find you have got hold of +something _light_ (cooks have not given it its name without a reason), +which is also soft, sinks under your finger if you press it, and rises +again afterwards like a sponge. In fact, the lung, like the sponge, is +composed of an infinity of minute cells, whose elastic sides can be +contracted or expanded at will. They are like so many little chambers, +into every one of which blood and air keep running hastily, each on its +own side, to bid good day to each other, touch hands, and then hurry out +as briskly as they came in. Whether the bit of lights the cat is eating, +comes from an ox, a pig, or a sheep, you may look at it with perfect +confidence; your own lung is precisely like it. You would see nothing +different, could you look into your own chest. + +So much for the _substance_ of the lungs. As to SHAPE, imagine +two large, elongated packets, flat inside, descending right and left, +inside the breast, and bearing the heart, suspended between the two, +in the middle. The extremity of each packet descends below the heart, +and it is in the interval which separates them that the arch of the +diaphragm performs its up and down movement. + +I have already said that air reaches the lungs through the _larynx_. The +_larynx_ (of which we shall speak further when I have explained another +curious thing very valuable to little girls--the voice), the _larynx_ is +a tube composed of five pieces of _cartilage_ (you know now what +_cartilage_ or _gristle_ is), the firm resisting texture of which keeps +it always open. After these five pieces of _cartilage_, come others, and +the tube is continued; but it then takes the name of the _trachea_; the +_larynx_ and _trachea_ constituting the _windpipe_. At its entrance into +the chest, the _trachea_ divides into two branches, which are called +_bronchial tubes_, and which run, one into the right lung, the other +into the left. You sometimes hear people talking about _bronchitis_. It +is an inflammation of these _bronchial tubes_, which are within an inch +or two of the lungs. It is necessary, therefore, to be very careful in +such circumstances, and do exactly what the doctor prescribes, +because--one step further, and the inflammation extends from the +bronchial tubes into the lungs themselves, with which it is not safe to +play tricks. + +Having reached the lungs, the _bronchial tubes_ subdivide into +branches, which ramify again in their turn like the boughs of a tree, +and the whole ramification terminates in imperceptible little tubes, +each of which comes out in one of those little chambers I was talking +about just now. And this is the way in which air gets there at all. + +The venous blood which leaves the heart, arrives on its side by one +large canal, which passes out from the right ventricle, and which is +called the _pulmonary artery_. And, to tell you the truth, while there +is no learned man present to be angry with us, it is a very ill-chosen +name, because it is _venous_ blood which flows in this so-called +_artery_. But the doctors have decided that all the vessels which run +from the heart should be called _arteries_, and all those which go back +to it _veins_, whatever may be the nature of the blood which they +contain. We cannot help it, because they manage all these matters in +their own way; but in that case it was scarcely worth their while to +talk about _arterial_ and _venous_ blood. It would have been better to +have said simply, red blood and black blood. + +Be this as it may, _venous blood_ arrives from the right _ventricle_ +through the _pulmonary artery_. This divides itself, like the _bronchial +tubes_, into thousands of little pipes, whose extremities come creeping +along the partitions of the little chambers in question. + +And here, then, takes place, between the air and the blood, that +mysterious intercourse for the account of which I have kept you waiting +so long; and at the end of which the black blood becomes red, or, in +other words, from venous becomes arterial. I have called it +"intercourse," and this is really the proper phrase; for this +transformation of the blood is accomplished by means of an exchange. +The air gives something to the blood, and the blood gives something +to the air--each giving, in exchange, like two people over a bargain +in the marketplace. + +With your permission, my dear child, we will stop here to-day. We have +now got to the charcoal market, and it is a little black. + + + +LETTER XX. + +CARBON AND OXYGEN. + +Here, then, my dear child, we have arrived at the explanation of that +great mystery, WHY _we breathe._ Keep on the alert, for we are now +entering into a region where everything will be new to you. + +Here we are at the charcoal market, I said to you just now, and no +doubt you concluded that I was beginning another comparison. + +But no such thing; there is no question of comparison or simile here; +I state the fact itself, pure and simple as it stands: it is a +_market,_ for commercial intercourse and exchange are carried on +there, as I told you before, and it is a _charcoal_ market, +because _charcoal_ is, positively, the essential and chief article of +commerce. + +You are astonished, I dare say, and are ready to ask me whether I can +possibly mean real charcoal, charcoal such as the cook puts into the +furnace. Surely, say you, we have nothing like _that_ in our bodies? +Surely we don't eat _that_? + +But I answer yes; real, true charcoal, and you do not dislike it; you +eat of it even daily; nay, you do not swallow a single mouthful of +food which does not contain its proportion of charcoal. + +You laugh; but wait a little and listen. + +When you are toasting a slice of bread for breakfast, and hold it too +near the fire, what happens to it? + +It turns quite black, does it not? + +When mutton-chops are left too long unturned on the gridiron, what +happens to them? + +They turn quite black also. + +When your brother forgets the apples which he has set to roast, what +happens to them? + +They turn quite black, as you have seen more than once. + +It is always black, then, that these things turn, is it not? and a +fine rich _charcoaly_ black, as you may see if you please to +observe charcoal closely, for just such is the color of little burnt +cakes, over-roasted chestnuts, and potatoes in their skins, which have +been dropped into the fire. + +But there is a common term by which we can express more accurately the +misfortune which has befallen all these various things--slices of +bread, mutton-chops, apples, cakes, chestnuts, potatoes, and what-not, +when "burnt," "over-toasted," "over-roasted," or "over-baked." We may +call them _carbonized_, or more simply _charred_ or _charcoaled_; though +the word _charred_ is generally used only for burnt _wood_. But _carbon_ +being the principal ingredient of _charcoal_, and _charcoal_ being one +of the purer forms in which we get at _carbon_, they are almost +synonymous terms, and you may call your burnt food _carbonized_, or +_charred_, or _charcoaled_, whichever you prefer. + +The next question is, how did charcoal or carbon get into the food so +as to justify our talking of its being _carbonized_ or _charred_? Even +when we use charcoal stoves for cooking, the charcoal does not jump out +and get into the mutton-chops, etc., you may be sure. Then it is clear +it must have been in them before they were brought to the fire to be +cooked; and such is indeed the case, only its black face escaped notice +because it was in such gay-looking company, and kept itself hid behind +the others like a needle lost in a match-box. Set fire to the matches, +and you will soon have nothing left but the needle, which will then +strike your eye at once. And so with our burnt food; the fire has +carried off all the other ingredients, and the charcoal is left behind +alone, exposed to everybody's view, as if on purpose to teach them that +it was always there; in the apples, i.e., the potatoes, mutton-chops, +etc., which seemed so tempting when the black rogue was hid, but from +which now, when he is there by himself, they turn away in disgust. + +Charcoal is, in fact, a much more generally distributed substance than +you have been used to suppose, dear child. That which comes from burnt +wood is most easily observed, because there is a much larger proportion +of charcoal in wood than anywhere else; but there is not a morsel, +however small, of any animal or vegetable whatsoever, which does not +contain charcoal. In the sugar which you crunch, in the wine which you +drink, there is charcoal. I could even find some in the water you wash +in if I were to try hard. There is charcoal in the goose-quill which +I hold in my hand at this moment, and in the paper on which I am +writing, and in the handkerchief on my knee. If I hold them all three +in the light of my wax taper, I shall soon see them turn black and +betray the presence of our friend. It exists in the wax taper itself, +as also in the candle, as also in the oil lamp. If I were to hold a +piece of flat glass above their flame, I should collect enough of it +to blacken the tip of anybody's nose who presumed to doubt the fact. +There is a portion of it in the air; a portion of it in the earth. +Where is it not? In short, all the stones of all the buildings in the +world are filled with it from top to bottom. _Charcoal,_ under his more +scientific and important name of _carbon,_ may be called one of the +great lords of the world. His domain is so extensive that one might go +round the world without getting out of it; he is even worse than the +Marquis of Carabas. + +After this you will never, I hope, want to persuade me you do not +eatcharcoal; for, indeed, you would be puzzled to escape doing so. Of +all the things you see on the dinner-table there is but one in which you +will not find it--viz., the salt-cellar; and even while saying this, +I mean only, in the _salt_ itself, for as to the salt-cellar, +clear and transparent as its glass may be, there is charcoal in it! + +Our bodies, therefore, are full of charcoal. Everything that we eat +supplies them with enormous quantities of it, which take up their +quarters in every corner of our organs. It is one of the principal +materials of the vast collection of structures of which I spoke to you +in the early part of these letters, and of which the blood, the steward +of the body, is the universal master-builder. If you remember, I told +you then that these structures fell to pieces of themselves, in +proportion as the workmen went on building, and that the blood, which +brings fresh materials on its arrival from the lungs and heart, carries +away the refuse ones on its return. And, of all these refuse materials, +old charcoal is one of those which takes up the most room, as fresh +charcoal took up a great deal of room in the new materials. The blood, +as he goes back again, has his pockets quite crammed with it, and if +he did not try hard to get rid of it as fast as possible, he would be +disabled from being of any further use. + +Now it is in the lungs that he clears himself of it. He gives it up +to the air, which has need of it for a very interesting operation, of +which I shall tell you more by and bye; and in return the air gives +him something which is quite indispensable to him, for without it he +would not dare to return to the organs, as his authority would no +longer be recognised. + +In the same way, the charcoal-seller goes to market with his charcoal +and receives silver in exchange. + +If he were to go home without money his wife would receive him with +abuse. + +But what is the indispensable thing which the blood obtains in his +marketing? + +Remember its name well: it is OXYGEN. + +And we must speak of it with respect, for we are talking here of a +very great and powerful personage, very superior even to CARBON. If +CARBON be one of the great lords of the world, OXYGEN is its king. + +There is a certain substance, my dear child, of which many people, +especially little girls, do not even know the name, but which yet +constitutes of itself alone a good half of everything we are acquainted +with in the world. And this substance is the very thing I have just +named to you. It is OXYGEN. + +Ascend into the air as high as you can go, viz., to forty miles or so +from the ground, as we said before; _oxygen_ forms the fifth part +of that vast aerial ocean which surrounds the globe on every side. +There it is free--is _itself_--if I may use the expression; it +is in the condition of _gas_; that is to say, it eludes our sight, +though there is no difficulty in ascertaining its presence, when one +knows how to set about it. + +Go down into the depths of the sea. People think they have good reasons +for believing this to be two and a half miles deep on an average, which +would give a pretty little sum total of tons for its whole weight, as +you will be convinced, if you take the trouble of observing the space +it covers on a map of the world;--to say nothing of lakes, rivers, +streams, the water in the clouds, the water scattered throughout the +interior or on the surface of continents, including that with which +you wash your face every morning. + +Oxygen enters in the proportion of eight-ninths into the composition +of this incalculable mass. _Eight-ninths_, you understand, which +is very near being the whole nine; in every nine pounds of water there +are eight pounds of oxygen, the remainder being left for another +substance, of which we shall have occasion to speak presently, and +which is called _hydrogen_. + +The earth on which you tread is full of oxygen. So far as we have +penetrated hitherto into the interior of the globe, we have found king +Oxygen everywhere: hidden under a thousand forms, connected with a +heap of substances, not one of which could exist without him; imprisoned +in a thousand combinations, and always ready to resume his natural +condition if his prison-house be destroyed. The whole surface of the +earth, plains, hills, mountains, towns, deserts, cultivated fields, +everything you would look down upon, if on a clear day you could be +carried high enough in a balloon to take in the whole earth at a +glance:--all that may be considered as an immense reservoir of oxygen, +out of which we should see it escaping in gigantic waves, if some +superhuman chemist were to take it into his head to put our poor little +globe into a retort of the same kind as chemists use among us. To give +you an example; the stones of our fine buildings, in which we have +already discovered the presence of _carbon_, are almost half made +up of _oxygen_. In a stone which weighs 100 lbs. there are 48 +lbs. of oxygen, and the first chemist who passes by could make them +come out of it if he chose, if he were to use a little trouble and +skill. + +I enumerated to you last time many of the substances in which _carbon_ +is to be found; but as regards _oxygen_ we must give up all attempt at +making a list; it would comprehend the whole dictionary. Touch whatever +lies under your hand--in your room--in the house--wherever you may go--I +will almost defy you to put your finger upon anything--metals +excepted--which is not crammed with oxygen. Your very body, to conclude +with, would become so small a thing, were the oxygen it contains +extracted from it, that you would be perfectly amazed. + +So when I told you oxygen was king of the world, I did not say too +much, did I? Between ourselves too, it is a great misfortune that +people live on so complacently in total ignorance of this all-important +material, which is connected with everything, which insinuates itself +everywhere, which we make use of every instant of our lives, which may +almost be said to be in some sort our very selves, since it constitutes +three-fourths of our body, but whose name nevertheless would, I am +certain, make many pretty little mouths pout, if one were to utter it +in a drawing-room. + +This is really the case. Many young ladies who are proud to know who +Caractacus was, would be ashamed to know anything about oxygen. There +is a foolish notion that women have no business with such subjects, +probably because children are supposed not to breathe and mothers are +not required to watch over them? + +This reminds me that we are on the road to explain _respiration,_ +which I had almost forgotten in lifting up this corner of the veil +behind which Nature hides her most valuable secrets from the idle and +ignorant. + +It is _oxygen_ then, which the blood carries off triumphantly from his +interview with the air in the cells of the lungs; and, by the way, it +is, thanks to this oxygen that it returns from the lungs to the heart, +and so from the heart to the organs, with that beautiful rosy tint which +distinguishes _arterial_ from _venous_ blood. + +Now the blood gives out this oxygen on its road every time it performs +the journey, and the perpetual course it performs from the lungs to +the organs, and from the organs to the lungs, has for its chief object +the perpetual renovation of this previous provision, which is as +perpetually consumed. + +Do you ask of what use it is? Does the blood leave it at random in our +organs, and is it one of the materials with which our steward is +constantly providing the little workmen of the body for their various +constructions? + +No, my dear child. The proverb _"One cannot live upon air,"_ is +a very true one, although it is equally true that we cannot live without +air. Air does not nourish our organs; on the contrary, it consumes +them, and what we eat, serves to supply in precisely the same proportion +its insatiable appetite. When we leave off eating, from whatever cause, +the air does not leave off too. He goes on always just the same, and +that is the reason why people who are starved to death are so thin. +(The air has consumed the vital parts.) + +You did not expect this; but now prepare yourself to go on from one +surprise to another. To begin with, I shall have to stop here and +explain to you before we go any further--can you guess what? Nay, I +am sure you cannot; FIRE. + +There is not much connection, you will say, between _fire_ and +_breathing_. + +But there you are mistaken. It is precisely the same thing, as I will +prove to you next time. + + + +LETTER XXI. + +COMBUSTION. + +Have you never, my dear child, whilst warming your little feet on the +hearth in winter-time, asked yourself, _What is fire?_ that great +benefactor of man; fire, without which part of the world would be +uninhabitable by us during at least a third of the year; fire, without +which we could not bake a morsel of bread, and would have to eat our +meat raw; fire, which lights up the night for us, and without which +we should have to go to bed when the hens go to roost; fire, which +subdues metals, and without which we should have neither iron, nor +copper, nor silver, nor anything that is manufactured from those +materials; fire, without which, in short, human industry could not +rise to much higher results than that of the monkey and of the beaver? + +We are all of us, it is true, so much accustomed to fire that we do +not pay much attention to it, and have a sort of persuasion that lucifer +matches have existed from all eternity. But the first men, who were +nearer neighbors to that great discovery whence all others have +originated--the first men treated fire with more respect than we do. +It was to them one of the mighty things of the world. The ancient +Persians made a god of it, and told how Zoroaster, their prophet, went +to seek it in heaven, passing thither from the top of the Himalayas, +the highest chain of mountains in the known world. + +The old Greeks pretended that Prometheus stole it from the gods, to +make a present of it to man, which came to nearly the same thing as +the Persian account. The Romans had their _sacred fire_, which +the celebrated Vestals were bound to keep lighted, on pain of death +to whoever should let it go out. At the present day we do not stand +upon such ceremonies, but warm our feet at it quite familiarly, without +wishing for anything further. But you would see a terrible revolution +in the world if some Prometheus reversed were, some fine morning, to +steal it from us, and carry it back to its ancient owners. Every branch +of human industry would suddenly stop, as if by enchantment, and in +the course of a very few years the poor little framework of human +society, of which we are now so proud, would totally change its aspect, +and the whole world would be turned topsy-turvy. + +But do not be alarmed; there is no danger of the sort. Fire is not a +present once made to man, but liable to be taken away from him at will. +It is a law of nature which existed before the human race came into +being, and which will doubtless continue to exist when the human race +shall have disappeared. The existence of fire is connected in the most +intimate way with that of that great king of the world of whom we spoke +last time--Oxygen. Fire is the wedding-feast of Oxygen with other +substances! + +When kings are married, what rejoicings there are! what a commotion! +what illuminations! It is only right and proper, then, that the king +of the world should have rejoicings and illuminations at his weddings +also. And they have never been wanting. The rejoicings are the warmth +which rejoices us; the illuminations, the flame which gives us light. +But man, in his dealings with nature, is an imperious subject, such +as few earthly kings are troubled with--happily for them! Whenever he +wants warmth and light he forces the king of the world to get married, +and then takes advantage of the feast; nothing worse than that. + +"How so?" you exclaim. "If I want to make a fire with stones or iron, +I should never succeed. Is this because oxygen never unites himself +with those substances, nor with heaps of others which are equally +useless in lighting a fire? Yet you told me that oxygen was to be met +with almost everywhere." + +It is a fair question, my dear child; but my answer is, that what you +said last is precisely the reason why all substances are not fit for +making fire of. When oxygen is already there, as he is in stones, for +instance, the marriage is over--the feast cannot begin again. Kings +are like other people in this respect; their weddings are only +celebrated once. If you had happened to be present at the moment when +oxygen was united to the materials of which stones are composed, you +would have seen a feast of which I should like to have heard some news. +I was not there myself either; but learned men in these latter days +have succeeded in breaking the bonds which united oxygen with the +primitive substances in certain fragments of stone, and with these +substances thus freed, and consequently able to remarry, they have +been enabled to give us, in miniature, the spectacle of the festivities +of a fresh wedding. And I can assure you it is enough to make one +shudder, to think of the time when such a marriage must have taken +place on a large scale. + +With regard to _iron_ the case is quite different. + +You have without doubt heard tell of Louis XIV. (of France), that proud +king who was called _le Grand_, and who is said to have heard +himself compared to the sun, without smiling. It seems that he one day +took it into his head to marry, it is difficult to say why, with Madame +de Maintenon, the old wife of a poor paralytic poet named Scarron, +who, as such, however, was only known by some few farces. Do you suppose +that the palace of Versailles was illuminated in honor of this marriage? +Not a bit of it. It was a disgraceful marriage, which they were bound +to keep secret. The ceremony was conducted mysteriously and without +lighting a single candle more than ordinary. + +I do not pretend to say that oxygen has any of these weaknesses, nor +that he is any more partial to marrying with one body more than with +another. In the good God's great world, outside of the family of man, +they know nothing of our foolish pride, of our little weaknesses. It +is nevertheless a fact that this dear monarch has his preferences, and +that all his marriages are not made in this fashion. + +Leave those pretty little scissors of yours, with which you would try +in vain to make a fire, outside your window for two or three days, and +then observe the dreadful, scaly, red stain which you are sure to find +on them afterwards, and which is called _rust._ Have you any idea +whence it proceeds? I will tell you. It comes from the oxygen, which +has been making one of those cheerless secret marriages with the iron +of your scissors. So there have been no pretty sights nor sounds, no +lights nor cheerful noises to entertain anybody, and though people may +have wished for them ever so much, they have had to do without them. + +I will tell you the true reason of these marriages _incognito._ +It is because oxygen is but feebly attracted by iron, who does not +stand so high in his good graces as many other bodies, and so (to +continue the joke) he unites slowly and languidly with him, as we may +say. + +Now tell me, when you set fire to a bit of paper, how long does it +take to burn? + +Half a minute, at the utmost, you answer. + +Very good. And how long does it take to produce that rust-stain, even +though it is probably not a hundredth part the size of the paper? + +Two or three days, is your reply, for so I told you my self. + +Here is a strange difference indeed; but from it you may discover why +you have not seen any signs of rejoicing or illuminations at the iron +wedding. These are always in proportion to the quantity of oxygen which +is being married at once--and this was--oh, such a slow affair! When +the quantity is very small indeed, the festal illuminations are very +small indeed too, and in fact escape observation altogether. In the +same way that you would not be conscious of little bits of thread laid +delicately one after another on your back, whereas you would plainly +feel a large sheet, were it to fall on your shoulders. Yet what is the +large sheet but a great quantity of little bits of thread? Only in +that case they would all come upon you at once, like the marriage +illuminations of burning paper. + +Wait a little longer and we shall finish. + +What is there, then, in the paper which pleases the oxygen so much +that he unites himself to it so readily, and in such large quantities? + +What is there? Two substances of high degree, who have actually risen +to the dignity of a royal alliance, by the important part they play +in the world; one of these, charcoal or _carbon_, we know quite +well already; the other I have only mentioned to you in connection +with water, HYDROGEN. Thanks to gas companies, everybody in these days +knows _hydrogen,_ at least by name. But before proceeding, I will +just tell you that it is by far the lightest body that is known. It +is forty and a half times lighter than air, which is not very heavy +itself, although in the mass it has its weight, as we have seen. + +The true province of hydrogen is water, where it keeps house with +oxygen, in proportion of one to eight pounds, as you may remember I +stated in my last letter. But beside this, _hydrogen_ and _carbon_ are +in a manner inseparable friends, whom one invariably meets side by side +in all animal and vegetable substances. In wood, coal, oil, tallow, and +spirits of wine; in everything in short that we call _combustibles,_ +because the name of _combustion_ has been given to this marriage of +oxygen with other bodies, hydrogen and carbon keep themselves shut up +very discreetly and very quietly; like two children playing at +hide-and-seek. You have sometimes played at hide-and-seek yourself, no +doubt? Now, if some naughty child had come behind you with a lighted +candle, what would you have done? You would have had to turn out, whether +you liked it or not, and be caught. Well! this is what happens to our two +friends, when you bring the paper to the fire. The heat forces them out, +and the oxygen, which is always at hand, seizes upon them. In a +twinkling they are married, and a beautiful flame springs up into the +air, which lasts till everything has disappeared. + +Hydrogen and carbon! These, then, are the two great combustibles, the +two parents of fire; and as nature has lavished them upon us in what +we may call inexhaustible quantities; when you hear people lamenting +and saying that wood is disappearing, that coal is diminishing, and +that the human race will end by not knowing how to warm themselves, +do not disturb yourself in the least. + +There is more hydrogen in a bucket of water than is wanted to cook a +large dinner. There is as much and more carbon in our stone quarries +than in our coal pits, and when all the woods in the world are cut +down (which I trust will never be!) do you know what we shall do? Why, +we shall take to burning the mountains. The Jura mountains in +Switzerland, for instance, (to take the most favorable case) are great +masses of carbon, without its ever being visible. Everything depends +upon knowing how to make it come out of its hiding place; but that +will de done when it is wanted: more difficult matters have been +accomplished already. As to oxygen, whether carbon comes to him from +a log of wood or from a building stone; whether the hydrogen comes +from a candle or a glass of water, is a matter of perfect indifference +to him. He only considers persons, not their origin, and marries as +willingly in one case as in the other. + +So we have returned to the subject of _respiration_, on which I +always seem to be turning my back; but now the question is, what brings +us to it again? And this is the explanation. + +When the oxygen picked up in the lungs by the blood has traveled with +it to the organs, he finds there two well-known friends--hydrogen and +carbon. + +You smile, and exclaim at once, "Then he marries them, does he?" + +Yes, my dear child; and it is only for that purpose he enters our +bodies at all. And this is why I could not make you understand the +nature of respiration until I had explained that of fire to you. As +I have told you before, it is the same thing. Invite air into your +body by the bellows of your chest, or drive it into the fire by the +kitchen bellows--it is always king Oxygen whom you are sending to his +wedding. + + + +LETTER XXII. + +ANIMAL HEAT. + +Now, then, we have got hold of the secret of respiration; the _oxygen_ +within us unites itself to the _hydrogen_ and _carbon._ + +And for what purpose, do you suppose? + +Unquestionably it must be to make a fire, since they never come together +without doing so. + +But what do people make fires for? I ask next. Well! surely to warm +themselves, do they not? + +And this is the history of your body being warm exactly like a +dining-room stove, where the oxygen in the air forms an alliance with +the hydrogen and carbon of the wood. Nature warms little girls inside, +on precisely the same plan by which men warm their houses in winter. + +Imagine, then, a little stove, furnished with little arms for helping +itself out of the wood-basket as it is wanted, and with little legs +to run and refill it when it is empty; the fire must be always burning +there, and the stove must be always warm. + +Just such a little stove is your body; your mouth being the little +door, by which there constantly enter--not wood, that would hardly be +pleasant--but--hydrogen and carbon under the forms of bread, mutton +broth, cakes, sweetmeats, and all the good things people have learnt +to make with sugar, fat, and flour. There is hydrogen and carbon in +everything we eat, as I have already told you; but sugar, fat, flour, +and _wine_ are the substances which contain them in the greatest +quantities, and consequently they are our best _combustibles._ + +You are surprised, perhaps, at _wine_ being a combustible; wine, +which you think would put out rather than make a fire. + +And it would. But that is only because in it, what is good for burning +is mixed with a great deal of water, which prevents our being able to +set it on fire. But if part of this water is withdrawn, you have +_brandy,_ which lights easily enough; and if part of the remaining +water is withdrawn from the brandy, you have _spirits of wine_, which +takes fire more easily still. If you have ever seen a _spirit-of-wine_ +lamp, you must know something about this. Judge from that what a fire +spirits of wine must make in the body, even when it has a good deal of +water with it; for it is right to tell you that your little stove is +very superior to the one in the dining-room, and that it hunts out for +consumption the smallest portions of combustible matter, in places where +the other would be a good deal puzzled to find them. + +This is not all, however. I have much greater wonders to tell you yet. + +What should you say to a stove, which, summer or winter, night or day, +in rain or sunshine, amid the ice of the pole, or under the sun of the +equator, was able to keep itself constantly in the same condition; +neither hotter nor colder one minute than another, whether you gave +it much or little fuel, at a given moment, and sometimes when you gave +it nothing for whole days together? It would be worthy of a fairy tale, +would it not? Yet the human body is a stove of this description. + +But this requires a little explanation. + +It is rather bold in me, you may think, to assert so freely, that all +the year round, from one end of the earth to the other, the human body +is never colder nor hotter than mine is, for instance, at this present +moment. "Hot" and "cold" is soon said, you argue: but the exact +varieties of _more_ or _less_ are not so easy to measure, and especially +not easy to remember, with reference to so many bodies, scattered over +the face of the whole earth. What may be warmth for one in one case, may +not be equal warmth for another; and even supposing that the same +individual learned man could go and inspect every part of the globe in +succession, how could he possibly recall, while touching the body of a +negro in Senegal, in July, the exact amount of animal heat he had found +in a Greenland Esquimaux in January? + +Be content. I should not have settled the question so cavalierly, if +people had not discovered an infallible method of estimating accurately, +and always in the same manner, the degree of warmth, in other words, +the _temperature_ of the body. + +Let us first see, then, what this method is, though it will oblige us +to digress a little; but you are accustomed to that now, surely; and +besides, if I were to go straight ahead, you would not be able to +follow me. + +Do you ever recollect being very cold? Let mammas look after their +little girls as much as they please, to prevent it, it is sure to +happen to every one some day or other. Now does it not seem at those +times as if the whole body were contracting itself--and when people +are shivering with cold, have they not a shrunk, shrivelled look? When +the weather is very hot, on the contrary, our bodies feel as if they +were swelling and stretching, and one seems to take up more room than +before. This is the case with all bodies. Heat swells, or, as learned +people call it, expands, them: cold shrinks or contracts them. +Furthermore, _mercury_ is one of the things most susceptible of this +action of heat and cold, and we have had recourse to it accordingly, in +the construction of the _thermometer_, [Footnote: _Thermometer_ comes +from two Greek words: _thermos_, heat; and _metron_, measure. The +degrees in the Thermometer about to be described are marked on the +_Centigrade_ principle. [Not the one (Fahrenheit) in general use in the +United States.]] a very useful instrument, which you will hear spoken of +all your life. + +The _thermometer_, or _heat-measure_, consists of a little hollow ball +filled with mercury, out of which rises a small tube of very thin glass, +in which the mercury can move up and down. When the thermometer is +exposed to heat, the heat causes the mercury to expand, so it goes up +the tube; when the thermometer is exposed to cold, the mercury contracts +and sinks again. + +Now suppose you were to melt some ice in the palm of one hand, and try +to dip a finger-tip of the other in a saucepan of boiling water; you +would find a great difference of temperature between the two, would +you not? Which difference of temperature people have succeeded in +measuring with the thermometer, as accurately as your mamma measures +a piece of cloth with her yard measure. + +This is how it is done: + +You surround the ball of mercury with pounded ice, and while it is +melting make a mark at that point in the tube where the mercury has +stopped in its descent. Then plunge the thermometer into boiling water. +Whereupon the mercury goes up, up, up, till at last it reaches a point +beyond which it will not pass. Here a second mark is made, and the +space between the two marks is divided into a hundred perfectly equal +parts, indicated by so many small lines, which are called _degrees_. But +this word _degrees_ has a double meaning in some languages. It means +_steps_ as well as the degrees of measurement we are talking about; +steps being, as you know, the perfectly equal parts into which a +staircase is divided. Fancy the mercury-tube a staircase, then, rising +from the cellar where the melting ice is, up to the garret where the +boiling water is, and let it consist of 100 steps. The mercury goes up +and down this staircase, according as the temperature it encounters +approaches that of the boiling water or of the melting ice; and if you +wish to know exactly how far it is from the cellar or from the garret, +you have only to count the _steps_. Hence arise those expressions which +you so often hear--high temperature and low temperature. These mean, +temperature according to which the mercury goes up or down this +staircase. + +On the actual floor of the cellar where the ice melts, there are yet +no degrees (a floor is not a _step_, you know), so there you find the +word _zero_, which means a cipher or nought. Then you begin to count 1, +2, 3, 4 degrees, marked by lines up to 100, where you reach the garret, +_i.e._ the boiling-water height. + +Of course, if the thermometer be exposed to an amount of cold greater +than that of melting ice, the mercury will sink below the cellar. +Accordingly the staircase is carried below it, with steps (so to speak) +of precisely the same size as those above, and you count as before, +1, 2, 3, &c., as it descends; adding however, to distinguish these +degrees from the others, "_below zero_." You may go on in that +way as far as 40; but there you must stop. At that point the mercury +freezes. He sits down there on his last step, and will not go any +further! + +In the same way if the thermometer is exposed to a heat greater than +that of boiling water, the mercury will rise higher than the garret. +So the staircase is made to go up higher, and always with steps of the +same size, counting from 101 upwards, as far as 350 if you choose; but +no further, observe! If the temperature were raised beyond that, the +mercury would begin to boil, and then, indeed, good-bye to steps and +measured degrees! The gentleman would dance so fast that there would +be no possibility of seeing anything, to say nothing of his flying +away! + +Now nothing is easier than to use the thermometer. You place it in the +situation where you want to measure the heat, and the mercury goes up +or down of itself until it reaches the degree which corresponds with +the temperature of the place. It is much more convenient than your +mamma's yard measure, which has to be moved about over the stuff, and +which is very apt to slip if you do not hold it carefully. Dressmakers +would be delighted to have a measure which only wanted laying upon the +material, and which would unroll itself and stop short just at the +proper point. And this kind of office the thermometer really performs. + +We will suppose to-day to be the 30th of November. I have just carried +the thermometer out of doors; the mercury has fixed itself at the +second degree _below zero_. This tells me that it is freezing +cold. My fingers have told me so already; but exactly to what extent +they could not say. Just now in the room, the mercury was at the 15th +degree _above_ zero, thanks to the stove in which we have a good +fire. In summer-time it rises to 25, 26, or 28 degrees. I once saw it +climb as high as 33 degrees: in the shade of course, you understand; +in the sun it would have been quite another affair. Well! there was +a universal outcry against the heat. Grown-up young ladies whom I try +to teach all sorts of things as I do you, pretended that it was +impossible to work. Yet I should find a still greater heat inside my +body, if I could get the thermometer there. Have no fears, however; +I am not going to make a hole in it: luckily there is one already. I +put the ball of mercury into my mouth. And now I can almost tell without +looking. The mercury was on its way up the staircase as soon as I took +the ball in my hand--and now it has reached the 37th step. + +You can try the experiment on yourself, but I forewarn you that it +ought to be rather hotter with you than with me: the mercury will +probably rise a degree higher. I will not promise that in your +grandpapa's mouth it may not sink a degree--but that will be all. In +different mouths it has, between the 38th and 36th degree, room for +the play of a little variation, but it can no more go beyond these +than a tethered cow can get beyond the circle made by her cord as she +turns round the stake. Go round the world with your thermometer, pop +it into everybody's mouth, wiping it if you choose as you proceed, you +will always find the mercury on guard. Its tethering cord is somewhat +elastic, like everything else about us; but if by any accident it +should exceed its limit by even one degree above or below, it would +be quite as extraordinary as meeting a giant of eight feet, or a dwarf +of three--which one does see occasionally, although the standard of +human height varies generally round the centre of five feet. + +Since there is a fire always kept burning within us, there is no +difficulty in comprehending why our bodies always keep warm. Of course, +however, the fire must be kept brighter in winter than in summer, but +people have no need to be told so. Nature provides for the necessity. +She gives us more appetite in cold than in hot weather; not that we +can perceive much difference in ourselves in this respect from winter +to summer; for our bodies stick to their accustomed habits, and call +out pretty loudly for the same daily rations, though without having +the same need of them. In order to estimate fairly the connexion which +exists between the internal need of food--_i.e.,_ of combustible +matter--and the external temperature, we must compare the Hindoo, who +lives on a pinch of rice a day, between the tropic and the equator, +with the Esquimaux, who, to keep up his 37 degrees of heat, beyond the +polar circle, in a country where European travellers have seen mercury +freeze, sometimes swallows from ten to fifteen pints of whale-oil at +a sitting! Just fancy _whale-oil!_ which is much nastier than +even cod-liver oil, if you ever tasted that; but, on the other hand, +it is a thorough _combustible_, and the poor people are not so +very particular: come what will, the fire must be kept up, and that +briskly. But without going thus into extremes, a friend of mine once +told me that in Portugal, the land of oranges, it is not uncommon to +see gentlemen and ladies (that is to say, those who can eat and drink +what they please) dine standing, in five minutes, on a bit of bread +and whatever else may be handy. Propose this system to the inhabitants +of our colder and damper climate, whose very young ladies, fair and +delicate-looking as they are, need a helping of good roast-beef for +dinner to keep life in them, and they would only laugh at you. But +those who were well instructed could go on to inform you that the +chilly atmosphere of northern countries creates the necessity for a +more active internal fire than is ever needed under the burning sun +of Portugal, and that a mouthful of bread per day will not, in their +case, suffice to maintain the appointed thirty-seven degrees of heat. + +For the same reason, Spaniards drink water, and are satisfied; whereas +English wine-merchants add brandy to a good many foreign wines, or +they would be quite unacceptable from being deficient in combustible. +It is for the same reason, also, that Russians can swallow, without +wincing, bumpers of brandy which would kill a Provençal outright: and +that the Swedish Government has no end of trouble to keep the country +people from converting into brandy the corn that ought to go to the +miller; whilst the Mohammedan Arabs accept without difficulty that +precept of the Koran which forbids the use of wine and spirituous +liquors. It is easy for the Arabs, who are kept warm by their climate, +to do without brandy. It is less easy for the Swedes, who are surrounded +by cold. + +All this comes as a matter of course, and we do the same thing +ourselves, without being unusually sagacious. In January, when the +thermometer goes down to twelve or fifteen degrees below zero, I put +more fuel into my stove than I am doing to-day, with only two degrees +of cold to bear with. There is nothing surprising in all this. + +The wonderful thing is, that when an Englishman goes to India, he takes +his roast beef and his spirits with him, and in a temperature of more +than thirty degrees of heat, quietly heaps up fuel in his stove, just +as if he was in England, or nearly so. You think he will set fire to +the house, perhaps. But no. Send the thermometer to his mouth for +information, and it will only mark down thirty-seven degrees; neither +more nor less than in the mouth of a rice-eater! The stove has more +sense than its owner. It only burns just what hydrogen and carbon it +wants, and takes no more trouble about the remainder than if it had +not been eaten. + +How about the remainder, then? you ask; if it is not consumed for use, +what becomes of it? Do you remember, my dear child, that long ago, +after explaining the office of the bile and the liver, I put off telling +you what the bile _consisted of_, until we had talked about the lungs +and respiration? Well, the time has come now; so listen. + +The hydrogen and carbon which is not consumed by the oxygen in the +blood, is seized upon by the liver, who employs it in the manufacture +of bile. Therefore the greater the amount of unemployed hydrogen and +carbon there is in the blood, the greater is the quantity of bile +manufactured by the liver--that is all. When once the body has attained +to its proper degree of heat, it is in vain you load it with +combustibles; it will not get any warmer, do what you will. Only you +will have cut out so much extra work for the liver, and the poor wretch +will have to get through it as he can. Accordingly, what happens in +the long run to our great eaters and drinkers, whether in India or +elsewhere? The bile-manufacturer, overwhelmed with work, gets worn +out at last, and kicks; and people come home with that miserable +disease, which is called the "liver-complaint." + +This is one explanation of that wonderful uniformity of temperature +which, happily, human imprudence cannot disturb. But the blood has a +second resource for getting rid of its superfluity of hydrogen and +carbon, and herein especially is displayed the beautiful foresight +with which everything about us has been prearranged. We are told that +wolves, when they get hold of a larger piece of meat than they care +to eat at the moment, carry off what they do not want to some corner +and bury it in the ground, whence they get it again when their hunger +returns. Dogs sometimes do the same; and the blood has a similar +instinct. Listen attentively, for this is very interesting. + +I light a candle and you see a bright flame, which will last as long +as there is any tallow below the wick. Can you tell me what it proceeds +from? + +Nay, do not laugh at the question; it is quite to the purpose, I assure +you. + +We know, do we not, that the substances which burn best are those which +are full of hydrogen and carbon? Tallow, then, is one of those +substances. But tell me further, if you please, what is tallow? + +Tallow is _mutton fat_, allow me to say, if you never heard it before. + +Now comes the question, who provided the sheep's fat with such a +quantity of hydrogen and carbon as to qualify it for making candles? + +The sheep's blood undoubtedly, since blood is the purveyor-general of +living bodies--of the sheep's body as well as of our own. + +But how came it that the sheep's blood had so large a stock of these +materials? + +Undoubtedly, again, because there was more of them in the food the +sheep had eaten than the oxygen was able to consume or the liver to +employ. In short, the sheep has lungs and a bile-manufactory, as we +have; oxygen performs the same office for it as for us. What takes +place in its body in the matter of respiration is an exact counterpart +of what happens in ours, and the history of its fat is simply the +history of our own. + +Now do you think it is for our sakes that the sheep's blood deposits +its fat in little pellet-like morsels throughout the body; do you +suppose the poor creature works in this manner merely to have the honor +of providing us with candles? It is not likely. I was talking about +the wolf just now; but there is no need to look beyond ourselves. In +many poor people's cottages there is somewhere an old earthen pot in +which the savings of each day are carefully put by, penny by penny, +as a last resource in time of need. Should a wicked thief succeed in +murdering the owner and laying hold of the treasure, he will squander +in a few hours of brilliant revelry the precious hoard so slowly got +together as a provision for possible needs. And this is what man does, +when he kills the sheep and takes its fat to make candles of! The poor +animal's blood knew well that bad times might come, that grass might +fail, and the combustible matter conveyed into the body become +insufficient to maintain its thirty-nine or forty degrees of heat +(which is the sheep's measure, who is rather hotter than we are). So +it quietly laid up its surplus stock of combustible so conveniently +brought to hand, and destined to be burnt little by little in the +depths of the organs, should times of scarcity arise. But here steps +in man, the universal thief of Nature, and turns it into a beautiful +flame, regardless of cost, and burns in one evening what his victim +had been economizing for so long. To burn for burning's sake, however, +has always been the fate of tallow, the only difference being in the +way it is done. Like the poor man's clumsy pence, which were put by +to be spent some day or other, only in another manner. It is worth +noting here, that some of the Russian soldiers who were in France in +1815 had a very good idea of restoring candles to their original +destiny. As children of the north, driven to get fire wherever they +could, they ate all the candle-ends they could lay hold of, preferring +to burn the tallow, sheep's fashion, inside rather than out! + +Fat is, then, the savings' bank of the blood; there it deposits its +savings, and there it can always find them again in time of need. +Witness the fat pig described by Liebig, the great German chemist, +which having been swallowed up by a landslip, was found alive at the +end of 160 days. Fat was out of the question there, of course; the +animal weighed ten stone less than before. We will take the illustrious +professor's word on trust, but were a few days subtracted from the +account the case would still be a splendid example of the resource +which blood finds in fat when other nourishment fails; for the pig had +certainly been breathing during the whole 160 days, and as, in all +probability, he moved about much slower than usual, his hydrogen and +carbon fire was never extinguished for a single instant; of that I am +perfectly certain, and you shall soon know why. It was well for the +poor fellow himself that he had put by his provisions in time of plenty. +And who suffered? Why, the pig's master, who had looked forward with +pleasure to the rashers of bacon he should cut by and by from the +stores of combustibles in his larder. For once Master Piggy ate his +own bacon himself! + +You understand now, I hope, by what ingenious management that marvellous +stove, called an animal, never burns too much fuel, whatever be the +quantity it is supplied with, and how, on the other hand, it has always +as much as it wants. + +I have now to explain how important it is that it _should_ always +have enough, and that this is not merely a question of heat and cold, +as with dining-room stoves, but one of life and death! Cheer up! I +have only one more word to say about Respiration, and when you have +heard it you will appreciate still better the lesson of economy which +you have learnt from Nature to-day. + + + +LETTER XXIII. + +ACTION OF THE BLOOD UPON THE ORGANS. + +The first time we talked about the Blood, my dear little pupil, I +introduced him to you as the steward of your body, and what a steward +to be sure! Always awake, as you may remember, always in motion; his +pockets ever full of the materials unceasingly required by the +indefatigable builders of that human edifice in which it has pleased +God to house your dear little self. If you wish really to understand +what follows now, we must carry on the simile a little further. + +A steward not only provides the workmen with materials, but gives them +orders as well, and this is part of the blood's business also. He is +not only commissary-general, but _whipper-in_ of the whole household, +and besides the care of giving out all the stores, has the charge to see +that everything is properly done. The unhappy men who purchase +prosperity at the dreadful cost of maintaining slavery, pretend that +their slaves would do no work worth looking at, were there not always +some one behind them with a whip in his hand. Well, our organs are +slaves, and slaves of the worst sort. They would never do anything +at all, if the blood were not everlastingly whipping them up in his +ceaseless rounds. Let him come to a stand-still for one minute, for +a second even, and everything stops short; then we are at once in the +castle of the Sleeping Beauty in the wood. But perhaps I cannot do +better than to compare our bodily machine to a violin--to hit upon +something less dismal than slaves--a violin with blood for its bow. +As long as the bow runs over the strings the violin makes music and +lives; when the bow stops, it is silent and dies. + +You have never yet had a fainting fit, my dear child; it rarely happens +at your age. But you may possibly have seen somebody faint; or, at any +rate, you have heard it talked about. Do you know what takes place in +such cases? Now and then, in consequence of some violent emotion, but +how or why I cannot tell you, all the blood rushes suddenly back towards +the heart, as during an earthquake a river will sometimes flow back +towards its source, leaving its bed dry. Thereupon the face turns +white, as if to give notice that there is no longer anything red below +the skin. The organs, no longer stimulated by the blood, leave off +work altogether. The brain goes to sleep, the muscles relax, +consciousness ceases, and you behold the poor body, from which the +soul seems to have departed, give way on all sides, and fall to the +ground like a corpse. This is not exactly death, but it is yet an +interruption of life. It would be death if nature did not get the upper +hand again, and send back the deserter to his post. + +I may remark here that it was partly on this account that some of the +ancients thought the soul was seated in the blood; not a bad idea for +people who were determined to pronounce where the soul was, when it +is so easy to say one knows nothing about it. But those who placed it +in the breath, and who have bequeathed to us those beautiful +expressions--_yielding up the last breath--giving up the ghost_--were +not wrong neither. + +In point of fact the blood is not the soul of the body; in other words, +does not keep the body alive, otherwise than by keeping up unceasingly +and everywhere that magic fire of which we were talking last time. + +The French people, in their picturesque language, have found an +expression, full of energy, to express the action exercised by the +master workman, who knows how to make his people work: "_Il vous met +le feu sous le ventre._" [Footnote: Literally, _he puts fire under +their bellies;_ but here signifying that he makes it so hot that +the organs are compelled to continue in motion.] This is, to the letter, +the process employed by the blood to make the organs work. It makes +a fire under the belly. Unhappily their work only lasts as long as the +fire which causes the heat, and which is so necessary to life that it +is almost confounded with it. It is the sacred fire of the Roman +Vestals, which must be fed night and day under pain of death should +it go out. Now, if to feed the sacred fire of life, it be necessary +that the blood should everywhere find hydrogen and carbon +_unattached_, that is to say, free and ready to unite themselves +to oxygen, it is no less necessary that he should bring oxygen with +him everywhere. Else there would be no marriage, and therefore no fire. +Oxygen is, then, the talisman which brings the organs to obedience. +Without oxygen he would be a slave-driver without his whip; his orders +would be despised. If the organs were to be deluged with _venous_ +blood--with that black blood which has lost its oxygen, they would not +stir any more than if they had received so much water. They acknowledge +nothing but _arterial_ blood--red blood--blood rich in oxygen. +That is what they respect, and which has authority over them; the other +is a bankrupt who has lost his credit with his cash; those whom he fed +but lately now laugh in his face. And as our good steward spends all +his oxygen every time he goes his rounds, it would soon be over with +him, and, consequently, with us, too, if he had not some method of +replenishing his purse after each journey. Happily the lungs are the +inexhaustible chest to which he always returns to renew his right of +authority; that is, his power of preserving life. When it comes to the +_last sigh_, the last effort of the diaphragm by which the chest +is closed forever, we must bid adieu to life. In yielding up that, we +have in very truth yielded up the ghost. + +This is no joke, as you see, and it would not do to be caught +unprepared, with an inexorable necessity hanging over one, which never +allows a moment's respite. The blood acts like a reasonable being, +therefore, in laying up his stores of combustible in reserve. Moreover, +whether he has done so or not, the fire must go on all the same; that +is absolutely necessary; and if he has no spare fat to feed it with, +when, from any cause, the stomach leaves off working, he makes use of +anything he can lay his hands upon. + +I know a story on this subject which will amuse you. + +There lived, in the reign of Francis I. of France, an honest countryman, +of Périgord, named Bernard Palissy. At that time everybody could not +afford to have earthenware plates, as they have now. It was a +manufacture of which only the Italians had the secret, and Bernard, +who knew something of the matter, from being a glass-worker, took it +into his head to try and find it out entirely by himself. So, without +asking anybody's advice, he turned potter, built ovens, picked up wood +as he could, manufactured his first pots, whether well or ill, made +a beginning, and waited. He had fifteen or sixteen years of it before +he succeeded; fifteen or sixteen years of ruinous experiments, which +would have discouraged a less sturdy heart than his. But he, after he +had succeeded in picking up some money by his church windows, returned +to his work with unconquerable perseverance, insensible to poverty, +deaf to the ridicule of neighbors, and unmoved by the abuse of his +wife, who was furious, as you may suppose, at being forced to play the +heroine without having the least turn for it. And one fine day there +was a grand uproar in La Chapelle-Biron (that was the name of his +village). "Bernard Palissy has gone mad," said everybody; "he is burning +up his house to bake his pots." And upon my word it was true! Wood +happened to be wanting while a batch was in the oven, and Bernard +having begun by using up the garden palisades, took next the large +tables, and at last the floor of the house! What his wife had to say, +I leave you to judge; as for him he listened to nothing; but, fixing +his eyes on the insatiable furnace, threw in one thing after another, +caring only for the risk to his handiwork. The ceiling would have +followed the floor had not his pots been sufficiently baked without. + +And thus, and thus, does the blood, when combustible matter fails him! +He demolishes the house, and throws it, bit by bit, into the fire. The +fat goes into it naturally enough, as I have already explained to you. +It is the fuel-store of the house. It was put by on purpose, and may +be used up without injury. Then comes the turn of the muscles; more +useful without being indispensable. Those are Bernard Palissy's +palisades one may contrive to do without them. They melt away, so to +speak, after a few days' fast, and you find yourself what people call +"nothing but skin and bone." But then, if this condition is prolonged, +and the exhausted flesh cannot supply the demand, the blood does not +hesitate a moment. He boldly falls upon the most important organs, +without stopping to consider; he, too, is devoted solely to his work, +and that, like the baking of pots, never comes to an end by being +completed; if external help does not arrive in time, the house soon +becomes uninhabitable, and life slips away. The man dies of hunger. + +But in the same way that poor Bernard Palissy was in reality working, +all the time, for his wife and children, whose future well-being he +strove for as the final end of all his efforts, though at the risk of +letting them sleep under the bare heavens; so the blood was laboring +up to the last moment for that very life which he at last turned out +of doors; and the work of destruction which caused its final departure +has had in reality the effect of prolonging its stay. Without it, all +would have been over long before. + + + +LETTER XXIV. + +THE WORK OP THE ORGANS. + +Thus much is settled, then. It is the blood which sets everything in +motion throughout the body. The organs are idlers who would do nothing +but for him; they only work when goaded on, if I may use the expression, +by that fire--always on the point of going out--which he is perpetually +coming back to rekindle, thanks to the oxygen he carries with him from +the lungs. + +This will enable me to explain many things, which, although not new +to you, you have probably never tried to account for before. + +To begin with: do you remember what happened to you the other day, +when you tried to overtake your mischievous brother in running, and +he, taking advantage of his school-boy legs, led you mercilessly through +all the garden walks, without having the grace even to let you catch +him at the end? You were quite out of breath; your heart beat so rapidly +it almost hurt you; and you were so hot that the perspiration poured +in great drops down your face, so that your mamma, quite frightened, +took you up in her arms and carried you to the fire; for the coolness +of evening was coming on, and a little girl drenched with perspiration +is soon chilled. + +Tell me now, what connection was there between your overrunning yourself +in a race and the extraordinary degree of heat which came over you so +soon? Your cheeks were cool and fresh when you began to run; what made +them so red all at once, and especially at a moment when the air was +cool and fresh in the garden? + +You open your eyes in surprise; you had never thought of this. No! +that is just the way with little girls. They run; they get hot; it +seems as natural as warming oneself in the sun, and they never ask why +it is so. + +Yet you could almost tell me the "why" yourself, if you stopped to +think about it, now that you are what your school-boy brother would +say "_up to a thing or two;_" but to save time, I will help you. + +You run as a bird flies, without thinking about it. Nevertheless, if +you could see with a magic glass all that takes place in your body +while those active little feet are carrying it like a feather across +the garden, you would be perfectly amazed. One of these days, when we +have finished our present history, I will tell you that other one, +which is equally worth the trouble. It is enough for the present to +know, that a very complicated piece of work is being carried on there, +in which almost all the muscles of the body take part at the same time, +contracting and relaxing in turn, like so many springs, of which each +either drives forward or holds back a part of the machine. In fact, +while your eyes and thoughts are fixed on the butterfly which is +flitting away from you through the air, there is going on within you +such an unheard-of outlay of efforts as could never be got out of our +idlers if the terrible steward did not lash them severely. + +Now, his lash, as we have said often enough, is that eternal fire, the +materials of which he conveys to all parts of the body. On those special +occasions, therefore, he is obliged to make his fire burn much more +briskly than usual--exactly like railway engine-drivers, who increase +the heat of their fire to get up steam in proportion to the speed they +wish to go. + +From this you will understand that it is no great wonder that your +small frame should get heated from such work as racing and chasing; +and that if you pursue it too long, the perspiration which comes out +all over you is sufficiently explained. + +This is not all, however. The fire, whose strength has to be increased, +naturally requires a larger amount of combustible matter than before, +and forasmuch as there is only a certain fixed quantity in each drop +of blood, whenever the muscles want more than usual, the blood itself +must flow to them in greater abundance. Now if it were a question of +supplying only one part of the body (as it is, you may remember, of +supplying the stomach during the progress of digestion), he might +contrive to accomplish his task there by neglecting it elsewhere, and +overflow one organ at his ease, at the expense of all the rest. But +in this case he is wanted everywhere in the same abundance. It is not +a question of taking one muscle's share for the benefit of another. +From one end of the body to the other, all want to be deluged at once. +And remember that these exigencies do not bring a drop more blood into +the body. How is he to get out of his difficulty then, this overwhelmed +steward of ours? Well! just as your mamma manages, my dear, when there +is more to do than usual in the house;--by running quicker than ever +from the cellar to the garret, and from your room to your papa's! That +is called doubling oneself; and this gallant blood doubles itself to +some purpose. He runs and runs and runs, arrives in hurried streams, +and returns full gallop, passing and repassing through the heart, which +empties and fills itself in sudden jerks. Unluckily, the poor heart +is a delicate sort of person, who does not like having his habits +disarranged, and this forced work soon makes him desperate. The other +day, in his despair, he knocked with all his strength against the walls +of his little chamber, to warn his young mistress that he could bear +no more, and that they were both of them in danger. In fact, you ought +to know that if one was infatuated enough to go on running too long, +one might die of it. When you learn ancient history, you will probably +be told of what happened to the soldier of Marathon, who flew like an +arrow from the field of battle to the gates of Athens, that he might +tell his fellow-citizens a quarter of an hour earlier, that his country +was saved; and he fell dead on his arrival. + +But it is not the heart only which suffers by this mad career of the +blood. During each journey it performs it passes through the lungs, +which in their turn are forced to play with hasty jerks. And this is +well for our good steward; for the lungs, filling with air at each +descent of the diaphragm (if you remember what we have said before), +more air, and consequently more oxygen, comes in, and the blood has +by this means a larger stock on hand, ready to help him out in the +unusual waste which is just then going on in the muscles. I spoke just +now of railway steam-engines. See how self-supporting ours is! The +greater the amount of fire wanted, the faster the blood flows; and the +faster the blood flows, the oftener does the coffer re-fill itself, +whence comes the supply of oxygen requisite for keeping up the fire. +All this goes on at once, by one impulse, and the balance between the +receipts and expenditure settles itself of its own accord. How thankful +many families would be if their money-chest would but fill itself in +the same way--in exact proportion as they spend the cash! There is +only one slight drawback, which is, that the diaphragm gets tired with +the unaccustomed gallop it is thus forced into. It falls into +convulsions, therefore, like its neighbor the heart, and the breathing +is stopped, from having been driven too rapidly. An excellent example +for people who want to spend too much at once; showing that Nature +herself cries out against it, even when the only thing wanted is +atmospheric air. + +Now, run if you dare! And, to tell you the truth, it would be a great +pity if you did _not_ dare; for our good God has made little children +for running. They have nimbler blood than we older grandfathers, more +elastic lungs, and consequently more oxygen to spend at a time. But you +must confess that it is a great pity we should run all our lives as many +people do, without having the slightest idea of these admirable +contrivances, thanks to which we are enabled to do it. We can run all +the same, it is true, without the knowledge, the little child as easily +as the little roebuck, which sets a similar machine in motion. But it is +no use talking about the little roebuck; it cannot learn what God has +done for it, but the little child can, if he will. Furthermore, there is +nothing to be really alarmed about, for those great commotions only +occur when we have committed excess; and it is a very good thing, in a +general way, for the blood to give us a stroke of his lash from time to +time. I told you lately that the fire which sets the organs to work is +life; and it is no misfortune to be a little more alive than usual. +Besides which, this increased activity of the internal fire does not +serve us in running only. Every time that a man makes an effort; every +time he lifts a weight, or handles a tool, the blood rushes forward to +deluge the muscles that are thus called into play; the heart beats more +quickly, and the air streams in greater abundance into the lungs. Look +at a man chopping wood. If the log resists too much, if for a minute or +two the man has to strike blow after blow without stopping, you will +soon see him panting for breath, just as if he had been running a race. +On the other hand, he will have gained something from chopping his log +besides the right of warming himself before it at the fire. Blood does +not carry fire only into the muscles; he supplies them with nourishment +also, does he not? Every drop of blood deposits its little offering as +it goes by, and consequently the greater the number that pass along, the +richer is the harvest for the muscle. Look, accordingly, at the laboring +classes. How much healthier and stronger they are than those who do not +work! I speak, of course, of working with one's limbs generally; for +those poor girls who work from morning to night, sitting on their +chairs, are none the better for it, but, on the contrary, worse. There +are also certain worthy fellows who, like myself at the present moment, +drive a pen over sheets of paper for half a day at a time, whose muscles +never get any bigger for it, that is quite clear. Moreover, one +condition has to be fulfilled, which unhappily is not always done. The +more people labor, the more they ought to eat. To you, who have just +been looking at the drama that is performed in the body every time a +muscle is set in motion, this is obvious enough. There is no fire +without smoke, says the proverb. It would have been much better to +have said,--there is no fire without fuel;--and the fuel for our fire +is, as you know, what we eat. Try if you can get one stove to burn +more brightly than another, if you have put less fuel into it. Yet, +alas! this is what many poor wretches are obliged to do but too often; +and then the blood, instead of feeding their muscles, consumes them, +for the reasons I gave, in telling you the story of Bernard Palissy. +Think of this, oh my dear child, when you are grown up, and never +grudge those who work for you their proper share of food. + +Here I see many other lessons crowding up, out of what you have just +learnt. + +And first Nature herself, taken as you find her, shows you that manual +labor is, for us, a most beneficial condition of existence; that it +brings about a re-doubling, an exaltation of life; and that +consequently, we have no need to look down upon those who gain their +bread, as we word it, by the sweat of their brows. I told you this +before, in speaking of the hand, which is of so much more use to those +people than to you; and I repeat it now for another reason, viz.: +because labor elevates him who undertakes it, and creates a real +physical nobility. Barbarians in old times, who knew nothing noble nor +grand but war, despised labor, and left it to their slaves; so much +so, that the name _servile labor_, _i.e._ the labor of slaves, +has stuck to it in some places. As for war, the lot of the ancient +nobility, I scarcely dare to say much against it, however much I should +like to do so on some accounts. For, after all, so long as there are +ruffians to trample on the weak, one is only too glad to find brave +men ready to risk their lives in keeping such rascals down: so long +as there are wolves, we must needs keep shepherds' dogs. But in spite +of everything, the best that can be said in favor of war is, that it +remains a sad but inevitable necessity, and that to get rid of it, +more is wanting than the wish. What a contrast to labor--that contest +of Man with Nature;--that merciful and fruitful war, where victories +are not estimated like other victories, by the number of the slain, +but which, on the contrary, scatters fresh life around it as it spreads; +fresh life in the laborer himself, by the very act of work, fresh life +around him without, by the fruits that work produces! + +Between the man who dies in slaying others, and the man who keeps +others alive by living longer himself, it seems cruel to make invidious +comparisons; but if it be just to honor the first out of respect for +the cause he has defended, whenever that cause is respectable--it is, +to say the least of it, not less just to do equal honor to the second. + +But let us come down from these philosophic heights, and return to +you, dear child; to you, who have nothing to do with war, its massacres +or its laurels. + +It is true, however, that you have nothing to do either, with chopping +wood, and I am not asking you to undertake any such thing. But in the +life of a woman, from the time of her childhood upwards, a thousand +things arise for the hands to do, and the question is, how often you +are likely to feel ashamed of not sending for the servants to do them? +Avoid this false and fatal idea as much as possible. The work of the +hands dishonors no one; it is honorable. To cast it aside altogether +is to make yourself smaller instead of greater; to deprive yourself +of one of the glories and the joys of life. If a good thing is set +before you at dinner, do you send for the servants to eat it? If an +occasion arises for making the blood circulate more rapidly in your +veins, and of increasing the strength and life with, in you into the +bargain, why make _them_ a present of it? Especially when it +cannot be an agreeable present considering that good servants have +plenty of such opportunities from morning to night every day. + +There was once upon a time a Persian prince staying in Paris, who was +taken to a very fashionable ball, that he might see a specimen of +European civilization. I am not talking about a prince in the "Arabian +Nights;" mine lived, I believe, in the time of Louis Philippe. The +beautiful dancers wheeled round, their eyes brilliant with pleasure, +in the arms of elegant cavaliers; one would have said that the whole +of this airy troop, swaying to and fro in time to the lively flourishes +of the music, was animated by one soul; everything seemed full of joy +in that large and splendidly lit hall, and mothers secretly envied +their daughters as they passed and re-passed before them. Our oriental +alone scanned with a disdainful eye this youthful enjoyment. + +When it was ended,--"How is this?" said he to his conductor; "did you +not tell me that I was to see here the most distinguished families of +Paris?" + +"Certainly," replied the other; "among those young ladies who were +just now dancing before you, there were at least twenty of the grandest +heiresses of France." + +"Young ladies who dance! Come, come! In my country we have dancers, +but they are paid for it. Our wives are never permitted to dance +themselves. That is all very well for the common people!" + +Remember, when needful, the contempt of this Persian prince, my dear +child; and let me beg of you, work for yourself. The dance of labor +is worth quite as much as that of the ball-room, when you give your +heart to it. It is even worth more, very often; and next time I will +tell you why. + + + +LETTER XXV. + +CARBONIC ACID. + +We are going to make acquaintance to-day with a new personage, who +well deserves our attention. It is the child of oxygen and carbon, +[Footnote: This is the name learned men have given to Charcoal.] though +not in the same way that you are the child of your parents. + +To tell you how it is made is more than I am able. It is a _gas_, +or if you like the word better, it is an _air_; for when we say +"gas," we mean "air;" only it is always a different sort of air from +the air of the atmosphere, which learned people are not in the habit +of calling _gas_. I cannot, therefore, show you _carbonic acid_ itself, +for it cannot be seen any more than the air which fills an empty glass. +But I can tell you where there is some, and you even probably know it by +its effects, although you have never heard its name. + +Do you remember, on your aunt's wedding-day, that there was a sparkling +wine called champagne, at the grand breakfast? You smile, so I conclude +somebody gave you a little to taste; and if so, you will remember how +sharp it felt to your tongue. Do you remember, too, how the cork flew +out when they were opening the bottle, and how the noise of the "pop!" +startled more little girls than one? It was _carbonic acid_ which +sent the cork flying in that wild way; the carbonic acid which was +imprisoned in the bottle, in desperately close quarters with the wine, +and which accordingly flew out, like a regular goblin, the moment the +iron wire which held down the cork was removed. What sparkled in the +glass, making that pretty white froth which phizzed so gently, as if +inviting you to drink, was the carbonic acid in the wine, making its +escape in thousands of tiny bubbles. What felt so sharp to your tongue +was the same carbonic acid, in its quality of acidity, for thence it +has its name; the word _acid_ being borrowed from a Latin word +signifying the sharp pungent taste, almost _fine-pointed_ as it +were, peculiar to all substances which we call _acids_. + +It is carbonic acid also which causes the froth in beer and in new +wine when bottled. It is he who makes soda-water sparkle and sting the +tongue, and ginger-beer the same, if you happen to like it; and so far +you have no particular reason for thinking ill of him. But beware. It +is with him as with a good many others who have sparkling spirits, who +make conversation effervesce with gayety, and who are very seductive +in society when you have nothing else to do but to laugh over your +glass, but whose society is fatal to the soul which delivers itself +up to them. This charming carbonic acid is a mortal poison to any one +who allows it to get into his lungs. + +You remember what a violent headache your servant suffered from the +other day after ironing all those clothes you had in the wash? She +owed that headache entirely to this work which she did for you. She +had remained too long standing over the coals over which her flat-irons +were being heated. You know already that when charcoal burns, it is +from the carbon uniting with the oxygen of the air; from this union +proceeds that mischievous child, carbonic acid gas, in torrents, and +the poor girl was ill, because she had breathed more of this than was +good for her health. Observe well, that the room-door was open to let +in the fresh air, and that there was a chimney, to allow the carbonic +acid to escape. It was on this account that she got off with only a +headache. Unhappily, there have sometimes been miserable people who, +weary of life, and knowing this, but not knowing or thinking about the +God who overrules every sorrow for good, have shut themselves up in +a room with a brazier of burning charcoal, after taking the fatal +precaution of stopping up every opening by which air could possibly +get in; and when at last, in such a case, uneasy friends have forced +open the well-closed door, they have found nothing within but a corpse. +Then, too, there are those frightful accidents of which we hear so +often, of workmen groping their way down into long disused wells, who +have died as they reached the bottom; or of sudden deaths in coal-pits. +In general these have been owing to the poor victims encountering the +long pent-up carbonic acid gas, whose poisonous breath blasted and +destroyed them at once. + +You may well ask why I am telling you such horrible stories, and what +I am coming to with my carbonic acid? But you have more to do with it +than you think, dear child. You, and I, and everybody we meet, nay, +and the very animals themselves, since their machines are of the same +sort as ours, are all little manufactories of carbonic acid. The thing +is quite clear. Since there is a charcoal fire lit in every part of +our body, there always arises from the union of the oxygen brought by +the blood with the carbon it meets in our organs, that mischievous +child we have been talking about; and our throat is the chimney by +which he gets away. He would kill us outright were he to stop in the +house. + +This is how it comes about: In proportion as the blood loses its oxygen, +it picks up in exchange the carbonic acid produced by combustion, so +that it is quite loaded with it by the time it returns to the lungs. +There it takes in a fresh supply of oxygen, and discharges at the same +time its overplus of carbonic acid, which is driven out of the body +by the contractions of the chest, pell-mell with the air which has +just been made use of in breathing. You are aware that this air is not +the same at its exit as at its entrance to the body, and that if you +try and breathe it over again it will no longer be of the same use to +you. That is because it has lost part of its oxygen and brings back +to you the carbonic acid which it had just carried off. If you take +it in a third time, it will be still worse for you; and in case you +should continue to persist--the oxygen always diminishing, and the +carbonic acid always increasing in quantity--the air which was at first +the means of your life will at last become the cause of your death. +Try, as an experiment, to shut yourself up in a small trunk, where no +fresh air can get in; or even in a narrow closely-shut closet, and you +will soon tell me strange news. There will be no occasion to light a +charcoal fire for you in there. Enough is kept burning in your own +little stove, and you will poison yourself. + +You see now that the dreadful stories I was telling a short time ago +have something to do with you, and that it is a good thing to be warned +beforehand. And now tell me, when a hundred people--or I ought to say, +a hundred manufactories of carbonic acid--are crowded together for a +whole evening, sometimes for a whole night, in a space just big enough +to allow them to go in and come out; tell me, I say, if that is a sort +of thing which can be beneficial to the health of little girls whose +blood flows so fast, and who require so much oxygen; and whether, on +the contrary, it is not one's duty to keep them away from such scenes? + +There may be amusement there, I know; but the best pleasures are those +for which one does not pay too dearly. I have seen the very wax lights +faint and turn pale all at once, in the very midst of those murderous +assemblies, as if to warn the imprudent guests that there was only +just time to open the windows. + +And this reminds me of a point I had nearly forgotten. Wax-candles arc +like ourselves. In order to burn, they must have oxygen, and, like us, +they are extinguished by carbonic acid. But like us also--and indeed +to a greater extent, because they consume much more charcoal at +once--they manufacture carbonic acid. Hence that very illumination +which affords the company so much pleasure and pride is plainly an +additional cause of danger. Each of those wax-lights which is spread +around with such a prodigal hand, the only fear being that there may +not be enough of them, is a hungry intruder employed in devouring with +all his might the scanty amount of oxygen provided for the consumption +of the guests. + +From each of those cheerful flames--the suns, as it were, of the festive +assembly--shoots out a strong jet of carbonic acid, contributing by +so much to swell out the already formidable streams of poisoned gas, +exhaled to the utmost extent by the dancers. And wait--there is still +something else I was forgetting. You dance. And I told you last time +at what cost you have to dance. You have to make the fire burn much +quicker than usual, that is, to consume a great deal more oxygen at +once, and so you double and treble the activity of the carbonic acid +manufacture: and this just at the moment when it would be so convenient +that it should go on as slowly as possible! After this, you need not +be surprised that people should look fagged and exhausted next morning. +What astonishes me is that they are not obliged to lie in bed +altogether, after treating their poor lungs to such an entertainment. +And even if you have spared your legs, you are not much better off, +as you are sure to find out in time, especially if the thing is repeated +too often. + +When I told you just now that the dance of labor was worth as much as +the dance of the ball-room, was I right or wrong? What do you say +yourself? + +I could repeat the same of theatres--places of entertainment specially +adapted for impoverishing the blood, and ruining the health of the +happy mortals who go there, evening after evening, to purchase at the +door the right of filling their lungs with carbonic acid, not to speak +of other poisons. You must see clearly that such places as those are +not fit for little lungs as dainty as yours; and this may help you to +submit with a good grace when you see people going there without you. +Grown-up people escape moreover, because the human machine possesses +a strange elasticity, which enables it to accommodate itself--one +scarcely knows how--to the sometimes very critical positions in which +its lords and masters place it without a thought. But to do this, it +is well that it should be thoroughly formed and established; for you +run a risk of injuring it for ever, if you misuse it too early in life. +Tell this to your dear schoolboy brother, when he wants to smoke his +cigar like a man. If his lungs could speak, they would call out to him +that it was very hard upon them, at their age, to be so treated, and +that he ought at any rate to wait till they had passed their +examinations! + +But I must not get into a dispute with so important an individual, by +throwing stones into a garden which is not under my care. For you, my +dear child, the moral of this day's lesson--which to my mind is much +more alarming than a hobgoblin tale, since it concerns the realities +of every-day life--is clear; and it is this: + +Seek your amusements as far as possible in the fresh air. In the summer, +when the lamp is lit, bid your mamma a sweet good-night, and go to +bed. In the winter do not wait till there is a great quantity of +carbonic acid in the room where the grown-up people are sitting, before +you retire to your own like a reasonable girl, anxious not to do +mischief to that valuable and indefatigable servant, the poor blood! +Not to mention that if she were to injure him too much, she would have +to bear his grumbling for the rest of her life. We cannot change him +as we change other servants. + + + +LETTER XXVI. + +ALIMENTS OF COMBUSTION. + +We have spent a very long time, my dear child, over the little fire, +which goes on burning secretly in every one of us, quietly devouring +what little girls eat with such a good appetite, quite unsuspicious +of what they are doing it for. However, if I mean to finish the history +of our mouthful of bread, I must push on to its last chapter. + +The _whole_ of what we eat is not burnt, as you may easily suppose; for, +if it were, what would the blood have left to feed the body with, and to +repair in due proportion the continual destruction or waste which goes +on in our organs? Our food, or "_aliments_" as the general collection of +different sorts of food is called, are divided into two very distinct +sets: some, which are destined to be burnt, and which are called +_aliments of combustion_; others, which are destined to nourish the +body, and which are called _aliments of nutrition_. I have to tell you +now about these last, and you will find their history by no means +uninteresting. + +Learned men having detected, beyond the possibility of a doubt, the +existence of these two sorts of aliments, one is tempted to think they +ought to have made it known to the cooks, and that ever since so +important a discovery, the dishes on all well-regulated tables should +have been arranged accordingly; aliments of combustion on one side, +aliments of nutrition on the other. It cannot be enough merely to give +your guests a treat; you ought to provide them with everything necessary +for the proper fulfilment of the claims within; and if you give some +nothing but combustibles, leaving the others no share of fuel, how +will they be able to manage? Nobody thinks about this, however; not +even cooks, to begin with, who, as far as fire is concerned, find they +have had quite enough to do with it in their cooking; and as for the +guests, when they have had their dinner they go away satisfied, as a +matter of course, quite as well provided for as if the mistress of the +house had made her calculations, pen in hand, while writing out the +bill of fare, with a view to combustion and nutrition. Now, how is +that? + +It is because the two sorts of aliments are, for the most part, met +with together in everything we eat, so that we swallow them at once +in one mouthful; and have therefore no need to trouble ourselves further +on the subject. There is our bit of bread, for instance. What is bread +made of? Of flour. Bread, then, must contain all that was previously +in the flour. Very good. Now I will teach you how to discover in flour +the aliment of combustion on the one hand, and the aliment of nutrition +on the other. + +Take a handful of flour, and hold it under a small stream of water; +knead it lightly between your fingers. The water will be quite white +as it leaves it, carrying away with it a fine powder, which you could +easily collect if you were to let the water run into a vase, where the +powder would soon settle to the bottom. That powder is starch--the +same starch as washerwomen use for starching linen, and which our +grandfathers employed in powdering their wigs. You had some put on +your own hair one day when you were dressed up as a court-lady of olden +time. Now, starch is an excellent combustible. People have succeeded, +by means which I will not offer to detail here, in ascertaining almost +exactly what it is made of, and they have found in it three of our old +acquaintances, oxygen, hydrogen, and carbon, combined together in such +proportions that 100 ounces of starch contain as follows: + + Ounces. + Carbon 45 + Hydrogen 6 + Oxygen 49 + --- + 100 +I give you the calculation in round numbers, so as not to burden your +memory with fractions; and I will do the same with the other sums I +shall have to go through to-day, this being, let me tell you, an +arithmetical day. Besides, I could scarcely take upon myself to warrant +the absolute correctness of those very precise fractions people +sometimes go into. Even our learned friends squabble now and then as +to which is right or wrong over the 100th part of a grain, more or +less, in making out their balance, and you and I will not offer to +decide between them. I always think we have accomplished wonders in +getting even _near_ the mark, and with their permission we will +stop there. + +Starch, then, of whose weight carbon constitutes nearly one-half, is +of course a first-rate combustible. Indeed, one may almost consider +it the parent, as it were, of at least half our aliments of combustion, +for if (in consequence of a certain operation, which nature has the +power of performing for herself, in certain circumstances) it loses +a portion of its carbon, so that there remain but 36 ounces of it in +the 100 of starch, our starch is turned into something else; now can +you guess what that something is? Neither more nor less than _sugar_! +Witness the grand manufactories at Colmar, in France, where bags of +starch are converted into casks of syrup by a process of nature alone; +so that the inhabitants of the neighborhood sweeten their coffee at +breakfast with what might have been made into rolls, had it been left +alone. And this is not all. Give back this starch-sugar into the hands +of Nature once more by putting it into certain other conditions, and a +new process begins in it. About a third of its carbon will unite itself, +of its own accord, with the two-thirds of its oxygen, so as to make +carbonic acid, (you are acquainted with that gentleman now) which shall +fly off and away, and there will remain--what do you think?--_Alcohol_, +that other combustible we talked about, and which burns even better than +sugar and starch, since in a hundred ounces it contains as follows:-- + + Ounces. + Carbon 53 + Hydrogen 13 + Oxygen 34 + --- + 100 + +All this astonishes you. What would you say then if I were to tell you +that your pocket-handkerchief is composed of entirely the same materials +as starch, and in the same proportions too, and that if a chemist were +to take a fancy, by way of a joke, to make you a tumbler of sugar and +water, or a small glass of brandy out of it, he could do so if he +chose. Wonders are found, you see, in other places besides fairy tales; +and since I have begun this subject I will go on to the end. Know then +that from the log on the fire, to the back of your chair, everything +made of wood, is in pretty nearly the same predicament as your +pocket-handkerchief; and if people are not in the habit of making casks +of syrup and kegs of brandy out of the trees they cut down in the +woods, it is only, I assure you, because such sugar and brandy would +cost more to make than other sorts, and would not be so good in the +end. Should some one ever invent and bring to perfection an economical +process for doing it thoroughly well, sugar-makers and spirit-distillers +will have to be on their guard! + +But we are wandering from our subject. If I have allowed myself to +make this digression, however, it is because I am not sorry to accustom +your mind early to the idea of those wonderful transformations which +nature accomplishes, and of which I could give you many other instances. + +To return to our flour. As soon as all the starch is gone out of it, +there remains in your hand a whitish, elastic substance, which is also +sticky or _glutinous_, so that it makes a very good glue if you choose; +and hence its name of _gluten_, which is the Latin word for glue. + +When dried, this _gluten_ becomes brittle and semi-transparent. +It keeps for an unlimited time in _alcohol_, putrefies very soon +in water exposed to the air, and is easily dissolved in a wash of soda +or potash. Finally 100 ounces of it contain as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +Observe the last material named. It is a new arrival, of which I shall +soon have something to say. + +But where am I leading you? you will ask, with all these uninteresting +details about glue. + +Wait a little and you shall hear. + +You have probably never seen any one bled, which is a pity, as it +happens; for if you had, you might have noticed (provided you had had +the courage to look into the basin), that after a few seconds, the +blood which had been taken away separated itself of its own accord +into two portions; the one a yellowish transparent liquid, the other +an opaque red mass floating on the top, and which is called the +_coagulum_ of the blood or _clot_. This _coagulum_ owes its color to an +infinity of minute red bodies of which we will speak more fully by and +by, and which are retained as if in a net, in the meshes of a peculiar +substance to which I am now going to call your attention. + +That substance is whitish, elastic and sticky; and when dried becomes +brittle and semi-transparent. It keeps for an unlimited time in alcohol, +putrefies very soon in water exposed to the air, and is easily dissolved +in a wash of soda or potash. Finally 100 ounces of it contain as +follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +This substance is called _fibrine_. It goes to form the fibres of those +muscles which are contained in a half formed state in the blood. + +You are laughing by this time I know, and I also know the reason why. +I have told you the same story twice over. You have not forgotten my +wearisome description of _gluten_, and here I am, saying exactly +the same thing of _fibrine_! You conclude I am dreaming, and have +made a mistake! + +But no, I am wide awake, I assure you, and mean what I say. And if +these details are the same in the two cases, it is for the simple +reason that the two bodies are one and the same thing; _gluten_ and +_fibrine_ being in reality but one substance, so that were the most +skilful professor to see the two together dried, he would be puzzled to +say which came from the flour, and which from the blood. I mentioned +that our muscles existed in a half-formed state in the blood. Here is +something further. The _fibres_ of muscles exist previously in full +perfection, in the bread we eat; and when you make little round pills of +the crumbs at your side, it is composed of fibres stolen from your +muscles which enable the particles to stick together; and I say _stolen +from your muscles_, because they are the _gluten_ which you ought to +have eaten. I hope the thought of this may cure you of a foolish habit, +which is sometimes far from agreeable to those who sit by you. + +This, then, is the first great _aliment of nutrition_, and you +may make yourself perfectly easy about the fate of those who eat bread. +If little girls should now and then have to lunch on dry bread, I do +not see that they are much to be pitied. There is the starch to keep +up their fire, and the gluten for their nourishment, and that is all +they require. The porter above is the only one who finds fault. And +in these days porters have become more difficult to please than the +masters themselves. + +Then as to babies who drink nothing but milk, you perhaps wish to know +where they get their share of fibrine. + +And I am obliged to own there is none in the milk itself; but, I +daresay, you know curdled milk or _rennet_? The same separation into two +portions has taken place there which occurs in the blood when drawn from +the arm; underneath is a yellowish transparent liquid,--that is the +_whey_; above a white curd of which cheese is made, and which contains a +great part of what would have made butter. By carefully clearing the +curd from all its buttery particles you obtain a kind of white powder +which is the essential principle of cheese, and to which the pretty name +of _casein_ is given because _caseus_ is the Latin for cheese. I shall +not trouble you now with details about _casein_; but there is one thing +you ought to know. A hundred ounces of _casein_ contain as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +Exactly like gluten and fibrine! + +Now, then, you can understand that no particular credit is due to the +blood for manufacturing muscles out of the cheese of the milk which +a little baby sucks. He has much less trouble than the manufacturers +at Colmar have in turning their starch into sugar; because in his case +the new substance is not only composed of the same materials as the +old one, but contains them in exactly the same proportion also. + +We have a second aliment of nutrition, you see, and I must warn you +that it is not found in milk only. It exists in large quantities in +peas, beans, lentils, and kidney-beans, which are actually full of +cheese, however strange this may seem to you. It would not surprise +you so much, however, if you had been in China and had tasted those +delicious little cheeses which are sold in the streets of Canton. They +cannot be distinguished from our own. Only the Chinese (from whom we +shall learn a great many things when we have beaten them so that they +will conclude to be friends with us)--the Chinese, I say, do without +milk altogether. They stew down peas into a thin pulp. They curdle +this pulp just as we do milk, and in the same way they squeeze the +curd well, salt it, and put it into moulds--just as we do--and out +comes a cheese at last--a real cheese, composed of real _casein_! +Put it into the hands of a chemist, and ask him the component parts +of a hundred grains of it, and he will tell you as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7, etc. + +I stop there; for you surely know the list by this time! + +Only the third aliment of nutrition remains to be considered, for there +are but three; and I will tell you in confidence, what is stranger +still, viz., that there is in reality but one! But we have had enough +food for one day, and I do not wish to spoil your appetite. We will +reserve the rest for another meal. + + + +LETTER XXVII. + +ALIMENTS OF NUTRITION (_continued_). + +NITROGEN OR AZOTE. + +There is a favorite conjuring trick, which always amuses people, though +it deceives no one. The conjuror shows you an egg, holds it up to the +light that you may see it is quite fresh, then breaks it; +and--crack--out comes a poor little wet bird, who flies away as well +as he can. + +This trick is repeated in earnest by nature every day, under our very +eyes, without our paying any attention to it. She brings a chicken out +of the egg, which we place under the hen for twenty-two days, instead +of eating it in the shell as we might have done, and we view it as a +matter of course. Yet we do not say here that the bird may not have +come down the conjuror's sleeve, or the hen may not have brought it +from under her wing. It was really in the egg, and its own beak tapped +against the shell from within and cracked it. + +How has this come about? No one can have put that beak, those feathers, +those feet, the whole little body, in short, into the egg while the +hen was sitting upon it, that is certain. It is equally certain, then, +that the liquid inside the egg must have contained materials for all +those things beforehand; and if Nature could manufacture the bones, +muscles, eyes, etc., of the chicken, out of that liquid while in the +egg, she would probably have found no more difficulty in manufacturing +your bones, muscles, eyes, etc., from it had you swallowed the egg +yourself. + +Here, then, is an undeniable _aliment of nutrition_. + +It is called _albumen_, which is the Latin word for _white of egg_. It +is easily recognized by a very obvious characteristic. When exposed to a +temperature varying from sixty to seventy-five degrees of heat, +according to the quantity of water with which it is mixed, _albumen_ +hardens, and changes from a colorless transparent liquid, into that +opaque white substance, which everybody who has eaten "hard-boiled eggs" +is perfectly well acquainted with. + +I will only add one trifling detail. 100 ounces of albumen contain as +follows: + + Ounces. + Carbon 63 + Hydrogen -- + +You can fill up this number yourself, can you not? And knowing the 7 +of hydrogen, you may guess what follows! After what we have talked of +last time, here is already an explanation of the chicken's growth. But +let us go on. + +You recollect that yellowish liquid I spoke about, which lies underneath +the _clot_, or _coagulum_ of the blood? I will tell you its name, that +we may get on more easily afterward. It is called the _serum_, a Latin +word, which, for once, people have not taken the trouble of translating, +and which also means _whey_. Put this _serum_ on the fire, and in +scarcely longer time than it takes to boil an egg hard, it will be full +of an opaque white substance, which is the very _albumen_ we are +speaking of. Our blood, then, contains _white of egg_; it contains in +fact--if you care to know it--sixty-five times more white of egg than +fibrine, for in 1,000 ounces of blood, you will find 195 of _albumen_, +and only three of _fibrine_; of _casein_, none. + +Nevertheless we eat cheese from time to time. And we generally eat +more meat than eggs, and meat is principally composed of fibrine! I +should be a good deal puzzled to make you understand this, if we had +not our grand list to refer to. + + Ounces. + Carbon 63 + Hydrogen 7, etc. + +_Fibrine_, casein_, _albumen_, they are all the same thing in the main. +It is one substance assuming different appearances, according to the +occasion; like actors who play several parts in a piece, and go behind +the scenes from time to time to change their dresses. The usual +appearance of the aliment of nutrition in the blood is _albumen_; and in +the stomach, which is the dressing-room of our actors, _fibrine_ and +_casein_ disguise themselves ingeniously as _albumen_; trusting to +_albumen_ to come forward afterwards as _fibrine_ or _casein_, when +there is either a muscle to be formed, or milk to be produced. + +Know, moreover, that _albumen_ very often comes to us ready dressed, and +it is not only from eggs we get it. As we have already found the +_fibrine_ of the muscle and the _casein_ of milk in vegetables, so we +shall also find there, and that without looking far, the albumen of the +egg. It exists in grass, in salad, and in all the soft parts of +vegetables. The juice of root-vegetables in particular contains +remarkable quantities of it. Boil, for instance, the juice of a turnip, +after straining it quite clear, and you will see a white, opaque +substance produced, exactly like that which you would observe under +similar circumstances in the _serum_ of the blood; real _white of egg_, +that is to say--to call it by the name you are most familiar with--with +all its due proportions of carbon, hydrogen, oxygen, and nitrogen. + +I wonder whether you feel as I do, dear child; for I own that I turn +giddy almost when I look too long into these depths of the mysteries +of nature. Here, for instance, is the substance which is found +everywhere, and everywhere the same--in the grass as in the egg, in +your blood as in turnip-juice! And with this one sole substance which +it has pleased the great Creator to throw broadcast into everything +you eat, He has fashioned all the thousand portions of your frame, +diverse and delicate as they are; never once undoing it, so to speak, +to re-arrange differently the elements of which it is composed. From +time to time it receives some slight impulse which alters its appearance +but not its nature, and that is all. As the chemist found it in the +bit of salad, so he will find it again in the tip of your nose, if you +will trust him with that for examination. We are proud of our personal +appearance sometimes, and smile at ourselves in the looking-glass; we +think the body a very precious thing; but yet when we look deeply into +it we find it merely so much charcoal, water and air. + +This reminds me that we have not yet made acquaintance with the new +personage who was lately introduced upon the scene. _Nitrogen_ or +_azote_, I mean. He plays too important a part to be allowed to remain +in obscurity. + +You have already learnt that oxygen united with hydrogen produces +water. Combined with nitrogen it produces air; but in that case there +is no union of the two. They are merely neighbors, occupying between +them the whole space extending from the earth's surface to forty or +fifty miles above our heads; together everywhere, but everywhere as +entire strangers to each other as two Englishmen who have never been +introduced! I should be a good deal puzzled to say what nitrogen does +in the air: he is there as an inert body, and leaves all the business +to the oxygen. When we breathe, for instance, the nitrogen enters our +lungs together with its inseparable companion, but it goes out as it +went in, without leaving a trace of its passage. Nevertheless, as +sometimes happens among men, the one who does nothing takes up the +most room. Nitrogen alone occupies four-fifths of the atmosphere, where +it is of no other use than to moderate the ardent activity of king +oxygen, who would consume everything were he alone. I can compare it +to nothing better than to the water you mix with wine, which would be +too fiery for your inside if you drank it by itself. This is what +nitrogen does. It puts the drag on the car of combustion; as in society, +the large proportion of quiet people put the drag on the car of progress +(let us for once indulge ourselves in talking like the newspapers!); +and such people are of definite use, however irritating their +interference may appear in some cases. The world would go on too rapidly +if there were nothing but oxygen among men. We have quite enough in +having a fifth of it! + +But what in the world am I talking about? Let us get back to nitrogen +as fast as we can! + +We must not imagine there is no energy in this quiet moderator of +oxygen. Like those calm people who become terrible when once roused, +our nitrogen becomes extremely violent in his actions when he is excited +by another substance, and is bent on forming alliances. Sometimes the +usually cold neighbor unites itself to oxygen in the closest bonds; +in which case the two together form that powerful liquid, _aqua-fortis_, +of which you may have heard, and which corrodes copper, burns the skin, +and devours indiscriminately almost everything it comes in contact with. +Combined with hydrogen, nitrogen forms _ammonia_, which is still often +called by its old name _volatile alkali_; one of the most powerful +bodies in existence, and one for which you would very soon learn to +entertain a proper respect, if somebody were to uncork a bottle of it +under your nose. Finally, nitrogen and carbon combined, produce a quite +foreign substance (_cyanogen_), resembling neither father nor mother in +its actions and powers, to the confusion of all preconceived ideas, when +Gay-Lussac, a Frenchman, introduced it to the world, where it fell like +a bombshell upon the theory of chemical combinations. This impertinent +fellow, combining with hydrogen in his turn, produces _prussic acid_, +the most frightful of poisons; one drop of which placed on the tongue of +a horse strikes it dead as if by lightning. + +You perceive that you must not trust our worthy friend too far. You +have learnt, however, elsewhere, that it is not equally formidable in +all its combinations. Those very substances which, when paired off +into small separate groups, destroy all before them, constitute, all +four together, that precious aliment of nutrition of which we are +formed. Moreover, its real name is "_azotized aliment_" because +it is the presence of nitrogen or azote in it, which, above all, +determines its quality, so that people are in the habit of estimating +the nourishing power of our food by the amount of nitrogen it contains. +In fact, nitrogen seems to be a substance especially inclined towards +everything that has life. His three comrades wander in mighty streams, +so to speak, through every part of creation; but he, except in the +vast domain of the atmosphere, where he reigns in such majestic repose, +is rarely met with, except in animals, or in such portions of plants +as are destined for the support of animal life. + +On this point I will tell you the history of his original name, +_azote_, which you will find curious enough. A short time before +the French Revolution, in 1789, the principal properties of this gas +were made known to the world by a learned Frenchman, who may be almost +considered the father of modern chemistry, and whose name I must beg +you to recollect. [Footnote: Dr. Daniel Rutherford (Edinburgh) +discovered the existence of _Nitrogen_, A. D. 1772; but he never +investigated its character.] He was called _Lavoisier_. While +endeavoring to account satisfactorily for _combustion_, which +before his time people explained any way they could, Lavoisier succeeded +in separating our two friends, the neighbors in the atmosphere, one +from the other, and was the first man in the world who managed to +secure in two bottles--on the one hand, the bubbling oxygen freed from +his tiresome mentor; on the other, the sober *azote, snatched away +from his giddy pupil. What he did with the bottle of oxygen matters +but little to us; but in the bottle of _azote_ he plunged, by way +of experiment, an unfortunate mouse, and subsequently a little bird, +both of whom, finding no oxygen to breathe, died one after the other. +Nothing could live in it, as you may suppose; and Lavoisier thought +it must be right to give so destructive a gas the name of _azote_, +which in Greek means "_opposed to life_." Meantime, science went +on progressing by the gleam of the lamp he had lit, and then followed +the discoveries of his successors, who forced their way into the obscure +laboratory where the elements of living bodies are prepared. And at +last it was ascertained that this _azote_, opposed to life as it +was thought to be, was actually an essential property of life; that +it accompanied it everywhere, and that without it the whole framework +of the animal machine would fall to pieces. It is still known by its +old name, which custom had sanctioned; but I imagine no learned man +can ever utter it now without a feeling of humility, and without the +thought that the future has possibly many contradictions in store for +him also. Besides, nitrogen has to pass through many fine-drawing +processes before it attains that post of honor which has been assigned +to it in the animal kingdom. The animal himself can do nothing with +it, unless it has been previously absorbed and digested by the +vegetable, and the vegetable in its turn could get no good from it, +were it to remain isolated and indifferent in the bosom of the +atmosphere. It is only when it has formed one of those combinations +I have been telling you about, and more particularly the second, which +produces _ammonia_, that it fairly enters upon the round of life. +And then, in the mysterious depths of vegetable existence is organized +that wonderful _quadrille_ of the _aliments of nutrition_, the history +of which has now been sufficiently explained to you. + +The vegetable kingdom, therefore, is simply the great kitchen in which +the dinner of the animal kingdom is being constantly made ready; and +when we eat beef, it is, in fact, the grass which the ox has eaten, +which nourishes us. The animal is only a medium which transmits intact +to us the _albumen_ extracted in his own stomach from the juices +furnished to him in the fields. He is the waiter of the eating-house; +the dishes which he brings us have been given him already cooked in +the kitchen. But to appreciate properly the service he renders us we +must remember that the dishes to be obtained from grass are very, very +small, and that it would be a great fatigue to the stomach if it could +only get at such tiny scraps at a time; as, alas! has sometimes happened +to the famine-stricken poor, who have tried in vain to support life +from the grass in the field. But these minute dishes are brought to +us in the mass whenever we eat beef, and our stomachs benefit +accordingly. Do not forget this, my child; and when mamma asks you to +eat meat, obey her with a good grace; if, that is to say, you wish to +grow up to be a woman. + + + +LETTER XXVIII. + +COMPOSITION OF THE BLOOD. + +One word more before we finish. We must not leave off without bidding +a last farewell to the good servant of whom we have spoken so much; +the model steward so exact in giving back everything he receives--the +factotum of the house in short. We have watched him at work long enough, +but I have not yet described him personally to you, nor told you exactly +what he is composed of. + +And here I shall be obliged to begin again with figures and +calculations, although I am told young people are not very fond of +them. Nevertheless, none of us can manage our affairs properly without +them. Hereafter, when you are at the head of a family, you will be +obliged to practise arithmetic, if you want to know what is going on +in your house. Never allow yourself to look upon what is necessary as +wearisome; the true secret of being punctual in our duties is to throw +our heart and interest into them. + +I choose, therefore, to suppose that you will be interested to know +that 1000 ounces of blood generally contain, (for there are shades of +difference between one sort of blood and another) 870 ounces of the +_serum_ I have been talking about, and 130 ounces of _clot_. At first +sight one would take the quantity of _clot_ to be much greater than it +really is; but in the state you see it, in the basin, it contains a +considerable amount of water, which belongs by right to its companion +_serum_, and which has to be drained away from it before it can be +weighed. + +Now, in our 870 ounces of serum, we shall find, to begin with, 790 of +water; do not be astonished at the quantity. Most of the weight of all +animals is produced by water; they weigh comparatively nothing after +being thoroughly dried in a stove--when they are dead of course--for +neither animal nor plant can live unless saturated with water. This, +by the way, may serve to explain the ease with which we can keep +ourselves floating in water; we are not much more than water ourselves! +Were it not for those abominable bones which are a little bit heavier +than the rest, we should never sink unless a stone were hung round our +necks. + +I repeat then; 790 ounces of water in 870 of _serum_, which leaves 80. +Of this, _albumen_ furnishes seventy, and the ten others, with the +exception of a small portion of fat which floats here and there +ready-made, are _salts_. It would take too long to explain what _salts_ +are here, but there is one sort of salt you know perfectly well; viz., +that which is put on the dinner-table in a salt-cellar. And it is the +most important of all. More than half the ten ounces of salts consist of +it alone, which will make you understand better than before, what I +explained with reference to the stomach; that is, why we put salt in our +food. The porter above is quite up to his business when he asks everyone +who enters to produce his little bit of salt. It is an attention which +the blood appreciates very highly, although table-salt is of no great +use to him in his building operations; but it evidently keeps him in +good humor, and he would work badly without it. It is the same with all +the animals man makes use of, and even the plants he cultivates, find +that salt gives them an appetite. And it would almost seem as if nature +had purposely dealt with us in this matter on a magnificent scale. She +has made salt-magazines of the sea and the bosom of the earth, where it +exists in prodigious masses which cost nothing but the labor of stooping +to pick up, except in countries where a gentleman called a tax-gatherer, +stands by to count the lumps and allow them to pass on by paying a +duty. For my part, if I were the government--this is a secret between +you and me, mind--I would look out for something else to stand in the +place of the salt-tax. It is not well to interpose between man and the +gratuities of Dame Nature, and to make him pay more heavily for the +blood's chosen friend than she meant him to be charged. + +But to proceed, the kitchen-salt being deducted from the ten ounces +of salts-in-general, there remain altogether from four to five ounces, +which contain----. But here I stop, for it puzzles me very much how +to go on! Enough, that to enable you to follow me, you would require +at least as much knowledge of chemistry as will be expected of a young +man who has to pass an examination in medicine. Fancy the contents of +a whole druggist's shop! I will tell you a few names, that you may +have a specimen of the style in use, but I forewarn you that they are +not inviting: _hydrochlorate of ammonia; hydrochlorate of potash; +carbonate of lime; sulphate of potash; phosphate of lime; phosphate +of magnesia; lactate of soda._ I spare you the others, for many +others there are, without counting those which have not yet been +discovered I All these things are to be found, I must tell you, in +fibrine and albumen, but in such minute quantities that it is scarcely +possible to recognize them. + +In the serum, for instance, the gentlemen are so very small, and so +completely entangled one with the other, that it is startling to think +of the skill and patience requisite for making them all out, to say +nothing of affixing the right name--uncouth as it may seem--to each +grain of this almost imperceptible dust! He who first called man an +epitome of creation, scarcely knew how truly he was speaking, for man +bears about in his veins, ascertained samples of at least half the +primitive substances from which all others are made, and if the whole +of them should some day be found to be there, I for one should not be +surprised. + +This is well worth knowing, is it not? and I have not come to the end +of my story yet. + +We have still the 130 ounces of _clot_ to speak about. But their +contents are easily reckoned. Three ounces of fibrine and 127 of +_globules_. + +Here, however, we enter upon such a world of wonders, that I am quite +delighted to be able to finish with it. It will be the masterpiece of +our exhibition! + +You feel quite sure blood is red, do you not? Well! it is no more red +than the water of a stream would be, if you were to fill it with little +red fishes. Suppose the fishes to be very very small, as small as a +grain of sand; and closely crowded together through the whole depth +of the stream: the water would look quite red, would it not? And this +is the way in which blood looks red: only observe one thing; a grain +of sand is a mountain in comparison with the little red fishes in the +blood. If I were to tell you they measured about the 3,200th part of +an inch in diameter, you would not be much the wiser, so I prefer +saying (by way of giving you a more striking idea of their minuteness) +that there would be about a million in such a drop of blood as would +hang on the point of a needle. I say so on the authority of a scientific +Frenchman--M. Bouillet. Not that he ever counted them, as you may +suppose, any more than I have done; but this is as near an approach +as can be made by calculation to the size of those fabulous +blood-fishes, which are the 3,200th part of an inch in diameter. + +These littlest fishes are called _globules_; but they are not +exactly shaped like _little globes_, as the word would lead you +to suppose. They are more like little plates slightly hollowed out on +both sides. The central nucleus is surrounded by a flattened margin +rather bladdery in appearance, of a beautiful red color, formed of a +sort of very soft and very elastic jelly. I scarcely need tell you +that all this was discovered through the microscope, and moreover, by +examining the blood of frogs, in which the globules are much larger +than in ours. [Footnote: Authentic portraits of these globules drawn--so +to speak--by Nature herself, are to be seen on the admirable Photographs +obtained by Bertsch, with the aid of the solar microscope, invented +by himself and Arnaud. There you see them magnified 250,000 times, and +may study them at your ease, and verify my description for yourself +without any fear of being deceived. You must persuade your father to +procure one. This result of photography is among the wonders of modern +science.] + +It was in 1661--rather more than two hundred years ago--that an Italian +and a Dutchman discovered, each by himself in his own country, the +microscopic population of the blood. The name of the Italian is not +very difficult--_Malpighi_. As to the Dutchman's, you must pronounce it +in the best way you can--he was called _Leeuwenhock_. You smile, but he +was nevertheless one of the first men who really comprehended what a +wonderful auxiliary human science had just got hold of in the +microscope, and he has helped to open the eyes of the world to the +marvels of miniature creation. So content yourself, young lady, with +mis-pronouncing his name, and beware of laughing at it! Names are +something like faces, one may live to be ashamed of ridiculing +the wrong one. + +This discovery of the globules of the blood, was destined to throw +great light upon the way in which the _nutrition of the organs_ +was carried on. Modern chemists, who are always fond of investigation, +have examined what they are made of, and can find little else in them +but _albumen_. Out of our 127 ounces of globules, 125 are albumen; +and these, with the 70 ounces which we found before in the serum, make +up the 195 ounces (of albumen) which I told you were contained in the +1,000 ounces of blood. Forgive me all these ounces and figures. Exact +accounts give exact information. + +These globules, then, are composed almost entirely of albumen. Nearly +two-thirds of all the albumen in the blood is concentrated in them; +and you know now the use of albumen, viz., that it is the foundation +of all the buildings of which the blood is the architect. Everything +leads us to believe that the formation of globules in the blood is the +last touch given by nature to that magical provision begun in +thevegetable, continued in the stomach, and finished in the veins, to +which, in combination with carbon, hydrogen, oxygen, and nitrogen, we +are indebted for the subsistence of every portion of our body. Thus +the blood-globules may be considered as albumen which has finished its +education, and is ready to go into the world; while the albumen of the +serum is, like our young friends, the generations in reserve, who are +still at school awaiting their turn. + +This is more than a mere supposition. Scientific men have taken to +themselves, on their own authority, all sorts of rights over animals, +and we profit basely enough by their crimes--I will not withdraw the +word--in order to increase our knowledge. Accordingly, they conceived +the idea of opening the veins of animals, and allowing the blood to +flow until the victim was prostrate and motionless as a corpse. This +done, they proceeded to fill the exhausted veins with blood, similar +to that which had been withdrawn, and with the blood, life was seen +gradually to return, till the animal rose from the ground, walked, and +resumed its disturbed existence, as if nothing had happened. The +interesting part of the experiment to us is, that if serum only, without +globules, be restored to the unfortunate animal, it is of no use +whatever, and the corpse does not revive. + +It is evident, then, that all the power and virtue of the blood lies +in the globules; and according as their number is great or small it +is "rich" or "poor," as it is called; and where their number is not +up to the mark, the blood acts more feebly on the organs, life is +calmer, and people are no longer troubled with emotions--in other +words, with violent heats of the blood. Hence the impassible character +of _lymphatic_ people, who often get on in the struggle of life +better than others, because they are never in a hurry, and know how +to wait for opportunities. You will occasionally hear the word +_lymphatic_, for it has become the fashion, and it is time for +me to explain it; but unluckily the explanation is not in its favor. + +You remember those little scavengers we spoke about formerly, who came +from the depths of all the organs, carrying away with them the worn-out +building materials, and covering the surface of the body with an +inextricable net work of tiny canals. These canals are called +_lymphatic vessels_, in consequence of being filled with a liquid +which is called _lymph_ (_water_, in Latin), but why I cannot +tell you, for it is, in fact, simple _serum_. There was a very +simple way of ascertaining this by making out an inventory of the +contents of the _lymph_ liquid, and when this was done, they were +found to consist of water, albumen, and the salts of serum; there was +even a little fibrine; the only thing wanting was _globules_. + +How the truant serum finds its way into the lymphatic vessels is +probably as follows:--I have already mentioned the inconceivable +delicacy of the capillary vessels, those last ramifications of our +arteries and veins. It needs all the impulsive power of the heart to +enable the blood to force its way through these narrow passages; and +minute as are the globules, it would seem that they have but just room +to pass, for in examining under the microscope a corner of the tongue +of a live frog, the globules have been seen doubling themselves up to +pass through the capillaries, resuming their natural form afterwards. + +It was this, indeed, which made me tell you just now that their margins +were elastic. During this momentary crush, part of the serum being +forced on too fast, oozes through the wall of the over-filled +capillaries, as water oozes through the leathern pipes of a fire-engine, +and hence probably the appearance of serum or _lymph_ in the organs, +where it is immediately sucked up (i. e., _absorbed_) by the lymphatic +vessels. Now, you will easily understand that the larger the proportion +of serum in the blood, the greater will be the quantity to be expelled +in passing through the capillaries, and the more will the lymphatic +vessels swell. In such cases the temperament or constitution is said to +be _lymphatic_. If, on the contrary, the globules are in excess, the +lymphatic vessels receive less serum, and diminish in size. The +temperament is then called _sanguine_, as if there were no serum in the +blood. You shall be judge yourself, knowing what you now do, whether it +would not be more reasonable to call such temperaments _serous_ and +_globulous_. At any rate those names would give people an idea of the +real state of things, and teach them that there were such things as +globules in the blood. + +[Footnote: Here is a summary of the contents of 1000 oz. of blood:-- + + Ounces. + Water................... 790 + Serum. Albumen...................70 870 + Salts.................... 10 + + Fibrine................... 3 + Clot. Globules Albumen.. 125 130 + Coloring matter...... 2 127 + ---- + 1000 + ----] + +To conclude, I must give you an account of the two ounces which still +remain of the 127 of globules, albumen taking up only 125, as you know. +Those two poor little ounces--the remainder of the thousand with which +we started--would you believe it?--they alone have the honor of +conferring upon the blood its beautiful red color. They constitute the +coloring matter of the globules, and you will never guess its chief +element. It is iron; ay, actually iron, young lady--the iron of swords +and bayonets. We often accuse it of tingeing the earth with blood; and +you may now know further, that it reddens blood itself by way of +compensation. Do not trouble yourself as to where it comes from. Our +fields are full of it, our very plants have stores of it. It sometimes +happens that our digestive apparatus, put out of order by other +occupations, fails to make use of the amount of iron offered to it; +in which case the blood is discolored, and the face turns pallid as +wax: this is an illness requiring great care. If it should ever befall +you, you will not be surprised, after to-day's lesson, to hear the +doctor say that you must have some iron. But be easy--you will not +have to swallow it whole! If you will take my advice, you will obey +the doctor's orders as soon as you can. + +Not that looking pale signifies any thing: indeed, some young ladies +think it an advantage. But it is no advantage to any body when the +blood-globules are distressed for want of their proper supply of iron, +and do their work grudgingly, like ill-fed laborers. Nothing can go +on without them, you know, and they are people whom it is not well to +leave too long out of sorts. Else languor comes on; languor which is +the beginning of death: and pray remember that iron, which so often +causes death, is equally useful for keeping it at bay. By sending it +to the discolored globules, you give them back their energy and +brilliancy together. + +I have come here to the end of all that is known with any certainty +about these wonderful globules which are to us the medium of life. +Shall I go further, is the question, and take you with me into the +fields of supposition, so full of noxious weeds? And yet why not? +Science owes its present position to the praiseworthy rule of never +adopting any theory which is not supported by well-established facts; +and I would be the last to advise a change. Were I to tell you, what +I am now going to say to you, at a meeting of the British Association +of Science, they would turn me out of the room, and with very good +reason. Nothing ought to be taught there but what can be proved. But +this is of no consequence to you and me, and we have a right to amuse +ourselves a little, after having worked so hard. + +Well, there is an idea which nothing shall ever drive out of my head, +however imperfectly it may be proved as yet; namely, that each of our +globules is an animated being; and that our life is the mysterious +result of these millions of lesser lives, each of them insignificant +in itself; in the same way that the mighty existence of a nation, is +a compound of crowds of existences, each, for the most part, without +individual importance. Take our own or any other country as an instance; +where millions of brains, many of them by no means first-rate in power, +go to form a national character, the highest (as each _nation_ +is apt to think of itself) in the world. According to this idea, you +must be a sort of nation yourself, my dear child, which is gratifying +to think of on the whole. + +This is much more extraordinary than what I told you some time ago, +of the individual life of the organs, each of which on this new system +would be a province in itself! Do not exclaim too hastily. Whether the +globules are animated or not, it is very certain, let me tell you, +that your life depends entirely upon them; that it is weakened if they +are weakened; that it revives with them; and that whether you attribute +individual life to them or not, makes no alteration in the fact: their +action upon you remains the same. And he must be a very clever man who +can show me the exact difference between action and life. Hereafter, +when we have descended the scale of the animal world together, and are +arrived at the study of what are called microscopic animals, you will +better understand the words which appear so strange to you now. What +little our feeble instruments have revealed to us so far, of the history +of those globules, places them almost on a level with those strange +creatures, inexplicable to us, which are found in innumerable +multitudes, in a variety of liquids. We trace in them the beginning +of organization; their form and size are alike in all individuals of +the same species; and species vary enough to induce one to believe, +that there is a necessary relation between an animal's way of life and +that of its globules. If the microscope has not yet caught them in any +overt living act, who can be surprised? it is only dead blood which +has been submitted to the test. They ought to be observed in the +exercise of their functions, in the living animal itself, as has been +done to some extent in the frog; and if our foolish chat could influence +scientific observers, I would say to them what M. Leverrier said years +ago to the astonished astronomers: "Look yonder; you ought to see a +light there with which you are not yet acquainted!" + +I am carrying you a long way on the wings of my fancy, my dear child; +but have no fears; I will not let you fall. This life of our globules, +which would, after all, be only one mystery the more among many, opens +before our eyes a magnificent vista of the uniformity in the scheme +of creation; which goes on repeating itself, while enlarging its circles +to infinity. We may, all of us, be only so many globules of the great +invisible fabric of humanity, in which we go up and down one after +another; and those vast globes which our telescopes follow through +celestial space, may be but globules of one, as yet unknown, to which +the Almighty alone can give a name. + +Take this page to your father, my dear child, if you do not understand +it rightly; and now, shake hands, my history is ended! + + + +PART SECOND--ANIMALS. + +LETTER XXIX. + +CLASSIFICATION OF ANIMALS. + + +'It is dangerous to show man how much he resembles the beasts, without +at the same time pointing out to him his own greatness. It is also +dangerous to show him his greatness, without pointing out his baseness. +It is more dangerous still to leave him in ignorance of both. But it +is greatly for his advantage to have both set before him.'--_Pensées +de Pascal_. + +The man who wrote that, my dear child, did not trouble himself much +about children. He was one of the gravest specimens of literary +genius--a man who can scarcely be said to have ever been a child +himself; for as the story goes, he was found one day, when only twelve +years old, inventing geometry, and his father only saved him from +trouble, by putting the great book of Euclid into his hands; and, at +sixteen, he wrote a treatise on _Conic Sections_, which was the +wonder of all the learned men of the day. I have not a very clear idea +of what Conic Sections are myself; but I tell you this to show that +Pascal was a very profound and learned man, under whose authority, +therefore, I am very glad to take shelter, now that I am going to set +before you the very startling points of resemblance which exist between +you and the beasts. + +As to your greatness, it delights me to explain it to you. It is not +due to the handsome clothes you wear when you are going out, nor to +the luxurious furniture of mamma's drawing-room, but to the possession +of that young soul which is beginning to dawn within you, as the sun +rises in the morning sky, and pierces through the early mists; in that +growing intelligence which has enabled you to understand so far all +the pretty stories I have told you; in that fresh unsullied conscience, +which congratulates you when you have been good, and reproves you when +you have done wrong: all of them gifts which are not bestowed on the +lower animals, or certainly not to the same extent as upon you--gifts +by which you rise more and more above them, the more they are developed +in yourself. Your baseness--but, begging Pascal's pardon, I cannot +call it baseness--your connecting link with the brute creation lies +in those other gifts of God which you and they share in common--in +those wonders of your organization, which we shall now meet with in +them again, in full perfection at first, and that in every respect; +by which fact you may learn, if you never thought of it before, that +the lower animals come from the same creating hand as yourself, and +ought to be looked upon to some extent as younger brothers, however +distasteful such a notion may seem at first. Societies have been +established of late, both in France and England, for the protection +of animals; and a noble and honorable task they have undertaken, in +spite of the jokes that have been made at their expense. It is a +mischievous cavil to tell people who are doing good in one direction, +that more might have been done somewhere else. Everything hangs together +in the progress of public morality, and you cannot strike a blow at +cruelty to animals without at the same time making a hit at cruelty +to man. And the best argument in favor of the rights of beasts to +protection, will be found in the tour you and I are now going to make +together through the different classes of the animal creation. + +Let us begin with the horse--one of the beasts which oftenest needs +our protection. Give him the mouthful of bread whose history we have +just finished. He accepts it as a treat, and needs no pressing to eat +it. And if it could tell you all its adventures afterwards, you would +find that you were listening to precisely the same story as your own +over again; that nothing was different, nothing wanting. First of +all--teeth to grind it, and a tongue to swallow it with, as a matter +of course. Next a _larynx_, which hides itself to avoid it, and an +oesophagus,* which receives it, just as in your case; a stomach with its +_gastric juices_, the same as yours, in bagpipe form, and its _pylorus_, +like your own; a _lesser intestine_, into which bile pours from a liver +like yours; _chyliferous vessels_ which suck up a milky chyle, as with +you; farther on a _large intestine_; and so on to the end. Nor is this +all:--the horse has also a heart, with its two _ventricles_, and its +double play of valves; a heart which the little girl in our tale might +confidently have exhibited to the engineers as her own, but that it +would have been somewhat too big, of course; into which heart, as into +ours, comes _venous_ blood, to be changed afterwards to _arterial_; in +lungs to which the air keeps rushing, forced thither by the see-saw +action of a _diaphragm_, as faithful a servant to him as to you. +And those lungs like our own, are a charcoal market: the same exchange +takes place there, of carbonic acid for oxygen, as in ours, an +unanswerable proof that the stove inside the horse burns fuel in the +same way as our own: and if you were to place the thermometer inside +his mouth (for we are polite enough to call it his mouth), it would +mark 37 1-2 degrees of heat (centigrade)--a difference from ourselves +not worth mentioning. Finally, if you examine his blood, you will meet +with the same _serum_ and _clot_, the whole company of _hydroclorates, +phosphates, carbonates, &c._, from which we shrank before, and globules +made like your own; having the same construction, and the same life, or +action, if you like it better. I need scarcely add that 100 oz. of its +_fibrine_ and _albumen_ contain: + + Of carbon......... 63 oz. + Of hydrogen........ 7 + +This is understood all along as being the case everywhere, from man +down to the turnip; so that, like you, this noble animal, as the horse +is called, is in point of fact only so much carbon, so much water, and +so much air, joined to a handful of salt, which represents the earth's +share in the bodies of animals. + +You must confess that, if we cannot quite call the horse a +fellow-creature, he is nevertheless very like us. And it is the same +with all those animals which man makes use of as his servants, and +which have really a sort of right to the protection of society, since +they form, to a certain extent, a portion of the human family. I do +not speak here of the dog, who pays his taxes, poor fellow, in his +quality of friend to man. + +When I think of the almost identical organization of man and his +next-door neighbors, I am astonished how it could possibly have come +into the head of a certain learned individual (I will not mention his +name), when drawing up a plan of natural history, to give to man a +separate kingdom, as a sequel to the three kingdoms already +established--the mineral, vegetable, and animal. One might have forgiven +Pascal if such an idea had got into his head after writing his treatise +on Conic Sections; there being nothing in them to throw light on such +a subject. But in a naturalist, an observer who had spent his life in +the study of living creatures, the thing seems almost incredible. +Possibly he had reasons for what he did, but he certainly did not find +them in the subjects of his studies. + +Forgive me, my dear child, for forgetting you in this fit of indignation +upon a point you cannot care much about. It leads me naturally enough +to my present business, which is none of the easiest, but you must +help me by paying attention. I am going to describe the _classification +of the animal kingdom_. + +There are a terrible number of animals, as you know; and if we wish +to study them to any real purpose, we must begin by introducing some +sort of order into the innumerable crowds which throng, pell-mell, +around us for observation. We should otherwise never know where to +begin, or when we had come to an end. + +There are many ways of setting a crowd in order, but they all go upon +the same plan. The individuals composing the crowd are parcelled off +into companies, each company having a distinguishing mark peculiar to +those who compose it. Thus the first division is into a few large +companies, which are afterwards subdivided into smaller ones, and those +into others still less, until the divisions have gone far enough. And +this is what is called a _classification_. + +Let us imagine, as an example, a large crowd in a public garden; I +will soon classify it for you. I shall put the men on one side and the +women on the other. Then--to begin with the women--I shall subdivide +them into married and single. Then among married women I shall make +a company of mammas, and another of those who have no children. Among +the unmarried I shall have a group of those who have never been +married--girls, that is--and another of widows--those who were once +married, but are so no longer. Then, following the girls, I shall +separate them into tall and short. And among the short ones I shall +divide the brunettes from the blondes, and so I shall get at last to +a little blonde girl, whose classification (were she a soldier) in +military rank would be as follows:--_squadron_ of blondes; _company_ of +shorts; _battalion_ of girls; _regiment_ of unmarried women; _division_ +of women. The division of men could be carried out in the same manner; +and thus we should classify our mob into complete military order. This +is easy enough, however; but the classifying of animals is a very +different affair, and I will tell you why. We ourselves require a +classification to study them by, though none was needed for their +creation. The Almighty has formed them all on one uniform plan, around +which He has, if I may so express it, lavished an infinity of +modifications separating species from species, yet without placing +between the different species those fixed barriers which we should +require now to enable us to classify them strictly. You who are learning +the pianoforte have perhaps been told the meaning of a _theme_ of +music--the first idea of the composer who follows it throughout the +piece from one end to the other, embroidering on it, as on a bit of +canvas, a thousand variations melting one into another. Such is pretty +nearly, if we may venture the comparison, the way in which we can +picture to ourselves the Almighty moving through the work of animal +creation. Step in afterwards and divide away into regiments and +battalions, if you please. Nature permits it, but she will never, +to accommodate your classifications, separate what in her is really +united. + +There is still a way, however, and that is to do as I did just now in +the case of the crowd. To take, viz., only one _character_ (as we call a +distinguishing mark in natural history), and to throw together all the +individuals which possess it, the blondes, the shorts, the girls, &c. In +this way it may soon be done; but what is the result? You are in one +class, your eldest sister is in another, your mamma in a third, and your +brother in a different division altogether, a long way from you all. +Such a classification is called _artificial_, and you can see at once +that it is worthless. + +The most natural plan is to put together those that are of the same +family; and the classifications made on this principle are called +_natural_ classifications. + +It is a classification of this sort which has been adopted for the +animal kingdom. People have taken all the animals which possess in +common not one character only, but a collection of characters of the +most important kind, _dominant characters_, as they are called; +and of these animals they have formed, to begin with, large primary +groups; subdividing these afterwards according to the secondary +differences, which distinguish different species in the same group +from each other. + +In this manner all the different sorts of animals are included in +different systematic divisions of one vast whole, through which it is +easy to find one's way, because there is a beginning and an end; and +in which animals of the same family are always grouped side by side. +Were I to mention all the divisions of this immense classification at +once, you would find the account a little long, and not very amusing. +We will go through them by degrees therefore, and, to simplify matters, +will, throughout the whole, only consider those particular characters +which are connected with our special study, the nourishment of life, +that is to say: so that you will always find yourself on well-known +ground. + +I must tell you once for all, however, that it is with this as it is +with grammar. Here and there are--and it cannot be avoided--certain +exceptional cases which keep protesting timidly against the +arbitrariness of rules; but no matter; we must be contented with what +we can get, and be grateful into the bargain to those who have given +us this skillful classification, at once so ingenious and useful, in +spite of its inevitable imperfections. What is impossible is expected +of nobody. You could not understand, even if I wished to explain it +to you, the amount of science, labor and genius requisite for making +out that long list, which, tiresome as it may seem to children, is +absolutely beautiful in the eyes of learned men; too beautiful, perhaps, +and I will tell you why when we have finished. Meantime, as the best +reward we can give to those who have done us some great service is to +teach their names to children, I will tell you, before bidding you +good-bye, to whom we owe this classification, the details of which I +do not enter upon to-day. + +In the first place, we owe the method employed in its establishment, +the method of _natural classification, i.e._, to a learned man +of the last century--a learned Frenchman, Bernard de Jussieu--who tried +it upon plants; another large flock by no means very easy to put in +order, as you may convince yourself any day by studying botany. The +man who applied this system to animals was also a learned Frenchman, +the clearness of the French mind adapting them peculiarly for that +sort of work. And he, too, is one of the glories of that nation. His +labors and discoveries gave a perfectly new impulse to the study of +nature. It was George Cuvier, whose statue you may see at Montbéliard, +if you should ever go there. Not that Cuvier carried through this +gigantic work alone, though the credit of it is justly his due, he +having directed and inspired it. He was assisted by many. But among +his assistants there was one, Laurillard, the most modest, yet the +most active of all, whose name I will mention also, because, like the +others, more or less celebrated, he has never had his reward. [Footnote: +In the earlier editions of this work, there was, in this place, a +severe reproach upon Cuvier for not having given proper credit to +Laurillard. This reproach I have since learned was unjust. M. +Valenciennes himself, one of the most illustrious of the collaborators +of the great Cuvier, has written me a letter in which he defends the +reputation of his friend with a warm indignation which does honor to +both of them; and cites passages in which Cuvier has spoken of +Laurillard, and among others, in the third volume of the _Ossements +Fossiles_, p. 32, ed. of 1822.] + +It only remains for me, therefore, to let the lash, which I was laying +upon the shoulders of another, fall now upon my own, and to deplore +the too great facility with which I had credited, without sufficient +proofs, an assertion which I had otherwise good reason to believe to +be exact--coming to me, as it did, from Montbéliard himself, on the +testimony, it is said, of the family of Laurillard. From this avowal, +a little painful, I confess, my young readers may learn the +inconvenience of rashly condemning others! As I said in the concluding +passage, which truth, only too late, now compels me to suppress--"The +truth is sure to come out at last." + + + +LETTER XXX. + +MAMMALIA. (_Mammals_.) + +Do you remember of my talking of the _vertebral column_ when I was +describing that great artery, the _aorta_, to which it forms a rampart +of defence? I should not have named it without explanation, but that you +had only to pass your hand down your back to find out what it was. Now +the _vertebral column_, or backbone, is one of those _dominant +characters_ which always carries along with it a train of other points +of resemblance in the animals where it is found. It has been chosen, +therefore, as the rallying-point of the first great group. I must tell +you beforehand that there are four of these groups, four large +companies, _i.e._, which naturalists have called by various names; as +Groups, Sections, Primary Divisions and even Branches; in this case +comparing them to four great branches of a tree, going off in different +directions from the same trunk. + +And, first of all, we have to begin with the group of the +_Vertebrata_--vertebrata animals--vertebrata being a word which +explains itself. + +Of course we ourselves belong to this group. In fact, we are at the +head of it; but it descends far below us. It goes on to the frog and +the fish, and includes the monkey, the ox, the fowl and the lizard; +for all these creatures possess the vertebral column. The frog does +not appear to be very much like us at first sight; and yet, by virtue +of its vertebra, it has its points of resemblance to us, which are +worth the trouble of considering. Vertebrated animals are all furnished +with a head, containing a brain, which gives its orders to the whole +body; they have all an internal skeleton, that is to say, a system of +bones linked together, forming a solid base by which all the organs +are supported. I was going to add that they have all four limbs; but +here the serpent glides in to call me to order, and to hiss at our +childish craving for fine-drawn divisions, in perfect order, where +there is an exactly proper place for everything. However, each has, +without exception, a heart, with its network of blood-vessels; red +blood, under its two conditions of arterial and venous; and also a +digestive tube, acting, on the whole, pretty much like our own. I do +not insist, mind, upon this last point, viz., that of the digestive +tube; for we shall see, by-and-by, that it is a character beyond the +pale of the primary groups. It is the fundamental character of the +trunk itself, which necessarily exists, therefore, in all the groups; +and, as I told you in my first letter, you will find it everywhere. + +This is--to let you into the secret at once--the theme on which the +Great Composer has based all His infinite varieties of animal life; +and herein lies the uniformity of the animal creation, that startling +uniformity which has given so much offence to many learned men, and +which is so obvious that it will strike you of itself, I feel sure. +But I reserve this subject to the end of my letters, when you will +have heard all, and be able to judge for yourself. + +It would be plunging back into confusion to attempt to examine all the +vertebrated classes at once. After making a division you must go on. +The groups have, therefore, been subdivided into _five classes_, which +we will study in succession, only naming each now: viz. _mammals_, +_birds_, _reptiles_, _fish_, and _batrachians_. Do not alarm yourself at +this last name: it is a Greek word, meaning simply frogs. + +The mammals are our immediate neighbors. Mammalia are the animals which +produce milk. They bring forth their young alive, and give suck to +them as soon as they are born. This was your first nourishment, my +dear child, so you yourself are a little mammal. + +What I said to you in the last letter about the horse, applies pretty +nearly as well to all mammals. We shall not, therefore, have any great +variations to notice here. Nevertheless, as these are the animals which +interest us most nearly, as they are in fact our nearest of kin, so +to speak, and those with whom we have the most to do, we will now pass +in review the different orders of which their class is composed. I +must explain to you that the _classes_ are subdivided into +_orders_, the orders into _families_, the families into +_genera_, the genera into _species_; as in armies divisions +subdivide into regiments, regiments into battalions, &c. It became +necessary, moreover, to make use of special names, in order to make +these subdivisions comprehensible, and the following are those which +have been adopted. + +ORDER 1. _Bimana (two-handed)_. + +Here we may pass on at once, for we have discussed this order enough +already. We are _bimane_ ourselves, since we have the distinction +of possessing two hands. Yes; that is the pretty title which the +professors have been so polite as to give us, instead of leaving us +simply our proper name of man. Yet it would have been very easy to do +this, seeing that we are the only family, the only genus, and the only +species of the order. In railway travelling, people of distinction +have a reserved carriage to themselves: so we decidedly deserve an +order to ourselves; but that is not quite the same as a separate +kingdom. In short, you are a _bimane_; so make the best you can of it. + +ORDER 2. _Quadrumana (four-handed)_. + +These, as their name indicates, have four hands: two at the end of the +arms, and two at the end of the legs; such are the monkeys. There is +nothing to remark; they are all alike. Stay; I am wrong, though: there +is something, insignificant it is true, but still pointing to deviation. +In some the canine teeth are set forward, _i.e._ project, and are +longer than the rest, and some species, as the ape, for instance, have +just under their cheeks convenient little pockets, which open into the +mouth, and in which they can deposit a reserve of nuts to be devoured +at leisure; these are called _pouches_. + +It is a trifle in itself, but we have here a first example of the +eccentricities of nature in the construction of animals. At one time +she adds a detail; at another she suppresses one. Sometimes she is +pleased to enlarge an organ, as in the canine teeth of the monkey; +sometimes she reduces it; or perhaps here she makes its construction +more simple; there again more complicated: but still it is always the +same organ. So the dressmaker shapes the sleeves of a dress, sometimes +open, sometimes closed, flat or puffed, plain or ornamented, +pagoda-shaped or gigot-formed: but still they are all of them sleeves. + +ORDER 3. _Cheiroptera (wing-handed)_. + +I am quite ashamed of offering you such a word as this, my dear child. +It was a Greek fancy of the learned men, who would not condescend to +use the vulgar name Bats. In the Greek, _cheir_ means hand, and +_pteron_ wing. The Cheiroptera are animals with winged hands; in +fact, the fingers which terminate the fore-limbs of the bat lengthen +as they spread out to an extravagant extent; and are connected together +by a membrane springing from the body, with which they beat the air +as with a wing, and which enables them to fly with such ease that +theyare often taken for birds. + +But, so far from really being a bird, this curious little creature has +the same internal organization as ours, and indeed comes so near us, +though without looking as if it did, that a scientific man, and a very +distinguished one too, placed the bat in the first family of the animal +kingdom, with the monkey, and, you will hardly believe it, with man. +It is found that the bat, like man and the monkey, suckles its young +at the breast; and it was this very character which Linnæus, the leader +of artificial classification, thought of selecting as the distinguishing +mark of his first family in the animal kingdom. It is true that in +honor of the human race he had given that first family a much more +sonorous name than our usual one of _man_--viz. _primates_, the first in +rank--that is, the princes. But, alas! we were to be princes on an +equality with bats; and, for my own part, I prefer being a _bimane_, and +alone. I really believe that it was to put this saucy little creature +back into its proper place that, at the time of the great revolution in +favor of natural classification, the conclave of professors assembled at +the Botanical Gardens in Paris inflicted this horrid name of Cheiroptera +on the bat, ejecting it contemptuously from the overthrown dynasty of +the _primates_. + +I have not been sorry to make you acquainted as we went along, with +this little trait in the history of classification; but beyond it there +is really nothing particular to say about the apparatus for the +nourishment of the deposed bat-princes, which is a plain proof how +nearly it must be like our own. By-the-by, there is one trifling remark +to be made with regard to her teeth. The bats we have in our country +(France), for there are many varieties of species in the world, live +on insects, which they catch in their flight by night. These insects +are often enveloped in a very hard outer case, which molars like ours +would have some difficulty in chewing properly; consequently the molars +of our little friend are fringed with conical points, and with these +she grinds down her prey without difficulty. + +In America there is a large bat, the vampire, which lives on the blood +of animals, and nature has armed it accordingly. It has at the +extremityof its muzzle two sharp beak-like incisors, like the lancets of +a surgeon. The vampire bat, which roams by night like other bats, goes +straight at the large animals it sees asleep, delicately opens a vein +in the throat without waking them, and sucks their blood in long +draughts, taking care, by fanning them with its wings, to lull them +into a cool and balmy slumber. It does not, as you see, make a savage +attack on its victim: it merely inflicts a bite like that of the leech, +but the result may be death. This is the best emblem I know of the +sycophant, who undermines your soul while he fans your vanity; and +observe, while we are on the subject, that this species has always had +the art of insinuating itself among princes. + +ORDER 4. _Carnivora (flesh-eaters)_. + +When translated into English, this word needs no explanation. And here +we have the tribe of bears, wolves, foxes, weasels, dogs, cats, tigers, +lions, of all the fighting animals, _i.e._, those which steep +their muzzles in blood, and live by devouring others. These have a +similar apparatus for nutrition to our own; especially the bear, who, +with the monkey, is the animal most nearly resembling man, seeing that +he has feet like ours, with scarcely any tail, while the monkey has +our hands, without specifying any other points of resemblance. Like +ourselves, too, the bear is omnivorous; that is to say, it eats +everything, vegetables and fruit as well as meat; and nature, which +has given it our diet, has furnished it with molars almost exactly +like our own. Its canine teeth alone differ from ours: they are more +prominent even than those of the _quadrumana_; and this is the +case with all the members of the order, in whom we find them sometimes +developed into actual daggers. But those of them which are purely +carnivorous have molars peculiar to themselves. The lion, for example, +who does not share the bear's taste for carrots, and who would die of +hunger surrounded by the honey and grapes of which the bear is so +fond--the lion, who never takes anything but raw meat between his +teeth, has molars furnished with sharp cutting edges, intended to slice +the meat like the chopping knives used by cooks for making a hash. + +The lion offers another peculiarity, which is common to him with all +the _Carnivora_. Place your finger close to the lower end of your +ear, and work your jaw; you will feel something hard moving backward +and forward against your finger. This is where the lower jaw is set +into a bone of the skull, called the _temporal_, if you care to know its +name; in other words, the bone of the temple. The extremity of the jaw +bends, and forms a kind of little knob, called _condyle_, which fits +into a cavity of the temporal bone. With us the cavity is not very deep, +nor the knob very large, so that it can play very freely; and it is this +which allows us that second movement from side to side, of which I spoke +to you formerly, and thanks to which, our little mills reduce a mouthful +of bread into paste. But this freedom of action has also its +inconveniences. You must never attempt to force too large an article +into your mouth at once--an apple, for instance--the efforts you would +then be obliged to make might easily cause the _condyle_ to slip out of +its little cavity, where its hold is but slight, and to get under the +_temporal bone_; and there you would be with your mouth wide open until +the doctor arrived. The lion, whose voracious jaw opens like the door of +an oven, so that the tamers of wild beasts have no scruple in thrusting +in their whole heads, a mouthful a good deal larger than an apple; the +lion, who has no doctors, would often be liable to this accident--an +irremediable one in his case--if nature had not made a special provision +for him. In order to secure greater firmness and strength, the second +movement is in his case sacrificed by embedding the _condyles_ +deeply in their cavities, where they are fastened in such a fashion +that they can only move up and down, like the handles of a pair of +pincers. This is a restraint which enables the jaw to be safely thrown +open as wide as the fiery impulse of its terrible proprietor impels +it. Less freedom, in exchange for more power, is a bargain which any +one would gladly accept who plays the part of a lion! + +I have here a remark to make. We have now passed in review three orders +besides our own, and have only had to point out a change in the +fastenings of the jaws and in the teeth; and you will find that the +same sort of modifications take place in the whole class of mammals. +This is in fact the essentially movable and variable point in their +apparatus for nutrition. The jaw and its weapons vary their character +from one species to another, according to the nature of their food; +but the modifications generally terminate there, _i.e._ on the +threshold, as it were. The interior arrangements of the house remain +otherwise much the same in all. + +Here, however, in the lion, there is an interior change to be described; +but not in the arrangement of the parts, only in their size; the stomach +in this species being even smaller and weaker in proportion than ours, +and the digestive tube more than twice as short. The digestive tube +of an ordinary sized man is about seven times the length of his body, +whilst that of the lion only measures three times the length of the +animal. This is a natural consequence of the kind of nourishment he +takes. Flesh and blood, on which he lives entirely, is concentrated +_albumen_, prepared beforehand in the bodies of his victims; so +that no great preparation is needed here to convert it into lion's +blood. A professor of chemistry, who has a good assistant, does not +need a very large laboratory. This is the case with the lion; and +nature, which makes nothing in vain, has here economised space. Tame +the monarch of the forest into a domestic animal, and change his food, +and I will wager anything you please that, in the course of a few +generations, his digestive tube will lengthen itself. Examine the +inside of the cat, his little cousin, formed originally on the same +pattern as himself, and, without having ascertained the fact myself, +I am sure that, by dint of feeding it daily on sops and milk from +generation to generation, its digestive tube has become more than three +times the length of its body. + +Here you ought to be told at once a very important fact relative to +the organization of the lower animals, one which places them all very +far below the order of _Bimana_, since there is such an order. +In bestowing intelligence and freedom of action on man, the Almighty +has given him the unspeakable privilege of working in His footsteps--if +I may presume to use the expression--of following up His work of +creation as it came from His hand. Now especially that man begins to +see a little more clearly into the laws of life, he has entered more +directly into the possession of this almost divine privilege, which +the Almighty has graciously vouchsafed him. You can even now have an +ox or a sheep made to order in England, giving your dimensions, as if +you were ordering a cabinet; and in a few years, if you have not asked +actual impossibilities, your commission will be executed to within an +inch. This is not said in reference to the _Carnivora_. But in +bidding you good-bye, my dear little mammal, I could not bear to leave +you under the weight of that debasing title: I wanted also to show you +your greatness. + + + +LETTER XXXI. + +MAMMALIA. _(Mammals)--continued_. + +Let us continue to pass in review the different orders of the class +Mammalia. We may meet elsewhere with facts more important to science, +but nowhere with any so personally interesting to ourselves. + +ORDER 5. _Insectivora (insect-eaters)_. + +This order devours insects, as their name tells you plainly enough. +They feed in the same manner as the bats; consequently they have molars +like theirs, as was necessary. It is an unimportant little family, and +we will not waste much time upon it. The chief of the order is the +hedgehog, a native of our country--not very large, about nine inches +long--which lives in the woods, and which when rolled up into a ball, +with all its quills standing out, looks very much like an enormous +horse-chestnut in its shell. Its canines have not much work to do, +consequently they are very small; but, on the other hand, its two front +incisors are prolonged beyond the others, the better to seize its prey, +which creeps upon the ground. Internally there is nothing to remark +upon. + +Next to the hedgehog I will mention as a curiosity the shrew or +sand-mouse, which, in spite of its name, is no mouse at all, but has +the honor, if honor it be, of being the smallest animal known of the +class Mammalia. + +It is about two inches in length altogether; and if you carefully +examine its little body, you will find that it contains all the organs +you possess yourself--oesophagus, stomach, liver, intestines, veins, +arteries, heart, lungs--nothing is wanting: the machinery is absolutely +the same. + +ORDER 6. _Rodentia (rodents)_. + +Were we to translate this word into its meaning, namely, the _Gnawers_, +there would be some comfort in it, for we would at once know what it +means: but no matter. Rodents, or Gnawers, are rats, hares, rabbits, +beavers, marmosets, squirrels, in fact all the creatures which _nibble_. +To _nibble_, if you do not exactly understand the word, means to chew +with the points of the teeth. The rodents have no other way of eating +but by filing, if one may so say, their food with the points of two +incisors with which both the jaws are provided; these incisors are very +long, much longer even than those of the hedgehog. The next time you see +a rabbit at table, ask to see the head; and you will find that it has +four pretty little teeth, very sharp, shaped like a joiner's chisel; +that is to say, with a "bevelled edge," to use the received expression; +in other words, with one edge thinner than the other. + +Here, then, we begin to diverge from the old model. First, there is a +different fastening, or _articulation_, as it is called, of the jaw. Its +_condyles_, which we saw just now in the _Carnivora_ enlarged +transversely and deeply embedded in the _fossae_ or cavity of the +temporal bone, extend here longitudinally; an arrangement which enables +the jaw to move backward and forward at pleasure, like the arm of the +locksmith when using the file. Furthermore, those little teeth, which +are constantly rubbing against each other, would be very soon worn out, +if, like our own, they were made once for all; accordingly their germ, +or _pulp_, to use the proper term, instead of perishing, as with us, +when the tooth has once come, retains its life, and works on throughout +the life of the animal. They sometimes say of a man who has not eaten +for a long while, that his teeth have grown long. This is a joke with +us; but in the case of a _rodent_ would be too serious a matter to be a +joke; for, as their incisors are always growing, like our nails, they +would soon become too long if the animal ceased for any length of time +to wear them down by eating. It is for this reason that rats and mice +have such incessant appetites, and that with them "all is fish that +comes to the net;" old books, rags, and even planks of wood, which they +will gnaw for want of something better. Come what may, they must keep up +at an equal rate the wear and tear of the incisors, and the internal +growth of the pulp beneath, which is always pushing the tooth forward. +This dull continuous work might otherwise have a terrible result, which +you would never suspect. It is very disastrous for a young lady to lose +a front tooth, as it is called, for it sadly spoils a pretty face; but +for a _rodent_ such a loss is much worse; in fact, it is a +death-warrant. The corresponding tooth, having no longer anything to rub +against, ceases to wear out; and as it does not stop growing on this +account, it lengthens indefinitely, until at last it pushes out beyond +the mouth, and places itself like a bar between the two Remaining teeth +and the food of the animal, who, poor beast, being unable to eat, +ceases to live. + +The canines, whose duty it is to pierce the food, have, of course, no +use in a jaw that grinds, nor are they to be found there. Between the +incisors and the molars there is a large vacant space, which you will +easily detect if you examine a rabbit's head. + +Finally, animals which can fall back in time of need on a plank for +their dinner, require a very different-sized cooking apparatus to that +of the _Carnivora_. Thus the rat, the most perfect sample of the +rodent order, possesses a digestive tube of a prodigious length, through +which the scrapings of wood have plenty of time for travelling, while +the minute nutritive particles they contain are being thoroughly +disengaged; and as every part of the animal organization tends towards +keeping our insatiable rodents in the constant state of voracity +required by its inexorable pulps, nature has given it an enormous heart +whose size exceeds even that of its stomach. + +Perhaps you do not catch at once the connection which exists between +the size of the heart and of the appetite; yet it is very simple. Large +barrels are requisite for those who brew a great deal of beer, and +large hearts for those who make a great deal of blood. Now, it is the +blood, as you know, which carries heat; in other words, life, throughout +the body; when it pours in in torrents, the fire goes twice as fast, +and, consequently, the feeding must be kept up. A medical friend of +mine told me that he once had some rats sent to him--a boxful in +fact--for one of those scientific experiments which one would venture +to condemn more earnestly if their results were not sometimes +beneficial. Next morning there were only two or three animals to be +found, and these had eaten up the others. See the consequence of having +too much heart! + +ORDER 7. _Pachydermata (thick-skinned)_. + +In Greek _pachus_ means thick, and _derma_ skin. _Pachyderms_, +therefore, are thick-skinned animals. It is rather a vague denomination, +as you perceive, and does not tell us much about them; but it appears +that it was not very easy to find a better term. For my own part I +should be very much puzzled to find a name really suitable for such an +irregular company as this, in which all the huge beasts of the +earth--the elephant, the rhinoceros, the hippopotamus--are heaped one +upon the other, side by side with the horse, the ass, and the hog; +begging your pardon for an ugly word. + +All these creatures live on vegetables, with the exception of the hog, +to whom nothing comes amiss; or who, in other words, is _omnivorous_, +like the bear, and also another member of the class _Mammalia_, which I +do not name for fear of making you blush at your companionship. This +assures you that, in the order of the _Pachydermata_, the digestive +apparatus is very fully developed. The horse, for instance, has a very +voluminous stomach, which extends much farther back than the point at +which the oesophagus empties itself; and in which, on close examination, +a sort of contraction is observed which appears to divide it in half, +producing the false effect of there being two stomachs. But, after all, +we do not find, even in this case, any essential difference to remark +upon in the internal arrangements; it is always the teeth we must look +at if we want to have something to say. There, indeed, we have only to +choose; nature has indulged herself in all manner of fantastic freaks. + +To begin with the elephant, the grand master of the order, he presents +us with one of the most oddly-furnished jaws in existence. Every one +knows those two enormous tusks which protrude from his mouth, and which +furnish human industry with nearly the whole store of ivory it has +need of. Those two teeth are the largest, beyond comparison, of any +in the animal kingdom; yet they are two merely ornamental teeth, +perfectly useless in the operation of eating, and very ruinous into +the bargain to the proprietor. All those stores of the blood which +furnish the materials for ivory pass into these tusks, and, as often +happens to people who give way to a taste for luxuries, there is nothing +left wherewith to provide the animal with serviceable teeth. Those +tusks of the elephant are nothing but his upper incisors, the only +ones, observe, which curve in coming out of his jaw. In the lower jaw +he has no incisors at all; canine teeth are entirely wanting; and by +way of dental apparatus, this meagerly-furnished mouth possesses on +each side of either jaw one or two molars, enormous in size, but not +of ivory. They are composed of a number of enamelled upright layers +of tooth-substance (_dentine_), soldered together with a bony +cement; and these are our giant's only resource for chewing the grass, +young shoots, and leaves of trees, which are his natural food. +[Footnote: These teeth are nevertheless very efficient grindstones.] +As a consolation, he has the glory of knowing that he possesses the +very finest teeth in the world, the terror of all who approach him; +and I can compare him to nothing so well as to a vain woman, who is +contented to live on potatoes that she may wear fine clothes and excite +the envy of her neighbors. + +The hippopotamus also has incisors in the upper jaw, which curve as +they come out of the mouth; but these never attain anything like the +size of the elephant's tusks, neither do they hinder the development +of the other teeth, of which this animal has a very respectable +collection. The upper incisors bend downward; those in the lower jaw +stand out horizontally, and terminate in sharp points like +plough-shares; and indeed the hippopotamus uses them for tearing up +the ground in order to get at the roots which form its nutriment. These +are, besides, formidable weapons, with which when enraged the animal +can tear even boats in pieces; for, as you are aware, the hippopotamus +is almost amphibious, and browses on water-plants, and lives in the +great rivers of Africa, its native country. Its name alone would have +told you this had you understood Greek; [Footnote: _Ippos_, a horse, and +_potamos_, a river. The Greeks, who had seen the hippopotamus in the +Nile, in Egypt, named it the river-horse; as afterwards the Romans +called the elephant the ox of Lucania, because they first saw it in +Lucania during the war with Pyrrhus.] but I have no complaint to make +this time, for it was the Greeks themselves who gave it. You would find +it very awkward, would you not? if you had to breakfast at the bottom of +the Thames, and could not swallow a morsel without having your nose +filled with water? But the hippopotamus labors under no such +inconvenience. Its nostrils are provided with two little doors, which it +closes at will, and behind this screen the lungs keep quite quiet while +the animal goes backwards and forwards in the water. There is generally +a hippopotamus in every large menagerie. The next time you visit one +look at him. You will see him with a large stomach almost trailing on +the ground: and no wonder; he needs plenty of room in which to stow away +all the canes, reeds, and water-plants from the bottoms of rivers, which +are not very nutritious food. Accordingly the stomach of the river-horse +presents the appearance not only of two compartments, like that of the +true horse, but looks as if it were divided into three or four. + +To conclude my account of this animal, I must add that the ivory of +its teeth is even more beautiful than that of the elephant's tusks, +and that dentists carve it into very magnificent teeth for their +patients. This is not a matter to interest you much at present, but +we never know what may happen. I advise you, however, never to make +use of hippopotamus's teeth; they turn yellow very quickly, and, when +people are driven to buy teeth, the least they can try for, is to get +good-looking ones for their money. + +I should like to say something about the rhinoceros while we are on +the colossal tribes, but it is a very unsatisfactory subject. The +animal has no canines, sometimes no incisors even; sometimes it has +as many as thirty-six teeth, according to the species, as naturalists +aver; and this is all I have to say about this great lump of flesh, +so misshapen outside, yet so regularly formed within. He it is who +especially deserves the title _pachydermata_, his skin being so +hard and thick that bullets glance off its surface. But this has nothing +to do with our present subject, any more than the horn upon his nose, +whose turn for description may come if I ever give you the history of +the skin and all connected with it. + +The hog also has canines, and very strong ones; but it is in the wild +state, when it is called a boar, that these appear in their real form. +There we find them projecting out of the mouth with a curve, as is so +commonly seen among the _pachydermata_, forming those terrible, +sharp, and pointed tusks which have been so often fatal to the hunter. +The wild boar of the forest is supposed to be the original ancestor +of the domestic pig; and if, as is probable, this is really the case, +we have here a remarkable instance of the effect of man's treatment +upon the organisation of the animals he collects around him. The wild +boar lives only on fruits and roots, which, like the hippopotamus, he +tears up with his tusks, those safeguards of his, amid the many perils +of his life in the woods. In the service of man, on the contrary, he +becomes lazy, cowardly, and greedy; unlearns his energy and +combativeness, eats all that is offered to him in the trough, even +meat, when it happens to be thrown in; and, in order to do this +moreeasily, has recalled toward his mouth those formidable war-tusks of +his, so tremendous as weapons, so useless as teeth; has, in fact, +turned his sword into a fork. It is the case of a Tartar degenerated +into a Chinaman. [Footnote: China, about which we have heard a great +deal of late years, has been several times invaded by the warrior +hordes of Tartary. But at each time, unto the second and third +generations, the vanquishers have taken the effeminate manners, the +costume and the usages of the vanquished, and so many conquests have +only resulted in converting millions of Tartars into Chinese.] + +This suggests to me an idea relative to the horse, the last important +member of the _pachydermata_ which remains to be spoken of. It +also has its canines, but very small ones; they disappear, so to speak, +in a large vacancy between the incisors and the molars, where man +inserts the bit, by means of which the animal has been subdued. Small +as these are, however, these canines indicate that the horse might eat +flesh, canine teeth being the distinctive attribute of the carnivorous +mammals. I have read somewhere, but I do not remember where, that an +unusual development of strength could be produced in the horse by +feeding it on flesh; and the old Greek poets write of a king [Footnote: +Diomed, King of Thrace] in the barbarous ages who gave his horses, +men for food. If I knew some rich professor who was inclined to spend +money in the investigation of a curious fact, I would advise him to +set apart a sum for putting horses on a meat diet, from sire to son, +gradually increasing the quantity; and I would boldly warrant that in +the course of successive generations the canines would become so large +as to impede the entrance of the bit into the mouth, and, moreover, +would make it rather a ticklish office for the groom to place it there. +But let us set aside the teeth the horse might possibly have, in order +to examine those it has already. There are six incisors in each jaw; +these are long and rather projecting teeth, by examining which, the +age of the horse can be detected from certain marks which appear in +them from year to year. The molars are flat, square, furrowed with +bars of enamel, marking out more or less distinct crescents; perfectly +constructed, in short, for chewing hay and oats. Nevertheless, I should +never be surprised to see the enamel crescents become sharp-cutting +in our rich professor's stable; so skillful is the unseen Architect +who created animals, in altering the house when the tenant changes his +habits. + +ORDER 8. _Ruminantia (ruminants)._ + +I shall retain through life a pleasant recollection of the +_ruminants_. Through them I obtained the first prize for natural +history which was ever given in France to the pupils of the learned +university. It is thirty years ago since this happened, and I own, +without any false modesty, that even now the word _ruminant_ rings +very agreeably in my ear. It reminds me of one of the proudest moments +of my life, of the honor done to me by the illustrious Geoffroy St. +Hilaire, when he called me, a little college urchin, up to him, that +he might have a nearer view, as he said, of the baby-professor who had +spoken so well on ruminants. Yes, it is more than thirty years ago, for +alas! it was in 1831. There needed no less an event, as I have told +you before, than the revolution of 1830 in France to induce the big-wigs +of education to sacrifice two hours per week in one class to the study +of natural history. Yes, my dear child, it is only that short time ago +since natural history became one of the subjects of study in French +colleges; and the gray-haired men of the present day finished their +education, as it is called, without having learnt a single word of +what I am now taking the trouble to teach you, a mere child. You see +you have come into the world just at the right time, and will be able +to instruct others in your turn. But before giving lessons to other +people you must first finish learning your own. Forgive me this +involuntary reference to a happy time when I was not much more rational +than you are. And now, let us return to our ruminants--those dear, +good beasts, the nourishing fathers of the human race. + + + +LETTER XXXII. + +MAMMALIA--_continued_. + +ORDER 8. _Ruminants--continued_. + +Every created thing has an appointed part to perform; but there are +some mysterious parts of which we cannot understand the drift. That +of the ruminants, however, is so clearly marked out, that we detect +it at a glance. + +To qualify myself for supplying your young mind with the food I am +going to offer it to-day, I have been obliged, my dear child, to browse +in a good many books of which you could have understood but little +yourself; and I have been forced to ruminate a long time upon what I +have read, and to digest it slowly in my head, which I may say, without +vanity, is of larger capacity than yours; no great wonder at my age. +Now, if I have succeeded in my undertaking, you will benefit by all +the work which has been going on in my mind for the purpose of feeding +yours without over-fatigue to it; and I shall almost have the right +to say that its nourishment has been derived from me. My lamp could +tell you what it has sometimes cost me to supply a single page which +might instruct, without repelling you. + +Now, this is precisely what the _ruminant_ does. The part he has +to perform is to collect in the meadows a sort of food, which would +disgust less well-organized stomachs than his own, to work it well up +within him, and to give it back in a more palatable and less +indigestible form. The little flesh-eaters (_carnivora_) come +afterwards to the feast, and the feast is himself! + +The whole history, then, of the ruminant is to be read in his stomach. +His real office is to digest, and in fact he devotes the best hours +of his days to the perfecting of that beneficent labor, on which the +life of so many weak stomachs depends. Have you ever amused yourself +by watching a large ox lying down in a meadow? Long after he has +finished grazing, his jaw continues to work, turning round and round +like the grindstone of a painter when he is rubbing down his colors. +Look, and you will see that he will remain there for hours together, +motionless and contemplative, absorbed in this incomprehensible +mastication, rolling about in his throat from time to time some +invisible food. Do not laugh at him, however. As you sec him there he +is performing his part in life, he is _ruminating_. + +To ruminate is to chew over again what has been already swallowed; +and, however droll this may seem to you, it is the business which all +ruminants are born to. You remember the monkey's pouch, which serves +him as a larder, whence he takes out his provisions as he wants to +eat. The ruminant has an immense pouch of the same kind, into which, +while he is grazing, he hastily conveys large masses of half-bitten +grass. You probably think he is eating when he has his head down in +the grass; but you are mistaken. This is only a preparatory work; he +is hastily heaping up in his larder the food he intends to eat +by-and-by; only his larder, instead of being, like the monkey's, in +his cheeks, where, indeed, there would not have been half room enough +for those great bundles he tucks in, is in the middle of his body, +close to the extremity of the oesophagus, whose lower wall, being slit +at that part, becomes an imperfectly secure tube, ready to burst open +under pressure, and allow the food to escape between the edges of the +slit; these, otherwise, remaining naturally closed. As soon as the +large bundles of grass come to this part, they press against the walls +of the tube, which they by this means separate, and fall into the +provision-pouch, which bears the name of paunch, or grass-pocket, in +fact. As soon as the paunch is well filled, and the animal sure of his +dinner, he lies down in some quiet corner, where he proceeds gravely +with the important act, which is the real object of his existence. A +little below the entrance to the paunch, and communicating both with +it and the canal of the oesophagus, is a second receptacle, which old +French naturalists, not being much acquainted with Greek, named the +_cap_, on account of its fancied resemblance to the caps worn on +the head, and which we call 'king's hood' or 'honey-comb bag.' This +second stomach now contracts (at least so it is supposed), and thus +retains, as if with a closed fist, a portion of the grass accumulated +in the paunch: of this it forms a pellet, which it sends back into the +oesophagus, and the oesophagus, by continued contractions from below +upwards, returns it to the mouth, where at last the grassy lump is +chewed in good earnest, and to some purpose. There is no necessity for +hurry; the ruminant has no other business on the face of the earth but +this, and thus hour after hour passes away, the food pellets rising +one after another to the onslaught of the teeth. Nor do they go back +again until they have been reduced by long mastication into an almost +liquid paste, which glides through the oesophagus without forcing open +the slit, and falls straight into a third pouch, called by old Frenchmen +the _leaf_, on account of certain large folds, some what like the leaves +of a book, which line the interior; and known to us as the _manyplies_. +From this stomach, No. 3, this grass-pap passes into a fourth and last +bag, which is the real stomach, and where the final work of digestion is +accomplished. This fourth pouch also has a pretty little name of the +old-fashioned sort, like the three others; it is called the _reed_ or +_rennet-bag_, from the property it possesses, in the calf, of turning +milk into curds: and of his four stomachs this is the only one which the +ruminant makes use of at first. As long as the young animal is nursed by +its mother, the other compartments remain inactive and small in size; +they neither grow nor exercise their functions until it begins to eat +grass. Indeed, they would probably entirely disappear, if any one would +go to the expense of keeping the animal on milk all its life. If it +ceased to have anything to ruminate, nature would certainly lose no time +in relieving it of its useless workshop of rumination. + +As it is right to give every one his due, I will mention that we owe +our accurate knowledge of this simple and ingenious mechanism of +_rumination_ to the labors of Flourens, a scientific Frenchman, +who is still alive, and who has made a great many interesting inquiries +into the subject we are now considering, _i. e._, the life of +animals. He is a very clever man into the bargain--so perfect a master +of his own language, that the French Academy has felt itself justified +in opening its doors to him--an unheard-of honor for a member of the +Academy of Sciences. And yet, in spite of all this, I heartily +congratulate you that the discovery of the _paunch_, the _cap_, the +_leaf_, and the _rennet-bag_, was not delayed for his arrival. He is +just the man who might have been tempted, in his capacity of profound +scholar, to have hunted up for them in the _Jardin des racines grecques_ +[Footnote: Your brother can tell you about the _Jardin des racines +grecques_. It is a charming little book, of which every generation of +collegians has learnt, by heart, the commencement; but I have never +known one, even among the most intrepid, who had ever been to the end of +it.], four magnificent names, which would only have bewildered you. + +Beyond the rennet-bag there is no change of conformation to note, +except that the intestinal tube is naturally much longer than ours, +on account of the difference of food: as a general rule, it is ten or +twelve times the length of the body. The sheep, who is able to pick +up a living in the poorest pastures, is indebted for this inestimable +power, which makes him the special blessing of dry and barren countries, +to a still further peculiarity of organization; with him the intestinal +tube is twenty-eight times the length of the body. + +We have seen among the _Carnivora_, whose jaws have so much work +to do, that the condyles of the jawbone are sunk deeply into the fossa +of the temporal bone. The ruminant, whose peaceful mouth is formed for +contending only with grass, is organized quite differently. + +Here the condyle is flattened, and the fossa of the temporal bone very +shallow, presenting to the condyle an almost flat surface, so that the +jawbone is enabled to revolve with ease for the better mastication of +the pellets of grass. This conformation is also to be seen in the +_pachydermata_ who feed upon vegetables. In the horse, especially, +whose food is almost the same as that of the ox, the _articulation_ +(as this joining of the condyle to the temporal bone is called) of the +jaw, is also nearly identical; and it is the same with the teeth, with +very trifling variations, those of all ruminants are constructed on +the same plan as in the horse. The canines only require a separate +notice. + +But first I must tell you that, by some special privilege, the reason +for which I do not undertake to explain, the order of ruminants is the +only one containing animals with horns on their foreheads. Stags, +goats, reindeer, chamois, gazelles, roebucks, oxen, buffaloes, all the +beasts with horned foreheads, belong to the ruminants. Indeed, this +fact would form a very convenient mark of distinction between them and +other animals, were there not exceptions to it. Some ruminants have +no horns; and then, as if in compensation for the deficiency, we find +them provided with canines in the upper jaw, in addition to those +below. + +The ruminant which has the most beautiful canines is the musk-deer, +a pretty little animal inhabiting the highlands of Central Asia, like +the chamois of the Alps. But now that you know who he is, you will +probably often be tempted to wish he had never existed; for it is from +a small pouch below his belly that people obtain that odious musk of +which Oriental beauties are so fond, and which even certain +strong-nerved ladies of our own country are guilty of using in public, +to the great detriment of general health. But enough of this; our +business is with the canines of the musk-deer. They project with a +descending curve from the upper jaw, and would give the animal the +very false appearance of a small wild boar, but for the great delicacy +of its legs, which are more slender than even those of our roebuck, +to whom, with the exception of the horns, it bears a close resemblance, +as its name implies. + +After the musk-deer comes the large family of camels and llamas, which +represent--the former in Asia and Africa, the latter in America--the +irregular groups of ruminants which have canines instead of horns, and +which seem to be placed as intermediates between true ruminants and +the pachydermata. They form the connecting link between the horse and +the ox, and men prefer employing them as beasts of burden to using +them as butcher's meat; though one could eat them in their own country +with less disgust than Europeans feel in making a meal of horseflesh; +so that they might be a very acceptable resource in many cases. The +real fact is, that ruminants with horns and without upper canines have +more delicate flesh than the others, and seem more especially destined +to be eaten. Yet if one had only to look at the stomach, which is, +after all, the distinctive characteristic of the order, camels and +llamas would stand in the first rank as ruminants. Besides the usual +character of four stomachs, their paunch and honeycomb-bag are furnished +with large cells which act as reservoirs, and fill with water whenever +the animal has the chance of drinking freely, and from whence in time +of drought he draws it up into his mouth and swallows it. This is what +makes the camel so valuable to the wandering tribes in the great deserts +of Africa and Asia. He is the only animal who can pass several days +under the burning sun of Sahara without drinking--or rather without +appearing to do so--for he carries his provision of water concealed +from all eyes in the recesses of his body. I dare say you have often +heard stories of Arabs dying of thirst who have opened the stomachs +of their camels in search of a last draught of water. It must be a +terrible thirst to drive a man to such an extremity; for, as you may +imagine, one could not expect the water there to be either fresh or +clear, to say nothing of the great risk there would generally be of +finding the reservoir empty. Such an extreme is never resorted to till +water has failed for a long time, and all the goatskin bottles have +been emptied; and in such a ease it is but too likely that the camel +has followed his master's example, and emptied his water-skins for his +own use. But this is only half the internal fittings of the "ship of +the desert," as the Arabs call him. In the desert it is often as +difficult to find food as water; and nature has equally provided for +this. The hump you see rising upon the camel's back in your +picture-books is his safeguard against starvation. It is a huge mass +of fat. I need say no more. You will remember Mr. Liebeg's pig, which +lived 160 days upon its own bacon. Without going quite such lengths +as that, the camel can keep up his fire for a long time upon the fuel +which the blood obtains from this blessed hump. Since we are talking +of this animal, and he takes a remarkable place in a history of +nutrition, I ought to tell you that camels are classed into two families +by their hump: there is the camel, properly so called, which has two +humps, and the dromedary, which has but one. This latter did not require +such a supply of provisions as the other, for he is very much swifter +of foot, and consequently his journeys are more speedily performed. + +I have nothing particular to say to you about the other ruminants, in +the matter of their organs of nutrition; but I will not quit the subject +without reminding you of one thing which concerns nutrition, not theirs, +however, but ours. It was by the taming of the domestic ruminants--that +unfailing dinner-material which now follows everywhere at the heels +of his master--that human civilisation began. Before that event, man, +driven to depend for his living upon the hazards of the chase, spent +his whole time in seeking for food, and had none to spare for the +pursuit of any other branch of industry. + +Far as we may ascend in the history of ages we shall find shepherd +races. Beyond them there is no history at all, nor could there be. The +first leisure hours of man, and, consequently, his first efforts in +art and literature, date from the period when the ruminant animals, +those special fabricators of nutritive aliments, were gathered around +mankind, and worked out their destiny under the shadow of his tent, +by his direction, and for his benefit. But all this is so distant from +us now, that it is scarcely worth the trouble of thinking about. The +human race is somewhat like those old people who have lost all +recollection of their childhood; and young people are not required to +know what their elders have forgotten. It is well, however, that they +should not be quite ignorant on the subject. When you hear that the +Society for the Prevention of Cruelty to Animals has taken up the cause +of some barbarously-used ox or sheep, do not turn it into ridicule. +Those humble species have supported ours from the first; and you should +recollect, now and then, that human society made its first step forward +when it began to keep flocks and herds. + + + +LETTER XXXIII. + +MAMMALIA--_continued_. + +We come now to animals less familiar to you, and none of which inhabit +Europe. We shall therefore pass more quickly over them. + +ORDER 9. _Marsupialia (pouched)_. + +_Marsupium_ is Latin for purse, pouch, or pocket. The marsupials +are distinguished from other animals by a pouch which the mother has +under her belly, and in which the little ones take refuge at the +slightest alarm. You would be very much interested with their whole +story; but it has nothing to do with our present subject, which we +should soon lose sight of if we once began to wander away. This order, +so easily distinguished otherwise by that singular pouch, unfortunately +for us, offers nothing new for observation. It includes several species, +differing entirely from one another on the subject of nutrition, and +closely resembling some already described. Some are both carnivorous +and insectivorous, and are therefore armed with powerful canines, and +with molars like those of the hedgehog. Others are herbivorous, like +hares, and have almost the jaws of a rodent. Among the former we have +the opossum, celebrated by Florian in one of his prettiest fables. The +opossum inhabits South America. Charming little marsupials are to be +found in the Molucca Isles, whence come the nutmeg and the clove; these +are very like our squirrels, and live as they do, in trees, hunting +after fruit and insects. But the greatest number of marsupials belong +to Australia, the real native land of the order. They form by far the +larger portion of the mammalia with which that country is enriched; +the most celebrated amongst them being the kangaroo; an animal which +is now becoming common in European menageries, and which, excepting +in the matter of its pouch, is nothing but a magnified rabbit, as tall +as a man, and with a tail almost as long as itself. As a rabbit, you +know what its eating apparatus must be; and some day, no doubt, the +French Acclimatisation Society will enable us to judge of its flavor. +It is a kind of meat very likely to be seen on our dinner-tables +by-and-by; and, as you have plenty of time before you, probably you +may eat of it before you die. + +ORDER 10. _Edentata (toothless)_. + +These come more directly within our limits. They are classed according +to their teeth; yet if their name were to be trusted, they ought to +have no teeth at all. Whereas, alas! almost all of them have some, and +I am heartily ashamed of their scientific designation; but how can we +help it? The only really _Edentata, i. e_. toothless animals, amongst +them are the ant-eaters, who, considering the nature of their food, are +not much in want of teeth. They feed among the ant-hills, whence they +get their name; and as they are a tolerable size (from two to three feet +in length), it would really have been quite a hardship upon them to have +been forced to crunch the ants one by one at every meal. To get on +rapidly they catch them with their tongue; but what a tongue! Imagine a +kind of long earthworm, lodged in a snout which is elongated like a +bird's beak, and has a very small opening at the extremity. The ant +eater inserts this long, string-like tongue into the crowded ranks of +its victims, and, as its surface is glutinous, they stick to it by +hundreds at a time, and are swallowed at one gulp without a chance of +escape. This tongue, perfectly unique in its character, stretches out in +its murderous exertions to nearly three times the length of the animal's +long head. What a distance there seems between such a tongue as this and +your own little doorkeeper! But no wonder: we have now reached the +confines of the kingdom of _Mammalia,_ and the face of nature is +beginning to change. + +The Armadillo, for instance, which comes next to the ant-eater, looks +far more like the tortoise or lizard than its noble mammalian brethren. +It is covered with scales; and, to look at it, you would say it was +a reptile, in spite of its higher internal organization. As for teeth, +it has certainly enough of them to give the lie to its name of +_edentata;_ but they are not very serviceable ones. They are called +molars, however, because they are situated in that part of the mouth +which is always assigned to molars; but they are miserable grindstones, +very unlike any of which we have hitherto treated. They are all of them +flattened cylinders, with no enamel bars to strengthen them; are small +and poor, and are placed at rather wide intervals from one another. The +poor armadillo munches with these, as best he can, slugs, tender roots, +and other prey of the same sort, with which he is obliged to content +himself, and which do not require very formidable tools. + +The most questionable member of this class is the Unau, or Two-toed +Sloth. It only wants incisors to be as toothless as ourselves! and the +first time I saw it I took it for a little bear. It is true I was then +younger than you are now; for the bear, who is one of our nearest +neighbors, ought not to have been confounded with the unhappy being +before us, one of the drudges of the animal creation; though M. de +Blainville (who had not my excuse) proposed placing it still nearer +to us, namely, amongst the _Quadrumana_. Observe that instead of hands +it has at the end of its fore-limbs only two enormously curved claws, +which have somewhat the appearance of a gigantic fork accidentally +twisted. Accordingly its illustrious sponsor offered it to the world as +an _irregular quadrumane_. I believe so, indeed! This _quadrumane_ +without hands--this _edentate_ whose molars are preceded by magnificent +canines--this enigma of nature, created for the confusion and despair of +all classification--does, I must in all humility confess, completely +upset the rule I laid down so stringently when speaking of the horse, as +to the objects for which canine teeth were framed. The canine teeth of +the sloth are more developed than its molars, and yet I cannot tell you +what they are there for at all. It feeds upon the leaves of trees; and +old travellers in South America, where it inhabits, have told us that, +when it has once hoisted itself up a tree, it will strip it to its last +leaf, and afterwards drop to the ground to avoid the trouble of crawling +down. This was what first obtained for it the villanous name of sloth, a +title which is certainly justified by its gait when on the ground; for +it is so ill-made that it cannot stand upright on its legs, but moves +clumsily forward by dragging itself on its elbows. It seems, however, +that when once in a tree it is a different creature altogether, and +can scramble lightly from branch to branch. Moreover, if its claws +cannot reasonably be reckoned as hands, they are at all events excellent +hooks; and when it is springing about thus in the forest, suspended +to the branches by its long arms, one might be tempted, while watching +it from below, to decide in favor of M. de Blainville's opinion. I saw +it originally myself in a cage. + +As to the sloth's relationship to the armadillo, this rests upon a +detail which bears directly upon our subject. The molars in both animals +are cylindrical and smooth, this is a trifle, but what would you have? +The animal had to be classed somehow; since naturalists have not had +the wit to make detached companies, as they do in regiments of soldiers. +ORDER 11. _Amphibia (two-lived)_. + +We are going farther and farther away. Here are animals who are nearly +half fishes (_amphis_, _double_, and _bios_,_life_). The _Amphibia_ have +two lives: one in the water, which is their true life, and where they +are in their element; the other upon land, where they can only crawl; +for their paws, which are but half developed, are destined to perform +the office of fins, and the hinder ones are extended flatly behind them, +and act like a fish's tail. They are divided into two families, the seal +and the walrus. The first feed on fish, and have the same internal +organization as the _Carnivora_, as well as the same dental +conformation. Some species have even exactly thirty-two teeth, as we +have. The jaw of the walrus is the least regular, and the incisors are +generally wanting, especially in the full-grown animal; for it appears +they lose them very young, as you lost your milk teeth, only, unluckily +for the walrus, his never grow again. On the other hand, he has two +canines in his upper jaw, which, next to the elephant's tusks, are the +largest we have yet met with. They are sometimes as much as two feet +long, and incline downwards with a curve, like the two bars of a +pick-axe. They would play the walrus the same trick that the incisors of +rodents are apt to do when they have not work enough to wear them down; +that is, stop up the entrance of its mouth, were it not that the lower +jaw is contracted in front, in order to fit into the space between the +two canines, which thus form a sort of passage in which it manoeuvres +freely. As you may suppose, the walrus cannot insert prey of any great +size into this contracted passage; but that is no matter, as he lives +partly on seaweeds, and partly--indeed principally--on shell-fish; his +molars being specially adapted for breaking shells. They are short +massive cylinders--the upper ones fitting into the lower as a pestle +into a mortar. + +After the walrus comes a strange animal which has been ranked among +Cetaceans (we shall see why presently), but which it would be better +not to separate from the Amphibians, since an Amphibian order has been +made, for it crawls from time to time upon land: this is the Manatee, +or Sea-cow. It comes still nearer a fish than the others. Its forelimbs +are absolute fins, with mere vestiges of nails at their edges; it has +no hind ones, and its body, which is quite cylindrical, ends in a fin +tail in the shape of a shovel. The sea-cow feeds on plants and herbage, +and lives at the mouths of great rivers, going up them occasionally +to great distances, their banks serving it for pasture ground. In some +respects it is half brother to the hippopotamus and the great grass +eating _Pachydermata_, to whom it comes so near in internal +organization, and above all in the structure of its molars, that M. +de Blainville seriously proposed ranking it among the elephants, though +as an _irregular elephant_, as you may suppose. But then Cuvier +had even placed the seal among the _Carnivora_, by the side of +the cat, whose whiskers it possessed, and of the dog, whom it resembled +in the formation of its head. A naturalist's office is sometimes very +perplexing, I assure you; and as we are touching on this subject, I +cannot resist telling you that the sea-cow laid claim to, on so many +sides, had by right a free admission to the celebrated order of +_Primates_, although it looks exactly like a large barrel elongated +at the two ends. It suckles its young at the breast like man and the +monkey; and if Linnæus flinched from this rather too absurd parentage, +old navigators were less scrupulous. Observing this creature in the +distance, sporting on the waves, the upper part of its body quite out +of the sea, the sailors, whose eye is not of the most refined, and who +have no objections generally to the marvellous, imagined they saw a +new species of human beings; and hence arose those stories of mermaids +and sirens which have been told from the days of Homer downwards, and +the traditions of which have not yet quite died out in seaport towns. +To have been passed from man to the whale, touching the elephant on +the road, is a long way to travel, especially when, after all, one is +only a huge barrel of amphibious fat; and you may judge from this that +it is not always an easy thing to classify animals. + +ORDER 12. _Cetacea (whale-kind)_. + +Cetaceans are whales; and if I had been consulted on the matter, I +should have joined this order and the last together, under whatever +name was thought most appropriate. The passage from the seal to the +whale through the walrus and the sea-cow is an easy and natural one, +the two latter being obviously the connecting links; and in spite of +certain diversities of food, they form in reality one family-party, +as do the marsupials. + +But it is too late in the day to talk of this, my dear child, and you +and I cannot pretend to alter what is taught in the schools. + +But you are astonished, are you not? to hear that the whale is not a +fish: and no wonder. It is with it, however, as with the armadillo; +it is a fish with a higher organisation inside. The interior of this +enormous mass is a faithful reproduction, as a whole, of that of the +shrew-mouse; and when we come to talk of fishes you will have some +faint idea of the prodigious distance which this places between the +whale and his countrymen of the ocean. + +As far as we are concerned, the chief difference is in their way of +breathing. The cetaceans breathe like ourselves, and are obliged to +come to the surface of the water to take air; while fishes have a +special apparatus, which I will explain to you presently, which enables +them to breathe in the water. This is a disadvantage to the cetacean +in his fish life; nevertheless, of all the mammals (as may easily be +imagined) he is the one who can remain longest under the water. With +us, for instance, the best divers one ever heard of, those who go to +the bottom of the sea after the pearl-oyster, can scarcely stay below +longer than two minutes; and even during that short time the veins of +the head become so overcharged with the blood, which cannot return to +the lungs owing to its forced inactivity, that when the diver comes +back to the surface it is by no means unusual to see him streaming +with blood from both nose and ears. The cetaceans remain under water +for half an hour at a time without seeming to suffer in the least; and +Breschet, a clever French naturalist, has given a very satisfactory +explanation of this wonderful faculty. In dissecting a cetacean, he +discovered all along the vertebral column an extensive network of large +veins, which are not found in other mammals, and which seemed designed +to serve as a refuge place for the blood during the time the animal +remains submerged. According to him, this network would act as a +reservoir, to which any overplus in the head or important organs would +flow through vessels communicating therewith, and which might swell +out as it pleased, without any risk to the inert bed of fat against +which it lies. From thence the blood rushes to the lungs, as soon as +the animal's return to the air enables them to play as usual. It must +be admitted, at the same time, that all this involves the necessity +of a much less active life than that of land mammals, that is to say, +a consumption of oxygen much smaller in proportion than theirs; for +were you to be furnished down your back with the finest network +reservoir in the world for venous blood, it would still not enable you +to remain half an hour without breathing. + +There is nothing remarkable in the digestive apparatus of the cetaceans +except about the mouth, which is, as you know, the essentially variable +point among animals. To begin with, the cetacean tongue has the most +original appearance possible. Indeed, it is not a tongue, but a large +carpet, spread over the floor of the animal's mouth, and bears not the +faintest trace of resemblance to that nimble delicate porter, who does +you such good service. Imagine a thick soft lump absolutely crammed +with fat, and completely immovable, because it is glued down along its +whole length to the bottom of the mouth, and you will have a good idea +of this strange tongue, which in the whale, the largest of the +cetaceans, attains to the length of twenty-five feet and the width of +twelve, and of itself alone furnishes the whale-fishers with from five +to six tons of oil. This is a great deal farther from us than even the +long string which serves as a tongue to the ant-eater; and you feel +at once that we are getting among strangers. + +With respect to teeth, I have now a melancholy piece of news to tell +you. We have done with them; we have seen the last of incisors, canines, +and molars, henceforth you will hear no more about those valuable +instruments. The teeth of the cetaceans, with whom this painful +falling-off begins, are no more teeth than his tongue is a tongue. +They are like so many nails set in a row in the jaw, and can only be +of use in retaining prey, not in grinding it; so that of the many +processes your bit of bread has to go through before it becomes a part +of yourself, there is one which is dispensed with here altogether, +namely, mastication. Cetaceans swallow their food without chewing it. + +Besides, they have not got a whole set even of these unmasticating +teeth. Dolphins and porpoises, those faithful companions of the sailor, +around whose vessel they come playing and tumbling in the seas of all +countries, are the only ones who have them in both jaws. And these are +the small fry of the order; they do not usually exceed six or ten feet +in length. + +The Cachalot, or Spermaceti Whale, an enormous cetacean, which rivals +the true whale in size, and whose head alone forms nearly the half of +its body, has teeth in the lower jaw only. This lower jaw, whose two +sides are joined together for half their length (a new deviation, very +unlike anything we have found before), is so little proportioned to +the gigantic head which contains it, that it is almost lost to sight, +and seems like a small plank slipped under a great square block. + +Such as it is, however, it possesses many very respectable teeth, of +which some weigh as much as two pounds; and with these the cachalot, +whose ferocity is tremendous, tears in pieces everything that comes +near it, sometimes even the boats of the fishermen who risk their lives +in the dangerous pursuit of capturing them. By a singular arrangement, +of which this is the only known instance, there is, opposite each of +the cachalot's teeth, a corresponding cavity in the upper jaw, into +which they fit closely, turning the monster's muzzle into the most +formidable pair of pincers to be found in the animal kingdom. Another +curiosity in the order is the tooth of the Narwhal, a modest cetacean, +who is not much more than twenty feet long! + +I speak of _the tooth_, because the creature has commonly but +one; a cylindrical-pointed tooth, spirally furrowed, whose length +varies from six to ten feet, and which comes straight out from the +extreme front of the upper jaw, like a soldier's pike. There are two +sockets at this extremity of the jaw, each furnished with a tooth-germ; +but as a general rule the germ on the left side is the only one which +develops, the other lying asleep in its socket, where it is choked up +and never appears. Behind this long pike, which, like the tusk of the +elephant, attracts to itself all the ivory in the body, lies a +completely unfurnished mouth; so that the owner of this magnificent +weapon, invaluable as a war-tool, but quite inapplicable to the purpose +of supporting life, is obliged to feed on small fishes and +_mollusks_. We have not yet spoken about these latter, but if you +have ever seen slugs and snails you will know what a _mollusk_ is. + +The same wretched food falls to the lot of the whale also, that giant +of the ocean, whose open mouth forms an aperture twenty feet in extent. +Geoffroy St. Hilaire, in his indefatigable endeavors to trace out +points of resemblance connecting together animals the most unlike in +outward appearance, discovered, along the lower jaw of a young whale, +certain traces of teeth, indicating a last effort on the part of nature +to carry out her usual plan in furnishing the jaws of mammals; but, +like the right-hand tooth of the narwhal, these vain attempts soon +disappear, overgrown and lost in the tissue of the bone, so that the +whale offers us a true type of an _edentate_, classable with the +ant-eater, if one dared, and some people have dared, which by this +time will not surprise you. A classifying professor is utterly +merciless, whether he gets hold of the poor beasts by the mouth or by +the paw: they may protest with all the rest of their body against the +peg on which they are hung; so much the worse for them! If one were +to listen to what they have all got to say, it would be impossible to +classify even one. + +To return to the whale. As a compensation for the teeth which she found +herself unable to give him, nature has manufactured on the two sides +of his upper jaw the most extraordinary apparatus without exception +to be found in the mammal mouth. You know what is called the +_whalebone_ used in stay-making, &c. The name is quite correct; +for those little flexible black strips, which support the figure so +nicely, began life in wandering over the polar or Australasian seas, +fastened to the palate of some monstrous whale. + +On the two sides of the upper jaw the membrane which covers the palate +sends out rows of broad, thin, horny plates, which are from eight to +ten feet long (they have sometimes been seen twenty-five feet) in the +centre of each side, but which decrease gradually towards the +extremities. These are plates of whalebone (sometimes called whale's +whiskers), and the industry of man has turned them to a thousand +different uses; and you will open your eyes in astonishment when I +tell you that 800 or 900 of them have been sometimes counted on each +side of one mouth. Think of the number of stays that could be furnished +from the whalebone plates of one whale! It is true, they were not +exactly designed for this purpose originally. At the tips and on the +edges of these plates, the elastic fibres of which they are composed +unravel and peel off, and hang down from the lip like tufts of +horsehair. The Arctic seas, which the whale inhabits, are, like other +seas, full of innumerable troops of various little sea-animals, and +it is these which are destined to the honor of nourishing this gigantic +mass of flesh. When the colossus wishes to take a meal, he stretches +his mouth to its utmost width, and the salt water rushing in as into +a gulf, carries with it the imprudent little fry, who disappear then +and there for ever, being retained by the fringe-like sieve of the +whalebone. But as, in this way of eating, the stomach of the whale, +however large, would be terribly overgorged with water, he is furnished +with another apparatus for preventing the inconvenience. All the +superfluous water is rejected by the _pharynx_, and springs up +in spouts of fifteen or twenty feet high, through the nostrils, +_i.e._ the nasal openings, sometimes called "vents," sometimes +"blow-holes," which are pierced exactly at the top of the head. This +is a peculiarity common to all cetaceans, who have thence received the +name of "blowers," alluding to the powerful blast which is necessary +to send those majestic columns of water into the air; but it takes a +much milder form with the lesser cetaceans, such as dolphins and +porpoises. There is but a slight jet with them: the water escapes +comparatively quite quietly from the nostril-vents, trickling away +down the animal's sides. + +I hope you consider that I have told you something new this time, my +dear child, and that our machine is beginning to change its appearance +very materially. I told you before that we had reached the outskirts +of the mammal kingdom. When we got to the armadillo we were within a +stone's throw of the reptiles, and here, one step more would take us +to the fishes. But we must first consider the birds, who are a very +superior set of animals to either of the latter; and we have accordingly +an order of mammals (Monotremes) which, as you will now find, opens +the road on that side also. + +There are but two sorts, and both of them are natives of Australia, +which is, as you may have heard, the land of the wonderful in natural +history, and their existence was unknown to the learned men of Europe +till within the last sixty years. The most extraordinary of the two +is the _Ornithorhynchus_, or, to translate the hard Greek word +into English, the _Duck-bill_. Its mouth is a true duck's bill, +a downright horny beak, and its short paws sprawling sideways with a +membrane joining the toes together below, and coming a good deal beyond +them in front, seem intermediate between the flippers of the seal and +the webbed feet of a water-bird. The first naturalist who had anything +to do with the ornithorhynchus, Blumenbach the German, who gave it its +pretty name, did not think it was able to suckle its young, so much +did it differ from mammals in some respects, though looking so like +them on the whole. And presently a report arose in the learned world +that the new animal which had been classed at all risks among mammals +(it having the close fur and almost the body of the otter), a report +arose, I say, that this ornithorhynchus of Blumenbach laid eggs like +a real duck. The uproar in the Academies was tremendous. As early as +1829, indeed, a learned Englishman, Sir Everard Home had sent over to +France an authenticated drawing, as he said, of an ornithorhynchian +egg, to the delight of the hunters after analogies among animal races; +while Cuvier looked sadly askance at the intruder, whose arrival threw +his animal outlines into confusion, there being no place in them for +such a beast. Happily for the poor animal, he has ended by almost +settling the matter for himself. The ornithorhynchian egg has never +turned up. But in the animal's nest have been found baby +ornithorhynchuses, newly born, under two inches long (the full-grown +animal being more than a foot and a half), and not a trace of eggshells +near. Further investigations showed that the mother ornithorhynchus +nursed her young with milk, for curdled milk was found in their +stomachs; so the Australian phenomenon has been restored triumphantly +to the Mammalian order, whence Geoffroy St. Hilaire had excluded both +it and its companion, the _echidna_, a sort of hedgehog, provided +like the ornithorhynchus with a bird-like bill, only more of the +canary-bird sort; and like it, also, approximating to the bird tribe +by other details which do not belong to our subject. And so the matter +stands at present; and all we venture to say is that classification +had a very lucky escape. + +And now, my dear child, that I have made you acquainted in detail with +your nearest neighbors, the last of whom, nevertheless, are strangely +unlike you outside, however they may resemble you within, I shall take +the liberty of going more quickly over the ground, and shall point out +in the mass only the more important changes which lead from one class +of animals to another. I should be found fault with if I tried to make +you too learned, and you yourself might be tempted to tell me, to my +sorrow, that you had heard about enough. + + + +LETTER XXXIV. + +AVES. (_Birds._) + +Tell me, my dear child, when you have seen birds taking their flight +into the air, and going boldly to their object, without a thought of +all the barriers, ditches, rivers, and mountains, which hinder man at +every step in his travels, did it never strike you to wish for their +wings, and imagine how you would fly off if you had them? If you ever +dreamt this dream, do not apologise for it; it is one as old as the +world. 'Oh that I had wings like a dove!' cried the Prophet, nearly +3,000 years ago; and the dialogue of the swallow and the prisoner, so +often sung by poets, has been repeated in prose behind all the +prison-bars on the globe since prisons were first invented. + +Now you will not think it kind on my part, but I must undeceive you +about this fancy, as you will be undeceived some day about many others. +The wings of a dove or swallow would be of no use to you if you had +them, any more than the formidable swords of the middle ages would be +to our modern gentlemen, were any one to put such into their hands. +We are not adapted for them, nor they for us. + +You saw, some time ago, what an amount of muscular exertion was required +for running--what a violent flow of blood, what hurried play of the +lungs. Now in flying it is still worse; for the earth, at any rate, +holds us up quite naturally, whereas the air will not hold up the bird +unless it is beaten vigorously and unremittingly by an untiring wing. +If we men, constructed as we are, had to do such work, we should be +out of breath at once; the heart would cry out immediately for quarter, +and the diaphragm turn red with anger. And only just imagine in what +a critical position a poor wretch launched into the air on the wings +of a swallow would find himself when, at the end of five minutes, his +servants should refuse point-blank to go on working at a height of 500 +feet above the ground! + +But a bird has not these internal rebellions to fear. In the first +place, it has no diaphragm; so here is another friend to whom we must +say good-bye. We shall not meet with him again anywhere. The journey +we are taking together, my dear, is somewhat like the journey of life. +One sets off, surrounded by friends and acquaintances, but whoever +travels on to the end is apt to find himself alone at last; this is +what is happening to the digestive tube, which we shall see losing all +its accessories, one by one, as we gradually advance in our study. +Even now here is one essential fundamental difference in the internal +machinery. The body has only one compartment instead of two; and the +lungs, masters of the whole space, extend freely to its utmost depths. +When a fowl is cut up at table, look along the body, and you will find +lodged in the cavity of the ribs, a long, blackish, and spongy mass: +this is the lungs. There is not, therefore, the same danger of a bird's +getting out of breath as with us; that delicate board which is found +in our bellows is wanting in his. His is set in action solely by the +to-and-fro movement of the ribs, which is produced by muscular +exertions, which are greatly increased during the action of the wings. +From which it follows, that the rapidity of flight itself regulates +the arrival of air, and consequently the expenditure of strength, or, +if you like better, the activity of the fire, since the energy of the +muscles depends, as we have seen, upon the quantity of oxygen that +feeds the internal stove. + +This is not all. These elongated lungs are still not sufficient to +furnish the blood with all the oxygen demanded by this excessive labor +of flight. They are pierced with holes, through which issue pipes which +carry the air all over the body. You know what is said of +spendthrifts?-that they burn the candle at both ends. It is so with +the blood of birds. That fillip which in our case it receives in the +lungs, and which sends it back full of vigor into the arteries, is +repeated in the bird at the other end of the arteries as well. The +capillaries, those delicate vessels at the end of the arteries, plunge +from all sides into little reservoirs of air-lungs, therefore-where +the blood renews its provision of oxygen, and relights its +half-extinguished fire, so that it sends the combustion afresh into +the muscles on its return back to the heart, and sets them going a +second time. + +The natural consequence of this prodigality of combustion is, that +there must be, in proportion, much more oxygen in birds than in us; +and that of all animals a bird is the one most quickly poisoned by his +own carbonic acid when the air is not renewed around him. Therefore, +let me beg you never to think of putting a poor little bird under a +wine-glass, as a child of my acquaintance once did, that she might +examine her little friend more closely. In the twinkling of an eye he +would consume all the oxygen inside his prison, and you would soon see +him fall upon his side and die. + +On the other hand, the temperature of these flying machines, which +consume so much oxygen, is very much higher than ours. It rises to +41°, 42° (centigrade), and sometimes to 44°, 7° higher than with us. +If ever you have taken hold of a little bird, you will have remarked +how warm it makes your hand: this is quite natural, since there is +always a double fire going on within him, to meet the extraordinary +expenditure of strength that is required of him whenever he takes wing. +Besides, do but look at the poor little creature when you have +imprisoned it in a cage! How it goes up! How it comes down! How it +hops from one perch to another, with a quick sudden movement, like +that of a spring when it unbends. There is no apparent cause for this +state of continual agitation; and yet there is a cause, and only too +serious a one. Its fire is not slackened because you have put it into +a cage, and its muscles, lashed furiously on by the double-oxygenized +blood, drive it hap-hazard into a thousand movements, in which it +expends, as best it can, a superabundance of power, which no longer +finds natural employment. Little children, who are the real +singing-birds of our homes, and whose blood also drives much more +energetically along than ours--little children I say--often fare no +better than caged birds in those larger cages we call schools; and +schoolmasters and governesses would scold rather less if they thought +rather more about this. It is right, I do not deny it, that the +rebellious young rogues should be taught in good time not to abandon +themselves, like wild birds, to the mere animal impulses of the blood: +but, in dealing with them, one must also make allowances, as they say, +for the fire within, and know how to open the cage now and then. It +is not for you, however, that I say this, young lady: you are no longer +a little child; but it may happen that you may have some to take care +of some day. Believe me, then, you must not expect too much wisdom +from them, and you must allow them to change their perch every now and +then. It is a law of our Almighty Father that little children, and +little birds, should not stay too long in one place. + +The mechanism of the circulation is here the same as with us, and does +not offer any important peculiarity. Only the left ventricle of the +heart has walls of extreme thickness, which enable it to launch the +blood into the members with greater vigor and rapidity; and the blood +itself, although it is composed of precisely the same materials as +that of the mammals, differs from it nevertheless as regards the +globules. In the first place, they are more numerous; secondly, they +are larger; and finally, instead of being round like a plate, they are +drawn out ovally, and are almost shaped like those long dishes on which +fish is usually served. I shall not attempt to give you the reason of +their size and form. This is hidden from us in the same mystery which +envelopes all the microscopic population of the blood; but is it not +a curious thing, this strange persistency of form in the globules ofall +animals of one class? In all birds they are oval; in all mammals +they are round. In all? Nay, I am wrong. As if the better to hide from +us the key to this riddle, nature has amused herself by making an +exception. Camels and llamas, I forgot to tell you, have also globules +in the form of long dishes, like the hen and the chaffinch. Find out +why, if you can. As to the reason of the number, it is a very simple +one. Since the energy of the blood resides in the globules, it follows +that the most energetic blood will contain the largest amount of +globules. Looking at you, for instance, little monkey, running and +jumping about the garden, I would lay a wager, without counting first, +that there are, in one drop of your blood, some millions more globules +than in one of mine. + +Let us now go on to the digestion, with which, properly, we ought to +have begun; but I preferred pointing out to you, first, the particular +character which is the chief mark of distinction in the organization +of the bird. + +'When hens grow teeth,' says a shrewd proverb, meaning of course, +_never_. Birds have no teeth, and in this respect there is no +variety among them. All, from the first to the last, have uniformly +the same tool to eat with--the bill, that is--which is, in all cases, +composed of the same elements, two jawbones elongated to a point, and +clothed in a horny armour, which makes their edges sharp and cutting. +At the same time were we to review the birds in detail, as we have +done the mammals, you would see that there are almost more modifications +to be observed in this one single instrument than in our thirty-two +teeth. All birds have a beak, but each has his own, organized expressly +with reference to the kind of food needed by its owner. The eagle's +beak, which mangles living prey, is pointed, bent, and hard as steel; +the bill of the duck, which laps up water from ponds and puddles, in +order to get worms and half-decomposed refuse out of it, is soft, and +flattened like a shovel. The woodpecker's, which has to pierce the +trunks of trees, is like a pickaxe; that of the humming-bird, which +has to suck up the juice of flowers from the bottom of their corollas, +is slender as a needle. The swallow feeds on flies, which it snaps up +on the wing, and has a soft bill, which opens like a little oven. The +stork picks up reptiles in the mud of the marshes; its beak is +straight-pointed, cutting as a knife, and resembles a long pair of +pincers. The sparrow feeds especially on hard grains, difficult to +break; accordingly its beak is stumpy, short, and thick, and is arched +on the upper side for still further solidity. But I should never end +if I began to enumerate all the thousand varieties in the bills of +birds. Each variety, too, corresponds with some peculiar sort of life, +and consequently with a general conformation (easily ascertained) of +the animal in which it appears. Give a naturalist the bill of a +bird--only its bill remember--and he will tell you half its history +without fear of being mistaken. + +On the other hand, we must not deceive ourselves as to the real value +of this complaisant bill. Let it transform itself as it pleases into +all manner of forms for the better fulfilment of its task, it makes, +at the best, but a very poor instrument for mastication; nay, to say +the truth, it breaks, cuts, and tears, but it never masticates at all. +Thus the bird's mouthful is far from undergoing as perfect a preparation +as ours does. It is no sooner taken in than it is swallowed, and the +salivary glands, which are still to be found under the tongue, seem +only to be there as a matter of form; what little saliva they produce +is thick and sticky, and has none of the qualities necessary for making +that liquid paste which our tongue sweeps up from every corner of the +mouth. Besides, it must be owned that a bird's tongue would be a very +awkward implement in such a task. Open a hen's bill and you will see +therein a very inferior sort of porter. It is merely a dry hard lance, +as it were, armed with prickles at the point, as ill-qualified for +tasting as for sweeping. So the hen does not waste her time in finding +out the flavor of what is thrown to her. She picks up and swallows +over and over again, without appearing to experience any other pleasure +than that of satisfying her appetite. Birds of prey, it is true, have +rather more convenient tongues, capable, moreover, of tasting up to +a certain point; and the parrot, who is a complete epicure, and chews +his food philosophically, has a charming-little black one, thick, +fleshy, and susceptible--a true porter, in fact-who enables Polly +thoroughly to enjoy her breakfast. But certain birds who live on insects +surpass even the hen in the dryness and hardness of their tongues. +That of the woodpecker, especially, is a model of the kind, and deserves +a few words more than the others. Picture to yourselves a long pin, +terminated by an iron point with barbs like those of fish-hooks. An +ingenious mechanism enables the bird to dart it out with the rapidity +of lightning, far beyond his bill, upon the insects to which he gives +chase. The point pierces them, and the hooks retain them, without any +need of assistance from the bill. I have just told you that this bill +pierces the bark of trees; but it only plays the part of gamekeepers +on grand sporting occasions, who beat the bushes to make the game rise. +The woodpecker's bill routs up the insects by destroying their shelter; +but the real sportsman is the tongue. Good-bye to any notion of a cosy +little chat in such a porter's lodge as that! What could a harpoon +have to say for itself? + +Do not, however, let this miserable entrance-hall alarm you, at the +same time, for the fate of the mouthful thus presented half-dressed +to the œsophagus. You will find it only so much the better treated +within. In the first place, the œsophagus, when half-way down to the +stomach, swells out suddenly and forms a pocket, which is generally +particularly well developed in birds who feed on grain; this is called +the _crop_ in English, in French _jabot_; whence comes the application +of that word to those full shirt-frills which have sometimes been the +fashion. It is the pigeon's _crop_ that gives him the rounded chest over +which he bridles so prettily. The crop is a receptacle where the food +makes a halt: it is something between the pouch of the monkey and the +paunch of the ox; a preparatory stomach, which does not, it is true, +send back the grain to the bill, for the bill could do it no good, but +in which that grain lies until there is room for it further on. + +Prom thence it resumes its journey; but, before reaching the true +stomach, it passes through a second enlargement of the oesophagus, +whose walls are pitted with numberless little cavities, from which +pour over it the juices destined to supply the place of the saliva +that was wanting above. + +It reaches its destination at last, but still hard, and generally +whole. No matter, however. The stomach which receives it, and which +is called the gizzard, is quite a different sort of thing from a useless +membrane, thin and delicate like ours. It is a thick muscle of enormous +power, lined inside with a kind of horny skin, so tough that nothing +can break through it. You may form some idea of the prodigious strength +of this organ, when I tell you that turkey-fowls have been made to +swallow hollow balls of glass, so thick as not to break when dropped +to the ground, and that at the end of a few days they have been found +reduced almost to powder in the uninjured stomach. No fear of +indigestion with such an apparatus as that. Though the grain may not +have been masticated in the bill, what does it signify? There is a +power here, as you see, quite equal to carrying the whole work through. +Thanks, indeed, to the invaluable horn which lines it, fowls which +have no teeth of their own can safely present themselves with as many +and as hard ones as they please. They swallow small pebbles, which rub +against the grain, during the contractions of the gizzard, and act +just as effectually as if they were fixed in the jawbone. Well, this +terrible gizzard performs its crushing work with such energy, that not +only the grain but the pebbles themselves are ground down there, and +end by being pounded into fine sand. When you rear fowls, do not forget, +if you keep them shut up, to put within their reach a store of small +pebbles, so that they may have teeth to run to in time of need. + +You remember the _pylorus_--the porter down below, who keeps the +door of egress from our stomach? He is as badly provided for here as +his fellow-workmen up above; worse in fact. It is a gaping hole, and +we cannot expect a very strict supervision from it. Birds who feed on +fruits profit by this fact to carry vegetables from one country to +another. With such an easy opening, seeds have a good many chances of +passing from the stomach unaltered; and then they drop from the clouds, +as is supposed, hap-hazard, and germinate afterwards, when circumstances +prove favorable, to grow up before the astonished eyes of the natives +into plants of which they have never even heard. The French +Acclimatization Society, which I spoke of lately, and which, though +so modern, has correspondents all over the globe, is at this moment +laboring to effect an exchange between all countries of the natural +productions of their soil. But here you see that nature had thought +of this before, and established her acclimatization society long ago. + +To complete the internal work of digestion, so feebly begun in the +bill, an extremely large liver pours torrents of bile into the duodenum, +and the manufacture of chyle proceeds with that wild rapidity which +characterizes all the living actions of birds. But speaking of this +liver, I think I ought to give you an account of a celebrated dish, +considered a great dainty by epicures, called _pâtés de foies +gras_--_fat liver patties_, to translate it into its meaning. +Very likely you will not care to eat them after hearing my story; but +that will be no great loss to you, for it is a very indigestible sort +of food, and not at all good for children. + +You remember my telling you about Englishmen going to India and coming +back with a liver-complaint, from having eaten and drunk more than the +climate allowed? By an imitation of this process, human +ingenuity--occasionally so cruel--has created the _pâtés de foies +gras_, the glory of Strasburg. I have been in the country, and can +tell you how it is managed. They shut a goose up in a square box, where +there is just room for his body. They open his bill at feeding-time, +and cram down with the finger as much food as can be got in. This is +throttling rather than feeding it. The poor beast, who can use no +resistance, since it cannot move, and who is kept in the dark to prevent +excitement; the poor beast is quite unable to burn all the mass of +combustibles with which the blood soon finds itself loaded. This carries +them to the liver to be turned into bile; but the liver is not equal +to the work, becomes loaded in its turn by unemployed materials, and +grows and grows, till at last, having filled up all the space around +it, it stops the play of the heart and lungs. When the animal is +nearly suffocated they kill it; and this is how we come to have _pâtés +de foies gras_ to eat! If they give us a fit of indigestion +afterwards, it is a vengeance we richly deserve. At Toulouse, where +the same trade is carried on on a large scale, they used formerly to +go even beyond this. They fastened the goose by the feet before the +fire-place, after having put out its eyes. The imitation of the +Englishman's proceeding was still more perfect here, for the fire acted +the part of the Indian sun to perfection. I do not know that part of +the country well enough to tell you whether they have quite given up +this piece of wicked ingenuity; all I can say is, I devoutly hope so. + +The intestine of birds is much shorter than that of mammals. Here +everything is done at full gallop, and the chyle has not to go far +before it is absorbed. I have before me a book, in which I am told +that the wagtails eaten in France can be fattened in twenty-four hours, +if you only know how to set about it, and these birds are not rare; +they belong to the same family as the red-breasts, the tomtits, and +the nightingale. Thrushes and wheatears (ortolans) require, for the +same purpose, four or five days in the same country, left to themselves +to roam about, when the vine keeps open table for them. + +This incredible quickness, not only in digesting, but, what is much +more, in transforming food into fresh living material +(_assimilating_ it, as it is called), has often a fatal result +for the bird. He is prohibited from fasting; his life is a fire of +straw, which must be replenished unceasingly, or it will die out in +the twinkling of an eye. Our own little birds--children--eat oftener +than grown-up people, and if by any accident they are kept waiting +awhile, they soon cry out with hunger. You know this, do you not? Well, +then, if any one should give you a bird to keep in a cage, remember +that you have undertaken a great responsibility, and that it will not +do to be careless with him. To neglect feeding him for one day is to +run the risk of finding him starved to death next morning. With this +warning, I will conclude my chapter on birds. I hope I have not spoken +in vain in behalf of those poor little captive songsters, whose fragile +lives are at the mercy of their young masters and mistresses. + + + +LETTER XXXV. + +REPTILIA. (_Reptiles_.) + +Passing from birds to reptiles is like falling from a torrent into +still water. Life drags on as sluggishly with the second as it dashes +furiously forward with the first. + +I spoke to you just now about a fire of straw: now we have a fire such +as Frenchwomen make in their _chaufferettes_, or foot-stoves. A +handful of charcoal-dust, and a few live embers between two layers of +ashes, is enough for the whole day; which is economical, is it not? +but then it throws out only just warmth enough to keep one's feet +comfortable. And so it is with reptiles. They live at very small +expense. If you feed them once a month they will not complain, for so +slow a fire does not often need replenishing with combustibles. It is +even said that the experiment has been carried so far with tortoises +that they have been made to fast for more than a year, and still the +charcoal fire kept up its languid pace. Of course, on the other hand, +there is not nearly so much oxygen consumed at once upon such a diet +as this. Where a bird would perish twenty times over in five minutes +for want of oxygen, a lizard can remain whole hours with impunity. +Moreover, the animal heat of reptiles is in proportion to their +expenditure of it. Graceful as is the snake (that living jewel so often +copied by bracelet-makers), you feel on touching it an instinctive +horror, caused by the thrill of cold it produces. All the animals we +have considered hitherto have warm blood, and bear within themselves +the source of their heat, which is pretty nearly always the same. But +reptiles are cold-blooded, and heat comes to them chiefly from without. + +If, at the end of a cold winter, we go to some favorable corner to +catch the first rays of spring sunshine, we feel ourselves almost +re-born, as it were, as if a new life had come into us with the +sunbeams. Look at the little lizard you see frisking on the white +stones of the wall; upon him decidedly the sun is darting actual life +from its rays. While the cold lasted he staid squatting in his +hiding-place--not asleep, but annihilated--congealed, so to speak, +like water caught by the frost; no longer digesting, and hardly +breathing, he had ceased to live in reality: and it is no imaginary +regeneration which the return of warmth brings to him. Like those +helpless people who have not the power to carve out their own destinies, +reptiles have within them only an insufficient source of animation; +their life is at the mercy of the sun, and is high or low, according +as that rises or sets in the heavens. At Martinique, where at noonday +it darts its devouring rays perpendicularly upon the cane-fields, and +every one flies into the shade to escape its scorching heat, the +rattlesnake traverses the country, monarch of all he surveys; he strikes +rapidly with a vigorous tail upon the calcined ground; and woe then +to any one who receives his bite! All the fire of the atmosphere has +passed into his frame. Now go to the Zoological Gardens, and see him +there: he crawls languidly under the coverings that shelter him; if +by chance he bites any one, it is with an idle tooth that no longer +knows how to kill; his life was left behind with the sun of the tropics, +and it is little more than a corpse that you are looking at. + +And so among ourselves, my dear child: we meet with people whose whole +power comes from without, who are brilliant and haughty in the sunshine +of good fortune, but crest-fallen, cowardly, and cringing in the cold +days of adversity. Nevertheless, they are constituted originally like +other people: they are neither greater fools as a general rule, nor +less gifted than their neighbors; where they fail is in the heart, but +that is enough to spoil everything. And so with reptiles: the heart +is their weak point also. Like us, they have lungs into which the air +pours without any difficulty, and a heart to send the blood to them; +so it seems at first sight as if there could be nothing to prevent +their resisting the changes of external temperature just as well as +ourselves. There is only one small trifle wanting, and that is a +partition in the middle of the heart; but this one defect is enough +to disorder the whole machinery. + +You know that, with us, the heart is divided into two compartments: +the right ventricle, which receives the venous blood from the organs +and sends it to the lungs; the left ventricle, which receives it (now +become arterial) from the lungs and returns it to the organs. Hence +the double system of veins and arteries, the one going from the heart +to the lungs, the other from the heart to the organs. All this is found +the same in reptiles: except that the partition, which separates our +two ventricles from each other, does not exist in them; and the heart +has only one common room, in which, therefore, arterial and venous +blood become mixed together. It follows from this that, at each +contraction of the heart, it is a mixture of arterial and venous blood +which is sent in the two opposite directions at the same time, and +that the organs receive some which has been used before, while the +lungs have some returned to them which has been regenerated already. +Now, on the one hand, this mixed blood can only keep up an imperfect +combustion in the body (like the live embers between two layers of +ashes that we spoke of lately), and, on the other hand, the air in the +lungs can only act upon a part of the blood it meets with there, the +rest having already undergone the regenerating process. And this +accounts for both the feeble animal heat and the small consumption of +oxygen in reptiles. + +Added to which the lungs of a reptile are coarsely constructed, and +composed of cells enormous in comparison with ours, so that the blood +does not find nearly as many little chambers to rush into for a taste +of air as with us. Moreover, you must understand that there is no such +thing as a diaphragm here: the lungs float loosely in the form of +elongated bags in the one only cavity of the body, and the slight +movement of the ribs does not allow them to dilate sufficiently to +take in much air at a time. + +All these things, taken together, make the reptile a very poor stove, +and render him incapable of any prolonged exertion. The serpent darts +like an arrow upon his prey; but he could not pursue it for half a +mile without stopping, not even over the burning soil of the equator. +The lizard is very nimble, is it not? and the quickness of its movements +rather reminds one of the agility of a bird. But watch it, and you +will see it only moves in jerks, and keeps stopping every minute; it +cannot escape you if there is no hole near into which it can disappear. +In France there is a large green lizard that runs among the vine trees. +If you pursue him he is off like lightning for a second; then he stops +suddenly short. You return to the charge, and he starts afresh, but +only to stop again. At the fourth or fifth attack he is quite out of +breath; you poke him with the stick with which you have been hunting +him, but in vain; there he lies motionless, in spite of his alarm. A +few steps have brought him to the end of his powers, like a man whose +heart is diseased and who cannot go far. This, however, is a peculiarity +common to all reptiles. Each of the three orders of which this third +class of Vertebrata is composed has its own particular history besides. +You must excuse my mentioning the barbarous names that have been given +them, and allow me to call them _tortoises_, _lizards_, and _serpents_, +like other people. The hard names mean no more than these; but they are +Greek, which is always more imposing. + +The slowness of the tortoise has passed into a proverb, which is not +to be wondered at; for they cannot inhale the air, because their ribs +(which are a reptile's only resource for breathing) are condemned to +absolute immobility. The _carapace_, or shell, which the tortoise +carries on his back, and under which it retreats upon the least alarm, +as under a shield, is really formed of its ribs, each of which has +widened itself so as to join on to its neighbor, like the boards of +an inlaid floor, which run one into another. Of course there is no +question of moving up and down with such ribs, and the poor bellows +cannot work at all. How does the tortoise get out of this difficulty +then, you will ask? I answer, it swallows air, as we should swallow +a glass of water. You see its mouth open and then shut again, thereby +taking in an actual mouthful of air, which the sides of the mouth, by +contracting themselves, send straight to the lungs. These, which are +very large, get filled in this way by degrees, and, when they are quite +inflated, they expel the overplus by collapsing, like an over-stretched +spring. You may imagine that this does not produce a very active +respiration, and that a tortoise would be puzzled to run at even a +moderate trot. To be sure, when he has once filled his great lungs +with air, he has enough for a long time. Most tortoises are aquatic, +and, as divers, leave the cetaceans far behind. Méry, an obscure French +naturalist of the days of the Empire, pretended that he had kept in +his house, _for a month_, some tortoises, whose breathing he had +completely stopped. Only imagine from this how far their life must be +below ours, although it is the result of similar actions, performed by +organs which after all are copies (imperfect ones, it is true) of our +own. + +Some tortoises feed on vegetable substances, and some upon fish or +small soft-bodied animals. Like birds, they mash their food with +difficulty, by means of a real bill. Their jawbones are generally +arched forward toward the front, and are furnished with sharp horny +plates, in which a fairly-marked denticulation or notching may sometimes +be traced, as in the bills of birds of prey. Indeed there is one, the +_caretta_, whose hooked and notched beak so completely recalls +the warlike bill of a hawk, that it is usually known by the name of +the "Hawk's-bill Turtle." You ought to know about this tortoise, for +it is the one which furnishes tortoise-shell, that nice material which +is so smooth to the touch, so pretty to look at, and so very fragile, +that it seems only fit for the use of ladies' hands. I could hardly +speak of tortoises without saying something of this one, out of +whose back was carved the handle of your own pretty little penknife. + +Behind this bill of the hawk's-bill there is a tongue, but of the +character of a whale's tongue, and it is fastened underneath to the +bottom of the mouth. At the base of it there is a sort of fleshy pad +or cushion, which serves instead of a soft palate, that being another +detail which is about to disappear from our history. We are now really +entering upon the simplification of the digestive tube, which will, +I forewarn you, end by being nothing more than a perfectly straight +pipe, without any appendages whatever. In tortoises the intestine is +still tolerably long, and is doubled up backwards and forwards many +times in the abdomen; but it is already beginning to lose that variety +of form which its different parts assumed in the higher animals. The +large intestine can no longer be clearly distinguished from the smaller +one, nor this from the stomach, which itself seems to be a continuation +of the oesophagus, without any very distinct boundary line between them. +The porter, who with us keeps the door of the stomach, does his duty +here so badly, that there are certain kinds of tortoises whose +oesophagus is covered with spines, the points inclined backward, to +prevent the food from rising up into the mouth whilst the oesophagus is +driving it down by its contractions. + +In the gray lizards of our walls we find teeth again, but very different +from any that we have hitherto seen. In the first place, they are not +content with their usual place on the edge of the jaws, but encroach +upon the surface of the palate, where they stretch out in close lines. +Besides, they are even still less like teeth than the great nails in +the jaws of the cetaceans. They are little ivory prongs, with the +points turned inwards, analogous to the thorns of the oesophagus in the +tortoise, and serve the lizard solely to retain and bruise his prey. +He lives on insects, especially flies, which he seizes on the wing +with the greatest skill, hastily catching and engulphing them in his +open jaw; they pierce themselves on the little prongs, and are swallowed +promiscuously. The tongue of the lizard has also a curious peculiarity, +which is shared by that of the serpent: it is divided at the end into +two threads, which dart in and out of its mouth, and by means of which +it laps, like a dog, the few drops of water it requires to satisfy its +thirst. I have seen lizards which had been tamed by children greedily +sucking up the saliva from their lips by drawing across them those +little forked tongues of theirs, which, after all, are very soft, and +perfectly inoffensive. + +The tongue of the chameleon, another species of lizard, is still more +curious. You must know that the chameleon is a lumbering lazy animal, +who feeds on flies and other swift insects, and who would, therefore, +be constantly liable to go without his dinner but that his tongue +serves him for a hunting weapon, like those of the wood-pecker and the +ant-eater. When at rest, it is an oval spongy mass, lying comfortably +in the mouth, with nothing formidable in its appearance; but let the +prey come frisking round the chameleon, as if despising so helpless +an enemy, and this great soft tongue is transformed into an active +dart. It shoots forth like an arrow, and will sometimes seize the rash +intruder at half a foot's distance, transferring it with equal rapidity +to the motionless mouth. The blow is so soon struck, that it is very +difficult to see how it all happens. Some say that the chameleon curves +the tip of his tongue by a sudden effort, and then catches his flies +with it, just as you would catch them with your hand. Others maintain +(and this is the general opinion) that the tongue of the chameleon is +terminated by a sort of sticky cushion, on which the flies are caught, +like birds with birdlime. This singular dart is always out-jerked with +such force that, if it strikes against a glass (the experiment has +been tried with chameleons in captivity), it makes a sound as loud as +that of a pea from a pea-shooter; so you may judge if it is not strong +enough to stun a fly. Besides this, too, the chameleon (who is +by-the-by, a hideous little beast) has given endless trouble to +naturalists on another and very different point. It is he who is +so celebrated for his faculty of changing color when any emotion +agitates him; and ever since the days of Aristotle, who lived more than +two thousand years ago, people have been trying to explain this, without +any one being able to flatter himself that he has found out the exact +answer to the riddle. + +But there is a lizard more interesting still, and that is the crocodile. +He stands alone among reptiles. His heart has two ventricles, and you +would think that he ought to be included in the class of warm-blooded +animals. But, no. The separation of the two kinds of blood takes place +in the heart, it is true, and it is really true arterial blood which +the aorta carries away from the left ventricle. But the right ventricle +has two doors of exit. One communicates with the lungs, the other with +the aorta; and the latter has hardly performed its distribution in the +upper part of the body when it meets, as it descends, with a treacherous +tube bringing to it a current of venous blood. In this way only half +the blood that comes from the veins passes on to be regenerated by +contact with the air, and all the hinder part of the body receives +nothing but the mixed blood common to reptiles, while the head and +fore members enjoy the privilege of the superior orders. After this +go and lay down your laws of classification! Nature, while maintaining +amongst all animals the same principle of life--the regeneration of +the blood by oxygen--has in their construction followed many systems +leading to the same result by different combinations, and which seem +to permit the establishment of essential distinctions among them. Here +is an animal who, if I may so express myself, is climbing up from one +system to the other, and you would have to cut him in two before you +could classify him properly, since his fore-quarters have risen to the +warm-blooded animals, while his hind ones are left behind among the +cold-blooded reptiles! + +But there is something which even outdoes this. + +On dry land the crocodile is timid, faltering, a bad walker, incapable +of regular combat, and a man can manage him with a stick. One feels +that he is betrayed by the hinder half of his body, through which +circulates the only half-oxygenized blood. But when once he has plunged +into the water his whole behavior suddenly alters; he is a ferocious +being, high-mettled, indomitable, a savage enemy, redoubling his +exertions, as if the entire mass of his blood had suddenly become +arterial. Geoffroy St. Hilaire, who followed Bonaparte as a scientific +explorer when he set out for the conquest of Egypt, the country of +crocodiles, was deeply struck by studying on the spot this double life, +which seems in a way to maintain two beings in the same body. He +afterwards gave an extremely curious explanation of it in his work on +the crocodiles of Egypt. Here it is; but I forewarn you that you will +not understand it: + +"The crocodile, when it is under water, receives by two canals into +the cavity of the abdomen, a considerable quantity of water, which the +animal can renew at will." + +You are not much the wiser, are you? But wait a moment. We are soon +coming to the fishes, and you will then see what an unlimited scope +nature has allowed herself here. Not satisfied with two systems in one +animal, she appears to have got hold of three. + +If we continue the examination of this privileged reptile, we shall +find many other infractions of the usual rules of his class. His tongue, +certainly, is fastened to his mouth like that of the tortoise, so much +so that the ancient Egyptians told the Greeks he had not got one; but +his set of teeth clearly approach those of the lower mammals. You have +probably heard a great deal of the strength of the crocodile's +formidable teeth. Travellers have given them this reputation; but we +have nothing to do with that now. They stand in battle array, in a +single line, along the whole length of the jaws, into which they are +sunk with genuine fangs, whilst the prongs of our little lizard are +merely fastened to the surface of the bones which support them. Indeed, +in one way, the crocodile is even better provided than the mammals. +He possesses under each tooth one or two germs, the life of which lasts +as long as that of the animal, and which are always there ready +toreplace the previous one should it chance to fall out. There are many +ladies, and (not to be rude) gentlemen as well, who would, I am sure, +give a great deal to have as many teeth at their service. Indeed, they +may possibly think Dame Nature very unjust to have selected this great +villanous beast rather than us as the object of a gift which they would +have been so well able to appreciate. But we must not blame nature too +quickly: she had her reasons. We, during our infancy, have teeth in +reserve. Now, a reptile may be considered as an imperfect rough draft +of a mammal; and the crocodile gives one thoroughly the idea of a +mammal half-finished and fixed for life in a state of childhood. I am +sorry that I cannot enter into full details, that you might see how +far the idea is a just one. Moreover, in his character of a perpetual +child, he is always growing bigger all his life long, and never seems +able to die but by accident, hardly ever, I may really say, from old +age. By specimens kept in captivity, it has been ascertained that +their growth is very slow. Well, imagine their being only from seven +to eight inches long when they come out of the shell, and that +full-grown crocodiles have been found thirty feet in length, and +calculate accordingly. You will not account for it under a century; +and I should like to know what would become of this venerable child +of more than a hundred years old if kind Mother Nature had not left +him our system of milk-teeth to the end? + +A curious peculiarity of these persistent teeth is, that they are +hollow inside, so much so, that the bowls of tobacco-pipes are said +to be made from them in Europe. I mention the fact, although of no +great interest to you, for the benefit of any pipe-merchants who have +not yet thought of sending for such things to Cairo. + +But let us return to the efforts perceptible in the organization of +the crocodile to raise itself to a higher level. The soft palate, as +we called it (Letter VII.), is wanting in other reptiles; but here +there is one which completely closes the entrance of the windpipe (the +larynx). I announced, too, the disappearance of the diaphragm; and we +bewailed together the loss of that servant of the good old times, whose +touching history you must, I am sure, remember. But I reckoned without +this wretched crocodile, who seems determined to give the lie to all +we have been saying. He has a diaphragm, and one which acts well enough +in the main, although it is pierced right through the middle, as if +it were rather ashamed of being there, and wished to make up for +dividing the body into two compartments, against all proper reptile +regulations, by opening a door of communication between them. What +shall I tell you besides? The lungs, not to be behind the rest of this +aristocratic reptile's organization, are hollowed into cells much more +complicated than those of his fellows. You find here no end of nooks +and corners, which multiply opportunities of contact between the air +and the blood, and so give the crocodile almost the respiration of the +mammals, as he has already got pretty nearly their system of +circulation. + +With serpents, again, we fall very low. When we were speaking of the +tortoises I told you that, in proportion as we come down in the scale, +the digestive tube has a tendency to get rid of its accessories, and +to assume the appearance of a perfectly straight tube. If any one were +to cut open a serpent before you, you would see this final condition +almost reached already. In the first place, the soft palate is entirely +suppressed, and the mouth extends straight into the oesophagus, whose +tube seems to run through the whole length of the body without +interruption, with just four or five doublings towards the base, in +that part which represents the intestines. An imperceptible swelling +indicates the place where the real stomach lies within; but in another +sense one may call the oesophagus, and I might almost add the mouth +itself, its stomach. You shall see how. + +The jaws of serpents are even in a more unfinished state than those +of other reptiles. Nature has not taken the time to weld the different +parts of them together; but these begin by not being very firmly joined, +remember, in young mammals. The bones of the head, which support the +jaws, are themselves movable, and can be detached from the skull if +necessary, so as to allow the throat to open extraordinarily wide; +thus it is not uncommon to see a serpent swallow animals much larger +than itself. You will be horrified when I tell you that the anaconda, +one of the giants of the family, swallows large quadrupeds at a single +mouthful. What are our mouthfuls in comparison with his? however, it +must be confessed, that his often take several days to go down. When +the animal has rolled up his prey in his terrible folds, he pounds and +kneads it till it is reduced to a kind of long roll, which he moistens +with a copious slaver to make it slip down more easily. Then, attacking +it at one end, he fastens this very expansive jaw upon it, and the +gigantic mouthful slowly begins its journey; what was left outside the +mouth, advancing little by little, in proportion as the digestion +reduces what has entered to pulp, and sends it farther down. This is +on great occasions; but in the case of more modest prey--a rabbit, for +instance--the mouthful goes in whole at one gulp and remains stationary, +partly in the oesophagus, partly in the stomach, while the powerful +juices distilled by the walls of the latter are dissolving it. + +You can see that a soft palate would have been quite useless here, and +that the serpent has not much need of teeth to chew his food. +Accordingly, his are nothing but simple prongs, like those of the +lizard, and, like his, they extend over the palate, the more effectually +to cut off the return of the swallowed masses of food. About a hundred +and twenty have been counted in the throat of the boa-constrictor; but +their number varies considerably in the different species. They are +not organs of the highest order, and nature is not very particular +about the quantity. + +There is only one tooth among serpents of which she takes any particular +care, and that is the venomous tooth which she has bestowed on certain +species, and which serves them for striking down, as it were, the +animals on which they feed. Let us study it in the rattlesnake, the +most celebrated of this odious race. On each side of the upper jaw you +may see, isolated from the others, and exceeding them all in length, +a very sharp fang pierced through by a tiny canal, which opens into +a gland placed at the root of the tooth. The bone which supports this +little apparatus is very flexible, and when at rest, the fang, falling +back, hides itself in a fold of the gum. When the animal wishes to +bite, it springs up again, and the gland, compressed by the action of +biting, sends into the little canal a jet of poison, which runs through +it into the wound. As far as can be ascertained, this poison paralyses +the victim and disorders the blood, which at once loses its power, +and no longer acts upon the organs as before; still it is only injurious +when it has been carried by the current of circulation into the mass +of the blood; if swallowed, it has no effect whatever on the stomach. +Now do not look at me with such incredulous eyes, as if it were quite +impossible any one should think of swallowing such a thing. You have +no idea what a scientific man is capable of when he comes to close +quarters with nature, for the purpose of extracting one of her secrets. +He has his own fields of battle, where very often as much courage is +displayed as on any other. + +These two fangs, in which lie all the power of the animal, are of the +greatest importance to him, and their want of solidity makes them +liable to remain in the wounds which they have made. In consequence +of this, they enjoy the same privilege as the teeth of the crocodile, +and in a still greater degree even. Behind each poison fang lie in +wait, not one nor two, but several sentinel germs, ready at the first +alarm of a loss to set to work and re-supply the disarmed serpent with +his venomous needle. So the serpent also lives in a state of perpetual +childhood: he is always growing; and I could not tell you the exact +natural limits of his life any more than of that of the crocodile. +They are gentlemen who do not allow themselves to be very closely +studied in a state of freedom. But these also grow very slowly, and +some have been met with whose size had extended quite enormously from +their first start. I ought to tell you, once for all, that this +indefinite growth, joined to extreme longevity, is found in many of +the inferior species whom we have yet to consider. It seems the portion +of these unfinished creatures, in which nature has only as it were +sketched in her work, and who seem vowed to endless youth, in testimony +of the state of childhood they represent, a state transitory among the +superior animals, but permanent with them. It belonged of right, +therefore, to the serpent, which is the most unfinished animal we have +yet met with, and who, at the first glance, seems almost reduced to +a mere digestive tube, lodged between a vertebral column and a series +of small ribs, whose number sometimes reaches three hundred. The liver, +which, with us, presents such a distinct and bulky mass, is here +elongated into a thin cord, which runs the whole length of the +oesophagus +and intestine, to the walls of which it is, to some extent, attached. + +It is the same with the lungs. There is rarely room for the full +development of two in this narrow conduit, where everything has to +follow the shape of the master of the house: one, therefore, is often +merely indicated by a very slight protuberance; the other, presenting +the appearance of a long tube, which extends nearly half-way down the +body, and whose feeble action halts periodically at each of those +monstrous repasts, after which the torpid animal becomes nothing but +a huge digesting machine. We have now reached the extreme limits of +that organization, the most perfect model of which we find in man, and +which is no longer to be recognized in fishes. + + + +LETTER XXXVI. + +PISCES. (_Fishes._) + +We are becoming terribly learned, my poor child, and I am half afraid +you will be getting tired of me. When I was little myself, I had rather +a fancy for breaking open those barking pasteboard dogs you know so +well; to see what was inside them. Why should you not, then, feel a +certain amount of interest in looking with me into the insides of real +animals? Still I cannot conceal from myself that the subject grows +very serious at last, and that while I am busied in struggling to make +myself intelligible through the endless crowd of facts which surround +me, I am apt to neglect chatting with you as we go along. Happily, +however, here is an opportunity for so doing. + +Up to the present time we have lived, as it were, upon the explanations +I gave you whilst studying the action of life in yourself, and all the +organs we have met with since, have been only, properly speaking, +reproductions, more or less exact, of those which you yourself possess. +But, in passing over into the kingdom of fishes, we find ourselves in +the presence of something altogether new, and I must go back to our +old familiar style of talking to open the subject. + +Take a water-bottle half-filled with water, and shake it well, and you +will see a quantity of white froth come to the surface of the liquid. +This is the air which having been drawn in by the water, as it went +up and down in the bottle, is now struggling to fly off again in bubbles +as fast as it can. But the whole of it does not get away; a small +portion remains behind, and melts, as it were, into the water, as a +morsel of sugar would do, taking up its abode therein. This seems odd +to you, but I will tell you how you may convince yourself of the fact. +Get a small white glass bottle, slightly rounded, and thin at the +bottom, if possible; fill it with water, and hold it for a short time +over a lighted taper. If you do this carefully there is no danger. You +will soon see tiny little balls, looking like drops of silver, rise +from the bottom of the bottle, come up to the surface, and burst. This +is the air which was installed in the water, as I described above, and +which is now running away from the heat of the candle, as the +inhabitants run away from a house on fire. After a time the whole will +have passed off, and the little balls will cease to rise. + +But what has all this to do with fishes? you ask. + +A very great deal, I assure you, dear child. If there had been a little +fish in your bottle, before it was exposed to the flame, it would have +found means to make use of that air, whose original presence in the +water you cannot refuse to believe after having seen it come out. It +is with this air that fishes breathe in the water. They do so rather +feebly, I admit; but, as if to make up to them for the small amount +of the air placed at their disposal, it contains more oxygen than that +we breathe ourselves, because oxygen, dissolving more readily in water +than nitrogen, is there in greater proportion. Of course, you do not +suppose that fishes have lungs like ours? I dare say you know the two +large openings on each side of their head, called _gills_, by which the +fishermen string them together to carry them away more easily? It is +there you will find their lungs, to which the name of _branchiae_, or +gills, has been given, because they are so different from other organs +of respiration that it was impossible to use one word for the two. The +arrangement of the gills varies considerably in the different species, +but their general form is the same everywhere. They are composed of a +number of plates, consisting of an infinitude of leaflets, arranged like +a fringe, and suspended by bony arches, into which plates and leaflets +the blood pours from a thousand invisible canals. + +First of all, then, we must see how blood circulates in fishes. + +Like reptiles, their heart has only one ventricle, and yet the arterial +and venous blood go each its separate way without the slightest risk +of being mixed; but this is because fishes have not that double system +of veins and arteries which hitherto we have always met with. The +venous blood goes to the heart, which drives it into the gills, from +whence it passes forward of its own accord, as arterial blood into the +organs, under the remote influence of the original impetus from the +heart, the newly-arrived blood incessantly driving the other before +it into the vessels of circulation. It does not flow very quickly, as +you may suppose; and as the heart is close to the head, its action is +but very feebly felt at the extremity of the body, when this happens +to be very long. Nature has, in consequence, taken pity on the eel, +whose tail is so far from its heart, and provided accordingly. Dr. +Marshall Hall has discovered near the tip a second, reinforcing heart, +so to speak, which has its own pulsations, independent of the pulsations +of the one above, and gives a fresh impetus to the sluggish blood, +[Footnote: Many observers refer this to the lymphatic system.--TR.] +which otherwise, as it would seem, would scarcely be able to accomplish +the long return journey. Finally, even with an additional heart in +thetail, the circulation among fishes is quite on a par with their +respiration. They have a melancholy steward, whose legs are very heavy, +and his pockets very light, and their life comes down a peg lower in +consequence. It is always the same life nevertheless--you must never +lose sight of that fact: it gets low in consequence of the imperfection +of the machine, but without changing its nature, any more than the +light in our different sorts of lighting apparatus. You remember that +comparison of the lamp with which I began my story, and which you could +not at the time see the full value of? From a dungeon lamp up to a +candle, you have always grease burning in the air at the end of the +threads of a wick. It does not burn equally well everywhere, and does +not always give the same amount of light; but that is all the +difference. From the mammal to the fish, it is always hydrogen and +carbon (as we have said of the grease) which oxygen sets on fire in +the human body at the fine-drawn extremities of the blood-vessels; +only the fire is lower in some than others, and the life with it. Let +us now look at the circulation of water in the fish's body. + +The gills communicate with the mouth by a sort of grating, formed by +the bony arches to which the gill-plates are suspended. The fish begins +by swallowing water, which then passes through the grating and +circulates round the innumerable leaflets of which each plate is +composed, and among which creep the blood-vessels. It is through the +thin coats of these leaflets that the mysterious exchange is made of +the unemployed oxygen in the water and the carbonic acid in the blood. +When this is over, the cover which closes the gills opens to let out +the water, and a fresh gulp takes its place; and so on continually. +When the fish is out of the water its gills fall together and dry up; +the course of the blood, already so weak, is interrupted by the breaking +down and shrinking of the vessels, and the animal can no longer breathe; +so that we have here the curious instance of a creature breathing +oxygen like ourselves, who is drowned, if we may use the expression, +in the air in which we find life, and lives in the water in which we +are drowned. While he is in the water matters take another course, and +his gills, moistened and supported, accommodate themselves perfectly +to the contact of the air, which desires nothing better than to give +up its oxygen to the blood, through the coats of the capillaries. +Accordingly you will often see fishes--carps, for example--come to +the surface of the water to inhale the air like a mammal or a reptile. +This is a valuable resource, which supplements the parsimonious +allowance of air given out to them by the water. There are even certain +fishes whose gills, more firmly closed than those of others, have, in +addition, a number of cells, which retain for a considerable time a +sufficient quantity of water to preserve the gills in their natural +state. These fishes can easily take an airing on land, where they +breathe the air as you or I do, and are downright amphibians. + +The most celebrated of these is the _Anabas_, or "climbing-fish." +an Indian fish, which not only can remain many days out of the water, +but also amuses itself by climbing up the palm trees--it is hard to +say how--and establishing itself in the little pools of water left by +the rain at the roots of the leaves. But we need not go to India to +find those wandering fishes. There is one of them living among ourselves +who can walk about in the grass, and I was talking to you about him +only just now--that is the eel. If you ever put eels in a fish-pond +you must, I assure you, try to make it agreeable to them, otherwise +they will have no scruple in setting politeness at defiance and moving +off to seek their fortune elsewhere. In a country walk, when the dew +is on the ground, you yourself may chance to come across one or two +of these gentlemen, who have had their reasons for changing their +residence, and whom you will see gliding so briskly along that they +will deceive you into taking them for snakes if you have not a very +experienced eye; so much so, that in certain parts of France where the +peasants ate snakes formerly, they reconciled themselves to the sickly +idea by christening them _hedgerow-eels_. + +On the other hand, fishes may be drowned in water just as easily as +ourselves if it does not contain air. The little fish who could have +lived very well in the bottle we were just now talking about before +you exposed it to the flame of the taper, would have died in it after +all the air-bubbles had gone off; and I hope I need not tell you why. +In the same way, if you leave fishes too long in a small quantity of +water without renewing it, they suffer exactly as we do if the air +which we breathe is not changed often enough. As soon as they have +consumed what oxygen is in the water, it can no longer keep them alive. +It is then, especially, you will see them come gasping to the surface +to call upon the air for help. Those who keep gold fish in a glass +bowl ought to know this, and to change their water oftener than is +generally done. When we take poor little creatures from their natural +way of life, and set a human providence over them in the place of the +Divine one which has hitherto been their safeguard, the least we can +do is to acquaint ourselves with the laws of their existence, so that +we may not expose them to the risk of suffering by our ignorance. +Finally, there are fishes whose gills, still more greedy of oxygen, +will not act well except in thoroughly aerated water, and who would +soon die in our tanks. This is the case with the trout, who is only +happy in the waters of hilly countries; rich with all the air they +have carried along with them as they fell from rock to rock. Now that +people are beginning to do with fishes what has long since been done +with sheep and oxen--keep them in flocks to have them always ready for +use--you may perhaps hear a good deal said about vessels made expressly +for the carriage of trout, with a thousand inventions besides for +sending air into the water, and you will not have to ask the meaning +of this now. + +I promised last time that I would revert in the chapter of fishes to +that marvellous transformation of the crocodile which has been explained +by the torrent of water he draws into his stomach. You could understand +nothing about it the other day; but after what we have just seen the +explanation suggests itself. Just as the extraordinary activity of +life in birds is explained by that double oxygenization of blood, of +which part takes place in the lungs and part in the reservoirs of air +placed everywhere in the way of the capillaries, so this sudden increase +of energy in the crocodile the moment it plunges into water may be +explained by a second respiration suddenly established in the vast +cavity of the abdomen, by the contact of the capillaries with the water +which penetrates there. Hence the crocodile would then have, like the +bird, a double respiration: only with him the one would be permanent +and from the lungs, the other temporary and from the stomach. By this, +on the one hand, he would rise up to the birds, since the blood +encounters air twice over in its course, while, at the same time, he +would plunge into the world of fishes, since the blood has to seek air +in the water. The above, be it remembered, is only a supposition, and +I ought to add that in this case there would be a good deal of danger +in observing nature at work, for in front of the laboratory, where she +is toiling in secret, stands on guard a row of teeth, by no means +encouraging to indiscreet intruders. At the same time, if there ever +were a legitimate conjecture, this is it. Everything seems to confirm +it; and if it be true, we should have in the crocodile a specimen of +each of the four systems adopted by nature for the mammal, the bird, +the reptile and the fish. At first I spoke of two, then of three; so +that even in my addition I was modestly below the mark, and had really +some grounds for recommending our friends the classifiers to beware +what they asserted in this case. + +Talking of puzzling classifications, this is just the place for +mentioning the _batrachians_, who have been made into a class by +themselves, but who most distinctly belong to two classes at the same +time; not like the crocodile by details borrowed from each, but by a +fundamental change which takes place at a certain period in their +organization. The batrachians are in reality reptiles, but they are +reptiles which begin by being fishes, and real fishes too. + +If you have ever strolled about in the country, you must have often +come across those great pools of water which collect at rainy seasons +in the ruts of deep lanes. Amuse yourself by looking into them in +early summer, and unless the land is too parched and dry, the chances +are that you will see quantities of little black fishes, almost entirely +composed of a long tail joined to a large head, playing jovially in +the muddy waters, and looking as if they had dropped there from the +skies. These are young frogs--_tadpoles_, as we call them--and +they are beginning their apprenticeship of life. Enclosed in each side +of those great heads, they have gills, and they breathe in the same +manner as fishes. Presently the two hind feet begin to bud out and +grow, little by little; then the fore feet; finally, the tail wastes +away till it disappears; and thus insensibly the tadpole is transformed +into a frog. Observe here that the tadpole's gills share the same fate +as his fish-tail; they wither and disappear by slow degrees, and +gradually as they do so, his lungs are developed. The animal changes +his class very quietly, and without ceasing to be genuinely the same, +although it would be impossible at last to recognize the old individual +in the new if you had not heard its history beforehand. This is one +of the most striking exemplifications I know of the mysterious process +by which nature has insensibly raised animals from one class to another, +always improving upon her original plan without ever abandoning it. + +On the shores of certain subterranean lakes which exist in Carniola, +a country subject at this time to Austria, there are to be found +batrachians far more ambitious than our frog--namely, the _proteans_. +These cumulate rather than change: they become reptiles without ceasing +to be fishes, if I may so express it; they develop lungs as they grow +up, and yet keep their gills. I could tell you a thousand other +particulars about these batrachians if I were to examine them all in +succession; for it is a very motley family, in the bosom of which the +transition from reptiles to fishes is in some imperceptible manner +accomplished; from the frog, which the unanimous consent of mankind has +always ranked among reptiles, to the axolotl or siren, who lives in +Mexican lakes; and who, feature for feature, is exactly like a carp, +with four little feet fastened under him. To be quite in order, the +batrachians ought to have followed the reptiles, for their interior +organization is the same; but how could I tell you about their gills +without explaining that there was air in the water? and I did not want, +for the sake of these intruders, whose babyhood-gills only just appear +and disappear, to rob the history of the fishes of its most interesting +points. + +Let us be satisfied, then, with this passing glance at a dubious class, +whose history is only a repetition of two others, and let us return +to our friends the fishes. We have seen how they breathe, now let us +look how they eat. + +The modifications of the digestive apparatus are endless among fishes. +The lampreys, who are placed in the lower ranks of the class, carry +out to its fullest extent the type which we have already seen indicated +in the serpent. The digestive tube is quite straight, without any +perceptible swelling, and does not even go the whole length of the +body. It comes to an end at some distance from the tail. Among some +fishes an odd tendency begins to display itself, which we shall meet +with again farther on. The digestive tube, after going downwards towards +the bottom of the body, as we have seen it do so constantly hitherto, +doubles back, and comes up again to the throat, under which it empties +itself. In most cases the stomach is distinct; but it assumes a thousand +different forms; as if nature had wished to try her hand in all sorts +of ways in the construction of these imperfect vertebrates, before +adopting the definite model which was to serve for the others. + +The liver is enormous, and generally contains a great quantity of oil, +the taste of which you will know if you have ever swallowed a spoonful +of cod-liver oil; but in most fishes its old companion, the +_pancreas_, has disappeared. In its stead you will find, close +by the outlet of the pylorus, the open ends of certain small tubes, +which are shut in at their upper extremity like a "blind alley," and +through which descends into the interstices a thick glairy fluid, given +out from their sides or walls. The result is the same, you see, although +the organ is different; and, remarkably enough, these little tubes are +wanting among fishes, which, like carp, have a species of salivary +glands in their mouths, of which the others show no trace; from which +one may fairly conclude that these glands and tubes mutually supply +each other's places. Here, then, you see an instance of the light which +different animal organisations throw upon each other when they are +compared together. In fact, this one establishes pretty clearly the +real office of the pancreas in the higher races, exhibiting it to us +as an internal salivary gland, intended to complete the work only begun +by those in the mouth, in the case of lazy people who swallow their +food too quickly. + +There is the same diversity in the mouth as in the intestine. Some +fishes, like the skate, have no tongue at all. Others, instead of a +tongue, have a hard dry filament, very nearly immovable, and which one +would think was put there like a stake, to show the place where the +tongue is to be found in the more perfect organisations. There are +even fishes, like the perch and the pike, whose tongue is furnished +with teeth, or rather fangs; an evident sign that it has forfeited the +confidential position occupied by your own good little porter. You +must know also that the perch and the pike, like many other of their +fellows, have teeth all over the mouth. This invasion of the palate +by teeth, which began in the lizard and the serpent, assumes alarming +proportions here. It is not merely the roof of the palate which is +spiked with teeth: above, below, at the sides, everywhere to the very +limits of the oesophagus, the little fangs triumphantly stick out their +slender points. It is impossible, therefore, to state their number. +Nature has scattered them broadcast without counting, just as she has +done with the hairs of the beard round the human mouth; and the +comparison is not so impertinent as you may think. They sometimes form +an actual internal beard, even thicker than our outer one, and which +sprouts from the skin into the bargain. There is one fish whose teeth +are so delicate and so close together that, in passing your finger +over them, you would think you were touching velvet. This does not +refer to the shark, mind. His teeth are sharp-cutting notched blades, +hard as steel, arranged in threatening rows round the entrance of his +mouth, and cut a man in two as easily as your incisors do a piece of +apple. Others, such as the skate, have their mouths paved--that is the +proper term--with perfectly flat teeth. The first time your mamma is +sending to buy fish beg her to let you have a skate's head to look at. +You will be interested to see the small square ivory plates laid close +adjoining each other, like the tiles of a church floor. It is in fact +a regular hall-pavement, over which the visitors glide untouched, and +are then swallowed down in the lump; thus entering straight into the +house without having been stopped by the inscription nature has placed +over your door and mine--"Speak to the Porter." + +But all this is nothing compared to the lamprey's entrance-hall, which +differs from ours in quite another way. The lamprey, as I have already +told you, ranks almost lowest among fishes, and consequently among +vertebrate animals, of which fishes form the rear-guard. Indeed, it +is almost stretching a point to consider her worthy to bear the proud +title of a vertebrate at all; for the vertebral column, so clearly +marked in other fishes, where it forms the large central bone, is only +faintly indicated in certain species of lampreys, by a soft thread (or +filament), which is rather a membrane than a bony chaplet, and at the +top of this mockery of a vertebral column is the creature's mouth. If +you ever had leeches on, you will remember the sharp sting you felt +when the little beasts bit you. Well, the lamprey feeds herself just +in the same way as the leech does. Her mouth forms a completely circular +ring, which sticks to the prey, and through which runs backward and +forward a small tongue armed with lancets. This darts out to pierce +the skin, and draws in the blood as it retreats. Round your lips well; +dip them so into a glass of water, and draw back your tongue, and you +will at once feel the water rise into your mouth. It is by a similar +sort of proceeding that leeches relieve people of the blood they want +to get rid of; and in the same way the lamprey draws out the blood of +the animals upon which she fastens. + +What a long way we have come already! How very far we find ourselves +here from the little mouths we first talked about as chewing their +eatables so prettily! With the lamprey we bid adieu to the class +Vertebrata--the nobility of the animal kingdom--among whom nevertheless +we must distinguish between the peer, who approaches nearest the person +of his sovereign, and the inferior provincial lords who live at a +hundred miles' distance. There is only one step from the lamprey to +the _mollusks_ or soft-bodied animals, and this is the course +which animal organisation seems really to have taken in its progress. +But nature never moves forward in a single straight line. In passing +from the mollusk to the fish to get thence to the higher vertebrates, +she turned aside in another direction toward a class of animals which +rises far above mollusks, but which leads to nothing beyond. + +One would think there had been a check here, as if the creative power, +having discovered that it was going in a wrong direction, had retraced +its steps; if it be allowable to apply common ideas and expressions +to our conceptions of that Great Intelligence which has arranged the +plan of the mysterious ladder of animal life. + +The animals we must examine next, on account of their superiority to +the rest, are insects. Small as the ant is, it would not be right to +let her be preceded by the oyster. + + + +LETTER XXXVII. + +INSECTA. (_Insects._) + +Before speaking of insects, my dear child, it will be necessary, in +the first place, to tell you to what primary division they belong and +on what characters this division has been established. And here I find +myself in a difficulty. We have been but too learned already, and now +we run the risk of becoming still more so, if we commence an attack +on the three primary divisions which follow the vertebrates. We shall +have to encounter terrible names and tedious details, besides having +to take into account a thousand things of which we have not yet spoken. +We are going on quietly with the history of the feeding machine which +occupies the middle of the body, and learned men never looked in that +direction for the establishment of their divisions; between ourselves, +it was not accommodating enough. They have fallen back upon the +locomotive apparatus (_movement machine_) which affects the body +all over, and which they have proclaimed to be the leading feature of +the animal organization, without noticing however that it is, after +all, but the servant of the other. It is true that the great divisions +are more easily established upon this point than the other, because +the differences are more decided. It separates what the other unites, +and thus it is that nature carries on that beautiful combination which +the Germans have so accurately named "_Unity in Variety_" that +is to say, she is always at work, as I have already told you, on the +same canvas, but always embroidering it with a different pattern. +Wait! I have something to promise, if you are very good, and if this +history (that of the feeding machine) should have given you a taste +for inquiry. I will tell you another time the history of the movement +machine, and there the classification of our learned men will come in +naturally very well. In the meantime we will do as they do, and just +shut our eyes to their divisions, in which the feeding machine can +have no interest, because they were established without reference to +it. We will content ourselves, then, without further pretension to +science, with modestly examining the last transformations of our pet +machine in the principal groups of the inferior animals; of which +groups I will now tell you the names in their proper order. They are +as follows: Insects, Crustaceans, Mollusks, Worms, and Zoophytes. You +must take these names on trust; those which you do not understand will +be explained in their places. + +1. _Insects._--I know not where it was I once read that there are +said to be something like a hundred thousand different species of +insects; and I verily believe this is not all. Of course we shall not +attempt to review the whole of this formidable battalion. Let us take +one of those you are most familiar with--the cockchafer, for +instance--and examine what goes on in his inside. The history is nearly +that of all the others. + +"Fly away, cockchafer, fly!" says the song; and surely it is a bird +that we have here, and a bird which will appear to you even more +wonderful than those of which I have already spoken, when you have +considered the simplicity, and at the same time the strength, of his +organization. His mode of flight is rather lumbering, it is true; he +is, in comparison with the large flies, what the ox is to the deer; +but when you contrast the weight of his thick body with the delicacy +and narrow dimensions of the two membranes which sustain him in the +air, you may well ask yourself how those little morsels of wings, thin +as gold-beater's skin, can carry such a mass along. In fact, they only +accomplish this feat of strength by dint of an excess of activity +almost startling to think of. When you run as fast as you can, how +many times, think you, do you move your legs in one second? You would +be somewhat puzzled to say; and so should I: but I defy you to count +ten. Now the bird makes his wing move much oftener when he beats the +air with rapid blows as he flies; but even he does not strike a hundred +strokes in a second: and what is this to the feats of the cockchafer's +wing? It is not hundreds but thousands of times that he flaps his wings +in a second; and here let me hint, by-the-by, that when people seriously +wish to find out a method of travelling in the air, they will lay aside +balloons, of which they can make nothing in their present condition, +and will set to work to fabricate machines with wings which shall beat +the air as fast as those of the cockchafer. This sounds extravagant, +but I have seen an electric pile fixed in a stand with glass feet, +which caused a little hammer to beat thousands of times in a second: +and surely the hammer could have been made to communicate its movement +to a small wing! Forgive me this little castle in the air! The idea +came into my head a long while ago, and the cockchafer has just reminded +me of it. I will not, however, pursue the subject, neither will I offer +to explain the method used for counting the beats of an insect's wing. +That would carry us farther than would be desirable. + +To return to our little animal. I leave you to imagine the enormous +amount of strength required for such precipitate motion. We have spoken +of the rapid course of the blood in birds during flight: who shall +calculate its comparative rate in this fabulously wonderful locomotive, +the cockchafer? And if we lift up the cuirass which encases it, what +do we behold? Not a single trace of all the complicated +circulation-apparatus you have learnt to know so well; neither heart +nor veins nor arteries; only a quantity of whitish liquid, equally +distributed throughout the whole internal cavity. Not a trace of lungs, +nor any apparent means of renovation for this seemingly motionless +blood; for blood it is, in spite of its color, or, at any rate, blood +in its first stage of formation. It also has its globules--ill-formed, +it is true, and altogether in balls--like those found in the chyle +with us; which chyle, be it observed, is the same color as the blood +of insects, and may also be considered blood in its apprenticeship. +By what magic, then, is this raw, imperfectly-formed steward, who seems +altogether stationary, enabled to accomplish exploits which would +stagger his higher-bred compeers, agile and perfected as they are? +Where does he pick up the oxygen necessary for such repeated movements, +it being an established fact that no animal can move at all without +consuming oxygen, and that the quantity consumed is in proportion to +the rate of motion? Look under his wings for an answer. There, all +along his body, you will observe a number of small holes, pierced in +a line, at regular distances, and furnished with shutters of two kinds. +They are the mouths of what are called _tracheæ_, or breathing +tubes: and from them branch out a multitude of little canals, which, +spreading in endless ramifications through every part of the body, +convey to the whole mass of the blood, from all directions, the air +which makes its way into them through the tracheal holes. In this case, +you see, it is not the blood which seeks the air, but the air which +seeks the blood; whence arises a new system of circulation, whose +action is all the more energetic because it is unintermitting, and +makes itself felt everywhere at the same time. A little while ago we +were wondering at the twofold respiration of birds; yet this is far +less surprising than the universally-diffused respiration of insects, +who may well be able to do without lungs, seeing that their whole body +is one vast lung in itself. + +For the rest, do not trust to appearances, nor imagine that the blood +of our friend the cockchafer in reality remains motionless around the +air-tubes, idly drinking in the oxygen which is brought to it. Though +not flowing in enclosed canals, it is not the less continually displaced +by regular currents, which sweep through and renew this apparently +stagnant pool. Nor is this the only instance of such a current presented +to us by nature. + +Guess, however, if you can, where you will have to look for the +counterpart to the circulation of the cockchafer. In ocean itself! +But, remember, nothing is absolutely little or great in nature, who +applies her laws indifferently to a world as to an atom. The blood of +our world is water, which contains in itself all the germs of fertility, +and without which, as I have already told you, life is impossible +either in the animal or vegetable kingdom. The water of brooks, streams, +and rivers, flows along in channels, which, when figured in a map, +present to the eye of the beholder an exact picture of the system of +circulation found in the vertebrated animals. But the waters of the +sea are borne along, like the blood of insects, by a secret circulation, +which cannot be represented on the map; _i.e._ by immense currents +everlastingly in action, some on the surface, some in the mid-heart +of the ocean, which drive it in ceaseless course from the equator to +the poles, from the poles to the equator; so that the Supreme +Intelligence, in His overruling providence, has ordained the same law +to set in movement the immensity of ocean, and to effect circulation +in the cockchafer's few drops of blood. In the latter we find the +moving agent to be a long tube, which runs the whole length of the +back, and is called the dorsal vessel (from the Latin _dorsum_, +back). I told you that the cockchafer had no heart under his cuirass, +but I spoke too hastily. The dorsal vessel is a _true heart_, but +a heart devoid of veins or arteries, and thrown into the midst of the +blood. It dilates and contracts like ours, sucks in the blood by means +of side-valves, which act as our own do, and drives it back again into +the mass by that valve at its extremities, which opens near the head. +From thence arises a continued to-and-fro movement, which sends the +blood from the head to the tail, and brings it back again from the +tail to the head. But who would recognise, in this simple primitive +organisation, where all seems to go on of its own accord, as it were, +the same machine, with all its complicated movements, that we have +been so long considering? + +Well, in this apparently universal shipwreck of all the organs we know +so well, there is yet one which survives, and remains the same as ever, +namely, the digestive tube. I began by saying the insect is a bird. +His digestive tube is formed upon the same pattern as that of birds, +so that naturalists have bestowed the same names on the various parts +in each of them. After the oesophagus comes a crop (_jabot_), very +distinctly indicated; then a gizzard with thick coats, in which the +food is ground down. The hen, if you remember, swallows small pebbles, +which perform in her gizzard the office of the teeth in our mouths. +The cockchafer has no need to swallow anything. His gizzard is furnished +with little pieces of horn; real teeth, fixed in their places, which +have a great advantage over the chance teeth picked up at random by +the hen. I pointed out to you in birds, between the crop and the +gizzard, a swelling or enlargement of the digestive tube, pitted with +small holes, where the food is moistened by juices. The same enlargement +is found here, covered all over with a multitude of small tubes, which +might easily be mistaken for hairs, from which also falls a perfect +shower of juices. The only difference is, that it comes after the +gizzard, instead of before it, as in birds. Some naturalists, +considering that the manufacture of chyle takes place here, have called +it the _chylific ventricle;_ [Footnote: The corresponding +protuberance of the birds bears a name, somewhat similar, but stillmore +barbarous. I had passed it over in silence, because, I make the +confession in all humility, I do not understand it; but a remorse now +seizes me: it is called the _Ventricule succenturie._] a somewhat +barbarous name, but one which explains itself, and might with truth +be applied to the _duodenum_ of the higher animals. Bile is poured +in close to the hinder end of it, but you must not look for the liver; +it has disappeared, or rather its form is entirely changed. You remember +what the _pancreas_ had become in fishes; _i.e._ a row of tubes giving +out a _salivary fluid._ Such is exactly the appearance of the liver in +the cockchafer. + +Instead of that fleshy substance on which hitherto the office of +preparing the bile had devolved, you see nothing but a floating bundle +of long loose tubes, which, opening into the intestines, pour in their +bile. The organ is transformed, but we recognise it again by the office +it performs, which continues the same. As to the _pancreas_ it is +wanting here, as in the fish with salivary glands; but in its place +in many insects other tubes, acting also as glands, pour saliva into +the _pharynx; i. e._, the cavity at the back of the throat. + +As you see, therefore, everything is found complete in this tube of +a few inches long; and you can also distinguish there a small and a +large intestine. We are speaking of the cockchafer, which feeds on the +leaves of trees; and it is for this reason I name some inches as the +length of the digestive tube. This would not be longer than the body +itself, had it been destined, as in the case of many other insects, +to receive animal food. In fact, the law which we have shown to exist +with regard to the ox and the lion, rules also over the insect-world; +and whilst a radical change seems to have been made in the rest of the +organisation, here everything is in its place, and we find ourselves +in the same system. + +Was I not justified in asserting that the unity of the animal plan is +to be found in the digestive tube? and that this is the unchanging +basis upon which the Creator of the animal world had raised his varied +constructions? + +How would it be, then, if we were to take the insect from its +starting-point when it is only a worm, that is to say, merely and +simply a digestive tube? for I am only telling you a small portion of +its history here; a history you must know, which reveals a miracle +still more wonderful than the transformation of the little tadpole +into the frog! There is a brilliant-colored fly which comes buzzing +about the meat-safe--the bluebottle--do you know her? It is on her +account that we put large covers of iron wire over the dishes of meat; +but, perhaps, you never troubled yourself to think why. + +But the truth is, she only comes there to deposit her eggs in the good +roast-meat; and if she could get near enough to do so, you would soon +afterwards see it swarming with little white worms, which would entirely +take away all your appetite. These worms are only flies out at nurse, +and they will find their wings by-and-by if you only give them time +enough. Disgusting as they may appear on a dining-table, I assure you +they deserve more interest than you may think. When we come to speak +of worms, we will ask of them to let out the secret of the mysterious +transformations of animals. + +In the meantime, let us finish the observations we were making on the +_perfect insect_, as this little creature is called when he has +passed through the intermediate stages which separate him from the +undeveloped condition. Forgive me, my dear child, here I am speaking +to you as if you were a grown-up woman! This is because it is so +difficult to explain things of this sort in any other way. And now +that you have been introduced into the midst of the wonders of creation, +you ought to familiarise yourself with the ideas and terms they have +suggested to mankind. I began with you as a child, and great would be +my triumph if I could leave you a grown-up girl! And I flatter myself +that I have so far set your brain, to work, under pretence of amusing +you, that this hope is not altogether unfounded. I found it necessary +to say this to you in confidence, because I have just read over our +first conversations, and perceive that I have insensibly put you on +a different diet from the one I began with. I am obliged to comfort +myself by remembering that you have grown older since, and that you +are now acquainted with a great many things which you had never heard +spoken of then. And this is the secret of all transformations. We crept +on at first over ground that was quite unknown to us; but as we went +along, our wings must have begun to grow, and we are now able to fly +a little! + +Do not be afraid, however; I will exercise your tiny butterfly-wings +very carefully just at present. We have only to examine what becomes +of the _chyle_ of the cockchafer after it has been prepared in +the pretty little tube so finely wrought. We men have _chyliferous_ +vessels which draw up chyle from the intestines and throw it within +a short distance of the heart, into the torrent of blood, where its +education is completed. But the cockchafer, who has no other vessels +than his air-pipes, and the _dorsal tube_, which has no communication +with the intestines, what is he to do? Do not distress yourself about +him. Make a tube of a bit of linen, well sewn together, and fill it with +water. Sew it together as firmly as you may on all sides, the water will +have no difficulty in escaping through the meshes. And this is just what +happens with the little tubes found in animals, the coats of which are +formed of interwoven fibres. By-the-by, from thence comes their name of +"_tissue_," which they share in common with all the solid substances of +the body, for all were once supposed to have the same general structure. +The intestine of the cockchafer floats, did I not say? in the lake of +blood which fills the whole cavity of the body. Well, then, the chyle +has only to penetrate through these coats, to go where it is wanted. +Hence it is not at all surprising that this blood should be white; and I +have very good reasons just now for comparing it to our _chyle_. It is, +indeed, chyle arriving directly from the place of its manufacture, +without undergoing any other process; by which you may see that this +little machine (of the digestive organs of the cockchafer), though +differing in appearance so entirely from our own, is reducible to the +same elements of construction, and that life is maintained by the same +process as with us; namely, by the action of the air upon the albumen +extracted from food. The cockchafer, it is true, is much further removed +from being a fellow-creature of ours than even the horse; but the +principle of life is the same with him as with us. And this is quite +enough to cause children, who can feel and reason, to think twice before +they begin to torture, by way of amusement, a creature whose life the +God of goodness has subjected to the same conditions as our own. I speak +this to those miserable little executioners who make toys of suffering +animals: but the case is different with agriculturists, who have +necessarily to contend with the devourers of their harvests, and whom, +I admit, it would not be reasonable to bind down by the maxim of Uncle +Toby. + +[Footnote: I have introduced my Uncle Toby, who really has nothing +to do here, in order to make you acquainted with a few lines of Sterne, +which I wish I could place before the eyes of every child in the world. + +"Go!" said he, one day at table, to an enormous fly which had been +buzzing around his nose and had cruelly tormented him all dinner time. +After many attempts, he finally caught him in his hand. "Go! I will +not do thee any harm," said my Uncle Toby, rising and crossing the +room with the fly in his hand; "I would not hurt a hair of your head. +Go!" said he, opening the window and his hand at the same moment, to +let the fly escape; "go, poor little devil; away with you; why should +I do you any harm? the world is certainly large enough to contain both +of us!"] + +But now to finish with the cockchafer. We have got to examine one very +important part of his body, that which in other animals has been the +one most talked about ever since we began our study: I mean the mouth. +You know that this is the essentially variable point in the digestive +tube; so that you will not be much surprised, should we find he has +something altogether new. The mouth of the cockchafer is composed of +a great number of small pieces placed externally round the entrance +to the _alimentary canal_; but the names of these, as they would +not interest you, I will not enter upon with you; more especially as +they refer to such tiny morsels, that you would have great difficulty +in finding them again on the owner. Of these pieces only two are worth +our attention. These are two bits of extremely hard horn, placed one +on each side of the animal, which are called "_mandibles_" and +which serve the cockchafer to cut up the leaves which he eats. Fancy +your share of teeth being two huge things fixed in the two corners of +your mouth, each advancing alone against the other till they meet under +the nose! You would then attack your tarts with the weapons of the +cockchafer! You would not, however, be able to bite them straight +through from the top to the bottom, as is done by all the animals whom +we have yet seen. It is this which so peculiarly distinguishes the +insect's manner of feeding; for we have already been taught by the +bird and the tortoise, that it is possible to eat with two pieces of +horn. The cockchafer now shows us how to eat sideways; but this is +merely an accessory detail. It does not affect what happens after the +mouthful is swallowed. All insects, however, have not this peculiarity. +The cockchafer belongs to the category of grinding insects as they are +called, who bite their food: but there is the category of the sucking +insects (or suckers), whose food consists of liquids; and these insects +are furnished in a different manner. + +In the innocent butterfly, who lives on the juice of flowers, the +digestive tube terminates externally in a sort of _trunk,_ twisted +in several convolutions, which is nothing more than an exaggerated +elongation of the two jaws, which become hollow within, and form a +tube when joined together. When the insect alights on a flower, he +suddenly unrolls this trunk, and sucks in the juices from the depth +of its "corolla," as you would drink up liquid with a straw from the +bottom of a small vial. Amuse yourself some summer's day by watching +a butterfly in his labors amongst the flowers: sometimes he stops +still, but oftener he is contented to hover over them; and, as he does +so, you will see a little loose thread, as it were, move backwards and +forwards as fast as possible: this is his trunk, which he darts out, +while flying, into the corolla of the flowers, but which scarcely seems +to touch them, so delicate is its approach. + +Less inoffensive far is the trunk of the mosquito-gnat, and of all the +detestable troop of blood-sucking flies. It is always a tube; but this +tube is no longer a simple straw, but a sheath furnished with stilettos +of such exquisite delicacy and temper, that nothing is comparable to +them; and these, as they play up and down, pierce the skin of the +victim, like the lancets of the lamprey, and, like them, draw in blood +as they retreat. + +Finally, amongst the _parasites,_ the last and lowest group of +insects, the stiletto-sheath is reduced to the size of a kind of little +tube-shaped beak, which, when not in use, folds down like the fangs +of the rattlesnake. + +You do not know, perhaps, what a parasite is. The word comes from the +Greek, and signifies literally, "_that which moves round the +corn._" The Greeks applied it to those shameless paupers who, to +escape honest labor, made their way into the houses of the great, and +enjoyed themselves at their expense. These parasites are little animals +which settle themselves on large ones, to suck in, without having +worked for it, the blood which the others have manufactured. The wolf +hunts, fights, and tears its victim in pieces; and then, by means of +that interior labor which I have spent so much time in describing, +transforms it into nourishing liquid: and when all this is accomplished, +the little flea, who lives hidden among his hairs, coolly draws out +for his own use the valuable blood obtained with so much effort. There +are many parasites in the world, my dear child--yourself, for instance, +to begin with--who are perfectly happy to chew your bread without +asking where the corn comes from which made it. But you have heart +enough to see plainly that this indifference ought not to last, and +that it is not honorable to go on living in this indefinite manner at +other people's cost only. + +You will some day have duties to fulfil, which you should accustom +yourself to think of now, in order that you may prepare yourself for +them beforehand, so that it may never hereafter be said of you that +you passed through the midst of human society, taking from it all you +needed, without giving it back anything in return, I advise you to +conjure up this idea when the time comes to leave off playing and begin +preparing to be of use. The sort of thing is not always very amusing, +I admit, but you must look upon it as the ladder by which you will be +enabled to rise from the degradation of a parasitical life. If you +were in a well, and some one were to let down a real ladder for you +to get up by, I do not think you would complain of the difficulty of +using it. It is for you, then, to consider whether you would like to +remain for ever in your present condition; for those who learn nothing, +who _submit_ to nothing, who are good for nothing, but to show +off and amuse themselves--these remain parasites all their lives in +reality, however little they may sometimes seem to suspect it. + +At your age, however, there is still no disgrace in the matter. God +shows us by the insects that little things are allowed to be +parasitical; but on this subject I must return to a point in the history +of animals which I touched upon before. I told you, in speaking of the +crocodile, that the perfect state of the inferior animals is found +represented in the infancy or less perfect state of those above them: +and I may say the same again with regard to insects. All the young of +the mammalia begin life as parasites, at least, as sucking animals: +for they all live at first on their mother's milk, which is nothing +more than blood in a peculiar state. But the name of parasite among +insects is generally confined to those which take up their abode on +the bodies of their hosts; though in common justice it might equally +well be applied to the gnat and his relations, who, when once full, +make their bow and are off, like the kitten when he has finished +sucking. Well, without meaning to find fault, if we descend to the +lower ranks of the mammals, we shall find among them many parasites +in the received sense of the word. You remember the pouch to which the +marsupials owe their odd name. The young kangaroo remains hidden for +months in the pouch of its mother, feeding continually all the time; +and it is then a strict parasite. During the four following months it +goes in and out, and strolls about between meals, like other young +ones of its class, and is then an animal at nurse affording thus a +twofold example of the tendency of the great Creator to repeat Himself +in His conceptions, here using for the infancy of the mammal the system +invented for adult insects--elsewhere repeating the butterfly in the +humming-bird, who may fairly be called a vertebrated butterfly, and +reproducing the gnat in the vampire-bat, which I look upon as an +enlarged and perfected revise of the original pattern, whence comes +the scourge of our sweet summer nights. + +And now, surely, I have said enough about these parasites, whose very +name, I suspect, will make you shudder after my impertinent application +of it. Never mind: it depends entirely upon yourself to get rid of +whatever you find humiliating in the position I have hinted at. Do all +you can to bring happiness to the parents on whom you live at present, +and who give their life-blood so willingly for your good. God has made +you very different from those little animals who have neither heart +nor reason to guide them. Do not be like them, then, in conduct. By +a little obedience and love--child as you are--you can pay them back +what you owe, and they will never complain of the bargain. + + + +LETTER XXXVIII. + +CRUSTACEA--MOLLUSCA. (_Crustaceans and Mollusks._) + +_Crustaceans._ + +Crustaceans consist of cray-fish, crabs, lobsters, and prawns, who may +be considered cousins-german of insects, among which more than one +naturalist has thought they ought to be placed. Like them they are +divided into _grinders_, having the same action of the mandibles; +and _suckers_, who are also parasites, and have tubular sheaths +containing stilettos. Mammals and birds are the victims of parasitical +insects; fishes have been reserved for the crustaceans, who do not +disdain also to fasten upon their humble neighbors, the mollusks; and +even among themselves the little ones settle down on the great. A few +live on land, but an immense majority in water, and seem destined to +represent, in the aquatic world, the aerial class of insects, from +whom, however, they differ in many ways. + +The first difference is in that stony crust with which they are +enveloped, like the cockchafer in his horny cuirass, and which you +must know well enough if you have ever eaten lobster. Wherever we meet +with horn in insects, we find stone in crustaceans. The jaws are stony, +and the teeth of the stomach also. They are constructed on the same +plan, only the materials are changed. + +The digestive tube is less complicated, and consists merely of one +large stomach, instead of that series of stomachs by which insects +approach the organisation of birds. On the other hand, if among some +of them the liver is reduced to simple tubes, floating loosely in the +body, as we have just seen it in the cockchafer among insects, these +tubes are generally so profusely multiplied, and press so closely +against each other, that they form a large compact lump--a true liver, +to sum up all--from which issues, as from ours, a _choledochian +canal_, a bile duct, _i. e._, which passes out into the intestine at the +entrance of the pylorus. + +You recollect that canal of the liver which I was afraid to tell you +the name of because it was so ugly? Well, this is that formidable name! +Now that you have swallowed so many others, you must be strong enough +to digest this. + +No chyliferous vessels have been found in crustaceans, whence one may +conclude that the chyle leaves the intestine by oozing from it, just +as it does in insects. There it gives rise to an almost transparent +sort of blood, a kind of sap, or lymph, which is put in motion by a +genuine circulation-apparatus; a real heart, with all its canals. This +heart has only one ventricle, and only sends blood in one direction, +as in the case of fishes; but there is an essential difference between +them, which we must point out. The heart of fishes may be called a +venous heart, since it only receives venous blood, which passes thence +to the gills, while that of crustaceans is an arterial heart. It +receives the blood directly it leaves the respiratory organ, and sends +it, not into one aorta, but into several arteries, which set out at +once, each in its own direction, to nourish the various quarters of +the body. This greatly resembles the system of circulation, with which +we are already acquainted. The veins only are unsatisfactory. They +form a kind of transition between the uncertain currents which convey +the blood of insects from one end to the other of the cavity in which +these strange organs lie bathed, and the closed canals of the higher +animals. But they are not canals, properly speaking. The irregular +intervals which separate the organs, more numerous here, are enclosed +by membranes, between which the venous blood pours, and naturally the +chyle also. The whole thus arrives at certain excavations formed at +the place where the legs are jointed on to the body--reservoirs, so +to speak--where the real canals come to carry it off and convey it +away into the gills. + +It is, in fact, by means of gills that crustaceans breathe in their +character of aquatic animals. These gills are made nearly upon the +same model as we have already seen in those of fishes; and although +their form and arrangement differ in different species, yet the +principle is always the same: they are tufts of leaflets springing +from stems, up and down which run two tubes; one which brings the blood +from the venous reservoirs, the other which carries it to the heart. +Crabs, lobsters, and crayfish, who are the "file-leaders" of the +crustacean tribe, have gills enclosed in the body, as fishes have; but +the circulation of the water goes in a contrary direction to theirs, +as does that of the blood. Instead of entering at the mouth and going +out at the sides, as we have seen, it enters at the edge of the bony +shell which covers over the body and comes out near the mouth--a merely +accidental detail which does not in any way alter the play of the +apparatus. All these animals are equally adapted for swimming and for +walking, crabs especially, their gills accommodating themselves without +difficulty to contact with the outer air, as we have seen among certain +fishes; so that one might class them with amphibians. There is even one +crab who has acquired the name of _land-crab_, because, although he has +got gills, he dies in water, the small amount of air he can get out of +it at a time being insufficient for him, and who, therefore, lives +constantly on land. It is true that he seeks out damp spots, for his +gills would also fail him if they became parched, and, like the fishes +who make excursions on dry land, he is provided with an internal +reservoir, which is always filled with a certain quantity of water. + +Some aquatic crustaceans have the labor simplified by external gills, +which hang down into the water, sometimes depending from the stomach, +sometimes from the legs. In France you sometimes see at a table certain +little animals, very like shrimps (_squillæ_), the bases of whose +hinder legs are fringed by slender tufts, which are in fact their +gills. They find themselves placed there just within reach of the +venous blood; for in the body opposite the bases of the legs are little +cavities in which it accumulates. Now these gills can only act when +under water, and so the squillæ dies as soon as he is removed from +that protecting element. For the same reason they cannot be kept long, +nor travel far, much to the regret of those who like them and live at +some distance from the sea. + +There are other crustaceans, next-door neighbors of the squilla, whose +gills are still more simplified. Here the legs themselves are turned +into extremely thin plates, which play the part of gills, and are thus +organs for two purposes, serving at the same time to swim and breathe +with. + +We have in our house one little crustacean, the only one I know of who +associates with men, and that is the wood-louse. You must know the +little grizzly beast, which rolls itself up into a ball whenever it +thinks itself in danger, and who would be taken for an insect by anyone +who was not taught otherwise. The wood-louse has neither gills hanging +down outside, nor anything inside her body which resembles the breathing +apparatus of her great relations. But, on examining her closely, you +will perceive all along her stomach a series of little plates, which +are her breathing-organs, and which come under the class of gills, +because, like other gills, they require a certain degree of moisture +to make them act properly. You will never, therefore, see a wood-louse +strutting about in the sunshine, where he would dry up far too quickly; +but if ever you get into a dark, damp corner, there you have every +chance of finding one. + +Animals who breathe through their legs and through their stomachs! You +are astonished, and ask, What are we coming to? What would you say, +then, if I were to go really to the depths of the crustacean world? +We should find there such extraordinary beings as you can form no +notion of, for they all live down below in the sea, and have no special +breathing-organ at all, inasmuch as they breathe through the whole +surface of the body. Do not exclaim yet! I will soon show you one whom +you know perfectly well, and who has no other way of breathing. + +But we must keep to the higher crustaceans, if we want to judge of the +class. By going too low, we run the risk of not seeing clearly. Animal +creation is here on a system of experiments: and they are so endlessly +multiplied, and exhibit such a profusion both of deceptive resemblances, +and of differences which disappear by transformations, that +classification no longer knows which way to turn. Worms, crustaceans, +mollusks; to which group do these and those belong? To which ever we +like to refer them, for these groups represent nothing definitely +determined in the plan of creation; and though easy to be distinguished +from each other in the higher branches, they become confused together +in the lower, like mountain summits which spring from a common base, +at the foot of which they are all united together. + +On this account, my dear child, you will, I am sure, excuse me now and +henceforth, from entering into details of all the horrible beasts which +swarm in the shallows of the animal world, and whom learned men have +in their wonderful wisdom muffled up in terrible names, in order to +prevent children from coming near them! What would you have thought +of the poor little squilla, so prettily baptised by the fishermen, if +I had taught you that it belonged to the order of _Stomatopoda_? +You will scarcely be able to pronounce the word; but that is no fault +of mine, it is spelt so. + +We will content ourselves, then, with having taken a glance at the +most clearly marked individuals; and as I said to you just now, it is +by them that we will arrange our inventory of the groups. Here, as you +may have already remarked, instead of continuing to wander from the +original model whose gradual deterioration we have been following all +this time from one class to another, it would seem that we are retracing +our steps, and regaining some portion of the lost ground. This is +because insects, as I have already stated, are an exceptional case--an +idea apart from the great general plan--a by-lane turning off from one +side of the great line of animal creation. + +The crustacean, less perfectly worked out than the insect assuredly, +but more regular, forms, so to speak, the connecting line between that +tiny masterpiece of fancy, so incomplete in its exquisite organisation, +and the shapeless but better constituted lump of the mollusk, who +conceals under his heavy shell the sacred deposit of real organs, those +which we expect to find always and everywhere. An insect outside, +though less refined it is true, a mollusk within, the crustacean reminds +me of what among us is called an _amateur_--that mild lover of +the arts who holds a middle place, as it were, between the artist and +the common citizen. + +I regret that you are not at present quite able to appreciate my +comparison fully: but put it by, in reserve, if possible, in your +memory; you will find out hereafter how just it is, and it will, +perhaps, help to prevent you from always setting the lively, noisy +artist, above the quiet and silent citizen. Let this, however, be +between you and me. If they could hear us talking, neither artist nor +citizen would forgive me, and the amateur still less. + +_Mollusks._ + +There is one mollusk universally well known--namely, the oyster--so +we will choose him for discussion. To look on one's plate at that +little mass of soft, compact substance, one feels inclined to ask what +there can possibly be in common between it and us; and if you were to +declare that there was not the faintest trace of resemblance between +the organization of the oyster and our own, I should not be surprised. +Wiser people than you have been caught tripping there; not that they +were ignorant of the points in which the oyster resembled us, but they +paid no attention to them. Viewing it in other respects, they declared +that it was of a structure completely different to our own; and that, +in the construction of this machine, the Creator had worked upon a +particular plan, laid aside afterwards as useless for any other purpose. + +I should like to get hold of one of those Academicians, with thirty-six +plans, and confound him before you, in proof of his relationship to +the oyster, by showing you at one sitting that there is an oyster in +himself; nay, further, that he is nothing but an oyster, revised, +amended, and considerably enlarged. And do not imagine that I am only +using a figure of speech here, as the professors of rhetoric call it; +which would be in bad taste: I am speaking literally, and to prove the +existence of the oyster in question in our Academician, I shall only +ask permission to perform a slight operation upon him. You exclaim at +this; but do not alarm yourself, for it is only an operation on paper, +he will not die from it. See now, I cut off his head, his two arms, +and his legs; I take out of his body the vertebral column and the ribs; +I gently place what remains between two shells; and ... there is my +oyster. I willingly admit that it is more carefully elaborated and +richer in details than its sisters in the oyster beds; but all the +principal organs are to be found in them also, and they positively are +beings of a similar construction: you shall judge for yourself. + +The mouth--for there is a mouth, though one must look closer than the +oystermen do to discover it--the mouth is exactly what the gullet +(oesophagus) would be in a man whose head had been cut off; that is, +a truncated tube. Then comes the stomach, situated in the very midst +of the liver; which latter may easily be distinguished, even by the +most cursory glance at luncheon, from its dark color. The intestine +also goes right through the liver, doubling backwards and forwards +several times: and thus the digestive tube supplies itself with bile +from the cask (to borrow a commercial expression); and this saves the +expense of a bile-duct (choledochian canal), which would be an +unnecessary mode of conveyance in this case. The animal lives in water; +consequently, instead of lungs he has gills: [Footnote: The land-snail +has lungs.] these are those thin, finely-streaked plates which make +a fringe at the very edge of the shell. Finally, on leaving the gills +the blood is received by an arterial heart, with only one ventricle +like that of the crustaceans, in the shape of a small pear, similar +to ours, having an auricle, and an aorta, branching out so as to +distribute the blood throughout the whole body. And now what do we +find here, let me ask you, in this mutilated man, reduced to the soft +portions of the trunk, whom I have been imagining? A heart, with its +arteries; lungs; a liver; an intestine; a stomach and an oesophagus: +that is to say, merely and simply the organs of nutrition. That is +all, or very nearly so. + +As you perceive, then, all the elements of our own feeding-machine lie +between the two shells of a mollusk; in a rough state as yet, it is +true; incomplete, and unruly; as in the case of the intestine, for +instance, which in many of these creatures passes without ceremony +through the heart: but even so they are quite sufficiently indicated +to prevent their being mistaken. Now this machine, it is in vain to +deny it, is the animal itself; but it lives at first, and it is this +which dies in it last. The other matter (the locomotive power), +important as it may seem to us in higher races, only holds a secondary +position in reality: the proof of which is, that here is an animal +reduced absolutely to a mere feeding-machine, who still lives, whilst +there yet remains to be found one who has nothing left but his +movement-machine, and who can yet exist. We cannot disown this primitive +animal, for we have it within ourselves; lost, so to speak, in the +midst of the accessory organs which are successively added to it in +proportion as we rise in the animal scale, but still preserving its +own life, its personality, if I may use the expression. Listen to this, +for here is a history well worth hearing. + +I will explain to you, hereafter, how all the actions of the +movement-machine are performed by means of a network of nervous threads +(filaments), whose centre of impulsion is in the brain. How our will +acts upon the brain, and gives its orders to the muscles through the +nervous fibres, I will not offer to explain: it is a fact, let that +suffice us. You say to your foot, "Forward!" and off it starts; "Halt!" +and it stops. Here is an organ under command, a servant of the brain, +where we rule ourselves: with or without explanation, no one will ever +dispute this. The oyster, who has neither head nor brain, has, as his +only instrument of action, certain little masses of nervous substance +scattered right and left, which are called _ganglions_. These +communicate with each other and with the organs by nervous cords, which +are interlaced in all directions, without having any common centre, +and which give the impetus to all parts of the animal. + +Well, the human oyster presents to us exactly the same nervous +organisation. It has its ganglions and its nerves to itself, which are +put into communication with the brain by some threads strayed among +his own, but which are not under its orders, and which treat with it +on equal terms. You remember, perhaps, the little republic talked about +when we first entered the digestive tube; you have now the explanation +of it. This republic is the original animal; it is the feeding-machine. +I cannot describe it, and the kingdom of which you are queen, better +than by comparing them to two States having diplomatic relations with +each other, who exchange dispatches and reciprocal influences; and as +to the importance of these respective influences, if one were to compare +them I scarcely know to which side the balance could incline. + +We shall return elsewhere to this detail, one of the most interesting +of our organisation, and which here finds its natural explanation. For +the present I will content myself with reminding you that, since the +earliest days of human civilisation, all philosophers, all poets, and +all moralists, whether sacred or profane, have borne witness to that +double life within us, that inward being, blind and deaf, whose +disordered impulses so often carry trouble into those higher regions +where will and reason sit enthroned. Behold him taken in his lair at +last, this mysterious being. I have just unveiled his origin to you. +And here, dear child, I must shelter myself behind a profession of +faith. There will not be wanting people to tell you that it is degrading +man far too much to look so low for the sources of his organisation, +and that this sentence--_the human oyster_--which expresses my +idea so well, is neither more nor less than blasphemy. Let them talk, +but adopt their opinion only when they have proved to you that man had +a special Creator, and that the oyster came from a different hand from +ourselves. I should like to know with what face we could venture to +complain, poor worms that we are, because it has seemed good to our +common Father to carry forward in us his previous creations, and in +what respect human dignity would suffer from this contact with a being +who, like us, is one of the works of God. That human pride may suffer +thereby, I admit, and I am glad it should; but if God has included all +creation in His love, we may well include it all in our respect. Whence +comes our superiority at all, but from the gratuitous gifts of Him who +has made us what we are? Is it to lose it, then, to find ourselves +side by side with inferiors whom the Divine benevolence has visited +like ourselves? Surely not. But enough of the oyster, who has never, +that I am aware of, heard such strange discussions sounding in his +ears before. I have no time nor courage now to speak of the other +mollusks, who offer more or less the same system of organs which I +have just described. I must hasten on to the Worms, who give us the +last clue to the great enigma of the animal machine. + + + +LETTER XXXIX. + +VERMES--ZOOPHYTA. (_Worms and Zoophytes_). + +_Worms._ + +The worm of worms, the one you know best, is the earthworm: so he shall +have the honor of representing his group. + +He will not take much time to describe. He is, in brief, a tube, open +at both ends, so as to allow food to come in and go out. That is all. + +I talked to you before about the ruminants, those food-manufacturers +who are employed in cooking victuals for the stomach, and in disengaging +albumen from the coarse materials among which it is apparently lost, +so as to give it out again in a more acceptable form. The ruminant has +other workmen under him, whom I keep in store for you as the last of +the eaters, and who prepare the raw material for him*. These are the +vegetables, who seek out the elements of albumen in earth, water, and +air, those final sources of all alimentation. The earthworm also is +a _preparer_, but in a peculiar way. Look along the garden-walks +in summer-time, after rainy weather: you will see here and there, +little heaps of earth moulded into small sticks, like dough which has +been passed through a tube. [Footnote: M. Mace's account of the +earthworm's life seems founded on the assumption that it extracts its +nourishment from the earth itself, i.e., from inorganic matter, as +_vegetables_ do, to use his own words. But this notion is so +entirely at variance with present received opinions, and also with the +fact that the animal possesses a gizzard for digesting, as well as an +intestinal canal, that it has been necessary to make considerable +alterations in the description. To dismiss his theory of the primitive +animal, etc., altogether, was, however, impossible, without omitting +the whole chapter; but as young heads are not likely to trouble +themselves about it, and it is very innocent in itself, it will do no +harm; subject to this warning, that M. Macé has taken the earthworm +for a more simply organised creature than it really is.--TR.] This is +the damp soil which the worm has passed through his tube, after +extracting from it, during its passage, the various elements of +fertility he requires for the support of his life. This is what makes +him so particularly fond of garden soil, because it is richer in animal +and vegetable matter than common earth, and proves therefore more +nourishing food. The worm, then, feeds on the fat of the earth, which +he converts into azotic aliment for the use of moles, hens and Chinese. +It only figures, it is true, for want of something better, in Chinese +cookery, so profusely hospitable for all that; but the hen doats upon +it, and you do not despise it yourself when it comes back to you in +the form of a chicken's wing, that second transformation of the matter +of which the soil of your garden is composed. It is told of certain +savage tribes, the victims of constant scarcity, that they swallow +little balls of clay in order to keep down their hunger; and during +the great famines in India the distracted inhabitants may, we are told, +be seen digging up the banks of the rivers to feed on the fertile clay +in which the splendid vegetation of their country is developed. This +is a desperate trial of that primeval system of alimentation which +answers perfectly with the worm, but becomes a cruel mockery in the +case of an organisation as exacting as that of man. Let us examine a +little more closely, then, this wonderful tube. + +At first sight one notices, to begin with, that it is composed of +perfectly distinct rings, all quite alike. Inside as well as out each +of these rings is an exact repetition of the other. They are all formed +of circular muscles, enclosed between two coats, which extend from one +to the other. A series of ganglions, arranged in the form of a necklace +along the whole length of the body, set in motion the muscular system +of the rings, each of which possesses its local centre of impulsion. +Each feeds itself in its place from the nourishing juices with which +it is in contact, the interior coat enjoying the double property of +distilling digestive juices and absorbing digested ones. These juices +pass through the muscular partition, and proceed to bathe the outer +coat, which plays, at the same time, the part of coat and lung, and +affords a passage to the air through its soft, damp surface, like that +of gills. From all this results a fine red blood, such as we have not +met with since we left the reptiles, and which is manufactured in all +parts of the body at once. + +Each of these rings, then, the worm's only organs, is a little eating +machine to and for itself, and at the same time a little movement +machine also; in fact, a complete animal. Each one could, if necessary, +nourish itself and live apart; and this is what he really does. Learn +hence, to despise nothing in nature. One tramples an earthworm under +foot, and there below one's heel lies a little revealer of secrets, +whose organisation throws the most unexpected light upon one of the +greatest mysteries in our own life. + +I said to you before, and I felt at the time that it was rather beyond +you, that "each one of our organs is a distinct being, which has its +particular nature and special office, its separate life consequently; +and our individual life is the sum total of all these lesser lives, +independent one of the other, but which nevertheless blend together, +by a mysterious combination, into one common life, which is diffused +everywhere, but can be apprehended nowhere in particular." + +The study of the worm admirably explains this out-of-the-way sentence. +And here observe my adjective--my out-of-the-way--for it is a case in +point. We may call it a literary worm; a worm of four rings, each +perfect in itself, but yet compounded together into a whole with its +own idea. + +That which makes this idea of life most difficult to comprehend is, +that one cannot prove it by a direct experiment, since there is not +one of our organs which could exist separately from the others. Although +independent in their special action, yet these multiplied lives are +nevertheless in a state of absolute and mutual dependence, from the +imperative need they have of each other to make them act, each having +for its share only one particular function, the effect of which extends +to all the others. This is called the division of labor; and if you +still do not understand me clearly, I will explain it in another way. +The heart sends to all the organs--does it not?--the blood, without +which they could not live: separated from the heart, the lungs would +die immediately. It is to the lungs the blood goes to find the air, +without which it could not maintain life. Separated from the lungs, +the heart would die immediately. There is nothing belonging to us which +can avoid the inexorable requirements of blood and air; +consequently, there is nothing which can live an isolated life. + +I will borrow a simile from human society which you will understand +at once. In civilised countries, where division of labor is established, +the tailor makes clothes, the mason makes houses, and the baker makes +bread. If you could throw them each alone by himself into a wood, the +mason would not be able to dress himself, the baker would sleep in the +open air, and the tailor would not know how to make bread. Or rather, +as not one of them can carry on his trade without the co-operation of +a multitude of hands, they could none of them do anything at all. Each +completely independent in his work, yet each dependent upon the others, +both for living, and even for being able to work, our workmen can only +act when they remain bound in close union with the vast society of +which they form a part; and our organs--those other laborers whom you +have seen working for so long--our organs are just in the same +predicament. But in the primitive societies, among savage tribes, where +each man can make his clothes, his house, his bread (when he has any), +and everything else for himself, you might take such an individual if +you liked, and separate him from the rest of the tribe, and he would +go on living as before. And so with the rings of the worm, that +primitive society of organs. Each of them is a universal workman, who +knows how to make everything. Separate him from his fellows, it will +not disturb him at all, and he will go on living as if nothing was +thematter. + +I still remember some profound reflections I indulged in one day some +years ago whilst leaning on my spade and looking at a worm that I had +just cut in two, and whose two halves were walking off one on each +side. + +"There was only one creature here just now," I said to myself, "and +now there are two! Have I had power, then, to create one with a stroke +of the spade?" + +I had not then got hold of the key which I now give you, and to which +no possible objection can be raised. If there are two beings after the +stroke of the spade it is because there were two before. Nay, there +were even many more, if we may trust to the "Manual of Zoology" by +Milne Edwards, a very good book, excellent for an old scholar like +myself, and which I have found very useful in my country-home, as it +has enabled me to relate to you one after another the mysterious wonders +of life. + +He says that, "if one cuts an earthworm across into two, three, ten, +or even twenty morsels, each of these morsels will go on living in the +same way as the whole, and will form a new individual." + +Twenty! that seems to me a great many, because, as far as I can trust +to my brief observations as a gardener, it is necessary that some of +the rings should remain united together and afford each other mutual +support, in order to succeed in repairing the bleeding breaches; but +I would much rather believe it than try the operation. My mind is easy +when I am defending the plants that I have sown in my garden from the +gluttonous worm who would rob them of their food; but it would not be +so if I were cutting them up on my table to learn something about them. + +Besides, there is no need of an operation to convince oneself of the +particular life of each ring. There is one worm, well known by name +at least, though happily not to be met with every day, and that is the +tape-worm, who establishes himself in the intestine of man, and lives +on the chyme, as the other worm does on garden-mould. They call him +the _Solitary_ worm in France; and if ever one might suppose a +creature appropriately named, it would surely be him; for certainly +there is not much society to be looked for in the dwelling he chooses +for himself! But it happens that this pretended _solitary_ worm, +with his unlimited chain of rings, is only a long row of perfectly +distinct beings, so distinct indeed that, from time to time, some of +the rings let themselves go, fall off like ripe fruit, and go away to +live elsewhere, ready to become the nucleus of a new set, if a happy +accident carries them into another intestine, the only place favorable +to their development. + +At last, then, here is a corner of the curtain raised; here we see the +associated organs which constitute an animal, living for once a life +positively and in all respects their own. We are now satisfied about +this; and when at another time we find them bound together in the +chains of a union too ingenious to be severed with impunity--which we +shall discover by seeing their action stop at the moment of +separation--we shall know the cause. + +Do not think, my dear child, that a wretched earthworm can prove nothing +as regards other creatures. The worm is the starting-point of all the +organisations which come after him. Of what is he composed? Of a +tubewhich is itself composed of rings. Well, it is upon this very tube +that the whole animal machine has been founded: and these rings, as +they expand and modify themselves in a thousand different ways, give +birth to all those varieties of being which drive classifiers to +despair, because they will not understand that there ought only to be +one animal, since there is only one Creator of animals. Now, this +animal is a digestive tube served by organs; it is a worm, _i.e.,_ +which goes on constantly embellishing itself. I said to you long ago, +and at a time when you scarcely knew anything, "Have you ever observed +a worm or a leech in motion? You see a successive swelling up of the +whole surface of its body as the creature gradually pushes forward, +as if there was something in its inside rolling along from the tail +to the head. Such is precisely the appearance which the oesophagus +would present to you as the food passes down it, if you had the +opportunity of seeing it in action; and this has been called the +_vermicular_ movement, in consequence of its resemblance to the +movement of a worm." + +And afterwards, in speaking of the intestine: + +"If your body were made of glass, so that you could look through it +to watch the intestine at work, it would appear to you like an enormous +worm, coiled up into a bundle, heaving and moving with all its rings +at once." + +You have now got hold of the secret, namely, that from the beginning +to the end of the digestive tube, its movements are those of a worm. +What a wonder! and that the worm is a digestive tube which can walk. +This worm, or this tube, whichever you please to call it, has never +ceased crawling under our eyes since we began this study. Lost sight +of in man in the midst of the riches he has picked up on his road, +invisible and coiled backward and forward in his palace like an Eastern +despot who leaves everything to be done by his slaves; behold him here +in his first stage naked, shivering in the air, forced to go off himself +and alone to his pasture--ground! But in the coarse earth with which +he fills himself I can already see the delicate chyme which his numerous +servants will prepare for him later on, and into which the heart-tree +will one day send down its roots--the chyliferous vessels. + +A short time ago I called the oyster the primitive animal, but I was +in too great a hurry. The worm is the real primitive animal. He is to +be found in the oyster, as the oyster is to be found in us; and that +poor little beast is, by comparison, an animal of high pretension, who +would be shocked, I am sure, if he could understand what we are saying, +and heard us assert that he is nothing but an embellished worm. + +_Zoophytes._ + +Two centuries ago it was believed that below the worm, animal life, +properly so called, ceased, and the creatures whom I am about to +introduce you to were supposed to be animated plants rather than living +organisms. Hence their name was especially chosen to express that +double nature by which they were thought to have a share in two kingdoms +at one time--viz., the animal and vegetable--_zoon_ in Greek +meaning animal, and _phuton_ a plant. Zoophytes were set down as +animal plants. + +And although later discoveries have long ago established the fact of +the complete animality of zoophytes, the old name is still in general +use. But you must not let it deceive you. Zoophytes are animals every +inch of them, however low in the organic scale, and although many of +the compound ones imitate the growth of plants and shrubs so exactly +in their mode of spreading that it is only by the closest observation +we can persuade ourselves they do not belong to the vegetable kingdom. +Of these there are the delicate buff-colored, prettily-branched, horny +specimens found on the shore, which make so beautiful a variety in +seaweed pictures among the red and green colors of the real seaweed; +but of these also are those wonderful stony shrubs which grow on the +submerged rocks of islands in warm seas, and the material which you +know so well by the name of coral--the very coral of which the necklaces +and bracelets in the jeweller's window are composed. + +In all cases of compound zoophytes, however, there is one great point +which they have in common with the worm, viz., that there is an +association of distinct lives acting unanimously; or, rather, to the +same end. Plainly as this is seen in the worm, it is still more obvious +in the zoophyte. There is no need here either of cutting them up +yourself or of taking other people's dissecting operations upon trust. +It is enough to use your eyes, with the help, it is true, now and then, +of the microscope's clearer sight. + +You know the old oak-tree which stands on the outskirts of the wood, +and is called among the country folk _the patriarch_? Now, this +is clearly not an individual, but a nation. It is not a tree; it is +a forest. Nay, may I not call it a green field? For this trunk, so +truly venerable from ages of growth that one feels inclined to bow to +it as one goes by, is, in fact, a collection of structures, accumulated +by countless generations of fleeting herbs, _i.e.,_ leaves, not +one of which has lived for the space of a whole year round. Every +spring some thousands and thousands of buds open to the sun; each one, +therefore, affording a passage to a little green point; and this point +is an oak, who comes into the world, like the first oak, the grandfather +who formerly came forth from an acorn, under the form of an herb or +tender leaf, which a sheep might have browsed upon. Yet it is so +thoroughly an oak, that you have only to take out the bud carefully +before it has expanded and fasten it into another one's place upon a +tree of the same family, though of a different species, and it will +produce an oak of the same sort as its old companions, and which will, +as it progresses, look quite a stranger among the indigenous branches. +This is the secret of what the gardeners call _grafting_, and I +advise you to try the operation upon rose-trees, for nothing is more +amusing. When the autumnal frosts set in, all these troops of new +little oaks die, and deliver up their leaves to the wind; but they +leave behind, as their summer's work, a tiny morsel of new wood, upon +which, if you look carefully, you will see a fresh bud dawning--the +hope of the coming season. And thus the great life of the tree is +perpetuated from century to century by an uninterrupted succession of +transient lives, reminding one in all respects of the life of a nation; +and the similitude is complete in the evergreen trees, where the new +leaf makes its appearance before the old one has quitted the stem. + +And such is the life of the great stone trees and shrubs of various +kinds which grow under tropical seas, and whose makers and inhabitants +are the coral polyps, the undoubted heads of the Zoophyte race. + +But before considering the _polypidom,_ or external dwelling +(otherwise called the _coeneciun,_ or "common house"), you must +learn something of its originator, the little _polyp,_ who lives +inside, and belongs to a family so widely spread over the face of the +earth, that there are scarcely any waters, whether salt or fresh, +without them. + +In your own neighborhood, if you know how to look for them, are to be +found on the banks of ponds, or along the borders of streams which lie +sleeping in roadside ditches, extraordinary beings which, a hundred +years and more ago, completely bewildered the good Dutch naturalist +Trembley, who had taken it into his head to study them. Picture to +yourself some very tiny bags made of a kind of jelly; gray, brown, or, +most commonly of all, green in color, always transparent, and fastened +by their base to the stalks of _carex,_ water-lentils, or the +confervas, which grow in still water. A hunter on the watch, this bag +shoots out on all sides a number of slender threads, like so many +whip-lashes, arranged within a circle round the edge of its opening +or mouth; and with these whip-lashes all the animalcules which come +within reach are entwined, stifled, and carried away to the ever-yawning +little gulf, where they are digested in less than no time. Whatever +will not digest comes out afterwards by the way it went in. Of what +becomes of the results of this digestion it is impossible to form an +idea. Were you to cut up the bag and put little morsels of it under +the best microscope possible, you would see positively nothing but +solid jelly, without the least sign of any organisation whatever. But +this is not all. Replace these morsels in the water, and come back +tolook at them at the end of five, twenty, or thirty hours. Each one of +them will have become a perfect bag, ready to multiply itself afresh +if you submit it to the same operation. Sometimes, on some part of the +original bag, there suddenly appears a little raised spot, like that +which came on your baby brother's arm the other day after he had been +vaccinated. What would you have said, if this ugly spot had grown +larger and larger without stopping; if it had assumed legs, arms, and +a head, and so become another baby, growing from the arm of the first +one? Yet this is just what the spots do which come on the bag I have +been telling you of; and people have come across bags of a larger +species still--between one and two inches in size, in fact--which in +this way carried twelve young ones on their backs, if one is allowed +to talk of stomachs having _backs_. You perceive at once that +this commencement of animal life is not even a digestive tube, and +that nothing in it can be found but a stomach, opening straight to the +air above and closed up below. + +It was Réaumur, the originator of the famous thermometer, who gave a +name to the wonderful bags discovered by Trembley. Aristotle had +previously bestowed the title of _polypus_ (many feet) upon a +mollusk outwardly formed upon a similar model [Footnote: This is the +cuttle-fish, called _polypus_ by old naturalists. We shall speak +of it fully hereafter in the history of the movement machine.] with +large whips disposed regularly in a circle round the mouth, and intended +for a similar use, only that they have another function besides; that +of carrying the body along in the capacity of feet by clinging on to +the rocks with their suckers as they go. Réaumur transferred this name +to the newcomers, and called them fresh-water polyps, to the infinite +amusement of Voltaire, who had declared that they were only blades of +grass; a new proof, among many others, that in natural history all the +intellect in the world is not worth a pair of good eyes. + +But it was soon found out that, in collecting these bits of living +jelly near the Hague, Trembley had laid his hands on little beings of +immense importance on the surface of the globe, and that he had +discovered under his microscope the explanation of a mystery which had +spread itself, setting human science at defiance, over some thousands +of square miles. + +I talked to you just now of the jeweller's coral, of which ornaments +so becoming to dark-haired people are made. That is one of the stony +polypidoms I spoke of as stone trees found at the bottom of the sea, +where it grows attached to the rocks in the form of a charming little +shrub, stretching its red branches in all directions. The Greeks, who +were never at a loss, relate that Perseus one day laid down upon the +sea-shore the famous head of Medusa, the sight of which had the property +of turning everything to stone, and that the nymphs, in sport, showed +it to the coral shrubs; a fact which explained everything quite +naturally. Without exactly holding this mythological explanation, +modern philosophers had not got much farther, and coral was still a +puzzle to them, which they were not fond of troubling themselves about; +till, roused by Trembley's revelations, they examined it more carefully, +and discovered in its soft extremities (hitherto unnoticed) those same +living jelly-bags or sacs, with their circlets of legs, or rather arms, +charged with supplying them with food. These were marine polyps, which +grow, like those in fresh water, one upon another, but each in its own +crusty cell; and like the buds of the oak, these buds of the stony +tree form each its special deposit, which it bequeaths in dying to the +general mass. In short, as the tender shoot of the oak is filled by +degrees with the wood which forms within it, and hardens into a branch, +that goes on increasing by perpetually new growths, so the jelly polyp +of the polypidom hardens below into stone and dies incessantly at the +base, while it lives on indefinitely above in its constantly-renewed +summit. + +Do not get tired of all this phantasmagoria, my dear pupil: it is a +matter of the highest interest. Here is the point of junction--the +bond, as it were, between the three kingdoms: an animal growing +vegetable-wise produces a mineral mass, extracted from the waters of +the sea by an infinity of little living crucibles, who carry on under +our eyes the work begun in the first ages of the globe, and quietly +manufacture continents for the use of future generations. This ought +to console you, my dear child, for being little. It is by little things +that God loves to effect what is truly great. He did not seek out the +elephant or the whale to form these worlds; He chose workmen no bigger +than a pin's head. I have spoken to you about jeweller's coral, which +is made into toys or presents for ladies to adorn themselves with; but +its brethren, the madrepores of the Pacific Ocean play a very different +part. They have formed in front of the shores of New Holland a barrier +of reefs three hundred leagues in extent and twenty wide. What are all +our buildings after this?--those pyramids and cathedrals which seem +so gigantic to us? This ever-increasing wave of coral polypidoms will +one day shut against navigators the entrance to one part of the sea's +tropical region; and lands not to be found on the map to-day will then +lie stretched out under the sun, covered with plants and animals; and +this in places where ships now plough the ocean. Know, also, that a +great portion of the soil which we tread under foot has no other origin. +It was manufactured formerly in the sea by infinite myriads of beings, +often infinitely small. Each one, whether polype or shell, produced +its grain of stone, and from all these grains God, who directed their +work, has made our country. + +But it is time to bring this chattering to a close, for it will never +end if I do not force myself to stop. I leave it with regret; but all +these paths through which I have threaded my way one after another +without counting them, have already made a volume which may possibly +be considered too large for you. There are many other zoophytes besides +the coral polypes, and all of them beautiful and curious. They all +inhabit the fertile depths of the waters where God has deposited the +first germs of life. I cannot describe them to you now. But to make +amends, I will give you a piece of advice which will perhaps make some +people stare. Ask your papa to lend you Michelet's book, _The Sea_, +and look there for what is said about the mysterious animals which lie +hid beneath the waves. His book was not written for you as this one +is: and if, in spite of all my good intentions, I have not always +succeeded in being as comprehensible as I meant to be, Michelet, who +never thought about little people when he took up his pen, will +certainly startle you now and then. But do not be disheartened by a +word. You will find there, that which will be forever plain to you, +the poesy of nature, and children comprehend that better than learned +men. + + + +LETTER XL. + +THE NOURISHMENT OF PLANTS. + +One more word before we part about the last of the eaters, about +Vegetables. They will furnish you with a new and very clearly marked +proof of the uniformity of the fundamental conditions to which the +Author of life has subjected all organised beings. + +Let us look once more at this oak, of whose manner of growth I was +obliged to give you a sketch beforehand, in order to show you the ties +which unite it with its immediate neighbors in the animal kingdom. How +does it feed? I need not tell you this. It feeds by its roots, which +suck up in the bosom of the earth the water charged with the juices +which form its nourishment. Are you aware that every large branch had +its subterranean fellow or representative, and that the annual shoot +at the top of the tree is reproduced at the base by fresh fibres, which +extend themselves in the soil of the earth, in proportion as their +sisters above make their way in the air? And thus, by means of organs +ever young, the life and progress of the great association is kept up, +while those members whose day of work is over still remain there as +the supports of the edifice. It is the same with human societies. They +are sustained by what is old, but they live and progress only by what +is young. The sap, then, which is the name given to the moisture or +water sucked in by the young roots, having once got into the cells of +which the tissue of the fibres is composed, passes from one to another, +and travels thus to the top of the tree, where it is wanted by the +leaves. + +There is no obvious machinery here, however, to impel it forward. It +journeys on of itself, as it were, under the action of laws which have +never been satisfactorily explained, but all of which are dependent +on the vital force or life-power of the tree, inasmuch as without it +there is no circulation. One agent, but by no means the principal, or +it would act as well in a dead tree as a living one, is _capillary +attraction_; and, if you wish to know what that is, you have only +to think of what happens to a towel, if you hang it upon a peg, and +leave the end of it soaking in water. Does not the "wet" seem to climb +up it thread by thread, till it is damp from one end to the other? A +little in this way--but these similes are very imperfect, and will not +bear close application--the sap rises in a tree, stealing up branch +by branch; and it is then called _ascending sap_. [Footnote: M. Macé +speaks of this sap as the _blood of the tree_, and of the leaves only as +_lungs_. These statements have been modified so as to meet the fact that +_ascending sap_ consists of, and conveys the raw elements of _food_ to, +the leaves; that in the leaves this food is _digested_, as well as +brought in contact with the air, and that it is thus converted into that +nourishing fluid, the _descending sap_, which certainly plays the part +of steward to the tree as our blood does to us, and therefore may now be +called the blood of the tree. It must be remembered, however, that each +tree has its own sort of steward, as the case of the _Euphorbia_ (quoted +afterwards) plainly shows. The analogy with the more general substance +of blood is therefore not very complete.-TR.] + +It arrives at last at the leaves, which it enters as our food enters +our stomachs, and for the same purpose; for in them takes place, as +in all true stomachs, that process of digestion by which the elements +of the crude sap-food are decomposed from their first condition, and +converted into a nourishing chyle; in each tree of a sort "after its +kind." + +But more than this. Like the outer coat of the earthworm, the coat of +the leaf affords a passage to air and moisture through its surface; +and here, therefore, takes place that mysterious exchange which is +everywhere the essential condition of life. Here is the charcoal-market +as before, only the bargainers have changed parts. The air, which in +the other case received the _carbon,_ delivers it up, now, and +receives oxygen in exchange; exactly the reverse of its traffic with +animals. In other words, the tree inhales through its leaves the +carbonic acid gas thrown into the atmosphere by our lungs. On its own +responsibility it breaks through the alliance between the carbon and +oxygen contracted in our organs; keeps the carbon for its own use, to +restore it to us another day under the form of wood, or, by the aid +of the charcoal-burner, in the pure and simple state of charcoal; and +sets at liberty the oxygen, which once more goes off in search of new +lungs and a fresh alliance. Thus a constant equilibrium is maintained +in the atmosphere; and thus, by a system of perpetual rotation or +everlasting merry-go-round, the same substances serve, indefinitely, +to support life of every opposite description. + +Now there are two things to be remembered in this inverted respiration +of vegetables. In the first place, it occurs only in the parts which +are _green_. Flowers, fruit, the root, and every part of any other +color, do as we do when we breathe; _i.e._ deprive the air of its +oxygen, charging it with carbonic acid instead. For which reason, +by-the-by, we ought not to keep flowers in a bedroom at night. Charming +as they are, they are _poisoners_, and a headache is what we may +fairly expect after sleeping shut in with them in the same room. It +is almost as bad to allow green boughs to remain there either, for, +in the dark, even the green parts cease to purify the air, and begin +like the others to manufacture carbonic acid, at the expense of course +of their carbon, which thus by degrees is used up. Now, as it is the +carbon which constitutes the solid fibres of plants and produces their +green color, they soon become yellow and limp when deprived of light. +You may, perhaps, have wondered why the gardener amused himself with +smothering his poor lettuces by tying them up at top like a knot of +"back hair," instead of letting them grow freely in the air and +sunshine. It is, my dear, to make them more tender and delicate for +you to eat; and those beautiful, crisp, yellow leaves, so delicious +to the tooth, would have been green and tough, had they not slowly and +quietly let out a great portion of their store of carbon in darkness +during the last few days, before being gathered. Even without playing +the gardener, you may assure yourself of this fact in a still more +simple manner. Put a flat board upon the lawn and leave it there for +three days; then take it up again, and you will find just where the +board has prevented the light from reaching the grass, a yellow mark +so distinctly traced as to be seen from the other end of the garden. + +But to return to the sap, which we left undergoing a change from air +and solar influences in the leaves. The ascending sap was to all +appearance only clear water. When it returns from the leaves, charged +with carbon, it is a thick juice having almost the consistency, and +sometimes even the color of milk, and is possessed of properties +altogether new. The most striking example that I can give you of +thedifference of the two states of sap is the Euphorbia of the Canary +Islands, whose digestive or descending sap is a violent poison. When +the natives of the country are accidentally pressed by thirst, they +carefully remove the bark in which the fatal juice circulates, and are +then able to refresh themselves safely by sucking the stem, which +yields only the watery sap sucked from the ground, and as yet unaltered +and harmless. + +Each of these two saps, in fact, has its path distinctly traced for +it: the first rises through the wood, the second descends through the +bark, whence it is called descending sap. If you wish to satisfy +yourself of this, fasten a rather tight knot of pack-thread round a +young branch, and after a time you will see it pine below the knot and +become swollen above it, an unanswerable proof that the nutritive +juices flowed downward through the bark; for the wood inside the branch +will have been uninjured by the strangling pressure. Remember this, +my dear, when you are playing in the garden, and do not injure the +bark of the young trees your father likes so much to see flourishing. +It is by the bark that they are nourished, and you might even kill +them by treating it too roughly. + +And now I must show you how the nutrition is carried on, or, if you +like better, how the tree grows by means of this descending sap. See: +here is a fir tree, which has just been cut down to the ground. Now, +if you like, I will tell you in a moment how old it is. I will even +tell you the age of every branch, little and big ones both, without +making a mistake in a single year; and you know as well as I do that +I am no conjuror. You see these small circles so delicately drawn, as +it were, upon the face of the sawn trunk, each wider than the last, +as if they were composed of a set of tubes, of unequal sizes, fitting +exactly into each other. Now count them; and you will perhaps find +twenty-five; and as each of these circles represents the work of one +year, you will know that the tree is twenty-five years old. In spring, +when the sap begins to move more briskly, it deposits everywhere between +the wood and the bark, from the trunk to the farthest boughs of the +tree, a uniform layer of a thick liquid, which moulds itself exactly +upon the wood already formed. This layer stiffens during the year; it +gets filled with the carbon left in it atom after atom, by each drop +of the descending sap as it goes by, and thus insensibly becoming +organised and hardened. When winter arrives to interrupt the work, it +will have formed two _ligneous, i.e._ woody layers, as they are +called. Of these, one belongs to the wood, and will never move again +so long as the tree lasts, for it will be covered over, and as it were +buried, by the successive layers yet to come; while, on the contrary, +the other (layer) belongs to the bark, and is doomed to find itself +perpetually forced outwards by the fresh layers, which will after a +while insinuate themselves between it and the wood. + +It is for this reason that the bark of old trunks of trees is so deeply +furrowed, and that the dry scales may be picked off the surface without +the slightest injury to the tree. It is part of the original bark, +dead long ago. The old wood also is dead inside, and even when it is +altogether gone, the glad youthful branches growing green in the +sunshine will scarcely find it out! This accounts for those oaks which +time has hollowed without destroying, as those of Allonville in +Normandy, in which mass is said, and which is moreover the greenest +tree in the country. But without going so far, who has not seen those +hollow old willows, sometimes pierced with holes letting in daylight, +yet proudly crowned above by a forest of young boughs, as green and +full of vigor as if the trunk were still in its prime? What was dead +has departed, but all that has life in it remains, and that is enough +for the tree. + +Need I add that the descending sap, this steward of the vegetable, has +also his workmen to supply with materials, as in our case, and that +he is always falling in on his road with organs, all of which want +different things from him? That here a flower has to be formed, there +a fruit, there a leaf, or a bit of wood, and so on: and that a +mysterious intelligence--the same that we have found everywhere +else--presides over all these varied constructions, the materials for +which are mixed together pell-mell, in the imperceptible thread of sap +which oozes from the leaf to the bark? I recollect just as I am about +to conclude, my dear child, that I once told you, you were a small +temple in which God perpetually attests His presence, by a permanent +miracle. You may now henceforth look upon a tree as something more +than a bit of wood, yielding a pleasant shade. God is in it also. + + +CONCLUSION. + +And now, my dear little pupil, to what conclusion do we come from all +this? To that which I announced to you from the first. Throughout the +length and breadth of creation, from the highest to the lowest grade, +every living thing is subject to the same law. Everything eats, and +eats nearly in the same manner, since everywhere the same substances +furnish the feast. I laid down in my first letter that our feeding +machine was reproduced even to the farthest limits of the animal +kingdom, though always becoming more simple as the species descends +in the scale. And afterwards, where we began the study of animals, I +told you that in this machine lay the uniformity of their construction. +Was I not right? and what could I add to all the proofs which have +developed themselves one after another, to establish the fact of this +uniformity of plan in the animal machine, in all its essential points? +And it will be to the lasting renown of the illustrious Geoffroy St. +Hilaire that it was, in the face of all the Academies and under the +fire of very learned indignation, he proclaimed this truth, which one +cannot lose sight of without losing one's way in a crowd of arbitrary +fancies. + +I return, then, to the definition which I gave you in speaking of the +worm, and which is the final word of the ideas I have been endeavoring +to make you understand. _An animal is a digestive tube served by +organs._ + +In the first place it must eat, and for this therefore the Creator +provided first. All the rest came afterwards in order to enable it to +eat more readily, to secure its prey more easily, and to make the most +of it when eaten. The movement machine, therefore, whose history I +have promised you, is only an assistant, and not the principal feature +of the organisation, and it is not by it, therefore, that the question +can be decided, whether God has made three, four, or five animals, or +whether he has only made one. + +And now, my dear little pupil, I will bid you adieu, or rather say as +the French do, "Au revoir," which means "Good-bye till we meet again," +begging you to excuse any awkward expressions that may have escaped +me, as also my having now and then talked about things because they +have interested me, without perhaps sufficiently considering whether +they might have an equal interest for you. Yet, while the pen is still +in my hand, I will not leave you my concluding definition of an animal +without adding a word of explanation. You know nothing about such +matters yourself, but to some people my words might have the air of +a parody upon another definition, applied by those grave gentlemen the +Philosophers to man, whom they have denominated _An intelligence +served by organs_. My definition is applicable only to the animal, +and not to man, observe. Man in the natural, physical machinery of his +body, is very decidedly an animal; yet as certainly is he, by the +divine reflection which shines within him, something much more and +greater; but _what_, is so far beyond the reach of definitionthat I +shall not attempt to give you one. "Man," as Jesus Christ has +said, "lives not by bread alone, but by every word that proccedeth out +of the mouth of God." What it is that is nourished in us by that word, +is precisely what I cannot attempt to define for you; yet I think you +have understood my meaning. + +Go, then, and eat your food in peace, like the pretty little animal +that you are; but do not forget to nourish also the other part of your +being; that indeed which is of the most importance, and which enables +you to ascend to your Creator. + +THE END. + + + +POSTSCRIPT. + +In going through the preceding pages (Part II) with a comparative +anatomist, it became evident that some few popular and other errors +and misconceptions had crept into this portion of M. Macé's usually +clear and accurate work. + +Naturally it was not in his power to verify all the statements he had +to make on so many and such varied subjects, and he appears occasionally +to have trusted to works of old-fashioned or doubtful authority. + +In these cases I have considered it desirable to make such corrections +as should secure the trustworthiness of the descriptions as far as +they pretend to go. + +It would not, however, have been in my power to accomplish this, but +for the kind and efficient aid I have received from a scientific student +of these subjects; and I am glad of this opportunity of acknowledging +how much I am indebted to him for his assistance in making the necessary +alterations, as well as for confirming the correctness of the greater +portion of the work. + +MARGARET GATTY. + +January, 1865. January, 1865. + + + + + + + + + + +End of Project Gutenberg's The History of a Mouthful of Bread, by Jean Mace + +*** END OF THIS PROJECT GUTENBERG EBOOK THE HISTORY OF A MOUTHFUL OF BREAD *** + +***** This file should be named 6970-8.txt or 6970-8.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/6/9/7/6970/ + +Produced by Juliet Sutherland, Charles Franks and the +Online Distributed Proofreading Team. + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License available with this file or online at + www.gutenberg.org/license. + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS', WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation information page at www.gutenberg.org + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at 809 +North 1500 West, Salt Lake City, UT 84116, (801) 596-1887. Email +contact links and up to date contact information can be found at the +Foundation's web site and official page at www.gutenberg.org/contact + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit www.gutenberg.org/donate + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: www.gutenberg.org/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart was the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For forty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + +Most people start at our Web site which has the main PG search facility: + + www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. diff --git a/6970-8.zip b/6970-8.zip Binary files differnew file mode 100644 index 0000000..8977cc6 --- /dev/null +++ b/6970-8.zip diff --git a/6970.txt b/6970.txt new file mode 100644 index 0000000..a17f1fd --- /dev/null +++ b/6970.txt @@ -0,0 +1,11697 @@ +Project Gutenberg's The History of a Mouthful of Bread, by Jean Mace + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The History of a Mouthful of Bread + And its effect on the organization of men and animals + +Author: Jean Mace + +Posting Date: September 3, 2012 [EBook #6970] +Release Date: November, 2004 +First Posted: February 18, 2003 + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK THE HISTORY OF A MOUTHFUL OF BREAD *** + + + + +Produced by Juliet Sutherland, Charles Franks and the +Online Distributed Proofreading Team. + + + + + + + + + + +THE HISTORY OF A MOUTHFUL OF BREAD: +And Its Effect on the Organization of Men and Animals. + +BY JEAN MACE. + +Translated Prom the Eighth French Edition, By Mrs. Alfred Gatty. + + + + +EXTRACTS FROM THE PREFACE TO THE ENGLISH EDITION. + +The volume of which the following pages are a translation, has been +adopted by the _University Commission at Paris_ among their prize +books, and has reached an eighth edition. Perhaps these facts speak +sufficiently in its favor; but as translator, and to some extent editor, +I wish to add my testimony to the great charm as well as merit of the +little work. I sat down to it, I must own, with no special predilection +in favor of the subject as a suitable one for young people; but in the +course of the labor have become a thorough convert to the author's +views that such a study--perhaps I ought to add, so pursued as he has +enabled it to be--is likely to prove a most useful and most desirable +one. + +The precise age at which the interest of a young mind can be turned +towards this practical branch of natural history is an open question, +and not worth disputing about. It may vary even in different +individuals. The letters are addressed to a _child_--in the original +even to a _little girl_--and most undoubtedly, as the book stands, it is +fit for any child's perusal who can find amusement in its pages: while +to the rather older readers, of whom I trust there will be a great many, +I will venture to say that the advantage they will gain in the subject +having been so treated as to be brought within the comprehension and +adapted to the tastes of a child, is pretty nearly incalculable. The +quaintness and drollery of the illustrations with which difficult +scientific facts are set forth will provoke many a smile, no doubt, and +in some young people perhaps a tendency to feel themselves treated +_babyishly_; but if in the course of the babyish treatment they find +themselves almost unexpectedly becoming masters of an amount of valuable +information on very difficult subjects, they will have nothing to +complain of. Let such young readers refer to even a popular +Encyclopaedia for an insight into any of the subjects of the +twenty-eight chapters of this volume--"The Heart," "The Lungs," "The +Stomach," "Atmospheric Pressure,"--no matter which, and see how much +they can understand of it without an amount of preliminary instruction +which would require half-a-year's study, and they will then thoroughly +appreciate the quite marvellous ingenuity and beautiful skill with +which M. Mace has brought the great leading anatomical and physical +facts of life out of the depths of scientific learning, and made them +literally comprehensible by a child. + + * * * * * + +There is one point (independent of the scientific teaching) and that, +happily, the only really important one, in which the English translator +has had no change to make or desire. The religious teaching of the +book is unexceptionable. There is no strained introduction of the +subject, but there is throughout the volume an acknowledgment of the +Great Creator of this marvellous work of the human frame, of the daily +and hourly gratitude we owe to Him, and of the utter impossibility of +our tracing out half his wonders, even in the things nearest to our +senses, and most constantly subject to observation. M. Mace will help, +and not hinder the humility with which the Christian naturalist lifts +one veil only to recognise another beyond. + +It will be satisfactory to any one who may be inclined to wonder how +a lady can feel sure of having correctly translated the various +scientific and anatomical statements contained in the volume, to know +that the whole has been submitted to the careful revision of a medical +friend, to whom I have reason to be very grateful for valuable +explanations and corrections whenever they were necessary. In the same +way the chapter on "Atmospheric Pressure," where, owing to the +difference between French and English weights and measures, several +alterations of illustrations, etc., had to be made, has received similar +kind offices from the hands of a competent mathematician. + + * * * * * + +MARGARET GATTY. + +Ecclesfield, June, 1864. + + + + +NOTE TO THE AMERICAN EDITION. + +In May '66, the seventeenth edition of this work was on sale in Paris. +The date of Mrs. Gatty's preface, it will be observed, is June '64, +and at that time, the eighth French edition only had been reached. +That it should be a popular book and command large sale wherever it +is known, will not surprise any one who reads it: the only remarkable +circumstance about it is, that it should not have been republished +here long ere this. Even this may probably be accounted for, on the +supposition that the title under which the translation was published +in England, was so unmeaning--conveying not the slightest idea of the +contents of the book--that none of our publishers even ventured to +hand it over to their "readers" to examine. + +The author's title, _The History of a Mouthful of Bread_, while +falling far short of giving a clear notion of the entire scope of the +work, is shockingly diluted and meaningless, when translated _The +History of a Bit of Bread!_ + +To the translation of Mrs. Gatty, which is in the main an excellent +one, for she has generally seized upon the idea of the author and +rendered it with singular felicity, it may be very properly objected +that she has taken some liberties with the text when there was any +conflict of opinion between herself and her author, and has given her +own ideas instead of his, which is, probably, what she refers to when +she calls herself "to some extent editor." + +The reader of this edition will, in all these cases, find the thought +of the author and not that of his translator; for the reason that a +careful examination of the original has convinced the publisher that +in every instance the author was to be preferred to the translator, +to say nothing of the right an author may have to be faithfully +translated. + +Besides making these restorations, the copy from which this edition +was printed has been carefully compared with the last edition of the +author and a vast number of corrections made, and in its present shape +it is respectfully submitted and dedicated to every one (whose name +is legion, of course) who numbers among his young friends a "_my +dear child_" to present it to. + + + + + +CONTENTS. + +I.--INTRODUCTION + +FIRST PART MAN. + +II.--THE HAND +III.--THE TONGUE +IV.--THE TEETH +V.--THE TEETH (_continued_) +VI.--THE TEETH (_continued_) +VII.--THE THROAT +VIII.--THE STOMACH +IX.--THE STOMACH (_continued_) +X.--THE INTESTINAL CANAL +XI.--THE LIVER +XII.--THE CHYLE +XIII.--THE HEART +XIV.--THE ARTERIES +XV.--THE NOURISHMENT OF THE ORGANS +XVI.--THE ORGANS +XVII.--ARTERIAL AND VENOUS BLOOD +XVIII.--ATMOSPHERIC PRESSURE +XIX.--THE ACTION OF THE LUNGS +XX.--CARBON AND OXYGEN +XXI.--COMBUSTION +XXII.--ANIMAL HEAT +XXIII.--ACTION OF THE BLOOD UPON THE ORGANS +XXIV.--THE WORK OF THE ORGANS +XXV.--CARBONIC ACID +XXVI.--ALIMENTS OF COMBUSTION +XXVII.--ALIMENTS OF NUTRITION (_continued_)--NITROGEN OR AZOTE +XXVIII.--COMPOSITION OF THE BLOOD + + +SECOND PART. + +ANIMALS. + +XXIX.--CLASSIFICATION OF ANIMALS +XXX.--MAMMALIA (_Mammals_) +XXXI.--MAMMALIA. (_Mammals_)--_continued_ +XXXII.--MAMMALIA--_continued_ +XXXIII.--MAMMALIA--_continued_ +XXXIV.--AVES. (_Birds_) +XXXV.--REPTILIA. (_Reptiles_) +XXXVI.--PISCES. (_Fishes_) +XXXVII.--INSECTA. (_Insects_) +XXXVIII.--CRUSTACEA--MOLLUSKA. (_Crustaceans and Mollusks_) +XXXIX.--VERMES--ZOOPHYTA. (_Worms and Zoophytes_) +XL.--THE NOURISHMENT OF PLANTS +CONCLUSION + + + +I. + +INTRODUCTION. + +I am going to tell you, my dear child, something of the life and nature +of men and animals, believing the information may be of use to you in +after-life, besides being an amusement to you now. + +Of course, I shall have to explain to you a great many particulars +which are generally considered very difficult to understand, and which +are not always taught even to grown-up people. But if we work together, +and between us succeed in getting them clearly into your head, it will +be a great triumph to me, and you will find out that the science of +learned men is more entertaining for little girls, as well as more +comprehensible, than it is sometimes supposed to be. Moreover, you +will be in advance of your years, as it were, and one day may be +astonished to find that you had mastered in childhood, almost as a +mere amusement, some of the first principles of anatomy, chemistry, +and several other of the physical sciences, as well as having attained +to some knowledge of natural history generally. + +I begin at once, then, with the _History of a Mouthful of Bread_, +although I am aware you may be tempted to exclaim, that if I am going +to talk only about that, I may save myself the trouble. You know all +about it, you say, as well as I do, and need not surely be told how +to chew a bit of bread-and-butter! Well, but you must let me begin at +the very beginning with you, and you have no notion what an incredible +number of facts will be found to be connected with this chewing of a +piece of bread. A big book might be written about them, were all the +details to be entered into. + +First and foremost--Have you ever asked yourself _why_ people eat? + +You laugh at such a ridiculous question. + +"Why do people eat? Why, because there are bonbons, and cakes, and +gingerbread, and sweetmeats, and fruit, and all manner of things good +to eat." Very well, that is a very good reason, no doubt, and you may +think that no other is wanted. If there were nothing but soup in the +world, indeed, the case would be different. There might be some excuse +then for making the inquiry. + +Now, then, let us suppose for once that there _is_ nothing in the +world to eat but soup; and it is true that there are plenty of poor +little children for whom there is nothing else, but who go on eating +nevertheless, and with a very good appetite, too, I assure you, as +their parents know but too well very often. Why do people eat, then, +even when they have nothing to eat but soup? This is what I am going +to tell you, if you do not already know. + +The other day, when your mamma said that your frock "had grown" too +short, and that you could not go out visiting till we had given you +another with longer sleeves and waist, what was the real cause of this +necessity? + +What a droll question, you say, and you answer--"Because I had grown, +of course." + +To which I say "of course," too; for undoubtedly it was you who had +outgrown your frock. But then I must push the question further, and +ask--How had you grown? + +Now you are puzzled. Nobody had been to your bed and pulled out your +arms or your legs as you lay asleep. Nobody had pieced a bit on at the +elbow or the knee, as people slip in a new leaf to a table when there +is going to be a larger party than usual at dinner. How was it, then, +that the sleeves no longer came down to your wrists, or that the body +only reached your knees? Nothing grows larger without being added to, +any more than anything gets smaller without having lost something; you +may lay that down as a rule, once for all. If, therefore, nothing was +added to you from without, something must have been added to you from +within. Some sly goblin, as it were, must have been cramming into your +frame whatever increase it has made in arms, legs, or anything else. +And who, do you think, this sly goblin is? + +Why, my dear, it is _yourself!_ + +Ay! Bethink you, now, of all the bread-and-butter, and bonbons, and +gingerbread, and cakes, and sweetmeats, and even soup and plain food +(the soup and plain food being the most useful of all) which you have +been sending, day by day, for some time past, down what we used to +call "the red lane," into the little gulf below. What do you think +became of them when they got there? Well, they set to work at once, +without asking your leave, to transform themselves into something else; +and gliding cunningly into all the holes and corners of your body, +became there, each as best he might, bones, flesh, blood, etc., +etc. Touch yourself where you will, it is upon these things you lay +your hand, though, of course, without recognizing them, for the +transformation is perfect and complete. And it is the same with +everybody. + +Look at your little pink nails, which push out further and further +every morning; examine the tips of your beautiful fair hair, which +gets longer and longer by degrees; coming out from your head as grass +springs up from the earth; feel the firm corners of your second teeth, +which are gradually succeeding those which came to you in infancy; you +have _eaten_ all these things, and that no long time ago. + +Nor are you children the only creatures who are busy in this way. There +is your kitten, for instance, who a few months ago was only a tiny bit +of fur, but is now turning gradually into a grown-up cat. It is her +daily food which is daily becoming a cat inside her--her saucers of +milk now, and very soon her mice, all serve to the same end. + +The large ox, too, of whom you are so much afraid, because you cannot +as yet be persuaded what a good-natured beast he really is, and how +unlikely to do any harm to children who do none to him--that large ox +began life as a small calf, and it is the grass which he has been +eating for some time past which has transformed him into the huge mass +of flesh you now see, and which by-and-by will be eaten by man, to +become man's flesh in the same manner. + +But, further, still: Even the forest trees, which grow so high and +spread so wide, were at first no bigger than your little finger, and +all the grandeur and size you now look upon, they have taken in by the +process of eating. "What, _do trees eat?_" you ask. + +Verily, do they; and they are, by no means, the least greedy of eaters, +for they eat day and night without ceasing. Not, as you may suppose, +that they crunch bonbons, or anything else as you do; nor is the process +with them precisely the same as with you. Yet you will be surprised +hereafter, I assure you, to find how many points of resemblance exist +between them and us in this matter. But we will speak further of this +presently. + +Now, I think you must allow that there are few fairytales more +marvellous than this history of bread and meat turning into little +boys and girls, milk and mice turning into cats, and grass into oxen! +And I call it a _history_, observe, because it is a transformation +that never happens suddenly, but by degrees, as time goes on. + +Now, then, for the explanation. You have heard, I dare say, of those +wonderful spinning-machines which take in at one end a mass of raw +cotton, very like what you see in wadding, and give out at the other +a roll of fine calico, all folded and packed up ready to be delivered +to the tradespeople. Well, you have within you, a machine even more +ingenious than that, which receives from you all the bread-and-butter +and other sorts of food you choose to put into it, and returns it to +you changed into the nails, hair, bones and flesh we have been talking +about, and many other things besides; for there are quantities of +things in your body, all different from each other, which you are +manufacturing in this manner all day long, without knowing anything +about it. And a very fortunate thing this is for you: for I do not +know what would become of you if you had to be thinking from morning +to night of all that requires to be done in your body, as your mother +has to look after and remember all that has to be done in the house. +Just think what a relief it would be to her to possess a machine which +should sweep the rooms, cook the dinners, wash the plates, mend torn +clothes, and keep watch over everything without giving her any trouble; +and, moreover, make no more noise or fuss than yours does, which has +been working away ever since you were born without your ever troubling +your head about it, or probably even knowing of its existence! Just +think of this and be thankful. + +But do not fancy you are the only possessor of a magical machine of +this sort. Your kitten has one also, and the ox we were speaking of, +and all other living creatures. And theirs render the same service to +them that yours does to you, and much in the same way; for all these +machines are made after one model, though with certain variations +adapted to the differences in each animal. And, as you will see +by-and-by, these variations exactly correspond with the different sort +of work that has to be done in each particular case. For instance, +where the machine has grass to act upon, as in the ox, it is differently +constructed from that in the cat which has to deal with meat and mice. +In the same way in our manufactories, though all the spinning-machines +are made upon one model, there is one particular arrangement for those +which spin cotton, another for those which spin wool, another for flax, +and so on. + +But, further: + +You have possibly noticed already, without being told, that all animals +are not of equal value; or, at least, to use a better expression, they +have not all had the same advantages bestowed on them. The dog, for +instance, that loving and intelligent companion, who almost reads your +thoughts in your eyes, and is as affectionate and obedient to his master +as it were to be wished all children were to their parents--this dog +is, as you must own, very superior, in all ways, to the frog, with its +large goggle eyes and clammy body, hiding itself in the water as soon +as you come near it. But again, the frog, which can come and go as it +likes, is decidedly superior to the oyster, which has neither head nor +limbs, and lives all alone, glued into a shell, in a sort of perpetual +imprisonment. + +Now the machine I have been telling you about is found in the oyster +and in the frog as well as in the dog, only it is less complicated, +and therefore less perfect in the oyster than in the frog; and less +perfect again in the frog than in the dog; for as we descend in the +scale of animals we find it becoming less and less elaborate--losing +here one of its parts, there another, but nevertheless remaining still +the same machine to all intents and purposes; though by the time it +has reached its lowest condition of structure we should hardly be able +to recognize it again, if we had not watched it through all its +gradations of form, and escorted it, as it were, from stage to stage. + +Let me make this clear to you by a comparison. + +You know the lamp which is lit every evening on the drawing-room table, +and around which you all assemble to work or read. Take off first the +shade, which throws the light on your book--then the glass which +prevents it smoking--then the little chimney which holds the wick and +drives the air into the flame to make it burn brightly. Then take away +the screw, which sends the wick up and down; undo the pieces one by +one, until none remain but those absolutely necessary to having a light +at all--namely, the receptacle for the oil and the floating wick which +consumes it. + +Now if any one should come in and hear you say, "Look at my lamp," +what would he reply? He would most likely ask at once, "What lamp?"--for +there would be very little resemblance to a lamp in that mere ghost +of one before him. + +But to you, who have seen the different parts removed one after another, +that wick soaked in oil (let your friend shake his head about it as +he pleases) will still be the lamp to you, however divested of much +that made it once so perfect, and however dimly it may shine in +consequence. + +And this is exactly what happens when the machine we are discussing +is examined in the different grades of animals. The ignoramus who has +not followed it through its changes and reductions cannot recognize +it when it is presented to him in its lowest condition; but any one +who has carefully observed it throughout, knows that it is, in point +of fact, the same machine still. + +This, then, is what we are now going to look at together, my dear +little girl. We will study first, piece by piece, the exquisite machine +within ourselves, which is of such unceasing use to us as long as we +do not give it more than a proper share of work to perform. Do you +understand? We will see what becomes of the mouthful of bread which +you place so coolly between your teeth, as if when that was done nothing +further remained to be thought about. We will trace it in its passage +through every part of the machine, from beginning to end. It will +therefore be simply only the _History of a Mouthful of Bread_ I +am telling you, even while I seem to be talking of other matters; for +to make that comprehensible I shall have to enter into a good many +explanations. + +And when you have thoroughly got to understand the history of what you +eat yourself, we will look a little into the history of what other +animals eat, beginning by those most like ourselves, and going on to +the rest in regular succession downwards. And while we are on the +subject, I will say a word or two on the way in which vegetables eat, +for, as you remember, I have stated that they do eat also. + +Do you think this is likely to interest you, and be worth the trouble +of some thought and attention? + +Perhaps you may tell me it sounds very tedious, and like making a great +fuss about a trifle; that you have all your life eaten mouthfuls of +bread without troubling yourself as to what became of them, and yet +have not been stopped growing by your ignorance, any more than the +little cat, who knows no more how it happens than you do. + +True, my dear; but the cat is only a little cat, and you are a little +girl. Up to the present moment you and she have known, one as much as +the other on this subject, and on that point you have therefore had +no superiority over her. But she will never trouble herself about it, +and will always remain a little cat. You, on the contrary, are intended +by God to become something more in intelligence than you are now, and +it is by learning more than the cat that you will rise above her in +this respect. To learn, is the duty of all men, not only for the +pleasure of curiosity and the vanity of being called learned, but +because in proportion to what we learn we approach nearer to the destiny +which God has appointed to man, and when we walk obediently in the +path which God himself has marked out for us, we necessarily become +better. + +It is sometimes said to grown-up people, that it is never too late to +learn. To children one may say that it is never too early to learn. +And among the things which they may learn, those which I want now to +teach you have the double merit of being, in the first place amusing, +and afterwards, and above all, calculated to accustom you to think of +God, by causing you to observe the wonders which He has done. Sure am +I that when you know them you will not fail to admire them; moreover +I promise your mother that you will be all the better, as well as +wiser, for the study. + + + + +FIRST PART.--MAN. + +LETTER II. + +THE HAND. + +At the foot of the mountains, from whence I write to you, my dear +child, when we want to show the country to a stranger, we commence by +making him climb one of the heights, whence he may take in at a glance +the whole landscape below, all the woods and villages scattered over +the plain, even up to the blue line of the Rhine, which stretches out +to the distant horizon. After this he will easily find his way about. + +It is to the top of a mountain equally useful that I have just led +you. It has cost you some trouble to climb with me. You have had to +keep your eyes very wide open that you might see to the end of the +road we had to go together. Now then, let us come down and view the +country in detail. Then we shall go as if we were on wheels. + +And now let us begin at the beginning: + +Well, doubtless, as the subject is eating, you will expect me to begin +with the mouth. + +Wait a moment; there is something else first. But you are so accustomed +to make use of it, that you have never given it a thought, I dare say. + +It is not enough merely that one should have a mouth; we must be able +to put what we want within it. What would you do at dinner, for +instance, if you had no hands? + +The hand is then the first thing to be considered. + +I shall not give you a description of it; you know what it is like. +But what, perhaps, you do not know, because you have never thought +about it, is, the reason why your hand is a more convenient, and +consequently more perfect, instrument than a cat's paw, for instance, +which yet answers a similar purpose, for it helps the cat to catch +mice. + +Among your five fingers there is one which is called the thumb, which +stands out on one side quite apart from the others. Look at it with +respect; it is to these two little bones, covered over with a little +flesh, that man owes part of his physical superiority to other animals. +It is one of his best servants, one of the noblest of God's gifts to +him. Without the thumb three-fourths (at least) of human arts would +yet have to be invented; and to begin with, the art not only of carrying +the contents of one's plate to one's mouth, but of filling the plate +(a very important question in another way) would, but for the thumb, +have had difficulties to surmount of which you can form no idea. + +Have you noticed that when you want to take hold of anything (a piece +of bread, we will say, as we are on the subject of eating), have you +noticed that it is always the thumb who puts himself forward, and that +he is always on one side by himself, whilst the rest of the fingers +are on the other? If the thumb is not helping, nothing remains in your +hand, and you don't know what to do with it. Try, by way of experiment, +to carry your spoon to your mouth without putting your thumb to it, +and you will see what a long time it will take you to get through a +poor little plateful of broth. The thumb is placed in such a manner +on your hand that it can face each of the other fingers one after +another, or all together, as you please; and by this we are enabled +to grasp, as if with a pair of pincers, whatever object, whether large +or small. Our hands owe their perfection of usefulness to this happy +arrangement, which has been bestowed on no other animal, except the +monkey, our nearest neighbor. + +I may even add, while we are about it, that it is this which +distinguishes the hand from a paw or a foot. Our feet, which have other +things to do than to pick up apples or lay hold of a fork, our feet +have also each five fingers, but the largest cannot face the others; +it is not a thumb, therefore, and it is because of this that our feet +are not hands. Now the monkey has thumbs on the four members +corresponding to our arms and legs, and thus we may say that he has +hands at the end of his legs as well as of his arms. Nevertheless, he +is not on that account better off than we are, but quite the contrary. +I will explain this to you presently. + +To return to our subject. You see that it was necessary, before saying +anything about the mouth, to consider the hand, which is the mouth's +purveyor. Before the cook lights the fires the maid must go to market, +must she not? And it is a very valuable maid that we have here: what +would become of us without her? + +If we were in the habit of giving thought to everything, we should +never even gather a nut without being grateful to the Providence which +has provided us with the thumb, by means of which we are able to do +it so easily. + +But however well I may have expressed it, I am by no means sure, after +all, that I have succeeded in showing you clearly, how absolutely +necessary our hand is to us in eating, and why it has the honor to +stand at the beginning of the history of what we eat. + +It still appears to you, I suspect, that even if you were to lose the +use of your hands you would not, for all that, let yourself die of +hunger. + +This is because you have not attended to another circumstance, which +nevertheless demands your notice--namely, that from one end of the +world to the other, quantities of hands are being employed in providing +you with the wherewithal to eat. + +To go on further: Have you any idea how many hands have been put in +motion merely to enable you to have your coffee and roll in the morning? +What a number, to be sure, over this cup of coffee (which is a trifle +in comparison with the other food you will consume in the course of +the day); from the hand of the negro who gathered the coffee crop to +that of the cook who ground the berries, to say nothing of the hand +of the sailor who guided the ship which bore them to our shores. Again, +from the hand of the laborer who sowed the corn, and that of the miller +who ground it into flour, to the hand of the baker who made it into +a roll. Then the hand of the farmer's wife who milked the cow, and the +hand of the refiner who made the sugar; to say nothing of the many +others who prepared his work for him, and I know not how many more. + +How would it be, then, if I were to amuse myself by counting up all +the hands that are wanted to furnish-- + + The sugar-refiner's manufactory, + The milkmaid's shed, + The baker's oven, + The miller's mill, + The laborer's plough, + The sailor's ship? + +And even now is there nothing we have forgotten? Ah, yes! the most +important of all the hands to you;--the hand which brings together +for your benefit the fruits of the labor of all the others--the hand +of your dear mother, always active, always ready, that hand which so +often acts as yours when your own is awkward or idle. + +Now, then, you see how you might really manage to do without those two +comparatively helpless little paws of yours (although there is a thumb +to each), without suffering too much for want of food. With such an +army of hands at work, in every way, to furnish provision for that +little mouth, there would not be much danger. + + +But cut off your cat's fore paws--oh dear! what am I saying? Suppose, +rather, that she has not got any, and then count how many mice she +will catch in a day. The milk you give her is another matter, remember. +Like your cup of coffee, that is provided for her by others. + +Believe me, if you were suddenly left all alone in a wood, like those +pretty squirrels who nibble hazel-nuts so daintily, you would soon +discover, from being thus thrown upon your own resources, that the +mouth is not the only thing required for eating, and that whether it +be a paw or a hand, there must always be a servant to go to market for +Mr. Mouth, and to provide him with food. + +Happily, we are not driven to this extremity. We take hold of our +coffee-biscuit between the thumb and forefinger, and behold it is on +its road--Open the mouth, and it is soon done! + +But before we begin to chew, let us stop to consider a little. + +The mouth is the door at which everything enters. Now, to every +well-kept door there is a doorkeeper, or porter. And what is the office +of a well-instructed porter? Well, he asks the people that present +themselves, who they are, and what they have come for; and if he does +not like their appearance, he refuses them admittance. We too, then, +to be complete, need a porter of this sort in our mouths, and I am +happy to say we have one accordingly. I wonder whether you know him? +You look at me quite aghast! Oh, ungrateful child, not to know your +dearest friend! As a punishment, I shall not tell you who he is to-day. +I will give you till to-morrow to think about it. + +Meanwhile, as I have a little time left, I will say one word more about +what we are going to look at together. It would hardly be worth while +to tell you this pretty story which we have begun, if from time to +time we were not to extract a moral from it. And what is the moral of +our history to-day? + +It has more than one. + +In the first place it teaches you, if you never knew it before, that +you are under great obligations to other people, indeed to almost +everybody, and most of all perhaps to people whom you may be tempted +to look down upon. This laborer, with his coarse smock-frock and heavy +shoes, whom you are so ready to ridicule, is the very person who, with +his rough hand, has been the means of procuring for you half the good +things you eat. That workman, with turned-up sleeves, whose dirty black +fingers you are afraid of touching, has very likely blackened and +dirtied them in your service. You owe great respect to all these people, +I assure you, for they all work for you. Do not, then, go and fancy +yourself of great consequence among them--you who are of no use in any +way at present, who want everybody's help yourself, but as yet can +help nobody. + +Not that I mean to reproach you by saying this. Your turn has not come +yet, and everybody began like you originally. But I do wish to impress +upon you that you must prepare yourself to become some day useful to +others, so that you may pay back the debts which you are now +contracting. + +Every time you look at your little hand, remember that you have its +education to accomplish, its debts of honor to repay, and that you +must make haste and teach it to be very clever, so that it may no +longer be said of you, that you are of no use to anybody. + +And then, my dear child, remember that a day will come, when the revered +hands that now take care of your childhood--those hands which to-day +are yours, as it were--will become weak and incapacitated by age. You +will be strong, then, probably, and the assistance which you receive +now, you must then render to her, render it to her as you have received +it--that is to say, with your hands. It is the mother's hand which +comes and goes without ceasing about her little girl now. It is the +daughter's hand which should come and go around the old mother +hereafter--her hand and not another's. + +Here again, my child, the mouth is nothing without the hand. The mouth +says, "I love," the hand proves it. + + + +LETTER III. + +THE TONGUE. + +Now, about this doorkeeper, or porter, as we will call him, of the +mouth. I do not suppose you have guessed who he is; so I am going to +tell you. + +The porter who keeps the door of the mouth is _the sense of taste_. + +It is he who does the honors of the house so agreeably to proper +visitors, and gives such an unscrupulous dismissal to unpleasant +intruders. In other words, it is by his directions that we welcome so +affectionately with tongue and lips whatever is good to eat, and spit +out unhesitatingly whatever is unpleasant. + +I could speak very ill of this porter if I chose; which would not be +very pleasant for certain little gourmands that I see here, who think +a good deal too much of him. But I would rather begin by praising him. +I can make my exceptions afterwards. + +In the history I am going to give you, my dear child, there is one +thing you must never lose sight of, even when I do not allude to it; +and that is, that everything we shall examine into, has been expressly +arranged by God for the good and accommodation of our being in this +world; just as a cradle is arranged by a mother for the comfort of her +baby. We must look upon all these things, therefore, as so many +presentsfrom the Almighty himself; and abstain from speaking ill of +them, were it only out of respect for the hand which has bestowed them. + +Moreover, there is a very easy plan by which we may satisfy ourselves +of the usefulness and propriety of these gifts--namely, by considering +what would become of us if we were deprived of any one of them. + +Suppose, for instance, that you were totally deficient in the sense +of taste, and that when you put a piece of cake into your mouth, it +should create no more sensation in you than when you held it in your +hand? + +You would not have thought of imagining such a case yourself, I am +aware; for it never comes into a child's head to think that things can +be otherwise than as God has made them. And in that respect children +are sometimes wiser than philosophers. Nevertheless, we will suppose +this for once, and consider what would happen in consequence. + +Well, in the first place, you would eat old mouldy cake with just the +same relish as if it were fresh; and this mouldy cake, which now you +carefully avoid because it is mouldy, is very unwholesome food, and +would poison you were you to eat a great deal of it. + +I give this merely as an instance, but it is one of a thousand. And +although, with regard to eatables, you only know such as have been +prepared either in shops or in your mamma's kitchen, still you must +be aware there are many we ought to avoid, because they would do no +good in our stomachs, and that we should often be puzzled to distinguish +these from others, if the sense of taste did not warn us about them. +You must admit, therefore, that such warnings are not without their +value. + +In short, it is a marvellous fact that what is unfit for food, is +_almost always_ to be recognized as it enters the mouth, by its +disagreeable taste; a further proof that God has thought of everything. +Medicines, it is true, are unpleasant to the taste, and yet have to +be swallowed in certain cases. But we may compare them to +chimney-sweepers, who are neither pretty to look at, nor invited into +the drawing-room; but who, nevertheless, are from time to time let +into the grandest houses by the porters--though possibly with a +grimace--because their services are wanted. And in the same way +medicines have to be admitted sometimes--despite their +unpleasantness--because they, too, have to work in the chimney. Taste +does not deceive you about them, however; they are not intended to +serve as food. If any one should try to breakfast, dine, and sup upon +physic he would soon find this out. + +Besides, I only said _almost_ always, in speaking of unwholesome +food making itself known to us by its nasty taste; for it is an +unfortunate truth that men have invented a thousand plans for baffling +their natural guardian, and for bringing thieves secretly into the +company of honest people. They sometimes put poison, for instance, +into sugar--as is too often done in the case of those horrible green +and blue sugar plums, against which I have an old grudge, for they +poisoned a friend whom I loved dearly in my youth. Such things as these +pass imprudently by the porter, who sees nothing of their real +character--Mr. Sugar concealing the rogues behind him. + +Moreover, we are sometimes so foolish as not to leave the porter time +to make his examination. We swallow one thing after another greedily, +without tasting; and such a crowd of arrivals, coming in with a rush, +"forces the sentry," as they say; and whose fault is it, if, after +this, we find thieves established in the house? + +But animals have more sense than we have. + +Look at your kitten when you give her some tit-bit she is not acquainted +with--how cautiously and gently she puts out her nose, so as to give +herself time for consideration. Then how delicately she touches the +unknown object with the tip of her tongue, once, twice, and perhaps +three times. And when the tip of the tongue has thus gone forward +several times to make observations (for this is the great post of +observation for the cat's porter as well as for ours), she ventures +to decide upon swallowing, but not before. If she has the least +suspicion, no amount of coaxing makes any difference to her; you may +call "puss, puss," for ever; all your tender invitations are useless, +and she turns away. + +Very good; here then is one little animal, at least, who understands +for what end she has received the sense of taste, and who makes a +reasonable use of it. Very different from some children of my +acquaintance, who heedlessly stuff into their mouths whatever comes +into their hands, without even taking the trouble to taste it, and who +would escape a good many stomach-aches, if nothing else, if they were +as sensible as Pussy. + +This is the really useful side of _the sense of taste_; but its +agreeable side, which is sufficiently well known to you, is not to be +despised either, even on the grounds of utility. + +You must know, between ourselves, that eating would be a very tiresome +business if we did not taste what we are eating; and I can well imagine +what trouble mammas would have in persuading their children to come +to dinner or tea, if it were only a question of working their little +jaws, and nothing further. What struggles--what tears! And setting +aside children, who are by no means always the most disobedient to the +will of a good GOD, how few men would care to stop in the midst of +their occupations, to go and grind their teeth one against another for +half-an-hour, if there were not some pleasure attached to an exercise +not naturally amusing in itself? Ay, ay, my dear child, were it not +for the reward in pleasure which is given to men when they eat, the +human race, who as a whole do not live too well already, would live +still worse. And it is necessary that we should be fed, and well fed +too, if we would perform properly here below the mission which we have +received from above. + +Yes, "reward" was the word I used. Now it seems absurd to you, perhaps, +that it should be necessary to reward a man for eating a good dinner? +Well, well, GOD has been more kind to him, then, than you would be. +To every duty imposed by Him upon man, He has joined a pleasure as a +reward for fulfilling it. How many things should I not have to say to +you on this subject, if you were older? For the present, I will content +myself with making a comparison. + +When a mother thinks her child is not reasonable enough to do, of her +own accord, something which it is nevertheless important she should +do, as learning to read, for instance, or to work with her needle, +&c., she comes to the rescue with rewards, and gives her a plaything +when she has done well. And thus GOD, who had not confidence enough +in man's reason to trust to it alone for supplying the wants of human +nature, has placed a plaything in the shape of pleasure after every +necessity; and in supplying the want, man finds the reward. + +You will hardly believe that what I have here explained to you so +quietly by a childish comparison, has been, and alas! still is, the +subject of terrible disputes among grown-up people. If hereafter they +reach your ears, remember what I have told you now, viz., that the +pleasure lodged in the tongue and its surroundings, is a plaything, +but a plaything given to us by GOD; and that we must use it accordingly. + +If a little girl has had a plaything given to her by her mother, would +she think to please her by breaking it or throwing it into a corner? +No, certainly not: she would know that in so doing she would be going +directly against her mother's intentions and wishes. Nevertheless she +would amuse herself with it in play hours, with an easy conscience, +and, if she is amiable, she will remember while she does so, that it +comes to her from her mother, and will thank her at the bottom of her +heart. + +It is the same with man, of whose playthings we are speaking. + +But, moreover, this little girl (it is taken for granted that she is +a good little girl) will not make the plaything the business of her +whole day, the object of all her thoughts; she will not forget +everything for it, she will leave it unhesitatingly when her mamma +calls her. Neither will she wish to be alone in her enjoyments, but +will gladly see her little friends also enjoy similar playthings, +because she thinks that what is good for her must be good for others +too. + +It is thus that man should do with his playthings; but, alas! this is +what he does not by any means always do with them, and hence a great +deal has been said against them. Little girls, in particular, are apt +to fail on this point, and that is how the dreadful word _gluttony_ +came to be invented. For the same reason, also, people get punished +from time to time; such punishments being the consequence of the misuse +I speak of. + +If people who call to see your mamma were, instead of going straight +up stairs to her, to establish themselves at the lodge with the porter, +and stay there chatting with him, do you think she would be much +flattered by their visits? And yet this is exactly what people do who, +when eating, attend only to the porter. He is so pleasant, this porter; +he says such pretty things to you, that you go on talking to him just +as if he were the master of the house, who, meanwhile, has quite gone +out of your head. + +You heap sugar-plums upon sugar-plums, cakes upon cakes, sweetmeats +upon sweetmeats--everything that pleases the porter, but is of no use +whatever to the master of the house. And then what happens? The master +gets angry sometimes, and no wonder. Mr. Stomach grows weary of these +visits, which are of no use to him. He rings all the bells, makes no +end of a noise in the house, and forces that traitor of a porter who +has engrossed all his company, to do penance. You are ill--your mouth +is out of order--you have no appetite for anything. The mamma has taken +away the plaything which has been misused, and when she gives it back, +there must be great care taken not to do the same thing over again. + +I have thought it only right, my dear child, in telling you the history +of eating, to give to this little detail of its beginning, a place +proportioned to your interest in it. You see by what I have said, that +you are not altogether wrong in following your taste; but neither must +it be forgotten that this part of the business is not in reality the +most important; that a plaything is but a plaything, and that the +porter is not the master of the house. + +Now that we have made our good friend's acquaintance, we will wish him +farewell, and I will presently introduce you to his companions of the +antechamber, who are ranged on the two sides of the door, to make the +toilettes for the visitors who present themselves, and to put them in +order for being received in the drawing-room. You will see there some +jolly little fellows, who are also very useful in their way, and whose +history is no less curious. They are called TEETH. + + + +LETTER IV. + +THE TEETH. + +When you were quite little, my dear child, and still a nursling, you +had nothing behind your lips but two little rosy bars, which were of +no service for gnawing an apple, as they were not supplied with teeth. +You had no need of these then, since nothing but milk passed your lips, +neither had your nurse bargained for your having teeth to bite with. +You see that God provides for everything, as I have already said, and +shall often have occasion to point out to you. + +But by degrees the little infant grew into a great girl, and it became +necessary to think of giving her something more solid than milk to +eat; and for this purpose she required teeth. Then some little germs, +which had lain dormant, concealed within the jaws, awoke one after +another, like faithful workmen when they hear the striking of the +clock. Each set to work in his little cell, and with the help of some +phosphorus and some lime, it began to make itself a kind of white +armour, as hard as a stone, which grew larger from day to day. + +You know what lime is; that sort of white pulp which you have seen +standing in large troughs where the masons are building houses, andwhich +they use in making mortar; it is with this that your little +masons build your teeth. + +As to phosphorus, I am afraid you may never have seen any; but you may +have heard it spoken of. It is sold at the druggist's in the form of +little white sticks, about as thick as your finger; they have a +disagreeable, garlicky smell, and are obliged to be kept in jars of +water, because they seize every opportunity of taking fire; so I advise +you, if ever you do see any phosphorus, not to meddle with it--for in +burning, it sticks closely to the skin, and there is the greatest +difficulty in the world in extinguishing it, and the burns it makes +are fearful. I give you this caution, because phosphorus possesses a +very curious property, which might attract little girls. Wherever it +is rubbed, in the dark, on a door, or on a wall, it leaves a luminous +trail of a very peculiar appearance, which has been called +phosphorescent, from the name of the substance which produces it. And +in this way one can write on walls in letters of fire, to the terror +of cowards. Now, come; if you will promise to be very wise, and only +to make the experiment when your mamma is present, I will teach you +how to make phosphorescent lights without having to go to the +druggist's! There is a small quantity of phosphorus in lucifer matches, +which their garlicky smell proves. Rub them gently in the dark on a +bit of wood, and you will see a ray of light which will shine for some +moments. But mind, you must not play at that game when you are alone; +it is a dangerous amusement, and one hears every day of terrible +accidents caused by disobedient children playing with lucifer matches. +And while we are on the subject, let me warn you against putting them +into your mouth. Phosphorus is a poison, and such a powerful one that +people poison rats with bread-crumb balls in which it has been +introduced. + +"Oh dear me! and that poison makes part of our teeth?" + +Exactly so, and it even forms part of all our bones, and of the bones +of all animals; the best proof of which is, that the phosphorus of +lucifer matches has been procured out of bones from the slaughter-house. +One could make it from the teeth of little girls if one could get +enough of them. + +Now I see what puzzles you, and well it may. You are asking yourself +how those little tooth-makers, the gums, get hold of this terrible +phosphorus, which is set on fire by a mere nothing, and which we dare +not put into our mouths; where do they find the lime which I also +protest is not fit to eat, and yet of which we have stores from our +heads to our feet? + +It is very surprising, too, to think of its being forthcoming in the +jaws just when it is wanted there. + +You begin to perceive that there are many things to be learnt before +we come to the end of our history, and that we find ourselves checked +at every step; now listen, for we are coming to something very +important. + +In distant country-seats, where people are thrown entirely upon their +own resources, they must be provided beforehand with all that is +requisite for repairing the building; and there is, accordingly, a +person called a steward, who keeps everything under lock and key, and +distributes to the workmen whatever materials they may require. Thus, +the steward gives tiles to the slater, planks to the carpenter, colors +to the painter, lime and bricks to the mason--the very same lime that +we have in our teeth--in fact, he has got everything that can be wanted +in his storehouse, and it is to him that every one applies in time of +need. + +Now our body also is a mansion, and has its steward too. But what a +steward--how active! what a universal genius I how inefficient by +comparison are the stewards of the greatest lords! He goes, he comes, +he is everywhere at once; and this really, and not as we use the phrase +in speaking of a merely active man: for the _being everywhere at +once_ is in this case, a fact. He keeps everything, not in a +storehouse, but what is far better, in his very pockets, which he +empties by degrees as he goes about, distributing their contents without +ever making a mistake, without stopping, without delaying; and returns +to replenish his resources in a ceaseless, indefatigable course, which +never flags, night nor day. And you can form no idea how many workmen +he has under his orders, all laboring without intermission, all +requiring different things--not one of them pausing, even for a +joke!--not even to say--"Wait a moment;"--they do not understand what +waiting means: he must always keep giving, giving, giving. By and by +we shall have a long account to give of this wonderful steward, whose +name, be it known, if you have not already guessed it, is Blood. + +It is he who, one fine day when he was making his round of the jaws, +found those little germs I spoke of, awake and eager for work; and he +began at once to start them with materials. He knew that phosphorus +and lime were what they needed: he drew phosphorus and lime therefore +out of his pockets,--and, to be very exact, some other little matters +too,--but these were the most important; but I cannot stop to tell you +everything at once. + +Now, where did the blood obtain this phosphorus and lime? + +I expected you to ask this, but if you want everything explained as +we go along, we shall not get very far. In fact, if I answer all your +questions I shall be letting out my secret too soon, and telling you +the end of my story almost before it is begun. + +So be it, however; perhaps you will feel more courage to go on, when +you know where we are going. + +The steward of a country-house distributes tiles, planks, paint, bricks, +lime; but none of these things are his own, as you know; he has received +them from his master: and, in the same way, our steward has nothing +of his own: everything he distributes comes from the master of the +house, and as I have already told you, this master is the stomach. As +fast as the steward distributes, therefore, must the master renew the +stores--and renew them all, for unless he does this, the work would +stop. In proportion as the blood gives out on all sides the contents +of his pockets, the stomach must replenish them, and fill them with +everything necessary, or there would be a revolution in the house. +Now, as there can be nothing in the stomach but what has got into it +by the mouth, it behooves us to put into the mouth whatever is needed +for the supply of our numerous workmen; and this is why we eat. + +I perceive that I have plunged here into an explanation out of which +I shall not easily extricate myself, for I can guess what you are going +to say next. When you began to cut your teeth, you had eaten neither +phosphorus nor lime, as nothing but milk had entered your mouth. + +That is true. Neither then, nor since then, have you eaten those things, +and what is more, I hope you never will. And yet both must have got +into your mouth, for without them your teeth could never have grown. +How are we to get out of this puzzle? + +Suppose now, for a moment, that instead of phosphorus and lime, +thelittle workmen in your jaws had asked the blood for sugar to make the +teeth with. Fortunately this is only a supposition; otherwise I should +be in great fear for the poor teeth: they would not last very long. +Suppose, further, that instead of your eating the lump of sugar which +was destined to turn into a tooth, your mamma had melted it in a glass +of water, and had given it to you to drink; you could not say you had +eaten sugar, and yet the sugar would really have got into your stomach, +and there would be nothing very wonderful if the stomach had found it +out and given it to the blood, and the blood had carried it off to the +place where it was wanted. Now, allowing that the lump of sugar was +very small, and the glass of water very large, the sugar might have +passed without your perceiving it, and yet the tooth would have grown +all the same, and without the help of a miracle. + +And this is how it was. In the milk which you drank as a baby there +were both phosphorus and lime, though in very small quantities. There +were many other things besides; everything of course that the blood +required for the use of its work-people, because at that time the +stomach was only receiving milk, and yet all the work was going on as +usual. + +And therefore, my dear child, whenever in the course of our studies, +you hear me describe such and such a thing as being within us, say +quietly to yourself, "that also was in the milk which nourished me +when I was a baby." + +Of course, the same things are in what you eat now; only now they come +in a form more difficult to deal with, and the labor of detaching them +from the surrounding ingredients is much greater. The whole business +indeed of this famous machine which we are studying consists in +unfastening the links which hold things together, and in laying aside +what is useful, to be sent to the blood divested of the refuse. The +stomach was too feeble in your infancy to have encountered the work +it has to do now. It is for this reason that God devised for the benefit +of little children that excellent nourishment--milk--which contains, +all ready for use, every ingredient the blood wants; and is almost, +in fact, blood ready made. + +Only think, my child, what you owe to her who gave you this nourishment! +It was actually her blood she was giving you; her blood which entered +into your veins, and which wrought within you in the wonderful way +which I have been describing. Other people gave you sugar-plums, kisses, +and toys; but she gave you the teeth which crunched the sugar-plums, +the flesh of the rosy cheeks which got the kisses, and of the little +hands which handled the toys. If ever you can forget this, you are +ungrateful indeed! + +Now, beware of going on to ask me how we know that there are so many +sorts of things in milk, or I shall end by getting angry. Question +after question; why, you might drive me in this way to the end of the +world, and we should never reach the point we are aiming at. We have +already traveled far away from the teeth, concerning which I wanted +to talk to you at this time, but our lesson is nearly over and we have +scarcely said a word about them! One cannot learn everything at once. +Upon the point in question you must take my word; and as you may +believe, I would not run the risk of being contradicted before you, +by those who have authority on the subject. + +Let it suffice you, for to-day, to have gained some idea of the manner +in which the materials which constitute our bodies are manufactured +within us. We have got at this by talking of the teeth; to-morrow, it +may be the saliva, the next day something else. What I have now told +you will be of use all the way through, and I do not regret the time +we have given to the subject. If you have understood that well; the +time has not been lost. + + + +LETTER V. + +THE TEETH _(continued.)_ + +My thoughts return involuntarily to the subject I last explained to +you, my dear child, and I find that I have a great deal to say about +it still. + +You see now, I hope, that we have something else to consult besides +a dainty taste when we are eating; and that if we are to work to any +good purpose we must think a little about this poor blood; who has so +much to do, and who often finds himself so much at fault, when we send +him nothing but barley-sugar and biscuits for his support. It is not +with such stuff as that, as you may well imagine, that he can be enabled +to answer satisfactorily to the constant demands of his little workmen, +and we expose him to the risk of getting into disgrace with them, if +we furnish him with no better provisions. + +And who is the sufferer? Not I who am giving you this information, +most certainly. + +Now, when children hesitate about eating plain food, and fly from beef +to rush at dessert, they act as a man would do who should begin to +build by giving his workmen reeds instead of beams, and squares of +gingerbread instead of bricks. A pretty house he would have of +it;--just think! + +On the contrary, what your mother asks you to eat, my dear little +epicure, is sure to be something which contains the indispensable +supplies for which your blood is craving; for people knew all about +this by experience long before they could explain the why and the +wherefore. But now that you are so much better informed than even the +most learned men were a century ago, pouting and wry faces at table +are no longer excusable, and I should be sadly ashamed of you if I +should hear you continued to make them. + +And this is what I was more particularly thinking of just now, when +I took up my pen again. No doubt it is very amusing to be able to look +clearly into one's frame, and see what goes on inside, but the amusement +anything affords is the least important part of it; you have begun to +find this out already, and you will find it out more and more every +day. What seems to me one of the great advantages of the study we have +begun together is, that at every step you take you will meet with the +most practical and useful instruction, as well as the most unanswerable +reasons for doing what your parents ask you to do every day. + +To obey without knowing why is certainly possible, and may be done +happily enough. But we obey more readily and easily when we understand +the reason for doing so; and a duty which one can satisfy oneself +about, forces itself upon one as a sort of necessity. And what can +throw a stronger light on our duties than a thorough acquaintance with +ourselves? + +It is upwards of two thousand two hundred years ago (and that is not +yesterday, you must own!) since one of the greatest minds of the +world--Socrates--never forget that name--taught his disciples, as a +foundation precept, this apparently simple maxim, "Know thyself." He +meant this, it is true, in a much higher sense than we are aiming at +in these conversations of ours, but his rule is so practical, that +although you have only as yet taken a mere peep into one small corner +of self-knowledge, you find, if I am not much mistaken, that your heart +has beaten once or twice rather faster than it did before. Was I wrong, +in saying from the beginning, that we become better as we grow in +knowledge? Is it not true that you have felt more tenderly than ever +towards her who nourished you with her milk, since I explained to you +the value of milk; and that you have kissed your mother's hand all the +more lovingly since you heard my history of the hand? To tell you the +truth, if you had not done so, I should have been dissatisfied both +with you and myself. + +And wait! While we are talking thus, another thought has come into my +head about hands and nurses, which I must tell you of. + +There is something of the nurse, my child, in those who take the best +fruits of their intellect and heart, and transform them, as it were, +into milk, in order that your infant soul may receive a nourishment +it will be able to digest without too much effort. In this way their +very soul enters into you, and it is but fair that you should reward +them as they deserve. Young as you are, too, you have a recompense in +your power: one more acceptable even than Academic prizes--of which +it is indispensable not to be too avaricious--you can give them your +love. + +Besides, it is not only hands but heads that are at work for you, and +of these many more than you suppose; and your debt of gratitude is as +much due to the one as to the other. + +Perhaps my first letter may have led you to suppose that I was inclined +to laugh at what I called learned men; and they are perhaps a little +to blame for not thinking often enough about little girls; but +nevertheless these men are of the greatest use to them in an indirect +way. You owe them much, therefore, and without them could have known +nothing of what I am teaching you. It is very grand for us, is it not, +to know that there is phosphorus and lime in our teeth? But it took +generations of learned men, and investigations and discoveries without +end, and ages of laborious study, to extract from nature this secret +which you have learnt in five minutes. And whatever others you may +learn hereafter, remember that it is the same story with all. While +profiting, therefore, at your ease, by all these conquests of science, +I would have you hold in grateful recollection those who have gained +them at so much cost to themselves: almost always at the expense of +their fortune, sometimes at the peril of their lives. + +There they are, observe, a little knot of men with no sort of outward +pretension. They speak a language which scares children away. They +weigh dirty little powders in apothecaries' scales; steep sheets of +copper in acid-water; and watch air-bubbles passing through bent glass +tubes, some of which are as dangerous as cannon balls. They scrape old +bones, and slice scraps no bigger than a pin's head. They keep theireyes +fixed for hours upon things they are examining through microscopes +of a dozen glasses, and when you go to see what they are looking at, +you find nothing at all. To see them at work, in what they call their +laboratories, you would say that they were a set of madmen. But at the +end, it is found, some fine day, that they have changed the face of +the earth; have worked revolutions before which emperors and kings bow +in respect; have enriched nations by millions at a time; have revealed +to the human race, divine laws of which it had hitherto been ignorant; +finally, have furnished the means of teaching little boys and girls +some very curious things, which will make them more agreeable as well +as reasonable. And this is a benefit not to be despised, since these +children are destined one day to become fathers and mothers, and so +to govern the next generation; and the better they themselves are +instructed, the better this will be done. + +But now let us go back to the poor teeth, whom we seem to have forgotten +altogether. However, we knew very well that they would not run away +meantime. + +I told you before that it was their business to dress and prepare +whatever was presented to them, but the reception they bestow is not +one which would suit every body's taste, for it consists in being made +mince-meat of And in order to do their work in the best way possible +they divide their labor; some cut up, others tear, and others pound. + +First, there are those flat teeth in front of the two jaws, just below +the nose. Touch yours with the tip of your finger; you will find that +they terminate in sharp-edged blades, like knives. These are called +_incisors,_ from the Latin word _incidere,_ which means to cut, and it +is with them we bite bread and apples, where the first business is to +cut. It is with the same teeth that lazy little girls bite their thread, +when they will not take the trouble to find their scissors; and, by the +by, this is a very bad trick, because by rubbing them one against +another in this manner we wear them out, and, as you will soon discover, +worn-out teeth never grow again. + +The next sort are those little pointed teeth, which come after the +_incisors,_ on each side of both jaws. You will easily find them; +and if you press against them a little, you will feel their points. +If we call the first set the knives of the mouth, we may call these +its forks. They serve to pierce whatever requires to be torn, and they +are called _canine_ teeth, from the Latin word _canis_, a dog, because +dogs make great use of them in tearing their food. They place their paws +upon it, and plunging the canine teeth into it, pull off pieces by a +jerk of the head. Look into the mouth of papa's dog: you will recognize +these teeth by their rather curved points. They are longer than the +rest, and are called fangs. I do not know, after all, why they have +chosen to name these teeth _canine_, as all carnivorous animals have the +same fangs, and in the lion, the tiger, and many other species, they are +much more developed and sharper than in the dog. In cats they are like +little nails. However, the name is given, and we cannot alter it. + +The last teeth, which are placed at the back of the jaw, are called +molars, from the Latin word _mola_, which means a millstone. + +You must be prepared to meet with several Latin words as we go on; but +never mind; this will give you the opportunity of learning a little +Latin, and so of keeping your brother in order, if he ever looks down +upon you because he is learning Latin at school. Formerly, all learned +men wrote in Latin, and as they ruled supreme in all such subjects as +those we are discussing, they gave to everything such names as they +pleased, without consulting the public, who did not just then trouble +their heads about the matter. Now they give Greek names, which can +hardly be called an improvement; but if they ever wish to attract the +attention of little girls they must translate their hard words into +our own language. + +To return to our grinders: they perform the same office as a miller's +millstone; that is to say, they grind everything that comes in their +way. These teeth have flat, square tops, with little inequalities on +the surface, which you can feel the moment you lay your finger on them. +These are the largest and strongest of the three sets, and with them +we even crack nuts, when we prefer the risk of breaking our teeth to +the trouble of looking for the nut-crackers! + +Now, I will answer for it that you cannot explain to me why we always +place what is hard to break between the _molars,_ and never employ +the _incisors_ in the work? And yet everybody does this alike--from +the child to the grown-up man--and all equally without thinking of +what they are doing. + +I will tell you the reason, however, if you will first tell me why, +when you are going to snip off the tip of your thread (which offers +very little resistance), you do it with the point of your scissors; +whereas you put any tough thing which is likely to resist strongly (a +match, for instance) close up to their hinge; particularly if you have +no scruple about spoiling the scissors, by the way! + +If you were a grown-up lad, and I were teaching you natural philosophy, +I should have here a fine opportunity for explaining what is called +_the theory of the lever_. But I think _the theory of the lever_ would +frighten you; so we must get out of the difficulty in some other way. + +I find, however, that I have been joking so much as I went along, that +I have but little space left, and feel quite ashamed of myself. We +seem quite unlucky over these teeth. + +I have already been scolded by people who are not altogether wrong in +accusing me of losing my time in chattering, first of one thing and +then of another. They complain that by thus nibbling at every blade +of grass on the way-side we shall never get to the end of our journey; +and there is some truth in what they say. Still, I will whisper to you +in excuse that I thought we might play truant a little bit while we +were on familiar ground, where naturally you were sure to feel a +particular interest in everything. The hand, the tongue, the +teeth--these are all old friends of yours--and I thought you would +like to hear all about them. By-and-bye we shall be in the little black +hole, and then we shall get on much more rapidly. + + + +LETTER VI. + +THE TEETH _(continued)._ + +I left off at the _molars_, which are the teeth one selects to +crack nuts with; and if I remember rightly, we talked about different +ways of cutting with scissors. + +Let us look at the subject from a distance, that we may understand it +more clearly. Let us imagine a horse drawing a heavy cart slowly along. +Ask it to gallop, and it will answer, "With all my heart! but you must +give me a lighter carriage to draw." And now fancy another flying over +the ground with a gig behind it. Ask it to exchange the gig for the +cart, and it will say, "Yes; but then I shall have to go slowly." + +Whereby you see that with the same amount of strength to work with, +one has the choice of two things: either of conquering a great +resistance slowly, or a slight one quickly. + +And it is partly on this account, dear child, that I teach you so +gradually; for young heads, fresh to the work, are less easily drawn +along than others, and have but a certain amount of strength. + +Hitherto all has been clear as the day. Now take your scissors in your +left hand; hold the lower ring of the handle firmly between your thumb +and closed hand, so that the blade shall remain straight and immovable: +then with your other hand cause the upper ring to go up and down, and +watch the blade as it moves. The whole of it moves at once, and is put +in motion by the same power--viz., your right hand. But the point makes +a long circuit in the air, while the hinge end makes only a very little +one--indeed, moves almost imperceptibly: and, as you may imagine, a +different sort of effort is required from the motive power (your hand) +according as resistance is made at the point or at the hinge. The point +goes full gallop: it is the horse in the gig; the light work is for +him. The hinge moves slowly; it is the cart-horse, and takes the heavy +labor. + +I hope I have made you understand this, for it explains the cracking +of our nut, though you may not suspect it. Move your scissors once +more in the same way. Now, you have before you the pattern of the two +jaws on one side of your face, from the ear to the nose; the upper +one, which never moves (as you may convince yourself by placing a +finger on your upper lip when you either speak or eat), and the lower +one which goes up and down. Two pairs of scissors set points to points +give you the whole jaw. The _incisors_ are at the points, they +gallop up and down, and are worthless for doing hard work; the +_molars_ are at the hinges, and move slowly; and if anything tough +has to be dealt with, it comes to them as a matter of course; hence +they are the nutcrackers. You must own that it is pleasant to reflect +thus upon what we are doing every day, and the next time you see a +stonemason moving stones of twenty times his own weight with his iron +bar, ask your papa to explain to you the principle of the lever. After +what I have told you, you will understand it very readily, or at least +enough of it to satisfy your mind. + +But, besides this power of moving up and down, the lower jaw possesses +another less obvious one, by means of which it goes from right to left. +This is precisely what naughty children make use of when they grind +their teeth: not that I mean this remark for you, for I have a better +opinion of you than to suppose you do such things. Those who make such +bad use of their jaws deserve to lose the power of ever moving them +thus, and then they would find themselves sadly at a loss how to chew +their bread--for their _molars_ would be of but little service +to them in such a case; as it is chiefly by this second action of the +jaw that the food is pounded. Try to chew a bit of bread by only moving +your jaw up and down, and you will soon tire of the attempt. + +One word more to complete my description of the teeth: that portion +of them which is in the jaw is called the _root_; and the _incisors_, +which cannot work hard because, like the gig-horses, they have but +little resisting power, possess only small and short roots; whereas the +_canines,_ whose duty it is to tear the food sideways, would run the +risk of being dragged out and left sticking in the substances they are +at work upon, if they were not well secured; these, therefore, have +roots which go much deeper into the jaw, and in consequence of this they +give us more pain than the others when the dentist extracts them: those +famous _eye-teeth_, which so terrify people on such occasions, are the +_canines_ of the upper jaw, and lie, in fact, just below the eye. + +The _molars_ meanwhile would be in danger of being shaken in the +sideway movement, while chewing: so they do as you would do if you +were pushed aside. Now you would throw out your feet right and left +in order to steady yourself, and thus the molars, which have always +two roots, throw them out right and left for the same purpose. Some +have three, some four, and they require no less for the business they +have to do. + +Above the root comes what is called the crown; that is the part of the +tooth which is exposed to the air; the part which does the work, and +which bears the brunt of all the rubbing. Now, however hard it may be, +it would soon end in being worn out by all this fun if it were not +covered by a still harder substance, which is called _enamel_. +The _enamel_ which forms the coating of china plates, and which +you can easily distinguish by examining a broken plate, will give you +a very exact idea of it. It is this enamel which gives the teeth the +polish and brilliancy we so much admire, and it is desirable to be +very careful of it, not out of vanity, though there is no objection +to a little vanity on the subject, but because the enamel is +the protector of the teeth, and when that is destroyed, you may say +good-bye to the teeth themselves. All acids eat into the enamel, as +vinegar or lemon-juice does into marble; and one of the best means of +preserving this protecting armor of the teeth is never to eat the unripe +windfalls of fruit, which I have seen unreasonable children pick up in +orchards and devour so recklessly. They give sufficient warning, by +their acidity, that they are not fit for food, and when this warning is +neglected, they take their revenge by corroding the enamel of the +teeth; not to speak of the disturbance which they afterwards cause in +the poor stomach. + +I said that without this coating of enamel, the teeth would be +prematurely worn out, the reason of which is, that the teeth have not +the property of growing again, as the nails and hair have. When those +little germs of which I spoke when we began to describe the teeth, +have finished their work, they perish and fall out, like masons who, +when they have built the house, take their departure forever. + +But the "forever" wants explanation. For such stern conditions would +fall hard on very little children, who, not having come to their reason, +cannot be expected to understand the great value of their teeth, and +take all the care they need of them. So to them _a second_ chance +is given. + +Your first teeth, the _milk-teeth_, as they are called, count for +nothing: they are a kind of specimen, just to serve while you are very +young. + +When you are approaching what is called the age of reason, (and this +word implies a great deal, my dear child,) the real teeth, the teeth +which are to serve you for life, begin to whisper among themselves, +"Now, here is a little girl who is becoming reasonable, and who will +soon, or else never, be fit to take charge of her teeth." No sooner +said than done: other masons set to work in other cells, placed under +the first set, and as the permanent teeth keep growing and growing, +they gradually push out the milk-teeth, which were only keeping their +places ready for them till they came. + +This is just your case at present, and you now understand your +responsibility, and how necessary it is to preserve those good teeth +which have placed so generous a confidence in your care of them, and +which, once gone, can never be replaced. + +You have no loss by the exchange; you had twenty-four at first, you +will now have twenty-eight. Twenty-eight, did I say? nay, you will +have thirty-two; but the last four will come later still. The last +_molars_ on each side, above and below, in both jaws, will not +make their appearance till you are grown up. They are a fastidious and +timid set, and will not run any risks; and they are called +_wisdom-teeth_, because they do not appear till we are supposed +to have arrived at years of discretion. Some people do not cut them +before they are thirty, and you will agree that, if they have not +become wise by that time, they have but a very poor chance of ever +being so! + +There is much more still to be said about the teeth; but I think I +have told you quite enough to teach you the importance of these little +bony possessions of yours, which children do not always value as they +deserve, and whose safety they endanger as carelessly as if they had +fresh supplies of them ready in their pockets. If so many skilful +contrivances have been devised for enabling us to masticate our food +properly, it is clear that this process is not an unimportant one. +Those, therefore, who swallow a mouthful after two or three turns, +forget that they are thereby forcing the stomach to do the work the +teeth have neglected to do, and this is very bad economy, I can assure +you. You will see hereafter, when we speak about animals, that by a +marvellous compensation of nature, the power of the stomach is always +great in proportion to the _in_efficiency of the teeth, and that +by the same rule, it is weakest when the jaws are best furnished. Now, +no jaw is more completely furnished than the human one; it is clear, +then, that it should do its own work and not leave it to be done by +those who are less able: and the little girl who, in order to finish +her dinner more quickly, shirks the use of her teeth, and sends food, +half chewed, into her stomach, is like a man who, having two servants, +the one strong and vigorous, the other feeble and delicate, allows the +first to dawdle at his ease, and puts all the hard work on the other. +He would be very unjust in so doing, would he not? And as injustice +always meets with its reward, his work is sure to be badly done. + +Now, the work in question consists in reducing what we eat into a sort +of pulp or liquid paste, from which the blood extracts at last whatever +it requires. But the teeth may bite and tear the materials as they +please, they can make nothing of them but a powder, which would never +turn into a pulp, if during their labors they were not assisted by an +indispensable auxiliary. To make pap for infants what do we add to the +bread after it is cut in little bits? Without being a very clever cook, +you will know that it is water which is wanted. And thus, to assist +us in making pap for the blood, Providence has furnished us with a +number of small spongy organs within the mouth, which are always filled +with water. These are called _salivary glands_. This water oozes +out from them of itself, on the least movement of the jaw, which presses +upon the sponges as it goes up and down. The name of this water, as +I need scarcely tell you, is _saliva_. + +When I call it water, it is not merely from its resemblance; _saliva_ is +really pure water with a little _albumen_ added. Do not be afraid of +that word--it is not so alarming as it appears to be. It means simply +the substance you know as the _white of egg_. There is also a little +soda in the water, which you know is one of the ingredients of which +soap is made. And this explains why the saliva becomes frothy, when the +cheeks and tongue set it in motion in the mouth while we are talking; +just as the whites of egg, or soapy water, become frothy when whipped up +or beaten in a basin. + +But the albumen and the soda have not been added to the saliva, in our +case, merely to make it frothy; that would have been of very little +use. They give to the water a greater power to dissolve the food into +paste, and thus to begin that series of transformations by which it +gradually becomes the fine red blood which shows itself in little drops +at the tip of your finger when you have been using your needle +awkwardly. + +When once minced up by the teeth and moistened by the saliva, the food +is reduced to a state of pulp, and having nothing further to do in the +mouth, is ready to pass forward. But getting out of the mouth on its +journey downwards is not so simple an affair as getting into it by the +_front door_, as it did at first. Swallowing is in fact a complicated +action, and not to be explained in half a dozen words, and I think we +have already chatted enough for to-day. I only wish I may not have tired +you out with these interminable teeth! But you may expect something +quite new when I begin again. + + + +LETTER VII. + +THE THROAT. + +You remember a certain door-keeper, or porter, of whom we have already +spoken a good deal, who resides in the mouth--the sense of taste, I +mean? + +Well, it is a porter's business to sweep out the entrance to a house, +and you may always recognize him in the courtyard by his broom. + +And accordingly our porter too has a broom specially placed at his +service, namely, the tongue; and an unrivalled broom it is--for it is +self-acting, never wears out, and makes no dust--qualities we cannot +succeed in obtaining in any brooms of our own manufacture. + +When the time has come for the pounded mouthful (described in the last +chapter) to travel forward (the teeth having properly prepared it), +the broom begins its work; scouring all along the gums, twisting and +turning right and left, backwards and forwards, up and down; picking +up the least grains of the pulp which have been manufactured in the +mouth; and as the heap increases, it makes itself into a shovel--another +accomplishment one would scarcely have expected it to possess. What +it gathers together thus, rolls by degrees on its surface into a ball, +which at last finds itself fixed between the palate and the tongue in +such a manner that it cannot escape; at which moment the tongue presses +its tip against the upper front teeth, forms of itself an inclined +plane, and--but stop! we are getting on too fast. + +At the back of the mouth, (which is the antechamber, as we said before,) +is a sort of lobby, separated from the mouth by a little fleshy +tongue_let_, suspended to the palate, exactly like those tapestry +curtains which are sometimes hung between two rooms, under which one +is enabled to pass, by just lifting them up. + +If this lobby led only from the mouth to the stomach, the act of +swallowing would be the simplest thing in the world; the tongue would +be raised, the pounded ball would glide on, would pass under the +curtain, and then good-bye to it. Unfortunately, however, the architect +of the house seems to have economized his construction-apparatus here. +The lobby serves two purposes; it is the passage from the mouth to the +stomach, as well as from the nose to the lungs. + +The air we breathe has its two separate doors there--one opening +towards the nose, the other towards the lungs; through neither of which +is any sort of food allowed to pass. But, as you may imagine, the food +itself knows nothing of such spiteful restraints, and it is a matter +of perfect indifference to it through which of the doors it passes. +Not unlike a good many children who, though they are reasonable +creatures, will push their way into places where they have been +forbidden to go; and who can expect a pulpy food-ball to be more +reasonable than a child? It was necessary, therefore, so to arrange +matters that there should be no choice on the subject; that when the +food-ball got into the lobby it should find no door open but its own, +namely, that which led to the stomach. And that is exactly what is +done. + +You have not, perhaps, remarked that in the act of swallowing, something +rises and contracts itself at the same moment in your throat, producing +a kind of internal convulsion which jerks whatever is inside. People +do not think about it when they are eating, because it is an involuntary +action, and their attention is otherwise engaged. + +But try to swallow when there is nothing in your mouth, and you will +perceive what I mean at once. + +Now, imagine our lobby at the back of the throat as a small closet, +with a doorway in its wall, half-way up, the doorway being closed by +a curtain. In the ceiling is a hole, which leads to the nose; in the +floor two large tubes open out; the front one leading to the lungs, +the one behind, to the stomach. + +Now swallow, and I will tell you what happens. The curtain rises up +and clings to the ceiling, and thus the passage to the nose is stopped +up. The lung-tube rises along the wall, and hides itself under the +door, contracting itself, and making itself quite small, as if it +wished to leave plenty of room for the mouthful of food which is about +to pass over it; and, for still greater security, at the very moment +it rises, it pushes against a small trap-door which shuts up its mouth. +No other road remains, therefore, but through the tube which leads to +the stomach; the pulpy mouthful drops straight therein, without risk +of mistake, and when it is once there, everything readjusts itself as +before. + +These are very ingenious contrivances, and I will venture to say that +if we would but study the wonders of the marvellous and varied machinery +which is constantly at work in our behalf within us, we should be much +better employed than in learning things from which no practical good +can be derived. Moreover, we should be ashamed to trust, like the lower +animals, only to our instinct, (which, after all, is much less developed +in us than in them,) for blindly escaping the thousand chances of +destruction that beset a structure so fragile and delicate in its +contrivances as the human body. Besides, it is not only our own +machinery that is entrusted to us, we are liable to be responsible for +that of others, whose development it is our duty to guard and watch; +and how can we do this with a safe conscience, if we are ignorant of +the construction, the action, the laws of all sorts which the great +Artificer has, so to speak, made use of in forming our bodies? + +When you, in your turn, are a mother, you dear little rogue, who sit +there opening wide your bright eyes, and not comprehending a word of +what I am saying, you will be glad that you were taught when you were +little, how your own little girl ought to be managed. You will find +a hundred opportunities of making good use, in her behalf, of what you +and I are learning together, and in the meantime there is no reason +why you should not yourself profit by the knowledge you have gained. + +I am quite sure, for instance, that in repeating to your child the +simple rule of politeness, with which everybody is acquainted, "_Never +talk when you are eating_," you will be very careful to add, "_and +especially when you are swallowing_," for reasons I am about to detail. + +When we want to speak we have to drive the air from the lungs into the +mouth, and our words are sounds produced by this air as it passes +through. This is the reason why I advise you to go on gently, and make +the proper stops in reading aloud: to _take breath_, in fact, as +it is called; otherwise, breath would all at once fail you, and you +would be obliged to stop short in the middle of a sentence and wait +like a simpleton till you had refilled the lungs with air by breathing. +It was for this purpose, also, and not for mere economy's sake, as you +may have thought, that the little cross-road of four doors has been +placed at the back of the mouth, enabling it to communicate at pleasure +with either the lungs or the stomach. It is a dangerous passage for +food-parcels making their way to the stomach; but if you could +substitute for it, as it may have occurred to you to do lately, a +simple tube going directly to the stomach,--behold! you would find +yourself dumb;--a serious misfortune, eh? for a little girl! But come, +I am quizzing too much, so console yourself. I know many grown-up +people who would be at least as sorry as yourself. + +To return to our subject. We have said that, in order to guard against +accidents, the lung-tube is closed at the moment we are about to +swallow. But if by any unlucky chance the air is coming up from the +lungs at the same moment, it must have a free passage. Its tube cannot +help returning to its place; the little trap-door which shuts up the +opening opens whether or no, and then adieu to all the precautions of +good Mother Nature! The mouthful when it drops, falls outside of its +proper tube--that is to say, into the other, which is exactly in front +of it, and we find that we have _swallowed the wrong way_. + +You know what happens in such a case. You cough and cough till you are +torn to pieces, till you grow scarlet, or even blue in the face; till +you lose your breath; till your body trembles; till your eyes start +out of their sockets. Let who will be there, there is no resource but +to hide your face in your handkerchief. The tube, which was only made +for the passage of air, on finding an intruder forcing an entrance, +does its utmost to drive it back through the door. Then the lungs, +which would be destroyed by its getting to them, come to the assistance +of the faithful servant who is struggling for their protection: they +agitate themselves violently, and send forth gusts of air which drive +all before them. Thence arises the cough, and by this means at last +the enemy is thrust out of the mouth, like dust before the wind. And +it is only when the passages are cleared that the storm subsides. But +the commotion is no laughing matter, I assure you; for if one had +swallowed a little _too far_ the wrong way, or if the substance +swallowed had been too heavy for the air-tube, aided by the lungs, to +eject within a certain time, death would have ensued: instances of +which are by no means unknown. Nature does nothing in vain; this is +no case of a man frightened by a mouse. When you find your whole being +concentrating its efforts to one point, and betraying such distress, +at an accident apparently so trifling, you may be sure there is danger, +and real danger too; and if you doubt it, that makes no +difference--happily for you. + +Now you have learned why little girls should not attempt to talk and +swallow at the same time, and, I may add, still less laugh; for +laughingis a kind of somersault, performed by the lungs, and is always +accompanied by the ejectment of a great deal more breath than is +necessary in speaking, so that the jerks it occasions derange still +more the wise provisions made to protect life whenever we swallow +anything, and therefore we are more apt to swallow the wrong way while +laughing than while speaking. + +Need I say that we ought equally to guard against making others laugh +or talk; or exciting, or frightening them, while they are swallowing; +in short, avoid doing anything to create a sudden shock which might +suddenly force the air out of their lungs, and cause them in the same +manner to swallow the wrong way? Politeness requires this from us, and +what I have now said will fix the lesson still more strongly on your +mind. What would become of you if you were to see a person die in your +presence in consequence of some foolish joke, however apparently +innocent? + +Not to conclude with so painful a picture, I will, before we part, +give you the right names of the _curtain_, the _lobby_ or _closet_, and +the _tubes_ of which we have been speaking. + +The curtain is called the _Soft Palate_. + +The lobby, the _Pharynx_. + +The tube which leads to the stomach, the _Aesophagus_. + +The tube leading to the lungs, the _Larynx_. + +The opening of this tube is the _Glottis_, and the little trap-door +which closes it when one swallows, is the _Epiglottis_. + +You must excuse my attempting to explain the meanings of all these +names; it would take me too long to do so. After all, the mere names +are nothing. If I have succeeded in making you understand how all the +different parts act, you may call them what you like. + +Here we will rest. We are now on our way to where we shall see the +large apartments, and be introduced to the master, that head of the +house, whom no one can approach without so many ceremonies. + + + +LETTER VIII. + +THE STOMACH. + +Once in the _oesophagus_ (you remember this is the name of the tube +which leads to the stomach), the mouthful of food has nothing to do but +to proceed on its way. All along this tube there is a succession +of small elastic rings, [Footnote: Properly, _contractile circular +fibres_.] which contract behind the food to force it forward, and +widen before it to give it free passage. They thus propel it forward, +one after another, till it reaches the entrance to the stomach, into +which the last ring pushes it, closing upon it at the same time. + +Have you ever observed a worm or a leech in motion? You see a successive +swelling up of the whole surface of its body, as the creature gradually +pushes forward, just as if there was something in its inside rolling +along from the tail to the head. Such is precisely the appearance which +the _oesophagus_ would present to you, as the food passes down it, if +you had the opportunity of seeing it in action; and this has been called +_the vermicular movement_, in consequence of its resemblance to the +movement of a worm. + +Here I wish to draw your attention to the very important fact, that +this movement is in one respect of a quite different nature from that +of your thumb when you take hold of a bit of bread, or that of your +jaw when you bite with your teeth, or of your tongue, &c., when you +swallow. All these actions belong to yourself, to a certain extent; +they are voluntary, and under your own guidance; that is, you may +perform them or not, as you choose. There is a constant connexion +between you and them, and you knew what I meant at once as I named +each of them in succession. But in speaking of this other movement we +enter upon another world, of which you know nothing. Here is the black +hole of which I spoke. The little rings of the _oesophagus_ perform +their work by themselves, and you have no power in the matter. Not +only do they move independently of you, but were you to take it into +your head to stop them, it would be about as wise a proceeding as if +you were to talk to them. We will speak hereafter, in another place, +of these impertinent servants, who do not recognise your authority, +and with whom we shall have constantly to do, throughout what remains +to be said on the subject of eating. The truth is, your body is like +a little kingdom, of which you have to be the queen, but queen of the +frontiers only. The arms, the legs, the lips, the eyelids, all the +exterior parts, are your very humble servants; at your slightest bidding +they move or keep still: your will is their law. But in the interior +you are quite unknown. There, there is a little republic to itself, +ruling itself independently of your orders, which it would laugh at, +if you attempted to issue them. + +This republic, to make use of another metaphor, is the kitchen of the +body. It is there they make blood, as they know how; putting it to all +sorts of uses for your advantage, it is true, but without your consent. +You are in the position of the lady of a house whose servants have +shut the door of the kitchen in her face that they may carry on their +business after their own fashion, leaving only the housemaid and +coachman at her command. It may be humiliating, perhaps, to be thus +only partially mistress at home; but what can you do, my little +demi-queen? I will tell you: make up your mind to govern the subjects +under your orders as wisely as possible; and, as to the rest, be content +with the only resource left you: viz., that of looking in at the window +of the kitchen to see what goes on there! + +The stomach is the head cook: the president of the internal republic. +He has charge of the stoves; the whole weight of affairs is on his +hands, and he provides for the interests of all. Aesop taught us this, +long ago, in his fable of "The Belly and Members." [Footnote: La +Fontaine's translation is quoted in the French original, where the +name of the fable is "_Messer Gaster_," a more correct title than our +own. _Gaster_ is a Greek word signifying stomach; and it is strictly +_the stomach_ which is _meant_ in the fable. From this comes, too, the +medical term _gastritis_, the name of a disease of the stomach.--TR.] It +is a very good fable, and was wisely appealed to once by a Roman Consul +to appease a disturbance in the State. But the application was not quite +fair in one respect; and since I have started the subject, I will +satisfy myself by explaining to you where it was wrong. The time will +not be wasted, for this fable has furnished information to a great many +people about the economy of their insides, and possibly to you; and I +should like you to know the exact truth of all the particulars alluded +to. Whether Aesop understood them all, I cannot pretend to say; but the +application by the old Roman to the quarrel between the big-wig senators +and the people was on one point decidedly unjust; for there was, as far +as facts are concerned, something to be said on behalf of the stomach, +which Consul Menenius seems not to have thought of. + +When you come to this part of the Roman history you will learn that +the Roman Senate was a large and fat stomach, which did, it is true, +furnish good nourishment to the other members of the State, but kept +the best share for itself. We may say this now without risk of offence, +it having been dead for so long a time. Our stomach is the leanest, +slightest, frailest part of our body. It is master in the sense in +which it is said in the Gospel, "Let him that is first among you be +the servant of the others." It receives everything, but it gives +everything back, and keeps nothing, or almost nothing, for itself. +Between ourselves, Consul Menenius, the advocate of the Senate, had +no business to talk to the poor wretches at Rome of any comparison +between their government and so careful an administrator of the public +good as a human stomach. He should have taken his subject of comparison +from the families of geese or ducks--animals which have no teeth. These +have strong, well-grown stomachs--true Roman senators--whose stoutness +is in proportion to the work given them to do. But man provides his +with work already prepared by chewing, supposing him to have had the +sense to chew it, of course. It was not from a comparison with man, +therefore, that Menenius ought to have got his boasted apologue, which +was but a poor jest on the subject. + +You did not expect, my dear, to come in for a lesson on Roman History +in a discussion on the stomach. But the study of nature is connected +with everything else, though without appearing to be so, and I was not +sorry to give you, incidentally, this proof of the unexpected light +which it throws, as we go along, upon a thousand questions which appear +perfectly foreign to it. Look, for example, at this old fable cited +by Menenius. For the two thousand years and upwards that it has been +in circulation, troops of historians, poets, orators, and writers of +all kinds, have passed it forward from one to the other, without having +troubled themselves to investigate the laws of nature in connection +with the stomach; therefore, not one, that I am aware of, has observed +this small error, so trifling in appearance, so important in reality, +which nevertheless is obvious to the first young naturalist who thinks +the matter over. + +But enough of the Romans. Let us return to our master--the head cook, +if you choose to call him so. + +I was telling you just now that he managed the stoves, and you may +have thought that I was merely using similes, as I am apt to do. But +not so: it is quite true that he cooks; and so now tell me, if you +can, whence he gets his fire to cook with, or rather, to speak more +correctly, who gives it to him? + +Now you are quite puzzled, so I must help you out. + +In the mansion we were talking about some time ago, to whom would anyone +who wanted to light a fire, apply for wood? + +I think you can answer this yourself, for you cannot have forgotten +our famous steward, who gives everything to everybody. But, you will +wonder, I dare say, how the blood can carry wood in his pockets. +Wood? Ay, and real wood too, as we shall soon see: but it is not wood +we are talking about now. The blood has something more to the purpose +than wood in his pockets, for he has heat ready made. So when the +stomach wishes to set to work, it appeals to the blood, which comes +running from all parts of the body, and heats it so effectually that +everything within is really and actually cooked. This is why one feels +a sort of slight shudder down the back when the stomach has a great +deal to do at once, for the blood being called for in a hurry, comes +rushing along in great gushes, and carries with it the heat from the +other parts of the body. + +It is for this reason, too, that it is so dangerous to bathe when the +stomach is at work cooking, because the cold of the water drives +suddenly back all the blood which has accumulated around the little +saucepan, and this causes such a shock in the body that people often +die of it. + +Do not ask me, to-day, where this heat of the blood comes from; we +will speak of that hereafter. But I may tell you at once that our dear +steward is not a bit cleverer in this matter than other people, and +obtains his heat, like the humblest mortal, by burning his wood. Do +not puzzle yourself to find out how. Enough that he burns it as we do, +and by a similar process. + +Well, in one way or another, the master cook has his fire at command. +You know also, already, what it is he has to get cooked; namely, the +pulpy stew, which has begun in the mouth by chewing, and which it is +his business now to finish perfectly. Now see what a cook does who has +got her stew over the fire. She turns and turns it again and again, +and shakes the saucepan from time to time, that the ingredients may +be more thoroughly mixed up together; and this is precisely what is +done by the stomach; for all the time that the cooking is going on, +he swells and contracts himself alternately, after the fashion of those +rings of the _oesophagus_ we were talking about, tossing and tumbling +the food from one side to another, so as to knead it, as it were. + +Again, the cook adds water to her stew from time to time to keep it +moist; and so the stomach pours constantly upon his stew a liquid, +which contains a great deal of water, and which flows in from a quantity +of little holes, sunk in his delicate coats. + +What more? + +The cook puts in a little salt: and this the stomach takes care not +to forget either, for he is a cook who understands his business. In +the liquid of which I am speaking, there is, if not exactly salt as +one sees it at table, at all events the most active part of salt, that +which possesses in the highest degree the property of reducing +everything we eat to a paste; and this is the real reason why we find +all food so insipid which has not been seasoned with salt. As salt +contains a principle essential to the work to be done by the stomach, +some method had to be devised to induce us to provide him with it, and +this method the porter up above has hit upon. He makes a face if we +offer him anything without a little salt on it, as much as to say--"How +can you expect them to cook you properly down below, my good friend, +if you don't bring them proper materials?" + +Upon which hint men have always acted from the beginning; and as far +as we can trace history back, we find them mixing salt with their food, +though without knowing the real reason why. It is the same, too, with +the lower animals. They know nothing of the matter either, but this +does not prevent their having a natural relish for salt, as any one +will tell you who has the charge of cattle; for their stomachs require +for their cooking the very same seasoning as our own, and therefore +their porter above has received the same orders. + +Salt is not the only thing, however, that exists in that liquid in the +stomach. Learned men, after making minute researches, have found in +it another equally powerful material, which is also found in milk. +Therefore cheese, which contains this material as well as salt, is +quite in its place at the end of dinner. It furnishes reinforcements +for the stomach in cooking, and this is why you so often hear people +say that a little cheese helps the digestion. + +The _digestion_! Yes, that is the word I ought to have begun with. +It is the real name of all this cooking; an operation after which I +would defy you to recognise the nice little cakes you have eaten, any +better than your mamma can trace her pretty rosy-cheeked apples in the +jelly which she left on the fire two hours ago. The stomach, as you +see, is very busy quite as long a time as that, and if we have to be +very careful (as I pointed out before) not to disturb him too suddenly +in his work after dinner, it is also important that we should not, +while at dinner, give him more work to do than he is capable of doing. +Although he is the master, he is but a puny fellow, as I have already +pointed out; nevertheless, he works conscientiously, because he knows +that the life of the whole body depends upon his exertions. Some people +even say that in spite of his leanness he strips himself, at each +digestion, of his interior skin, which he sacrifices to his work, and +the fragments of which tend to increase and improve the stew which is +entrusted to his care. Think of this, my dear, whenever a greedy fit +comes over you, and recollect that such a disinterested public +functionary deserves some consideration. Besides, there is serious +danger, quite apart from any question of injustice, in overwhelming +him with work. If your legs are wearied out, you have it in your power +to lie in bed. If your arm is in pain, you can keep it at rest. But +your stomach is like those poor people who have to support their +families by the labor of each day. He, too, labors for others: he has +no right to rest, no right to be ill, therefore; and when he begins +to fail, woe betide you--you will have enough of it. + +Children who have learnt nothing may laugh at all this, but you, my +dear, are beginning to know something, and "science constrains," +_i.e._ it has its claims and requirements. It requires you, to-day, not +to be greedy, to-morrow, something else, and so on, continually, until +you have become quite reasonable and wise. I am sorry for you if this +vexes you, but it was your own wish to learn, and _science constrains_. +Indeed, I will whisper to you in confidence that this is the best excuse +people who are unwilling to learn have to offer for refusing. They do +not know what learning may lead to, and what a pity it would be if they +could no longer be greedy, or ill-natured, or selfish. What would become +of us all in such a case? + + + +LETTER IX. + +THE STOMACH--_(continued)_. + +We made a very long story of the stomach last time, my dear child; +and, after all, I see that there was one thing I forgot to tell +you--viz., what it is like. + +Have you ever seen a bagpiper, I wonder? A man who carries under his +arm a kind of large dark brown bag, which he fills with air by blowing +into it, and out of which he presently forces the same air into a +musical pipe by pressing it gently with his elbow. If you never saw +such a thing, it is a pity; first, because the bagpipe was the national +instrument of our ancestors the Gauls, and is religiously preserved +as such by the Scotch Highlanders and the peasants of Brittany--(two +remnants of that illustrious race, whose history I recommend to your +careful perusal some day); secondly, and it is this fact which has the +greatest interest for us just now, because that large bag, which is +the principal part of the instrument, gives you a very exact idea of +your stomach; for in fact it really and truly _is_ a stomach itself, and +moreover, the stomach of an animal whose interior formation resembles +yours very, very much. + +And who do you suppose is this audacious animal, which presumes to +have an inside so like that of a pretty little girl? Really, I am half +ashamed to name him, for fear you should be angry with me for doing +so. It is--it is the pig! The resemblance is not exactly a flattering +one to you, perhaps, but we are all alike, and it would be worse than +foolish to grumble at being created as we are. Moreover, there is one +difference; the pig, who thinks of nothing but eating, has a very much +larger stomach than we have, which is some consolation, at any rate. + +Place the palm of your right hand on what is called the pit of the +stomach, turning the ends of the fingers towards the heart; your hand +will nearly cover the space usually occupied by the stomach, and you +may figure it to yourself as a rounded and elongated bag, bigger above +than below, making a very decided bend inside as it descends from the +heart downward; something like one of those long French pears, called +"Bon-chretiens," if it were bent in the middle, and the big end of it +were placed next the heart. As for the exact size of the bag, there +is no telling it, for it depends upon circumstances. It is a very +convenient bag in that respect; just such a one as you would like to +have in your frock for a pocket; only there would be a danger of your +being tempted to put too many things into it. For as you fill it, it +expands, and enlarges itself like an indian-rubber ball, which, though +only the size of an egg to begin with, becomes as big as your head if +you blow hard into it. Then, as it gets empty, it recovers itself, +diminishing gradually in size in plait-like contractions. + +When people remain too long without eating, they have, as they say, +twinges in the stomach. This is because the stomach, becoming by degrees +quite empty, and contracting more and more, the surrounding parts which +were sustained by it, lose their support, and strain at their ligaments, +which now have all the weight to bear. Careless people, who do not +think of such things, are reminded by the twinging pains that it is +time to eat, just as a careless servant is called to order by the bell +of which his master has pulled the string. + +In your case, my dear child, such warnings are soon attended to, and +you have not always even to wait till they come. But there are hundreds +of miserable beings who are warned to no purpose, who cannot obey the +master when he calls for his rations, because they have nothing to +give him; and when this forced disobedience lasts too long, they end +by dying of it. In cases like these, when human beings thus cruelly +perish, the stomach is found to be contracted till it is scarcely +bigger than one's finger. + +On the other hand, a man once died suffocated from excess of food, +after one of those great public dinners, which last four, six, or more +hours--one can scarcely say correctly how long--and the doctors who +examined him found his stomach so prodigiously enlarged that it alone +occupied more than one-half of his inside. As you perceive, therefore, +the stomach has, properly speaking, no fixed size. Its size depends +upon what there is in it. It is like those men whose manners go up and +down with their fortunes; who seem very grand people when their pockets +are well filled, but become very small ones when their purses are +empty. There is, nevertheless, this difference between them, that such +men are fools, because they are men, and not _bags_; whereas the +stomach is a sensible bag, fulfilling with intelligence the duties of +its character as a bag. It is very fortunate for us that it is ready +to change its size, according to the caprices of our appetite; and +dressmakers would do well if they could get a hint from it how to +improve their style of pockets, which certainly cannot have cost their +inventors any very great effort of imagination! + +The way in which this extraordinary pocket empties itself is not less +curious than the rest. As long as digestion is going on, the stomach +is firmly closed at each end; at the upper one by the last ring of the +_aesophagus_, and at the lower by another ring of the same kind, +only stronger; the watchful guardian of the passage which leads to the +intestines. This ring is called the _pylorus_. + +For once, here is a name which agrees with our method of describing +the human machine, and I have much pleasure in translating it to you, +although it is a Greek word. _Pylorus_ is the Greek for a porter; +and our ring is indeed a porter like the one of which we have already +said so much, and which I called last time the _porter up above_, +in anticipation of his colleague below. + +The porter up above presides at the entrance; the one below at the +exit, and both for the same purpose, namely, to _taste._ [Footnote: +It would be absurd to say so in the common acceptation of the term; +but according to No. 1 of Mr. Mayo's "Classification of the impressions +produced by substances taken into the fauces," viz., _"Where +sensations of_ touch _alone are produced, as by rock-crystal, +sapphire, or ice,"_ the word taste may be applied to the +discriminating faculty of the _Pylorus_.--TR.] + +It may well astonish you, that you should have in your inside a taster +who is not accountable to you; who experiences sensations of which you +know nothing, and cannot even form an idea. Yet thus it is. The +_pylorus_ actually tastes the paste which is in the stomach, and +if it is not to his taste, that is to say, if the work of digestion +has not sufficiently transformed it for use, he keeps the door +relentlessly closed. + +The porter up above has a thousand different tastes. He makes his bow +to meringues, and admits wings of chickens. Fries, roasts, stews, +things tender or crisp, sweet and salt, oily, greasy, or sour; amongall +kinds he has friends whom he welcomes in succession; and it is +well for us that he does so, for we share in all his pleasures. + +The porter below, who works for himself alone, obscure and unknown +down in his black hole, the porter below, I say, has but one taste, +knows but one friend--a gray-looking paste, semi-liquid, with a very +peculiar unsavoury smell, disagreeable enough to any one but himself, +which is called the _chyme_, I scarcely know why, but it is what +everything one eats turns into, without exception, be it delicate or +coarse by nature. The great lord's truffle-stuffed pullet makes, as +nearly as possible, the same _chyme_ as the charcoal-burner's black +bread; and though the palate of the former may be better treated +than that of the latter, the _pylori_ can enjoy but one and the +selfsame sauce. Equality is soon restored in this case, therefore, as +you see. + +To be free to pass through then, the contents of the stomach must be +reduced to the condition of _chyme,_ the only substance which finds +favor with the _pylorus:_ and as, in the endless varieties of food which +go to form our nutriment, some sorts turn into _chyme_ much more quickly +than others, it follows, that by the aid of its discriminating tact +(which is not easy to elude) the _pylorus_ allows some to pass, while it +turns back others, until all in succession are converted into chyme. For +example, in the case of a mouthful of bread and meat swallowed at once, +the bread passes away on its travels long before the meat has done +dancing attendance in the stomach, awaiting that transformation without +which the _pylorus_ will never allow it to slip through. + +This ought to make you seriously reflect on the danger of carelessly +swallowing things, which, by their nature, are not susceptible of being +converted into _chyme,_ particularly if they are too large to +hide in the general paste, as a cherry-stone will sometimes do, so +mixed up with other food as to pass unperceived by the _pylorus,_ +over whose decisions we have no control, remember. It bangs the door +to, be assured, in the very face of anything obnoxious without +hesitation, and the poor stomach would find itself condemned to retain +them for an indefinite period, unless by dint of prayers and +supplications they should contrive to soften the stern guardian, who +may at last get accustomed to their approach, and, perhaps, in a weak +moment, allow them to pass as contraband goods; like a custom-house +officer on a foreign frontier who will occasionally shut his eyes to +a country friend's packet of tobacco. But the poor stomach has had to +suffer a martyrdom meantime, while the dispute was pending, and before +the intruder has been winked at by the porter. + +I shall remember all my life the history of a peach-stone, which was +related to me in 1831. I was at the time a youngster at the Stanislaus +College, and (aided perhaps by the Revolution of July, which had +recently occurred), it was just then discovered to be a proper thing +to set about teaching the laws of nature to children. Consequently, +for the first time in the history of schools, a professor of natural +history was added to the instructors of Latin and Greek. I leave you +to judge how we opened our ears to his lessons. When we arrived in the +course of our new studies at the _pylorus,_ of which we had none +of us ever heard before, our professor, in warning us, as I have done +you, of the dangers of imprudent gluttony, related, as an instance, +the case of a lady who had inadvertently swallowed a peach-stone. For +two years she suffered agonies in her stomach without any cessation +or relief. The luckless peach-stone, repelled by the walls of the +stomach, which its very touch irritated, was incessantly thrown against +the entrance of the _pylorus,_ but in vain. As to turning itself +into _chyme,_ such a thing was not to be thought of, it was far +too hard a substance for that. Round and round it went, causing in its +relentless course such renewed suffering to the poor patient, that she +was visibly sinking from day to day. + +The doctors, finding all their treatment of no avail, began to despair +of her life, when one fine day she was suddenly, and as if by +enchantment, relieved of her tormentor. The peach-stone had bribed the +porter, with whom, in the course of the two years, it had scraped up +a sort of friendship. It had cleared the terrible barrier, had been +allowed to slip out, and the lady was saved; but it was only just in +time. + +I do not know, my dear, that this story, which is certainly well +calculated to cure you of any fancy for swallowing peach-stones, +willmake as much impression on you as it did on me five-and-twenty years +ago. The idea of telling it to you occurred to me quite by chance. It +has carried me back to the time when, as is now the case with you, the +mysteries which lie hidden in our internal organization were beginning +to be revealed to my mind; and you will one day know with what delight +one recalls the remembrance of these first dawnings of the intellectual +life--that delightful infancy of the growing mind--more rich in +recollections, and more interesting a thousand fold than the infancy +of the body. I have allowed myself the little treat of this episode, +and if I have had the good fortune to amuse you at all during our +progress, you must not cavil at this piece of self-indulgence. +And now we have done just what the peach-stone did; we, too, have +passed the barrier, and are out of the stomach, but still we have not +yet come to the end of our tale. + + + +LETTER X. + +THE INTESTINAL CANAL. + +I venture to hope, my dear child, that more and more light is dawning +upon your mind, as we gradually proceed on our little journey. You +must by this time have some idea how the food, which has been masticated +and softened in the mouth, cooked, kneaded, and decomposed in the +stomach, and transformed into a soft, semi-transparent kind of paste, +will soon be ready to mix with the blood, in order to repair the waste +that the life-stream is continually undergoing in its ceaseless course +through all parts of the body. + +You have perhaps thought it a sad degradation for a truffle-stuffed +fowl to turn to _chyme._ But when you consider that by this means +it becomes part and parcel of a human body, the change is not to be +despised. It was necessary, to begin with, that materials destined to +the honor of being incorporated into our frame, should break the links +which bound them to the condition of fowl and vegetable, and thus be +free to engage in new relations; just as a man who wishes to be +naturalized in a new country must first break the ties which hold him +to the old one. Those articles of food we were speaking of lately, +which are so stiff and ceremonious, and want so much coaxing before +they change into _chyme,_ which, moreover, we call _indigestible_ +because they tire the stomach so much more than the rest, are merely +those whose component parts being held together by more solid ties than +usual, continue obstinately in the same state as at first, and will not +consent to that dissolution which is the first condition of their +glorious transformation. + +Moreover, the transformation which has been described to you now, you +will henceforth meet with everywhere; wherever, that is to say, and +as far as, you choose to pursue the study of nature. God works by one +grand and simple rule so far as we can discover. He destroys to +reconstruct, builds up what is to be, out of the ruins of what has +been, creates life by death, if I may so express myself, and thus, +what takes place in our stomachs on a small scale goes on on a large +one in the universe. + +Social communities, like everything else, are subject to this universal +law, and it is not always an advantage to them when they refuse to be +digested in the great stomach of the age! + +While we are on this subject, and to show you how wonderfully this +little history of eating, told in this familiar style, applies right +and left, let us reflect on the causes which have produced a great and +mighty nation in one country (as in France), while in another (as in. +Germany), a far more numerous and even more intellectual population +has failed to rise to anything like the same distinction. The +explanation is not difficult. In the one case, the petty tribes among +which the land was originally divided consented to mix, and dissolve, +and be digested as it were together, in order to revive again for a +more glorious career; while in the other, the aboriginal societies +have adhered stiffly to their distinctive characters, and failing to +submit to the regenerating process, cling together in indigested +portions, rather than assimilate into one great whole. + +However, we must return to the _pylorus_ or we shall be getting +into a difficulty! What I am now going to offer you though, is rather +hard of digestion, but it will not do to provide sweet pastry only for +your brain; it will be more wholesome for it to have something a little +more solid to bite at from time to time. + +The _pylorus_, then, as has been shown, makes way for all sorts +of aliments when they have been converted into _chyme; i.e._, +when they have lost their original form and individuality. They are +dead to their first life, therefore; now the question is, how are they +to be revived into the new one? + +Behind the _pylorus_ extends a long conduit or tube--so long as to be +sometimes seven times the length of the whole body, but doubled up +backwards and forwards a number of times, so as to form a large bundle, +which fills the whole cavity of the belly--or as we also call it, the +_abdomen_. This bundle or packet is known to everybody as _the +intestines_, and it is divided into two portions: the _small +intestine_--that is, the slenderer, finer portion which begins at the +_pylorus_, and forms all the doublings of the packet, and the _large +intestine_, which is shorter and thicker also, as its name implies, and +keeps to some extent separate, though it is in reality only a +continuation of the other. This starts at the base of the _abdomen_, +near the right side, goes up in a straight line to the height of the +stomach, below which it passes, making a large bend in front of the +small intestine; after which it descends on the left side to the lower +part of the trunk, where it terminates. + +You will perhaps inquire how the _chyme_ continues to make its way +through all these manifold twists of the intestines; but do not trouble +yourself; it has only to let itself go. That _vermicular movement_ which +we noticed in the _oesophagus_ and in the _stomach_ is found here also. +It reigns, so to speak, from one end of our internal eating-machine to +the other; which eating-machine, by the way, we will now call by its +proper scientific name--_the intestinal canal_; and it is by that +movement the food is carried forward from the first moment it leaves the +mouth, and helped through all its journeyings, till it reaches the +termination of the large intestine. + +If your body were made of glass, so that you could look through it to +watch the intestine at work, it would appear to you like an enormous +worm coiled up into a bundle, heaving and moving with all its rings +at once. You never suspected there was such a movement within you; yet +it has been going on there continually ever since you were born, and +will not cease till you die. Your internal machinery never goes to +sleep, not even when you are sleeping yourself. It is a workshop in +constant operation, providing night and day for your necessities; and +in this respect the inner man sets a first-rate example to the outer +one! You will recollect what I said to you the other day about the +internal republic, and the provinces which are under your sole +government. It would be very disgraceful for the kingdom to be doing +nothing while the republic is working so hard; and a queen who +understands her office will make it a point of honor to banish idleness +from her household; in the houses of her neighbors this word is unknown. + +The _chyme_ once launched into this moving tube, is in no danger +of remaining stationary there; the fear is, of its passing on too +quickly, as you will soon see. But this danger has been provided +against. Along the whole course of its journey, though chiefly at the +commencement, it encounters at intervals certain elastic fleshy valves +which interrupt its progress, and do not allow it to pass till it has +accumulated in sufficient force to push them before it, and so escape. +In consequence of which it is always being checked in its advance; and +during these stoppages a most important work goes on upon it at leisure. + +You must understand first, that the substances of which our food is +composed, and which are afterwards decomposed in the stomach, are not +all invited to enter the blood. Our aliments are something like the +stones which the gold-seekers of California reduce to powder in order +to extract therefrom the hidden particles of gold they contain. The +gold of our food is that portion of it which the blood is able to +appropriate to his own advantage; the rest he rejects as refuse. And +this explains why a small slice of meat nourishes you more than a whole +plateful of salad. Meat is a stone absolutely full of gold, while the +salad has only a few veins of it here and there, and by far the greater +part of the material it sends to the intestines, has, in consequence, +to be thrown away. + +Now it is in the first portion of the small intestine, the part known +by the Latin name _duodenum,_ which signifies twelve (because it +is about the length of twelve finger-breadths), that the division takes +place between the parts which go to nourish the blood, and those which +are useless refuse. It is an important operation as you may suppose, +and were the _chyme_ to pass rapidly through the small intestine +the gold would run the risk of being carried off with the refuse. + +After the delay in the stomach, the food-substances make another halt +in the _duodenum,_ which, being very thin and slender, would have +great difficulty in containing them at the time of their grand entry, +an hour or two after a meal, were it not that it possesses the property +of expanding itself to such an extent, that it swells out on grand +occasions to the usual size of the stomach itself, so that it has +sometimes been considered as a second stomach. And no doubt the +operation which takes place in it gives it a claim to the appellation, +for thereby the finishing stroke is put to the work previously begun +in the stomach, and one may fairly say that, but for this last touch, +very little would be accomplished at all. + +Above the _duodenum_, and hid behind the stomach, is a kind of sponge, +similar in nature to those we have already observed in the mouth. To +this has been given the somewhat ridiculous name of _pancreas_; I call +it ridiculous because it is derived from two Greek words which signify +_all flesh_; whereas the _pancreas_, which is a sponge of the same +description as the salivary glands, presents the appearance of a grayish +granulous mass which is not fleshy at all. Whatever be its name, +however, our sponge communicates with the _duodenum_ through a small +tube, by means of which it pours into the _chyme_, as it accumulates, a +copious supply of a fluid exactly like the _saliva_ of the mouth. + +Just by the place where the tube from the _pancreas_ empties itself into +the _duodenum_, another tube arrives bringing also a fluid, but of a +different sort. This last comes from the liver, where there is a +manufactory of _bile_--an unpleasant yellowish-green liquid, the name of +which you have no doubt heard before, and which plays a very important +part in the transformation of the aliments. + +These new agents, the bile and the liver, are far too important to be +passed over in a few words; I reserve them, therefore, for my next +letter. Meantime, not to leave you longer in suspense, I may say that +the separation between the gold and the refuse in the _chyme_ takes +place as soon as the latter has received the two liquids furnished +by the liver and the _pancreas_. If you ask in what manner the +division is accomplished, I confess, to my shame, that I am not able +to explain it! What takes place there is a chemical process, and +hereafter I shall have occasion to explain the meaning of that phrase. +But the Great Chemist has not in this instance seen fit to divulge to +man the secret of the work. + +Indeed, you must prepare yourself beforehand, my dear child, to meet +with many other mysteries besides this, if we pursue to the end our +study of this flesh and bone which constitute the body of man. And +here I recall what Camille Desmoulins is reported to have said about +St. Just, viz., that he carried his head as high as if it were a +consecrated Host. + +[Footnote: The young Protestant reader who has never lived +in a Catholic country, will perhaps need to be told, that what +is here called Consecrated Host, is the sacramental wafer, or communion +bread of the church. In French called _hostie_, in Italian, _ostia_. + +In all their religious processions, which are very frequent, the host +is carried by the priest highest in authority, in a glass box placed +on a staff about four feet long, which he holds before him and so far +elevated that he has to look up to it. Over his head a richly +embroidered canopy of satin is always carried by several men; and while +these are passing, all good Catholics uncover the head and bend the +knee, wherever they may be. + +It is the custom also for the priest to be called to administer the +sacrament to any one about to die, on which occasion he always walks +under this canopy, dressed in his priestly robes, carrying the host +and preceded by some boys, ringing a bell, when the same ceremony is +observed. In passing a regiment or company of soldiers, the column is +halted, wheeled into line, and with arms presented, the whole line, +officers and men, kneel before it, and the priest usually turns and +offers a benediction. When he goes in the evening to the house of the +dying, it is customary for the people to go out upon the balconies +with lighted lamps and kneel while the host is being carried by.] + +You will read about these two men by-and-by in history. Meantime I +will not bid you do exactly the same as St. Just, because you would be +laughed at; but in one point of view he was not altogether wrong. The +human body is, in very truth, a temple in which the Deity maybe said +to reside, not inactively, not veiling his presence, but living and +moving unceasingly, watching on our behalf over the mysterious +accomplishment of the everlasting laws which equally guide the +_chyme_ in its workings through our frames, and direct the sun +in its course through the heavens. We mortals eat, but it is God who +brings nourishment out of our food. + + + +LETTER XI. + +THE LIVER. + +I fear you will be getting a little weary, my dear, of dwelling so long +on this intestinal tube, where things which looked so well on one's +plate become so transformed that they cannot be recognized, and where +there is nothing to talk about but _chyme_, and _bile_, and the +_pancreas,_ and all sorts of things neither pleasant to the eye nor +agreeable to the ear. + +But what is to be done? It is always the same story with useful things. +The people by whose labor you live in this world, are by no means the +handsomest to look at, and so it is in the little world we carry about +in our bodies. + +Never mind! Keep up your heart. We are getting to the end. We shall +very soon be following the nourishing portion of our food, on its +journey to the blood, and you will find yourself in new scenes. + +First, though, let us say a few words about the liver--the +bile-manufacturer; and to begin with, I will describe the place he +occupies in our interior. + +The interior of the human body is divided into two large compartments, +placed one above the other; the _chest_ and the _abdomen_. These are two +distinct apartments, each containing its own particular class of +tenants: the upper one being occupied by the heart and the lungs (the +respective offices of which I will presently explain to you); while in +the lower are the stomach, the intestines, and all the other machinery +which assists in the process of digestion. These two stories of +apartments are separated as those of our houses are, by a floor placed +just above the pit of the stomach. This floor is a large thin, flat +muscle, stretched like canvas, right across the body; and it is called +the _diaphragm_--another hard word! Never mind; but do your best to +recollect it, for we shall have great need of it when we come to the +lungs. If you had been born in Greece, you would have no difficulty with +the word, for it is Greek for _separation_. It means, in fact, a +_separating partition_, or, as I called it just now, _a floor._ All this +is preparatory to telling you that the liver is hooked to the diaphragm +in the abdomen. It is a very large mass and fills up, by itself alone, +all the right side of the lower compartment, from the top downwards, to +where the bones end which protect the abdomen on each side, and which +are called _the short ribs._ Place your hand there, and you will find +them without difficulty. + +Large as the liver is, it hangs suspended to a mere point of the +diaphragm, and shakes about with even the slightest movement of the +body. It is partly on this account that many people do not like to +sleep lying on the left side, especially after a good dinner, because +in this position the liver weighs upon and oppresses the stomach, like +a stout gentleman asleep in a coach who falls upon and crushes his +companion at every jolt of the vehicle. The liver within you produces, +then, the same effect that a cat, lying on the pit of your stomach +would do, and the result is that you have the nightmare. + +The liver is of a deep-red color. It is an accumulation of excessively +minute atoms, which, when united, form a somewhat compact mass, and +within each of which there is a little cell, invisible to the naked +eye, where an operation of the highest importance to our existence is +mysteriously carried on. It appears a very simple one, it is true, yet +hitherto it has baffled all attempts at explanation. Listen, however; +the subject is well worthy your careful attention, whether it can be +explained or not, and we must look back to take it up from thebeginning. + +I told you about the thousand workmen constantly busied in every part +of our bodies, who call on the blood without ceasing for "more, more." +You will remember further that it is to enable the blood to supply +these constant demands, that we require food. + +This being understood, it is not difficult to see why we grow; the +difficulty is, rather, to explain why we do not continue to grow. + +Consider, for instance, the quantity of food you have eaten during the +last year. Picture to yourself all the bread, meat, vegetables, fruits, +cakes, &c., piled upon a table. Put a whole year's milk into a large +earthenware pan, all the sweetmeats into a large jar, all the soup +into a great tureen, and see what a huge heap you will have collected +together. Then try to recollect how much you have increased in size +with all this nourishment, which has entered your body. But reckoning +in this way--even supposing the little workmen had used only a half +or even a third of the materials in question, and rejected the rest +as refuse--you would have to stoop in order to get in at the door; and +as for your papa, whose heap must have been bigger than yours, his +case would be desperate indeed; and yet he has not grown at all! + +This is very curious, and I dare say you have never thought about it +before. + +Do you know the story of a certain lady called Penelope, who was the +wife of Ulysses, a very celebrated king of whom the world has talked +for the last 3000 years--thanks to a poet called Homer, who did him +the honor of making him his hero! The husband of Penelope had left her +for a long time to go to the wars, and as he did not return, people +tried to persuade her to marry again. For peace and quiet's sake, she +promised to do so when she should have finished a piece of cloth she +was weaving, at which she worked all day long. They thought to get +hold of her very soon, but her importunate lovers were disappointed; +for the faithful wife, determined to await the return of her husband, +unwove every night the portion she had woven during the day; and I +leave you to judge what progress the web made in the course of a year! + +Now, every part of our bodies is a kind of Penelope's web, with this +difference--that here the web unravels at one end as fast as the work +progresses at the other. As the little masons put new bricks to the +house on one side, the old ones crumble away on another--in this manner +the work might go on forever without the house becoming bigger; while, +on the other hand, the house is always being rebuilt. People who are +fond of building, as some are, would quite enjoy having such a mansion +as this on hand! + +At your early age, my love, fewer bricks drop out than are added, and +this is why you grow from year to year. At your papa's age, just the +same number perish and are replaced; and therefore he continues the +same size, although in the course of the year he swallows three times +his own weight of food. But when I say this, do not suppose it is an +offensive remark, or that I think him either too little a man, or too +great an eater; seeing that there are 365 days in the year, and that +a quart of water weighs two pounds: I need not say more! + +But the next question is, what becomes of all the refuse which this +perpetual destruction produces? + +What becomes of it? Have you forgotten our steward who looks after +everything? He is a more active fellow than I have represented him! +To the office of purveyor-general he adds that of universal scavenger. +But in the latter department he obtains help. Wherever he passes along, +troops of little scavengers press forward, like himself always busy; +and while he holds out a new brick to the mason as he hurries by, the +little scavenger slips out the old one and conveys it away. The history +of these scavengers is a very curious one, and we shall have to speak +about it a little further on. They are minute pipes, _i.e. ducts_, +spread all over the body, which they envelope as if with fine net work. +They all communicate together, and end by emptying the whole of their +contents into one large canal, which, in its turn, empties itself into +the great stream of the blood. Imagine all the drains of a great town +flowing into one large one, which should empty itself into the river +on which the town was built, and you will have a fair idea of the whole +transaction. What the river would in such a case be to the town, the +blood is to the body--the universal scavenger, as I said before. But +you will ask further, What does the blood do with all this?--a question +which brings us back once more to the liver. + +You must have seen, just now, that the pockets of our dear steward +would be rapidly overloaded, were he to keep constantly filling them +with the old worn-out materials which the builders rejected, unless +he had some means of emptying them as he went along. Accordingly, a +wise Providence has furnished the body, on all sides, with clusters +of small chambers or cells, in which the blood deposits, as he goes +by, all the refuse he has picked up, and which makes its exit from the +body sometimes in one way, sometimes in another. Now, the cells of the +liver are among these refuse-chambers. One may even consider them as +some of the most important ones. When the blood has run its course +through the lower compartment, I mean the _abdomen_, it collects +from all directions and rushes into a large canal called the _portal +vein_, which conveys it to the liver. As soon as this canal has +entered the liver, it divides and subdivides itself in every direction, +like the limbs and branches of a tree diverging from the trunk; and +very soon the blood finds itself disseminating through an infinity of +small canals or pipes, whose ultimate extremities, a thousand times +finer than the finest hairs of your head, communicate with the tiny +cells of the liver. There, each of the imperceptible little drops, +thus carried into these imperceptibly minute cell-chambers, rids +itself--but no one knows how--of a part of the sweepings it has carried +along with it. Which done, the little drops thread their way back +through other canals as fine as the first, and which go on uniting +more and more to each other, like the branches of a tree on their way +to the trunk--forming at last one large canal, through which the blood +escapes from the liver, once more relieved from its weight of rubbish, +and ready to recommence its work. + +You are going to ask me, "What is all this to me--this history of the +blood and its sweepings? It was the bile you undertook to tell me +about, that liquid you spoke of as so necessary for the transformation +of the food: we were to get out of the intestinal tubes by the help +of the bile, you promised me." + +Well, my little impatient minx, it is the history of the bile that I +have been relating to you, and what is most remarkable about it is +this. You have perhaps heard of those wholesale ragpickers, who +makelarge fortunes by collecting out of the mud and dirt of the streets, +the many valuable things which have been dropped there? Well, the liver +is the master-ragpicker of the body. He fabricates, out of the refuse +of the blood, that bile which is so valuable in the economy of the +human frame. This bile is neither more nor less than the deposit left +by the little drops of blood in the innumerable minute liver-cells. +See what an ingenious arrangement, and in what a simple way two objects +are effected by one operation! + +Now you have learnt the genealogy of the bile, and the double office +of the liver, which benefits the blood by what it takes from it, +benefits the _chyme_ by what it gives it, and is an economist at +the same time--since it only gives back what it has received. This was +what I particularly wished to explain to you: the rest you will easily +learn. + +The bile does not make a long stay in the little cells, it also escapes, +by canals similar to those which carry off the blood, after +itspurification; and which in a similar way unite by degrees together, +until at length they terminate in a single canal, communicating with +a little bag placed close against the liver, where the bile accumulates +between the periods of digestion--so forming a stock on hand, ready +to pour at once into the _duodenum_ when the latter calls for its +assistance. The next time the cook cleans out a fowl, ask her to show +you the little greenish bladder which she calls the gall and which she +takes such care not to burst, because it contains a bitter liquid +which, if spilt upon it, would quite ruin the flavor of the fowl. Such, +precisely, is the bag which holds the bile. Moreover, it is close by +the liver of the fowl that you will find it placed: and you can convince +yourself in a moment by it, that the little provision I tell you of +is always stored away therein. + +We have also within us a multitude of minute electric telegraphs, which +transmit intelligence of all that occurs from one part of the body to +another, in a more wonderful manner even than the telegraphs of man's +making; later we shall see how they work. By their means the little +bag by the liver is made aware in the twinkling of an eye of the +entrance of the _chyme_ into the _duodenum,_ and forthwith the bile +returns for some distance by the canal which brought it, and then +branches off into a larger one which opens into the _duodenum._ + +The liver, on getting this intelligence, sets to work more diligently +than ever, and the bile flows in streams into the _duodenum,_ where it +mixes as it arrives with the current which comes from the _pancreas._ +Thus combined, the two liquids flow over the _chyme,_ which they +saturate on all sides; and here, as I have said, the work of the +intestinal canal ends. What is serviceable for the blood is separated +from the useless refuse, and nothing remains but to get it out of the +intestines. It is true that in their character of tubes these are closed +on all sides. But do not trouble yourself: a means of escape is +prepared. + +Before we part, however, I must apologize for something. I have not +described to you what the bile consists of, or what kind of refuse the +blood leaves in the liver; nevertheless, as you take an interest in +this much-neglected book of nature, you ought to know these things. + +It is, however, very difficult to lead you by the hand through so many +wonder*, where the secrets of nature are all in operation at once, and +to explain each as soon as we meet with it. They combine, and progress +together like the waves of the sea, where one breath suffices to agitate +the whole mass. + +When we have talked about the lungs, we will have another word to say +about the liver. + + + +LETTER XII. THE CHYLE. + +To-day we have to begin by making acquaintance with a new term. I would +willingly have spared you this, if I could, for the word is neither +a pretty, nor a well-chosen one, but we cannot get on without it. + +You are aware now that the learned, unknown sponsors, who gave names +to the different parts of the body, bestowed the odd-enough one of +_chyme_ on that pasty substance which passes out of the stomach when the +cooking is over. We have said quite enough about it, and you know enough +of it I am sure. Well! the people seem to have had quite a fancy for the +word _chyme_, for they adopted it again, with only a very slight +alteration, when they wanted to specify separately the quintessence of +the _chyme_ (the useful part that is), which has to unite with the +blood, and which we have been speaking of as the _gold_ of the +aliments--this then they called _chyle_. I give you the name as I +received it, but have no responsibility in the matter. + +In concluding the last chapter I said we were sure to find there was +a plan for extracting the best part of the _chyme_, viz. the _chyle_, +from the intestinal canal; and a very simple one it is. A complete +regiment of those little scavengers lately described, are drawn up in +battle-array along the whole length of the small intestine, but +especially round about the _duodenum._ There, a thousand minute pipes +pierce in all directions through the coat of the intestine, and suck, +like so many constantly open mouths, the drops of _chyle_ as fast as +they are formed. They are called _chyliferous vessels_ or chyle-bearers, +just as we might call hot-air stoves _caloriferous_ or heat-bearers--from +the Latin word _fero,_ which means to carry or bear. I mentioned +before that there were, within the intestine, certain elastic valves +which obstruct the progress of the _chyme,_ and oblige it to be +constantly stopping. There are in fact so many of these, and the skin +which lines the intestinal canal is so folded and plaited, that if it +were stretched out at full length on a big table, it would cover at +least as large a surface as that other skin, with which you are so well +acquainted, which entirely clothes the body outside. + +Now, the _chyliferous vessels_ we have been speaking of insinuate +themselves into all the plaits and folds alluded to, and thus they +reach at last the very centre of the _chymous_ paste, and not a single +drop of _chyle_ can escape them. They do their work so well, that the +separation is effected long before the paste reaches the large +intestine; and when that has forced its way through the door which +guards the entrance, and which prevents its ever returning again, the +_chyle_ is already far off on its mission. It has threaded its way along +the little pipes, and, always creeping nearer and nearer, is on the +high-road to the heart, where it is anxiously expected. + +And what becomes of the rest? There is nothing further to be said about +it, but that it shares the fate of everything else which, having +answered its purpose in its place, is no longer wanted and must be got +rid of. Thus in works where iron-stone smelting is carried on, the +refuse that remains after the ore is extracted, though available for +road-making or other purposes, is thrown out of the manufactory as a +useless incumbrance there. + +Our history requires us to follow the fate of that golden aliment the +_chyle,_ which is now in a condition to support the life of the body, +and every drop of which will turn into blood--the blood which beats at +our hearts, nourishes our limbs, and sets at work the fibres of our +brain. + +I ought to tell you first that the _chyle,_ when it leaves the +intestine, is very like milk. It is a white, rather fatty juice, having +the appearance, when you look closely at it, of a kind of _whey,_ +in which a crowd of globules, or little balls if you prefer it, +infinitesimally small, are swimming about. Some people, whose curiosity +nothing can check, have put the tips of their tongue to it; so I am +able to tell you, if you care for the information, that it has rather +a saltish taste. + +At this point it is what may be called new-born blood, and to carry +on the metaphor, blood whose education has yet to be completed. All +the elements of blood are there already, but in confusion and +intermingled, so that they cannot yet be recognised. A wonderful fact, +and one of which I have no explanation to offer you, because among the +many mysteries which are silently going on within us is this, that the +education of the new-born blood begins entirely of itself in the vessels +which are carrying it along. During their very journey, the confused +elements are setting themselves in order and forming into groups. In +short the _chyle,_ when it comes out of the chyliferous vessels, +is already much more like blood than when it entered them, and yet one +cannot account for the change. It is changed, however; its whiteness +has already assumed a rosy tinge, and if it is exposed to the air it +may be seen turning slightly red, as if to give notice to the observer +of what it is about to become. + +You know that all our scavengers uniting together deposit their +sweepings in one large canal, which is called the _thoracic duct._ +The _chyle_ scavengers arrive there just like the rest, and there +our poor friend finds himself confounded for a moment with all the +dross of the body, as sometimes happens to men who devote themselves +to the public good. But the crisis passes in an instant. A little +further off, the _thoracic duct_ pours its whole contents together +into a large vein situated close to the heart, and the blood has no +difficulty in recognising and appropriating what belongs to him. + +Here, my dear little scholar, we conclude the first part of our story. +To eat is to nourish oneself; that is, to furnish all parts of the +body with the substances necessary to them for the proper performance +of their functions. The mouth receives these substances in their crude +condition, the intestinal canal prepares them for use, and the blood +distributes them. + +After the history of the _preparation,_ comes naturally that of the +_distribution._ + +The first is called the DIGESTION. It is the history of the _chyle,_ +which begins between the thumb and forefinger while as yet invisible, +hid in the thousand prisons of our different sorts of food, and ends in +the _thoracic duct_, when, disengaged from all previous bonds, purified +and refined by the ordeals of its intestinal life, it leaps into the +blood, carrying with it a renewal of life and power. + +The second history is that of the CIRCULATION. It is the history of +the _Blood,_ that indefatigable traveler, who is constantly +_circulating_ or describing a circle (the Latins called it _circulus_) +through the body; by which I mean that it is continually retracing its +steps, coming out of the heart to return to it, re-entering it only to +leave it again, and so on without intermission, until the hour of death. + +The history of the _Digestion_, which we have just gone through, +goes on quietly from one end to the other without any complication. + +That of the _Circulation_, which we are about to begin, is mixed +up with another history, from which it cannot be kept separate while +the description is going on, although the two histories are in reality +quite distinct from each other. The blood describes two circles, to +speak correctly: 1st. A wide one, which extends from the extremities +of the body to the heart, and back again from the heart to the +extremities. 2d. A more contracted one, which goes from the heart to +the lungs, and back from the lungs to the heart. Whilst circulating +in the lungs, it encounters the air we breathe; and here takes place, +between it and the air, one of the most curious transactions imaginable, +without which the blood would not be able to nourish the body even for +five minutes. This is called RESPIRATION, or the act of breathing. + +Digestion, circulation, respiration, the three histories together form +but one--that of NUTRITION, or the act of nourishing; in other words, +of supporting life. This is what I called _eating_ at first, that +I might not mystify you at the beginning with hard words. But now that +we are growing learned ourselves, we must accustom ourselves to the +terms in use among learned people, especially when they are not more +formidable than those I have just taught you. + +Our next subject for consideration, then, Will be the circulation; and +we will begin with the heart, since that is to the circulation what +the stomach is to the digestion--viz., master of the establishment. +He is a very important person, this heart, as I hardly need tell you. +Even ignorant people speak respectfully of him, and I am sure beforehand +that his history will interest you very much. + +Do you feel as I do, my dear child? I am quite happy at having brought +you thus far on our journey, and at being able to take a rest with you +at the gateway of the new country into which we are about to enter, +like travelers sitting down upon a boundary frontier. What a distance +we have come, since the day when I took you by the hand to conduct you +inside this little body, of which you were making use without knowing +anything about it! How many things we have learned already, and how +many more remain to be learned, of which you have at present no idea! +I assure you I should be almost afraid myself of what is before us +yet, if I did not rely upon my own strong desire to instruct you, and +the tender affection I bear to you. Believe me, the greatest of +constraining powers is love; and when I get bewildered in the midst +of some difficult explanation which will not come out clearly, I have +only to place before me those laughing eyes of yours, where sleeps a +soul that must soon awaken to consciousness, in order to make the +daylight come into my own! + +Must I add, too, that I am not working for you only? We are all placed +in this world to help each other, and in striving to bring down light +into your intellect, and good sentiments into your heart, I am thinking +also of those to whom you, in your turn, may render the same good +service hereafter, provided I have the happiness of succeeding now +with you. This ought to be so, ought it not? You should resolve to be +numbered one day among those who have not lived altogether for +themselves, but who have given the world something worth having as +they passed through it. To-day's labor will have been well employed +if, later on, it turns out that this history of the _chyle_ has +not been told you in vain! + + + +LETTER XIII. + +THE HEART. + +There was once upon a time a banker, a millionaire, who could reckon +his wealth not by millions only, but by hundreds of millions and more; +who was, in fact, so tremendously rich that he did not know what to +do with his money--a difficulty in which nobody had ever been before. + +This man took it into his head to build a palace infinitely superior +to anything that had hitherto been seen. Marbles, carpets, gildings, +silk hangings, pictures, and statues--in fact, the whole mass of +common-place luxuries as one sees them even in the grandest royal +abodes, fell short of his magnificent pretensions. He was an intelligent +man, and thoroughly understood the respect due to his riches; and the +common fate of kings seemed to him far too shabby for the entertainment +of his dynasty, which he looked upon as very superior to all the +families of crowned heads in the world. In consequence he sent to the +four quarters of the globe for the most illustrious professors, the +most skilful engineers, the cleverest and most ingenious workmen in +every department; and giving them unlimited permission as to +expenditure? ordered them to adorn his palace with all the wonders of +science and human industry. + +Science, and human industry, and unlimited means--what will they not +accomplish? No wonder that nothing was talked of for a hundred miles +around but the magic building--of which, by the way, I do not venture +to give you a description, because it would carry me too far away. Let +it suffice to say, that never Emperor of China, Caliph of Bagdad, or +Great Mogul had such a habitation as our banker, and for a very good +reason--he was twenty times as rich as any such gentry as I have named +ever were in their lives. + +When all was finished one trifling flaw was discovered: the place was +not supplied with water. A spring-seeker, who was summoned to the +premises, could only discover a small subterranean watercourse, a sort +of zigzag pipe, formed by nature, between two beds of clay, in which +the rain of the neighborhood collected as in a sort of reservoir. The +water was neither very clear nor very plentiful, as you may imagine; +and the professor appointed to examine it, having begun by tasting it, +made a horrible face, and declared there was no use in proceeding any +further; for it had a stagnant flavor which would not be agreeable to +my lord. + +To the amazement of every body, my lord jumped for joy when he heard +this unpleasant news. It was proposed to him to fetch water from a +river which flowed a few miles' distance off; but he would hear of +nothing of the sort. What he wanted was something new, unexpected, +impossible--that was his object throughout. He took a pen and drew up +at a sitting the following programme, which caused our poor professors +to open their eyes in dismay:-- + +1st. We will use the water on the premises. + +2ndly. It shall flow night day and in all parts of the palace at once. + +3rdly. There shall be plenty of it, and it shall be good. + +The professors looked at each other for some time without speaking, +and the gravest of them, whose fortunes and characters had been long +ago established, suggested that they should simply give my lord and +his money the slip, and so teach him to make fools of people another +time! + +But the youngsters, less easily discouraged, cried out against this +with one accord. They declared that the honor of science was at stake, +and that they ought to return impudence for impudence, by executing +to the letter the impertinent programme! At length, after much +discussion and many propositions made against all hope, and thrown +aside one after the other as impracticable, a sudden inspiration crossed +the brain of an engineer who had not yet spoken; and the following is +what he proposed:-- + +What prevented the water from being sweet and fit to drink, was the +want of movement and air. What had to be done, therefore, was to erect +a pump, but a pump provided with numberless small pipes, extending to +the watercourse in all directions, and so arranged that by means of +them it should be able to draw up the water from all the corners and +windings where it lay stagnating, and then forcing it forward into a +pipe terminating in a rose, like that of a watering-pot, whence it +should gush out to fall down in fine rain, into a reservoir in the +open air. From thence another action of the pump was to bring it back +well aerated, to send it once more into a large pipe with numerous +lesser ramifications, which should convey it into every corner of the +palace. + +Up to this point all seemed practicable, but the hardest part had not +yet come. The great difficulty was how to supply this enormous +consumption with so slender a runnel of water as the one at their +disposal. But our engineer had provided for this by a stroke of genius. + +Under each of the taps (always kept open), which were dispersed all +over the palace, he would place a small cistern, from the bottom of +which should go a pipe communicating with the body of the force-pump +which drew up the water from the original watercourse. By which means +the water which ran from the taps would be taken up again and go back +to feed the reservoir in the open air; whence it would again return +to supply the taps; and so on and on, the same water continually keeping +the game alive, as people call it. Have you not sometimes seen at a +circus or theatre a large army represented by a hundred supernumeraries, +who file in close columns before the audience, going out at one side +of the stage and coming in at the other, following close at each other's +heels indefinitely? By a similar artifice the engineer would change +his meagre little runnel into an inexhaustible fountain. The water +drawn up from the watercourse by each stroke of the pump would fully +compensate for what was used in its passage through the palace by the +inhabitants. Lastly, as it might sometimes happen that the said +inhabitants washed their hands under the taps, the water on its return +to the cisterns, was to pass through a series of small filters, in +order to cleanse it from any impurity it might have contracted by the +way. Always flowing, always limpid, it would soon lose every trace of +its original source, and might defy comparison with the water of any +river in the world! + +A unanimous buzz of congratulations welcomed this plan, at once so +simple and so bold, and our professors thought their troubles were +over, but they were not at the end of their difficulties yet. When it +came to the actual erection of the machine, (naturally a most +complicated one, as it had to set a-going a quintuple system of +pipes--pipes from the water-course to the pump, pipes from the pump +to the reservoir, pipes from the reservoir to the pump, from the pump +to the taps, and from the taps to the pump again,)--our banker, who +had got amused and excited as they went on, conducted them to a small +dark closet, only a few square feet in size, concealed in a corner of +the large apartments, and informed them with a laugh that he had no +other place to offer them. Besides which, he made them understand that +on account of its situation, there could be no question of furnaces +or boilers being set up there (he detested equally coal-smoke, fires, +and explosions)--nor of workmen employed about the machine (it would +not be decent to have them going up and down the front staircase)--nor +above all, of the frightful brake-wheels always screeching and +grinding, the unwieldy pistons rising and falling with a noise +sufficient to give one the headache. He himself slept near the little +dark closet, and the slightest noise was fatal to his repose. Having +explained all this, the rich man curtly made his bow and retired. + +For once our professors owned themselves beaten. They had come forward +quite proud of their invention, and now they were received, not with +ecstasies of delight, but with fresh demands, more ridiculous even +than the first. They were decidedly being mystified, and were preparing +in consequence to pack up and begone, furious, and swearing by all +their gods that they would never again expose science to see itself +disgraced by a purse-proud vulgarian's scorn; when, lo! happily, a +good fairy, the special friend of learned men, came passing by that +way. She raised her enchanted wand with the tip of her finger, and all +at once a little girl dressed in rags appeared in the midst of our +astonished professors. Without giving them time to recover themselves, +the child put her hand into the little patched waist of her dress, and +drew forth a rounded object, about the size of her closed fist from +which hung a quantity of tubes spreading in all directions. + +"See!" cried she; "here is the machine your banker demands of you." + +Picture to yourself a small closed bag, narrowing to a point at the +end, and separated within into two very distinct compartments by a +fleshy partition which went across the inside from the top to the +bottom. Such was the object held up by the little girl. Prom each of +these compartments issued a thick tube, ramifying into endless smaller +ones; and they were moreover each surmounted by a sort of pouch, into +which ran another tube, of the same description as the first. Each of +these four portions (the two compartments and their pouches) was in +constant but independent motion, distending and contracting alternately; +and by carefully examining the noiseless play of this singular machine, +(the walls of which were, by the magic power of the fairy, rendered +transparent to the bystanders,) the learned assembly were very soon +enabled to convince themselves, that it fulfilled all the +monstrousconditions exacted of them by the fantastic millionaire. + +All was in movement together, I told you; but let us begin at one end. +The right-hand compartment and its pouch represented the first pump; +the pump employed to draw, by the same stroke, the water from the +stagnant channel, and that from the taps. It was perfectly easy to +distinguish the two systems of pipes, and how they united together at +the small pouch on their arrival. When this was distended, a vacuum +was created inside, which was instantly filled by the liquid from the +tube which ran into it, (do not ask me why or how; I will explain that +presently). When it contracted again, the liquid which had just entered +was not able to get back, being prevented from so doing by a very +ingenious and simple contrivance, which requires a brief explanation. + +Take off the lock from your chamber-door, which opens inside; then, +standing outside, push against it with your shoulder, and you will get +in without any difficulty. But when you are in, try to push the door +open again with your shoulder in order to get outside into the passage, +and you will find that you will not be able to pass through, and this +simply because it does not open on that side. + +Which was exactly what happened to the liquid in the pouch! + +The door between the tube and the pouch only opened inwardly, and the +liquid finding itself pressed on all sides in proportion as the pouch +contracted more and more, and unable to return, was obliged at last +to make its way through another similar door which led to the large +compartment below. Here the same game recommenced. The compartment +which had distended itself to receive it, contracted in its turn, and +the liquid finding the road again barred behind it, had no choice but +to force its way through the tube which led to the air-reservoir. + +Here commenced the work of the second pump,--the pump of the left +compartment. The little pouch, when distended, was filled by the liquid +from the reservoir, and then forced it forward into the large +compartment below, always by means of the same process. This compartment +again drove it, by a powerful contraction, into the large conducting +tube charged with the office of its general distribution throughout +the body. At the end of all which, it returned once more into the +right-hand pump as before, to pursue the same course again, &c., &c. + +Thus, as you see, the whole mechanism turned upon two little points +of detail, of the simplest description possible; namely, first, on the +entrance-doors only opening on one side; and secondly, on the elastic +covers of the pouches and compartments distending and contracting +spontaneously. It was the prettiest thing in the world to see this +unpretending-looking little bag working thus, quite naturally, without +a suspicion that it was solving a problem which so many men, proud of +their science, had given up as hopeless. Certainly here was a machine +which made no noise! Once installed in its dark closet, it would have +been necessary to place your hand upon it to find out that it moved +at all. My lord could certainly sleep beside it without disturbance. + +"How much do you want for it?" said they to the poor little beggar +girl. "Name your price; have no fear; we will pay you anything you +wish." + +"I cannot give it to you," replied the child; "I need it too much +myself: IT IS MY HEART. Now that you have seen it, make another like +it, if you can." And she disappeared. + +It is said that the engineer, who longed to see his idea carried out, +tried hard to construct a similar machine with gutta-percha and iron +wires, and to set it in motion by electricity. But history does not +tell us that he succeeded, and we have yet to ask ourselves whether +the richest man in the world, aided by the wisest men in the world, +could ever provide himself with a miracle of wonder, such as the, +ragged child had received as a free gift from the hands of a gracious +Creator. + + + +LETTER XIV. + +THE ARTERIES. + +If you have thoroughly understood the story I last told you, my child, +it will have revealed to you the whole mystery of the _circulation +of the blood,_ and you are at the present moment wiser than all the +learned men of antiquity and the middle ages, for they had none of +them the faintest surmise of the truth. + +It may, perhaps, seem odd to you that men should have existed for +upwards of five thousand years without making inquiry into a matter +which so closely concerned them, and which was so easy to find out. +Is it not almost incredible that so many hearts should have beaten for +so long a period without any of their owners having felt a wish to +know exactly _why?_ Yet so it is. The action of the heart and the +flow of the blood have not been understood for much more than two +hundred years, and the man whose name is attached to this great +discovery richly deserves that we should say a few words about him. + +He was called Harvey. He was an Englishman; physician to King Charles +I., who was beheaded in 1648; and when he first ventured publicly to +teach that the blood was constantly circulating from one end of the +human body to the other, perpetually returning and retracing its steps, +a great scandal was created in the world. He was called a fool,--an +impertinent innovator,--a madman. His words shattered old doctrines, +and he only received for his reward all the petty annoyances which men +are apt to lavish so freely upon any one who tells them something new; +because--do you see?--it is so disagreeable to be disturbed in one's +habits and preconceived ideas. + +Harvey is not the only one in the history of mankind who has committed +the sin of being right in defiance of the opinions of his age. It is +true posterity takes account afterwards of the labors of genius, and +inscribes a fresh name upon her list. But one must pay for this glory +in one's lifetime. One cannot have everything at once. + +This is an old story, my child, but always new nevertheless; and for +my own part it is, I own, one of my pleasures to amuse myself by +reflecting how much cause for laughter three-fourths of the great men +of the present day are providing for the little girls who shall be +alive two centuries hence. Time is a great avenger, and puts many +things and men in their proper places. + +Let us pause here a moment while we are speaking of Harvey. I should +be curious to know what any one of the courtiers of Charles I., bedecked +in feathers, ribbons and laces, would have said to the valet who would +have placed the excellent Harvey, with his insane invention, above his +most gracious majesty, the lord and king of all Great Britain! And yet +what is his most gracious majesty to you to-day? What do you owe to +him? in what does he interest you? While you can never hear the name +of Harvey pronounced without remembering that you are under many +obligations to him! A thousand years hence, when society shall have +made the great progress which may reasonably be expected, the name of +Harvey will be familiar to every one who owns a heart, while that of +Charles I. will be only a vanished shadow; a souvenir lost in the maze +of history. + +Our debt of remembrance paid, let us return to the heart--the little +closed bag which labors so prettily. We must now inquire the real names +of whatever has figured in our story. + +The two great compartments are called _ventricles,_ the two small +pouches _auricles,_ and they are also distinguished as being on the +right or left side;--_right ventricle, left ventricle, right auricle, +left auricle._ + +The inner doors on which depends all the action of the machine, are +called _valvelets._ By-and-bye, when the pump and the steam-engine +are explained to you, you will meet again with these treacherous doors, +which never allow what has once entered to go back again; but then we +shall call them _valves._ + +The air-reservoir, I need scarcely tell you, is the _lung,_ to +which the blood goes to put itself in contact with the air. + +The subterranean watercourse, of which I hope we have talked long +enough, is _the small intestine,_ in which the _chyle_ collects; and +the tubes which run into it are, of course, the _chyliferous vessels,_ +the only channels by which anything reaches the heart which has not +previously gone out from it. + +The tubes of distribution, which run out from the machine in all +directions, are called with us _arteries_; the return tubes, which +bring back the water to the machine, are called _veins._ + +Finally, we have not exactly the _filters_ employed to clear the +water from the impurities contracted as it goes along, for no such +thing exists in us. There are in our case the refuse-chambers of which +I have already spoken, in connexion with the liver, where the blood +disembarrasses itself of any useless materials, and from which it comes +out with clean pockets, so to speak, reverting to the comparison of +which we have already availed ourselves. + +As you see, then, everything comes round again; and the bright idea +which our professors hit upon in order to satisfy the caprice of the +banker is exactly carried out in your own body, only a thousand times +more perfectly than could have been done by them all, even with all +their science added to all his money. + +I mentioned that the shrewdest of the party boasted about making an +artificial heart. But, let me tell you, there is one thing I would +have defied him to imitate, by any expedient he could devise, and that +is the inimitable construction of the _arteries_ and _veins,_ and the +incomprehensible delicacy of their innumerable ramifications. + +Let us talk a little about these marvellous tubes, and begin with the +arteries, which have the most important part to play. + +Did you ever see a doctor try the pulse of his patient? Take hold of +your own wrist and search a little above the thumb. You will soon find +the place and feel something beating against your finger. There is an +artery which passes there, and the little beating you feel is the +rebound of the pulsations, of your heart. Every time that the left +_ventricle,_ by contracting itself, chases the blood into the arteries, +these, of which the tissue is very elastic, become distended all at +once, and then contract again, repeating the process whenever a fresh +gush of blood arrives, so that their movement is exactly regulated by +the movement of the heart. It is true the two movements are in a +contrary direction; that is to say, the artery becomes distended, while +the heart contracts, and contracts when the heart enlarges itself; but +that makes no difference to the doctor. What he wants to know is, with +what force and rapidity the heart of the patient beats, and I will +explain why. It is an interesting point in the history of circulation. + +When you were very little--very little indeed, my dear child--your +heart beat from 130 to 140 times in a minute. Afterwards the beats +sank to 100 per minute; then to fewer still. At present I cannot tell +you the precise number: perhaps, about ninety. When you are a grown-up +young lady, it will beat about eighty times in the minute; when you +are a mother, about seventy-three times; when a grandmother (if such +a blessing be granted you), only from fifty to sixty times, perhaps +even fewer. People tell of an old man of eighty-four whose heart beat +only twenty-nine times in the sixty seconds. + +Observe that in all my calculations I have taken special care to prefix +the word _about_ to the numbers mentioned. And this because, in +point of fact, the heart is a capricious creature, which has no exact +rules to go by. It changes its pace on every occasion--fear, joy, every +emotion which agitates the soul, quickens or retards its movements; +and derangements of health may be detected by its pulsations, which +are infinitely varied in character. In fever, for instance, which is +nothing but a race of the blood at full speed, the hearts of grown-up +people beat as quickly as those of little children; sometimes, indeed, +more quickly still. In certain maladies it goes with great sudden +leaps, like a galloping horse; in others it trots in little jerks; +while in some cases it moves slowly and wearily, and its throbs are +so weak that one can scarcely feel them. + +These pulsations, then, afford important revelations to the doctor. +The heart is for him a gossiping confidant, who lets out the secrets +of illnesses, however closely they may fancy themselves hidden in the +remote depths of the body. When the doctor lays his finger on the +patient's pulse, it is precisely the same thing to him as if he had +laid it on his heart, only with this difference, that the one is much +less difficult to do, and much sooner done than the other. + +The artery of the wrist is in fact a small heart, not only because it +follows all the movements of the large one, but because it carries +forward the work which the other begins, and assists also in propelling +the blood to the furthest extremities of the limbs, driving it on in +its turn at each of its own contractions. Imagine a fire-engine, whose +pipes should take up and drive forwards along their whole length the +water which is thrown upon the fire, and you will have some idea of +the marvellous machine which is at work in our behalf within us. Nor +are you to suppose that the wrist-artery is a specially privileged +one, because it has been chosen to hold intercourse with physicians. +All the others are equally serviceable; and if they cannot all be +used for "feeling the pulse," it is because they are generally more +deeply buried in the flesh, where it is not easy to reach them. + +Observe your mother when she is packing a trunk, and you will see that +whatever she is most afraid maybe spoiled, she is most careful to put +in the middle, so that it may be least exposed to accidents. And this +is what a kind Providence has done with the arteries, which have the +utmost cause to dread accidents; whilst the veins, which are much +better able to bear rough usage, are allowed to wander about freely +just under the skin. But when the bones happen to take up a great deal +of room, and come near the skin themselves, as is the case in the +wrist, the artery is forced, whether he likes it or not, to venture +to the surface, and then we are able to put our fingers upon him. + +And there are others in the same sort of situation; the artery of the +foot for instance. But only just think how far from agreeable it would +be to have to take off your shoe and present your foot to the doctor! + +The artery which passes to the temple, just by the ear, is another +affair. That would answer the purpose very well in fact, and I even +advise you to make use of it when you want to feel your own pulse. It +is more easily found than the other even, and its pulsations are still +more easily perceptible. Nevertheless, when all is said and done, it +is better for the doctor to take his patient by the hand than by the +head. Merely as a matter of good manners. + +I will now make you acquainted with the principal arteries, and the +manner in which they distribute the blood through the body. + +The whole of the blood driven out by the left ventricle at each of its +contractions, passes into one large canal called the _aorta_. The +_aorta_ as it goes away at first ascends; then bends back in a curve; +and from this curve, which is called the _arch of the aorta_ (from its +shape) diverge right and left, certain branch-pipes which carry the +blood into the two arms and on each side of the head; and which are, in +fact, the beginning, or upper end, of those whose pulsations we feel +with our fingers in the two wrists and at the temples. + +The supply to the upper part of the body being secured, the _aorta_ +begins to descend. But now imagine of what importance it must be, that +this head-artery--the foster-father of the whole body--should be +sheltered from every accident. The _aorta_ once divided, death is +inevitable; you might as well have your head cut off at once; and +thus it has been fixed in the best--that is to say, the safest--place. +Of course you know what is meant by the _backbone_ or _spine_, called +also the _vertebral column_, in consequence of its being made like a +sort of column composed of a series of small bones fastened together, +which are named _vertebrae_. Touch it and feel how solid it is, and how +few dangers there can be for anything placed behind it. Well, that is +the rampart which has been given to the _Aorta_. As this descends, it +slips behind the heart and takes up its place in front of the _vertebral +column_ which it follows all the way down the back, just to the top of +the loins. There it is, so to speak, almost unassailable; in fact hardly +any cases are known of the _Aorta_ being wounded; to get at it, it would +be necessary to bestow one of those blows which used to be given in the +time of the Crusades, which cut the body in two. There was an end of the +_Aorta_, as of every thing else then; it was unfortunately not worth +talking about any longer! + +The next time you see a fish on the table, ask to be shown the large +central bone. It is the fish's _vertebral column_, and it will give you +an idea of your own, for it is constructed on the same plan. You will +perceive a blackish thread running all along it--that is _the aorta_. + +As it descends, the _aorta_ sends off on its passage a great number of +arteries which carry the blood into all parts of the body. Arrived at +the loins it forms a fork; dividing into two great branches, which +continue their descent, one on each side the body, down to the very +extremities of the two feet. + +As you perceive, dear child, this is not very difficult to remember. +A large fork, whose two points are at the tips of the feet, the handle +of which curves at the top like the crook of a crozier; from this curve +come four branches, which pass into the two arms and to the two sides +of the head--and this is the whole story. But of course, it would be +another affair were I to enter into the detail of all the ramifications. +Here it is that all engineers, past, present, and future, are baffled, +defeated and outdone! Choose any place you please upon your body, and +run the finest needle you can find into it what will issue from the +puncture? + +"Thanks for the proposal," you say; "I have no occasion to try the +experiment, to discover that blood will come out." + +You say that very readily, young lady; but have you ever asked yourself, +what is implied by your being so sure before hand that you can bring +blood from any part of your body if you choose to prick it, though +never so slightly? It implies that there is not on your whole frame +a spot the size of a needle's point, which has not its own little canal +filled with blood; for if there were such a one, there at any rate the +needle would pass in without tearing the canal, and causing the blood +to flow out. And now count the number of places from the top to the +bottom of your dear little self, on which one could put the point of +a needle, and even when you have counted them all, do not fancy you +have arrived at the number of the tiny tubes of blood. Compared to +these, your needle is a coarse stake, and tears not one but a thousand +of these little tubes in its passage. + +That seems to you rather a strong expression, does it not? But let me +make good my boldness. A needle's point is very fine, I admit; but a +person who could not see it without spectacles must have very poor +sight. Whereas the last subdivisions of the blood-tubes are so +attenuated, that the best eyes in the world, your own included, cannot +distinguish them. You are astonished at this, and yet it is nothing +compared to what follows. + +No doubt you have heard of the microscope,--that wonderful instrument +by which you may see objects a thousand, a hundred thousand, a million +times, if necessary, larger than they really are. With the microscope, +therefore, as a matter of course, we can see a good many of those tiny +canals which elude our unaided sight. But, alas! we discover at the +same time that these are by no means the last subdivisions. The canals +invisible to our naked eyes subdivide themselves again into others, +and these into others again, and so it goes on, till at last--the man +at the microscope can see no more, but the subdivisions still continue. + +You were ready to exclaim, at my talking of thousands of canals being +torn by a needle in passing through; but had I even said millions, it +may be doubted whether I should have spoken the whole truth. + +Besides, when you consider the office of the blood, you can easily +understand that if there were a single atom of the body left unvisited +by him, that atom could never be nourished. Do I say nourished? I have +made here a supposition altogether inadmissible; it could have no +existence at all, since it is the blood only which produces it. + +These imperceptible canals of blood have been called _capillaries_, +from the Latin word, _capillus_, which means a hair; because the +old learned men, who had no suspicion of the wonders hereafter to be +revealed by the microscope, could think of no better way of expressing +their delicacy, than by comparing them to hairs. Very likely they +thought even this a great compliment, but your delicate fair hairs, +fine as they are, are absolute cables--and coarse cables too, believe +me, compared to the _capillary vessels_ which extend to every portion +of your body. + +Observe further, that each of these arterial _capillaries_ is +necessarily composed (being the continuation of the large ones) of +three coats enclosed one within the other, which can be perfectly +distinguished in arteries of a tolerable size; add to this that within +these coats there is blood, and in the blood some thirty substances +we know of, not to speak of those we do not know; and then you will +begin to form some notion of the marvels collected together in each +poor little morsel of your body, however minute a one you may picture +to yourself. + + + +LETTER XV. + +THE NOURISHMENT OF THE ORGANS. + +When I said formerly that our dear and wonderful steward the blood, +was everywhere at once, you little suspected the prodigies involved +in that _everywhere_. But you will have a glimpse of them now, when I +tell you it is at the extremities of the _capillary arteries_ that he +carries on his distribution of goods, and accomplishes a mysterious act +of nutrition; a wonder much greater even than that of which we have just +spoken. Here, indeed, the question is no longer mechanical divisions, +whose delicacy, surprising as it may be, is yet within our powers of +comprehension. What is more surprising still, what moreover we cannot +comprehend at all, is the delicate sensitiveness of tact--I would almost +say of instinct--with which each one of the million millions of tiny +atoms of which our body is composed, draws out of the blood--the common +food of all--exactly that aliment which is necessary to it, leaving the +rest to his neighbor, and this without ever making a mistake. + +You have never thought about this; for children go on living at their +ease, as if it was the simplest thing in the world to do; never +suspecting even that their life is a continued miracle, and never, of +course, therefore, feeling bound to be grateful to the Author of that +miracle. And alas! how many hundreds of people live and die children +in that respect. + +But what would happen, I should like to know, if the eye took to seizing +upon the food of the nail, if the hairs stopped on the way what was +intended for the muscles, if the tongue absorbed what ought to go to +the teeth, and the teeth what ought to go to the tongue! Yet what +prevents their doing so? Can you tell me? They all drink alike out of +the same cup. The same blood goes to furnish them all. The substances +that it brings to the eye are the same as those which it brings to the +nail; and nevertheless the eye takes from it that which makes an eye, +and the nail that which makes a nail. + +How is this done, do you think? that is the question. + +When the doctors reply to this, that each organ has its peculiar +sensibility, which makes it recognize and imbibe from the blood one +particular substance and no other, they are strangely mistaken if they +flatter themselves that they have really answered anything. They have +done nothing but reproduce the question in other words, for it is +precisely that sensibility which requires explanation, and to tell us +that it exists, does not explain much, you must own. If you were to +ask why you had got a headache, and some one were to reply that it was +because your head ached, you would not be much the wiser I fancy. + +Each of our organs, then, may be considered as a distinct being, having +its separate life, and its particular likings. These organs behave +towards the blood like men who recognize some friend in a crowd, and +proceed to seize him by the arm; and when I told you just now that +they never made a mistake, I spoke of their regular course of action +in ordinary circumstances. Like men, they also make mistakes sometimes, +in certain cases; and take one substance for another, or do not +recognize the one they are in need of; an unanswerable proof that at +other times they exercise a sort of discernment, and do not act by a +sort of fatality, as one might be tempted to believe. Look at the +bones, for instance. They are composed of _gelatine_ (which cooks +serve up under the name of meat-jelly, but which would be more properly +called bone-jelly), and of phosphate of lime, a kind of stone of which +we have spoken before, if I remember rightly, and from which they get +all their solidity. Originally, the substance of the bone is entirely +gelatinous, and the phosphate of lime deposits itself therein by +degrees, as time goes on, and always in greater abundance as we advance +in age. + +Properly the bones borrow only gelatine and phosphate of lime from the +blood. But when they come to be broken, their texture or _tissue_ +inflames in the fractured place; and then it changes its tastes, if +I may so express myself; and, lo and behold, extracts from the blood +that which forms certain little fleshy shoots, which unite together +from the two sides of the fracture, and so mend the broken bone. Here is +one exception to the rule. + +Again, in certain diseases, the bones suddenly quarrel with the +phosphate of lime; they will not hear of it any longer, they will not +accept a fresh supply; and as the old wears out by degrees, by reason +of the continual destruction of which I spoke the other day, the bones +become more and more enfeebled, and soon can no longer support the +body. A second exception this. + +Finally, when old age comes on, the bones end by being so much +encumbered with phosphate of lime, that they have no room to admit the +fresh supply which keeps coming to them in the blood. What becomes of +it then? It goes to seek its fortune elsewhere; and there are charitable +souls, who forgetting their instinctive antipathies, consent to give +it hospitality, though much to the prejudice of the poor old man +himself, who is no longer served so well as formerly, by the incautious +servants who have allowed themselves to be thus fatally beguiled; but +no one consults him. It is the arteries especially, and sometimes +the muscles, which take this great liberty, and it is not unusual among +old people to meet with these fairly _ossified_--that is to say, +changed into bone, thanks to the phosphate of lime with which they +have consented to burden themselves. This is a third exception, and +I will spare you any others. + +What may we infer from all this, my dear child? Well, two things. +First, that we know nothing at all about the whole affair; a fact which +at once places us on a footing with the most learned philosophers in +the world. Secondly, that our body is a perpetual miracle; a miracle +which eats and drinks and walks, and which we must not look down upon +for so doing: for God dwells therein. I should have to come back to +this at every turn, if I wanted to fathom everything I have to tell +you about. Each tip of hair which you grow, is an incomprehensible +prodigy which would puzzle us for ever, if we did not call to our aid +those eternal laws which have made us what we are, and to which it is +very just our spirits should submit, since we could not exist for one +second were they to cease from making themselves obeyed in our bodies. + +Reflect on this, my dear little pupil. Young as you may be, you can +already understand from it, that there is above you something which +demands your respect. The good God, to whom your mother makes you pray +every night, on your knees, with folded hands, is not so far off as +you might perhaps suppose. He is not a being of the fancy, secluded +in the depths of that unknown space which men call Heaven, in order +to give it a name. If His all-powerful hand reaches thus into the +innermost recesses of your body, His voice speaks also in your heart, +and to what it says you must listen. + + + +LETTER XVI. + +THE ORGANS. + +Contrary to my custom, my dear child, I made use, in the last chapter, +of a new word, without giving an explanation of it. + +I spoke to you of _our organs_, and we have not yet ascertained what an +_organ_ is. + +You probably knew what I meant, because it is a word which is used in +conversation and pretty well understood by everybody. But I am bent +upon giving you a more exact idea of it, for the trouble will be well +bestowed. If I did not do this at once it was because there is a good +deal to tell about, and that would have carried me too far away from +my subject. + +_Organ_, comes from the Greek word _organon_, and means _instrument_. It +was used particularly to signify instruments of music, so much so that +our word "organ" comes from it. Our bodily organs then, are +_instruments_, or _tools_ if you like it better, which have been given +to us, wherewith to perform all the acts of life; and as there is not +one part of the body which is not of use to us for some purpose or +other, our body is, in point of fact, from head to foot a compound of +_organs_. Thus the hand is the tool which we make use of to lay hold of +anything--so an _organ_; the eye is the instrument of sight--so an +_organ_; the heart is the machine which causes the blood to circulate--so +an organ; the liver fabricates the bile--it is an organ therefore; +the bones are the framework which support the weight of the body--so +organs; the muscles are the power which sets the bones in movement--organs +also, therefore; the skin is the armor which protects them--so an +organ: in fact everything within us is an organ. If there was any corner +of our body which was not an organ, it would be useless to us, and we +should not, therefore, have received it, because God makes nothing +without a use. + +Here lies the secret of that great miracle which is called life. I do +not know whether you will be able to understand me thoroughly, but +open your ears, as if some one was going to explain addition to you; +this is not more difficult. + +Life is in reality the total of an addition sum. Each one of our organs +is a distinct being which has its particular nature and special office; +its separate life consequently; and our individual life is the sum +total of all these lesser lives, independent one of the other, but +which nevertheless blend together by a mysterious combination, into +one common life, which is everywhere and nowhere at the same time. It +follows from this, that the more organs a being has, the greater is +the sum total; the more, consequently, is life developed in him. +Remember this when we begin to study life in the lower animals. In +proportion as you find the number of _organs_ diminish, you will +find life diminishing in power, until we arrive at beings who have, +as it were, only one organ apparent, and whose life is so insignificant, +that we have some difficulty in giving an account of it, and are saying +the utmost that can be said in calling it life at all. + +But this comparison of life to the total of an addition sum, is too +dry; and, although it has its appropriate side, yet it might give you +a false idea of life; which is what always happens when one tries to +solve inscrutable questions and hidden mysteries by a matter-of-fact +illustration. + +Let us try for something more to the purpose. + +I told you that the Greek word _organon_ was applied especially +to instruments of music. Well, let us consider our organs as so many +musical instruments. You have, probably, sometimes been at a concert. +Each of the instruments in the orchestra performs its own part, does +it not? The little flute pipes through all its holes; the double-bass +pours thunder from its chords: the violin sighs with his; the cymbals +clash; the Chinese bells dance to their own tinkling; all go at it in +their own fashion, each independently of the other. And yet, when the +orchestra is in good tune together, and well played, you hear but one +sound; and to you the result of all these various noises, each of which +would have no meaning alone, is music composed by some great artist +whom you do not see. It is no longer a flute, a double-bass, or a violin +which you hoar; it is a symphony of Beethoven's, an oratorio of Haydn's, +or Mozart's overture to _Don Juan_. + +Life is just like this. All the instruments are playing together, and +there is but one music; music written by God. + +But wait! when I say _life is just like this_, let us come to an +understanding. Life is _some_thing like it, that is all, for as +to telling you what life is, I shall not attempt it. I know nothing +about it, do you see, though that is a painful confession to have to +make to a pupil; but in this case it does not distress me, and you are +welcome to hunt the world through for a master, who in this matter +does know anything. I could make a hundred other comparisons, but +theywould all fail in some point or other. Shall I tell you where this +one fails? In an orchestra there is always a musician by the side of +the instrument. Now with us we see the instrument well enough, but we +cannot see the musician. + +You are inclined to ask me, perhaps, why I am wasting so much paper +to-day in talking to you about organs, instead of going on tranquilly +with our little history of the circulation. But I told you just now +that the secret of life lies in the organs, and before entering upon +the history of life, I ought to have begun with them. It is there all +the books begin which treat of the subject we are studying together, +and if you had one in your hands at this moment, it would teach you +that all creatures whatsoever are divided into those which have organs +and those which have none--that is, into _organic_ and _inorganic_ +beings [Footnote: A lump of iron is the same throughout. Each of its +parts has the same properties and the same uses. It has no organs, it is +an _inorganic_ being. A rose tree has flowers, which are differently +made from its leaves, and serve a different use: a root which sucks up +the precious food of the earth; a bark which is of a different nature +from the wood, and serves a different purpose. It has organs; it is an +_organic being_: all animals and vegetables are _organic beings_.] (_in_ +stands here for _not_, as _in_complete means not complete). + +This is, in fact, the starting point for the study of nature, and there +are many other things besides which I ought to have told you before +I began. But we went straight ahead, without looking at what we were +leaving behind, satisfied with turning aside from time to time to pay +our debts. + +And while I am making my confession, I ought to tell you all. You would +probably only have listened to me with half an ear, if I had begun at +the beginning. There is a proverb which says--"The appetite comes with +eating." I do not advise you to follow this proverb too closely at +dinner, for it might mislead you sadly. But it is always true when +applied to learning; it is what one knows already that gives one a +taste for learning more. If I have been making you bite at the organs +to-day, which is rather a tough morsel, it was because I fancied that +your appetite had begun to come. Was I wrong? + +Let us now return to the blood which nourishes the organs. + + + +LETTER XVII. + +ARTERIAL AND VENOUS BLOOD. + +It is at the extremity of the capillary arteries, as we have said, +that the incomprehensible prodigy of the nourishment of our organs is +accomplished. This done, the next thing is for the blood to return to +its starting-point; and here recommence those infinitesimally minute +wonders of which we have already spoken. Close upon the capillary +_arteries_ follow the capillary _veins_, equally fine and imperceptible +as the others. These take possession of the blood everywhere at once, +without allowing it a moment's respite, and it is thenceforth on its +road of return, travelling back again to the heart. + +Where do the veins begin? where do the arteries end? No one can say +precisely, since the last ramifications of each elude the eye of man, +however much it may be aided by the admirable instruments which his +genius has invented. Nevertheless, although no one has ever ascertained +the fact by sight, there is one thing I can tell you--namely, that our +minute veins are a continuation of our minute arteries, and that it +is the same canal which as it lengthens out turns from an artery into +a vein, without any interruption; the substances destined for the +nourishment of the organs passing through its walls, as moisture passes +through our skin when we perspire. + +But if nobody has seen this, say you, how can they know it for a fact? + +Let me explain. In man, and in the animals which come nearest to man +in structure, it has never been seen; but it has been seen elsewhere. +This requires a little explanation, and you will not regret my giving +it hereafter. It has its interest, I assure you. + +When you put your hand on your throat, how does it feel to you? +_Warm_, does it not? And when you take hold of a kitten or a bird, +how do they feel? _warm_ in the same way. Now, then, can you tell +me whence comes this warmth? But to save time I will answer the question +myself. It comes from their and your _blood_, which is itself warm, and +we shall soon see why. You have no idea of all the curious facts wrapt +up in that little phrase, "You are warm-blooded;" your blood is warm. +But it has not got warm of itself; bear that well in mind. + +Now if you touch a frog, a lizard, or a fish, how do they feel to you? +Cold, of course, you answer. But I ask why? A question you will answer +in the same way as the other. Because their blood is cold, they are +"cold-blooded." + +Precisely; and while you are about it you may add that, if their blood +be cold, it is because it has not been warmed as yours is. Do not be +impatient, we shall make all this clear at the proper time and place. + +Now in the cold-blooded animals, such as serpents, frogs, tortoises, +lizards, fishes, and others, the blood circulates as it does in us, +and what is more, it does so, thanks to a machinery very similar to +our own. But, as you may imagine, a machine which produces warmth must +be constructed in a more perfect manner than a machine which produces +no warmth; and to speak truth, without flattering you, there is a +little difference between you and a frog, and it seems natural enough +that the body of a frog should be more clumsy in structure than yours. + +It is the old story of the poor man being not so well lodged as the +rich; but putting aside rich and poor, who are all human beings alike, +let us take one of those lovely dolls who walk, and move their arms +and head, and say papa! and mamma! and compare it with a cheap bazaar +doll which you can get for a penny. Both are made, in the main, in one +way. Each has two arms, two legs, a mouth, a nose, eyes, &c.; but what +a difference in the details of the two! and what infinitely more pains +have been bestowed on one than on the other! + +Well, cold-blooded animals are, so to speak, _penny doll_ animals, +by comparison with ourselves. Like us they have arteries and veins, +but there is not near so much workmanship in them; and that marvellous +delicacy of the capillary extremities, which in man and in the +warm-blooded animals drives the close observer to despair, does not +exist to trouble us in these others. It is true that with the naked +eye we are still unable to see everything, even in them; but with the +help of the microscope the whole is laid open to us--the extremities +of the arteries and the extremities of the veins; and it was here that +what I was telling you of, just now, was observed and discovered,--namely, +that the end of the artery changes into a vein, without any +interruption in the tube. It was these very observations upon fishes and +frogs, which eventually gained the day in favor of Harvey's ideas on the +circulation of the blood, at which the learned men of his own age had +laughed so much. He was dead by that time it is true, as has happened +but too often in such cases, but do not let us pity him too much! He who +has had the rare good-fortune to lay hold of a new truth, and launch it +into the world, is sufficiently recompensed in advance. If he also +craves after the flattering voice of man's approbation, and the toylike +pleasure of personal triumph, he is after all but a child, unworthy of +the great part God has given him the privilege of playing. + +A child, did I say? Then how rude you must have thought me, dear child! +And as a punishment, you are perhaps going to remind me that I have +once more fallen into my old bad habit of wandering away from my +subject. Never mind, I am going to return to it at once. + +How can one distinguish--you will ask me--an artery from a vein, so +as to be able to determine which is a vein and which an artery? + +In many ways, I reply. First of all, an artery, as I told you lately, +is composed of three coats, of which the principal, _i.e._. the +inner one, is tough and elastic, whereby the artery is enabled to force +the blood forward in its turn, but which is also the reason of arterial +cuts being so dangerous; for in such cases the wounded tube remains +wide open; being held so by the stiffer inner coat; and thus the blood +is allowed to run out indefinitely. Now this inner coat is wanting in +the veins, whose walls sink in together when a cut is made in them, +so that it is much easier to stop the flow of the blood in them. + +Furthermore, the veins are furnished inside at intervals with little +doors, similar to those we noticed at the entrance of the _auricles_ and +_ventricles_ of the heart. You remember those important _valvelets_, on +which depends so much of the mechanism; which permit the blood to pass +in one direction, but will not allow it to return back in the +other?--well, the little doors of the veins, which are also called +_valvelets_, do exactly the same work. They open in the direction of the +heart, to allow the blood to pass on, but it finds them fast closed if +it wants to go back; so that as soon as it has forced one passage there +is no longer any hope of its return, and thus by degrees it gets nearer +and nearer to the heart without any possibility of escape. There is +nothing similar to this in the arteries, which the blood traverses in a +single bound from the impetus it receives from the heart. + +Finally--and this is most important--the blood which is found in the +veins is no longer the same as that which fills the heart. + +No longer the same? you exclaim--have we then two sorts of blood in +our bodies? Most certainly, my dear child; but you would not have +suspected it; for when you accidentally prick or cut yourself, or when +your nose bleeds, it is always the same sort of blood that comes +out--that fine red liquid which everybody knows so well by sight. This +is because the blood flows at once from the small arteries and small +veins, and what you see is a mixture of the two. The same mixture +issues from all wounds, whether small or great, and on this account +people are unanimous in declaring that blood is red; a statement which +is not true of either arterial or venous blood, separately. The last +is black, as you might convince yourself if you had courage enough, +and should happen to be in the room with any one who was going to be +bled,--a rare event, happily, in these enlightened days. + +In such a case it is always a vein which is opened, the reason of which +you will understand, after what I said of the danger of cutting the +arteries. You would there, fore see a reddish black jet of liquid spout +from under the lancet; much blacker than red, however--that is +_venous_ blood. When, on the other band, an artery has been accidentally +cut, what comes out is quite different. It is a rosy, frothy fluid, +almost like milk and carmine dissolved in it, which has been whipped up +with a stick; this is called _arterial_ blood. + +Nothing is more simple, as you perceive, than to distinguish an artery +from a vein; you have only to ascertain what is inside of it. When the +blood goes out to our organs to nourish them, it is _arterial_; when it +is returning back after having nourished them, it has become _venous_. +But what--you will ask--is it going to do now at the heart, towards +which it is on its road? It is going to seek there a fresh impetus which +shall send it once more into the lungs, where it will again become +_arterial_, _i. e._ and once more capable of affording nourishment to +the organs. Therein lies the whole secret, and the why and the wherefore +of the CIRCULATION. + +This is easily said, dear child; but suppose that you do not comprehend +it? Well, you need not be ashamed. There is no possibility of +comprehending it until one has learnt what RESPIRATION is--so here we +are stopped short. + +To-morrow, then, when we will begin with the study of this third part +of the History of Nutrition; and if the first two have amused you, I +feel pretty sure you will not find this last one dull. + + + +LETTER XVIII. + +ATMOSPHERIC PRESSURE. + +When we have been laboring very hard, my dear child, and want to rest +for a minute, we say, _Let us take breath_; because breathing is +an action which takes place of itself, requiring neither effort nor +attention on our part. + +But, if it takes place of itself, it does not explain itself; +consequently, when I say to you, _Now, let us take breath_, this +is not a signal for my having a rest, for I have undertaken to explain +Respiration to you. + +If you were a German, I would remind you of what so often happens when +you put a fork into a dish of sour-krout. You want to lay hold of a +little bit merely, but the strips of cabbage-leaf are twisted one +within the other, and hang together in spite of you, so that +withoutintending it you get hold of a whole plateful at once. + +Now this Respiration affair is something like the sour-krout +story--begging your pardon for the comparison. I should have liked to +give you only a small plateful--a child's plateful--of it; but I feel +the explanations coming, hanging one upon the other; and, whether I +will or no, I must treat you like a grown-up person, and we must give +up for once the nice little doll's dinners with which we began. + +In my opinion, you will lose nothing by the change if you will but pay +attention; for about that soft little breath of yours, which is always +coming and going over your pretty lips, there are many more things to +be learnt than you have heard of yet. As I said just now, you will +find you have got hold of a plateful all at once. A good appetite to +you! + +To prevent confusion we will divide the subject into two parts. I shall +explain to you first, _How we breathe?_--a very curious question, +as you will see. And afterwards we will examine, _Why we breathe?_--which +is still more interesting. + +First, I must tell you that air is heavy, and very heavy too; a thousand +times more so than you may suppose. The air we breathe, through which +we move backwards and forwards, that air is _some_thing, remember, +although we do not see it; and when there is a wind, that is to say, +when the air is in motion, like a stream of water running down a hill, +we are forced to acknowledge its being something, for we see it throw +down the largest trees and carry along the biggest ships. But without +going so far out of the way for examples, try--you who run so well--to +run for two minutes against a strong wind: and then you shall tell me +whether the air is something or nothing. But if it be something it +must have weight, for all substances have; paper as well as lead; with +this sole difference, that the weight of lead is greater in proportion +to its size than that of paper. Now a sheet of paper is very light, +is it not? and you would be puzzled perhaps to say what it weighs. But +many sheets of paper placed one upon the other, end by forming a thick +book which has its undeniable weight; and if some one were to heap +upon your head a pile of large books, like those you see on your papa's +shelves, the end might be that you would be crushed to death. + +In the same way, a small amount of air is by no means heavy; but you +can conceive that a great quantity of it gathered together may end by +weighing a great deal. Now get well into your head the fact, that we, +here, on the surface of the earth, are at the bottom of an immense +mass of air, extending to somewhere about forty or fifty miles above +our heads. Let us say forty to make more sure, for learned men have +not yet been able to calculate the precise height to a nicety; and for +my own part, I think we have done wonders to get so near the mark even +as this. But can you picture to yourself the distance which forty miles +high really is? I will help you to form some idea. + +One mile contains 5,280 feet, and your papa is six feet high. One mile +high would therefore be 880 times as high as your papa, But this is +a mere nothing--only one mile's height. In forty miles there would be +no less than 211,200 feet; and setting papas aside, of whom it would +take 35,200, one on the top of the other, to go so far into the sky, +let us think of the height of the tallest buildings you know; church +and cathedral towers for instance. Now the towers of many parish +churches are 150 feet high; the towers of York Minister not 300. At +that rate it would take 1,408 ordinary parish church-towers, or upwards +of 704 York Minster towers, piled one above the other, to reach to the +end of the forty miles of air above our heads. I leave you to judge +what would be the weight of a mass of paper piled up as high as that. +You may safely grant then, that this mass or pile, or if you like it +better, this _column_ of air (for that is the proper expression), +must be of considerable weight; as is still further made certain by +the fact of its having been weighed, so that I can even name the weight +to you if you wish to hear it. Bear in mind too, that the weight of +a column of air will be in proportion to its _superficial extent_--to +its breadth and width, that is; for, as you may suppose, a column as +large in extent as one of the towers of York Minster will weigh a good +deal more than one the size of a single brick. + +But wait; here is a book on the table which will serve me for a measure, +and as you will probably find the same on your mamma's table, you can +follow my measurement. It is a French Grammar. The back is seven inches +long and four and a quarter wide. That is, there are four and a quarter +rows, each seven inches long. In other words, the back contains +nearly--and let us call it quite, for convenience' sake--thirty inches +side by side. Thirty _square inches_ as it is called. Measure your +mamma's copy and you will see. Now, can you guess the weight of the +column of air forty miles high which this volume supports? Upwards +of four cwt.; 450 lbs., that is to say. If you want to be very exact, +here is the rule. Air presses on all bodies at the rate of fifteen +pounds to every square inch; so now you can make the calculation for +yourself. + +But I suspect you had no idea you were so strong; for I see you tossing +up the book, heavily laden as it is, like a feather. + +Comfort yourself. There is no magic in the matter. If a very strong man +were to push you on one side, could you resist him? Certainly not. But +if another man of equal strength were to push you at the same time on +the other side, what would happen? Well, you would remain quietly in +your place, without troubling yourself more about one than the other, +the two forces mutually destroying each other. And this is the case +here. While the air above your book is weighing down upon it with a +force of 450 lbs., the air below it presses against it underneath with +an equal weight, and this destroys the effect of the other. From 450 +lbs. take 450 lbs., and nothing remains. Your grammar has nothing to +carry after all, and you may toss it about as you please, without +deserving much credit for the effort. + +"What are you telling me?" you inquire. "If I put a stone on the top +of my head, I can feel its weight easily enough; but if I put my hand +on the top of the stone I no longer feel anything. How can the air +below the stone press against it? And talking of columns--how pleasant +it would be, for instance, if the people who go up the Monument were +to have the weight of it on their heads when they get to the top!" + +Well said, little one. And your objection reminds me of an argument +which distracted my head as a lad, when I first heard the pressure of +air explained by a good fellow who did not trouble himself to be quite +as exact as you and I are in our discussions. I was told that the +surface of the body, or the skin of a large man, measured sixteen feet +square, which is equal to the surface of a table four feet long and +four broad. Now, you know that in four feet there are forty-eight +inches, and on the surface of the table are forty-eight rows, with +forty-eight inches in each, or 2,304 square inches; so that a man's +surface is 2,304 square inches, and the weight his body supports is +34,560 lbs., or upwards of fifteen tons--always at the rate of fifteen +pounds to every square inch, you understand. Now, I was constantly +asking myself how it happened that in entering a house one never seemed +to get rid of this almost fabulous weight, since the roof of the house +must naturally interpose itself between the air-column of forty miles +high and the man who would then only have some few feet of air above +his head. The roof would support the rest, that was clear. From whence, +then, came the 34,560 lbs. which seemed to weigh as heavily as before; +since, whether on the threshold of the door, while still under shelter +of the roof, or two steps outside in the open air, under the tremendous +column forty miles high, one never felt a bit lighter, not even to the +extent of the weight of a single sheet of paper? This was a difficulty +from which I could never extricate myself. + +I found out the answer to the riddle afterwards, and a very simple one +it is. + +Air does not, in point of fact, _weigh down_ like a solid fifty +pounds' weight, which has no impulse but to descend, and has nothing +to do with anything above it. It _presses against_ rather, like +a spring, which, having been compressed, tries to resume its natural +position with a force equal to that which holds it back. Ask some one +to show you the spring of a watch, and you will understand this better. +Each atom of air is a spring of matchless elasticity, which nothing +can break, which never wears out, which one can always compress, if +one employs force sufficient, and which is always ready to expand +indefinitely, in proportion as the compressing power is withdrawn. + +Now, consider the column of air outside the door, where there is a +pile of such springs forty miles high. The lower ones have to bear up +all their comrades, which press upon them with their united weight, +and these make desperate efforts to repulse the tremendous pressure, +and to spread out in their turn. They endeavor to escape in every +direction--to the right, to the left, above, below; but caught between +the earth, which will not give way, and the compact mass of all the +columns of air which surrounds the earth in every direction, and of +which the lower part is equally compressed everywhere, they struggle +unceasingly, but in vain; indefatigable, but powerless. You live in +the midst of those little wrestlers, and naturally bear the punishment +of the injury done to them. They press against you as against every +thing else--before, behind, on all sides--with a force equal to thatwith +which they are themselves compressed, or I would say, equal to +the weight by which they are so horribly squeezed and contracted: so +that, in fact, you bear this weight not only on your head and shoulders, +as you might at first suppose, but also all along your body and limbs, +under your arms, under your chin, in the hollow of your nostrils, +everywhere. + +Now we will suppose you to enter the house; and what do you find there? +Outer air, which on its part has got in by the door, the window, and +every little crevice in the wall. The column outside the roof no longer +presses upon it, but what is the gain of that? + +It was compressed when it got in, and the little springs will struggle +as a matter of course, quite as much on this side of the door as on +the other. The protecting roof has so little power that were it not +itself protected by the air outside, the pressure of which keeps it +in its place, the air within would shiver it into a thousand fragments +in its efforts to get loose. + +You laugh; but wait till I explain myself further. I will take the +case of a miniature house to make the matter pleasanter to you; one +fifteen feet long, fifteen feet wide, and with a flat roof, the most +economical plan as regards space. Fifteen feet are five yards, and as +the multiplication table tells us that five times five make twenty-five, +our roof will in this case be twenty-five square yards (_i. e._ +225 square feet) in superficial extent, or _area_; it is not much, +and you will find few as small. + +Would you like to calculate the force with which the millions and +thousand millions of little spring imps imprisoned under that poor +unfortunate roof would press against it? We settled before that the +quantity of them brought to bear upon a square inch had the power to +push at the rate of fifteen pounds. Were they to push against a square +yard (a surface 1296 times greater than the square inch) it would +therefore be 19,440 lbs. This being so for one square yard, calculate +for twenty-five square yards, and you will have the amount of pressure +against our roof--viz. 486,000 lbs--merely that! And now tell me what +cottage roof in the world was ever built so as to be able to stand +against such a weight? + +Perhaps though, you can scarcely appreciate the amount of heaviness, +486,000 lbs. Well, 486,000 lbs. is nearly 217 tons; and one of those +railway trucks that you see laden with coals at the stations can carry, +perhaps, from eight to ten tons, without breaking down. Say ten tons +as an outside estimate, and then think of piling the contents of +twenty-one such trucks on your roof, and yet you would still be short +of the weight of air which is bearing down upon it. I need scarcely +say now that were you to take away the air from within the roof, theair +without would smash both it and the whole cottage flat, as a giant +at a fair strikes an egg flat with one blow of his fist. To show you +how in another way: take a moderate sized column or pillar, such as +you see sometimes in a nobleman's grounds, of about the weight of the +twenty-one tons, and set it up like a chimney on the roof of our +cottage, then walk away to a little distance and watch what will happen! + +There, little Miss Laugher! have you at last learned to value the +weight of the air, or _atmospheric pressure_ as it is more properly +called; since it is the force with which the atmosphere presses against +rather than weighs upon everything on the surface of the globe? It is +no joke, as you perceive, and it affords plenty of subject +forreflection. I have still to prove to you that I have not been making +fun of you with my calculations, and that the weight of air upon a +square inch is really what I have said--viz., fifteen pounds. + +Now, there is a very simple way by which we might get to know your +strength, and tell its amount in figures, if one chose; namely, by +putting a weight on your arms--a heap of books, if you please--and +keep adding and adding to it, until those poor little arms were unable +to bear any more. Then weighing what they had borne, whether we should +find it to be ten or thirty pounds--I cannot guess how much it might +be at this distance--one might safely say, without fear of mistake, +"The strength of this young lady is equal to ten, twenty, or thirty +pounds"--in other words, "she represents a weight of ten, twenty, or +thirty pounds" and by a similar plan people have ascertained the +strength of the air--that is, the weight which it represents. They +have weighed what it is capable of carrying. + +I told you lately that the whole surface of the earth was covered by +an immense army of little imps--otherwise called little air-springs, +which, compressed by the giant mass of their comrades above, all of +whom they have to carry on their backs, are always trying to protect +themselves, by pushing back everything which comes across them. Imagine +the bottom of a well. Our imps are permanently installed there as a +matter of course, and face to face with the water they push against +it, each one doing his best, on all points at once. As the pressure +is equal everywhere therefore, and always the same, there are no signs +of it to be seen. + +Now insert in the water the end of a tube closed below by a cork which +exactly fits the interior, but which can be moved up and down in the +tube by means of a bar of iron or wood which runs through it. This is +called a _piston_, I may as well tell you as we go on. + +When the piston rises in the tube, it drives before it, as it goes, +the air which was already there; and which cannot slip away down the +sides because the piston fits so closely to them all the way along. +The result of this is, that just underneath the piston there is a place +in the water to which the air cannot reach, and at that place the water +has no pressure upon it at all. + +Now see what happens. Pressed upon heavily by the air in every other +part and place, like a mouse hunted by a cat, who finds at last a hole +through which to escape, the poor water darts at this and ascends the +tube close after the piston. + +So far so good; but if the tube is very long, and the piston rises +rather high;--at thirty-three or thirty-four feet above the level of +the water it has to continue its ascent alone. The water parts company, +stopping quietly behind, half-way up the tube. + +"What is the meaning of this?" you will ask. + +It means that the force which presses on the well-water all round the +tube, and thus drives it up, has done all it can, and that our little +air-imps refuse to supply any more. The water which rises in the tube +has a weight of its own of course, and with this weight it presses, +as it is fair it should, on the water below. In proportion as the +piston rises, the column of water which follows it gets bigger and +bigger, and naturally its weight increases at the same time. At last +there comes a moment when this weight becomes such that its pressure +on the water below is equal to that with which the air-imps are pressing +on the water in the well. Thenceforth they may push as they please; +no more water will go up. They are in the same position now that they +were before, when their comrades (afterwards driven out by the piston) +were pressing upon the same point, which had only a moment's freedom; +and this water column of thirty-three or thirty-four feet holds them +in check, to exactly the same extent as the gay fellows whose place +it has taken. + +Nothing is easier now than to calculate, even to a few grains almost, +the force of the pressure of air. One can get at the weight of water, +thank goodness! and it has been ascertained that our water-column will +weigh fifteen pounds if the tube is a square inch in size. You will +comprehend after this that it might be any size you may please to +imagine, without there being the slightest alteration in the height +of the column. The larger it is, the heavier will be the column of +water on the one hand; but on the other, the greater will be the number +of air-imps turned out; so it comes to the same thing in the end. + +If you should feel any doubt about the correctness of this reasoning, +you have only to try the experiment over again, in a well, filled with +mercury for instance. Ask to be shown some pure mercury, which is also +called _Quicksilver_, because one wants to express melted silver, +apt to be constantly on the move; it is often to be met with in houses. +Mercury weighs thirteen and a half times more than water: according +to our calculations, therefore, it would take thirteen and a half times +less of it than of water to bring our little air-imps to reason. And +this is just what you will find happens; you will see the column of +mercury stop short exactly at the moment when it has attained the +orthodox weight of fifteen pounds; that is to say, at a height of +twenty-eight inches. + +On the other hand, take some ether. You know that delicate spirit, +which smells so strong, which makes your hand feel cold if it is put +upon it, and which we give to sick people to inhale. Ether weighs +one-quarter less than water. In a well of ether you would therefore +see something quite different, and your column would rise without being +asked, to something like forty-three feet, exactly up to the point of +weighing--like the others--fifteen pounds to every square inch. Air +will not be replaced with less. + +That, then, is the measure of its strength, or our scales are deceitful. + + + +LETTER XIX. + +THE ACTION OF THE LUNGS. + +I hope I have told you enough, my dear child, to enable you fully to +estimate the force with which air presses upon everything on the surface +of the earth, and consequently upon our own bodies among the rest. + +If you understand this, nothing is easier than to understand how air +comes and goes in our lungs. + +When the cook wants to light her fire with two or three hot coals, +what does she do? + +She takes the bellows and blows it, does she not? + +But if she has no bellows at hand, what does she do? You answer at +once, she blows it herself with all the strength of her lungs. + +By which it would seem--does it not?--that we are a sort of living +bellows, being able, in case of necessity, to act as a substitute for +the wood and leather ones of common use. And if we really possess the +power of doing the work of a bellows, may not this be because we have +within us some little machine of the nature of a bellows? + +Exactly; and this fact gives me the opportunity of making you understand +the action of the lungs by explaining that of the bellows, which is +in everybody's hands, but which three-fourths of the people use, without +troubling themselves to inquire how it is made or acts. + +"A bellows, as you know, is composed of two pieces of board, capable +of being separated and brought together again at will, and united by +a piece of leather so shaped and arranged that it doubles up when the +boards close, the intermediate space forming a firmly-closed box, the +size of which increases or diminishes at every movement of the boards. + +"We take the bellows down to use it, and there are the boards, lying +flat upon each other, the box between them quite small. Is there +anything inside, do you think? + +"Nothing," you answer; "the bellows is empty." + +Do you think so really, my child? Do you think a tumbler is empty, +then, when you have drunk out its contents; and that jelly pots are +empty when all the jelly is eaten? There are not so many empty things +in the world, I assure you, as you suppose. You forget the air--that +monster who is always wanting to stretch himself out, and pushes against +everything he meets. He is an unceremonious gentleman, who takes +possession of every vacant place; as fast as you put a spoonful on +your plate, he takes up the room of the jelly which has been removed, +and at each mouthful you swallow, he slips into the place of the water +which goes away. When you think the glass and pot are empty, they are, +in reality, full of air. You cannot see it; but it is there, you may +rely upon it. + +There is air, then, in the bellows-box, because there is air in every +place where there is nothing else to dispute possession with it. The +quantity is small in this case, no doubt, because the box is small and +cannot hold much. + +But now, look! I separate the boards, and the box, which was small, +becomes large. For once, then, here is a box which must be partially +empty; for it has just, as if by magic, made a space in itself in which +positively there cannot be anything, since there was nothing there +beforehand. + +Ay! but look down at the centre of the upper board. You see a little +hole there, do you not, and below the little hole a small piece of +leather, which seems to close it up? That is a _valve_, one of those +doors, such as we noticed before in the heart, and such as are to be +found, moreover, in most houses, which let people through on one side +but not on the other. This one opens when it is pushed from without, but +lets nothing out which has once got in. Now, the air outside, as I said +before, is always pushing against everything. He pushes as a matter of +course, therefore, against the valve, and as there is nothing behind it +to resist the pressure, in proportion as room is made inside the box, he +enters and fills it with himself. + +But presently some one begins to close the bellows, and he finds himself +caught between the boards; on which these invite him to begone, with +the same sort of politeness displayed by the police, when the hour of +departure comes in a place of public exhibition; when, _i.e._, +they spread out on all sides, and force the crowd before them till +they have found the road to the door. But the air cannot get back by +the way it came in, the door being shut. As, however, it must go out +somewhere, whether it likes it or not, it passes through the tube at +the end of the box (the _nozzle_ of the bellows), and comes out +thence with a rush upon the fire. When it is once gone the bellows can +be distended again, and the process be repeated as before indefinitely. + +And this is just what goes on inside ourselves. Your chest, my child, +is a box which expands and contracts alternately; making a place for +the air by the first effort, and then driving it out by the second. +It is neither more nor less than a bellows, but of a simpler +construction than that used by the cook. The exit pipe serves also for +a door of entrance, and there is but one board instead of two. + +The _exit pipe_ is the _larynx_, of which we spoke before, +when we were talking of swallowing the wrong way, and which communicates +with the air outside, through the nose and mouth at the same time, +allowing us to breathe through either one or the other as we like. + +As to the _board_, I said a few words about it when I was describing the +liver. It is the _diaphragm_--that separating partition--that floor +which is placed between the two stories or divisions of the body--the +belly and the chest. + +But here especially the infinite superiority of the works of God over +the miserable inventions of man comes out in all its grandeur. + +A bellows which was to have the honor of keeping up within us that +miraculous fire--the pre-eminently sacred fire--which we call Life, +required something more than a common board for its foundation. And +accordingly this, of which I am now going to give you a detailed +history, is as marvellous as it is admirable. I fancy that when you +have read my account, you will no longer turn up your nose at the vile +word _diaphragm_. + +Let us first take a peep at the construction of the bellows. + +On each side of the _vertebral column_, from the neck to the loins, +spring twelve long bones, one below the other, bent in the form of bows; +these are called the _ribs_. The first seven pairs of ribs rest, and as +it were, unite, in front, upon a bone called the _sternum_, which you +can trace with your finger down to the pit of the stomach, at which +point the finger sinks in, for there is no more _sternum_, and the last +five ribs on each side no longer unite with those of the opposite one. +For which reason they are called _false ribs_. On the other hand they +are joined to each other at the ends by means of a strip or band of a +substance sufficiently strong, but at the same time flexible, and +somewhat elastic, which is called _cartilage_ or _gristle_. The next +time you see a roasting piece of veal on the table, look well at it, and +you will see at the end a white substance which crackles under your +teeth; that is _gristle_. + +This forms the framework of our bellows, which you may picture to +yourself as a kind of cage, widening towards the bottom and going to +a point at the top, for the arches formed by the upper ribs are smaller +than the others. The whole terminates in a sort of ring, through which +pass, together, the _oesophagus_ and the _trachea_. + +The space between the ribs is occupied by muscles which reach from one +to the other, and the whole framework or cage is shut in below by the +_diaphragm_, that marvellous board whose history I have promised to +relate. + +The _diaphragm_, as I told you some time ago, is a large muscle, thin +and flat, stretched like a cloth between the chest and the _abdomen_. It +is fastened by an infinity of little threads called _fibres_, to the +lower edge of the cage I have just been describing, and it looks at +first sight as if it must be incapable of moving, since it is fixed in +one invariable manner all round the body. + +It moves nevertheless, but not in the same way as the boards of our +bellows. + +Ask your brother to hold two corners of your pocket-handkerchief; take +hold of the other two yourself, and turn the handkerchief so as to +face the wind. The four corners remain in their place, do they not? +but the middle, inflated by the wind, curves and swells out in front +like a ship's sail, which itself is only an immense hand kerchief after +all. Then draw the handkerchief tightly towards you, each to your own +side, and it will recover itself and become flat again. Loosen it a +little and it will curve and swell out again in the middle, and this +maneuver you can go through as often as you choose. + +Which very maneuver the _diaphragm_ is continually performing, of and by +itself. + +In its natural position it bulges upwards in the middle, like a cloth +swollen out by the wind, and thus occupies a portion of the chest at +the expense of the lungs. When air has to be admitted, its _fibres_ +tighten and bring it flat again, as you and your brother brought the +handkerchief flat just now by tightening it. + +The whole space previously occupied by the arch of the _diaphragm_ +is thus given up to the lungs, which, being elastic, instantly stretch +themselves out to it; while air, running in through the nose and mouth, +fills up in proportion the empty place (_vacuum_) created by the +extension of the lungs, exactly as in the case of the bellows. + +But soon the fibres of the _diaphragm_ relax. It rises up again into its +old position, driving back the lungs as it does so; and the air finding +there is now no room for it, goes out by the same way the other came in. +I say _the other_, observe, because the air that goes out is no longer +the same as when it came in; and this is the secret of _why we breathe_; +while the up and down movement of the _diaphragm_ is the explanation of +_how we breathe_. + +As you perceive, then, the mechanism of these bellows of ours, is of +the most simple, and consequently of the most ingenious character, and +leaves far behind it anything we have ever imagined. + +Are you disappointed? Do you feel inclined to exclaim, "Is this all?" +to ask where are the wonders I promised you? to protest that I may +talk as I please about the inflating and flattening of a +pocket-handkerchief? _you_ can see nothing so marvellous in the +matter; nothing worth making your mouth water for. + +A little patience, Mademoiselle! Hitherto we have talked only of the +machine; but there is a goblin inside it, and our fairy tale is going +to begin again. + +There are in some families certain old servants who belong to the +house, more, it may be said, than their masters, in some ways. They +educate the children, and they serve them till death; they live for +them alone, and know so well what they have to do, both by day and +night, that there is no need to give them any orders. Nay, not only +is it unnecessary to give them directions--it is for the most part +labor in vain. They are so completely at home in their business, that +they will go nobody's way but their own. If you wish them to alter +their habits they may obey you for an instant, but it is only to return +into the old groove directly after; for they know better than you do +what you want. + +I was very little when I first read in the story-books of my day, some +bitter complaints of the disappearance of this race of old-fashioned +servants of the good old times. And you very likely may have seen it +said that they are no longer to be met with. Yet there will always be +some, depend upon it, in families, who know how to make and to keep +them. Good old times or not, they have never been found in any other +but these cases. + +Still, _I_ have just such a one as I have described--even I who +am talking to you--and so has your mamma; and what is more, you have +one yourself; and what is more still, everybody else has one. This +servant of the good old times, who will never disappear (and this is +more than one can promise of any other) is the _Diaphragm!_ When +you came into the world, my dear child, and were merely a poor little +lump of flesh, without strength, intelligence, or will; incapable of +giving any orders whatever to those organs of yours, of whose existence +you were not even aware, your _diaphragm_ quietly began his duties, +without leave or inquiry from you, and with your first _breath_ your +life began. Since which he has always gone on, whether you attended +to him or not, and his last effort will be your last sigh. + +When you go to sleep, careless of all that is to happen, until you +awake again, that servant of yours, indefatigable at his post, labors +for you still, and the light breath which half opens your rosy little +lips as it passes through them; that light breath which your happy +mother watches with such pleasure, is his work. Midnight strikes--one +o'clock--two; all around you are buried in sleep--but he is awake +still. Were it otherwise--were he to go to sleep when you do, you +would never awake again! + +This protector of each instant, this faithful guardian of your life, +is, nevertheless, subject to you as a servant to his master. Attend +to him, and he will obey your orders. You can make him go at a great +pace, or slowly, as you choose; or stop him altogether, if the fancy +takes you to do so: but this not for long. The servant of the good old +times is obstinate in the performance of his duties. He will yield to +you in trifles; but do not try to force him over serious matters. I +have read somewhere of a desperate young fellow, chained down in a +dungeon, who killed himself by holding his breath; but I never quite +believed it. Mr. Diaphragm would not allow any one to carry rebellion +so far as that. + +But we have not finished yet, and you do not yet know how appropriate +is the comparison I am making. + +Should any misfortune, any grief, any trifling annoyance even, befall +his master, a good servant suffers with him, and as much as he does; +sometimes even more. Occasionally the master is comforted, while he +remains still disturbed. + +"And the diaphragm?" you ask. + +The diaphragm does precisely the same, my dear child. Yours, especially, +shares in all your griefs to such an extent that, truth to say, he is +not always quite reasonable. The other day when your mamma did not +want to take you into the country with her, he was so sorry for you +that he went into perfect convulsions, and you sobbed and sobbed till +she was obliged to say, "Come, then, you naughty child;" whereupon you +embraced your mamma, and were quite happy again, while he remained +still unappeased, and your poor little chest was shaken more than once +afterwards by his last convulsions. + +Sobbing, you must know, is merely a convulsion--a great shake of the +diaphragm--which is the reason of its causing such a heaving of the +chest. + +It is the same with respect to joy. The joy of the master makes the +servant dance, and so the diaphragm too! Its little internal jumps +are, then, what we call laughter--a thing you are well acquainted with. +Put your hand on your chest next time you laugh (and I hope it will +be soon) and you will feel how it dances--thanks to the diaphragm which +jumps for joy whenever it finds you in good humor. + +Please to observe further, that nothing of all this is done to order. +He starts of himself, poor fellow, without waiting to ask if you will +ever know anything about it; and, in truth, you have known nothing +about it up to the present moment. + +What say you to the diaphragm now, my child? Does not the very name +please you? You scarcely expected to find there--under your lungs--so +good a servant, one so attached to your person, so strongly resembling +in all points the best specimens we know among men. And still we have +not done. I have reserved as a finale for you a new point of resemblance +which will make you open your eyes very wide indeed. + +The old servant is sometimes cross and grumbling. If anything is going +against his grain in the house he has no scruple in saying so; and his +mode of speaking is sometimes rather rude. Nor is it of any use to get +impatient and impose silence on him; he will listen to nothing--it is +his privilege. But let some unforeseen accident happen to his master, +let him see him deeply affected, and in a moment all his anger is over. +He sets himself silently to work again, recalled to order twenty times +sooner by his master's emotion than by his utmost impatience. + +You ask what I am coming to now? My dear child, what I have just told +you is the history of the _hiccup_--the history of the hiccup, neither +more nor less. + +I must first tell you, however, that the _diaphragm_ keeps up +intimate relations with his neighbor below--the stomach. Every time +he rises in the breast the stomach rises behind him; and not only the +stomach, but also its companions, the intestines. All the officials +employed in the business of digestion travel regularly with him; coming +down as well as going up in company. Put your hand upon your abdomen +and breathe strongly and you will feel the rebound of all the movements +of the diaphragm. + +Now, when matters are going on wrongly inside, when too much work has +been imposed on the officials, or work they dislike, or else when they +have been disturbed in their labors, it will sometimes happen that the +_diaphragm_ takes part with his comrades in the abdomen. He gets +angry then, and shakes his master, who cannot help himself a bit. You +must be very well acquainted with these attacks, which are very +fatiguing when they last long. One begs pardon and resists him in vain; +he does as he pleases, without stopping to listen, turning everything +upside down; and do you know the only efficacious plan for calming him +at once? It was a constant source of wonder to me when I was little. +A sudden fright, a start unexpectedly caused by a friendly hand slipping +secretly behind, and laying hold of one, was all-sufficient; disarmed +by the agitation you have undergone, the naughty, stubborn muscle +forgives you, and you are cured. + +Having dwelt so long on the truly wonderful resemblance between the +proceedings of two sorts of beings, whom no one that I know of ever +thought of comparing together before, I will now, my dear child, give +you the key to all these comparisons, which seem so whimsical at first, +but are so striking in reality, and which come to my pen of their own +accord, as it were, in the midst of the explanations I have undertaken +to give you. Many people who would not themselves care for them, will +declare that they are too hard for a little girl to follow. But for +my own part, I find that the eye can take in a mountain as easily as +a fly, and that it is not more difficult to lay hold of great ideas +than of little ones. It is short-sighted people, not children, who +cannot see far before them. Who made the heavens and the earth? God, +your catechism tells you. The same God made both; did he not? We do +not acknowledge two. And if it be the self-same God who made everything, +the hand of the universal Maker will be found everywhere; and from the +highest to the lowest portion of His work the same mind will manifest +itself under a thousand different forms. Not only, either, is each man +separately, one by one, the work of God. The whole human race, taken +in the mass, is also His creation; and the laws by which human +society--that great body of the human race--seeks to regulate itself +for the preservation of its existence, are undoubtedly the same as +those which overruled the organization of our individual bodies. It +is not very astonishing, then, if we find, in the life of human society +around us, details corresponding with each detail of the life of the +human body, or, at any rate, closely resembling them. What would really +be astonishing, would be that mankind as a whole should be differently +constituted from man as an individual, and that human society should +have other appointed conditions of well-being than those of each of +its members. + +So, while I am on the subject, I should like to advise those who wishto +apply themselves to what is called _politics_--that is to say, social +life--to begin their studies of the body social, by studying the body +human, first. They will learn more from it than from the newspapers! + +But you have nothing to do with all this. For the present, take notice +of one thing only; viz., that the hand of the same God has passed over +everything, and that there is neither much presumption nor much merit +in tracing points of comparison between the different parts of His +work. These comparisons are not a mere play of the mind; they really +exist ready made in the very foundations of things. + +Now let us come down a little from these heights and return to our +friends the lungs. I have not spoken about them for some time, and I +have not yet told you how they are constructed. + +I wish I could show you some, but the cook will do so, if you would +like to see them. The _lights_ with which she feeds the cat and +the dog are the lungs of some animal. + +Take up a piece in your hand, and you will find you have got hold of +something _light_ (cooks have not given it its name without a reason), +which is also soft, sinks under your finger if you press it, and rises +again afterwards like a sponge. In fact, the lung, like the sponge, is +composed of an infinity of minute cells, whose elastic sides can be +contracted or expanded at will. They are like so many little chambers, +into every one of which blood and air keep running hastily, each on its +own side, to bid good day to each other, touch hands, and then hurry out +as briskly as they came in. Whether the bit of lights the cat is eating, +comes from an ox, a pig, or a sheep, you may look at it with perfect +confidence; your own lung is precisely like it. You would see nothing +different, could you look into your own chest. + +So much for the _substance_ of the lungs. As to SHAPE, imagine +two large, elongated packets, flat inside, descending right and left, +inside the breast, and bearing the heart, suspended between the two, +in the middle. The extremity of each packet descends below the heart, +and it is in the interval which separates them that the arch of the +diaphragm performs its up and down movement. + +I have already said that air reaches the lungs through the _larynx_. The +_larynx_ (of which we shall speak further when I have explained another +curious thing very valuable to little girls--the voice), the _larynx_ is +a tube composed of five pieces of _cartilage_ (you know now what +_cartilage_ or _gristle_ is), the firm resisting texture of which keeps +it always open. After these five pieces of _cartilage_, come others, and +the tube is continued; but it then takes the name of the _trachea_; the +_larynx_ and _trachea_ constituting the _windpipe_. At its entrance into +the chest, the _trachea_ divides into two branches, which are called +_bronchial tubes_, and which run, one into the right lung, the other +into the left. You sometimes hear people talking about _bronchitis_. It +is an inflammation of these _bronchial tubes_, which are within an inch +or two of the lungs. It is necessary, therefore, to be very careful in +such circumstances, and do exactly what the doctor prescribes, +because--one step further, and the inflammation extends from the +bronchial tubes into the lungs themselves, with which it is not safe to +play tricks. + +Having reached the lungs, the _bronchial tubes_ subdivide into +branches, which ramify again in their turn like the boughs of a tree, +and the whole ramification terminates in imperceptible little tubes, +each of which comes out in one of those little chambers I was talking +about just now. And this is the way in which air gets there at all. + +The venous blood which leaves the heart, arrives on its side by one +large canal, which passes out from the right ventricle, and which is +called the _pulmonary artery_. And, to tell you the truth, while there +is no learned man present to be angry with us, it is a very ill-chosen +name, because it is _venous_ blood which flows in this so-called +_artery_. But the doctors have decided that all the vessels which run +from the heart should be called _arteries_, and all those which go back +to it _veins_, whatever may be the nature of the blood which they +contain. We cannot help it, because they manage all these matters in +their own way; but in that case it was scarcely worth their while to +talk about _arterial_ and _venous_ blood. It would have been better to +have said simply, red blood and black blood. + +Be this as it may, _venous blood_ arrives from the right _ventricle_ +through the _pulmonary artery_. This divides itself, like the _bronchial +tubes_, into thousands of little pipes, whose extremities come creeping +along the partitions of the little chambers in question. + +And here, then, takes place, between the air and the blood, that +mysterious intercourse for the account of which I have kept you waiting +so long; and at the end of which the black blood becomes red, or, in +other words, from venous becomes arterial. I have called it +"intercourse," and this is really the proper phrase; for this +transformation of the blood is accomplished by means of an exchange. +The air gives something to the blood, and the blood gives something +to the air--each giving, in exchange, like two people over a bargain +in the marketplace. + +With your permission, my dear child, we will stop here to-day. We have +now got to the charcoal market, and it is a little black. + + + +LETTER XX. + +CARBON AND OXYGEN. + +Here, then, my dear child, we have arrived at the explanation of that +great mystery, WHY _we breathe._ Keep on the alert, for we are now +entering into a region where everything will be new to you. + +Here we are at the charcoal market, I said to you just now, and no +doubt you concluded that I was beginning another comparison. + +But no such thing; there is no question of comparison or simile here; +I state the fact itself, pure and simple as it stands: it is a +_market,_ for commercial intercourse and exchange are carried on +there, as I told you before, and it is a _charcoal_ market, +because _charcoal_ is, positively, the essential and chief article of +commerce. + +You are astonished, I dare say, and are ready to ask me whether I can +possibly mean real charcoal, charcoal such as the cook puts into the +furnace. Surely, say you, we have nothing like _that_ in our bodies? +Surely we don't eat _that_? + +But I answer yes; real, true charcoal, and you do not dislike it; you +eat of it even daily; nay, you do not swallow a single mouthful of +food which does not contain its proportion of charcoal. + +You laugh; but wait a little and listen. + +When you are toasting a slice of bread for breakfast, and hold it too +near the fire, what happens to it? + +It turns quite black, does it not? + +When mutton-chops are left too long unturned on the gridiron, what +happens to them? + +They turn quite black also. + +When your brother forgets the apples which he has set to roast, what +happens to them? + +They turn quite black, as you have seen more than once. + +It is always black, then, that these things turn, is it not? and a +fine rich _charcoaly_ black, as you may see if you please to +observe charcoal closely, for just such is the color of little burnt +cakes, over-roasted chestnuts, and potatoes in their skins, which have +been dropped into the fire. + +But there is a common term by which we can express more accurately the +misfortune which has befallen all these various things--slices of +bread, mutton-chops, apples, cakes, chestnuts, potatoes, and what-not, +when "burnt," "over-toasted," "over-roasted," or "over-baked." We may +call them _carbonized_, or more simply _charred_ or _charcoaled_; though +the word _charred_ is generally used only for burnt _wood_. But _carbon_ +being the principal ingredient of _charcoal_, and _charcoal_ being one +of the purer forms in which we get at _carbon_, they are almost +synonymous terms, and you may call your burnt food _carbonized_, or +_charred_, or _charcoaled_, whichever you prefer. + +The next question is, how did charcoal or carbon get into the food so +as to justify our talking of its being _carbonized_ or _charred_? Even +when we use charcoal stoves for cooking, the charcoal does not jump out +and get into the mutton-chops, etc., you may be sure. Then it is clear +it must have been in them before they were brought to the fire to be +cooked; and such is indeed the case, only its black face escaped notice +because it was in such gay-looking company, and kept itself hid behind +the others like a needle lost in a match-box. Set fire to the matches, +and you will soon have nothing left but the needle, which will then +strike your eye at once. And so with our burnt food; the fire has +carried off all the other ingredients, and the charcoal is left behind +alone, exposed to everybody's view, as if on purpose to teach them that +it was always there; in the apples, i.e., the potatoes, mutton-chops, +etc., which seemed so tempting when the black rogue was hid, but from +which now, when he is there by himself, they turn away in disgust. + +Charcoal is, in fact, a much more generally distributed substance than +you have been used to suppose, dear child. That which comes from burnt +wood is most easily observed, because there is a much larger proportion +of charcoal in wood than anywhere else; but there is not a morsel, +however small, of any animal or vegetable whatsoever, which does not +contain charcoal. In the sugar which you crunch, in the wine which you +drink, there is charcoal. I could even find some in the water you wash +in if I were to try hard. There is charcoal in the goose-quill which +I hold in my hand at this moment, and in the paper on which I am +writing, and in the handkerchief on my knee. If I hold them all three +in the light of my wax taper, I shall soon see them turn black and +betray the presence of our friend. It exists in the wax taper itself, +as also in the candle, as also in the oil lamp. If I were to hold a +piece of flat glass above their flame, I should collect enough of it +to blacken the tip of anybody's nose who presumed to doubt the fact. +There is a portion of it in the air; a portion of it in the earth. +Where is it not? In short, all the stones of all the buildings in the +world are filled with it from top to bottom. _Charcoal,_ under his more +scientific and important name of _carbon,_ may be called one of the +great lords of the world. His domain is so extensive that one might go +round the world without getting out of it; he is even worse than the +Marquis of Carabas. + +After this you will never, I hope, want to persuade me you do not +eatcharcoal; for, indeed, you would be puzzled to escape doing so. Of +all the things you see on the dinner-table there is but one in which you +will not find it--viz., the salt-cellar; and even while saying this, +I mean only, in the _salt_ itself, for as to the salt-cellar, +clear and transparent as its glass may be, there is charcoal in it! + +Our bodies, therefore, are full of charcoal. Everything that we eat +supplies them with enormous quantities of it, which take up their +quarters in every corner of our organs. It is one of the principal +materials of the vast collection of structures of which I spoke to you +in the early part of these letters, and of which the blood, the steward +of the body, is the universal master-builder. If you remember, I told +you then that these structures fell to pieces of themselves, in +proportion as the workmen went on building, and that the blood, which +brings fresh materials on its arrival from the lungs and heart, carries +away the refuse ones on its return. And, of all these refuse materials, +old charcoal is one of those which takes up the most room, as fresh +charcoal took up a great deal of room in the new materials. The blood, +as he goes back again, has his pockets quite crammed with it, and if +he did not try hard to get rid of it as fast as possible, he would be +disabled from being of any further use. + +Now it is in the lungs that he clears himself of it. He gives it up +to the air, which has need of it for a very interesting operation, of +which I shall tell you more by and bye; and in return the air gives +him something which is quite indispensable to him, for without it he +would not dare to return to the organs, as his authority would no +longer be recognised. + +In the same way, the charcoal-seller goes to market with his charcoal +and receives silver in exchange. + +If he were to go home without money his wife would receive him with +abuse. + +But what is the indispensable thing which the blood obtains in his +marketing? + +Remember its name well: it is OXYGEN. + +And we must speak of it with respect, for we are talking here of a +very great and powerful personage, very superior even to CARBON. If +CARBON be one of the great lords of the world, OXYGEN is its king. + +There is a certain substance, my dear child, of which many people, +especially little girls, do not even know the name, but which yet +constitutes of itself alone a good half of everything we are acquainted +with in the world. And this substance is the very thing I have just +named to you. It is OXYGEN. + +Ascend into the air as high as you can go, viz., to forty miles or so +from the ground, as we said before; _oxygen_ forms the fifth part +of that vast aerial ocean which surrounds the globe on every side. +There it is free--is _itself_--if I may use the expression; it +is in the condition of _gas_; that is to say, it eludes our sight, +though there is no difficulty in ascertaining its presence, when one +knows how to set about it. + +Go down into the depths of the sea. People think they have good reasons +for believing this to be two and a half miles deep on an average, which +would give a pretty little sum total of tons for its whole weight, as +you will be convinced, if you take the trouble of observing the space +it covers on a map of the world;--to say nothing of lakes, rivers, +streams, the water in the clouds, the water scattered throughout the +interior or on the surface of continents, including that with which +you wash your face every morning. + +Oxygen enters in the proportion of eight-ninths into the composition +of this incalculable mass. _Eight-ninths_, you understand, which +is very near being the whole nine; in every nine pounds of water there +are eight pounds of oxygen, the remainder being left for another +substance, of which we shall have occasion to speak presently, and +which is called _hydrogen_. + +The earth on which you tread is full of oxygen. So far as we have +penetrated hitherto into the interior of the globe, we have found king +Oxygen everywhere: hidden under a thousand forms, connected with a +heap of substances, not one of which could exist without him; imprisoned +in a thousand combinations, and always ready to resume his natural +condition if his prison-house be destroyed. The whole surface of the +earth, plains, hills, mountains, towns, deserts, cultivated fields, +everything you would look down upon, if on a clear day you could be +carried high enough in a balloon to take in the whole earth at a +glance:--all that may be considered as an immense reservoir of oxygen, +out of which we should see it escaping in gigantic waves, if some +superhuman chemist were to take it into his head to put our poor little +globe into a retort of the same kind as chemists use among us. To give +you an example; the stones of our fine buildings, in which we have +already discovered the presence of _carbon_, are almost half made +up of _oxygen_. In a stone which weighs 100 lbs. there are 48 +lbs. of oxygen, and the first chemist who passes by could make them +come out of it if he chose, if he were to use a little trouble and +skill. + +I enumerated to you last time many of the substances in which _carbon_ +is to be found; but as regards _oxygen_ we must give up all attempt at +making a list; it would comprehend the whole dictionary. Touch whatever +lies under your hand--in your room--in the house--wherever you may go--I +will almost defy you to put your finger upon anything--metals +excepted--which is not crammed with oxygen. Your very body, to conclude +with, would become so small a thing, were the oxygen it contains +extracted from it, that you would be perfectly amazed. + +So when I told you oxygen was king of the world, I did not say too +much, did I? Between ourselves too, it is a great misfortune that +people live on so complacently in total ignorance of this all-important +material, which is connected with everything, which insinuates itself +everywhere, which we make use of every instant of our lives, which may +almost be said to be in some sort our very selves, since it constitutes +three-fourths of our body, but whose name nevertheless would, I am +certain, make many pretty little mouths pout, if one were to utter it +in a drawing-room. + +This is really the case. Many young ladies who are proud to know who +Caractacus was, would be ashamed to know anything about oxygen. There +is a foolish notion that women have no business with such subjects, +probably because children are supposed not to breathe and mothers are +not required to watch over them? + +This reminds me that we are on the road to explain _respiration,_ +which I had almost forgotten in lifting up this corner of the veil +behind which Nature hides her most valuable secrets from the idle and +ignorant. + +It is _oxygen_ then, which the blood carries off triumphantly from his +interview with the air in the cells of the lungs; and, by the way, it +is, thanks to this oxygen that it returns from the lungs to the heart, +and so from the heart to the organs, with that beautiful rosy tint which +distinguishes _arterial_ from _venous_ blood. + +Now the blood gives out this oxygen on its road every time it performs +the journey, and the perpetual course it performs from the lungs to +the organs, and from the organs to the lungs, has for its chief object +the perpetual renovation of this previous provision, which is as +perpetually consumed. + +Do you ask of what use it is? Does the blood leave it at random in our +organs, and is it one of the materials with which our steward is +constantly providing the little workmen of the body for their various +constructions? + +No, my dear child. The proverb _"One cannot live upon air,"_ is +a very true one, although it is equally true that we cannot live without +air. Air does not nourish our organs; on the contrary, it consumes +them, and what we eat, serves to supply in precisely the same proportion +its insatiable appetite. When we leave off eating, from whatever cause, +the air does not leave off too. He goes on always just the same, and +that is the reason why people who are starved to death are so thin. +(The air has consumed the vital parts.) + +You did not expect this; but now prepare yourself to go on from one +surprise to another. To begin with, I shall have to stop here and +explain to you before we go any further--can you guess what? Nay, I +am sure you cannot; FIRE. + +There is not much connection, you will say, between _fire_ and +_breathing_. + +But there you are mistaken. It is precisely the same thing, as I will +prove to you next time. + + + +LETTER XXI. + +COMBUSTION. + +Have you never, my dear child, whilst warming your little feet on the +hearth in winter-time, asked yourself, _What is fire?_ that great +benefactor of man; fire, without which part of the world would be +uninhabitable by us during at least a third of the year; fire, without +which we could not bake a morsel of bread, and would have to eat our +meat raw; fire, which lights up the night for us, and without which +we should have to go to bed when the hens go to roost; fire, which +subdues metals, and without which we should have neither iron, nor +copper, nor silver, nor anything that is manufactured from those +materials; fire, without which, in short, human industry could not +rise to much higher results than that of the monkey and of the beaver? + +We are all of us, it is true, so much accustomed to fire that we do +not pay much attention to it, and have a sort of persuasion that lucifer +matches have existed from all eternity. But the first men, who were +nearer neighbors to that great discovery whence all others have +originated--the first men treated fire with more respect than we do. +It was to them one of the mighty things of the world. The ancient +Persians made a god of it, and told how Zoroaster, their prophet, went +to seek it in heaven, passing thither from the top of the Himalayas, +the highest chain of mountains in the known world. + +The old Greeks pretended that Prometheus stole it from the gods, to +make a present of it to man, which came to nearly the same thing as +the Persian account. The Romans had their _sacred fire_, which +the celebrated Vestals were bound to keep lighted, on pain of death +to whoever should let it go out. At the present day we do not stand +upon such ceremonies, but warm our feet at it quite familiarly, without +wishing for anything further. But you would see a terrible revolution +in the world if some Prometheus reversed were, some fine morning, to +steal it from us, and carry it back to its ancient owners. Every branch +of human industry would suddenly stop, as if by enchantment, and in +the course of a very few years the poor little framework of human +society, of which we are now so proud, would totally change its aspect, +and the whole world would be turned topsy-turvy. + +But do not be alarmed; there is no danger of the sort. Fire is not a +present once made to man, but liable to be taken away from him at will. +It is a law of nature which existed before the human race came into +being, and which will doubtless continue to exist when the human race +shall have disappeared. The existence of fire is connected in the most +intimate way with that of that great king of the world of whom we spoke +last time--Oxygen. Fire is the wedding-feast of Oxygen with other +substances! + +When kings are married, what rejoicings there are! what a commotion! +what illuminations! It is only right and proper, then, that the king +of the world should have rejoicings and illuminations at his weddings +also. And they have never been wanting. The rejoicings are the warmth +which rejoices us; the illuminations, the flame which gives us light. +But man, in his dealings with nature, is an imperious subject, such +as few earthly kings are troubled with--happily for them! Whenever he +wants warmth and light he forces the king of the world to get married, +and then takes advantage of the feast; nothing worse than that. + +"How so?" you exclaim. "If I want to make a fire with stones or iron, +I should never succeed. Is this because oxygen never unites himself +with those substances, nor with heaps of others which are equally +useless in lighting a fire? Yet you told me that oxygen was to be met +with almost everywhere." + +It is a fair question, my dear child; but my answer is, that what you +said last is precisely the reason why all substances are not fit for +making fire of. When oxygen is already there, as he is in stones, for +instance, the marriage is over--the feast cannot begin again. Kings +are like other people in this respect; their weddings are only +celebrated once. If you had happened to be present at the moment when +oxygen was united to the materials of which stones are composed, you +would have seen a feast of which I should like to have heard some news. +I was not there myself either; but learned men in these latter days +have succeeded in breaking the bonds which united oxygen with the +primitive substances in certain fragments of stone, and with these +substances thus freed, and consequently able to remarry, they have +been enabled to give us, in miniature, the spectacle of the festivities +of a fresh wedding. And I can assure you it is enough to make one +shudder, to think of the time when such a marriage must have taken +place on a large scale. + +With regard to _iron_ the case is quite different. + +You have without doubt heard tell of Louis XIV. (of France), that proud +king who was called _le Grand_, and who is said to have heard +himself compared to the sun, without smiling. It seems that he one day +took it into his head to marry, it is difficult to say why, with Madame +de Maintenon, the old wife of a poor paralytic poet named Scarron, +who, as such, however, was only known by some few farces. Do you suppose +that the palace of Versailles was illuminated in honor of this marriage? +Not a bit of it. It was a disgraceful marriage, which they were bound +to keep secret. The ceremony was conducted mysteriously and without +lighting a single candle more than ordinary. + +I do not pretend to say that oxygen has any of these weaknesses, nor +that he is any more partial to marrying with one body more than with +another. In the good God's great world, outside of the family of man, +they know nothing of our foolish pride, of our little weaknesses. It +is nevertheless a fact that this dear monarch has his preferences, and +that all his marriages are not made in this fashion. + +Leave those pretty little scissors of yours, with which you would try +in vain to make a fire, outside your window for two or three days, and +then observe the dreadful, scaly, red stain which you are sure to find +on them afterwards, and which is called _rust._ Have you any idea +whence it proceeds? I will tell you. It comes from the oxygen, which +has been making one of those cheerless secret marriages with the iron +of your scissors. So there have been no pretty sights nor sounds, no +lights nor cheerful noises to entertain anybody, and though people may +have wished for them ever so much, they have had to do without them. + +I will tell you the true reason of these marriages _incognito._ +It is because oxygen is but feebly attracted by iron, who does not +stand so high in his good graces as many other bodies, and so (to +continue the joke) he unites slowly and languidly with him, as we may +say. + +Now tell me, when you set fire to a bit of paper, how long does it +take to burn? + +Half a minute, at the utmost, you answer. + +Very good. And how long does it take to produce that rust-stain, even +though it is probably not a hundredth part the size of the paper? + +Two or three days, is your reply, for so I told you my self. + +Here is a strange difference indeed; but from it you may discover why +you have not seen any signs of rejoicing or illuminations at the iron +wedding. These are always in proportion to the quantity of oxygen which +is being married at once--and this was--oh, such a slow affair! When +the quantity is very small indeed, the festal illuminations are very +small indeed too, and in fact escape observation altogether. In the +same way that you would not be conscious of little bits of thread laid +delicately one after another on your back, whereas you would plainly +feel a large sheet, were it to fall on your shoulders. Yet what is the +large sheet but a great quantity of little bits of thread? Only in +that case they would all come upon you at once, like the marriage +illuminations of burning paper. + +Wait a little longer and we shall finish. + +What is there, then, in the paper which pleases the oxygen so much +that he unites himself to it so readily, and in such large quantities? + +What is there? Two substances of high degree, who have actually risen +to the dignity of a royal alliance, by the important part they play +in the world; one of these, charcoal or _carbon_, we know quite +well already; the other I have only mentioned to you in connection +with water, HYDROGEN. Thanks to gas companies, everybody in these days +knows _hydrogen,_ at least by name. But before proceeding, I will +just tell you that it is by far the lightest body that is known. It +is forty and a half times lighter than air, which is not very heavy +itself, although in the mass it has its weight, as we have seen. + +The true province of hydrogen is water, where it keeps house with +oxygen, in proportion of one to eight pounds, as you may remember I +stated in my last letter. But beside this, _hydrogen_ and _carbon_ are +in a manner inseparable friends, whom one invariably meets side by side +in all animal and vegetable substances. In wood, coal, oil, tallow, and +spirits of wine; in everything in short that we call _combustibles,_ +because the name of _combustion_ has been given to this marriage of +oxygen with other bodies, hydrogen and carbon keep themselves shut up +very discreetly and very quietly; like two children playing at +hide-and-seek. You have sometimes played at hide-and-seek yourself, no +doubt? Now, if some naughty child had come behind you with a lighted +candle, what would you have done? You would have had to turn out, whether +you liked it or not, and be caught. Well! this is what happens to our two +friends, when you bring the paper to the fire. The heat forces them out, +and the oxygen, which is always at hand, seizes upon them. In a +twinkling they are married, and a beautiful flame springs up into the +air, which lasts till everything has disappeared. + +Hydrogen and carbon! These, then, are the two great combustibles, the +two parents of fire; and as nature has lavished them upon us in what +we may call inexhaustible quantities; when you hear people lamenting +and saying that wood is disappearing, that coal is diminishing, and +that the human race will end by not knowing how to warm themselves, +do not disturb yourself in the least. + +There is more hydrogen in a bucket of water than is wanted to cook a +large dinner. There is as much and more carbon in our stone quarries +than in our coal pits, and when all the woods in the world are cut +down (which I trust will never be!) do you know what we shall do? Why, +we shall take to burning the mountains. The Jura mountains in +Switzerland, for instance, (to take the most favorable case) are great +masses of carbon, without its ever being visible. Everything depends +upon knowing how to make it come out of its hiding place; but that +will de done when it is wanted: more difficult matters have been +accomplished already. As to oxygen, whether carbon comes to him from +a log of wood or from a building stone; whether the hydrogen comes +from a candle or a glass of water, is a matter of perfect indifference +to him. He only considers persons, not their origin, and marries as +willingly in one case as in the other. + +So we have returned to the subject of _respiration_, on which I +always seem to be turning my back; but now the question is, what brings +us to it again? And this is the explanation. + +When the oxygen picked up in the lungs by the blood has traveled with +it to the organs, he finds there two well-known friends--hydrogen and +carbon. + +You smile, and exclaim at once, "Then he marries them, does he?" + +Yes, my dear child; and it is only for that purpose he enters our +bodies at all. And this is why I could not make you understand the +nature of respiration until I had explained that of fire to you. As +I have told you before, it is the same thing. Invite air into your +body by the bellows of your chest, or drive it into the fire by the +kitchen bellows--it is always king Oxygen whom you are sending to his +wedding. + + + +LETTER XXII. + +ANIMAL HEAT. + +Now, then, we have got hold of the secret of respiration; the _oxygen_ +within us unites itself to the _hydrogen_ and _carbon._ + +And for what purpose, do you suppose? + +Unquestionably it must be to make a fire, since they never come together +without doing so. + +But what do people make fires for? I ask next. Well! surely to warm +themselves, do they not? + +And this is the history of your body being warm exactly like a +dining-room stove, where the oxygen in the air forms an alliance with +the hydrogen and carbon of the wood. Nature warms little girls inside, +on precisely the same plan by which men warm their houses in winter. + +Imagine, then, a little stove, furnished with little arms for helping +itself out of the wood-basket as it is wanted, and with little legs +to run and refill it when it is empty; the fire must be always burning +there, and the stove must be always warm. + +Just such a little stove is your body; your mouth being the little +door, by which there constantly enter--not wood, that would hardly be +pleasant--but--hydrogen and carbon under the forms of bread, mutton +broth, cakes, sweetmeats, and all the good things people have learnt +to make with sugar, fat, and flour. There is hydrogen and carbon in +everything we eat, as I have already told you; but sugar, fat, flour, +and _wine_ are the substances which contain them in the greatest +quantities, and consequently they are our best _combustibles._ + +You are surprised, perhaps, at _wine_ being a combustible; wine, +which you think would put out rather than make a fire. + +And it would. But that is only because in it, what is good for burning +is mixed with a great deal of water, which prevents our being able to +set it on fire. But if part of this water is withdrawn, you have +_brandy,_ which lights easily enough; and if part of the remaining +water is withdrawn from the brandy, you have _spirits of wine_, which +takes fire more easily still. If you have ever seen a _spirit-of-wine_ +lamp, you must know something about this. Judge from that what a fire +spirits of wine must make in the body, even when it has a good deal of +water with it; for it is right to tell you that your little stove is +very superior to the one in the dining-room, and that it hunts out for +consumption the smallest portions of combustible matter, in places where +the other would be a good deal puzzled to find them. + +This is not all, however. I have much greater wonders to tell you yet. + +What should you say to a stove, which, summer or winter, night or day, +in rain or sunshine, amid the ice of the pole, or under the sun of the +equator, was able to keep itself constantly in the same condition; +neither hotter nor colder one minute than another, whether you gave +it much or little fuel, at a given moment, and sometimes when you gave +it nothing for whole days together? It would be worthy of a fairy tale, +would it not? Yet the human body is a stove of this description. + +But this requires a little explanation. + +It is rather bold in me, you may think, to assert so freely, that all +the year round, from one end of the earth to the other, the human body +is never colder nor hotter than mine is, for instance, at this present +moment. "Hot" and "cold" is soon said, you argue: but the exact +varieties of _more_ or _less_ are not so easy to measure, and especially +not easy to remember, with reference to so many bodies, scattered over +the face of the whole earth. What may be warmth for one in one case, may +not be equal warmth for another; and even supposing that the same +individual learned man could go and inspect every part of the globe in +succession, how could he possibly recall, while touching the body of a +negro in Senegal, in July, the exact amount of animal heat he had found +in a Greenland Esquimaux in January? + +Be content. I should not have settled the question so cavalierly, if +people had not discovered an infallible method of estimating accurately, +and always in the same manner, the degree of warmth, in other words, +the _temperature_ of the body. + +Let us first see, then, what this method is, though it will oblige us +to digress a little; but you are accustomed to that now, surely; and +besides, if I were to go straight ahead, you would not be able to +follow me. + +Do you ever recollect being very cold? Let mammas look after their +little girls as much as they please, to prevent it, it is sure to +happen to every one some day or other. Now does it not seem at those +times as if the whole body were contracting itself--and when people +are shivering with cold, have they not a shrunk, shrivelled look? When +the weather is very hot, on the contrary, our bodies feel as if they +were swelling and stretching, and one seems to take up more room than +before. This is the case with all bodies. Heat swells, or, as learned +people call it, expands, them: cold shrinks or contracts them. +Furthermore, _mercury_ is one of the things most susceptible of this +action of heat and cold, and we have had recourse to it accordingly, in +the construction of the _thermometer_, [Footnote: _Thermometer_ comes +from two Greek words: _thermos_, heat; and _metron_, measure. The +degrees in the Thermometer about to be described are marked on the +_Centigrade_ principle. [Not the one (Fahrenheit) in general use in the +United States.]] a very useful instrument, which you will hear spoken of +all your life. + +The _thermometer_, or _heat-measure_, consists of a little hollow ball +filled with mercury, out of which rises a small tube of very thin glass, +in which the mercury can move up and down. When the thermometer is +exposed to heat, the heat causes the mercury to expand, so it goes up +the tube; when the thermometer is exposed to cold, the mercury contracts +and sinks again. + +Now suppose you were to melt some ice in the palm of one hand, and try +to dip a finger-tip of the other in a saucepan of boiling water; you +would find a great difference of temperature between the two, would +you not? Which difference of temperature people have succeeded in +measuring with the thermometer, as accurately as your mamma measures +a piece of cloth with her yard measure. + +This is how it is done: + +You surround the ball of mercury with pounded ice, and while it is +melting make a mark at that point in the tube where the mercury has +stopped in its descent. Then plunge the thermometer into boiling water. +Whereupon the mercury goes up, up, up, till at last it reaches a point +beyond which it will not pass. Here a second mark is made, and the +space between the two marks is divided into a hundred perfectly equal +parts, indicated by so many small lines, which are called _degrees_. But +this word _degrees_ has a double meaning in some languages. It means +_steps_ as well as the degrees of measurement we are talking about; +steps being, as you know, the perfectly equal parts into which a +staircase is divided. Fancy the mercury-tube a staircase, then, rising +from the cellar where the melting ice is, up to the garret where the +boiling water is, and let it consist of 100 steps. The mercury goes up +and down this staircase, according as the temperature it encounters +approaches that of the boiling water or of the melting ice; and if you +wish to know exactly how far it is from the cellar or from the garret, +you have only to count the _steps_. Hence arise those expressions which +you so often hear--high temperature and low temperature. These mean, +temperature according to which the mercury goes up or down this +staircase. + +On the actual floor of the cellar where the ice melts, there are yet +no degrees (a floor is not a _step_, you know), so there you find the +word _zero_, which means a cipher or nought. Then you begin to count 1, +2, 3, 4 degrees, marked by lines up to 100, where you reach the garret, +_i.e._ the boiling-water height. + +Of course, if the thermometer be exposed to an amount of cold greater +than that of melting ice, the mercury will sink below the cellar. +Accordingly the staircase is carried below it, with steps (so to speak) +of precisely the same size as those above, and you count as before, +1, 2, 3, &c., as it descends; adding however, to distinguish these +degrees from the others, "_below zero_." You may go on in that +way as far as 40; but there you must stop. At that point the mercury +freezes. He sits down there on his last step, and will not go any +further! + +In the same way if the thermometer is exposed to a heat greater than +that of boiling water, the mercury will rise higher than the garret. +So the staircase is made to go up higher, and always with steps of the +same size, counting from 101 upwards, as far as 350 if you choose; but +no further, observe! If the temperature were raised beyond that, the +mercury would begin to boil, and then, indeed, good-bye to steps and +measured degrees! The gentleman would dance so fast that there would +be no possibility of seeing anything, to say nothing of his flying +away! + +Now nothing is easier than to use the thermometer. You place it in the +situation where you want to measure the heat, and the mercury goes up +or down of itself until it reaches the degree which corresponds with +the temperature of the place. It is much more convenient than your +mamma's yard measure, which has to be moved about over the stuff, and +which is very apt to slip if you do not hold it carefully. Dressmakers +would be delighted to have a measure which only wanted laying upon the +material, and which would unroll itself and stop short just at the +proper point. And this kind of office the thermometer really performs. + +We will suppose to-day to be the 30th of November. I have just carried +the thermometer out of doors; the mercury has fixed itself at the +second degree _below zero_. This tells me that it is freezing +cold. My fingers have told me so already; but exactly to what extent +they could not say. Just now in the room, the mercury was at the 15th +degree _above_ zero, thanks to the stove in which we have a good +fire. In summer-time it rises to 25, 26, or 28 degrees. I once saw it +climb as high as 33 degrees: in the shade of course, you understand; +in the sun it would have been quite another affair. Well! there was +a universal outcry against the heat. Grown-up young ladies whom I try +to teach all sorts of things as I do you, pretended that it was +impossible to work. Yet I should find a still greater heat inside my +body, if I could get the thermometer there. Have no fears, however; +I am not going to make a hole in it: luckily there is one already. I +put the ball of mercury into my mouth. And now I can almost tell without +looking. The mercury was on its way up the staircase as soon as I took +the ball in my hand--and now it has reached the 37th step. + +You can try the experiment on yourself, but I forewarn you that it +ought to be rather hotter with you than with me: the mercury will +probably rise a degree higher. I will not promise that in your +grandpapa's mouth it may not sink a degree--but that will be all. In +different mouths it has, between the 38th and 36th degree, room for +the play of a little variation, but it can no more go beyond these +than a tethered cow can get beyond the circle made by her cord as she +turns round the stake. Go round the world with your thermometer, pop +it into everybody's mouth, wiping it if you choose as you proceed, you +will always find the mercury on guard. Its tethering cord is somewhat +elastic, like everything else about us; but if by any accident it +should exceed its limit by even one degree above or below, it would +be quite as extraordinary as meeting a giant of eight feet, or a dwarf +of three--which one does see occasionally, although the standard of +human height varies generally round the centre of five feet. + +Since there is a fire always kept burning within us, there is no +difficulty in comprehending why our bodies always keep warm. Of course, +however, the fire must be kept brighter in winter than in summer, but +people have no need to be told so. Nature provides for the necessity. +She gives us more appetite in cold than in hot weather; not that we +can perceive much difference in ourselves in this respect from winter +to summer; for our bodies stick to their accustomed habits, and call +out pretty loudly for the same daily rations, though without having +the same need of them. In order to estimate fairly the connexion which +exists between the internal need of food--_i.e.,_ of combustible +matter--and the external temperature, we must compare the Hindoo, who +lives on a pinch of rice a day, between the tropic and the equator, +with the Esquimaux, who, to keep up his 37 degrees of heat, beyond the +polar circle, in a country where European travellers have seen mercury +freeze, sometimes swallows from ten to fifteen pints of whale-oil at +a sitting! Just fancy _whale-oil!_ which is much nastier than +even cod-liver oil, if you ever tasted that; but, on the other hand, +it is a thorough _combustible_, and the poor people are not so +very particular: come what will, the fire must be kept up, and that +briskly. But without going thus into extremes, a friend of mine once +told me that in Portugal, the land of oranges, it is not uncommon to +see gentlemen and ladies (that is to say, those who can eat and drink +what they please) dine standing, in five minutes, on a bit of bread +and whatever else may be handy. Propose this system to the inhabitants +of our colder and damper climate, whose very young ladies, fair and +delicate-looking as they are, need a helping of good roast-beef for +dinner to keep life in them, and they would only laugh at you. But +those who were well instructed could go on to inform you that the +chilly atmosphere of northern countries creates the necessity for a +more active internal fire than is ever needed under the burning sun +of Portugal, and that a mouthful of bread per day will not, in their +case, suffice to maintain the appointed thirty-seven degrees of heat. + +For the same reason, Spaniards drink water, and are satisfied; whereas +English wine-merchants add brandy to a good many foreign wines, or +they would be quite unacceptable from being deficient in combustible. +It is for the same reason, also, that Russians can swallow, without +wincing, bumpers of brandy which would kill a Provencal outright: and +that the Swedish Government has no end of trouble to keep the country +people from converting into brandy the corn that ought to go to the +miller; whilst the Mohammedan Arabs accept without difficulty that +precept of the Koran which forbids the use of wine and spirituous +liquors. It is easy for the Arabs, who are kept warm by their climate, +to do without brandy. It is less easy for the Swedes, who are surrounded +by cold. + +All this comes as a matter of course, and we do the same thing +ourselves, without being unusually sagacious. In January, when the +thermometer goes down to twelve or fifteen degrees below zero, I put +more fuel into my stove than I am doing to-day, with only two degrees +of cold to bear with. There is nothing surprising in all this. + +The wonderful thing is, that when an Englishman goes to India, he takes +his roast beef and his spirits with him, and in a temperature of more +than thirty degrees of heat, quietly heaps up fuel in his stove, just +as if he was in England, or nearly so. You think he will set fire to +the house, perhaps. But no. Send the thermometer to his mouth for +information, and it will only mark down thirty-seven degrees; neither +more nor less than in the mouth of a rice-eater! The stove has more +sense than its owner. It only burns just what hydrogen and carbon it +wants, and takes no more trouble about the remainder than if it had +not been eaten. + +How about the remainder, then? you ask; if it is not consumed for use, +what becomes of it? Do you remember, my dear child, that long ago, +after explaining the office of the bile and the liver, I put off telling +you what the bile _consisted of_, until we had talked about the lungs +and respiration? Well, the time has come now; so listen. + +The hydrogen and carbon which is not consumed by the oxygen in the +blood, is seized upon by the liver, who employs it in the manufacture +of bile. Therefore the greater the amount of unemployed hydrogen and +carbon there is in the blood, the greater is the quantity of bile +manufactured by the liver--that is all. When once the body has attained +to its proper degree of heat, it is in vain you load it with +combustibles; it will not get any warmer, do what you will. Only you +will have cut out so much extra work for the liver, and the poor wretch +will have to get through it as he can. Accordingly, what happens in +the long run to our great eaters and drinkers, whether in India or +elsewhere? The bile-manufacturer, overwhelmed with work, gets worn +out at last, and kicks; and people come home with that miserable +disease, which is called the "liver-complaint." + +This is one explanation of that wonderful uniformity of temperature +which, happily, human imprudence cannot disturb. But the blood has a +second resource for getting rid of its superfluity of hydrogen and +carbon, and herein especially is displayed the beautiful foresight +with which everything about us has been prearranged. We are told that +wolves, when they get hold of a larger piece of meat than they care +to eat at the moment, carry off what they do not want to some corner +and bury it in the ground, whence they get it again when their hunger +returns. Dogs sometimes do the same; and the blood has a similar +instinct. Listen attentively, for this is very interesting. + +I light a candle and you see a bright flame, which will last as long +as there is any tallow below the wick. Can you tell me what it proceeds +from? + +Nay, do not laugh at the question; it is quite to the purpose, I assure +you. + +We know, do we not, that the substances which burn best are those which +are full of hydrogen and carbon? Tallow, then, is one of those +substances. But tell me further, if you please, what is tallow? + +Tallow is _mutton fat_, allow me to say, if you never heard it before. + +Now comes the question, who provided the sheep's fat with such a +quantity of hydrogen and carbon as to qualify it for making candles? + +The sheep's blood undoubtedly, since blood is the purveyor-general of +living bodies--of the sheep's body as well as of our own. + +But how came it that the sheep's blood had so large a stock of these +materials? + +Undoubtedly, again, because there was more of them in the food the +sheep had eaten than the oxygen was able to consume or the liver to +employ. In short, the sheep has lungs and a bile-manufactory, as we +have; oxygen performs the same office for it as for us. What takes +place in its body in the matter of respiration is an exact counterpart +of what happens in ours, and the history of its fat is simply the +history of our own. + +Now do you think it is for our sakes that the sheep's blood deposits +its fat in little pellet-like morsels throughout the body; do you +suppose the poor creature works in this manner merely to have the honor +of providing us with candles? It is not likely. I was talking about +the wolf just now; but there is no need to look beyond ourselves. In +many poor people's cottages there is somewhere an old earthen pot in +which the savings of each day are carefully put by, penny by penny, +as a last resource in time of need. Should a wicked thief succeed in +murdering the owner and laying hold of the treasure, he will squander +in a few hours of brilliant revelry the precious hoard so slowly got +together as a provision for possible needs. And this is what man does, +when he kills the sheep and takes its fat to make candles of! The poor +animal's blood knew well that bad times might come, that grass might +fail, and the combustible matter conveyed into the body become +insufficient to maintain its thirty-nine or forty degrees of heat +(which is the sheep's measure, who is rather hotter than we are). So +it quietly laid up its surplus stock of combustible so conveniently +brought to hand, and destined to be burnt little by little in the +depths of the organs, should times of scarcity arise. But here steps +in man, the universal thief of Nature, and turns it into a beautiful +flame, regardless of cost, and burns in one evening what his victim +had been economizing for so long. To burn for burning's sake, however, +has always been the fate of tallow, the only difference being in the +way it is done. Like the poor man's clumsy pence, which were put by +to be spent some day or other, only in another manner. It is worth +noting here, that some of the Russian soldiers who were in France in +1815 had a very good idea of restoring candles to their original +destiny. As children of the north, driven to get fire wherever they +could, they ate all the candle-ends they could lay hold of, preferring +to burn the tallow, sheep's fashion, inside rather than out! + +Fat is, then, the savings' bank of the blood; there it deposits its +savings, and there it can always find them again in time of need. +Witness the fat pig described by Liebig, the great German chemist, +which having been swallowed up by a landslip, was found alive at the +end of 160 days. Fat was out of the question there, of course; the +animal weighed ten stone less than before. We will take the illustrious +professor's word on trust, but were a few days subtracted from the +account the case would still be a splendid example of the resource +which blood finds in fat when other nourishment fails; for the pig had +certainly been breathing during the whole 160 days, and as, in all +probability, he moved about much slower than usual, his hydrogen and +carbon fire was never extinguished for a single instant; of that I am +perfectly certain, and you shall soon know why. It was well for the +poor fellow himself that he had put by his provisions in time of plenty. +And who suffered? Why, the pig's master, who had looked forward with +pleasure to the rashers of bacon he should cut by and by from the +stores of combustibles in his larder. For once Master Piggy ate his +own bacon himself! + +You understand now, I hope, by what ingenious management that marvellous +stove, called an animal, never burns too much fuel, whatever be the +quantity it is supplied with, and how, on the other hand, it has always +as much as it wants. + +I have now to explain how important it is that it _should_ always +have enough, and that this is not merely a question of heat and cold, +as with dining-room stoves, but one of life and death! Cheer up! I +have only one more word to say about Respiration, and when you have +heard it you will appreciate still better the lesson of economy which +you have learnt from Nature to-day. + + + +LETTER XXIII. + +ACTION OF THE BLOOD UPON THE ORGANS. + +The first time we talked about the Blood, my dear little pupil, I +introduced him to you as the steward of your body, and what a steward +to be sure! Always awake, as you may remember, always in motion; his +pockets ever full of the materials unceasingly required by the +indefatigable builders of that human edifice in which it has pleased +God to house your dear little self. If you wish really to understand +what follows now, we must carry on the simile a little further. + +A steward not only provides the workmen with materials, but gives them +orders as well, and this is part of the blood's business also. He is +not only commissary-general, but _whipper-in_ of the whole household, +and besides the care of giving out all the stores, has the charge to see +that everything is properly done. The unhappy men who purchase +prosperity at the dreadful cost of maintaining slavery, pretend that +their slaves would do no work worth looking at, were there not always +some one behind them with a whip in his hand. Well, our organs are +slaves, and slaves of the worst sort. They would never do anything +at all, if the blood were not everlastingly whipping them up in his +ceaseless rounds. Let him come to a stand-still for one minute, for +a second even, and everything stops short; then we are at once in the +castle of the Sleeping Beauty in the wood. But perhaps I cannot do +better than to compare our bodily machine to a violin--to hit upon +something less dismal than slaves--a violin with blood for its bow. +As long as the bow runs over the strings the violin makes music and +lives; when the bow stops, it is silent and dies. + +You have never yet had a fainting fit, my dear child; it rarely happens +at your age. But you may possibly have seen somebody faint; or, at any +rate, you have heard it talked about. Do you know what takes place in +such cases? Now and then, in consequence of some violent emotion, but +how or why I cannot tell you, all the blood rushes suddenly back towards +the heart, as during an earthquake a river will sometimes flow back +towards its source, leaving its bed dry. Thereupon the face turns +white, as if to give notice that there is no longer anything red below +the skin. The organs, no longer stimulated by the blood, leave off +work altogether. The brain goes to sleep, the muscles relax, +consciousness ceases, and you behold the poor body, from which the +soul seems to have departed, give way on all sides, and fall to the +ground like a corpse. This is not exactly death, but it is yet an +interruption of life. It would be death if nature did not get the upper +hand again, and send back the deserter to his post. + +I may remark here that it was partly on this account that some of the +ancients thought the soul was seated in the blood; not a bad idea for +people who were determined to pronounce where the soul was, when it +is so easy to say one knows nothing about it. But those who placed it +in the breath, and who have bequeathed to us those beautiful +expressions--_yielding up the last breath--giving up the ghost_--were +not wrong neither. + +In point of fact the blood is not the soul of the body; in other words, +does not keep the body alive, otherwise than by keeping up unceasingly +and everywhere that magic fire of which we were talking last time. + +The French people, in their picturesque language, have found an +expression, full of energy, to express the action exercised by the +master workman, who knows how to make his people work: "_Il vous met +le feu sous le ventre._" [Footnote: Literally, _he puts fire under +their bellies;_ but here signifying that he makes it so hot that +the organs are compelled to continue in motion.] This is, to the letter, +the process employed by the blood to make the organs work. It makes +a fire under the belly. Unhappily their work only lasts as long as the +fire which causes the heat, and which is so necessary to life that it +is almost confounded with it. It is the sacred fire of the Roman +Vestals, which must be fed night and day under pain of death should +it go out. Now, if to feed the sacred fire of life, it be necessary +that the blood should everywhere find hydrogen and carbon +_unattached_, that is to say, free and ready to unite themselves +to oxygen, it is no less necessary that he should bring oxygen with +him everywhere. Else there would be no marriage, and therefore no fire. +Oxygen is, then, the talisman which brings the organs to obedience. +Without oxygen he would be a slave-driver without his whip; his orders +would be despised. If the organs were to be deluged with _venous_ +blood--with that black blood which has lost its oxygen, they would not +stir any more than if they had received so much water. They acknowledge +nothing but _arterial_ blood--red blood--blood rich in oxygen. +That is what they respect, and which has authority over them; the other +is a bankrupt who has lost his credit with his cash; those whom he fed +but lately now laugh in his face. And as our good steward spends all +his oxygen every time he goes his rounds, it would soon be over with +him, and, consequently, with us, too, if he had not some method of +replenishing his purse after each journey. Happily the lungs are the +inexhaustible chest to which he always returns to renew his right of +authority; that is, his power of preserving life. When it comes to the +_last sigh_, the last effort of the diaphragm by which the chest +is closed forever, we must bid adieu to life. In yielding up that, we +have in very truth yielded up the ghost. + +This is no joke, as you see, and it would not do to be caught +unprepared, with an inexorable necessity hanging over one, which never +allows a moment's respite. The blood acts like a reasonable being, +therefore, in laying up his stores of combustible in reserve. Moreover, +whether he has done so or not, the fire must go on all the same; that +is absolutely necessary; and if he has no spare fat to feed it with, +when, from any cause, the stomach leaves off working, he makes use of +anything he can lay his hands upon. + +I know a story on this subject which will amuse you. + +There lived, in the reign of Francis I. of France, an honest countryman, +of Perigord, named Bernard Palissy. At that time everybody could not +afford to have earthenware plates, as they have now. It was a +manufacture of which only the Italians had the secret, and Bernard, +who knew something of the matter, from being a glass-worker, took it +into his head to try and find it out entirely by himself. So, without +asking anybody's advice, he turned potter, built ovens, picked up wood +as he could, manufactured his first pots, whether well or ill, made +a beginning, and waited. He had fifteen or sixteen years of it before +he succeeded; fifteen or sixteen years of ruinous experiments, which +would have discouraged a less sturdy heart than his. But he, after he +had succeeded in picking up some money by his church windows, returned +to his work with unconquerable perseverance, insensible to poverty, +deaf to the ridicule of neighbors, and unmoved by the abuse of his +wife, who was furious, as you may suppose, at being forced to play the +heroine without having the least turn for it. And one fine day there +was a grand uproar in La Chapelle-Biron (that was the name of his +village). "Bernard Palissy has gone mad," said everybody; "he is burning +up his house to bake his pots." And upon my word it was true! Wood +happened to be wanting while a batch was in the oven, and Bernard +having begun by using up the garden palisades, took next the large +tables, and at last the floor of the house! What his wife had to say, +I leave you to judge; as for him he listened to nothing; but, fixing +his eyes on the insatiable furnace, threw in one thing after another, +caring only for the risk to his handiwork. The ceiling would have +followed the floor had not his pots been sufficiently baked without. + +And thus, and thus, does the blood, when combustible matter fails him! +He demolishes the house, and throws it, bit by bit, into the fire. The +fat goes into it naturally enough, as I have already explained to you. +It is the fuel-store of the house. It was put by on purpose, and may +be used up without injury. Then comes the turn of the muscles; more +useful without being indispensable. Those are Bernard Palissy's +palisades one may contrive to do without them. They melt away, so to +speak, after a few days' fast, and you find yourself what people call +"nothing but skin and bone." But then, if this condition is prolonged, +and the exhausted flesh cannot supply the demand, the blood does not +hesitate a moment. He boldly falls upon the most important organs, +without stopping to consider; he, too, is devoted solely to his work, +and that, like the baking of pots, never comes to an end by being +completed; if external help does not arrive in time, the house soon +becomes uninhabitable, and life slips away. The man dies of hunger. + +But in the same way that poor Bernard Palissy was in reality working, +all the time, for his wife and children, whose future well-being he +strove for as the final end of all his efforts, though at the risk of +letting them sleep under the bare heavens; so the blood was laboring +up to the last moment for that very life which he at last turned out +of doors; and the work of destruction which caused its final departure +has had in reality the effect of prolonging its stay. Without it, all +would have been over long before. + + + +LETTER XXIV. + +THE WORK OP THE ORGANS. + +Thus much is settled, then. It is the blood which sets everything in +motion throughout the body. The organs are idlers who would do nothing +but for him; they only work when goaded on, if I may use the expression, +by that fire--always on the point of going out--which he is perpetually +coming back to rekindle, thanks to the oxygen he carries with him from +the lungs. + +This will enable me to explain many things, which, although not new +to you, you have probably never tried to account for before. + +To begin with: do you remember what happened to you the other day, +when you tried to overtake your mischievous brother in running, and +he, taking advantage of his school-boy legs, led you mercilessly through +all the garden walks, without having the grace even to let you catch +him at the end? You were quite out of breath; your heart beat so rapidly +it almost hurt you; and you were so hot that the perspiration poured +in great drops down your face, so that your mamma, quite frightened, +took you up in her arms and carried you to the fire; for the coolness +of evening was coming on, and a little girl drenched with perspiration +is soon chilled. + +Tell me now, what connection was there between your overrunning yourself +in a race and the extraordinary degree of heat which came over you so +soon? Your cheeks were cool and fresh when you began to run; what made +them so red all at once, and especially at a moment when the air was +cool and fresh in the garden? + +You open your eyes in surprise; you had never thought of this. No! +that is just the way with little girls. They run; they get hot; it +seems as natural as warming oneself in the sun, and they never ask why +it is so. + +Yet you could almost tell me the "why" yourself, if you stopped to +think about it, now that you are what your school-boy brother would +say "_up to a thing or two;_" but to save time, I will help you. + +You run as a bird flies, without thinking about it. Nevertheless, if +you could see with a magic glass all that takes place in your body +while those active little feet are carrying it like a feather across +the garden, you would be perfectly amazed. One of these days, when we +have finished our present history, I will tell you that other one, +which is equally worth the trouble. It is enough for the present to +know, that a very complicated piece of work is being carried on there, +in which almost all the muscles of the body take part at the same time, +contracting and relaxing in turn, like so many springs, of which each +either drives forward or holds back a part of the machine. In fact, +while your eyes and thoughts are fixed on the butterfly which is +flitting away from you through the air, there is going on within you +such an unheard-of outlay of efforts as could never be got out of our +idlers if the terrible steward did not lash them severely. + +Now, his lash, as we have said often enough, is that eternal fire, the +materials of which he conveys to all parts of the body. On those special +occasions, therefore, he is obliged to make his fire burn much more +briskly than usual--exactly like railway engine-drivers, who increase +the heat of their fire to get up steam in proportion to the speed they +wish to go. + +From this you will understand that it is no great wonder that your +small frame should get heated from such work as racing and chasing; +and that if you pursue it too long, the perspiration which comes out +all over you is sufficiently explained. + +This is not all, however. The fire, whose strength has to be increased, +naturally requires a larger amount of combustible matter than before, +and forasmuch as there is only a certain fixed quantity in each drop +of blood, whenever the muscles want more than usual, the blood itself +must flow to them in greater abundance. Now if it were a question of +supplying only one part of the body (as it is, you may remember, of +supplying the stomach during the progress of digestion), he might +contrive to accomplish his task there by neglecting it elsewhere, and +overflow one organ at his ease, at the expense of all the rest. But +in this case he is wanted everywhere in the same abundance. It is not +a question of taking one muscle's share for the benefit of another. +From one end of the body to the other, all want to be deluged at once. +And remember that these exigencies do not bring a drop more blood into +the body. How is he to get out of his difficulty then, this overwhelmed +steward of ours? Well! just as your mamma manages, my dear, when there +is more to do than usual in the house;--by running quicker than ever +from the cellar to the garret, and from your room to your papa's! That +is called doubling oneself; and this gallant blood doubles itself to +some purpose. He runs and runs and runs, arrives in hurried streams, +and returns full gallop, passing and repassing through the heart, which +empties and fills itself in sudden jerks. Unluckily, the poor heart +is a delicate sort of person, who does not like having his habits +disarranged, and this forced work soon makes him desperate. The other +day, in his despair, he knocked with all his strength against the walls +of his little chamber, to warn his young mistress that he could bear +no more, and that they were both of them in danger. In fact, you ought +to know that if one was infatuated enough to go on running too long, +one might die of it. When you learn ancient history, you will probably +be told of what happened to the soldier of Marathon, who flew like an +arrow from the field of battle to the gates of Athens, that he might +tell his fellow-citizens a quarter of an hour earlier, that his country +was saved; and he fell dead on his arrival. + +But it is not the heart only which suffers by this mad career of the +blood. During each journey it performs it passes through the lungs, +which in their turn are forced to play with hasty jerks. And this is +well for our good steward; for the lungs, filling with air at each +descent of the diaphragm (if you remember what we have said before), +more air, and consequently more oxygen, comes in, and the blood has +by this means a larger stock on hand, ready to help him out in the +unusual waste which is just then going on in the muscles. I spoke just +now of railway steam-engines. See how self-supporting ours is! The +greater the amount of fire wanted, the faster the blood flows; and the +faster the blood flows, the oftener does the coffer re-fill itself, +whence comes the supply of oxygen requisite for keeping up the fire. +All this goes on at once, by one impulse, and the balance between the +receipts and expenditure settles itself of its own accord. How thankful +many families would be if their money-chest would but fill itself in +the same way--in exact proportion as they spend the cash! There is +only one slight drawback, which is, that the diaphragm gets tired with +the unaccustomed gallop it is thus forced into. It falls into +convulsions, therefore, like its neighbor the heart, and the breathing +is stopped, from having been driven too rapidly. An excellent example +for people who want to spend too much at once; showing that Nature +herself cries out against it, even when the only thing wanted is +atmospheric air. + +Now, run if you dare! And, to tell you the truth, it would be a great +pity if you did _not_ dare; for our good God has made little children +for running. They have nimbler blood than we older grandfathers, more +elastic lungs, and consequently more oxygen to spend at a time. But you +must confess that it is a great pity we should run all our lives as many +people do, without having the slightest idea of these admirable +contrivances, thanks to which we are enabled to do it. We can run all +the same, it is true, without the knowledge, the little child as easily +as the little roebuck, which sets a similar machine in motion. But it is +no use talking about the little roebuck; it cannot learn what God has +done for it, but the little child can, if he will. Furthermore, there is +nothing to be really alarmed about, for those great commotions only +occur when we have committed excess; and it is a very good thing, in a +general way, for the blood to give us a stroke of his lash from time to +time. I told you lately that the fire which sets the organs to work is +life; and it is no misfortune to be a little more alive than usual. +Besides which, this increased activity of the internal fire does not +serve us in running only. Every time that a man makes an effort; every +time he lifts a weight, or handles a tool, the blood rushes forward to +deluge the muscles that are thus called into play; the heart beats more +quickly, and the air streams in greater abundance into the lungs. Look +at a man chopping wood. If the log resists too much, if for a minute or +two the man has to strike blow after blow without stopping, you will +soon see him panting for breath, just as if he had been running a race. +On the other hand, he will have gained something from chopping his log +besides the right of warming himself before it at the fire. Blood does +not carry fire only into the muscles; he supplies them with nourishment +also, does he not? Every drop of blood deposits its little offering as +it goes by, and consequently the greater the number that pass along, the +richer is the harvest for the muscle. Look, accordingly, at the laboring +classes. How much healthier and stronger they are than those who do not +work! I speak, of course, of working with one's limbs generally; for +those poor girls who work from morning to night, sitting on their +chairs, are none the better for it, but, on the contrary, worse. There +are also certain worthy fellows who, like myself at the present moment, +drive a pen over sheets of paper for half a day at a time, whose muscles +never get any bigger for it, that is quite clear. Moreover, one +condition has to be fulfilled, which unhappily is not always done. The +more people labor, the more they ought to eat. To you, who have just +been looking at the drama that is performed in the body every time a +muscle is set in motion, this is obvious enough. There is no fire +without smoke, says the proverb. It would have been much better to +have said,--there is no fire without fuel;--and the fuel for our fire +is, as you know, what we eat. Try if you can get one stove to burn +more brightly than another, if you have put less fuel into it. Yet, +alas! this is what many poor wretches are obliged to do but too often; +and then the blood, instead of feeding their muscles, consumes them, +for the reasons I gave, in telling you the story of Bernard Palissy. +Think of this, oh my dear child, when you are grown up, and never +grudge those who work for you their proper share of food. + +Here I see many other lessons crowding up, out of what you have just +learnt. + +And first Nature herself, taken as you find her, shows you that manual +labor is, for us, a most beneficial condition of existence; that it +brings about a re-doubling, an exaltation of life; and that +consequently, we have no need to look down upon those who gain their +bread, as we word it, by the sweat of their brows. I told you this +before, in speaking of the hand, which is of so much more use to those +people than to you; and I repeat it now for another reason, viz.: +because labor elevates him who undertakes it, and creates a real +physical nobility. Barbarians in old times, who knew nothing noble nor +grand but war, despised labor, and left it to their slaves; so much +so, that the name _servile labor_, _i.e._ the labor of slaves, +has stuck to it in some places. As for war, the lot of the ancient +nobility, I scarcely dare to say much against it, however much I should +like to do so on some accounts. For, after all, so long as there are +ruffians to trample on the weak, one is only too glad to find brave +men ready to risk their lives in keeping such rascals down: so long +as there are wolves, we must needs keep shepherds' dogs. But in spite +of everything, the best that can be said in favor of war is, that it +remains a sad but inevitable necessity, and that to get rid of it, +more is wanting than the wish. What a contrast to labor--that contest +of Man with Nature;--that merciful and fruitful war, where victories +are not estimated like other victories, by the number of the slain, +but which, on the contrary, scatters fresh life around it as it spreads; +fresh life in the laborer himself, by the very act of work, fresh life +around him without, by the fruits that work produces! + +Between the man who dies in slaying others, and the man who keeps +others alive by living longer himself, it seems cruel to make invidious +comparisons; but if it be just to honor the first out of respect for +the cause he has defended, whenever that cause is respectable--it is, +to say the least of it, not less just to do equal honor to the second. + +But let us come down from these philosophic heights, and return to +you, dear child; to you, who have nothing to do with war, its massacres +or its laurels. + +It is true, however, that you have nothing to do either, with chopping +wood, and I am not asking you to undertake any such thing. But in the +life of a woman, from the time of her childhood upwards, a thousand +things arise for the hands to do, and the question is, how often you +are likely to feel ashamed of not sending for the servants to do them? +Avoid this false and fatal idea as much as possible. The work of the +hands dishonors no one; it is honorable. To cast it aside altogether +is to make yourself smaller instead of greater; to deprive yourself +of one of the glories and the joys of life. If a good thing is set +before you at dinner, do you send for the servants to eat it? If an +occasion arises for making the blood circulate more rapidly in your +veins, and of increasing the strength and life with, in you into the +bargain, why make _them_ a present of it? Especially when it +cannot be an agreeable present considering that good servants have +plenty of such opportunities from morning to night every day. + +There was once upon a time a Persian prince staying in Paris, who was +taken to a very fashionable ball, that he might see a specimen of +European civilization. I am not talking about a prince in the "Arabian +Nights;" mine lived, I believe, in the time of Louis Philippe. The +beautiful dancers wheeled round, their eyes brilliant with pleasure, +in the arms of elegant cavaliers; one would have said that the whole +of this airy troop, swaying to and fro in time to the lively flourishes +of the music, was animated by one soul; everything seemed full of joy +in that large and splendidly lit hall, and mothers secretly envied +their daughters as they passed and re-passed before them. Our oriental +alone scanned with a disdainful eye this youthful enjoyment. + +When it was ended,--"How is this?" said he to his conductor; "did you +not tell me that I was to see here the most distinguished families of +Paris?" + +"Certainly," replied the other; "among those young ladies who were +just now dancing before you, there were at least twenty of the grandest +heiresses of France." + +"Young ladies who dance! Come, come! In my country we have dancers, +but they are paid for it. Our wives are never permitted to dance +themselves. That is all very well for the common people!" + +Remember, when needful, the contempt of this Persian prince, my dear +child; and let me beg of you, work for yourself. The dance of labor +is worth quite as much as that of the ball-room, when you give your +heart to it. It is even worth more, very often; and next time I will +tell you why. + + + +LETTER XXV. + +CARBONIC ACID. + +We are going to make acquaintance to-day with a new personage, who +well deserves our attention. It is the child of oxygen and carbon, +[Footnote: This is the name learned men have given to Charcoal.] though +not in the same way that you are the child of your parents. + +To tell you how it is made is more than I am able. It is a _gas_, +or if you like the word better, it is an _air_; for when we say +"gas," we mean "air;" only it is always a different sort of air from +the air of the atmosphere, which learned people are not in the habit +of calling _gas_. I cannot, therefore, show you _carbonic acid_ itself, +for it cannot be seen any more than the air which fills an empty glass. +But I can tell you where there is some, and you even probably know it by +its effects, although you have never heard its name. + +Do you remember, on your aunt's wedding-day, that there was a sparkling +wine called champagne, at the grand breakfast? You smile, so I conclude +somebody gave you a little to taste; and if so, you will remember how +sharp it felt to your tongue. Do you remember, too, how the cork flew +out when they were opening the bottle, and how the noise of the "pop!" +startled more little girls than one? It was _carbonic acid_ which +sent the cork flying in that wild way; the carbonic acid which was +imprisoned in the bottle, in desperately close quarters with the wine, +and which accordingly flew out, like a regular goblin, the moment the +iron wire which held down the cork was removed. What sparkled in the +glass, making that pretty white froth which phizzed so gently, as if +inviting you to drink, was the carbonic acid in the wine, making its +escape in thousands of tiny bubbles. What felt so sharp to your tongue +was the same carbonic acid, in its quality of acidity, for thence it +has its name; the word _acid_ being borrowed from a Latin word +signifying the sharp pungent taste, almost _fine-pointed_ as it +were, peculiar to all substances which we call _acids_. + +It is carbonic acid also which causes the froth in beer and in new +wine when bottled. It is he who makes soda-water sparkle and sting the +tongue, and ginger-beer the same, if you happen to like it; and so far +you have no particular reason for thinking ill of him. But beware. It +is with him as with a good many others who have sparkling spirits, who +make conversation effervesce with gayety, and who are very seductive +in society when you have nothing else to do but to laugh over your +glass, but whose society is fatal to the soul which delivers itself +up to them. This charming carbonic acid is a mortal poison to any one +who allows it to get into his lungs. + +You remember what a violent headache your servant suffered from the +other day after ironing all those clothes you had in the wash? She +owed that headache entirely to this work which she did for you. She +had remained too long standing over the coals over which her flat-irons +were being heated. You know already that when charcoal burns, it is +from the carbon uniting with the oxygen of the air; from this union +proceeds that mischievous child, carbonic acid gas, in torrents, and +the poor girl was ill, because she had breathed more of this than was +good for her health. Observe well, that the room-door was open to let +in the fresh air, and that there was a chimney, to allow the carbonic +acid to escape. It was on this account that she got off with only a +headache. Unhappily, there have sometimes been miserable people who, +weary of life, and knowing this, but not knowing or thinking about the +God who overrules every sorrow for good, have shut themselves up in +a room with a brazier of burning charcoal, after taking the fatal +precaution of stopping up every opening by which air could possibly +get in; and when at last, in such a case, uneasy friends have forced +open the well-closed door, they have found nothing within but a corpse. +Then, too, there are those frightful accidents of which we hear so +often, of workmen groping their way down into long disused wells, who +have died as they reached the bottom; or of sudden deaths in coal-pits. +In general these have been owing to the poor victims encountering the +long pent-up carbonic acid gas, whose poisonous breath blasted and +destroyed them at once. + +You may well ask why I am telling you such horrible stories, and what +I am coming to with my carbonic acid? But you have more to do with it +than you think, dear child. You, and I, and everybody we meet, nay, +and the very animals themselves, since their machines are of the same +sort as ours, are all little manufactories of carbonic acid. The thing +is quite clear. Since there is a charcoal fire lit in every part of +our body, there always arises from the union of the oxygen brought by +the blood with the carbon it meets in our organs, that mischievous +child we have been talking about; and our throat is the chimney by +which he gets away. He would kill us outright were he to stop in the +house. + +This is how it comes about: In proportion as the blood loses its oxygen, +it picks up in exchange the carbonic acid produced by combustion, so +that it is quite loaded with it by the time it returns to the lungs. +There it takes in a fresh supply of oxygen, and discharges at the same +time its overplus of carbonic acid, which is driven out of the body +by the contractions of the chest, pell-mell with the air which has +just been made use of in breathing. You are aware that this air is not +the same at its exit as at its entrance to the body, and that if you +try and breathe it over again it will no longer be of the same use to +you. That is because it has lost part of its oxygen and brings back +to you the carbonic acid which it had just carried off. If you take +it in a third time, it will be still worse for you; and in case you +should continue to persist--the oxygen always diminishing, and the +carbonic acid always increasing in quantity--the air which was at first +the means of your life will at last become the cause of your death. +Try, as an experiment, to shut yourself up in a small trunk, where no +fresh air can get in; or even in a narrow closely-shut closet, and you +will soon tell me strange news. There will be no occasion to light a +charcoal fire for you in there. Enough is kept burning in your own +little stove, and you will poison yourself. + +You see now that the dreadful stories I was telling a short time ago +have something to do with you, and that it is a good thing to be warned +beforehand. And now tell me, when a hundred people--or I ought to say, +a hundred manufactories of carbonic acid--are crowded together for a +whole evening, sometimes for a whole night, in a space just big enough +to allow them to go in and come out; tell me, I say, if that is a sort +of thing which can be beneficial to the health of little girls whose +blood flows so fast, and who require so much oxygen; and whether, on +the contrary, it is not one's duty to keep them away from such scenes? + +There may be amusement there, I know; but the best pleasures are those +for which one does not pay too dearly. I have seen the very wax lights +faint and turn pale all at once, in the very midst of those murderous +assemblies, as if to warn the imprudent guests that there was only +just time to open the windows. + +And this reminds me of a point I had nearly forgotten. Wax-candles arc +like ourselves. In order to burn, they must have oxygen, and, like us, +they are extinguished by carbonic acid. But like us also--and indeed +to a greater extent, because they consume much more charcoal at +once--they manufacture carbonic acid. Hence that very illumination +which affords the company so much pleasure and pride is plainly an +additional cause of danger. Each of those wax-lights which is spread +around with such a prodigal hand, the only fear being that there may +not be enough of them, is a hungry intruder employed in devouring with +all his might the scanty amount of oxygen provided for the consumption +of the guests. + +From each of those cheerful flames--the suns, as it were, of the festive +assembly--shoots out a strong jet of carbonic acid, contributing by +so much to swell out the already formidable streams of poisoned gas, +exhaled to the utmost extent by the dancers. And wait--there is still +something else I was forgetting. You dance. And I told you last time +at what cost you have to dance. You have to make the fire burn much +quicker than usual, that is, to consume a great deal more oxygen at +once, and so you double and treble the activity of the carbonic acid +manufacture: and this just at the moment when it would be so convenient +that it should go on as slowly as possible! After this, you need not +be surprised that people should look fagged and exhausted next morning. +What astonishes me is that they are not obliged to lie in bed +altogether, after treating their poor lungs to such an entertainment. +And even if you have spared your legs, you are not much better off, +as you are sure to find out in time, especially if the thing is repeated +too often. + +When I told you just now that the dance of labor was worth as much as +the dance of the ball-room, was I right or wrong? What do you say +yourself? + +I could repeat the same of theatres--places of entertainment specially +adapted for impoverishing the blood, and ruining the health of the +happy mortals who go there, evening after evening, to purchase at the +door the right of filling their lungs with carbonic acid, not to speak +of other poisons. You must see clearly that such places as those are +not fit for little lungs as dainty as yours; and this may help you to +submit with a good grace when you see people going there without you. +Grown-up people escape moreover, because the human machine possesses +a strange elasticity, which enables it to accommodate itself--one +scarcely knows how--to the sometimes very critical positions in which +its lords and masters place it without a thought. But to do this, it +is well that it should be thoroughly formed and established; for you +run a risk of injuring it for ever, if you misuse it too early in life. +Tell this to your dear schoolboy brother, when he wants to smoke his +cigar like a man. If his lungs could speak, they would call out to him +that it was very hard upon them, at their age, to be so treated, and +that he ought at any rate to wait till they had passed their +examinations! + +But I must not get into a dispute with so important an individual, by +throwing stones into a garden which is not under my care. For you, my +dear child, the moral of this day's lesson--which to my mind is much +more alarming than a hobgoblin tale, since it concerns the realities +of every-day life--is clear; and it is this: + +Seek your amusements as far as possible in the fresh air. In the summer, +when the lamp is lit, bid your mamma a sweet good-night, and go to +bed. In the winter do not wait till there is a great quantity of +carbonic acid in the room where the grown-up people are sitting, before +you retire to your own like a reasonable girl, anxious not to do +mischief to that valuable and indefatigable servant, the poor blood! +Not to mention that if she were to injure him too much, she would have +to bear his grumbling for the rest of her life. We cannot change him +as we change other servants. + + + +LETTER XXVI. + +ALIMENTS OF COMBUSTION. + +We have spent a very long time, my dear child, over the little fire, +which goes on burning secretly in every one of us, quietly devouring +what little girls eat with such a good appetite, quite unsuspicious +of what they are doing it for. However, if I mean to finish the history +of our mouthful of bread, I must push on to its last chapter. + +The _whole_ of what we eat is not burnt, as you may easily suppose; for, +if it were, what would the blood have left to feed the body with, and to +repair in due proportion the continual destruction or waste which goes +on in our organs? Our food, or "_aliments_" as the general collection of +different sorts of food is called, are divided into two very distinct +sets: some, which are destined to be burnt, and which are called +_aliments of combustion_; others, which are destined to nourish the +body, and which are called _aliments of nutrition_. I have to tell you +now about these last, and you will find their history by no means +uninteresting. + +Learned men having detected, beyond the possibility of a doubt, the +existence of these two sorts of aliments, one is tempted to think they +ought to have made it known to the cooks, and that ever since so +important a discovery, the dishes on all well-regulated tables should +have been arranged accordingly; aliments of combustion on one side, +aliments of nutrition on the other. It cannot be enough merely to give +your guests a treat; you ought to provide them with everything necessary +for the proper fulfilment of the claims within; and if you give some +nothing but combustibles, leaving the others no share of fuel, how +will they be able to manage? Nobody thinks about this, however; not +even cooks, to begin with, who, as far as fire is concerned, find they +have had quite enough to do with it in their cooking; and as for the +guests, when they have had their dinner they go away satisfied, as a +matter of course, quite as well provided for as if the mistress of the +house had made her calculations, pen in hand, while writing out the +bill of fare, with a view to combustion and nutrition. Now, how is +that? + +It is because the two sorts of aliments are, for the most part, met +with together in everything we eat, so that we swallow them at once +in one mouthful; and have therefore no need to trouble ourselves further +on the subject. There is our bit of bread, for instance. What is bread +made of? Of flour. Bread, then, must contain all that was previously +in the flour. Very good. Now I will teach you how to discover in flour +the aliment of combustion on the one hand, and the aliment of nutrition +on the other. + +Take a handful of flour, and hold it under a small stream of water; +knead it lightly between your fingers. The water will be quite white +as it leaves it, carrying away with it a fine powder, which you could +easily collect if you were to let the water run into a vase, where the +powder would soon settle to the bottom. That powder is starch--the +same starch as washerwomen use for starching linen, and which our +grandfathers employed in powdering their wigs. You had some put on +your own hair one day when you were dressed up as a court-lady of olden +time. Now, starch is an excellent combustible. People have succeeded, +by means which I will not offer to detail here, in ascertaining almost +exactly what it is made of, and they have found in it three of our old +acquaintances, oxygen, hydrogen, and carbon, combined together in such +proportions that 100 ounces of starch contain as follows: + + Ounces. + Carbon 45 + Hydrogen 6 + Oxygen 49 + --- + 100 +I give you the calculation in round numbers, so as not to burden your +memory with fractions; and I will do the same with the other sums I +shall have to go through to-day, this being, let me tell you, an +arithmetical day. Besides, I could scarcely take upon myself to warrant +the absolute correctness of those very precise fractions people +sometimes go into. Even our learned friends squabble now and then as +to which is right or wrong over the 100th part of a grain, more or +less, in making out their balance, and you and I will not offer to +decide between them. I always think we have accomplished wonders in +getting even _near_ the mark, and with their permission we will +stop there. + +Starch, then, of whose weight carbon constitutes nearly one-half, is +of course a first-rate combustible. Indeed, one may almost consider +it the parent, as it were, of at least half our aliments of combustion, +for if (in consequence of a certain operation, which nature has the +power of performing for herself, in certain circumstances) it loses +a portion of its carbon, so that there remain but 36 ounces of it in +the 100 of starch, our starch is turned into something else; now can +you guess what that something is? Neither more nor less than _sugar_! +Witness the grand manufactories at Colmar, in France, where bags of +starch are converted into casks of syrup by a process of nature alone; +so that the inhabitants of the neighborhood sweeten their coffee at +breakfast with what might have been made into rolls, had it been left +alone. And this is not all. Give back this starch-sugar into the hands +of Nature once more by putting it into certain other conditions, and a +new process begins in it. About a third of its carbon will unite itself, +of its own accord, with the two-thirds of its oxygen, so as to make +carbonic acid, (you are acquainted with that gentleman now) which shall +fly off and away, and there will remain--what do you think?--_Alcohol_, +that other combustible we talked about, and which burns even better than +sugar and starch, since in a hundred ounces it contains as follows:-- + + Ounces. + Carbon 53 + Hydrogen 13 + Oxygen 34 + --- + 100 + +All this astonishes you. What would you say then if I were to tell you +that your pocket-handkerchief is composed of entirely the same materials +as starch, and in the same proportions too, and that if a chemist were +to take a fancy, by way of a joke, to make you a tumbler of sugar and +water, or a small glass of brandy out of it, he could do so if he +chose. Wonders are found, you see, in other places besides fairy tales; +and since I have begun this subject I will go on to the end. Know then +that from the log on the fire, to the back of your chair, everything +made of wood, is in pretty nearly the same predicament as your +pocket-handkerchief; and if people are not in the habit of making casks +of syrup and kegs of brandy out of the trees they cut down in the +woods, it is only, I assure you, because such sugar and brandy would +cost more to make than other sorts, and would not be so good in the +end. Should some one ever invent and bring to perfection an economical +process for doing it thoroughly well, sugar-makers and spirit-distillers +will have to be on their guard! + +But we are wandering from our subject. If I have allowed myself to +make this digression, however, it is because I am not sorry to accustom +your mind early to the idea of those wonderful transformations which +nature accomplishes, and of which I could give you many other instances. + +To return to our flour. As soon as all the starch is gone out of it, +there remains in your hand a whitish, elastic substance, which is also +sticky or _glutinous_, so that it makes a very good glue if you choose; +and hence its name of _gluten_, which is the Latin word for glue. + +When dried, this _gluten_ becomes brittle and semi-transparent. +It keeps for an unlimited time in _alcohol_, putrefies very soon +in water exposed to the air, and is easily dissolved in a wash of soda +or potash. Finally 100 ounces of it contain as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +Observe the last material named. It is a new arrival, of which I shall +soon have something to say. + +But where am I leading you? you will ask, with all these uninteresting +details about glue. + +Wait a little and you shall hear. + +You have probably never seen any one bled, which is a pity, as it +happens; for if you had, you might have noticed (provided you had had +the courage to look into the basin), that after a few seconds, the +blood which had been taken away separated itself of its own accord +into two portions; the one a yellowish transparent liquid, the other +an opaque red mass floating on the top, and which is called the +_coagulum_ of the blood or _clot_. This _coagulum_ owes its color to an +infinity of minute red bodies of which we will speak more fully by and +by, and which are retained as if in a net, in the meshes of a peculiar +substance to which I am now going to call your attention. + +That substance is whitish, elastic and sticky; and when dried becomes +brittle and semi-transparent. It keeps for an unlimited time in alcohol, +putrefies very soon in water exposed to the air, and is easily dissolved +in a wash of soda or potash. Finally 100 ounces of it contain as +follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +This substance is called _fibrine_. It goes to form the fibres of those +muscles which are contained in a half formed state in the blood. + +You are laughing by this time I know, and I also know the reason why. +I have told you the same story twice over. You have not forgotten my +wearisome description of _gluten_, and here I am, saying exactly +the same thing of _fibrine_! You conclude I am dreaming, and have +made a mistake! + +But no, I am wide awake, I assure you, and mean what I say. And if +these details are the same in the two cases, it is for the simple +reason that the two bodies are one and the same thing; _gluten_ and +_fibrine_ being in reality but one substance, so that were the most +skilful professor to see the two together dried, he would be puzzled to +say which came from the flour, and which from the blood. I mentioned +that our muscles existed in a half-formed state in the blood. Here is +something further. The _fibres_ of muscles exist previously in full +perfection, in the bread we eat; and when you make little round pills of +the crumbs at your side, it is composed of fibres stolen from your +muscles which enable the particles to stick together; and I say _stolen +from your muscles_, because they are the _gluten_ which you ought to +have eaten. I hope the thought of this may cure you of a foolish habit, +which is sometimes far from agreeable to those who sit by you. + +This, then, is the first great _aliment of nutrition_, and you +may make yourself perfectly easy about the fate of those who eat bread. +If little girls should now and then have to lunch on dry bread, I do +not see that they are much to be pitied. There is the starch to keep +up their fire, and the gluten for their nourishment, and that is all +they require. The porter above is the only one who finds fault. And +in these days porters have become more difficult to please than the +masters themselves. + +Then as to babies who drink nothing but milk, you perhaps wish to know +where they get their share of fibrine. + +And I am obliged to own there is none in the milk itself; but, I +daresay, you know curdled milk or _rennet_? The same separation into two +portions has taken place there which occurs in the blood when drawn from +the arm; underneath is a yellowish transparent liquid,--that is the +_whey_; above a white curd of which cheese is made, and which contains a +great part of what would have made butter. By carefully clearing the +curd from all its buttery particles you obtain a kind of white powder +which is the essential principle of cheese, and to which the pretty name +of _casein_ is given because _caseus_ is the Latin for cheese. I shall +not trouble you now with details about _casein_; but there is one thing +you ought to know. A hundred ounces of _casein_ contain as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +Exactly like gluten and fibrine! + +Now, then, you can understand that no particular credit is due to the +blood for manufacturing muscles out of the cheese of the milk which +a little baby sucks. He has much less trouble than the manufacturers +at Colmar have in turning their starch into sugar; because in his case +the new substance is not only composed of the same materials as the +old one, but contains them in exactly the same proportion also. + +We have a second aliment of nutrition, you see, and I must warn you +that it is not found in milk only. It exists in large quantities in +peas, beans, lentils, and kidney-beans, which are actually full of +cheese, however strange this may seem to you. It would not surprise +you so much, however, if you had been in China and had tasted those +delicious little cheeses which are sold in the streets of Canton. They +cannot be distinguished from our own. Only the Chinese (from whom we +shall learn a great many things when we have beaten them so that they +will conclude to be friends with us)--the Chinese, I say, do without +milk altogether. They stew down peas into a thin pulp. They curdle +this pulp just as we do milk, and in the same way they squeeze the +curd well, salt it, and put it into moulds--just as we do--and out +comes a cheese at last--a real cheese, composed of real _casein_! +Put it into the hands of a chemist, and ask him the component parts +of a hundred grains of it, and he will tell you as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7, etc. + +I stop there; for you surely know the list by this time! + +Only the third aliment of nutrition remains to be considered, for there +are but three; and I will tell you in confidence, what is stranger +still, viz., that there is in reality but one! But we have had enough +food for one day, and I do not wish to spoil your appetite. We will +reserve the rest for another meal. + + + +LETTER XXVII. + +ALIMENTS OF NUTRITION (_continued_). + +NITROGEN OR AZOTE. + +There is a favorite conjuring trick, which always amuses people, though +it deceives no one. The conjuror shows you an egg, holds it up to the +light that you may see it is quite fresh, then breaks it; +and--crack--out comes a poor little wet bird, who flies away as well +as he can. + +This trick is repeated in earnest by nature every day, under our very +eyes, without our paying any attention to it. She brings a chicken out +of the egg, which we place under the hen for twenty-two days, instead +of eating it in the shell as we might have done, and we view it as a +matter of course. Yet we do not say here that the bird may not have +come down the conjuror's sleeve, or the hen may not have brought it +from under her wing. It was really in the egg, and its own beak tapped +against the shell from within and cracked it. + +How has this come about? No one can have put that beak, those feathers, +those feet, the whole little body, in short, into the egg while the +hen was sitting upon it, that is certain. It is equally certain, then, +that the liquid inside the egg must have contained materials for all +those things beforehand; and if Nature could manufacture the bones, +muscles, eyes, etc., of the chicken, out of that liquid while in the +egg, she would probably have found no more difficulty in manufacturing +your bones, muscles, eyes, etc., from it had you swallowed the egg +yourself. + +Here, then, is an undeniable _aliment of nutrition_. + +It is called _albumen_, which is the Latin word for _white of egg_. It +is easily recognized by a very obvious characteristic. When exposed to a +temperature varying from sixty to seventy-five degrees of heat, +according to the quantity of water with which it is mixed, _albumen_ +hardens, and changes from a colorless transparent liquid, into that +opaque white substance, which everybody who has eaten "hard-boiled eggs" +is perfectly well acquainted with. + +I will only add one trifling detail. 100 ounces of albumen contain as +follows: + + Ounces. + Carbon 63 + Hydrogen -- + +You can fill up this number yourself, can you not? And knowing the 7 +of hydrogen, you may guess what follows! After what we have talked of +last time, here is already an explanation of the chicken's growth. But +let us go on. + +You recollect that yellowish liquid I spoke about, which lies underneath +the _clot_, or _coagulum_ of the blood? I will tell you its name, that +we may get on more easily afterward. It is called the _serum_, a Latin +word, which, for once, people have not taken the trouble of translating, +and which also means _whey_. Put this _serum_ on the fire, and in +scarcely longer time than it takes to boil an egg hard, it will be full +of an opaque white substance, which is the very _albumen_ we are +speaking of. Our blood, then, contains _white of egg_; it contains in +fact--if you care to know it--sixty-five times more white of egg than +fibrine, for in 1,000 ounces of blood, you will find 195 of _albumen_, +and only three of _fibrine_; of _casein_, none. + +Nevertheless we eat cheese from time to time. And we generally eat +more meat than eggs, and meat is principally composed of fibrine! I +should be a good deal puzzled to make you understand this, if we had +not our grand list to refer to. + + Ounces. + Carbon 63 + Hydrogen 7, etc. + +_Fibrine_, casein_, _albumen_, they are all the same thing in the main. +It is one substance assuming different appearances, according to the +occasion; like actors who play several parts in a piece, and go behind +the scenes from time to time to change their dresses. The usual +appearance of the aliment of nutrition in the blood is _albumen_; and in +the stomach, which is the dressing-room of our actors, _fibrine_ and +_casein_ disguise themselves ingeniously as _albumen_; trusting to +_albumen_ to come forward afterwards as _fibrine_ or _casein_, when +there is either a muscle to be formed, or milk to be produced. + +Know, moreover, that _albumen_ very often comes to us ready dressed, and +it is not only from eggs we get it. As we have already found the +_fibrine_ of the muscle and the _casein_ of milk in vegetables, so we +shall also find there, and that without looking far, the albumen of the +egg. It exists in grass, in salad, and in all the soft parts of +vegetables. The juice of root-vegetables in particular contains +remarkable quantities of it. Boil, for instance, the juice of a turnip, +after straining it quite clear, and you will see a white, opaque +substance produced, exactly like that which you would observe under +similar circumstances in the _serum_ of the blood; real _white of egg_, +that is to say--to call it by the name you are most familiar with--with +all its due proportions of carbon, hydrogen, oxygen, and nitrogen. + +I wonder whether you feel as I do, dear child; for I own that I turn +giddy almost when I look too long into these depths of the mysteries +of nature. Here, for instance, is the substance which is found +everywhere, and everywhere the same--in the grass as in the egg, in +your blood as in turnip-juice! And with this one sole substance which +it has pleased the great Creator to throw broadcast into everything +you eat, He has fashioned all the thousand portions of your frame, +diverse and delicate as they are; never once undoing it, so to speak, +to re-arrange differently the elements of which it is composed. From +time to time it receives some slight impulse which alters its appearance +but not its nature, and that is all. As the chemist found it in the +bit of salad, so he will find it again in the tip of your nose, if you +will trust him with that for examination. We are proud of our personal +appearance sometimes, and smile at ourselves in the looking-glass; we +think the body a very precious thing; but yet when we look deeply into +it we find it merely so much charcoal, water and air. + +This reminds me that we have not yet made acquaintance with the new +personage who was lately introduced upon the scene. _Nitrogen_ or +_azote_, I mean. He plays too important a part to be allowed to remain +in obscurity. + +You have already learnt that oxygen united with hydrogen produces +water. Combined with nitrogen it produces air; but in that case there +is no union of the two. They are merely neighbors, occupying between +them the whole space extending from the earth's surface to forty or +fifty miles above our heads; together everywhere, but everywhere as +entire strangers to each other as two Englishmen who have never been +introduced! I should be a good deal puzzled to say what nitrogen does +in the air: he is there as an inert body, and leaves all the business +to the oxygen. When we breathe, for instance, the nitrogen enters our +lungs together with its inseparable companion, but it goes out as it +went in, without leaving a trace of its passage. Nevertheless, as +sometimes happens among men, the one who does nothing takes up the +most room. Nitrogen alone occupies four-fifths of the atmosphere, where +it is of no other use than to moderate the ardent activity of king +oxygen, who would consume everything were he alone. I can compare it +to nothing better than to the water you mix with wine, which would be +too fiery for your inside if you drank it by itself. This is what +nitrogen does. It puts the drag on the car of combustion; as in society, +the large proportion of quiet people put the drag on the car of progress +(let us for once indulge ourselves in talking like the newspapers!); +and such people are of definite use, however irritating their +interference may appear in some cases. The world would go on too rapidly +if there were nothing but oxygen among men. We have quite enough in +having a fifth of it! + +But what in the world am I talking about? Let us get back to nitrogen +as fast as we can! + +We must not imagine there is no energy in this quiet moderator of +oxygen. Like those calm people who become terrible when once roused, +our nitrogen becomes extremely violent in his actions when he is excited +by another substance, and is bent on forming alliances. Sometimes the +usually cold neighbor unites itself to oxygen in the closest bonds; +in which case the two together form that powerful liquid, _aqua-fortis_, +of which you may have heard, and which corrodes copper, burns the skin, +and devours indiscriminately almost everything it comes in contact with. +Combined with hydrogen, nitrogen forms _ammonia_, which is still often +called by its old name _volatile alkali_; one of the most powerful +bodies in existence, and one for which you would very soon learn to +entertain a proper respect, if somebody were to uncork a bottle of it +under your nose. Finally, nitrogen and carbon combined, produce a quite +foreign substance (_cyanogen_), resembling neither father nor mother in +its actions and powers, to the confusion of all preconceived ideas, when +Gay-Lussac, a Frenchman, introduced it to the world, where it fell like +a bombshell upon the theory of chemical combinations. This impertinent +fellow, combining with hydrogen in his turn, produces _prussic acid_, +the most frightful of poisons; one drop of which placed on the tongue of +a horse strikes it dead as if by lightning. + +You perceive that you must not trust our worthy friend too far. You +have learnt, however, elsewhere, that it is not equally formidable in +all its combinations. Those very substances which, when paired off +into small separate groups, destroy all before them, constitute, all +four together, that precious aliment of nutrition of which we are +formed. Moreover, its real name is "_azotized aliment_" because +it is the presence of nitrogen or azote in it, which, above all, +determines its quality, so that people are in the habit of estimating +the nourishing power of our food by the amount of nitrogen it contains. +In fact, nitrogen seems to be a substance especially inclined towards +everything that has life. His three comrades wander in mighty streams, +so to speak, through every part of creation; but he, except in the +vast domain of the atmosphere, where he reigns in such majestic repose, +is rarely met with, except in animals, or in such portions of plants +as are destined for the support of animal life. + +On this point I will tell you the history of his original name, +_azote_, which you will find curious enough. A short time before +the French Revolution, in 1789, the principal properties of this gas +were made known to the world by a learned Frenchman, who may be almost +considered the father of modern chemistry, and whose name I must beg +you to recollect. [Footnote: Dr. Daniel Rutherford (Edinburgh) +discovered the existence of _Nitrogen_, A. D. 1772; but he never +investigated its character.] He was called _Lavoisier_. While +endeavoring to account satisfactorily for _combustion_, which +before his time people explained any way they could, Lavoisier succeeded +in separating our two friends, the neighbors in the atmosphere, one +from the other, and was the first man in the world who managed to +secure in two bottles--on the one hand, the bubbling oxygen freed from +his tiresome mentor; on the other, the sober *azote, snatched away +from his giddy pupil. What he did with the bottle of oxygen matters +but little to us; but in the bottle of _azote_ he plunged, by way +of experiment, an unfortunate mouse, and subsequently a little bird, +both of whom, finding no oxygen to breathe, died one after the other. +Nothing could live in it, as you may suppose; and Lavoisier thought +it must be right to give so destructive a gas the name of _azote_, +which in Greek means "_opposed to life_." Meantime, science went +on progressing by the gleam of the lamp he had lit, and then followed +the discoveries of his successors, who forced their way into the obscure +laboratory where the elements of living bodies are prepared. And at +last it was ascertained that this _azote_, opposed to life as it +was thought to be, was actually an essential property of life; that +it accompanied it everywhere, and that without it the whole framework +of the animal machine would fall to pieces. It is still known by its +old name, which custom had sanctioned; but I imagine no learned man +can ever utter it now without a feeling of humility, and without the +thought that the future has possibly many contradictions in store for +him also. Besides, nitrogen has to pass through many fine-drawing +processes before it attains that post of honor which has been assigned +to it in the animal kingdom. The animal himself can do nothing with +it, unless it has been previously absorbed and digested by the +vegetable, and the vegetable in its turn could get no good from it, +were it to remain isolated and indifferent in the bosom of the +atmosphere. It is only when it has formed one of those combinations +I have been telling you about, and more particularly the second, which +produces _ammonia_, that it fairly enters upon the round of life. +And then, in the mysterious depths of vegetable existence is organized +that wonderful _quadrille_ of the _aliments of nutrition_, the history +of which has now been sufficiently explained to you. + +The vegetable kingdom, therefore, is simply the great kitchen in which +the dinner of the animal kingdom is being constantly made ready; and +when we eat beef, it is, in fact, the grass which the ox has eaten, +which nourishes us. The animal is only a medium which transmits intact +to us the _albumen_ extracted in his own stomach from the juices +furnished to him in the fields. He is the waiter of the eating-house; +the dishes which he brings us have been given him already cooked in +the kitchen. But to appreciate properly the service he renders us we +must remember that the dishes to be obtained from grass are very, very +small, and that it would be a great fatigue to the stomach if it could +only get at such tiny scraps at a time; as, alas! has sometimes happened +to the famine-stricken poor, who have tried in vain to support life +from the grass in the field. But these minute dishes are brought to +us in the mass whenever we eat beef, and our stomachs benefit +accordingly. Do not forget this, my child; and when mamma asks you to +eat meat, obey her with a good grace; if, that is to say, you wish to +grow up to be a woman. + + + +LETTER XXVIII. + +COMPOSITION OF THE BLOOD. + +One word more before we finish. We must not leave off without bidding +a last farewell to the good servant of whom we have spoken so much; +the model steward so exact in giving back everything he receives--the +factotum of the house in short. We have watched him at work long enough, +but I have not yet described him personally to you, nor told you exactly +what he is composed of. + +And here I shall be obliged to begin again with figures and +calculations, although I am told young people are not very fond of +them. Nevertheless, none of us can manage our affairs properly without +them. Hereafter, when you are at the head of a family, you will be +obliged to practise arithmetic, if you want to know what is going on +in your house. Never allow yourself to look upon what is necessary as +wearisome; the true secret of being punctual in our duties is to throw +our heart and interest into them. + +I choose, therefore, to suppose that you will be interested to know +that 1000 ounces of blood generally contain, (for there are shades of +difference between one sort of blood and another) 870 ounces of the +_serum_ I have been talking about, and 130 ounces of _clot_. At first +sight one would take the quantity of _clot_ to be much greater than it +really is; but in the state you see it, in the basin, it contains a +considerable amount of water, which belongs by right to its companion +_serum_, and which has to be drained away from it before it can be +weighed. + +Now, in our 870 ounces of serum, we shall find, to begin with, 790 of +water; do not be astonished at the quantity. Most of the weight of all +animals is produced by water; they weigh comparatively nothing after +being thoroughly dried in a stove--when they are dead of course--for +neither animal nor plant can live unless saturated with water. This, +by the way, may serve to explain the ease with which we can keep +ourselves floating in water; we are not much more than water ourselves! +Were it not for those abominable bones which are a little bit heavier +than the rest, we should never sink unless a stone were hung round our +necks. + +I repeat then; 790 ounces of water in 870 of _serum_, which leaves 80. +Of this, _albumen_ furnishes seventy, and the ten others, with the +exception of a small portion of fat which floats here and there +ready-made, are _salts_. It would take too long to explain what _salts_ +are here, but there is one sort of salt you know perfectly well; viz., +that which is put on the dinner-table in a salt-cellar. And it is the +most important of all. More than half the ten ounces of salts consist of +it alone, which will make you understand better than before, what I +explained with reference to the stomach; that is, why we put salt in our +food. The porter above is quite up to his business when he asks everyone +who enters to produce his little bit of salt. It is an attention which +the blood appreciates very highly, although table-salt is of no great +use to him in his building operations; but it evidently keeps him in +good humor, and he would work badly without it. It is the same with all +the animals man makes use of, and even the plants he cultivates, find +that salt gives them an appetite. And it would almost seem as if nature +had purposely dealt with us in this matter on a magnificent scale. She +has made salt-magazines of the sea and the bosom of the earth, where it +exists in prodigious masses which cost nothing but the labor of stooping +to pick up, except in countries where a gentleman called a tax-gatherer, +stands by to count the lumps and allow them to pass on by paying a +duty. For my part, if I were the government--this is a secret between +you and me, mind--I would look out for something else to stand in the +place of the salt-tax. It is not well to interpose between man and the +gratuities of Dame Nature, and to make him pay more heavily for the +blood's chosen friend than she meant him to be charged. + +But to proceed, the kitchen-salt being deducted from the ten ounces +of salts-in-general, there remain altogether from four to five ounces, +which contain----. But here I stop, for it puzzles me very much how +to go on! Enough, that to enable you to follow me, you would require +at least as much knowledge of chemistry as will be expected of a young +man who has to pass an examination in medicine. Fancy the contents of +a whole druggist's shop! I will tell you a few names, that you may +have a specimen of the style in use, but I forewarn you that they are +not inviting: _hydrochlorate of ammonia; hydrochlorate of potash; +carbonate of lime; sulphate of potash; phosphate of lime; phosphate +of magnesia; lactate of soda._ I spare you the others, for many +others there are, without counting those which have not yet been +discovered I All these things are to be found, I must tell you, in +fibrine and albumen, but in such minute quantities that it is scarcely +possible to recognize them. + +In the serum, for instance, the gentlemen are so very small, and so +completely entangled one with the other, that it is startling to think +of the skill and patience requisite for making them all out, to say +nothing of affixing the right name--uncouth as it may seem--to each +grain of this almost imperceptible dust! He who first called man an +epitome of creation, scarcely knew how truly he was speaking, for man +bears about in his veins, ascertained samples of at least half the +primitive substances from which all others are made, and if the whole +of them should some day be found to be there, I for one should not be +surprised. + +This is well worth knowing, is it not? and I have not come to the end +of my story yet. + +We have still the 130 ounces of _clot_ to speak about. But their +contents are easily reckoned. Three ounces of fibrine and 127 of +_globules_. + +Here, however, we enter upon such a world of wonders, that I am quite +delighted to be able to finish with it. It will be the masterpiece of +our exhibition! + +You feel quite sure blood is red, do you not? Well! it is no more red +than the water of a stream would be, if you were to fill it with little +red fishes. Suppose the fishes to be very very small, as small as a +grain of sand; and closely crowded together through the whole depth +of the stream: the water would look quite red, would it not? And this +is the way in which blood looks red: only observe one thing; a grain +of sand is a mountain in comparison with the little red fishes in the +blood. If I were to tell you they measured about the 3,200th part of +an inch in diameter, you would not be much the wiser, so I prefer +saying (by way of giving you a more striking idea of their minuteness) +that there would be about a million in such a drop of blood as would +hang on the point of a needle. I say so on the authority of a scientific +Frenchman--M. Bouillet. Not that he ever counted them, as you may +suppose, any more than I have done; but this is as near an approach +as can be made by calculation to the size of those fabulous +blood-fishes, which are the 3,200th part of an inch in diameter. + +These littlest fishes are called _globules_; but they are not +exactly shaped like _little globes_, as the word would lead you +to suppose. They are more like little plates slightly hollowed out on +both sides. The central nucleus is surrounded by a flattened margin +rather bladdery in appearance, of a beautiful red color, formed of a +sort of very soft and very elastic jelly. I scarcely need tell you +that all this was discovered through the microscope, and moreover, by +examining the blood of frogs, in which the globules are much larger +than in ours. [Footnote: Authentic portraits of these globules drawn--so +to speak--by Nature herself, are to be seen on the admirable Photographs +obtained by Bertsch, with the aid of the solar microscope, invented +by himself and Arnaud. There you see them magnified 250,000 times, and +may study them at your ease, and verify my description for yourself +without any fear of being deceived. You must persuade your father to +procure one. This result of photography is among the wonders of modern +science.] + +It was in 1661--rather more than two hundred years ago--that an Italian +and a Dutchman discovered, each by himself in his own country, the +microscopic population of the blood. The name of the Italian is not +very difficult--_Malpighi_. As to the Dutchman's, you must pronounce it +in the best way you can--he was called _Leeuwenhock_. You smile, but he +was nevertheless one of the first men who really comprehended what a +wonderful auxiliary human science had just got hold of in the +microscope, and he has helped to open the eyes of the world to the +marvels of miniature creation. So content yourself, young lady, with +mis-pronouncing his name, and beware of laughing at it! Names are +something like faces, one may live to be ashamed of ridiculing +the wrong one. + +This discovery of the globules of the blood, was destined to throw +great light upon the way in which the _nutrition of the organs_ +was carried on. Modern chemists, who are always fond of investigation, +have examined what they are made of, and can find little else in them +but _albumen_. Out of our 127 ounces of globules, 125 are albumen; +and these, with the 70 ounces which we found before in the serum, make +up the 195 ounces (of albumen) which I told you were contained in the +1,000 ounces of blood. Forgive me all these ounces and figures. Exact +accounts give exact information. + +These globules, then, are composed almost entirely of albumen. Nearly +two-thirds of all the albumen in the blood is concentrated in them; +and you know now the use of albumen, viz., that it is the foundation +of all the buildings of which the blood is the architect. Everything +leads us to believe that the formation of globules in the blood is the +last touch given by nature to that magical provision begun in +thevegetable, continued in the stomach, and finished in the veins, to +which, in combination with carbon, hydrogen, oxygen, and nitrogen, we +are indebted for the subsistence of every portion of our body. Thus +the blood-globules may be considered as albumen which has finished its +education, and is ready to go into the world; while the albumen of the +serum is, like our young friends, the generations in reserve, who are +still at school awaiting their turn. + +This is more than a mere supposition. Scientific men have taken to +themselves, on their own authority, all sorts of rights over animals, +and we profit basely enough by their crimes--I will not withdraw the +word--in order to increase our knowledge. Accordingly, they conceived +the idea of opening the veins of animals, and allowing the blood to +flow until the victim was prostrate and motionless as a corpse. This +done, they proceeded to fill the exhausted veins with blood, similar +to that which had been withdrawn, and with the blood, life was seen +gradually to return, till the animal rose from the ground, walked, and +resumed its disturbed existence, as if nothing had happened. The +interesting part of the experiment to us is, that if serum only, without +globules, be restored to the unfortunate animal, it is of no use +whatever, and the corpse does not revive. + +It is evident, then, that all the power and virtue of the blood lies +in the globules; and according as their number is great or small it +is "rich" or "poor," as it is called; and where their number is not +up to the mark, the blood acts more feebly on the organs, life is +calmer, and people are no longer troubled with emotions--in other +words, with violent heats of the blood. Hence the impassible character +of _lymphatic_ people, who often get on in the struggle of life +better than others, because they are never in a hurry, and know how +to wait for opportunities. You will occasionally hear the word +_lymphatic_, for it has become the fashion, and it is time for +me to explain it; but unluckily the explanation is not in its favor. + +You remember those little scavengers we spoke about formerly, who came +from the depths of all the organs, carrying away with them the worn-out +building materials, and covering the surface of the body with an +inextricable net work of tiny canals. These canals are called +_lymphatic vessels_, in consequence of being filled with a liquid +which is called _lymph_ (_water_, in Latin), but why I cannot +tell you, for it is, in fact, simple _serum_. There was a very +simple way of ascertaining this by making out an inventory of the +contents of the _lymph_ liquid, and when this was done, they were +found to consist of water, albumen, and the salts of serum; there was +even a little fibrine; the only thing wanting was _globules_. + +How the truant serum finds its way into the lymphatic vessels is +probably as follows:--I have already mentioned the inconceivable +delicacy of the capillary vessels, those last ramifications of our +arteries and veins. It needs all the impulsive power of the heart to +enable the blood to force its way through these narrow passages; and +minute as are the globules, it would seem that they have but just room +to pass, for in examining under the microscope a corner of the tongue +of a live frog, the globules have been seen doubling themselves up to +pass through the capillaries, resuming their natural form afterwards. + +It was this, indeed, which made me tell you just now that their margins +were elastic. During this momentary crush, part of the serum being +forced on too fast, oozes through the wall of the over-filled +capillaries, as water oozes through the leathern pipes of a fire-engine, +and hence probably the appearance of serum or _lymph_ in the organs, +where it is immediately sucked up (i. e., _absorbed_) by the lymphatic +vessels. Now, you will easily understand that the larger the proportion +of serum in the blood, the greater will be the quantity to be expelled +in passing through the capillaries, and the more will the lymphatic +vessels swell. In such cases the temperament or constitution is said to +be _lymphatic_. If, on the contrary, the globules are in excess, the +lymphatic vessels receive less serum, and diminish in size. The +temperament is then called _sanguine_, as if there were no serum in the +blood. You shall be judge yourself, knowing what you now do, whether it +would not be more reasonable to call such temperaments _serous_ and +_globulous_. At any rate those names would give people an idea of the +real state of things, and teach them that there were such things as +globules in the blood. + +[Footnote: Here is a summary of the contents of 1000 oz. of blood:-- + + Ounces. + Water................... 790 + Serum. Albumen...................70 870 + Salts.................... 10 + + Fibrine................... 3 + Clot. Globules Albumen.. 125 130 + Coloring matter...... 2 127 + ---- + 1000 + ----] + +To conclude, I must give you an account of the two ounces which still +remain of the 127 of globules, albumen taking up only 125, as you know. +Those two poor little ounces--the remainder of the thousand with which +we started--would you believe it?--they alone have the honor of +conferring upon the blood its beautiful red color. They constitute the +coloring matter of the globules, and you will never guess its chief +element. It is iron; ay, actually iron, young lady--the iron of swords +and bayonets. We often accuse it of tingeing the earth with blood; and +you may now know further, that it reddens blood itself by way of +compensation. Do not trouble yourself as to where it comes from. Our +fields are full of it, our very plants have stores of it. It sometimes +happens that our digestive apparatus, put out of order by other +occupations, fails to make use of the amount of iron offered to it; +in which case the blood is discolored, and the face turns pallid as +wax: this is an illness requiring great care. If it should ever befall +you, you will not be surprised, after to-day's lesson, to hear the +doctor say that you must have some iron. But be easy--you will not +have to swallow it whole! If you will take my advice, you will obey +the doctor's orders as soon as you can. + +Not that looking pale signifies any thing: indeed, some young ladies +think it an advantage. But it is no advantage to any body when the +blood-globules are distressed for want of their proper supply of iron, +and do their work grudgingly, like ill-fed laborers. Nothing can go +on without them, you know, and they are people whom it is not well to +leave too long out of sorts. Else languor comes on; languor which is +the beginning of death: and pray remember that iron, which so often +causes death, is equally useful for keeping it at bay. By sending it +to the discolored globules, you give them back their energy and +brilliancy together. + +I have come here to the end of all that is known with any certainty +about these wonderful globules which are to us the medium of life. +Shall I go further, is the question, and take you with me into the +fields of supposition, so full of noxious weeds? And yet why not? +Science owes its present position to the praiseworthy rule of never +adopting any theory which is not supported by well-established facts; +and I would be the last to advise a change. Were I to tell you, what +I am now going to say to you, at a meeting of the British Association +of Science, they would turn me out of the room, and with very good +reason. Nothing ought to be taught there but what can be proved. But +this is of no consequence to you and me, and we have a right to amuse +ourselves a little, after having worked so hard. + +Well, there is an idea which nothing shall ever drive out of my head, +however imperfectly it may be proved as yet; namely, that each of our +globules is an animated being; and that our life is the mysterious +result of these millions of lesser lives, each of them insignificant +in itself; in the same way that the mighty existence of a nation, is +a compound of crowds of existences, each, for the most part, without +individual importance. Take our own or any other country as an instance; +where millions of brains, many of them by no means first-rate in power, +go to form a national character, the highest (as each _nation_ +is apt to think of itself) in the world. According to this idea, you +must be a sort of nation yourself, my dear child, which is gratifying +to think of on the whole. + +This is much more extraordinary than what I told you some time ago, +of the individual life of the organs, each of which on this new system +would be a province in itself! Do not exclaim too hastily. Whether the +globules are animated or not, it is very certain, let me tell you, +that your life depends entirely upon them; that it is weakened if they +are weakened; that it revives with them; and that whether you attribute +individual life to them or not, makes no alteration in the fact: their +action upon you remains the same. And he must be a very clever man who +can show me the exact difference between action and life. Hereafter, +when we have descended the scale of the animal world together, and are +arrived at the study of what are called microscopic animals, you will +better understand the words which appear so strange to you now. What +little our feeble instruments have revealed to us so far, of the history +of those globules, places them almost on a level with those strange +creatures, inexplicable to us, which are found in innumerable +multitudes, in a variety of liquids. We trace in them the beginning +of organization; their form and size are alike in all individuals of +the same species; and species vary enough to induce one to believe, +that there is a necessary relation between an animal's way of life and +that of its globules. If the microscope has not yet caught them in any +overt living act, who can be surprised? it is only dead blood which +has been submitted to the test. They ought to be observed in the +exercise of their functions, in the living animal itself, as has been +done to some extent in the frog; and if our foolish chat could influence +scientific observers, I would say to them what M. Leverrier said years +ago to the astonished astronomers: "Look yonder; you ought to see a +light there with which you are not yet acquainted!" + +I am carrying you a long way on the wings of my fancy, my dear child; +but have no fears; I will not let you fall. This life of our globules, +which would, after all, be only one mystery the more among many, opens +before our eyes a magnificent vista of the uniformity in the scheme +of creation; which goes on repeating itself, while enlarging its circles +to infinity. We may, all of us, be only so many globules of the great +invisible fabric of humanity, in which we go up and down one after +another; and those vast globes which our telescopes follow through +celestial space, may be but globules of one, as yet unknown, to which +the Almighty alone can give a name. + +Take this page to your father, my dear child, if you do not understand +it rightly; and now, shake hands, my history is ended! + + + +PART SECOND--ANIMALS. + +LETTER XXIX. + +CLASSIFICATION OF ANIMALS. + + +'It is dangerous to show man how much he resembles the beasts, without +at the same time pointing out to him his own greatness. It is also +dangerous to show him his greatness, without pointing out his baseness. +It is more dangerous still to leave him in ignorance of both. But it +is greatly for his advantage to have both set before him.'--_Pensees +de Pascal_. + +The man who wrote that, my dear child, did not trouble himself much +about children. He was one of the gravest specimens of literary +genius--a man who can scarcely be said to have ever been a child +himself; for as the story goes, he was found one day, when only twelve +years old, inventing geometry, and his father only saved him from +trouble, by putting the great book of Euclid into his hands; and, at +sixteen, he wrote a treatise on _Conic Sections_, which was the +wonder of all the learned men of the day. I have not a very clear idea +of what Conic Sections are myself; but I tell you this to show that +Pascal was a very profound and learned man, under whose authority, +therefore, I am very glad to take shelter, now that I am going to set +before you the very startling points of resemblance which exist between +you and the beasts. + +As to your greatness, it delights me to explain it to you. It is not +due to the handsome clothes you wear when you are going out, nor to +the luxurious furniture of mamma's drawing-room, but to the possession +of that young soul which is beginning to dawn within you, as the sun +rises in the morning sky, and pierces through the early mists; in that +growing intelligence which has enabled you to understand so far all +the pretty stories I have told you; in that fresh unsullied conscience, +which congratulates you when you have been good, and reproves you when +you have done wrong: all of them gifts which are not bestowed on the +lower animals, or certainly not to the same extent as upon you--gifts +by which you rise more and more above them, the more they are developed +in yourself. Your baseness--but, begging Pascal's pardon, I cannot +call it baseness--your connecting link with the brute creation lies +in those other gifts of God which you and they share in common--in +those wonders of your organization, which we shall now meet with in +them again, in full perfection at first, and that in every respect; +by which fact you may learn, if you never thought of it before, that +the lower animals come from the same creating hand as yourself, and +ought to be looked upon to some extent as younger brothers, however +distasteful such a notion may seem at first. Societies have been +established of late, both in France and England, for the protection +of animals; and a noble and honorable task they have undertaken, in +spite of the jokes that have been made at their expense. It is a +mischievous cavil to tell people who are doing good in one direction, +that more might have been done somewhere else. Everything hangs together +in the progress of public morality, and you cannot strike a blow at +cruelty to animals without at the same time making a hit at cruelty +to man. And the best argument in favor of the rights of beasts to +protection, will be found in the tour you and I are now going to make +together through the different classes of the animal creation. + +Let us begin with the horse--one of the beasts which oftenest needs +our protection. Give him the mouthful of bread whose history we have +just finished. He accepts it as a treat, and needs no pressing to eat +it. And if it could tell you all its adventures afterwards, you would +find that you were listening to precisely the same story as your own +over again; that nothing was different, nothing wanting. First of +all--teeth to grind it, and a tongue to swallow it with, as a matter +of course. Next a _larynx_, which hides itself to avoid it, and an +oesophagus,* which receives it, just as in your case; a stomach with its +_gastric juices_, the same as yours, in bagpipe form, and its _pylorus_, +like your own; a _lesser intestine_, into which bile pours from a liver +like yours; _chyliferous vessels_ which suck up a milky chyle, as with +you; farther on a _large intestine_; and so on to the end. Nor is this +all:--the horse has also a heart, with its two _ventricles_, and its +double play of valves; a heart which the little girl in our tale might +confidently have exhibited to the engineers as her own, but that it +would have been somewhat too big, of course; into which heart, as into +ours, comes _venous_ blood, to be changed afterwards to _arterial_; in +lungs to which the air keeps rushing, forced thither by the see-saw +action of a _diaphragm_, as faithful a servant to him as to you. +And those lungs like our own, are a charcoal market: the same exchange +takes place there, of carbonic acid for oxygen, as in ours, an +unanswerable proof that the stove inside the horse burns fuel in the +same way as our own: and if you were to place the thermometer inside +his mouth (for we are polite enough to call it his mouth), it would +mark 37 1-2 degrees of heat (centigrade)--a difference from ourselves +not worth mentioning. Finally, if you examine his blood, you will meet +with the same _serum_ and _clot_, the whole company of _hydroclorates, +phosphates, carbonates, &c._, from which we shrank before, and globules +made like your own; having the same construction, and the same life, or +action, if you like it better. I need scarcely add that 100 oz. of its +_fibrine_ and _albumen_ contain: + + Of carbon......... 63 oz. + Of hydrogen........ 7 + +This is understood all along as being the case everywhere, from man +down to the turnip; so that, like you, this noble animal, as the horse +is called, is in point of fact only so much carbon, so much water, and +so much air, joined to a handful of salt, which represents the earth's +share in the bodies of animals. + +You must confess that, if we cannot quite call the horse a +fellow-creature, he is nevertheless very like us. And it is the same +with all those animals which man makes use of as his servants, and +which have really a sort of right to the protection of society, since +they form, to a certain extent, a portion of the human family. I do +not speak here of the dog, who pays his taxes, poor fellow, in his +quality of friend to man. + +When I think of the almost identical organization of man and his +next-door neighbors, I am astonished how it could possibly have come +into the head of a certain learned individual (I will not mention his +name), when drawing up a plan of natural history, to give to man a +separate kingdom, as a sequel to the three kingdoms already +established--the mineral, vegetable, and animal. One might have forgiven +Pascal if such an idea had got into his head after writing his treatise +on Conic Sections; there being nothing in them to throw light on such +a subject. But in a naturalist, an observer who had spent his life in +the study of living creatures, the thing seems almost incredible. +Possibly he had reasons for what he did, but he certainly did not find +them in the subjects of his studies. + +Forgive me, my dear child, for forgetting you in this fit of indignation +upon a point you cannot care much about. It leads me naturally enough +to my present business, which is none of the easiest, but you must +help me by paying attention. I am going to describe the _classification +of the animal kingdom_. + +There are a terrible number of animals, as you know; and if we wish +to study them to any real purpose, we must begin by introducing some +sort of order into the innumerable crowds which throng, pell-mell, +around us for observation. We should otherwise never know where to +begin, or when we had come to an end. + +There are many ways of setting a crowd in order, but they all go upon +the same plan. The individuals composing the crowd are parcelled off +into companies, each company having a distinguishing mark peculiar to +those who compose it. Thus the first division is into a few large +companies, which are afterwards subdivided into smaller ones, and those +into others still less, until the divisions have gone far enough. And +this is what is called a _classification_. + +Let us imagine, as an example, a large crowd in a public garden; I +will soon classify it for you. I shall put the men on one side and the +women on the other. Then--to begin with the women--I shall subdivide +them into married and single. Then among married women I shall make +a company of mammas, and another of those who have no children. Among +the unmarried I shall have a group of those who have never been +married--girls, that is--and another of widows--those who were once +married, but are so no longer. Then, following the girls, I shall +separate them into tall and short. And among the short ones I shall +divide the brunettes from the blondes, and so I shall get at last to +a little blonde girl, whose classification (were she a soldier) in +military rank would be as follows:--_squadron_ of blondes; _company_ of +shorts; _battalion_ of girls; _regiment_ of unmarried women; _division_ +of women. The division of men could be carried out in the same manner; +and thus we should classify our mob into complete military order. This +is easy enough, however; but the classifying of animals is a very +different affair, and I will tell you why. We ourselves require a +classification to study them by, though none was needed for their +creation. The Almighty has formed them all on one uniform plan, around +which He has, if I may so express it, lavished an infinity of +modifications separating species from species, yet without placing +between the different species those fixed barriers which we should +require now to enable us to classify them strictly. You who are learning +the pianoforte have perhaps been told the meaning of a _theme_ of +music--the first idea of the composer who follows it throughout the +piece from one end to the other, embroidering on it, as on a bit of +canvas, a thousand variations melting one into another. Such is pretty +nearly, if we may venture the comparison, the way in which we can +picture to ourselves the Almighty moving through the work of animal +creation. Step in afterwards and divide away into regiments and +battalions, if you please. Nature permits it, but she will never, +to accommodate your classifications, separate what in her is really +united. + +There is still a way, however, and that is to do as I did just now in +the case of the crowd. To take, viz., only one _character_ (as we call a +distinguishing mark in natural history), and to throw together all the +individuals which possess it, the blondes, the shorts, the girls, &c. In +this way it may soon be done; but what is the result? You are in one +class, your eldest sister is in another, your mamma in a third, and your +brother in a different division altogether, a long way from you all. +Such a classification is called _artificial_, and you can see at once +that it is worthless. + +The most natural plan is to put together those that are of the same +family; and the classifications made on this principle are called +_natural_ classifications. + +It is a classification of this sort which has been adopted for the +animal kingdom. People have taken all the animals which possess in +common not one character only, but a collection of characters of the +most important kind, _dominant characters_, as they are called; +and of these animals they have formed, to begin with, large primary +groups; subdividing these afterwards according to the secondary +differences, which distinguish different species in the same group +from each other. + +In this manner all the different sorts of animals are included in +different systematic divisions of one vast whole, through which it is +easy to find one's way, because there is a beginning and an end; and +in which animals of the same family are always grouped side by side. +Were I to mention all the divisions of this immense classification at +once, you would find the account a little long, and not very amusing. +We will go through them by degrees therefore, and, to simplify matters, +will, throughout the whole, only consider those particular characters +which are connected with our special study, the nourishment of life, +that is to say: so that you will always find yourself on well-known +ground. + +I must tell you once for all, however, that it is with this as it is +with grammar. Here and there are--and it cannot be avoided--certain +exceptional cases which keep protesting timidly against the +arbitrariness of rules; but no matter; we must be contented with what +we can get, and be grateful into the bargain to those who have given +us this skillful classification, at once so ingenious and useful, in +spite of its inevitable imperfections. What is impossible is expected +of nobody. You could not understand, even if I wished to explain it +to you, the amount of science, labor and genius requisite for making +out that long list, which, tiresome as it may seem to children, is +absolutely beautiful in the eyes of learned men; too beautiful, perhaps, +and I will tell you why when we have finished. Meantime, as the best +reward we can give to those who have done us some great service is to +teach their names to children, I will tell you, before bidding you +good-bye, to whom we owe this classification, the details of which I +do not enter upon to-day. + +In the first place, we owe the method employed in its establishment, +the method of _natural classification, i.e._, to a learned man +of the last century--a learned Frenchman, Bernard de Jussieu--who tried +it upon plants; another large flock by no means very easy to put in +order, as you may convince yourself any day by studying botany. The +man who applied this system to animals was also a learned Frenchman, +the clearness of the French mind adapting them peculiarly for that +sort of work. And he, too, is one of the glories of that nation. His +labors and discoveries gave a perfectly new impulse to the study of +nature. It was George Cuvier, whose statue you may see at Montbeliard, +if you should ever go there. Not that Cuvier carried through this +gigantic work alone, though the credit of it is justly his due, he +having directed and inspired it. He was assisted by many. But among +his assistants there was one, Laurillard, the most modest, yet the +most active of all, whose name I will mention also, because, like the +others, more or less celebrated, he has never had his reward. [Footnote: +In the earlier editions of this work, there was, in this place, a +severe reproach upon Cuvier for not having given proper credit to +Laurillard. This reproach I have since learned was unjust. M. +Valenciennes himself, one of the most illustrious of the collaborators +of the great Cuvier, has written me a letter in which he defends the +reputation of his friend with a warm indignation which does honor to +both of them; and cites passages in which Cuvier has spoken of +Laurillard, and among others, in the third volume of the _Ossements +Fossiles_, p. 32, ed. of 1822.] + +It only remains for me, therefore, to let the lash, which I was laying +upon the shoulders of another, fall now upon my own, and to deplore +the too great facility with which I had credited, without sufficient +proofs, an assertion which I had otherwise good reason to believe to +be exact--coming to me, as it did, from Montbeliard himself, on the +testimony, it is said, of the family of Laurillard. From this avowal, +a little painful, I confess, my young readers may learn the +inconvenience of rashly condemning others! As I said in the concluding +passage, which truth, only too late, now compels me to suppress--"The +truth is sure to come out at last." + + + +LETTER XXX. + +MAMMALIA. (_Mammals_.) + +Do you remember of my talking of the _vertebral column_ when I was +describing that great artery, the _aorta_, to which it forms a rampart +of defence? I should not have named it without explanation, but that you +had only to pass your hand down your back to find out what it was. Now +the _vertebral column_, or backbone, is one of those _dominant +characters_ which always carries along with it a train of other points +of resemblance in the animals where it is found. It has been chosen, +therefore, as the rallying-point of the first great group. I must tell +you beforehand that there are four of these groups, four large +companies, _i.e._, which naturalists have called by various names; as +Groups, Sections, Primary Divisions and even Branches; in this case +comparing them to four great branches of a tree, going off in different +directions from the same trunk. + +And, first of all, we have to begin with the group of the +_Vertebrata_--vertebrata animals--vertebrata being a word which +explains itself. + +Of course we ourselves belong to this group. In fact, we are at the +head of it; but it descends far below us. It goes on to the frog and +the fish, and includes the monkey, the ox, the fowl and the lizard; +for all these creatures possess the vertebral column. The frog does +not appear to be very much like us at first sight; and yet, by virtue +of its vertebra, it has its points of resemblance to us, which are +worth the trouble of considering. Vertebrated animals are all furnished +with a head, containing a brain, which gives its orders to the whole +body; they have all an internal skeleton, that is to say, a system of +bones linked together, forming a solid base by which all the organs +are supported. I was going to add that they have all four limbs; but +here the serpent glides in to call me to order, and to hiss at our +childish craving for fine-drawn divisions, in perfect order, where +there is an exactly proper place for everything. However, each has, +without exception, a heart, with its network of blood-vessels; red +blood, under its two conditions of arterial and venous; and also a +digestive tube, acting, on the whole, pretty much like our own. I do +not insist, mind, upon this last point, viz., that of the digestive +tube; for we shall see, by-and-by, that it is a character beyond the +pale of the primary groups. It is the fundamental character of the +trunk itself, which necessarily exists, therefore, in all the groups; +and, as I told you in my first letter, you will find it everywhere. + +This is--to let you into the secret at once--the theme on which the +Great Composer has based all His infinite varieties of animal life; +and herein lies the uniformity of the animal creation, that startling +uniformity which has given so much offence to many learned men, and +which is so obvious that it will strike you of itself, I feel sure. +But I reserve this subject to the end of my letters, when you will +have heard all, and be able to judge for yourself. + +It would be plunging back into confusion to attempt to examine all the +vertebrated classes at once. After making a division you must go on. +The groups have, therefore, been subdivided into _five classes_, which +we will study in succession, only naming each now: viz. _mammals_, +_birds_, _reptiles_, _fish_, and _batrachians_. Do not alarm yourself at +this last name: it is a Greek word, meaning simply frogs. + +The mammals are our immediate neighbors. Mammalia are the animals which +produce milk. They bring forth their young alive, and give suck to +them as soon as they are born. This was your first nourishment, my +dear child, so you yourself are a little mammal. + +What I said to you in the last letter about the horse, applies pretty +nearly as well to all mammals. We shall not, therefore, have any great +variations to notice here. Nevertheless, as these are the animals which +interest us most nearly, as they are in fact our nearest of kin, so +to speak, and those with whom we have the most to do, we will now pass +in review the different orders of which their class is composed. I +must explain to you that the _classes_ are subdivided into +_orders_, the orders into _families_, the families into +_genera_, the genera into _species_; as in armies divisions +subdivide into regiments, regiments into battalions, &c. It became +necessary, moreover, to make use of special names, in order to make +these subdivisions comprehensible, and the following are those which +have been adopted. + +ORDER 1. _Bimana (two-handed)_. + +Here we may pass on at once, for we have discussed this order enough +already. We are _bimane_ ourselves, since we have the distinction +of possessing two hands. Yes; that is the pretty title which the +professors have been so polite as to give us, instead of leaving us +simply our proper name of man. Yet it would have been very easy to do +this, seeing that we are the only family, the only genus, and the only +species of the order. In railway travelling, people of distinction +have a reserved carriage to themselves: so we decidedly deserve an +order to ourselves; but that is not quite the same as a separate +kingdom. In short, you are a _bimane_; so make the best you can of it. + +ORDER 2. _Quadrumana (four-handed)_. + +These, as their name indicates, have four hands: two at the end of the +arms, and two at the end of the legs; such are the monkeys. There is +nothing to remark; they are all alike. Stay; I am wrong, though: there +is something, insignificant it is true, but still pointing to deviation. +In some the canine teeth are set forward, _i.e._ project, and are +longer than the rest, and some species, as the ape, for instance, have +just under their cheeks convenient little pockets, which open into the +mouth, and in which they can deposit a reserve of nuts to be devoured +at leisure; these are called _pouches_. + +It is a trifle in itself, but we have here a first example of the +eccentricities of nature in the construction of animals. At one time +she adds a detail; at another she suppresses one. Sometimes she is +pleased to enlarge an organ, as in the canine teeth of the monkey; +sometimes she reduces it; or perhaps here she makes its construction +more simple; there again more complicated: but still it is always the +same organ. So the dressmaker shapes the sleeves of a dress, sometimes +open, sometimes closed, flat or puffed, plain or ornamented, +pagoda-shaped or gigot-formed: but still they are all of them sleeves. + +ORDER 3. _Cheiroptera (wing-handed)_. + +I am quite ashamed of offering you such a word as this, my dear child. +It was a Greek fancy of the learned men, who would not condescend to +use the vulgar name Bats. In the Greek, _cheir_ means hand, and +_pteron_ wing. The Cheiroptera are animals with winged hands; in +fact, the fingers which terminate the fore-limbs of the bat lengthen +as they spread out to an extravagant extent; and are connected together +by a membrane springing from the body, with which they beat the air +as with a wing, and which enables them to fly with such ease that +theyare often taken for birds. + +But, so far from really being a bird, this curious little creature has +the same internal organization as ours, and indeed comes so near us, +though without looking as if it did, that a scientific man, and a very +distinguished one too, placed the bat in the first family of the animal +kingdom, with the monkey, and, you will hardly believe it, with man. +It is found that the bat, like man and the monkey, suckles its young +at the breast; and it was this very character which Linnaeus, the leader +of artificial classification, thought of selecting as the distinguishing +mark of his first family in the animal kingdom. It is true that in +honor of the human race he had given that first family a much more +sonorous name than our usual one of _man_--viz. _primates_, the first in +rank--that is, the princes. But, alas! we were to be princes on an +equality with bats; and, for my own part, I prefer being a _bimane_, and +alone. I really believe that it was to put this saucy little creature +back into its proper place that, at the time of the great revolution in +favor of natural classification, the conclave of professors assembled at +the Botanical Gardens in Paris inflicted this horrid name of Cheiroptera +on the bat, ejecting it contemptuously from the overthrown dynasty of +the _primates_. + +I have not been sorry to make you acquainted as we went along, with +this little trait in the history of classification; but beyond it there +is really nothing particular to say about the apparatus for the +nourishment of the deposed bat-princes, which is a plain proof how +nearly it must be like our own. By-the-by, there is one trifling remark +to be made with regard to her teeth. The bats we have in our country +(France), for there are many varieties of species in the world, live +on insects, which they catch in their flight by night. These insects +are often enveloped in a very hard outer case, which molars like ours +would have some difficulty in chewing properly; consequently the molars +of our little friend are fringed with conical points, and with these +she grinds down her prey without difficulty. + +In America there is a large bat, the vampire, which lives on the blood +of animals, and nature has armed it accordingly. It has at the +extremityof its muzzle two sharp beak-like incisors, like the lancets of +a surgeon. The vampire bat, which roams by night like other bats, goes +straight at the large animals it sees asleep, delicately opens a vein +in the throat without waking them, and sucks their blood in long +draughts, taking care, by fanning them with its wings, to lull them +into a cool and balmy slumber. It does not, as you see, make a savage +attack on its victim: it merely inflicts a bite like that of the leech, +but the result may be death. This is the best emblem I know of the +sycophant, who undermines your soul while he fans your vanity; and +observe, while we are on the subject, that this species has always had +the art of insinuating itself among princes. + +ORDER 4. _Carnivora (flesh-eaters)_. + +When translated into English, this word needs no explanation. And here +we have the tribe of bears, wolves, foxes, weasels, dogs, cats, tigers, +lions, of all the fighting animals, _i.e._, those which steep +their muzzles in blood, and live by devouring others. These have a +similar apparatus for nutrition to our own; especially the bear, who, +with the monkey, is the animal most nearly resembling man, seeing that +he has feet like ours, with scarcely any tail, while the monkey has +our hands, without specifying any other points of resemblance. Like +ourselves, too, the bear is omnivorous; that is to say, it eats +everything, vegetables and fruit as well as meat; and nature, which +has given it our diet, has furnished it with molars almost exactly +like our own. Its canine teeth alone differ from ours: they are more +prominent even than those of the _quadrumana_; and this is the +case with all the members of the order, in whom we find them sometimes +developed into actual daggers. But those of them which are purely +carnivorous have molars peculiar to themselves. The lion, for example, +who does not share the bear's taste for carrots, and who would die of +hunger surrounded by the honey and grapes of which the bear is so +fond--the lion, who never takes anything but raw meat between his +teeth, has molars furnished with sharp cutting edges, intended to slice +the meat like the chopping knives used by cooks for making a hash. + +The lion offers another peculiarity, which is common to him with all +the _Carnivora_. Place your finger close to the lower end of your +ear, and work your jaw; you will feel something hard moving backward +and forward against your finger. This is where the lower jaw is set +into a bone of the skull, called the _temporal_, if you care to know its +name; in other words, the bone of the temple. The extremity of the jaw +bends, and forms a kind of little knob, called _condyle_, which fits +into a cavity of the temporal bone. With us the cavity is not very deep, +nor the knob very large, so that it can play very freely; and it is this +which allows us that second movement from side to side, of which I spoke +to you formerly, and thanks to which, our little mills reduce a mouthful +of bread into paste. But this freedom of action has also its +inconveniences. You must never attempt to force too large an article +into your mouth at once--an apple, for instance--the efforts you would +then be obliged to make might easily cause the _condyle_ to slip out of +its little cavity, where its hold is but slight, and to get under the +_temporal bone_; and there you would be with your mouth wide open until +the doctor arrived. The lion, whose voracious jaw opens like the door of +an oven, so that the tamers of wild beasts have no scruple in thrusting +in their whole heads, a mouthful a good deal larger than an apple; the +lion, who has no doctors, would often be liable to this accident--an +irremediable one in his case--if nature had not made a special provision +for him. In order to secure greater firmness and strength, the second +movement is in his case sacrificed by embedding the _condyles_ +deeply in their cavities, where they are fastened in such a fashion +that they can only move up and down, like the handles of a pair of +pincers. This is a restraint which enables the jaw to be safely thrown +open as wide as the fiery impulse of its terrible proprietor impels +it. Less freedom, in exchange for more power, is a bargain which any +one would gladly accept who plays the part of a lion! + +I have here a remark to make. We have now passed in review three orders +besides our own, and have only had to point out a change in the +fastenings of the jaws and in the teeth; and you will find that the +same sort of modifications take place in the whole class of mammals. +This is in fact the essentially movable and variable point in their +apparatus for nutrition. The jaw and its weapons vary their character +from one species to another, according to the nature of their food; +but the modifications generally terminate there, _i.e._ on the +threshold, as it were. The interior arrangements of the house remain +otherwise much the same in all. + +Here, however, in the lion, there is an interior change to be described; +but not in the arrangement of the parts, only in their size; the stomach +in this species being even smaller and weaker in proportion than ours, +and the digestive tube more than twice as short. The digestive tube +of an ordinary sized man is about seven times the length of his body, +whilst that of the lion only measures three times the length of the +animal. This is a natural consequence of the kind of nourishment he +takes. Flesh and blood, on which he lives entirely, is concentrated +_albumen_, prepared beforehand in the bodies of his victims; so +that no great preparation is needed here to convert it into lion's +blood. A professor of chemistry, who has a good assistant, does not +need a very large laboratory. This is the case with the lion; and +nature, which makes nothing in vain, has here economised space. Tame +the monarch of the forest into a domestic animal, and change his food, +and I will wager anything you please that, in the course of a few +generations, his digestive tube will lengthen itself. Examine the +inside of the cat, his little cousin, formed originally on the same +pattern as himself, and, without having ascertained the fact myself, +I am sure that, by dint of feeding it daily on sops and milk from +generation to generation, its digestive tube has become more than three +times the length of its body. + +Here you ought to be told at once a very important fact relative to +the organization of the lower animals, one which places them all very +far below the order of _Bimana_, since there is such an order. +In bestowing intelligence and freedom of action on man, the Almighty +has given him the unspeakable privilege of working in His footsteps--if +I may presume to use the expression--of following up His work of +creation as it came from His hand. Now especially that man begins to +see a little more clearly into the laws of life, he has entered more +directly into the possession of this almost divine privilege, which +the Almighty has graciously vouchsafed him. You can even now have an +ox or a sheep made to order in England, giving your dimensions, as if +you were ordering a cabinet; and in a few years, if you have not asked +actual impossibilities, your commission will be executed to within an +inch. This is not said in reference to the _Carnivora_. But in +bidding you good-bye, my dear little mammal, I could not bear to leave +you under the weight of that debasing title: I wanted also to show you +your greatness. + + + +LETTER XXXI. + +MAMMALIA. _(Mammals)--continued_. + +Let us continue to pass in review the different orders of the class +Mammalia. We may meet elsewhere with facts more important to science, +but nowhere with any so personally interesting to ourselves. + +ORDER 5. _Insectivora (insect-eaters)_. + +This order devours insects, as their name tells you plainly enough. +They feed in the same manner as the bats; consequently they have molars +like theirs, as was necessary. It is an unimportant little family, and +we will not waste much time upon it. The chief of the order is the +hedgehog, a native of our country--not very large, about nine inches +long--which lives in the woods, and which when rolled up into a ball, +with all its quills standing out, looks very much like an enormous +horse-chestnut in its shell. Its canines have not much work to do, +consequently they are very small; but, on the other hand, its two front +incisors are prolonged beyond the others, the better to seize its prey, +which creeps upon the ground. Internally there is nothing to remark +upon. + +Next to the hedgehog I will mention as a curiosity the shrew or +sand-mouse, which, in spite of its name, is no mouse at all, but has +the honor, if honor it be, of being the smallest animal known of the +class Mammalia. + +It is about two inches in length altogether; and if you carefully +examine its little body, you will find that it contains all the organs +you possess yourself--oesophagus, stomach, liver, intestines, veins, +arteries, heart, lungs--nothing is wanting: the machinery is absolutely +the same. + +ORDER 6. _Rodentia (rodents)_. + +Were we to translate this word into its meaning, namely, the _Gnawers_, +there would be some comfort in it, for we would at once know what it +means: but no matter. Rodents, or Gnawers, are rats, hares, rabbits, +beavers, marmosets, squirrels, in fact all the creatures which _nibble_. +To _nibble_, if you do not exactly understand the word, means to chew +with the points of the teeth. The rodents have no other way of eating +but by filing, if one may so say, their food with the points of two +incisors with which both the jaws are provided; these incisors are very +long, much longer even than those of the hedgehog. The next time you see +a rabbit at table, ask to see the head; and you will find that it has +four pretty little teeth, very sharp, shaped like a joiner's chisel; +that is to say, with a "bevelled edge," to use the received expression; +in other words, with one edge thinner than the other. + +Here, then, we begin to diverge from the old model. First, there is a +different fastening, or _articulation_, as it is called, of the jaw. Its +_condyles_, which we saw just now in the _Carnivora_ enlarged +transversely and deeply embedded in the _fossae_ or cavity of the +temporal bone, extend here longitudinally; an arrangement which enables +the jaw to move backward and forward at pleasure, like the arm of the +locksmith when using the file. Furthermore, those little teeth, which +are constantly rubbing against each other, would be very soon worn out, +if, like our own, they were made once for all; accordingly their germ, +or _pulp_, to use the proper term, instead of perishing, as with us, +when the tooth has once come, retains its life, and works on throughout +the life of the animal. They sometimes say of a man who has not eaten +for a long while, that his teeth have grown long. This is a joke with +us; but in the case of a _rodent_ would be too serious a matter to be a +joke; for, as their incisors are always growing, like our nails, they +would soon become too long if the animal ceased for any length of time +to wear them down by eating. It is for this reason that rats and mice +have such incessant appetites, and that with them "all is fish that +comes to the net;" old books, rags, and even planks of wood, which they +will gnaw for want of something better. Come what may, they must keep up +at an equal rate the wear and tear of the incisors, and the internal +growth of the pulp beneath, which is always pushing the tooth forward. +This dull continuous work might otherwise have a terrible result, which +you would never suspect. It is very disastrous for a young lady to lose +a front tooth, as it is called, for it sadly spoils a pretty face; but +for a _rodent_ such a loss is much worse; in fact, it is a +death-warrant. The corresponding tooth, having no longer anything to rub +against, ceases to wear out; and as it does not stop growing on this +account, it lengthens indefinitely, until at last it pushes out beyond +the mouth, and places itself like a bar between the two Remaining teeth +and the food of the animal, who, poor beast, being unable to eat, +ceases to live. + +The canines, whose duty it is to pierce the food, have, of course, no +use in a jaw that grinds, nor are they to be found there. Between the +incisors and the molars there is a large vacant space, which you will +easily detect if you examine a rabbit's head. + +Finally, animals which can fall back in time of need on a plank for +their dinner, require a very different-sized cooking apparatus to that +of the _Carnivora_. Thus the rat, the most perfect sample of the +rodent order, possesses a digestive tube of a prodigious length, through +which the scrapings of wood have plenty of time for travelling, while +the minute nutritive particles they contain are being thoroughly +disengaged; and as every part of the animal organization tends towards +keeping our insatiable rodents in the constant state of voracity +required by its inexorable pulps, nature has given it an enormous heart +whose size exceeds even that of its stomach. + +Perhaps you do not catch at once the connection which exists between +the size of the heart and of the appetite; yet it is very simple. Large +barrels are requisite for those who brew a great deal of beer, and +large hearts for those who make a great deal of blood. Now, it is the +blood, as you know, which carries heat; in other words, life, throughout +the body; when it pours in in torrents, the fire goes twice as fast, +and, consequently, the feeding must be kept up. A medical friend of +mine told me that he once had some rats sent to him--a boxful in +fact--for one of those scientific experiments which one would venture +to condemn more earnestly if their results were not sometimes +beneficial. Next morning there were only two or three animals to be +found, and these had eaten up the others. See the consequence of having +too much heart! + +ORDER 7. _Pachydermata (thick-skinned)_. + +In Greek _pachus_ means thick, and _derma_ skin. _Pachyderms_, +therefore, are thick-skinned animals. It is rather a vague denomination, +as you perceive, and does not tell us much about them; but it appears +that it was not very easy to find a better term. For my own part I +should be very much puzzled to find a name really suitable for such an +irregular company as this, in which all the huge beasts of the +earth--the elephant, the rhinoceros, the hippopotamus--are heaped one +upon the other, side by side with the horse, the ass, and the hog; +begging your pardon for an ugly word. + +All these creatures live on vegetables, with the exception of the hog, +to whom nothing comes amiss; or who, in other words, is _omnivorous_, +like the bear, and also another member of the class _Mammalia_, which I +do not name for fear of making you blush at your companionship. This +assures you that, in the order of the _Pachydermata_, the digestive +apparatus is very fully developed. The horse, for instance, has a very +voluminous stomach, which extends much farther back than the point at +which the oesophagus empties itself; and in which, on close examination, +a sort of contraction is observed which appears to divide it in half, +producing the false effect of there being two stomachs. But, after all, +we do not find, even in this case, any essential difference to remark +upon in the internal arrangements; it is always the teeth we must look +at if we want to have something to say. There, indeed, we have only to +choose; nature has indulged herself in all manner of fantastic freaks. + +To begin with the elephant, the grand master of the order, he presents +us with one of the most oddly-furnished jaws in existence. Every one +knows those two enormous tusks which protrude from his mouth, and which +furnish human industry with nearly the whole store of ivory it has +need of. Those two teeth are the largest, beyond comparison, of any +in the animal kingdom; yet they are two merely ornamental teeth, +perfectly useless in the operation of eating, and very ruinous into +the bargain to the proprietor. All those stores of the blood which +furnish the materials for ivory pass into these tusks, and, as often +happens to people who give way to a taste for luxuries, there is nothing +left wherewith to provide the animal with serviceable teeth. Those +tusks of the elephant are nothing but his upper incisors, the only +ones, observe, which curve in coming out of his jaw. In the lower jaw +he has no incisors at all; canine teeth are entirely wanting; and by +way of dental apparatus, this meagerly-furnished mouth possesses on +each side of either jaw one or two molars, enormous in size, but not +of ivory. They are composed of a number of enamelled upright layers +of tooth-substance (_dentine_), soldered together with a bony +cement; and these are our giant's only resource for chewing the grass, +young shoots, and leaves of trees, which are his natural food. +[Footnote: These teeth are nevertheless very efficient grindstones.] +As a consolation, he has the glory of knowing that he possesses the +very finest teeth in the world, the terror of all who approach him; +and I can compare him to nothing so well as to a vain woman, who is +contented to live on potatoes that she may wear fine clothes and excite +the envy of her neighbors. + +The hippopotamus also has incisors in the upper jaw, which curve as +they come out of the mouth; but these never attain anything like the +size of the elephant's tusks, neither do they hinder the development +of the other teeth, of which this animal has a very respectable +collection. The upper incisors bend downward; those in the lower jaw +stand out horizontally, and terminate in sharp points like +plough-shares; and indeed the hippopotamus uses them for tearing up +the ground in order to get at the roots which form its nutriment. These +are, besides, formidable weapons, with which when enraged the animal +can tear even boats in pieces; for, as you are aware, the hippopotamus +is almost amphibious, and browses on water-plants, and lives in the +great rivers of Africa, its native country. Its name alone would have +told you this had you understood Greek; [Footnote: _Ippos_, a horse, and +_potamos_, a river. The Greeks, who had seen the hippopotamus in the +Nile, in Egypt, named it the river-horse; as afterwards the Romans +called the elephant the ox of Lucania, because they first saw it in +Lucania during the war with Pyrrhus.] but I have no complaint to make +this time, for it was the Greeks themselves who gave it. You would find +it very awkward, would you not? if you had to breakfast at the bottom of +the Thames, and could not swallow a morsel without having your nose +filled with water? But the hippopotamus labors under no such +inconvenience. Its nostrils are provided with two little doors, which it +closes at will, and behind this screen the lungs keep quite quiet while +the animal goes backwards and forwards in the water. There is generally +a hippopotamus in every large menagerie. The next time you visit one +look at him. You will see him with a large stomach almost trailing on +the ground: and no wonder; he needs plenty of room in which to stow away +all the canes, reeds, and water-plants from the bottoms of rivers, which +are not very nutritious food. Accordingly the stomach of the river-horse +presents the appearance not only of two compartments, like that of the +true horse, but looks as if it were divided into three or four. + +To conclude my account of this animal, I must add that the ivory of +its teeth is even more beautiful than that of the elephant's tusks, +and that dentists carve it into very magnificent teeth for their +patients. This is not a matter to interest you much at present, but +we never know what may happen. I advise you, however, never to make +use of hippopotamus's teeth; they turn yellow very quickly, and, when +people are driven to buy teeth, the least they can try for, is to get +good-looking ones for their money. + +I should like to say something about the rhinoceros while we are on +the colossal tribes, but it is a very unsatisfactory subject. The +animal has no canines, sometimes no incisors even; sometimes it has +as many as thirty-six teeth, according to the species, as naturalists +aver; and this is all I have to say about this great lump of flesh, +so misshapen outside, yet so regularly formed within. He it is who +especially deserves the title _pachydermata_, his skin being so +hard and thick that bullets glance off its surface. But this has nothing +to do with our present subject, any more than the horn upon his nose, +whose turn for description may come if I ever give you the history of +the skin and all connected with it. + +The hog also has canines, and very strong ones; but it is in the wild +state, when it is called a boar, that these appear in their real form. +There we find them projecting out of the mouth with a curve, as is so +commonly seen among the _pachydermata_, forming those terrible, +sharp, and pointed tusks which have been so often fatal to the hunter. +The wild boar of the forest is supposed to be the original ancestor +of the domestic pig; and if, as is probable, this is really the case, +we have here a remarkable instance of the effect of man's treatment +upon the organisation of the animals he collects around him. The wild +boar lives only on fruits and roots, which, like the hippopotamus, he +tears up with his tusks, those safeguards of his, amid the many perils +of his life in the woods. In the service of man, on the contrary, he +becomes lazy, cowardly, and greedy; unlearns his energy and +combativeness, eats all that is offered to him in the trough, even +meat, when it happens to be thrown in; and, in order to do this +moreeasily, has recalled toward his mouth those formidable war-tusks of +his, so tremendous as weapons, so useless as teeth; has, in fact, +turned his sword into a fork. It is the case of a Tartar degenerated +into a Chinaman. [Footnote: China, about which we have heard a great +deal of late years, has been several times invaded by the warrior +hordes of Tartary. But at each time, unto the second and third +generations, the vanquishers have taken the effeminate manners, the +costume and the usages of the vanquished, and so many conquests have +only resulted in converting millions of Tartars into Chinese.] + +This suggests to me an idea relative to the horse, the last important +member of the _pachydermata_ which remains to be spoken of. It +also has its canines, but very small ones; they disappear, so to speak, +in a large vacancy between the incisors and the molars, where man +inserts the bit, by means of which the animal has been subdued. Small +as these are, however, these canines indicate that the horse might eat +flesh, canine teeth being the distinctive attribute of the carnivorous +mammals. I have read somewhere, but I do not remember where, that an +unusual development of strength could be produced in the horse by +feeding it on flesh; and the old Greek poets write of a king [Footnote: +Diomed, King of Thrace] in the barbarous ages who gave his horses, +men for food. If I knew some rich professor who was inclined to spend +money in the investigation of a curious fact, I would advise him to +set apart a sum for putting horses on a meat diet, from sire to son, +gradually increasing the quantity; and I would boldly warrant that in +the course of successive generations the canines would become so large +as to impede the entrance of the bit into the mouth, and, moreover, +would make it rather a ticklish office for the groom to place it there. +But let us set aside the teeth the horse might possibly have, in order +to examine those it has already. There are six incisors in each jaw; +these are long and rather projecting teeth, by examining which, the +age of the horse can be detected from certain marks which appear in +them from year to year. The molars are flat, square, furrowed with +bars of enamel, marking out more or less distinct crescents; perfectly +constructed, in short, for chewing hay and oats. Nevertheless, I should +never be surprised to see the enamel crescents become sharp-cutting +in our rich professor's stable; so skillful is the unseen Architect +who created animals, in altering the house when the tenant changes his +habits. + +ORDER 8. _Ruminantia (ruminants)._ + +I shall retain through life a pleasant recollection of the +_ruminants_. Through them I obtained the first prize for natural +history which was ever given in France to the pupils of the learned +university. It is thirty years ago since this happened, and I own, +without any false modesty, that even now the word _ruminant_ rings +very agreeably in my ear. It reminds me of one of the proudest moments +of my life, of the honor done to me by the illustrious Geoffroy St. +Hilaire, when he called me, a little college urchin, up to him, that +he might have a nearer view, as he said, of the baby-professor who had +spoken so well on ruminants. Yes, it is more than thirty years ago, for +alas! it was in 1831. There needed no less an event, as I have told +you before, than the revolution of 1830 in France to induce the big-wigs +of education to sacrifice two hours per week in one class to the study +of natural history. Yes, my dear child, it is only that short time ago +since natural history became one of the subjects of study in French +colleges; and the gray-haired men of the present day finished their +education, as it is called, without having learnt a single word of +what I am now taking the trouble to teach you, a mere child. You see +you have come into the world just at the right time, and will be able +to instruct others in your turn. But before giving lessons to other +people you must first finish learning your own. Forgive me this +involuntary reference to a happy time when I was not much more rational +than you are. And now, let us return to our ruminants--those dear, +good beasts, the nourishing fathers of the human race. + + + +LETTER XXXII. + +MAMMALIA--_continued_. + +ORDER 8. _Ruminants--continued_. + +Every created thing has an appointed part to perform; but there are +some mysterious parts of which we cannot understand the drift. That +of the ruminants, however, is so clearly marked out, that we detect +it at a glance. + +To qualify myself for supplying your young mind with the food I am +going to offer it to-day, I have been obliged, my dear child, to browse +in a good many books of which you could have understood but little +yourself; and I have been forced to ruminate a long time upon what I +have read, and to digest it slowly in my head, which I may say, without +vanity, is of larger capacity than yours; no great wonder at my age. +Now, if I have succeeded in my undertaking, you will benefit by all +the work which has been going on in my mind for the purpose of feeding +yours without over-fatigue to it; and I shall almost have the right +to say that its nourishment has been derived from me. My lamp could +tell you what it has sometimes cost me to supply a single page which +might instruct, without repelling you. + +Now, this is precisely what the _ruminant_ does. The part he has +to perform is to collect in the meadows a sort of food, which would +disgust less well-organized stomachs than his own, to work it well up +within him, and to give it back in a more palatable and less +indigestible form. The little flesh-eaters (_carnivora_) come +afterwards to the feast, and the feast is himself! + +The whole history, then, of the ruminant is to be read in his stomach. +His real office is to digest, and in fact he devotes the best hours +of his days to the perfecting of that beneficent labor, on which the +life of so many weak stomachs depends. Have you ever amused yourself +by watching a large ox lying down in a meadow? Long after he has +finished grazing, his jaw continues to work, turning round and round +like the grindstone of a painter when he is rubbing down his colors. +Look, and you will see that he will remain there for hours together, +motionless and contemplative, absorbed in this incomprehensible +mastication, rolling about in his throat from time to time some +invisible food. Do not laugh at him, however. As you sec him there he +is performing his part in life, he is _ruminating_. + +To ruminate is to chew over again what has been already swallowed; +and, however droll this may seem to you, it is the business which all +ruminants are born to. You remember the monkey's pouch, which serves +him as a larder, whence he takes out his provisions as he wants to +eat. The ruminant has an immense pouch of the same kind, into which, +while he is grazing, he hastily conveys large masses of half-bitten +grass. You probably think he is eating when he has his head down in +the grass; but you are mistaken. This is only a preparatory work; he +is hastily heaping up in his larder the food he intends to eat +by-and-by; only his larder, instead of being, like the monkey's, in +his cheeks, where, indeed, there would not have been half room enough +for those great bundles he tucks in, is in the middle of his body, +close to the extremity of the oesophagus, whose lower wall, being slit +at that part, becomes an imperfectly secure tube, ready to burst open +under pressure, and allow the food to escape between the edges of the +slit; these, otherwise, remaining naturally closed. As soon as the +large bundles of grass come to this part, they press against the walls +of the tube, which they by this means separate, and fall into the +provision-pouch, which bears the name of paunch, or grass-pocket, in +fact. As soon as the paunch is well filled, and the animal sure of his +dinner, he lies down in some quiet corner, where he proceeds gravely +with the important act, which is the real object of his existence. A +little below the entrance to the paunch, and communicating both with +it and the canal of the oesophagus, is a second receptacle, which old +French naturalists, not being much acquainted with Greek, named the +_cap_, on account of its fancied resemblance to the caps worn on +the head, and which we call 'king's hood' or 'honey-comb bag.' This +second stomach now contracts (at least so it is supposed), and thus +retains, as if with a closed fist, a portion of the grass accumulated +in the paunch: of this it forms a pellet, which it sends back into the +oesophagus, and the oesophagus, by continued contractions from below +upwards, returns it to the mouth, where at last the grassy lump is +chewed in good earnest, and to some purpose. There is no necessity for +hurry; the ruminant has no other business on the face of the earth but +this, and thus hour after hour passes away, the food pellets rising +one after another to the onslaught of the teeth. Nor do they go back +again until they have been reduced by long mastication into an almost +liquid paste, which glides through the oesophagus without forcing open +the slit, and falls straight into a third pouch, called by old Frenchmen +the _leaf_, on account of certain large folds, some what like the leaves +of a book, which line the interior; and known to us as the _manyplies_. +From this stomach, No. 3, this grass-pap passes into a fourth and last +bag, which is the real stomach, and where the final work of digestion is +accomplished. This fourth pouch also has a pretty little name of the +old-fashioned sort, like the three others; it is called the _reed_ or +_rennet-bag_, from the property it possesses, in the calf, of turning +milk into curds: and of his four stomachs this is the only one which the +ruminant makes use of at first. As long as the young animal is nursed by +its mother, the other compartments remain inactive and small in size; +they neither grow nor exercise their functions until it begins to eat +grass. Indeed, they would probably entirely disappear, if any one would +go to the expense of keeping the animal on milk all its life. If it +ceased to have anything to ruminate, nature would certainly lose no time +in relieving it of its useless workshop of rumination. + +As it is right to give every one his due, I will mention that we owe +our accurate knowledge of this simple and ingenious mechanism of +_rumination_ to the labors of Flourens, a scientific Frenchman, +who is still alive, and who has made a great many interesting inquiries +into the subject we are now considering, _i. e._, the life of +animals. He is a very clever man into the bargain--so perfect a master +of his own language, that the French Academy has felt itself justified +in opening its doors to him--an unheard-of honor for a member of the +Academy of Sciences. And yet, in spite of all this, I heartily +congratulate you that the discovery of the _paunch_, the _cap_, the +_leaf_, and the _rennet-bag_, was not delayed for his arrival. He is +just the man who might have been tempted, in his capacity of profound +scholar, to have hunted up for them in the _Jardin des racines grecques_ +[Footnote: Your brother can tell you about the _Jardin des racines +grecques_. It is a charming little book, of which every generation of +collegians has learnt, by heart, the commencement; but I have never +known one, even among the most intrepid, who had ever been to the end of +it.], four magnificent names, which would only have bewildered you. + +Beyond the rennet-bag there is no change of conformation to note, +except that the intestinal tube is naturally much longer than ours, +on account of the difference of food: as a general rule, it is ten or +twelve times the length of the body. The sheep, who is able to pick +up a living in the poorest pastures, is indebted for this inestimable +power, which makes him the special blessing of dry and barren countries, +to a still further peculiarity of organization; with him the intestinal +tube is twenty-eight times the length of the body. + +We have seen among the _Carnivora_, whose jaws have so much work +to do, that the condyles of the jawbone are sunk deeply into the fossa +of the temporal bone. The ruminant, whose peaceful mouth is formed for +contending only with grass, is organized quite differently. + +Here the condyle is flattened, and the fossa of the temporal bone very +shallow, presenting to the condyle an almost flat surface, so that the +jawbone is enabled to revolve with ease for the better mastication of +the pellets of grass. This conformation is also to be seen in the +_pachydermata_ who feed upon vegetables. In the horse, especially, +whose food is almost the same as that of the ox, the _articulation_ +(as this joining of the condyle to the temporal bone is called) of the +jaw, is also nearly identical; and it is the same with the teeth, with +very trifling variations, those of all ruminants are constructed on +the same plan as in the horse. The canines only require a separate +notice. + +But first I must tell you that, by some special privilege, the reason +for which I do not undertake to explain, the order of ruminants is the +only one containing animals with horns on their foreheads. Stags, +goats, reindeer, chamois, gazelles, roebucks, oxen, buffaloes, all the +beasts with horned foreheads, belong to the ruminants. Indeed, this +fact would form a very convenient mark of distinction between them and +other animals, were there not exceptions to it. Some ruminants have +no horns; and then, as if in compensation for the deficiency, we find +them provided with canines in the upper jaw, in addition to those +below. + +The ruminant which has the most beautiful canines is the musk-deer, +a pretty little animal inhabiting the highlands of Central Asia, like +the chamois of the Alps. But now that you know who he is, you will +probably often be tempted to wish he had never existed; for it is from +a small pouch below his belly that people obtain that odious musk of +which Oriental beauties are so fond, and which even certain +strong-nerved ladies of our own country are guilty of using in public, +to the great detriment of general health. But enough of this; our +business is with the canines of the musk-deer. They project with a +descending curve from the upper jaw, and would give the animal the +very false appearance of a small wild boar, but for the great delicacy +of its legs, which are more slender than even those of our roebuck, +to whom, with the exception of the horns, it bears a close resemblance, +as its name implies. + +After the musk-deer comes the large family of camels and llamas, which +represent--the former in Asia and Africa, the latter in America--the +irregular groups of ruminants which have canines instead of horns, and +which seem to be placed as intermediates between true ruminants and +the pachydermata. They form the connecting link between the horse and +the ox, and men prefer employing them as beasts of burden to using +them as butcher's meat; though one could eat them in their own country +with less disgust than Europeans feel in making a meal of horseflesh; +so that they might be a very acceptable resource in many cases. The +real fact is, that ruminants with horns and without upper canines have +more delicate flesh than the others, and seem more especially destined +to be eaten. Yet if one had only to look at the stomach, which is, +after all, the distinctive characteristic of the order, camels and +llamas would stand in the first rank as ruminants. Besides the usual +character of four stomachs, their paunch and honeycomb-bag are furnished +with large cells which act as reservoirs, and fill with water whenever +the animal has the chance of drinking freely, and from whence in time +of drought he draws it up into his mouth and swallows it. This is what +makes the camel so valuable to the wandering tribes in the great deserts +of Africa and Asia. He is the only animal who can pass several days +under the burning sun of Sahara without drinking--or rather without +appearing to do so--for he carries his provision of water concealed +from all eyes in the recesses of his body. I dare say you have often +heard stories of Arabs dying of thirst who have opened the stomachs +of their camels in search of a last draught of water. It must be a +terrible thirst to drive a man to such an extremity; for, as you may +imagine, one could not expect the water there to be either fresh or +clear, to say nothing of the great risk there would generally be of +finding the reservoir empty. Such an extreme is never resorted to till +water has failed for a long time, and all the goatskin bottles have +been emptied; and in such a ease it is but too likely that the camel +has followed his master's example, and emptied his water-skins for his +own use. But this is only half the internal fittings of the "ship of +the desert," as the Arabs call him. In the desert it is often as +difficult to find food as water; and nature has equally provided for +this. The hump you see rising upon the camel's back in your +picture-books is his safeguard against starvation. It is a huge mass +of fat. I need say no more. You will remember Mr. Liebeg's pig, which +lived 160 days upon its own bacon. Without going quite such lengths +as that, the camel can keep up his fire for a long time upon the fuel +which the blood obtains from this blessed hump. Since we are talking +of this animal, and he takes a remarkable place in a history of +nutrition, I ought to tell you that camels are classed into two families +by their hump: there is the camel, properly so called, which has two +humps, and the dromedary, which has but one. This latter did not require +such a supply of provisions as the other, for he is very much swifter +of foot, and consequently his journeys are more speedily performed. + +I have nothing particular to say to you about the other ruminants, in +the matter of their organs of nutrition; but I will not quit the subject +without reminding you of one thing which concerns nutrition, not theirs, +however, but ours. It was by the taming of the domestic ruminants--that +unfailing dinner-material which now follows everywhere at the heels +of his master--that human civilisation began. Before that event, man, +driven to depend for his living upon the hazards of the chase, spent +his whole time in seeking for food, and had none to spare for the +pursuit of any other branch of industry. + +Far as we may ascend in the history of ages we shall find shepherd +races. Beyond them there is no history at all, nor could there be. The +first leisure hours of man, and, consequently, his first efforts in +art and literature, date from the period when the ruminant animals, +those special fabricators of nutritive aliments, were gathered around +mankind, and worked out their destiny under the shadow of his tent, +by his direction, and for his benefit. But all this is so distant from +us now, that it is scarcely worth the trouble of thinking about. The +human race is somewhat like those old people who have lost all +recollection of their childhood; and young people are not required to +know what their elders have forgotten. It is well, however, that they +should not be quite ignorant on the subject. When you hear that the +Society for the Prevention of Cruelty to Animals has taken up the cause +of some barbarously-used ox or sheep, do not turn it into ridicule. +Those humble species have supported ours from the first; and you should +recollect, now and then, that human society made its first step forward +when it began to keep flocks and herds. + + + +LETTER XXXIII. + +MAMMALIA--_continued_. + +We come now to animals less familiar to you, and none of which inhabit +Europe. We shall therefore pass more quickly over them. + +ORDER 9. _Marsupialia (pouched)_. + +_Marsupium_ is Latin for purse, pouch, or pocket. The marsupials +are distinguished from other animals by a pouch which the mother has +under her belly, and in which the little ones take refuge at the +slightest alarm. You would be very much interested with their whole +story; but it has nothing to do with our present subject, which we +should soon lose sight of if we once began to wander away. This order, +so easily distinguished otherwise by that singular pouch, unfortunately +for us, offers nothing new for observation. It includes several species, +differing entirely from one another on the subject of nutrition, and +closely resembling some already described. Some are both carnivorous +and insectivorous, and are therefore armed with powerful canines, and +with molars like those of the hedgehog. Others are herbivorous, like +hares, and have almost the jaws of a rodent. Among the former we have +the opossum, celebrated by Florian in one of his prettiest fables. The +opossum inhabits South America. Charming little marsupials are to be +found in the Molucca Isles, whence come the nutmeg and the clove; these +are very like our squirrels, and live as they do, in trees, hunting +after fruit and insects. But the greatest number of marsupials belong +to Australia, the real native land of the order. They form by far the +larger portion of the mammalia with which that country is enriched; +the most celebrated amongst them being the kangaroo; an animal which +is now becoming common in European menageries, and which, excepting +in the matter of its pouch, is nothing but a magnified rabbit, as tall +as a man, and with a tail almost as long as itself. As a rabbit, you +know what its eating apparatus must be; and some day, no doubt, the +French Acclimatisation Society will enable us to judge of its flavor. +It is a kind of meat very likely to be seen on our dinner-tables +by-and-by; and, as you have plenty of time before you, probably you +may eat of it before you die. + +ORDER 10. _Edentata (toothless)_. + +These come more directly within our limits. They are classed according +to their teeth; yet if their name were to be trusted, they ought to +have no teeth at all. Whereas, alas! almost all of them have some, and +I am heartily ashamed of their scientific designation; but how can we +help it? The only really _Edentata, i. e_. toothless animals, amongst +them are the ant-eaters, who, considering the nature of their food, are +not much in want of teeth. They feed among the ant-hills, whence they +get their name; and as they are a tolerable size (from two to three feet +in length), it would really have been quite a hardship upon them to have +been forced to crunch the ants one by one at every meal. To get on +rapidly they catch them with their tongue; but what a tongue! Imagine a +kind of long earthworm, lodged in a snout which is elongated like a +bird's beak, and has a very small opening at the extremity. The ant +eater inserts this long, string-like tongue into the crowded ranks of +its victims, and, as its surface is glutinous, they stick to it by +hundreds at a time, and are swallowed at one gulp without a chance of +escape. This tongue, perfectly unique in its character, stretches out in +its murderous exertions to nearly three times the length of the animal's +long head. What a distance there seems between such a tongue as this and +your own little doorkeeper! But no wonder: we have now reached the +confines of the kingdom of _Mammalia,_ and the face of nature is +beginning to change. + +The Armadillo, for instance, which comes next to the ant-eater, looks +far more like the tortoise or lizard than its noble mammalian brethren. +It is covered with scales; and, to look at it, you would say it was +a reptile, in spite of its higher internal organization. As for teeth, +it has certainly enough of them to give the lie to its name of +_edentata;_ but they are not very serviceable ones. They are called +molars, however, because they are situated in that part of the mouth +which is always assigned to molars; but they are miserable grindstones, +very unlike any of which we have hitherto treated. They are all of them +flattened cylinders, with no enamel bars to strengthen them; are small +and poor, and are placed at rather wide intervals from one another. The +poor armadillo munches with these, as best he can, slugs, tender roots, +and other prey of the same sort, with which he is obliged to content +himself, and which do not require very formidable tools. + +The most questionable member of this class is the Unau, or Two-toed +Sloth. It only wants incisors to be as toothless as ourselves! and the +first time I saw it I took it for a little bear. It is true I was then +younger than you are now; for the bear, who is one of our nearest +neighbors, ought not to have been confounded with the unhappy being +before us, one of the drudges of the animal creation; though M. de +Blainville (who had not my excuse) proposed placing it still nearer +to us, namely, amongst the _Quadrumana_. Observe that instead of hands +it has at the end of its fore-limbs only two enormously curved claws, +which have somewhat the appearance of a gigantic fork accidentally +twisted. Accordingly its illustrious sponsor offered it to the world as +an _irregular quadrumane_. I believe so, indeed! This _quadrumane_ +without hands--this _edentate_ whose molars are preceded by magnificent +canines--this enigma of nature, created for the confusion and despair of +all classification--does, I must in all humility confess, completely +upset the rule I laid down so stringently when speaking of the horse, as +to the objects for which canine teeth were framed. The canine teeth of +the sloth are more developed than its molars, and yet I cannot tell you +what they are there for at all. It feeds upon the leaves of trees; and +old travellers in South America, where it inhabits, have told us that, +when it has once hoisted itself up a tree, it will strip it to its last +leaf, and afterwards drop to the ground to avoid the trouble of crawling +down. This was what first obtained for it the villanous name of sloth, a +title which is certainly justified by its gait when on the ground; for +it is so ill-made that it cannot stand upright on its legs, but moves +clumsily forward by dragging itself on its elbows. It seems, however, +that when once in a tree it is a different creature altogether, and +can scramble lightly from branch to branch. Moreover, if its claws +cannot reasonably be reckoned as hands, they are at all events excellent +hooks; and when it is springing about thus in the forest, suspended +to the branches by its long arms, one might be tempted, while watching +it from below, to decide in favor of M. de Blainville's opinion. I saw +it originally myself in a cage. + +As to the sloth's relationship to the armadillo, this rests upon a +detail which bears directly upon our subject. The molars in both animals +are cylindrical and smooth, this is a trifle, but what would you have? +The animal had to be classed somehow; since naturalists have not had +the wit to make detached companies, as they do in regiments of soldiers. +ORDER 11. _Amphibia (two-lived)_. + +We are going farther and farther away. Here are animals who are nearly +half fishes (_amphis_, _double_, and _bios_,_life_). The _Amphibia_ have +two lives: one in the water, which is their true life, and where they +are in their element; the other upon land, where they can only crawl; +for their paws, which are but half developed, are destined to perform +the office of fins, and the hinder ones are extended flatly behind them, +and act like a fish's tail. They are divided into two families, the seal +and the walrus. The first feed on fish, and have the same internal +organization as the _Carnivora_, as well as the same dental +conformation. Some species have even exactly thirty-two teeth, as we +have. The jaw of the walrus is the least regular, and the incisors are +generally wanting, especially in the full-grown animal; for it appears +they lose them very young, as you lost your milk teeth, only, unluckily +for the walrus, his never grow again. On the other hand, he has two +canines in his upper jaw, which, next to the elephant's tusks, are the +largest we have yet met with. They are sometimes as much as two feet +long, and incline downwards with a curve, like the two bars of a +pick-axe. They would play the walrus the same trick that the incisors of +rodents are apt to do when they have not work enough to wear them down; +that is, stop up the entrance of its mouth, were it not that the lower +jaw is contracted in front, in order to fit into the space between the +two canines, which thus form a sort of passage in which it manoeuvres +freely. As you may suppose, the walrus cannot insert prey of any great +size into this contracted passage; but that is no matter, as he lives +partly on seaweeds, and partly--indeed principally--on shell-fish; his +molars being specially adapted for breaking shells. They are short +massive cylinders--the upper ones fitting into the lower as a pestle +into a mortar. + +After the walrus comes a strange animal which has been ranked among +Cetaceans (we shall see why presently), but which it would be better +not to separate from the Amphibians, since an Amphibian order has been +made, for it crawls from time to time upon land: this is the Manatee, +or Sea-cow. It comes still nearer a fish than the others. Its forelimbs +are absolute fins, with mere vestiges of nails at their edges; it has +no hind ones, and its body, which is quite cylindrical, ends in a fin +tail in the shape of a shovel. The sea-cow feeds on plants and herbage, +and lives at the mouths of great rivers, going up them occasionally +to great distances, their banks serving it for pasture ground. In some +respects it is half brother to the hippopotamus and the great grass +eating _Pachydermata_, to whom it comes so near in internal +organization, and above all in the structure of its molars, that M. +de Blainville seriously proposed ranking it among the elephants, though +as an _irregular elephant_, as you may suppose. But then Cuvier +had even placed the seal among the _Carnivora_, by the side of +the cat, whose whiskers it possessed, and of the dog, whom it resembled +in the formation of its head. A naturalist's office is sometimes very +perplexing, I assure you; and as we are touching on this subject, I +cannot resist telling you that the sea-cow laid claim to, on so many +sides, had by right a free admission to the celebrated order of +_Primates_, although it looks exactly like a large barrel elongated +at the two ends. It suckles its young at the breast like man and the +monkey; and if Linnaeus flinched from this rather too absurd parentage, +old navigators were less scrupulous. Observing this creature in the +distance, sporting on the waves, the upper part of its body quite out +of the sea, the sailors, whose eye is not of the most refined, and who +have no objections generally to the marvellous, imagined they saw a +new species of human beings; and hence arose those stories of mermaids +and sirens which have been told from the days of Homer downwards, and +the traditions of which have not yet quite died out in seaport towns. +To have been passed from man to the whale, touching the elephant on +the road, is a long way to travel, especially when, after all, one is +only a huge barrel of amphibious fat; and you may judge from this that +it is not always an easy thing to classify animals. + +ORDER 12. _Cetacea (whale-kind)_. + +Cetaceans are whales; and if I had been consulted on the matter, I +should have joined this order and the last together, under whatever +name was thought most appropriate. The passage from the seal to the +whale through the walrus and the sea-cow is an easy and natural one, +the two latter being obviously the connecting links; and in spite of +certain diversities of food, they form in reality one family-party, +as do the marsupials. + +But it is too late in the day to talk of this, my dear child, and you +and I cannot pretend to alter what is taught in the schools. + +But you are astonished, are you not? to hear that the whale is not a +fish: and no wonder. It is with it, however, as with the armadillo; +it is a fish with a higher organisation inside. The interior of this +enormous mass is a faithful reproduction, as a whole, of that of the +shrew-mouse; and when we come to talk of fishes you will have some +faint idea of the prodigious distance which this places between the +whale and his countrymen of the ocean. + +As far as we are concerned, the chief difference is in their way of +breathing. The cetaceans breathe like ourselves, and are obliged to +come to the surface of the water to take air; while fishes have a +special apparatus, which I will explain to you presently, which enables +them to breathe in the water. This is a disadvantage to the cetacean +in his fish life; nevertheless, of all the mammals (as may easily be +imagined) he is the one who can remain longest under the water. With +us, for instance, the best divers one ever heard of, those who go to +the bottom of the sea after the pearl-oyster, can scarcely stay below +longer than two minutes; and even during that short time the veins of +the head become so overcharged with the blood, which cannot return to +the lungs owing to its forced inactivity, that when the diver comes +back to the surface it is by no means unusual to see him streaming +with blood from both nose and ears. The cetaceans remain under water +for half an hour at a time without seeming to suffer in the least; and +Breschet, a clever French naturalist, has given a very satisfactory +explanation of this wonderful faculty. In dissecting a cetacean, he +discovered all along the vertebral column an extensive network of large +veins, which are not found in other mammals, and which seemed designed +to serve as a refuge place for the blood during the time the animal +remains submerged. According to him, this network would act as a +reservoir, to which any overplus in the head or important organs would +flow through vessels communicating therewith, and which might swell +out as it pleased, without any risk to the inert bed of fat against +which it lies. From thence the blood rushes to the lungs, as soon as +the animal's return to the air enables them to play as usual. It must +be admitted, at the same time, that all this involves the necessity +of a much less active life than that of land mammals, that is to say, +a consumption of oxygen much smaller in proportion than theirs; for +were you to be furnished down your back with the finest network +reservoir in the world for venous blood, it would still not enable you +to remain half an hour without breathing. + +There is nothing remarkable in the digestive apparatus of the cetaceans +except about the mouth, which is, as you know, the essentially variable +point among animals. To begin with, the cetacean tongue has the most +original appearance possible. Indeed, it is not a tongue, but a large +carpet, spread over the floor of the animal's mouth, and bears not the +faintest trace of resemblance to that nimble delicate porter, who does +you such good service. Imagine a thick soft lump absolutely crammed +with fat, and completely immovable, because it is glued down along its +whole length to the bottom of the mouth, and you will have a good idea +of this strange tongue, which in the whale, the largest of the +cetaceans, attains to the length of twenty-five feet and the width of +twelve, and of itself alone furnishes the whale-fishers with from five +to six tons of oil. This is a great deal farther from us than even the +long string which serves as a tongue to the ant-eater; and you feel +at once that we are getting among strangers. + +With respect to teeth, I have now a melancholy piece of news to tell +you. We have done with them; we have seen the last of incisors, canines, +and molars, henceforth you will hear no more about those valuable +instruments. The teeth of the cetaceans, with whom this painful +falling-off begins, are no more teeth than his tongue is a tongue. +They are like so many nails set in a row in the jaw, and can only be +of use in retaining prey, not in grinding it; so that of the many +processes your bit of bread has to go through before it becomes a part +of yourself, there is one which is dispensed with here altogether, +namely, mastication. Cetaceans swallow their food without chewing it. + +Besides, they have not got a whole set even of these unmasticating +teeth. Dolphins and porpoises, those faithful companions of the sailor, +around whose vessel they come playing and tumbling in the seas of all +countries, are the only ones who have them in both jaws. And these are +the small fry of the order; they do not usually exceed six or ten feet +in length. + +The Cachalot, or Spermaceti Whale, an enormous cetacean, which rivals +the true whale in size, and whose head alone forms nearly the half of +its body, has teeth in the lower jaw only. This lower jaw, whose two +sides are joined together for half their length (a new deviation, very +unlike anything we have found before), is so little proportioned to +the gigantic head which contains it, that it is almost lost to sight, +and seems like a small plank slipped under a great square block. + +Such as it is, however, it possesses many very respectable teeth, of +which some weigh as much as two pounds; and with these the cachalot, +whose ferocity is tremendous, tears in pieces everything that comes +near it, sometimes even the boats of the fishermen who risk their lives +in the dangerous pursuit of capturing them. By a singular arrangement, +of which this is the only known instance, there is, opposite each of +the cachalot's teeth, a corresponding cavity in the upper jaw, into +which they fit closely, turning the monster's muzzle into the most +formidable pair of pincers to be found in the animal kingdom. Another +curiosity in the order is the tooth of the Narwhal, a modest cetacean, +who is not much more than twenty feet long! + +I speak of _the tooth_, because the creature has commonly but +one; a cylindrical-pointed tooth, spirally furrowed, whose length +varies from six to ten feet, and which comes straight out from the +extreme front of the upper jaw, like a soldier's pike. There are two +sockets at this extremity of the jaw, each furnished with a tooth-germ; +but as a general rule the germ on the left side is the only one which +develops, the other lying asleep in its socket, where it is choked up +and never appears. Behind this long pike, which, like the tusk of the +elephant, attracts to itself all the ivory in the body, lies a +completely unfurnished mouth; so that the owner of this magnificent +weapon, invaluable as a war-tool, but quite inapplicable to the purpose +of supporting life, is obliged to feed on small fishes and +_mollusks_. We have not yet spoken about these latter, but if you +have ever seen slugs and snails you will know what a _mollusk_ is. + +The same wretched food falls to the lot of the whale also, that giant +of the ocean, whose open mouth forms an aperture twenty feet in extent. +Geoffroy St. Hilaire, in his indefatigable endeavors to trace out +points of resemblance connecting together animals the most unlike in +outward appearance, discovered, along the lower jaw of a young whale, +certain traces of teeth, indicating a last effort on the part of nature +to carry out her usual plan in furnishing the jaws of mammals; but, +like the right-hand tooth of the narwhal, these vain attempts soon +disappear, overgrown and lost in the tissue of the bone, so that the +whale offers us a true type of an _edentate_, classable with the +ant-eater, if one dared, and some people have dared, which by this +time will not surprise you. A classifying professor is utterly +merciless, whether he gets hold of the poor beasts by the mouth or by +the paw: they may protest with all the rest of their body against the +peg on which they are hung; so much the worse for them! If one were +to listen to what they have all got to say, it would be impossible to +classify even one. + +To return to the whale. As a compensation for the teeth which she found +herself unable to give him, nature has manufactured on the two sides +of his upper jaw the most extraordinary apparatus without exception +to be found in the mammal mouth. You know what is called the +_whalebone_ used in stay-making, &c. The name is quite correct; +for those little flexible black strips, which support the figure so +nicely, began life in wandering over the polar or Australasian seas, +fastened to the palate of some monstrous whale. + +On the two sides of the upper jaw the membrane which covers the palate +sends out rows of broad, thin, horny plates, which are from eight to +ten feet long (they have sometimes been seen twenty-five feet) in the +centre of each side, but which decrease gradually towards the +extremities. These are plates of whalebone (sometimes called whale's +whiskers), and the industry of man has turned them to a thousand +different uses; and you will open your eyes in astonishment when I +tell you that 800 or 900 of them have been sometimes counted on each +side of one mouth. Think of the number of stays that could be furnished +from the whalebone plates of one whale! It is true, they were not +exactly designed for this purpose originally. At the tips and on the +edges of these plates, the elastic fibres of which they are composed +unravel and peel off, and hang down from the lip like tufts of +horsehair. The Arctic seas, which the whale inhabits, are, like other +seas, full of innumerable troops of various little sea-animals, and +it is these which are destined to the honor of nourishing this gigantic +mass of flesh. When the colossus wishes to take a meal, he stretches +his mouth to its utmost width, and the salt water rushing in as into +a gulf, carries with it the imprudent little fry, who disappear then +and there for ever, being retained by the fringe-like sieve of the +whalebone. But as, in this way of eating, the stomach of the whale, +however large, would be terribly overgorged with water, he is furnished +with another apparatus for preventing the inconvenience. All the +superfluous water is rejected by the _pharynx_, and springs up +in spouts of fifteen or twenty feet high, through the nostrils, +_i.e._ the nasal openings, sometimes called "vents," sometimes +"blow-holes," which are pierced exactly at the top of the head. This +is a peculiarity common to all cetaceans, who have thence received the +name of "blowers," alluding to the powerful blast which is necessary +to send those majestic columns of water into the air; but it takes a +much milder form with the lesser cetaceans, such as dolphins and +porpoises. There is but a slight jet with them: the water escapes +comparatively quite quietly from the nostril-vents, trickling away +down the animal's sides. + +I hope you consider that I have told you something new this time, my +dear child, and that our machine is beginning to change its appearance +very materially. I told you before that we had reached the outskirts +of the mammal kingdom. When we got to the armadillo we were within a +stone's throw of the reptiles, and here, one step more would take us +to the fishes. But we must first consider the birds, who are a very +superior set of animals to either of the latter; and we have accordingly +an order of mammals (Monotremes) which, as you will now find, opens +the road on that side also. + +There are but two sorts, and both of them are natives of Australia, +which is, as you may have heard, the land of the wonderful in natural +history, and their existence was unknown to the learned men of Europe +till within the last sixty years. The most extraordinary of the two +is the _Ornithorhynchus_, or, to translate the hard Greek word +into English, the _Duck-bill_. Its mouth is a true duck's bill, +a downright horny beak, and its short paws sprawling sideways with a +membrane joining the toes together below, and coming a good deal beyond +them in front, seem intermediate between the flippers of the seal and +the webbed feet of a water-bird. The first naturalist who had anything +to do with the ornithorhynchus, Blumenbach the German, who gave it its +pretty name, did not think it was able to suckle its young, so much +did it differ from mammals in some respects, though looking so like +them on the whole. And presently a report arose in the learned world +that the new animal which had been classed at all risks among mammals +(it having the close fur and almost the body of the otter), a report +arose, I say, that this ornithorhynchus of Blumenbach laid eggs like +a real duck. The uproar in the Academies was tremendous. As early as +1829, indeed, a learned Englishman, Sir Everard Home had sent over to +France an authenticated drawing, as he said, of an ornithorhynchian +egg, to the delight of the hunters after analogies among animal races; +while Cuvier looked sadly askance at the intruder, whose arrival threw +his animal outlines into confusion, there being no place in them for +such a beast. Happily for the poor animal, he has ended by almost +settling the matter for himself. The ornithorhynchian egg has never +turned up. But in the animal's nest have been found baby +ornithorhynchuses, newly born, under two inches long (the full-grown +animal being more than a foot and a half), and not a trace of eggshells +near. Further investigations showed that the mother ornithorhynchus +nursed her young with milk, for curdled milk was found in their +stomachs; so the Australian phenomenon has been restored triumphantly +to the Mammalian order, whence Geoffroy St. Hilaire had excluded both +it and its companion, the _echidna_, a sort of hedgehog, provided +like the ornithorhynchus with a bird-like bill, only more of the +canary-bird sort; and like it, also, approximating to the bird tribe +by other details which do not belong to our subject. And so the matter +stands at present; and all we venture to say is that classification +had a very lucky escape. + +And now, my dear child, that I have made you acquainted in detail with +your nearest neighbors, the last of whom, nevertheless, are strangely +unlike you outside, however they may resemble you within, I shall take +the liberty of going more quickly over the ground, and shall point out +in the mass only the more important changes which lead from one class +of animals to another. I should be found fault with if I tried to make +you too learned, and you yourself might be tempted to tell me, to my +sorrow, that you had heard about enough. + + + +LETTER XXXIV. + +AVES. (_Birds._) + +Tell me, my dear child, when you have seen birds taking their flight +into the air, and going boldly to their object, without a thought of +all the barriers, ditches, rivers, and mountains, which hinder man at +every step in his travels, did it never strike you to wish for their +wings, and imagine how you would fly off if you had them? If you ever +dreamt this dream, do not apologise for it; it is one as old as the +world. 'Oh that I had wings like a dove!' cried the Prophet, nearly +3,000 years ago; and the dialogue of the swallow and the prisoner, so +often sung by poets, has been repeated in prose behind all the +prison-bars on the globe since prisons were first invented. + +Now you will not think it kind on my part, but I must undeceive you +about this fancy, as you will be undeceived some day about many others. +The wings of a dove or swallow would be of no use to you if you had +them, any more than the formidable swords of the middle ages would be +to our modern gentlemen, were any one to put such into their hands. +We are not adapted for them, nor they for us. + +You saw, some time ago, what an amount of muscular exertion was required +for running--what a violent flow of blood, what hurried play of the +lungs. Now in flying it is still worse; for the earth, at any rate, +holds us up quite naturally, whereas the air will not hold up the bird +unless it is beaten vigorously and unremittingly by an untiring wing. +If we men, constructed as we are, had to do such work, we should be +out of breath at once; the heart would cry out immediately for quarter, +and the diaphragm turn red with anger. And only just imagine in what +a critical position a poor wretch launched into the air on the wings +of a swallow would find himself when, at the end of five minutes, his +servants should refuse point-blank to go on working at a height of 500 +feet above the ground! + +But a bird has not these internal rebellions to fear. In the first +place, it has no diaphragm; so here is another friend to whom we must +say good-bye. We shall not meet with him again anywhere. The journey +we are taking together, my dear, is somewhat like the journey of life. +One sets off, surrounded by friends and acquaintances, but whoever +travels on to the end is apt to find himself alone at last; this is +what is happening to the digestive tube, which we shall see losing all +its accessories, one by one, as we gradually advance in our study. +Even now here is one essential fundamental difference in the internal +machinery. The body has only one compartment instead of two; and the +lungs, masters of the whole space, extend freely to its utmost depths. +When a fowl is cut up at table, look along the body, and you will find +lodged in the cavity of the ribs, a long, blackish, and spongy mass: +this is the lungs. There is not, therefore, the same danger of a bird's +getting out of breath as with us; that delicate board which is found +in our bellows is wanting in his. His is set in action solely by the +to-and-fro movement of the ribs, which is produced by muscular +exertions, which are greatly increased during the action of the wings. +From which it follows, that the rapidity of flight itself regulates +the arrival of air, and consequently the expenditure of strength, or, +if you like better, the activity of the fire, since the energy of the +muscles depends, as we have seen, upon the quantity of oxygen that +feeds the internal stove. + +This is not all. These elongated lungs are still not sufficient to +furnish the blood with all the oxygen demanded by this excessive labor +of flight. They are pierced with holes, through which issue pipes which +carry the air all over the body. You know what is said of +spendthrifts?-that they burn the candle at both ends. It is so with +the blood of birds. That fillip which in our case it receives in the +lungs, and which sends it back full of vigor into the arteries, is +repeated in the bird at the other end of the arteries as well. The +capillaries, those delicate vessels at the end of the arteries, plunge +from all sides into little reservoirs of air-lungs, therefore-where +the blood renews its provision of oxygen, and relights its +half-extinguished fire, so that it sends the combustion afresh into +the muscles on its return back to the heart, and sets them going a +second time. + +The natural consequence of this prodigality of combustion is, that +there must be, in proportion, much more oxygen in birds than in us; +and that of all animals a bird is the one most quickly poisoned by his +own carbonic acid when the air is not renewed around him. Therefore, +let me beg you never to think of putting a poor little bird under a +wine-glass, as a child of my acquaintance once did, that she might +examine her little friend more closely. In the twinkling of an eye he +would consume all the oxygen inside his prison, and you would soon see +him fall upon his side and die. + +On the other hand, the temperature of these flying machines, which +consume so much oxygen, is very much higher than ours. It rises to +41 deg., 42 deg. (centigrade), and sometimes to 44 deg., 7 deg. higher than with us. +If ever you have taken hold of a little bird, you will have remarked +how warm it makes your hand: this is quite natural, since there is +always a double fire going on within him, to meet the extraordinary +expenditure of strength that is required of him whenever he takes wing. +Besides, do but look at the poor little creature when you have +imprisoned it in a cage! How it goes up! How it comes down! How it +hops from one perch to another, with a quick sudden movement, like +that of a spring when it unbends. There is no apparent cause for this +state of continual agitation; and yet there is a cause, and only too +serious a one. Its fire is not slackened because you have put it into +a cage, and its muscles, lashed furiously on by the double-oxygenized +blood, drive it hap-hazard into a thousand movements, in which it +expends, as best it can, a superabundance of power, which no longer +finds natural employment. Little children, who are the real +singing-birds of our homes, and whose blood also drives much more +energetically along than ours--little children I say--often fare no +better than caged birds in those larger cages we call schools; and +schoolmasters and governesses would scold rather less if they thought +rather more about this. It is right, I do not deny it, that the +rebellious young rogues should be taught in good time not to abandon +themselves, like wild birds, to the mere animal impulses of the blood: +but, in dealing with them, one must also make allowances, as they say, +for the fire within, and know how to open the cage now and then. It +is not for you, however, that I say this, young lady: you are no longer +a little child; but it may happen that you may have some to take care +of some day. Believe me, then, you must not expect too much wisdom +from them, and you must allow them to change their perch every now and +then. It is a law of our Almighty Father that little children, and +little birds, should not stay too long in one place. + +The mechanism of the circulation is here the same as with us, and does +not offer any important peculiarity. Only the left ventricle of the +heart has walls of extreme thickness, which enable it to launch the +blood into the members with greater vigor and rapidity; and the blood +itself, although it is composed of precisely the same materials as +that of the mammals, differs from it nevertheless as regards the +globules. In the first place, they are more numerous; secondly, they +are larger; and finally, instead of being round like a plate, they are +drawn out ovally, and are almost shaped like those long dishes on which +fish is usually served. I shall not attempt to give you the reason of +their size and form. This is hidden from us in the same mystery which +envelopes all the microscopic population of the blood; but is it not +a curious thing, this strange persistency of form in the globules ofall +animals of one class? In all birds they are oval; in all mammals +they are round. In all? Nay, I am wrong. As if the better to hide from +us the key to this riddle, nature has amused herself by making an +exception. Camels and llamas, I forgot to tell you, have also globules +in the form of long dishes, like the hen and the chaffinch. Find out +why, if you can. As to the reason of the number, it is a very simple +one. Since the energy of the blood resides in the globules, it follows +that the most energetic blood will contain the largest amount of +globules. Looking at you, for instance, little monkey, running and +jumping about the garden, I would lay a wager, without counting first, +that there are, in one drop of your blood, some millions more globules +than in one of mine. + +Let us now go on to the digestion, with which, properly, we ought to +have begun; but I preferred pointing out to you, first, the particular +character which is the chief mark of distinction in the organization +of the bird. + +'When hens grow teeth,' says a shrewd proverb, meaning of course, +_never_. Birds have no teeth, and in this respect there is no +variety among them. All, from the first to the last, have uniformly +the same tool to eat with--the bill, that is--which is, in all cases, +composed of the same elements, two jawbones elongated to a point, and +clothed in a horny armour, which makes their edges sharp and cutting. +At the same time were we to review the birds in detail, as we have +done the mammals, you would see that there are almost more modifications +to be observed in this one single instrument than in our thirty-two +teeth. All birds have a beak, but each has his own, organized expressly +with reference to the kind of food needed by its owner. The eagle's +beak, which mangles living prey, is pointed, bent, and hard as steel; +the bill of the duck, which laps up water from ponds and puddles, in +order to get worms and half-decomposed refuse out of it, is soft, and +flattened like a shovel. The woodpecker's, which has to pierce the +trunks of trees, is like a pickaxe; that of the humming-bird, which +has to suck up the juice of flowers from the bottom of their corollas, +is slender as a needle. The swallow feeds on flies, which it snaps up +on the wing, and has a soft bill, which opens like a little oven. The +stork picks up reptiles in the mud of the marshes; its beak is +straight-pointed, cutting as a knife, and resembles a long pair of +pincers. The sparrow feeds especially on hard grains, difficult to +break; accordingly its beak is stumpy, short, and thick, and is arched +on the upper side for still further solidity. But I should never end +if I began to enumerate all the thousand varieties in the bills of +birds. Each variety, too, corresponds with some peculiar sort of life, +and consequently with a general conformation (easily ascertained) of +the animal in which it appears. Give a naturalist the bill of a +bird--only its bill remember--and he will tell you half its history +without fear of being mistaken. + +On the other hand, we must not deceive ourselves as to the real value +of this complaisant bill. Let it transform itself as it pleases into +all manner of forms for the better fulfilment of its task, it makes, +at the best, but a very poor instrument for mastication; nay, to say +the truth, it breaks, cuts, and tears, but it never masticates at all. +Thus the bird's mouthful is far from undergoing as perfect a preparation +as ours does. It is no sooner taken in than it is swallowed, and the +salivary glands, which are still to be found under the tongue, seem +only to be there as a matter of form; what little saliva they produce +is thick and sticky, and has none of the qualities necessary for making +that liquid paste which our tongue sweeps up from every corner of the +mouth. Besides, it must be owned that a bird's tongue would be a very +awkward implement in such a task. Open a hen's bill and you will see +therein a very inferior sort of porter. It is merely a dry hard lance, +as it were, armed with prickles at the point, as ill-qualified for +tasting as for sweeping. So the hen does not waste her time in finding +out the flavor of what is thrown to her. She picks up and swallows +over and over again, without appearing to experience any other pleasure +than that of satisfying her appetite. Birds of prey, it is true, have +rather more convenient tongues, capable, moreover, of tasting up to +a certain point; and the parrot, who is a complete epicure, and chews +his food philosophically, has a charming-little black one, thick, +fleshy, and susceptible--a true porter, in fact-who enables Polly +thoroughly to enjoy her breakfast. But certain birds who live on insects +surpass even the hen in the dryness and hardness of their tongues. +That of the woodpecker, especially, is a model of the kind, and deserves +a few words more than the others. Picture to yourselves a long pin, +terminated by an iron point with barbs like those of fish-hooks. An +ingenious mechanism enables the bird to dart it out with the rapidity +of lightning, far beyond his bill, upon the insects to which he gives +chase. The point pierces them, and the hooks retain them, without any +need of assistance from the bill. I have just told you that this bill +pierces the bark of trees; but it only plays the part of gamekeepers +on grand sporting occasions, who beat the bushes to make the game rise. +The woodpecker's bill routs up the insects by destroying their shelter; +but the real sportsman is the tongue. Good-bye to any notion of a cosy +little chat in such a porter's lodge as that! What could a harpoon +have to say for itself? + +Do not, however, let this miserable entrance-hall alarm you, at the +same time, for the fate of the mouthful thus presented half-dressed +to the oesophagus. You will find it only so much the better treated +within. In the first place, the oesophagus, when half-way down to the +stomach, swells out suddenly and forms a pocket, which is generally +particularly well developed in birds who feed on grain; this is called +the _crop_ in English, in French _jabot_; whence comes the application +of that word to those full shirt-frills which have sometimes been the +fashion. It is the pigeon's _crop_ that gives him the rounded chest over +which he bridles so prettily. The crop is a receptacle where the food +makes a halt: it is something between the pouch of the monkey and the +paunch of the ox; a preparatory stomach, which does not, it is true, +send back the grain to the bill, for the bill could do it no good, but +in which that grain lies until there is room for it further on. + +Prom thence it resumes its journey; but, before reaching the true +stomach, it passes through a second enlargement of the oesophagus, +whose walls are pitted with numberless little cavities, from which +pour over it the juices destined to supply the place of the saliva +that was wanting above. + +It reaches its destination at last, but still hard, and generally +whole. No matter, however. The stomach which receives it, and which +is called the gizzard, is quite a different sort of thing from a useless +membrane, thin and delicate like ours. It is a thick muscle of enormous +power, lined inside with a kind of horny skin, so tough that nothing +can break through it. You may form some idea of the prodigious strength +of this organ, when I tell you that turkey-fowls have been made to +swallow hollow balls of glass, so thick as not to break when dropped +to the ground, and that at the end of a few days they have been found +reduced almost to powder in the uninjured stomach. No fear of +indigestion with such an apparatus as that. Though the grain may not +have been masticated in the bill, what does it signify? There is a +power here, as you see, quite equal to carrying the whole work through. +Thanks, indeed, to the invaluable horn which lines it, fowls which +have no teeth of their own can safely present themselves with as many +and as hard ones as they please. They swallow small pebbles, which rub +against the grain, during the contractions of the gizzard, and act +just as effectually as if they were fixed in the jawbone. Well, this +terrible gizzard performs its crushing work with such energy, that not +only the grain but the pebbles themselves are ground down there, and +end by being pounded into fine sand. When you rear fowls, do not forget, +if you keep them shut up, to put within their reach a store of small +pebbles, so that they may have teeth to run to in time of need. + +You remember the _pylorus_--the porter down below, who keeps the +door of egress from our stomach? He is as badly provided for here as +his fellow-workmen up above; worse in fact. It is a gaping hole, and +we cannot expect a very strict supervision from it. Birds who feed on +fruits profit by this fact to carry vegetables from one country to +another. With such an easy opening, seeds have a good many chances of +passing from the stomach unaltered; and then they drop from the clouds, +as is supposed, hap-hazard, and germinate afterwards, when circumstances +prove favorable, to grow up before the astonished eyes of the natives +into plants of which they have never even heard. The French +Acclimatization Society, which I spoke of lately, and which, though +so modern, has correspondents all over the globe, is at this moment +laboring to effect an exchange between all countries of the natural +productions of their soil. But here you see that nature had thought +of this before, and established her acclimatization society long ago. + +To complete the internal work of digestion, so feebly begun in the +bill, an extremely large liver pours torrents of bile into the duodenum, +and the manufacture of chyle proceeds with that wild rapidity which +characterizes all the living actions of birds. But speaking of this +liver, I think I ought to give you an account of a celebrated dish, +considered a great dainty by epicures, called _pates de foies +gras_--_fat liver patties_, to translate it into its meaning. +Very likely you will not care to eat them after hearing my story; but +that will be no great loss to you, for it is a very indigestible sort +of food, and not at all good for children. + +You remember my telling you about Englishmen going to India and coming +back with a liver-complaint, from having eaten and drunk more than the +climate allowed? By an imitation of this process, human +ingenuity--occasionally so cruel--has created the _pates de foies +gras_, the glory of Strasburg. I have been in the country, and can +tell you how it is managed. They shut a goose up in a square box, where +there is just room for his body. They open his bill at feeding-time, +and cram down with the finger as much food as can be got in. This is +throttling rather than feeding it. The poor beast, who can use no +resistance, since it cannot move, and who is kept in the dark to prevent +excitement; the poor beast is quite unable to burn all the mass of +combustibles with which the blood soon finds itself loaded. This carries +them to the liver to be turned into bile; but the liver is not equal +to the work, becomes loaded in its turn by unemployed materials, and +grows and grows, till at last, having filled up all the space around +it, it stops the play of the heart and lungs. When the animal is +nearly suffocated they kill it; and this is how we come to have _pates +de foies gras_ to eat! If they give us a fit of indigestion +afterwards, it is a vengeance we richly deserve. At Toulouse, where +the same trade is carried on on a large scale, they used formerly to +go even beyond this. They fastened the goose by the feet before the +fire-place, after having put out its eyes. The imitation of the +Englishman's proceeding was still more perfect here, for the fire acted +the part of the Indian sun to perfection. I do not know that part of +the country well enough to tell you whether they have quite given up +this piece of wicked ingenuity; all I can say is, I devoutly hope so. + +The intestine of birds is much shorter than that of mammals. Here +everything is done at full gallop, and the chyle has not to go far +before it is absorbed. I have before me a book, in which I am told +that the wagtails eaten in France can be fattened in twenty-four hours, +if you only know how to set about it, and these birds are not rare; +they belong to the same family as the red-breasts, the tomtits, and +the nightingale. Thrushes and wheatears (ortolans) require, for the +same purpose, four or five days in the same country, left to themselves +to roam about, when the vine keeps open table for them. + +This incredible quickness, not only in digesting, but, what is much +more, in transforming food into fresh living material +(_assimilating_ it, as it is called), has often a fatal result +for the bird. He is prohibited from fasting; his life is a fire of +straw, which must be replenished unceasingly, or it will die out in +the twinkling of an eye. Our own little birds--children--eat oftener +than grown-up people, and if by any accident they are kept waiting +awhile, they soon cry out with hunger. You know this, do you not? Well, +then, if any one should give you a bird to keep in a cage, remember +that you have undertaken a great responsibility, and that it will not +do to be careless with him. To neglect feeding him for one day is to +run the risk of finding him starved to death next morning. With this +warning, I will conclude my chapter on birds. I hope I have not spoken +in vain in behalf of those poor little captive songsters, whose fragile +lives are at the mercy of their young masters and mistresses. + + + +LETTER XXXV. + +REPTILIA. (_Reptiles_.) + +Passing from birds to reptiles is like falling from a torrent into +still water. Life drags on as sluggishly with the second as it dashes +furiously forward with the first. + +I spoke to you just now about a fire of straw: now we have a fire such +as Frenchwomen make in their _chaufferettes_, or foot-stoves. A +handful of charcoal-dust, and a few live embers between two layers of +ashes, is enough for the whole day; which is economical, is it not? +but then it throws out only just warmth enough to keep one's feet +comfortable. And so it is with reptiles. They live at very small +expense. If you feed them once a month they will not complain, for so +slow a fire does not often need replenishing with combustibles. It is +even said that the experiment has been carried so far with tortoises +that they have been made to fast for more than a year, and still the +charcoal fire kept up its languid pace. Of course, on the other hand, +there is not nearly so much oxygen consumed at once upon such a diet +as this. Where a bird would perish twenty times over in five minutes +for want of oxygen, a lizard can remain whole hours with impunity. +Moreover, the animal heat of reptiles is in proportion to their +expenditure of it. Graceful as is the snake (that living jewel so often +copied by bracelet-makers), you feel on touching it an instinctive +horror, caused by the thrill of cold it produces. All the animals we +have considered hitherto have warm blood, and bear within themselves +the source of their heat, which is pretty nearly always the same. But +reptiles are cold-blooded, and heat comes to them chiefly from without. + +If, at the end of a cold winter, we go to some favorable corner to +catch the first rays of spring sunshine, we feel ourselves almost +re-born, as it were, as if a new life had come into us with the +sunbeams. Look at the little lizard you see frisking on the white +stones of the wall; upon him decidedly the sun is darting actual life +from its rays. While the cold lasted he staid squatting in his +hiding-place--not asleep, but annihilated--congealed, so to speak, +like water caught by the frost; no longer digesting, and hardly +breathing, he had ceased to live in reality: and it is no imaginary +regeneration which the return of warmth brings to him. Like those +helpless people who have not the power to carve out their own destinies, +reptiles have within them only an insufficient source of animation; +their life is at the mercy of the sun, and is high or low, according +as that rises or sets in the heavens. At Martinique, where at noonday +it darts its devouring rays perpendicularly upon the cane-fields, and +every one flies into the shade to escape its scorching heat, the +rattlesnake traverses the country, monarch of all he surveys; he strikes +rapidly with a vigorous tail upon the calcined ground; and woe then +to any one who receives his bite! All the fire of the atmosphere has +passed into his frame. Now go to the Zoological Gardens, and see him +there: he crawls languidly under the coverings that shelter him; if +by chance he bites any one, it is with an idle tooth that no longer +knows how to kill; his life was left behind with the sun of the tropics, +and it is little more than a corpse that you are looking at. + +And so among ourselves, my dear child: we meet with people whose whole +power comes from without, who are brilliant and haughty in the sunshine +of good fortune, but crest-fallen, cowardly, and cringing in the cold +days of adversity. Nevertheless, they are constituted originally like +other people: they are neither greater fools as a general rule, nor +less gifted than their neighbors; where they fail is in the heart, but +that is enough to spoil everything. And so with reptiles: the heart +is their weak point also. Like us, they have lungs into which the air +pours without any difficulty, and a heart to send the blood to them; +so it seems at first sight as if there could be nothing to prevent +their resisting the changes of external temperature just as well as +ourselves. There is only one small trifle wanting, and that is a +partition in the middle of the heart; but this one defect is enough +to disorder the whole machinery. + +You know that, with us, the heart is divided into two compartments: +the right ventricle, which receives the venous blood from the organs +and sends it to the lungs; the left ventricle, which receives it (now +become arterial) from the lungs and returns it to the organs. Hence +the double system of veins and arteries, the one going from the heart +to the lungs, the other from the heart to the organs. All this is found +the same in reptiles: except that the partition, which separates our +two ventricles from each other, does not exist in them; and the heart +has only one common room, in which, therefore, arterial and venous +blood become mixed together. It follows from this that, at each +contraction of the heart, it is a mixture of arterial and venous blood +which is sent in the two opposite directions at the same time, and +that the organs receive some which has been used before, while the +lungs have some returned to them which has been regenerated already. +Now, on the one hand, this mixed blood can only keep up an imperfect +combustion in the body (like the live embers between two layers of +ashes that we spoke of lately), and, on the other hand, the air in the +lungs can only act upon a part of the blood it meets with there, the +rest having already undergone the regenerating process. And this +accounts for both the feeble animal heat and the small consumption of +oxygen in reptiles. + +Added to which the lungs of a reptile are coarsely constructed, and +composed of cells enormous in comparison with ours, so that the blood +does not find nearly as many little chambers to rush into for a taste +of air as with us. Moreover, you must understand that there is no such +thing as a diaphragm here: the lungs float loosely in the form of +elongated bags in the one only cavity of the body, and the slight +movement of the ribs does not allow them to dilate sufficiently to +take in much air at a time. + +All these things, taken together, make the reptile a very poor stove, +and render him incapable of any prolonged exertion. The serpent darts +like an arrow upon his prey; but he could not pursue it for half a +mile without stopping, not even over the burning soil of the equator. +The lizard is very nimble, is it not? and the quickness of its movements +rather reminds one of the agility of a bird. But watch it, and you +will see it only moves in jerks, and keeps stopping every minute; it +cannot escape you if there is no hole near into which it can disappear. +In France there is a large green lizard that runs among the vine trees. +If you pursue him he is off like lightning for a second; then he stops +suddenly short. You return to the charge, and he starts afresh, but +only to stop again. At the fourth or fifth attack he is quite out of +breath; you poke him with the stick with which you have been hunting +him, but in vain; there he lies motionless, in spite of his alarm. A +few steps have brought him to the end of his powers, like a man whose +heart is diseased and who cannot go far. This, however, is a peculiarity +common to all reptiles. Each of the three orders of which this third +class of Vertebrata is composed has its own particular history besides. +You must excuse my mentioning the barbarous names that have been given +them, and allow me to call them _tortoises_, _lizards_, and _serpents_, +like other people. The hard names mean no more than these; but they are +Greek, which is always more imposing. + +The slowness of the tortoise has passed into a proverb, which is not +to be wondered at; for they cannot inhale the air, because their ribs +(which are a reptile's only resource for breathing) are condemned to +absolute immobility. The _carapace_, or shell, which the tortoise +carries on his back, and under which it retreats upon the least alarm, +as under a shield, is really formed of its ribs, each of which has +widened itself so as to join on to its neighbor, like the boards of +an inlaid floor, which run one into another. Of course there is no +question of moving up and down with such ribs, and the poor bellows +cannot work at all. How does the tortoise get out of this difficulty +then, you will ask? I answer, it swallows air, as we should swallow +a glass of water. You see its mouth open and then shut again, thereby +taking in an actual mouthful of air, which the sides of the mouth, by +contracting themselves, send straight to the lungs. These, which are +very large, get filled in this way by degrees, and, when they are quite +inflated, they expel the overplus by collapsing, like an over-stretched +spring. You may imagine that this does not produce a very active +respiration, and that a tortoise would be puzzled to run at even a +moderate trot. To be sure, when he has once filled his great lungs +with air, he has enough for a long time. Most tortoises are aquatic, +and, as divers, leave the cetaceans far behind. Mery, an obscure French +naturalist of the days of the Empire, pretended that he had kept in +his house, _for a month_, some tortoises, whose breathing he had +completely stopped. Only imagine from this how far their life must be +below ours, although it is the result of similar actions, performed by +organs which after all are copies (imperfect ones, it is true) of our +own. + +Some tortoises feed on vegetable substances, and some upon fish or +small soft-bodied animals. Like birds, they mash their food with +difficulty, by means of a real bill. Their jawbones are generally +arched forward toward the front, and are furnished with sharp horny +plates, in which a fairly-marked denticulation or notching may sometimes +be traced, as in the bills of birds of prey. Indeed there is one, the +_caretta_, whose hooked and notched beak so completely recalls +the warlike bill of a hawk, that it is usually known by the name of +the "Hawk's-bill Turtle." You ought to know about this tortoise, for +it is the one which furnishes tortoise-shell, that nice material which +is so smooth to the touch, so pretty to look at, and so very fragile, +that it seems only fit for the use of ladies' hands. I could hardly +speak of tortoises without saying something of this one, out of +whose back was carved the handle of your own pretty little penknife. + +Behind this bill of the hawk's-bill there is a tongue, but of the +character of a whale's tongue, and it is fastened underneath to the +bottom of the mouth. At the base of it there is a sort of fleshy pad +or cushion, which serves instead of a soft palate, that being another +detail which is about to disappear from our history. We are now really +entering upon the simplification of the digestive tube, which will, +I forewarn you, end by being nothing more than a perfectly straight +pipe, without any appendages whatever. In tortoises the intestine is +still tolerably long, and is doubled up backwards and forwards many +times in the abdomen; but it is already beginning to lose that variety +of form which its different parts assumed in the higher animals. The +large intestine can no longer be clearly distinguished from the smaller +one, nor this from the stomach, which itself seems to be a continuation +of the oesophagus, without any very distinct boundary line between them. +The porter, who with us keeps the door of the stomach, does his duty +here so badly, that there are certain kinds of tortoises whose +oesophagus is covered with spines, the points inclined backward, to +prevent the food from rising up into the mouth whilst the oesophagus is +driving it down by its contractions. + +In the gray lizards of our walls we find teeth again, but very different +from any that we have hitherto seen. In the first place, they are not +content with their usual place on the edge of the jaws, but encroach +upon the surface of the palate, where they stretch out in close lines. +Besides, they are even still less like teeth than the great nails in +the jaws of the cetaceans. They are little ivory prongs, with the +points turned inwards, analogous to the thorns of the oesophagus in the +tortoise, and serve the lizard solely to retain and bruise his prey. +He lives on insects, especially flies, which he seizes on the wing +with the greatest skill, hastily catching and engulphing them in his +open jaw; they pierce themselves on the little prongs, and are swallowed +promiscuously. The tongue of the lizard has also a curious peculiarity, +which is shared by that of the serpent: it is divided at the end into +two threads, which dart in and out of its mouth, and by means of which +it laps, like a dog, the few drops of water it requires to satisfy its +thirst. I have seen lizards which had been tamed by children greedily +sucking up the saliva from their lips by drawing across them those +little forked tongues of theirs, which, after all, are very soft, and +perfectly inoffensive. + +The tongue of the chameleon, another species of lizard, is still more +curious. You must know that the chameleon is a lumbering lazy animal, +who feeds on flies and other swift insects, and who would, therefore, +be constantly liable to go without his dinner but that his tongue +serves him for a hunting weapon, like those of the wood-pecker and the +ant-eater. When at rest, it is an oval spongy mass, lying comfortably +in the mouth, with nothing formidable in its appearance; but let the +prey come frisking round the chameleon, as if despising so helpless +an enemy, and this great soft tongue is transformed into an active +dart. It shoots forth like an arrow, and will sometimes seize the rash +intruder at half a foot's distance, transferring it with equal rapidity +to the motionless mouth. The blow is so soon struck, that it is very +difficult to see how it all happens. Some say that the chameleon curves +the tip of his tongue by a sudden effort, and then catches his flies +with it, just as you would catch them with your hand. Others maintain +(and this is the general opinion) that the tongue of the chameleon is +terminated by a sort of sticky cushion, on which the flies are caught, +like birds with birdlime. This singular dart is always out-jerked with +such force that, if it strikes against a glass (the experiment has +been tried with chameleons in captivity), it makes a sound as loud as +that of a pea from a pea-shooter; so you may judge if it is not strong +enough to stun a fly. Besides this, too, the chameleon (who is +by-the-by, a hideous little beast) has given endless trouble to +naturalists on another and very different point. It is he who is +so celebrated for his faculty of changing color when any emotion +agitates him; and ever since the days of Aristotle, who lived more than +two thousand years ago, people have been trying to explain this, without +any one being able to flatter himself that he has found out the exact +answer to the riddle. + +But there is a lizard more interesting still, and that is the crocodile. +He stands alone among reptiles. His heart has two ventricles, and you +would think that he ought to be included in the class of warm-blooded +animals. But, no. The separation of the two kinds of blood takes place +in the heart, it is true, and it is really true arterial blood which +the aorta carries away from the left ventricle. But the right ventricle +has two doors of exit. One communicates with the lungs, the other with +the aorta; and the latter has hardly performed its distribution in the +upper part of the body when it meets, as it descends, with a treacherous +tube bringing to it a current of venous blood. In this way only half +the blood that comes from the veins passes on to be regenerated by +contact with the air, and all the hinder part of the body receives +nothing but the mixed blood common to reptiles, while the head and +fore members enjoy the privilege of the superior orders. After this +go and lay down your laws of classification! Nature, while maintaining +amongst all animals the same principle of life--the regeneration of +the blood by oxygen--has in their construction followed many systems +leading to the same result by different combinations, and which seem +to permit the establishment of essential distinctions among them. Here +is an animal who, if I may so express myself, is climbing up from one +system to the other, and you would have to cut him in two before you +could classify him properly, since his fore-quarters have risen to the +warm-blooded animals, while his hind ones are left behind among the +cold-blooded reptiles! + +But there is something which even outdoes this. + +On dry land the crocodile is timid, faltering, a bad walker, incapable +of regular combat, and a man can manage him with a stick. One feels +that he is betrayed by the hinder half of his body, through which +circulates the only half-oxygenized blood. But when once he has plunged +into the water his whole behavior suddenly alters; he is a ferocious +being, high-mettled, indomitable, a savage enemy, redoubling his +exertions, as if the entire mass of his blood had suddenly become +arterial. Geoffroy St. Hilaire, who followed Bonaparte as a scientific +explorer when he set out for the conquest of Egypt, the country of +crocodiles, was deeply struck by studying on the spot this double life, +which seems in a way to maintain two beings in the same body. He +afterwards gave an extremely curious explanation of it in his work on +the crocodiles of Egypt. Here it is; but I forewarn you that you will +not understand it: + +"The crocodile, when it is under water, receives by two canals into +the cavity of the abdomen, a considerable quantity of water, which the +animal can renew at will." + +You are not much the wiser, are you? But wait a moment. We are soon +coming to the fishes, and you will then see what an unlimited scope +nature has allowed herself here. Not satisfied with two systems in one +animal, she appears to have got hold of three. + +If we continue the examination of this privileged reptile, we shall +find many other infractions of the usual rules of his class. His tongue, +certainly, is fastened to his mouth like that of the tortoise, so much +so that the ancient Egyptians told the Greeks he had not got one; but +his set of teeth clearly approach those of the lower mammals. You have +probably heard a great deal of the strength of the crocodile's +formidable teeth. Travellers have given them this reputation; but we +have nothing to do with that now. They stand in battle array, in a +single line, along the whole length of the jaws, into which they are +sunk with genuine fangs, whilst the prongs of our little lizard are +merely fastened to the surface of the bones which support them. Indeed, +in one way, the crocodile is even better provided than the mammals. +He possesses under each tooth one or two germs, the life of which lasts +as long as that of the animal, and which are always there ready +toreplace the previous one should it chance to fall out. There are many +ladies, and (not to be rude) gentlemen as well, who would, I am sure, +give a great deal to have as many teeth at their service. Indeed, they +may possibly think Dame Nature very unjust to have selected this great +villanous beast rather than us as the object of a gift which they would +have been so well able to appreciate. But we must not blame nature too +quickly: she had her reasons. We, during our infancy, have teeth in +reserve. Now, a reptile may be considered as an imperfect rough draft +of a mammal; and the crocodile gives one thoroughly the idea of a +mammal half-finished and fixed for life in a state of childhood. I am +sorry that I cannot enter into full details, that you might see how +far the idea is a just one. Moreover, in his character of a perpetual +child, he is always growing bigger all his life long, and never seems +able to die but by accident, hardly ever, I may really say, from old +age. By specimens kept in captivity, it has been ascertained that +their growth is very slow. Well, imagine their being only from seven +to eight inches long when they come out of the shell, and that +full-grown crocodiles have been found thirty feet in length, and +calculate accordingly. You will not account for it under a century; +and I should like to know what would become of this venerable child +of more than a hundred years old if kind Mother Nature had not left +him our system of milk-teeth to the end? + +A curious peculiarity of these persistent teeth is, that they are +hollow inside, so much so, that the bowls of tobacco-pipes are said +to be made from them in Europe. I mention the fact, although of no +great interest to you, for the benefit of any pipe-merchants who have +not yet thought of sending for such things to Cairo. + +But let us return to the efforts perceptible in the organization of +the crocodile to raise itself to a higher level. The soft palate, as +we called it (Letter VII.), is wanting in other reptiles; but here +there is one which completely closes the entrance of the windpipe (the +larynx). I announced, too, the disappearance of the diaphragm; and we +bewailed together the loss of that servant of the good old times, whose +touching history you must, I am sure, remember. But I reckoned without +this wretched crocodile, who seems determined to give the lie to all +we have been saying. He has a diaphragm, and one which acts well enough +in the main, although it is pierced right through the middle, as if +it were rather ashamed of being there, and wished to make up for +dividing the body into two compartments, against all proper reptile +regulations, by opening a door of communication between them. What +shall I tell you besides? The lungs, not to be behind the rest of this +aristocratic reptile's organization, are hollowed into cells much more +complicated than those of his fellows. You find here no end of nooks +and corners, which multiply opportunities of contact between the air +and the blood, and so give the crocodile almost the respiration of the +mammals, as he has already got pretty nearly their system of +circulation. + +With serpents, again, we fall very low. When we were speaking of the +tortoises I told you that, in proportion as we come down in the scale, +the digestive tube has a tendency to get rid of its accessories, and +to assume the appearance of a perfectly straight tube. If any one were +to cut open a serpent before you, you would see this final condition +almost reached already. In the first place, the soft palate is entirely +suppressed, and the mouth extends straight into the oesophagus, whose +tube seems to run through the whole length of the body without +interruption, with just four or five doublings towards the base, in +that part which represents the intestines. An imperceptible swelling +indicates the place where the real stomach lies within; but in another +sense one may call the oesophagus, and I might almost add the mouth +itself, its stomach. You shall see how. + +The jaws of serpents are even in a more unfinished state than those +of other reptiles. Nature has not taken the time to weld the different +parts of them together; but these begin by not being very firmly joined, +remember, in young mammals. The bones of the head, which support the +jaws, are themselves movable, and can be detached from the skull if +necessary, so as to allow the throat to open extraordinarily wide; +thus it is not uncommon to see a serpent swallow animals much larger +than itself. You will be horrified when I tell you that the anaconda, +one of the giants of the family, swallows large quadrupeds at a single +mouthful. What are our mouthfuls in comparison with his? however, it +must be confessed, that his often take several days to go down. When +the animal has rolled up his prey in his terrible folds, he pounds and +kneads it till it is reduced to a kind of long roll, which he moistens +with a copious slaver to make it slip down more easily. Then, attacking +it at one end, he fastens this very expansive jaw upon it, and the +gigantic mouthful slowly begins its journey; what was left outside the +mouth, advancing little by little, in proportion as the digestion +reduces what has entered to pulp, and sends it farther down. This is +on great occasions; but in the case of more modest prey--a rabbit, for +instance--the mouthful goes in whole at one gulp and remains stationary, +partly in the oesophagus, partly in the stomach, while the powerful +juices distilled by the walls of the latter are dissolving it. + +You can see that a soft palate would have been quite useless here, and +that the serpent has not much need of teeth to chew his food. +Accordingly, his are nothing but simple prongs, like those of the +lizard, and, like his, they extend over the palate, the more effectually +to cut off the return of the swallowed masses of food. About a hundred +and twenty have been counted in the throat of the boa-constrictor; but +their number varies considerably in the different species. They are +not organs of the highest order, and nature is not very particular +about the quantity. + +There is only one tooth among serpents of which she takes any particular +care, and that is the venomous tooth which she has bestowed on certain +species, and which serves them for striking down, as it were, the +animals on which they feed. Let us study it in the rattlesnake, the +most celebrated of this odious race. On each side of the upper jaw you +may see, isolated from the others, and exceeding them all in length, +a very sharp fang pierced through by a tiny canal, which opens into +a gland placed at the root of the tooth. The bone which supports this +little apparatus is very flexible, and when at rest, the fang, falling +back, hides itself in a fold of the gum. When the animal wishes to +bite, it springs up again, and the gland, compressed by the action of +biting, sends into the little canal a jet of poison, which runs through +it into the wound. As far as can be ascertained, this poison paralyses +the victim and disorders the blood, which at once loses its power, +and no longer acts upon the organs as before; still it is only injurious +when it has been carried by the current of circulation into the mass +of the blood; if swallowed, it has no effect whatever on the stomach. +Now do not look at me with such incredulous eyes, as if it were quite +impossible any one should think of swallowing such a thing. You have +no idea what a scientific man is capable of when he comes to close +quarters with nature, for the purpose of extracting one of her secrets. +He has his own fields of battle, where very often as much courage is +displayed as on any other. + +These two fangs, in which lie all the power of the animal, are of the +greatest importance to him, and their want of solidity makes them +liable to remain in the wounds which they have made. In consequence +of this, they enjoy the same privilege as the teeth of the crocodile, +and in a still greater degree even. Behind each poison fang lie in +wait, not one nor two, but several sentinel germs, ready at the first +alarm of a loss to set to work and re-supply the disarmed serpent with +his venomous needle. So the serpent also lives in a state of perpetual +childhood: he is always growing; and I could not tell you the exact +natural limits of his life any more than of that of the crocodile. +They are gentlemen who do not allow themselves to be very closely +studied in a state of freedom. But these also grow very slowly, and +some have been met with whose size had extended quite enormously from +their first start. I ought to tell you, once for all, that this +indefinite growth, joined to extreme longevity, is found in many of +the inferior species whom we have yet to consider. It seems the portion +of these unfinished creatures, in which nature has only as it were +sketched in her work, and who seem vowed to endless youth, in testimony +of the state of childhood they represent, a state transitory among the +superior animals, but permanent with them. It belonged of right, +therefore, to the serpent, which is the most unfinished animal we have +yet met with, and who, at the first glance, seems almost reduced to +a mere digestive tube, lodged between a vertebral column and a series +of small ribs, whose number sometimes reaches three hundred. The liver, +which, with us, presents such a distinct and bulky mass, is here +elongated into a thin cord, which runs the whole length of the +oesophagus +and intestine, to the walls of which it is, to some extent, attached. + +It is the same with the lungs. There is rarely room for the full +development of two in this narrow conduit, where everything has to +follow the shape of the master of the house: one, therefore, is often +merely indicated by a very slight protuberance; the other, presenting +the appearance of a long tube, which extends nearly half-way down the +body, and whose feeble action halts periodically at each of those +monstrous repasts, after which the torpid animal becomes nothing but +a huge digesting machine. We have now reached the extreme limits of +that organization, the most perfect model of which we find in man, and +which is no longer to be recognized in fishes. + + + +LETTER XXXVI. + +PISCES. (_Fishes._) + +We are becoming terribly learned, my poor child, and I am half afraid +you will be getting tired of me. When I was little myself, I had rather +a fancy for breaking open those barking pasteboard dogs you know so +well; to see what was inside them. Why should you not, then, feel a +certain amount of interest in looking with me into the insides of real +animals? Still I cannot conceal from myself that the subject grows +very serious at last, and that while I am busied in struggling to make +myself intelligible through the endless crowd of facts which surround +me, I am apt to neglect chatting with you as we go along. Happily, +however, here is an opportunity for so doing. + +Up to the present time we have lived, as it were, upon the explanations +I gave you whilst studying the action of life in yourself, and all the +organs we have met with since, have been only, properly speaking, +reproductions, more or less exact, of those which you yourself possess. +But, in passing over into the kingdom of fishes, we find ourselves in +the presence of something altogether new, and I must go back to our +old familiar style of talking to open the subject. + +Take a water-bottle half-filled with water, and shake it well, and you +will see a quantity of white froth come to the surface of the liquid. +This is the air which having been drawn in by the water, as it went +up and down in the bottle, is now struggling to fly off again in bubbles +as fast as it can. But the whole of it does not get away; a small +portion remains behind, and melts, as it were, into the water, as a +morsel of sugar would do, taking up its abode therein. This seems odd +to you, but I will tell you how you may convince yourself of the fact. +Get a small white glass bottle, slightly rounded, and thin at the +bottom, if possible; fill it with water, and hold it for a short time +over a lighted taper. If you do this carefully there is no danger. You +will soon see tiny little balls, looking like drops of silver, rise +from the bottom of the bottle, come up to the surface, and burst. This +is the air which was installed in the water, as I described above, and +which is now running away from the heat of the candle, as the +inhabitants run away from a house on fire. After a time the whole will +have passed off, and the little balls will cease to rise. + +But what has all this to do with fishes? you ask. + +A very great deal, I assure you, dear child. If there had been a little +fish in your bottle, before it was exposed to the flame, it would have +found means to make use of that air, whose original presence in the +water you cannot refuse to believe after having seen it come out. It +is with this air that fishes breathe in the water. They do so rather +feebly, I admit; but, as if to make up to them for the small amount +of the air placed at their disposal, it contains more oxygen than that +we breathe ourselves, because oxygen, dissolving more readily in water +than nitrogen, is there in greater proportion. Of course, you do not +suppose that fishes have lungs like ours? I dare say you know the two +large openings on each side of their head, called _gills_, by which the +fishermen string them together to carry them away more easily? It is +there you will find their lungs, to which the name of _branchiae_, or +gills, has been given, because they are so different from other organs +of respiration that it was impossible to use one word for the two. The +arrangement of the gills varies considerably in the different species, +but their general form is the same everywhere. They are composed of a +number of plates, consisting of an infinitude of leaflets, arranged like +a fringe, and suspended by bony arches, into which plates and leaflets +the blood pours from a thousand invisible canals. + +First of all, then, we must see how blood circulates in fishes. + +Like reptiles, their heart has only one ventricle, and yet the arterial +and venous blood go each its separate way without the slightest risk +of being mixed; but this is because fishes have not that double system +of veins and arteries which hitherto we have always met with. The +venous blood goes to the heart, which drives it into the gills, from +whence it passes forward of its own accord, as arterial blood into the +organs, under the remote influence of the original impetus from the +heart, the newly-arrived blood incessantly driving the other before +it into the vessels of circulation. It does not flow very quickly, as +you may suppose; and as the heart is close to the head, its action is +but very feebly felt at the extremity of the body, when this happens +to be very long. Nature has, in consequence, taken pity on the eel, +whose tail is so far from its heart, and provided accordingly. Dr. +Marshall Hall has discovered near the tip a second, reinforcing heart, +so to speak, which has its own pulsations, independent of the pulsations +of the one above, and gives a fresh impetus to the sluggish blood, +[Footnote: Many observers refer this to the lymphatic system.--TR.] +which otherwise, as it would seem, would scarcely be able to accomplish +the long return journey. Finally, even with an additional heart in +thetail, the circulation among fishes is quite on a par with their +respiration. They have a melancholy steward, whose legs are very heavy, +and his pockets very light, and their life comes down a peg lower in +consequence. It is always the same life nevertheless--you must never +lose sight of that fact: it gets low in consequence of the imperfection +of the machine, but without changing its nature, any more than the +light in our different sorts of lighting apparatus. You remember that +comparison of the lamp with which I began my story, and which you could +not at the time see the full value of? From a dungeon lamp up to a +candle, you have always grease burning in the air at the end of the +threads of a wick. It does not burn equally well everywhere, and does +not always give the same amount of light; but that is all the +difference. From the mammal to the fish, it is always hydrogen and +carbon (as we have said of the grease) which oxygen sets on fire in +the human body at the fine-drawn extremities of the blood-vessels; +only the fire is lower in some than others, and the life with it. Let +us now look at the circulation of water in the fish's body. + +The gills communicate with the mouth by a sort of grating, formed by +the bony arches to which the gill-plates are suspended. The fish begins +by swallowing water, which then passes through the grating and +circulates round the innumerable leaflets of which each plate is +composed, and among which creep the blood-vessels. It is through the +thin coats of these leaflets that the mysterious exchange is made of +the unemployed oxygen in the water and the carbonic acid in the blood. +When this is over, the cover which closes the gills opens to let out +the water, and a fresh gulp takes its place; and so on continually. +When the fish is out of the water its gills fall together and dry up; +the course of the blood, already so weak, is interrupted by the breaking +down and shrinking of the vessels, and the animal can no longer breathe; +so that we have here the curious instance of a creature breathing +oxygen like ourselves, who is drowned, if we may use the expression, +in the air in which we find life, and lives in the water in which we +are drowned. While he is in the water matters take another course, and +his gills, moistened and supported, accommodate themselves perfectly +to the contact of the air, which desires nothing better than to give +up its oxygen to the blood, through the coats of the capillaries. +Accordingly you will often see fishes--carps, for example--come to +the surface of the water to inhale the air like a mammal or a reptile. +This is a valuable resource, which supplements the parsimonious +allowance of air given out to them by the water. There are even certain +fishes whose gills, more firmly closed than those of others, have, in +addition, a number of cells, which retain for a considerable time a +sufficient quantity of water to preserve the gills in their natural +state. These fishes can easily take an airing on land, where they +breathe the air as you or I do, and are downright amphibians. + +The most celebrated of these is the _Anabas_, or "climbing-fish." +an Indian fish, which not only can remain many days out of the water, +but also amuses itself by climbing up the palm trees--it is hard to +say how--and establishing itself in the little pools of water left by +the rain at the roots of the leaves. But we need not go to India to +find those wandering fishes. There is one of them living among ourselves +who can walk about in the grass, and I was talking to you about him +only just now--that is the eel. If you ever put eels in a fish-pond +you must, I assure you, try to make it agreeable to them, otherwise +they will have no scruple in setting politeness at defiance and moving +off to seek their fortune elsewhere. In a country walk, when the dew +is on the ground, you yourself may chance to come across one or two +of these gentlemen, who have had their reasons for changing their +residence, and whom you will see gliding so briskly along that they +will deceive you into taking them for snakes if you have not a very +experienced eye; so much so, that in certain parts of France where the +peasants ate snakes formerly, they reconciled themselves to the sickly +idea by christening them _hedgerow-eels_. + +On the other hand, fishes may be drowned in water just as easily as +ourselves if it does not contain air. The little fish who could have +lived very well in the bottle we were just now talking about before +you exposed it to the flame of the taper, would have died in it after +all the air-bubbles had gone off; and I hope I need not tell you why. +In the same way, if you leave fishes too long in a small quantity of +water without renewing it, they suffer exactly as we do if the air +which we breathe is not changed often enough. As soon as they have +consumed what oxygen is in the water, it can no longer keep them alive. +It is then, especially, you will see them come gasping to the surface +to call upon the air for help. Those who keep gold fish in a glass +bowl ought to know this, and to change their water oftener than is +generally done. When we take poor little creatures from their natural +way of life, and set a human providence over them in the place of the +Divine one which has hitherto been their safeguard, the least we can +do is to acquaint ourselves with the laws of their existence, so that +we may not expose them to the risk of suffering by our ignorance. +Finally, there are fishes whose gills, still more greedy of oxygen, +will not act well except in thoroughly aerated water, and who would +soon die in our tanks. This is the case with the trout, who is only +happy in the waters of hilly countries; rich with all the air they +have carried along with them as they fell from rock to rock. Now that +people are beginning to do with fishes what has long since been done +with sheep and oxen--keep them in flocks to have them always ready for +use--you may perhaps hear a good deal said about vessels made expressly +for the carriage of trout, with a thousand inventions besides for +sending air into the water, and you will not have to ask the meaning +of this now. + +I promised last time that I would revert in the chapter of fishes to +that marvellous transformation of the crocodile which has been explained +by the torrent of water he draws into his stomach. You could understand +nothing about it the other day; but after what we have just seen the +explanation suggests itself. Just as the extraordinary activity of +life in birds is explained by that double oxygenization of blood, of +which part takes place in the lungs and part in the reservoirs of air +placed everywhere in the way of the capillaries, so this sudden increase +of energy in the crocodile the moment it plunges into water may be +explained by a second respiration suddenly established in the vast +cavity of the abdomen, by the contact of the capillaries with the water +which penetrates there. Hence the crocodile would then have, like the +bird, a double respiration: only with him the one would be permanent +and from the lungs, the other temporary and from the stomach. By this, +on the one hand, he would rise up to the birds, since the blood +encounters air twice over in its course, while, at the same time, he +would plunge into the world of fishes, since the blood has to seek air +in the water. The above, be it remembered, is only a supposition, and +I ought to add that in this case there would be a good deal of danger +in observing nature at work, for in front of the laboratory, where she +is toiling in secret, stands on guard a row of teeth, by no means +encouraging to indiscreet intruders. At the same time, if there ever +were a legitimate conjecture, this is it. Everything seems to confirm +it; and if it be true, we should have in the crocodile a specimen of +each of the four systems adopted by nature for the mammal, the bird, +the reptile and the fish. At first I spoke of two, then of three; so +that even in my addition I was modestly below the mark, and had really +some grounds for recommending our friends the classifiers to beware +what they asserted in this case. + +Talking of puzzling classifications, this is just the place for +mentioning the _batrachians_, who have been made into a class by +themselves, but who most distinctly belong to two classes at the same +time; not like the crocodile by details borrowed from each, but by a +fundamental change which takes place at a certain period in their +organization. The batrachians are in reality reptiles, but they are +reptiles which begin by being fishes, and real fishes too. + +If you have ever strolled about in the country, you must have often +come across those great pools of water which collect at rainy seasons +in the ruts of deep lanes. Amuse yourself by looking into them in +early summer, and unless the land is too parched and dry, the chances +are that you will see quantities of little black fishes, almost entirely +composed of a long tail joined to a large head, playing jovially in +the muddy waters, and looking as if they had dropped there from the +skies. These are young frogs--_tadpoles_, as we call them--and +they are beginning their apprenticeship of life. Enclosed in each side +of those great heads, they have gills, and they breathe in the same +manner as fishes. Presently the two hind feet begin to bud out and +grow, little by little; then the fore feet; finally, the tail wastes +away till it disappears; and thus insensibly the tadpole is transformed +into a frog. Observe here that the tadpole's gills share the same fate +as his fish-tail; they wither and disappear by slow degrees, and +gradually as they do so, his lungs are developed. The animal changes +his class very quietly, and without ceasing to be genuinely the same, +although it would be impossible at last to recognize the old individual +in the new if you had not heard its history beforehand. This is one +of the most striking exemplifications I know of the mysterious process +by which nature has insensibly raised animals from one class to another, +always improving upon her original plan without ever abandoning it. + +On the shores of certain subterranean lakes which exist in Carniola, +a country subject at this time to Austria, there are to be found +batrachians far more ambitious than our frog--namely, the _proteans_. +These cumulate rather than change: they become reptiles without ceasing +to be fishes, if I may so express it; they develop lungs as they grow +up, and yet keep their gills. I could tell you a thousand other +particulars about these batrachians if I were to examine them all in +succession; for it is a very motley family, in the bosom of which the +transition from reptiles to fishes is in some imperceptible manner +accomplished; from the frog, which the unanimous consent of mankind has +always ranked among reptiles, to the axolotl or siren, who lives in +Mexican lakes; and who, feature for feature, is exactly like a carp, +with four little feet fastened under him. To be quite in order, the +batrachians ought to have followed the reptiles, for their interior +organization is the same; but how could I tell you about their gills +without explaining that there was air in the water? and I did not want, +for the sake of these intruders, whose babyhood-gills only just appear +and disappear, to rob the history of the fishes of its most interesting +points. + +Let us be satisfied, then, with this passing glance at a dubious class, +whose history is only a repetition of two others, and let us return +to our friends the fishes. We have seen how they breathe, now let us +look how they eat. + +The modifications of the digestive apparatus are endless among fishes. +The lampreys, who are placed in the lower ranks of the class, carry +out to its fullest extent the type which we have already seen indicated +in the serpent. The digestive tube is quite straight, without any +perceptible swelling, and does not even go the whole length of the +body. It comes to an end at some distance from the tail. Among some +fishes an odd tendency begins to display itself, which we shall meet +with again farther on. The digestive tube, after going downwards towards +the bottom of the body, as we have seen it do so constantly hitherto, +doubles back, and comes up again to the throat, under which it empties +itself. In most cases the stomach is distinct; but it assumes a thousand +different forms; as if nature had wished to try her hand in all sorts +of ways in the construction of these imperfect vertebrates, before +adopting the definite model which was to serve for the others. + +The liver is enormous, and generally contains a great quantity of oil, +the taste of which you will know if you have ever swallowed a spoonful +of cod-liver oil; but in most fishes its old companion, the +_pancreas_, has disappeared. In its stead you will find, close +by the outlet of the pylorus, the open ends of certain small tubes, +which are shut in at their upper extremity like a "blind alley," and +through which descends into the interstices a thick glairy fluid, given +out from their sides or walls. The result is the same, you see, although +the organ is different; and, remarkably enough, these little tubes are +wanting among fishes, which, like carp, have a species of salivary +glands in their mouths, of which the others show no trace; from which +one may fairly conclude that these glands and tubes mutually supply +each other's places. Here, then, you see an instance of the light which +different animal organisations throw upon each other when they are +compared together. In fact, this one establishes pretty clearly the +real office of the pancreas in the higher races, exhibiting it to us +as an internal salivary gland, intended to complete the work only begun +by those in the mouth, in the case of lazy people who swallow their +food too quickly. + +There is the same diversity in the mouth as in the intestine. Some +fishes, like the skate, have no tongue at all. Others, instead of a +tongue, have a hard dry filament, very nearly immovable, and which one +would think was put there like a stake, to show the place where the +tongue is to be found in the more perfect organisations. There are +even fishes, like the perch and the pike, whose tongue is furnished +with teeth, or rather fangs; an evident sign that it has forfeited the +confidential position occupied by your own good little porter. You +must know also that the perch and the pike, like many other of their +fellows, have teeth all over the mouth. This invasion of the palate +by teeth, which began in the lizard and the serpent, assumes alarming +proportions here. It is not merely the roof of the palate which is +spiked with teeth: above, below, at the sides, everywhere to the very +limits of the oesophagus, the little fangs triumphantly stick out their +slender points. It is impossible, therefore, to state their number. +Nature has scattered them broadcast without counting, just as she has +done with the hairs of the beard round the human mouth; and the +comparison is not so impertinent as you may think. They sometimes form +an actual internal beard, even thicker than our outer one, and which +sprouts from the skin into the bargain. There is one fish whose teeth +are so delicate and so close together that, in passing your finger +over them, you would think you were touching velvet. This does not +refer to the shark, mind. His teeth are sharp-cutting notched blades, +hard as steel, arranged in threatening rows round the entrance of his +mouth, and cut a man in two as easily as your incisors do a piece of +apple. Others, such as the skate, have their mouths paved--that is the +proper term--with perfectly flat teeth. The first time your mamma is +sending to buy fish beg her to let you have a skate's head to look at. +You will be interested to see the small square ivory plates laid close +adjoining each other, like the tiles of a church floor. It is in fact +a regular hall-pavement, over which the visitors glide untouched, and +are then swallowed down in the lump; thus entering straight into the +house without having been stopped by the inscription nature has placed +over your door and mine--"Speak to the Porter." + +But all this is nothing compared to the lamprey's entrance-hall, which +differs from ours in quite another way. The lamprey, as I have already +told you, ranks almost lowest among fishes, and consequently among +vertebrate animals, of which fishes form the rear-guard. Indeed, it +is almost stretching a point to consider her worthy to bear the proud +title of a vertebrate at all; for the vertebral column, so clearly +marked in other fishes, where it forms the large central bone, is only +faintly indicated in certain species of lampreys, by a soft thread (or +filament), which is rather a membrane than a bony chaplet, and at the +top of this mockery of a vertebral column is the creature's mouth. If +you ever had leeches on, you will remember the sharp sting you felt +when the little beasts bit you. Well, the lamprey feeds herself just +in the same way as the leech does. Her mouth forms a completely circular +ring, which sticks to the prey, and through which runs backward and +forward a small tongue armed with lancets. This darts out to pierce +the skin, and draws in the blood as it retreats. Round your lips well; +dip them so into a glass of water, and draw back your tongue, and you +will at once feel the water rise into your mouth. It is by a similar +sort of proceeding that leeches relieve people of the blood they want +to get rid of; and in the same way the lamprey draws out the blood of +the animals upon which she fastens. + +What a long way we have come already! How very far we find ourselves +here from the little mouths we first talked about as chewing their +eatables so prettily! With the lamprey we bid adieu to the class +Vertebrata--the nobility of the animal kingdom--among whom nevertheless +we must distinguish between the peer, who approaches nearest the person +of his sovereign, and the inferior provincial lords who live at a +hundred miles' distance. There is only one step from the lamprey to +the _mollusks_ or soft-bodied animals, and this is the course +which animal organisation seems really to have taken in its progress. +But nature never moves forward in a single straight line. In passing +from the mollusk to the fish to get thence to the higher vertebrates, +she turned aside in another direction toward a class of animals which +rises far above mollusks, but which leads to nothing beyond. + +One would think there had been a check here, as if the creative power, +having discovered that it was going in a wrong direction, had retraced +its steps; if it be allowable to apply common ideas and expressions +to our conceptions of that Great Intelligence which has arranged the +plan of the mysterious ladder of animal life. + +The animals we must examine next, on account of their superiority to +the rest, are insects. Small as the ant is, it would not be right to +let her be preceded by the oyster. + + + +LETTER XXXVII. + +INSECTA. (_Insects._) + +Before speaking of insects, my dear child, it will be necessary, in +the first place, to tell you to what primary division they belong and +on what characters this division has been established. And here I find +myself in a difficulty. We have been but too learned already, and now +we run the risk of becoming still more so, if we commence an attack +on the three primary divisions which follow the vertebrates. We shall +have to encounter terrible names and tedious details, besides having +to take into account a thousand things of which we have not yet spoken. +We are going on quietly with the history of the feeding machine which +occupies the middle of the body, and learned men never looked in that +direction for the establishment of their divisions; between ourselves, +it was not accommodating enough. They have fallen back upon the +locomotive apparatus (_movement machine_) which affects the body +all over, and which they have proclaimed to be the leading feature of +the animal organization, without noticing however that it is, after +all, but the servant of the other. It is true that the great divisions +are more easily established upon this point than the other, because +the differences are more decided. It separates what the other unites, +and thus it is that nature carries on that beautiful combination which +the Germans have so accurately named "_Unity in Variety_" that +is to say, she is always at work, as I have already told you, on the +same canvas, but always embroidering it with a different pattern. +Wait! I have something to promise, if you are very good, and if this +history (that of the feeding machine) should have given you a taste +for inquiry. I will tell you another time the history of the movement +machine, and there the classification of our learned men will come in +naturally very well. In the meantime we will do as they do, and just +shut our eyes to their divisions, in which the feeding machine can +have no interest, because they were established without reference to +it. We will content ourselves, then, without further pretension to +science, with modestly examining the last transformations of our pet +machine in the principal groups of the inferior animals; of which +groups I will now tell you the names in their proper order. They are +as follows: Insects, Crustaceans, Mollusks, Worms, and Zoophytes. You +must take these names on trust; those which you do not understand will +be explained in their places. + +1. _Insects._--I know not where it was I once read that there are +said to be something like a hundred thousand different species of +insects; and I verily believe this is not all. Of course we shall not +attempt to review the whole of this formidable battalion. Let us take +one of those you are most familiar with--the cockchafer, for +instance--and examine what goes on in his inside. The history is nearly +that of all the others. + +"Fly away, cockchafer, fly!" says the song; and surely it is a bird +that we have here, and a bird which will appear to you even more +wonderful than those of which I have already spoken, when you have +considered the simplicity, and at the same time the strength, of his +organization. His mode of flight is rather lumbering, it is true; he +is, in comparison with the large flies, what the ox is to the deer; +but when you contrast the weight of his thick body with the delicacy +and narrow dimensions of the two membranes which sustain him in the +air, you may well ask yourself how those little morsels of wings, thin +as gold-beater's skin, can carry such a mass along. In fact, they only +accomplish this feat of strength by dint of an excess of activity +almost startling to think of. When you run as fast as you can, how +many times, think you, do you move your legs in one second? You would +be somewhat puzzled to say; and so should I: but I defy you to count +ten. Now the bird makes his wing move much oftener when he beats the +air with rapid blows as he flies; but even he does not strike a hundred +strokes in a second: and what is this to the feats of the cockchafer's +wing? It is not hundreds but thousands of times that he flaps his wings +in a second; and here let me hint, by-the-by, that when people seriously +wish to find out a method of travelling in the air, they will lay aside +balloons, of which they can make nothing in their present condition, +and will set to work to fabricate machines with wings which shall beat +the air as fast as those of the cockchafer. This sounds extravagant, +but I have seen an electric pile fixed in a stand with glass feet, +which caused a little hammer to beat thousands of times in a second: +and surely the hammer could have been made to communicate its movement +to a small wing! Forgive me this little castle in the air! The idea +came into my head a long while ago, and the cockchafer has just reminded +me of it. I will not, however, pursue the subject, neither will I offer +to explain the method used for counting the beats of an insect's wing. +That would carry us farther than would be desirable. + +To return to our little animal. I leave you to imagine the enormous +amount of strength required for such precipitate motion. We have spoken +of the rapid course of the blood in birds during flight: who shall +calculate its comparative rate in this fabulously wonderful locomotive, +the cockchafer? And if we lift up the cuirass which encases it, what +do we behold? Not a single trace of all the complicated +circulation-apparatus you have learnt to know so well; neither heart +nor veins nor arteries; only a quantity of whitish liquid, equally +distributed throughout the whole internal cavity. Not a trace of lungs, +nor any apparent means of renovation for this seemingly motionless +blood; for blood it is, in spite of its color, or, at any rate, blood +in its first stage of formation. It also has its globules--ill-formed, +it is true, and altogether in balls--like those found in the chyle +with us; which chyle, be it observed, is the same color as the blood +of insects, and may also be considered blood in its apprenticeship. +By what magic, then, is this raw, imperfectly-formed steward, who seems +altogether stationary, enabled to accomplish exploits which would +stagger his higher-bred compeers, agile and perfected as they are? +Where does he pick up the oxygen necessary for such repeated movements, +it being an established fact that no animal can move at all without +consuming oxygen, and that the quantity consumed is in proportion to +the rate of motion? Look under his wings for an answer. There, all +along his body, you will observe a number of small holes, pierced in +a line, at regular distances, and furnished with shutters of two kinds. +They are the mouths of what are called _tracheae_, or breathing +tubes: and from them branch out a multitude of little canals, which, +spreading in endless ramifications through every part of the body, +convey to the whole mass of the blood, from all directions, the air +which makes its way into them through the tracheal holes. In this case, +you see, it is not the blood which seeks the air, but the air which +seeks the blood; whence arises a new system of circulation, whose +action is all the more energetic because it is unintermitting, and +makes itself felt everywhere at the same time. A little while ago we +were wondering at the twofold respiration of birds; yet this is far +less surprising than the universally-diffused respiration of insects, +who may well be able to do without lungs, seeing that their whole body +is one vast lung in itself. + +For the rest, do not trust to appearances, nor imagine that the blood +of our friend the cockchafer in reality remains motionless around the +air-tubes, idly drinking in the oxygen which is brought to it. Though +not flowing in enclosed canals, it is not the less continually displaced +by regular currents, which sweep through and renew this apparently +stagnant pool. Nor is this the only instance of such a current presented +to us by nature. + +Guess, however, if you can, where you will have to look for the +counterpart to the circulation of the cockchafer. In ocean itself! +But, remember, nothing is absolutely little or great in nature, who +applies her laws indifferently to a world as to an atom. The blood of +our world is water, which contains in itself all the germs of fertility, +and without which, as I have already told you, life is impossible +either in the animal or vegetable kingdom. The water of brooks, streams, +and rivers, flows along in channels, which, when figured in a map, +present to the eye of the beholder an exact picture of the system of +circulation found in the vertebrated animals. But the waters of the +sea are borne along, like the blood of insects, by a secret circulation, +which cannot be represented on the map; _i.e._ by immense currents +everlastingly in action, some on the surface, some in the mid-heart +of the ocean, which drive it in ceaseless course from the equator to +the poles, from the poles to the equator; so that the Supreme +Intelligence, in His overruling providence, has ordained the same law +to set in movement the immensity of ocean, and to effect circulation +in the cockchafer's few drops of blood. In the latter we find the +moving agent to be a long tube, which runs the whole length of the +back, and is called the dorsal vessel (from the Latin _dorsum_, +back). I told you that the cockchafer had no heart under his cuirass, +but I spoke too hastily. The dorsal vessel is a _true heart_, but +a heart devoid of veins or arteries, and thrown into the midst of the +blood. It dilates and contracts like ours, sucks in the blood by means +of side-valves, which act as our own do, and drives it back again into +the mass by that valve at its extremities, which opens near the head. +From thence arises a continued to-and-fro movement, which sends the +blood from the head to the tail, and brings it back again from the +tail to the head. But who would recognise, in this simple primitive +organisation, where all seems to go on of its own accord, as it were, +the same machine, with all its complicated movements, that we have +been so long considering? + +Well, in this apparently universal shipwreck of all the organs we know +so well, there is yet one which survives, and remains the same as ever, +namely, the digestive tube. I began by saying the insect is a bird. +His digestive tube is formed upon the same pattern as that of birds, +so that naturalists have bestowed the same names on the various parts +in each of them. After the oesophagus comes a crop (_jabot_), very +distinctly indicated; then a gizzard with thick coats, in which the +food is ground down. The hen, if you remember, swallows small pebbles, +which perform in her gizzard the office of the teeth in our mouths. +The cockchafer has no need to swallow anything. His gizzard is furnished +with little pieces of horn; real teeth, fixed in their places, which +have a great advantage over the chance teeth picked up at random by +the hen. I pointed out to you in birds, between the crop and the +gizzard, a swelling or enlargement of the digestive tube, pitted with +small holes, where the food is moistened by juices. The same enlargement +is found here, covered all over with a multitude of small tubes, which +might easily be mistaken for hairs, from which also falls a perfect +shower of juices. The only difference is, that it comes after the +gizzard, instead of before it, as in birds. Some naturalists, +considering that the manufacture of chyle takes place here, have called +it the _chylific ventricle;_ [Footnote: The corresponding +protuberance of the birds bears a name, somewhat similar, but stillmore +barbarous. I had passed it over in silence, because, I make the +confession in all humility, I do not understand it; but a remorse now +seizes me: it is called the _Ventricule succenturie._] a somewhat +barbarous name, but one which explains itself, and might with truth +be applied to the _duodenum_ of the higher animals. Bile is poured +in close to the hinder end of it, but you must not look for the liver; +it has disappeared, or rather its form is entirely changed. You remember +what the _pancreas_ had become in fishes; _i.e._ a row of tubes giving +out a _salivary fluid._ Such is exactly the appearance of the liver in +the cockchafer. + +Instead of that fleshy substance on which hitherto the office of +preparing the bile had devolved, you see nothing but a floating bundle +of long loose tubes, which, opening into the intestines, pour in their +bile. The organ is transformed, but we recognise it again by the office +it performs, which continues the same. As to the _pancreas_ it is +wanting here, as in the fish with salivary glands; but in its place +in many insects other tubes, acting also as glands, pour saliva into +the _pharynx; i. e._, the cavity at the back of the throat. + +As you see, therefore, everything is found complete in this tube of +a few inches long; and you can also distinguish there a small and a +large intestine. We are speaking of the cockchafer, which feeds on the +leaves of trees; and it is for this reason I name some inches as the +length of the digestive tube. This would not be longer than the body +itself, had it been destined, as in the case of many other insects, +to receive animal food. In fact, the law which we have shown to exist +with regard to the ox and the lion, rules also over the insect-world; +and whilst a radical change seems to have been made in the rest of the +organisation, here everything is in its place, and we find ourselves +in the same system. + +Was I not justified in asserting that the unity of the animal plan is +to be found in the digestive tube? and that this is the unchanging +basis upon which the Creator of the animal world had raised his varied +constructions? + +How would it be, then, if we were to take the insect from its +starting-point when it is only a worm, that is to say, merely and +simply a digestive tube? for I am only telling you a small portion of +its history here; a history you must know, which reveals a miracle +still more wonderful than the transformation of the little tadpole +into the frog! There is a brilliant-colored fly which comes buzzing +about the meat-safe--the bluebottle--do you know her? It is on her +account that we put large covers of iron wire over the dishes of meat; +but, perhaps, you never troubled yourself to think why. + +But the truth is, she only comes there to deposit her eggs in the good +roast-meat; and if she could get near enough to do so, you would soon +afterwards see it swarming with little white worms, which would entirely +take away all your appetite. These worms are only flies out at nurse, +and they will find their wings by-and-by if you only give them time +enough. Disgusting as they may appear on a dining-table, I assure you +they deserve more interest than you may think. When we come to speak +of worms, we will ask of them to let out the secret of the mysterious +transformations of animals. + +In the meantime, let us finish the observations we were making on the +_perfect insect_, as this little creature is called when he has +passed through the intermediate stages which separate him from the +undeveloped condition. Forgive me, my dear child, here I am speaking +to you as if you were a grown-up woman! This is because it is so +difficult to explain things of this sort in any other way. And now +that you have been introduced into the midst of the wonders of creation, +you ought to familiarise yourself with the ideas and terms they have +suggested to mankind. I began with you as a child, and great would be +my triumph if I could leave you a grown-up girl! And I flatter myself +that I have so far set your brain, to work, under pretence of amusing +you, that this hope is not altogether unfounded. I found it necessary +to say this to you in confidence, because I have just read over our +first conversations, and perceive that I have insensibly put you on +a different diet from the one I began with. I am obliged to comfort +myself by remembering that you have grown older since, and that you +are now acquainted with a great many things which you had never heard +spoken of then. And this is the secret of all transformations. We crept +on at first over ground that was quite unknown to us; but as we went +along, our wings must have begun to grow, and we are now able to fly +a little! + +Do not be afraid, however; I will exercise your tiny butterfly-wings +very carefully just at present. We have only to examine what becomes +of the _chyle_ of the cockchafer after it has been prepared in +the pretty little tube so finely wrought. We men have _chyliferous_ +vessels which draw up chyle from the intestines and throw it within +a short distance of the heart, into the torrent of blood, where its +education is completed. But the cockchafer, who has no other vessels +than his air-pipes, and the _dorsal tube_, which has no communication +with the intestines, what is he to do? Do not distress yourself about +him. Make a tube of a bit of linen, well sewn together, and fill it with +water. Sew it together as firmly as you may on all sides, the water will +have no difficulty in escaping through the meshes. And this is just what +happens with the little tubes found in animals, the coats of which are +formed of interwoven fibres. By-the-by, from thence comes their name of +"_tissue_," which they share in common with all the solid substances of +the body, for all were once supposed to have the same general structure. +The intestine of the cockchafer floats, did I not say? in the lake of +blood which fills the whole cavity of the body. Well, then, the chyle +has only to penetrate through these coats, to go where it is wanted. +Hence it is not at all surprising that this blood should be white; and I +have very good reasons just now for comparing it to our _chyle_. It is, +indeed, chyle arriving directly from the place of its manufacture, +without undergoing any other process; by which you may see that this +little machine (of the digestive organs of the cockchafer), though +differing in appearance so entirely from our own, is reducible to the +same elements of construction, and that life is maintained by the same +process as with us; namely, by the action of the air upon the albumen +extracted from food. The cockchafer, it is true, is much further removed +from being a fellow-creature of ours than even the horse; but the +principle of life is the same with him as with us. And this is quite +enough to cause children, who can feel and reason, to think twice before +they begin to torture, by way of amusement, a creature whose life the +God of goodness has subjected to the same conditions as our own. I speak +this to those miserable little executioners who make toys of suffering +animals: but the case is different with agriculturists, who have +necessarily to contend with the devourers of their harvests, and whom, +I admit, it would not be reasonable to bind down by the maxim of Uncle +Toby. + +[Footnote: I have introduced my Uncle Toby, who really has nothing +to do here, in order to make you acquainted with a few lines of Sterne, +which I wish I could place before the eyes of every child in the world. + +"Go!" said he, one day at table, to an enormous fly which had been +buzzing around his nose and had cruelly tormented him all dinner time. +After many attempts, he finally caught him in his hand. "Go! I will +not do thee any harm," said my Uncle Toby, rising and crossing the +room with the fly in his hand; "I would not hurt a hair of your head. +Go!" said he, opening the window and his hand at the same moment, to +let the fly escape; "go, poor little devil; away with you; why should +I do you any harm? the world is certainly large enough to contain both +of us!"] + +But now to finish with the cockchafer. We have got to examine one very +important part of his body, that which in other animals has been the +one most talked about ever since we began our study: I mean the mouth. +You know that this is the essentially variable point in the digestive +tube; so that you will not be much surprised, should we find he has +something altogether new. The mouth of the cockchafer is composed of +a great number of small pieces placed externally round the entrance +to the _alimentary canal_; but the names of these, as they would +not interest you, I will not enter upon with you; more especially as +they refer to such tiny morsels, that you would have great difficulty +in finding them again on the owner. Of these pieces only two are worth +our attention. These are two bits of extremely hard horn, placed one +on each side of the animal, which are called "_mandibles_" and +which serve the cockchafer to cut up the leaves which he eats. Fancy +your share of teeth being two huge things fixed in the two corners of +your mouth, each advancing alone against the other till they meet under +the nose! You would then attack your tarts with the weapons of the +cockchafer! You would not, however, be able to bite them straight +through from the top to the bottom, as is done by all the animals whom +we have yet seen. It is this which so peculiarly distinguishes the +insect's manner of feeding; for we have already been taught by the +bird and the tortoise, that it is possible to eat with two pieces of +horn. The cockchafer now shows us how to eat sideways; but this is +merely an accessory detail. It does not affect what happens after the +mouthful is swallowed. All insects, however, have not this peculiarity. +The cockchafer belongs to the category of grinding insects as they are +called, who bite their food: but there is the category of the sucking +insects (or suckers), whose food consists of liquids; and these insects +are furnished in a different manner. + +In the innocent butterfly, who lives on the juice of flowers, the +digestive tube terminates externally in a sort of _trunk,_ twisted +in several convolutions, which is nothing more than an exaggerated +elongation of the two jaws, which become hollow within, and form a +tube when joined together. When the insect alights on a flower, he +suddenly unrolls this trunk, and sucks in the juices from the depth +of its "corolla," as you would drink up liquid with a straw from the +bottom of a small vial. Amuse yourself some summer's day by watching +a butterfly in his labors amongst the flowers: sometimes he stops +still, but oftener he is contented to hover over them; and, as he does +so, you will see a little loose thread, as it were, move backwards and +forwards as fast as possible: this is his trunk, which he darts out, +while flying, into the corolla of the flowers, but which scarcely seems +to touch them, so delicate is its approach. + +Less inoffensive far is the trunk of the mosquito-gnat, and of all the +detestable troop of blood-sucking flies. It is always a tube; but this +tube is no longer a simple straw, but a sheath furnished with stilettos +of such exquisite delicacy and temper, that nothing is comparable to +them; and these, as they play up and down, pierce the skin of the +victim, like the lancets of the lamprey, and, like them, draw in blood +as they retreat. + +Finally, amongst the _parasites,_ the last and lowest group of +insects, the stiletto-sheath is reduced to the size of a kind of little +tube-shaped beak, which, when not in use, folds down like the fangs +of the rattlesnake. + +You do not know, perhaps, what a parasite is. The word comes from the +Greek, and signifies literally, "_that which moves round the +corn._" The Greeks applied it to those shameless paupers who, to +escape honest labor, made their way into the houses of the great, and +enjoyed themselves at their expense. These parasites are little animals +which settle themselves on large ones, to suck in, without having +worked for it, the blood which the others have manufactured. The wolf +hunts, fights, and tears its victim in pieces; and then, by means of +that interior labor which I have spent so much time in describing, +transforms it into nourishing liquid: and when all this is accomplished, +the little flea, who lives hidden among his hairs, coolly draws out +for his own use the valuable blood obtained with so much effort. There +are many parasites in the world, my dear child--yourself, for instance, +to begin with--who are perfectly happy to chew your bread without +asking where the corn comes from which made it. But you have heart +enough to see plainly that this indifference ought not to last, and +that it is not honorable to go on living in this indefinite manner at +other people's cost only. + +You will some day have duties to fulfil, which you should accustom +yourself to think of now, in order that you may prepare yourself for +them beforehand, so that it may never hereafter be said of you that +you passed through the midst of human society, taking from it all you +needed, without giving it back anything in return, I advise you to +conjure up this idea when the time comes to leave off playing and begin +preparing to be of use. The sort of thing is not always very amusing, +I admit, but you must look upon it as the ladder by which you will be +enabled to rise from the degradation of a parasitical life. If you +were in a well, and some one were to let down a real ladder for you +to get up by, I do not think you would complain of the difficulty of +using it. It is for you, then, to consider whether you would like to +remain for ever in your present condition; for those who learn nothing, +who _submit_ to nothing, who are good for nothing, but to show +off and amuse themselves--these remain parasites all their lives in +reality, however little they may sometimes seem to suspect it. + +At your age, however, there is still no disgrace in the matter. God +shows us by the insects that little things are allowed to be +parasitical; but on this subject I must return to a point in the history +of animals which I touched upon before. I told you, in speaking of the +crocodile, that the perfect state of the inferior animals is found +represented in the infancy or less perfect state of those above them: +and I may say the same again with regard to insects. All the young of +the mammalia begin life as parasites, at least, as sucking animals: +for they all live at first on their mother's milk, which is nothing +more than blood in a peculiar state. But the name of parasite among +insects is generally confined to those which take up their abode on +the bodies of their hosts; though in common justice it might equally +well be applied to the gnat and his relations, who, when once full, +make their bow and are off, like the kitten when he has finished +sucking. Well, without meaning to find fault, if we descend to the +lower ranks of the mammals, we shall find among them many parasites +in the received sense of the word. You remember the pouch to which the +marsupials owe their odd name. The young kangaroo remains hidden for +months in the pouch of its mother, feeding continually all the time; +and it is then a strict parasite. During the four following months it +goes in and out, and strolls about between meals, like other young +ones of its class, and is then an animal at nurse affording thus a +twofold example of the tendency of the great Creator to repeat Himself +in His conceptions, here using for the infancy of the mammal the system +invented for adult insects--elsewhere repeating the butterfly in the +humming-bird, who may fairly be called a vertebrated butterfly, and +reproducing the gnat in the vampire-bat, which I look upon as an +enlarged and perfected revise of the original pattern, whence comes +the scourge of our sweet summer nights. + +And now, surely, I have said enough about these parasites, whose very +name, I suspect, will make you shudder after my impertinent application +of it. Never mind: it depends entirely upon yourself to get rid of +whatever you find humiliating in the position I have hinted at. Do all +you can to bring happiness to the parents on whom you live at present, +and who give their life-blood so willingly for your good. God has made +you very different from those little animals who have neither heart +nor reason to guide them. Do not be like them, then, in conduct. By +a little obedience and love--child as you are--you can pay them back +what you owe, and they will never complain of the bargain. + + + +LETTER XXXVIII. + +CRUSTACEA--MOLLUSCA. (_Crustaceans and Mollusks._) + +_Crustaceans._ + +Crustaceans consist of cray-fish, crabs, lobsters, and prawns, who may +be considered cousins-german of insects, among which more than one +naturalist has thought they ought to be placed. Like them they are +divided into _grinders_, having the same action of the mandibles; +and _suckers_, who are also parasites, and have tubular sheaths +containing stilettos. Mammals and birds are the victims of parasitical +insects; fishes have been reserved for the crustaceans, who do not +disdain also to fasten upon their humble neighbors, the mollusks; and +even among themselves the little ones settle down on the great. A few +live on land, but an immense majority in water, and seem destined to +represent, in the aquatic world, the aerial class of insects, from +whom, however, they differ in many ways. + +The first difference is in that stony crust with which they are +enveloped, like the cockchafer in his horny cuirass, and which you +must know well enough if you have ever eaten lobster. Wherever we meet +with horn in insects, we find stone in crustaceans. The jaws are stony, +and the teeth of the stomach also. They are constructed on the same +plan, only the materials are changed. + +The digestive tube is less complicated, and consists merely of one +large stomach, instead of that series of stomachs by which insects +approach the organisation of birds. On the other hand, if among some +of them the liver is reduced to simple tubes, floating loosely in the +body, as we have just seen it in the cockchafer among insects, these +tubes are generally so profusely multiplied, and press so closely +against each other, that they form a large compact lump--a true liver, +to sum up all--from which issues, as from ours, a _choledochian +canal_, a bile duct, _i. e._, which passes out into the intestine at the +entrance of the pylorus. + +You recollect that canal of the liver which I was afraid to tell you +the name of because it was so ugly? Well, this is that formidable name! +Now that you have swallowed so many others, you must be strong enough +to digest this. + +No chyliferous vessels have been found in crustaceans, whence one may +conclude that the chyle leaves the intestine by oozing from it, just +as it does in insects. There it gives rise to an almost transparent +sort of blood, a kind of sap, or lymph, which is put in motion by a +genuine circulation-apparatus; a real heart, with all its canals. This +heart has only one ventricle, and only sends blood in one direction, +as in the case of fishes; but there is an essential difference between +them, which we must point out. The heart of fishes may be called a +venous heart, since it only receives venous blood, which passes thence +to the gills, while that of crustaceans is an arterial heart. It +receives the blood directly it leaves the respiratory organ, and sends +it, not into one aorta, but into several arteries, which set out at +once, each in its own direction, to nourish the various quarters of +the body. This greatly resembles the system of circulation, with which +we are already acquainted. The veins only are unsatisfactory. They +form a kind of transition between the uncertain currents which convey +the blood of insects from one end to the other of the cavity in which +these strange organs lie bathed, and the closed canals of the higher +animals. But they are not canals, properly speaking. The irregular +intervals which separate the organs, more numerous here, are enclosed +by membranes, between which the venous blood pours, and naturally the +chyle also. The whole thus arrives at certain excavations formed at +the place where the legs are jointed on to the body--reservoirs, so +to speak--where the real canals come to carry it off and convey it +away into the gills. + +It is, in fact, by means of gills that crustaceans breathe in their +character of aquatic animals. These gills are made nearly upon the +same model as we have already seen in those of fishes; and although +their form and arrangement differ in different species, yet the +principle is always the same: they are tufts of leaflets springing +from stems, up and down which run two tubes; one which brings the blood +from the venous reservoirs, the other which carries it to the heart. +Crabs, lobsters, and crayfish, who are the "file-leaders" of the +crustacean tribe, have gills enclosed in the body, as fishes have; but +the circulation of the water goes in a contrary direction to theirs, +as does that of the blood. Instead of entering at the mouth and going +out at the sides, as we have seen, it enters at the edge of the bony +shell which covers over the body and comes out near the mouth--a merely +accidental detail which does not in any way alter the play of the +apparatus. All these animals are equally adapted for swimming and for +walking, crabs especially, their gills accommodating themselves without +difficulty to contact with the outer air, as we have seen among certain +fishes; so that one might class them with amphibians. There is even one +crab who has acquired the name of _land-crab_, because, although he has +got gills, he dies in water, the small amount of air he can get out of +it at a time being insufficient for him, and who, therefore, lives +constantly on land. It is true that he seeks out damp spots, for his +gills would also fail him if they became parched, and, like the fishes +who make excursions on dry land, he is provided with an internal +reservoir, which is always filled with a certain quantity of water. + +Some aquatic crustaceans have the labor simplified by external gills, +which hang down into the water, sometimes depending from the stomach, +sometimes from the legs. In France you sometimes see at a table certain +little animals, very like shrimps (_squillae_), the bases of whose +hinder legs are fringed by slender tufts, which are in fact their +gills. They find themselves placed there just within reach of the +venous blood; for in the body opposite the bases of the legs are little +cavities in which it accumulates. Now these gills can only act when +under water, and so the squillae dies as soon as he is removed from +that protecting element. For the same reason they cannot be kept long, +nor travel far, much to the regret of those who like them and live at +some distance from the sea. + +There are other crustaceans, next-door neighbors of the squilla, whose +gills are still more simplified. Here the legs themselves are turned +into extremely thin plates, which play the part of gills, and are thus +organs for two purposes, serving at the same time to swim and breathe +with. + +We have in our house one little crustacean, the only one I know of who +associates with men, and that is the wood-louse. You must know the +little grizzly beast, which rolls itself up into a ball whenever it +thinks itself in danger, and who would be taken for an insect by anyone +who was not taught otherwise. The wood-louse has neither gills hanging +down outside, nor anything inside her body which resembles the breathing +apparatus of her great relations. But, on examining her closely, you +will perceive all along her stomach a series of little plates, which +are her breathing-organs, and which come under the class of gills, +because, like other gills, they require a certain degree of moisture +to make them act properly. You will never, therefore, see a wood-louse +strutting about in the sunshine, where he would dry up far too quickly; +but if ever you get into a dark, damp corner, there you have every +chance of finding one. + +Animals who breathe through their legs and through their stomachs! You +are astonished, and ask, What are we coming to? What would you say, +then, if I were to go really to the depths of the crustacean world? +We should find there such extraordinary beings as you can form no +notion of, for they all live down below in the sea, and have no special +breathing-organ at all, inasmuch as they breathe through the whole +surface of the body. Do not exclaim yet! I will soon show you one whom +you know perfectly well, and who has no other way of breathing. + +But we must keep to the higher crustaceans, if we want to judge of the +class. By going too low, we run the risk of not seeing clearly. Animal +creation is here on a system of experiments: and they are so endlessly +multiplied, and exhibit such a profusion both of deceptive resemblances, +and of differences which disappear by transformations, that +classification no longer knows which way to turn. Worms, crustaceans, +mollusks; to which group do these and those belong? To which ever we +like to refer them, for these groups represent nothing definitely +determined in the plan of creation; and though easy to be distinguished +from each other in the higher branches, they become confused together +in the lower, like mountain summits which spring from a common base, +at the foot of which they are all united together. + +On this account, my dear child, you will, I am sure, excuse me now and +henceforth, from entering into details of all the horrible beasts which +swarm in the shallows of the animal world, and whom learned men have +in their wonderful wisdom muffled up in terrible names, in order to +prevent children from coming near them! What would you have thought +of the poor little squilla, so prettily baptised by the fishermen, if +I had taught you that it belonged to the order of _Stomatopoda_? +You will scarcely be able to pronounce the word; but that is no fault +of mine, it is spelt so. + +We will content ourselves, then, with having taken a glance at the +most clearly marked individuals; and as I said to you just now, it is +by them that we will arrange our inventory of the groups. Here, as you +may have already remarked, instead of continuing to wander from the +original model whose gradual deterioration we have been following all +this time from one class to another, it would seem that we are retracing +our steps, and regaining some portion of the lost ground. This is +because insects, as I have already stated, are an exceptional case--an +idea apart from the great general plan--a by-lane turning off from one +side of the great line of animal creation. + +The crustacean, less perfectly worked out than the insect assuredly, +but more regular, forms, so to speak, the connecting line between that +tiny masterpiece of fancy, so incomplete in its exquisite organisation, +and the shapeless but better constituted lump of the mollusk, who +conceals under his heavy shell the sacred deposit of real organs, those +which we expect to find always and everywhere. An insect outside, +though less refined it is true, a mollusk within, the crustacean reminds +me of what among us is called an _amateur_--that mild lover of +the arts who holds a middle place, as it were, between the artist and +the common citizen. + +I regret that you are not at present quite able to appreciate my +comparison fully: but put it by, in reserve, if possible, in your +memory; you will find out hereafter how just it is, and it will, +perhaps, help to prevent you from always setting the lively, noisy +artist, above the quiet and silent citizen. Let this, however, be +between you and me. If they could hear us talking, neither artist nor +citizen would forgive me, and the amateur still less. + +_Mollusks._ + +There is one mollusk universally well known--namely, the oyster--so +we will choose him for discussion. To look on one's plate at that +little mass of soft, compact substance, one feels inclined to ask what +there can possibly be in common between it and us; and if you were to +declare that there was not the faintest trace of resemblance between +the organization of the oyster and our own, I should not be surprised. +Wiser people than you have been caught tripping there; not that they +were ignorant of the points in which the oyster resembled us, but they +paid no attention to them. Viewing it in other respects, they declared +that it was of a structure completely different to our own; and that, +in the construction of this machine, the Creator had worked upon a +particular plan, laid aside afterwards as useless for any other purpose. + +I should like to get hold of one of those Academicians, with thirty-six +plans, and confound him before you, in proof of his relationship to +the oyster, by showing you at one sitting that there is an oyster in +himself; nay, further, that he is nothing but an oyster, revised, +amended, and considerably enlarged. And do not imagine that I am only +using a figure of speech here, as the professors of rhetoric call it; +which would be in bad taste: I am speaking literally, and to prove the +existence of the oyster in question in our Academician, I shall only +ask permission to perform a slight operation upon him. You exclaim at +this; but do not alarm yourself, for it is only an operation on paper, +he will not die from it. See now, I cut off his head, his two arms, +and his legs; I take out of his body the vertebral column and the ribs; +I gently place what remains between two shells; and ... there is my +oyster. I willingly admit that it is more carefully elaborated and +richer in details than its sisters in the oyster beds; but all the +principal organs are to be found in them also, and they positively are +beings of a similar construction: you shall judge for yourself. + +The mouth--for there is a mouth, though one must look closer than the +oystermen do to discover it--the mouth is exactly what the gullet +(oesophagus) would be in a man whose head had been cut off; that is, +a truncated tube. Then comes the stomach, situated in the very midst +of the liver; which latter may easily be distinguished, even by the +most cursory glance at luncheon, from its dark color. The intestine +also goes right through the liver, doubling backwards and forwards +several times: and thus the digestive tube supplies itself with bile +from the cask (to borrow a commercial expression); and this saves the +expense of a bile-duct (choledochian canal), which would be an +unnecessary mode of conveyance in this case. The animal lives in water; +consequently, instead of lungs he has gills: [Footnote: The land-snail +has lungs.] these are those thin, finely-streaked plates which make +a fringe at the very edge of the shell. Finally, on leaving the gills +the blood is received by an arterial heart, with only one ventricle +like that of the crustaceans, in the shape of a small pear, similar +to ours, having an auricle, and an aorta, branching out so as to +distribute the blood throughout the whole body. And now what do we +find here, let me ask you, in this mutilated man, reduced to the soft +portions of the trunk, whom I have been imagining? A heart, with its +arteries; lungs; a liver; an intestine; a stomach and an oesophagus: +that is to say, merely and simply the organs of nutrition. That is +all, or very nearly so. + +As you perceive, then, all the elements of our own feeding-machine lie +between the two shells of a mollusk; in a rough state as yet, it is +true; incomplete, and unruly; as in the case of the intestine, for +instance, which in many of these creatures passes without ceremony +through the heart: but even so they are quite sufficiently indicated +to prevent their being mistaken. Now this machine, it is in vain to +deny it, is the animal itself; but it lives at first, and it is this +which dies in it last. The other matter (the locomotive power), +important as it may seem to us in higher races, only holds a secondary +position in reality: the proof of which is, that here is an animal +reduced absolutely to a mere feeding-machine, who still lives, whilst +there yet remains to be found one who has nothing left but his +movement-machine, and who can yet exist. We cannot disown this primitive +animal, for we have it within ourselves; lost, so to speak, in the +midst of the accessory organs which are successively added to it in +proportion as we rise in the animal scale, but still preserving its +own life, its personality, if I may use the expression. Listen to this, +for here is a history well worth hearing. + +I will explain to you, hereafter, how all the actions of the +movement-machine are performed by means of a network of nervous threads +(filaments), whose centre of impulsion is in the brain. How our will +acts upon the brain, and gives its orders to the muscles through the +nervous fibres, I will not offer to explain: it is a fact, let that +suffice us. You say to your foot, "Forward!" and off it starts; "Halt!" +and it stops. Here is an organ under command, a servant of the brain, +where we rule ourselves: with or without explanation, no one will ever +dispute this. The oyster, who has neither head nor brain, has, as his +only instrument of action, certain little masses of nervous substance +scattered right and left, which are called _ganglions_. These +communicate with each other and with the organs by nervous cords, which +are interlaced in all directions, without having any common centre, +and which give the impetus to all parts of the animal. + +Well, the human oyster presents to us exactly the same nervous +organisation. It has its ganglions and its nerves to itself, which are +put into communication with the brain by some threads strayed among +his own, but which are not under its orders, and which treat with it +on equal terms. You remember, perhaps, the little republic talked about +when we first entered the digestive tube; you have now the explanation +of it. This republic is the original animal; it is the feeding-machine. +I cannot describe it, and the kingdom of which you are queen, better +than by comparing them to two States having diplomatic relations with +each other, who exchange dispatches and reciprocal influences; and as +to the importance of these respective influences, if one were to compare +them I scarcely know to which side the balance could incline. + +We shall return elsewhere to this detail, one of the most interesting +of our organisation, and which here finds its natural explanation. For +the present I will content myself with reminding you that, since the +earliest days of human civilisation, all philosophers, all poets, and +all moralists, whether sacred or profane, have borne witness to that +double life within us, that inward being, blind and deaf, whose +disordered impulses so often carry trouble into those higher regions +where will and reason sit enthroned. Behold him taken in his lair at +last, this mysterious being. I have just unveiled his origin to you. +And here, dear child, I must shelter myself behind a profession of +faith. There will not be wanting people to tell you that it is degrading +man far too much to look so low for the sources of his organisation, +and that this sentence--_the human oyster_--which expresses my +idea so well, is neither more nor less than blasphemy. Let them talk, +but adopt their opinion only when they have proved to you that man had +a special Creator, and that the oyster came from a different hand from +ourselves. I should like to know with what face we could venture to +complain, poor worms that we are, because it has seemed good to our +common Father to carry forward in us his previous creations, and in +what respect human dignity would suffer from this contact with a being +who, like us, is one of the works of God. That human pride may suffer +thereby, I admit, and I am glad it should; but if God has included all +creation in His love, we may well include it all in our respect. Whence +comes our superiority at all, but from the gratuitous gifts of Him who +has made us what we are? Is it to lose it, then, to find ourselves +side by side with inferiors whom the Divine benevolence has visited +like ourselves? Surely not. But enough of the oyster, who has never, +that I am aware of, heard such strange discussions sounding in his +ears before. I have no time nor courage now to speak of the other +mollusks, who offer more or less the same system of organs which I +have just described. I must hasten on to the Worms, who give us the +last clue to the great enigma of the animal machine. + + + +LETTER XXXIX. + +VERMES--ZOOPHYTA. (_Worms and Zoophytes_). + +_Worms._ + +The worm of worms, the one you know best, is the earthworm: so he shall +have the honor of representing his group. + +He will not take much time to describe. He is, in brief, a tube, open +at both ends, so as to allow food to come in and go out. That is all. + +I talked to you before about the ruminants, those food-manufacturers +who are employed in cooking victuals for the stomach, and in disengaging +albumen from the coarse materials among which it is apparently lost, +so as to give it out again in a more acceptable form. The ruminant has +other workmen under him, whom I keep in store for you as the last of +the eaters, and who prepare the raw material for him*. These are the +vegetables, who seek out the elements of albumen in earth, water, and +air, those final sources of all alimentation. The earthworm also is +a _preparer_, but in a peculiar way. Look along the garden-walks +in summer-time, after rainy weather: you will see here and there, +little heaps of earth moulded into small sticks, like dough which has +been passed through a tube. [Footnote: M. Mace's account of the +earthworm's life seems founded on the assumption that it extracts its +nourishment from the earth itself, i.e., from inorganic matter, as +_vegetables_ do, to use his own words. But this notion is so +entirely at variance with present received opinions, and also with the +fact that the animal possesses a gizzard for digesting, as well as an +intestinal canal, that it has been necessary to make considerable +alterations in the description. To dismiss his theory of the primitive +animal, etc., altogether, was, however, impossible, without omitting +the whole chapter; but as young heads are not likely to trouble +themselves about it, and it is very innocent in itself, it will do no +harm; subject to this warning, that M. Mace has taken the earthworm +for a more simply organised creature than it really is.--TR.] This is +the damp soil which the worm has passed through his tube, after +extracting from it, during its passage, the various elements of +fertility he requires for the support of his life. This is what makes +him so particularly fond of garden soil, because it is richer in animal +and vegetable matter than common earth, and proves therefore more +nourishing food. The worm, then, feeds on the fat of the earth, which +he converts into azotic aliment for the use of moles, hens and Chinese. +It only figures, it is true, for want of something better, in Chinese +cookery, so profusely hospitable for all that; but the hen doats upon +it, and you do not despise it yourself when it comes back to you in +the form of a chicken's wing, that second transformation of the matter +of which the soil of your garden is composed. It is told of certain +savage tribes, the victims of constant scarcity, that they swallow +little balls of clay in order to keep down their hunger; and during +the great famines in India the distracted inhabitants may, we are told, +be seen digging up the banks of the rivers to feed on the fertile clay +in which the splendid vegetation of their country is developed. This +is a desperate trial of that primeval system of alimentation which +answers perfectly with the worm, but becomes a cruel mockery in the +case of an organisation as exacting as that of man. Let us examine a +little more closely, then, this wonderful tube. + +At first sight one notices, to begin with, that it is composed of +perfectly distinct rings, all quite alike. Inside as well as out each +of these rings is an exact repetition of the other. They are all formed +of circular muscles, enclosed between two coats, which extend from one +to the other. A series of ganglions, arranged in the form of a necklace +along the whole length of the body, set in motion the muscular system +of the rings, each of which possesses its local centre of impulsion. +Each feeds itself in its place from the nourishing juices with which +it is in contact, the interior coat enjoying the double property of +distilling digestive juices and absorbing digested ones. These juices +pass through the muscular partition, and proceed to bathe the outer +coat, which plays, at the same time, the part of coat and lung, and +affords a passage to the air through its soft, damp surface, like that +of gills. From all this results a fine red blood, such as we have not +met with since we left the reptiles, and which is manufactured in all +parts of the body at once. + +Each of these rings, then, the worm's only organs, is a little eating +machine to and for itself, and at the same time a little movement +machine also; in fact, a complete animal. Each one could, if necessary, +nourish itself and live apart; and this is what he really does. Learn +hence, to despise nothing in nature. One tramples an earthworm under +foot, and there below one's heel lies a little revealer of secrets, +whose organisation throws the most unexpected light upon one of the +greatest mysteries in our own life. + +I said to you before, and I felt at the time that it was rather beyond +you, that "each one of our organs is a distinct being, which has its +particular nature and special office, its separate life consequently; +and our individual life is the sum total of all these lesser lives, +independent one of the other, but which nevertheless blend together, +by a mysterious combination, into one common life, which is diffused +everywhere, but can be apprehended nowhere in particular." + +The study of the worm admirably explains this out-of-the-way sentence. +And here observe my adjective--my out-of-the-way--for it is a case in +point. We may call it a literary worm; a worm of four rings, each +perfect in itself, but yet compounded together into a whole with its +own idea. + +That which makes this idea of life most difficult to comprehend is, +that one cannot prove it by a direct experiment, since there is not +one of our organs which could exist separately from the others. Although +independent in their special action, yet these multiplied lives are +nevertheless in a state of absolute and mutual dependence, from the +imperative need they have of each other to make them act, each having +for its share only one particular function, the effect of which extends +to all the others. This is called the division of labor; and if you +still do not understand me clearly, I will explain it in another way. +The heart sends to all the organs--does it not?--the blood, without +which they could not live: separated from the heart, the lungs would +die immediately. It is to the lungs the blood goes to find the air, +without which it could not maintain life. Separated from the lungs, +the heart would die immediately. There is nothing belonging to us which +can avoid the inexorable requirements of blood and air; +consequently, there is nothing which can live an isolated life. + +I will borrow a simile from human society which you will understand +at once. In civilised countries, where division of labor is established, +the tailor makes clothes, the mason makes houses, and the baker makes +bread. If you could throw them each alone by himself into a wood, the +mason would not be able to dress himself, the baker would sleep in the +open air, and the tailor would not know how to make bread. Or rather, +as not one of them can carry on his trade without the co-operation of +a multitude of hands, they could none of them do anything at all. Each +completely independent in his work, yet each dependent upon the others, +both for living, and even for being able to work, our workmen can only +act when they remain bound in close union with the vast society of +which they form a part; and our organs--those other laborers whom you +have seen working for so long--our organs are just in the same +predicament. But in the primitive societies, among savage tribes, where +each man can make his clothes, his house, his bread (when he has any), +and everything else for himself, you might take such an individual if +you liked, and separate him from the rest of the tribe, and he would +go on living as before. And so with the rings of the worm, that +primitive society of organs. Each of them is a universal workman, who +knows how to make everything. Separate him from his fellows, it will +not disturb him at all, and he will go on living as if nothing was +thematter. + +I still remember some profound reflections I indulged in one day some +years ago whilst leaning on my spade and looking at a worm that I had +just cut in two, and whose two halves were walking off one on each +side. + +"There was only one creature here just now," I said to myself, "and +now there are two! Have I had power, then, to create one with a stroke +of the spade?" + +I had not then got hold of the key which I now give you, and to which +no possible objection can be raised. If there are two beings after the +stroke of the spade it is because there were two before. Nay, there +were even many more, if we may trust to the "Manual of Zoology" by +Milne Edwards, a very good book, excellent for an old scholar like +myself, and which I have found very useful in my country-home, as it +has enabled me to relate to you one after another the mysterious wonders +of life. + +He says that, "if one cuts an earthworm across into two, three, ten, +or even twenty morsels, each of these morsels will go on living in the +same way as the whole, and will form a new individual." + +Twenty! that seems to me a great many, because, as far as I can trust +to my brief observations as a gardener, it is necessary that some of +the rings should remain united together and afford each other mutual +support, in order to succeed in repairing the bleeding breaches; but +I would much rather believe it than try the operation. My mind is easy +when I am defending the plants that I have sown in my garden from the +gluttonous worm who would rob them of their food; but it would not be +so if I were cutting them up on my table to learn something about them. + +Besides, there is no need of an operation to convince oneself of the +particular life of each ring. There is one worm, well known by name +at least, though happily not to be met with every day, and that is the +tape-worm, who establishes himself in the intestine of man, and lives +on the chyme, as the other worm does on garden-mould. They call him +the _Solitary_ worm in France; and if ever one might suppose a +creature appropriately named, it would surely be him; for certainly +there is not much society to be looked for in the dwelling he chooses +for himself! But it happens that this pretended _solitary_ worm, +with his unlimited chain of rings, is only a long row of perfectly +distinct beings, so distinct indeed that, from time to time, some of +the rings let themselves go, fall off like ripe fruit, and go away to +live elsewhere, ready to become the nucleus of a new set, if a happy +accident carries them into another intestine, the only place favorable +to their development. + +At last, then, here is a corner of the curtain raised; here we see the +associated organs which constitute an animal, living for once a life +positively and in all respects their own. We are now satisfied about +this; and when at another time we find them bound together in the +chains of a union too ingenious to be severed with impunity--which we +shall discover by seeing their action stop at the moment of +separation--we shall know the cause. + +Do not think, my dear child, that a wretched earthworm can prove nothing +as regards other creatures. The worm is the starting-point of all the +organisations which come after him. Of what is he composed? Of a +tubewhich is itself composed of rings. Well, it is upon this very tube +that the whole animal machine has been founded: and these rings, as +they expand and modify themselves in a thousand different ways, give +birth to all those varieties of being which drive classifiers to +despair, because they will not understand that there ought only to be +one animal, since there is only one Creator of animals. Now, this +animal is a digestive tube served by organs; it is a worm, _i.e.,_ +which goes on constantly embellishing itself. I said to you long ago, +and at a time when you scarcely knew anything, "Have you ever observed +a worm or a leech in motion? You see a successive swelling up of the +whole surface of its body as the creature gradually pushes forward, +as if there was something in its inside rolling along from the tail +to the head. Such is precisely the appearance which the oesophagus +would present to you as the food passes down it, if you had the +opportunity of seeing it in action; and this has been called the +_vermicular_ movement, in consequence of its resemblance to the +movement of a worm." + +And afterwards, in speaking of the intestine: + +"If your body were made of glass, so that you could look through it +to watch the intestine at work, it would appear to you like an enormous +worm, coiled up into a bundle, heaving and moving with all its rings +at once." + +You have now got hold of the secret, namely, that from the beginning +to the end of the digestive tube, its movements are those of a worm. +What a wonder! and that the worm is a digestive tube which can walk. +This worm, or this tube, whichever you please to call it, has never +ceased crawling under our eyes since we began this study. Lost sight +of in man in the midst of the riches he has picked up on his road, +invisible and coiled backward and forward in his palace like an Eastern +despot who leaves everything to be done by his slaves; behold him here +in his first stage naked, shivering in the air, forced to go off himself +and alone to his pasture--ground! But in the coarse earth with which +he fills himself I can already see the delicate chyme which his numerous +servants will prepare for him later on, and into which the heart-tree +will one day send down its roots--the chyliferous vessels. + +A short time ago I called the oyster the primitive animal, but I was +in too great a hurry. The worm is the real primitive animal. He is to +be found in the oyster, as the oyster is to be found in us; and that +poor little beast is, by comparison, an animal of high pretension, who +would be shocked, I am sure, if he could understand what we are saying, +and heard us assert that he is nothing but an embellished worm. + +_Zoophytes._ + +Two centuries ago it was believed that below the worm, animal life, +properly so called, ceased, and the creatures whom I am about to +introduce you to were supposed to be animated plants rather than living +organisms. Hence their name was especially chosen to express that +double nature by which they were thought to have a share in two kingdoms +at one time--viz., the animal and vegetable--_zoon_ in Greek +meaning animal, and _phuton_ a plant. Zoophytes were set down as +animal plants. + +And although later discoveries have long ago established the fact of +the complete animality of zoophytes, the old name is still in general +use. But you must not let it deceive you. Zoophytes are animals every +inch of them, however low in the organic scale, and although many of +the compound ones imitate the growth of plants and shrubs so exactly +in their mode of spreading that it is only by the closest observation +we can persuade ourselves they do not belong to the vegetable kingdom. +Of these there are the delicate buff-colored, prettily-branched, horny +specimens found on the shore, which make so beautiful a variety in +seaweed pictures among the red and green colors of the real seaweed; +but of these also are those wonderful stony shrubs which grow on the +submerged rocks of islands in warm seas, and the material which you +know so well by the name of coral--the very coral of which the necklaces +and bracelets in the jeweller's window are composed. + +In all cases of compound zoophytes, however, there is one great point +which they have in common with the worm, viz., that there is an +association of distinct lives acting unanimously; or, rather, to the +same end. Plainly as this is seen in the worm, it is still more obvious +in the zoophyte. There is no need here either of cutting them up +yourself or of taking other people's dissecting operations upon trust. +It is enough to use your eyes, with the help, it is true, now and then, +of the microscope's clearer sight. + +You know the old oak-tree which stands on the outskirts of the wood, +and is called among the country folk _the patriarch_? Now, this +is clearly not an individual, but a nation. It is not a tree; it is +a forest. Nay, may I not call it a green field? For this trunk, so +truly venerable from ages of growth that one feels inclined to bow to +it as one goes by, is, in fact, a collection of structures, accumulated +by countless generations of fleeting herbs, _i.e.,_ leaves, not +one of which has lived for the space of a whole year round. Every +spring some thousands and thousands of buds open to the sun; each one, +therefore, affording a passage to a little green point; and this point +is an oak, who comes into the world, like the first oak, the grandfather +who formerly came forth from an acorn, under the form of an herb or +tender leaf, which a sheep might have browsed upon. Yet it is so +thoroughly an oak, that you have only to take out the bud carefully +before it has expanded and fasten it into another one's place upon a +tree of the same family, though of a different species, and it will +produce an oak of the same sort as its old companions, and which will, +as it progresses, look quite a stranger among the indigenous branches. +This is the secret of what the gardeners call _grafting_, and I +advise you to try the operation upon rose-trees, for nothing is more +amusing. When the autumnal frosts set in, all these troops of new +little oaks die, and deliver up their leaves to the wind; but they +leave behind, as their summer's work, a tiny morsel of new wood, upon +which, if you look carefully, you will see a fresh bud dawning--the +hope of the coming season. And thus the great life of the tree is +perpetuated from century to century by an uninterrupted succession of +transient lives, reminding one in all respects of the life of a nation; +and the similitude is complete in the evergreen trees, where the new +leaf makes its appearance before the old one has quitted the stem. + +And such is the life of the great stone trees and shrubs of various +kinds which grow under tropical seas, and whose makers and inhabitants +are the coral polyps, the undoubted heads of the Zoophyte race. + +But before considering the _polypidom,_ or external dwelling +(otherwise called the _coeneciun,_ or "common house"), you must +learn something of its originator, the little _polyp,_ who lives +inside, and belongs to a family so widely spread over the face of the +earth, that there are scarcely any waters, whether salt or fresh, +without them. + +In your own neighborhood, if you know how to look for them, are to be +found on the banks of ponds, or along the borders of streams which lie +sleeping in roadside ditches, extraordinary beings which, a hundred +years and more ago, completely bewildered the good Dutch naturalist +Trembley, who had taken it into his head to study them. Picture to +yourself some very tiny bags made of a kind of jelly; gray, brown, or, +most commonly of all, green in color, always transparent, and fastened +by their base to the stalks of _carex,_ water-lentils, or the +confervas, which grow in still water. A hunter on the watch, this bag +shoots out on all sides a number of slender threads, like so many +whip-lashes, arranged within a circle round the edge of its opening +or mouth; and with these whip-lashes all the animalcules which come +within reach are entwined, stifled, and carried away to the ever-yawning +little gulf, where they are digested in less than no time. Whatever +will not digest comes out afterwards by the way it went in. Of what +becomes of the results of this digestion it is impossible to form an +idea. Were you to cut up the bag and put little morsels of it under +the best microscope possible, you would see positively nothing but +solid jelly, without the least sign of any organisation whatever. But +this is not all. Replace these morsels in the water, and come back +tolook at them at the end of five, twenty, or thirty hours. Each one of +them will have become a perfect bag, ready to multiply itself afresh +if you submit it to the same operation. Sometimes, on some part of the +original bag, there suddenly appears a little raised spot, like that +which came on your baby brother's arm the other day after he had been +vaccinated. What would you have said, if this ugly spot had grown +larger and larger without stopping; if it had assumed legs, arms, and +a head, and so become another baby, growing from the arm of the first +one? Yet this is just what the spots do which come on the bag I have +been telling you of; and people have come across bags of a larger +species still--between one and two inches in size, in fact--which in +this way carried twelve young ones on their backs, if one is allowed +to talk of stomachs having _backs_. You perceive at once that +this commencement of animal life is not even a digestive tube, and +that nothing in it can be found but a stomach, opening straight to the +air above and closed up below. + +It was Reaumur, the originator of the famous thermometer, who gave a +name to the wonderful bags discovered by Trembley. Aristotle had +previously bestowed the title of _polypus_ (many feet) upon a +mollusk outwardly formed upon a similar model [Footnote: This is the +cuttle-fish, called _polypus_ by old naturalists. We shall speak +of it fully hereafter in the history of the movement machine.] with +large whips disposed regularly in a circle round the mouth, and intended +for a similar use, only that they have another function besides; that +of carrying the body along in the capacity of feet by clinging on to +the rocks with their suckers as they go. Reaumur transferred this name +to the newcomers, and called them fresh-water polyps, to the infinite +amusement of Voltaire, who had declared that they were only blades of +grass; a new proof, among many others, that in natural history all the +intellect in the world is not worth a pair of good eyes. + +But it was soon found out that, in collecting these bits of living +jelly near the Hague, Trembley had laid his hands on little beings of +immense importance on the surface of the globe, and that he had +discovered under his microscope the explanation of a mystery which had +spread itself, setting human science at defiance, over some thousands +of square miles. + +I talked to you just now of the jeweller's coral, of which ornaments +so becoming to dark-haired people are made. That is one of the stony +polypidoms I spoke of as stone trees found at the bottom of the sea, +where it grows attached to the rocks in the form of a charming little +shrub, stretching its red branches in all directions. The Greeks, who +were never at a loss, relate that Perseus one day laid down upon the +sea-shore the famous head of Medusa, the sight of which had the property +of turning everything to stone, and that the nymphs, in sport, showed +it to the coral shrubs; a fact which explained everything quite +naturally. Without exactly holding this mythological explanation, +modern philosophers had not got much farther, and coral was still a +puzzle to them, which they were not fond of troubling themselves about; +till, roused by Trembley's revelations, they examined it more carefully, +and discovered in its soft extremities (hitherto unnoticed) those same +living jelly-bags or sacs, with their circlets of legs, or rather arms, +charged with supplying them with food. These were marine polyps, which +grow, like those in fresh water, one upon another, but each in its own +crusty cell; and like the buds of the oak, these buds of the stony +tree form each its special deposit, which it bequeaths in dying to the +general mass. In short, as the tender shoot of the oak is filled by +degrees with the wood which forms within it, and hardens into a branch, +that goes on increasing by perpetually new growths, so the jelly polyp +of the polypidom hardens below into stone and dies incessantly at the +base, while it lives on indefinitely above in its constantly-renewed +summit. + +Do not get tired of all this phantasmagoria, my dear pupil: it is a +matter of the highest interest. Here is the point of junction--the +bond, as it were, between the three kingdoms: an animal growing +vegetable-wise produces a mineral mass, extracted from the waters of +the sea by an infinity of little living crucibles, who carry on under +our eyes the work begun in the first ages of the globe, and quietly +manufacture continents for the use of future generations. This ought +to console you, my dear child, for being little. It is by little things +that God loves to effect what is truly great. He did not seek out the +elephant or the whale to form these worlds; He chose workmen no bigger +than a pin's head. I have spoken to you about jeweller's coral, which +is made into toys or presents for ladies to adorn themselves with; but +its brethren, the madrepores of the Pacific Ocean play a very different +part. They have formed in front of the shores of New Holland a barrier +of reefs three hundred leagues in extent and twenty wide. What are all +our buildings after this?--those pyramids and cathedrals which seem +so gigantic to us? This ever-increasing wave of coral polypidoms will +one day shut against navigators the entrance to one part of the sea's +tropical region; and lands not to be found on the map to-day will then +lie stretched out under the sun, covered with plants and animals; and +this in places where ships now plough the ocean. Know, also, that a +great portion of the soil which we tread under foot has no other origin. +It was manufactured formerly in the sea by infinite myriads of beings, +often infinitely small. Each one, whether polype or shell, produced +its grain of stone, and from all these grains God, who directed their +work, has made our country. + +But it is time to bring this chattering to a close, for it will never +end if I do not force myself to stop. I leave it with regret; but all +these paths through which I have threaded my way one after another +without counting them, have already made a volume which may possibly +be considered too large for you. There are many other zoophytes besides +the coral polypes, and all of them beautiful and curious. They all +inhabit the fertile depths of the waters where God has deposited the +first germs of life. I cannot describe them to you now. But to make +amends, I will give you a piece of advice which will perhaps make some +people stare. Ask your papa to lend you Michelet's book, _The Sea_, +and look there for what is said about the mysterious animals which lie +hid beneath the waves. His book was not written for you as this one +is: and if, in spite of all my good intentions, I have not always +succeeded in being as comprehensible as I meant to be, Michelet, who +never thought about little people when he took up his pen, will +certainly startle you now and then. But do not be disheartened by a +word. You will find there, that which will be forever plain to you, +the poesy of nature, and children comprehend that better than learned +men. + + + +LETTER XL. + +THE NOURISHMENT OF PLANTS. + +One more word before we part about the last of the eaters, about +Vegetables. They will furnish you with a new and very clearly marked +proof of the uniformity of the fundamental conditions to which the +Author of life has subjected all organised beings. + +Let us look once more at this oak, of whose manner of growth I was +obliged to give you a sketch beforehand, in order to show you the ties +which unite it with its immediate neighbors in the animal kingdom. How +does it feed? I need not tell you this. It feeds by its roots, which +suck up in the bosom of the earth the water charged with the juices +which form its nourishment. Are you aware that every large branch had +its subterranean fellow or representative, and that the annual shoot +at the top of the tree is reproduced at the base by fresh fibres, which +extend themselves in the soil of the earth, in proportion as their +sisters above make their way in the air? And thus, by means of organs +ever young, the life and progress of the great association is kept up, +while those members whose day of work is over still remain there as +the supports of the edifice. It is the same with human societies. They +are sustained by what is old, but they live and progress only by what +is young. The sap, then, which is the name given to the moisture or +water sucked in by the young roots, having once got into the cells of +which the tissue of the fibres is composed, passes from one to another, +and travels thus to the top of the tree, where it is wanted by the +leaves. + +There is no obvious machinery here, however, to impel it forward. It +journeys on of itself, as it were, under the action of laws which have +never been satisfactorily explained, but all of which are dependent +on the vital force or life-power of the tree, inasmuch as without it +there is no circulation. One agent, but by no means the principal, or +it would act as well in a dead tree as a living one, is _capillary +attraction_; and, if you wish to know what that is, you have only +to think of what happens to a towel, if you hang it upon a peg, and +leave the end of it soaking in water. Does not the "wet" seem to climb +up it thread by thread, till it is damp from one end to the other? A +little in this way--but these similes are very imperfect, and will not +bear close application--the sap rises in a tree, stealing up branch +by branch; and it is then called _ascending sap_. [Footnote: M. Mace +speaks of this sap as the _blood of the tree_, and of the leaves only as +_lungs_. These statements have been modified so as to meet the fact that +_ascending sap_ consists of, and conveys the raw elements of _food_ to, +the leaves; that in the leaves this food is _digested_, as well as +brought in contact with the air, and that it is thus converted into that +nourishing fluid, the _descending sap_, which certainly plays the part +of steward to the tree as our blood does to us, and therefore may now be +called the blood of the tree. It must be remembered, however, that each +tree has its own sort of steward, as the case of the _Euphorbia_ (quoted +afterwards) plainly shows. The analogy with the more general substance +of blood is therefore not very complete.-TR.] + +It arrives at last at the leaves, which it enters as our food enters +our stomachs, and for the same purpose; for in them takes place, as +in all true stomachs, that process of digestion by which the elements +of the crude sap-food are decomposed from their first condition, and +converted into a nourishing chyle; in each tree of a sort "after its +kind." + +But more than this. Like the outer coat of the earthworm, the coat of +the leaf affords a passage to air and moisture through its surface; +and here, therefore, takes place that mysterious exchange which is +everywhere the essential condition of life. Here is the charcoal-market +as before, only the bargainers have changed parts. The air, which in +the other case received the _carbon,_ delivers it up, now, and +receives oxygen in exchange; exactly the reverse of its traffic with +animals. In other words, the tree inhales through its leaves the +carbonic acid gas thrown into the atmosphere by our lungs. On its own +responsibility it breaks through the alliance between the carbon and +oxygen contracted in our organs; keeps the carbon for its own use, to +restore it to us another day under the form of wood, or, by the aid +of the charcoal-burner, in the pure and simple state of charcoal; and +sets at liberty the oxygen, which once more goes off in search of new +lungs and a fresh alliance. Thus a constant equilibrium is maintained +in the atmosphere; and thus, by a system of perpetual rotation or +everlasting merry-go-round, the same substances serve, indefinitely, +to support life of every opposite description. + +Now there are two things to be remembered in this inverted respiration +of vegetables. In the first place, it occurs only in the parts which +are _green_. Flowers, fruit, the root, and every part of any other +color, do as we do when we breathe; _i.e._ deprive the air of its +oxygen, charging it with carbonic acid instead. For which reason, +by-the-by, we ought not to keep flowers in a bedroom at night. Charming +as they are, they are _poisoners_, and a headache is what we may +fairly expect after sleeping shut in with them in the same room. It +is almost as bad to allow green boughs to remain there either, for, +in the dark, even the green parts cease to purify the air, and begin +like the others to manufacture carbonic acid, at the expense of course +of their carbon, which thus by degrees is used up. Now, as it is the +carbon which constitutes the solid fibres of plants and produces their +green color, they soon become yellow and limp when deprived of light. +You may, perhaps, have wondered why the gardener amused himself with +smothering his poor lettuces by tying them up at top like a knot of +"back hair," instead of letting them grow freely in the air and +sunshine. It is, my dear, to make them more tender and delicate for +you to eat; and those beautiful, crisp, yellow leaves, so delicious +to the tooth, would have been green and tough, had they not slowly and +quietly let out a great portion of their store of carbon in darkness +during the last few days, before being gathered. Even without playing +the gardener, you may assure yourself of this fact in a still more +simple manner. Put a flat board upon the lawn and leave it there for +three days; then take it up again, and you will find just where the +board has prevented the light from reaching the grass, a yellow mark +so distinctly traced as to be seen from the other end of the garden. + +But to return to the sap, which we left undergoing a change from air +and solar influences in the leaves. The ascending sap was to all +appearance only clear water. When it returns from the leaves, charged +with carbon, it is a thick juice having almost the consistency, and +sometimes even the color of milk, and is possessed of properties +altogether new. The most striking example that I can give you of +thedifference of the two states of sap is the Euphorbia of the Canary +Islands, whose digestive or descending sap is a violent poison. When +the natives of the country are accidentally pressed by thirst, they +carefully remove the bark in which the fatal juice circulates, and are +then able to refresh themselves safely by sucking the stem, which +yields only the watery sap sucked from the ground, and as yet unaltered +and harmless. + +Each of these two saps, in fact, has its path distinctly traced for +it: the first rises through the wood, the second descends through the +bark, whence it is called descending sap. If you wish to satisfy +yourself of this, fasten a rather tight knot of pack-thread round a +young branch, and after a time you will see it pine below the knot and +become swollen above it, an unanswerable proof that the nutritive +juices flowed downward through the bark; for the wood inside the branch +will have been uninjured by the strangling pressure. Remember this, +my dear, when you are playing in the garden, and do not injure the +bark of the young trees your father likes so much to see flourishing. +It is by the bark that they are nourished, and you might even kill +them by treating it too roughly. + +And now I must show you how the nutrition is carried on, or, if you +like better, how the tree grows by means of this descending sap. See: +here is a fir tree, which has just been cut down to the ground. Now, +if you like, I will tell you in a moment how old it is. I will even +tell you the age of every branch, little and big ones both, without +making a mistake in a single year; and you know as well as I do that +I am no conjuror. You see these small circles so delicately drawn, as +it were, upon the face of the sawn trunk, each wider than the last, +as if they were composed of a set of tubes, of unequal sizes, fitting +exactly into each other. Now count them; and you will perhaps find +twenty-five; and as each of these circles represents the work of one +year, you will know that the tree is twenty-five years old. In spring, +when the sap begins to move more briskly, it deposits everywhere between +the wood and the bark, from the trunk to the farthest boughs of the +tree, a uniform layer of a thick liquid, which moulds itself exactly +upon the wood already formed. This layer stiffens during the year; it +gets filled with the carbon left in it atom after atom, by each drop +of the descending sap as it goes by, and thus insensibly becoming +organised and hardened. When winter arrives to interrupt the work, it +will have formed two _ligneous, i.e._ woody layers, as they are +called. Of these, one belongs to the wood, and will never move again +so long as the tree lasts, for it will be covered over, and as it were +buried, by the successive layers yet to come; while, on the contrary, +the other (layer) belongs to the bark, and is doomed to find itself +perpetually forced outwards by the fresh layers, which will after a +while insinuate themselves between it and the wood. + +It is for this reason that the bark of old trunks of trees is so deeply +furrowed, and that the dry scales may be picked off the surface without +the slightest injury to the tree. It is part of the original bark, +dead long ago. The old wood also is dead inside, and even when it is +altogether gone, the glad youthful branches growing green in the +sunshine will scarcely find it out! This accounts for those oaks which +time has hollowed without destroying, as those of Allonville in +Normandy, in which mass is said, and which is moreover the greenest +tree in the country. But without going so far, who has not seen those +hollow old willows, sometimes pierced with holes letting in daylight, +yet proudly crowned above by a forest of young boughs, as green and +full of vigor as if the trunk were still in its prime? What was dead +has departed, but all that has life in it remains, and that is enough +for the tree. + +Need I add that the descending sap, this steward of the vegetable, has +also his workmen to supply with materials, as in our case, and that +he is always falling in on his road with organs, all of which want +different things from him? That here a flower has to be formed, there +a fruit, there a leaf, or a bit of wood, and so on: and that a +mysterious intelligence--the same that we have found everywhere +else--presides over all these varied constructions, the materials for +which are mixed together pell-mell, in the imperceptible thread of sap +which oozes from the leaf to the bark? I recollect just as I am about +to conclude, my dear child, that I once told you, you were a small +temple in which God perpetually attests His presence, by a permanent +miracle. You may now henceforth look upon a tree as something more +than a bit of wood, yielding a pleasant shade. God is in it also. + + +CONCLUSION. + +And now, my dear little pupil, to what conclusion do we come from all +this? To that which I announced to you from the first. Throughout the +length and breadth of creation, from the highest to the lowest grade, +every living thing is subject to the same law. Everything eats, and +eats nearly in the same manner, since everywhere the same substances +furnish the feast. I laid down in my first letter that our feeding +machine was reproduced even to the farthest limits of the animal +kingdom, though always becoming more simple as the species descends +in the scale. And afterwards, where we began the study of animals, I +told you that in this machine lay the uniformity of their construction. +Was I not right? and what could I add to all the proofs which have +developed themselves one after another, to establish the fact of this +uniformity of plan in the animal machine, in all its essential points? +And it will be to the lasting renown of the illustrious Geoffroy St. +Hilaire that it was, in the face of all the Academies and under the +fire of very learned indignation, he proclaimed this truth, which one +cannot lose sight of without losing one's way in a crowd of arbitrary +fancies. + +I return, then, to the definition which I gave you in speaking of the +worm, and which is the final word of the ideas I have been endeavoring +to make you understand. _An animal is a digestive tube served by +organs._ + +In the first place it must eat, and for this therefore the Creator +provided first. All the rest came afterwards in order to enable it to +eat more readily, to secure its prey more easily, and to make the most +of it when eaten. The movement machine, therefore, whose history I +have promised you, is only an assistant, and not the principal feature +of the organisation, and it is not by it, therefore, that the question +can be decided, whether God has made three, four, or five animals, or +whether he has only made one. + +And now, my dear little pupil, I will bid you adieu, or rather say as +the French do, "Au revoir," which means "Good-bye till we meet again," +begging you to excuse any awkward expressions that may have escaped +me, as also my having now and then talked about things because they +have interested me, without perhaps sufficiently considering whether +they might have an equal interest for you. Yet, while the pen is still +in my hand, I will not leave you my concluding definition of an animal +without adding a word of explanation. You know nothing about such +matters yourself, but to some people my words might have the air of +a parody upon another definition, applied by those grave gentlemen the +Philosophers to man, whom they have denominated _An intelligence +served by organs_. My definition is applicable only to the animal, +and not to man, observe. Man in the natural, physical machinery of his +body, is very decidedly an animal; yet as certainly is he, by the +divine reflection which shines within him, something much more and +greater; but _what_, is so far beyond the reach of definitionthat I +shall not attempt to give you one. "Man," as Jesus Christ has +said, "lives not by bread alone, but by every word that proccedeth out +of the mouth of God." What it is that is nourished in us by that word, +is precisely what I cannot attempt to define for you; yet I think you +have understood my meaning. + +Go, then, and eat your food in peace, like the pretty little animal +that you are; but do not forget to nourish also the other part of your +being; that indeed which is of the most importance, and which enables +you to ascend to your Creator. + +THE END. + + + +POSTSCRIPT. + +In going through the preceding pages (Part II) with a comparative +anatomist, it became evident that some few popular and other errors +and misconceptions had crept into this portion of M. Mace's usually +clear and accurate work. + +Naturally it was not in his power to verify all the statements he had +to make on so many and such varied subjects, and he appears occasionally +to have trusted to works of old-fashioned or doubtful authority. + +In these cases I have considered it desirable to make such corrections +as should secure the trustworthiness of the descriptions as far as +they pretend to go. + +It would not, however, have been in my power to accomplish this, but +for the kind and efficient aid I have received from a scientific student +of these subjects; and I am glad of this opportunity of acknowledging +how much I am indebted to him for his assistance in making the necessary +alterations, as well as for confirming the correctness of the greater +portion of the work. + +MARGARET GATTY. + +January, 1865. January, 1865. + + + + + + + + + + +End of Project Gutenberg's The History of a Mouthful of Bread, by Jean Mace + +*** END OF THIS PROJECT GUTENBERG EBOOK THE HISTORY OF A MOUTHFUL OF BREAD *** + +***** This file should be named 6970.txt or 6970.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/6/9/7/6970/ + +Produced by Juliet Sutherland, Charles Franks and the +Online Distributed Proofreading Team. + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. Special rules, +set forth in the General Terms of Use part of this license, apply to +copying and distributing Project Gutenberg-tm electronic works to +protect the PROJECT GUTENBERG-tm concept and trademark. Project +Gutenberg is a registered trademark, and may not be used if you +charge for the eBooks, unless you receive specific permission. If you +do not charge anything for copies of this eBook, complying with the +rules is very easy. You may use this eBook for nearly any purpose +such as creation of derivative works, reports, performances and +research. They may be modified and printed and given away--you may do +practically ANYTHING with public domain eBooks. Redistribution is +subject to the trademark license, especially commercial +redistribution. + + + +*** START: FULL LICENSE *** + +THE FULL PROJECT GUTENBERG LICENSE +PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK + +To protect the Project Gutenberg-tm mission of promoting the free +distribution of electronic works, by using or distributing this work +(or any other work associated in any way with the phrase "Project +Gutenberg"), you agree to comply with all the terms of the Full Project +Gutenberg-tm License available with this file or online at + www.gutenberg.org/license. + + +Section 1. General Terms of Use and Redistributing Project Gutenberg-tm +electronic works + +1.A. By reading or using any part of this Project Gutenberg-tm +electronic work, you indicate that you have read, understand, agree to +and accept all the terms of this license and intellectual property +(trademark/copyright) agreement. If you do not agree to abide by all +the terms of this agreement, you must cease using and return or destroy +all copies of Project Gutenberg-tm electronic works in your possession. +If you paid a fee for obtaining a copy of or access to a Project +Gutenberg-tm electronic work and you do not agree to be bound by the +terms of this agreement, you may obtain a refund from the person or +entity to whom you paid the fee as set forth in paragraph 1.E.8. + +1.B. "Project Gutenberg" is a registered trademark. It may only be +used on or associated in any way with an electronic work by people who +agree to be bound by the terms of this agreement. There are a few +things that you can do with most Project Gutenberg-tm electronic works +even without complying with the full terms of this agreement. See +paragraph 1.C below. There are a lot of things you can do with Project +Gutenberg-tm electronic works if you follow the terms of this agreement +and help preserve free future access to Project Gutenberg-tm electronic +works. See paragraph 1.E below. + +1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" +or PGLAF), owns a compilation copyright in the collection of Project +Gutenberg-tm electronic works. Nearly all the individual works in the +collection are in the public domain in the United States. If an +individual work is in the public domain in the United States and you are +located in the United States, we do not claim a right to prevent you from +copying, distributing, performing, displaying or creating derivative +works based on the work as long as all references to Project Gutenberg +are removed. Of course, we hope that you will support the Project +Gutenberg-tm mission of promoting free access to electronic works by +freely sharing Project Gutenberg-tm works in compliance with the terms of +this agreement for keeping the Project Gutenberg-tm name associated with +the work. You can easily comply with the terms of this agreement by +keeping this work in the same format with its attached full Project +Gutenberg-tm License when you share it without charge with others. + +1.D. The copyright laws of the place where you are located also govern +what you can do with this work. Copyright laws in most countries are in +a constant state of change. If you are outside the United States, check +the laws of your country in addition to the terms of this agreement +before downloading, copying, displaying, performing, distributing or +creating derivative works based on this work or any other Project +Gutenberg-tm work. The Foundation makes no representations concerning +the copyright status of any work in any country outside the United +States. + +1.E. Unless you have removed all references to Project Gutenberg: + +1.E.1. The following sentence, with active links to, or other immediate +access to, the full Project Gutenberg-tm License must appear prominently +whenever any copy of a Project Gutenberg-tm work (any work on which the +phrase "Project Gutenberg" appears, or with which the phrase "Project +Gutenberg" is associated) is accessed, displayed, performed, viewed, +copied or distributed: + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + +1.E.2. If an individual Project Gutenberg-tm electronic work is derived +from the public domain (does not contain a notice indicating that it is +posted with permission of the copyright holder), the work can be copied +and distributed to anyone in the United States without paying any fees +or charges. If you are redistributing or providing access to a work +with the phrase "Project Gutenberg" associated with or appearing on the +work, you must comply either with the requirements of paragraphs 1.E.1 +through 1.E.7 or obtain permission for the use of the work and the +Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or +1.E.9. + +1.E.3. If an individual Project Gutenberg-tm electronic work is posted +with the permission of the copyright holder, your use and distribution +must comply with both paragraphs 1.E.1 through 1.E.7 and any additional +terms imposed by the copyright holder. Additional terms will be linked +to the Project Gutenberg-tm License for all works posted with the +permission of the copyright holder found at the beginning of this work. + +1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm +License terms from this work, or any files containing a part of this +work or any other work associated with Project Gutenberg-tm. + +1.E.5. Do not copy, display, perform, distribute or redistribute this +electronic work, or any part of this electronic work, without +prominently displaying the sentence set forth in paragraph 1.E.1 with +active links or immediate access to the full terms of the Project +Gutenberg-tm License. + +1.E.6. You may convert to and distribute this work in any binary, +compressed, marked up, nonproprietary or proprietary form, including any +word processing or hypertext form. However, if you provide access to or +distribute copies of a Project Gutenberg-tm work in a format other than +"Plain Vanilla ASCII" or other format used in the official version +posted on the official Project Gutenberg-tm web site (www.gutenberg.org), +you must, at no additional cost, fee or expense to the user, provide a +copy, a means of exporting a copy, or a means of obtaining a copy upon +request, of the work in its original "Plain Vanilla ASCII" or other +form. Any alternate format must include the full Project Gutenberg-tm +License as specified in paragraph 1.E.1. + +1.E.7. Do not charge a fee for access to, viewing, displaying, +performing, copying or distributing any Project Gutenberg-tm works +unless you comply with paragraph 1.E.8 or 1.E.9. + +1.E.8. You may charge a reasonable fee for copies of or providing +access to or distributing Project Gutenberg-tm electronic works provided +that + +- You pay a royalty fee of 20% of the gross profits you derive from + the use of Project Gutenberg-tm works calculated using the method + you already use to calculate your applicable taxes. The fee is + owed to the owner of the Project Gutenberg-tm trademark, but he + has agreed to donate royalties under this paragraph to the + Project Gutenberg Literary Archive Foundation. Royalty payments + must be paid within 60 days following each date on which you + prepare (or are legally required to prepare) your periodic tax + returns. Royalty payments should be clearly marked as such and + sent to the Project Gutenberg Literary Archive Foundation at the + address specified in Section 4, "Information about donations to + the Project Gutenberg Literary Archive Foundation." + +- You provide a full refund of any money paid by a user who notifies + you in writing (or by e-mail) within 30 days of receipt that s/he + does not agree to the terms of the full Project Gutenberg-tm + License. You must require such a user to return or + destroy all copies of the works possessed in a physical medium + and discontinue all use of and all access to other copies of + Project Gutenberg-tm works. + +- You provide, in accordance with paragraph 1.F.3, a full refund of any + money paid for a work or a replacement copy, if a defect in the + electronic work is discovered and reported to you within 90 days + of receipt of the work. + +- You comply with all other terms of this agreement for free + distribution of Project Gutenberg-tm works. + +1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm +electronic work or group of works on different terms than are set +forth in this agreement, you must obtain permission in writing from +both the Project Gutenberg Literary Archive Foundation and Michael +Hart, the owner of the Project Gutenberg-tm trademark. Contact the +Foundation as set forth in Section 3 below. + +1.F. + +1.F.1. Project Gutenberg volunteers and employees expend considerable +effort to identify, do copyright research on, transcribe and proofread +public domain works in creating the Project Gutenberg-tm +collection. Despite these efforts, Project Gutenberg-tm electronic +works, and the medium on which they may be stored, may contain +"Defects," such as, but not limited to, incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other intellectual +property infringement, a defective or damaged disk or other medium, a +computer virus, or computer codes that damage or cannot be read by +your equipment. + +1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right +of Replacement or Refund" described in paragraph 1.F.3, the Project +Gutenberg Literary Archive Foundation, the owner of the Project +Gutenberg-tm trademark, and any other party distributing a Project +Gutenberg-tm electronic work under this agreement, disclaim all +liability to you for damages, costs and expenses, including legal +fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT +LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE +PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE +TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE +LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR +INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH +DAMAGE. + +1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a +defect in this electronic work within 90 days of receiving it, you can +receive a refund of the money (if any) you paid for it by sending a +written explanation to the person you received the work from. If you +received the work on a physical medium, you must return the medium with +your written explanation. The person or entity that provided you with +the defective work may elect to provide a replacement copy in lieu of a +refund. If you received the work electronically, the person or entity +providing it to you may choose to give you a second opportunity to +receive the work electronically in lieu of a refund. If the second copy +is also defective, you may demand a refund in writing without further +opportunities to fix the problem. + +1.F.4. Except for the limited right of replacement or refund set forth +in paragraph 1.F.3, this work is provided to you 'AS-IS', WITH NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO +WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE. + +1.F.5. Some states do not allow disclaimers of certain implied +warranties or the exclusion or limitation of certain types of damages. +If any disclaimer or limitation set forth in this agreement violates the +law of the state applicable to this agreement, the agreement shall be +interpreted to make the maximum disclaimer or limitation permitted by +the applicable state law. The invalidity or unenforceability of any +provision of this agreement shall not void the remaining provisions. + +1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the +trademark owner, any agent or employee of the Foundation, anyone +providing copies of Project Gutenberg-tm electronic works in accordance +with this agreement, and any volunteers associated with the production, +promotion and distribution of Project Gutenberg-tm electronic works, +harmless from all liability, costs and expenses, including legal fees, +that arise directly or indirectly from any of the following which you do +or cause to occur: (a) distribution of this or any Project Gutenberg-tm +work, (b) alteration, modification, or additions or deletions to any +Project Gutenberg-tm work, and (c) any Defect you cause. + + +Section 2. Information about the Mission of Project Gutenberg-tm + +Project Gutenberg-tm is synonymous with the free distribution of +electronic works in formats readable by the widest variety of computers +including obsolete, old, middle-aged and new computers. It exists +because of the efforts of hundreds of volunteers and donations from +people in all walks of life. + +Volunteers and financial support to provide volunteers with the +assistance they need are critical to reaching Project Gutenberg-tm's +goals and ensuring that the Project Gutenberg-tm collection will +remain freely available for generations to come. In 2001, the Project +Gutenberg Literary Archive Foundation was created to provide a secure +and permanent future for Project Gutenberg-tm and future generations. +To learn more about the Project Gutenberg Literary Archive Foundation +and how your efforts and donations can help, see Sections 3 and 4 +and the Foundation information page at www.gutenberg.org + + +Section 3. Information about the Project Gutenberg Literary Archive +Foundation + +The Project Gutenberg Literary Archive Foundation is a non profit +501(c)(3) educational corporation organized under the laws of the +state of Mississippi and granted tax exempt status by the Internal +Revenue Service. The Foundation's EIN or federal tax identification +number is 64-6221541. Contributions to the Project Gutenberg +Literary Archive Foundation are tax deductible to the full extent +permitted by U.S. federal laws and your state's laws. + +The Foundation's principal office is located at 4557 Melan Dr. S. +Fairbanks, AK, 99712., but its volunteers and employees are scattered +throughout numerous locations. Its business office is located at 809 +North 1500 West, Salt Lake City, UT 84116, (801) 596-1887. Email +contact links and up to date contact information can be found at the +Foundation's web site and official page at www.gutenberg.org/contact + +For additional contact information: + Dr. Gregory B. Newby + Chief Executive and Director + gbnewby@pglaf.org + +Section 4. Information about Donations to the Project Gutenberg +Literary Archive Foundation + +Project Gutenberg-tm depends upon and cannot survive without wide +spread public support and donations to carry out its mission of +increasing the number of public domain and licensed works that can be +freely distributed in machine readable form accessible by the widest +array of equipment including outdated equipment. Many small donations +($1 to $5,000) are particularly important to maintaining tax exempt +status with the IRS. + +The Foundation is committed to complying with the laws regulating +charities and charitable donations in all 50 states of the United +States. Compliance requirements are not uniform and it takes a +considerable effort, much paperwork and many fees to meet and keep up +with these requirements. We do not solicit donations in locations +where we have not received written confirmation of compliance. To +SEND DONATIONS or determine the status of compliance for any +particular state visit www.gutenberg.org/donate + +While we cannot and do not solicit contributions from states where we +have not met the solicitation requirements, we know of no prohibition +against accepting unsolicited donations from donors in such states who +approach us with offers to donate. + +International donations are gratefully accepted, but we cannot make +any statements concerning tax treatment of donations received from +outside the United States. U.S. laws alone swamp our small staff. + +Please check the Project Gutenberg Web pages for current donation +methods and addresses. Donations are accepted in a number of other +ways including checks, online payments and credit card donations. +To donate, please visit: www.gutenberg.org/donate + + +Section 5. General Information About Project Gutenberg-tm electronic +works. + +Professor Michael S. Hart was the originator of the Project Gutenberg-tm +concept of a library of electronic works that could be freely shared +with anyone. For forty years, he produced and distributed Project +Gutenberg-tm eBooks with only a loose network of volunteer support. + +Project Gutenberg-tm eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the U.S. +unless a copyright notice is included. Thus, we do not necessarily +keep eBooks in compliance with any particular paper edition. + +Most people start at our Web site which has the main PG search facility: + + www.gutenberg.org + +This Web site includes information about Project Gutenberg-tm, +including how to make donations to the Project Gutenberg Literary +Archive Foundation, how to help produce our new eBooks, and how to +subscribe to our email newsletter to hear about new eBooks. diff --git a/6970.zip b/6970.zip Binary files differnew file mode 100644 index 0000000..edeb6b8 --- /dev/null +++ b/6970.zip diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..e79dd54 --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #6970 (https://www.gutenberg.org/ebooks/6970) diff --git a/old/7brd110.txt b/old/7brd110.txt new file mode 100644 index 0000000..fa1bb57 --- /dev/null +++ b/old/7brd110.txt @@ -0,0 +1,11666 @@ +Project Gutenberg's The History of a Mouthful of Bread, by Jean Mace + +Copyright laws are changing all over the world. Be sure to check the +copyright laws for your country before downloading or redistributing +this or any other Project Gutenberg eBook. + +This header should be the first thing seen when viewing this Project +Gutenberg file. Please do not remove it. Do not change or edit the +header without written permission. + +Please read the "legal small print," and other information about the +eBook and Project Gutenberg at the bottom of this file. Included is +important information about your specific rights and restrictions in +how the file may be used. You can also find out about how to make a +donation to Project Gutenberg, and how to get involved. + + +**Welcome To The World of Free Plain Vanilla Electronic Texts** + +**eBooks Readable By Both Humans and By Computers, Since 1971** + +*****These eBooks Were Prepared By Thousands of Volunteers!**** + + +Title: The History of a Mouthful of Bread + And its effect on the organization of men and animals + +Author: Jean Mace + +Release Date: November, 2004 [EBook #6970] +[Yes, we are more than one year ahead of schedule] +[This file was first posted on February 18, 2003] + +Edition: 10 + +Language: English + +Character set encoding: ASCII + +*** START OF THE PROJECT GUTENBERG EBOOK THE HISTORY OF A MOUTHFUL OF BREAD *** + + + + +Juliet Sutherland, Charles Franks and the Online Distributed Proofreading Team. + + + + +THE HISTORY OF A MOUTHFUL OF BREAD: +And Its Effect on the Organization of Men and Animals. + +BY JEAN MACE. + +Translated Prom the Eighth French Edition, By Mrs. Alfred Gatty. + + + + +EXTRACTS FROM THE PREFACE TO THE ENGLISH EDITION. + +The volume of which the following pages are a translation, has been +adopted by the _University Commission at Paris_ among their prize +books, and has reached an eighth edition. Perhaps these facts speak +sufficiently in its favor; but as translator, and to some extent editor, +I wish to add my testimony to the great charm as well as merit of the +little work. I sat down to it, I must own, with no special predilection +in favor of the subject as a suitable one for young people; but in the +course of the labor have become a thorough convert to the author's +views that such a study--perhaps I ought to add, so pursued as he has +enabled it to be--is likely to prove a most useful and most desirable +one. + +The precise age at which the interest of a young mind can be turned +towards this practical branch of natural history is an open question, +and not worth disputing about. It may vary even in different +individuals. The letters are addressed to a _child_--in the original +even to a _little girl_--and most undoubtedly, as the book stands, it is +fit for any child's perusal who can find amusement in its pages: while +to the rather older readers, of whom I trust there will be a great many, +I will venture to say that the advantage they will gain in the subject +having been so treated as to be brought within the comprehension and +adapted to the tastes of a child, is pretty nearly incalculable. The +quaintness and drollery of the illustrations with which difficult +scientific facts are set forth will provoke many a smile, no doubt, and +in some young people perhaps a tendency to feel themselves treated +_babyishly_; but if in the course of the babyish treatment they find +themselves almost unexpectedly becoming masters of an amount of valuable +information on very difficult subjects, they will have nothing to +complain of. Let such young readers refer to even a popular +Encyclopaedia for an insight into any of the subjects of the +twenty-eight chapters of this volume--"The Heart," "The Lungs," "The +Stomach," "Atmospheric Pressure,"--no matter which, and see how much +they can understand of it without an amount of preliminary instruction +which would require half-a-year's study, and they will then thoroughly +appreciate the quite marvellous ingenuity and beautiful skill with +which M. Mace has brought the great leading anatomical and physical +facts of life out of the depths of scientific learning, and made them +literally comprehensible by a child. + + * * * * * + +There is one point (independent of the scientific teaching) and that, +happily, the only really important one, in which the English translator +has had no change to make or desire. The religious teaching of the +book is unexceptionable. There is no strained introduction of the +subject, but there is throughout the volume an acknowledgment of the +Great Creator of this marvellous work of the human frame, of the daily +and hourly gratitude we owe to Him, and of the utter impossibility of +our tracing out half his wonders, even in the things nearest to our +senses, and most constantly subject to observation. M. Mace will help, +and not hinder the humility with which the Christian naturalist lifts +one veil only to recognise another beyond. + +It will be satisfactory to any one who may be inclined to wonder how +a lady can feel sure of having correctly translated the various +scientific and anatomical statements contained in the volume, to know +that the whole has been submitted to the careful revision of a medical +friend, to whom I have reason to be very grateful for valuable +explanations and corrections whenever they were necessary. In the same +way the chapter on "Atmospheric Pressure," where, owing to the +difference between French and English weights and measures, several +alterations of illustrations, etc., had to be made, has received similar +kind offices from the hands of a competent mathematician. + + * * * * * + +MARGARET GATTY. + +Ecclesfield, June, 1864. + + + + +NOTE TO THE AMERICAN EDITION. + +In May '66, the seventeenth edition of this work was on sale in Paris. +The date of Mrs. Gatty's preface, it will be observed, is June '64, +and at that time, the eighth French edition only had been reached. +That it should be a popular book and command large sale wherever it +is known, will not surprise any one who reads it: the only remarkable +circumstance about it is, that it should not have been republished +here long ere this. Even this may probably be accounted for, on the +supposition that the title under which the translation was published +in England, was so unmeaning--conveying not the slightest idea of the +contents of the book--that none of our publishers even ventured to +hand it over to their "readers" to examine. + +The author's title, _The History of a Mouthful of Bread_, while +falling far short of giving a clear notion of the entire scope of the +work, is shockingly diluted and meaningless, when translated _The +History of a Bit of Bread!_ + +To the translation of Mrs. Gatty, which is in the main an excellent +one, for she has generally seized upon the idea of the author and +rendered it with singular felicity, it may be very properly objected +that she has taken some liberties with the text when there was any +conflict of opinion between herself and her author, and has given her +own ideas instead of his, which is, probably, what she refers to when +she calls herself "to some extent editor." + +The reader of this edition will, in all these cases, find the thought +of the author and not that of his translator; for the reason that a +careful examination of the original has convinced the publisher that +in every instance the author was to be preferred to the translator, +to say nothing of the right an author may have to be faithfully +translated. + +Besides making these restorations, the copy from which this edition +was printed has been carefully compared with the last edition of the +author and a vast number of corrections made, and in its present shape +it is respectfully submitted and dedicated to every one (whose name +is legion, of course) who numbers among his young friends a "_my +dear child_" to present it to. + + + + + +CONTENTS. + +I.--INTRODUCTION + +FIRST PART MAN. + +II.--THE HAND +III.--THE TONGUE +IV.--THE TEETH +V.--THE TEETH (_continued_) +VI.--THE TEETH (_continued_) +VII.--THE THROAT +VIII.--THE STOMACH +IX.--THE STOMACH (_continued_) +X.--THE INTESTINAL CANAL +XI.--THE LIVER +XII.--THE CHYLE +XIII.--THE HEART +XIV.--THE ARTERIES +XV.--THE NOURISHMENT OF THE ORGANS +XVI.--THE ORGANS +XVII.--ARTERIAL AND VENOUS BLOOD +XVIII.--ATMOSPHERIC PRESSURE +XIX.--THE ACTION OF THE LUNGS +XX.--CARBON AND OXYGEN +XXI.--COMBUSTION +XXII.--ANIMAL HEAT +XXIII.--ACTION OF THE BLOOD UPON THE ORGANS +XXIV.--THE WORK OF THE ORGANS +XXV.--CARBONIC ACID +XXVI.--ALIMENTS OF COMBUSTION +XXVII.--ALIMENTS OF NUTRITION (_continued_)--NITROGEN OR AZOTE +XXVIII.--COMPOSITION OF THE BLOOD + + +SECOND PART. + +ANIMALS. + +XXIX.--CLASSIFICATION OF ANIMALS +XXX.--MAMMALIA (_Mammals_) +XXXI.--MAMMALIA. (_Mammals_)--_continued_ +XXXII.--MAMMALIA--_continued_ +XXXIII.--MAMMALIA--_continued_ +XXXIV.--AVES. (_Birds_) +XXXV.--REPTILIA. (_Reptiles_) +XXXVI.--PISCES. (_Fishes_) +XXXVII.--INSECTA. (_Insects_) +XXXVIII.--CRUSTACEA--MOLLUSKA. (_Crustaceans and Mollusks_) +XXXIX.--VERMES--ZOOPHYTA. (_Worms and Zoophytes_) +XL.--THE NOURISHMENT OF PLANTS +CONCLUSION + + + +I. + +INTRODUCTION. + +I am going to tell you, my dear child, something of the life and nature +of men and animals, believing the information may be of use to you in +after-life, besides being an amusement to you now. + +Of course, I shall have to explain to you a great many particulars +which are generally considered very difficult to understand, and which +are not always taught even to grown-up people. But if we work together, +and between us succeed in getting them clearly into your head, it will +be a great triumph to me, and you will find out that the science of +learned men is more entertaining for little girls, as well as more +comprehensible, than it is sometimes supposed to be. Moreover, you +will be in advance of your years, as it were, and one day may be +astonished to find that you had mastered in childhood, almost as a +mere amusement, some of the first principles of anatomy, chemistry, +and several other of the physical sciences, as well as having attained +to some knowledge of natural history generally. + +I begin at once, then, with the _History of a Mouthful of Bread_, +although I am aware you may be tempted to exclaim, that if I am going +to talk only about that, I may save myself the trouble. You know all +about it, you say, as well as I do, and need not surely be told how +to chew a bit of bread-and-butter! Well, but you must let me begin at +the very beginning with you, and you have no notion what an incredible +number of facts will be found to be connected with this chewing of a +piece of bread. A big book might be written about them, were all the +details to be entered into. + +First and foremost--Have you ever asked yourself _why_ people eat? + +You laugh at such a ridiculous question. + +"Why do people eat? Why, because there are bonbons, and cakes, and +gingerbread, and sweetmeats, and fruit, and all manner of things good +to eat." Very well, that is a very good reason, no doubt, and you may +think that no other is wanted. If there were nothing but soup in the +world, indeed, the case would be different. There might be some excuse +then for making the inquiry. + +Now, then, let us suppose for once that there _is_ nothing in the +world to eat but soup; and it is true that there are plenty of poor +little children for whom there is nothing else, but who go on eating +nevertheless, and with a very good appetite, too, I assure you, as +their parents know but too well very often. Why do people eat, then, +even when they have nothing to eat but soup? This is what I am going +to tell you, if you do not already know. + +The other day, when your mamma said that your frock "had grown" too +short, and that you could not go out visiting till we had given you +another with longer sleeves and waist, what was the real cause of this +necessity? + +What a droll question, you say, and you answer--"Because I had grown, +of course." + +To which I say "of course," too; for undoubtedly it was you who had +outgrown your frock. But then I must push the question further, and +ask--How had you grown? + +Now you are puzzled. Nobody had been to your bed and pulled out your +arms or your legs as you lay asleep. Nobody had pieced a bit on at the +elbow or the knee, as people slip in a new leaf to a table when there +is going to be a larger party than usual at dinner. How was it, then, +that the sleeves no longer came down to your wrists, or that the body +only reached your knees? Nothing grows larger without being added to, +any more than anything gets smaller without having lost something; you +may lay that down as a rule, once for all. If, therefore, nothing was +added to you from without, something must have been added to you from +within. Some sly goblin, as it were, must have been cramming into your +frame whatever increase it has made in arms, legs, or anything else. +And who, do you think, this sly goblin is? + +Why, my dear, it is _yourself!_ + +Ay! Bethink you, now, of all the bread-and-butter, and bonbons, and +gingerbread, and cakes, and sweetmeats, and even soup and plain food +(the soup and plain food being the most useful of all) which you have +been sending, day by day, for some time past, down what we used to +call "the red lane," into the little gulf below. What do you think +became of them when they got there? Well, they set to work at once, +without asking your leave, to transform themselves into something else; +and gliding cunningly into all the holes and corners of your body, +became there, each as best he might, bones, flesh, blood, etc., +etc. Touch yourself where you will, it is upon these things you lay +your hand, though, of course, without recognizing them, for the +transformation is perfect and complete. And it is the same with +everybody. + +Look at your little pink nails, which push out further and further +every morning; examine the tips of your beautiful fair hair, which +gets longer and longer by degrees; coming out from your head as grass +springs up from the earth; feel the firm corners of your second teeth, +which are gradually succeeding those which came to you in infancy; you +have _eaten_ all these things, and that no long time ago. + +Nor are you children the only creatures who are busy in this way. There +is your kitten, for instance, who a few months ago was only a tiny bit +of fur, but is now turning gradually into a grown-up cat. It is her +daily food which is daily becoming a cat inside her--her saucers of +milk now, and very soon her mice, all serve to the same end. + +The large ox, too, of whom you are so much afraid, because you cannot +as yet be persuaded what a good-natured beast he really is, and how +unlikely to do any harm to children who do none to him--that large ox +began life as a small calf, and it is the grass which he has been +eating for some time past which has transformed him into the huge mass +of flesh you now see, and which by-and-by will be eaten by man, to +become man's flesh in the same manner. + +But, further, still: Even the forest trees, which grow so high and +spread so wide, were at first no bigger than your little finger, and +all the grandeur and size you now look upon, they have taken in by the +process of eating. "What, _do trees eat?_" you ask. + +Verily, do they; and they are, by no means, the least greedy of eaters, +for they eat day and night without ceasing. Not, as you may suppose, +that they crunch bonbons, or anything else as you do; nor is the process +with them precisely the same as with you. Yet you will be surprised +hereafter, I assure you, to find how many points of resemblance exist +between them and us in this matter. But we will speak further of this +presently. + +Now, I think you must allow that there are few fairytales more +marvellous than this history of bread and meat turning into little +boys and girls, milk and mice turning into cats, and grass into oxen! +And I call it a _history_, observe, because it is a transformation +that never happens suddenly, but by degrees, as time goes on. + +Now, then, for the explanation. You have heard, I dare say, of those +wonderful spinning-machines which take in at one end a mass of raw +cotton, very like what you see in wadding, and give out at the other +a roll of fine calico, all folded and packed up ready to be delivered +to the tradespeople. Well, you have within you, a machine even more +ingenious than that, which receives from you all the bread-and-butter +and other sorts of food you choose to put into it, and returns it to +you changed into the nails, hair, bones and flesh we have been talking +about, and many other things besides; for there are quantities of +things in your body, all different from each other, which you are +manufacturing in this manner all day long, without knowing anything +about it. And a very fortunate thing this is for you: for I do not +know what would become of you if you had to be thinking from morning +to night of all that requires to be done in your body, as your mother +has to look after and remember all that has to be done in the house. +Just think what a relief it would be to her to possess a machine which +should sweep the rooms, cook the dinners, wash the plates, mend torn +clothes, and keep watch over everything without giving her any trouble; +and, moreover, make no more noise or fuss than yours does, which has +been working away ever since you were born without your ever troubling +your head about it, or probably even knowing of its existence! Just +think of this and be thankful. + +But do not fancy you are the only possessor of a magical machine of +this sort. Your kitten has one also, and the ox we were speaking of, +and all other living creatures. And theirs render the same service to +them that yours does to you, and much in the same way; for all these +machines are made after one model, though with certain variations +adapted to the differences in each animal. And, as you will see +by-and-by, these variations exactly correspond with the different sort +of work that has to be done in each particular case. For instance, +where the machine has grass to act upon, as in the ox, it is differently +constructed from that in the cat which has to deal with meat and mice. +In the same way in our manufactories, though all the spinning-machines +are made upon one model, there is one particular arrangement for those +which spin cotton, another for those which spin wool, another for flax, +and so on. + +But, further: + +You have possibly noticed already, without being told, that all animals +are not of equal value; or, at least, to use a better expression, they +have not all had the same advantages bestowed on them. The dog, for +instance, that loving and intelligent companion, who almost reads your +thoughts in your eyes, and is as affectionate and obedient to his master +as it were to be wished all children were to their parents--this dog +is, as you must own, very superior, in all ways, to the frog, with its +large goggle eyes and clammy body, hiding itself in the water as soon +as you come near it. But again, the frog, which can come and go as it +likes, is decidedly superior to the oyster, which has neither head nor +limbs, and lives all alone, glued into a shell, in a sort of perpetual +imprisonment. + +Now the machine I have been telling you about is found in the oyster +and in the frog as well as in the dog, only it is less complicated, +and therefore less perfect in the oyster than in the frog; and less +perfect again in the frog than in the dog; for as we descend in the +scale of animals we find it becoming less and less elaborate--losing +here one of its parts, there another, but nevertheless remaining still +the same machine to all intents and purposes; though by the time it +has reached its lowest condition of structure we should hardly be able +to recognize it again, if we had not watched it through all its +gradations of form, and escorted it, as it were, from stage to stage. + +Let me make this clear to you by a comparison. + +You know the lamp which is lit every evening on the drawing-room table, +and around which you all assemble to work or read. Take off first the +shade, which throws the light on your book--then the glass which +prevents it smoking--then the little chimney which holds the wick and +drives the air into the flame to make it burn brightly. Then take away +the screw, which sends the wick up and down; undo the pieces one by +one, until none remain but those absolutely necessary to having a light +at all--namely, the receptacle for the oil and the floating wick which +consumes it. + +Now if any one should come in and hear you say, "Look at my lamp," +what would he reply? He would most likely ask at once, "What lamp?"--for +there would be very little resemblance to a lamp in that mere ghost +of one before him. + +But to you, who have seen the different parts removed one after another, +that wick soaked in oil (let your friend shake his head about it as +he pleases) will still be the lamp to you, however divested of much +that made it once so perfect, and however dimly it may shine in +consequence. + +And this is exactly what happens when the machine we are discussing +is examined in the different grades of animals. The ignoramus who has +not followed it through its changes and reductions cannot recognize +it when it is presented to him in its lowest condition; but any one +who has carefully observed it throughout, knows that it is, in point +of fact, the same machine still. + +This, then, is what we are now going to look at together, my dear +little girl. We will study first, piece by piece, the exquisite machine +within ourselves, which is of such unceasing use to us as long as we +do not give it more than a proper share of work to perform. Do you +understand? We will see what becomes of the mouthful of bread which +you place so coolly between your teeth, as if when that was done nothing +further remained to be thought about. We will trace it in its passage +through every part of the machine, from beginning to end. It will +therefore be simply only the _History of a Mouthful of Bread_ I +am telling you, even while I seem to be talking of other matters; for +to make that comprehensible I shall have to enter into a good many +explanations. + +And when you have thoroughly got to understand the history of what you +eat yourself, we will look a little into the history of what other +animals eat, beginning by those most like ourselves, and going on to +the rest in regular succession downwards. And while we are on the +subject, I will say a word or two on the way in which vegetables eat, +for, as you remember, I have stated that they do eat also. + +Do you think this is likely to interest you, and be worth the trouble +of some thought and attention? + +Perhaps you may tell me it sounds very tedious, and like making a great +fuss about a trifle; that you have all your life eaten mouthfuls of +bread without troubling yourself as to what became of them, and yet +have not been stopped growing by your ignorance, any more than the +little cat, who knows no more how it happens than you do. + +True, my dear; but the cat is only a little cat, and you are a little +girl. Up to the present moment you and she have known, one as much as +the other on this subject, and on that point you have therefore had +no superiority over her. But she will never trouble herself about it, +and will always remain a little cat. You, on the contrary, are intended +by God to become something more in intelligence than you are now, and +it is by learning more than the cat that you will rise above her in +this respect. To learn, is the duty of all men, not only for the +pleasure of curiosity and the vanity of being called learned, but +because in proportion to what we learn we approach nearer to the destiny +which God has appointed to man, and when we walk obediently in the +path which God himself has marked out for us, we necessarily become +better. + +It is sometimes said to grown-up people, that it is never too late to +learn. To children one may say that it is never too early to learn. +And among the things which they may learn, those which I want now to +teach you have the double merit of being, in the first place amusing, +and afterwards, and above all, calculated to accustom you to think of +God, by causing you to observe the wonders which He has done. Sure am +I that when you know them you will not fail to admire them; moreover +I promise your mother that you will be all the better, as well as +wiser, for the study. + + + + +FIRST PART.--MAN. + +LETTER II. + +THE HAND. + +At the foot of the mountains, from whence I write to you, my dear +child, when we want to show the country to a stranger, we commence by +making him climb one of the heights, whence he may take in at a glance +the whole landscape below, all the woods and villages scattered over +the plain, even up to the blue line of the Rhine, which stretches out +to the distant horizon. After this he will easily find his way about. + +It is to the top of a mountain equally useful that I have just led +you. It has cost you some trouble to climb with me. You have had to +keep your eyes very wide open that you might see to the end of the +road we had to go together. Now then, let us come down and view the +country in detail. Then we shall go as if we were on wheels. + +And now let us begin at the beginning: + +Well, doubtless, as the subject is eating, you will expect me to begin +with the mouth. + +Wait a moment; there is something else first. But you are so accustomed +to make use of it, that you have never given it a thought, I dare say. + +It is not enough merely that one should have a mouth; we must be able +to put what we want within it. What would you do at dinner, for +instance, if you had no hands? + +The hand is then the first thing to be considered. + +I shall not give you a description of it; you know what it is like. +But what, perhaps, you do not know, because you have never thought +about it, is, the reason why your hand is a more convenient, and +consequently more perfect, instrument than a cat's paw, for instance, +which yet answers a similar purpose, for it helps the cat to catch +mice. + +Among your five fingers there is one which is called the thumb, which +stands out on one side quite apart from the others. Look at it with +respect; it is to these two little bones, covered over with a little +flesh, that man owes part of his physical superiority to other animals. +It is one of his best servants, one of the noblest of God's gifts to +him. Without the thumb three-fourths (at least) of human arts would +yet have to be invented; and to begin with, the art not only of carrying +the contents of one's plate to one's mouth, but of filling the plate +(a very important question in another way) would, but for the thumb, +have had difficulties to surmount of which you can form no idea. + +Have you noticed that when you want to take hold of anything (a piece +of bread, we will say, as we are on the subject of eating), have you +noticed that it is always the thumb who puts himself forward, and that +he is always on one side by himself, whilst the rest of the fingers +are on the other? If the thumb is not helping, nothing remains in your +hand, and you don't know what to do with it. Try, by way of experiment, +to carry your spoon to your mouth without putting your thumb to it, +and you will see what a long time it will take you to get through a +poor little plateful of broth. The thumb is placed in such a manner +on your hand that it can face each of the other fingers one after +another, or all together, as you please; and by this we are enabled +to grasp, as if with a pair of pincers, whatever object, whether large +or small. Our hands owe their perfection of usefulness to this happy +arrangement, which has been bestowed on no other animal, except the +monkey, our nearest neighbor. + +I may even add, while we are about it, that it is this which +distinguishes the hand from a paw or a foot. Our feet, which have other +things to do than to pick up apples or lay hold of a fork, our feet +have also each five fingers, but the largest cannot face the others; +it is not a thumb, therefore, and it is because of this that our feet +are not hands. Now the monkey has thumbs on the four members +corresponding to our arms and legs, and thus we may say that he has +hands at the end of his legs as well as of his arms. Nevertheless, he +is not on that account better off than we are, but quite the contrary. +I will explain this to you presently. + +To return to our subject. You see that it was necessary, before saying +anything about the mouth, to consider the hand, which is the mouth's +purveyor. Before the cook lights the fires the maid must go to market, +must she not? And it is a very valuable maid that we have here: what +would become of us without her? + +If we were in the habit of giving thought to everything, we should +never even gather a nut without being grateful to the Providence which +has provided us with the thumb, by means of which we are able to do +it so easily. + +But however well I may have expressed it, I am by no means sure, after +all, that I have succeeded in showing you clearly, how absolutely +necessary our hand is to us in eating, and why it has the honor to +stand at the beginning of the history of what we eat. + +It still appears to you, I suspect, that even if you were to lose the +use of your hands you would not, for all that, let yourself die of +hunger. + +This is because you have not attended to another circumstance, which +nevertheless demands your notice--namely, that from one end of the +world to the other, quantities of hands are being employed in providing +you with the wherewithal to eat. + +To go on further: Have you any idea how many hands have been put in +motion merely to enable you to have your coffee and roll in the morning? +What a number, to be sure, over this cup of coffee (which is a trifle +in comparison with the other food you will consume in the course of +the day); from the hand of the negro who gathered the coffee crop to +that of the cook who ground the berries, to say nothing of the hand +of the sailor who guided the ship which bore them to our shores. Again, +from the hand of the laborer who sowed the corn, and that of the miller +who ground it into flour, to the hand of the baker who made it into +a roll. Then the hand of the farmer's wife who milked the cow, and the +hand of the refiner who made the sugar; to say nothing of the many +others who prepared his work for him, and I know not how many more. + +How would it be, then, if I were to amuse myself by counting up all +the hands that are wanted to furnish-- + + The sugar-refiner's manufactory, + The milkmaid's shed, + The baker's oven, + The miller's mill, + The laborer's plough, + The sailor's ship? + +And even now is there nothing we have forgotten? Ah, yes! the most +important of all the hands to you;--the hand which brings together +for your benefit the fruits of the labor of all the others--the hand +of your dear mother, always active, always ready, that hand which so +often acts as yours when your own is awkward or idle. + +Now, then, you see how you might really manage to do without those two +comparatively helpless little paws of yours (although there is a thumb +to each), without suffering too much for want of food. With such an +army of hands at work, in every way, to furnish provision for that +little mouth, there would not be much danger. + + +But cut off your cat's fore paws--oh dear! what am I saying? Suppose, +rather, that she has not got any, and then count how many mice she +will catch in a day. The milk you give her is another matter, remember. +Like your cup of coffee, that is provided for her by others. + +Believe me, if you were suddenly left all alone in a wood, like those +pretty squirrels who nibble hazel-nuts so daintily, you would soon +discover, from being thus thrown upon your own resources, that the +mouth is not the only thing required for eating, and that whether it +be a paw or a hand, there must always be a servant to go to market for +Mr. Mouth, and to provide him with food. + +Happily, we are not driven to this extremity. We take hold of our +coffee-biscuit between the thumb and forefinger, and behold it is on +its road--Open the mouth, and it is soon done! + +But before we begin to chew, let us stop to consider a little. + +The mouth is the door at which everything enters. Now, to every +well-kept door there is a doorkeeper, or porter. And what is the office +of a well-instructed porter? Well, he asks the people that present +themselves, who they are, and what they have come for; and if he does +not like their appearance, he refuses them admittance. We too, then, +to be complete, need a porter of this sort in our mouths, and I am +happy to say we have one accordingly. I wonder whether you know him? +You look at me quite aghast! Oh, ungrateful child, not to know your +dearest friend! As a punishment, I shall not tell you who he is to-day. +I will give you till to-morrow to think about it. + +Meanwhile, as I have a little time left, I will say one word more about +what we are going to look at together. It would hardly be worth while +to tell you this pretty story which we have begun, if from time to +time we were not to extract a moral from it. And what is the moral of +our history to-day? + +It has more than one. + +In the first place it teaches you, if you never knew it before, that +you are under great obligations to other people, indeed to almost +everybody, and most of all perhaps to people whom you may be tempted +to look down upon. This laborer, with his coarse smock-frock and heavy +shoes, whom you are so ready to ridicule, is the very person who, with +his rough hand, has been the means of procuring for you half the good +things you eat. That workman, with turned-up sleeves, whose dirty black +fingers you are afraid of touching, has very likely blackened and +dirtied them in your service. You owe great respect to all these people, +I assure you, for they all work for you. Do not, then, go and fancy +yourself of great consequence among them--you who are of no use in any +way at present, who want everybody's help yourself, but as yet can +help nobody. + +Not that I mean to reproach you by saying this. Your turn has not come +yet, and everybody began like you originally. But I do wish to impress +upon you that you must prepare yourself to become some day useful to +others, so that you may pay back the debts which you are now +contracting. + +Every time you look at your little hand, remember that you have its +education to accomplish, its debts of honor to repay, and that you +must make haste and teach it to be very clever, so that it may no +longer be said of you, that you are of no use to anybody. + +And then, my dear child, remember that a day will come, when the revered +hands that now take care of your childhood--those hands which to-day +are yours, as it were--will become weak and incapacitated by age. You +will be strong, then, probably, and the assistance which you receive +now, you must then render to her, render it to her as you have received +it--that is to say, with your hands. It is the mother's hand which +comes and goes without ceasing about her little girl now. It is the +daughter's hand which should come and go around the old mother +hereafter--her hand and not another's. + +Here again, my child, the mouth is nothing without the hand. The mouth +says, "I love," the hand proves it. + + + +LETTER III. + +THE TONGUE. + +Now, about this doorkeeper, or porter, as we will call him, of the +mouth. I do not suppose you have guessed who he is; so I am going to +tell you. + +The porter who keeps the door of the mouth is _the sense of taste_. + +It is he who does the honors of the house so agreeably to proper +visitors, and gives such an unscrupulous dismissal to unpleasant +intruders. In other words, it is by his directions that we welcome so +affectionately with tongue and lips whatever is good to eat, and spit +out unhesitatingly whatever is unpleasant. + +I could speak very ill of this porter if I chose; which would not be +very pleasant for certain little gourmands that I see here, who think +a good deal too much of him. But I would rather begin by praising him. +I can make my exceptions afterwards. + +In the history I am going to give you, my dear child, there is one +thing you must never lose sight of, even when I do not allude to it; +and that is, that everything we shall examine into, has been expressly +arranged by God for the good and accommodation of our being in this +world; just as a cradle is arranged by a mother for the comfort of her +baby. We must look upon all these things, therefore, as so many +presentsfrom the Almighty himself; and abstain from speaking ill of +them, were it only out of respect for the hand which has bestowed them. + +Moreover, there is a very easy plan by which we may satisfy ourselves +of the usefulness and propriety of these gifts--namely, by considering +what would become of us if we were deprived of any one of them. + +Suppose, for instance, that you were totally deficient in the sense +of taste, and that when you put a piece of cake into your mouth, it +should create no more sensation in you than when you held it in your +hand? + +You would not have thought of imagining such a case yourself, I am +aware; for it never comes into a child's head to think that things can +be otherwise than as God has made them. And in that respect children +are sometimes wiser than philosophers. Nevertheless, we will suppose +this for once, and consider what would happen in consequence. + +Well, in the first place, you would eat old mouldy cake with just the +same relish as if it were fresh; and this mouldy cake, which now you +carefully avoid because it is mouldy, is very unwholesome food, and +would poison you were you to eat a great deal of it. + +I give this merely as an instance, but it is one of a thousand. And +although, with regard to eatables, you only know such as have been +prepared either in shops or in your mamma's kitchen, still you must +be aware there are many we ought to avoid, because they would do no +good in our stomachs, and that we should often be puzzled to distinguish +these from others, if the sense of taste did not warn us about them. +You must admit, therefore, that such warnings are not without their +value. + +In short, it is a marvellous fact that what is unfit for food, is +_almost always_ to be recognized as it enters the mouth, by its +disagreeable taste; a further proof that God has thought of everything. +Medicines, it is true, are unpleasant to the taste, and yet have to +be swallowed in certain cases. But we may compare them to +chimney-sweepers, who are neither pretty to look at, nor invited into +the drawing-room; but who, nevertheless, are from time to time let +into the grandest houses by the porters--though possibly with a +grimace--because their services are wanted. And in the same way +medicines have to be admitted sometimes--despite their +unpleasantness--because they, too, have to work in the chimney. Taste +does not deceive you about them, however; they are not intended to +serve as food. If any one should try to breakfast, dine, and sup upon +physic he would soon find this out. + +Besides, I only said _almost_ always, in speaking of unwholesome +food making itself known to us by its nasty taste; for it is an +unfortunate truth that men have invented a thousand plans for baffling +their natural guardian, and for bringing thieves secretly into the +company of honest people. They sometimes put poison, for instance, +into sugar--as is too often done in the case of those horrible green +and blue sugar plums, against which I have an old grudge, for they +poisoned a friend whom I loved dearly in my youth. Such things as these +pass imprudently by the porter, who sees nothing of their real +character--Mr. Sugar concealing the rogues behind him. + +Moreover, we are sometimes so foolish as not to leave the porter time +to make his examination. We swallow one thing after another greedily, +without tasting; and such a crowd of arrivals, coming in with a rush, +"forces the sentry," as they say; and whose fault is it, if, after +this, we find thieves established in the house? + +But animals have more sense than we have. + +Look at your kitten when you give her some tit-bit she is not acquainted +with--how cautiously and gently she puts out her nose, so as to give +herself time for consideration. Then how delicately she touches the +unknown object with the tip of her tongue, once, twice, and perhaps +three times. And when the tip of the tongue has thus gone forward +several times to make observations (for this is the great post of +observation for the cat's porter as well as for ours), she ventures +to decide upon swallowing, but not before. If she has the least +suspicion, no amount of coaxing makes any difference to her; you may +call "puss, puss," for ever; all your tender invitations are useless, +and she turns away. + +Very good; here then is one little animal, at least, who understands +for what end she has received the sense of taste, and who makes a +reasonable use of it. Very different from some children of my +acquaintance, who heedlessly stuff into their mouths whatever comes +into their hands, without even taking the trouble to taste it, and who +would escape a good many stomach-aches, if nothing else, if they were +as sensible as Pussy. + +This is the really useful side of _the sense of taste_; but its +agreeable side, which is sufficiently well known to you, is not to be +despised either, even on the grounds of utility. + +You must know, between ourselves, that eating would be a very tiresome +business if we did not taste what we are eating; and I can well imagine +what trouble mammas would have in persuading their children to come +to dinner or tea, if it were only a question of working their little +jaws, and nothing further. What struggles--what tears! And setting +aside children, who are by no means always the most disobedient to the +will of a good GOD, how few men would care to stop in the midst of +their occupations, to go and grind their teeth one against another for +half-an-hour, if there were not some pleasure attached to an exercise +not naturally amusing in itself? Ay, ay, my dear child, were it not +for the reward in pleasure which is given to men when they eat, the +human race, who as a whole do not live too well already, would live +still worse. And it is necessary that we should be fed, and well fed +too, if we would perform properly here below the mission which we have +received from above. + +Yes, "reward" was the word I used. Now it seems absurd to you, perhaps, +that it should be necessary to reward a man for eating a good dinner? +Well, well, GOD has been more kind to him, then, than you would be. +To every duty imposed by Him upon man, He has joined a pleasure as a +reward for fulfilling it. How many things should I not have to say to +you on this subject, if you were older? For the present, I will content +myself with making a comparison. + +When a mother thinks her child is not reasonable enough to do, of her +own accord, something which it is nevertheless important she should +do, as learning to read, for instance, or to work with her needle, +&c., she comes to the rescue with rewards, and gives her a plaything +when she has done well. And thus GOD, who had not confidence enough +in man's reason to trust to it alone for supplying the wants of human +nature, has placed a plaything in the shape of pleasure after every +necessity; and in supplying the want, man finds the reward. + +You will hardly believe that what I have here explained to you so +quietly by a childish comparison, has been, and alas! still is, the +subject of terrible disputes among grown-up people. If hereafter they +reach your ears, remember what I have told you now, viz., that the +pleasure lodged in the tongue and its surroundings, is a plaything, +but a plaything given to us by GOD; and that we must use it accordingly. + +If a little girl has had a plaything given to her by her mother, would +she think to please her by breaking it or throwing it into a corner? +No, certainly not: she would know that in so doing she would be going +directly against her mother's intentions and wishes. Nevertheless she +would amuse herself with it in play hours, with an easy conscience, +and, if she is amiable, she will remember while she does so, that it +comes to her from her mother, and will thank her at the bottom of her +heart. + +It is the same with man, of whose playthings we are speaking. + +But, moreover, this little girl (it is taken for granted that she is +a good little girl) will not make the plaything the business of her +whole day, the object of all her thoughts; she will not forget +everything for it, she will leave it unhesitatingly when her mamma +calls her. Neither will she wish to be alone in her enjoyments, but +will gladly see her little friends also enjoy similar playthings, +because she thinks that what is good for her must be good for others +too. + +It is thus that man should do with his playthings; but, alas! this is +what he does not by any means always do with them, and hence a great +deal has been said against them. Little girls, in particular, are apt +to fail on this point, and that is how the dreadful word _gluttony_ +came to be invented. For the same reason, also, people get punished +from time to time; such punishments being the consequence of the misuse +I speak of. + +If people who call to see your mamma were, instead of going straight +up stairs to her, to establish themselves at the lodge with the porter, +and stay there chatting with him, do you think she would be much +flattered by their visits? And yet this is exactly what people do who, +when eating, attend only to the porter. He is so pleasant, this porter; +he says such pretty things to you, that you go on talking to him just +as if he were the master of the house, who, meanwhile, has quite gone +out of your head. + +You heap sugar-plums upon sugar-plums, cakes upon cakes, sweetmeats +upon sweetmeats--everything that pleases the porter, but is of no use +whatever to the master of the house. And then what happens? The master +gets angry sometimes, and no wonder. Mr. Stomach grows weary of these +visits, which are of no use to him. He rings all the bells, makes no +end of a noise in the house, and forces that traitor of a porter who +has engrossed all his company, to do penance. You are ill--your mouth +is out of order--you have no appetite for anything. The mamma has taken +away the plaything which has been misused, and when she gives it back, +there must be great care taken not to do the same thing over again. + +I have thought it only right, my dear child, in telling you the history +of eating, to give to this little detail of its beginning, a place +proportioned to your interest in it. You see by what I have said, that +you are not altogether wrong in following your taste; but neither must +it be forgotten that this part of the business is not in reality the +most important; that a plaything is but a plaything, and that the +porter is not the master of the house. + +Now that we have made our good friend's acquaintance, we will wish him +farewell, and I will presently introduce you to his companions of the +antechamber, who are ranged on the two sides of the door, to make the +toilettes for the visitors who present themselves, and to put them in +order for being received in the drawing-room. You will see there some +jolly little fellows, who are also very useful in their way, and whose +history is no less curious. They are called TEETH. + + + +LETTER IV. + +THE TEETH. + +When you were quite little, my dear child, and still a nursling, you +had nothing behind your lips but two little rosy bars, which were of +no service for gnawing an apple, as they were not supplied with teeth. +You had no need of these then, since nothing but milk passed your lips, +neither had your nurse bargained for your having teeth to bite with. +You see that God provides for everything, as I have already said, and +shall often have occasion to point out to you. + +But by degrees the little infant grew into a great girl, and it became +necessary to think of giving her something more solid than milk to +eat; and for this purpose she required teeth. Then some little germs, +which had lain dormant, concealed within the jaws, awoke one after +another, like faithful workmen when they hear the striking of the +clock. Each set to work in his little cell, and with the help of some +phosphorus and some lime, it began to make itself a kind of white +armour, as hard as a stone, which grew larger from day to day. + +You know what lime is; that sort of white pulp which you have seen +standing in large troughs where the masons are building houses, andwhich +they use in making mortar; it is with this that your little +masons build your teeth. + +As to phosphorus, I am afraid you may never have seen any; but you may +have heard it spoken of. It is sold at the druggist's in the form of +little white sticks, about as thick as your finger; they have a +disagreeable, garlicky smell, and are obliged to be kept in jars of +water, because they seize every opportunity of taking fire; so I advise +you, if ever you do see any phosphorus, not to meddle with it--for in +burning, it sticks closely to the skin, and there is the greatest +difficulty in the world in extinguishing it, and the burns it makes +are fearful. I give you this caution, because phosphorus possesses a +very curious property, which might attract little girls. Wherever it +is rubbed, in the dark, on a door, or on a wall, it leaves a luminous +trail of a very peculiar appearance, which has been called +phosphorescent, from the name of the substance which produces it. And +in this way one can write on walls in letters of fire, to the terror +of cowards. Now, come; if you will promise to be very wise, and only +to make the experiment when your mamma is present, I will teach you +how to make phosphorescent lights without having to go to the +druggist's! There is a small quantity of phosphorus in lucifer matches, +which their garlicky smell proves. Rub them gently in the dark on a +bit of wood, and you will see a ray of light which will shine for some +moments. But mind, you must not play at that game when you are alone; +it is a dangerous amusement, and one hears every day of terrible +accidents caused by disobedient children playing with lucifer matches. +And while we are on the subject, let me warn you against putting them +into your mouth. Phosphorus is a poison, and such a powerful one that +people poison rats with bread-crumb balls in which it has been +introduced. + +"Oh dear me! and that poison makes part of our teeth?" + +Exactly so, and it even forms part of all our bones, and of the bones +of all animals; the best proof of which is, that the phosphorus of +lucifer matches has been procured out of bones from the slaughter-house. +One could make it from the teeth of little girls if one could get +enough of them. + +Now I see what puzzles you, and well it may. You are asking yourself +how those little tooth-makers, the gums, get hold of this terrible +phosphorus, which is set on fire by a mere nothing, and which we dare +not put into our mouths; where do they find the lime which I also +protest is not fit to eat, and yet of which we have stores from our +heads to our feet? + +It is very surprising, too, to think of its being forthcoming in the +jaws just when it is wanted there. + +You begin to perceive that there are many things to be learnt before +we come to the end of our history, and that we find ourselves checked +at every step; now listen, for we are coming to something very +important. + +In distant country-seats, where people are thrown entirely upon their +own resources, they must be provided beforehand with all that is +requisite for repairing the building; and there is, accordingly, a +person called a steward, who keeps everything under lock and key, and +distributes to the workmen whatever materials they may require. Thus, +the steward gives tiles to the slater, planks to the carpenter, colors +to the painter, lime and bricks to the mason--the very same lime that +we have in our teeth--in fact, he has got everything that can be wanted +in his storehouse, and it is to him that every one applies in time of +need. + +Now our body also is a mansion, and has its steward too. But what a +steward--how active! what a universal genius I how inefficient by +comparison are the stewards of the greatest lords! He goes, he comes, +he is everywhere at once; and this really, and not as we use the phrase +in speaking of a merely active man: for the _being everywhere at +once_ is in this case, a fact. He keeps everything, not in a +storehouse, but what is far better, in his very pockets, which he +empties by degrees as he goes about, distributing their contents without +ever making a mistake, without stopping, without delaying; and returns +to replenish his resources in a ceaseless, indefatigable course, which +never flags, night nor day. And you can form no idea how many workmen +he has under his orders, all laboring without intermission, all +requiring different things--not one of them pausing, even for a +joke!--not even to say--"Wait a moment;"--they do not understand what +waiting means: he must always keep giving, giving, giving. By and by +we shall have a long account to give of this wonderful steward, whose +name, be it known, if you have not already guessed it, is Blood. + +It is he who, one fine day when he was making his round of the jaws, +found those little germs I spoke of, awake and eager for work; and he +began at once to start them with materials. He knew that phosphorus +and lime were what they needed: he drew phosphorus and lime therefore +out of his pockets,--and, to be very exact, some other little matters +too,--but these were the most important; but I cannot stop to tell you +everything at once. + +Now, where did the blood obtain this phosphorus and lime? + +I expected you to ask this, but if you want everything explained as +we go along, we shall not get very far. In fact, if I answer all your +questions I shall be letting out my secret too soon, and telling you +the end of my story almost before it is begun. + +So be it, however; perhaps you will feel more courage to go on, when +you know where we are going. + +The steward of a country-house distributes tiles, planks, paint, bricks, +lime; but none of these things are his own, as you know; he has received +them from his master: and, in the same way, our steward has nothing +of his own: everything he distributes comes from the master of the +house, and as I have already told you, this master is the stomach. As +fast as the steward distributes, therefore, must the master renew the +stores--and renew them all, for unless he does this, the work would +stop. In proportion as the blood gives out on all sides the contents +of his pockets, the stomach must replenish them, and fill them with +everything necessary, or there would be a revolution in the house. +Now, as there can be nothing in the stomach but what has got into it +by the mouth, it behooves us to put into the mouth whatever is needed +for the supply of our numerous workmen; and this is why we eat. + +I perceive that I have plunged here into an explanation out of which +I shall not easily extricate myself, for I can guess what you are going +to say next. When you began to cut your teeth, you had eaten neither +phosphorus nor lime, as nothing but milk had entered your mouth. + +That is true. Neither then, nor since then, have you eaten those things, +and what is more, I hope you never will. And yet both must have got +into your mouth, for without them your teeth could never have grown. +How are we to get out of this puzzle? + +Suppose now, for a moment, that instead of phosphorus and lime, +thelittle workmen in your jaws had asked the blood for sugar to make the +teeth with. Fortunately this is only a supposition; otherwise I should +be in great fear for the poor teeth: they would not last very long. +Suppose, further, that instead of your eating the lump of sugar which +was destined to turn into a tooth, your mamma had melted it in a glass +of water, and had given it to you to drink; you could not say you had +eaten sugar, and yet the sugar would really have got into your stomach, +and there would be nothing very wonderful if the stomach had found it +out and given it to the blood, and the blood had carried it off to the +place where it was wanted. Now, allowing that the lump of sugar was +very small, and the glass of water very large, the sugar might have +passed without your perceiving it, and yet the tooth would have grown +all the same, and without the help of a miracle. + +And this is how it was. In the milk which you drank as a baby there +were both phosphorus and lime, though in very small quantities. There +were many other things besides; everything of course that the blood +required for the use of its work-people, because at that time the +stomach was only receiving milk, and yet all the work was going on as +usual. + +And therefore, my dear child, whenever in the course of our studies, +you hear me describe such and such a thing as being within us, say +quietly to yourself, "that also was in the milk which nourished me +when I was a baby." + +Of course, the same things are in what you eat now; only now they come +in a form more difficult to deal with, and the labor of detaching them +from the surrounding ingredients is much greater. The whole business +indeed of this famous machine which we are studying consists in +unfastening the links which hold things together, and in laying aside +what is useful, to be sent to the blood divested of the refuse. The +stomach was too feeble in your infancy to have encountered the work +it has to do now. It is for this reason that God devised for the benefit +of little children that excellent nourishment--milk--which contains, +all ready for use, every ingredient the blood wants; and is almost, +in fact, blood ready made. + +Only think, my child, what you owe to her who gave you this nourishment! +It was actually her blood she was giving you; her blood which entered +into your veins, and which wrought within you in the wonderful way +which I have been describing. Other people gave you sugar-plums, kisses, +and toys; but she gave you the teeth which crunched the sugar-plums, +the flesh of the rosy cheeks which got the kisses, and of the little +hands which handled the toys. If ever you can forget this, you are +ungrateful indeed! + +Now, beware of going on to ask me how we know that there are so many +sorts of things in milk, or I shall end by getting angry. Question +after question; why, you might drive me in this way to the end of the +world, and we should never reach the point we are aiming at. We have +already traveled far away from the teeth, concerning which I wanted +to talk to you at this time, but our lesson is nearly over and we have +scarcely said a word about them! One cannot learn everything at once. +Upon the point in question you must take my word; and as you may +believe, I would not run the risk of being contradicted before you, +by those who have authority on the subject. + +Let it suffice you, for to-day, to have gained some idea of the manner +in which the materials which constitute our bodies are manufactured +within us. We have got at this by talking of the teeth; to-morrow, it +may be the saliva, the next day something else. What I have now told +you will be of use all the way through, and I do not regret the time +we have given to the subject. If you have understood that well; the +time has not been lost. + + + +LETTER V. + +THE TEETH _(continued.)_ + +My thoughts return involuntarily to the subject I last explained to +you, my dear child, and I find that I have a great deal to say about +it still. + +You see now, I hope, that we have something else to consult besides +a dainty taste when we are eating; and that if we are to work to any +good purpose we must think a little about this poor blood; who has so +much to do, and who often finds himself so much at fault, when we send +him nothing but barley-sugar and biscuits for his support. It is not +with such stuff as that, as you may well imagine, that he can be enabled +to answer satisfactorily to the constant demands of his little workmen, +and we expose him to the risk of getting into disgrace with them, if +we furnish him with no better provisions. + +And who is the sufferer? Not I who am giving you this information, +most certainly. + +Now, when children hesitate about eating plain food, and fly from beef +to rush at dessert, they act as a man would do who should begin to +build by giving his workmen reeds instead of beams, and squares of +gingerbread instead of bricks. A pretty house he would have of it; +--just think! + +On the contrary, what your mother asks you to eat, my dear little +epicure, is sure to be something which contains the indispensable +supplies for which your blood is craving; for people knew all about +this by experience long before they could explain the why and the +wherefore. But now that you are so much better informed than even the +most learned men were a century ago, pouting and wry faces at table +are no longer excusable, and I should be sadly ashamed of you if I +should hear you continued to make them. + +And this is what I was more particularly thinking of just now, when +I took up my pen again. No doubt it is very amusing to be able to look +clearly into one's frame, and see what goes on inside, but the amusement +anything affords is the least important part of it; you have begun to +find this out already, and you will find it out more and more every +day. What seems to me one of the great advantages of the study we have +begun together is, that at every step you take you will meet with the +most practical and useful instruction, as well as the most unanswerable +reasons for doing what your parents ask you to do every day. + +To obey without knowing why is certainly possible, and may be done +happily enough. But we obey more readily and easily when we understand +the reason for doing so; and a duty which one can satisfy oneself +about, forces itself upon one as a sort of necessity. And what can +throw a stronger light on our duties than a thorough acquaintance with +ourselves? + +It is upwards of two thousand two hundred years ago (and that is not +yesterday, you must own!) since one of the greatest minds of the +world--Socrates--never forget that name--taught his disciples, as a +foundation precept, this apparently simple maxim, "Know thyself." He +meant this, it is true, in a much higher sense than we are aiming at +in these conversations of ours, but his rule is so practical, that +although you have only as yet taken a mere peep into one small corner +of self-knowledge, you find, if I am not much mistaken, that your heart +has beaten once or twice rather faster than it did before. Was I wrong, +in saying from the beginning, that we become better as we grow in +knowledge? Is it not true that you have felt more tenderly than ever +towards her who nourished you with her milk, since I explained to you +the value of milk; and that you have kissed your mother's hand all the +more lovingly since you heard my history of the hand? To tell you the +truth, if you had not done so, I should have been dissatisfied both +with you and myself. + +And wait! While we are talking thus, another thought has come into my +head about hands and nurses, which I must tell you of. + +There is something of the nurse, my child, in those who take the best +fruits of their intellect and heart, and transform them, as it were, +into milk, in order that your infant soul may receive a nourishment +it will be able to digest without too much effort. In this way their +very soul enters into you, and it is but fair that you should reward +them as they deserve. Young as you are, too, you have a recompense in +your power: one more acceptable even than Academic prizes--of which +it is indispensable not to be too avaricious--you can give them your +love. + +Besides, it is not only hands but heads that are at work for you, and +of these many more than you suppose; and your debt of gratitude is as +much due to the one as to the other. + +Perhaps my first letter may have led you to suppose that I was inclined +to laugh at what I called learned men; and they are perhaps a little +to blame for not thinking often enough about little girls; but +nevertheless these men are of the greatest use to them in an indirect +way. You owe them much, therefore, and without them could have known +nothing of what I am teaching you. It is very grand for us, is it not, +to know that there is phosphorus and lime in our teeth? But it took +generations of learned men, and investigations and discoveries without +end, and ages of laborious study, to extract from nature this secret +which you have learnt in five minutes. And whatever others you may +learn hereafter, remember that it is the same story with all. While +profiting, therefore, at your ease, by all these conquests of science, +I would have you hold in grateful recollection those who have gained +them at so much cost to themselves: almost always at the expense of +their fortune, sometimes at the peril of their lives. + +There they are, observe, a little knot of men with no sort of outward +pretension. They speak a language which scares children away. They +weigh dirty little powders in apothecaries' scales; steep sheets of +copper in acid-water; and watch air-bubbles passing through bent glass +tubes, some of which are as dangerous as cannon balls. They scrape old +bones, and slice scraps no bigger than a pin's head. They keep theireyes +fixed for hours upon things they are examining through microscopes +of a dozen glasses, and when you go to see what they are looking at, +you find nothing at all. To see them at work, in what they call their +laboratories, you would say that they were a set of madmen. But at the +end, it is found, some fine day, that they have changed the face of +the earth; have worked revolutions before which emperors and kings bow +in respect; have enriched nations by millions at a time; have revealed +to the human race, divine laws of which it had hitherto been ignorant; +finally, have furnished the means of teaching little boys and girls +some very curious things, which will make them more agreeable as well +as reasonable. And this is a benefit not to be despised, since these +children are destined one day to become fathers and mothers, and so +to govern the next generation; and the better they themselves are +instructed, the better this will be done. + +But now let us go back to the poor teeth, whom we seem to have forgotten +altogether. However, we knew very well that they would not run away +meantime. + +I told you before that it was their business to dress and prepare +whatever was presented to them, but the reception they bestow is not +one which would suit every body's taste, for it consists in being made +mince-meat of And in order to do their work in the best way possible +they divide their labor; some cut up, others tear, and others pound. + +First, there are those flat teeth in front of the two jaws, just below +the nose. Touch yours with the tip of your finger; you will find that +they terminate in sharp-edged blades, like knives. These are called +_incisors,_ from the Latin word _incidere,_ which means to cut, and it +is with them we bite bread and apples, where the first business is to +cut. It is with the same teeth that lazy little girls bite their thread, +when they will not take the trouble to find their scissors; and, by the +by, this is a very bad trick, because by rubbing them one against +another in this manner we wear them out, and, as you will soon discover, +worn-out teeth never grow again. + +The next sort are those little pointed teeth, which come after the +_incisors,_ on each side of both jaws. You will easily find them; +and if you press against them a little, you will feel their points. +If we call the first set the knives of the mouth, we may call these +its forks. They serve to pierce whatever requires to be torn, and they +are called _canine_ teeth, from the Latin word _canis_, a dog, because +dogs make great use of them in tearing their food. They place their paws +upon it, and plunging the canine teeth into it, pull off pieces by a +jerk of the head. Look into the mouth of papa's dog: you will recognize +these teeth by their rather curved points. They are longer than the +rest, and are called fangs. I do not know, after all, why they have +chosen to name these teeth _canine_, as all carnivorous animals have the +same fangs, and in the lion, the tiger, and many other species, they are +much more developed and sharper than in the dog. In cats they are like +little nails. However, the name is given, and we cannot alter it. + +The last teeth, which are placed at the back of the jaw, are called +molars, from the Latin word _mola_, which means a millstone. + +You must be prepared to meet with several Latin words as we go on; but +never mind; this will give you the opportunity of learning a little +Latin, and so of keeping your brother in order, if he ever looks down +upon you because he is learning Latin at school. Formerly, all learned +men wrote in Latin, and as they ruled supreme in all such subjects as +those we are discussing, they gave to everything such names as they +pleased, without consulting the public, who did not just then trouble +their heads about the matter. Now they give Greek names, which can +hardly be called an improvement; but if they ever wish to attract the +attention of little girls they must translate their hard words into +our own language. + +To return to our grinders: they perform the same office as a miller's +millstone; that is to say, they grind everything that comes in their +way. These teeth have flat, square tops, with little inequalities on +the surface, which you can feel the moment you lay your finger on them. +These are the largest and strongest of the three sets, and with them +we even crack nuts, when we prefer the risk of breaking our teeth to +the trouble of looking for the nut-crackers! + +Now, I will answer for it that you cannot explain to me why we always +place what is hard to break between the _molars,_ and never employ +the _incisors_ in the work? And yet everybody does this alike--from +the child to the grown-up man--and all equally without thinking of +what they are doing. + +I will tell you the reason, however, if you will first tell me why, +when you are going to snip off the tip of your thread (which offers +very little resistance), you do it with the point of your scissors; +whereas you put any tough thing which is likely to resist strongly (a +match, for instance) close up to their hinge; particularly if you have +no scruple about spoiling the scissors, by the way! + +If you were a grown-up lad, and I were teaching you natural philosophy, +I should have here a fine opportunity for explaining what is called +_the theory of the lever_. But I think _the theory of the lever_ would +frighten you; so we must get out of the difficulty in some other way. + +I find, however, that I have been joking so much as I went along, that +I have but little space left, and feel quite ashamed of myself. We +seem quite unlucky over these teeth. + +I have already been scolded by people who are not altogether wrong in +accusing me of losing my time in chattering, first of one thing and +then of another. They complain that by thus nibbling at every blade +of grass on the way-side we shall never get to the end of our journey; +and there is some truth in what they say. Still, I will whisper to you +in excuse that I thought we might play truant a little bit while we +were on familiar ground, where naturally you were sure to feel a +particular interest in everything. The hand, the tongue, the +teeth--these are all old friends of yours--and I thought you would +like to hear all about them. By-and-bye we shall be in the little black +hole, and then we shall get on much more rapidly. + + + +LETTER VI. + +THE TEETH _(continued)._ + +I left off at the _molars_, which are the teeth one selects to +crack nuts with; and if I remember rightly, we talked about different +ways of cutting with scissors. + +Let us look at the subject from a distance, that we may understand it +more clearly. Let us imagine a horse drawing a heavy cart slowly along. +Ask it to gallop, and it will answer, "With all my heart! but you must +give me a lighter carriage to draw." And now fancy another flying over +the ground with a gig behind it. Ask it to exchange the gig for the +cart, and it will say, "Yes; but then I shall have to go slowly." + +Whereby you see that with the same amount of strength to work with, +one has the choice of two things: either of conquering a great +resistance slowly, or a slight one quickly. + +And it is partly on this account, dear child, that I teach you so +gradually; for young heads, fresh to the work, are less easily drawn +along than others, and have but a certain amount of strength. + +Hitherto all has been clear as the day. Now take your scissors in your +left hand; hold the lower ring of the handle firmly between your thumb +and closed hand, so that the blade shall remain straight and immovable: +then with your other hand cause the upper ring to go up and down, and +watch the blade as it moves. The whole of it moves at once, and is put +in motion by the same power--viz., your right hand. But the point makes +a long circuit in the air, while the hinge end makes only a very little +one--indeed, moves almost imperceptibly: and, as you may imagine, a +different sort of effort is required from the motive power (your hand) +according as resistance is made at the point or at the hinge. The point +goes full gallop: it is the horse in the gig; the light work is for +him. The hinge moves slowly; it is the cart-horse, and takes the heavy +labor. + +I hope I have made you understand this, for it explains the cracking +of our nut, though you may not suspect it. Move your scissors once +more in the same way. Now, you have before you the pattern of the two +jaws on one side of your face, from the ear to the nose; the upper +one, which never moves (as you may convince yourself by placing a +finger on your upper lip when you either speak or eat), and the lower +one which goes up and down. Two pairs of scissors set points to points +give you the whole jaw. The _incisors_ are at the points, they +gallop up and down, and are worthless for doing hard work; the +_molars_ are at the hinges, and move slowly; and if anything tough +has to be dealt with, it comes to them as a matter of course; hence +they are the nutcrackers. You must own that it is pleasant to reflect +thus upon what we are doing every day, and the next time you see a +stonemason moving stones of twenty times his own weight with his iron +bar, ask your papa to explain to you the principle of the lever. After +what I have told you, you will understand it very readily, or at least +enough of it to satisfy your mind. + +But, besides this power of moving up and down, the lower jaw possesses +another less obvious one, by means of which it goes from right to left. +This is precisely what naughty children make use of when they grind +their teeth: not that I mean this remark for you, for I have a better +opinion of you than to suppose you do such things. Those who make such +bad use of their jaws deserve to lose the power of ever moving them +thus, and then they would find themselves sadly at a loss how to chew +their bread--for their _molars_ would be of but little service +to them in such a case; as it is chiefly by this second action of the +jaw that the food is pounded. Try to chew a bit of bread by only moving +your jaw up and down, and you will soon tire of the attempt. + +One word more to complete my description of the teeth: that portion +of them which is in the jaw is called the _root_; and the _incisors_, +which cannot work hard because, like the gig-horses, they have but +little resisting power, possess only small and short roots; whereas the +_canines,_ whose duty it is to tear the food sideways, would run the +risk of being dragged out and left sticking in the substances they are +at work upon, if they were not well secured; these, therefore, have +roots which go much deeper into the jaw, and in consequence of this they +give us more pain than the others when the dentist extracts them: those +famous _eye-teeth_, which so terrify people on such occasions, are the +_canines_ of the upper jaw, and lie, in fact, just below the eye. + +The _molars_ meanwhile would be in danger of being shaken in the +sideway movement, while chewing: so they do as you would do if you +were pushed aside. Now you would throw out your feet right and left +in order to steady yourself, and thus the molars, which have always +two roots, throw them out right and left for the same purpose. Some +have three, some four, and they require no less for the business they +have to do. + +Above the root comes what is called the crown; that is the part of the +tooth which is exposed to the air; the part which does the work, and +which bears the brunt of all the rubbing. Now, however hard it may be, +it would soon end in being worn out by all this fun if it were not +covered by a still harder substance, which is called _enamel_. +The _enamel_ which forms the coating of china plates, and which +you can easily distinguish by examining a broken plate, will give you +a very exact idea of it. It is this enamel which gives the teeth the +polish and brilliancy we so much admire, and it is desirable to be +very careful of it, not out of vanity, though there is no objection +to a little vanity on the subject, but because the enamel is +the protector of the teeth, and when that is destroyed, you may say good- +bye to the teeth themselves. All acids eat into the enamel, as vinegar or +lemon-juice does into marble; and one of the best means of preserving +this protecting armor of the teeth is never to eat the unripe windfalls +of fruit, which I have seen unreasonable children pick up in orchards +and devour so recklessly. They give sufficient warning, by their +acidity, that they are not fit for food, and when this warning is +neglected, they take their revenge by corroding the enamel of the +teeth; not to speak of the disturbance which they afterwards cause in +the poor stomach. + +I said that without this coating of enamel, the teeth would be +prematurely worn out, the reason of which is, that the teeth have not +the property of growing again, as the nails and hair have. When those +little germs of which I spoke when we began to describe the teeth, +have finished their work, they perish and fall out, like masons who, +when they have built the house, take their departure forever. + +But the "forever" wants explanation. For such stern conditions would +fall hard on very little children, who, not having come to their reason, +cannot be expected to understand the great value of their teeth, and +take all the care they need of them. So to them _a second_ chance +is given. + +Your first teeth, the _milk-teeth_, as they are called, count for +nothing: they are a kind of specimen, just to serve while you are very +young. + +When you are approaching what is called the age of reason, (and this +word implies a great deal, my dear child,) the real teeth, the teeth +which are to serve you for life, begin to whisper among themselves, +"Now, here is a little girl who is becoming reasonable, and who will +soon, or else never, be fit to take charge of her teeth." No sooner +said than done: other masons set to work in other cells, placed under +the first set, and as the permanent teeth keep growing and growing, +they gradually push out the milk-teeth, which were only keeping their +places ready for them till they came. + +This is just your case at present, and you now understand your +responsibility, and how necessary it is to preserve those good teeth +which have placed so generous a confidence in your care of them, and +which, once gone, can never be replaced. + +You have no loss by the exchange; you had twenty-four at first, you +will now have twenty-eight. Twenty-eight, did I say? nay, you will +have thirty-two; but the last four will come later still. The last +_molars_ on each side, above and below, in both jaws, will not +make their appearance till you are grown up. They are a fastidious and +timid set, and will not run any risks; and they are called +_wisdom-teeth_, because they do not appear till we are supposed +to have arrived at years of discretion. Some people do not cut them +before they are thirty, and you will agree that, if they have not +become wise by that time, they have but a very poor chance of ever +being so! + +There is much more still to be said about the teeth; but I think I +have told you quite enough to teach you the importance of these little +bony possessions of yours, which children do not always value as they +deserve, and whose safety they endanger as carelessly as if they had +fresh supplies of them ready in their pockets. If so many skilful +contrivances have been devised for enabling us to masticate our food +properly, it is clear that this process is not an unimportant one. +Those, therefore, who swallow a mouthful after two or three turns, +forget that they are thereby forcing the stomach to do the work the +teeth have neglected to do, and this is very bad economy, I can assure +you. You will see hereafter, when we speak about animals, that by a +marvellous compensation of nature, the power of the stomach is always +great in proportion to the _in_efficiency of the teeth, and that +by the same rule, it is weakest when the jaws are best furnished. Now, +no jaw is more completely furnished than the human one; it is clear, +then, that it should do its own work and not leave it to be done by +those who are less able: and the little girl who, in order to finish +her dinner more quickly, shirks the use of her teeth, and sends food, +half chewed, into her stomach, is like a man who, having two servants, +the one strong and vigorous, the other feeble and delicate, allows the +first to dawdle at his ease, and puts all the hard work on the other. +He would be very unjust in so doing, would he not? And as injustice +always meets with its reward, his work is sure to be badly done. + +Now, the work in question consists in reducing what we eat into a sort +of pulp or liquid paste, from which the blood extracts at last whatever +it requires. But the teeth may bite and tear the materials as they +please, they can make nothing of them but a powder, which would never +turn into a pulp, if during their labors they were not assisted by an +indispensable auxiliary. To make pap for infants what do we add to the +bread after it is cut in little bits? Without being a very clever cook, +you will know that it is water which is wanted. And thus, to assist +us in making pap for the blood, Providence has furnished us with a +number of small spongy organs within the mouth, which are always filled +with water. These are called _salivary glands_. This water oozes +out from them of itself, on the least movement of the jaw, which presses +upon the sponges as it goes up and down. The name of this water, as +I need scarcely tell you, is _saliva_. + +When I call it water, it is not merely from its resemblance; _saliva_ is +really pure water with a little _albumen_ added. Do not be afraid of +that word--it is not so alarming as it appears to be. It means simply +the substance you know as the _white of egg_. There is also a little +soda in the water, which you know is one of the ingredients of which +soap is made. And this explains why the saliva becomes frothy, when the +cheeks and tongue set it in motion in the mouth while we are talking; +just as the whites of egg, or soapy water, become frothy when whipped up +or beaten in a basin. + +But the albumen and the soda have not been added to the saliva, in our +case, merely to make it frothy; that would have been of very little +use. They give to the water a greater power to dissolve the food into +paste, and thus to begin that series of transformations by which it +gradually becomes the fine red blood which shows itself in little drops +at the tip of your finger when you have been using your needle +awkwardly. + +When once minced up by the teeth and moistened by the saliva, the food +is reduced to a state of pulp, and having nothing further to do in the +mouth, is ready to pass forward. But getting out of the mouth on its +journey downwards is not so simple an affair as getting into it by the +_front door_, as it did at first. Swallowing is in fact a complicated +action, and not to be explained in half a dozen words, and I think we +have already chatted enough for to-day. I only wish I may not have tired +you out with these interminable teeth! But you may expect something +quite new when I begin again. + + + +LETTER VII. + +THE THROAT. + +You remember a certain door-keeper, or porter, of whom we have already +spoken a good deal, who resides in the mouth--the sense of taste, I +mean? + +Well, it is a porter's business to sweep out the entrance to a house, +and you may always recognize him in the courtyard by his broom. + +And accordingly our porter too has a broom specially placed at his +service, namely, the tongue; and an unrivalled broom it is--for it is +self-acting, never wears out, and makes no dust--qualities we cannot +succeed in obtaining in any brooms of our own manufacture. + +When the time has come for the pounded mouthful (described in the last +chapter) to travel forward (the teeth having properly prepared it), +the broom begins its work; scouring all along the gums, twisting and +turning right and left, backwards and forwards, up and down; picking +up the least grains of the pulp which have been manufactured in the +mouth; and as the heap increases, it makes itself into a shovel--another +accomplishment one would scarcely have expected it to possess. What +it gathers together thus, rolls by degrees on its surface into a ball, +which at last finds itself fixed between the palate and the tongue in +such a manner that it cannot escape; at which moment the tongue presses +its tip against the upper front teeth, forms of itself an inclined +plane, and--but stop! we are getting on too fast. + +At the back of the mouth, (which is the antechamber, as we said before,) +is a sort of lobby, separated from the mouth by a little fleshy +tongue_let_, suspended to the palate, exactly like those tapestry +curtains which are sometimes hung between two rooms, under which one +is enabled to pass, by just lifting them up. + +If this lobby led only from the mouth to the stomach, the act of +swallowing would be the simplest thing in the world; the tongue would +be raised, the pounded ball would glide on, would pass under the +curtain, and then good-bye to it. Unfortunately, however, the architect +of the house seems to have economized his construction-apparatus here. +The lobby serves two purposes; it is the passage from the mouth to the +stomach, as well as from the nose to the lungs. + +The air we breathe has its two separate doors there--one opening +towards the nose, the other towards the lungs; through neither of which +is any sort of food allowed to pass. But, as you may imagine, the food +itself knows nothing of such spiteful restraints, and it is a matter +of perfect indifference to it through which of the doors it passes. +Not unlike a good many children who, though they are reasonable +creatures, will push their way into places where they have been +forbidden to go; and who can expect a pulpy food-ball to be more +reasonable than a child? It was necessary, therefore, so to arrange +matters that there should be no choice on the subject; that when the +food-ball got into the lobby it should find no door open but its own, +namely, that which led to the stomach. And that is exactly what is +done. + +You have not, perhaps, remarked that in the act of swallowing, something +rises and contracts itself at the same moment in your throat, producing +a kind of internal convulsion which jerks whatever is inside. People +do not think about it when they are eating, because it is an involuntary +action, and their attention is otherwise engaged. + +But try to swallow when there is nothing in your mouth, and you will +perceive what I mean at once. + +Now, imagine our lobby at the back of the throat as a small closet, +with a doorway in its wall, half-way up, the doorway being closed by +a curtain. In the ceiling is a hole, which leads to the nose; in the +floor two large tubes open out; the front one leading to the lungs, +the one behind, to the stomach. + +Now swallow, and I will tell you what happens. The curtain rises up +and clings to the ceiling, and thus the passage to the nose is stopped +up. The lung-tube rises along the wall, and hides itself under the +door, contracting itself, and making itself quite small, as if it +wished to leave plenty of room for the mouthful of food which is about +to pass over it; and, for still greater security, at the very moment +it rises, it pushes against a small trap-door which shuts up its mouth. +No other road remains, therefore, but through the tube which leads to +the stomach; the pulpy mouthful drops straight therein, without risk +of mistake, and when it is once there, everything readjusts itself as +before. + +These are very ingenious contrivances, and I will venture to say that +if we would but study the wonders of the marvellous and varied machinery +which is constantly at work in our behalf within us, we should be much +better employed than in learning things from which no practical good +can be derived. Moreover, we should be ashamed to trust, like the lower +animals, only to our instinct, (which, after all, is much less developed +in us than in them,) for blindly escaping the thousand chances of +destruction that beset a structure so fragile and delicate in its +contrivances as the human body. Besides, it is not only our own +machinery that is entrusted to us, we are liable to be responsible for +that of others, whose development it is our duty to guard and watch; +and how can we do this with a safe conscience, if we are ignorant of +the construction, the action, the laws of all sorts which the great +Artificer has, so to speak, made use of in forming our bodies? + +When you, in your turn, are a mother, you dear little rogue, who sit +there opening wide your bright eyes, and not comprehending a word of +what I am saying, you will be glad that you were taught when you were +little, how your own little girl ought to be managed. You will find +a hundred opportunities of making good use, in her behalf, of what you +and I are learning together, and in the meantime there is no reason +why you should not yourself profit by the knowledge you have gained. + +I am quite sure, for instance, that in repeating to your child the +simple rule of politeness, with which everybody is acquainted, "_Never +talk when you are eating_," you will be very careful to add, "_and +especially when you are swallowing_," for reasons I am about to detail. + +When we want to speak we have to drive the air from the lungs into the +mouth, and our words are sounds produced by this air as it passes +through. This is the reason why I advise you to go on gently, and make +the proper stops in reading aloud: to _take breath_, in fact, as +it is called; otherwise, breath would all at once fail you, and you +would be obliged to stop short in the middle of a sentence and wait +like a simpleton till you had refilled the lungs with air by breathing. +It was for this purpose, also, and not for mere economy's sake, as you +may have thought, that the little cross-road of four doors has been +placed at the back of the mouth, enabling it to communicate at pleasure +with either the lungs or the stomach. It is a dangerous passage for +food-parcels making their way to the stomach; but if you could +substitute for it, as it may have occurred to you to do lately, a +simple tube going directly to the stomach,--behold! you would find +yourself dumb;--a serious misfortune, eh? for a little girl! But come, +I am quizzing too much, so console yourself. I know many grown-up +people who would be at least as sorry as yourself. + +To return to our subject. We have said that, in order to guard against +accidents, the lung-tube is closed at the moment we are about to +swallow. But if by any unlucky chance the air is coming up from the +lungs at the same moment, it must have a free passage. Its tube cannot +help returning to its place; the little trap-door which shuts up the +opening opens whether or no, and then adieu to all the precautions of +good Mother Nature! The mouthful when it drops, falls outside of its +proper tube--that is to say, into the other, which is exactly in front +of it, and we find that we have _swallowed the wrong way_. + +You know what happens in such a case. You cough and cough till you are +torn to pieces, till you grow scarlet, or even blue in the face; till +you lose your breath; till your body trembles; till your eyes start +out of their sockets. Let who will be there, there is no resource but +to hide your face in your handkerchief. The tube, which was only made +for the passage of air, on finding an intruder forcing an entrance, +does its utmost to drive it back through the door. Then the lungs, +which would be destroyed by its getting to them, come to the assistance +of the faithful servant who is struggling for their protection: they +agitate themselves violently, and send forth gusts of air which drive +all before them. Thence arises the cough, and by this means at last +the enemy is thrust out of the mouth, like dust before the wind. And +it is only when the passages are cleared that the storm subsides. But +the commotion is no laughing matter, I assure you; for if one had +swallowed a little _too far_ the wrong way, or if the substance +swallowed had been too heavy for the air-tube, aided by the lungs, to +eject within a certain time, death would have ensued: instances of +which are by no means unknown. Nature does nothing in vain; this is +no case of a man frightened by a mouse. When you find your whole being +concentrating its efforts to one point, and betraying such distress, +at an accident apparently so trifling, you may be sure there is danger, +and real danger too; and if you doubt it, that makes no +difference--happily for you. + +Now you have learned why little girls should not attempt to talk and +swallow at the same time, and, I may add, still less laugh; for +laughingis a kind of somersault, performed by the lungs, and is always +accompanied by the ejectment of a great deal more breath than is +necessary in speaking, so that the jerks it occasions derange still +more the wise provisions made to protect life whenever we swallow +anything, and therefore we are more apt to swallow the wrong way while +laughing than while speaking. + +Need I say that we ought equally to guard against making others laugh +or talk; or exciting, or frightening them, while they are swallowing; +in short, avoid doing anything to create a sudden shock which might +suddenly force the air out of their lungs, and cause them in the same +manner to swallow the wrong way? Politeness requires this from us, and +what I have now said will fix the lesson still more strongly on your +mind. What would become of you if you were to see a person die in your +presence in consequence of some foolish joke, however apparently +innocent? + +Not to conclude with so painful a picture, I will, before we part, +give you the right names of the _curtain_, the _lobby_ or _closet_, and +the _tubes_ of which we have been speaking. + +The curtain is called the _Soft Palate_. + +The lobby, the _Pharynx_. + +The tube which leads to the stomach, the _Aesophagus_. + +The tube leading to the lungs, the _Larynx_. + +The opening of this tube is the _Glottis_, and the little trap-door +which closes it when one swallows, is the _Epiglottis_. + +You must excuse my attempting to explain the meanings of all these +names; it would take me too long to do so. After all, the mere names +are nothing. If I have succeeded in making you understand how all the +different parts act, you may call them what you like. + +Here we will rest. We are now on our way to where we shall see the +large apartments, and be introduced to the master, that head of the +house, whom no one can approach without so many ceremonies. + + + +LETTER VIII. + +THE STOMACH. + +Once in the _oesophagus_ (you remember this is the name of the tube +which leads to the stomach), the mouthful of food has nothing to do but +to proceed on its way. All along this tube there is a succession +of small elastic rings, [Footnote: Properly, _contractile circular +fibres_.] which contract behind the food to force it forward, and +widen before it to give it free passage. They thus propel it forward, +one after another, till it reaches the entrance to the stomach, into +which the last ring pushes it, closing upon it at the same time. + +Have you ever observed a worm or a leech in motion? You see a successive +swelling up of the whole surface of its body, as the creature gradually +pushes forward, just as if there was something in its inside rolling +along from the tail to the head. Such is precisely the appearance which +the _oesophagus_ would present to you, as the food passes down it, if +you had the opportunity of seeing it in action; and this has been called +_the vermicular movement_, in consequence of its resemblance to the +movement of a worm. + +Here I wish to draw your attention to the very important fact, that +this movement is in one respect of a quite different nature from that +of your thumb when you take hold of a bit of bread, or that of your +jaw when you bite with your teeth, or of your tongue, &c., when you +swallow. All these actions belong to yourself, to a certain extent; +they are voluntary, and under your own guidance; that is, you may +perform them or not, as you choose. There is a constant connexion +between you and them, and you knew what I meant at once as I named +each of them in succession. But in speaking of this other movement we +enter upon another world, of which you know nothing. Here is the black +hole of which I spoke. The little rings of the _oesophagus_ perform +their work by themselves, and you have no power in the matter. Not +only do they move independently of you, but were you to take it into +your head to stop them, it would be about as wise a proceeding as if +you were to talk to them. We will speak hereafter, in another place, +of these impertinent servants, who do not recognise your authority, +and with whom we shall have constantly to do, throughout what remains +to be said on the subject of eating. The truth is, your body is like +a little kingdom, of which you have to be the queen, but queen of the +frontiers only. The arms, the legs, the lips, the eyelids, all the +exterior parts, are your very humble servants; at your slightest bidding +they move or keep still: your will is their law. But in the interior +you are quite unknown. There, there is a little republic to itself, +ruling itself independently of your orders, which it would laugh at, +if you attempted to issue them. + +This republic, to make use of another metaphor, is the kitchen of the +body. It is there they make blood, as they know how; putting it to all +sorts of uses for your advantage, it is true, but without your consent. +You are in the position of the lady of a house whose servants have +shut the door of the kitchen in her face that they may carry on their +business after their own fashion, leaving only the housemaid and +coachman at her command. It may be humiliating, perhaps, to be thus +only partially mistress at home; but what can you do, my little +demi-queen? I will tell you: make up your mind to govern the subjects +under your orders as wisely as possible; and, as to the rest, be content +with the only resource left you: viz., that of looking in at the window +of the kitchen to see what goes on there! + +The stomach is the head cook: the president of the internal republic. +He has charge of the stoves; the whole weight of affairs is on his +hands, and he provides for the interests of all. Aesop taught us this, +long ago, in his fable of "The Belly and Members." [Footnote: La +Fontaine's translation is quoted in the French original, where the +name of the fable is "_Messer Gaster_," a more correct title than our +own. _Gaster_ is a Greek word signifying stomach; and it is strictly +_the stomach_ which is _meant_ in the fable. From this comes, too, the +medical term _gastritis_, the name of a disease of the stomach.--TR.] It +is a very good fable, and was wisely appealed to once by a Roman Consul +to appease a disturbance in the State. But the application was not quite +fair in one respect; and since I have started the subject, I will +satisfy myself by explaining to you where it was wrong. The time will +not be wasted, for this fable has furnished information to a great many +people about the economy of their insides, and possibly to you; and I +should like you to know the exact truth of all the particulars alluded +to. Whether Aesop understood them all, I cannot pretend to say; but the +application by the old Roman to the quarrel between the big-wig senators +and the people was on one point decidedly unjust; for there was, as far +as facts are concerned, something to be said on behalf of the stomach, +which Consul Menenius seems not to have thought of. + +When you come to this part of the Roman history you will learn that +the Roman Senate was a large and fat stomach, which did, it is true, +furnish good nourishment to the other members of the State, but kept +the best share for itself. We may say this now without risk of offence, +it having been dead for so long a time. Our stomach is the leanest, +slightest, frailest part of our body. It is master in the sense in +which it is said in the Gospel, "Let him that is first among you be +the servant of the others." It receives everything, but it gives +everything back, and keeps nothing, or almost nothing, for itself. +Between ourselves, Consul Menenius, the advocate of the Senate, had +no business to talk to the poor wretches at Rome of any comparison +between their government and so careful an administrator of the public +good as a human stomach. He should have taken his subject of comparison +from the families of geese or ducks--animals which have no teeth. These +have strong, well-grown stomachs--true Roman senators--whose stoutness +is in proportion to the work given them to do. But man provides his +with work already prepared by chewing, supposing him to have had the +sense to chew it, of course. It was not from a comparison with man, +therefore, that Menenius ought to have got his boasted apologue, which +was but a poor jest on the subject. + +You did not expect, my dear, to come in for a lesson on Roman History +in a discussion on the stomach. But the study of nature is connected +with everything else, though without appearing to be so, and I was not +sorry to give you, incidentally, this proof of the unexpected light +which it throws, as we go along, upon a thousand questions which appear +perfectly foreign to it. Look, for example, at this old fable cited +by Menenius. For the two thousand years and upwards that it has been +in circulation, troops of historians, poets, orators, and writers of +all kinds, have passed it forward from one to the other, without having +troubled themselves to investigate the laws of nature in connection +with the stomach; therefore, not one, that I am aware of, has observed +this small error, so trifling in appearance, so important in reality, +which nevertheless is obvious to the first young naturalist who thinks +the matter over. + +But enough of the Romans. Let us return to our master--the head cook, +if you choose to call him so. + +I was telling you just now that he managed the stoves, and you may +have thought that I was merely using similes, as I am apt to do. But +not so: it is quite true that he cooks; and so now tell me, if you +can, whence he gets his fire to cook with, or rather, to speak more +correctly, who gives it to him? + +Now you are quite puzzled, so I must help you out. + +In the mansion we were talking about some time ago, to whom would anyone +who wanted to light a fire, apply for wood? + +I think you can answer this yourself, for you cannot have forgotten +our famous steward, who gives everything to everybody. But, you will +wonder, I dare say, how the blood can carry wood in his pockets. +Wood? Ay, and real wood too, as we shall soon see: but it is not wood +we are talking about now. The blood has something more to the purpose +than wood in his pockets, for he has heat ready made. So when the +stomach wishes to set to work, it appeals to the blood, which comes +running from all parts of the body, and heats it so effectually that +everything within is really and actually cooked. This is why one feels +a sort of slight shudder down the back when the stomach has a great +deal to do at once, for the blood being called for in a hurry, comes +rushing along in great gushes, and carries with it the heat from the +other parts of the body. + +It is for this reason, too, that it is so dangerous to bathe when the +stomach is at work cooking, because the cold of the water drives +suddenly back all the blood which has accumulated around the little +saucepan, and this causes such a shock in the body that people often +die of it. + +Do not ask me, to-day, where this heat of the blood comes from; we +will speak of that hereafter. But I may tell you at once that our dear +steward is not a bit cleverer in this matter than other people, and +obtains his heat, like the humblest mortal, by burning his wood. Do +not puzzle yourself to find out how. Enough that he burns it as we do, +and by a similar process. + +Well, in one way or another, the master cook has his fire at command. +You know also, already, what it is he has to get cooked; namely, the +pulpy stew, which has begun in the mouth by chewing, and which it is +his business now to finish perfectly. Now see what a cook does who has +got her stew over the fire. She turns and turns it again and again, +and shakes the saucepan from time to time, that the ingredients may +be more thoroughly mixed up together; and this is precisely what is +done by the stomach; for all the time that the cooking is going on, +he swells and contracts himself alternately, after the fashion of those +rings of the _oesophagus_ we were talking about, tossing and tumbling +the food from one side to another, so as to knead it, as it were. + +Again, the cook adds water to her stew from time to time to keep it +moist; and so the stomach pours constantly upon his stew a liquid, +which contains a great deal of water, and which flows in from a quantity +of little holes, sunk in his delicate coats. + +What more? + +The cook puts in a little salt: and this the stomach takes care not +to forget either, for he is a cook who understands his business. In +the liquid of which I am speaking, there is, if not exactly salt as +one sees it at table, at all events the most active part of salt, that +which possesses in the highest degree the property of reducing +everything we eat to a paste; and this is the real reason why we find +all food so insipid which has not been seasoned with salt. As salt +contains a principle essential to the work to be done by the stomach, +some method had to be devised to induce us to provide him with it, and +this method the porter up above has hit upon. He makes a face if we +offer him anything without a little salt on it, as much as to say--"How +can you expect them to cook you properly down below, my good friend, +if you don't bring them proper materials?" + +Upon which hint men have always acted from the beginning; and as far +as we can trace history back, we find them mixing salt with their food, +though without knowing the real reason why. It is the same, too, with +the lower animals. They know nothing of the matter either, but this +does not prevent their having a natural relish for salt, as any one +will tell you who has the charge of cattle; for their stomachs require +for their cooking the very same seasoning as our own, and therefore +their porter above has received the same orders. + +Salt is not the only thing, however, that exists in that liquid in the +stomach. Learned men, after making minute researches, have found in +it another equally powerful material, which is also found in milk. +Therefore cheese, which contains this material as well as salt, is +quite in its place at the end of dinner. It furnishes reinforcements +for the stomach in cooking, and this is why you so often hear people +say that a little cheese helps the digestion. + +The _digestion_! Yes, that is the word I ought to have begun with. +It is the real name of all this cooking; an operation after which I +would defy you to recognise the nice little cakes you have eaten, any +better than your mamma can trace her pretty rosy-cheeked apples in the +jelly which she left on the fire two hours ago. The stomach, as you +see, is very busy quite as long a time as that, and if we have to be +very careful (as I pointed out before) not to disturb him too suddenly +in his work after dinner, it is also important that we should not, +while at dinner, give him more work to do than he is capable of doing. +Although he is the master, he is but a puny fellow, as I have already +pointed out; nevertheless, he works conscientiously, because he knows +that the life of the whole body depends upon his exertions. Some people +even say that in spite of his leanness he strips himself, at each +digestion, of his interior skin, which he sacrifices to his work, and +the fragments of which tend to increase and improve the stew which is +entrusted to his care. Think of this, my dear, whenever a greedy fit +comes over you, and recollect that such a disinterested public +functionary deserves some consideration. Besides, there is serious +danger, quite apart from any question of injustice, in overwhelming +him with work. If your legs are wearied out, you have it in your power +to lie in bed. If your arm is in pain, you can keep it at rest. But +your stomach is like those poor people who have to support their +families by the labor of each day. He, too, labors for others: he has +no right to rest, no right to be ill, therefore; and when he begins +to fail, woe betide you--you will have enough of it. + +Children who have learnt nothing may laugh at all this, but you, my +dear, are beginning to know something, and "science constrains," +_i.e._ it has its claims and requirements. It requires you, to-day, not +to be greedy, to-morrow, something else, and so on, continually, until +you have become quite reasonable and wise. I am sorry for you if this +vexes you, but it was your own wish to learn, and _science constrains_. +Indeed, I will whisper to you in confidence that this is the best excuse +people who are unwilling to learn have to offer for refusing. They do +not know what learning may lead to, and what a pity it would be if they +could no longer be greedy, or ill-natured, or selfish. What would become +of us all in such a case? + + + +LETTER IX. + +THE STOMACH--_(continued)_. + +We made a very long story of the stomach last time, my dear child; +and, after all, I see that there was one thing I forgot to tell +you--viz., what it is like. + +Have you ever seen a bagpiper, I wonder? A man who carries under his +arm a kind of large dark brown bag, which he fills with air by blowing +into it, and out of which he presently forces the same air into a +musical pipe by pressing it gently with his elbow. If you never saw +such a thing, it is a pity; first, because the bagpipe was the national +instrument of our ancestors the Gauls, and is religiously preserved +as such by the Scotch Highlanders and the peasants of Brittany--(two +remnants of that illustrious race, whose history I recommend to your +careful perusal some day); secondly, and it is this fact which has the +greatest interest for us just now, because that large bag, which is +the principal part of the instrument, gives you a very exact idea of +your stomach; for in fact it really and truly _is_ a stomach itself, and +moreover, the stomach of an animal whose interior formation resembles +yours very, very much. + +And who do you suppose is this audacious animal, which presumes to +have an inside so like that of a pretty little girl? Really, I am half +ashamed to name him, for fear you should be angry with me for doing +so. It is--it is the pig! The resemblance is not exactly a flattering +one to you, perhaps, but we are all alike, and it would be worse than +foolish to grumble at being created as we are. Moreover, there is one +difference; the pig, who thinks of nothing but eating, has a very much +larger stomach than we have, which is some consolation, at any rate. + +Place the palm of your right hand on what is called the pit of the +stomach, turning the ends of the fingers towards the heart; your hand +will nearly cover the space usually occupied by the stomach, and you +may figure it to yourself as a rounded and elongated bag, bigger above +than below, making a very decided bend inside as it descends from the +heart downward; something like one of those long French pears, called +"Bon-chretiens," if it were bent in the middle, and the big end of it +were placed next the heart. As for the exact size of the bag, there +is no telling it, for it depends upon circumstances. It is a very +convenient bag in that respect; just such a one as you would like to +have in your frock for a pocket; only there would be a danger of your +being tempted to put too many things into it. For as you fill it, it +expands, and enlarges itself like an indian-rubber ball, which, though +only the size of an egg to begin with, becomes as big as your head if +you blow hard into it. Then, as it gets empty, it recovers itself, +diminishing gradually in size in plait-like contractions. + +When people remain too long without eating, they have, as they say, +twinges in the stomach. This is because the stomach, becoming by degrees +quite empty, and contracting more and more, the surrounding parts which +were sustained by it, lose their support, and strain at their ligaments, +which now have all the weight to bear. Careless people, who do not +think of such things, are reminded by the twinging pains that it is +time to eat, just as a careless servant is called to order by the bell +of which his master has pulled the string. + +In your case, my dear child, such warnings are soon attended to, and +you have not always even to wait till they come. But there are hundreds +of miserable beings who are warned to no purpose, who cannot obey the +master when he calls for his rations, because they have nothing to +give him; and when this forced disobedience lasts too long, they end +by dying of it. In cases like these, when human beings thus cruelly +perish, the stomach is found to be contracted till it is scarcely +bigger than one's finger. + +On the other hand, a man once died suffocated from excess of food, +after one of those great public dinners, which last four, six, or more +hours--one can scarcely say correctly how long--and the doctors who +examined him found his stomach so prodigiously enlarged that it alone +occupied more than one-half of his inside. As you perceive, therefore, +the stomach has, properly speaking, no fixed size. Its size depends +upon what there is in it. It is like those men whose manners go up and +down with their fortunes; who seem very grand people when their pockets +are well filled, but become very small ones when their purses are +empty. There is, nevertheless, this difference between them, that such +men are fools, because they are men, and not _bags_; whereas the +stomach is a sensible bag, fulfilling with intelligence the duties of +its character as a bag. It is very fortunate for us that it is ready +to change its size, according to the caprices of our appetite; and +dressmakers would do well if they could get a hint from it how to +improve their style of pockets, which certainly cannot have cost their +inventors any very great effort of imagination! + +The way in which this extraordinary pocket empties itself is not less +curious than the rest. As long as digestion is going on, the stomach +is firmly closed at each end; at the upper one by the last ring of the +_aesophagus_, and at the lower by another ring of the same kind, +only stronger; the watchful guardian of the passage which leads to the +intestines. This ring is called the _pylorus_. + +For once, here is a name which agrees with our method of describing +the human machine, and I have much pleasure in translating it to you, +although it is a Greek word. _Pylorus_ is the Greek for a porter; +and our ring is indeed a porter like the one of which we have already +said so much, and which I called last time the _porter up above_, +in anticipation of his colleague below. + +The porter up above presides at the entrance; the one below at the +exit, and both for the same purpose, namely, to _taste._ [Footnote: +It would be absurd to say so in the common acceptation of the term; +but according to No. 1 of Mr. Mayo's "Classification of the impressions +produced by substances taken into the fauces," viz., _"Where +sensations of_ touch _alone are produced, as by rock-crystal, +sapphire, or ice,"_ the word taste may be applied to the +discriminating faculty of the _Pylorus_.--TR.] + +It may well astonish you, that you should have in your inside a taster +who is not accountable to you; who experiences sensations of which you +know nothing, and cannot even form an idea. Yet thus it is. The +_pylorus_ actually tastes the paste which is in the stomach, and +if it is not to his taste, that is to say, if the work of digestion +has not sufficiently transformed it for use, he keeps the door +relentlessly closed. + +The porter up above has a thousand different tastes. He makes his bow +to meringues, and admits wings of chickens. Fries, roasts, stews, +things tender or crisp, sweet and salt, oily, greasy, or sour; amongall +kinds he has friends whom he welcomes in succession; and it is +well for us that he does so, for we share in all his pleasures. + +The porter below, who works for himself alone, obscure and unknown +down in his black hole, the porter below, I say, has but one taste, +knows but one friend--a gray-looking paste, semi-liquid, with a very +peculiar unsavoury smell, disagreeable enough to any one but himself, +which is called the _chyme_, I scarcely know why, but it is what +everything one eats turns into, without exception, be it delicate or +coarse by nature. The great lord's truffle-stuffed pullet makes, as +nearly as possible, the same _chyme_ as the charcoal-burner's black +bread; and though the palate of the former may be better treated +than that of the latter, the _pylori_ can enjoy but one and the +selfsame sauce. Equality is soon restored in this case, therefore, as +you see. + +To be free to pass through then, the contents of the stomach must be +reduced to the condition of _chyme,_ the only substance which finds +favor with the _pylorus:_ and as, in the endless varieties of food which +go to form our nutriment, some sorts turn into _chyme_ much more quickly +than others, it follows, that by the aid of its discriminating tact +(which is not easy to elude) the _pylorus_ allows some to pass, while it +turns back others, until all in succession are converted into chyme. For +example, in the case of a mouthful of bread and meat swallowed at once, +the bread passes away on its travels long before the meat has done +dancing attendance in the stomach, awaiting that transformation without +which the _pylorus_ will never allow it to slip through. + +This ought to make you seriously reflect on the danger of carelessly +swallowing things, which, by their nature, are not susceptible of being +converted into _chyme,_ particularly if they are too large to +hide in the general paste, as a cherry-stone will sometimes do, so +mixed up with other food as to pass unperceived by the _pylorus,_ +over whose decisions we have no control, remember. It bangs the door +to, be assured, in the very face of anything obnoxious without +hesitation, and the poor stomach would find itself condemned to retain +them for an indefinite period, unless by dint of prayers and +supplications they should contrive to soften the stern guardian, who +may at last get accustomed to their approach, and, perhaps, in a weak +moment, allow them to pass as contraband goods; like a custom-house +officer on a foreign frontier who will occasionally shut his eyes to +a country friend's packet of tobacco. But the poor stomach has had to +suffer a martyrdom meantime, while the dispute was pending, and before +the intruder has been winked at by the porter. + +I shall remember all my life the history of a peach-stone, which was +related to me in 1831. I was at the time a youngster at the Stanislaus +College, and (aided perhaps by the Revolution of July, which had +recently occurred), it was just then discovered to be a proper thing +to set about teaching the laws of nature to children. Consequently, +for the first time in the history of schools, a professor of natural +history was added to the instructors of Latin and Greek. I leave you +to judge how we opened our ears to his lessons. When we arrived in the +course of our new studies at the _pylorus,_ of which we had none +of us ever heard before, our professor, in warning us, as I have done +you, of the dangers of imprudent gluttony, related, as an instance, +the case of a lady who had inadvertently swallowed a peach-stone. For +two years she suffered agonies in her stomach without any cessation +or relief. The luckless peach-stone, repelled by the walls of the +stomach, which its very touch irritated, was incessantly thrown against +the entrance of the _pylorus,_ but in vain. As to turning itself +into _chyme,_ such a thing was not to be thought of, it was far +too hard a substance for that. Round and round it went, causing in its +relentless course such renewed suffering to the poor patient, that she +was visibly sinking from day to day. + +The doctors, finding all their treatment of no avail, began to despair +of her life, when one fine day she was suddenly, and as if by +enchantment, relieved of her tormentor. The peach-stone had bribed the +porter, with whom, in the course of the two years, it had scraped up +a sort of friendship. It had cleared the terrible barrier, had been +allowed to slip out, and the lady was saved; but it was only just in +time. + +I do not know, my dear, that this story, which is certainly well +calculated to cure you of any fancy for swallowing peach-stones, +willmake as much impression on you as it did on me five-and-twenty years +ago. The idea of telling it to you occurred to me quite by chance. It +has carried me back to the time when, as is now the case with you, the +mysteries which lie hidden in our internal organization were beginning +to be revealed to my mind; and you will one day know with what delight +one recalls the remembrance of these first dawnings of the intellectual +life--that delightful infancy of the growing mind--more rich in +recollections, and more interesting a thousand fold than the infancy +of the body. I have allowed myself the little treat of this episode, +and if I have had the good fortune to amuse you at all during our +progress, you must not cavil at this piece of self-indulgence. +And now we have done just what the peach-stone did; we, too, have +passed the barrier, and are out of the stomach, but still we have not +yet come to the end of our tale. + + + +LETTER X. + +THE INTESTINAL CANAL. + +I venture to hope, my dear child, that more and more light is dawning +upon your mind, as we gradually proceed on our little journey. You +must by this time have some idea how the food, which has been masticated +and softened in the mouth, cooked, kneaded, and decomposed in the +stomach, and transformed into a soft, semi-transparent kind of paste, +will soon be ready to mix with the blood, in order to repair the waste +that the life-stream is continually undergoing in its ceaseless course +through all parts of the body. + +You have perhaps thought it a sad degradation for a truffle-stuffed +fowl to turn to _chyme._ But when you consider that by this means +it becomes part and parcel of a human body, the change is not to be +despised. It was necessary, to begin with, that materials destined to +the honor of being incorporated into our frame, should break the links +which bound them to the condition of fowl and vegetable, and thus be +free to engage in new relations; just as a man who wishes to be +naturalized in a new country must first break the ties which hold him +to the old one. Those articles of food we were speaking of lately, +which are so stiff and ceremonious, and want so much coaxing before +they change into _chyme,_ which, moreover, we call _indigestible_ +because they tire the stomach so much more than the rest, are merely +those whose component parts being held together by more solid ties than +usual, continue obstinately in the same state as at first, and will not +consent to that dissolution which is the first condition of their +glorious transformation. + +Moreover, the transformation which has been described to you now, you +will henceforth meet with everywhere; wherever, that is to say, and +as far as, you choose to pursue the study of nature. God works by one +grand and simple rule so far as we can discover. He destroys to +reconstruct, builds up what is to be, out of the ruins of what has +been, creates life by death, if I may so express myself, and thus, +what takes place in our stomachs on a small scale goes on on a large +one in the universe. + +Social communities, like everything else, are subject to this universal +law, and it is not always an advantage to them when they refuse to be +digested in the great stomach of the age! + +While we are on this subject, and to show you how wonderfully this +little history of eating, told in this familiar style, applies right +and left, let us reflect on the causes which have produced a great and +mighty nation in one country (as in France), while in another (as in. +Germany), a far more numerous and even more intellectual population +has failed to rise to anything like the same distinction. The +explanation is not difficult. In the one case, the petty tribes among +which the land was originally divided consented to mix, and dissolve, +and be digested as it were together, in order to revive again for a +more glorious career; while in the other, the aboriginal societies +have adhered stiffly to their distinctive characters, and failing to +submit to the regenerating process, cling together in indigested +portions, rather than assimilate into one great whole. + +However, we must return to the _pylorus_ or we shall be getting +into a difficulty! What I am now going to offer you though, is rather +hard of digestion, but it will not do to provide sweet pastry only for +your brain; it will be more wholesome for it to have something a little +more solid to bite at from time to time. + +The _pylorus_, then, as has been shown, makes way for all sorts +of aliments when they have been converted into _chyme; i.e._, +when they have lost their original form and individuality. They are +dead to their first life, therefore; now the question is, how are they +to be revived into the new one? + +Behind the _pylorus_ extends a long conduit or tube--so long as to be +sometimes seven times the length of the whole body, but doubled up +backwards and forwards a number of times, so as to form a large bundle, +which fills the whole cavity of the belly--or as we also call it, the +_abdomen_. This bundle or packet is known to everybody as _the +intestines_, and it is divided into two portions: the _small +intestine_--that is, the slenderer, finer portion which begins at the +_pylorus_, and forms all the doublings of the packet, and the _large +intestine_, which is shorter and thicker also, as its name implies, and +keeps to some extent separate, though it is in reality only a +continuation of the other. This starts at the base of the _abdomen_, +near the right side, goes up in a straight line to the height of the +stomach, below which it passes, making a large bend in front of the +small intestine; after which it descends on the left side to the lower +part of the trunk, where it terminates. + +You will perhaps inquire how the _chyme_ continues to make its way +through all these manifold twists of the intestines; but do not trouble +yourself; it has only to let itself go. That _vermicular movement_ which +we noticed in the _oesophagus_ and in the _stomach_ is found here also. +It reigns, so to speak, from one end of our internal eating-machine to +the other; which eating-machine, by the way, we will now call by its +proper scientific name--_the intestinal canal_; and it is by that +movement the food is carried forward from the first moment it leaves the +mouth, and helped through all its journeyings, till it reaches the +termination of the large intestine. + +If your body were made of glass, so that you could look through it to +watch the intestine at work, it would appear to you like an enormous +worm coiled up into a bundle, heaving and moving with all its rings +at once. You never suspected there was such a movement within you; yet +it has been going on there continually ever since you were born, and +will not cease till you die. Your internal machinery never goes to +sleep, not even when you are sleeping yourself. It is a workshop in +constant operation, providing night and day for your necessities; and +in this respect the inner man sets a first-rate example to the outer +one! You will recollect what I said to you the other day about the +internal republic, and the provinces which are under your sole +government. It would be very disgraceful for the kingdom to be doing +nothing while the republic is working so hard; and a queen who +understands her office will make it a point of honor to banish idleness +from her household; in the houses of her neighbors this word is unknown. + +The _chyme_ once launched into this moving tube, is in no danger +of remaining stationary there; the fear is, of its passing on too +quickly, as you will soon see. But this danger has been provided +against. Along the whole course of its journey, though chiefly at the +commencement, it encounters at intervals certain elastic fleshy valves +which interrupt its progress, and do not allow it to pass till it has +accumulated in sufficient force to push them before it, and so escape. +In consequence of which it is always being checked in its advance; and +during these stoppages a most important work goes on upon it at leisure. + +You must understand first, that the substances of which our food is +composed, and which are afterwards decomposed in the stomach, are not +all invited to enter the blood. Our aliments are something like the +stones which the gold-seekers of California reduce to powder in order +to extract therefrom the hidden particles of gold they contain. The +gold of our food is that portion of it which the blood is able to +appropriate to his own advantage; the rest he rejects as refuse. And +this explains why a small slice of meat nourishes you more than a whole +plateful of salad. Meat is a stone absolutely full of gold, while the +salad has only a few veins of it here and there, and by far the greater +part of the material it sends to the intestines, has, in consequence, +to be thrown away. + +Now it is in the first portion of the small intestine, the part known +by the Latin name _duodenum,_ which signifies twelve (because it +is about the length of twelve finger-breadths), that the division takes +place between the parts which go to nourish the blood, and those which +are useless refuse. It is an important operation as you may suppose, +and were the _chyme_ to pass rapidly through the small intestine +the gold would run the risk of being carried off with the refuse. + +After the delay in the stomach, the food-substances make another halt +in the _duodenum,_ which, being very thin and slender, would have +great difficulty in containing them at the time of their grand entry, +an hour or two after a meal, were it not that it possesses the property +of expanding itself to such an extent, that it swells out on grand +occasions to the usual size of the stomach itself, so that it has +sometimes been considered as a second stomach. And no doubt the +operation which takes place in it gives it a claim to the appellation, +for thereby the finishing stroke is put to the work previously begun +in the stomach, and one may fairly say that, but for this last touch, +very little would be accomplished at all. + +Above the _duodenum_, and hid behind the stomach, is a kind of sponge, +similar in nature to those we have already observed in the mouth. To +this has been given the somewhat ridiculous name of _pancreas_; I call +it ridiculous because it is derived from two Greek words which signify +_all flesh_; whereas the _pancreas_, which is a sponge of the same +description as the salivary glands, presents the appearance of a grayish +granulous mass which is not fleshy at all. Whatever be its name, +however, our sponge communicates with the _duodenum_ through a small +tube, by means of which it pours into the _chyme_, as it accumulates, a +copious supply of a fluid exactly like the _saliva_ of the mouth. + +Just by the place where the tube from the _pancreas_ empties itself into +the _duodenum_, another tube arrives bringing also a fluid, but of a +different sort. This last comes from the liver, where there is a +manufactory of _bile_--an unpleasant yellowish-green liquid, the name of +which you have no doubt heard before, and which plays a very important +part in the transformation of the aliments. + +These new agents, the bile and the liver, are far too important to be +passed over in a few words; I reserve them, therefore, for my next +letter. Meantime, not to leave you longer in suspense, I may say that +the separation between the gold and the refuse in the _chyme_ takes +place as soon as the latter has received the two liquids furnished +by the liver and the _pancreas_. If you ask in what manner the +division is accomplished, I confess, to my shame, that I am not able +to explain it! What takes place there is a chemical process, and +hereafter I shall have occasion to explain the meaning of that phrase. +But the Great Chemist has not in this instance seen fit to divulge to +man the secret of the work. + +Indeed, you must prepare yourself beforehand, my dear child, to meet +with many other mysteries besides this, if we pursue to the end our +study of this flesh and bone which constitute the body of man. And +here I recall what Camille Desmoulins is reported to have said about +St. Just, viz., that he carried his head as high as if it were a +consecrated Host. + +[Footnote: The young Protestant reader who has never lived +in a Catholic country, will perhaps need to be told, that what +is here called Consecrated Host, is the sacramental wafer, or communion +bread of the church. In French called _hostie_, in Italian, _ostia_. + +In all their religious processions, which are very frequent, the host +is carried by the priest highest in authority, in a glass box placed +on a staff about four feet long, which he holds before him and so far +elevated that he has to look up to it. Over his head a richly +embroidered canopy of satin is always carried by several men; and while +these are passing, all good Catholics uncover the head and bend the +knee, wherever they may be. + +It is the custom also for the priest to be called to administer the +sacrament to any one about to die, on which occasion he always walks +under this canopy, dressed in his priestly robes, carrying the host +and preceded by some boys, ringing a bell, when the same ceremony is +observed. In passing a regiment or company of soldiers, the column is +halted, wheeled into line, and with arms presented, the whole line, +officers and men, kneel before it, and the priest usually turns and +offers a benediction. When he goes in the evening to the house of the +dying, it is customary for the people to go out upon the balconies +with lighted lamps and kneel while the host is being carried by.] + +You will read about these two men by-and-by in history. Meantime I +will not bid you do exactly the same as St. Just, because you would be +laughed at; but in one point of view he was not altogether wrong. The +human body is, in very truth, a temple in which the Deity maybe said +to reside, not inactively, not veiling his presence, but living and +moving unceasingly, watching on our behalf over the mysterious +accomplishment of the everlasting laws which equally guide the +_chyme_ in its workings through our frames, and direct the sun +in its course through the heavens. We mortals eat, but it is God who +brings nourishment out of our food. + + + +LETTER XI. + +THE LIVER. + +I fear you will be getting a little weary, my dear, of dwelling so long +on this intestinal tube, where things which looked so well on one's +plate become so transformed that they cannot be recognized, and where +there is nothing to talk about but _chyme_, and _bile_, and the +_pancreas,_ and all sorts of things neither pleasant to the eye nor +agreeable to the ear. + +But what is to be done? It is always the same story with useful things. +The people by whose labor you live in this world, are by no means the +handsomest to look at, and so it is in the little world we carry about +in our bodies. + +Never mind! Keep up your heart. We are getting to the end. We shall +very soon be following the nourishing portion of our food, on its +journey to the blood, and you will find yourself in new scenes. + +First, though, let us say a few words about the liver--the +bile-manufacturer; and to begin with, I will describe the place he +occupies in our interior. + +The interior of the human body is divided into two large compartments, +placed one above the other; the _chest_ and the _abdomen_. These are two +distinct apartments, each containing its own particular class of +tenants: the upper one being occupied by the heart and the lungs (the +respective offices of which I will presently explain to you); while in +the lower are the stomach, the intestines, and all the other machinery +which assists in the process of digestion. These two stories of +apartments are separated as those of our houses are, by a floor placed +just above the pit of the stomach. This floor is a large thin, flat +muscle, stretched like canvas, right across the body; and it is called +the _diaphragm_--another hard word! Never mind; but do your best to +recollect it, for we shall have great need of it when we come to the +lungs. If you had been born in Greece, you would have no difficulty with +the word, for it is Greek for _separation_. It means, in fact, a +_separating partition_, or, as I called it just now, _a floor._ All this +is preparatory to telling you that the liver is hooked to the diaphragm +in the abdomen. It is a very large mass and fills up, by itself alone, +all the right side of the lower compartment, from the top downwards, to +where the bones end which protect the abdomen on each side, and which +are called _the short ribs._ Place your hand there, and you will find +them without difficulty. + +Large as the liver is, it hangs suspended to a mere point of the +diaphragm, and shakes about with even the slightest movement of the +body. It is partly on this account that many people do not like to +sleep lying on the left side, especially after a good dinner, because +in this position the liver weighs upon and oppresses the stomach, like +a stout gentleman asleep in a coach who falls upon and crushes his +companion at every jolt of the vehicle. The liver within you produces, +then, the same effect that a cat, lying on the pit of your stomach +would do, and the result is that you have the nightmare. + +The liver is of a deep-red color. It is an accumulation of excessively +minute atoms, which, when united, form a somewhat compact mass, and +within each of which there is a little cell, invisible to the naked +eye, where an operation of the highest importance to our existence is +mysteriously carried on. It appears a very simple one, it is true, yet +hitherto it has baffled all attempts at explanation. Listen, however; +the subject is well worthy your careful attention, whether it can be +explained or not, and we must look back to take it up from thebeginning. + +I told you about the thousand workmen constantly busied in every part +of our bodies, who call on the blood without ceasing for "more, more." +You will remember further that it is to enable the blood to supply +these constant demands, that we require food. + +This being understood, it is not difficult to see why we grow; the +difficulty is, rather, to explain why we do not continue to grow. + +Consider, for instance, the quantity of food you have eaten during the +last year. Picture to yourself all the bread, meat, vegetables, fruits, +cakes, &c., piled upon a table. Put a whole year's milk into a large +earthenware pan, all the sweetmeats into a large jar, all the soup +into a great tureen, and see what a huge heap you will have collected +together. Then try to recollect how much you have increased in size +with all this nourishment, which has entered your body. But reckoning +in this way--even supposing the little workmen had used only a half +or even a third of the materials in question, and rejected the rest +as refuse--you would have to stoop in order to get in at the door; and +as for your papa, whose heap must have been bigger than yours, his +case would be desperate indeed; and yet he has not grown at all! + +This is very curious, and I dare say you have never thought about it +before. + +Do you know the story of a certain lady called Penelope, who was the +wife of Ulysses, a very celebrated king of whom the world has talked +for the last 3000 years--thanks to a poet called Homer, who did him +the honor of making him his hero! The husband of Penelope had left her +for a long time to go to the wars, and as he did not return, people +tried to persuade her to marry again. For peace and quiet's sake, she +promised to do so when she should have finished a piece of cloth she +was weaving, at which she worked all day long. They thought to get +hold of her very soon, but her importunate lovers were disappointed; +for the faithful wife, determined to await the return of her husband, +unwove every night the portion she had woven during the day; and I +leave you to judge what progress the web made in the course of a year! + +Now, every part of our bodies is a kind of Penelope's web, with this +difference--that here the web unravels at one end as fast as the work +progresses at the other. As the little masons put new bricks to the +house on one side, the old ones crumble away on another--in this manner +the work might go on forever without the house becoming bigger; while, +on the other hand, the house is always being rebuilt. People who are +fond of building, as some are, would quite enjoy having such a mansion +as this on hand! + +At your early age, my love, fewer bricks drop out than are added, and +this is why you grow from year to year. At your papa's age, just the +same number perish and are replaced; and therefore he continues the +same size, although in the course of the year he swallows three times +his own weight of food. But when I say this, do not suppose it is an +offensive remark, or that I think him either too little a man, or too +great an eater; seeing that there are 365 days in the year, and that +a quart of water weighs two pounds: I need not say more! + +But the next question is, what becomes of all the refuse which this +perpetual destruction produces? + +What becomes of it? Have you forgotten our steward who looks after +everything? He is a more active fellow than I have represented him! +To the office of purveyor-general he adds that of universal scavenger. +But in the latter department he obtains help. Wherever he passes along, +troops of little scavengers press forward, like himself always busy; +and while he holds out a new brick to the mason as he hurries by, the +little scavenger slips out the old one and conveys it away. The history +of these scavengers is a very curious one, and we shall have to speak +about it a little further on. They are minute pipes, _i.e. ducts_, +spread all over the body, which they envelope as if with fine net work. +They all communicate together, and end by emptying the whole of their +contents into one large canal, which, in its turn, empties itself into +the great stream of the blood. Imagine all the drains of a great town +flowing into one large one, which should empty itself into the river +on which the town was built, and you will have a fair idea of the whole +transaction. What the river would in such a case be to the town, the +blood is to the body--the universal scavenger, as I said before. But +you will ask further, What does the blood do with all this?--a question +which brings us back once more to the liver. + +You must have seen, just now, that the pockets of our dear steward +would be rapidly overloaded, were he to keep constantly filling them +with the old worn-out materials which the builders rejected, unless +he had some means of emptying them as he went along. Accordingly, a +wise Providence has furnished the body, on all sides, with clusters +of small chambers or cells, in which the blood deposits, as he goes +by, all the refuse he has picked up, and which makes its exit from the +body sometimes in one way, sometimes in another. Now, the cells of the +liver are among these refuse-chambers. One may even consider them as +some of the most important ones. When the blood has run its course +through the lower compartment, I mean the _abdomen_, it collects +from all directions and rushes into a large canal called the _portal +vein_, which conveys it to the liver. As soon as this canal has +entered the liver, it divides and subdivides itself in every direction, +like the limbs and branches of a tree diverging from the trunk; and +very soon the blood finds itself disseminating through an infinity of +small canals or pipes, whose ultimate extremities, a thousand times +finer than the finest hairs of your head, communicate with the tiny +cells of the liver. There, each of the imperceptible little drops, +thus carried into these imperceptibly minute cell-chambers, rids +itself--but no one knows how--of a part of the sweepings it has carried +along with it. Which done, the little drops thread their way back +through other canals as fine as the first, and which go on uniting +more and more to each other, like the branches of a tree on their way +to the trunk--forming at last one large canal, through which the blood +escapes from the liver, once more relieved from its weight of rubbish, +and ready to recommence its work. + +You are going to ask me, "What is all this to me--this history of the +blood and its sweepings? It was the bile you undertook to tell me +about, that liquid you spoke of as so necessary for the transformation +of the food: we were to get out of the intestinal tubes by the help +of the bile, you promised me." + +Well, my little impatient minx, it is the history of the bile that I +have been relating to you, and what is most remarkable about it is +this. You have perhaps heard of those wholesale ragpickers, who +makelarge fortunes by collecting out of the mud and dirt of the streets, +the many valuable things which have been dropped there? Well, the liver +is the master-ragpicker of the body. He fabricates, out of the refuse +of the blood, that bile which is so valuable in the economy of the +human frame. This bile is neither more nor less than the deposit left +by the little drops of blood in the innumerable minute liver-cells. +See what an ingenious arrangement, and in what a simple way two objects +are effected by one operation! + +Now you have learnt the genealogy of the bile, and the double office +of the liver, which benefits the blood by what it takes from it, +benefits the _chyme_ by what it gives it, and is an economist at +the same time--since it only gives back what it has received. This was +what I particularly wished to explain to you: the rest you will easily +learn. + +The bile does not make a long stay in the little cells, it also escapes, +by canals similar to those which carry off the blood, after +itspurification; and which in a similar way unite by degrees together, +until at length they terminate in a single canal, communicating with +a little bag placed close against the liver, where the bile accumulates +between the periods of digestion--so forming a stock on hand, ready +to pour at once into the _duodenum_ when the latter calls for its +assistance. The next time the cook cleans out a fowl, ask her to show +you the little greenish bladder which she calls the gall and which she +takes such care not to burst, because it contains a bitter liquid +which, if spilt upon it, would quite ruin the flavor of the fowl. Such, +precisely, is the bag which holds the bile. Moreover, it is close by +the liver of the fowl that you will find it placed: and you can convince +yourself in a moment by it, that the little provision I tell you of +is always stored away therein. + +We have also within us a multitude of minute electric telegraphs, which +transmit intelligence of all that occurs from one part of the body to +another, in a more wonderful manner even than the telegraphs of man's +making; later we shall see how they work. By their means the little +bag by the liver is made aware in the twinkling of an eye of the +entrance of the _chyme_ into the _duodenum,_ and forthwith the bile +returns for some distance by the canal which brought it, and then +branches off into a larger one which opens into the _duodenum._ + +The liver, on getting this intelligence, sets to work more diligently +than ever, and the bile flows in streams into the _duodenum,_ where it +mixes as it arrives with the current which comes from the _pancreas._ +Thus combined, the two liquids flow over the _chyme,_ which they +saturate on all sides; and here, as I have said, the work of the +intestinal canal ends. What is serviceable for the blood is separated +from the useless refuse, and nothing remains but to get it out of the +intestines. It is true that in their character of tubes these are closed +on all sides. But do not trouble yourself: a means of escape is +prepared. + +Before we part, however, I must apologize for something. I have not +described to you what the bile consists of, or what kind of refuse the +blood leaves in the liver; nevertheless, as you take an interest in +this much-neglected book of nature, you ought to know these things. + +It is, however, very difficult to lead you by the hand through so many +wonder*, where the secrets of nature are all in operation at once, and +to explain each as soon as we meet with it. They combine, and progress +together like the waves of the sea, where one breath suffices to agitate +the whole mass. + +When we have talked about the lungs, we will have another word to say +about the liver. + + + +LETTER XII. THE CHYLE. + +To-day we have to begin by making acquaintance with a new term. I would +willingly have spared you this, if I could, for the word is neither +a pretty, nor a well-chosen one, but we cannot get on without it. + +You are aware now that the learned, unknown sponsors, who gave names +to the different parts of the body, bestowed the odd-enough one of +_chyme_ on that pasty substance which passes out of the stomach when the +cooking is over. We have said quite enough about it, and you know enough +of it I am sure. Well! the people seem to have had quite a fancy for the +word _chyme_, for they adopted it again, with only a very slight +alteration, when they wanted to specify separately the quintessence of +the _chyme_ (the useful part that is), which has to unite with the +blood, and which we have been speaking of as the _gold_ of the aliments +--this then they called _chyle_. I give you the name as I received it, +but have no responsibility in the matter. + +In concluding the last chapter I said we were sure to find there was +a plan for extracting the best part of the _chyme_, viz. the _chyle_, +from the intestinal canal; and a very simple one it is. A complete +regiment of those little scavengers lately described, are drawn up in +battle-array along the whole length of the small intestine, but +especially round about the _duodenum._ There, a thousand minute pipes +pierce in all directions through the coat of the intestine, and suck, +like so many constantly open mouths, the drops of _chyle_ as fast as +they are formed. They are called _chyliferous vessels_ or chyle-bearers, +just as we might call hot-air stoves _caloriferous_ or heat-bearers-- +from the Latin word _fero,_ which means to carry or bear. I mentioned +before that there were, within the intestine, certain elastic valves +which obstruct the progress of the _chyme,_ and oblige it to be +constantly stopping. There are in fact so many of these, and the skin +which lines the intestinal canal is so folded and plaited, that if it +were stretched out at full length on a big table, it would cover at +least as large a surface as that other skin, with which you are so well +acquainted, which entirely clothes the body outside. + +Now, the _chyliferous vessels_ we have been speaking of insinuate +themselves into all the plaits and folds alluded to, and thus they +reach at last the very centre of the _chymous_ paste, and not a single +drop of _chyle_ can escape them. They do their work so well, that the +separation is effected long before the paste reaches the large +intestine; and when that has forced its way through the door which +guards the entrance, and which prevents its ever returning again, the +_chyle_ is already far off on its mission. It has threaded its way along +the little pipes, and, always creeping nearer and nearer, is on the +high-road to the heart, where it is anxiously expected. + +And what becomes of the rest? There is nothing further to be said about +it, but that it shares the fate of everything else which, having +answered its purpose in its place, is no longer wanted and must be got +rid of. Thus in works where iron-stone smelting is carried on, the +refuse that remains after the ore is extracted, though available for +road-making or other purposes, is thrown out of the manufactory as a +useless incumbrance there. + +Our history requires us to follow the fate of that golden aliment the +_chyle,_ which is now in a condition to support the life of the body, +and every drop of which will turn into blood--the blood which beats at +our hearts, nourishes our limbs, and sets at work the fibres of our +brain. + +I ought to tell you first that the _chyle,_ when it leaves the +intestine, is very like milk. It is a white, rather fatty juice, having +the appearance, when you look closely at it, of a kind of _whey,_ +in which a crowd of globules, or little balls if you prefer it, +infinitesimally small, are swimming about. Some people, whose curiosity +nothing can check, have put the tips of their tongue to it; so I am +able to tell you, if you care for the information, that it has rather +a saltish taste. + +At this point it is what may be called new-born blood, and to carry +on the metaphor, blood whose education has yet to be completed. All +the elements of blood are there already, but in confusion and +intermingled, so that they cannot yet be recognised. A wonderful fact, +and one of which I have no explanation to offer you, because among the +many mysteries which are silently going on within us is this, that the +education of the new-born blood begins entirely of itself in the vessels +which are carrying it along. During their very journey, the confused +elements are setting themselves in order and forming into groups. In +short the _chyle,_ when it comes out of the chyliferous vessels, +is already much more like blood than when it entered them, and yet one +cannot account for the change. It is changed, however; its whiteness +has already assumed a rosy tinge, and if it is exposed to the air it +may be seen turning slightly red, as if to give notice to the observer +of what it is about to become. + +You know that all our scavengers uniting together deposit their +sweepings in one large canal, which is called the _thoracic duct._ +The _chyle_ scavengers arrive there just like the rest, and there +our poor friend finds himself confounded for a moment with all the +dross of the body, as sometimes happens to men who devote themselves +to the public good. But the crisis passes in an instant. A little +further off, the _thoracic duct_ pours its whole contents together +into a large vein situated close to the heart, and the blood has no +difficulty in recognising and appropriating what belongs to him. + +Here, my dear little scholar, we conclude the first part of our story. +To eat is to nourish oneself; that is, to furnish all parts of the +body with the substances necessary to them for the proper performance +of their functions. The mouth receives these substances in their crude +condition, the intestinal canal prepares them for use, and the blood +distributes them. + +After the history of the _preparation,_ comes naturally that of the +_distribution._ + +The first is called the DIGESTION. It is the history of the _chyle,_ +which begins between the thumb and forefinger while as yet invisible, +hid in the thousand prisons of our different sorts of food, and ends in +the _thoracic duct, when, disengaged from all previous bonds, purified +and refined by the ordeals of its intestinal life, it leaps into the +blood, carrying with it a renewal of life and power. + +The second history is that of the CIRCULATION. It is the history of +the _Blood,_ that indefatigable traveler, who is constantly +_circulating_ or describing a circle (the Latins called it _circulus_) +through the body; by which I mean that it is continually retracing its +steps, coming out of the heart to return to it, re-entering it only to +leave it again, and so on without intermission, until the hour of death. + +The history of the _Digestion_, which we have just gone through, +goes on quietly from one end to the other without any complication. + +That of the _Circulation_, which we are about to begin, is mixed +up with another history, from which it cannot be kept separate while +the description is going on, although the two histories are in reality +quite distinct from each other. The blood describes two circles, to +speak correctly: 1st. A wide one, which extends from the extremities +of the body to the heart, and back again from the heart to the +extremities. 2d. A more contracted one, which goes from the heart to +the lungs, and back from the lungs to the heart. Whilst circulating +in the lungs, it encounters the air we breathe; and here takes place, +between it and the air, one of the most curious transactions imaginable, +without which the blood would not be able to nourish the body even for +five minutes. This is called RESPIRATION, or the act of breathing. + +Digestion, circulation, respiration, the three histories together form +but one--that of NUTRITION, or the act of nourishing; in other words, +of supporting life. This is what I called _eating_ at first, that +I might not mystify you at the beginning with hard words. But now that +we are growing learned ourselves, we must accustom ourselves to the +terms in use among learned people, especially when they are not more +formidable than those I have just taught you. + +Our next subject for consideration, then, Will be the circulation; and +we will begin with the heart, since that is to the circulation what +the stomach is to the digestion--viz., master of the establishment. +He is a very important person, this heart, as I hardly need tell you. +Even ignorant people speak respectfully of him, and I am sure beforehand +that his history will interest you very much. + +Do you feel as I do, my dear child? I am quite happy at having brought +you thus far on our journey, and at being able to take a rest with you +at the gateway of the new country into which we are about to enter, +like travelers sitting down upon a boundary frontier. What a distance +we have come, since the day when I took you by the hand to conduct you +inside this little body, of which you were making use without knowing +anything about it! How many things we have learned already, and how +many more remain to be learned, of which you have at present no idea! +I assure you I should be almost afraid myself of what is before us +yet, if I did not rely upon my own strong desire to instruct you, and +the tender affection I bear to you. Believe me, the greatest of +constraining powers is love; and when I get bewildered in the midst +of some difficult explanation which will not come out clearly, I have +only to place before me those laughing eyes of yours, where sleeps a +soul that must soon awaken to consciousness, in order to make the +daylight come into my own! + +Must I add, too, that I am not working for you only? We are all placed +in this world to help each other, and in striving to bring down light +into your intellect, and good sentiments into your heart, I am thinking +also of those to whom you, in your turn, may render the same good +service hereafter, provided I have the happiness of succeeding now +with you. This ought to be so, ought it not? You should resolve to be +numbered one day among those who have not lived altogether for +themselves, but who have given the world something worth having as +they passed through it. To-day's labor will have been well employed +if, later on, it turns out that this history of the _chyle_ has +not been told you in vain! + + + +LETTER XIII. + +THE HEART. + +There was once upon a time a banker, a millionaire, who could reckon +his wealth not by millions only, but by hundreds of millions and more; +who was, in fact, so tremendously rich that he did not know what to +do with his money--a difficulty in which nobody had ever been before. + +This man took it into his head to build a palace infinitely superior +to anything that had hitherto been seen. Marbles, carpets, gildings, +silk hangings, pictures, and statues--in fact, the whole mass of +common-place luxuries as one sees them even in the grandest royal +abodes, fell short of his magnificent pretensions. He was an intelligent +man, and thoroughly understood the respect due to his riches; and the +common fate of kings seemed to him far too shabby for the entertainment +of his dynasty, which he looked upon as very superior to all the +families of crowned heads in the world. In consequence he sent to the +four quarters of the globe for the most illustrious professors, the +most skilful engineers, the cleverest and most ingenious workmen in +every department; and giving them unlimited permission as to +expenditure? ordered them to adorn his palace with all the wonders of +science and human industry. + +Science, and human industry, and unlimited means--what will they not +accomplish? No wonder that nothing was talked of for a hundred miles +around but the magic building--of which, by the way, I do not venture +to give you a description, because it would carry me too far away. Let +it suffice to say, that never Emperor of China, Caliph of Bagdad, or +Great Mogul had such a habitation as our banker, and for a very good +reason--he was twenty times as rich as any such gentry as I have named +ever were in their lives. + +When all was finished one trifling flaw was discovered: the place was +not supplied with water. A spring-seeker, who was summoned to the +premises, could only discover a small subterranean watercourse, a sort +of zigzag pipe, formed by nature, between two beds of clay, in which +the rain of the neighborhood collected as in a sort of reservoir. The +water was neither very clear nor very plentiful, as you may imagine; +and the professor appointed to examine it, having begun by tasting it, +made a horrible face, and declared there was no use in proceeding any +further; for it had a stagnant flavor which would not be agreeable to +my lord. + +To the amazement of every body, my lord jumped for joy when he heard +this unpleasant news. It was proposed to him to fetch water from a +river which flowed a few miles' distance off; but he would hear of +nothing of the sort. What he wanted was something new, unexpected, +impossible--that was his object throughout. He took a pen and drew up +at a sitting the following programme, which caused our poor professors +to open their eyes in dismay:-- + +1st. We will use the water on the premises. + +2ndly. It shall flow night day and in all parts of the palace at once. + +3rdly. There shall be plenty of it, and it shall be good. + +The professors looked at each other for some time without speaking, +and the gravest of them, whose fortunes and characters had been long +ago established, suggested that they should simply give my lord and +his money the slip, and so teach him to make fools of people another +time! + +But the youngsters, less easily discouraged, cried out against this +with one accord. They declared that the honor of science was at stake, +and that they ought to return impudence for impudence, by executing +to the letter the impertinent programme! At length, after much +discussion and many propositions made against all hope, and thrown +aside one after the other as impracticable, a sudden inspiration crossed +the brain of an engineer who had not yet spoken; and the following is +what he proposed:-- + +What prevented the water from being sweet and fit to drink, was the +want of movement and air. What had to be done, therefore, was to erect +a pump, but a pump provided with numberless small pipes, extending to +the watercourse in all directions, and so arranged that by means of +them it should be able to draw up the water from all the corners and +windings where it lay stagnating, and then forcing it forward into a +pipe terminating in a rose, like that of a watering-pot, whence it +should gush out to fall down in fine rain, into a reservoir in the +open air. From thence another action of the pump was to bring it back +well aerated, to send it once more into a large pipe with numerous +lesser ramifications, which should convey it into every corner of the +palace. + +Up to this point all seemed practicable, but the hardest part had not +yet come. The great difficulty was how to supply this enormous +consumption with so slender a runnel of water as the one at their +disposal. But our engineer had provided for this by a stroke of genius. + +Under each of the taps (always kept open), which were dispersed all +over the palace, he would place a small cistern, from the bottom of +which should go a pipe communicating with the body of the force-pump +which drew up the water from the original watercourse. By which means +the water which ran from the taps would be taken up again and go back +to feed the reservoir in the open air; whence it would again return +to supply the taps; and so on and on, the same water continually keeping +the game alive, as people call it. Have you not sometimes seen at a +circus or theatre a large army represented by a hundred supernumeraries, +who file in close columns before the audience, going out at one side +of the stage and coming in at the other, following close at each other's +heels indefinitely? By a similar artifice the engineer would change +his meagre little runnel into an inexhaustible fountain. The water +drawn up from the watercourse by each stroke of the pump would fully +compensate for what was used in its passage through the palace by the +inhabitants. Lastly, as it might sometimes happen that the said +inhabitants washed their hands under the taps, the water on its return +to the cisterns, was to pass through a series of small filters, in +order to cleanse it from any impurity it might have contracted by the +way. Always flowing, always limpid, it would soon lose every trace of +its original source, and might defy comparison with the water of any +river in the world! + +A unanimous buzz of congratulations welcomed this plan, at once so +simple and so bold, and our professors thought their troubles were +over, but they were not at the end of their difficulties yet. When it +came to the actual erection of the machine, (naturally a most +complicated one, as it had to set a-going a quintuple system of +pipes--pipes from the water-course to the pump, pipes from the pump +to the reservoir, pipes from the reservoir to the pump, from the pump +to the taps, and from the taps to the pump again,)--our banker, who +had got amused and excited as they went on, conducted them to a small +dark closet, only a few square feet in size, concealed in a corner of +the large apartments, and informed them with a laugh that he had no +other place to offer them. Besides which, he made them understand that +on account of its situation, there could be no question of furnaces +or boilers being set up there (he detested equally coal-smoke, fires, +and explosions)--nor of workmen employed about the machine (it would +not be decent to have them going up and down the front staircase)-- +nor above all, of the frightful brake-wheels always screeching and +grinding, the unwieldy pistons rising and falling with a noise +sufficient to give one the headache. He himself slept near the little +dark closet, and the slightest noise was fatal to his repose. Having +explained all this, the rich man curtly made his bow and retired. + +For once our professors owned themselves beaten. They had come forward +quite proud of their invention, and now they were received, not with +ecstasies of delight, but with fresh demands, more ridiculous even +than the first. They were decidedly being mystified, and were preparing +in consequence to pack up and begone, furious, and swearing by all +their gods that they would never again expose science to see itself +disgraced by a purse-proud vulgarian's scorn; when, lo! happily, a +good fairy, the special friend of learned men, came passing by that +way. She raised her enchanted wand with the tip of her finger, and all +at once a little girl dressed in rags appeared in the midst of our +astonished professors. Without giving them time to recover themselves, +the child put her hand into the little patched waist of her dress, and +drew forth a rounded object, about the size of her closed fist from +which hung a quantity of tubes spreading in all directions. + +"See!" cried she; "here is the machine your banker demands of you." + +Picture to yourself a small closed bag, narrowing to a point at the +end, and separated within into two very distinct compartments by a +fleshy partition which went across the inside from the top to the +bottom. Such was the object held up by the little girl. Prom each of +these compartments issued a thick tube, ramifying into endless smaller +ones; and they were moreover each surmounted by a sort of pouch, into +which ran another tube, of the same description as the first. Each of +these four portions (the two compartments and their pouches) was in +constant but independent motion, distending and contracting alternately; +and by carefully examining the noiseless play of this singular machine, +(the walls of which were, by the magic power of the fairy, rendered +transparent to the bystanders,) the learned assembly were very soon +enabled to convince themselves, that it fulfilled all the +monstrousconditions exacted of them by the fantastic millionaire. + +All was in movement together, I told you; but let us begin at one end. +The right-hand compartment and its pouch represented the first pump; +the pump employed to draw, by the same stroke, the water from the +stagnant channel, and that from the taps. It was perfectly easy to +distinguish the two systems of pipes, and how they united together at +the small pouch on their arrival. When this was distended, a vacuum +was created inside, which was instantly filled by the liquid from the +tube which ran into it, (do not ask me why or how; I will explain that +presently). When it contracted again, the liquid which had just entered +was not able to get back, being prevented from so doing by a very +ingenious and simple contrivance, which requires a brief explanation. + +Take off the lock from your chamber-door, which opens inside; then, +standing outside, push against it with your shoulder, and you will get +in without any difficulty. But when you are in, try to push the door +open again with your shoulder in order to get outside into the passage, +and you will find that you will not be able to pass through, and this +simply because it does not open on that side. + +Which was exactly what happened to the liquid in the pouch! + +The door between the tube and the pouch only opened inwardly, and the +liquid finding itself pressed on all sides in proportion as the pouch +contracted more and more, and unable to return, was obliged at last +to make its way through another similar door which led to the large +compartment below. Here the same game recommenced. The compartment +which had distended itself to receive it, contracted in its turn, and +the liquid finding the road again barred behind it, had no choice but +to force its way through the tube which led to the air-reservoir. + +Here commenced the work of the second pump,--the pump of the left +compartment. The little pouch, when distended, was filled by the liquid +from the reservoir, and then forced it forward into the large +compartment below, always by means of the same process. This compartment +again drove it, by a powerful contraction, into the large conducting +tube charged with the office of its general distribution throughout +the body. At the end of all which, it returned once more into the +right-hand pump as before, to pursue the same course again, &c., &c. + +Thus, as you see, the whole mechanism turned upon two little points +of detail, of the simplest description possible; namely, first, on the +entrance-doors only opening on one side; and secondly, on the elastic +covers of the pouches and compartments distending and contracting +spontaneously. It was the prettiest thing in the world to see this +unpretending-looking little bag working thus, quite naturally, without +a suspicion that it was solving a problem which so many men, proud of +their science, had given up as hopeless. Certainly here was a machine +which made no noise! Once installed in its dark closet, it would have +been necessary to place your hand upon it to find out that it moved +at all. My lord could certainly sleep beside it without disturbance. + +"How much do you want for it?" said they to the poor little beggar +girl. "Name your price; have no fear; we will pay you anything you +wish." + +"I cannot give it to you," replied the child; "I need it too much +myself: IT IS MY HEART. Now that you have seen it, make another like +it, if you can." And she disappeared. + +It is said that the engineer, who longed to see his idea carried out, +tried hard to construct a similar machine with gutta-percha and iron +wires, and to set it in motion by electricity. But history does not +tell us that he succeeded, and we have yet to ask ourselves whether +the richest man in the world, aided by the wisest men in the world, +could ever provide himself with a miracle of wonder, such as the, +ragged child had received as a free gift from the hands of a gracious +Creator. + + + +LETTER XIV. + +THE ARTERIES. + +If you have thoroughly understood the story I last told you, my child, +it will have revealed to you the whole mystery of the _circulation +of the blood,_ and you are at the present moment wiser than all the +learned men of antiquity and the middle ages, for they had none of +them the faintest surmise of the truth. + +It may, perhaps, seem odd to you that men should have existed for +upwards of five thousand years without making inquiry into a matter +which so closely concerned them, and which was so easy to find out. +Is it not almost incredible that so many hearts should have beaten for +so long a period without any of their owners having felt a wish to +know exactly _why?_ Yet so it is. The action of the heart and the +flow of the blood have not been understood for much more than two +hundred years, and the man whose name is attached to this great +discovery richly deserves that we should say a few words about him. + +He was called Harvey. He was an Englishman; physician to King Charles +I., who was beheaded in 1648; and when he first ventured publicly to +teach that the blood was constantly circulating from one end of the +human body to the other, perpetually returning and retracing its steps, +a great scandal was created in the world. He was called a fool,--an +impertinent innovator,--a madman. His words shattered old doctrines, +and he only received for his reward all the petty annoyances which men +are apt to lavish so freely upon any one who tells them something new; +because--do you see?--it is so disagreeable to be disturbed in one's +habits and preconceived ideas. + +Harvey is not the only one in the history of mankind who has committed +the sin of being right in defiance of the opinions of his age. It is +true posterity takes account afterwards of the labors of genius, and +inscribes a fresh name upon her list. But one must pay for this glory +in one's lifetime. One cannot have everything at once. + +This is an old story, my child, but always new nevertheless; and for +my own part it is, I own, one of my pleasures to amuse myself by +reflecting how much cause for laughter three-fourths of the great men +of the present day are providing for the little girls who shall be +alive two centuries hence. Time is a great avenger, and puts many +things and men in their proper places. + +Let us pause here a moment while we are speaking of Harvey. I should +be curious to know what any one of the courtiers of Charles I., bedecked +in feathers, ribbons and laces, would have said to the valet who would +have placed the excellent Harvey, with his insane invention, above his +most gracious majesty, the lord and king of all Great Britain! And yet +what is his most gracious majesty to you to-day? What do you owe to +him? in what does he interest you? While you can never hear the name +of Harvey pronounced without remembering that you are under many +obligations to him! A thousand years hence, when society shall have +made the great progress which may reasonably be expected, the name of +Harvey will be familiar to every one who owns a heart, while that of +Charles I. will be only a vanished shadow; a souvenir lost in the maze +of history. + +Our debt of remembrance paid, let us return to the heart--the little +closed bag which labors so prettily. We must now inquire the real names +of whatever has figured in our story. + +The two great compartments are called _ventricles,_ the two small +pouches _auricles,_ and they are also distinguished as being on the +right or left side;--_right ventricle, left ventricle, right auricle, +left auricle._ + +The inner doors on which depends all the action of the machine, are +called _valvelets._ By-and-bye, when the pump and the steam-engine +are explained to you, you will meet again with these treacherous doors, +which never allow what has once entered to go back again; but then we +shall call them _valves._ + +The air-reservoir, I need scarcely tell you, is the _lung,_ to +which the blood goes to put itself in contact with the air. + +The subterranean watercourse, of which I hope we have talked long +enough, is _the small intestine,_ in which the _chyle_ collects; and +the tubes which run into it are, of course, the _chyliferous vessels,_ +the only channels by which anything reaches the heart which has not +previously gone out from it. + +The tubes of distribution, which run out from the machine in all +directions, are called with us _arteries_; the return tubes, which +bring back the water to the machine, are called _veins._ + +Finally, we have not exactly the _filters_ employed to clear the +water from the impurities contracted as it goes along, for no such +thing exists in us. There are in our case the refuse-chambers of which +I have already spoken, in connexion with the liver, where the blood +disembarrasses itself of any useless materials, and from which it comes +out with clean pockets, so to speak, reverting to the comparison of +which we have already availed ourselves. + +As you see, then, everything comes round again; and the bright idea +which our professors hit upon in order to satisfy the caprice of the +banker is exactly carried out in your own body, only a thousand times +more perfectly than could have been done by them all, even with all +their science added to all his money. + +I mentioned that the shrewdest of the party boasted about making an +artificial heart. But, let me tell you, there is one thing I would +have defied him to imitate, by any expedient he could devise, and that +is the inimitable construction of the _arteries_ and _veins,_ and the +incomprehensible delicacy of their innumerable ramifications. + +Let us talk a little about these marvellous tubes, and begin with the +arteries, which have the most important part to play. + +Did you ever see a doctor try the pulse of his patient? Take hold of +your own wrist and search a little above the thumb. You will soon find +the place and feel something beating against your finger. There is an +artery which passes there, and the little beating you feel is the +rebound of the pulsations, of your heart. Every time that the left +_ventricle,_ by contracting itself, chases the blood into the arteries, +these, of which the tissue is very elastic, become distended all at +once, and then contract again, repeating the process whenever a fresh +gush of blood arrives, so that their movement is exactly regulated by +the movement of the heart. It is true the two movements are in a +contrary direction; that is to say, the artery becomes distended, while +the heart contracts, and contracts when the heart enlarges itself; but +that makes no difference to the doctor. What he wants to know is, with +what force and rapidity the heart of the patient beats, and I will +explain why. It is an interesting point in the history of circulation. + +When you were very little--very little indeed, my dear child--your +heart beat from 130 to 140 times in a minute. Afterwards the beats +sank to 100 per minute; then to fewer still. At present I cannot tell +you the precise number: perhaps, about ninety. When you are a grown-up +young lady, it will beat about eighty times in the minute; when you +are a mother, about seventy-three times; when a grandmother (if such +a blessing be granted you), only from fifty to sixty times, perhaps +even fewer. People tell of an old man of eighty-four whose heart beat +only twenty-nine times in the sixty seconds. + +Observe that in all my calculations I have taken special care to prefix +the word _about_ to the numbers mentioned. And this because, in +point of fact, the heart is a capricious creature, which has no exact +rules to go by. It changes its pace on every occasion--fear, joy, every +emotion which agitates the soul, quickens or retards its movements; +and derangements of health may be detected by its pulsations, which +are infinitely varied in character. In fever, for instance, which is +nothing but a race of the blood at full speed, the hearts of grown-up +people beat as quickly as those of little children; sometimes, indeed, +more quickly still. In certain maladies it goes with great sudden +leaps, like a galloping horse; in others it trots in little jerks; +while in some cases it moves slowly and wearily, and its throbs are +so weak that one can scarcely feel them. + +These pulsations, then, afford important revelations to the doctor. +The heart is for him a gossiping confidant, who lets out the secrets +of illnesses, however closely they may fancy themselves hidden in the +remote depths of the body. When the doctor lays his finger on the +patient's pulse, it is precisely the same thing to him as if he had +laid it on his heart, only with this difference, that the one is much +less difficult to do, and much sooner done than the other. + +The artery of the wrist is in fact a small heart, not only because it +follows all the movements of the large one, but because it carries +forward the work which the other begins, and assists also in propelling +the blood to the furthest extremities of the limbs, driving it on in +its turn at each of its own contractions. Imagine a fire-engine, whose +pipes should take up and drive forwards along their whole length the +water which is thrown upon the fire, and you will have some idea of +the marvellous machine which is at work in our behalf within us. Nor +are you to suppose that the wrist-artery is a specially privileged +one, because it has been chosen to hold intercourse with physicians. +All the others are equally serviceable; and if they cannot all be +used for "feeling the pulse," it is because they are generally more +deeply buried in the flesh, where it is not easy to reach them. + +Observe your mother when she is packing a trunk, and you will see that +whatever she is most afraid maybe spoiled, she is most careful to put +in the middle, so that it may be least exposed to accidents. And this +is what a kind Providence has done with the arteries, which have the +utmost cause to dread accidents; whilst the veins, which are much +better able to bear rough usage, are allowed to wander about freely +just under the skin. But when the bones happen to take up a great deal +of room, and come near the skin themselves, as is the case in the +wrist, the artery is forced, whether he likes it or not, to venture +to the surface, and then we are able to put our fingers upon him. + +And there are others in the same sort of situation; the artery of the +foot for instance. But only just think how far from agreeable it would +be to have to take off your shoe and present your foot to the doctor! + +The artery which passes to the temple, just by the ear, is another +affair. That would answer the purpose very well in fact, and I even +advise you to make use of it when you want to feel your own pulse. It +is more easily found than the other even, and its pulsations are still +more easily perceptible. Nevertheless, when all is said and done, it +is better for the doctor to take his patient by the hand than by the +head. Merely as a matter of good manners. + +I will now make you acquainted with the principal arteries, and the +manner in which they distribute the blood through the body. + +The whole of the blood driven out by the left ventricle at each of its +contractions, passes into one large canal called the _aorta_. The +_aorta_ as it goes away at first ascends; then bends back in a curve; +and from this curve, which is called the _arch of the aorta_ (from its +shape) diverge right and left, certain branch-pipes which carry the +blood into the two arms and on each side of the head; and which are, in +fact, the beginning, or upper end, of those whose pulsations we feel +with our fingers in the two wrists and at the temples. + +The supply to the upper part of the body being secured, the _aorta_ +begins to descend. But now imagine of what importance it must be, that +this head-artery--the foster-father of the whole body--should be +sheltered from every accident. The _aorta_ once divided, death is +inevitable; you might as well have your head cut off at once; and +thus it has been fixed in the best--that is to say, the safest--place. +Of course you know what is meant by the _backbone_ or _spine_, called +also the _vertebral column_, in consequence of its being made like a +sort of column composed of a series of small bones fastened together, +which are named _vertebrae_. Touch it and feel how solid it is, and how +few dangers there can be for anything placed behind it. Well, that is +the rampart which has been given to the _Aorta_. As this descends, it +slips behind the heart and takes up its place in front of the _vertebral +column_ which it follows all the way down the back, just to the top of +the loins. There it is, so to speak, almost unassailable; in fact hardly +any cases are known of the _Aorta_ being wounded; to get at it, it would +be necessary to bestow one of those blows which used to be given in the +time of the Crusades, which cut the body in two. There was an end of the +_Aorta_, as of every thing else then; it was unfortunately not worth +talking about any longer! + +The next time you see a fish on the table, ask to be shown the large +central bone. It is the fish's _vertebral column_, and it will give you +an idea of your own, for it is constructed on the same plan. You will +perceive a blackish thread running all along it--that is _the aorta_. + +As it descends, the _aorta_ sends off on its passage a great number of +arteries which carry the blood into all parts of the body. Arrived at +the loins it forms a fork; dividing into two great branches, which +continue their descent, one on each side the body, down to the very +extremities of the two feet. + +As you perceive, dear child, this is not very difficult to remember. +A large fork, whose two points are at the tips of the feet, the handle +of which curves at the top like the crook of a crozier; from this curve +come four branches, which pass into the two arms and to the two sides +of the head--and this is the whole story. But of course, it would be +another affair were I to enter into the detail of all the ramifications. +Here it is that all engineers, past, present, and future, are baffled, +defeated and outdone! Choose any place you please upon your body, and +run the finest needle you can find into it what will issue from the +puncture? + +"Thanks for the proposal," you say; "I have no occasion to try the +experiment, to discover that blood will come out." + +You say that very readily, young lady; but have you ever asked yourself, +what is implied by your being so sure before hand that you can bring +blood from any part of your body if you choose to prick it, though +never so slightly? It implies that there is not on your whole frame +a spot the size of a needle's point, which has not its own little canal +filled with blood; for if there were such a one, there at any rate the +needle would pass in without tearing the canal, and causing the blood +to flow out. And now count the number of places from the top to the +bottom of your dear little self, on which one could put the point of +a needle, and even when you have counted them all, do not fancy you +have arrived at the number of the tiny tubes of blood. Compared to +these, your needle is a coarse stake, and tears not one but a thousand +of these little tubes in its passage. + +That seems to you rather a strong expression, does it not? But let me +make good my boldness. A needle's point is very fine, I admit; but a +person who could not see it without spectacles must have very poor +sight. Whereas the last subdivisions of the blood-tubes are so +attenuated, that the best eyes in the world, your own included, cannot +distinguish them. You are astonished at this, and yet it is nothing +compared to what follows. + +No doubt you have heard of the microscope,--that wonderful instrument +by which you may see objects a thousand, a hundred thousand, a million +times, if necessary, larger than they really are. With the microscope, +therefore, as a matter of course, we can see a good many of those tiny +canals which elude our unaided sight. But, alas! we discover at the +same time that these are by no means the last subdivisions. The canals +invisible to our naked eyes subdivide themselves again into others, +and these into others again, and so it goes on, till at last--the man +at the microscope can see no more, but the subdivisions still continue. + +You were ready to exclaim, at my talking of thousands of canals being +torn by a needle in passing through; but had I even said millions, it +may be doubted whether I should have spoken the whole truth. + +Besides, when you consider the office of the blood, you can easily +understand that if there were a single atom of the body left unvisited +by him, that atom could never be nourished. Do I say nourished? I have +made here a supposition altogether inadmissible; it could have no +existence at all, since it is the blood only which produces it. + +These imperceptible canals of blood have been called _capillaries_, +from the Latin word, _capillus_, which means a hair; because the +old learned men, who had no suspicion of the wonders hereafter to be +revealed by the microscope, could think of no better way of expressing +their delicacy, than by comparing them to hairs. Very likely they +thought even this a great compliment, but your delicate fair hairs, +fine as they are, are absolute cables--and coarse cables too, believe +me, compared to the _capillary vessels_ which extend to every portion +of your body. + +Observe further, that each of these arterial _capillaries_ is +necessarily composed (being the continuation of the large ones) of +three coats enclosed one within the other, which can be perfectly +distinguished in arteries of a tolerable size; add to this that within +these coats there is blood, and in the blood some thirty substances +we know of, not to speak of those we do not know; and then you will +begin to form some notion of the marvels collected together in each +poor little morsel of your body, however minute a one you may picture +to yourself. + + + +LETTER XV. + +THE NOURISHMENT OF THE ORGANS. + +When I said formerly that our dear and wonderful steward the blood, +was everywhere at once, you little suspected the prodigies involved +in that _everywhere_. But you will have a glimpse of them now, when I +tell you it is at the extremities of the _capillary arteries_ that he +carries on his distribution of goods, and accomplishes a mysterious act +of nutrition; a wonder much greater even than that of which we have just +spoken. Here, indeed, the question is no longer mechanical divisions, +whose delicacy, surprising as it may be, is yet within our powers of +comprehension. What is more surprising still, what moreover we cannot +comprehend at all, is the delicate sensitiveness of tact--I would almost +say of instinct--with which each one of the million millions of tiny +atoms of which our body is composed, draws out of the blood--the common +food of all--exactly that aliment which is necessary to it, leaving the +rest to his neighbor, and this without ever making a mistake. + +You have never thought about this; for children go on living at their +ease, as if it was the simplest thing in the world to do; never +suspecting even that their life is a continued miracle, and never, of +course, therefore, feeling bound to be grateful to the Author of that +miracle. And alas! how many hundreds of people live and die children +in that respect. + +But what would happen, I should like to know, if the eye took to seizing +upon the food of the nail, if the hairs stopped on the way what was +intended for the muscles, if the tongue absorbed what ought to go to +the teeth, and the teeth what ought to go to the tongue! Yet what +prevents their doing so? Can you tell me? They all drink alike out of +the same cup. The same blood goes to furnish them all. The substances +that it brings to the eye are the same as those which it brings to the +nail; and nevertheless the eye takes from it that which makes an eye, +and the nail that which makes a nail. + +How is this done, do you think? that is the question. + +When the doctors reply to this, that each organ has its peculiar +sensibility, which makes it recognize and imbibe from the blood one +particular substance and no other, they are strangely mistaken if they +flatter themselves that they have really answered anything. They have +done nothing but reproduce the question in other words, for it is +precisely that sensibility which requires explanation, and to tell us +that it exists, does not explain much, you must own. If you were to +ask why you had got a headache, and some one were to reply that it was +because your head ached, you would not be much the wiser I fancy. + +Each of our organs, then, may be considered as a distinct being, having +its separate life, and its particular likings. These organs behave +towards the blood like men who recognize some friend in a crowd, and +proceed to seize him by the arm; and when I told you just now that +they never made a mistake, I spoke of their regular course of action +in ordinary circumstances. Like men, they also make mistakes sometimes, +in certain cases; and take one substance for another, or do not +recognize the one they are in need of; an unanswerable proof that at +other times they exercise a sort of discernment, and do not act by a +sort of fatality, as one might be tempted to believe. Look at the +bones, for instance. They are composed of _gelatine_ (which cooks +serve up under the name of meat-jelly, but which would be more properly +called bone-jelly), and of phosphate of lime, a kind of stone of which +we have spoken before, if I remember rightly, and from which they get +all their solidity. Originally, the substance of the bone is entirely +gelatinous, and the phosphate of lime deposits itself therein by +degrees, as time goes on, and always in greater abundance as we advance +in age. + +Properly the bones borrow only gelatine and phosphate of lime from the +blood. But when they come to be broken, their texture or _tissue_ +inflames in the fractured place; and then it changes its tastes, if +I may so express myself; and, lo and behold, extracts from the blood +that which forms certain little fleshy shoots, which unite together +from the two sides of the fracture, and so mend the broken bone. Here is +one exception to the rule. + +Again, in certain diseases, the bones suddenly quarrel with the +phosphate of lime; they will not hear of it any longer, they will not +accept a fresh supply; and as the old wears out by degrees, by reason +of the continual destruction of which I spoke the other day, the bones +become more and more enfeebled, and soon can no longer support the +body. A second exception this. + +Finally, when old age comes on, the bones end by being so much +encumbered with phosphate of lime, that they have no room to admit the +fresh supply which keeps coming to them in the blood. What becomes of +it then? It goes to seek its fortune elsewhere; and there are charitable +souls, who forgetting their instinctive antipathies, consent to give +it hospitality, though much to the prejudice of the poor old man +himself, who is no longer served so well as formerly, by the incautious +servants who have allowed themselves to be thus fatally beguiled; but +no one consults him. It is the arteries especially, and sometimes +the muscles, which take this great liberty, and it is not unusual among +old people to meet with these fairly _ossified_--that is to say, +changed into bone, thanks to the phosphate of lime with which they +have consented to burden themselves. This is a third exception, and +I will spare you any others. + +What may we infer from all this, my dear child? Well, two things. +First, that we know nothing at all about the whole affair; a fact which +at once places us on a footing with the most learned philosophers in +the world. Secondly, that our body is a perpetual miracle; a miracle +which eats and drinks and walks, and which we must not look down upon +for so doing: for God dwells therein. I should have to come back to +this at every turn, if I wanted to fathom everything I have to tell +you about. Each tip of hair which you grow, is an incomprehensible +prodigy which would puzzle us for ever, if we did not call to our aid +those eternal laws which have made us what we are, and to which it is +very just our spirits should submit, since we could not exist for one +second were they to cease from making themselves obeyed in our bodies. + +Reflect on this, my dear little pupil. Young as you may be, you can +already understand from it, that there is above you something which +demands your respect. The good God, to whom your mother makes you pray +every night, on your knees, with folded hands, is not so far off as +you might perhaps suppose. He is not a being of the fancy, secluded +in the depths of that unknown space which men call Heaven, in order +to give it a name. If His all-powerful hand reaches thus into the +innermost recesses of your body, His voice speaks also in your heart, +and to what it says you must listen. + + + +LETTER XVI. + +THE ORGANS. + +Contrary to my custom, my dear child, I made use, in the last chapter, +of a new word, without giving an explanation of it. + +I spoke to you of _our organs_, and we have not yet ascertained what an +_organ_ is. + +You probably knew what I meant, because it is a word which is used in +conversation and pretty well understood by everybody. But I am bent +upon giving you a more exact idea of it, for the trouble will be well +bestowed. If I did not do this at once it was because there is a good +deal to tell about, and that would have carried me too far away from +my subject. + +_Organ_, comes from the Greek word _organon_, and means _instrument_. It +was used particularly to signify instruments of music, so much so that +our word "organ" comes from it. Our bodily organs then, are +_instruments_, or _tools_ if you like it better, which have been given +to us, wherewith to perform all the acts of life; and as there is not +one part of the body which is not of use to us for some purpose or +other, our body is, in point of fact, from head to foot a compound of +_organs_. Thus the hand is the tool which we make use of to lay hold of +anything--so an _organ_; the eye is the instrument of sight--so an +_organ_; the heart is the machine which causes the blood to circulate-- +so an organ; the liver fabricates the bile--it is an organ therefore; +the bones are the framework which support the weight of the body--so +organs; the muscles are the power which sets the bones in movement-- +organs also, therefore; the skin is the armor which protects them--so an +organ: in fact everything within us is an organ. If there was any corner +of our body which was not an organ, it would be useless to us, and we +should not, therefore, have received it, because God makes nothing +without a use. + +Here lies the secret of that great miracle which is called life. I do +not know whether you will be able to understand me thoroughly, but +open your ears, as if some one was going to explain addition to you; +this is not more difficult. + +Life is in reality the total of an addition sum. Each one of our organs +is a distinct being which has its particular nature and special office; +its separate life consequently; and our individual life is the sum +total of all these lesser lives, independent one of the other, but +which nevertheless blend together by a mysterious combination, into +one common life, which is everywhere and nowhere at the same time. It +follows from this, that the more organs a being has, the greater is +the sum total; the more, consequently, is life developed in him. +Remember this when we begin to study life in the lower animals. In +proportion as you find the number of _organs_ diminish, you will +find life diminishing in power, until we arrive at beings who have, +as it were, only one organ apparent, and whose life is so insignificant, +that we have some difficulty in giving an account of it, and are saying +the utmost that can be said in calling it life at all. + +But this comparison of life to the total of an addition sum, is too +dry; and, although it has its appropriate side, yet it might give you +a false idea of life; which is what always happens when one tries to +solve inscrutable questions and hidden mysteries by a matter-of-fact +illustration. + +Let us try for something more to the purpose. + +I told you that the Greek word _organon_ was applied especially +to instruments of music. Well, let us consider our organs as so many +musical instruments. You have, probably, sometimes been at a concert. +Each of the instruments in the orchestra performs its own part, does +it not? The little flute pipes through all its holes; the double-bass +pours thunder from its chords: the violin sighs with his; the cymbals +clash; the Chinese bells dance to their own tinkling; all go at it in +their own fashion, each independently of the other. And yet, when the +orchestra is in good tune together, and well played, you hear but one +sound; and to you the result of all these various noises, each of which +would have no meaning alone, is music composed by some great artist +whom you do not see. It is no longer a flute, a double-bass, or a violin +which you hoar; it is a symphony of Beethoven's, an oratorio of Haydn's, +or Mozart's overture to _Don Juan_. + +Life is just like this. All the instruments are playing together, and +there is but one music; music written by God. + +But wait! when I say _life is just like this_, let us come to an +understanding. Life is _some_thing like it, that is all, for as +to telling you what life is, I shall not attempt it. I know nothing +about it, do you see, though that is a painful confession to have to +make to a pupil; but in this case it does not distress me, and you are +welcome to hunt the world through for a master, who in this matter +does know anything. I could make a hundred other comparisons, but +theywould all fail in some point or other. Shall I tell you where this +one fails? In an orchestra there is always a musician by the side of +the instrument. Now with us we see the instrument well enough, but we +cannot see the musician. + +You are inclined to ask me, perhaps, why I am wasting so much paper +to-day in talking to you about organs, instead of going on tranquilly +with our little history of the circulation. But I told you just now +that the secret of life lies in the organs, and before entering upon +the history of life, I ought to have begun with them. It is there all +the books begin which treat of the subject we are studying together, +and if you had one in your hands at this moment, it would teach you +that all creatures whatsoever are divided into those which have organs +and those which have none--that is, into _organic_ and _inorganic_ +beings [Footnote: A lump of iron is the same throughout. Each of its +parts has the same properties and the same uses. It has no organs, it is +an _inorganic_ being. A rose tree has flowers, which are differently +made from its leaves, and serve a different use: a root which sucks up +the precious food of the earth; a bark which is of a different nature +from the wood, and serves a different purpose. It has organs; it is an +_organic being_: all animals and vegetables are _organic beings_.] (_in_ +stands here for _not_, as _in_complete means not complete). + +This is, in fact, the starting point for the study of nature, and there +are many other things besides which I ought to have told you before +I began. But we went straight ahead, without looking at what we were +leaving behind, satisfied with turning aside from time to time to pay +our debts. + +And while I am making my confession, I ought to tell you all. You would +probably only have listened to me with half an ear, if I had begun at +the beginning. There is a proverb which says--"The appetite comes with +eating." I do not advise you to follow this proverb too closely at +dinner, for it might mislead you sadly. But it is always true when +applied to learning; it is what one knows already that gives one a +taste for learning more. If I have been making you bite at the organs +to-day, which is rather a tough morsel, it was because I fancied that +your appetite had begun to come. Was I wrong? + +Let us now return to the blood which nourishes the organs. + + + +LETTER XVII. + +ARTERIAL AND VENOUS BLOOD. + +It is at the extremity of the capillary arteries, as we have said, +that the incomprehensible prodigy of the nourishment of our organs is +accomplished. This done, the next thing is for the blood to return to +its starting-point; and here recommence those infinitesimally minute +wonders of which we have already spoken. Close upon the capillary +_arteries_ follow the capillary _veins_, equally fine and imperceptible +as the others. These take possession of the blood everywhere at once, +without allowing it a moment's respite, and it is thenceforth on its +road of return, travelling back again to the heart. + +Where do the veins begin? where do the arteries end? No one can say +precisely, since the last ramifications of each elude the eye of man, +however much it may be aided by the admirable instruments which his +genius has invented. Nevertheless, although no one has ever ascertained +the fact by sight, there is one thing I can tell you--namely, that our +minute veins are a continuation of our minute arteries, and that it +is the same canal which as it lengthens out turns from an artery into +a vein, without any interruption; the substances destined for the +nourishment of the organs passing through its walls, as moisture passes +through our skin when we perspire. + +But if nobody has seen this, say you, how can they know it for a fact? + +Let me explain. In man, and in the animals which come nearest to man +in structure, it has never been seen; but it has been seen elsewhere. +This requires a little explanation, and you will not regret my giving +it hereafter. It has its interest, I assure you. + +When you put your hand on your throat, how does it feel to you? +_Warm_, does it not? And when you take hold of a kitten or a bird, +how do they feel? _warm_ in the same way. Now, then, can you tell +me whence comes this warmth? But to save time I will answer the question +myself. It comes from their and your _blood_, which is itself warm, and +we shall soon see why. You have no idea of all the curious facts wrapt +up in that little phrase, "You are warm-blooded;" your blood is warm. +But it has not got warm of itself; bear that well in mind. + +Now if you touch a frog, a lizard, or a fish, how do they feel to you? +Cold, of course, you answer. But I ask why? A question you will answer +in the same way as the other. Because their blood is cold, they are +"cold-blooded." + +Precisely; and while you are about it you may add that, if their blood +be cold, it is because it has not been warmed as yours is. Do not be +impatient, we shall make all this clear at the proper time and place. + +Now in the cold-blooded animals, such as serpents, frogs, tortoises, +lizards, fishes, and others, the blood circulates as it does in us, +and what is more, it does so, thanks to a machinery very similar to +our own. But, as you may imagine, a machine which produces warmth must +be constructed in a more perfect manner than a machine which produces +no warmth; and to speak truth, without flattering you, there is a +little difference between you and a frog, and it seems natural enough +that the body of a frog should be more clumsy in structure than yours. + +It is the old story of the poor man being not so well lodged as the +rich; but putting aside rich and poor, who are all human beings alike, +let us take one of those lovely dolls who walk, and move their arms +and head, and say papa! and mamma! and compare it with a cheap bazaar +doll which you can get for a penny. Both are made, in the main, in one +way. Each has two arms, two legs, a mouth, a nose, eyes, &c.; but what +a difference in the details of the two! and what infinitely more pains +have been bestowed on one than on the other! + +Well, cold-blooded animals are, so to speak, _penny doll_ animals, +by comparison with ourselves. Like us they have arteries and veins, +but there is not near so much workmanship in them; and that marvellous +delicacy of the capillary extremities, which in man and in the +warm-blooded animals drives the close observer to despair, does not +exist to trouble us in these others. It is true that with the naked +eye we are still unable to see everything, even in them; but with the +help of the microscope the whole is laid open to us--the extremities +of the arteries and the extremities of the veins; and it was here that +what I was telling you of, just now, was observed and discovered,-- +namely, that the end of the artery changes into a vein, without any +interruption in the tube. It was these very observations upon fishes and +frogs, which eventually gained the day in favor of Harvey's ideas on the +circulation of the blood, at which the learned men of his own age had +laughed so much. He was dead by that time it is true, as has happened +but too often in such cases, but do not let us pity him too much! He who +has had the rare good-fortune to lay hold of a new truth, and launch it +into the world, is sufficiently recompensed in advance. If he also +craves after the flattering voice of man's approbation, and the toylike +pleasure of personal triumph, he is after all but a child, unworthy of +the great part God has given him the privilege of playing. + +A child, did I say? Then how rude you must have thought me, dear child! +And as a punishment, you are perhaps going to remind me that I have +once more fallen into my old bad habit of wandering away from my +subject. Never mind, I am going to return to it at once. + +How can one distinguish--you will ask me--an artery from a vein, so +as to be able to determine which is a vein and which an artery? + +In many ways, I reply. First of all, an artery, as I told you lately, +is composed of three coats, of which the principal, _i.e._. the +inner one, is tough and elastic, whereby the artery is enabled to force +the blood forward in its turn, but which is also the reason of arterial +cuts being so dangerous; for in such cases the wounded tube remains +wide open; being held so by the stiffer inner coat; and thus the blood +is allowed to run out indefinitely. Now this inner coat is wanting in +the veins, whose walls sink in together when a cut is made in them, +so that it is much easier to stop the flow of the blood in them. + +Furthermore, the veins are furnished inside at intervals with little +doors, similar to those we noticed at the entrance of the _auricles_ and +_ventricles_ of the heart. You remember those important _valvelets_, on +which depends so much of the mechanism; which permit the blood to pass +in one direction, but will not allow it to return back in the +other?--well, the little doors of the veins, which are also called +_valvelets_, do exactly the same work. They open in the direction of the +heart, to allow the blood to pass on, but it finds them fast closed if +it wants to go back; so that as soon as it has forced one passage there +is no longer any hope of its return, and thus by degrees it gets nearer +and nearer to the heart without any possibility of escape. There is +nothing similar to this in the arteries, which the blood traverses in a +single bound from the impetus it receives from the heart. + +Finally--and this is most important--the blood which is found in the +veins is no longer the same as that which fills the heart. + +No longer the same? you exclaim--have we then two sorts of blood in +our bodies? Most certainly, my dear child; but you would not have +suspected it; for when you accidentally prick or cut yourself, or when +your nose bleeds, it is always the same sort of blood that comes +out--that fine red liquid which everybody knows so well by sight. This +is because the blood flows at once from the small arteries and small +veins, and what you see is a mixture of the two. The same mixture +issues from all wounds, whether small or great, and on this account +people are unanimous in declaring that blood is red; a statement which +is not true of either arterial or venous blood, separately. The last +is black, as you might convince yourself if you had courage enough, +and should happen to be in the room with any one who was going to be +bled,--a rare event, happily, in these enlightened days. + +In such a case it is always a vein which is opened, the reason of which +you will understand, after what I said of the danger of cutting the +arteries. You would there, fore see a reddish black jet of liquid spout +from under the lancet; much blacker than red, however--that is +_venous_ blood. When, on the other band, an artery has been accidentally +cut, what comes out is quite different. It is a rosy, frothy fluid, +almost like milk and carmine dissolved in it, which has been whipped up +with a stick; this is called _arterial_ blood. + +Nothing is more simple, as you perceive, than to distinguish an artery +from a vein; you have only to ascertain what is inside of it. When the +blood goes out to our organs to nourish them, it is _arterial_; when it +is returning back after having nourished them, it has become _venous_. +But what--you will ask--is it going to do now at the heart, towards +which it is on its road? It is going to seek there a fresh impetus which +shall send it once more into the lungs, where it will again become +_arterial_, _i. e._ and once more capable of affording nourishment to +the organs. Therein lies the whole secret, and the why and the wherefore +of the CIRCULATION. + +This is easily said, dear child; but suppose that you do not comprehend +it? Well, you need not be ashamed. There is no possibility of +comprehending it until one has learnt what RESPIRATION is--so here we +are stopped short. + +To-morrow, then, when we will begin with the study of this third part +of the History of Nutrition; and if the first two have amused you, I +feel pretty sure you will not find this last one dull. + + + +LETTER XVIII. + +ATMOSPHERIC PRESSURE. + +When we have been laboring very hard, my dear child, and want to rest +for a minute, we say, _Let us take breath_; because breathing is +an action which takes place of itself, requiring neither effort nor +attention on our part. + +But, if it takes place of itself, it does not explain itself; +consequently, when I say to you, _Now, let us take breath_, this +is not a signal for my having a rest, for I have undertaken to explain +Respiration to you. + +If you were a German, I would remind you of what so often happens when +you put a fork into a dish of sour-krout. You want to lay hold of a +little bit merely, but the strips of cabbage-leaf are twisted one +within the other, and hang together in spite of you, so that +withoutintending it you get hold of a whole plateful at once. + +Now this Respiration affair is something like the sour-krout +story--begging your pardon for the comparison. I should have liked to +give you only a small plateful--a child's plateful--of it; but I feel +the explanations coming, hanging one upon the other; and, whether I +will or no, I must treat you like a grown-up person, and we must give +up for once the nice little doll's dinners with which we began. + +In my opinion, you will lose nothing by the change if you will but pay +attention; for about that soft little breath of yours, which is always +coming and going over your pretty lips, there are many more things to +be learnt than you have heard of yet. As I said just now, you will +find you have got hold of a plateful all at once. A good appetite to +you! + +To prevent confusion we will divide the subject into two parts. I shall +explain to you first, _How we breathe?_--a very curious question, +as you will see. And afterwards we will examine, _Why we breathe?_-- +which is still more interesting. + +First, I must tell you that air is heavy, and very heavy too; a thousand +times more so than you may suppose. The air we breathe, through which +we move backwards and forwards, that air is _some_thing, remember, +although we do not see it; and when there is a wind, that is to say, +when the air is in motion, like a stream of water running down a hill, +we are forced to acknowledge its being something, for we see it throw +down the largest trees and carry along the biggest ships. But without +going so far out of the way for examples, try--you who run so well--to +run for two minutes against a strong wind: and then you shall tell me +whether the air is something or nothing. But if it be something it +must have weight, for all substances have; paper as well as lead; with +this sole difference, that the weight of lead is greater in proportion +to its size than that of paper. Now a sheet of paper is very light, +is it not? and you would be puzzled perhaps to say what it weighs. But +many sheets of paper placed one upon the other, end by forming a thick +book which has its undeniable weight; and if some one were to heap +upon your head a pile of large books, like those you see on your papa's +shelves, the end might be that you would be crushed to death. + +In the same way, a small amount of air is by no means heavy; but you +can conceive that a great quantity of it gathered together may end by +weighing a great deal. Now get well into your head the fact, that we, +here, on the surface of the earth, are at the bottom of an immense +mass of air, extending to somewhere about forty or fifty miles above +our heads. Let us say forty to make more sure, for learned men have +not yet been able to calculate the precise height to a nicety; and for +my own part, I think we have done wonders to get so near the mark even +as this. But can you picture to yourself the distance which forty miles +high really is? I will help you to form some idea. + +One mile contains 5,280 feet, and your papa is six feet high. One mile +high would therefore be 880 times as high as your papa, But this is +a mere nothing--only one mile's height. In forty miles there would be +no less than 211,200 feet; and setting papas aside, of whom it would +take 35,200, one on the top of the other, to go so far into the sky, +let us think of the height of the tallest buildings you know; church +and cathedral towers for instance. Now the towers of many parish +churches are 150 feet high; the towers of York Minister not 300. At +that rate it would take 1,408 ordinary parish church-towers, or upwards +of 704 York Minster towers, piled one above the other, to reach to the +end of the forty miles of air above our heads. I leave you to judge +what would be the weight of a mass of paper piled up as high as that. +You may safely grant then, that this mass or pile, or if you like it +better, this _column_ of air (for that is the proper expression), +must be of considerable weight; as is still further made certain by +the fact of its having been weighed, so that I can even name the weight +to you if you wish to hear it. Bear in mind too, that the weight of +a column of air will be in proportion to its _superficial extent_--to +its breadth and width, that is; for, as you may suppose, a column as +large in extent as one of the towers of York Minster will weigh a good +deal more than one the size of a single brick. + +But wait; here is a book on the table which will serve me for a measure, +and as you will probably find the same on your mamma's table, you can +follow my measurement. It is a French Grammar. The back is seven inches +long and four and a quarter wide. That is, there are four and a quarter +rows, each seven inches long. In other words, the back contains +nearly--and let us call it quite, for convenience' sake--thirty inches +side by side. Thirty _square inches_ as it is called. Measure your +mamma's copy and you will see. Now, can you guess the weight of the +column of air forty miles high which this volume supports? Upwards +of four cwt.; 450 lbs., that is to say. If you want to be very exact, +here is the rule. Air presses on all bodies at the rate of fifteen +pounds to every square inch; so now you can make the calculation for +yourself. + +But I suspect you had no idea you were so strong; for I see you tossing +up the book, heavily laden as it is, like a feather. + +Comfort yourself. There is no magic in the matter. If a very strong man +were to push you on one side, could you resist him? Certainly not. But +if another man of equal strength were to push you at the same time on +the other side, what would happen? Well, you would remain quietly in +your place, without troubling yourself more about one than the other, +the two forces mutually destroying each other. And this is the case +here. While the air above your book is weighing down upon it with a +force of 450 lbs., the air below it presses against it underneath with +an equal weight, and this destroys the effect of the other. From 450 +lbs. take 450 lbs., and nothing remains. Your grammar has nothing to +carry after all, and you may toss it about as you please, without +deserving much credit for the effort. + +"What are you telling me?" you inquire. "If I put a stone on the top +of my head, I can feel its weight easily enough; but if I put my hand +on the top of the stone I no longer feel anything. How can the air +below the stone press against it? And talking of columns--how pleasant +it would be, for instance, if the people who go up the Monument were +to have the weight of it on their heads when they get to the top!" + +Well said, little one. And your objection reminds me of an argument +which distracted my head as a lad, when I first heard the pressure of +air explained by a good fellow who did not trouble himself to be quite +as exact as you and I are in our discussions. I was told that the +surface of the body, or the skin of a large man, measured sixteen feet +square, which is equal to the surface of a table four feet long and +four broad. Now, you know that in four feet there are forty-eight +inches, and on the surface of the table are forty-eight rows, with +forty-eight inches in each, or 2,304 square inches; so that a man's +surface is 2,304 square inches, and the weight his body supports is +34,560 lbs., or upwards of fifteen tons--always at the rate of fifteen +pounds to every square inch, you understand. Now, I was constantly +asking myself how it happened that in entering a house one never seemed +to get rid of this almost fabulous weight, since the roof of the house +must naturally interpose itself between the air-column of forty miles +high and the man who would then only have some few feet of air above +his head. The roof would support the rest, that was clear. From whence, +then, came the 34,560 lbs. which seemed to weigh as heavily as before; +since, whether on the threshold of the door, while still under shelter +of the roof, or two steps outside in the open air, under the tremendous +column forty miles high, one never felt a bit lighter, not even to the +extent of the weight of a single sheet of paper? This was a difficulty +from which I could never extricate myself. + +I found out the answer to the riddle afterwards, and a very simple one +it is. + +Air does not, in point of fact, _weigh down_ like a solid fifty +pounds' weight, which has no impulse but to descend, and has nothing +to do with anything above it. It _presses against_ rather, like +a spring, which, having been compressed, tries to resume its natural +position with a force equal to that which holds it back. Ask some one +to show you the spring of a watch, and you will understand this better. +Each atom of air is a spring of matchless elasticity, which nothing +can break, which never wears out, which one can always compress, if +one employs force sufficient, and which is always ready to expand +indefinitely, in proportion as the compressing power is withdrawn. + +Now, consider the column of air outside the door, where there is a +pile of such springs forty miles high. The lower ones have to bear up +all their comrades, which press upon them with their united weight, +and these make desperate efforts to repulse the tremendous pressure, +and to spread out in their turn. They endeavor to escape in every +direction--to the right, to the left, above, below; but caught between +the earth, which will not give way, and the compact mass of all the +columns of air which surrounds the earth in every direction, and of +which the lower part is equally compressed everywhere, they struggle +unceasingly, but in vain; indefatigable, but powerless. You live in +the midst of those little wrestlers, and naturally bear the punishment +of the injury done to them. They press against you as against every +thing else--before, behind, on all sides--with a force equal to thatwith +which they are themselves compressed, or I would say, equal to +the weight by which they are so horribly squeezed and contracted: so +that, in fact, you bear this weight not only on your head and shoulders, +as you might at first suppose, but also all along your body and limbs, +under your arms, under your chin, in the hollow of your nostrils, +everywhere. + +Now we will suppose you to enter the house; and what do you find there? +Outer air, which on its part has got in by the door, the window, and +every little crevice in the wall. The column outside the roof no longer +presses upon it, but what is the gain of that? + +It was compressed when it got in, and the little springs will struggle +as a matter of course, quite as much on this side of the door as on +the other. The protecting roof has so little power that were it not +itself protected by the air outside, the pressure of which keeps it +in its place, the air within would shiver it into a thousand fragments +in its efforts to get loose. + +You laugh; but wait till I explain myself further. I will take the +case of a miniature house to make the matter pleasanter to you; one +fifteen feet long, fifteen feet wide, and with a flat roof, the most +economical plan as regards space. Fifteen feet are five yards, and as +the multiplication table tells us that five times five make twenty-five, +our roof will in this case be twenty-five square yards (_i. e._ +225 square feet) in superficial extent, or _area_; it is not much, +and you will find few as small. + +Would you like to calculate the force with which the millions and +thousand millions of little spring imps imprisoned under that poor +unfortunate roof would press against it? We settled before that the +quantity of them brought to bear upon a square inch had the power to +push at the rate of fifteen pounds. Were they to push against a square +yard (a surface 1296 times greater than the square inch) it would +therefore be 19,440 lbs. This being so for one square yard, calculate +for twenty-five square yards, and you will have the amount of pressure +against our roof--viz. 486,000 lbs--merely that! And now tell me what +cottage roof in the world was ever built so as to be able to stand +against such a weight? + +Perhaps though, you can scarcely appreciate the amount of heaviness, +486,000 lbs. Well, 486,000 lbs. is nearly 217 tons; and one of those +railway trucks that you see laden with coals at the stations can carry, +perhaps, from eight to ten tons, without breaking down. Say ten tons +as an outside estimate, and then think of piling the contents of +twenty-one such trucks on your roof, and yet you would still be short +of the weight of air which is bearing down upon it. I need scarcely +say now that were you to take away the air from within the roof, theair +without would smash both it and the whole cottage flat, as a giant +at a fair strikes an egg flat with one blow of his fist. To show you +how in another way: take a moderate sized column or pillar, such as +you see sometimes in a nobleman's grounds, of about the weight of the +twenty-one tons, and set it up like a chimney on the roof of our +cottage, then walk away to a little distance and watch what will happen! + +There, little Miss Laugher! have you at last learned to value the +weight of the air, or _atmospheric pressure_ as it is more properly +called; since it is the force with which the atmosphere presses against +rather than weighs upon everything on the surface of the globe? It is +no joke, as you perceive, and it affords plenty of subject +forreflection. I have still to prove to you that I have not been making +fun of you with my calculations, and that the weight of air upon a +square inch is really what I have said--viz., fifteen pounds. + +Now, there is a very simple way by which we might get to know your +strength, and tell its amount in figures, if one chose; namely, by +putting a weight on your arms--a heap of books, if you please--and +keep adding and adding to it, until those poor little arms were unable +to bear any more. Then weighing what they had borne, whether we should +find it to be ten or thirty pounds--I cannot guess how much it might +be at this distance--one might safely say, without fear of mistake, +"The strength of this young lady is equal to ten, twenty, or thirty +pounds"--in other words, "she represents a weight of ten, twenty, or +thirty pounds" and by a similar plan people have ascertained the +strength of the air--that is, the weight which it represents. They +have weighed what it is capable of carrying. + +I told you lately that the whole surface of the earth was covered by +an immense army of little imps--otherwise called little air-springs, +which, compressed by the giant mass of their comrades above, all of +whom they have to carry on their backs, are always trying to protect +themselves, by pushing back everything which comes across them. Imagine +the bottom of a well. Our imps are permanently installed there as a +matter of course, and face to face with the water they push against +it, each one doing his best, on all points at once. As the pressure +is equal everywhere therefore, and always the same, there are no signs +of it to be seen. + +Now insert in the water the end of a tube closed below by a cork which +exactly fits the interior, but which can be moved up and down in the +tube by means of a bar of iron or wood which runs through it. This is +called a _piston_, I may as well tell you as we go on. + +When the piston rises in the tube, it drives before it, as it goes, +the air which was already there; and which cannot slip away down the +sides because the piston fits so closely to them all the way along. +The result of this is, that just underneath the piston there is a place +in the water to which the air cannot reach, and at that place the water +has no pressure upon it at all. + +Now see what happens. Pressed upon heavily by the air in every other +part and place, like a mouse hunted by a cat, who finds at last a hole +through which to escape, the poor water darts at this and ascends the +tube close after the piston. + +So far so good; but if the tube is very long, and the piston rises +rather high;--at thirty-three or thirty-four feet above the level of +the water it has to continue its ascent alone. The water parts company, +stopping quietly behind, half-way up the tube. + +"What is the meaning of this?" you will ask. + +It means that the force which presses on the well-water all round the +tube, and thus drives it up, has done all it can, and that our little +air-imps refuse to supply any more. The water which rises in the tube +has a weight of its own of course, and with this weight it presses, +as it is fair it should, on the water below. In proportion as the +piston rises, the column of water which follows it gets bigger and +bigger, and naturally its weight increases at the same time. At last +there comes a moment when this weight becomes such that its pressure +on the water below is equal to that with which the air-imps are pressing +on the water in the well. Thenceforth they may push as they please; +no more water will go up. They are in the same position now that they +were before, when their comrades (afterwards driven out by the piston) +were pressing upon the same point, which had only a moment's freedom; +and this water column of thirty-three or thirty-four feet holds them +in check, to exactly the same extent as the gay fellows whose place +it has taken. + +Nothing is easier now than to calculate, even to a few grains almost, +the force of the pressure of air. One can get at the weight of water, +thank goodness! and it has been ascertained that our water-column will +weigh fifteen pounds if the tube is a square inch in size. You will +comprehend after this that it might be any size you may please to +imagine, without there being the slightest alteration in the height +of the column. The larger it is, the heavier will be the column of +water on the one hand; but on the other, the greater will be the number +of air-imps turned out; so it comes to the same thing in the end. + +If you should feel any doubt about the correctness of this reasoning, +you have only to try the experiment over again, in a well, filled with +mercury for instance. Ask to be shown some pure mercury, which is also +called _Quicksilver_, because one wants to express melted silver, +apt to be constantly on the move; it is often to be met with in houses. +Mercury weighs thirteen and a half times more than water: according +to our calculations, therefore, it would take thirteen and a half times +less of it than of water to bring our little air-imps to reason. And +this is just what you will find happens; you will see the column of +mercury stop short exactly at the moment when it has attained the +orthodox weight of fifteen pounds; that is to say, at a height of +twenty-eight inches. + +On the other hand, take some ether. You know that delicate spirit, +which smells so strong, which makes your hand feel cold if it is put +upon it, and which we give to sick people to inhale. Ether weighs +one-quarter less than water. In a well of ether you would therefore +see something quite different, and your column would rise without being +asked, to something like forty-three feet, exactly up to the point of +weighing--like the others--fifteen pounds to every square inch. Air +will not be replaced with less. + +That, then, is the measure of its strength, or our scales are deceitful. + + + +LETTER XIX. + +THE ACTION OF THE LUNGS. + +I hope I have told you enough, my dear child, to enable you fully to +estimate the force with which air presses upon everything on the surface +of the earth, and consequently upon our own bodies among the rest. + +If you understand this, nothing is easier than to understand how air +comes and goes in our lungs. + +When the cook wants to light her fire with two or three hot coals, +what does she do? + +She takes the bellows and blows it, does she not? + +But if she has no bellows at hand, what does she do? You answer at +once, she blows it herself with all the strength of her lungs. + +By which it would seem--does it not?--that we are a sort of living +bellows, being able, in case of necessity, to act as a substitute for +the wood and leather ones of common use. And if we really possess the +power of doing the work of a bellows, may not this be because we have +within us some little machine of the nature of a bellows? + +Exactly; and this fact gives me the opportunity of making you understand +the action of the lungs by explaining that of the bellows, which is +in everybody's hands, but which three-fourths of the people use, without +troubling themselves to inquire how it is made or acts. + +"A bellows, as you know, is composed of two pieces of board, capable +of being separated and brought together again at will, and united by +a piece of leather so shaped and arranged that it doubles up when the +boards close, the intermediate space forming a firmly-closed box, the +size of which increases or diminishes at every movement of the boards. + +"We take the bellows down to use it, and there are the boards, lying +flat upon each other, the box between them quite small. Is there +anything inside, do you think? + +"Nothing," you answer; "the bellows is empty." + +Do you think so really, my child? Do you think a tumbler is empty, +then, when you have drunk out its contents; and that jelly pots are +empty when all the jelly is eaten? There are not so many empty things +in the world, I assure you, as you suppose. You forget the air--that +monster who is always wanting to stretch himself out, and pushes against +everything he meets. He is an unceremonious gentleman, who takes +possession of every vacant place; as fast as you put a spoonful on +your plate, he takes up the room of the jelly which has been removed, +and at each mouthful you swallow, he slips into the place of the water +which goes away. When you think the glass and pot are empty, they are, +in reality, full of air. You cannot see it; but it is there, you may +rely upon it. + +There is air, then, in the bellows-box, because there is air in every +place where there is nothing else to dispute possession with it. The +quantity is small in this case, no doubt, because the box is small and +cannot hold much. + +But now, look! I separate the boards, and the box, which was small, +becomes large. For once, then, here is a box which must be partially +empty; for it has just, as if by magic, made a space in itself in which +positively there cannot be anything, since there was nothing there +beforehand. + +Ay! but look down at the centre of the upper board. You see a little +hole there, do you not, and below the little hole a small piece of +leather, which seems to close it up? That is a _valve_, one of those +doors, such as we noticed before in the heart, and such as are to be +found, moreover, in most houses, which let people through on one side +but not on the other. This one opens when it is pushed from without, but +lets nothing out which has once got in. Now, the air outside, as I said +before, is always pushing against everything. He pushes as a matter of +course, therefore, against the valve, and as there is nothing behind it +to resist the pressure, in proportion as room is made inside the box, he +enters and fills it with himself. + +But presently some one begins to close the bellows, and he finds himself +caught between the boards; on which these invite him to begone, with +the same sort of politeness displayed by the police, when the hour of +departure comes in a place of public exhibition; when, _i.e._, +they spread out on all sides, and force the crowd before them till +they have found the road to the door. But the air cannot get back by +the way it came in, the door being shut. As, however, it must go out +somewhere, whether it likes it or not, it passes through the tube at +the end of the box (the _nozzle_ of the bellows), and comes out +thence with a rush upon the fire. When it is once gone the bellows can +be distended again, and the process be repeated as before indefinitely. + +And this is just what goes on inside ourselves. Your chest, my child, +is a box which expands and contracts alternately; making a place for +the air by the first effort, and then driving it out by the second. +It is neither more nor less than a bellows, but of a simpler +construction than that used by the cook. The exit pipe serves also for +a door of entrance, and there is but one board instead of two. + +The _exit pipe_ is the _larynx_, of which we spoke before, +when we were talking of swallowing the wrong way, and which communicates +with the air outside, through the nose and mouth at the same time, +allowing us to breathe through either one or the other as we like. + +As to the _board_, I said a few words about it when I was describing the +liver. It is the _diaphragm_--that separating partition--that floor +which is placed between the two stories or divisions of the body--the +belly and the chest. + +But here especially the infinite superiority of the works of God over +the miserable inventions of man comes out in all its grandeur. + +A bellows which was to have the honor of keeping up within us that +miraculous fire--the pre-eminently sacred fire--which we call Life, +required something more than a common board for its foundation. And +accordingly this, of which I am now going to give you a detailed +history, is as marvellous as it is admirable. I fancy that when you +have read my account, you will no longer turn up your nose at the vile +word _diaphragm_. + +Let us first take a peep at the construction of the bellows. + +On each side of the _vertebral column_, from the neck to the loins, +spring twelve long bones, one below the other, bent in the form of bows; +these are called the _ribs_. The first seven pairs of ribs rest, and as +it were, unite, in front, upon a bone called the _sternum_, which you +can trace with your finger down to the pit of the stomach, at which +point the finger sinks in, for there is no more _sternum_, and the last +five ribs on each side no longer unite with those of the opposite one. +For which reason they are called _false ribs_. On the other hand they +are joined to each other at the ends by means of a strip or band of a +substance sufficiently strong, but at the same time flexible, and +somewhat elastic, which is called _cartilage_ or _gristle_. The next +time you see a roasting piece of veal on the table, look well at it, and +you will see at the end a white substance which crackles under your +teeth; that is _gristle_. + +This forms the framework of our bellows, which you may picture to +yourself as a kind of cage, widening towards the bottom and going to +a point at the top, for the arches formed by the upper ribs are smaller +than the others. The whole terminates in a sort of ring, through which +pass, together, the _oesophagus_ and the _trachea_. + +The space between the ribs is occupied by muscles which reach from one +to the other, and the whole framework or cage is shut in below by the +_diaphragm_, that marvellous board whose history I have promised to +relate. + +The _diaphragm_, as I told you some time ago, is a large muscle, thin +and flat, stretched like a cloth between the chest and the _abdomen_. It +is fastened by an infinity of little threads called _fibres_, to the +lower edge of the cage I have just been describing, and it looks at +first sight as if it must be incapable of moving, since it is fixed in +one invariable manner all round the body. + +It moves nevertheless, but not in the same way as the boards of our +bellows. + +Ask your brother to hold two corners of your pocket-handkerchief; take +hold of the other two yourself, and turn the handkerchief so as to +face the wind. The four corners remain in their place, do they not? +but the middle, inflated by the wind, curves and swells out in front +like a ship's sail, which itself is only an immense hand kerchief after +all. Then draw the handkerchief tightly towards you, each to your own +side, and it will recover itself and become flat again. Loosen it a +little and it will curve and swell out again in the middle, and this +maneuver you can go through as often as you choose. + +Which very maneuver the _diaphragm_ is continually performing, of and by +itself. + +In its natural position it bulges upwards in the middle, like a cloth +swollen out by the wind, and thus occupies a portion of the chest at +the expense of the lungs. When air has to be admitted, its _fibres_ +tighten and bring it flat again, as you and your brother brought the +handkerchief flat just now by tightening it. + +The whole space previously occupied by the arch of the _diaphragm_ +is thus given up to the lungs, which, being elastic, instantly stretch +themselves out to it; while air, running in through the nose and mouth, +fills up in proportion the empty place (_vacuum_) created by the +extension of the lungs, exactly as in the case of the bellows. + +But soon the fibres of the _diaphragm_ relax. It rises up again into its +old position, driving back the lungs as it does so; and the air finding +there is now no room for it, goes out by the same way the other came in. +I say _the other_, observe, because the air that goes out is no longer +the same as when it came in; and this is the secret of _why we breathe_; +while the up and down movement of the _diaphragm_ is the explanation of +_how we breathe_. + +As you perceive, then, the mechanism of these bellows of ours, is of +the most simple, and consequently of the most ingenious character, and +leaves far behind it anything we have ever imagined. + +Are you disappointed? Do you feel inclined to exclaim, "Is this all?" +to ask where are the wonders I promised you? to protest that I may +talk as I please about the inflating and flattening of a +pocket-handkerchief? _you_ can see nothing so marvellous in the +matter; nothing worth making your mouth water for. + +A little patience, Mademoiselle! Hitherto we have talked only of the +machine; but there is a goblin inside it, and our fairy tale is going +to begin again. + +There are in some families certain old servants who belong to the +house, more, it may be said, than their masters, in some ways. They +educate the children, and they serve them till death; they live for +them alone, and know so well what they have to do, both by day and +night, that there is no need to give them any orders. Nay, not only +is it unnecessary to give them directions--it is for the most part +labor in vain. They are so completely at home in their business, that +they will go nobody's way but their own. If you wish them to alter +their habits they may obey you for an instant, but it is only to return +into the old groove directly after; for they know better than you do +what you want. + +I was very little when I first read in the story-books of my day, some +bitter complaints of the disappearance of this race of old-fashioned +servants of the good old times. And you very likely may have seen it +said that they are no longer to be met with. Yet there will always be +some, depend upon it, in families, who know how to make and to keep +them. Good old times or not, they have never been found in any other +but these cases. + +Still, _I_ have just such a one as I have described--even I who +am talking to you--and so has your mamma; and what is more, you have +one yourself; and what is more still, everybody else has one. This +servant of the good old times, who will never disappear (and this is +more than one can promise of any other) is the _Diaphragm!_ When +you came into the world, my dear child, and were merely a poor little +lump of flesh, without strength, intelligence, or will; incapable of +giving any orders whatever to those organs of yours, of whose existence +you were not even aware, your _diaphragm_ quietly began his duties, +without leave or inquiry from you, and with your first _breath_ your +life began. Since which he has always gone on, whether you attended +to him or not, and his last effort will be your last sigh. + +When you go to sleep, careless of all that is to happen, until you +awake again, that servant of yours, indefatigable at his post, labors +for you still, and the light breath which half opens your rosy little +lips as it passes through them; that light breath which your happy +mother watches with such pleasure, is his work. Midnight strikes--one +o'clock--two; all around you are buried in sleep--but he is awake +still. Were it otherwise--were he to go to sleep when you do, you +would never awake again! + +This protector of each instant, this faithful guardian of your life, +is, nevertheless, subject to you as a servant to his master. Attend +to him, and he will obey your orders. You can make him go at a great +pace, or slowly, as you choose; or stop him altogether, if the fancy +takes you to do so: but this not for long. The servant of the good old +times is obstinate in the performance of his duties. He will yield to +you in trifles; but do not try to force him over serious matters. I +have read somewhere of a desperate young fellow, chained down in a +dungeon, who killed himself by holding his breath; but I never quite +believed it. Mr. Diaphragm would not allow any one to carry rebellion +so far as that. + +But we have not finished yet, and you do not yet know how appropriate +is the comparison I am making. + +Should any misfortune, any grief, any trifling annoyance even, befall +his master, a good servant suffers with him, and as much as he does; +sometimes even more. Occasionally the master is comforted, while he +remains still disturbed. + +"And the diaphragm?" you ask. + +The diaphragm does precisely the same, my dear child. Yours, especially, +shares in all your griefs to such an extent that, truth to say, he is +not always quite reasonable. The other day when your mamma did not +want to take you into the country with her, he was so sorry for you +that he went into perfect convulsions, and you sobbed and sobbed till +she was obliged to say, "Come, then, you naughty child;" whereupon you +embraced your mamma, and were quite happy again, while he remained +still unappeased, and your poor little chest was shaken more than once +afterwards by his last convulsions. + +Sobbing, you must know, is merely a convulsion--a great shake of the +diaphragm--which is the reason of its causing such a heaving of the +chest. + +It is the same with respect to joy. The joy of the master makes the +servant dance, and so the diaphragm too! Its little internal jumps +are, then, what we call laughter--a thing you are well acquainted with. +Put your hand on your chest next time you laugh (and I hope it will +be soon) and you will feel how it dances--thanks to the diaphragm which +jumps for joy whenever it finds you in good humor. + +Please to observe further, that nothing of all this is done to order. +He starts of himself, poor fellow, without waiting to ask if you will +ever know anything about it; and, in truth, you have known nothing +about it up to the present moment. + +What say you to the diaphragm now, my child? Does not the very name +please you? You scarcely expected to find there--under your lungs--so +good a servant, one so attached to your person, so strongly resembling +in all points the best specimens we know among men. And still we have +not done. I have reserved as a finale for you a new point of resemblance +which will make you open your eyes very wide indeed. + +The old servant is sometimes cross and grumbling. If anything is going +against his grain in the house he has no scruple in saying so; and his +mode of speaking is sometimes rather rude. Nor is it of any use to get +impatient and impose silence on him; he will listen to nothing--it is +his privilege. But let some unforeseen accident happen to his master, +let him see him deeply affected, and in a moment all his anger is over. +He sets himself silently to work again, recalled to order twenty times +sooner by his master's emotion than by his utmost impatience. + +You ask what I am coming to now? My dear child, what I have just told +you is the history of the _hiccup_--the history of the hiccup, neither +more nor less. + +I must first tell you, however, that the _diaphragm_ keeps up +intimate relations with his neighbor below--the stomach. Every time +he rises in the breast the stomach rises behind him; and not only the +stomach, but also its companions, the intestines. All the officials +employed in the business of digestion travel regularly with him; coming +down as well as going up in company. Put your hand upon your abdomen +and breathe strongly and you will feel the rebound of all the movements +of the diaphragm. + +Now, when matters are going on wrongly inside, when too much work has +been imposed on the officials, or work they dislike, or else when they +have been disturbed in their labors, it will sometimes happen that the +_diaphragm_ takes part with his comrades in the abdomen. He gets +angry then, and shakes his master, who cannot help himself a bit. You +must be very well acquainted with these attacks, which are very +fatiguing when they last long. One begs pardon and resists him in vain; +he does as he pleases, without stopping to listen, turning everything +upside down; and do you know the only efficacious plan for calming him +at once? It was a constant source of wonder to me when I was little. +A sudden fright, a start unexpectedly caused by a friendly hand slipping +secretly behind, and laying hold of one, was all-sufficient; disarmed +by the agitation you have undergone, the naughty, stubborn muscle +forgives you, and you are cured. + +Having dwelt so long on the truly wonderful resemblance between the +proceedings of two sorts of beings, whom no one that I know of ever +thought of comparing together before, I will now, my dear child, give +you the key to all these comparisons, which seem so whimsical at first, +but are so striking in reality, and which come to my pen of their own +accord, as it were, in the midst of the explanations I have undertaken +to give you. Many people who would not themselves care for them, will +declare that they are too hard for a little girl to follow. But for +my own part, I find that the eye can take in a mountain as easily as +a fly, and that it is not more difficult to lay hold of great ideas +than of little ones. It is short-sighted people, not children, who +cannot see far before them. Who made the heavens and the earth? God, +your catechism tells you. The same God made both; did he not? We do +not acknowledge two. And if it be the self-same God who made everything, +the hand of the universal Maker will be found everywhere; and from the +highest to the lowest portion of His work the same mind will manifest +itself under a thousand different forms. Not only, either, is each man +separately, one by one, the work of God. The whole human race, taken +in the mass, is also His creation; and the laws by which human +society--that great body of the human race--seeks to regulate itself +for the preservation of its existence, are undoubtedly the same as +those which overruled the organization of our individual bodies. It +is not very astonishing, then, if we find, in the life of human society +around us, details corresponding with each detail of the life of the +human body, or, at any rate, closely resembling them. What would really +be astonishing, would be that mankind as a whole should be differently +constituted from man as an individual, and that human society should +have other appointed conditions of well-being than those of each of +its members. + +So, while I am on the subject, I should like to advise those who wishto +apply themselves to what is called _politics_--that is to say, social +life--to begin their studies of the body social, by studying the body +human, first. They will learn more from it than from the newspapers! + +But you have nothing to do with all this. For the present, take notice +of one thing only; viz., that the hand of the same God has passed over +everything, and that there is neither much presumption nor much merit +in tracing points of comparison between the different parts of His +work. These comparisons are not a mere play of the mind; they really +exist ready made in the very foundations of things. + +Now let us come down a little from these heights and return to our +friends the lungs. I have not spoken about them for some time, and I +have not yet told you how they are constructed. + +I wish I could show you some, but the cook will do so, if you would +like to see them. The _lights_ with which she feeds the cat and +the dog are the lungs of some animal. + +Take up a piece in your hand, and you will find you have got hold of +something _light_ (cooks have not given it its name without a reason), +which is also soft, sinks under your finger if you press it, and rises +again afterwards like a sponge. In fact, the lung, like the sponge, is +composed of an infinity of minute cells, whose elastic sides can be +contracted or expanded at will. They are like so many little chambers, +into every one of which blood and air keep running hastily, each on its +own side, to bid good day to each other, touch hands, and then hurry out +as briskly as they came in. Whether the bit of lights the cat is eating, +comes from an ox, a pig, or a sheep, you may look at it with perfect +confidence; your own lung is precisely like it. You would see nothing +different, could you look into your own chest. + +So much for the _substance_ of the lungs. As to SHAPE, imagine +two large, elongated packets, flat inside, descending right and left, +inside the breast, and bearing the heart, suspended between the two, +in the middle. The extremity of each packet descends below the heart, +and it is in the interval which separates them that the arch of the +diaphragm performs its up and down movement. + +I have already said that air reaches the lungs through the _larynx_. The +_larynx_ (of which we shall speak further when I have explained another +curious thing very valuable to little girls--the voice), the _larynx_ is +a tube composed of five pieces of _cartilage_ (you know now what +_cartilage_ or _gristle_ is), the firm resisting texture of which keeps +it always open. After these five pieces of _cartilage_, come others, and +the tube is continued; but it then takes the name of the _trachea_; the +_larynx_ and _trachea_ constituting the _windpipe_. At its entrance into +the chest, the _trachea_ divides into two branches, which are called +_bronchial tubes_, and which run, one into the right lung, the other +into the left. You sometimes hear people talking about _bronchitis_. It +is an inflammation of these _bronchial tubes_, which are within an inch +or two of the lungs. It is necessary, therefore, to be very careful in +such circumstances, and do exactly what the doctor prescribes, because-- +one step further, and the inflammation extends from the bronchial tubes +into the lungs themselves, with which it is not safe to play tricks. + +Having reached the lungs, the _bronchial tubes_ subdivide into +branches, which ramify again in their turn like the boughs of a tree, +and the whole ramification terminates in imperceptible little tubes, +each of which comes out in one of those little chambers I was talking +about just now. And this is the way in which air gets there at all. + +The venous blood which leaves the heart, arrives on its side by one +large canal, which passes out from the right ventricle, and which is +called the _pulmonary artery_. And, to tell you the truth, while there +is no learned man present to be angry with us, it is a very ill-chosen +name, because it is _venous_ blood which flows in this so-called +_artery_. But the doctors have decided that all the vessels which run +from the heart should be called _arteries_, and all those which go back +to it _veins_, whatever may be the nature of the blood which they +contain. We cannot help it, because they manage all these matters in +their own way; but in that case it was scarcely worth their while to +talk about _arterial_ and _venous_ blood. It would have been better to +have said simply, red blood and black blood. + +Be this as it may, _venous blood_ arrives from the right _ventricle_ +through the _pulmonary artery_. This divides itself, like the _bronchial +tubes_, into thousands of little pipes, whose extremities come creeping +along the partitions of the little chambers in question. + +And here, then, takes place, between the air and the blood, that +mysterious intercourse for the account of which I have kept you waiting +so long; and at the end of which the black blood becomes red, or, in +other words, from venous becomes arterial. I have called it +"intercourse," and this is really the proper phrase; for this +transformation of the blood is accomplished by means of an exchange. +The air gives something to the blood, and the blood gives something +to the air--each giving, in exchange, like two people over a bargain +in the marketplace. + +With your permission, my dear child, we will stop here to-day. We have +now got to the charcoal market, and it is a little black. + + + +LETTER XX. + +CARBON AND OXYGEN. + +Here, then, my dear child, we have arrived at the explanation of that +great mystery, WHY _we breathe._ Keep on the alert, for we are now +entering into a region where everything will be new to you. + +Here we are at the charcoal market, I said to you just now, and no +doubt you concluded that I was beginning another comparison. + +But no such thing; there is no question of comparison or simile here; +I state the fact itself, pure and simple as it stands: it is a +_market,_ for commercial intercourse and exchange are carried on +there, as I told you before, and it is a _charcoal_ market, +because _charcoal_ is, positively, the essential and chief article of +commerce. + +You are astonished, I dare say, and are ready to ask me whether I can +possibly mean real charcoal, charcoal such as the cook puts into the +furnace. Surely, say you, we have nothing like _that_ in our bodies? +Surely we don't eat _that_? + +But I answer yes; real, true charcoal, and you do not dislike it; you +eat of it even daily; nay, you do not swallow a single mouthful of +food which does not contain its proportion of charcoal. + +You laugh; but wait a little and listen. + +When you are toasting a slice of bread for breakfast, and hold it too +near the fire, what happens to it? + +It turns quite black, does it not? + +When mutton-chops are left too long unturned on the gridiron, what +happens to them? + +They turn quite black also. + +When your brother forgets the apples which he has set to roast, what +happens to them? + +They turn quite black, as you have seen more than once. + +It is always black, then, that these things turn, is it not? and a +fine rich _charcoaly_ black, as you may see if you please to +observe charcoal closely, for just such is the color of little burnt +cakes, over-roasted chestnuts, and potatoes in their skins, which have +been dropped into the fire. + +But there is a common term by which we can express more accurately the +misfortune which has befallen all these various things--slices of +bread, mutton-chops, apples, cakes, chestnuts, potatoes, and what-not, +when "burnt," "over-toasted," "over-roasted," or "over-baked." We may +call them _carbonized_, or more simply _charred_ or _charcoaled_; though +the word _charred_ is generally used only for burnt _wood_. But _carbon_ +being the principal ingredient of _charcoal_, and _charcoal_ being one +of the purer forms in which we get at _carbon_, they are almost +synonymous terms, and you may call your burnt food _carbonized_, or +_charred_, or _charcoaled_, whichever you prefer. + +The next question is, how did charcoal or carbon get into the food so +as to justify our talking of its being _carbonized_ or _charred_? Even +when we use charcoal stoves for cooking, the charcoal does not jump out +and get into the mutton-chops, etc., you may be sure. Then it is clear +it must have been in them before they were brought to the fire to be +cooked; and such is indeed the case, only its black face escaped notice +because it was in such gay-looking company, and kept itself hid behind +the others like a needle lost in a match-box. Set fire to the matches, +and you will soon have nothing left but the needle, which will then +strike your eye at once. And so with our burnt food; the fire has +carried off all the other ingredients, and the charcoal is left behind +alone, exposed to everybody's view, as if on purpose to teach them that +it was always there; in the apples, i.e., the potatoes, mutton-chops, +etc., which seemed so tempting when the black rogue was hid, but from +which now, when he is there by himself, they turn away in disgust. + +Charcoal is, in fact, a much more generally distributed substance than +you have been used to suppose, dear child. That which comes from burnt +wood is most easily observed, because there is a much larger proportion +of charcoal in wood than anywhere else; but there is not a morsel, +however small, of any animal or vegetable whatsoever, which does not +contain charcoal. In the sugar which you crunch, in the wine which you +drink, there is charcoal. I could even find some in the water you wash +in if I were to try hard. There is charcoal in the goose-quill which +I hold in my hand at this moment, and in the paper on which I am +writing, and in the handkerchief on my knee. If I hold them all three +in the light of my wax taper, I shall soon see them turn black and +betray the presence of our friend. It exists in the wax taper itself, +as also in the candle, as also in the oil lamp. If I were to hold a +piece of flat glass above their flame, I should collect enough of it +to blacken the tip of anybody's nose who presumed to doubt the fact. +There is a portion of it in the air; a portion of it in the earth. +Where is it not? In short, all the stones of all the buildings in the +world are filled with it from top to bottom. _Charcoal,_ under his more +scientific and important name of _carbon,_ may be called one of the +great lords of the world. His domain is so extensive that one might go +round the world without getting out of it; he is even worse than the +Marquis of Carabas. + +After this you will never, I hope, want to persuade me you do not +eatcharcoal; for, indeed, you would be puzzled to escape doing so. Of +all the things you see on the dinner-table there is but one in which you +will not find it--viz., the salt-cellar; and even while saying this, +I mean only, in the _salt_ itself, for as to the salt-cellar, +clear and transparent as its glass may be, there is charcoal in it! + +Our bodies, therefore, are full of charcoal. Everything that we eat +supplies them with enormous quantities of it, which take up their +quarters in every corner of our organs. It is one of the principal +materials of the vast collection of structures of which I spoke to you +in the early part of these letters, and of which the blood, the steward +of the body, is the universal master-builder. If you remember, I told +you then that these structures fell to pieces of themselves, in +proportion as the workmen went on building, and that the blood, which +brings fresh materials on its arrival from the lungs and heart, carries +away the refuse ones on its return. And, of all these refuse materials, +old charcoal is one of those which takes up the most room, as fresh +charcoal took up a great deal of room in the new materials. The blood, +as he goes back again, has his pockets quite crammed with it, and if +he did not try hard to get rid of it as fast as possible, he would be +disabled from being of any further use. + +Now it is in the lungs that he clears himself of it. He gives it up +to the air, which has need of it for a very interesting operation, of +which I shall tell you more by and bye; and in return the air gives +him something which is quite indispensable to him, for without it he +would not dare to return to the organs, as his authority would no +longer be recognised. + +In the same way, the charcoal-seller goes to market with his charcoal +and receives silver in exchange. + +If he were to go home without money his wife would receive him with +abuse. + +But what is the indispensable thing which the blood obtains in his +marketing? + +Remember its name well: it is OXYGEN. + +And we must speak of it with respect, for we are talking here of a +very great and powerful personage, very superior even to CARBON. If +CARBON be one of the great lords of the world, OXYGEN is its king. + +There is a certain substance, my dear child, of which many people, +especially little girls, do not even know the name, but which yet +constitutes of itself alone a good half of everything we are acquainted +with in the world. And this substance is the very thing I have just +named to you. It is OXYGEN. + +Ascend into the air as high as you can go, viz., to forty miles or so +from the ground, as we said before; _oxygen_ forms the fifth part +of that vast aerial ocean which surrounds the globe on every side. +There it is free--is _itself_--if I may use the expression; it +is in the condition of _gas_; that is to say, it eludes our sight, +though there is no difficulty in ascertaining its presence, when one +knows how to set about it. + +Go down into the depths of the sea. People think they have good reasons +for believing this to be two and a half miles deep on an average, which +would give a pretty little sum total of tons for its whole weight, as +you will be convinced, if you take the trouble of observing the space +it covers on a map of the world;--to say nothing of lakes, rivers, +streams, the water in the clouds, the water scattered throughout the +interior or on the surface of continents, including that with which +you wash your face every morning. + +Oxygen enters in the proportion of eight-ninths into the composition +of this incalculable mass. _Eight-ninths_, you understand, which +is very near being the whole nine; in every nine pounds of water there +are eight pounds of oxygen, the remainder being left for another +substance, of which we shall have occasion to speak presently, and +which is called _hydrogen_. + +The earth on which you tread is full of oxygen. So far as we have +penetrated hitherto into the interior of the globe, we have found king +Oxygen everywhere: hidden under a thousand forms, connected with a +heap of substances, not one of which could exist without him; imprisoned +in a thousand combinations, and always ready to resume his natural +condition if his prison-house be destroyed. The whole surface of the +earth, plains, hills, mountains, towns, deserts, cultivated fields, +everything you would look down upon, if on a clear day you could be +carried high enough in a balloon to take in the whole earth at a +glance:--all that may be considered as an immense reservoir of oxygen, +out of which we should see it escaping in gigantic waves, if some +superhuman chemist were to take it into his head to put our poor little +globe into a retort of the same kind as chemists use among us. To give +you an example; the stones of our fine buildings, in which we have +already discovered the presence of _carbon_, are almost half made +up of _oxygen_. In a stone which weighs 100 lbs. there are 48 +lbs. of oxygen, and the first chemist who passes by could make them +come out of it if he chose, if he were to use a little trouble and +skill. + +I enumerated to you last time many of the substances in which _carbon_ +is to be found; but as regards _oxygen_ we must give up all attempt at +making a list; it would comprehend the whole dictionary. Touch whatever +lies under your hand--in your room--in the house--wherever you may go--I +will almost defy you to put your finger upon anything--metals +excepted--which is not crammed with oxygen. Your very body, to conclude +with, would become so small a thing, were the oxygen it contains +extracted from it, that you would be perfectly amazed. + +So when I told you oxygen was king of the world, I did not say too +much, did I? Between ourselves too, it is a great misfortune that +people live on so complacently in total ignorance of this all-important +material, which is connected with everything, which insinuates itself +everywhere, which we make use of every instant of our lives, which may +almost be said to be in some sort our very selves, since it constitutes +three-fourths of our body, but whose name nevertheless would, I am +certain, make many pretty little mouths pout, if one were to utter it +in a drawing-room. + +This is really the case. Many young ladies who are proud to know who +Caractacus was, would be ashamed to know anything about oxygen. There +is a foolish notion that women have no business with such subjects, +probably because children are supposed not to breathe and mothers are +not required to watch over them? + +This reminds me that we are on the road to explain _respiration,_ +which I had almost forgotten in lifting up this corner of the veil +behind which Nature hides her most valuable secrets from the idle and +ignorant. + +It is _oxygen_ then, which the blood carries off triumphantly from his +interview with the air in the cells of the lungs; and, by the way, it +is, thanks to this oxygen that it returns from the lungs to the heart, +and so from the heart to the organs, with that beautiful rosy tint which +distinguishes _arterial_ from _venous_ blood. + +Now the blood gives out this oxygen on its road every time it performs +the journey, and the perpetual course it performs from the lungs to +the organs, and from the organs to the lungs, has for its chief object +the perpetual renovation of this previous provision, which is as +perpetually consumed. + +Do you ask of what use it is? Does the blood leave it at random in our +organs, and is it one of the materials with which our steward is +constantly providing the little workmen of the body for their various +constructions? + +No, my dear child. The proverb _"One cannot live upon air,"_ is +a very true one, although it is equally true that we cannot live without +air. Air does not nourish our organs; on the contrary, it consumes +them, and what we eat, serves to supply in precisely the same proportion +its insatiable appetite. When we leave off eating, from whatever cause, +the air does not leave off too. He goes on always just the same, and +that is the reason why people who are starved to death are so thin. +(The air has consumed the vital parts.) + +You did not expect this; but now prepare yourself to go on from one +surprise to another. To begin with, I shall have to stop here and +explain to you before we go any further--can you guess what? Nay, I +am sure you cannot; FIRE. + +There is not much connection, you will say, between _fire_ and +_breathing_. + +But there you are mistaken. It is precisely the same thing, as I will +prove to you next time. + + + +LETTER XXI. + +COMBUSTION. + +Have you never, my dear child, whilst warming your little feet on the +hearth in winter-time, asked yourself, _What is fire?_ that great +benefactor of man; fire, without which part of the world would be +uninhabitable by us during at least a third of the year; fire, without +which we could not bake a morsel of bread, and would have to eat our +meat raw; fire, which lights up the night for us, and without which +we should have to go to bed when the hens go to roost; fire, which +subdues metals, and without which we should have neither iron, nor +copper, nor silver, nor anything that is manufactured from those +materials; fire, without which, in short, human industry could not +rise to much higher results than that of the monkey and of the beaver? + +We are all of us, it is true, so much accustomed to fire that we do +not pay much attention to it, and have a sort of persuasion that lucifer +matches have existed from all eternity. But the first men, who were +nearer neighbors to that great discovery whence all others have +originated--the first men treated fire with more respect than we do. +It was to them one of the mighty things of the world. The ancient +Persians made a god of it, and told how Zoroaster, their prophet, went +to seek it in heaven, passing thither from the top of the Himalayas, +the highest chain of mountains in the known world. + +The old Greeks pretended that Prometheus stole it from the gods, to +make a present of it to man, which came to nearly the same thing as +the Persian account. The Romans had their _sacred fire_, which +the celebrated Vestals were bound to keep lighted, on pain of death +to whoever should let it go out. At the present day we do not stand +upon such ceremonies, but warm our feet at it quite familiarly, without +wishing for anything further. But you would see a terrible revolution +in the world if some Prometheus reversed were, some fine morning, to +steal it from us, and carry it back to its ancient owners. Every branch +of human industry would suddenly stop, as if by enchantment, and in +the course of a very few years the poor little framework of human +society, of which we are now so proud, would totally change its aspect, +and the whole world would be turned topsy-turvy. + +But do not be alarmed; there is no danger of the sort. Fire is not a +present once made to man, but liable to be taken away from him at will. +It is a law of nature which existed before the human race came into +being, and which will doubtless continue to exist when the human race +shall have disappeared. The existence of fire is connected in the most +intimate way with that of that great king of the world of whom we spoke +last time--Oxygen. Fire is the wedding-feast of Oxygen with other +substances! + +When kings are married, what rejoicings there are! what a commotion! +what illuminations! It is only right and proper, then, that the king +of the world should have rejoicings and illuminations at his weddings +also. And they have never been wanting. The rejoicings are the warmth +which rejoices us; the illuminations, the flame which gives us light. +But man, in his dealings with nature, is an imperious subject, such +as few earthly kings are troubled with--happily for them! Whenever he +wants warmth and light he forces the king of the world to get married, +and then takes advantage of the feast; nothing worse than that. + +"How so?" you exclaim. "If I want to make a fire with stones or iron, +I should never succeed. Is this because oxygen never unites himself +with those substances, nor with heaps of others which are equally +useless in lighting a fire? Yet you told me that oxygen was to be met +with almost everywhere." + +It is a fair question, my dear child; but my answer is, that what you +said last is precisely the reason why all substances are not fit for +making fire of. When oxygen is already there, as he is in stones, for +instance, the marriage is over--the feast cannot begin again. Kings +are like other people in this respect; their weddings are only +celebrated once. If you had happened to be present at the moment when +oxygen was united to the materials of which stones are composed, you +would have seen a feast of which I should like to have heard some news. +I was not there myself either; but learned men in these latter days +have succeeded in breaking the bonds which united oxygen with the +primitive substances in certain fragments of stone, and with these +substances thus freed, and consequently able to remarry, they have +been enabled to give us, in miniature, the spectacle of the festivities +of a fresh wedding. And I can assure you it is enough to make one +shudder, to think of the time when such a marriage must have taken +place on a large scale. + +With regard to _iron_ the case is quite different. + +You have without doubt heard tell of Louis XIV. (of France), that proud +king who was called _le Grand_, and who is said to have heard +himself compared to the sun, without smiling. It seems that he one day +took it into his head to marry, it is difficult to say why, with Madame +de Maintenon, the old wife of a poor paralytic poet named Scarron, +who, as such, however, was only known by some few farces. Do you suppose +that the palace of Versailles was illuminated in honor of this marriage? +Not a bit of it. It was a disgraceful marriage, which they were bound +to keep secret. The ceremony was conducted mysteriously and without +lighting a single candle more than ordinary. + +I do not pretend to say that oxygen has any of these weaknesses, nor +that he is any more partial to marrying with one body more than with +another. In the good God's great world, outside of the family of man, +they know nothing of our foolish pride, of our little weaknesses. It +is nevertheless a fact that this dear monarch has his preferences, and +that all his marriages are not made in this fashion. + +Leave those pretty little scissors of yours, with which you would try +in vain to make a fire, outside your window for two or three days, and +then observe the dreadful, scaly, red stain which you are sure to find +on them afterwards, and which is called _rust._ Have you any idea +whence it proceeds? I will tell you. It comes from the oxygen, which +has been making one of those cheerless secret marriages with the iron +of your scissors. So there have been no pretty sights nor sounds, no +lights nor cheerful noises to entertain anybody, and though people may +have wished for them ever so much, they have had to do without them. + +I will tell you the true reason of these marriages _incognito._ +It is because oxygen is but feebly attracted by iron, who does not +stand so high in his good graces as many other bodies, and so (to +continue the joke) he unites slowly and languidly with him, as we may +say. + +Now tell me, when you set fire to a bit of paper, how long does it +take to burn? + +Half a minute, at the utmost, you answer. + +Very good. And how long does it take to produce that rust-stain, even +though it is probably not a hundredth part the size of the paper? + +Two or three days, is your reply, for so I told you my self. + +Here is a strange difference indeed; but from it you may discover why +you have not seen any signs of rejoicing or illuminations at the iron +wedding. These are always in proportion to the quantity of oxygen which +is being married at once--and this was--oh, such a slow affair! When +the quantity is very small indeed, the festal illuminations are very +small indeed too, and in fact escape observation altogether. In the +same way that you would not be conscious of little bits of thread laid +delicately one after another on your back, whereas you would plainly +feel a large sheet, were it to fall on your shoulders. Yet what is the +large sheet but a great quantity of little bits of thread? Only in +that case they would all come upon you at once, like the marriage +illuminations of burning paper. + +Wait a little longer and we shall finish. + +What is there, then, in the paper which pleases the oxygen so much +that he unites himself to it so readily, and in such large quantities? + +What is there? Two substances of high degree, who have actually risen +to the dignity of a royal alliance, by the important part they play +in the world; one of these, charcoal or _carbon_, we know quite +well already; the other I have only mentioned to you in connection +with water, HYDROGEN. Thanks to gas companies, everybody in these days +knows _hydrogen,_ at least by name. But before proceeding, I will +just tell you that it is by far the lightest body that is known. It +is forty and a half times lighter than air, which is not very heavy +itself, although in the mass it has its weight, as we have seen. + +The true province of hydrogen is water, where it keeps house with +oxygen, in proportion of one to eight pounds, as you may remember I +stated in my last letter. But beside this, _hydrogen_ and _carbon_ are +in a manner inseparable friends, whom one invariably meets side by side +in all animal and vegetable substances. In wood, coal, oil, tallow, and +spirits of wine; in everything in short that we call _combustibles,_ +because the name of _combustion_ has been given to this marriage of +oxygen with other bodies, hydrogen and carbon keep themselves shut up +very discreetly and very quietly; like two children playing at hide-and- +seek. You have sometimes played at hide-and-seek yourself, no doubt? +Now, if some naughty child had come behind you with a lighted candle, +what would you have done? You would have had to turn out, whether you +liked it or not, and be caught. Well! this is what happens to our two +friends, when you bring the paper to the fire. The heat forces them out, +and the oxygen, which is always at hand, seizes upon them. In a +twinkling they are married, and a beautiful flame springs up into the +air, which lasts till everything has disappeared. + +Hydrogen and carbon! These, then, are the two great combustibles, the +two parents of fire; and as nature has lavished them upon us in what +we may call inexhaustible quantities; when you hear people lamenting +and saying that wood is disappearing, that coal is diminishing, and +that the human race will end by not knowing how to warm themselves, +do not disturb yourself in the least. + +There is more hydrogen in a bucket of water than is wanted to cook a +large dinner. There is as much and more carbon in our stone quarries +than in our coal pits, and when all the woods in the world are cut +down (which I trust will never be!) do you know what we shall do? Why, +we shall take to burning the mountains. The Jura mountains in +Switzerland, for instance, (to take the most favorable case) are great +masses of carbon, without its ever being visible. Everything depends +upon knowing how to make it come out of its hiding place; but that +will de done when it is wanted: more difficult matters have been +accomplished already. As to oxygen, whether carbon comes to him from +a log of wood or from a building stone; whether the hydrogen comes +from a candle or a glass of water, is a matter of perfect indifference +to him. He only considers persons, not their origin, and marries as +willingly in one case as in the other. + +So we have returned to the subject of _respiration_, on which I +always seem to be turning my back; but now the question is, what brings +us to it again? And this is the explanation. + +When the oxygen picked up in the lungs by the blood has traveled with +it to the organs, he finds there two well-known friends--hydrogen and +carbon. + +You smile, and exclaim at once, "Then he marries them, does he?" + +Yes, my dear child; and it is only for that purpose he enters our +bodies at all. And this is why I could not make you understand the +nature of respiration until I had explained that of fire to you. As +I have told you before, it is the same thing. Invite air into your +body by the bellows of your chest, or drive it into the fire by the +kitchen bellows--it is always king Oxygen whom you are sending to his +wedding. + + + +LETTER XXII. + +ANIMAL HEAT. + +Now, then, we have got hold of the secret of respiration; the _oxygen_ +within us unites itself to the _hydrogen_ and _carbon._ + +And for what purpose, do you suppose? + +Unquestionably it must be to make a fire, since they never come together +without doing so. + +But what do people make fires for? I ask next. Well! surely to warm +themselves, do they not? + +And this is the history of your body being warm exactly like a +dining-room stove, where the oxygen in the air forms an alliance with +the hydrogen and carbon of the wood. Nature warms little girls inside, +on precisely the same plan by which men warm their houses in winter. + +Imagine, then, a little stove, furnished with little arms for helping +itself out of the wood-basket as it is wanted, and with little legs +to run and refill it when it is empty; the fire must be always burning +there, and the stove must be always warm. + +Just such a little stove is your body; your mouth being the little +door, by which there constantly enter--not wood, that would hardly be +pleasant--but--hydrogen and carbon under the forms of bread, mutton +broth, cakes, sweetmeats, and all the good things people have learnt +to make with sugar, fat, and flour. There is hydrogen and carbon in +everything we eat, as I have already told you; but sugar, fat, flour, +and _wine_ are the substances which contain them in the greatest +quantities, and consequently they are our best _combustibles._ + +You are surprised, perhaps, at _wine_ being a combustible; wine, +which you think would put out rather than make a fire. + +And it would. But that is only because in it, what is good for burning +is mixed with a great deal of water, which prevents our being able to +set it on fire. But if part of this water is withdrawn, you have +_brandy,_ which lights easily enough; and if part of the remaining +water is withdrawn from the brandy, you have _spirits of wine_, which +takes fire more easily still. If you have ever seen a _spirit-of-wine_ +lamp, you must know something about this. Judge from that what a fire +spirits of wine must make in the body, even when it has a good deal of +water with it; for it is right to tell you that your little stove is +very superior to the one in the dining-room, and that it hunts out for +consumption the smallest portions of combustible matter, in places where +the other would be a good deal puzzled to find them. + +This is not all, however. I have much greater wonders to tell you yet. + +What should you say to a stove, which, summer or winter, night or day, +in rain or sunshine, amid the ice of the pole, or under the sun of the +equator, was able to keep itself constantly in the same condition; +neither hotter nor colder one minute than another, whether you gave +it much or little fuel, at a given moment, and sometimes when you gave +it nothing for whole days together? It would be worthy of a fairy tale, +would it not? Yet the human body is a stove of this description. + +But this requires a little explanation. + +It is rather bold in me, you may think, to assert so freely, that all +the year round, from one end of the earth to the other, the human body +is never colder nor hotter than mine is, for instance, at this present +moment. "Hot" and "cold" is soon said, you argue: but the exact +varieties of _more_ or _less_ are not so easy to measure, and especially +not easy to remember, with reference to so many bodies, scattered over +the face of the whole earth. What may be warmth for one in one case, may +not be equal warmth for another; and even supposing that the same +individual learned man could go and inspect every part of the globe in +succession, how could he possibly recall, while touching the body of a +negro in Senegal, in July, the exact amount of animal heat he had found +in a Greenland Esquimaux in January? + +Be content. I should not have settled the question so cavalierly, if +people had not discovered an infallible method of estimating accurately, +and always in the same manner, the degree of warmth, in other words, +the _temperature_ of the body. + +Let us first see, then, what this method is, though it will oblige us +to digress a little; but you are accustomed to that now, surely; and +besides, if I were to go straight ahead, you would not be able to +follow me. + +Do you ever recollect being very cold? Let mammas look after their +little girls as much as they please, to prevent it, it is sure to +happen to every one some day or other. Now does it not seem at those +times as if the whole body were contracting itself--and when people +are shivering with cold, have they not a shrunk, shrivelled look? When +the weather is very hot, on the contrary, our bodies feel as if they +were swelling and stretching, and one seems to take up more room than +before. This is the case with all bodies. Heat swells, or, as learned +people call it, expands, them: cold shrinks or contracts them. +Furthermore, _mercury_ is one of the things most susceptible of this +action of heat and cold, and we have had recourse to it accordingly, in +the construction of the _thermometer_, [Footnote: _Thermometer_ comes +from two Greek words: _thermos_, heat; and _metron_, measure. The +degrees in the Thermometer about to be described are marked on the +_Centigrade_ principle. [Not the one (Fahrenheit) in general use in the +United States.]] a very useful instrument, which you will hear spoken of +all your life. + +The _thermometer_, or _heat-measure_, consists of a little hollow ball +filled with mercury, out of which rises a small tube of very thin glass, +in which the mercury can move up and down. When the thermometer is +exposed to heat, the heat causes the mercury to expand, so it goes up +the tube; when the thermometer is exposed to cold, the mercury contracts +and sinks again. + +Now suppose you were to melt some ice in the palm of one hand, and try +to dip a finger-tip of the other in a saucepan of boiling water; you +would find a great difference of temperature between the two, would +you not? Which difference of temperature people have succeeded in +measuring with the thermometer, as accurately as your mamma measures +a piece of cloth with her yard measure. + +This is how it is done: + +You surround the ball of mercury with pounded ice, and while it is +melting make a mark at that point in the tube where the mercury has +stopped in its descent. Then plunge the thermometer into boiling water. +Whereupon the mercury goes up, up, up, till at last it reaches a point +beyond which it will not pass. Here a second mark is made, and the +space between the two marks is divided into a hundred perfectly equal +parts, indicated by so many small lines, which are called _degrees_. But +this word _degrees_ has a double meaning in some languages. It means +_steps_ as well as the degrees of measurement we are talking about; +steps being, as you know, the perfectly equal parts into which a +staircase is divided. Fancy the mercury-tube a staircase, then, rising +from the cellar where the melting ice is, up to the garret where the +boiling water is, and let it consist of 100 steps. The mercury goes up +and down this staircase, according as the temperature it encounters +approaches that of the boiling water or of the melting ice; and if you +wish to know exactly how far it is from the cellar or from the garret, +you have only to count the _steps_. Hence arise those expressions which +you so often hear--high temperature and low temperature. These mean, +temperature according to which the mercury goes up or down this +staircase. + +On the actual floor of the cellar where the ice melts, there are yet +no degrees (a floor is not a _step_, you know), so there you find the +word _zero_, which means a cipher or nought. Then you begin to count 1, +2, 3, 4 degrees, marked by lines up to 100, where you reach the garret, +_i.e._ the boiling-water height. + +Of course, if the thermometer be exposed to an amount of cold greater +than that of melting ice, the mercury will sink below the cellar. +Accordingly the staircase is carried below it, with steps (so to speak) +of precisely the same size as those above, and you count as before, +1, 2, 3, &c., as it descends; adding however, to distinguish these +degrees from the others, "_below zero_." You may go on in that +way as far as 40; but there you must stop. At that point the mercury +freezes. He sits down there on his last step, and will not go any +further! + +In the same way if the thermometer is exposed to a heat greater than +that of boiling water, the mercury will rise higher than the garret. +So the staircase is made to go up higher, and always with steps of the +same size, counting from 101 upwards, as far as 350 if you choose; but +no further, observe! If the temperature were raised beyond that, the +mercury would begin to boil, and then, indeed, good-bye to steps and +measured degrees! The gentleman would dance so fast that there would +be no possibility of seeing anything, to say nothing of his flying +away! + +Now nothing is easier than to use the thermometer. You place it in the +situation where you want to measure the heat, and the mercury goes up +or down of itself until it reaches the degree which corresponds with +the temperature of the place. It is much more convenient than your +mamma's yard measure, which has to be moved about over the stuff, and +which is very apt to slip if you do not hold it carefully. Dressmakers +would be delighted to have a measure which only wanted laying upon the +material, and which would unroll itself and stop short just at the +proper point. And this kind of office the thermometer really performs. + +We will suppose to-day to be the 30th of November. I have just carried +the thermometer out of doors; the mercury has fixed itself at the +second degree _below zero_. This tells me that it is freezing +cold. My fingers have told me so already; but exactly to what extent +they could not say. Just now in the room, the mercury was at the 15th +degree _above_ zero, thanks to the stove in which we have a good +fire. In summer-time it rises to 25, 26, or 28 degrees. I once saw it +climb as high as 33 degrees: in the shade of course, you understand; +in the sun it would have been quite another affair. Well! there was +a universal outcry against the heat. Grown-up young ladies whom I try +to teach all sorts of things as I do you, pretended that it was +impossible to work. Yet I should find a still greater heat inside my +body, if I could get the thermometer there. Have no fears, however; +I am not going to make a hole in it: luckily there is one already. I +put the ball of mercury into my mouth. And now I can almost tell without +looking. The mercury was on its way up the staircase as soon as I took +the ball in my hand--and now it has reached the 37th step. + +You can try the experiment on yourself, but I forewarn you that it +ought to be rather hotter with you than with me: the mercury will +probably rise a degree higher. I will not promise that in your +grandpapa's mouth it may not sink a degree--but that will be all. In +different mouths it has, between the 38th and 36th degree, room for +the play of a little variation, but it can no more go beyond these +than a tethered cow can get beyond the circle made by her cord as she +turns round the stake. Go round the world with your thermometer, pop +it into everybody's mouth, wiping it if you choose as you proceed, you +will always find the mercury on guard. Its tethering cord is somewhat +elastic, like everything else about us; but if by any accident it +should exceed its limit by even one degree above or below, it would +be quite as extraordinary as meeting a giant of eight feet, or a dwarf +of three--which one does see occasionally, although the standard of +human height varies generally round the centre of five feet. + +Since there is a fire always kept burning within us, there is no +difficulty in comprehending why our bodies always keep warm. Of course, +however, the fire must be kept brighter in winter than in summer, but +people have no need to be told so. Nature provides for the necessity. +She gives us more appetite in cold than in hot weather; not that we +can perceive much difference in ourselves in this respect from winter +to summer; for our bodies stick to their accustomed habits, and call +out pretty loudly for the same daily rations, though without having +the same need of them. In order to estimate fairly the connexion which +exists between the internal need of food--_i.e.,_ of combustible +matter--and the external temperature, we must compare the Hindoo, who +lives on a pinch of rice a day, between the tropic and the equator, +with the Esquimaux, who, to keep up his 37 degrees of heat, beyond the +polar circle, in a country where European travellers have seen mercury +freeze, sometimes swallows from ten to fifteen pints of whale-oil at +a sitting! Just fancy _whale-oil!_ which is much nastier than +even cod-liver oil, if you ever tasted that; but, on the other hand, +it is a thorough _combustible_, and the poor people are not so +very particular: come what will, the fire must be kept up, and that +briskly. But without going thus into extremes, a friend of mine once +told me that in Portugal, the land of oranges, it is not uncommon to +see gentlemen and ladies (that is to say, those who can eat and drink +what they please) dine standing, in five minutes, on a bit of bread +and whatever else may be handy. Propose this system to the inhabitants +of our colder and damper climate, whose very young ladies, fair and +delicate-looking as they are, need a helping of good roast-beef for +dinner to keep life in them, and they would only laugh at you. But +those who were well instructed could go on to inform you that the +chilly atmosphere of northern countries creates the necessity for a +more active internal fire than is ever needed under the burning sun +of Portugal, and that a mouthful of bread per day will not, in their +case, suffice to maintain the appointed thirty-seven degrees of heat. + +For the same reason, Spaniards drink water, and are satisfied; whereas +English wine-merchants add brandy to a good many foreign wines, or +they would be quite unacceptable from being deficient in combustible. +It is for the same reason, also, that Russians can swallow, without +wincing, bumpers of brandy which would kill a Provencal outright: and +that the Swedish Government has no end of trouble to keep the country +people from converting into brandy the corn that ought to go to the +miller; whilst the Mohammedan Arabs accept without difficulty that +precept of the Koran which forbids the use of wine and spirituous +liquors. It is easy for the Arabs, who are kept warm by their climate, +to do without brandy. It is less easy for the Swedes, who are surrounded +by cold. + +All this comes as a matter of course, and we do the same thing +ourselves, without being unusually sagacious. In January, when the +thermometer goes down to twelve or fifteen degrees below zero, I put +more fuel into my stove than I am doing to-day, with only two degrees +of cold to bear with. There is nothing surprising in all this. + +The wonderful thing is, that when an Englishman goes to India, he takes +his roast beef and his spirits with him, and in a temperature of more +than thirty degrees of heat, quietly heaps up fuel in his stove, just +as if he was in England, or nearly so. You think he will set fire to +the house, perhaps. But no. Send the thermometer to his mouth for +information, and it will only mark down thirty-seven degrees; neither +more nor less than in the mouth of a rice-eater! The stove has more +sense than its owner. It only burns just what hydrogen and carbon it +wants, and takes no more trouble about the remainder than if it had +not been eaten. + +How about the remainder, then? you ask; if it is not consumed for use, +what becomes of it? Do you remember, my dear child, that long ago, +after explaining the office of the bile and the liver, I put off telling +you what the bile _consisted of_, until we had talked about the lungs +and respiration? Well, the time has come now; so listen. + +The hydrogen and carbon which is not consumed by the oxygen in the +blood, is seized upon by the liver, who employs it in the manufacture +of bile. Therefore the greater the amount of unemployed hydrogen and +carbon there is in the blood, the greater is the quantity of bile +manufactured by the liver--that is all. When once the body has attained +to its proper degree of heat, it is in vain you load it with +combustibles; it will not get any warmer, do what you will. Only you +will have cut out so much extra work for the liver, and the poor wretch +will have to get through it as he can. Accordingly, what happens in +the long run to our great eaters and drinkers, whether in India or +elsewhere? The bile-manufacturer, overwhelmed with work, gets worn +out at last, and kicks; and people come home with that miserable +disease, which is called the "liver-complaint." + +This is one explanation of that wonderful uniformity of temperature +which, happily, human imprudence cannot disturb. But the blood has a +second resource for getting rid of its superfluity of hydrogen and +carbon, and herein especially is displayed the beautiful foresight +with which everything about us has been prearranged. We are told that +wolves, when they get hold of a larger piece of meat than they care +to eat at the moment, carry off what they do not want to some corner +and bury it in the ground, whence they get it again when their hunger +returns. Dogs sometimes do the same; and the blood has a similar +instinct. Listen attentively, for this is very interesting. + +I light a candle and you see a bright flame, which will last as long +as there is any tallow below the wick. Can you tell me what it proceeds +from? + +Nay, do not laugh at the question; it is quite to the purpose, I assure +you. + +We know, do we not, that the substances which burn best are those which +are full of hydrogen and carbon? Tallow, then, is one of those +substances. But tell me further, if you please, what is tallow? + +Tallow is _mutton fat_, allow me to say, if you never heard it before. + +Now comes the question, who provided the sheep's fat with such a +quantity of hydrogen and carbon as to qualify it for making candles? + +The sheep's blood undoubtedly, since blood is the purveyor-general of +living bodies--of the sheep's body as well as of our own. + +But how came it that the sheep's blood had so large a stock of these +materials? + +Undoubtedly, again, because there was more of them in the food the +sheep had eaten than the oxygen was able to consume or the liver to +employ. In short, the sheep has lungs and a bile-manufactory, as we +have; oxygen performs the same office for it as for us. What takes +place in its body in the matter of respiration is an exact counterpart +of what happens in ours, and the history of its fat is simply the +history of our own. + +Now do you think it is for our sakes that the sheep's blood deposits +its fat in little pellet-like morsels throughout the body; do you +suppose the poor creature works in this manner merely to have the honor +of providing us with candles? It is not likely. I was talking about +the wolf just now; but there is no need to look beyond ourselves. In +many poor people's cottages there is somewhere an old earthen pot in +which the savings of each day are carefully put by, penny by penny, +as a last resource in time of need. Should a wicked thief succeed in +murdering the owner and laying hold of the treasure, he will squander +in a few hours of brilliant revelry the precious hoard so slowly got +together as a provision for possible needs. And this is what man does, +when he kills the sheep and takes its fat to make candles of! The poor +animal's blood knew well that bad times might come, that grass might +fail, and the combustible matter conveyed into the body become +insufficient to maintain its thirty-nine or forty degrees of heat +(which is the sheep's measure, who is rather hotter than we are). So +it quietly laid up its surplus stock of combustible so conveniently +brought to hand, and destined to be burnt little by little in the +depths of the organs, should times of scarcity arise. But here steps +in man, the universal thief of Nature, and turns it into a beautiful +flame, regardless of cost, and burns in one evening what his victim +had been economizing for so long. To burn for burning's sake, however, +has always been the fate of tallow, the only difference being in the +way it is done. Like the poor man's clumsy pence, which were put by +to be spent some day or other, only in another manner. It is worth +noting here, that some of the Russian soldiers who were in France in +1815 had a very good idea of restoring candles to their original +destiny. As children of the north, driven to get fire wherever they +could, they ate all the candle-ends they could lay hold of, preferring +to burn the tallow, sheep's fashion, inside rather than out! + +Fat is, then, the savings' bank of the blood; there it deposits its +savings, and there it can always find them again in time of need. +Witness the fat pig described by Liebig, the great German chemist, +which having been swallowed up by a landslip, was found alive at the +end of 160 days. Fat was out of the question there, of course; the +animal weighed ten stone less than before. We will take the illustrious +professor's word on trust, but were a few days subtracted from the +account the case would still be a splendid example of the resource +which blood finds in fat when other nourishment fails; for the pig had +certainly been breathing during the whole 160 days, and as, in all +probability, he moved about much slower than usual, his hydrogen and +carbon fire was never extinguished for a single instant; of that I am +perfectly certain, and you shall soon know why. It was well for the +poor fellow himself that he had put by his provisions in time of plenty. +And who suffered? Why, the pig's master, who had looked forward with +pleasure to the rashers of bacon he should cut by and by from the +stores of combustibles in his larder. For once Master Piggy ate his +own bacon himself! + +You understand now, I hope, by what ingenious management that marvellous +stove, called an animal, never burns too much fuel, whatever be the +quantity it is supplied with, and how, on the other hand, it has always +as much as it wants. + +I have now to explain how important it is that it _should_ always +have enough, and that this is not merely a question of heat and cold, +as with dining-room stoves, but one of life and death! Cheer up! I +have only one more word to say about Respiration, and when you have +heard it you will appreciate still better the lesson of economy which +you have learnt from Nature to-day. + + + +LETTER XXIII. + +ACTION OF THE BLOOD UPON THE ORGANS. + +The first time we talked about the Blood, my dear little pupil, I +introduced him to you as the steward of your body, and what a steward +to be sure! Always awake, as you may remember, always in motion; his +pockets ever full of the materials unceasingly required by the +indefatigable builders of that human edifice in which it has pleased +God to house your dear little self. If you wish really to understand +what follows now, we must carry on the simile a little further. + +A steward not only provides the workmen with materials, but gives them +orders as well, and this is part of the blood's business also. He is +not only commissary-general, but _whipper-in_ of the whole household, +and besides the care of giving out all the stores, has the charge to see +that everything is properly done. The unhappy men who purchase +prosperity at the dreadful cost of maintaining slavery, pretend that +their slaves would do no work worth looking at, were there not always +some one behind them with a whip in his hand. Well, our organs are +slaves, and slaves of the worst sort. They would never do anything +at all, if the blood were not everlastingly whipping them up in his +ceaseless rounds. Let him come to a stand-still for one minute, for +a second even, and everything stops short; then we are at once in the +castle of the Sleeping Beauty in the wood. But perhaps I cannot do +better than to compare our bodily machine to a violin--to hit upon +something less dismal than slaves--a violin with blood for its bow. +As long as the bow runs over the strings the violin makes music and +lives; when the bow stops, it is silent and dies. + +You have never yet had a fainting fit, my dear child; it rarely happens +at your age. But you may possibly have seen somebody faint; or, at any +rate, you have heard it talked about. Do you know what takes place in +such cases? Now and then, in consequence of some violent emotion, but +how or why I cannot tell you, all the blood rushes suddenly back towards +the heart, as during an earthquake a river will sometimes flow back +towards its source, leaving its bed dry. Thereupon the face turns +white, as if to give notice that there is no longer anything red below +the skin. The organs, no longer stimulated by the blood, leave off +work altogether. The brain goes to sleep, the muscles relax, +consciousness ceases, and you behold the poor body, from which the +soul seems to have departed, give way on all sides, and fall to the +ground like a corpse. This is not exactly death, but it is yet an +interruption of life. It would be death if nature did not get the upper +hand again, and send back the deserter to his post. + +I may remark here that it was partly on this account that some of the +ancients thought the soul was seated in the blood; not a bad idea for +people who were determined to pronounce where the soul was, when it +is so easy to say one knows nothing about it. But those who placed it +in the breath, and who have bequeathed to us those beautiful +expressions--_yielding up the last breath--giving up the ghost_--were +not wrong neither. + +In point of fact the blood is not the soul of the body; in other words, +does not keep the body alive, otherwise than by keeping up unceasingly +and everywhere that magic fire of which we were talking last time. + +The French people, in their picturesque language, have found an +expression, full of energy, to express the action exercised by the +master workman, who knows how to make his people work: "_Il vous met +le feu sous le ventre._" [Footnote: Literally, _he puts fire under +their bellies;_ but here signifying that he makes it so hot that +the organs are compelled to continue in motion.] This is, to the letter, +the process employed by the blood to make the organs work. It makes +a fire under the belly. Unhappily their work only lasts as long as the +fire which causes the heat, and which is so necessary to life that it +is almost confounded with it. It is the sacred fire of the Roman +Vestals, which must be fed night and day under pain of death should +it go out. Now, if to feed the sacred fire of life, it be necessary +that the blood should everywhere find hydrogen and carbon +_unattached_, that is to say, free and ready to unite themselves +to oxygen, it is no less necessary that he should bring oxygen with +him everywhere. Else there would be no marriage, and therefore no fire. +Oxygen is, then, the talisman which brings the organs to obedience. +Without oxygen he would be a slave-driver without his whip; his orders +would be despised. If the organs were to be deluged with _venous_ +blood--with that black blood which has lost its oxygen, they would not +stir any more than if they had received so much water. They acknowledge +nothing but _arterial_ blood--red blood--blood rich in oxygen. +That is what they respect, and which has authority over them; the other +is a bankrupt who has lost his credit with his cash; those whom he fed +but lately now laugh in his face. And as our good steward spends all +his oxygen every time he goes his rounds, it would soon be over with +him, and, consequently, with us, too, if he had not some method of +replenishing his purse after each journey. Happily the lungs are the +inexhaustible chest to which he always returns to renew his right of +authority; that is, his power of preserving life. When it comes to the +_last sigh_, the last effort of the diaphragm by which the chest +is closed forever, we must bid adieu to life. In yielding up that, we +have in very truth yielded up the ghost. + +This is no joke, as you see, and it would not do to be caught +unprepared, with an inexorable necessity hanging over one, which never +allows a moment's respite. The blood acts like a reasonable being, +therefore, in laying up his stores of combustible in reserve. Moreover, +whether he has done so or not, the fire must go on all the same; that +is absolutely necessary; and if he has no spare fat to feed it with, +when, from any cause, the stomach leaves off working, he makes use of +anything he can lay his hands upon. + +I know a story on this subject which will amuse you. + +There lived, in the reign of Francis I. of France, an honest countryman, +of Perigord, named Bernard Palissy. At that time everybody could not +afford to have earthenware plates, as they have now. It was a +manufacture of which only the Italians had the secret, and Bernard, +who knew something of the matter, from being a glass-worker, took it +into his head to try and find it out entirely by himself. So, without +asking anybody's advice, he turned potter, built ovens, picked up wood +as he could, manufactured his first pots, whether well or ill, made +a beginning, and waited. He had fifteen or sixteen years of it before +he succeeded; fifteen or sixteen years of ruinous experiments, which +would have discouraged a less sturdy heart than his. But he, after he +had succeeded in picking up some money by his church windows, returned +to his work with unconquerable perseverance, insensible to poverty, +deaf to the ridicule of neighbors, and unmoved by the abuse of his +wife, who was furious, as you may suppose, at being forced to play the +heroine without having the least turn for it. And one fine day there +was a grand uproar in La Chapelle-Biron (that was the name of his +village). "Bernard Palissy has gone mad," said everybody; "he is burning +up his house to bake his pots." And upon my word it was true! Wood +happened to be wanting while a batch was in the oven, and Bernard +having begun by using up the garden palisades, took next the large +tables, and at last the floor of the house! What his wife had to say, +I leave you to judge; as for him he listened to nothing; but, fixing +his eyes on the insatiable furnace, threw in one thing after another, +caring only for the risk to his handiwork. The ceiling would have +followed the floor had not his pots been sufficiently baked without. + +And thus, and thus, does the blood, when combustible matter fails him! +He demolishes the house, and throws it, bit by bit, into the fire. The +fat goes into it naturally enough, as I have already explained to you. +It is the fuel-store of the house. It was put by on purpose, and may +be used up without injury. Then comes the turn of the muscles; more +useful without being indispensable. Those are Bernard Palissy's +palisades one may contrive to do without them. They melt away, so to +speak, after a few days' fast, and you find yourself what people call +"nothing but skin and bone." But then, if this condition is prolonged, +and the exhausted flesh cannot supply the demand, the blood does not +hesitate a moment. He boldly falls upon the most important organs, +without stopping to consider; he, too, is devoted solely to his work, +and that, like the baking of pots, never comes to an end by being +completed; if external help does not arrive in time, the house soon +becomes uninhabitable, and life slips away. The man dies of hunger. + +But in the same way that poor Bernard Palissy was in reality working, +all the time, for his wife and children, whose future well-being he +strove for as the final end of all his efforts, though at the risk of +letting them sleep under the bare heavens; so the blood was laboring +up to the last moment for that very life which he at last turned out +of doors; and the work of destruction which caused its final departure +has had in reality the effect of prolonging its stay. Without it, all +would have been over long before. + + + +LETTER XXIV. + +THE WORK OP THE ORGANS. + +Thus much is settled, then. It is the blood which sets everything in +motion throughout the body. The organs are idlers who would do nothing +but for him; they only work when goaded on, if I may use the expression, +by that fire--always on the point of going out--which he is perpetually +coming back to rekindle, thanks to the oxygen he carries with him from +the lungs. + +This will enable me to explain many things, which, although not new +to you, you have probably never tried to account for before. + +To begin with: do you remember what happened to you the other day, +when you tried to overtake your mischievous brother in running, and +he, taking advantage of his school-boy legs, led you mercilessly through +all the garden walks, without having the grace even to let you catch +him at the end? You were quite out of breath; your heart beat so rapidly +it almost hurt you; and you were so hot that the perspiration poured +in great drops down your face, so that your mamma, quite frightened, +took you up in her arms and carried you to the fire; for the coolness +of evening was coming on, and a little girl drenched with perspiration +is soon chilled. + +Tell me now, what connection was there between your overrunning yourself +in a race and the extraordinary degree of heat which came over you so +soon? Your cheeks were cool and fresh when you began to run; what made +them so red all at once, and especially at a moment when the air was +cool and fresh in the garden? + +You open your eyes in surprise; you had never thought of this. No! +that is just the way with little girls. They run; they get hot; it +seems as natural as warming oneself in the sun, and they never ask why +it is so. + +Yet you could almost tell me the "why" yourself, if you stopped to +think about it, now that you are what your school-boy brother would +say "_up to a thing or two;_" but to save time, I will help you. + +You run as a bird flies, without thinking about it. Nevertheless, if +you could see with a magic glass all that takes place in your body +while those active little feet are carrying it like a feather across +the garden, you would be perfectly amazed. One of these days, when we +have finished our present history, I will tell you that other one, +which is equally worth the trouble. It is enough for the present to +know, that a very complicated piece of work is being carried on there, +in which almost all the muscles of the body take part at the same time, +contracting and relaxing in turn, like so many springs, of which each +either drives forward or holds back a part of the machine. In fact, +while your eyes and thoughts are fixed on the butterfly which is +flitting away from you through the air, there is going on within you +such an unheard-of outlay of efforts as could never be got out of our +idlers if the terrible steward did not lash them severely. + +Now, his lash, as we have said often enough, is that eternal fire, the +materials of which he conveys to all parts of the body. On those special +occasions, therefore, he is obliged to make his fire burn much more +briskly than usual--exactly like railway engine-drivers, who increase +the heat of their fire to get up steam in proportion to the speed they +wish to go. + +From this you will understand that it is no great wonder that your +small frame should get heated from such work as racing and chasing; +and that if you pursue it too long, the perspiration which comes out +all over you is sufficiently explained. + +This is not all, however. The fire, whose strength has to be increased, +naturally requires a larger amount of combustible matter than before, +and forasmuch as there is only a certain fixed quantity in each drop +of blood, whenever the muscles want more than usual, the blood itself +must flow to them in greater abundance. Now if it were a question of +supplying only one part of the body (as it is, you may remember, of +supplying the stomach during the progress of digestion), he might +contrive to accomplish his task there by neglecting it elsewhere, and +overflow one organ at his ease, at the expense of all the rest. But +in this case he is wanted everywhere in the same abundance. It is not +a question of taking one muscle's share for the benefit of another. +From one end of the body to the other, all want to be deluged at once. +And remember that these exigencies do not bring a drop more blood into +the body. How is he to get out of his difficulty then, this overwhelmed +steward of ours? Well! just as your mamma manages, my dear, when there +is more to do than usual in the house;--by running quicker than ever +from the cellar to the garret, and from your room to your papa's! That +is called doubling oneself; and this gallant blood doubles itself to +some purpose. He runs and runs and runs, arrives in hurried streams, +and returns full gallop, passing and repassing through the heart, which +empties and fills itself in sudden jerks. Unluckily, the poor heart +is a delicate sort of person, who does not like having his habits +disarranged, and this forced work soon makes him desperate. The other +day, in his despair, he knocked with all his strength against the walls +of his little chamber, to warn his young mistress that he could bear +no more, and that they were both of them in danger. In fact, you ought +to know that if one was infatuated enough to go on running too long, +one might die of it. When you learn ancient history, you will probably +be told of what happened to the soldier of Marathon, who flew like an +arrow from the field of battle to the gates of Athens, that he might +tell his fellow-citizens a quarter of an hour earlier, that his country +was saved; and he fell dead on his arrival. + +But it is not the heart only which suffers by this mad career of the +blood. During each journey it performs it passes through the lungs, +which in their turn are forced to play with hasty jerks. And this is +well for our good steward; for the lungs, filling with air at each +descent of the diaphragm (if you remember what we have said before), +more air, and consequently more oxygen, comes in, and the blood has +by this means a larger stock on hand, ready to help him out in the +unusual waste which is just then going on in the muscles. I spoke just +now of railway steam-engines. See how self-supporting ours is! The +greater the amount of fire wanted, the faster the blood flows; and the +faster the blood flows, the oftener does the coffer re-fill itself, +whence comes the supply of oxygen requisite for keeping up the fire. +All this goes on at once, by one impulse, and the balance between the +receipts and expenditure settles itself of its own accord. How thankful +many families would be if their money-chest would but fill itself in +the same way--in exact proportion as they spend the cash! There is +only one slight drawback, which is, that the diaphragm gets tired with +the unaccustomed gallop it is thus forced into. It falls into +convulsions, therefore, like its neighbor the heart, and the breathing +is stopped, from having been driven too rapidly. An excellent example +for people who want to spend too much at once; showing that Nature +herself cries out against it, even when the only thing wanted is +atmospheric air. + +Now, run if you dare! And, to tell you the truth, it would be a great +pity if you did _not_ dare; for our good God has made little children +for running. They have nimbler blood than we older grandfathers, more +elastic lungs, and consequently more oxygen to spend at a time. But you +must confess that it is a great pity we should run all our lives as many +people do, without having the slightest idea of these admirable +contrivances, thanks to which we are enabled to do it. We can run all +the same, it is true, without the knowledge, the little child as easily +as the little roebuck, which sets a similar machine in motion. But it is +no use talking about the little roebuck; it cannot learn what God has +done for it, but the little child can, if he will. Furthermore, there is +nothing to be really alarmed about, for those great commotions only +occur when we have committed excess; and it is a very good thing, in a +general way, for the blood to give us a stroke of his lash from time to +time. I told you lately that the fire which sets the organs to work is +life; and it is no misfortune to be a little more alive than usual. +Besides which, this increased activity of the internal fire does not +serve us in running only. Every time that a man makes an effort; every +time he lifts a weight, or handles a tool, the blood rushes forward to +deluge the muscles that are thus called into play; the heart beats more +quickly, and the air streams in greater abundance into the lungs. Look +at a man chopping wood. If the log resists too much, if for a minute or +two the man has to strike blow after blow without stopping, you will +soon see him panting for breath, just as if he had been running a race. +On the other hand, he will have gained something from chopping his log +besides the right of warming himself before it at the fire. Blood does +not carry fire only into the muscles; he supplies them with nourishment +also, does he not? Every drop of blood deposits its little offering as +it goes by, and consequently the greater the number that pass along, the +richer is the harvest for the muscle. Look, accordingly, at the laboring +classes. How much healthier and stronger they are than those who do not +work! I speak, of course, of working with one's limbs generally; for +those poor girls who work from morning to night, sitting on their +chairs, are none the better for it, but, on the contrary, worse. There +are also certain worthy fellows who, like myself at the present moment, +drive a pen over sheets of paper for half a day at a time, whose muscles +never get any bigger for it, that is quite clear. Moreover, one +condition has to be fulfilled, which unhappily is not always done. The +more people labor, the more they ought to eat. To you, who have just +been looking at the drama that is performed in the body every time a +muscle is set in motion, this is obvious enough. There is no fire +without smoke, says the proverb. It would have been much better to +have said,--there is no fire without fuel;--and the fuel for our fire +is, as you know, what we eat. Try if you can get one stove to burn +more brightly than another, if you have put less fuel into it. Yet, +alas! this is what many poor wretches are obliged to do but too often; +and then the blood, instead of feeding their muscles, consumes them, +for the reasons I gave, in telling you the story of Bernard Palissy. +Think of this, oh my dear child, when you are grown up, and never +grudge those who work for you their proper share of food. + +Here I see many other lessons crowding up, out of what you have just +learnt. + +And first Nature herself, taken as you find her, shows you that manual +labor is, for us, a most beneficial condition of existence; that it +brings about a re-doubling, an exaltation of life; and that +consequently, we have no need to look down upon those who gain their +bread, as we word it, by the sweat of their brows. I told you this +before, in speaking of the hand, which is of so much more use to those +people than to you; and I repeat it now for another reason, viz.: +because labor elevates him who undertakes it, and creates a real +physical nobility. Barbarians in old times, who knew nothing noble nor +grand but war, despised labor, and left it to their slaves; so much +so, that the name _servile labor_, _i.e._ the labor of slaves, +has stuck to it in some places. As for war, the lot of the ancient +nobility, I scarcely dare to say much against it, however much I should +like to do so on some accounts. For, after all, so long as there are +ruffians to trample on the weak, one is only too glad to find brave +men ready to risk their lives in keeping such rascals down: so long +as there are wolves, we must needs keep shepherds' dogs. But in spite +of everything, the best that can be said in favor of war is, that it +remains a sad but inevitable necessity, and that to get rid of it, +more is wanting than the wish. What a contrast to labor--that contest +of Man with Nature;--that merciful and fruitful war, where victories +are not estimated like other victories, by the number of the slain, +but which, on the contrary, scatters fresh life around it as it spreads; +fresh life in the laborer himself, by the very act of work, fresh life +around him without, by the fruits that work produces! + +Between the man who dies in slaying others, and the man who keeps +others alive by living longer himself, it seems cruel to make invidious +comparisons; but if it be just to honor the first out of respect for +the cause he has defended, whenever that cause is respectable--it is, +to say the least of it, not less just to do equal honor to the second. + +But let us come down from these philosophic heights, and return to +you, dear child; to you, who have nothing to do with war, its massacres +or its laurels. + +It is true, however, that you have nothing to do either, with chopping +wood, and I am not asking you to undertake any such thing. But in the +life of a woman, from the time of her childhood upwards, a thousand +things arise for the hands to do, and the question is, how often you +are likely to feel ashamed of not sending for the servants to do them? +Avoid this false and fatal idea as much as possible. The work of the +hands dishonors no one; it is honorable. To cast it aside altogether +is to make yourself smaller instead of greater; to deprive yourself +of one of the glories and the joys of life. If a good thing is set +before you at dinner, do you send for the servants to eat it? If an +occasion arises for making the blood circulate more rapidly in your +veins, and of increasing the strength and life with, in you into the +bargain, why make _them_ a present of it? Especially when it +cannot be an agreeable present considering that good servants have +plenty of such opportunities from morning to night every day. + +There was once upon a time a Persian prince staying in Paris, who was +taken to a very fashionable ball, that he might see a specimen of +European civilization. I am not talking about a prince in the "Arabian +Nights;" mine lived, I believe, in the time of Louis Philippe. The +beautiful dancers wheeled round, their eyes brilliant with pleasure, +in the arms of elegant cavaliers; one would have said that the whole +of this airy troop, swaying to and fro in time to the lively flourishes +of the music, was animated by one soul; everything seemed full of joy +in that large and splendidly lit hall, and mothers secretly envied +their daughters as they passed and re-passed before them. Our oriental +alone scanned with a disdainful eye this youthful enjoyment. + +When it was ended,--"How is this?" said he to his conductor; "did you +not tell me that I was to see here the most distinguished families of +Paris?" + +"Certainly," replied the other; "among those young ladies who were +just now dancing before you, there were at least twenty of the grandest +heiresses of France." + +"Young ladies who dance! Come, come! In my country we have dancers, +but they are paid for it. Our wives are never permitted to dance +themselves. That is all very well for the common people!" + +Remember, when needful, the contempt of this Persian prince, my dear +child; and let me beg of you, work for yourself. The dance of labor +is worth quite as much as that of the ball-room, when you give your +heart to it. It is even worth more, very often; and next time I will +tell you why. + + + +LETTER XXV. + +CARBONIC ACID. + +We are going to make acquaintance to-day with a new personage, who +well deserves our attention. It is the child of oxygen and carbon, +[Footnote: This is the name learned men have given to Charcoal.] though +not in the same way that you are the child of your parents. + +To tell you how it is made is more than I am able. It is a _gas_, +or if you like the word better, it is an _air_; for when we say +"gas," we mean "air;" only it is always a different sort of air from +the air of the atmosphere, which learned people are not in the habit +of calling _gas_. I cannot, therefore, show you _carbonic acid_ itself, +for it cannot be seen any more than the air which fills an empty glass. +But I can tell you where there is some, and you even probably know it by +its effects, although you have never heard its name. + +Do you remember, on your aunt's wedding-day, that there was a sparkling +wine called champagne, at the grand breakfast? You smile, so I conclude +somebody gave you a little to taste; and if so, you will remember how +sharp it felt to your tongue. Do you remember, too, how the cork flew +out when they were opening the bottle, and how the noise of the "pop!" +startled more little girls than one? It was _carbonic acid_ which +sent the cork flying in that wild way; the carbonic acid which was +imprisoned in the bottle, in desperately close quarters with the wine, +and which accordingly flew out, like a regular goblin, the moment the +iron wire which held down the cork was removed. What sparkled in the +glass, making that pretty white froth which phizzed so gently, as if +inviting you to drink, was the carbonic acid in the wine, making its +escape in thousands of tiny bubbles. What felt so sharp to your tongue +was the same carbonic acid, in its quality of acidity, for thence it +has its name; the word _acid_ being borrowed from a Latin word +signifying the sharp pungent taste, almost _fine-pointed_ as it +were, peculiar to all substances which we call _acids_. + +It is carbonic acid also which causes the froth in beer and in new +wine when bottled. It is he who makes soda-water sparkle and sting the +tongue, and ginger-beer the same, if you happen to like it; and so far +you have no particular reason for thinking ill of him. But beware. It +is with him as with a good many others who have sparkling spirits, who +make conversation effervesce with gayety, and who are very seductive +in society when you have nothing else to do but to laugh over your +glass, but whose society is fatal to the soul which delivers itself +up to them. This charming carbonic acid is a mortal poison to any one +who allows it to get into his lungs. + +You remember what a violent headache your servant suffered from the +other day after ironing all those clothes you had in the wash? She +owed that headache entirely to this work which she did for you. She +had remained too long standing over the coals over which her flat-irons +were being heated. You know already that when charcoal burns, it is +from the carbon uniting with the oxygen of the air; from this union +proceeds that mischievous child, carbonic acid gas, in torrents, and +the poor girl was ill, because she had breathed more of this than was +good for her health. Observe well, that the room-door was open to let +in the fresh air, and that there was a chimney, to allow the carbonic +acid to escape. It was on this account that she got off with only a +headache. Unhappily, there have sometimes been miserable people who, +weary of life, and knowing this, but not knowing or thinking about the +God who overrules every sorrow for good, have shut themselves up in +a room with a brazier of burning charcoal, after taking the fatal +precaution of stopping up every opening by which air could possibly +get in; and when at last, in such a case, uneasy friends have forced +open the well-closed door, they have found nothing within but a corpse. +Then, too, there are those frightful accidents of which we hear so +often, of workmen groping their way down into long disused wells, who +have died as they reached the bottom; or of sudden deaths in coal-pits. +In general these have been owing to the poor victims encountering the +long pent-up carbonic acid gas, whose poisonous breath blasted and +destroyed them at once. + +You may well ask why I am telling you such horrible stories, and what +I am coming to with my carbonic acid? But you have more to do with it +than you think, dear child. You, and I, and everybody we meet, nay, +and the very animals themselves, since their machines are of the same +sort as ours, are all little manufactories of carbonic acid. The thing +is quite clear. Since there is a charcoal fire lit in every part of +our body, there always arises from the union of the oxygen brought by +the blood with the carbon it meets in our organs, that mischievous +child we have been talking about; and our throat is the chimney by +which he gets away. He would kill us outright were he to stop in the +house. + +This is how it comes about: In proportion as the blood loses its oxygen, +it picks up in exchange the carbonic acid produced by combustion, so +that it is quite loaded with it by the time it returns to the lungs. +There it takes in a fresh supply of oxygen, and discharges at the same +time its overplus of carbonic acid, which is driven out of the body +by the contractions of the chest, pell-mell with the air which has +just been made use of in breathing. You are aware that this air is not +the same at its exit as at its entrance to the body, and that if you +try and breathe it over again it will no longer be of the same use to +you. That is because it has lost part of its oxygen and brings back +to you the carbonic acid which it had just carried off. If you take +it in a third time, it will be still worse for you; and in case you +should continue to persist--the oxygen always diminishing, and the +carbonic acid always increasing in quantity--the air which was at first +the means of your life will at last become the cause of your death. +Try, as an experiment, to shut yourself up in a small trunk, where no +fresh air can get in; or even in a narrow closely-shut closet, and you +will soon tell me strange news. There will be no occasion to light a +charcoal fire for you in there. Enough is kept burning in your own +little stove, and you will poison yourself. + +You see now that the dreadful stories I was telling a short time ago +have something to do with you, and that it is a good thing to be warned +beforehand. And now tell me, when a hundred people--or I ought to say, +a hundred manufactories of carbonic acid--are crowded together for a +whole evening, sometimes for a whole night, in a space just big enough +to allow them to go in and come out; tell me, I say, if that is a sort +of thing which can be beneficial to the health of little girls whose +blood flows so fast, and who require so much oxygen; and whether, on +the contrary, it is not one's duty to keep them away from such scenes? + +There may be amusement there, I know; but the best pleasures are those +for which one does not pay too dearly. I have seen the very wax lights +faint and turn pale all at once, in the very midst of those murderous +assemblies, as if to warn the imprudent guests that there was only +just time to open the windows. + +And this reminds me of a point I had nearly forgotten. Wax-candles arc +like ourselves. In order to burn, they must have oxygen, and, like us, +they are extinguished by carbonic acid. But like us also--and indeed +to a greater extent, because they consume much more charcoal at +once--they manufacture carbonic acid. Hence that very illumination +which affords the company so much pleasure and pride is plainly an +additional cause of danger. Each of those wax-lights which is spread +around with such a prodigal hand, the only fear being that there may +not be enough of them, is a hungry intruder employed in devouring with +all his might the scanty amount of oxygen provided for the consumption +of the guests. + +From each of those cheerful flames--the suns, as it were, of the festive +assembly--shoots out a strong jet of carbonic acid, contributing by +so much to swell out the already formidable streams of poisoned gas, +exhaled to the utmost extent by the dancers. And wait--there is still +something else I was forgetting. You dance. And I told you last time +at what cost you have to dance. You have to make the fire burn much +quicker than usual, that is, to consume a great deal more oxygen at +once, and so you double and treble the activity of the carbonic acid +manufacture: and this just at the moment when it would be so convenient +that it should go on as slowly as possible! After this, you need not +be surprised that people should look fagged and exhausted next morning. +What astonishes me is that they are not obliged to lie in bed +altogether, after treating their poor lungs to such an entertainment. +And even if you have spared your legs, you are not much better off, +as you are sure to find out in time, especially if the thing is repeated +too often. + +When I told you just now that the dance of labor was worth as much as +the dance of the ball-room, was I right or wrong? What do you say +yourself? + +I could repeat the same of theatres--places of entertainment specially +adapted for impoverishing the blood, and ruining the health of the +happy mortals who go there, evening after evening, to purchase at the +door the right of filling their lungs with carbonic acid, not to speak +of other poisons. You must see clearly that such places as those are +not fit for little lungs as dainty as yours; and this may help you to +submit with a good grace when you see people going there without you. +Grown-up people escape moreover, because the human machine possesses +a strange elasticity, which enables it to accommodate itself--one +scarcely knows how--to the sometimes very critical positions in which +its lords and masters place it without a thought. But to do this, it +is well that it should be thoroughly formed and established; for you +run a risk of injuring it for ever, if you misuse it too early in life. +Tell this to your dear schoolboy brother, when he wants to smoke his +cigar like a man. If his lungs could speak, they would call out to him +that it was very hard upon them, at their age, to be so treated, and +that he ought at any rate to wait till they had passed their +examinations! + +But I must not get into a dispute with so important an individual, by +throwing stones into a garden which is not under my care. For you, my +dear child, the moral of this day's lesson--which to my mind is much +more alarming than a hobgoblin tale, since it concerns the realities +of every-day life--is clear; and it is this: + +Seek your amusements as far as possible in the fresh air. In the summer, +when the lamp is lit, bid your mamma a sweet good-night, and go to +bed. In the winter do not wait till there is a great quantity of +carbonic acid in the room where the grown-up people are sitting, before +you retire to your own like a reasonable girl, anxious not to do +mischief to that valuable and indefatigable servant, the poor blood! +Not to mention that if she were to injure him too much, she would have +to bear his grumbling for the rest of her life. We cannot change him +as we change other servants. + + + +LETTER XXVI. + +ALIMENTS OF COMBUSTION. + +We have spent a very long time, my dear child, over the little fire, +which goes on burning secretly in every one of us, quietly devouring +what little girls eat with such a good appetite, quite unsuspicious +of what they are doing it for. However, if I mean to finish the history +of our mouthful of bread, I must push on to its last chapter. + +The _whole_ of what we eat is not burnt, as you may easily suppose; for, +if it were, what would the blood have left to feed the body with, and to +repair in due proportion the continual destruction or waste which goes +on in our organs? Our food, or "_aliments_" as the general collection of +different sorts of food is called, are divided into two very distinct +sets: some, which are destined to be burnt, and which are called +_aliments of combustion_; others, which are destined to nourish the +body, and which are called _aliments of nutrition_. I have to tell you +now about these last, and you will find their history by no means +uninteresting. + +Learned men having detected, beyond the possibility of a doubt, the +existence of these two sorts of aliments, one is tempted to think they +ought to have made it known to the cooks, and that ever since so +important a discovery, the dishes on all well-regulated tables should +have been arranged accordingly; aliments of combustion on one side, +aliments of nutrition on the other. It cannot be enough merely to give +your guests a treat; you ought to provide them with everything necessary +for the proper fulfilment of the claims within; and if you give some +nothing but combustibles, leaving the others no share of fuel, how +will they be able to manage? Nobody thinks about this, however; not +even cooks, to begin with, who, as far as fire is concerned, find they +have had quite enough to do with it in their cooking; and as for the +guests, when they have had their dinner they go away satisfied, as a +matter of course, quite as well provided for as if the mistress of the +house had made her calculations, pen in hand, while writing out the +bill of fare, with a view to combustion and nutrition. Now, how is +that? + +It is because the two sorts of aliments are, for the most part, met +with together in everything we eat, so that we swallow them at once +in one mouthful; and have therefore no need to trouble ourselves further +on the subject. There is our bit of bread, for instance. What is bread +made of? Of flour. Bread, then, must contain all that was previously +in the flour. Very good. Now I will teach you how to discover in flour +the aliment of combustion on the one hand, and the aliment of nutrition +on the other. + +Take a handful of flour, and hold it under a small stream of water; +knead it lightly between your fingers. The water will be quite white +as it leaves it, carrying away with it a fine powder, which you could +easily collect if you were to let the water run into a vase, where the +powder would soon settle to the bottom. That powder is starch--the +same starch as washerwomen use for starching linen, and which our +grandfathers employed in powdering their wigs. You had some put on +your own hair one day when you were dressed up as a court-lady of olden +time. Now, starch is an excellent combustible. People have succeeded, +by means which I will not offer to detail here, in ascertaining almost +exactly what it is made of, and they have found in it three of our old +acquaintances, oxygen, hydrogen, and carbon, combined together in such +proportions that 100 ounces of starch contain as follows: + + Ounces. + Carbon 45 + Hydrogen 6 + Oxygen 49 + --- + 100 +I give you the calculation in round numbers, so as not to burden your +memory with fractions; and I will do the same with the other sums I +shall have to go through to-day, this being, let me tell you, an +arithmetical day. Besides, I could scarcely take upon myself to warrant +the absolute correctness of those very precise fractions people +sometimes go into. Even our learned friends squabble now and then as +to which is right or wrong over the 100th part of a grain, more or +less, in making out their balance, and you and I will not offer to +decide between them. I always think we have accomplished wonders in +getting even _near_ the mark, and with their permission we will +stop there. + +Starch, then, of whose weight carbon constitutes nearly one-half, is +of course a first-rate combustible. Indeed, one may almost consider +it the parent, as it were, of at least half our aliments of combustion, +for if (in consequence of a certain operation, which nature has the +power of performing for herself, in certain circumstances) it loses +a portion of its carbon, so that there remain but 36 ounces of it in +the 100 of starch, our starch is turned into something else; now can +you guess what that something is? Neither more nor less than _sugar_! +Witness the grand manufactories at Colmar, in France, where bags of +starch are converted into casks of syrup by a process of nature alone; +so that the inhabitants of the neighborhood sweeten their coffee at +breakfast with what might have been made into rolls, had it been left +alone. And this is not all. Give back this starch-sugar into the hands +of Nature once more by putting it into certain other conditions, and a +new process begins in it. About a third of its carbon will unite itself, +of its own accord, with the two-thirds of its oxygen, so as to make +carbonic acid, (you are acquainted with that gentleman now) which shall +fly off and away, and there will remain--what do you think?--_Alcohol_, +that other combustible we talked about, and which burns even better than +sugar and starch, since in a hundred ounces it contains as follows:-- + + Ounces. + Carbon 53 + Hydrogen 13 + Oxygen 34 + --- + 100 + +All this astonishes you. What would you say then if I were to tell you +that your pocket-handkerchief is composed of entirely the same materials +as starch, and in the same proportions too, and that if a chemist were +to take a fancy, by way of a joke, to make you a tumbler of sugar and +water, or a small glass of brandy out of it, he could do so if he +chose. Wonders are found, you see, in other places besides fairy tales; +and since I have begun this subject I will go on to the end. Know then +that from the log on the fire, to the back of your chair, everything +made of wood, is in pretty nearly the same predicament as your +pocket-handkerchief; and if people are not in the habit of making casks +of syrup and kegs of brandy out of the trees they cut down in the +woods, it is only, I assure you, because such sugar and brandy would +cost more to make than other sorts, and would not be so good in the +end. Should some one ever invent and bring to perfection an economical +process for doing it thoroughly well, sugar-makers and spirit-distillers +will have to be on their guard! + +But we are wandering from our subject. If I have allowed myself to +make this digression, however, it is because I am not sorry to accustom +your mind early to the idea of those wonderful transformations which +nature accomplishes, and of which I could give you many other instances. + +To return to our flour. As soon as all the starch is gone out of it, +there remains in your hand a whitish, elastic substance, which is also +sticky or _glutinous_, so that it makes a very good glue if you choose; +and hence its name of _gluten_, which is the Latin word for glue. + +When dried, this _gluten_ becomes brittle and semi-transparent. +It keeps for an unlimited time in _alcohol_, putrefies very soon +in water exposed to the air, and is easily dissolved in a wash of soda +or potash. Finally 100 ounces of it contain as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +Observe the last material named. It is a new arrival, of which I shall +soon have something to say. + +But where am I leading you? you will ask, with all these uninteresting +details about glue. + +Wait a little and you shall hear. + +You have probably never seen any one bled, which is a pity, as it +happens; for if you had, you might have noticed (provided you had had +the courage to look into the basin), that after a few seconds, the +blood which had been taken away separated itself of its own accord +into two portions; the one a yellowish transparent liquid, the other +an opaque red mass floating on the top, and which is called the +_coagulum_ of the blood or _clot_. This _coagulum_ owes its color to an +infinity of minute red bodies of which we will speak more fully by and +by, and which are retained as if in a net, in the meshes of a peculiar +substance to which I am now going to call your attention. + +That substance is whitish, elastic and sticky; and when dried becomes +brittle and semi-transparent. It keeps for an unlimited time in alcohol, +putrefies very soon in water exposed to the air, and is easily dissolved +in a wash of soda or potash. Finally 100 ounces of it contain as +follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +This substance is called _fibrine_. It goes to form the fibres of those +muscles which are contained in a half formed state in the blood. + +You are laughing by this time I know, and I also know the reason why. +I have told you the same story twice over. You have not forgotten my +wearisome description of _gluten_, and here I am, saying exactly +the same thing of _fibrine_! You conclude I am dreaming, and have +made a mistake! + +But no, I am wide awake, I assure you, and mean what I say. And if +these details are the same in the two cases, it is for the simple +reason that the two bodies are one and the same thing; _gluten_ and +_fibrine_ being in reality but one substance, so that were the most +skilful professor to see the two together dried, he would be puzzled to +say which came from the flour, and which from the blood. I mentioned +that our muscles existed in a half-formed state in the blood. Here is +something further. The _fibres_ of muscles exist previously in full +perfection, in the bread we eat; and when you make little round pills of +the crumbs at your side, it is composed of fibres stolen from your +muscles which enable the particles to stick together; and I say _stolen +from your muscles_, because they are the _gluten_ which you ought to +have eaten. I hope the thought of this may cure you of a foolish habit, +which is sometimes far from agreeable to those who sit by you. + +This, then, is the first great _aliment of nutrition_, and you +may make yourself perfectly easy about the fate of those who eat bread. +If little girls should now and then have to lunch on dry bread, I do +not see that they are much to be pitied. There is the starch to keep +up their fire, and the gluten for their nourishment, and that is all +they require. The porter above is the only one who finds fault. And +in these days porters have become more difficult to please than the +masters themselves. + +Then as to babies who drink nothing but milk, you perhaps wish to know +where they get their share of fibrine. + +And I am obliged to own there is none in the milk itself; but, I +daresay, you know curdled milk or _rennet_? The same separation into two +portions has taken place there which occurs in the blood when drawn from +the arm; underneath is a yellowish transparent liquid,--that is the +_whey_; above a white curd of which cheese is made, and which contains a +great part of what would have made butter. By carefully clearing the +curd from all its buttery particles you obtain a kind of white powder +which is the essential principle of cheese, and to which the pretty name +of _casein_ is given because _caseus_ is the Latin for cheese. I shall +not trouble you now with details about _casein_; but there is one thing +you ought to know. A hundred ounces of _casein_ contain as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +Exactly like gluten and fibrine! + +Now, then, you can understand that no particular credit is due to the +blood for manufacturing muscles out of the cheese of the milk which +a little baby sucks. He has much less trouble than the manufacturers +at Colmar have in turning their starch into sugar; because in his case +the new substance is not only composed of the same materials as the +old one, but contains them in exactly the same proportion also. + +We have a second aliment of nutrition, you see, and I must warn you +that it is not found in milk only. It exists in large quantities in +peas, beans, lentils, and kidney-beans, which are actually full of +cheese, however strange this may seem to you. It would not surprise +you so much, however, if you had been in China and had tasted those +delicious little cheeses which are sold in the streets of Canton. They +cannot be distinguished from our own. Only the Chinese (from whom we +shall learn a great many things when we have beaten them so that they +will conclude to be friends with us)--the Chinese, I say, do without +milk altogether. They stew down peas into a thin pulp. They curdle +this pulp just as we do milk, and in the same way they squeeze the +curd well, salt it, and put it into moulds--just as we do--and out +comes a cheese at last--a real cheese, composed of real _casein_! +Put it into the hands of a chemist, and ask him the component parts +of a hundred grains of it, and he will tell you as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7, etc. + +I stop there; for you surely know the list by this time! + +Only the third aliment of nutrition remains to be considered, for there +are but three; and I will tell you in confidence, what is stranger +still, viz., that there is in reality but one! But we have had enough +food for one day, and I do not wish to spoil your appetite. We will +reserve the rest for another meal. + + + +LETTER XXVII. + +ALIMENTS OF NUTRITION (_continued_). + +NITROGEN OR AZOTE. + +There is a favorite conjuring trick, which always amuses people, though +it deceives no one. The conjuror shows you an egg, holds it up to the +light that you may see it is quite fresh, then breaks it; +and--crack--out comes a poor little wet bird, who flies away as well +as he can. + +This trick is repeated in earnest by nature every day, under our very +eyes, without our paying any attention to it. She brings a chicken out +of the egg, which we place under the hen for twenty-two days, instead +of eating it in the shell as we might have done, and we view it as a +matter of course. Yet we do not say here that the bird may not have +come down the conjuror's sleeve, or the hen may not have brought it +from under her wing. It was really in the egg, and its own beak tapped +against the shell from within and cracked it. + +How has this come about? No one can have put that beak, those feathers, +those feet, the whole little body, in short, into the egg while the +hen was sitting upon it, that is certain. It is equally certain, then, +that the liquid inside the egg must have contained materials for all +those things beforehand; and if Nature could manufacture the bones, +muscles, eyes, etc., of the chicken, out of that liquid while in the +egg, she would probably have found no more difficulty in manufacturing +your bones, muscles, eyes, etc., from it had you swallowed the egg +yourself. + +Here, then, is an undeniable _aliment of nutrition_. + +It is called _albumen_, which is the Latin word for _white of egg_. It +is easily recognized by a very obvious characteristic. When exposed to a +temperature varying from sixty to seventy-five degrees of heat, +according to the quantity of water with which it is mixed, _albumen_ +hardens, and changes from a colorless transparent liquid, into that +opaque white substance, which everybody who has eaten "hard-boiled eggs" +is perfectly well acquainted with. + +I will only add one trifling detail. 100 ounces of albumen contain as +follows: + + Ounces. + Carbon 63 + Hydrogen -- + +You can fill up this number yourself, can you not? And knowing the 7 +of hydrogen, you may guess what follows! After what we have talked of +last time, here is already an explanation of the chicken's growth. But +let us go on. + +You recollect that yellowish liquid I spoke about, which lies underneath +the _clot_, or _coagulum_ of the blood? I will tell you its name, that +we may get on more easily afterward. It is called the _serum_, a Latin +word, which, for once, people have not taken the trouble of translating, +and which also means _whey_. Put this _serum_ on the fire, and in +scarcely longer time than it takes to boil an egg hard, it will be full +of an opaque white substance, which is the very _albumen_ we are +speaking of. Our blood, then, contains _white of egg_; it contains in +fact--if you care to know it--sixty-five times more white of egg than +fibrine, for in 1,000 ounces of blood, you will find 195 of _albumen_, +and only three of _fibrine_; of _casein_, none. + +Nevertheless we eat cheese from time to time. And we generally eat +more meat than eggs, and meat is principally composed of fibrine! I +should be a good deal puzzled to make you understand this, if we had +not our grand list to refer to. + + Ounces. + Carbon 63 + Hydrogen 7, etc. + +_Fibrine_, casein_, _albumen_, they are all the same thing in the main. +It is one substance assuming different appearances, according to the +occasion; like actors who play several parts in a piece, and go behind +the scenes from time to time to change their dresses. The usual +appearance of the aliment of nutrition in the blood is _albumen_; and in +the stomach, which is the dressing-room of our actors, _fibrine_ and +_casein_ disguise themselves ingeniously as _albumen_; trusting to +_albumen_ to come forward afterwards as _fibrine_ or _casein_, when +there is either a muscle to be formed, or milk to be produced. + +Know, moreover, that _albumen_ very often comes to us ready dressed, and +it is not only from eggs we get it. As we have already found the +_fibrine_ of the muscle and the _casein_ of milk in vegetables, so we +shall also find there, and that without looking far, the albumen of the +egg. It exists in grass, in salad, and in all the soft parts of +vegetables. The juice of root-vegetables in particular contains +remarkable quantities of it. Boil, for instance, the juice of a turnip, +after straining it quite clear, and you will see a white, opaque +substance produced, exactly like that which you would observe under +similar circumstances in the _serum_ of the blood; real _white of egg_, +that is to say--to call it by the name you are most familiar with--with +all its due proportions of carbon, hydrogen, oxygen, and nitrogen. + +I wonder whether you feel as I do, dear child; for I own that I turn +giddy almost when I look too long into these depths of the mysteries +of nature. Here, for instance, is the substance which is found +everywhere, and everywhere the same--in the grass as in the egg, in +your blood as in turnip-juice! And with this one sole substance which +it has pleased the great Creator to throw broadcast into everything +you eat, He has fashioned all the thousand portions of your frame, +diverse and delicate as they are; never once undoing it, so to speak, +to re-arrange differently the elements of which it is composed. From +time to time it receives some slight impulse which alters its appearance +but not its nature, and that is all. As the chemist found it in the +bit of salad, so he will find it again in the tip of your nose, if you +will trust him with that for examination. We are proud of our personal +appearance sometimes, and smile at ourselves in the looking-glass; we +think the body a very precious thing; but yet when we look deeply into +it we find it merely so much charcoal, water and air. + +This reminds me that we have not yet made acquaintance with the new +personage who was lately introduced upon the scene. _Nitrogen_ or +_azote_, I mean. He plays too important a part to be allowed to remain +in obscurity. + +You have already learnt that oxygen united with hydrogen produces +water. Combined with nitrogen it produces air; but in that case there +is no union of the two. They are merely neighbors, occupying between +them the whole space extending from the earth's surface to forty or +fifty miles above our heads; together everywhere, but everywhere as +entire strangers to each other as two Englishmen who have never been +introduced! I should be a good deal puzzled to say what nitrogen does +in the air: he is there as an inert body, and leaves all the business +to the oxygen. When we breathe, for instance, the nitrogen enters our +lungs together with its inseparable companion, but it goes out as it +went in, without leaving a trace of its passage. Nevertheless, as +sometimes happens among men, the one who does nothing takes up the +most room. Nitrogen alone occupies four-fifths of the atmosphere, where +it is of no other use than to moderate the ardent activity of king +oxygen, who would consume everything were he alone. I can compare it +to nothing better than to the water you mix with wine, which would be +too fiery for your inside if you drank it by itself. This is what +nitrogen does. It puts the drag on the car of combustion; as in society, +the large proportion of quiet people put the drag on the car of progress +(let us for once indulge ourselves in talking like the newspapers!); +and such people are of definite use, however irritating their +interference may appear in some cases. The world would go on too rapidly +if there were nothing but oxygen among men. We have quite enough in +having a fifth of it! + +But what in the world am I talking about? Let us get back to nitrogen +as fast as we can! + +We must not imagine there is no energy in this quiet moderator of +oxygen. Like those calm people who become terrible when once roused, +our nitrogen becomes extremely violent in his actions when he is excited +by another substance, and is bent on forming alliances. Sometimes the +usually cold neighbor unites itself to oxygen in the closest bonds; +in which case the two together form that powerful liquid, _aqua-fortis_, +of which you may have heard, and which corrodes copper, burns the skin, +and devours indiscriminately almost everything it comes in contact with. +Combined with hydrogen, nitrogen forms _ammonia_, which is still often +called by its old name _volatile alkali_; one of the most powerful +bodies in existence, and one for which you would very soon learn to +entertain a proper respect, if somebody were to uncork a bottle of it +under your nose. Finally, nitrogen and carbon combined, produce a quite +foreign substance (_cyanogen_), resembling neither father nor mother in +its actions and powers, to the confusion of all preconceived ideas, when +Gay-Lussac, a Frenchman, introduced it to the world, where it fell like +a bombshell upon the theory of chemical combinations. This impertinent +fellow, combining with hydrogen in his turn, produces _prussic acid_, +the most frightful of poisons; one drop of which placed on the tongue of +a horse strikes it dead as if by lightning. + +You perceive that you must not trust our worthy friend too far. You +have learnt, however, elsewhere, that it is not equally formidable in +all its combinations. Those very substances which, when paired off +into small separate groups, destroy all before them, constitute, all +four together, that precious aliment of nutrition of which we are +formed. Moreover, its real name is "_azotized aliment_" because +it is the presence of nitrogen or azote in it, which, above all, +determines its quality, so that people are in the habit of estimating +the nourishing power of our food by the amount of nitrogen it contains. +In fact, nitrogen seems to be a substance especially inclined towards +everything that has life. His three comrades wander in mighty streams, +so to speak, through every part of creation; but he, except in the +vast domain of the atmosphere, where he reigns in such majestic repose, +is rarely met with, except in animals, or in such portions of plants +as are destined for the support of animal life. + +On this point I will tell you the history of his original name, +_azote_, which you will find curious enough. A short time before +the French Revolution, in 1789, the principal properties of this gas +were made known to the world by a learned Frenchman, who may be almost +considered the father of modern chemistry, and whose name I must beg +you to recollect. [Footnote: Dr. Daniel Rutherford (Edinburgh) +discovered the existence of _Nitrogen_, A. D. 1772; but he never +investigated its character.] He was called _Lavoisier_. While +endeavoring to account satisfactorily for _combustion_, which +before his time people explained any way they could, Lavoisier succeeded +in separating our two friends, the neighbors in the atmosphere, one +from the other, and was the first man in the world who managed to +secure in two bottles--on the one hand, the bubbling oxygen freed from +his tiresome mentor; on the other, the sober *azote, snatched away +from his giddy pupil. What he did with the bottle of oxygen matters +but little to us; but in the bottle of _azote_ he plunged, by way +of experiment, an unfortunate mouse, and subsequently a little bird, +both of whom, finding no oxygen to breathe, died one after the other. +Nothing could live in it, as you may suppose; and Lavoisier thought +it must be right to give so destructive a gas the name of _azote_, +which in Greek means "_opposed to life_." Meantime, science went +on progressing by the gleam of the lamp he had lit, and then followed +the discoveries of his successors, who forced their way into the obscure +laboratory where the elements of living bodies are prepared. And at +last it was ascertained that this _azote_, opposed to life as it +was thought to be, was actually an essential property of life; that +it accompanied it everywhere, and that without it the whole framework +of the animal machine would fall to pieces. It is still known by its +old name, which custom had sanctioned; but I imagine no learned man +can ever utter it now without a feeling of humility, and without the +thought that the future has possibly many contradictions in store for +him also. Besides, nitrogen has to pass through many fine-drawing +processes before it attains that post of honor which has been assigned +to it in the animal kingdom. The animal himself can do nothing with +it, unless it has been previously absorbed and digested by the +vegetable, and the vegetable in its turn could get no good from it, +were it to remain isolated and indifferent in the bosom of the +atmosphere. It is only when it has formed one of those combinations +I have been telling you about, and more particularly the second, which +produces _ammonia_, that it fairly enters upon the round of life. +And then, in the mysterious depths of vegetable existence is organized +that wonderful _quadrille_ of the _aliments of nutrition_, the history +of which has now been sufficiently explained to you. + +The vegetable kingdom, therefore, is simply the great kitchen in which +the dinner of the animal kingdom is being constantly made ready; and +when we eat beef, it is, in fact, the grass which the ox has eaten, +which nourishes us. The animal is only a medium which transmits intact +to us the _albumen_ extracted in his own stomach from the juices +furnished to him in the fields. He is the waiter of the eating-house; +the dishes which he brings us have been given him already cooked in +the kitchen. But to appreciate properly the service he renders us we +must remember that the dishes to be obtained from grass are very, very +small, and that it would be a great fatigue to the stomach if it could +only get at such tiny scraps at a time; as, alas! has sometimes happened +to the famine-stricken poor, who have tried in vain to support life +from the grass in the field. But these minute dishes are brought to +us in the mass whenever we eat beef, and our stomachs benefit +accordingly. Do not forget this, my child; and when mamma asks you to +eat meat, obey her with a good grace; if, that is to say, you wish to +grow up to be a woman. + + + +LETTER XXVIII. + +COMPOSITION OF THE BLOOD. + +One word more before we finish. We must not leave off without bidding +a last farewell to the good servant of whom we have spoken so much; +the model steward so exact in giving back everything he receives--the +factotum of the house in short. We have watched him at work long enough, +but I have not yet described him personally to you, nor told you exactly +what he is composed of. + +And here I shall be obliged to begin again with figures and +calculations, although I am told young people are not very fond of +them. Nevertheless, none of us can manage our affairs properly without +them. Hereafter, when you are at the head of a family, you will be +obliged to practise arithmetic, if you want to know what is going on +in your house. Never allow yourself to look upon what is necessary as +wearisome; the true secret of being punctual in our duties is to throw +our heart and interest into them. + +I choose, therefore, to suppose that you will be interested to know +that 1000 ounces of blood generally contain, (for there are shades of +difference between one sort of blood and another) 870 ounces of the +_serum_ I have been talking about, and 130 ounces of _clot_. At first +sight one would take the quantity of _clot_ to be much greater than it +really is; but in the state you see it, in the basin, it contains a +considerable amount of water, which belongs by right to its companion +_serum_, and which has to be drained away from it before it can be +weighed. + +Now, in our 870 ounces of serum, we shall find, to begin with, 790 of +water; do not be astonished at the quantity. Most of the weight of all +animals is produced by water; they weigh comparatively nothing after +being thoroughly dried in a stove--when they are dead of course--for +neither animal nor plant can live unless saturated with water. This, +by the way, may serve to explain the ease with which we can keep +ourselves floating in water; we are not much more than water ourselves! +Were it not for those abominable bones which are a little bit heavier +than the rest, we should never sink unless a stone were hung round our +necks. + +I repeat then; 790 ounces of water in 870 of _serum_, which leaves 80. +Of this, _albumen_ furnishes seventy, and the ten others, with the +exception of a small portion of fat which floats here and there +ready-made, are _salts_. It would take too long to explain what _salts_ +are here, but there is one sort of salt you know perfectly well; viz., +that which is put on the dinner-table in a salt-cellar. And it is the +most important of all. More than half the ten ounces of salts consist of +it alone, which will make you understand better than before, what I +explained with reference to the stomach; that is, why we put salt in our +food. The porter above is quite up to his business when he asks everyone +who enters to produce his little bit of salt. It is an attention which +the blood appreciates very highly, although table-salt is of no great +use to him in his building operations; but it evidently keeps him in +good humor, and he would work badly without it. It is the same with all +the animals man makes use of, and even the plants he cultivates, find +that salt gives them an appetite. And it would almost seem as if nature +had purposely dealt with us in this matter on a magnificent scale. She +has made salt-magazines of the sea and the bosom of the earth, where it +exists in prodigious masses which cost nothing but the labor of stooping +to pick up, except in countries where a gentleman called a tax-gatherer, +stands by to count the lumps and allow them to pass on by paying a +duty. For my part, if I were the government--this is a secret between +you and me, mind--I would look out for something else to stand in the +place of the salt-tax. It is not well to interpose between man and the +gratuities of Dame Nature, and to make him pay more heavily for the +blood's chosen friend than she meant him to be charged. + +But to proceed, the kitchen-salt being deducted from the ten ounces +of salts-in-general, there remain altogether from four to five ounces, +which contain----. But here I stop, for it puzzles me very much how +to go on! Enough, that to enable you to follow me, you would require +at least as much knowledge of chemistry as will be expected of a young +man who has to pass an examination in medicine. Fancy the contents of +a whole druggist's shop! I will tell you a few names, that you may +have a specimen of the style in use, but I forewarn you that they are +not inviting: _hydrochlorate of ammonia; hydrochlorate of potash; +carbonate of lime; sulphate of potash; phosphate of lime; phosphate +of magnesia; lactate of soda._ I spare you the others, for many +others there are, without counting those which have not yet been +discovered I All these things are to be found, I must tell you, in +fibrine and albumen, but in such minute quantities that it is scarcely +possible to recognize them. + +In the serum, for instance, the gentlemen are so very small, and so +completely entangled one with the other, that it is startling to think +of the skill and patience requisite for making them all out, to say +nothing of affixing the right name--uncouth as it may seem--to each +grain of this almost imperceptible dust! He who first called man an +epitome of creation, scarcely knew how truly he was speaking, for man +bears about in his veins, ascertained samples of at least half the +primitive substances from which all others are made, and if the whole +of them should some day be found to be there, I for one should not be +surprised. + +This is well worth knowing, is it not? and I have not come to the end +of my story yet. + +We have still the 130 ounces of _clot_ to speak about. But their +contents are easily reckoned. Three ounces of fibrine and 127 of +_globules_. + +Here, however, we enter upon such a world of wonders, that I am quite +delighted to be able to finish with it. It will be the masterpiece of +our exhibition! + +You feel quite sure blood is red, do you not? Well! it is no more red +than the water of a stream would be, if you were to fill it with little +red fishes. Suppose the fishes to be very very small, as small as a +grain of sand; and closely crowded together through the whole depth +of the stream: the water would look quite red, would it not? And this +is the way in which blood looks red: only observe one thing; a grain +of sand is a mountain in comparison with the little red fishes in the +blood. If I were to tell you they measured about the 3,200th part of +an inch in diameter, you would not be much the wiser, so I prefer +saying (by way of giving you a more striking idea of their minuteness) +that there would be about a million in such a drop of blood as would +hang on the point of a needle. I say so on the authority of a scientific +Frenchman--M. Bouillet. Not that he ever counted them, as you may +suppose, any more than I have done; but this is as near an approach +as can be made by calculation to the size of those fabulous +blood-fishes, which are the 3,200th part of an inch in diameter. + +These littlest fishes are called _globules_; but they are not +exactly shaped like _little globes_, as the word would lead you +to suppose. They are more like little plates slightly hollowed out on +both sides. The central nucleus is surrounded by a flattened margin +rather bladdery in appearance, of a beautiful red color, formed of a +sort of very soft and very elastic jelly. I scarcely need tell you +that all this was discovered through the microscope, and moreover, by +examining the blood of frogs, in which the globules are much larger +than in ours. [Footnote: Authentic portraits of these globules drawn--so +to speak--by Nature herself, are to be seen on the admirable Photographs +obtained by Bertsch, with the aid of the solar microscope, invented +by himself and Arnaud. There you see them magnified 250,000 times, and +may study them at your ease, and verify my description for yourself +without any fear of being deceived. You must persuade your father to +procure one. This result of photography is among the wonders of modern +science.] + +It was in 1661--rather more than two hundred years ago--that an Italian +and a Dutchman discovered, each by himself in his own country, the +microscopic population of the blood. The name of the Italian is not +very difficult--_Malpighi_. As to the Dutchman's, you must pronounce it +in the best way you can--he was called _Leeuwenhock_. You smile, but he +was nevertheless one of the first men who really comprehended what a +wonderful auxiliary human science had just got hold of in the +microscope, and he has helped to open the eyes of the world to the +marvels of miniature creation. So content yourself, young lady, with +mis-pronouncing his name, and beware of laughing at it! Names are +something like faces, one may live to be ashamed of ridiculing +the wrong one. + +This discovery of the globules of the blood, was destined to throw +great light upon the way in which the _nutrition of the organs_ +was carried on. Modern chemists, who are always fond of investigation, +have examined what they are made of, and can find little else in them +but _albumen_. Out of our 127 ounces of globules, 125 are albumen; +and these, with the 70 ounces which we found before in the serum, make +up the 195 ounces (of albumen) which I told you were contained in the +1,000 ounces of blood. Forgive me all these ounces and figures. Exact +accounts give exact information. + +These globules, then, are composed almost entirely of albumen. Nearly +two-thirds of all the albumen in the blood is concentrated in them; +and you know now the use of albumen, viz., that it is the foundation +of all the buildings of which the blood is the architect. Everything +leads us to believe that the formation of globules in the blood is the +last touch given by nature to that magical provision begun in +thevegetable, continued in the stomach, and finished in the veins, to +which, in combination with carbon, hydrogen, oxygen, and nitrogen, we +are indebted for the subsistence of every portion of our body. Thus +the blood-globules may be considered as albumen which has finished its +education, and is ready to go into the world; while the albumen of the +serum is, like our young friends, the generations in reserve, who are +still at school awaiting their turn. + +This is more than a mere supposition. Scientific men have taken to +themselves, on their own authority, all sorts of rights over animals, +and we profit basely enough by their crimes--I will not withdraw the +word--in order to increase our knowledge. Accordingly, they conceived +the idea of opening the veins of animals, and allowing the blood to +flow until the victim was prostrate and motionless as a corpse. This +done, they proceeded to fill the exhausted veins with blood, similar +to that which had been withdrawn, and with the blood, life was seen +gradually to return, till the animal rose from the ground, walked, and +resumed its disturbed existence, as if nothing had happened. The +interesting part of the experiment to us is, that if serum only, without +globules, be restored to the unfortunate animal, it is of no use +whatever, and the corpse does not revive. + +It is evident, then, that all the power and virtue of the blood lies +in the globules; and according as their number is great or small it +is "rich" or "poor," as it is called; and where their number is not +up to the mark, the blood acts more feebly on the organs, life is +calmer, and people are no longer troubled with emotions--in other +words, with violent heats of the blood. Hence the impassible character +of _lymphatic_ people, who often get on in the struggle of life +better than others, because they are never in a hurry, and know how +to wait for opportunities. You will occasionally hear the word +_lymphatic_, for it has become the fashion, and it is time for +me to explain it; but unluckily the explanation is not in its favor. + +You remember those little scavengers we spoke about formerly, who came +from the depths of all the organs, carrying away with them the worn-out +building materials, and covering the surface of the body with an +inextricable net work of tiny canals. These canals are called +_lymphatic vessels_, in consequence of being filled with a liquid +which is called _lymph_ (_water_, in Latin), but why I cannot +tell you, for it is, in fact, simple _serum_. There was a very +simple way of ascertaining this by making out an inventory of the +contents of the _lymph_ liquid, and when this was done, they were +found to consist of water, albumen, and the salts of serum; there was +even a little fibrine; the only thing wanting was _globules_. + +How the truant serum finds its way into the lymphatic vessels is +probably as follows:--I have already mentioned the inconceivable +delicacy of the capillary vessels, those last ramifications of our +arteries and veins. It needs all the impulsive power of the heart to +enable the blood to force its way through these narrow passages; and +minute as are the globules, it would seem that they have but just room +to pass, for in examining under the microscope a corner of the tongue +of a live frog, the globules have been seen doubling themselves up to +pass through the capillaries, resuming their natural form afterwards. + +It was this, indeed, which made me tell you just now that their margins +were elastic. During this momentary crush, part of the serum being +forced on too fast, oozes through the wall of the over-filled +capillaries, as water oozes through the leathern pipes of a fire-engine, +and hence probably the appearance of serum or _lymph_ in the organs, +where it is immediately sucked up (i. e., _absorbed_) by the lymphatic +vessels. Now, you will easily understand that the larger the proportion +of serum in the blood, the greater will be the quantity to be expelled +in passing through the capillaries, and the more will the lymphatic +vessels swell. In such cases the temperament or constitution is said to +be _lymphatic_. If, on the contrary, the globules are in excess, the +lymphatic vessels receive less serum, and diminish in size. The +temperament is then called _sanguine_, as if there were no serum in the +blood. You shall be judge yourself, knowing what you now do, whether it +would not be more reasonable to call such temperaments _serous_ and +_globulous_. At any rate those names would give people an idea of the +real state of things, and teach them that there were such things as +globules in the blood. + +[Footnote: Here is a summary of the contents of 1000 oz. of blood:-- + + Ounces. + Water................... 790 + Serum. Albumen...................70 870 + Salts.................... 10 + + Fibrine................... 3 + Clot. Globules Albumen.. 125 130 + Coloring matter...... 2 127 + ---- + 1000 + ----] + +To conclude, I must give you an account of the two ounces which still +remain of the 127 of globules, albumen taking up only 125, as you know. +Those two poor little ounces--the remainder of the thousand with which +we started--would you believe it?--they alone have the honor of +conferring upon the blood its beautiful red color. They constitute the +coloring matter of the globules, and you will never guess its chief +element. It is iron; ay, actually iron, young lady--the iron of swords +and bayonets. We often accuse it of tingeing the earth with blood; and +you may now know further, that it reddens blood itself by way of +compensation. Do not trouble yourself as to where it comes from. Our +fields are full of it, our very plants have stores of it. It sometimes +happens that our digestive apparatus, put out of order by other +occupations, fails to make use of the amount of iron offered to it; +in which case the blood is discolored, and the face turns pallid as +wax: this is an illness requiring great care. If it should ever befall +you, you will not be surprised, after to-day's lesson, to hear the +doctor say that you must have some iron. But be easy--you will not +have to swallow it whole! If you will take my advice, you will obey +the doctor's orders as soon as you can. + +Not that looking pale signifies any thing: indeed, some young ladies +think it an advantage. But it is no advantage to any body when the +blood-globules are distressed for want of their proper supply of iron, +and do their work grudgingly, like ill-fed laborers. Nothing can go +on without them, you know, and they are people whom it is not well to +leave too long out of sorts. Else languor comes on; languor which is +the beginning of death: and pray remember that iron, which so often +causes death, is equally useful for keeping it at bay. By sending it +to the discolored globules, you give them back their energy and +brilliancy together. + +I have come here to the end of all that is known with any certainty +about these wonderful globules which are to us the medium of life. +Shall I go further, is the question, and take you with me into the +fields of supposition, so full of noxious weeds? And yet why not? +Science owes its present position to the praiseworthy rule of never +adopting any theory which is not supported by well-established facts; +and I would be the last to advise a change. Were I to tell you, what +I am now going to say to you, at a meeting of the British Association +of Science, they would turn me out of the room, and with very good +reason. Nothing ought to be taught there but what can be proved. But +this is of no consequence to you and me, and we have a right to amuse +ourselves a little, after having worked so hard. + +Well, there is an idea which nothing shall ever drive out of my head, +however imperfectly it may be proved as yet; namely, that each of our +globules is an animated being; and that our life is the mysterious +result of these millions of lesser lives, each of them insignificant +in itself; in the same way that the mighty existence of a nation, is +a compound of crowds of existences, each, for the most part, without +individual importance. Take our own or any other country as an instance; +where millions of brains, many of them by no means first-rate in power, +go to form a national character, the highest (as each _nation_ +is apt to think of itself) in the world. According to this idea, you +must be a sort of nation yourself, my dear child, which is gratifying +to think of on the whole. + +This is much more extraordinary than what I told you some time ago, +of the individual life of the organs, each of which on this new system +would be a province in itself! Do not exclaim too hastily. Whether the +globules are animated or not, it is very certain, let me tell you, +that your life depends entirely upon them; that it is weakened if they +are weakened; that it revives with them; and that whether you attribute +individual life to them or not, makes no alteration in the fact: their +action upon you remains the same. And he must be a very clever man who +can show me the exact difference between action and life. Hereafter, +when we have descended the scale of the animal world together, and are +arrived at the study of what are called microscopic animals, you will +better understand the words which appear so strange to you now. What +little our feeble instruments have revealed to us so far, of the history +of those globules, places them almost on a level with those strange +creatures, inexplicable to us, which are found in innumerable +multitudes, in a variety of liquids. We trace in them the beginning +of organization; their form and size are alike in all individuals of +the same species; and species vary enough to induce one to believe, +that there is a necessary relation between an animal's way of life and +that of its globules. If the microscope has not yet caught them in any +overt living act, who can be surprised? it is only dead blood which +has been submitted to the test. They ought to be observed in the +exercise of their functions, in the living animal itself, as has been +done to some extent in the frog; and if our foolish chat could influence +scientific observers, I would say to them what M. Leverrier said years +ago to the astonished astronomers: "Look yonder; you ought to see a +light there with which you are not yet acquainted!" + +I am carrying you a long way on the wings of my fancy, my dear child; +but have no fears; I will not let you fall. This life of our globules, +which would, after all, be only one mystery the more among many, opens +before our eyes a magnificent vista of the uniformity in the scheme +of creation; which goes on repeating itself, while enlarging its circles +to infinity. We may, all of us, be only so many globules of the great +invisible fabric of humanity, in which we go up and down one after +another; and those vast globes which our telescopes follow through +celestial space, may be but globules of one, as yet unknown, to which +the Almighty alone can give a name. + +Take this page to your father, my dear child, if you do not understand +it rightly; and now, shake hands, my history is ended! + + + +PART SECOND--ANIMALS. + +LETTER XXIX. + +CLASSIFICATION OF ANIMALS. + + +'It is dangerous to show man how much he resembles the beasts, without +at the same time pointing out to him his own greatness. It is also +dangerous to show him his greatness, without pointing out his baseness. +It is more dangerous still to leave him in ignorance of both. But it +is greatly for his advantage to have both set before him.'--_Pensees +de Pascal_. + +The man who wrote that, my dear child, did not trouble himself much +about children. He was one of the gravest specimens of literary +genius--a man who can scarcely be said to have ever been a child +himself; for as the story goes, he was found one day, when only twelve +years old, inventing geometry, and his father only saved him from +trouble, by putting the great book of Euclid into his hands; and, at +sixteen, he wrote a treatise on _Conic Sections_, which was the +wonder of all the learned men of the day. I have not a very clear idea +of what Conic Sections are myself; but I tell you this to show that +Pascal was a very profound and learned man, under whose authority, +therefore, I am very glad to take shelter, now that I am going to set +before you the very startling points of resemblance which exist between +you and the beasts. + +As to your greatness, it delights me to explain it to you. It is not +due to the handsome clothes you wear when you are going out, nor to +the luxurious furniture of mamma's drawing-room, but to the possession +of that young soul which is beginning to dawn within you, as the sun +rises in the morning sky, and pierces through the early mists; in that +growing intelligence which has enabled you to understand so far all +the pretty stories I have told you; in that fresh unsullied conscience, +which congratulates you when you have been good, and reproves you when +you have done wrong: all of them gifts which are not bestowed on the +lower animals, or certainly not to the same extent as upon you--gifts +by which you rise more and more above them, the more they are developed +in yourself. Your baseness--but, begging Pascal's pardon, I cannot +call it baseness--your connecting link with the brute creation lies +in those other gifts of God which you and they share in common--in +those wonders of your organization, which we shall now meet with in +them again, in full perfection at first, and that in every respect; +by which fact you may learn, if you never thought of it before, that +the lower animals come from the same creating hand as yourself, and +ought to be looked upon to some extent as younger brothers, however +distasteful such a notion may seem at first. Societies have been +established of late, both in France and England, for the protection +of animals; and a noble and honorable task they have undertaken, in +spite of the jokes that have been made at their expense. It is a +mischievous cavil to tell people who are doing good in one direction, +that more might have been done somewhere else. Everything hangs together +in the progress of public morality, and you cannot strike a blow at +cruelty to animals without at the same time making a hit at cruelty +to man. And the best argument in favor of the rights of beasts to +protection, will be found in the tour you and I are now going to make +together through the different classes of the animal creation. + +Let us begin with the horse--one of the beasts which oftenest needs +our protection. Give him the mouthful of bread whose history we have +just finished. He accepts it as a treat, and needs no pressing to eat +it. And if it could tell you all its adventures afterwards, you would +find that you were listening to precisely the same story as your own +over again; that nothing was different, nothing wanting. First of +all--teeth to grind it, and a tongue to swallow it with, as a matter +of course. Next a _larynx_, which hides itself to avoid it, and an +oesophagus,* which receives it, just as in your case; a stomach with its +_gastric juices_, the same as yours, in bagpipe form, and its _pylorus_, +like your own; a _lesser intestine_, into which bile pours from a liver +like yours; _chyliferous vessels_ which suck up a milky chyle, as with +you; farther on a _large intestine_; and so on to the end. Nor is this +all:--the horse has also a heart, with its two _ventricles_, and its +double play of valves; a heart which the little girl in our tale might +confidently have exhibited to the engineers as her own, but that it +would have been somewhat too big, of course; into which heart, as into +ours, comes _venous_ blood, to be changed afterwards to _arterial_; in +lungs to which the air keeps rushing, forced thither by the see-saw +action of a _diaphragm_, as faithful a servant to him as to you. +And those lungs like our own, are a charcoal market: the same exchange +takes place there, of carbonic acid for oxygen, as in ours, an +unanswerable proof that the stove inside the horse burns fuel in the +same way as our own: and if you were to place the thermometer inside +his mouth (for we are polite enough to call it his mouth), it would +mark 37 1-2 degrees of heat (centigrade)--a difference from ourselves +not worth mentioning. Finally, if you examine his blood, you will meet +with the same _serum_ and _clot_, the whole company of _hydroclorates, +phosphates, carbonates, &c._, from which we shrank before, and globules +made like your own; having the same construction, and the same life, or +action, if you like it better. I need scarcely add that 100 oz. of its +_fibrine_ and _albumen_ contain: + + Of carbon......... 63 oz. + Of hydrogen........ 7 + +This is understood all along as being the case everywhere, from man +down to the turnip; so that, like you, this noble animal, as the horse +is called, is in point of fact only so much carbon, so much water, and +so much air, joined to a handful of salt, which represents the earth's +share in the bodies of animals. + +You must confess that, if we cannot quite call the horse a +fellow-creature, he is nevertheless very like us. And it is the same +with all those animals which man makes use of as his servants, and +which have really a sort of right to the protection of society, since +they form, to a certain extent, a portion of the human family. I do +not speak here of the dog, who pays his taxes, poor fellow, in his +quality of friend to man. + +When I think of the almost identical organization of man and his +next-door neighbors, I am astonished how it could possibly have come +into the head of a certain learned individual (I will not mention his +name), when drawing up a plan of natural history, to give to man a +separate kingdom, as a sequel to the three kingdoms already +established--the mineral, vegetable, and animal. One might have forgiven +Pascal if such an idea had got into his head after writing his treatise +on Conic Sections; there being nothing in them to throw light on such +a subject. But in a naturalist, an observer who had spent his life in +the study of living creatures, the thing seems almost incredible. +Possibly he had reasons for what he did, but he certainly did not find +them in the subjects of his studies. + +Forgive me, my dear child, for forgetting you in this fit of indignation +upon a point you cannot care much about. It leads me naturally enough +to my present business, which is none of the easiest, but you must +help me by paying attention. I am going to describe the _classification +of the animal kingdom_. + +There are a terrible number of animals, as you know; and if we wish +to study them to any real purpose, we must begin by introducing some +sort of order into the innumerable crowds which throng, pell-mell, +around us for observation. We should otherwise never know where to +begin, or when we had come to an end. + +There are many ways of setting a crowd in order, but they all go upon +the same plan. The individuals composing the crowd are parcelled off +into companies, each company having a distinguishing mark peculiar to +those who compose it. Thus the first division is into a few large +companies, which are afterwards subdivided into smaller ones, and those +into others still less, until the divisions have gone far enough. And +this is what is called a _classification_. + +Let us imagine, as an example, a large crowd in a public garden; I +will soon classify it for you. I shall put the men on one side and the +women on the other. Then--to begin with the women--I shall subdivide +them into married and single. Then among married women I shall make +a company of mammas, and another of those who have no children. Among +the unmarried I shall have a group of those who have never been +married--girls, that is--and another of widows--those who were once +married, but are so no longer. Then, following the girls, I shall +separate them into tall and short. And among the short ones I shall +divide the brunettes from the blondes, and so I shall get at last to +a little blonde girl, whose classification (were she a soldier) in +military rank would be as follows:--_squadron_ of blondes; _company_ of +shorts; _battalion_ of girls; _regiment_ of unmarried women; _division_ +of women. The division of men could be carried out in the same manner; +and thus we should classify our mob into complete military order. This +is easy enough, however; but the classifying of animals is a very +different affair, and I will tell you why. We ourselves require a +classification to study them by, though none was needed for their +creation. The Almighty has formed them all on one uniform plan, around +which He has, if I may so express it, lavished an infinity of +modifications separating species from species, yet without placing +between the different species those fixed barriers which we should +require now to enable us to classify them strictly. You who are learning +the pianoforte have perhaps been told the meaning of a _theme_ of +music--the first idea of the composer who follows it throughout the +piece from one end to the other, embroidering on it, as on a bit of +canvas, a thousand variations melting one into another. Such is pretty +nearly, if we may venture the comparison, the way in which we can +picture to ourselves the Almighty moving through the work of animal +creation. Step in afterwards and divide away into regiments and +battalions, if you please. Nature permits it, but she will never, +to accommodate your classifications, separate what in her is really +united. + +There is still a way, however, and that is to do as I did just now in +the case of the crowd. To take, viz., only one _character_ (as we call a +distinguishing mark in natural history), and to throw together all the +individuals which possess it, the blondes, the shorts, the girls, &c. In +this way it may soon be done; but what is the result? You are in one +class, your eldest sister is in another, your mamma in a third, and your +brother in a different division altogether, a long way from you all. +Such a classification is called _artificial_, and you can see at once +that it is worthless. + +The most natural plan is to put together those that are of the same +family; and the classifications made on this principle are called +_natural_ classifications. + +It is a classification of this sort which has been adopted for the +animal kingdom. People have taken all the animals which possess in +common not one character only, but a collection of characters of the +most important kind, _dominant characters_, as they are called; +and of these animals they have formed, to begin with, large primary +groups; subdividing these afterwards according to the secondary +differences, which distinguish different species in the same group +from each other. + +In this manner all the different sorts of animals are included in +different systematic divisions of one vast whole, through which it is +easy to find one's way, because there is a beginning and an end; and +in which animals of the same family are always grouped side by side. +Were I to mention all the divisions of this immense classification at +once, you would find the account a little long, and not very amusing. +We will go through them by degrees therefore, and, to simplify matters, +will, throughout the whole, only consider those particular characters +which are connected with our special study, the nourishment of life, +that is to say: so that you will always find yourself on well-known +ground. + +I must tell you once for all, however, that it is with this as it is +with grammar. Here and there are--and it cannot be avoided--certain +exceptional cases which keep protesting timidly against the +arbitrariness of rules; but no matter; we must be contented with what +we can get, and be grateful into the bargain to those who have given +us this skillful classification, at once so ingenious and useful, in +spite of its inevitable imperfections. What is impossible is expected +of nobody. You could not understand, even if I wished to explain it +to you, the amount of science, labor and genius requisite for making +out that long list, which, tiresome as it may seem to children, is +absolutely beautiful in the eyes of learned men; too beautiful, perhaps, +and I will tell you why when we have finished. Meantime, as the best +reward we can give to those who have done us some great service is to +teach their names to children, I will tell you, before bidding you +good-bye, to whom we owe this classification, the details of which I +do not enter upon to-day. + +In the first place, we owe the method employed in its establishment, +the method of _natural classification, i.e._, to a learned man +of the last century--a learned Frenchman, Bernard de Jussieu--who tried +it upon plants; another large flock by no means very easy to put in +order, as you may convince yourself any day by studying botany. The +man who applied this system to animals was also a learned Frenchman, +the clearness of the French mind adapting them peculiarly for that +sort of work. And he, too, is one of the glories of that nation. His +labors and discoveries gave a perfectly new impulse to the study of +nature. It was George Cuvier, whose statue you may see at Montbeliard, +if you should ever go there. Not that Cuvier carried through this +gigantic work alone, though the credit of it is justly his due, he +having directed and inspired it. He was assisted by many. But among +his assistants there was one, Laurillard, the most modest, yet the +most active of all, whose name I will mention also, because, like the +others, more or less celebrated, he has never had his reward. [Footnote: +In the earlier editions of this work, there was, in this place, a +severe reproach upon Cuvier for not having given proper credit to +Laurillard. This reproach I have since learned was unjust. M. +Valenciennes himself, one of the most illustrious of the collaborators +of the great Cuvier, has written me a letter in which he defends the +reputation of his friend with a warm indignation which does honor to +both of them; and cites passages in which Cuvier has spoken of +Laurillard, and among others, in the third volume of the _Ossements +Fossiles_, p. 32, ed. of 1822.] + +It only remains for me, therefore, to let the lash, which I was laying +upon the shoulders of another, fall now upon my own, and to deplore +the too great facility with which I had credited, without sufficient +proofs, an assertion which I had otherwise good reason to believe to +be exact--coming to me, as it did, from Montbeliard himself, on the +testimony, it is said, of the family of Laurillard. From this avowal, +a little painful, I confess, my young readers may learn the +inconvenience of rashly condemning others! As I said in the concluding +passage, which truth, only too late, now compels me to suppress--"The +truth is sure to come out at last." + + + +LETTER XXX. + +MAMMALIA. (_Mammals_.) + +Do you remember of my talking of the _vertebral column_ when I was +describing that great artery, the _aorta_, to which it forms a rampart +of defence? I should not have named it without explanation, but that you +had only to pass your hand down your back to find out what it was. Now +the _vertebral column_, or backbone, is one of those _dominant +characters_ which always carries along with it a train of other points +of resemblance in the animals where it is found. It has been chosen, +therefore, as the rallying-point of the first great group. I must tell +you beforehand that there are four of these groups, four large +companies, _i.e._, which naturalists have called by various names; as +Groups, Sections, Primary Divisions and even Branches; in this case +comparing them to four great branches of a tree, going off in different +directions from the same trunk. + +And, first of all, we have to begin with the group of the +_Vertebrata_--vertebrata animals--vertebrata being a word which +explains itself. + +Of course we ourselves belong to this group. In fact, we are at the +head of it; but it descends far below us. It goes on to the frog and +the fish, and includes the monkey, the ox, the fowl and the lizard; +for all these creatures possess the vertebral column. The frog does +not appear to be very much like us at first sight; and yet, by virtue +of its vertebra, it has its points of resemblance to us, which are +worth the trouble of considering. Vertebrated animals are all furnished +with a head, containing a brain, which gives its orders to the whole +body; they have all an internal skeleton, that is to say, a system of +bones linked together, forming a solid base by which all the organs +are supported. I was going to add that they have all four limbs; but +here the serpent glides in to call me to order, and to hiss at our +childish craving for fine-drawn divisions, in perfect order, where +there is an exactly proper place for everything. However, each has, +without exception, a heart, with its network of blood-vessels; red +blood, under its two conditions of arterial and venous; and also a +digestive tube, acting, on the whole, pretty much like our own. I do +not insist, mind, upon this last point, viz., that of the digestive +tube; for we shall see, by-and-by, that it is a character beyond the +pale of the primary groups. It is the fundamental character of the +trunk itself, which necessarily exists, therefore, in all the groups; +and, as I told you in my first letter, you will find it everywhere. + +This is--to let you into the secret at once--the theme on which the +Great Composer has based all His infinite varieties of animal life; +and herein lies the uniformity of the animal creation, that startling +uniformity which has given so much offence to many learned men, and +which is so obvious that it will strike you of itself, I feel sure. +But I reserve this subject to the end of my letters, when you will +have heard all, and be able to judge for yourself. + +It would be plunging back into confusion to attempt to examine all the +vertebrated classes at once. After making a division you must go on. +The groups have, therefore, been subdivided into _five classes_, which +we will study in succession, only naming each now: viz. _mammals_, +_birds_, _reptiles_, _fish_, and _batrachians_. Do not alarm yourself at +this last name: it is a Greek word, meaning simply frogs. + +The mammals are our immediate neighbors. Mammalia are the animals which +produce milk. They bring forth their young alive, and give suck to +them as soon as they are born. This was your first nourishment, my +dear child, so you yourself are a little mammal. + +What I said to you in the last letter about the horse, applies pretty +nearly as well to all mammals. We shall not, therefore, have any great +variations to notice here. Nevertheless, as these are the animals which +interest us most nearly, as they are in fact our nearest of kin, so +to speak, and those with whom we have the most to do, we will now pass +in review the different orders of which their class is composed. I +must explain to you that the _classes_ are subdivided into +_orders_, the orders into _families_, the families into +_genera_, the genera into _species_; as in armies divisions +subdivide into regiments, regiments into battalions, &c. It became +necessary, moreover, to make use of special names, in order to make +these subdivisions comprehensible, and the following are those which +have been adopted. + +ORDER 1. _Bimana (two-handed)_. + +Here we may pass on at once, for we have discussed this order enough +already. We are _bimane_ ourselves, since we have the distinction +of possessing two hands. Yes; that is the pretty title which the +professors have been so polite as to give us, instead of leaving us +simply our proper name of man. Yet it would have been very easy to do +this, seeing that we are the only family, the only genus, and the only +species of the order. In railway travelling, people of distinction +have a reserved carriage to themselves: so we decidedly deserve an +order to ourselves; but that is not quite the same as a separate +kingdom. In short, you are a _bimane_; so make the best you can of it. + +ORDER 2. _Quadrumana (four-handed)_. + +These, as their name indicates, have four hands: two at the end of the +arms, and two at the end of the legs; such are the monkeys. There is +nothing to remark; they are all alike. Stay; I am wrong, though: there +is something, insignificant it is true, but still pointing to deviation. +In some the canine teeth are set forward, _i.e._ project, and are +longer than the rest, and some species, as the ape, for instance, have +just under their cheeks convenient little pockets, which open into the +mouth, and in which they can deposit a reserve of nuts to be devoured +at leisure; these are called _pouches_. + +It is a trifle in itself, but we have here a first example of the +eccentricities of nature in the construction of animals. At one time +she adds a detail; at another she suppresses one. Sometimes she is +pleased to enlarge an organ, as in the canine teeth of the monkey; +sometimes she reduces it; or perhaps here she makes its construction +more simple; there again more complicated: but still it is always the +same organ. So the dressmaker shapes the sleeves of a dress, sometimes +open, sometimes closed, flat or puffed, plain or ornamented, +pagoda-shaped or gigot-formed: but still they are all of them sleeves. + +ORDER 3. _Cheiroptera (wing-handed)_. + +I am quite ashamed of offering you such a word as this, my dear child. +It was a Greek fancy of the learned men, who would not condescend to +use the vulgar name Bats. In the Greek, _cheir_ means hand, and +_pteron_ wing. The Cheiroptera are animals with winged hands; in +fact, the fingers which terminate the fore-limbs of the bat lengthen +as they spread out to an extravagant extent; and are connected together +by a membrane springing from the body, with which they beat the air +as with a wing, and which enables them to fly with such ease that +theyare often taken for birds. + +But, so far from really being a bird, this curious little creature has +the same internal organization as ours, and indeed comes so near us, +though without looking as if it did, that a scientific man, and a very +distinguished one too, placed the bat in the first family of the animal +kingdom, with the monkey, and, you will hardly believe it, with man. +It is found that the bat, like man and the monkey, suckles its young +at the breast; and it was this very character which Linnaeus, the leader +of artificial classification, thought of selecting as the distinguishing +mark of his first family in the animal kingdom. It is true that in +honor of the human race he had given that first family a much more +sonorous name than our usual one of _man_--viz. _primates_, the first in +rank--that is, the princes. But, alas! we were to be princes on an +equality with bats; and, for my own part, I prefer being a _bimane_, and +alone. I really believe that it was to put this saucy little creature +back into its proper place that, at the time of the great revolution in +favor of natural classification, the conclave of professors assembled at +the Botanical Gardens in Paris inflicted this horrid name of Cheiroptera +on the bat, ejecting it contemptuously from the overthrown dynasty of +the _primates_. + +I have not been sorry to make you acquainted as we went along, with +this little trait in the history of classification; but beyond it there +is really nothing particular to say about the apparatus for the +nourishment of the deposed bat-princes, which is a plain proof how +nearly it must be like our own. By-the-by, there is one trifling remark +to be made with regard to her teeth. The bats we have in our country +(France), for there are many varieties of species in the world, live +on insects, which they catch in their flight by night. These insects +are often enveloped in a very hard outer case, which molars like ours +would have some difficulty in chewing properly; consequently the molars +of our little friend are fringed with conical points, and with these +she grinds down her prey without difficulty. + +In America there is a large bat, the vampire, which lives on the blood +of animals, and nature has armed it accordingly. It has at the +extremityof its muzzle two sharp beak-like incisors, like the lancets of +a surgeon. The vampire bat, which roams by night like other bats, goes +straight at the large animals it sees asleep, delicately opens a vein +in the throat without waking them, and sucks their blood in long +draughts, taking care, by fanning them with its wings, to lull them +into a cool and balmy slumber. It does not, as you see, make a savage +attack on its victim: it merely inflicts a bite like that of the leech, +but the result may be death. This is the best emblem I know of the +sycophant, who undermines your soul while he fans your vanity; and +observe, while we are on the subject, that this species has always had +the art of insinuating itself among princes. + +ORDER 4. _Carnivora (flesh-eaters)_. + +When translated into English, this word needs no explanation. And here +we have the tribe of bears, wolves, foxes, weasels, dogs, cats, tigers, +lions, of all the fighting animals, _i.e._, those which steep +their muzzles in blood, and live by devouring others. These have a +similar apparatus for nutrition to our own; especially the bear, who, +with the monkey, is the animal most nearly resembling man, seeing that +he has feet like ours, with scarcely any tail, while the monkey has +our hands, without specifying any other points of resemblance. Like +ourselves, too, the bear is omnivorous; that is to say, it eats +everything, vegetables and fruit as well as meat; and nature, which +has given it our diet, has furnished it with molars almost exactly +like our own. Its canine teeth alone differ from ours: they are more +prominent even than those of the _quadrumana_; and this is the +case with all the members of the order, in whom we find them sometimes +developed into actual daggers. But those of them which are purely +carnivorous have molars peculiar to themselves. The lion, for example, +who does not share the bear's taste for carrots, and who would die of +hunger surrounded by the honey and grapes of which the bear is so +fond--the lion, who never takes anything but raw meat between his +teeth, has molars furnished with sharp cutting edges, intended to slice +the meat like the chopping knives used by cooks for making a hash. + +The lion offers another peculiarity, which is common to him with all +the _Carnivora_. Place your finger close to the lower end of your +ear, and work your jaw; you will feel something hard moving backward +and forward against your finger. This is where the lower jaw is set +into a bone of the skull, called the _temporal_, if you care to know its +name; in other words, the bone of the temple. The extremity of the jaw +bends, and forms a kind of little knob, called _condyle_, which fits +into a cavity of the temporal bone. With us the cavity is not very deep, +nor the knob very large, so that it can play very freely; and it is this +which allows us that second movement from side to side, of which I spoke +to you formerly, and thanks to which, our little mills reduce a mouthful +of bread into paste. But this freedom of action has also its +inconveniences. You must never attempt to force too large an article +into your mouth at once--an apple, for instance--the efforts you would +then be obliged to make might easily cause the _condyle_ to slip out of +its little cavity, where its hold is but slight, and to get under the +_temporal bone_; and there you would be with your mouth wide open until +the doctor arrived. The lion, whose voracious jaw opens like the door of +an oven, so that the tamers of wild beasts have no scruple in thrusting +in their whole heads, a mouthful a good deal larger than an apple; the +lion, who has no doctors, would often be liable to this accident--an +irremediable one in his case--if nature had not made a special provision +for him. In order to secure greater firmness and strength, the second +movement is in his case sacrificed by embedding the _condyles_ +deeply in their cavities, where they are fastened in such a fashion +that they can only move up and down, like the handles of a pair of +pincers. This is a restraint which enables the jaw to be safely thrown +open as wide as the fiery impulse of its terrible proprietor impels +it. Less freedom, in exchange for more power, is a bargain which any +one would gladly accept who plays the part of a lion! + +I have here a remark to make. We have now passed in review three orders +besides our own, and have only had to point out a change in the +fastenings of the jaws and in the teeth; and you will find that the +same sort of modifications take place in the whole class of mammals. +This is in fact the essentially movable and variable point in their +apparatus for nutrition. The jaw and its weapons vary their character +from one species to another, according to the nature of their food; +but the modifications generally terminate there, _i.e._ on the +threshold, as it were. The interior arrangements of the house remain +otherwise much the same in all. + +Here, however, in the lion, there is an interior change to be described; +but not in the arrangement of the parts, only in their size; the stomach +in this species being even smaller and weaker in proportion than ours, +and the digestive tube more than twice as short. The digestive tube +of an ordinary sized man is about seven times the length of his body, +whilst that of the lion only measures three times the length of the +animal. This is a natural consequence of the kind of nourishment he +takes. Flesh and blood, on which he lives entirely, is concentrated +_albumen_, prepared beforehand in the bodies of his victims; so +that no great preparation is needed here to convert it into lion's +blood. A professor of chemistry, who has a good assistant, does not +need a very large laboratory. This is the case with the lion; and +nature, which makes nothing in vain, has here economised space. Tame +the monarch of the forest into a domestic animal, and change his food, +and I will wager anything you please that, in the course of a few +generations, his digestive tube will lengthen itself. Examine the +inside of the cat, his little cousin, formed originally on the same +pattern as himself, and, without having ascertained the fact myself, +I am sure that, by dint of feeding it daily on sops and milk from +generation to generation, its digestive tube has become more than three +times the length of its body. + +Here you ought to be told at once a very important fact relative to +the organization of the lower animals, one which places them all very +far below the order of _Bimana_, since there is such an order. +In bestowing intelligence and freedom of action on man, the Almighty +has given him the unspeakable privilege of working in His footsteps--if +I may presume to use the expression--of following up His work of +creation as it came from His hand. Now especially that man begins to +see a little more clearly into the laws of life, he has entered more +directly into the possession of this almost divine privilege, which +the Almighty has graciously vouchsafed him. You can even now have an +ox or a sheep made to order in England, giving your dimensions, as if +you were ordering a cabinet; and in a few years, if you have not asked +actual impossibilities, your commission will be executed to within an +inch. This is not said in reference to the _Carnivora_. But in +bidding you good-bye, my dear little mammal, I could not bear to leave +you under the weight of that debasing title: I wanted also to show you +your greatness. + + + +LETTER XXXI. + +MAMMALIA. _(Mammals)--continued_. + +Let us continue to pass in review the different orders of the class +Mammalia. We may meet elsewhere with facts more important to science, +but nowhere with any so personally interesting to ourselves. + +ORDER 5. _Insectivora (insect-eaters)_. + +This order devours insects, as their name tells you plainly enough. +They feed in the same manner as the bats; consequently they have molars +like theirs, as was necessary. It is an unimportant little family, and +we will not waste much time upon it. The chief of the order is the +hedgehog, a native of our country--not very large, about nine inches +long--which lives in the woods, and which when rolled up into a ball, +with all its quills standing out, looks very much like an enormous +horse-chestnut in its shell. Its canines have not much work to do, +consequently they are very small; but, on the other hand, its two front +incisors are prolonged beyond the others, the better to seize its prey, +which creeps upon the ground. Internally there is nothing to remark +upon. + +Next to the hedgehog I will mention as a curiosity the shrew or +sand-mouse, which, in spite of its name, is no mouse at all, but has +the honor, if honor it be, of being the smallest animal known of the +class Mammalia. + +It is about two inches in length altogether; and if you carefully +examine its little body, you will find that it contains all the organs +you possess yourself--oesophagus, stomach, liver, intestines, veins, +arteries, heart, lungs--nothing is wanting: the machinery is absolutely +the same. + +ORDER 6. _Rodentia (rodents)_. + +Were we to translate this word into its meaning, namely, the _Gnawers_, +there would be some comfort in it, for we would at once know what it +means: but no matter. Rodents, or Gnawers, are rats, hares, rabbits, +beavers, marmosets, squirrels, in fact all the creatures which _nibble_. +To _nibble_, if you do not exactly understand the word, means to chew +with the points of the teeth. The rodents have no other way of eating +but by filing, if one may so say, their food with the points of two +incisors with which both the jaws are provided; these incisors are very +long, much longer even than those of the hedgehog. The next time you see +a rabbit at table, ask to see the head; and you will find that it has +four pretty little teeth, very sharp, shaped like a joiner's chisel; +that is to say, with a "bevelled edge," to use the received expression; +in other words, with one edge thinner than the other. + +Here, then, we begin to diverge from the old model. First, there is a +different fastening, or _articulation_, as it is called, of the jaw. Its +_condyles_, which we saw just now in the _Carnivora_ enlarged +transversely and deeply embedded in the _fossae_ or cavity of the +temporal bone, extend here longitudinally; an arrangement which enables +the jaw to move backward and forward at pleasure, like the arm of the +locksmith when using the file. Furthermore, those little teeth, which +are constantly rubbing against each other, would be very soon worn out, +if, like our own, they were made once for all; accordingly their germ, +or _pulp_, to use the proper term, instead of perishing, as with us, +when the tooth has once come, retains its life, and works on throughout +the life of the animal. They sometimes say of a man who has not eaten +for a long while, that his teeth have grown long. This is a joke with +us; but in the case of a _rodent_ would be too serious a matter to be a +joke; for, as their incisors are always growing, like our nails, they +would soon become too long if the animal ceased for any length of time +to wear them down by eating. It is for this reason that rats and mice +have such incessant appetites, and that with them "all is fish that +comes to the net;" old books, rags, and even planks of wood, which they +will gnaw for want of something better. Come what may, they must keep up +at an equal rate the wear and tear of the incisors, and the internal +growth of the pulp beneath, which is always pushing the tooth forward. +This dull continuous work might otherwise have a terrible result, which +you would never suspect. It is very disastrous for a young lady to lose +a front tooth, as it is called, for it sadly spoils a pretty face; but +for a _rodent_ such a loss is much worse; in fact, it is a death- +warrant. The corresponding tooth, having no longer anything to rub +against, ceases to wear out; and as it does not stop growing on this +account, it lengthens indefinitely, until at last it pushes out beyond +the mouth, and places itself like a bar between the two Remaining teeth +and the food of the animal, who, poor beast, being unable to eat, +ceases to live. + +The canines, whose duty it is to pierce the food, have, of course, no +use in a jaw that grinds, nor are they to be found there. Between the +incisors and the molars there is a large vacant space, which you will +easily detect if you examine a rabbit's head. + +Finally, animals which can fall back in time of need on a plank for +their dinner, require a very different-sized cooking apparatus to that +of the _Carnivora_. Thus the rat, the most perfect sample of the +rodent order, possesses a digestive tube of a prodigious length, through +which the scrapings of wood have plenty of time for travelling, while +the minute nutritive particles they contain are being thoroughly +disengaged; and as every part of the animal organization tends towards +keeping our insatiable rodents in the constant state of voracity +required by its inexorable pulps, nature has given it an enormous heart +whose size exceeds even that of its stomach. + +Perhaps you do not catch at once the connection which exists between +the size of the heart and of the appetite; yet it is very simple. Large +barrels are requisite for those who brew a great deal of beer, and +large hearts for those who make a great deal of blood. Now, it is the +blood, as you know, which carries heat; in other words, life, throughout +the body; when it pours in in torrents, the fire goes twice as fast, +and, consequently, the feeding must be kept up. A medical friend of +mine told me that he once had some rats sent to him--a boxful in +fact--for one of those scientific experiments which one would venture +to condemn more earnestly if their results were not sometimes +beneficial. Next morning there were only two or three animals to be +found, and these had eaten up the others. See the consequence of having +too much heart! + +ORDER 7. _Pachydermata (thick-skinned)_. + +In Greek _pachus_ means thick, and _derma_ skin. _Pachyderms_, +therefore, are thick-skinned animals. It is rather a vague denomination, +as you perceive, and does not tell us much about them; but it appears +that it was not very easy to find a better term. For my own part I +should be very much puzzled to find a name really suitable for such an +irregular company as this, in which all the huge beasts of the +earth--the elephant, the rhinoceros, the hippopotamus--are heaped one +upon the other, side by side with the horse, the ass, and the hog; +begging your pardon for an ugly word. + +All these creatures live on vegetables, with the exception of the hog, +to whom nothing comes amiss; or who, in other words, is _omnivorous_, +like the bear, and also another member of the class _Mammalia_, which I +do not name for fear of making you blush at your companionship. This +assures you that, in the order of the _Pachydermata_, the digestive +apparatus is very fully developed. The horse, for instance, has a very +voluminous stomach, which extends much farther back than the point at +which the oesophagus empties itself; and in which, on close examination, +a sort of contraction is observed which appears to divide it in half, +producing the false effect of there being two stomachs. But, after all, +we do not find, even in this case, any essential difference to remark +upon in the internal arrangements; it is always the teeth we must look +at if we want to have something to say. There, indeed, we have only to +choose; nature has indulged herself in all manner of fantastic freaks. + +To begin with the elephant, the grand master of the order, he presents +us with one of the most oddly-furnished jaws in existence. Every one +knows those two enormous tusks which protrude from his mouth, and which +furnish human industry with nearly the whole store of ivory it has +need of. Those two teeth are the largest, beyond comparison, of any +in the animal kingdom; yet they are two merely ornamental teeth, +perfectly useless in the operation of eating, and very ruinous into +the bargain to the proprietor. All those stores of the blood which +furnish the materials for ivory pass into these tusks, and, as often +happens to people who give way to a taste for luxuries, there is nothing +left wherewith to provide the animal with serviceable teeth. Those +tusks of the elephant are nothing but his upper incisors, the only +ones, observe, which curve in coming out of his jaw. In the lower jaw +he has no incisors at all; canine teeth are entirely wanting; and by +way of dental apparatus, this meagerly-furnished mouth possesses on +each side of either jaw one or two molars, enormous in size, but not +of ivory. They are composed of a number of enamelled upright layers +of tooth-substance (_dentine_), soldered together with a bony +cement; and these are our giant's only resource for chewing the grass, +young shoots, and leaves of trees, which are his natural food. +[Footnote: These teeth are nevertheless very efficient grindstones.] +As a consolation, he has the glory of knowing that he possesses the +very finest teeth in the world, the terror of all who approach him; +and I can compare him to nothing so well as to a vain woman, who is +contented to live on potatoes that she may wear fine clothes and excite +the envy of her neighbors. + +The hippopotamus also has incisors in the upper jaw, which curve as +they come out of the mouth; but these never attain anything like the +size of the elephant's tusks, neither do they hinder the development +of the other teeth, of which this animal has a very respectable +collection. The upper incisors bend downward; those in the lower jaw +stand out horizontally, and terminate in sharp points like +plough-shares; and indeed the hippopotamus uses them for tearing up +the ground in order to get at the roots which form its nutriment. These +are, besides, formidable weapons, with which when enraged the animal +can tear even boats in pieces; for, as you are aware, the hippopotamus +is almost amphibious, and browses on water-plants, and lives in the +great rivers of Africa, its native country. Its name alone would have +told you this had you understood Greek; [Footnote: _Ippos_, a horse, and +_potamos_, a river. The Greeks, who had seen the hippopotamus in the +Nile, in Egypt, named it the river-horse; as afterwards the Romans +called the elephant the ox of Lucania, because they first saw it in +Lucania during the war with Pyrrhus.] but I have no complaint to make +this time, for it was the Greeks themselves who gave it. You would find +it very awkward, would you not? if you had to breakfast at the bottom of +the Thames, and could not swallow a morsel without having your nose +filled with water? But the hippopotamus labors under no such +inconvenience. Its nostrils are provided with two little doors, which it +closes at will, and behind this screen the lungs keep quite quiet while +the animal goes backwards and forwards in the water. There is generally +a hippopotamus in every large menagerie. The next time you visit one +look at him. You will see him with a large stomach almost trailing on +the ground: and no wonder; he needs plenty of room in which to stow away +all the canes, reeds, and water-plants from the bottoms of rivers, which +are not very nutritious food. Accordingly the stomach of the river-horse +presents the appearance not only of two compartments, like that of the +true horse, but looks as if it were divided into three or four. + +To conclude my account of this animal, I must add that the ivory of +its teeth is even more beautiful than that of the elephant's tusks, +and that dentists carve it into very magnificent teeth for their +patients. This is not a matter to interest you much at present, but +we never know what may happen. I advise you, however, never to make +use of hippopotamus's teeth; they turn yellow very quickly, and, when +people are driven to buy teeth, the least they can try for, is to get +good-looking ones for their money. + +I should like to say something about the rhinoceros while we are on +the colossal tribes, but it is a very unsatisfactory subject. The +animal has no canines, sometimes no incisors even; sometimes it has +as many as thirty-six teeth, according to the species, as naturalists +aver; and this is all I have to say about this great lump of flesh, +so misshapen outside, yet so regularly formed within. He it is who +especially deserves the title _pachydermata_, his skin being so +hard and thick that bullets glance off its surface. But this has nothing +to do with our present subject, any more than the horn upon his nose, +whose turn for description may come if I ever give you the history of +the skin and all connected with it. + +The hog also has canines, and very strong ones; but it is in the wild +state, when it is called a boar, that these appear in their real form. +There we find them projecting out of the mouth with a curve, as is so +commonly seen among the _pachydermata_, forming those terrible, +sharp, and pointed tusks which have been so often fatal to the hunter. +The wild boar of the forest is supposed to be the original ancestor +of the domestic pig; and if, as is probable, this is really the case, +we have here a remarkable instance of the effect of man's treatment +upon the organisation of the animals he collects around him. The wild +boar lives only on fruits and roots, which, like the hippopotamus, he +tears up with his tusks, those safeguards of his, amid the many perils +of his life in the woods. In the service of man, on the contrary, he +becomes lazy, cowardly, and greedy; unlearns his energy and +combativeness, eats all that is offered to him in the trough, even +meat, when it happens to be thrown in; and, in order to do this +moreeasily, has recalled toward his mouth those formidable war-tusks of +his, so tremendous as weapons, so useless as teeth; has, in fact, +turned his sword into a fork. It is the case of a Tartar degenerated +into a Chinaman. [Footnote: China, about which we have heard a great +deal of late years, has been several times invaded by the warrior +hordes of Tartary. But at each time, unto the second and third +generations, the vanquishers have taken the effeminate manners, the +costume and the usages of the vanquished, and so many conquests have +only resulted in converting millions of Tartars into Chinese.] + +This suggests to me an idea relative to the horse, the last important +member of the _pachydermata_ which remains to be spoken of. It +also has its canines, but very small ones; they disappear, so to speak, +in a large vacancy between the incisors and the molars, where man +inserts the bit, by means of which the animal has been subdued. Small +as these are, however, these canines indicate that the horse might eat +flesh, canine teeth being the distinctive attribute of the carnivorous +mammals. I have read somewhere, but I do not remember where, that an +unusual development of strength could be produced in the horse by +feeding it on flesh; and the old Greek poets write of a king [Footnote: +Diomed, King of Thrace] in the barbarous ages who gave his horses, +men for food. If I knew some rich professor who was inclined to spend +money in the investigation of a curious fact, I would advise him to +set apart a sum for putting horses on a meat diet, from sire to son, +gradually increasing the quantity; and I would boldly warrant that in +the course of successive generations the canines would become so large +as to impede the entrance of the bit into the mouth, and, moreover, +would make it rather a ticklish office for the groom to place it there. +But let us set aside the teeth the horse might possibly have, in order +to examine those it has already. There are six incisors in each jaw; +these are long and rather projecting teeth, by examining which, the +age of the horse can be detected from certain marks which appear in +them from year to year. The molars are flat, square, furrowed with +bars of enamel, marking out more or less distinct crescents; perfectly +constructed, in short, for chewing hay and oats. Nevertheless, I should +never be surprised to see the enamel crescents become sharp-cutting +in our rich professor's stable; so skillful is the unseen Architect +who created animals, in altering the house when the tenant changes his +habits. + +ORDER 8. _Ruminantia (ruminants)._ + +I shall retain through life a pleasant recollection of the +_ruminants_. Through them I obtained the first prize for natural +history which was ever given in France to the pupils of the learned +university. It is thirty years ago since this happened, and I own, +without any false modesty, that even now the word _ruminant_ rings +very agreeably in my ear. It reminds me of one of the proudest moments +of my life, of the honor done to me by the illustrious Geoffroy St. +Hilaire, when he called me, a little college urchin, up to him, that +he might have a nearer view, as he said, of the baby-professor who had +spoken so well on ruminants. Yes, it is more than thirty years ago, for +alas! it was in 1831. There needed no less an event, as I have told +you before, than the revolution of 1830 in France to induce the big-wigs +of education to sacrifice two hours per week in one class to the study +of natural history. Yes, my dear child, it is only that short time ago +since natural history became one of the subjects of study in French +colleges; and the gray-haired men of the present day finished their +education, as it is called, without having learnt a single word of +what I am now taking the trouble to teach you, a mere child. You see +you have come into the world just at the right time, and will be able +to instruct others in your turn. But before giving lessons to other +people you must first finish learning your own. Forgive me this +involuntary reference to a happy time when I was not much more rational +than you are. And now, let us return to our ruminants--those dear, +good beasts, the nourishing fathers of the human race. + + + +LETTER XXXII. + +MAMMALIA--_continued_. + +ORDER 8. _Ruminants--continued_. + +Every created thing has an appointed part to perform; but there are +some mysterious parts of which we cannot understand the drift. That +of the ruminants, however, is so clearly marked out, that we detect +it at a glance. + +To qualify myself for supplying your young mind with the food I am +going to offer it to-day, I have been obliged, my dear child, to browse +in a good many books of which you could have understood but little +yourself; and I have been forced to ruminate a long time upon what I +have read, and to digest it slowly in my head, which I may say, without +vanity, is of larger capacity than yours; no great wonder at my age. +Now, if I have succeeded in my undertaking, you will benefit by all +the work which has been going on in my mind for the purpose of feeding +yours without over-fatigue to it; and I shall almost have the right +to say that its nourishment has been derived from me. My lamp could +tell you what it has sometimes cost me to supply a single page which +might instruct, without repelling you. + +Now, this is precisely what the _ruminant_ does. The part he has +to perform is to collect in the meadows a sort of food, which would +disgust less well-organized stomachs than his own, to work it well up +within him, and to give it back in a more palatable and less +indigestible form. The little flesh-eaters (_carnivora_) come +afterwards to the feast, and the feast is himself! + +The whole history, then, of the ruminant is to be read in his stomach. +His real office is to digest, and in fact he devotes the best hours +of his days to the perfecting of that beneficent labor, on which the +life of so many weak stomachs depends. Have you ever amused yourself +by watching a large ox lying down in a meadow? Long after he has +finished grazing, his jaw continues to work, turning round and round +like the grindstone of a painter when he is rubbing down his colors. +Look, and you will see that he will remain there for hours together, +motionless and contemplative, absorbed in this incomprehensible +mastication, rolling about in his throat from time to time some +invisible food. Do not laugh at him, however. As you sec him there he +is performing his part in life, he is _ruminating_. + +To ruminate is to chew over again what has been already swallowed; +and, however droll this may seem to you, it is the business which all +ruminants are born to. You remember the monkey's pouch, which serves +him as a larder, whence he takes out his provisions as he wants to +eat. The ruminant has an immense pouch of the same kind, into which, +while he is grazing, he hastily conveys large masses of half-bitten +grass. You probably think he is eating when he has his head down in +the grass; but you are mistaken. This is only a preparatory work; he +is hastily heaping up in his larder the food he intends to eat +by-and-by; only his larder, instead of being, like the monkey's, in +his cheeks, where, indeed, there would not have been half room enough +for those great bundles he tucks in, is in the middle of his body, +close to the extremity of the oesophagus, whose lower wall, being slit +at that part, becomes an imperfectly secure tube, ready to burst open +under pressure, and allow the food to escape between the edges of the +slit; these, otherwise, remaining naturally closed. As soon as the +large bundles of grass come to this part, they press against the walls +of the tube, which they by this means separate, and fall into the +provision-pouch, which bears the name of paunch, or grass-pocket, in +fact. As soon as the paunch is well filled, and the animal sure of his +dinner, he lies down in some quiet corner, where he proceeds gravely +with the important act, which is the real object of his existence. A +little below the entrance to the paunch, and communicating both with +it and the canal of the oesophagus, is a second receptacle, which old +French naturalists, not being much acquainted with Greek, named the +_cap_, on account of its fancied resemblance to the caps worn on +the head, and which we call 'king's hood' or 'honey-comb bag.' This +second stomach now contracts (at least so it is supposed), and thus +retains, as if with a closed fist, a portion of the grass accumulated +in the paunch: of this it forms a pellet, which it sends back into the +oesophagus, and the oesophagus, by continued contractions from below +upwards, returns it to the mouth, where at last the grassy lump is +chewed in good earnest, and to some purpose. There is no necessity for +hurry; the ruminant has no other business on the face of the earth but +this, and thus hour after hour passes away, the food pellets rising +one after another to the onslaught of the teeth. Nor do they go back +again until they have been reduced by long mastication into an almost +liquid paste, which glides through the oesophagus without forcing open +the slit, and falls straight into a third pouch, called by old Frenchmen +the _leaf_, on account of certain large folds, some what like the leaves +of a book, which line the interior; and known to us as the _manyplies_. +From this stomach, No. 3, this grass-pap passes into a fourth and last +bag, which is the real stomach, and where the final work of digestion is +accomplished. This fourth pouch also has a pretty little name of the +old-fashioned sort, like the three others; it is called the _reed_ or +_rennet-bag_, from the property it possesses, in the calf, of turning +milk into curds: and of his four stomachs this is the only one which the +ruminant makes use of at first. As long as the young animal is nursed by +its mother, the other compartments remain inactive and small in size; +they neither grow nor exercise their functions until it begins to eat +grass. Indeed, they would probably entirely disappear, if any one would +go to the expense of keeping the animal on milk all its life. If it +ceased to have anything to ruminate, nature would certainly lose no time +in relieving it of its useless workshop of rumination. + +As it is right to give every one his due, I will mention that we owe +our accurate knowledge of this simple and ingenious mechanism of +_rumination_ to the labors of Flourens, a scientific Frenchman, +who is still alive, and who has made a great many interesting inquiries +into the subject we are now considering, _i. e._, the life of +animals. He is a very clever man into the bargain--so perfect a master +of his own language, that the French Academy has felt itself justified +in opening its doors to him--an unheard-of honor for a member of the +Academy of Sciences. And yet, in spite of all this, I heartily +congratulate you that the discovery of the _paunch_, the _cap_, the +_leaf_, and the _rennet-bag_, was not delayed for his arrival. He is +just the man who might have been tempted, in his capacity of profound +scholar, to have hunted up for them in the _Jardin des racines grecques_ +[Footnote: Your brother can tell you about the _Jardin des racines +grecques_. It is a charming little book, of which every generation of +collegians has learnt, by heart, the commencement; but I have never +known one, even among the most intrepid, who had ever been to the end of +it.], four magnificent names, which would only have bewildered you. + +Beyond the rennet-bag there is no change of conformation to note, +except that the intestinal tube is naturally much longer than ours, +on account of the difference of food: as a general rule, it is ten or +twelve times the length of the body. The sheep, who is able to pick +up a living in the poorest pastures, is indebted for this inestimable +power, which makes him the special blessing of dry and barren countries, +to a still further peculiarity of organization; with him the intestinal +tube is twenty-eight times the length of the body. + +We have seen among the _Carnivora_, whose jaws have so much work +to do, that the condyles of the jawbone are sunk deeply into the fossa +of the temporal bone. The ruminant, whose peaceful mouth is formed for +contending only with grass, is organized quite differently. + +Here the condyle is flattened, and the fossa of the temporal bone very +shallow, presenting to the condyle an almost flat surface, so that the +jawbone is enabled to revolve with ease for the better mastication of +the pellets of grass. This conformation is also to be seen in the +_pachydermata_ who feed upon vegetables. In the horse, especially, +whose food is almost the same as that of the ox, the _articulation_ +(as this joining of the condyle to the temporal bone is called) of the +jaw, is also nearly identical; and it is the same with the teeth, with +very trifling variations, those of all ruminants are constructed on +the same plan as in the horse. The canines only require a separate +notice. + +But first I must tell you that, by some special privilege, the reason +for which I do not undertake to explain, the order of ruminants is the +only one containing animals with horns on their foreheads. Stags, +goats, reindeer, chamois, gazelles, roebucks, oxen, buffaloes, all the +beasts with horned foreheads, belong to the ruminants. Indeed, this +fact would form a very convenient mark of distinction between them and +other animals, were there not exceptions to it. Some ruminants have +no horns; and then, as if in compensation for the deficiency, we find +them provided with canines in the upper jaw, in addition to those +below. + +The ruminant which has the most beautiful canines is the musk-deer, +a pretty little animal inhabiting the highlands of Central Asia, like +the chamois of the Alps. But now that you know who he is, you will +probably often be tempted to wish he had never existed; for it is from +a small pouch below his belly that people obtain that odious musk of +which Oriental beauties are so fond, and which even certain +strong-nerved ladies of our own country are guilty of using in public, +to the great detriment of general health. But enough of this; our +business is with the canines of the musk-deer. They project with a +descending curve from the upper jaw, and would give the animal the +very false appearance of a small wild boar, but for the great delicacy +of its legs, which are more slender than even those of our roebuck, +to whom, with the exception of the horns, it bears a close resemblance, +as its name implies. + +After the musk-deer comes the large family of camels and llamas, which +represent--the former in Asia and Africa, the latter in America--the +irregular groups of ruminants which have canines instead of horns, and +which seem to be placed as intermediates between true ruminants and +the pachydermata. They form the connecting link between the horse and +the ox, and men prefer employing them as beasts of burden to using +them as butcher's meat; though one could eat them in their own country +with less disgust than Europeans feel in making a meal of horseflesh; +so that they might be a very acceptable resource in many cases. The +real fact is, that ruminants with horns and without upper canines have +more delicate flesh than the others, and seem more especially destined +to be eaten. Yet if one had only to look at the stomach, which is, +after all, the distinctive characteristic of the order, camels and +llamas would stand in the first rank as ruminants. Besides the usual +character of four stomachs, their paunch and honeycomb-bag are furnished +with large cells which act as reservoirs, and fill with water whenever +the animal has the chance of drinking freely, and from whence in time +of drought he draws it up into his mouth and swallows it. This is what +makes the camel so valuable to the wandering tribes in the great deserts +of Africa and Asia. He is the only animal who can pass several days +under the burning sun of Sahara without drinking--or rather without +appearing to do so--for he carries his provision of water concealed +from all eyes in the recesses of his body. I dare say you have often +heard stories of Arabs dying of thirst who have opened the stomachs +of their camels in search of a last draught of water. It must be a +terrible thirst to drive a man to such an extremity; for, as you may +imagine, one could not expect the water there to be either fresh or +clear, to say nothing of the great risk there would generally be of +finding the reservoir empty. Such an extreme is never resorted to till +water has failed for a long time, and all the goatskin bottles have +been emptied; and in such a ease it is but too likely that the camel +has followed his master's example, and emptied his water-skins for his +own use. But this is only half the internal fittings of the "ship of +the desert," as the Arabs call him. In the desert it is often as +difficult to find food as water; and nature has equally provided for +this. The hump you see rising upon the camel's back in your +picture-books is his safeguard against starvation. It is a huge mass +of fat. I need say no more. You will remember Mr. Liebeg's pig, which +lived 160 days upon its own bacon. Without going quite such lengths +as that, the camel can keep up his fire for a long time upon the fuel +which the blood obtains from this blessed hump. Since we are talking +of this animal, and he takes a remarkable place in a history of +nutrition, I ought to tell you that camels are classed into two families +by their hump: there is the camel, properly so called, which has two +humps, and the dromedary, which has but one. This latter did not require +such a supply of provisions as the other, for he is very much swifter +of foot, and consequently his journeys are more speedily performed. + +I have nothing particular to say to you about the other ruminants, in +the matter of their organs of nutrition; but I will not quit the subject +without reminding you of one thing which concerns nutrition, not theirs, +however, but ours. It was by the taming of the domestic ruminants--that +unfailing dinner-material which now follows everywhere at the heels +of his master--that human civilisation began. Before that event, man, +driven to depend for his living upon the hazards of the chase, spent +his whole time in seeking for food, and had none to spare for the +pursuit of any other branch of industry. + +Far as we may ascend in the history of ages we shall find shepherd +races. Beyond them there is no history at all, nor could there be. The +first leisure hours of man, and, consequently, his first efforts in +art and literature, date from the period when the ruminant animals, +those special fabricators of nutritive aliments, were gathered around +mankind, and worked out their destiny under the shadow of his tent, +by his direction, and for his benefit. But all this is so distant from +us now, that it is scarcely worth the trouble of thinking about. The +human race is somewhat like those old people who have lost all +recollection of their childhood; and young people are not required to +know what their elders have forgotten. It is well, however, that they +should not be quite ignorant on the subject. When you hear that the +Society for the Prevention of Cruelty to Animals has taken up the cause +of some barbarously-used ox or sheep, do not turn it into ridicule. +Those humble species have supported ours from the first; and you should +recollect, now and then, that human society made its first step forward +when it began to keep flocks and herds. + + + +LETTER XXXIII. + +MAMMALIA--_continued_. + +We come now to animals less familiar to you, and none of which inhabit +Europe. We shall therefore pass more quickly over them. + +ORDER 9. _Marsupialia (pouched)_. + +_Marsupium_ is Latin for purse, pouch, or pocket. The marsupials +are distinguished from other animals by a pouch which the mother has +under her belly, and in which the little ones take refuge at the +slightest alarm. You would be very much interested with their whole +story; but it has nothing to do with our present subject, which we +should soon lose sight of if we once began to wander away. This order, +so easily distinguished otherwise by that singular pouch, unfortunately +for us, offers nothing new for observation. It includes several species, +differing entirely from one another on the subject of nutrition, and +closely resembling some already described. Some are both carnivorous +and insectivorous, and are therefore armed with powerful canines, and +with molars like those of the hedgehog. Others are herbivorous, like +hares, and have almost the jaws of a rodent. Among the former we have +the opossum, celebrated by Florian in one of his prettiest fables. The +opossum inhabits South America. Charming little marsupials are to be +found in the Molucca Isles, whence come the nutmeg and the clove; these +are very like our squirrels, and live as they do, in trees, hunting +after fruit and insects. But the greatest number of marsupials belong +to Australia, the real native land of the order. They form by far the +larger portion of the mammalia with which that country is enriched; +the most celebrated amongst them being the kangaroo; an animal which +is now becoming common in European menageries, and which, excepting +in the matter of its pouch, is nothing but a magnified rabbit, as tall +as a man, and with a tail almost as long as itself. As a rabbit, you +know what its eating apparatus must be; and some day, no doubt, the +French Acclimatisation Society will enable us to judge of its flavor. +It is a kind of meat very likely to be seen on our dinner-tables +by-and-by; and, as you have plenty of time before you, probably you +may eat of it before you die. + +ORDER 10. _Edentata (toothless)_. + +These come more directly within our limits. They are classed according +to their teeth; yet if their name were to be trusted, they ought to +have no teeth at all. Whereas, alas! almost all of them have some, and +I am heartily ashamed of their scientific designation; but how can we +help it? The only really _Edentata, i. e_. toothless animals, amongst +them are the ant-eaters, who, considering the nature of their food, are +not much in want of teeth. They feed among the ant-hills, whence they +get their name; and as they are a tolerable size (from two to three feet +in length), it would really have been quite a hardship upon them to have +been forced to crunch the ants one by one at every meal. To get on +rapidly they catch them with their tongue; but what a tongue! Imagine a +kind of long earthworm, lodged in a snout which is elongated like a +bird's beak, and has a very small opening at the extremity. The ant +eater inserts this long, string-like tongue into the crowded ranks of +its victims, and, as its surface is glutinous, they stick to it by +hundreds at a time, and are swallowed at one gulp without a chance of +escape. This tongue, perfectly unique in its character, stretches out in +its murderous exertions to nearly three times the length of the animal's +long head. What a distance there seems between such a tongue as this and +your own little doorkeeper! But no wonder: we have now reached the +confines of the kingdom of _Mammalia,_ and the face of nature is +beginning to change. + +The Armadillo, for instance, which comes next to the ant-eater, looks +far more like the tortoise or lizard than its noble mammalian brethren. +It is covered with scales; and, to look at it, you would say it was +a reptile, in spite of its higher internal organization. As for teeth, +it has certainly enough of them to give the lie to its name of +_edentata;_ but they are not very serviceable ones. They are called +molars, however, because they are situated in that part of the mouth +which is always assigned to molars; but they are miserable grindstones, +very unlike any of which we have hitherto treated. They are all of them +flattened cylinders, with no enamel bars to strengthen them; are small +and poor, and are placed at rather wide intervals from one another. The +poor armadillo munches with these, as best he can, slugs, tender roots, +and other prey of the same sort, with which he is obliged to content +himself, and which do not require very formidable tools. + +The most questionable member of this class is the Unau, or Two-toed +Sloth. It only wants incisors to be as toothless as ourselves! and the +first time I saw it I took it for a little bear. It is true I was then +younger than you are now; for the bear, who is one of our nearest +neighbors, ought not to have been confounded with the unhappy being +before us, one of the drudges of the animal creation; though M. de +Blainville (who had not my excuse) proposed placing it still nearer +to us, namely, amongst the _Quadrumana_. Observe that instead of hands +it has at the end of its fore-limbs only two enormously curved claws, +which have somewhat the appearance of a gigantic fork accidentally +twisted. Accordingly its illustrious sponsor offered it to the world as +an _irregular quadrumane_. I believe so, indeed! This _quadrumane_ +without hands--this _edentate_ whose molars are preceded by magnificent +canines--this enigma of nature, created for the confusion and despair of +all classification--does, I must in all humility confess, completely +upset the rule I laid down so stringently when speaking of the horse, as +to the objects for which canine teeth were framed. The canine teeth of +the sloth are more developed than its molars, and yet I cannot tell you +what they are there for at all. It feeds upon the leaves of trees; and +old travellers in South America, where it inhabits, have told us that, +when it has once hoisted itself up a tree, it will strip it to its last +leaf, and afterwards drop to the ground to avoid the trouble of crawling +down. This was what first obtained for it the villanous name of sloth, a +title which is certainly justified by its gait when on the ground; for +it is so ill-made that it cannot stand upright on its legs, but moves +clumsily forward by dragging itself on its elbows. It seems, however, +that when once in a tree it is a different creature altogether, and +can scramble lightly from branch to branch. Moreover, if its claws +cannot reasonably be reckoned as hands, they are at all events excellent +hooks; and when it is springing about thus in the forest, suspended +to the branches by its long arms, one might be tempted, while watching +it from below, to decide in favor of M. de Blainville's opinion. I saw +it originally myself in a cage. + +As to the sloth's relationship to the armadillo, this rests upon a +detail which bears directly upon our subject. The molars in both animals +are cylindrical and smooth, this is a trifle, but what would you have? +The animal had to be classed somehow; since naturalists have not had +the wit to make detached companies, as they do in regiments of soldiers. +ORDER 11. _Amphibia (two-lived)_. + +We are going farther and farther away. Here are animals who are nearly +half fishes (_amphis_, _double_, and _bios_,_life_). The _Amphibia_ have +two lives: one in the water, which is their true life, and where they +are in their element; the other upon land, where they can only crawl; +for their paws, which are but half developed, are destined to perform +the office of fins, and the hinder ones are extended flatly behind them, +and act like a fish's tail. They are divided into two families, the seal +and the walrus. The first feed on fish, and have the same internal +organization as the _Carnivora_, as well as the same dental +conformation. Some species have even exactly thirty-two teeth, as we +have. The jaw of the walrus is the least regular, and the incisors are +generally wanting, especially in the full-grown animal; for it appears +they lose them very young, as you lost your milk teeth, only, unluckily +for the walrus, his never grow again. On the other hand, he has two +canines in his upper jaw, which, next to the elephant's tusks, are the +largest we have yet met with. They are sometimes as much as two feet +long, and incline downwards with a curve, like the two bars of a pick- +axe. They would play the walrus the same trick that the incisors of +rodents are apt to do when they have not work enough to wear them down; +that is, stop up the entrance of its mouth, were it not that the lower +jaw is contracted in front, in order to fit into the space between the +two canines, which thus form a sort of passage in which it manoeuvres +freely. As you may suppose, the walrus cannot insert prey of any great +size into this contracted passage; but that is no matter, as he lives +partly on seaweeds, and partly--indeed principally--on shell-fish; his +molars being specially adapted for breaking shells. They are short +massive cylinders--the upper ones fitting into the lower as a pestle +into a mortar. + +After the walrus comes a strange animal which has been ranked among +Cetaceans (we shall see why presently), but which it would be better +not to separate from the Amphibians, since an Amphibian order has been +made, for it crawls from time to time upon land: this is the Manatee, +or Sea-cow. It comes still nearer a fish than the others. Its forelimbs +are absolute fins, with mere vestiges of nails at their edges; it has +no hind ones, and its body, which is quite cylindrical, ends in a fin +tail in the shape of a shovel. The sea-cow feeds on plants and herbage, +and lives at the mouths of great rivers, going up them occasionally +to great distances, their banks serving it for pasture ground. In some +respects it is half brother to the hippopotamus and the great grass +eating _Pachydermata_, to whom it comes so near in internal +organization, and above all in the structure of its molars, that M. +de Blainville seriously proposed ranking it among the elephants, though +as an _irregular elephant_, as you may suppose. But then Cuvier +had even placed the seal among the _Carnivora_, by the side of +the cat, whose whiskers it possessed, and of the dog, whom it resembled +in the formation of its head. A naturalist's office is sometimes very +perplexing, I assure you; and as we are touching on this subject, I +cannot resist telling you that the sea-cow laid claim to, on so many +sides, had by right a free admission to the celebrated order of +_Primates_, although it looks exactly like a large barrel elongated +at the two ends. It suckles its young at the breast like man and the +monkey; and if Linnaeus flinched from this rather too absurd parentage, +old navigators were less scrupulous. Observing this creature in the +distance, sporting on the waves, the upper part of its body quite out +of the sea, the sailors, whose eye is not of the most refined, and who +have no objections generally to the marvellous, imagined they saw a +new species of human beings; and hence arose those stories of mermaids +and sirens which have been told from the days of Homer downwards, and +the traditions of which have not yet quite died out in seaport towns. +To have been passed from man to the whale, touching the elephant on +the road, is a long way to travel, especially when, after all, one is +only a huge barrel of amphibious fat; and you may judge from this that +it is not always an easy thing to classify animals. + +ORDER 12. _Cetacea (whale-kind)_. + +Cetaceans are whales; and if I had been consulted on the matter, I +should have joined this order and the last together, under whatever +name was thought most appropriate. The passage from the seal to the +whale through the walrus and the sea-cow is an easy and natural one, +the two latter being obviously the connecting links; and in spite of +certain diversities of food, they form in reality one family-party, +as do the marsupials. + +But it is too late in the day to talk of this, my dear child, and you +and I cannot pretend to alter what is taught in the schools. + +But you are astonished, are you not? to hear that the whale is not a +fish: and no wonder. It is with it, however, as with the armadillo; +it is a fish with a higher organisation inside. The interior of this +enormous mass is a faithful reproduction, as a whole, of that of the +shrew-mouse; and when we come to talk of fishes you will have some +faint idea of the prodigious distance which this places between the +whale and his countrymen of the ocean. + +As far as we are concerned, the chief difference is in their way of +breathing. The cetaceans breathe like ourselves, and are obliged to +come to the surface of the water to take air; while fishes have a +special apparatus, which I will explain to you presently, which enables +them to breathe in the water. This is a disadvantage to the cetacean +in his fish life; nevertheless, of all the mammals (as may easily be +imagined) he is the one who can remain longest under the water. With +us, for instance, the best divers one ever heard of, those who go to +the bottom of the sea after the pearl-oyster, can scarcely stay below +longer than two minutes; and even during that short time the veins of +the head become so overcharged with the blood, which cannot return to +the lungs owing to its forced inactivity, that when the diver comes +back to the surface it is by no means unusual to see him streaming +with blood from both nose and ears. The cetaceans remain under water +for half an hour at a time without seeming to suffer in the least; and +Breschet, a clever French naturalist, has given a very satisfactory +explanation of this wonderful faculty. In dissecting a cetacean, he +discovered all along the vertebral column an extensive network of large +veins, which are not found in other mammals, and which seemed designed +to serve as a refuge place for the blood during the time the animal +remains submerged. According to him, this network would act as a +reservoir, to which any overplus in the head or important organs would +flow through vessels communicating therewith, and which might swell +out as it pleased, without any risk to the inert bed of fat against +which it lies. From thence the blood rushes to the lungs, as soon as +the animal's return to the air enables them to play as usual. It must +be admitted, at the same time, that all this involves the necessity +of a much less active life than that of land mammals, that is to say, +a consumption of oxygen much smaller in proportion than theirs; for +were you to be furnished down your back with the finest network +reservoir in the world for venous blood, it would still not enable you +to remain half an hour without breathing. + +There is nothing remarkable in the digestive apparatus of the cetaceans +except about the mouth, which is, as you know, the essentially variable +point among animals. To begin with, the cetacean tongue has the most +original appearance possible. Indeed, it is not a tongue, but a large +carpet, spread over the floor of the animal's mouth, and bears not the +faintest trace of resemblance to that nimble delicate porter, who does +you such good service. Imagine a thick soft lump absolutely crammed +with fat, and completely immovable, because it is glued down along its +whole length to the bottom of the mouth, and you will have a good idea +of this strange tongue, which in the whale, the largest of the +cetaceans, attains to the length of twenty-five feet and the width of +twelve, and of itself alone furnishes the whale-fishers with from five +to six tons of oil. This is a great deal farther from us than even the +long string which serves as a tongue to the ant-eater; and you feel +at once that we are getting among strangers. + +With respect to teeth, I have now a melancholy piece of news to tell +you. We have done with them; we have seen the last of incisors, canines, +and molars, henceforth you will hear no more about those valuable +instruments. The teeth of the cetaceans, with whom this painful +falling-off begins, are no more teeth than his tongue is a tongue. +They are like so many nails set in a row in the jaw, and can only be +of use in retaining prey, not in grinding it; so that of the many +processes your bit of bread has to go through before it becomes a part +of yourself, there is one which is dispensed with here altogether, +namely, mastication. Cetaceans swallow their food without chewing it. + +Besides, they have not got a whole set even of these unmasticating +teeth. Dolphins and porpoises, those faithful companions of the sailor, +around whose vessel they come playing and tumbling in the seas of all +countries, are the only ones who have them in both jaws. And these are +the small fry of the order; they do not usually exceed six or ten feet +in length. + +The Cachalot, or Spermaceti Whale, an enormous cetacean, which rivals +the true whale in size, and whose head alone forms nearly the half of +its body, has teeth in the lower jaw only. This lower jaw, whose two +sides are joined together for half their length (a new deviation, very +unlike anything we have found before), is so little proportioned to +the gigantic head which contains it, that it is almost lost to sight, +and seems like a small plank slipped under a great square block. + +Such as it is, however, it possesses many very respectable teeth, of +which some weigh as much as two pounds; and with these the cachalot, +whose ferocity is tremendous, tears in pieces everything that comes +near it, sometimes even the boats of the fishermen who risk their lives +in the dangerous pursuit of capturing them. By a singular arrangement, +of which this is the only known instance, there is, opposite each of +the cachalot's teeth, a corresponding cavity in the upper jaw, into +which they fit closely, turning the monster's muzzle into the most +formidable pair of pincers to be found in the animal kingdom. Another +curiosity in the order is the tooth of the Narwhal, a modest cetacean, +who is not much more than twenty feet long! + +I speak of _the tooth_, because the creature has commonly but +one; a cylindrical-pointed tooth, spirally furrowed, whose length +varies from six to ten feet, and which comes straight out from the +extreme front of the upper jaw, like a soldier's pike. There are two +sockets at this extremity of the jaw, each furnished with a tooth-germ; +but as a general rule the germ on the left side is the only one which +develops, the other lying asleep in its socket, where it is choked up +and never appears. Behind this long pike, which, like the tusk of the +elephant, attracts to itself all the ivory in the body, lies a +completely unfurnished mouth; so that the owner of this magnificent +weapon, invaluable as a war-tool, but quite inapplicable to the purpose +of supporting life, is obliged to feed on small fishes and +_mollusks_. We have not yet spoken about these latter, but if you +have ever seen slugs and snails you will know what a _mollusk_ is. + +The same wretched food falls to the lot of the whale also, that giant +of the ocean, whose open mouth forms an aperture twenty feet in extent. +Geoffroy St. Hilaire, in his indefatigable endeavors to trace out +points of resemblance connecting together animals the most unlike in +outward appearance, discovered, along the lower jaw of a young whale, +certain traces of teeth, indicating a last effort on the part of nature +to carry out her usual plan in furnishing the jaws of mammals; but, +like the right-hand tooth of the narwhal, these vain attempts soon +disappear, overgrown and lost in the tissue of the bone, so that the +whale offers us a true type of an _edentate_, classable with the +ant-eater, if one dared, and some people have dared, which by this +time will not surprise you. A classifying professor is utterly +merciless, whether he gets hold of the poor beasts by the mouth or by +the paw: they may protest with all the rest of their body against the +peg on which they are hung; so much the worse for them! If one were +to listen to what they have all got to say, it would be impossible to +classify even one. + +To return to the whale. As a compensation for the teeth which she found +herself unable to give him, nature has manufactured on the two sides +of his upper jaw the most extraordinary apparatus without exception +to be found in the mammal mouth. You know what is called the +_whalebone_ used in stay-making, &c. The name is quite correct; +for those little flexible black strips, which support the figure so +nicely, began life in wandering over the polar or Australasian seas, +fastened to the palate of some monstrous whale. + +On the two sides of the upper jaw the membrane which covers the palate +sends out rows of broad, thin, horny plates, which are from eight to +ten feet long (they have sometimes been seen twenty-five feet) in the +centre of each side, but which decrease gradually towards the +extremities. These are plates of whalebone (sometimes called whale's +whiskers), and the industry of man has turned them to a thousand +different uses; and you will open your eyes in astonishment when I +tell you that 800 or 900 of them have been sometimes counted on each +side of one mouth. Think of the number of stays that could be furnished +from the whalebone plates of one whale! It is true, they were not +exactly designed for this purpose originally. At the tips and on the +edges of these plates, the elastic fibres of which they are composed +unravel and peel off, and hang down from the lip like tufts of +horsehair. The Arctic seas, which the whale inhabits, are, like other +seas, full of innumerable troops of various little sea-animals, and +it is these which are destined to the honor of nourishing this gigantic +mass of flesh. When the colossus wishes to take a meal, he stretches +his mouth to its utmost width, and the salt water rushing in as into +a gulf, carries with it the imprudent little fry, who disappear then +and there for ever, being retained by the fringe-like sieve of the +whalebone. But as, in this way of eating, the stomach of the whale, +however large, would be terribly overgorged with water, he is furnished +with another apparatus for preventing the inconvenience. All the +superfluous water is rejected by the _pharynx_, and springs up +in spouts of fifteen or twenty feet high, through the nostrils, +_i.e._ the nasal openings, sometimes called "vents," sometimes +"blow-holes," which are pierced exactly at the top of the head. This +is a peculiarity common to all cetaceans, who have thence received the +name of "blowers," alluding to the powerful blast which is necessary +to send those majestic columns of water into the air; but it takes a +much milder form with the lesser cetaceans, such as dolphins and +porpoises. There is but a slight jet with them: the water escapes +comparatively quite quietly from the nostril-vents, trickling away +down the animal's sides. + +I hope you consider that I have told you something new this time, my +dear child, and that our machine is beginning to change its appearance +very materially. I told you before that we had reached the outskirts +of the mammal kingdom. When we got to the armadillo we were within a +stone's throw of the reptiles, and here, one step more would take us +to the fishes. But we must first consider the birds, who are a very +superior set of animals to either of the latter; and we have accordingly +an order of mammals (Monotremes) which, as you will now find, opens +the road on that side also. + +There are but two sorts, and both of them are natives of Australia, +which is, as you may have heard, the land of the wonderful in natural +history, and their existence was unknown to the learned men of Europe +till within the last sixty years. The most extraordinary of the two +is the _Ornithorhynchus_, or, to translate the hard Greek word +into English, the _Duck-bill_. Its mouth is a true duck's bill, +a downright horny beak, and its short paws sprawling sideways with a +membrane joining the toes together below, and coming a good deal beyond +them in front, seem intermediate between the flippers of the seal and +the webbed feet of a water-bird. The first naturalist who had anything +to do with the ornithorhynchus, Blumenbach the German, who gave it its +pretty name, did not think it was able to suckle its young, so much +did it differ from mammals in some respects, though looking so like +them on the whole. And presently a report arose in the learned world +that the new animal which had been classed at all risks among mammals +(it having the close fur and almost the body of the otter), a report +arose, I say, that this ornithorhynchus of Blumenbach laid eggs like +a real duck. The uproar in the Academies was tremendous. As early as +1829, indeed, a learned Englishman, Sir Everard Home had sent over to +France an authenticated drawing, as he said, of an ornithorhynchian +egg, to the delight of the hunters after analogies among animal races; +while Cuvier looked sadly askance at the intruder, whose arrival threw +his animal outlines into confusion, there being no place in them for +such a beast. Happily for the poor animal, he has ended by almost +settling the matter for himself. The ornithorhynchian egg has never +turned up. But in the animal's nest have been found baby +ornithorhynchuses, newly born, under two inches long (the full-grown +animal being more than a foot and a half), and not a trace of eggshells +near. Further investigations showed that the mother ornithorhynchus +nursed her young with milk, for curdled milk was found in their +stomachs; so the Australian phenomenon has been restored triumphantly +to the Mammalian order, whence Geoffroy St. Hilaire had excluded both +it and its companion, the _echidna_, a sort of hedgehog, provided +like the ornithorhynchus with a bird-like bill, only more of the +canary-bird sort; and like it, also, approximating to the bird tribe +by other details which do not belong to our subject. And so the matter +stands at present; and all we venture to say is that classification +had a very lucky escape. + +And now, my dear child, that I have made you acquainted in detail with +your nearest neighbors, the last of whom, nevertheless, are strangely +unlike you outside, however they may resemble you within, I shall take +the liberty of going more quickly over the ground, and shall point out +in the mass only the more important changes which lead from one class +of animals to another. I should be found fault with if I tried to make +you too learned, and you yourself might be tempted to tell me, to my +sorrow, that you had heard about enough. + + + +LETTER XXXIV. + +AVES. (_Birds._) + +Tell me, my dear child, when you have seen birds taking their flight +into the air, and going boldly to their object, without a thought of +all the barriers, ditches, rivers, and mountains, which hinder man at +every step in his travels, did it never strike you to wish for their +wings, and imagine how you would fly off if you had them? If you ever +dreamt this dream, do not apologise for it; it is one as old as the +world. 'Oh that I had wings like a dove!' cried the Prophet, nearly +3,000 years ago; and the dialogue of the swallow and the prisoner, so +often sung by poets, has been repeated in prose behind all the +prison-bars on the globe since prisons were first invented. + +Now you will not think it kind on my part, but I must undeceive you +about this fancy, as you will be undeceived some day about many others. +The wings of a dove or swallow would be of no use to you if you had +them, any more than the formidable swords of the middle ages would be +to our modern gentlemen, were any one to put such into their hands. +We are not adapted for them, nor they for us. + +You saw, some time ago, what an amount of muscular exertion was required +for running--what a violent flow of blood, what hurried play of the +lungs. Now in flying it is still worse; for the earth, at any rate, +holds us up quite naturally, whereas the air will not hold up the bird +unless it is beaten vigorously and unremittingly by an untiring wing. +If we men, constructed as we are, had to do such work, we should be +out of breath at once; the heart would cry out immediately for quarter, +and the diaphragm turn red with anger. And only just imagine in what +a critical position a poor wretch launched into the air on the wings +of a swallow would find himself when, at the end of five minutes, his +servants should refuse point-blank to go on working at a height of 500 +feet above the ground! + +But a bird has not these internal rebellions to fear. In the first +place, it has no diaphragm; so here is another friend to whom we must +say good-bye. We shall not meet with him again anywhere. The journey +we are taking together, my dear, is somewhat like the journey of life. +One sets off, surrounded by friends and acquaintances, but whoever +travels on to the end is apt to find himself alone at last; this is +what is happening to the digestive tube, which we shall see losing all +its accessories, one by one, as we gradually advance in our study. +Even now here is one essential fundamental difference in the internal +machinery. The body has only one compartment instead of two; and the +lungs, masters of the whole space, extend freely to its utmost depths. +When a fowl is cut up at table, look along the body, and you will find +lodged in the cavity of the ribs, a long, blackish, and spongy mass: +this is the lungs. There is not, therefore, the same danger of a bird's +getting out of breath as with us; that delicate board which is found +in our bellows is wanting in his. His is set in action solely by the +to-and-fro movement of the ribs, which is produced by muscular +exertions, which are greatly increased during the action of the wings. +From which it follows, that the rapidity of flight itself regulates +the arrival of air, and consequently the expenditure of strength, or, +if you like better, the activity of the fire, since the energy of the +muscles depends, as we have seen, upon the quantity of oxygen that +feeds the internal stove. + +This is not all. These elongated lungs are still not sufficient to +furnish the blood with all the oxygen demanded by this excessive labor +of flight. They are pierced with holes, through which issue pipes which +carry the air all over the body. You know what is said of +spendthrifts?-that they burn the candle at both ends. It is so with +the blood of birds. That fillip which in our case it receives in the +lungs, and which sends it back full of vigor into the arteries, is +repeated in the bird at the other end of the arteries as well. The +capillaries, those delicate vessels at the end of the arteries, plunge +from all sides into little reservoirs of air-lungs, therefore-where +the blood renews its provision of oxygen, and relights its +half-extinguished fire, so that it sends the combustion afresh into +the muscles on its return back to the heart, and sets them going a +second time. + +The natural consequence of this prodigality of combustion is, that +there must be, in proportion, much more oxygen in birds than in us; +and that of all animals a bird is the one most quickly poisoned by his +own carbonic acid when the air is not renewed around him. Therefore, +let me beg you never to think of putting a poor little bird under a +wine-glass, as a child of my acquaintance once did, that she might +examine her little friend more closely. In the twinkling of an eye he +would consume all the oxygen inside his prison, and you would soon see +him fall upon his side and die. + +On the other hand, the temperature of these flying machines, which +consume so much oxygen, is very much higher than ours. It rises to +41 deg., 42 deg. (centigrade), and sometimes to 44 deg., 7 deg. higher than with us. +If ever you have taken hold of a little bird, you will have remarked +how warm it makes your hand: this is quite natural, since there is +always a double fire going on within him, to meet the extraordinary +expenditure of strength that is required of him whenever he takes wing. +Besides, do but look at the poor little creature when you have +imprisoned it in a cage! How it goes up! How it comes down! How it +hops from one perch to another, with a quick sudden movement, like +that of a spring when it unbends. There is no apparent cause for this +state of continual agitation; and yet there is a cause, and only too +serious a one. Its fire is not slackened because you have put it into +a cage, and its muscles, lashed furiously on by the double-oxygenized +blood, drive it hap-hazard into a thousand movements, in which it +expends, as best it can, a superabundance of power, which no longer +finds natural employment. Little children, who are the real +singing-birds of our homes, and whose blood also drives much more +energetically along than ours--little children I say--often fare no +better than caged birds in those larger cages we call schools; and +schoolmasters and governesses would scold rather less if they thought +rather more about this. It is right, I do not deny it, that the +rebellious young rogues should be taught in good time not to abandon +themselves, like wild birds, to the mere animal impulses of the blood: +but, in dealing with them, one must also make allowances, as they say, +for the fire within, and know how to open the cage now and then. It +is not for you, however, that I say this, young lady: you are no longer +a little child; but it may happen that you may have some to take care +of some day. Believe me, then, you must not expect too much wisdom +from them, and you must allow them to change their perch every now and +then. It is a law of our Almighty Father that little children, and +little birds, should not stay too long in one place. + +The mechanism of the circulation is here the same as with us, and does +not offer any important peculiarity. Only the left ventricle of the +heart has walls of extreme thickness, which enable it to launch the +blood into the members with greater vigor and rapidity; and the blood +itself, although it is composed of precisely the same materials as +that of the mammals, differs from it nevertheless as regards the +globules. In the first place, they are more numerous; secondly, they +are larger; and finally, instead of being round like a plate, they are +drawn out ovally, and are almost shaped like those long dishes on which +fish is usually served. I shall not attempt to give you the reason of +their size and form. This is hidden from us in the same mystery which +envelopes all the microscopic population of the blood; but is it not +a curious thing, this strange persistency of form in the globules ofall +animals of one class? In all birds they are oval; in all mammals +they are round. In all? Nay, I am wrong. As if the better to hide from +us the key to this riddle, nature has amused herself by making an +exception. Camels and llamas, I forgot to tell you, have also globules +in the form of long dishes, like the hen and the chaffinch. Find out +why, if you can. As to the reason of the number, it is a very simple +one. Since the energy of the blood resides in the globules, it follows +that the most energetic blood will contain the largest amount of +globules. Looking at you, for instance, little monkey, running and +jumping about the garden, I would lay a wager, without counting first, +that there are, in one drop of your blood, some millions more globules +than in one of mine. + +Let us now go on to the digestion, with which, properly, we ought to +have begun; but I preferred pointing out to you, first, the particular +character which is the chief mark of distinction in the organization +of the bird. + +'When hens grow teeth,' says a shrewd proverb, meaning of course, +_never_. Birds have no teeth, and in this respect there is no +variety among them. All, from the first to the last, have uniformly +the same tool to eat with--the bill, that is--which is, in all cases, +composed of the same elements, two jawbones elongated to a point, and +clothed in a horny armour, which makes their edges sharp and cutting. +At the same time were we to review the birds in detail, as we have +done the mammals, you would see that there are almost more modifications +to be observed in this one single instrument than in our thirty-two +teeth. All birds have a beak, but each has his own, organized expressly +with reference to the kind of food needed by its owner. The eagle's +beak, which mangles living prey, is pointed, bent, and hard as steel; +the bill of the duck, which laps up water from ponds and puddles, in +order to get worms and half-decomposed refuse out of it, is soft, and +flattened like a shovel. The woodpecker's, which has to pierce the +trunks of trees, is like a pickaxe; that of the humming-bird, which +has to suck up the juice of flowers from the bottom of their corollas, +is slender as a needle. The swallow feeds on flies, which it snaps up +on the wing, and has a soft bill, which opens like a little oven. The +stork picks up reptiles in the mud of the marshes; its beak is +straight-pointed, cutting as a knife, and resembles a long pair of +pincers. The sparrow feeds especially on hard grains, difficult to +break; accordingly its beak is stumpy, short, and thick, and is arched +on the upper side for still further solidity. But I should never end +if I began to enumerate all the thousand varieties in the bills of +birds. Each variety, too, corresponds with some peculiar sort of life, +and consequently with a general conformation (easily ascertained) of +the animal in which it appears. Give a naturalist the bill of a bird +--only its bill remember--and he will tell you half its history without +fear of being mistaken. + +On the other hand, we must not deceive ourselves as to the real value +of this complaisant bill. Let it transform itself as it pleases into +all manner of forms for the better fulfilment of its task, it makes, +at the best, but a very poor instrument for mastication; nay, to say +the truth, it breaks, cuts, and tears, but it never masticates at all. +Thus the bird's mouthful is far from undergoing as perfect a preparation +as ours does. It is no sooner taken in than it is swallowed, and the +salivary glands, which are still to be found under the tongue, seem +only to be there as a matter of form; what little saliva they produce +is thick and sticky, and has none of the qualities necessary for making +that liquid paste which our tongue sweeps up from every corner of the +mouth. Besides, it must be owned that a bird's tongue would be a very +awkward implement in such a task. Open a hen's bill and you will see +therein a very inferior sort of porter. It is merely a dry hard lance, +as it were, armed with prickles at the point, as ill-qualified for +tasting as for sweeping. So the hen does not waste her time in finding +out the flavor of what is thrown to her. She picks up and swallows +over and over again, without appearing to experience any other pleasure +than that of satisfying her appetite. Birds of prey, it is true, have +rather more convenient tongues, capable, moreover, of tasting up to +a certain point; and the parrot, who is a complete epicure, and chews +his food philosophically, has a charming-little black one, thick, +fleshy, and susceptible--a true porter, in fact-who enables Polly +thoroughly to enjoy her breakfast. But certain birds who live on insects +surpass even the hen in the dryness and hardness of their tongues. +That of the woodpecker, especially, is a model of the kind, and deserves +a few words more than the others. Picture to yourselves a long pin, +terminated by an iron point with barbs like those of fish-hooks. An +ingenious mechanism enables the bird to dart it out with the rapidity +of lightning, far beyond his bill, upon the insects to which he gives +chase. The point pierces them, and the hooks retain them, without any +need of assistance from the bill. I have just told you that this bill +pierces the bark of trees; but it only plays the part of gamekeepers +on grand sporting occasions, who beat the bushes to make the game rise. +The woodpecker's bill routs up the insects by destroying their shelter; +but the real sportsman is the tongue. Good-bye to any notion of a cosy +little chat in such a porter's lodge as that! What could a harpoon +have to say for itself? + +Do not, however, let this miserable entrance-hall alarm you, at the +same time, for the fate of the mouthful thus presented half-dressed +to the oesophagus. You will find it only so much the better treated +within. In the first place, the oesophagus, when half-way down to the +stomach, swells out suddenly and forms a pocket, which is generally +particularly well developed in birds who feed on grain; this is called +the _crop_ in English, in French _jabot_; whence comes the application +of that word to those full shirt-frills which have sometimes been the +fashion. It is the pigeon's _crop_ that gives him the rounded chest over +which he bridles so prettily. The crop is a receptacle where the food +makes a halt: it is something between the pouch of the monkey and the +paunch of the ox; a preparatory stomach, which does not, it is true, +send back the grain to the bill, for the bill could do it no good, but +in which that grain lies until there is room for it further on. + +Prom thence it resumes its journey; but, before reaching the true +stomach, it passes through a second enlargement of the oesophagus, +whose walls are pitted with numberless little cavities, from which +pour over it the juices destined to supply the place of the saliva +that was wanting above. + +It reaches its destination at last, but still hard, and generally +whole. No matter, however. The stomach which receives it, and which +is called the gizzard, is quite a different sort of thing from a useless +membrane, thin and delicate like ours. It is a thick muscle of enormous +power, lined inside with a kind of horny skin, so tough that nothing +can break through it. You may form some idea of the prodigious strength +of this organ, when I tell you that turkey-fowls have been made to +swallow hollow balls of glass, so thick as not to break when dropped +to the ground, and that at the end of a few days they have been found +reduced almost to powder in the uninjured stomach. No fear of +indigestion with such an apparatus as that. Though the grain may not +have been masticated in the bill, what does it signify? There is a +power here, as you see, quite equal to carrying the whole work through. +Thanks, indeed, to the invaluable horn which lines it, fowls which +have no teeth of their own can safely present themselves with as many +and as hard ones as they please. They swallow small pebbles, which rub +against the grain, during the contractions of the gizzard, and act +just as effectually as if they were fixed in the jawbone. Well, this +terrible gizzard performs its crushing work with such energy, that not +only the grain but the pebbles themselves are ground down there, and +end by being pounded into fine sand. When you rear fowls, do not forget, +if you keep them shut up, to put within their reach a store of small +pebbles, so that they may have teeth to run to in time of need. + +You remember the _pylorus_--the porter down below, who keeps the +door of egress from our stomach? He is as badly provided for here as +his fellow-workmen up above; worse in fact. It is a gaping hole, and +we cannot expect a very strict supervision from it. Birds who feed on +fruits profit by this fact to carry vegetables from one country to +another. With such an easy opening, seeds have a good many chances of +passing from the stomach unaltered; and then they drop from the clouds, +as is supposed, hap-hazard, and germinate afterwards, when circumstances +prove favorable, to grow up before the astonished eyes of the natives +into plants of which they have never even heard. The French +Acclimatization Society, which I spoke of lately, and which, though +so modern, has correspondents all over the globe, is at this moment +laboring to effect an exchange between all countries of the natural +productions of their soil. But here you see that nature had thought +of this before, and established her acclimatization society long ago. + +To complete the internal work of digestion, so feebly begun in the +bill, an extremely large liver pours torrents of bile into the duodenum, +and the manufacture of chyle proceeds with that wild rapidity which +characterizes all the living actions of birds. But speaking of this +liver, I think I ought to give you an account of a celebrated dish, +considered a great dainty by epicures, called _pates de foies +gras_--_fat liver patties_, to translate it into its meaning. +Very likely you will not care to eat them after hearing my story; but +that will be no great loss to you, for it is a very indigestible sort +of food, and not at all good for children. + +You remember my telling you about Englishmen going to India and coming +back with a liver-complaint, from having eaten and drunk more than the +climate allowed? By an imitation of this process, human +ingenuity--occasionally so cruel--has created the _pates de foies +gras_, the glory of Strasburg. I have been in the country, and can +tell you how it is managed. They shut a goose up in a square box, where +there is just room for his body. They open his bill at feeding-time, +and cram down with the finger as much food as can be got in. This is +throttling rather than feeding it. The poor beast, who can use no +resistance, since it cannot move, and who is kept in the dark to prevent +excitement; the poor beast is quite unable to burn all the mass of +combustibles with which the blood soon finds itself loaded. This carries +them to the liver to be turned into bile; but the liver is not equal +to the work, becomes loaded in its turn by unemployed materials, and +grows and grows, till at last, having filled up all the space around +it, it stops the play of the heart and lungs. When the animal is +nearly suffocated they kill it; and this is how we come to have _pates +de foies gras_ to eat! If they give us a fit of indigestion +afterwards, it is a vengeance we richly deserve. At Toulouse, where +the same trade is carried on on a large scale, they used formerly to +go even beyond this. They fastened the goose by the feet before the +fire-place, after having put out its eyes. The imitation of the +Englishman's proceeding was still more perfect here, for the fire acted +the part of the Indian sun to perfection. I do not know that part of +the country well enough to tell you whether they have quite given up +this piece of wicked ingenuity; all I can say is, I devoutly hope so. + +The intestine of birds is much shorter than that of mammals. Here +everything is done at full gallop, and the chyle has not to go far +before it is absorbed. I have before me a book, in which I am told +that the wagtails eaten in France can be fattened in twenty-four hours, +if you only know how to set about it, and these birds are not rare; +they belong to the same family as the red-breasts, the tomtits, and +the nightingale. Thrushes and wheatears (ortolans) require, for the +same purpose, four or five days in the same country, left to themselves +to roam about, when the vine keeps open table for them. + +This incredible quickness, not only in digesting, but, what is much +more, in transforming food into fresh living material +(_assimilating_ it, as it is called), has often a fatal result +for the bird. He is prohibited from fasting; his life is a fire of +straw, which must be replenished unceasingly, or it will die out in +the twinkling of an eye. Our own little birds--children--eat oftener +than grown-up people, and if by any accident they are kept waiting +awhile, they soon cry out with hunger. You know this, do you not? Well, +then, if any one should give you a bird to keep in a cage, remember +that you have undertaken a great responsibility, and that it will not +do to be careless with him. To neglect feeding him for one day is to +run the risk of finding him starved to death next morning. With this +warning, I will conclude my chapter on birds. I hope I have not spoken +in vain in behalf of those poor little captive songsters, whose fragile +lives are at the mercy of their young masters and mistresses. + + + +LETTER XXXV. + +REPTILIA. (_Reptiles_.) + +Passing from birds to reptiles is like falling from a torrent into +still water. Life drags on as sluggishly with the second as it dashes +furiously forward with the first. + +I spoke to you just now about a fire of straw: now we have a fire such +as Frenchwomen make in their _chaufferettes_, or foot-stoves. A +handful of charcoal-dust, and a few live embers between two layers of +ashes, is enough for the whole day; which is economical, is it not? +but then it throws out only just warmth enough to keep one's feet +comfortable. And so it is with reptiles. They live at very small +expense. If you feed them once a month they will not complain, for so +slow a fire does not often need replenishing with combustibles. It is +even said that the experiment has been carried so far with tortoises +that they have been made to fast for more than a year, and still the +charcoal fire kept up its languid pace. Of course, on the other hand, +there is not nearly so much oxygen consumed at once upon such a diet +as this. Where a bird would perish twenty times over in five minutes +for want of oxygen, a lizard can remain whole hours with impunity. +Moreover, the animal heat of reptiles is in proportion to their +expenditure of it. Graceful as is the snake (that living jewel so often +copied by bracelet-makers), you feel on touching it an instinctive +horror, caused by the thrill of cold it produces. All the animals we +have considered hitherto have warm blood, and bear within themselves +the source of their heat, which is pretty nearly always the same. But +reptiles are cold-blooded, and heat comes to them chiefly from without. + +If, at the end of a cold winter, we go to some favorable corner to +catch the first rays of spring sunshine, we feel ourselves almost +re-born, as it were, as if a new life had come into us with the +sunbeams. Look at the little lizard you see frisking on the white +stones of the wall; upon him decidedly the sun is darting actual life +from its rays. While the cold lasted he staid squatting in his +hiding-place--not asleep, but annihilated--congealed, so to speak, +like water caught by the frost; no longer digesting, and hardly +breathing, he had ceased to live in reality: and it is no imaginary +regeneration which the return of warmth brings to him. Like those +helpless people who have not the power to carve out their own destinies, +reptiles have within them only an insufficient source of animation; +their life is at the mercy of the sun, and is high or low, according +as that rises or sets in the heavens. At Martinique, where at noonday +it darts its devouring rays perpendicularly upon the cane-fields, and +every one flies into the shade to escape its scorching heat, the +rattlesnake traverses the country, monarch of all he surveys; he strikes +rapidly with a vigorous tail upon the calcined ground; and woe then +to any one who receives his bite! All the fire of the atmosphere has +passed into his frame. Now go to the Zoological Gardens, and see him +there: he crawls languidly under the coverings that shelter him; if +by chance he bites any one, it is with an idle tooth that no longer +knows how to kill; his life was left behind with the sun of the tropics, +and it is little more than a corpse that you are looking at. + +And so among ourselves, my dear child: we meet with people whose whole +power comes from without, who are brilliant and haughty in the sunshine +of good fortune, but crest-fallen, cowardly, and cringing in the cold +days of adversity. Nevertheless, they are constituted originally like +other people: they are neither greater fools as a general rule, nor +less gifted than their neighbors; where they fail is in the heart, but +that is enough to spoil everything. And so with reptiles: the heart +is their weak point also. Like us, they have lungs into which the air +pours without any difficulty, and a heart to send the blood to them; +so it seems at first sight as if there could be nothing to prevent +their resisting the changes of external temperature just as well as +ourselves. There is only one small trifle wanting, and that is a +partition in the middle of the heart; but this one defect is enough +to disorder the whole machinery. + +You know that, with us, the heart is divided into two compartments: +the right ventricle, which receives the venous blood from the organs +and sends it to the lungs; the left ventricle, which receives it (now +become arterial) from the lungs and returns it to the organs. Hence +the double system of veins and arteries, the one going from the heart +to the lungs, the other from the heart to the organs. All this is found +the same in reptiles: except that the partition, which separates our +two ventricles from each other, does not exist in them; and the heart +has only one common room, in which, therefore, arterial and venous +blood become mixed together. It follows from this that, at each +contraction of the heart, it is a mixture of arterial and venous blood +which is sent in the two opposite directions at the same time, and +that the organs receive some which has been used before, while the +lungs have some returned to them which has been regenerated already. +Now, on the one hand, this mixed blood can only keep up an imperfect +combustion in the body (like the live embers between two layers of +ashes that we spoke of lately), and, on the other hand, the air in the +lungs can only act upon a part of the blood it meets with there, the +rest having already undergone the regenerating process. And this +accounts for both the feeble animal heat and the small consumption of +oxygen in reptiles. + +Added to which the lungs of a reptile are coarsely constructed, and +composed of cells enormous in comparison with ours, so that the blood +does not find nearly as many little chambers to rush into for a taste +of air as with us. Moreover, you must understand that there is no such +thing as a diaphragm here: the lungs float loosely in the form of +elongated bags in the one only cavity of the body, and the slight +movement of the ribs does not allow them to dilate sufficiently to +take in much air at a time. + +All these things, taken together, make the reptile a very poor stove, +and render him incapable of any prolonged exertion. The serpent darts +like an arrow upon his prey; but he could not pursue it for half a +mile without stopping, not even over the burning soil of the equator. +The lizard is very nimble, is it not? and the quickness of its movements +rather reminds one of the agility of a bird. But watch it, and you +will see it only moves in jerks, and keeps stopping every minute; it +cannot escape you if there is no hole near into which it can disappear. +In France there is a large green lizard that runs among the vine trees. +If you pursue him he is off like lightning for a second; then he stops +suddenly short. You return to the charge, and he starts afresh, but +only to stop again. At the fourth or fifth attack he is quite out of +breath; you poke him with the stick with which you have been hunting +him, but in vain; there he lies motionless, in spite of his alarm. A +few steps have brought him to the end of his powers, like a man whose +heart is diseased and who cannot go far. This, however, is a peculiarity +common to all reptiles. Each of the three orders of which this third +class of Vertebrata is composed has its own particular history besides. +You must excuse my mentioning the barbarous names that have been given +them, and allow me to call them _tortoises_, _lizards_, and _serpents_, +like other people. The hard names mean no more than these; but they are +Greek, which is always more imposing. + +The slowness of the tortoise has passed into a proverb, which is not +to be wondered at; for they cannot inhale the air, because their ribs +(which are a reptile's only resource for breathing) are condemned to +absolute immobility. The _carapace_, or shell, which the tortoise +carries on his back, and under which it retreats upon the least alarm, +as under a shield, is really formed of its ribs, each of which has +widened itself so as to join on to its neighbor, like the boards of +an inlaid floor, which run one into another. Of course there is no +question of moving up and down with such ribs, and the poor bellows +cannot work at all. How does the tortoise get out of this difficulty +then, you will ask? I answer, it swallows air, as we should swallow +a glass of water. You see its mouth open and then shut again, thereby +taking in an actual mouthful of air, which the sides of the mouth, by +contracting themselves, send straight to the lungs. These, which are +very large, get filled in this way by degrees, and, when they are quite +inflated, they expel the overplus by collapsing, like an over-stretched +spring. You may imagine that this does not produce a very active +respiration, and that a tortoise would be puzzled to run at even a +moderate trot. To be sure, when he has once filled his great lungs +with air, he has enough for a long time. Most tortoises are aquatic, +and, as divers, leave the cetaceans far behind. Mery, an obscure French +naturalist of the days of the Empire, pretended that he had kept in +his house, _for a month_, some tortoises, whose breathing he had +completely stopped. Only imagine from this how far their life must be +below ours, although it is the result of similar actions, performed by +organs which after all are copies (imperfect ones, it is true) of our +own. + +Some tortoises feed on vegetable substances, and some upon fish or +small soft-bodied animals. Like birds, they mash their food with +difficulty, by means of a real bill. Their jawbones are generally +arched forward toward the front, and are furnished with sharp horny +plates, in which a fairly-marked denticulation or notching may sometimes +be traced, as in the bills of birds of prey. Indeed there is one, the +_caretta_, whose hooked and notched beak so completely recalls +the warlike bill of a hawk, that it is usually known by the name of +the "Hawk's-bill Turtle." You ought to know about this tortoise, for +it is the one which furnishes tortoise-shell, that nice material which +is so smooth to the touch, so pretty to look at, and so very fragile, +that it seems only fit for the use of ladies' hands. I could hardly +speak of tortoises without saying something of this one, out of +whose back was carved the handle of your own pretty little penknife. + +Behind this bill of the hawk's-bill there is a tongue, but of the +character of a whale's tongue, and it is fastened underneath to the +bottom of the mouth. At the base of it there is a sort of fleshy pad +or cushion, which serves instead of a soft palate, that being another +detail which is about to disappear from our history. We are now really +entering upon the simplification of the digestive tube, which will, +I forewarn you, end by being nothing more than a perfectly straight +pipe, without any appendages whatever. In tortoises the intestine is +still tolerably long, and is doubled up backwards and forwards many +times in the abdomen; but it is already beginning to lose that variety +of form which its different parts assumed in the higher animals. The +large intestine can no longer be clearly distinguished from the smaller +one, nor this from the stomach, which itself seems to be a continuation +of the oesophagus, without any very distinct boundary line between them. +The porter, who with us keeps the door of the stomach, does his duty +here so badly, that there are certain kinds of tortoises whose +oesophagus is covered with spines, the points inclined backward, to +prevent the food from rising up into the mouth whilst the oesophagus is +driving it down by its contractions. + +In the gray lizards of our walls we find teeth again, but very different +from any that we have hitherto seen. In the first place, they are not +content with their usual place on the edge of the jaws, but encroach +upon the surface of the palate, where they stretch out in close lines. +Besides, they are even still less like teeth than the great nails in +the jaws of the cetaceans. They are little ivory prongs, with the +points turned inwards, analogous to the thorns of the oesophagus in the +tortoise, and serve the lizard solely to retain and bruise his prey. +He lives on insects, especially flies, which he seizes on the wing +with the greatest skill, hastily catching and engulphing them in his +open jaw; they pierce themselves on the little prongs, and are swallowed +promiscuously. The tongue of the lizard has also a curious peculiarity, +which is shared by that of the serpent: it is divided at the end into +two threads, which dart in and out of its mouth, and by means of which +it laps, like a dog, the few drops of water it requires to satisfy its +thirst. I have seen lizards which had been tamed by children greedily +sucking up the saliva from their lips by drawing across them those +little forked tongues of theirs, which, after all, are very soft, and +perfectly inoffensive. + +The tongue of the chameleon, another species of lizard, is still more +curious. You must know that the chameleon is a lumbering lazy animal, +who feeds on flies and other swift insects, and who would, therefore, +be constantly liable to go without his dinner but that his tongue +serves him for a hunting weapon, like those of the wood-pecker and the +ant-eater. When at rest, it is an oval spongy mass, lying comfortably +in the mouth, with nothing formidable in its appearance; but let the +prey come frisking round the chameleon, as if despising so helpless +an enemy, and this great soft tongue is transformed into an active +dart. It shoots forth like an arrow, and will sometimes seize the rash +intruder at half a foot's distance, transferring it with equal rapidity +to the motionless mouth. The blow is so soon struck, that it is very +difficult to see how it all happens. Some say that the chameleon curves +the tip of his tongue by a sudden effort, and then catches his flies +with it, just as you would catch them with your hand. Others maintain +(and this is the general opinion) that the tongue of the chameleon is +terminated by a sort of sticky cushion, on which the flies are caught, +like birds with birdlime. This singular dart is always out-jerked with +such force that, if it strikes against a glass (the experiment has +been tried with chameleons in captivity), it makes a sound as loud as +that of a pea from a pea-shooter; so you may judge if it is not strong +enough to stun a fly. Besides this, too, the chameleon (who is +by-the-by, a hideous little beast) has given endless trouble to +naturalists on another and very different point. It is he who is +so celebrated for his faculty of changing color when any emotion +agitates him; and ever since the days of Aristotle, who lived more than +two thousand years ago, people have been trying to explain this, without +any one being able to flatter himself that he has found out the exact +answer to the riddle. + +But there is a lizard more interesting still, and that is the crocodile. +He stands alone among reptiles. His heart has two ventricles, and you +would think that he ought to be included in the class of warm-blooded +animals. But, no. The separation of the two kinds of blood takes place +in the heart, it is true, and it is really true arterial blood which +the aorta carries away from the left ventricle. But the right ventricle +has two doors of exit. One communicates with the lungs, the other with +the aorta; and the latter has hardly performed its distribution in the +upper part of the body when it meets, as it descends, with a treacherous +tube bringing to it a current of venous blood. In this way only half +the blood that comes from the veins passes on to be regenerated by +contact with the air, and all the hinder part of the body receives +nothing but the mixed blood common to reptiles, while the head and +fore members enjoy the privilege of the superior orders. After this +go and lay down your laws of classification! Nature, while maintaining +amongst all animals the same principle of life--the regeneration of +the blood by oxygen--has in their construction followed many systems +leading to the same result by different combinations, and which seem +to permit the establishment of essential distinctions among them. Here +is an animal who, if I may so express myself, is climbing up from one +system to the other, and you would have to cut him in two before you +could classify him properly, since his fore-quarters have risen to the +warm-blooded animals, while his hind ones are left behind among the +cold-blooded reptiles! + +But there is something which even outdoes this. + +On dry land the crocodile is timid, faltering, a bad walker, incapable +of regular combat, and a man can manage him with a stick. One feels +that he is betrayed by the hinder half of his body, through which +circulates the only half-oxygenized blood. But when once he has plunged +into the water his whole behavior suddenly alters; he is a ferocious +being, high-mettled, indomitable, a savage enemy, redoubling his +exertions, as if the entire mass of his blood had suddenly become +arterial. Geoffroy St. Hilaire, who followed Bonaparte as a scientific +explorer when he set out for the conquest of Egypt, the country of +crocodiles, was deeply struck by studying on the spot this double life, +which seems in a way to maintain two beings in the same body. He +afterwards gave an extremely curious explanation of it in his work on +the crocodiles of Egypt. Here it is; but I forewarn you that you will +not understand it: + +"The crocodile, when it is under water, receives by two canals into +the cavity of the abdomen, a considerable quantity of water, which the +animal can renew at will." + +You are not much the wiser, are you? But wait a moment. We are soon +coming to the fishes, and you will then see what an unlimited scope +nature has allowed herself here. Not satisfied with two systems in one +animal, she appears to have got hold of three. + +If we continue the examination of this privileged reptile, we shall +find many other infractions of the usual rules of his class. His tongue, +certainly, is fastened to his mouth like that of the tortoise, so much +so that the ancient Egyptians told the Greeks he had not got one; but +his set of teeth clearly approach those of the lower mammals. You have +probably heard a great deal of the strength of the crocodile's +formidable teeth. Travellers have given them this reputation; but we +have nothing to do with that now. They stand in battle array, in a +single line, along the whole length of the jaws, into which they are +sunk with genuine fangs, whilst the prongs of our little lizard are +merely fastened to the surface of the bones which support them. Indeed, +in one way, the crocodile is even better provided than the mammals. +He possesses under each tooth one or two germs, the life of which lasts +as long as that of the animal, and which are always there ready +toreplace the previous one should it chance to fall out. There are many +ladies, and (not to be rude) gentlemen as well, who would, I am sure, +give a great deal to have as many teeth at their service. Indeed, they +may possibly think Dame Nature very unjust to have selected this great +villanous beast rather than us as the object of a gift which they would +have been so well able to appreciate. But we must not blame nature too +quickly: she had her reasons. We, during our infancy, have teeth in +reserve. Now, a reptile may be considered as an imperfect rough draft +of a mammal; and the crocodile gives one thoroughly the idea of a +mammal half-finished and fixed for life in a state of childhood. I am +sorry that I cannot enter into full details, that you might see how +far the idea is a just one. Moreover, in his character of a perpetual +child, he is always growing bigger all his life long, and never seems +able to die but by accident, hardly ever, I may really say, from old +age. By specimens kept in captivity, it has been ascertained that +their growth is very slow. Well, imagine their being only from seven +to eight inches long when they come out of the shell, and that +full-grown crocodiles have been found thirty feet in length, and +calculate accordingly. You will not account for it under a century; +and I should like to know what would become of this venerable child +of more than a hundred years old if kind Mother Nature had not left +him our system of milk-teeth to the end? + +A curious peculiarity of these persistent teeth is, that they are +hollow inside, so much so, that the bowls of tobacco-pipes are said +to be made from them in Europe. I mention the fact, although of no +great interest to you, for the benefit of any pipe-merchants who have +not yet thought of sending for such things to Cairo. + +But let us return to the efforts perceptible in the organization of +the crocodile to raise itself to a higher level. The soft palate, as +we called it (Letter VII.), is wanting in other reptiles; but here +there is one which completely closes the entrance of the windpipe (the +larynx). I announced, too, the disappearance of the diaphragm; and we +bewailed together the loss of that servant of the good old times, whose +touching history you must, I am sure, remember. But I reckoned without +this wretched crocodile, who seems determined to give the lie to all +we have been saying. He has a diaphragm, and one which acts well enough +in the main, although it is pierced right through the middle, as if +it were rather ashamed of being there, and wished to make up for +dividing the body into two compartments, against all proper reptile +regulations, by opening a door of communication between them. What +shall I tell you besides? The lungs, not to be behind the rest of this +aristocratic reptile's organization, are hollowed into cells much more +complicated than those of his fellows. You find here no end of nooks +and corners, which multiply opportunities of contact between the air +and the blood, and so give the crocodile almost the respiration of the +mammals, as he has already got pretty nearly their system of +circulation. + +With serpents, again, we fall very low. When we were speaking of the +tortoises I told you that, in proportion as we come down in the scale, +the digestive tube has a tendency to get rid of its accessories, and +to assume the appearance of a perfectly straight tube. If any one were +to cut open a serpent before you, you would see this final condition +almost reached already. In the first place, the soft palate is entirely +suppressed, and the mouth extends straight into the oesophagus, whose +tube seems to run through the whole length of the body without +interruption, with just four or five doublings towards the base, in +that part which represents the intestines. An imperceptible swelling +indicates the place where the real stomach lies within; but in another +sense one may call the oesophagus, and I might almost add the mouth +itself, its stomach. You shall see how. + +The jaws of serpents are even in a more unfinished state than those +of other reptiles. Nature has not taken the time to weld the different +parts of them together; but these begin by not being very firmly joined, +remember, in young mammals. The bones of the head, which support the +jaws, are themselves movable, and can be detached from the skull if +necessary, so as to allow the throat to open extraordinarily wide; +thus it is not uncommon to see a serpent swallow animals much larger +than itself. You will be horrified when I tell you that the anaconda, +one of the giants of the family, swallows large quadrupeds at a single +mouthful. What are our mouthfuls in comparison with his? however, it +must be confessed, that his often take several days to go down. When +the animal has rolled up his prey in his terrible folds, he pounds and +kneads it till it is reduced to a kind of long roll, which he moistens +with a copious slaver to make it slip down more easily. Then, attacking +it at one end, he fastens this very expansive jaw upon it, and the +gigantic mouthful slowly begins its journey; what was left outside the +mouth, advancing little by little, in proportion as the digestion +reduces what has entered to pulp, and sends it farther down. This is +on great occasions; but in the case of more modest prey--a rabbit, for +instance--the mouthful goes in whole at one gulp and remains stationary, +partly in the oesophagus, partly in the stomach, while the powerful +juices distilled by the walls of the latter are dissolving it. + +You can see that a soft palate would have been quite useless here, and +that the serpent has not much need of teeth to chew his food. +Accordingly, his are nothing but simple prongs, like those of the +lizard, and, like his, they extend over the palate, the more effectually +to cut off the return of the swallowed masses of food. About a hundred +and twenty have been counted in the throat of the boa-constrictor; but +their number varies considerably in the different species. They are +not organs of the highest order, and nature is not very particular +about the quantity. + +There is only one tooth among serpents of which she takes any particular +care, and that is the venomous tooth which she has bestowed on certain +species, and which serves them for striking down, as it were, the +animals on which they feed. Let us study it in the rattlesnake, the +most celebrated of this odious race. On each side of the upper jaw you +may see, isolated from the others, and exceeding them all in length, +a very sharp fang pierced through by a tiny canal, which opens into +a gland placed at the root of the tooth. The bone which supports this +little apparatus is very flexible, and when at rest, the fang, falling +back, hides itself in a fold of the gum. When the animal wishes to +bite, it springs up again, and the gland, compressed by the action of +biting, sends into the little canal a jet of poison, which runs through +it into the wound. As far as can be ascertained, this poison paralyses +the victim and disorders the blood, which at once loses its power, +and no longer acts upon the organs as before; still it is only injurious +when it has been carried by the current of circulation into the mass +of the blood; if swallowed, it has no effect whatever on the stomach. +Now do not look at me with such incredulous eyes, as if it were quite +impossible any one should think of swallowing such a thing. You have +no idea what a scientific man is capable of when he comes to close +quarters with nature, for the purpose of extracting one of her secrets. +He has his own fields of battle, where very often as much courage is +displayed as on any other. + +These two fangs, in which lie all the power of the animal, are of the +greatest importance to him, and their want of solidity makes them +liable to remain in the wounds which they have made. In consequence +of this, they enjoy the same privilege as the teeth of the crocodile, +and in a still greater degree even. Behind each poison fang lie in +wait, not one nor two, but several sentinel germs, ready at the first +alarm of a loss to set to work and re-supply the disarmed serpent with +his venomous needle. So the serpent also lives in a state of perpetual +childhood: he is always growing; and I could not tell you the exact +natural limits of his life any more than of that of the crocodile. +They are gentlemen who do not allow themselves to be very closely +studied in a state of freedom. But these also grow very slowly, and +some have been met with whose size had extended quite enormously from +their first start. I ought to tell you, once for all, that this +indefinite growth, joined to extreme longevity, is found in many of +the inferior species whom we have yet to consider. It seems the portion +of these unfinished creatures, in which nature has only as it were +sketched in her work, and who seem vowed to endless youth, in testimony +of the state of childhood they represent, a state transitory among the +superior animals, but permanent with them. It belonged of right, +therefore, to the serpent, which is the most unfinished animal we have +yet met with, and who, at the first glance, seems almost reduced to +a mere digestive tube, lodged between a vertebral column and a series +of small ribs, whose number sometimes reaches three hundred. The liver, +which, with us, presents such a distinct and bulky mass, is here +elongated into a thin cord, which runs the whole length of the +oesophagus +and intestine, to the walls of which it is, to some extent, attached. + +It is the same with the lungs. There is rarely room for the full +development of two in this narrow conduit, where everything has to +follow the shape of the master of the house: one, therefore, is often +merely indicated by a very slight protuberance; the other, presenting +the appearance of a long tube, which extends nearly half-way down the +body, and whose feeble action halts periodically at each of those +monstrous repasts, after which the torpid animal becomes nothing but +a huge digesting machine. We have now reached the extreme limits of +that organization, the most perfect model of which we find in man, and +which is no longer to be recognized in fishes. + + + +LETTER XXXVI. + +PISCES. (_Fishes._) + +We are becoming terribly learned, my poor child, and I am half afraid +you will be getting tired of me. When I was little myself, I had rather +a fancy for breaking open those barking pasteboard dogs you know so +well; to see what was inside them. Why should you not, then, feel a +certain amount of interest in looking with me into the insides of real +animals? Still I cannot conceal from myself that the subject grows +very serious at last, and that while I am busied in struggling to make +myself intelligible through the endless crowd of facts which surround +me, I am apt to neglect chatting with you as we go along. Happily, +however, here is an opportunity for so doing. + +Up to the present time we have lived, as it were, upon the explanations +I gave you whilst studying the action of life in yourself, and all the +organs we have met with since, have been only, properly speaking, +reproductions, more or less exact, of those which you yourself possess. +But, in passing over into the kingdom of fishes, we find ourselves in +the presence of something altogether new, and I must go back to our +old familiar style of talking to open the subject. + +Take a water-bottle half-filled with water, and shake it well, and you +will see a quantity of white froth come to the surface of the liquid. +This is the air which having been drawn in by the water, as it went +up and down in the bottle, is now struggling to fly off again in bubbles +as fast as it can. But the whole of it does not get away; a small +portion remains behind, and melts, as it were, into the water, as a +morsel of sugar would do, taking up its abode therein. This seems odd +to you, but I will tell you how you may convince yourself of the fact. +Get a small white glass bottle, slightly rounded, and thin at the +bottom, if possible; fill it with water, and hold it for a short time +over a lighted taper. If you do this carefully there is no danger. You +will soon see tiny little balls, looking like drops of silver, rise +from the bottom of the bottle, come up to the surface, and burst. This +is the air which was installed in the water, as I described above, and +which is now running away from the heat of the candle, as the +inhabitants run away from a house on fire. After a time the whole will +have passed off, and the little balls will cease to rise. + +But what has all this to do with fishes? you ask. + +A very great deal, I assure you, dear child. If there had been a little +fish in your bottle, before it was exposed to the flame, it would have +found means to make use of that air, whose original presence in the +water you cannot refuse to believe after having seen it come out. It +is with this air that fishes breathe in the water. They do so rather +feebly, I admit; but, as if to make up to them for the small amount +of the air placed at their disposal, it contains more oxygen than that +we breathe ourselves, because oxygen, dissolving more readily in water +than nitrogen, is there in greater proportion. Of course, you do not +suppose that fishes have lungs like ours? I dare say you know the two +large openings on each side of their head, called _gills_, by which the +fishermen string them together to carry them away more easily? It is +there you will find their lungs, to which the name of _branchiae_, or +gills, has been given, because they are so different from other organs +of respiration that it was impossible to use one word for the two. The +arrangement of the gills varies considerably in the different species, +but their general form is the same everywhere. They are composed of a +number of plates, consisting of an infinitude of leaflets, arranged like +a fringe, and suspended by bony arches, into which plates and leaflets +the blood pours from a thousand invisible canals. + +First of all, then, we must see how blood circulates in fishes. + +Like reptiles, their heart has only one ventricle, and yet the arterial +and venous blood go each its separate way without the slightest risk +of being mixed; but this is because fishes have not that double system +of veins and arteries which hitherto we have always met with. The +venous blood goes to the heart, which drives it into the gills, from +whence it passes forward of its own accord, as arterial blood into the +organs, under the remote influence of the original impetus from the +heart, the newly-arrived blood incessantly driving the other before +it into the vessels of circulation. It does not flow very quickly, as +you may suppose; and as the heart is close to the head, its action is +but very feebly felt at the extremity of the body, when this happens +to be very long. Nature has, in consequence, taken pity on the eel, +whose tail is so far from its heart, and provided accordingly. Dr. +Marshall Hall has discovered near the tip a second, reinforcing heart, +so to speak, which has its own pulsations, independent of the pulsations +of the one above, and gives a fresh impetus to the sluggish blood, +[Footnote: Many observers refer this to the lymphatic system.--TR.] +which otherwise, as it would seem, would scarcely be able to accomplish +the long return journey. Finally, even with an additional heart in +thetail, the circulation among fishes is quite on a par with their +respiration. They have a melancholy steward, whose legs are very heavy, +and his pockets very light, and their life comes down a peg lower in +consequence. It is always the same life nevertheless--you must never +lose sight of that fact: it gets low in consequence of the imperfection +of the machine, but without changing its nature, any more than the +light in our different sorts of lighting apparatus. You remember that +comparison of the lamp with which I began my story, and which you could +not at the time see the full value of? From a dungeon lamp up to a +candle, you have always grease burning in the air at the end of the +threads of a wick. It does not burn equally well everywhere, and does +not always give the same amount of light; but that is all the +difference. From the mammal to the fish, it is always hydrogen and +carbon (as we have said of the grease) which oxygen sets on fire in +the human body at the fine-drawn extremities of the blood-vessels; +only the fire is lower in some than others, and the life with it. Let +us now look at the circulation of water in the fish's body. + +The gills communicate with the mouth by a sort of grating, formed by +the bony arches to which the gill-plates are suspended. The fish begins +by swallowing water, which then passes through the grating and +circulates round the innumerable leaflets of which each plate is +composed, and among which creep the blood-vessels. It is through the +thin coats of these leaflets that the mysterious exchange is made of +the unemployed oxygen in the water and the carbonic acid in the blood. +When this is over, the cover which closes the gills opens to let out +the water, and a fresh gulp takes its place; and so on continually. +When the fish is out of the water its gills fall together and dry up; +the course of the blood, already so weak, is interrupted by the breaking +down and shrinking of the vessels, and the animal can no longer breathe; +so that we have here the curious instance of a creature breathing +oxygen like ourselves, who is drowned, if we may use the expression, +in the air in which we find life, and lives in the water in which we +are drowned. While he is in the water matters take another course, and +his gills, moistened and supported, accommodate themselves perfectly +to the contact of the air, which desires nothing better than to give +up its oxygen to the blood, through the coats of the capillaries. +Accordingly you will often see fishes--carps, for example--come to +the surface of the water to inhale the air like a mammal or a reptile. +This is a valuable resource, which supplements the parsimonious +allowance of air given out to them by the water. There are even certain +fishes whose gills, more firmly closed than those of others, have, in +addition, a number of cells, which retain for a considerable time a +sufficient quantity of water to preserve the gills in their natural +state. These fishes can easily take an airing on land, where they +breathe the air as you or I do, and are downright amphibians. + +The most celebrated of these is the _Anabas_, or "climbing-fish." +an Indian fish, which not only can remain many days out of the water, +but also amuses itself by climbing up the palm trees--it is hard to +say how--and establishing itself in the little pools of water left by +the rain at the roots of the leaves. But we need not go to India to +find those wandering fishes. There is one of them living among ourselves +who can walk about in the grass, and I was talking to you about him +only just now--that is the eel. If you ever put eels in a fish-pond +you must, I assure you, try to make it agreeable to them, otherwise +they will have no scruple in setting politeness at defiance and moving +off to seek their fortune elsewhere. In a country walk, when the dew +is on the ground, you yourself may chance to come across one or two +of these gentlemen, who have had their reasons for changing their +residence, and whom you will see gliding so briskly along that they +will deceive you into taking them for snakes if you have not a very +experienced eye; so much so, that in certain parts of France where the +peasants ate snakes formerly, they reconciled themselves to the sickly +idea by christening them _hedgerow-eels_. + +On the other hand, fishes may be drowned in water just as easily as +ourselves if it does not contain air. The little fish who could have +lived very well in the bottle we were just now talking about before +you exposed it to the flame of the taper, would have died in it after +all the air-bubbles had gone off; and I hope I need not tell you why. +In the same way, if you leave fishes too long in a small quantity of +water without renewing it, they suffer exactly as we do if the air +which we breathe is not changed often enough. As soon as they have +consumed what oxygen is in the water, it can no longer keep them alive. +It is then, especially, you will see them come gasping to the surface +to call upon the air for help. Those who keep gold fish in a glass +bowl ought to know this, and to change their water oftener than is +generally done. When we take poor little creatures from their natural +way of life, and set a human providence over them in the place of the +Divine one which has hitherto been their safeguard, the least we can +do is to acquaint ourselves with the laws of their existence, so that +we may not expose them to the risk of suffering by our ignorance. +Finally, there are fishes whose gills, still more greedy of oxygen, +will not act well except in thoroughly aerated water, and who would +soon die in our tanks. This is the case with the trout, who is only +happy in the waters of hilly countries; rich with all the air they +have carried along with them as they fell from rock to rock. Now that +people are beginning to do with fishes what has long since been done +with sheep and oxen--keep them in flocks to have them always ready for +use--you may perhaps hear a good deal said about vessels made expressly +for the carriage of trout, with a thousand inventions besides for +sending air into the water, and you will not have to ask the meaning +of this now. + +I promised last time that I would revert in the chapter of fishes to +that marvellous transformation of the crocodile which has been explained +by the torrent of water he draws into his stomach. You could understand +nothing about it the other day; but after what we have just seen the +explanation suggests itself. Just as the extraordinary activity of +life in birds is explained by that double oxygenization of blood, of +which part takes place in the lungs and part in the reservoirs of air +placed everywhere in the way of the capillaries, so this sudden increase +of energy in the crocodile the moment it plunges into water may be +explained by a second respiration suddenly established in the vast +cavity of the abdomen, by the contact of the capillaries with the water +which penetrates there. Hence the crocodile would then have, like the +bird, a double respiration: only with him the one would be permanent +and from the lungs, the other temporary and from the stomach. By this, +on the one hand, he would rise up to the birds, since the blood +encounters air twice over in its course, while, at the same time, he +would plunge into the world of fishes, since the blood has to seek air +in the water. The above, be it remembered, is only a supposition, and +I ought to add that in this case there would be a good deal of danger +in observing nature at work, for in front of the laboratory, where she +is toiling in secret, stands on guard a row of teeth, by no means +encouraging to indiscreet intruders. At the same time, if there ever +were a legitimate conjecture, this is it. Everything seems to confirm +it; and if it be true, we should have in the crocodile a specimen of +each of the four systems adopted by nature for the mammal, the bird, +the reptile and the fish. At first I spoke of two, then of three; so +that even in my addition I was modestly below the mark, and had really +some grounds for recommending our friends the classifiers to beware +what they asserted in this case. + +Talking of puzzling classifications, this is just the place for +mentioning the _batrachians_, who have been made into a class by +themselves, but who most distinctly belong to two classes at the same +time; not like the crocodile by details borrowed from each, but by a +fundamental change which takes place at a certain period in their +organization. The batrachians are in reality reptiles, but they are +reptiles which begin by being fishes, and real fishes too. + +If you have ever strolled about in the country, you must have often +come across those great pools of water which collect at rainy seasons +in the ruts of deep lanes. Amuse yourself by looking into them in +early summer, and unless the land is too parched and dry, the chances +are that you will see quantities of little black fishes, almost entirely +composed of a long tail joined to a large head, playing jovially in +the muddy waters, and looking as if they had dropped there from the +skies. These are young frogs--_tadpoles_, as we call them--and +they are beginning their apprenticeship of life. Enclosed in each side +of those great heads, they have gills, and they breathe in the same +manner as fishes. Presently the two hind feet begin to bud out and +grow, little by little; then the fore feet; finally, the tail wastes +away till it disappears; and thus insensibly the tadpole is transformed +into a frog. Observe here that the tadpole's gills share the same fate +as his fish-tail; they wither and disappear by slow degrees, and +gradually as they do so, his lungs are developed. The animal changes +his class very quietly, and without ceasing to be genuinely the same, +although it would be impossible at last to recognize the old individual +in the new if you had not heard its history beforehand. This is one +of the most striking exemplifications I know of the mysterious process +by which nature has insensibly raised animals from one class to another, +always improving upon her original plan without ever abandoning it. + +On the shores of certain subterranean lakes which exist in Carniola, +a country subject at this time to Austria, there are to be found +batrachians far more ambitious than our frog--namely, the _proteans_. +These cumulate rather than change: they become reptiles without ceasing +to be fishes, if I may so express it; they develop lungs as they grow +up, and yet keep their gills. I could tell you a thousand other +particulars about these batrachians if I were to examine them all in +succession; for it is a very motley family, in the bosom of which the +transition from reptiles to fishes is in some imperceptible manner +accomplished; from the frog, which the unanimous consent of mankind has +always ranked among reptiles, to the axolotl or siren, who lives in +Mexican lakes; and who, feature for feature, is exactly like a carp, +with four little feet fastened under him. To be quite in order, the +batrachians ought to have followed the reptiles, for their interior +organization is the same; but how could I tell you about their gills +without explaining that there was air in the water? and I did not want, +for the sake of these intruders, whose babyhood-gills only just appear +and disappear, to rob the history of the fishes of its most interesting +points. + +Let us be satisfied, then, with this passing glance at a dubious class, +whose history is only a repetition of two others, and let us return +to our friends the fishes. We have seen how they breathe, now let us +look how they eat. + +The modifications of the digestive apparatus are endless among fishes. +The lampreys, who are placed in the lower ranks of the class, carry +out to its fullest extent the type which we have already seen indicated +in the serpent. The digestive tube is quite straight, without any +perceptible swelling, and does not even go the whole length of the +body. It comes to an end at some distance from the tail. Among some +fishes an odd tendency begins to display itself, which we shall meet +with again farther on. The digestive tube, after going downwards towards +the bottom of the body, as we have seen it do so constantly hitherto, +doubles back, and comes up again to the throat, under which it empties +itself. In most cases the stomach is distinct; but it assumes a thousand +different forms; as if nature had wished to try her hand in all sorts +of ways in the construction of these imperfect vertebrates, before +adopting the definite model which was to serve for the others. + +The liver is enormous, and generally contains a great quantity of oil, +the taste of which you will know if you have ever swallowed a spoonful +of cod-liver oil; but in most fishes its old companion, the +_pancreas_, has disappeared. In its stead you will find, close +by the outlet of the pylorus, the open ends of certain small tubes, +which are shut in at their upper extremity like a "blind alley," and +through which descends into the interstices a thick glairy fluid, given +out from their sides or walls. The result is the same, you see, although +the organ is different; and, remarkably enough, these little tubes are +wanting among fishes, which, like carp, have a species of salivary +glands in their mouths, of which the others show no trace; from which +one may fairly conclude that these glands and tubes mutually supply +each other's places. Here, then, you see an instance of the light which +different animal organisations throw upon each other when they are +compared together. In fact, this one establishes pretty clearly the +real office of the pancreas in the higher races, exhibiting it to us +as an internal salivary gland, intended to complete the work only begun +by those in the mouth, in the case of lazy people who swallow their +food too quickly. + +There is the same diversity in the mouth as in the intestine. Some +fishes, like the skate, have no tongue at all. Others, instead of a +tongue, have a hard dry filament, very nearly immovable, and which one +would think was put there like a stake, to show the place where the +tongue is to be found in the more perfect organisations. There are +even fishes, like the perch and the pike, whose tongue is furnished +with teeth, or rather fangs; an evident sign that it has forfeited the +confidential position occupied by your own good little porter. You +must know also that the perch and the pike, like many other of their +fellows, have teeth all over the mouth. This invasion of the palate +by teeth, which began in the lizard and the serpent, assumes alarming +proportions here. It is not merely the roof of the palate which is +spiked with teeth: above, below, at the sides, everywhere to the very +limits of the oesophagus, the little fangs triumphantly stick out their +slender points. It is impossible, therefore, to state their number. +Nature has scattered them broadcast without counting, just as she has +done with the hairs of the beard round the human mouth; and the +comparison is not so impertinent as you may think. They sometimes form +an actual internal beard, even thicker than our outer one, and which +sprouts from the skin into the bargain. There is one fish whose teeth +are so delicate and so close together that, in passing your finger +over them, you would think you were touching velvet. This does not +refer to the shark, mind. His teeth are sharp-cutting notched blades, +hard as steel, arranged in threatening rows round the entrance of his +mouth, and cut a man in two as easily as your incisors do a piece of +apple. Others, such as the skate, have their mouths paved--that is the +proper term--with perfectly flat teeth. The first time your mamma is +sending to buy fish beg her to let you have a skate's head to look at. +You will be interested to see the small square ivory plates laid close +adjoining each other, like the tiles of a church floor. It is in fact +a regular hall-pavement, over which the visitors glide untouched, and +are then swallowed down in the lump; thus entering straight into the +house without having been stopped by the inscription nature has placed +over your door and mine--"Speak to the Porter." + +But all this is nothing compared to the lamprey's entrance-hall, which +differs from ours in quite another way. The lamprey, as I have already +told you, ranks almost lowest among fishes, and consequently among +vertebrate animals, of which fishes form the rear-guard. Indeed, it +is almost stretching a point to consider her worthy to bear the proud +title of a vertebrate at all; for the vertebral column, so clearly +marked in other fishes, where it forms the large central bone, is only +faintly indicated in certain species of lampreys, by a soft thread (or +filament), which is rather a membrane than a bony chaplet, and at the +top of this mockery of a vertebral column is the creature's mouth. If +you ever had leeches on, you will remember the sharp sting you felt +when the little beasts bit you. Well, the lamprey feeds herself just +in the same way as the leech does. Her mouth forms a completely circular +ring, which sticks to the prey, and through which runs backward and +forward a small tongue armed with lancets. This darts out to pierce +the skin, and draws in the blood as it retreats. Round your lips well; +dip them so into a glass of water, and draw back your tongue, and you +will at once feel the water rise into your mouth. It is by a similar +sort of proceeding that leeches relieve people of the blood they want +to get rid of; and in the same way the lamprey draws out the blood of +the animals upon which she fastens. + +What a long way we have come already! How very far we find ourselves +here from the little mouths we first talked about as chewing their +eatables so prettily! With the lamprey we bid adieu to the class +Vertebrata--the nobility of the animal kingdom--among whom nevertheless +we must distinguish between the peer, who approaches nearest the person +of his sovereign, and the inferior provincial lords who live at a +hundred miles' distance. There is only one step from the lamprey to +the _mollusks_ or soft-bodied animals, and this is the course +which animal organisation seems really to have taken in its progress. +But nature never moves forward in a single straight line. In passing +from the mollusk to the fish to get thence to the higher vertebrates, +she turned aside in another direction toward a class of animals which +rises far above mollusks, but which leads to nothing beyond. + +One would think there had been a check here, as if the creative power, +having discovered that it was going in a wrong direction, had retraced +its steps; if it be allowable to apply common ideas and expressions +to our conceptions of that Great Intelligence which has arranged the +plan of the mysterious ladder of animal life. + +The animals we must examine next, on account of their superiority to +the rest, are insects. Small as the ant is, it would not be right to +let her be preceded by the oyster. + + + +LETTER XXXVII. + +INSECTA. (_Insects._) + +Before speaking of insects, my dear child, it will be necessary, in +the first place, to tell you to what primary division they belong and +on what characters this division has been established. And here I find +myself in a difficulty. We have been but too learned already, and now +we run the risk of becoming still more so, if we commence an attack +on the three primary divisions which follow the vertebrates. We shall +have to encounter terrible names and tedious details, besides having +to take into account a thousand things of which we have not yet spoken. +We are going on quietly with the history of the feeding machine which +occupies the middle of the body, and learned men never looked in that +direction for the establishment of their divisions; between ourselves, +it was not accommodating enough. They have fallen back upon the +locomotive apparatus (_movement machine_) which affects the body +all over, and which they have proclaimed to be the leading feature of +the animal organization, without noticing however that it is, after +all, but the servant of the other. It is true that the great divisions +are more easily established upon this point than the other, because +the differences are more decided. It separates what the other unites, +and thus it is that nature carries on that beautiful combination which +the Germans have so accurately named "_Unity in Variety_" that +is to say, she is always at work, as I have already told you, on the +same canvas, but always embroidering it with a different pattern. +Wait! I have something to promise, if you are very good, and if this +history (that of the feeding machine) should have given you a taste +for inquiry. I will tell you another time the history of the movement +machine, and there the classification of our learned men will come in +naturally very well. In the meantime we will do as they do, and just +shut our eyes to their divisions, in which the feeding machine can +have no interest, because they were established without reference to +it. We will content ourselves, then, without further pretension to +science, with modestly examining the last transformations of our pet +machine in the principal groups of the inferior animals; of which +groups I will now tell you the names in their proper order. They are +as follows: Insects, Crustaceans, Mollusks, Worms, and Zoophytes. You +must take these names on trust; those which you do not understand will +be explained in their places. + +1. _Insects._--I know not where it was I once read that there are +said to be something like a hundred thousand different species of +insects; and I verily believe this is not all. Of course we shall not +attempt to review the whole of this formidable battalion. Let us take +one of those you are most familiar with--the cockchafer, for instance-- +and examine what goes on in his inside. The history is nearly that of +all the others. + +"Fly away, cockchafer, fly!" says the song; and surely it is a bird +that we have here, and a bird which will appear to you even more +wonderful than those of which I have already spoken, when you have +considered the simplicity, and at the same time the strength, of his +organization. His mode of flight is rather lumbering, it is true; he +is, in comparison with the large flies, what the ox is to the deer; +but when you contrast the weight of his thick body with the delicacy +and narrow dimensions of the two membranes which sustain him in the +air, you may well ask yourself how those little morsels of wings, thin +as gold-beater's skin, can carry such a mass along. In fact, they only +accomplish this feat of strength by dint of an excess of activity +almost startling to think of. When you run as fast as you can, how +many times, think you, do you move your legs in one second? You would +be somewhat puzzled to say; and so should I: but I defy you to count +ten. Now the bird makes his wing move much oftener when he beats the +air with rapid blows as he flies; but even he does not strike a hundred +strokes in a second: and what is this to the feats of the cockchafer's +wing? It is not hundreds but thousands of times that he flaps his wings +in a second; and here let me hint, by-the-by, that when people seriously +wish to find out a method of travelling in the air, they will lay aside +balloons, of which they can make nothing in their present condition, +and will set to work to fabricate machines with wings which shall beat +the air as fast as those of the cockchafer. This sounds extravagant, +but I have seen an electric pile fixed in a stand with glass feet, +which caused a little hammer to beat thousands of times in a second: +and surely the hammer could have been made to communicate its movement +to a small wing! Forgive me this little castle in the air! The idea +came into my head a long while ago, and the cockchafer has just reminded +me of it. I will not, however, pursue the subject, neither will I offer +to explain the method used for counting the beats of an insect's wing. +That would carry us farther than would be desirable. + +To return to our little animal. I leave you to imagine the enormous +amount of strength required for such precipitate motion. We have spoken +of the rapid course of the blood in birds during flight: who shall +calculate its comparative rate in this fabulously wonderful locomotive, +the cockchafer? And if we lift up the cuirass which encases it, what +do we behold? Not a single trace of all the complicated +circulation-apparatus you have learnt to know so well; neither heart +nor veins nor arteries; only a quantity of whitish liquid, equally +distributed throughout the whole internal cavity. Not a trace of lungs, +nor any apparent means of renovation for this seemingly motionless +blood; for blood it is, in spite of its color, or, at any rate, blood +in its first stage of formation. It also has its globules--ill-formed, +it is true, and altogether in balls--like those found in the chyle +with us; which chyle, be it observed, is the same color as the blood +of insects, and may also be considered blood in its apprenticeship. +By what magic, then, is this raw, imperfectly-formed steward, who seems +altogether stationary, enabled to accomplish exploits which would +stagger his higher-bred compeers, agile and perfected as they are? +Where does he pick up the oxygen necessary for such repeated movements, +it being an established fact that no animal can move at all without +consuming oxygen, and that the quantity consumed is in proportion to +the rate of motion? Look under his wings for an answer. There, all +along his body, you will observe a number of small holes, pierced in +a line, at regular distances, and furnished with shutters of two kinds. +They are the mouths of what are called _tracheae_, or breathing +tubes: and from them branch out a multitude of little canals, which, +spreading in endless ramifications through every part of the body, +convey to the whole mass of the blood, from all directions, the air +which makes its way into them through the tracheal holes. In this case, +you see, it is not the blood which seeks the air, but the air which +seeks the blood; whence arises a new system of circulation, whose +action is all the more energetic because it is unintermitting, and +makes itself felt everywhere at the same time. A little while ago we +were wondering at the twofold respiration of birds; yet this is far +less surprising than the universally-diffused respiration of insects, +who may well be able to do without lungs, seeing that their whole body +is one vast lung in itself. + +For the rest, do not trust to appearances, nor imagine that the blood +of our friend the cockchafer in reality remains motionless around the +air-tubes, idly drinking in the oxygen which is brought to it. Though +not flowing in enclosed canals, it is not the less continually displaced +by regular currents, which sweep through and renew this apparently +stagnant pool. Nor is this the only instance of such a current presented +to us by nature. + +Guess, however, if you can, where you will have to look for the +counterpart to the circulation of the cockchafer. In ocean itself! +But, remember, nothing is absolutely little or great in nature, who +applies her laws indifferently to a world as to an atom. The blood of +our world is water, which contains in itself all the germs of fertility, +and without which, as I have already told you, life is impossible +either in the animal or vegetable kingdom. The water of brooks, streams, +and rivers, flows along in channels, which, when figured in a map, +present to the eye of the beholder an exact picture of the system of +circulation found in the vertebrated animals. But the waters of the +sea are borne along, like the blood of insects, by a secret circulation, +which cannot be represented on the map; _i.e._ by immense currents +everlastingly in action, some on the surface, some in the mid-heart +of the ocean, which drive it in ceaseless course from the equator to +the poles, from the poles to the equator; so that the Supreme +Intelligence, in His overruling providence, has ordained the same law +to set in movement the immensity of ocean, and to effect circulation +in the cockchafer's few drops of blood. In the latter we find the +moving agent to be a long tube, which runs the whole length of the +back, and is called the dorsal vessel (from the Latin _dorsum_, +back). I told you that the cockchafer had no heart under his cuirass, +but I spoke too hastily. The dorsal vessel is a _true heart_, but +a heart devoid of veins or arteries, and thrown into the midst of the +blood. It dilates and contracts like ours, sucks in the blood by means +of side-valves, which act as our own do, and drives it back again into +the mass by that valve at its extremities, which opens near the head. +From thence arises a continued to-and-fro movement, which sends the +blood from the head to the tail, and brings it back again from the +tail to the head. But who would recognise, in this simple primitive +organisation, where all seems to go on of its own accord, as it were, +the same machine, with all its complicated movements, that we have +been so long considering? + +Well, in this apparently universal shipwreck of all the organs we know +so well, there is yet one which survives, and remains the same as ever, +namely, the digestive tube. I began by saying the insect is a bird. +His digestive tube is formed upon the same pattern as that of birds, +so that naturalists have bestowed the same names on the various parts +in each of them. After the oesophagus comes a crop (_jabot_), very +distinctly indicated; then a gizzard with thick coats, in which the +food is ground down. The hen, if you remember, swallows small pebbles, +which perform in her gizzard the office of the teeth in our mouths. +The cockchafer has no need to swallow anything. His gizzard is furnished +with little pieces of horn; real teeth, fixed in their places, which +have a great advantage over the chance teeth picked up at random by +the hen. I pointed out to you in birds, between the crop and the +gizzard, a swelling or enlargement of the digestive tube, pitted with +small holes, where the food is moistened by juices. The same enlargement +is found here, covered all over with a multitude of small tubes, which +might easily be mistaken for hairs, from which also falls a perfect +shower of juices. The only difference is, that it comes after the +gizzard, instead of before it, as in birds. Some naturalists, +considering that the manufacture of chyle takes place here, have called +it the _chylific ventricle;_ [Footnote: The corresponding +protuberance of the birds bears a name, somewhat similar, but stillmore +barbarous. I had passed it over in silence, because, I make the +confession in all humility, I do not understand it; but a remorse now +seizes me: it is called the _Ventricule succenturie._] a somewhat +barbarous name, but one which explains itself, and might with truth +be applied to the _duodenum_ of the higher animals. Bile is poured +in close to the hinder end of it, but you must not look for the liver; +it has disappeared, or rather its form is entirely changed. You remember +what the _pancreas_ had become in fishes; _i.e._ a row of tubes giving +out a _salivary fluid._ Such is exactly the appearance of the liver in +the cockchafer. + +Instead of that fleshy substance on which hitherto the office of +preparing the bile had devolved, you see nothing but a floating bundle +of long loose tubes, which, opening into the intestines, pour in their +bile. The organ is transformed, but we recognise it again by the office +it performs, which continues the same. As to the _pancreas_ it is +wanting here, as in the fish with salivary glands; but in its place +in many insects other tubes, acting also as glands, pour saliva into +the _pharynx; i. e._, the cavity at the back of the throat. + +As you see, therefore, everything is found complete in this tube of +a few inches long; and you can also distinguish there a small and a +large intestine. We are speaking of the cockchafer, which feeds on the +leaves of trees; and it is for this reason I name some inches as the +length of the digestive tube. This would not be longer than the body +itself, had it been destined, as in the case of many other insects, +to receive animal food. In fact, the law which we have shown to exist +with regard to the ox and the lion, rules also over the insect-world; +and whilst a radical change seems to have been made in the rest of the +organisation, here everything is in its place, and we find ourselves +in the same system. + +Was I not justified in asserting that the unity of the animal plan is +to be found in the digestive tube? and that this is the unchanging +basis upon which the Creator of the animal world had raised his varied +constructions? + +How would it be, then, if we were to take the insect from its +starting-point when it is only a worm, that is to say, merely and +simply a digestive tube? for I am only telling you a small portion of +its history here; a history you must know, which reveals a miracle +still more wonderful than the transformation of the little tadpole +into the frog! There is a brilliant-colored fly which comes buzzing +about the meat-safe--the bluebottle--do you know her? It is on her +account that we put large covers of iron wire over the dishes of meat; +but, perhaps, you never troubled yourself to think why. + +But the truth is, she only comes there to deposit her eggs in the good +roast-meat; and if she could get near enough to do so, you would soon +afterwards see it swarming with little white worms, which would entirely +take away all your appetite. These worms are only flies out at nurse, +and they will find their wings by-and-by if you only give them time +enough. Disgusting as they may appear on a dining-table, I assure you +they deserve more interest than you may think. When we come to speak +of worms, we will ask of them to let out the secret of the mysterious +transformations of animals. + +In the meantime, let us finish the observations we were making on the +_perfect insect_, as this little creature is called when he has +passed through the intermediate stages which separate him from the +undeveloped condition. Forgive me, my dear child, here I am speaking +to you as if you were a grown-up woman! This is because it is so +difficult to explain things of this sort in any other way. And now +that you have been introduced into the midst of the wonders of creation, +you ought to familiarise yourself with the ideas and terms they have +suggested to mankind. I began with you as a child, and great would be +my triumph if I could leave you a grown-up girl! And I flatter myself +that I have so far set your brain, to work, under pretence of amusing +you, that this hope is not altogether unfounded. I found it necessary +to say this to you in confidence, because I have just read over our +first conversations, and perceive that I have insensibly put you on +a different diet from the one I began with. I am obliged to comfort +myself by remembering that you have grown older since, and that you +are now acquainted with a great many things which you had never heard +spoken of then. And this is the secret of all transformations. We crept +on at first over ground that was quite unknown to us; but as we went +along, our wings must have begun to grow, and we are now able to fly +a little! + +Do not be afraid, however; I will exercise your tiny butterfly-wings +very carefully just at present. We have only to examine what becomes +of the _chyle_ of the cockchafer after it has been prepared in +the pretty little tube so finely wrought. We men have _chyliferous_ +vessels which draw up chyle from the intestines and throw it within +a short distance of the heart, into the torrent of blood, where its +education is completed. But the cockchafer, who has no other vessels +than his air-pipes, and the _dorsal tube_, which has no communication +with the intestines, what is he to do? Do not distress yourself about +him. Make a tube of a bit of linen, well sewn together, and fill it with +water. Sew it together as firmly as you may on all sides, the water will +have no difficulty in escaping through the meshes. And this is just what +happens with the little tubes found in animals, the coats of which are +formed of interwoven fibres. By-the-by, from thence comes their name of +"_tissue_," which they share in common with all the solid substances of +the body, for all were once supposed to have the same general structure. +The intestine of the cockchafer floats, did I not say? in the lake of +blood which fills the whole cavity of the body. Well, then, the chyle +has only to penetrate through these coats, to go where it is wanted. +Hence it is not at all surprising that this blood should be white; and I +have very good reasons just now for comparing it to our _chyle_. It is, +indeed, chyle arriving directly from the place of its manufacture, +without undergoing any other process; by which you may see that this +little machine (of the digestive organs of the cockchafer), though +differing in appearance so entirely from our own, is reducible to the +same elements of construction, and that life is maintained by the same +process as with us; namely, by the action of the air upon the albumen +extracted from food. The cockchafer, it is true, is much further removed +from being a fellow-creature of ours than even the horse; but the +principle of life is the same with him as with us. And this is quite +enough to cause children, who can feel and reason, to think twice before +they begin to torture, by way of amusement, a creature whose life the +God of goodness has subjected to the same conditions as our own. I speak +this to those miserable little executioners who make toys of suffering +animals: but the case is different with agriculturists, who have +necessarily to contend with the devourers of their harvests, and whom, +I admit, it would not be reasonable to bind down by the maxim of Uncle +Toby. + +[Footnote: I have introduced my Uncle Toby, who really has nothing +to do here, in order to make you acquainted with a few lines of Sterne, +which I wish I could place before the eyes of every child in the world. + +"Go!" said he, one day at table, to an enormous fly which had been +buzzing around his nose and had cruelly tormented him all dinner time. +After many attempts, he finally caught him in his hand. "Go! I will +not do thee any harm," said my Uncle Toby, rising and crossing the +room with the fly in his hand; "I would not hurt a hair of your head. +Go!" said he, opening the window and his hand at the same moment, to +let the fly escape; "go, poor little devil; away with you; why should +I do you any harm? the world is certainly large enough to contain both +of us!"] + +But now to finish with the cockchafer. We have got to examine one very +important part of his body, that which in other animals has been the +one most talked about ever since we began our study: I mean the mouth. +You know that this is the essentially variable point in the digestive +tube; so that you will not be much surprised, should we find he has +something altogether new. The mouth of the cockchafer is composed of +a great number of small pieces placed externally round the entrance +to the _alimentary canal_; but the names of these, as they would +not interest you, I will not enter upon with you; more especially as +they refer to such tiny morsels, that you would have great difficulty +in finding them again on the owner. Of these pieces only two are worth +our attention. These are two bits of extremely hard horn, placed one +on each side of the animal, which are called "_mandibles_" and +which serve the cockchafer to cut up the leaves which he eats. Fancy +your share of teeth being two huge things fixed in the two corners of +your mouth, each advancing alone against the other till they meet under +the nose! You would then attack your tarts with the weapons of the +cockchafer! You would not, however, be able to bite them straight +through from the top to the bottom, as is done by all the animals whom +we have yet seen. It is this which so peculiarly distinguishes the +insect's manner of feeding; for we have already been taught by the +bird and the tortoise, that it is possible to eat with two pieces of +horn. The cockchafer now shows us how to eat sideways; but this is +merely an accessory detail. It does not affect what happens after the +mouthful is swallowed. All insects, however, have not this peculiarity. +The cockchafer belongs to the category of grinding insects as they are +called, who bite their food: but there is the category of the sucking +insects (or suckers), whose food consists of liquids; and these insects +are furnished in a different manner. + +In the innocent butterfly, who lives on the juice of flowers, the +digestive tube terminates externally in a sort of _trunk,_ twisted +in several convolutions, which is nothing more than an exaggerated +elongation of the two jaws, which become hollow within, and form a +tube when joined together. When the insect alights on a flower, he +suddenly unrolls this trunk, and sucks in the juices from the depth +of its "corolla," as you would drink up liquid with a straw from the +bottom of a small vial. Amuse yourself some summer's day by watching +a butterfly in his labors amongst the flowers: sometimes he stops +still, but oftener he is contented to hover over them; and, as he does +so, you will see a little loose thread, as it were, move backwards and +forwards as fast as possible: this is his trunk, which he darts out, +while flying, into the corolla of the flowers, but which scarcely seems +to touch them, so delicate is its approach. + +Less inoffensive far is the trunk of the mosquito-gnat, and of all the +detestable troop of blood-sucking flies. It is always a tube; but this +tube is no longer a simple straw, but a sheath furnished with stilettos +of such exquisite delicacy and temper, that nothing is comparable to +them; and these, as they play up and down, pierce the skin of the +victim, like the lancets of the lamprey, and, like them, draw in blood +as they retreat. + +Finally, amongst the _parasites,_ the last and lowest group of +insects, the stiletto-sheath is reduced to the size of a kind of little +tube-shaped beak, which, when not in use, folds down like the fangs +of the rattlesnake. + +You do not know, perhaps, what a parasite is. The word comes from the +Greek, and signifies literally, "_that which moves round the +corn._" The Greeks applied it to those shameless paupers who, to +escape honest labor, made their way into the houses of the great, and +enjoyed themselves at their expense. These parasites are little animals +which settle themselves on large ones, to suck in, without having +worked for it, the blood which the others have manufactured. The wolf +hunts, fights, and tears its victim in pieces; and then, by means of +that interior labor which I have spent so much time in describing, +transforms it into nourishing liquid: and when all this is accomplished, +the little flea, who lives hidden among his hairs, coolly draws out +for his own use the valuable blood obtained with so much effort. There +are many parasites in the world, my dear child--yourself, for instance, +to begin with--who are perfectly happy to chew your bread without +asking where the corn comes from which made it. But you have heart +enough to see plainly that this indifference ought not to last, and +that it is not honorable to go on living in this indefinite manner at +other people's cost only. + +You will some day have duties to fulfil, which you should accustom +yourself to think of now, in order that you may prepare yourself for +them beforehand, so that it may never hereafter be said of you that +you passed through the midst of human society, taking from it all you +needed, without giving it back anything in return, I advise you to +conjure up this idea when the time comes to leave off playing and begin +preparing to be of use. The sort of thing is not always very amusing, +I admit, but you must look upon it as the ladder by which you will be +enabled to rise from the degradation of a parasitical life. If you +were in a well, and some one were to let down a real ladder for you +to get up by, I do not think you would complain of the difficulty of +using it. It is for you, then, to consider whether you would like to +remain for ever in your present condition; for those who learn nothing, +who _submit_ to nothing, who are good for nothing, but to show +off and amuse themselves--these remain parasites all their lives in +reality, however little they may sometimes seem to suspect it. + +At your age, however, there is still no disgrace in the matter. God +shows us by the insects that little things are allowed to be +parasitical; but on this subject I must return to a point in the history +of animals which I touched upon before. I told you, in speaking of the +crocodile, that the perfect state of the inferior animals is found +represented in the infancy or less perfect state of those above them: +and I may say the same again with regard to insects. All the young of +the mammalia begin life as parasites, at least, as sucking animals: +for they all live at first on their mother's milk, which is nothing +more than blood in a peculiar state. But the name of parasite among +insects is generally confined to those which take up their abode on +the bodies of their hosts; though in common justice it might equally +well be applied to the gnat and his relations, who, when once full, +make their bow and are off, like the kitten when he has finished +sucking. Well, without meaning to find fault, if we descend to the +lower ranks of the mammals, we shall find among them many parasites +in the received sense of the word. You remember the pouch to which the +marsupials owe their odd name. The young kangaroo remains hidden for +months in the pouch of its mother, feeding continually all the time; +and it is then a strict parasite. During the four following months it +goes in and out, and strolls about between meals, like other young +ones of its class, and is then an animal at nurse affording thus a +twofold example of the tendency of the great Creator to repeat Himself +in His conceptions, here using for the infancy of the mammal the system +invented for adult insects--elsewhere repeating the butterfly in the +humming-bird, who may fairly be called a vertebrated butterfly, and +reproducing the gnat in the vampire-bat, which I look upon as an +enlarged and perfected revise of the original pattern, whence comes +the scourge of our sweet summer nights. + +And now, surely, I have said enough about these parasites, whose very +name, I suspect, will make you shudder after my impertinent application +of it. Never mind: it depends entirely upon yourself to get rid of +whatever you find humiliating in the position I have hinted at. Do all +you can to bring happiness to the parents on whom you live at present, +and who give their life-blood so willingly for your good. God has made +you very different from those little animals who have neither heart +nor reason to guide them. Do not be like them, then, in conduct. By +a little obedience and love--child as you are--you can pay them back +what you owe, and they will never complain of the bargain. + + + +LETTER XXXVIII. + +CRUSTACEA--MOLLUSCA. (_Crustaceans and Mollusks._) + +_Crustaceans._ + +Crustaceans consist of cray-fish, crabs, lobsters, and prawns, who may +be considered cousins-german of insects, among which more than one +naturalist has thought they ought to be placed. Like them they are +divided into _grinders_, having the same action of the mandibles; +and _suckers_, who are also parasites, and have tubular sheaths +containing stilettos. Mammals and birds are the victims of parasitical +insects; fishes have been reserved for the crustaceans, who do not +disdain also to fasten upon their humble neighbors, the mollusks; and +even among themselves the little ones settle down on the great. A few +live on land, but an immense majority in water, and seem destined to +represent, in the aquatic world, the aerial class of insects, from +whom, however, they differ in many ways. + +The first difference is in that stony crust with which they are +enveloped, like the cockchafer in his horny cuirass, and which you +must know well enough if you have ever eaten lobster. Wherever we meet +with horn in insects, we find stone in crustaceans. The jaws are stony, +and the teeth of the stomach also. They are constructed on the same +plan, only the materials are changed. + +The digestive tube is less complicated, and consists merely of one +large stomach, instead of that series of stomachs by which insects +approach the organisation of birds. On the other hand, if among some +of them the liver is reduced to simple tubes, floating loosely in the +body, as we have just seen it in the cockchafer among insects, these +tubes are generally so profusely multiplied, and press so closely +against each other, that they form a large compact lump--a true liver, +to sum up all--from which issues, as from ours, a _choledochian +canal_, a bile duct, _i. e._, which passes out into the intestine at the +entrance of the pylorus. + +You recollect that canal of the liver which I was afraid to tell you +the name of because it was so ugly? Well, this is that formidable name! +Now that you have swallowed so many others, you must be strong enough +to digest this. + +No chyliferous vessels have been found in crustaceans, whence one may +conclude that the chyle leaves the intestine by oozing from it, just +as it does in insects. There it gives rise to an almost transparent +sort of blood, a kind of sap, or lymph, which is put in motion by a +genuine circulation-apparatus; a real heart, with all its canals. This +heart has only one ventricle, and only sends blood in one direction, +as in the case of fishes; but there is an essential difference between +them, which we must point out. The heart of fishes may be called a +venous heart, since it only receives venous blood, which passes thence +to the gills, while that of crustaceans is an arterial heart. It +receives the blood directly it leaves the respiratory organ, and sends +it, not into one aorta, but into several arteries, which set out at +once, each in its own direction, to nourish the various quarters of +the body. This greatly resembles the system of circulation, with which +we are already acquainted. The veins only are unsatisfactory. They +form a kind of transition between the uncertain currents which convey +the blood of insects from one end to the other of the cavity in which +these strange organs lie bathed, and the closed canals of the higher +animals. But they are not canals, properly speaking. The irregular +intervals which separate the organs, more numerous here, are enclosed +by membranes, between which the venous blood pours, and naturally the +chyle also. The whole thus arrives at certain excavations formed at +the place where the legs are jointed on to the body--reservoirs, so +to speak--where the real canals come to carry it off and convey it +away into the gills. + +It is, in fact, by means of gills that crustaceans breathe in their +character of aquatic animals. These gills are made nearly upon the +same model as we have already seen in those of fishes; and although +their form and arrangement differ in different species, yet the +principle is always the same: they are tufts of leaflets springing +from stems, up and down which run two tubes; one which brings the blood +from the venous reservoirs, the other which carries it to the heart. +Crabs, lobsters, and crayfish, who are the "file-leaders" of the +crustacean tribe, have gills enclosed in the body, as fishes have; but +the circulation of the water goes in a contrary direction to theirs, +as does that of the blood. Instead of entering at the mouth and going +out at the sides, as we have seen, it enters at the edge of the bony +shell which covers over the body and comes out near the mouth--a merely +accidental detail which does not in any way alter the play of the +apparatus. All these animals are equally adapted for swimming and for +walking, crabs especially, their gills accommodating themselves without +difficulty to contact with the outer air, as we have seen among certain +fishes; so that one might class them with amphibians. There is even one +crab who has acquired the name of _land-crab_, because, although he has +got gills, he dies in water, the small amount of air he can get out of +it at a time being insufficient for him, and who, therefore, lives +constantly on land. It is true that he seeks out damp spots, for his +gills would also fail him if they became parched, and, like the fishes +who make excursions on dry land, he is provided with an internal +reservoir, which is always filled with a certain quantity of water. + +Some aquatic crustaceans have the labor simplified by external gills, +which hang down into the water, sometimes depending from the stomach, +sometimes from the legs. In France you sometimes see at a table certain +little animals, very like shrimps (_squillae_), the bases of whose +hinder legs are fringed by slender tufts, which are in fact their +gills. They find themselves placed there just within reach of the +venous blood; for in the body opposite the bases of the legs are little +cavities in which it accumulates. Now these gills can only act when +under water, and so the squillae dies as soon as he is removed from +that protecting element. For the same reason they cannot be kept long, +nor travel far, much to the regret of those who like them and live at +some distance from the sea. + +There are other crustaceans, next-door neighbors of the squilla, whose +gills are still more simplified. Here the legs themselves are turned +into extremely thin plates, which play the part of gills, and are thus +organs for two purposes, serving at the same time to swim and breathe +with. + +We have in our house one little crustacean, the only one I know of who +associates with men, and that is the wood-louse. You must know the +little grizzly beast, which rolls itself up into a ball whenever it +thinks itself in danger, and who would be taken for an insect by anyone +who was not taught otherwise. The wood-louse has neither gills hanging +down outside, nor anything inside her body which resembles the breathing +apparatus of her great relations. But, on examining her closely, you +will perceive all along her stomach a series of little plates, which +are her breathing-organs, and which come under the class of gills, +because, like other gills, they require a certain degree of moisture +to make them act properly. You will never, therefore, see a wood-louse +strutting about in the sunshine, where he would dry up far too quickly; +but if ever you get into a dark, damp corner, there you have every +chance of finding one. + +Animals who breathe through their legs and through their stomachs! You +are astonished, and ask, What are we coming to? What would you say, +then, if I were to go really to the depths of the crustacean world? +We should find there such extraordinary beings as you can form no +notion of, for they all live down below in the sea, and have no special +breathing-organ at all, inasmuch as they breathe through the whole +surface of the body. Do not exclaim yet! I will soon show you one whom +you know perfectly well, and who has no other way of breathing. + +But we must keep to the higher crustaceans, if we want to judge of the +class. By going too low, we run the risk of not seeing clearly. Animal +creation is here on a system of experiments: and they are so endlessly +multiplied, and exhibit such a profusion both of deceptive resemblances, +and of differences which disappear by transformations, that +classification no longer knows which way to turn. Worms, crustaceans, +mollusks; to which group do these and those belong? To which ever we +like to refer them, for these groups represent nothing definitely +determined in the plan of creation; and though easy to be distinguished +from each other in the higher branches, they become confused together +in the lower, like mountain summits which spring from a common base, +at the foot of which they are all united together. + +On this account, my dear child, you will, I am sure, excuse me now and +henceforth, from entering into details of all the horrible beasts which +swarm in the shallows of the animal world, and whom learned men have +in their wonderful wisdom muffled up in terrible names, in order to +prevent children from coming near them! What would you have thought +of the poor little squilla, so prettily baptised by the fishermen, if +I had taught you that it belonged to the order of _Stomatopoda_? +You will scarcely be able to pronounce the word; but that is no fault +of mine, it is spelt so. + +We will content ourselves, then, with having taken a glance at the +most clearly marked individuals; and as I said to you just now, it is +by them that we will arrange our inventory of the groups. Here, as you +may have already remarked, instead of continuing to wander from the +original model whose gradual deterioration we have been following all +this time from one class to another, it would seem that we are retracing +our steps, and regaining some portion of the lost ground. This is +because insects, as I have already stated, are an exceptional case--an +idea apart from the great general plan--a by-lane turning off from one +side of the great line of animal creation. + +The crustacean, less perfectly worked out than the insect assuredly, +but more regular, forms, so to speak, the connecting line between that +tiny masterpiece of fancy, so incomplete in its exquisite organisation, +and the shapeless but better constituted lump of the mollusk, who +conceals under his heavy shell the sacred deposit of real organs, those +which we expect to find always and everywhere. An insect outside, +though less refined it is true, a mollusk within, the crustacean reminds +me of what among us is called an _amateur_--that mild lover of +the arts who holds a middle place, as it were, between the artist and +the common citizen. + +I regret that you are not at present quite able to appreciate my +comparison fully: but put it by, in reserve, if possible, in your +memory; you will find out hereafter how just it is, and it will, +perhaps, help to prevent you from always setting the lively, noisy +artist, above the quiet and silent citizen. Let this, however, be +between you and me. If they could hear us talking, neither artist nor +citizen would forgive me, and the amateur still less. + +_Mollusks._ + +There is one mollusk universally well known--namely, the oyster--so +we will choose him for discussion. To look on one's plate at that +little mass of soft, compact substance, one feels inclined to ask what +there can possibly be in common between it and us; and if you were to +declare that there was not the faintest trace of resemblance between +the organization of the oyster and our own, I should not be surprised. +Wiser people than you have been caught tripping there; not that they +were ignorant of the points in which the oyster resembled us, but they +paid no attention to them. Viewing it in other respects, they declared +that it was of a structure completely different to our own; and that, +in the construction of this machine, the Creator had worked upon a +particular plan, laid aside afterwards as useless for any other purpose. + +I should like to get hold of one of those Academicians, with thirty-six +plans, and confound him before you, in proof of his relationship to +the oyster, by showing you at one sitting that there is an oyster in +himself; nay, further, that he is nothing but an oyster, revised, +amended, and considerably enlarged. And do not imagine that I am only +using a figure of speech here, as the professors of rhetoric call it; +which would be in bad taste: I am speaking literally, and to prove the +existence of the oyster in question in our Academician, I shall only +ask permission to perform a slight operation upon him. You exclaim at +this; but do not alarm yourself, for it is only an operation on paper, +he will not die from it. See now, I cut off his head, his two arms, +and his legs; I take out of his body the vertebral column and the ribs; +I gently place what remains between two shells; and ... there is my +oyster. I willingly admit that it is more carefully elaborated and +richer in details than its sisters in the oyster beds; but all the +principal organs are to be found in them also, and they positively are +beings of a similar construction: you shall judge for yourself. + +The mouth--for there is a mouth, though one must look closer than the +oystermen do to discover it--the mouth is exactly what the gullet +(oesophagus) would be in a man whose head had been cut off; that is, +a truncated tube. Then comes the stomach, situated in the very midst +of the liver; which latter may easily be distinguished, even by the +most cursory glance at luncheon, from its dark color. The intestine +also goes right through the liver, doubling backwards and forwards +several times: and thus the digestive tube supplies itself with bile +from the cask (to borrow a commercial expression); and this saves the +expense of a bile-duct (choledochian canal), which would be an +unnecessary mode of conveyance in this case. The animal lives in water; +consequently, instead of lungs he has gills: [Footnote: The land-snail +has lungs.] these are those thin, finely-streaked plates which make +a fringe at the very edge of the shell. Finally, on leaving the gills +the blood is received by an arterial heart, with only one ventricle +like that of the crustaceans, in the shape of a small pear, similar +to ours, having an auricle, and an aorta, branching out so as to +distribute the blood throughout the whole body. And now what do we +find here, let me ask you, in this mutilated man, reduced to the soft +portions of the trunk, whom I have been imagining? A heart, with its +arteries; lungs; a liver; an intestine; a stomach and an oesophagus: +that is to say, merely and simply the organs of nutrition. That is +all, or very nearly so. + +As you perceive, then, all the elements of our own feeding-machine lie +between the two shells of a mollusk; in a rough state as yet, it is +true; incomplete, and unruly; as in the case of the intestine, for +instance, which in many of these creatures passes without ceremony +through the heart: but even so they are quite sufficiently indicated +to prevent their being mistaken. Now this machine, it is in vain to +deny it, is the animal itself; but it lives at first, and it is this +which dies in it last. The other matter (the locomotive power), +important as it may seem to us in higher races, only holds a secondary +position in reality: the proof of which is, that here is an animal +reduced absolutely to a mere feeding-machine, who still lives, whilst +there yet remains to be found one who has nothing left but his +movement-machine, and who can yet exist. We cannot disown this primitive +animal, for we have it within ourselves; lost, so to speak, in the +midst of the accessory organs which are successively added to it in +proportion as we rise in the animal scale, but still preserving its +own life, its personality, if I may use the expression. Listen to this, +for here is a history well worth hearing. + +I will explain to you, hereafter, how all the actions of the +movement-machine are performed by means of a network of nervous threads +(filaments), whose centre of impulsion is in the brain. How our will +acts upon the brain, and gives its orders to the muscles through the +nervous fibres, I will not offer to explain: it is a fact, let that +suffice us. You say to your foot, "Forward!" and off it starts; "Halt!" +and it stops. Here is an organ under command, a servant of the brain, +where we rule ourselves: with or without explanation, no one will ever +dispute this. The oyster, who has neither head nor brain, has, as his +only instrument of action, certain little masses of nervous substance +scattered right and left, which are called _ganglions_. These +communicate with each other and with the organs by nervous cords, which +are interlaced in all directions, without having any common centre, +and which give the impetus to all parts of the animal. + +Well, the human oyster presents to us exactly the same nervous +organisation. It has its ganglions and its nerves to itself, which are +put into communication with the brain by some threads strayed among +his own, but which are not under its orders, and which treat with it +on equal terms. You remember, perhaps, the little republic talked about +when we first entered the digestive tube; you have now the explanation +of it. This republic is the original animal; it is the feeding-machine. +I cannot describe it, and the kingdom of which you are queen, better +than by comparing them to two States having diplomatic relations with +each other, who exchange dispatches and reciprocal influences; and as +to the importance of these respective influences, if one were to compare +them I scarcely know to which side the balance could incline. + +We shall return elsewhere to this detail, one of the most interesting +of our organisation, and which here finds its natural explanation. For +the present I will content myself with reminding you that, since the +earliest days of human civilisation, all philosophers, all poets, and +all moralists, whether sacred or profane, have borne witness to that +double life within us, that inward being, blind and deaf, whose +disordered impulses so often carry trouble into those higher regions +where will and reason sit enthroned. Behold him taken in his lair at +last, this mysterious being. I have just unveiled his origin to you. +And here, dear child, I must shelter myself behind a profession of +faith. There will not be wanting people to tell you that it is degrading +man far too much to look so low for the sources of his organisation, +and that this sentence--_the human oyster_--which expresses my +idea so well, is neither more nor less than blasphemy. Let them talk, +but adopt their opinion only when they have proved to you that man had +a special Creator, and that the oyster came from a different hand from +ourselves. I should like to know with what face we could venture to +complain, poor worms that we are, because it has seemed good to our +common Father to carry forward in us his previous creations, and in +what respect human dignity would suffer from this contact with a being +who, like us, is one of the works of God. That human pride may suffer +thereby, I admit, and I am glad it should; but if God has included all +creation in His love, we may well include it all in our respect. Whence +comes our superiority at all, but from the gratuitous gifts of Him who +has made us what we are? Is it to lose it, then, to find ourselves +side by side with inferiors whom the Divine benevolence has visited +like ourselves? Surely not. But enough of the oyster, who has never, +that I am aware of, heard such strange discussions sounding in his +ears before. I have no time nor courage now to speak of the other +mollusks, who offer more or less the same system of organs which I +have just described. I must hasten on to the Worms, who give us the +last clue to the great enigma of the animal machine. + + + +LETTER XXXIX. + +VERMES--ZOOPHYTA. (_Worms and Zoophytes_). + +_Worms._ + +The worm of worms, the one you know best, is the earthworm: so he shall +have the honor of representing his group. + +He will not take much time to describe. He is, in brief, a tube, open +at both ends, so as to allow food to come in and go out. That is all. + +I talked to you before about the ruminants, those food-manufacturers +who are employed in cooking victuals for the stomach, and in disengaging +albumen from the coarse materials among which it is apparently lost, +so as to give it out again in a more acceptable form. The ruminant has +other workmen under him, whom I keep in store for you as the last of +the eaters, and who prepare the raw material for him*. These are the +vegetables, who seek out the elements of albumen in earth, water, and +air, those final sources of all alimentation. The earthworm also is +a _preparer_, but in a peculiar way. Look along the garden-walks +in summer-time, after rainy weather: you will see here and there, +little heaps of earth moulded into small sticks, like dough which has +been passed through a tube. [Footnote: M. Mace's account of the +earthworm's life seems founded on the assumption that it extracts its +nourishment from the earth itself, i.e., from inorganic matter, as +_vegetables_ do, to use his own words. But this notion is so +entirely at variance with present received opinions, and also with the +fact that the animal possesses a gizzard for digesting, as well as an +intestinal canal, that it has been necessary to make considerable +alterations in the description. To dismiss his theory of the primitive +animal, etc., altogether, was, however, impossible, without omitting +the whole chapter; but as young heads are not likely to trouble +themselves about it, and it is very innocent in itself, it will do no +harm; subject to this warning, that M. Mace has taken the earthworm +for a more simply organised creature than it really is.--TR.] This is +the damp soil which the worm has passed through his tube, after +extracting from it, during its passage, the various elements of +fertility he requires for the support of his life. This is what makes +him so particularly fond of garden soil, because it is richer in animal +and vegetable matter than common earth, and proves therefore more +nourishing food. The worm, then, feeds on the fat of the earth, which +he converts into azotic aliment for the use of moles, hens and Chinese. +It only figures, it is true, for want of something better, in Chinese +cookery, so profusely hospitable for all that; but the hen doats upon +it, and you do not despise it yourself when it comes back to you in +the form of a chicken's wing, that second transformation of the matter +of which the soil of your garden is composed. It is told of certain +savage tribes, the victims of constant scarcity, that they swallow +little balls of clay in order to keep down their hunger; and during +the great famines in India the distracted inhabitants may, we are told, +be seen digging up the banks of the rivers to feed on the fertile clay +in which the splendid vegetation of their country is developed. This +is a desperate trial of that primeval system of alimentation which +answers perfectly with the worm, but becomes a cruel mockery in the +case of an organisation as exacting as that of man. Let us examine a +little more closely, then, this wonderful tube. + +At first sight one notices, to begin with, that it is composed of +perfectly distinct rings, all quite alike. Inside as well as out each +of these rings is an exact repetition of the other. They are all formed +of circular muscles, enclosed between two coats, which extend from one +to the other. A series of ganglions, arranged in the form of a necklace +along the whole length of the body, set in motion the muscular system +of the rings, each of which possesses its local centre of impulsion. +Each feeds itself in its place from the nourishing juices with which +it is in contact, the interior coat enjoying the double property of +distilling digestive juices and absorbing digested ones. These juices +pass through the muscular partition, and proceed to bathe the outer +coat, which plays, at the same time, the part of coat and lung, and +affords a passage to the air through its soft, damp surface, like that +of gills. From all this results a fine red blood, such as we have not +met with since we left the reptiles, and which is manufactured in all +parts of the body at once. + +Each of these rings, then, the worm's only organs, is a little eating +machine to and for itself, and at the same time a little movement +machine also; in fact, a complete animal. Each one could, if necessary, +nourish itself and live apart; and this is what he really does. Learn +hence, to despise nothing in nature. One tramples an earthworm under +foot, and there below one's heel lies a little revealer of secrets, +whose organisation throws the most unexpected light upon one of the +greatest mysteries in our own life. + +I said to you before, and I felt at the time that it was rather beyond +you, that "each one of our organs is a distinct being, which has its +particular nature and special office, its separate life consequently; +and our individual life is the sum total of all these lesser lives, +independent one of the other, but which nevertheless blend together, +by a mysterious combination, into one common life, which is diffused +everywhere, but can be apprehended nowhere in particular." + +The study of the worm admirably explains this out-of-the-way sentence. +And here observe my adjective--my out-of-the-way--for it is a case in +point. We may call it a literary worm; a worm of four rings, each +perfect in itself, but yet compounded together into a whole with its +own idea. + +That which makes this idea of life most difficult to comprehend is, +that one cannot prove it by a direct experiment, since there is not +one of our organs which could exist separately from the others. Although +independent in their special action, yet these multiplied lives are +nevertheless in a state of absolute and mutual dependence, from the +imperative need they have of each other to make them act, each having +for its share only one particular function, the effect of which extends +to all the others. This is called the division of labor; and if you +still do not understand me clearly, I will explain it in another way. +The heart sends to all the organs--does it not?--the blood, without +which they could not live: separated from the heart, the lungs would +die immediately. It is to the lungs the blood goes to find the air, +without which it could not maintain life. Separated from the lungs, +the heart would die immediately. There is nothing belonging to us which +can avoid the inexorable requirements of blood and air; +consequently, there is nothing which can live an isolated life. + +I will borrow a simile from human society which you will understand +at once. In civilised countries, where division of labor is established, +the tailor makes clothes, the mason makes houses, and the baker makes +bread. If you could throw them each alone by himself into a wood, the +mason would not be able to dress himself, the baker would sleep in the +open air, and the tailor would not know how to make bread. Or rather, +as not one of them can carry on his trade without the co-operation of +a multitude of hands, they could none of them do anything at all. Each +completely independent in his work, yet each dependent upon the others, +both for living, and even for being able to work, our workmen can only +act when they remain bound in close union with the vast society of +which they form a part; and our organs--those other laborers whom you +have seen working for so long--our organs are just in the same +predicament. But in the primitive societies, among savage tribes, where +each man can make his clothes, his house, his bread (when he has any), +and everything else for himself, you might take such an individual if +you liked, and separate him from the rest of the tribe, and he would +go on living as before. And so with the rings of the worm, that +primitive society of organs. Each of them is a universal workman, who +knows how to make everything. Separate him from his fellows, it will +not disturb him at all, and he will go on living as if nothing was +thematter. + +I still remember some profound reflections I indulged in one day some +years ago whilst leaning on my spade and looking at a worm that I had +just cut in two, and whose two halves were walking off one on each +side. + +"There was only one creature here just now," I said to myself, "and +now there are two! Have I had power, then, to create one with a stroke +of the spade?" + +I had not then got hold of the key which I now give you, and to which +no possible objection can be raised. If there are two beings after the +stroke of the spade it is because there were two before. Nay, there +were even many more, if we may trust to the "Manual of Zoology" by +Milne Edwards, a very good book, excellent for an old scholar like +myself, and which I have found very useful in my country-home, as it +has enabled me to relate to you one after another the mysterious wonders +of life. + +He says that, "if one cuts an earthworm across into two, three, ten, +or even twenty morsels, each of these morsels will go on living in the +same way as the whole, and will form a new individual." + +Twenty! that seems to me a great many, because, as far as I can trust +to my brief observations as a gardener, it is necessary that some of +the rings should remain united together and afford each other mutual +support, in order to succeed in repairing the bleeding breaches; but +I would much rather believe it than try the operation. My mind is easy +when I am defending the plants that I have sown in my garden from the +gluttonous worm who would rob them of their food; but it would not be +so if I were cutting them up on my table to learn something about them. + +Besides, there is no need of an operation to convince oneself of the +particular life of each ring. There is one worm, well known by name +at least, though happily not to be met with every day, and that is the +tape-worm, who establishes himself in the intestine of man, and lives +on the chyme, as the other worm does on garden-mould. They call him +the _Solitary_ worm in France; and if ever one might suppose a +creature appropriately named, it would surely be him; for certainly +there is not much society to be looked for in the dwelling he chooses +for himself! But it happens that this pretended _solitary_ worm, +with his unlimited chain of rings, is only a long row of perfectly +distinct beings, so distinct indeed that, from time to time, some of +the rings let themselves go, fall off like ripe fruit, and go away to +live elsewhere, ready to become the nucleus of a new set, if a happy +accident carries them into another intestine, the only place favorable +to their development. + +At last, then, here is a corner of the curtain raised; here we see the +associated organs which constitute an animal, living for once a life +positively and in all respects their own. We are now satisfied about +this; and when at another time we find them bound together in the +chains of a union too ingenious to be severed with impunity--which we +shall discover by seeing their action stop at the moment of separation-- +we shall know the cause. + +Do not think, my dear child, that a wretched earthworm can prove nothing +as regards other creatures. The worm is the starting-point of all the +organisations which come after him. Of what is he composed? Of a +tubewhich is itself composed of rings. Well, it is upon this very tube +that the whole animal machine has been founded: and these rings, as +they expand and modify themselves in a thousand different ways, give +birth to all those varieties of being which drive classifiers to +despair, because they will not understand that there ought only to be +one animal, since there is only one Creator of animals. Now, this +animal is a digestive tube served by organs; it is a worm, _i.e.,_ +which goes on constantly embellishing itself. I said to you long ago, +and at a time when you scarcely knew anything, "Have you ever observed +a worm or a leech in motion? You see a successive swelling up of the +whole surface of its body as the creature gradually pushes forward, +as if there was something in its inside rolling along from the tail +to the head. Such is precisely the appearance which the oesophagus +would present to you as the food passes down it, if you had the +opportunity of seeing it in action; and this has been called the +_vermicular_ movement, in consequence of its resemblance to the +movement of a worm." + +And afterwards, in speaking of the intestine: + +"If your body were made of glass, so that you could look through it +to watch the intestine at work, it would appear to you like an enormous +worm, coiled up into a bundle, heaving and moving with all its rings +at once." + +You have now got hold of the secret, namely, that from the beginning +to the end of the digestive tube, its movements are those of a worm. +What a wonder! and that the worm is a digestive tube which can walk. +This worm, or this tube, whichever you please to call it, has never +ceased crawling under our eyes since we began this study. Lost sight +of in man in the midst of the riches he has picked up on his road, +invisible and coiled backward and forward in his palace like an Eastern +despot who leaves everything to be done by his slaves; behold him here +in his first stage naked, shivering in the air, forced to go off himself +and alone to his pasture--ground! But in the coarse earth with which +he fills himself I can already see the delicate chyme which his numerous +servants will prepare for him later on, and into which the heart-tree +will one day send down its roots--the chyliferous vessels. + +A short time ago I called the oyster the primitive animal, but I was +in too great a hurry. The worm is the real primitive animal. He is to +be found in the oyster, as the oyster is to be found in us; and that +poor little beast is, by comparison, an animal of high pretension, who +would be shocked, I am sure, if he could understand what we are saying, +and heard us assert that he is nothing but an embellished worm. + +_Zoophytes._ + +Two centuries ago it was believed that below the worm, animal life, +properly so called, ceased, and the creatures whom I am about to +introduce you to were supposed to be animated plants rather than living +organisms. Hence their name was especially chosen to express that +double nature by which they were thought to have a share in two kingdoms +at one time--viz., the animal and vegetable--_zoon_ in Greek +meaning animal, and _phuton_ a plant. Zoophytes were set down as +animal plants. + +And although later discoveries have long ago established the fact of +the complete animality of zoophytes, the old name is still in general +use. But you must not let it deceive you. Zoophytes are animals every +inch of them, however low in the organic scale, and although many of +the compound ones imitate the growth of plants and shrubs so exactly +in their mode of spreading that it is only by the closest observation +we can persuade ourselves they do not belong to the vegetable kingdom. +Of these there are the delicate buff-colored, prettily-branched, horny +specimens found on the shore, which make so beautiful a variety in +seaweed pictures among the red and green colors of the real seaweed; +but of these also are those wonderful stony shrubs which grow on the +submerged rocks of islands in warm seas, and the material which you +know so well by the name of coral--the very coral of which the necklaces +and bracelets in the jeweller's window are composed. + +In all cases of compound zoophytes, however, there is one great point +which they have in common with the worm, viz., that there is an +association of distinct lives acting unanimously; or, rather, to the +same end. Plainly as this is seen in the worm, it is still more obvious +in the zoophyte. There is no need here either of cutting them up +yourself or of taking other people's dissecting operations upon trust. +It is enough to use your eyes, with the help, it is true, now and then, +of the microscope's clearer sight. + +You know the old oak-tree which stands on the outskirts of the wood, +and is called among the country folk _the patriarch_? Now, this +is clearly not an individual, but a nation. It is not a tree; it is +a forest. Nay, may I not call it a green field? For this trunk, so +truly venerable from ages of growth that one feels inclined to bow to +it as one goes by, is, in fact, a collection of structures, accumulated +by countless generations of fleeting herbs, _i.e.,_ leaves, not +one of which has lived for the space of a whole year round. Every +spring some thousands and thousands of buds open to the sun; each one, +therefore, affording a passage to a little green point; and this point +is an oak, who comes into the world, like the first oak, the grandfather +who formerly came forth from an acorn, under the form of an herb or +tender leaf, which a sheep might have browsed upon. Yet it is so +thoroughly an oak, that you have only to take out the bud carefully +before it has expanded and fasten it into another one's place upon a +tree of the same family, though of a different species, and it will +produce an oak of the same sort as its old companions, and which will, +as it progresses, look quite a stranger among the indigenous branches. +This is the secret of what the gardeners call _grafting_, and I +advise you to try the operation upon rose-trees, for nothing is more +amusing. When the autumnal frosts set in, all these troops of new +little oaks die, and deliver up their leaves to the wind; but they +leave behind, as their summer's work, a tiny morsel of new wood, upon +which, if you look carefully, you will see a fresh bud dawning--the +hope of the coming season. And thus the great life of the tree is +perpetuated from century to century by an uninterrupted succession of +transient lives, reminding one in all respects of the life of a nation; +and the similitude is complete in the evergreen trees, where the new +leaf makes its appearance before the old one has quitted the stem. + +And such is the life of the great stone trees and shrubs of various +kinds which grow under tropical seas, and whose makers and inhabitants +are the coral polyps, the undoubted heads of the Zoophyte race. + +But before considering the _polypidom,_ or external dwelling +(otherwise called the _coeneciun,_ or "common house"), you must +learn something of its originator, the little _polyp,_ who lives +inside, and belongs to a family so widely spread over the face of the +earth, that there are scarcely any waters, whether salt or fresh, +without them. + +In your own neighborhood, if you know how to look for them, are to be +found on the banks of ponds, or along the borders of streams which lie +sleeping in roadside ditches, extraordinary beings which, a hundred +years and more ago, completely bewildered the good Dutch naturalist +Trembley, who had taken it into his head to study them. Picture to +yourself some very tiny bags made of a kind of jelly; gray, brown, or, +most commonly of all, green in color, always transparent, and fastened +by their base to the stalks of _carex,_ water-lentils, or the +confervas, which grow in still water. A hunter on the watch, this bag +shoots out on all sides a number of slender threads, like so many +whip-lashes, arranged within a circle round the edge of its opening +or mouth; and with these whip-lashes all the animalcules which come +within reach are entwined, stifled, and carried away to the ever-yawning +little gulf, where they are digested in less than no time. Whatever +will not digest comes out afterwards by the way it went in. Of what +becomes of the results of this digestion it is impossible to form an +idea. Were you to cut up the bag and put little morsels of it under +the best microscope possible, you would see positively nothing but +solid jelly, without the least sign of any organisation whatever. But +this is not all. Replace these morsels in the water, and come back +tolook at them at the end of five, twenty, or thirty hours. Each one of +them will have become a perfect bag, ready to multiply itself afresh +if you submit it to the same operation. Sometimes, on some part of the +original bag, there suddenly appears a little raised spot, like that +which came on your baby brother's arm the other day after he had been +vaccinated. What would you have said, if this ugly spot had grown +larger and larger without stopping; if it had assumed legs, arms, and +a head, and so become another baby, growing from the arm of the first +one? Yet this is just what the spots do which come on the bag I have +been telling you of; and people have come across bags of a larger +species still--between one and two inches in size, in fact--which in +this way carried twelve young ones on their backs, if one is allowed +to talk of stomachs having _backs_. You perceive at once that +this commencement of animal life is not even a digestive tube, and +that nothing in it can he found but a stomach, opening straight to the +air above and closed up below. + +It was Reaumur, the originator of the famous thermometer, who gave a +name to the wonderful bags discovered by Trembley. Aristotle had +previously bestowed the title of _polypus_ (many feet) upon a +mollusk outwardly formed upon a similar model [Footnote: This is the +cuttle-fish, called _polypus_ by old naturalists. We shall speak +of it fully hereafter in the history of the movement machine.] with +large whips disposed regularly in a circle round the mouth, and intended +for a similar use, only that they have another function besides; that +of carrying the body along in the capacity of feet by clinging on to +the rocks with their suckers as they go. Reaumur transferred this name +to the newcomers, and called them fresh-water polyps, to the infinite +amusement of Voltaire, who had declared that they were only blades of +grass; a new proof, among many others, that in natural history all the +intellect in the world is not worth a pair of good eyes. + +But it was soon found out that, in collecting these bits of living +jelly near the Hague, Trembley had laid his hands on little beings of +immense importance on the surface of the globe, and that he had +discovered under his microscope the explanation of a mystery which had +spread itself, setting human science at defiance, over some thousands +of square miles. + +I talked to you just now of the jeweller's coral, of which ornaments +so becoming to dark-haired people are made. That is one of the stony +polypidoms I spoke of as stone trees found at the bottom of the sea, +where it grows attached to the rocks in the form of a charming little +shrub, stretching its red branches in all directions. The Greeks, who +were never at a loss, relate that Perseus one day laid down upon the +sea-shore the famous head of Medusa, the sight of which had the property +of turning everything to stone, and that the nymphs, in sport, showed +it to the coral shrubs; a fact which explained everything quite +naturally. Without exactly holding this mythological explanation, +modern philosophers had not got much farther, and coral was still a +puzzle to them, which they were not fond of troubling themselves about; +till, roused by Trembley's revelations, they examined it more carefully, +and discovered in its soft extremities (hitherto unnoticed) those same +living jelly-bags or sacs, with their circlets of legs, or rather arms, +charged with supplying them with food. These were marine polyps, which +grow, like those in fresh water, one upon another, but each in its own +crusty cell; and like the buds of the oak, these buds of the stony +tree form each its special deposit, which it bequeaths in dying to the +general mass. In short, as the tender shoot of the oak is filled by +degrees with the wood which forms within it, and hardens into a branch, +that goes on increasing by perpetually new growths, so the jelly polyp +of the polypidom hardens below into stone and dies incessantly at the +base, while it lives on indefinitely above in its constantly-renewed +summit. + +Do not get tired of all this phantasmagoria, my dear pupil: it is a +matter of the highest interest. Here is the point of junction--the +bond, as it were, between the three kingdoms: an animal growing +vegetable-wise produces a mineral mass, extracted from the waters of +the sea by an infinity of little living crucibles, who carry on under +our eyes the work begun in the first ages of the globe, and quietly +manufacture continents for the use of future generations. This ought +to console you, my dear child, for being little. It is by little things +that God loves to effect what is truly great. He did not seek out the +elephant or the whale to form these worlds; He chose workmen no bigger +than a pin's head. I have spoken to you about jeweller's coral, which +is made into toys or presents for ladies to adorn themselves with; but +its brethren, the madrepores of the Pacific Ocean play a very different +part. They have formed in front of the shores of New Holland a barrier +of reefs three hundred leagues in extent and twenty wide. What are all +our buildings after this?--those pyramids and cathedrals which seem +so gigantic to us? This ever-increasing wave of coral polypidoms will +one day shut against navigators the entrance to one part of the sea's +tropical region; and lands not to be found on the map to-day will then +lie stretched out under the sun, covered with plants and animals; and +this in places where ships now plough the ocean. Know, also, that a +great portion of the soil which we tread under foot has no other origin. +It was manufactured formerly in the sea by infinite myriads of beings, +often infinitely small. Each one, whether polype or shell, produced +its grain of stone, and from all these grains God, who directed their +work, has made our country. + +But it is time to bring this chattering to a close, for it will never +end if I do not force myself to stop. I leave it with regret; but all +these paths through which I have threaded my way one after another +without counting them, have already made a volume which may possibly +be considered too large for you. There are many other zoophytes besides +the coral polypes, and all of them beautiful and curious. They all +inhabit the fertile depths of the waters where God has deposited the +first germs of life. I cannot describe them to you now. But to make +amends, I will give you a piece of advice which will perhaps make some +people stare. Ask your papa to lend you Michelet's book, _The Sea_, +and look there for what is said about the mysterious animals which lie +hid beneath the waves. His book was not written for you as this one +is: and if, in spite of all my good intentions, I have not always +succeeded in being as comprehensible as I meant to be, Michelet, who +never thought about little people when he took up his pen, will +certainly startle you now and then. But do not be disheartened by a +word. You will find there, that which will be forever plain to you, +the poesy of nature, and children comprehend that better than learned +men. + + + +LETTER XL. + +THE NOURISHMENT OF PLANTS. + +One more word before we part about the last of the eaters, about +Vegetables. They will furnish you with a new and very clearly marked +proof of the uniformity of the fundamental conditions to which the +Author of life has subjected all organised beings. + +Let us look once more at this oak, of whose manner of growth I was +obliged to give you a sketch beforehand, in order to show you the ties +which unite it with its immediate neighbors in the animal kingdom. How +does it feed? I need not tell you this. It feeds by its roots, which +suck up in the bosom of the earth the water charged with the juices +which form its nourishment. Are you aware that every large branch had +its subterranean fellow or representative, and that the annual shoot +at the top of the tree is reproduced at the base by fresh fibres, which +extend themselves in the soil of the earth, in proportion as their +sisters above make their way in the air? And thus, by means of organs +ever young, the life and progress of the great association is kept up, +while those members whose day of work is over still remain there as +the supports of the edifice. It is the same with human societies. They +are sustained by what is old, but they live and progress only by what +is young. The sap, then, which is the name given to the moisture or +water sucked in by the young roots, having once got into the cells of +which the tissue of the fibres is composed, passes from one to another, +and travels thus to the top of the tree, where it is wanted by the +leaves. + +There is no obvious machinery here, however, to impel it forward. It +journeys on of itself, as it were, under the action of laws which have +never been satisfactorily explained, but all of which are dependent +on the vital force or life-power of the tree, inasmuch as without it +there is no circulation. One agent, but by no means the principal, or +it would act as well in a dead tree as a living one, is _capillary +attraction_; and, if you wish to know what that is, you have only +to think of what happens to a towel, if you hang it upon a peg, and +leave the end of it soaking in water. Does not the "wet" seem to climb +up it thread by thread, till it is damp from one end to the other? A +little in this way--but these similes are very imperfect, and will not +bear close application--the sap rises in a tree, stealing up branch +by branch; and it is then called _ascending sap_. [Footnote: M. Mace +speaks of this sap as the _blood of the tree_, and of the leaves only as +_lungs_. These statements have been modified so as to meet the fact that +_ascending sap_ consists of, and conveys the raw elements of _food_ to, +the leaves; that in the leaves this food is _digested_, as well as +brought in contact with the air, and that it is thus converted into that +nourishing fluid, the _descending sap_, which certainly plays the part +of steward to the tree as our blood does to us, and therefore may now be +called the blood of the tree. It must be remembered, however, that each +tree has its own sort of steward, as the case of the _Euphorbia_ (quoted +afterwards) plainly shows. The analogy with the more general substance +of blood is therefore not very complete.-TR.] + +It arrives at last at the leaves, which it enters as our food enters +our stomachs, and for the same purpose; for in them takes place, as +in all true stomachs, that process of digestion by which the elements +of the crude sap-food are decomposed from their first condition, and +converted into a nourishing chyle; in each tree of a sort "after its +kind." + +But more than this. Like the outer coat of the earthworm, the coat of +the leaf affords a passage to air and moisture through its surface; +and here, therefore, takes place that mysterious exchange which is +everywhere the essential condition of life. Here is the charcoal-market +as before, only the bargainers have changed parts. The air, which in +the other case received the _carbon,_ delivers it up, now, and +receives oxygen in exchange; exactly the reverse of its traffic with +animals. In other words, the tree inhales through its leaves the +carbonic acid gas thrown into the atmosphere by our lungs. On its own +responsibility it breaks through the alliance between the carbon and +oxygen contracted in our organs; keeps the carbon for its own use, to +restore it to us another day under the form of wood, or, by the aid +of the charcoal-burner, in the pure and simple state of charcoal; and +sets at liberty the oxygen, which once more goes off in search of new +lungs and a fresh alliance. Thus a constant equilibrium is maintained +in the atmosphere; and thus, by a system of perpetual rotation or +everlasting merry-go-round, the same substances serve, indefinitely, +to support life of every opposite description. + +Now there are two things to be remembered in this inverted respiration +of vegetables. In the first place, it occurs only in the parts which +are _green_. Flowers, fruit, the root, and every part of any other +color, do as we do when we breathe; _i.e._ deprive the air of its +oxygen, charging it with carbonic acid instead. For which reason, +by-the-by, we ought not to keep flowers in a bedroom at night. Charming +as they are, they are _poisoners_, and a headache is what we may +fairly expect after sleeping shut in with them in the same room. It +is almost as bad to allow green boughs to remain there either, for, +in the dark, even the green parts cease to purify the air, and begin +like the others to manufacture carbonic acid, at the expense of course +of their carbon, which thus by degrees is used up. Now, as it is the +carbon which constitutes the solid fibres of plants and produces their +green color, they soon become yellow and limp when deprived of light. +You may, perhaps, have wondered why the gardener amused himself with +smothering his poor lettuces by tying them up at top like a knot of +"back hair," instead of letting them grow freely in the air and +sunshine. It is, my dear, to make them more tender and delicate for +you to eat; and those beautiful, crisp, yellow leaves, so delicious +to the tooth, would have been green and tough, had they not slowly and +quietly let out a great portion of their store of carbon in darkness +during the last few days, before being gathered. Even without playing +the gardener, you may assure yourself of this fact in a still more +simple manner. Put a flat board upon the lawn and leave it there for +three days; then take it up again, and you will find just where the +board has prevented the light from reaching the grass, a yellow mark +so distinctly traced as to be seen from the other end of the garden. + +But to return to the sap, which we left undergoing a change from air +and solar influences in the leaves. The ascending sap was to all +appearance only clear water. When it returns from the leaves, charged +with carbon, it is a thick juice having almost the consistency, and +sometimes even the color of milk, and is possessed of properties +altogether new. The most striking example that I can give you of +thedifference of the two states of sap is the Euphorbia of the Canary +Islands, whose digestive or descending sap is a violent poison. When +the natives of the country are accidentally pressed by thirst, they +carefully remove the bark in which the fatal juice circulates, and are +then able to refresh themselves safely by sucking the stem, which +yields only the watery sap sucked from the ground, and as yet unaltered +and harmless. + +Each of these two saps, in fact, has its path distinctly traced for +it: the first rises through the wood, the second descends through the +bark, whence it is called descending sap. If you wish to satisfy +yourself of this, fasten a rather tight knot of pack-thread round a +young branch, and after a time you will see it pine below the knot and +become swollen above it, an unanswerable proof that the nutritive +juices flowed downward through the bark; for the wood inside the branch +will have been uninjured by the strangling pressure. Remember this, +my dear, when you are playing in the garden, and do not injure the +bark of the young trees your father likes so much to see flourishing. +It is by the bark that they are nourished, and you might even kill +them by treating it too roughly. + +And now I must show you how the nutrition is carried on, or, if you +like better, how the tree grows by means of this descending sap. See: +here is a fir tree, which has just been cut down to the ground. Now, +if you like, I will tell you in a moment how old it is. I will even +tell you the age of every branch, little and big ones both, without +making a mistake in a single year; and you know as well as I do that +I am no conjuror. You see these small circles so delicately drawn, as +it were, upon the face of the sawn trunk, each wider than the last, +as if they were composed of a set of tubes, of unequal sizes, fitting +exactly into each other. Now count them; and you will perhaps find +twenty-five; and as each of these circles represents the work of one +year, you will know that the tree is twenty-five years old. In spring, +when the sap begins to move more briskly, it deposits everywhere between +the wood and the bark, from the trunk to the farthest boughs of the +tree, a uniform layer of a thick liquid, which moulds itself exactly +upon the wood already formed. This layer stiffens during the year; it +gets filled with the carbon left in it atom after atom, by each drop +of the descending sap as it goes by, and thus insensibly becoming +organised and hardened. When winter arrives to interrupt the work, it +will have formed two _ligneous, i.e._ woody layers, as they are +called. Of these, one belongs to the wood, and will never move again +so long as the tree lasts, for it will be covered over, and as it were +buried, by the successive layers yet to come; while, on the contrary, +the other (layer) belongs to the bark, and is doomed to find itself +perpetually forced outwards by the fresh layers, which will after a +while insinuate themselves between it and the wood. + +It is for this reason that the bark of old trunks of trees is so deeply +furrowed, and that the dry scales may be picked off the surface without +the slightest injury to the tree. It is part of the original bark, +dead long ago. The old wood also is dead inside, and even when it is +altogether gone, the glad youthful branches growing green in the +sunshine will scarcely find it out! This accounts for those oaks which +time has hollowed without destroying, as those of Allonville in +Normandy, in which mass is said, and which is moreover the greenest +tree in the country. But without going so far, who has not seen those +hollow old willows, sometimes pierced with holes letting in daylight, +yet proudly crowned above by a forest of young boughs, as green and +full of vigor as if the trunk were still in its prime? What was dead +has departed, but all that has life in it remains, and that is enough +for the tree. + +Need I add that the descending sap, this steward of the vegetable, has +also his workmen to supply with materials, as in our case, and that +he is always falling in on his road with organs, all of which want +different things from him? That here a flower has to be formed, there +a fruit, there a leaf, or a bit of wood, and so on: and that a +mysterious intelligence--the same that we have found everywhere +else--presides over all these varied constructions, the materials for +which are mixed together pell-mell, in the imperceptible thread of sap +which oozes from the leaf to the bark? I recollect just as I am about +to conclude, my dear child, that I once told you, you were a small +temple in which God perpetually attests His presence, by a permanent +miracle. You may now henceforth look upon a tree as something more +than a bit of wood, yielding a pleasant shade. God is in it also. + + +CONCLUSION. + +And now, my dear little pupil, to what conclusion do we come from all +this? To that which I announced to you from the first. Throughout the +length and breadth of creation, from the highest to the lowest grade, +every living thing is subject to the same law. Everything eats, and +eats nearly in the same manner, since everywhere the same substances +furnish the feast. I laid down in my first letter that our feeding +machine was reproduced even to the farthest limits of the animal +kingdom, though always becoming more simple as the species descends +in the scale. And afterwards, where we began the study of animals, I +told you that in this machine lay the uniformity of their construction. +Was I not right? and what could I add to all the proofs which have +developed themselves one after another, to establish the fact of this +uniformity of plan in the animal machine, in all its essential points? +And it will be to the lasting renown of the illustrious Geoffroy St. +Hilaire that it was, in the face of all the Academies and under the +fire of very learned indignation, he proclaimed this truth, which one +cannot lose sight of without losing one's way in a crowd of arbitrary +fancies. + +I return, then, to the definition which I gave you in speaking of the +worm, and which is the final word of the ideas I have been endeavoring +to make you understand. _An animal is a digestive tube served by +organs._ + +In the first place it must eat, and for this therefore the Creator +provided first. All the rest came afterwards in order to enable it to +eat more readily, to secure its prey more easily, and to make the most +of it when eaten. The movement machine, therefore, whose history I +have promised you, is only an assistant, and not the principal feature +of the organisation, and it is not by it, therefore, that the question +can be decided, whether God has made three, four, or five animals, or +whether he has only made one. + +And now, my dear little pupil, I will bid you adieu, or rather say as +the French do, "Au revoir," which means "Good-bye till we meet again," +begging you to excuse any awkward expressions that may have escaped +me, as also my having now and then talked about things because they +have interested me, without perhaps sufficiently considering whether +they might have an equal interest for you. Yet, while the pen is still +in my hand, I will not leave you my concluding definition of an animal +without adding a word of explanation. You know nothing about such +matters yourself, but to some people my words might have the air of +a parody upon another definition, applied by those grave gentlemen the +Philosophers to man, whom they have denominated _An intelligence +served by organs_. My definition is applicable only to the animal, +and not to man, observe. Man in the natural, physical machinery of his +body, is very decidedly an animal; yet as certainly is he, by the +divine reflection which shines within him, something much more and +greater; but _what_, is so far beyond the reach of definitionthat I +shall not attempt to give you one. "Man," as Jesus Christ has +said, "lives not by bread alone, but by every word that proccedeth out +of the mouth of God." What it is that is nourished in us by that word, +is precisely what I cannot attempt to define for you; yet I think you +have understood my meaning. + +Go, then, and eat your food in peace, like the pretty little animal +that you are; but do not forget to nourish also the other part of your +being; that indeed which is of the most importance, and which enables +you to ascend to your Creator. + +THE END. + + + +POSTSCRIPT. + +In going through the preceding pages (Part II) with a comparative +anatomist, it became evident that some few popular and other errors +and misconceptions had crept into this portion of M. Mace's usually +clear and accurate work. + +Naturally it was not in his power to verify all the statements he had +to make on so many and such varied subjects, and he appears occasionally +to have trusted to works of old-fashioned or doubtful authority. + +In these cases I have considered it desirable to make such corrections +as should secure the trustworthiness of the descriptions as far as +they pretend to go. + +It would not, however, have been in my power to accomplish this, but +for the kind and efficient aid I have received from a scientific student +of these subjects; and I am glad of this opportunity of acknowledging +how much I am indebted to him for his assistance in making the necessary +alterations, as well as for confirming the correctness of the greater +portion of the work. + +MARGARET GATTY. + +January, 1865. January, 1865. + + + + + +End of Project Gutenberg's The History of a Mouthful of Bread, by Jean Mace + +*** END OF THE PROJECT GUTENBERG EBOOK THE HISTORY OF A MOUTHFUL OF BREAD *** + +This file should be named 7brd110.txt or 7brd110.zip +Corrected EDITIONS of our eBooks get a new NUMBER, 7brd111.txt +VERSIONS based on separate sources get new LETTER, 7brd110a.txt + +Juliet Sutherland, Charles Franks and the Online Distributed +Proofreading Team. + +Project Gutenberg eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the US +unless a copyright notice is included. Thus, we usually do not +keep eBooks in compliance with any particular paper edition. + +We are now trying to release all our eBooks one year in advance +of the official release dates, leaving time for better editing. +Please be encouraged to tell us about any error or corrections, +even years after the official publication date. + +Please note neither this listing nor its contents are final til +midnight of the last day of the month of any such announcement. +The official release date of all Project Gutenberg eBooks is at +Midnight, Central Time, of the last day of the stated month. A +preliminary version may often be posted for suggestion, comment +and editing by those who wish to do so. + +Most people start at our Web sites at: +http://gutenberg.net or +http://promo.net/pg + +These Web sites include award-winning information about Project +Gutenberg, including how to donate, how to help produce our new +eBooks, and how to subscribe to our email newsletter (free!). + + +Those of you who want to download any eBook before announcement +can get to them as follows, and just download by date. This is +also a good way to get them instantly upon announcement, as the +indexes our cataloguers produce obviously take a while after an +announcement goes out in the Project Gutenberg Newsletter. + +http://www.ibiblio.org/gutenberg/etext03 or +ftp://ftp.ibiblio.org/pub/docs/books/gutenberg/etext03 + +Or /etext02, 01, 00, 99, 98, 97, 96, 95, 94, 93, 92, 92, 91 or 90 + +Just search by the first five letters of the filename you want, +as it appears in our Newsletters. + + +Information about Project Gutenberg (one page) + +We produce about two million dollars for each hour we work. The +time it takes us, a rather conservative estimate, is fifty hours +to get any eBook selected, entered, proofread, edited, copyright +searched and analyzed, the copyright letters written, etc. Our +projected audience is one hundred million readers. If the value +per text is nominally estimated at one dollar then we produce $2 +million dollars per hour in 2002 as we release over 100 new text +files per month: 1240 more eBooks in 2001 for a total of 4000+ +We are already on our way to trying for 2000 more eBooks in 2002 +If they reach just 1-2% of the world's population then the total +will reach over half a trillion eBooks given away by year's end. + +The Goal of Project Gutenberg is to Give Away 1 Trillion eBooks! +This is ten thousand titles each to one hundred million readers, +which is only about 4% of the present number of computer users. + +Here is the briefest record of our progress (* means estimated): + +eBooks Year Month + + 1 1971 July + 10 1991 January + 100 1994 January + 1000 1997 August + 1500 1998 October + 2000 1999 December + 2500 2000 December + 3000 2001 November + 4000 2001 October/November + 6000 2002 December* + 9000 2003 November* +10000 2004 January* + + +The Project Gutenberg Literary Archive Foundation has been created +to secure a future for Project Gutenberg into the next millennium. + +We need your donations more than ever! + +As of February, 2002, contributions are being solicited from people +and organizations in: Alabama, Alaska, Arkansas, Connecticut, +Delaware, District of Columbia, Florida, Georgia, Hawaii, Illinois, +Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, +Michigan, Mississippi, Missouri, Montana, Nebraska, Nevada, New +Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, +Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South +Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West +Virginia, Wisconsin, and Wyoming. + +We have filed in all 50 states now, but these are the only ones +that have responded. + +As the requirements for other states are met, additions to this list +will be made and fund raising will begin in the additional states. +Please feel free to ask to check the status of your state. + +In answer to various questions we have received on this: + +We are constantly working on finishing the paperwork to legally +request donations in all 50 states. If your state is not listed and +you would like to know if we have added it since the list you have, +just ask. + +While we cannot solicit donations from people in states where we are +not yet registered, we know of no prohibition against accepting +donations from donors in these states who approach us with an offer to +donate. + +International donations are accepted, but we don't know ANYTHING about +how to make them tax-deductible, or even if they CAN be made +deductible, and don't have the staff to handle it even if there are +ways. + +Donations by check or money order may be sent to: + +Project Gutenberg Literary Archive Foundation +PMB 113 +1739 University Ave. +Oxford, MS 38655-4109 + +Contact us if you want to arrange for a wire transfer or payment +method other than by check or money order. + +The Project Gutenberg Literary Archive Foundation has been approved by +the US Internal Revenue Service as a 501(c)(3) organization with EIN +[Employee Identification Number] 64-622154. Donations are +tax-deductible to the maximum extent permitted by law. As fund-raising +requirements for other states are met, additions to this list will be +made and fund-raising will begin in the additional states. + +We need your donations more than ever! + +You can get up to date donation information online at: + +http://www.gutenberg.net/donation.html + + +*** + +If you can't reach Project Gutenberg, +you can always email directly to: + +Michael S. Hart <hart@pobox.com> + +Prof. Hart will answer or forward your message. + +We would prefer to send you information by email. + + +**The Legal Small Print** + + +(Three Pages) + +***START**THE SMALL PRINT!**FOR PUBLIC DOMAIN EBOOKS**START*** +Why is this "Small Print!" statement here? You know: lawyers. +They tell us you might sue us if there is something wrong with +your copy of this eBook, even if you got it for free from +someone other than us, and even if what's wrong is not our +fault. So, among other things, this "Small Print!" statement +disclaims most of our liability to you. It also tells you how +you may distribute copies of this eBook if you want to. + +*BEFORE!* YOU USE OR READ THIS EBOOK +By using or reading any part of this PROJECT GUTENBERG-tm +eBook, you indicate that you understand, agree to and accept +this "Small Print!" statement. If you do not, you can receive +a refund of the money (if any) you paid for this eBook by +sending a request within 30 days of receiving it to the person +you got it from. If you received this eBook on a physical +medium (such as a disk), you must return it with your request. + +ABOUT PROJECT GUTENBERG-TM EBOOKS +This PROJECT GUTENBERG-tm eBook, like most PROJECT GUTENBERG-tm eBooks, +is a "public domain" work distributed by Professor Michael S. Hart +through the Project Gutenberg Association (the "Project"). +Among other things, this means that no one owns a United States copyright +on or for this work, so the Project (and you!) can copy and +distribute it in the United States without permission and +without paying copyright royalties. Special rules, set forth +below, apply if you wish to copy and distribute this eBook +under the "PROJECT GUTENBERG" trademark. + +Please do not use the "PROJECT GUTENBERG" trademark to market +any commercial products without permission. + +To create these eBooks, the Project expends considerable +efforts to identify, transcribe and proofread public domain +works. Despite these efforts, the Project's eBooks and any +medium they may be on may contain "Defects". Among other +things, Defects may take the form of incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other +intellectual property infringement, a defective or damaged +disk or other eBook medium, a computer virus, or computer +codes that damage or cannot be read by your equipment. + +LIMITED WARRANTY; DISCLAIMER OF DAMAGES +But for the "Right of Replacement or Refund" described below, +[1] Michael Hart and the Foundation (and any other party you may +receive this eBook from as a PROJECT GUTENBERG-tm eBook) disclaims +all liability to you for damages, costs and expenses, including +legal fees, and [2] YOU HAVE NO REMEDIES FOR NEGLIGENCE OR +UNDER STRICT LIABILITY, OR FOR BREACH OF WARRANTY OR CONTRACT, +INCLUDING BUT NOT LIMITED TO INDIRECT, CONSEQUENTIAL, PUNITIVE +OR INCIDENTAL DAMAGES, EVEN IF YOU GIVE NOTICE OF THE +POSSIBILITY OF SUCH DAMAGES. + +If you discover a Defect in this eBook within 90 days of +receiving it, you can receive a refund of the money (if any) +you paid for it by sending an explanatory note within that +time to the person you received it from. If you received it +on a physical medium, you must return it with your note, and +such person may choose to alternatively give you a replacement +copy. If you received it electronically, such person may +choose to alternatively give you a second opportunity to +receive it electronically. + +THIS EBOOK IS OTHERWISE PROVIDED TO YOU "AS-IS". NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, ARE MADE TO YOU AS +TO THE EBOOK OR ANY MEDIUM IT MAY BE ON, INCLUDING BUT NOT +LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A +PARTICULAR PURPOSE. + +Some states do not allow disclaimers of implied warranties or +the exclusion or limitation of consequential damages, so the +above disclaimers and exclusions may not apply to you, and you +may have other legal rights. + +INDEMNITY +You will indemnify and hold Michael Hart, the Foundation, +and its trustees and agents, and any volunteers associated +with the production and distribution of Project Gutenberg-tm +texts harmless, from all liability, cost and expense, including +legal fees, that arise directly or indirectly from any of the +following that you do or cause: [1] distribution of this eBook, +[2] alteration, modification, or addition to the eBook, +or [3] any Defect. + +DISTRIBUTION UNDER "PROJECT GUTENBERG-tm" +You may distribute copies of this eBook electronically, or by +disk, book or any other medium if you either delete this +"Small Print!" and all other references to Project Gutenberg, +or: + +[1] Only give exact copies of it. Among other things, this + requires that you do not remove, alter or modify the + eBook or this "small print!" statement. You may however, + if you wish, distribute this eBook in machine readable + binary, compressed, mark-up, or proprietary form, + including any form resulting from conversion by word + processing or hypertext software, but only so long as + *EITHER*: + + [*] The eBook, when displayed, is clearly readable, and + does *not* contain characters other than those + intended by the author of the work, although tilde + (~), asterisk (*) and underline (_) characters may + be used to convey punctuation intended by the + author, and additional characters may be used to + indicate hypertext links; OR + + [*] The eBook may be readily converted by the reader at + no expense into plain ASCII, EBCDIC or equivalent + form by the program that displays the eBook (as is + the case, for instance, with most word processors); + OR + + [*] You provide, or agree to also provide on request at + no additional cost, fee or expense, a copy of the + eBook in its original plain ASCII form (or in EBCDIC + or other equivalent proprietary form). + +[2] Honor the eBook refund and replacement provisions of this + "Small Print!" statement. + +[3] Pay a trademark license fee to the Foundation of 20% of the + gross profits you derive calculated using the method you + already use to calculate your applicable taxes. If you + don't derive profits, no royalty is due. Royalties are + payable to "Project Gutenberg Literary Archive Foundation" + the 60 days following each date you prepare (or were + legally required to prepare) your annual (or equivalent + periodic) tax return. Please contact us beforehand to + let us know your plans and to work out the details. + +WHAT IF YOU *WANT* TO SEND MONEY EVEN IF YOU DON'T HAVE TO? +Project Gutenberg is dedicated to increasing the number of +public domain and licensed works that can be freely distributed +in machine readable form. + +The Project gratefully accepts contributions of money, time, +public domain materials, or royalty free copyright licenses. +Money should be paid to the: +"Project Gutenberg Literary Archive Foundation." + +If you are interested in contributing scanning equipment or +software or other items, please contact Michael Hart at: +hart@pobox.com + +[Portions of this eBook's header and trailer may be reprinted only +when distributed free of all fees. Copyright (C) 2001, 2002 by +Michael S. Hart. Project Gutenberg is a TradeMark and may not be +used in any sales of Project Gutenberg eBooks or other materials be +they hardware or software or any other related product without +express permission.] + +*END THE SMALL PRINT! FOR PUBLIC DOMAIN EBOOKS*Ver.02/11/02*END* + diff --git a/old/7brd110.zip b/old/7brd110.zip Binary files differnew file mode 100644 index 0000000..050ac77 --- /dev/null +++ b/old/7brd110.zip diff --git a/old/8brd110.txt b/old/8brd110.txt new file mode 100644 index 0000000..ebb35eb --- /dev/null +++ b/old/8brd110.txt @@ -0,0 +1,11666 @@ +Project Gutenberg's The History of a Mouthful of Bread, by Jean Mace + +Copyright laws are changing all over the world. Be sure to check the +copyright laws for your country before downloading or redistributing +this or any other Project Gutenberg eBook. + +This header should be the first thing seen when viewing this Project +Gutenberg file. Please do not remove it. Do not change or edit the +header without written permission. + +Please read the "legal small print," and other information about the +eBook and Project Gutenberg at the bottom of this file. Included is +important information about your specific rights and restrictions in +how the file may be used. You can also find out about how to make a +donation to Project Gutenberg, and how to get involved. + + +**Welcome To The World of Free Plain Vanilla Electronic Texts** + +**eBooks Readable By Both Humans and By Computers, Since 1971** + +*****These eBooks Were Prepared By Thousands of Volunteers!***** + + +Title: The History of a Mouthful of Bread + And its effect on the organization of men and animals + +Author: Jean Mace + +Release Date: November, 2004 [EBook #6970] +[Yes, we are more than one year ahead of schedule] +[This file was first posted on February 18, 2003] + +Edition: 10 + +Language: English + +Character set encoding: Latin-1 + +*** START OF THE PROJECT GUTENBERG EBOOK THE HISTORY OF A MOUTHFUL OF BREAD *** + + + + +Juliet Sutherland, Charles Franks and the Online Distributed Proofreading Team. + + + + +THE HISTORY OF A MOUTHFUL OF BREAD: +And Its Effect on the Organization of Men and Animals. + +BY JEAN MACÉ. + +Translated Prom the Eighth French Edition, By Mrs. Alfred Gatty. + + + + +EXTRACTS FROM THE PREFACE TO THE ENGLISH EDITION. + +The volume of which the following pages are a translation, has been +adopted by the _University Commission at Paris_ among their prize +books, and has reached an eighth edition. Perhaps these facts speak +sufficiently in its favor; but as translator, and to some extent editor, +I wish to add my testimony to the great charm as well as merit of the +little work. I sat down to it, I must own, with no special predilection +in favor of the subject as a suitable one for young people; but in the +course of the labor have become a thorough convert to the author's +views that such a study--perhaps I ought to add, so pursued as he has +enabled it to be--is likely to prove a most useful and most desirable +one. + +The precise age at which the interest of a young mind can be turned +towards this practical branch of natural history is an open question, +and not worth disputing about. It may vary even in different +individuals. The letters are addressed to a _child_--in the original +even to a _little girl_--and most undoubtedly, as the book stands, it is +fit for any child's perusal who can find amusement in its pages: while +to the rather older readers, of whom I trust there will be a great many, +I will venture to say that the advantage they will gain in the subject +having been so treated as to be brought within the comprehension and +adapted to the tastes of a child, is pretty nearly incalculable. The +quaintness and drollery of the illustrations with which difficult +scientific facts are set forth will provoke many a smile, no doubt, and +in some young people perhaps a tendency to feel themselves treated +_babyishly_; but if in the course of the babyish treatment they find +themselves almost unexpectedly becoming masters of an amount of valuable +information on very difficult subjects, they will have nothing to +complain of. Let such young readers refer to even a popular +Encyclopaedia for an insight into any of the subjects of the +twenty-eight chapters of this volume--"The Heart," "The Lungs," "The +Stomach," "Atmospheric Pressure,"--no matter which, and see how much +they can understand of it without an amount of preliminary instruction +which would require half-a-year's study, and they will then thoroughly +appreciate the quite marvellous ingenuity and beautiful skill with +which M. Macé has brought the great leading anatomical and physical +facts of life out of the depths of scientific learning, and made them +literally comprehensible by a child. + + * * * * * + +There is one point (independent of the scientific teaching) and that, +happily, the only really important one, in which the English translator +has had no change to make or desire. The religious teaching of the +book is unexceptionable. There is no strained introduction of the +subject, but there is throughout the volume an acknowledgment of the +Great Creator of this marvellous work of the human frame, of the daily +and hourly gratitude we owe to Him, and of the utter impossibility of +our tracing out half his wonders, even in the things nearest to our +senses, and most constantly subject to observation. M. Macé will help, +and not hinder the humility with which the Christian naturalist lifts +one veil only to recognise another beyond. + +It will be satisfactory to any one who may be inclined to wonder how +a lady can feel sure of having correctly translated the various +scientific and anatomical statements contained in the volume, to know +that the whole has been submitted to the careful revision of a medical +friend, to whom I have reason to be very grateful for valuable +explanations and corrections whenever they were necessary. In the same +way the chapter on "Atmospheric Pressure," where, owing to the +difference between French and English weights and measures, several +alterations of illustrations, etc., had to be made, has received similar +kind offices from the hands of a competent mathematician. + + * * * * * + +MARGARET GATTY. + +Ecclesfield, June, 1864. + + + + +NOTE TO THE AMERICAN EDITION. + +In May '66, the seventeenth edition of this work was on sale in Paris. +The date of Mrs. Gatty's preface, it will be observed, is June '64, +and at that time, the eighth French edition only had been reached. +That it should be a popular book and command large sale wherever it +is known, will not surprise any one who reads it: the only remarkable +circumstance about it is, that it should not have been republished +here long ere this. Even this may probably be accounted for, on the +supposition that the title under which the translation was published +in England, was so unmeaning--conveying not the slightest idea of the +contents of the book--that none of our publishers even ventured to +hand it over to their "readers" to examine. + +The author's title, _The History of a Mouthful of Bread_, while +falling far short of giving a clear notion of the entire scope of the +work, is shockingly diluted and meaningless, when translated _The +History of a Bit of Bread!_ + +To the translation of Mrs. Gatty, which is in the main an excellent +one, for she has generally seized upon the idea of the author and +rendered it with singular felicity, it may be very properly objected +that she has taken some liberties with the text when there was any +conflict of opinion between herself and her author, and has given her +own ideas instead of his, which is, probably, what she refers to when +she calls herself "to some extent editor." + +The reader of this edition will, in all these cases, find the thought +of the author and not that of his translator; for the reason that a +careful examination of the original has convinced the publisher that +in every instance the author was to be preferred to the translator, +to say nothing of the right an author may have to be faithfully +translated. + +Besides making these restorations, the copy from which this edition +was printed has been carefully compared with the last edition of the +author and a vast number of corrections made, and in its present shape +it is respectfully submitted and dedicated to every one (whose name +is legion, of course) who numbers among his young friends a "_my +dear child_" to present it to. + + + + + +CONTENTS. + +I.--INTRODUCTION + +FIRST PART MAN. + +II.--THE HAND +III.--THE TONGUE +IV.--THE TEETH +V.--THE TEETH (_continued_) +VI.--THE TEETH (_continued_) +VII.--THE THROAT +VIII.--THE STOMACH +IX.--THE STOMACH (_continued_) +X.--THE INTESTINAL CANAL +XI.--THE LIVER +XII.--THE CHYLE +XIII.--THE HEART +XIV.--THE ARTERIES +XV.--THE NOURISHMENT OF THE ORGANS +XVI.--THE ORGANS +XVII.--ARTERIAL AND VENOUS BLOOD +XVIII.--ATMOSPHERIC PRESSURE +XIX.--THE ACTION OF THE LUNGS +XX.--CARBON AND OXYGEN +XXI.--COMBUSTION +XXII.--ANIMAL HEAT +XXIII.--ACTION OF THE BLOOD UPON THE ORGANS +XXIV.--THE WORK OF THE ORGANS +XXV.--CARBONIC ACID +XXVI.--ALIMENTS OF COMBUSTION +XXVII.--ALIMENTS OF NUTRITION (_continued_)--NITROGEN OR AZOTE +XXVIII.--COMPOSITION OF THE BLOOD + + +SECOND PART. + +ANIMALS. + +XXIX.--CLASSIFICATION OF ANIMALS +XXX.--MAMMALIA (_Mammals_) +XXXI.--MAMMALIA. (_Mammals_)--_continued_ +XXXII.--MAMMALIA--_continued_ +XXXIII.--MAMMALIA--_continued_ +XXXIV.--AVES. (_Birds_) +XXXV.--REPTILIA. (_Reptiles_) +XXXVI.--PISCES. (_Fishes_) +XXXVII.--INSECTA. (_Insects_) +XXXVIII.--CRUSTACEA--MOLLUSKA. (_Crustaceans and Mollusks_) +XXXIX.--VERMES--ZOOPHYTA. (_Worms and Zoophytes_) +XL.--THE NOURISHMENT OF PLANTS +CONCLUSION + + + +I. + +INTRODUCTION. + +I am going to tell you, my dear child, something of the life and nature +of men and animals, believing the information may be of use to you in +after-life, besides being an amusement to you now. + +Of course, I shall have to explain to you a great many particulars +which are generally considered very difficult to understand, and which +are not always taught even to grown-up people. But if we work together, +and between us succeed in getting them clearly into your head, it will +be a great triumph to me, and you will find out that the science of +learned men is more entertaining for little girls, as well as more +comprehensible, than it is sometimes supposed to be. Moreover, you +will be in advance of your years, as it were, and one day may be +astonished to find that you had mastered in childhood, almost as a +mere amusement, some of the first principles of anatomy, chemistry, +and several other of the physical sciences, as well as having attained +to some knowledge of natural history generally. + +I begin at once, then, with the _History of a Mouthful of Bread_, +although I am aware you may be tempted to exclaim, that if I am going +to talk only about that, I may save myself the trouble. You know all +about it, you say, as well as I do, and need not surely be told how +to chew a bit of bread-and-butter! Well, but you must let me begin at +the very beginning with you, and you have no notion what an incredible +number of facts will be found to be connected with this chewing of a +piece of bread. A big book might be written about them, were all the +details to be entered into. + +First and foremost--Have you ever asked yourself _why_ people eat? + +You laugh at such a ridiculous question. + +"Why do people eat? Why, because there are bonbons, and cakes, and +gingerbread, and sweetmeats, and fruit, and all manner of things good +to eat." Very well, that is a very good reason, no doubt, and you may +think that no other is wanted. If there were nothing but soup in the +world, indeed, the case would be different. There might be some excuse +then for making the inquiry. + +Now, then, let us suppose for once that there _is_ nothing in the +world to eat but soup; and it is true that there are plenty of poor +little children for whom there is nothing else, but who go on eating +nevertheless, and with a very good appetite, too, I assure you, as +their parents know but too well very often. Why do people eat, then, +even when they have nothing to eat but soup? This is what I am going +to tell you, if you do not already know. + +The other day, when your mamma said that your frock "had grown" too +short, and that you could not go out visiting till we had given you +another with longer sleeves and waist, what was the real cause of this +necessity? + +What a droll question, you say, and you answer--"Because I had grown, +of course." + +To which I say "of course," too; for undoubtedly it was you who had +outgrown your frock. But then I must push the question further, and +ask--How had you grown? + +Now you are puzzled. Nobody had been to your bed and pulled out your +arms or your legs as you lay asleep. Nobody had pieced a bit on at the +elbow or the knee, as people slip in a new leaf to a table when there +is going to be a larger party than usual at dinner. How was it, then, +that the sleeves no longer came down to your wrists, or that the body +only reached your knees? Nothing grows larger without being added to, +any more than anything gets smaller without having lost something; you +may lay that down as a rule, once for all. If, therefore, nothing was +added to you from without, something must have been added to you from +within. Some sly goblin, as it were, must have been cramming into your +frame whatever increase it has made in arms, legs, or anything else. +And who, do you think, this sly goblin is? + +Why, my dear, it is _yourself!_ + +Ay! Bethink you, now, of all the bread-and-butter, and bonbons, and +gingerbread, and cakes, and sweetmeats, and even soup and plain food +(the soup and plain food being the most useful of all) which you have +been sending, day by day, for some time past, down what we used to +call "the red lane," into the little gulf below. What do you think +became of them when they got there? Well, they set to work at once, +without asking your leave, to transform themselves into something else; +and gliding cunningly into all the holes and corners of your body, +became there, each as best he might, bones, flesh, blood, etc., +etc. Touch yourself where you will, it is upon these things you lay +your hand, though, of course, without recognizing them, for the +transformation is perfect and complete. And it is the same with +everybody. + +Look at your little pink nails, which push out further and further +every morning; examine the tips of your beautiful fair hair, which +gets longer and longer by degrees; coming out from your head as grass +springs up from the earth; feel the firm corners of your second teeth, +which are gradually succeeding those which came to you in infancy; you +have _eaten_ all these things, and that no long time ago. + +Nor are you children the only creatures who are busy in this way. There +is your kitten, for instance, who a few months ago was only a tiny bit +of fur, but is now turning gradually into a grown-up cat. It is her +daily food which is daily becoming a cat inside her--her saucers of +milk now, and very soon her mice, all serve to the same end. + +The large ox, too, of whom you are so much afraid, because you cannot +as yet be persuaded what a good-natured beast he really is, and how +unlikely to do any harm to children who do none to him--that large ox +began life as a small calf, and it is the grass which he has been +eating for some time past which has transformed him into the huge mass +of flesh you now see, and which by-and-by will be eaten by man, to +become man's flesh in the same manner. + +But, further, still: Even the forest trees, which grow so high and +spread so wide, were at first no bigger than your little finger, and +all the grandeur and size you now look upon, they have taken in by the +process of eating. "What, _do trees eat?_" you ask. + +Verily, do they; and they are, by no means, the least greedy of eaters, +for they eat day and night without ceasing. Not, as you may suppose, +that they crunch bonbons, or anything else as you do; nor is the process +with them precisely the same as with you. Yet you will be surprised +hereafter, I assure you, to find how many points of resemblance exist +between them and us in this matter. But we will speak further of this +presently. + +Now, I think you must allow that there are few fairytales more +marvellous than this history of bread and meat turning into little +boys and girls, milk and mice turning into cats, and grass into oxen! +And I call it a _history_, observe, because it is a transformation +that never happens suddenly, but by degrees, as time goes on. + +Now, then, for the explanation. You have heard, I dare say, of those +wonderful spinning-machines which take in at one end a mass of raw +cotton, very like what you see in wadding, and give out at the other +a roll of fine calico, all folded and packed up ready to be delivered +to the tradespeople. Well, you have within you, a machine even more +ingenious than that, which receives from you all the bread-and-butter +and other sorts of food you choose to put into it, and returns it to +you changed into the nails, hair, bones and flesh we have been talking +about, and many other things besides; for there are quantities of +things in your body, all different from each other, which you are +manufacturing in this manner all day long, without knowing anything +about it. And a very fortunate thing this is for you: for I do not +know what would become of you if you had to be thinking from morning +to night of all that requires to be done in your body, as your mother +has to look after and remember all that has to be done in the house. +Just think what a relief it would be to her to possess a machine which +should sweep the rooms, cook the dinners, wash the plates, mend torn +clothes, and keep watch over everything without giving her any trouble; +and, moreover, make no more noise or fuss than yours does, which has +been working away ever since you were born without your ever troubling +your head about it, or probably even knowing of its existence! Just +think of this and be thankful. + +But do not fancy you are the only possessor of a magical machine of +this sort. Your kitten has one also, and the ox we were speaking of, +and all other living creatures. And theirs render the same service to +them that yours does to you, and much in the same way; for all these +machines are made after one model, though with certain variations +adapted to the differences in each animal. And, as you will see +by-and-by, these variations exactly correspond with the different sort +of work that has to be done in each particular case. For instance, +where the machine has grass to act upon, as in the ox, it is differently +constructed from that in the cat which has to deal with meat and mice. +In the same way in our manufactories, though all the spinning-machines +are made upon one model, there is one particular arrangement for those +which spin cotton, another for those which spin wool, another for flax, +and so on. + +But, further: + +You have possibly noticed already, without being told, that all animals +are not of equal value; or, at least, to use a better expression, they +have not all had the same advantages bestowed on them. The dog, for +instance, that loving and intelligent companion, who almost reads your +thoughts in your eyes, and is as affectionate and obedient to his master +as it were to be wished all children were to their parents--this dog +is, as you must own, very superior, in all ways, to the frog, with its +large goggle eyes and clammy body, hiding itself in the water as soon +as you come near it. But again, the frog, which can come and go as it +likes, is decidedly superior to the oyster, which has neither head nor +limbs, and lives all alone, glued into a shell, in a sort of perpetual +imprisonment. + +Now the machine I have been telling you about is found in the oyster +and in the frog as well as in the dog, only it is less complicated, +and therefore less perfect in the oyster than in the frog; and less +perfect again in the frog than in the dog; for as we descend in the +scale of animals we find it becoming less and less elaborate--losing +here one of its parts, there another, but nevertheless remaining still +the same machine to all intents and purposes; though by the time it +has reached its lowest condition of structure we should hardly be able +to recognize it again, if we had not watched it through all its +gradations of form, and escorted it, as it were, from stage to stage. + +Let me make this clear to you by a comparison. + +You know the lamp which is lit every evening on the drawing-room table, +and around which you all assemble to work or read. Take off first the +shade, which throws the light on your book--then the glass which +prevents it smoking--then the little chimney which holds the wick and +drives the air into the flame to make it burn brightly. Then take away +the screw, which sends the wick up and down; undo the pieces one by +one, until none remain but those absolutely necessary to having a light +at all--namely, the receptacle for the oil and the floating wick which +consumes it. + +Now if any one should come in and hear you say, "Look at my lamp," +what would he reply? He would most likely ask at once, "What lamp?"--for +there would be very little resemblance to a lamp in that mere ghost +of one before him. + +But to you, who have seen the different parts removed one after another, +that wick soaked in oil (let your friend shake his head about it as +he pleases) will still be the lamp to you, however divested of much +that made it once so perfect, and however dimly it may shine in +consequence. + +And this is exactly what happens when the machine we are discussing +is examined in the different grades of animals. The ignoramus who has +not followed it through its changes and reductions cannot recognize +it when it is presented to him in its lowest condition; but any one +who has carefully observed it throughout, knows that it is, in point +of fact, the same machine still. + +This, then, is what we are now going to look at together, my dear +little girl. We will study first, piece by piece, the exquisite machine +within ourselves, which is of such unceasing use to us as long as we +do not give it more than a proper share of work to perform. Do you +understand? We will see what becomes of the mouthful of bread which +you place so coolly between your teeth, as if when that was done nothing +further remained to be thought about. We will trace it in its passage +through every part of the machine, from beginning to end. It will +therefore be simply only the _History of a Mouthful of Bread_ I +am telling you, even while I seem to be talking of other matters; for +to make that comprehensible I shall have to enter into a good many +explanations. + +And when you have thoroughly got to understand the history of what you +eat yourself, we will look a little into the history of what other +animals eat, beginning by those most like ourselves, and going on to +the rest in regular succession downwards. And while we are on the +subject, I will say a word or two on the way in which vegetables eat, +for, as you remember, I have stated that they do eat also. + +Do you think this is likely to interest you, and be worth the trouble +of some thought and attention? + +Perhaps you may tell me it sounds very tedious, and like making a great +fuss about a trifle; that you have all your life eaten mouthfuls of +bread without troubling yourself as to what became of them, and yet +have not been stopped growing by your ignorance, any more than the +little cat, who knows no more how it happens than you do. + +True, my dear; but the cat is only a little cat, and you are a little +girl. Up to the present moment you and she have known, one as much as +the other on this subject, and on that point you have therefore had +no superiority over her. But she will never trouble herself about it, +and will always remain a little cat. You, on the contrary, are intended +by God to become something more in intelligence than you are now, and +it is by learning more than the cat that you will rise above her in +this respect. To learn, is the duty of all men, not only for the +pleasure of curiosity and the vanity of being called learned, but +because in proportion to what we learn we approach nearer to the destiny +which God has appointed to man, and when we walk obediently in the +path which God himself has marked out for us, we necessarily become +better. + +It is sometimes said to grown-up people, that it is never too late to +learn. To children one may say that it is never too early to learn. +And among the things which they may learn, those which I want now to +teach you have the double merit of being, in the first place amusing, +and afterwards, and above all, calculated to accustom you to think of +God, by causing you to observe the wonders which He has done. Sure am +I that when you know them you will not fail to admire them; moreover +I promise your mother that you will be all the better, as well as +wiser, for the study. + + + + +FIRST PART.--MAN. + +LETTER II. + +THE HAND. + +At the foot of the mountains, from whence I write to you, my dear +child, when we want to show the country to a stranger, we commence by +making him climb one of the heights, whence he may take in at a glance +the whole landscape below, all the woods and villages scattered over +the plain, even up to the blue line of the Rhine, which stretches out +to the distant horizon. After this he will easily find his way about. + +It is to the top of a mountain equally useful that I have just led +you. It has cost you some trouble to climb with me. You have had to +keep your eyes very wide open that you might see to the end of the +road we had to go together. Now then, let us come down and view the +country in detail. Then we shall go as if we were on wheels. + +And now let us begin at the beginning: + +Well, doubtless, as the subject is eating, you will expect me to begin +with the mouth. + +Wait a moment; there is something else first. But you are so accustomed +to make use of it, that you have never given it a thought, I dare say. + +It is not enough merely that one should have a mouth; we must be able +to put what we want within it. What would you do at dinner, for +instance, if you had no hands? + +The hand is then the first thing to be considered. + +I shall not give you a description of it; you know what it is like. +But what, perhaps, you do not know, because you have never thought +about it, is, the reason why your hand is a more convenient, and +consequently more perfect, instrument than a cat's paw, for instance, +which yet answers a similar purpose, for it helps the cat to catch +mice. + +Among your five fingers there is one which is called the thumb, which +stands out on one side quite apart from the others. Look at it with +respect; it is to these two little bones, covered over with a little +flesh, that man owes part of his physical superiority to other animals. +It is one of his best servants, one of the noblest of God's gifts to +him. Without the thumb three-fourths (at least) of human arts would +yet have to be invented; and to begin with, the art not only of carrying +the contents of one's plate to one's mouth, but of filling the plate +(a very important question in another way) would, but for the thumb, +have had difficulties to surmount of which you can form no idea. + +Have you noticed that when you want to take hold of anything (a piece +of bread, we will say, as we are on the subject of eating), have you +noticed that it is always the thumb who puts himself forward, and that +he is always on one side by himself, whilst the rest of the fingers +are on the other? If the thumb is not helping, nothing remains in your +hand, and you don't know what to do with it. Try, by way of experiment, +to carry your spoon to your mouth without putting your thumb to it, +and you will see what a long time it will take you to get through a +poor little plateful of broth. The thumb is placed in such a manner +on your hand that it can face each of the other fingers one after +another, or all together, as you please; and by this we are enabled +to grasp, as if with a pair of pincers, whatever object, whether large +or small. Our hands owe their perfection of usefulness to this happy +arrangement, which has been bestowed on no other animal, except the +monkey, our nearest neighbor. + +I may even add, while we are about it, that it is this which +distinguishes the hand from a paw or a foot. Our feet, which have other +things to do than to pick up apples or lay hold of a fork, our feet +have also each five fingers, but the largest cannot face the others; +it is not a thumb, therefore, and it is because of this that our feet +are not hands. Now the monkey has thumbs on the four members +corresponding to our arms and legs, and thus we may say that he has +hands at the end of his legs as well as of his arms. Nevertheless, he +is not on that account better off than we are, but quite the contrary. +I will explain this to you presently. + +To return to our subject. You see that it was necessary, before saying +anything about the mouth, to consider the hand, which is the mouth's +purveyor. Before the cook lights the fires the maid must go to market, +must she not? And it is a very valuable maid that we have here: what +would become of us without her? + +If we were in the habit of giving thought to everything, we should +never even gather a nut without being grateful to the Providence which +has provided us with the thumb, by means of which we are able to do +it so easily. + +But however well I may have expressed it, I am by no means sure, after +all, that I have succeeded in showing you clearly, how absolutely +necessary our hand is to us in eating, and why it has the honor to +stand at the beginning of the history of what we eat. + +It still appears to you, I suspect, that even if you were to lose the +use of your hands you would not, for all that, let yourself die of +hunger. + +This is because you have not attended to another circumstance, which +nevertheless demands your notice--namely, that from one end of the +world to the other, quantities of hands are being employed in providing +you with the wherewithal to eat. + +To go on further: Have you any idea how many hands have been put in +motion merely to enable you to have your coffee and roll in the morning? +What a number, to be sure, over this cup of coffee (which is a trifle +in comparison with the other food you will consume in the course of +the day); from the hand of the negro who gathered the coffee crop to +that of the cook who ground the berries, to say nothing of the hand +of the sailor who guided the ship which bore them to our shores. Again, +from the hand of the laborer who sowed the corn, and that of the miller +who ground it into flour, to the hand of the baker who made it into +a roll. Then the hand of the farmer's wife who milked the cow, and the +hand of the refiner who made the sugar; to say nothing of the many +others who prepared his work for him, and I know not how many more. + +How would it be, then, if I were to amuse myself by counting up all +the hands that are wanted to furnish-- + + The sugar-refiner's manufactory, + The milkmaid's shed, + The baker's oven, + The miller's mill, + The laborer's plough, + The sailor's ship? + +And even now is there nothing we have forgotten? Ah, yes! the most +important of all the hands to you;--the hand which brings together +for your benefit the fruits of the labor of all the others--the hand +of your dear mother, always active, always ready, that hand which so +often acts as yours when your own is awkward or idle. + +Now, then, you see how you might really manage to do without those two +comparatively helpless little paws of yours (although there is a thumb +to each), without suffering too much for want of food. With such an +army of hands at work, in every way, to furnish provision for that +little mouth, there would not be much danger. + + +But cut off your cat's fore paws--oh dear! what am I saying? Suppose, +rather, that she has not got any, and then count how many mice she +will catch in a day. The milk you give her is another matter, remember. +Like your cup of coffee, that is provided for her by others. + +Believe me, if you were suddenly left all alone in a wood, like those +pretty squirrels who nibble hazel-nuts so daintily, you would soon +discover, from being thus thrown upon your own resources, that the +mouth is not the only thing required for eating, and that whether it +be a paw or a hand, there must always be a servant to go to market for +Mr. Mouth, and to provide him with food. + +Happily, we are not driven to this extremity. We take hold of our +coffee-biscuit between the thumb and forefinger, and behold it is on +its road--Open the mouth, and it is soon done! + +But before we begin to chew, let us stop to consider a little. + +The mouth is the door at which everything enters. Now, to every +well-kept door there is a doorkeeper, or porter. And what is the office +of a well-instructed porter? Well, he asks the people that present +themselves, who they are, and what they have come for; and if he does +not like their appearance, he refuses them admittance. We too, then, +to be complete, need a porter of this sort in our mouths, and I am +happy to say we have one accordingly. I wonder whether you know him? +You look at me quite aghast! Oh, ungrateful child, not to know your +dearest friend! As a punishment, I shall not tell you who he is to-day. +I will give you till to-morrow to think about it. + +Meanwhile, as I have a little time left, I will say one word more about +what we are going to look at together. It would hardly be worth while +to tell you this pretty story which we have begun, if from time to +time we were not to extract a moral from it. And what is the moral of +our history to-day? + +It has more than one. + +In the first place it teaches you, if you never knew it before, that +you are under great obligations to other people, indeed to almost +everybody, and most of all perhaps to people whom you may be tempted +to look down upon. This laborer, with his coarse smock-frock and heavy +shoes, whom you are so ready to ridicule, is the very person who, with +his rough hand, has been the means of procuring for you half the good +things you eat. That workman, with turned-up sleeves, whose dirty black +fingers you are afraid of touching, has very likely blackened and +dirtied them in your service. You owe great respect to all these people, +I assure you, for they all work for you. Do not, then, go and fancy +yourself of great consequence among them--you who are of no use in any +way at present, who want everybody's help yourself, but as yet can +help nobody. + +Not that I mean to reproach you by saying this. Your turn has not come +yet, and everybody began like you originally. But I do wish to impress +upon you that you must prepare yourself to become some day useful to +others, so that you may pay back the debts which you are now +contracting. + +Every time you look at your little hand, remember that you have its +education to accomplish, its debts of honor to repay, and that you +must make haste and teach it to be very clever, so that it may no +longer be said of you, that you are of no use to anybody. + +And then, my dear child, remember that a day will come, when the revered +hands that now take care of your childhood--those hands which to-day +are yours, as it were--will become weak and incapacitated by age. You +will be strong, then, probably, and the assistance which you receive +now, you must then render to her, render it to her as you have received +it--that is to say, with your hands. It is the mother's hand which +comes and goes without ceasing about her little girl now. It is the +daughter's hand which should come and go around the old mother +hereafter--her hand and not another's. + +Here again, my child, the mouth is nothing without the hand. The mouth +says, "I love," the hand proves it. + + + +LETTER III. + +THE TONGUE. + +Now, about this doorkeeper, or porter, as we will call him, of the +mouth. I do not suppose you have guessed who he is; so I am going to +tell you. + +The porter who keeps the door of the mouth is _the sense of taste_. + +It is he who does the honors of the house so agreeably to proper +visitors, and gives such an unscrupulous dismissal to unpleasant +intruders. In other words, it is by his directions that we welcome so +affectionately with tongue and lips whatever is good to eat, and spit +out unhesitatingly whatever is unpleasant. + +I could speak very ill of this porter if I chose; which would not be +very pleasant for certain little gourmands that I see here, who think +a good deal too much of him. But I would rather begin by praising him. +I can make my exceptions afterwards. + +In the history I am going to give you, my dear child, there is one +thing you must never lose sight of, even when I do not allude to it; +and that is, that everything we shall examine into, has been expressly +arranged by God for the good and accommodation of our being in this +world; just as a cradle is arranged by a mother for the comfort of her +baby. We must look upon all these things, therefore, as so many +presentsfrom the Almighty himself; and abstain from speaking ill of +them, were it only out of respect for the hand which has bestowed them. + +Moreover, there is a very easy plan by which we may satisfy ourselves +of the usefulness and propriety of these gifts--namely, by considering +what would become of us if we were deprived of any one of them. + +Suppose, for instance, that you were totally deficient in the sense +of taste, and that when you put a piece of cake into your mouth, it +should create no more sensation in you than when you held it in your +hand? + +You would not have thought of imagining such a case yourself, I am +aware; for it never comes into a child's head to think that things can +be otherwise than as God has made them. And in that respect children +are sometimes wiser than philosophers. Nevertheless, we will suppose +this for once, and consider what would happen in consequence. + +Well, in the first place, you would eat old mouldy cake with just the +same relish as if it were fresh; and this mouldy cake, which now you +carefully avoid because it is mouldy, is very unwholesome food, and +would poison you were you to eat a great deal of it. + +I give this merely as an instance, but it is one of a thousand. And +although, with regard to eatables, you only know such as have been +prepared either in shops or in your mamma's kitchen, still you must +be aware there are many we ought to avoid, because they would do no +good in our stomachs, and that we should often be puzzled to distinguish +these from others, if the sense of taste did not warn us about them. +You must admit, therefore, that such warnings are not without their +value. + +In short, it is a marvellous fact that what is unfit for food, is +_almost always_ to be recognized as it enters the mouth, by its +disagreeable taste; a further proof that God has thought of everything. +Medicines, it is true, are unpleasant to the taste, and yet have to +be swallowed in certain cases. But we may compare them to +chimney-sweepers, who are neither pretty to look at, nor invited into +the drawing-room; but who, nevertheless, are from time to time let +into the grandest houses by the porters--though possibly with a +grimace--because their services are wanted. And in the same way +medicines have to be admitted sometimes--despite their +unpleasantness--because they, too, have to work in the chimney. Taste +does not deceive you about them, however; they are not intended to +serve as food. If any one should try to breakfast, dine, and sup upon +physic he would soon find this out. + +Besides, I only said _almost_ always, in speaking of unwholesome +food making itself known to us by its nasty taste; for it is an +unfortunate truth that men have invented a thousand plans for baffling +their natural guardian, and for bringing thieves secretly into the +company of honest people. They sometimes put poison, for instance, +into sugar--as is too often done in the case of those horrible green +and blue sugar plums, against which I have an old grudge, for they +poisoned a friend whom I loved dearly in my youth. Such things as these +pass imprudently by the porter, who sees nothing of their real +character--Mr. Sugar concealing the rogues behind him. + +Moreover, we are sometimes so foolish as not to leave the porter time +to make his examination. We swallow one thing after another greedily, +without tasting; and such a crowd of arrivals, coming in with a rush, +"forces the sentry," as they say; and whose fault is it, if, after +this, we find thieves established in the house? + +But animals have more sense than we have. + +Look at your kitten when you give her some tit-bit she is not acquainted +with--how cautiously and gently she puts out her nose, so as to give +herself time for consideration. Then how delicately she touches the +unknown object with the tip of her tongue, once, twice, and perhaps +three times. And when the tip of the tongue has thus gone forward +several times to make observations (for this is the great post of +observation for the cat's porter as well as for ours), she ventures +to decide upon swallowing, but not before. If she has the least +suspicion, no amount of coaxing makes any difference to her; you may +call "puss, puss," for ever; all your tender invitations are useless, +and she turns away. + +Very good; here then is one little animal, at least, who understands +for what end she has received the sense of taste, and who makes a +reasonable use of it. Very different from some children of my +acquaintance, who heedlessly stuff into their mouths whatever comes +into their hands, without even taking the trouble to taste it, and who +would escape a good many stomach-aches, if nothing else, if they were +as sensible as Pussy. + +This is the really useful side of _the sense of taste_; but its +agreeable side, which is sufficiently well known to you, is not to be +despised either, even on the grounds of utility. + +You must know, between ourselves, that eating would be a very tiresome +business if we did not taste what we are eating; and I can well imagine +what trouble mammas would have in persuading their children to come +to dinner or tea, if it were only a question of working their little +jaws, and nothing further. What struggles--what tears! And setting +aside children, who are by no means always the most disobedient to the +will of a good GOD, how few men would care to stop in the midst of +their occupations, to go and grind their teeth one against another for +half-an-hour, if there were not some pleasure attached to an exercise +not naturally amusing in itself? Ay, ay, my dear child, were it not +for the reward in pleasure which is given to men when they eat, the +human race, who as a whole do not live too well already, would live +still worse. And it is necessary that we should be fed, and well fed +too, if we would perform properly here below the mission which we have +received from above. + +Yes, "reward" was the word I used. Now it seems absurd to you, perhaps, +that it should be necessary to reward a man for eating a good dinner? +Well, well, GOD has been more kind to him, then, than you would be. +To every duty imposed by Him upon man, He has joined a pleasure as a +reward for fulfilling it. How many things should I not have to say to +you on this subject, if you were older? For the present, I will content +myself with making a comparison. + +When a mother thinks her child is not reasonable enough to do, of her +own accord, something which it is nevertheless important she should +do, as learning to read, for instance, or to work with her needle, +&c., she comes to the rescue with rewards, and gives her a plaything +when she has done well. And thus GOD, who had not confidence enough +in man's reason to trust to it alone for supplying the wants of human +nature, has placed a plaything in the shape of pleasure after every +necessity; and in supplying the want, man finds the reward. + +You will hardly believe that what I have here explained to you so +quietly by a childish comparison, has been, and alas! still is, the +subject of terrible disputes among grown-up people. If hereafter they +reach your ears, remember what I have told you now, viz., that the +pleasure lodged in the tongue and its surroundings, is a plaything, +but a plaything given to us by GOD; and that we must use it accordingly. + +If a little girl has had a plaything given to her by her mother, would +she think to please her by breaking it or throwing it into a corner? +No, certainly not: she would know that in so doing she would be going +directly against her mother's intentions and wishes. Nevertheless she +would amuse herself with it in play hours, with an easy conscience, +and, if she is amiable, she will remember while she does so, that it +comes to her from her mother, and will thank her at the bottom of her +heart. + +It is the same with man, of whose playthings we are speaking. + +But, moreover, this little girl (it is taken for granted that she is +a good little girl) will not make the plaything the business of her +whole day, the object of all her thoughts; she will not forget +everything for it, she will leave it unhesitatingly when her mamma +calls her. Neither will she wish to be alone in her enjoyments, but +will gladly see her little friends also enjoy similar playthings, +because she thinks that what is good for her must be good for others +too. + +It is thus that man should do with his playthings; but, alas! this is +what he does not by any means always do with them, and hence a great +deal has been said against them. Little girls, in particular, are apt +to fail on this point, and that is how the dreadful word _gluttony_ +came to be invented. For the same reason, also, people get punished +from time to time; such punishments being the consequence of the misuse +I speak of. + +If people who call to see your mamma were, instead of going straight +up stairs to her, to establish themselves at the lodge with the porter, +and stay there chatting with him, do you think she would be much +flattered by their visits? And yet this is exactly what people do who, +when eating, attend only to the porter. He is so pleasant, this porter; +he says such pretty things to you, that you go on talking to him just +as if he were the master of the house, who, meanwhile, has quite gone +out of your head. + +You heap sugar-plums upon sugar-plums, cakes upon cakes, sweetmeats +upon sweetmeats--everything that pleases the porter, but is of no use +whatever to the master of the house. And then what happens? The master +gets angry sometimes, and no wonder. Mr. Stomach grows weary of these +visits, which are of no use to him. He rings all the bells, makes no +end of a noise in the house, and forces that traitor of a porter who +has engrossed all his company, to do penance. You are ill--your mouth +is out of order--you have no appetite for anything. The mamma has taken +away the plaything which has been misused, and when she gives it back, +there must be great care taken not to do the same thing over again. + +I have thought it only right, my dear child, in telling you the history +of eating, to give to this little detail of its beginning, a place +proportioned to your interest in it. You see by what I have said, that +you are not altogether wrong in following your taste; but neither must +it be forgotten that this part of the business is not in reality the +most important; that a plaything is but a plaything, and that the +porter is not the master of the house. + +Now that we have made our good friend's acquaintance, we will wish him +farewell, and I will presently introduce you to his companions of the +antechamber, who are ranged on the two sides of the door, to make the +toilettes for the visitors who present themselves, and to put them in +order for being received in the drawing-room. You will see there some +jolly little fellows, who are also very useful in their way, and whose +history is no less curious. They are called TEETH. + + + +LETTER IV. + +THE TEETH. + +When you were quite little, my dear child, and still a nursling, you +had nothing behind your lips but two little rosy bars, which were of +no service for gnawing an apple, as they were not supplied with teeth. +You had no need of these then, since nothing but milk passed your lips, +neither had your nurse bargained for your having teeth to bite with. +You see that God provides for everything, as I have already said, and +shall often have occasion to point out to you. + +But by degrees the little infant grew into a great girl, and it became +necessary to think of giving her something more solid than milk to +eat; and for this purpose she required teeth. Then some little germs, +which had lain dormant, concealed within the jaws, awoke one after +another, like faithful workmen when they hear the striking of the +clock. Each set to work in his little cell, and with the help of some +phosphorus and some lime, it began to make itself a kind of white +armour, as hard as a stone, which grew larger from day to day. + +You know what lime is; that sort of white pulp which you have seen +standing in large troughs where the masons are building houses, andwhich +they use in making mortar; it is with this that your little +masons build your teeth. + +As to phosphorus, I am afraid you may never have seen any; but you may +have heard it spoken of. It is sold at the druggist's in the form of +little white sticks, about as thick as your finger; they have a +disagreeable, garlicky smell, and are obliged to be kept in jars of +water, because they seize every opportunity of taking fire; so I advise +you, if ever you do see any phosphorus, not to meddle with it--for in +burning, it sticks closely to the skin, and there is the greatest +difficulty in the world in extinguishing it, and the burns it makes +are fearful. I give you this caution, because phosphorus possesses a +very curious property, which might attract little girls. Wherever it +is rubbed, in the dark, on a door, or on a wall, it leaves a luminous +trail of a very peculiar appearance, which has been called +phosphorescent, from the name of the substance which produces it. And +in this way one can write on walls in letters of fire, to the terror +of cowards. Now, come; if you will promise to be very wise, and only +to make the experiment when your mamma is present, I will teach you +how to make phosphorescent lights without having to go to the +druggist's! There is a small quantity of phosphorus in lucifer matches, +which their garlicky smell proves. Rub them gently in the dark on a +bit of wood, and you will see a ray of light which will shine for some +moments. But mind, you must not play at that game when you are alone; +it is a dangerous amusement, and one hears every day of terrible +accidents caused by disobedient children playing with lucifer matches. +And while we are on the subject, let me warn you against putting them +into your mouth. Phosphorus is a poison, and such a powerful one that +people poison rats with bread-crumb balls in which it has been +introduced. + +"Oh dear me! and that poison makes part of our teeth?" + +Exactly so, and it even forms part of all our bones, and of the bones +of all animals; the best proof of which is, that the phosphorus of +lucifer matches has been procured out of bones from the slaughter-house. +One could make it from the teeth of little girls if one could get +enough of them. + +Now I see what puzzles you, and well it may. You are asking yourself +how those little tooth-makers, the gums, get hold of this terrible +phosphorus, which is set on fire by a mere nothing, and which we dare +not put into our mouths; where do they find the lime which I also +protest is not fit to eat, and yet of which we have stores from our +heads to our feet? + +It is very surprising, too, to think of its being forthcoming in the +jaws just when it is wanted there. + +You begin to perceive that there are many things to be learnt before +we come to the end of our history, and that we find ourselves checked +at every step; now listen, for we are coming to something very +important. + +In distant country-seats, where people are thrown entirely upon their +own resources, they must be provided beforehand with all that is +requisite for repairing the building; and there is, accordingly, a +person called a steward, who keeps everything under lock and key, and +distributes to the workmen whatever materials they may require. Thus, +the steward gives tiles to the slater, planks to the carpenter, colors +to the painter, lime and bricks to the mason--the very same lime that +we have in our teeth--in fact, he has got everything that can be wanted +in his storehouse, and it is to him that every one applies in time of +need. + +Now our body also is a mansion, and has its steward too. But what a +steward--how active! what a universal genius I how inefficient by +comparison are the stewards of the greatest lords! He goes, he comes, +he is everywhere at once; and this really, and not as we use the phrase +in speaking of a merely active man: for the _being everywhere at +once_ is in this case, a fact. He keeps everything, not in a +storehouse, but what is far better, in his very pockets, which he +empties by degrees as he goes about, distributing their contents without +ever making a mistake, without stopping, without delaying; and returns +to replenish his resources in a ceaseless, indefatigable course, which +never flags, night nor day. And you can form no idea how many workmen +he has under his orders, all laboring without intermission, all +requiring different things--not one of them pausing, even for a +joke!--not even to say--"Wait a moment;"--they do not understand what +waiting means: he must always keep giving, giving, giving. By and by +we shall have a long account to give of this wonderful steward, whose +name, be it known, if you have not already guessed it, is Blood. + +It is he who, one fine day when he was making his round of the jaws, +found those little germs I spoke of, awake and eager for work; and he +began at once to start them with materials. He knew that phosphorus +and lime were what they needed: he drew phosphorus and lime therefore +out of his pockets,--and, to be very exact, some other little matters +too,--but these were the most important; but I cannot stop to tell you +everything at once. + +Now, where did the blood obtain this phosphorus and lime? + +I expected you to ask this, but if you want everything explained as +we go along, we shall not get very far. In fact, if I answer all your +questions I shall be letting out my secret too soon, and telling you +the end of my story almost before it is begun. + +So be it, however; perhaps you will feel more courage to go on, when +you know where we are going. + +The steward of a country-house distributes tiles, planks, paint, bricks, +lime; but none of these things are his own, as you know; he has received +them from his master: and, in the same way, our steward has nothing +of his own: everything he distributes comes from the master of the +house, and as I have already told you, this master is the stomach. As +fast as the steward distributes, therefore, must the master renew the +stores--and renew them all, for unless he does this, the work would +stop. In proportion as the blood gives out on all sides the contents +of his pockets, the stomach must replenish them, and fill them with +everything necessary, or there would be a revolution in the house. +Now, as there can be nothing in the stomach but what has got into it +by the mouth, it behooves us to put into the mouth whatever is needed +for the supply of our numerous workmen; and this is why we eat. + +I perceive that I have plunged here into an explanation out of which +I shall not easily extricate myself, for I can guess what you are going +to say next. When you began to cut your teeth, you had eaten neither +phosphorus nor lime, as nothing but milk had entered your mouth. + +That is true. Neither then, nor since then, have you eaten those things, +and what is more, I hope you never will. And yet both must have got +into your mouth, for without them your teeth could never have grown. +How are we to get out of this puzzle? + +Suppose now, for a moment, that instead of phosphorus and lime, +thelittle workmen in your jaws had asked the blood for sugar to make the +teeth with. Fortunately this is only a supposition; otherwise I should +be in great fear for the poor teeth: they would not last very long. +Suppose, further, that instead of your eating the lump of sugar which +was destined to turn into a tooth, your mamma had melted it in a glass +of water, and had given it to you to drink; you could not say you had +eaten sugar, and yet the sugar would really have got into your stomach, +and there would be nothing very wonderful if the stomach had found it +out and given it to the blood, and the blood had carried it off to the +place where it was wanted. Now, allowing that the lump of sugar was +very small, and the glass of water very large, the sugar might have +passed without your perceiving it, and yet the tooth would have grown +all the same, and without the help of a miracle. + +And this is how it was. In the milk which you drank as a baby there +were both phosphorus and lime, though in very small quantities. There +were many other things besides; everything of course that the blood +required for the use of its work-people, because at that time the +stomach was only receiving milk, and yet all the work was going on as +usual. + +And therefore, my dear child, whenever in the course of our studies, +you hear me describe such and such a thing as being within us, say +quietly to yourself, "that also was in the milk which nourished me +when I was a baby." + +Of course, the same things are in what you eat now; only now they come +in a form more difficult to deal with, and the labor of detaching them +from the surrounding ingredients is much greater. The whole business +indeed of this famous machine which we are studying consists in +unfastening the links which hold things together, and in laying aside +what is useful, to be sent to the blood divested of the refuse. The +stomach was too feeble in your infancy to have encountered the work +it has to do now. It is for this reason that God devised for the benefit +of little children that excellent nourishment--milk--which contains, +all ready for use, every ingredient the blood wants; and is almost, +in fact, blood ready made. + +Only think, my child, what you owe to her who gave you this nourishment! +It was actually her blood she was giving you; her blood which entered +into your veins, and which wrought within you in the wonderful way +which I have been describing. Other people gave you sugar-plums, kisses, +and toys; but she gave you the teeth which crunched the sugar-plums, +the flesh of the rosy cheeks which got the kisses, and of the little +hands which handled the toys. If ever you can forget this, you are +ungrateful indeed! + +Now, beware of going on to ask me how we know that there are so many +sorts of things in milk, or I shall end by getting angry. Question +after question; why, you might drive me in this way to the end of the +world, and we should never reach the point we are aiming at. We have +already traveled far away from the teeth, concerning which I wanted +to talk to you at this time, but our lesson is nearly over and we have +scarcely said a word about them! One cannot learn everything at once. +Upon the point in question you must take my word; and as you may +believe, I would not run the risk of being contradicted before you, +by those who have authority on the subject. + +Let it suffice you, for to-day, to have gained some idea of the manner +in which the materials which constitute our bodies are manufactured +within us. We have got at this by talking of the teeth; to-morrow, it +may be the saliva, the next day something else. What I have now told +you will be of use all the way through, and I do not regret the time +we have given to the subject. If you have understood that well; the +time has not been lost. + + + +LETTER V. + +THE TEETH _(continued.)_ + +My thoughts return involuntarily to the subject I last explained to +you, my dear child, and I find that I have a great deal to say about +it still. + +You see now, I hope, that we have something else to consult besides +a dainty taste when we are eating; and that if we are to work to any +good purpose we must think a little about this poor blood; who has so +much to do, and who often finds himself so much at fault, when we send +him nothing but barley-sugar and biscuits for his support. It is not +with such stuff as that, as you may well imagine, that he can be enabled +to answer satisfactorily to the constant demands of his little workmen, +and we expose him to the risk of getting into disgrace with them, if +we furnish him with no better provisions. + +And who is the sufferer? Not I who am giving you this information, +most certainly. + +Now, when children hesitate about eating plain food, and fly from beef +to rush at dessert, they act as a man would do who should begin to +build by giving his workmen reeds instead of beams, and squares of +gingerbread instead of bricks. A pretty house he would have of it; +--just think! + +On the contrary, what your mother asks you to eat, my dear little +epicure, is sure to be something which contains the indispensable +supplies for which your blood is craving; for people knew all about +this by experience long before they could explain the why and the +wherefore. But now that you are so much better informed than even the +most learned men were a century ago, pouting and wry faces at table +are no longer excusable, and I should be sadly ashamed of you if I +should hear you continued to make them. + +And this is what I was more particularly thinking of just now, when +I took up my pen again. No doubt it is very amusing to be able to look +clearly into one's frame, and see what goes on inside, but the amusement +anything affords is the least important part of it; you have begun to +find this out already, and you will find it out more and more every +day. What seems to me one of the great advantages of the study we have +begun together is, that at every step you take you will meet with the +most practical and useful instruction, as well as the most unanswerable +reasons for doing what your parents ask you to do every day. + +To obey without knowing why is certainly possible, and may be done +happily enough. But we obey more readily and easily when we understand +the reason for doing so; and a duty which one can satisfy oneself +about, forces itself upon one as a sort of necessity. And what can +throw a stronger light on our duties than a thorough acquaintance with +ourselves? + +It is upwards of two thousand two hundred years ago (and that is not +yesterday, you must own!) since one of the greatest minds of the +world--Socrates--never forget that name--taught his disciples, as a +foundation precept, this apparently simple maxim, "Know thyself." He +meant this, it is true, in a much higher sense than we are aiming at +in these conversations of ours, but his rule is so practical, that +although you have only as yet taken a mere peep into one small corner +of self-knowledge, you find, if I am not much mistaken, that your heart +has beaten once or twice rather faster than it did before. Was I wrong, +in saying from the beginning, that we become better as we grow in +knowledge? Is it not true that you have felt more tenderly than ever +towards her who nourished you with her milk, since I explained to you +the value of milk; and that you have kissed your mother's hand all the +more lovingly since you heard my history of the hand? To tell you the +truth, if you had not done so, I should have been dissatisfied both +with you and myself. + +And wait! While we are talking thus, another thought has come into my +head about hands and nurses, which I must tell you of. + +There is something of the nurse, my child, in those who take the best +fruits of their intellect and heart, and transform them, as it were, +into milk, in order that your infant soul may receive a nourishment +it will be able to digest without too much effort. In this way their +very soul enters into you, and it is but fair that you should reward +them as they deserve. Young as you are, too, you have a recompense in +your power: one more acceptable even than Academic prizes--of which +it is indispensable not to be too avaricious--you can give them your +love. + +Besides, it is not only hands but heads that are at work for you, and +of these many more than you suppose; and your debt of gratitude is as +much due to the one as to the other. + +Perhaps my first letter may have led you to suppose that I was inclined +to laugh at what I called learned men; and they are perhaps a little +to blame for not thinking often enough about little girls; but +nevertheless these men are of the greatest use to them in an indirect +way. You owe them much, therefore, and without them could have known +nothing of what I am teaching you. It is very grand for us, is it not, +to know that there is phosphorus and lime in our teeth? But it took +generations of learned men, and investigations and discoveries without +end, and ages of laborious study, to extract from nature this secret +which you have learnt in five minutes. And whatever others you may +learn hereafter, remember that it is the same story with all. While +profiting, therefore, at your ease, by all these conquests of science, +I would have you hold in grateful recollection those who have gained +them at so much cost to themselves: almost always at the expense of +their fortune, sometimes at the peril of their lives. + +There they are, observe, a little knot of men with no sort of outward +pretension. They speak a language which scares children away. They +weigh dirty little powders in apothecaries' scales; steep sheets of +copper in acid-water; and watch air-bubbles passing through bent glass +tubes, some of which are as dangerous as cannon balls. They scrape old +bones, and slice scraps no bigger than a pin's head. They keep theireyes +fixed for hours upon things they are examining through microscopes +of a dozen glasses, and when you go to see what they are looking at, +you find nothing at all. To see them at work, in what they call their +laboratories, you would say that they were a set of madmen. But at the +end, it is found, some fine day, that they have changed the face of +the earth; have worked revolutions before which emperors and kings bow +in respect; have enriched nations by millions at a time; have revealed +to the human race, divine laws of which it had hitherto been ignorant; +finally, have furnished the means of teaching little boys and girls +some very curious things, which will make them more agreeable as well +as reasonable. And this is a benefit not to be despised, since these +children are destined one day to become fathers and mothers, and so +to govern the next generation; and the better they themselves are +instructed, the better this will be done. + +But now let us go back to the poor teeth, whom we seem to have forgotten +altogether. However, we knew very well that they would not run away +meantime. + +I told you before that it was their business to dress and prepare +whatever was presented to them, but the reception they bestow is not +one which would suit every body's taste, for it consists in being made +mince-meat of And in order to do their work in the best way possible +they divide their labor; some cut up, others tear, and others pound. + +First, there are those flat teeth in front of the two jaws, just below +the nose. Touch yours with the tip of your finger; you will find that +they terminate in sharp-edged blades, like knives. These are called +_incisors,_ from the Latin word _incidere,_ which means to cut, and it +is with them we bite bread and apples, where the first business is to +cut. It is with the same teeth that lazy little girls bite their thread, +when they will not take the trouble to find their scissors; and, by the +by, this is a very bad trick, because by rubbing them one against +another in this manner we wear them out, and, as you will soon discover, +worn-out teeth never grow again. + +The next sort are those little pointed teeth, which come after the +_incisors,_ on each side of both jaws. You will easily find them; +and if you press against them a little, you will feel their points. +If we call the first set the knives of the mouth, we may call these +its forks. They serve to pierce whatever requires to be torn, and they +are called _canine_ teeth, from the Latin word _canis_, a dog, because +dogs make great use of them in tearing their food. They place their paws +upon it, and plunging the canine teeth into it, pull off pieces by a +jerk of the head. Look into the mouth of papa's dog: you will recognize +these teeth by their rather curved points. They are longer than the +rest, and are called fangs. I do not know, after all, why they have +chosen to name these teeth _canine_, as all carnivorous animals have the +same fangs, and in the lion, the tiger, and many other species, they are +much more developed and sharper than in the dog. In cats they are like +little nails. However, the name is given, and we cannot alter it. + +The last teeth, which are placed at the back of the jaw, are called +molars, from the Latin word _mola_, which means a millstone. + +You must be prepared to meet with several Latin words as we go on; but +never mind; this will give you the opportunity of learning a little +Latin, and so of keeping your brother in order, if he ever looks down +upon you because he is learning Latin at school. Formerly, all learned +men wrote in Latin, and as they ruled supreme in all such subjects as +those we are discussing, they gave to everything such names as they +pleased, without consulting the public, who did not just then trouble +their heads about the matter. Now they give Greek names, which can +hardly be called an improvement; but if they ever wish to attract the +attention of little girls they must translate their hard words into +our own language. + +To return to our grinders: they perform the same office as a miller's +millstone; that is to say, they grind everything that comes in their +way. These teeth have flat, square tops, with little inequalities on +the surface, which you can feel the moment you lay your finger on them. +These are the largest and strongest of the three sets, and with them +we even crack nuts, when we prefer the risk of breaking our teeth to +the trouble of looking for the nut-crackers! + +Now, I will answer for it that you cannot explain to me why we always +place what is hard to break between the _molars,_ and never employ +the _incisors_ in the work? And yet everybody does this alike--from +the child to the grown-up man--and all equally without thinking of +what they are doing. + +I will tell you the reason, however, if you will first tell me why, +when you are going to snip off the tip of your thread (which offers +very little resistance), you do it with the point of your scissors; +whereas you put any tough thing which is likely to resist strongly (a +match, for instance) close up to their hinge; particularly if you have +no scruple about spoiling the scissors, by the way! + +If you were a grown-up lad, and I were teaching you natural philosophy, +I should have here a fine opportunity for explaining what is called +_the theory of the lever_. But I think _the theory of the lever_ would +frighten you; so we must get out of the difficulty in some other way. + +I find, however, that I have been joking so much as I went along, that +I have but little space left, and feel quite ashamed of myself. We +seem quite unlucky over these teeth. + +I have already been scolded by people who are not altogether wrong in +accusing me of losing my time in chattering, first of one thing and +then of another. They complain that by thus nibbling at every blade +of grass on the way-side we shall never get to the end of our journey; +and there is some truth in what they say. Still, I will whisper to you +in excuse that I thought we might play truant a little bit while we +were on familiar ground, where naturally you were sure to feel a +particular interest in everything. The hand, the tongue, the +teeth--these are all old friends of yours--and I thought you would +like to hear all about them. By-and-bye we shall be in the little black +hole, and then we shall get on much more rapidly. + + + +LETTER VI. + +THE TEETH _(continued)._ + +I left off at the _molars_, which are the teeth one selects to +crack nuts with; and if I remember rightly, we talked about different +ways of cutting with scissors. + +Let us look at the subject from a distance, that we may understand it +more clearly. Let us imagine a horse drawing a heavy cart slowly along. +Ask it to gallop, and it will answer, "With all my heart! but you must +give me a lighter carriage to draw." And now fancy another flying over +the ground with a gig behind it. Ask it to exchange the gig for the +cart, and it will say, "Yes; but then I shall have to go slowly." + +Whereby you see that with the same amount of strength to work with, +one has the choice of two things: either of conquering a great +resistance slowly, or a slight one quickly. + +And it is partly on this account, dear child, that I teach you so +gradually; for young heads, fresh to the work, are less easily drawn +along than others, and have but a certain amount of strength. + +Hitherto all has been clear as the day. Now take your scissors in your +left hand; hold the lower ring of the handle firmly between your thumb +and closed hand, so that the blade shall remain straight and immovable: +then with your other hand cause the upper ring to go up and down, and +watch the blade as it moves. The whole of it moves at once, and is put +in motion by the same power--viz., your right hand. But the point makes +a long circuit in the air, while the hinge end makes only a very little +one--indeed, moves almost imperceptibly: and, as you may imagine, a +different sort of effort is required from the motive power (your hand) +according as resistance is made at the point or at the hinge. The point +goes full gallop: it is the horse in the gig; the light work is for +him. The hinge moves slowly; it is the cart-horse, and takes the heavy +labor. + +I hope I have made you understand this, for it explains the cracking +of our nut, though you may not suspect it. Move your scissors once +more in the same way. Now, you have before you the pattern of the two +jaws on one side of your face, from the ear to the nose; the upper +one, which never moves (as you may convince yourself by placing a +finger on your upper lip when you either speak or eat), and the lower +one which goes up and down. Two pairs of scissors set points to points +give you the whole jaw. The _incisors_ are at the points, they +gallop up and down, and are worthless for doing hard work; the +_molars_ are at the hinges, and move slowly; and if anything tough +has to be dealt with, it comes to them as a matter of course; hence +they are the nutcrackers. You must own that it is pleasant to reflect +thus upon what we are doing every day, and the next time you see a +stonemason moving stones of twenty times his own weight with his iron +bar, ask your papa to explain to you the principle of the lever. After +what I have told you, you will understand it very readily, or at least +enough of it to satisfy your mind. + +But, besides this power of moving up and down, the lower jaw possesses +another less obvious one, by means of which it goes from right to left. +This is precisely what naughty children make use of when they grind +their teeth: not that I mean this remark for you, for I have a better +opinion of you than to suppose you do such things. Those who make such +bad use of their jaws deserve to lose the power of ever moving them +thus, and then they would find themselves sadly at a loss how to chew +their bread--for their _molars_ would be of but little service +to them in such a case; as it is chiefly by this second action of the +jaw that the food is pounded. Try to chew a bit of bread by only moving +your jaw up and down, and you will soon tire of the attempt. + +One word more to complete my description of the teeth: that portion +of them which is in the jaw is called the _root_; and the _incisors_, +which cannot work hard because, like the gig-horses, they have but +little resisting power, possess only small and short roots; whereas the +_canines,_ whose duty it is to tear the food sideways, would run the +risk of being dragged out and left sticking in the substances they are +at work upon, if they were not well secured; these, therefore, have +roots which go much deeper into the jaw, and in consequence of this they +give us more pain than the others when the dentist extracts them: those +famous _eye-teeth_, which so terrify people on such occasions, are the +_canines_ of the upper jaw, and lie, in fact, just below the eye. + +The _molars_ meanwhile would be in danger of being shaken in the +sideway movement, while chewing: so they do as you would do if you +were pushed aside. Now you would throw out your feet right and left +in order to steady yourself, and thus the molars, which have always +two roots, throw them out right and left for the same purpose. Some +have three, some four, and they require no less for the business they +have to do. + +Above the root comes what is called the crown; that is the part of the +tooth which is exposed to the air; the part which does the work, and +which bears the brunt of all the rubbing. Now, however hard it may be, +it would soon end in being worn out by all this fun if it were not +covered by a still harder substance, which is called _enamel_. +The _enamel_ which forms the coating of china plates, and which +you can easily distinguish by examining a broken plate, will give you +a very exact idea of it. It is this enamel which gives the teeth the +polish and brilliancy we so much admire, and it is desirable to be +very careful of it, not out of vanity, though there is no objection +to a little vanity on the subject, but because the enamel is +the protector of the teeth, and when that is destroyed, you may say good- +bye to the teeth themselves. All acids eat into the enamel, as vinegar or +lemon-juice does into marble; and one of the best means of preserving +this protecting armor of the teeth is never to eat the unripe windfalls +of fruit, which I have seen unreasonable children pick up in orchards +and devour so recklessly. They give sufficient warning, by their +acidity, that they are not fit for food, and when this warning is +neglected, they take their revenge by corroding the enamel of the +teeth; not to speak of the disturbance which they afterwards cause in +the poor stomach. + +I said that without this coating of enamel, the teeth would be +prematurely worn out, the reason of which is, that the teeth have not +the property of growing again, as the nails and hair have. When those +little germs of which I spoke when we began to describe the teeth, +have finished their work, they perish and fall out, like masons who, +when they have built the house, take their departure forever. + +But the "forever" wants explanation. For such stern conditions would +fall hard on very little children, who, not having come to their reason, +cannot be expected to understand the great value of their teeth, and +take all the care they need of them. So to them _a second_ chance +is given. + +Your first teeth, the _milk-teeth_, as they are called, count for +nothing: they are a kind of specimen, just to serve while you are very +young. + +When you are approaching what is called the age of reason, (and this +word implies a great deal, my dear child,) the real teeth, the teeth +which are to serve you for life, begin to whisper among themselves, +"Now, here is a little girl who is becoming reasonable, and who will +soon, or else never, be fit to take charge of her teeth." No sooner +said than done: other masons set to work in other cells, placed under +the first set, and as the permanent teeth keep growing and growing, +they gradually push out the milk-teeth, which were only keeping their +places ready for them till they came. + +This is just your case at present, and you now understand your +responsibility, and how necessary it is to preserve those good teeth +which have placed so generous a confidence in your care of them, and +which, once gone, can never be replaced. + +You have no loss by the exchange; you had twenty-four at first, you +will now have twenty-eight. Twenty-eight, did I say? nay, you will +have thirty-two; but the last four will come later still. The last +_molars_ on each side, above and below, in both jaws, will not +make their appearance till you are grown up. They are a fastidious and +timid set, and will not run any risks; and they are called +_wisdom-teeth_, because they do not appear till we are supposed +to have arrived at years of discretion. Some people do not cut them +before they are thirty, and you will agree that, if they have not +become wise by that time, they have but a very poor chance of ever +being so! + +There is much more still to be said about the teeth; but I think I +have told you quite enough to teach you the importance of these little +bony possessions of yours, which children do not always value as they +deserve, and whose safety they endanger as carelessly as if they had +fresh supplies of them ready in their pockets. If so many skilful +contrivances have been devised for enabling us to masticate our food +properly, it is clear that this process is not an unimportant one. +Those, therefore, who swallow a mouthful after two or three turns, +forget that they are thereby forcing the stomach to do the work the +teeth have neglected to do, and this is very bad economy, I can assure +you. You will see hereafter, when we speak about animals, that by a +marvellous compensation of nature, the power of the stomach is always +great in proportion to the _in_efficiency of the teeth, and that +by the same rule, it is weakest when the jaws are best furnished. Now, +no jaw is more completely furnished than the human one; it is clear, +then, that it should do its own work and not leave it to be done by +those who are less able: and the little girl who, in order to finish +her dinner more quickly, shirks the use of her teeth, and sends food, +half chewed, into her stomach, is like a man who, having two servants, +the one strong and vigorous, the other feeble and delicate, allows the +first to dawdle at his ease, and puts all the hard work on the other. +He would be very unjust in so doing, would he not? And as injustice +always meets with its reward, his work is sure to be badly done. + +Now, the work in question consists in reducing what we eat into a sort +of pulp or liquid paste, from which the blood extracts at last whatever +it requires. But the teeth may bite and tear the materials as they +please, they can make nothing of them but a powder, which would never +turn into a pulp, if during their labors they were not assisted by an +indispensable auxiliary. To make pap for infants what do we add to the +bread after it is cut in little bits? Without being a very clever cook, +you will know that it is water which is wanted. And thus, to assist +us in making pap for the blood, Providence has furnished us with a +number of small spongy organs within the mouth, which are always filled +with water. These are called _salivary glands_. This water oozes +out from them of itself, on the least movement of the jaw, which presses +upon the sponges as it goes up and down. The name of this water, as +I need scarcely tell you, is _saliva_. + +When I call it water, it is not merely from its resemblance; _saliva_ is +really pure water with a little _albumen_ added. Do not be afraid of +that word--it is not so alarming as it appears to be. It means simply +the substance you know as the _white of egg_. There is also a little +soda in the water, which you know is one of the ingredients of which +soap is made. And this explains why the saliva becomes frothy, when the +cheeks and tongue set it in motion in the mouth while we are talking; +just as the whites of egg, or soapy water, become frothy when whipped up +or beaten in a basin. + +But the albumen and the soda have not been added to the saliva, in our +case, merely to make it frothy; that would have been of very little +use. They give to the water a greater power to dissolve the food into +paste, and thus to begin that series of transformations by which it +gradually becomes the fine red blood which shows itself in little drops +at the tip of your finger when you have been using your needle +awkwardly. + +When once minced up by the teeth and moistened by the saliva, the food +is reduced to a state of pulp, and having nothing further to do in the +mouth, is ready to pass forward. But getting out of the mouth on its +journey downwards is not so simple an affair as getting into it by the +_front door_, as it did at first. Swallowing is in fact a complicated +action, and not to be explained in half a dozen words, and I think we +have already chatted enough for to-day. I only wish I may not have tired +you out with these interminable teeth! But you may expect something +quite new when I begin again. + + + +LETTER VII. + +THE THROAT. + +You remember a certain door-keeper, or porter, of whom we have already +spoken a good deal, who resides in the mouth--the sense of taste, I +mean? + +Well, it is a porter's business to sweep out the entrance to a house, +and you may always recognize him in the courtyard by his broom. + +And accordingly our porter too has a broom specially placed at his +service, namely, the tongue; and an unrivalled broom it is--for it is +self-acting, never wears out, and makes no dust--qualities we cannot +succeed in obtaining in any brooms of our own manufacture. + +When the time has come for the pounded mouthful (described in the last +chapter) to travel forward (the teeth having properly prepared it), +the broom begins its work; scouring all along the gums, twisting and +turning right and left, backwards and forwards, up and down; picking +up the least grains of the pulp which have been manufactured in the +mouth; and as the heap increases, it makes itself into a shovel--another +accomplishment one would scarcely have expected it to possess. What +it gathers together thus, rolls by degrees on its surface into a ball, +which at last finds itself fixed between the palate and the tongue in +such a manner that it cannot escape; at which moment the tongue presses +its tip against the upper front teeth, forms of itself an inclined +plane, and--but stop! we are getting on too fast. + +At the back of the mouth, (which is the antechamber, as we said before,) +is a sort of lobby, separated from the mouth by a little fleshy +tongue_let_, suspended to the palate, exactly like those tapestry +curtains which are sometimes hung between two rooms, under which one +is enabled to pass, by just lifting them up. + +If this lobby led only from the mouth to the stomach, the act of +swallowing would be the simplest thing in the world; the tongue would +be raised, the pounded ball would glide on, would pass under the +curtain, and then good-bye to it. Unfortunately, however, the architect +of the house seems to have economized his construction-apparatus here. +The lobby serves two purposes; it is the passage from the mouth to the +stomach, as well as from the nose to the lungs. + +The air we breathe has its two separate doors there--one opening +towards the nose, the other towards the lungs; through neither of which +is any sort of food allowed to pass. But, as you may imagine, the food +itself knows nothing of such spiteful restraints, and it is a matter +of perfect indifference to it through which of the doors it passes. +Not unlike a good many children who, though they are reasonable +creatures, will push their way into places where they have been +forbidden to go; and who can expect a pulpy food-ball to be more +reasonable than a child? It was necessary, therefore, so to arrange +matters that there should be no choice on the subject; that when the +food-ball got into the lobby it should find no door open but its own, +namely, that which led to the stomach. And that is exactly what is +done. + +You have not, perhaps, remarked that in the act of swallowing, something +rises and contracts itself at the same moment in your throat, producing +a kind of internal convulsion which jerks whatever is inside. People +do not think about it when they are eating, because it is an involuntary +action, and their attention is otherwise engaged. + +But try to swallow when there is nothing in your mouth, and you will +perceive what I mean at once. + +Now, imagine our lobby at the back of the throat as a small closet, +with a doorway in its wall, half-way up, the doorway being closed by +a curtain. In the ceiling is a hole, which leads to the nose; in the +floor two large tubes open out; the front one leading to the lungs, +the one behind, to the stomach. + +Now swallow, and I will tell you what happens. The curtain rises up +and clings to the ceiling, and thus the passage to the nose is stopped +up. The lung-tube rises along the wall, and hides itself under the +door, contracting itself, and making itself quite small, as if it +wished to leave plenty of room for the mouthful of food which is about +to pass over it; and, for still greater security, at the very moment +it rises, it pushes against a small trap-door which shuts up its mouth. +No other road remains, therefore, but through the tube which leads to +the stomach; the pulpy mouthful drops straight therein, without risk +of mistake, and when it is once there, everything readjusts itself as +before. + +These are very ingenious contrivances, and I will venture to say that +if we would but study the wonders of the marvellous and varied machinery +which is constantly at work in our behalf within us, we should be much +better employed than in learning things from which no practical good +can be derived. Moreover, we should be ashamed to trust, like the lower +animals, only to our instinct, (which, after all, is much less developed +in us than in them,) for blindly escaping the thousand chances of +destruction that beset a structure so fragile and delicate in its +contrivances as the human body. Besides, it is not only our own +machinery that is entrusted to us, we are liable to be responsible for +that of others, whose development it is our duty to guard and watch; +and how can we do this with a safe conscience, if we are ignorant of +the construction, the action, the laws of all sorts which the great +Artificer has, so to speak, made use of in forming our bodies? + +When you, in your turn, are a mother, you dear little rogue, who sit +there opening wide your bright eyes, and not comprehending a word of +what I am saying, you will be glad that you were taught when you were +little, how your own little girl ought to be managed. You will find +a hundred opportunities of making good use, in her behalf, of what you +and I are learning together, and in the meantime there is no reason +why you should not yourself profit by the knowledge you have gained. + +I am quite sure, for instance, that in repeating to your child the +simple rule of politeness, with which everybody is acquainted, "_Never +talk when you are eating_," you will be very careful to add, "_and +especially when you are swallowing_," for reasons I am about to detail. + +When we want to speak we have to drive the air from the lungs into the +mouth, and our words are sounds produced by this air as it passes +through. This is the reason why I advise you to go on gently, and make +the proper stops in reading aloud: to _take breath_, in fact, as +it is called; otherwise, breath would all at once fail you, and you +would be obliged to stop short in the middle of a sentence and wait +like a simpleton till you had refilled the lungs with air by breathing. +It was for this purpose, also, and not for mere economy's sake, as you +may have thought, that the little cross-road of four doors has been +placed at the back of the mouth, enabling it to communicate at pleasure +with either the lungs or the stomach. It is a dangerous passage for +food-parcels making their way to the stomach; but if you could +substitute for it, as it may have occurred to you to do lately, a +simple tube going directly to the stomach,--behold! you would find +yourself dumb;--a serious misfortune, eh? for a little girl! But come, +I am quizzing too much, so console yourself. I know many grown-up +people who would be at least as sorry as yourself. + +To return to our subject. We have said that, in order to guard against +accidents, the lung-tube is closed at the moment we are about to +swallow. But if by any unlucky chance the air is coming up from the +lungs at the same moment, it must have a free passage. Its tube cannot +help returning to its place; the little trap-door which shuts up the +opening opens whether or no, and then adieu to all the precautions of +good Mother Nature! The mouthful when it drops, falls outside of its +proper tube--that is to say, into the other, which is exactly in front +of it, and we find that we have _swallowed the wrong way_. + +You know what happens in such a case. You cough and cough till you are +torn to pieces, till you grow scarlet, or even blue in the face; till +you lose your breath; till your body trembles; till your eyes start +out of their sockets. Let who will be there, there is no resource but +to hide your face in your handkerchief. The tube, which was only made +for the passage of air, on finding an intruder forcing an entrance, +does its utmost to drive it back through the door. Then the lungs, +which would be destroyed by its getting to them, come to the assistance +of the faithful servant who is struggling for their protection: they +agitate themselves violently, and send forth gusts of air which drive +all before them. Thence arises the cough, and by this means at last +the enemy is thrust out of the mouth, like dust before the wind. And +it is only when the passages are cleared that the storm subsides. But +the commotion is no laughing matter, I assure you; for if one had +swallowed a little _too far_ the wrong way, or if the substance +swallowed had been too heavy for the air-tube, aided by the lungs, to +eject within a certain time, death would have ensued: instances of +which are by no means unknown. Nature does nothing in vain; this is +no case of a man frightened by a mouse. When you find your whole being +concentrating its efforts to one point, and betraying such distress, +at an accident apparently so trifling, you may be sure there is danger, +and real danger too; and if you doubt it, that makes no +difference--happily for you. + +Now you have learned why little girls should not attempt to talk and +swallow at the same time, and, I may add, still less laugh; for +laughingis a kind of somersault, performed by the lungs, and is always +accompanied by the ejectment of a great deal more breath than is +necessary in speaking, so that the jerks it occasions derange still +more the wise provisions made to protect life whenever we swallow +anything, and therefore we are more apt to swallow the wrong way while +laughing than while speaking. + +Need I say that we ought equally to guard against making others laugh +or talk; or exciting, or frightening them, while they are swallowing; +in short, avoid doing anything to create a sudden shock which might +suddenly force the air out of their lungs, and cause them in the same +manner to swallow the wrong way? Politeness requires this from us, and +what I have now said will fix the lesson still more strongly on your +mind. What would become of you if you were to see a person die in your +presence in consequence of some foolish joke, however apparently +innocent? + +Not to conclude with so painful a picture, I will, before we part, +give you the right names of the _curtain_, the _lobby_ or _closet_, and +the _tubes_ of which we have been speaking. + +The curtain is called the _Soft Palate_. + +The lobby, the _Pharynx_. + +The tube which leads to the stomach, the _Aesophagus_. + +The tube leading to the lungs, the _Larynx_. + +The opening of this tube is the _Glottis_, and the little trap-door +which closes it when one swallows, is the _Epiglottis_. + +You must excuse my attempting to explain the meanings of all these +names; it would take me too long to do so. After all, the mere names +are nothing. If I have succeeded in making you understand how all the +different parts act, you may call them what you like. + +Here we will rest. We are now on our way to where we shall see the +large apartments, and be introduced to the master, that head of the +house, whom no one can approach without so many ceremonies. + + + +LETTER VIII. + +THE STOMACH. + +Once in the _oesophagus_ (you remember this is the name of the tube +which leads to the stomach), the mouthful of food has nothing to do but +to proceed on its way. All along this tube there is a succession +of small elastic rings, [Footnote: Properly, _contractile circular +fibres_.] which contract behind the food to force it forward, and +widen before it to give it free passage. They thus propel it forward, +one after another, till it reaches the entrance to the stomach, into +which the last ring pushes it, closing upon it at the same time. + +Have you ever observed a worm or a leech in motion? You see a successive +swelling up of the whole surface of its body, as the creature gradually +pushes forward, just as if there was something in its inside rolling +along from the tail to the head. Such is precisely the appearance which +the _oesophagus_ would present to you, as the food passes down it, if +you had the opportunity of seeing it in action; and this has been called +_the vermicular movement_, in consequence of its resemblance to the +movement of a worm. + +Here I wish to draw your attention to the very important fact, that +this movement is in one respect of a quite different nature from that +of your thumb when you take hold of a bit of bread, or that of your +jaw when you bite with your teeth, or of your tongue, &c., when you +swallow. All these actions belong to yourself, to a certain extent; +they are voluntary, and under your own guidance; that is, you may +perform them or not, as you choose. There is a constant connexion +between you and them, and you knew what I meant at once as I named +each of them in succession. But in speaking of this other movement we +enter upon another world, of which you know nothing. Here is the black +hole of which I spoke. The little rings of the _oesophagus_ perform +their work by themselves, and you have no power in the matter. Not +only do they move independently of you, but were you to take it into +your head to stop them, it would be about as wise a proceeding as if +you were to talk to them. We will speak hereafter, in another place, +of these impertinent servants, who do not recognise your authority, +and with whom we shall have constantly to do, throughout what remains +to be said on the subject of eating. The truth is, your body is like +a little kingdom, of which you have to be the queen, but queen of the +frontiers only. The arms, the legs, the lips, the eyelids, all the +exterior parts, are your very humble servants; at your slightest bidding +they move or keep still: your will is their law. But in the interior +you are quite unknown. There, there is a little republic to itself, +ruling itself independently of your orders, which it would laugh at, +if you attempted to issue them. + +This republic, to make use of another metaphor, is the kitchen of the +body. It is there they make blood, as they know how; putting it to all +sorts of uses for your advantage, it is true, but without your consent. +You are in the position of the lady of a house whose servants have +shut the door of the kitchen in her face that they may carry on their +business after their own fashion, leaving only the housemaid and +coachman at her command. It may be humiliating, perhaps, to be thus +only partially mistress at home; but what can you do, my little +demi-queen? I will tell you: make up your mind to govern the subjects +under your orders as wisely as possible; and, as to the rest, be content +with the only resource left you: viz., that of looking in at the window +of the kitchen to see what goes on there! + +The stomach is the head cook: the president of the internal republic. +He has charge of the stoves; the whole weight of affairs is on his +hands, and he provides for the interests of all. Aesop taught us this, +long ago, in his fable of "The Belly and Members." [Footnote: La +Fontaine's translation is quoted in the French original, where the +name of the fable is "_Messer Gaster_," a more correct title than our +own. _Gaster_ is a Greek word signifying stomach; and it is strictly +_the stomach_ which is _meant_ in the fable. From this comes, too, the +medical term _gastritis_, the name of a disease of the stomach.--TR.] It +is a very good fable, and was wisely appealed to once by a Roman Consul +to appease a disturbance in the State. But the application was not quite +fair in one respect; and since I have started the subject, I will +satisfy myself by explaining to you where it was wrong. The time will +not be wasted, for this fable has furnished information to a great many +people about the economy of their insides, and possibly to you; and I +should like you to know the exact truth of all the particulars alluded +to. Whether Aesop understood them all, I cannot pretend to say; but the +application by the old Roman to the quarrel between the big-wig senators +and the people was on one point decidedly unjust; for there was, as far +as facts are concerned, something to be said on behalf of the stomach, +which Consul Menenius seems not to have thought of. + +When you come to this part of the Roman history you will learn that +the Roman Senate was a large and fat stomach, which did, it is true, +furnish good nourishment to the other members of the State, but kept +the best share for itself. We may say this now without risk of offence, +it having been dead for so long a time. Our stomach is the leanest, +slightest, frailest part of our body. It is master in the sense in +which it is said in the Gospel, "Let him that is first among you be +the servant of the others." It receives everything, but it gives +everything back, and keeps nothing, or almost nothing, for itself. +Between ourselves, Consul Menenius, the advocate of the Senate, had +no business to talk to the poor wretches at Rome of any comparison +between their government and so careful an administrator of the public +good as a human stomach. He should have taken his subject of comparison +from the families of geese or ducks--animals which have no teeth. These +have strong, well-grown stomachs--true Roman senators--whose stoutness +is in proportion to the work given them to do. But man provides his +with work already prepared by chewing, supposing him to have had the +sense to chew it, of course. It was not from a comparison with man, +therefore, that Menenius ought to have got his boasted apologue, which +was but a poor jest on the subject. + +You did not expect, my dear, to come in for a lesson on Roman History +in a discussion on the stomach. But the study of nature is connected +with everything else, though without appearing to be so, and I was not +sorry to give you, incidentally, this proof of the unexpected light +which it throws, as we go along, upon a thousand questions which appear +perfectly foreign to it. Look, for example, at this old fable cited +by Menenius. For the two thousand years and upwards that it has been +in circulation, troops of historians, poets, orators, and writers of +all kinds, have passed it forward from one to the other, without having +troubled themselves to investigate the laws of nature in connection +with the stomach; therefore, not one, that I am aware of, has observed +this small error, so trifling in appearance, so important in reality, +which nevertheless is obvious to the first young naturalist who thinks +the matter over. + +But enough of the Romans. Let us return to our master--the head cook, +if you choose to call him so. + +I was telling you just now that he managed the stoves, and you may +have thought that I was merely using similes, as I am apt to do. But +not so: it is quite true that he cooks; and so now tell me, if you +can, whence he gets his fire to cook with, or rather, to speak more +correctly, who gives it to him? + +Now you are quite puzzled, so I must help you out. + +In the mansion we were talking about some time ago, to whom would anyone +who wanted to light a fire, apply for wood? + +I think you can answer this yourself, for you cannot have forgotten +our famous steward, who gives everything to everybody. But, you will +wonder, I dare say, how the blood can carry wood in his pockets. +Wood? Ay, and real wood too, as we shall soon see: but it is not wood +we are talking about now. The blood has something more to the purpose +than wood in his pockets, for he has heat ready made. So when the +stomach wishes to set to work, it appeals to the blood, which comes +running from all parts of the body, and heats it so effectually that +everything within is really and actually cooked. This is why one feels +a sort of slight shudder down the back when the stomach has a great +deal to do at once, for the blood being called for in a hurry, comes +rushing along in great gushes, and carries with it the heat from the +other parts of the body. + +It is for this reason, too, that it is so dangerous to bathe when the +stomach is at work cooking, because the cold of the water drives +suddenly back all the blood which has accumulated around the little +saucepan, and this causes such a shock in the body that people often +die of it. + +Do not ask me, to-day, where this heat of the blood comes from; we +will speak of that hereafter. But I may tell you at once that our dear +steward is not a bit cleverer in this matter than other people, and +obtains his heat, like the humblest mortal, by burning his wood. Do +not puzzle yourself to find out how. Enough that he burns it as we do, +and by a similar process. + +Well, in one way or another, the master cook has his fire at command. +You know also, already, what it is he has to get cooked; namely, the +pulpy stew, which has begun in the mouth by chewing, and which it is +his business now to finish perfectly. Now see what a cook does who has +got her stew over the fire. She turns and turns it again and again, +and shakes the saucepan from time to time, that the ingredients may +be more thoroughly mixed up together; and this is precisely what is +done by the stomach; for all the time that the cooking is going on, +he swells and contracts himself alternately, after the fashion of those +rings of the _oesophagus_ we were talking about, tossing and tumbling +the food from one side to another, so as to knead it, as it were. + +Again, the cook adds water to her stew from time to time to keep it +moist; and so the stomach pours constantly upon his stew a liquid, +which contains a great deal of water, and which flows in from a quantity +of little holes, sunk in his delicate coats. + +What more? + +The cook puts in a little salt: and this the stomach takes care not +to forget either, for he is a cook who understands his business. In +the liquid of which I am speaking, there is, if not exactly salt as +one sees it at table, at all events the most active part of salt, that +which possesses in the highest degree the property of reducing +everything we eat to a paste; and this is the real reason why we find +all food so insipid which has not been seasoned with salt. As salt +contains a principle essential to the work to be done by the stomach, +some method had to be devised to induce us to provide him with it, and +this method the porter up above has hit upon. He makes a face if we +offer him anything without a little salt on it, as much as to say--"How +can you expect them to cook you properly down below, my good friend, +if you don't bring them proper materials?" + +Upon which hint men have always acted from the beginning; and as far +as we can trace history back, we find them mixing salt with their food, +though without knowing the real reason why. It is the same, too, with +the lower animals. They know nothing of the matter either, but this +does not prevent their having a natural relish for salt, as any one +will tell you who has the charge of cattle; for their stomachs require +for their cooking the very same seasoning as our own, and therefore +their porter above has received the same orders. + +Salt is not the only thing, however, that exists in that liquid in the +stomach. Learned men, after making minute researches, have found in +it another equally powerful material, which is also found in milk. +Therefore cheese, which contains this material as well as salt, is +quite in its place at the end of dinner. It furnishes reinforcements +for the stomach in cooking, and this is why you so often hear people +say that a little cheese helps the digestion. + +The _digestion_! Yes, that is the word I ought to have begun with. +It is the real name of all this cooking; an operation after which I +would defy you to recognise the nice little cakes you have eaten, any +better than your mamma can trace her pretty rosy-cheeked apples in the +jelly which she left on the fire two hours ago. The stomach, as you +see, is very busy quite as long a time as that, and if we have to be +very careful (as I pointed out before) not to disturb him too suddenly +in his work after dinner, it is also important that we should not, +while at dinner, give him more work to do than he is capable of doing. +Although he is the master, he is but a puny fellow, as I have already +pointed out; nevertheless, he works conscientiously, because he knows +that the life of the whole body depends upon his exertions. Some people +even say that in spite of his leanness he strips himself, at each +digestion, of his interior skin, which he sacrifices to his work, and +the fragments of which tend to increase and improve the stew which is +entrusted to his care. Think of this, my dear, whenever a greedy fit +comes over you, and recollect that such a disinterested public +functionary deserves some consideration. Besides, there is serious +danger, quite apart from any question of injustice, in overwhelming +him with work. If your legs are wearied out, you have it in your power +to lie in bed. If your arm is in pain, you can keep it at rest. But +your stomach is like those poor people who have to support their +families by the labor of each day. He, too, labors for others: he has +no right to rest, no right to be ill, therefore; and when he begins +to fail, woe betide you--you will have enough of it. + +Children who have learnt nothing may laugh at all this, but you, my +dear, are beginning to know something, and "science constrains," +_i.e._ it has its claims and requirements. It requires you, to-day, not +to be greedy, to-morrow, something else, and so on, continually, until +you have become quite reasonable and wise. I am sorry for you if this +vexes you, but it was your own wish to learn, and _science constrains_. +Indeed, I will whisper to you in confidence that this is the best excuse +people who are unwilling to learn have to offer for refusing. They do +not know what learning may lead to, and what a pity it would be if they +could no longer be greedy, or ill-natured, or selfish. What would become +of us all in such a case? + + + +LETTER IX. + +THE STOMACH--_(continued)_. + +We made a very long story of the stomach last time, my dear child; +and, after all, I see that there was one thing I forgot to tell +you--viz., what it is like. + +Have you ever seen a bagpiper, I wonder? A man who carries under his +arm a kind of large dark brown bag, which he fills with air by blowing +into it, and out of which he presently forces the same air into a +musical pipe by pressing it gently with his elbow. If you never saw +such a thing, it is a pity; first, because the bagpipe was the national +instrument of our ancestors the Gauls, and is religiously preserved +as such by the Scotch Highlanders and the peasants of Brittany--(two +remnants of that illustrious race, whose history I recommend to your +careful perusal some day); secondly, and it is this fact which has the +greatest interest for us just now, because that large bag, which is +the principal part of the instrument, gives you a very exact idea of +your stomach; for in fact it really and truly _is_ a stomach itself, and +moreover, the stomach of an animal whose interior formation resembles +yours very, very much. + +And who do you suppose is this audacious animal, which presumes to +have an inside so like that of a pretty little girl? Really, I am half +ashamed to name him, for fear you should be angry with me for doing +so. It is--it is the pig! The resemblance is not exactly a flattering +one to you, perhaps, but we are all alike, and it would be worse than +foolish to grumble at being created as we are. Moreover, there is one +difference; the pig, who thinks of nothing but eating, has a very much +larger stomach than we have, which is some consolation, at any rate. + +Place the palm of your right hand on what is called the pit of the +stomach, turning the ends of the fingers towards the heart; your hand +will nearly cover the space usually occupied by the stomach, and you +may figure it to yourself as a rounded and elongated bag, bigger above +than below, making a very decided bend inside as it descends from the +heart downward; something like one of those long French pears, called +"Bon-chretiens," if it were bent in the middle, and the big end of it +were placed next the heart. As for the exact size of the bag, there +is no telling it, for it depends upon circumstances. It is a very +convenient bag in that respect; just such a one as you would like to +have in your frock for a pocket; only there would be a danger of your +being tempted to put too many things into it. For as you fill it, it +expands, and enlarges itself like an indian-rubber ball, which, though +only the size of an egg to begin with, becomes as big as your head if +you blow hard into it. Then, as it gets empty, it recovers itself, +diminishing gradually in size in plait-like contractions. + +When people remain too long without eating, they have, as they say, +twinges in the stomach. This is because the stomach, becoming by degrees +quite empty, and contracting more and more, the surrounding parts which +were sustained by it, lose their support, and strain at their ligaments, +which now have all the weight to bear. Careless people, who do not +think of such things, are reminded by the twinging pains that it is +time to eat, just as a careless servant is called to order by the bell +of which his master has pulled the string. + +In your case, my dear child, such warnings are soon attended to, and +you have not always even to wait till they come. But there are hundreds +of miserable beings who are warned to no purpose, who cannot obey the +master when he calls for his rations, because they have nothing to +give him; and when this forced disobedience lasts too long, they end +by dying of it. In cases like these, when human beings thus cruelly +perish, the stomach is found to be contracted till it is scarcely +bigger than one's finger. + +On the other hand, a man once died suffocated from excess of food, +after one of those great public dinners, which last four, six, or more +hours--one can scarcely say correctly how long--and the doctors who +examined him found his stomach so prodigiously enlarged that it alone +occupied more than one-half of his inside. As you perceive, therefore, +the stomach has, properly speaking, no fixed size. Its size depends +upon what there is in it. It is like those men whose manners go up and +down with their fortunes; who seem very grand people when their pockets +are well filled, but become very small ones when their purses are +empty. There is, nevertheless, this difference between them, that such +men are fools, because they are men, and not _bags_; whereas the +stomach is a sensible bag, fulfilling with intelligence the duties of +its character as a bag. It is very fortunate for us that it is ready +to change its size, according to the caprices of our appetite; and +dressmakers would do well if they could get a hint from it how to +improve their style of pockets, which certainly cannot have cost their +inventors any very great effort of imagination! + +The way in which this extraordinary pocket empties itself is not less +curious than the rest. As long as digestion is going on, the stomach +is firmly closed at each end; at the upper one by the last ring of the +_aesophagus_, and at the lower by another ring of the same kind, +only stronger; the watchful guardian of the passage which leads to the +intestines. This ring is called the _pylorus_. + +For once, here is a name which agrees with our method of describing +the human machine, and I have much pleasure in translating it to you, +although it is a Greek word. _Pylorus_ is the Greek for a porter; +and our ring is indeed a porter like the one of which we have already +said so much, and which I called last time the _porter up above_, +in anticipation of his colleague below. + +The porter up above presides at the entrance; the one below at the +exit, and both for the same purpose, namely, to _taste._ [Footnote: +It would be absurd to say so in the common acceptation of the term; +but according to No. 1 of Mr. Mayo's "Classification of the impressions +produced by substances taken into the fauces," viz., _"Where +sensations of_ touch _alone are produced, as by rock-crystal, +sapphire, or ice,"_ the word taste may be applied to the +discriminating faculty of the _Pylorus_.--TR.] + +It may well astonish you, that you should have in your inside a taster +who is not accountable to you; who experiences sensations of which you +know nothing, and cannot even form an idea. Yet thus it is. The +_pylorus_ actually tastes the paste which is in the stomach, and +if it is not to his taste, that is to say, if the work of digestion +has not sufficiently transformed it for use, he keeps the door +relentlessly closed. + +The porter up above has a thousand different tastes. He makes his bow +to meringues, and admits wings of chickens. Fries, roasts, stews, +things tender or crisp, sweet and salt, oily, greasy, or sour; amongall +kinds he has friends whom he welcomes in succession; and it is +well for us that he does so, for we share in all his pleasures. + +The porter below, who works for himself alone, obscure and unknown +down in his black hole, the porter below, I say, has but one taste, +knows but one friend--a gray-looking paste, semi-liquid, with a very +peculiar unsavoury smell, disagreeable enough to any one but himself, +which is called the _chyme_, I scarcely know why, but it is what +everything one eats turns into, without exception, be it delicate or +coarse by nature. The great lord's truffle-stuffed pullet makes, as +nearly as possible, the same _chyme_ as the charcoal-burner's black +bread; and though the palate of the former may be better treated +than that of the latter, the _pylori_ can enjoy but one and the +selfsame sauce. Equality is soon restored in this case, therefore, as +you see. + +To be free to pass through then, the contents of the stomach must be +reduced to the condition of _chyme,_ the only substance which finds +favor with the _pylorus:_ and as, in the endless varieties of food which +go to form our nutriment, some sorts turn into _chyme_ much more quickly +than others, it follows, that by the aid of its discriminating tact +(which is not easy to elude) the _pylorus_ allows some to pass, while it +turns back others, until all in succession are converted into chyme. For +example, in the case of a mouthful of bread and meat swallowed at once, +the bread passes away on its travels long before the meat has done +dancing attendance in the stomach, awaiting that transformation without +which the _pylorus_ will never allow it to slip through. + +This ought to make you seriously reflect on the danger of carelessly +swallowing things, which, by their nature, are not susceptible of being +converted into _chyme,_ particularly if they are too large to +hide in the general paste, as a cherry-stone will sometimes do, so +mixed up with other food as to pass unperceived by the _pylorus,_ +over whose decisions we have no control, remember. It bangs the door +to, be assured, in the very face of anything obnoxious without +hesitation, and the poor stomach would find itself condemned to retain +them for an indefinite period, unless by dint of prayers and +supplications they should contrive to soften the stern guardian, who +may at last get accustomed to their approach, and, perhaps, in a weak +moment, allow them to pass as contraband goods; like a custom-house +officer on a foreign frontier who will occasionally shut his eyes to +a country friend's packet of tobacco. But the poor stomach has had to +suffer a martyrdom meantime, while the dispute was pending, and before +the intruder has been winked at by the porter. + +I shall remember all my life the history of a peach-stone, which was +related to me in 1831. I was at the time a youngster at the Stanislaus +College, and (aided perhaps by the Revolution of July, which had +recently occurred), it was just then discovered to be a proper thing +to set about teaching the laws of nature to children. Consequently, +for the first time in the history of schools, a professor of natural +history was added to the instructors of Latin and Greek. I leave you +to judge how we opened our ears to his lessons. When we arrived in the +course of our new studies at the _pylorus,_ of which we had none +of us ever heard before, our professor, in warning us, as I have done +you, of the dangers of imprudent gluttony, related, as an instance, +the case of a lady who had inadvertently swallowed a peach-stone. For +two years she suffered agonies in her stomach without any cessation +or relief. The luckless peach-stone, repelled by the walls of the +stomach, which its very touch irritated, was incessantly thrown against +the entrance of the _pylorus,_ but in vain. As to turning itself +into _chyme,_ such a thing was not to be thought of, it was far +too hard a substance for that. Round and round it went, causing in its +relentless course such renewed suffering to the poor patient, that she +was visibly sinking from day to day. + +The doctors, finding all their treatment of no avail, began to despair +of her life, when one fine day she was suddenly, and as if by +enchantment, relieved of her tormentor. The peach-stone had bribed the +porter, with whom, in the course of the two years, it had scraped up +a sort of friendship. It had cleared the terrible barrier, had been +allowed to slip out, and the lady was saved; but it was only just in +time. + +I do not know, my dear, that this story, which is certainly well +calculated to cure you of any fancy for swallowing peach-stones, +willmake as much impression on you as it did on me five-and-twenty years +ago. The idea of telling it to you occurred to me quite by chance. It +has carried me back to the time when, as is now the case with you, the +mysteries which lie hidden in our internal organization were beginning +to be revealed to my mind; and you will one day know with what delight +one recalls the remembrance of these first dawnings of the intellectual +life--that delightful infancy of the growing mind--more rich in +recollections, and more interesting a thousand fold than the infancy +of the body. I have allowed myself the little treat of this episode, +and if I have had the good fortune to amuse you at all during our +progress, you must not cavil at this piece of self-indulgence. +And now we have done just what the peach-stone did; we, too, have +passed the barrier, and are out of the stomach, but still we have not +yet come to the end of our tale. + + + +LETTER X. + +THE INTESTINAL CANAL. + +I venture to hope, my dear child, that more and more light is dawning +upon your mind, as we gradually proceed on our little journey. You +must by this time have some idea how the food, which has been masticated +and softened in the mouth, cooked, kneaded, and decomposed in the +stomach, and transformed into a soft, semi-transparent kind of paste, +will soon be ready to mix with the blood, in order to repair the waste +that the life-stream is continually undergoing in its ceaseless course +through all parts of the body. + +You have perhaps thought it a sad degradation for a truffle-stuffed +fowl to turn to _chyme._ But when you consider that by this means +it becomes part and parcel of a human body, the change is not to be +despised. It was necessary, to begin with, that materials destined to +the honor of being incorporated into our frame, should break the links +which bound them to the condition of fowl and vegetable, and thus be +free to engage in new relations; just as a man who wishes to be +naturalized in a new country must first break the ties which hold him +to the old one. Those articles of food we were speaking of lately, +which are so stiff and ceremonious, and want so much coaxing before +they change into _chyme,_ which, moreover, we call _indigestible_ +because they tire the stomach so much more than the rest, are merely +those whose component parts being held together by more solid ties than +usual, continue obstinately in the same state as at first, and will not +consent to that dissolution which is the first condition of their +glorious transformation. + +Moreover, the transformation which has been described to you now, you +will henceforth meet with everywhere; wherever, that is to say, and +as far as, you choose to pursue the study of nature. God works by one +grand and simple rule so far as we can discover. He destroys to +reconstruct, builds up what is to be, out of the ruins of what has +been, creates life by death, if I may so express myself, and thus, +what takes place in our stomachs on a small scale goes on on a large +one in the universe. + +Social communities, like everything else, are subject to this universal +law, and it is not always an advantage to them when they refuse to be +digested in the great stomach of the age! + +While we are on this subject, and to show you how wonderfully this +little history of eating, told in this familiar style, applies right +and left, let us reflect on the causes which have produced a great and +mighty nation in one country (as in France), while in another (as in. +Germany), a far more numerous and even more intellectual population +has failed to rise to anything like the same distinction. The +explanation is not difficult. In the one case, the petty tribes among +which the land was originally divided consented to mix, and dissolve, +and be digested as it were together, in order to revive again for a +more glorious career; while in the other, the aboriginal societies +have adhered stiffly to their distinctive characters, and failing to +submit to the regenerating process, cling together in indigested +portions, rather than assimilate into one great whole. + +However, we must return to the _pylorus_ or we shall be getting +into a difficulty! What I am now going to offer you though, is rather +hard of digestion, but it will not do to provide sweet pastry only for +your brain; it will be more wholesome for it to have something a little +more solid to bite at from time to time. + +The _pylorus_, then, as has been shown, makes way for all sorts +of aliments when they have been converted into _chyme; i.e._, +when they have lost their original form and individuality. They are +dead to their first life, therefore; now the question is, how are they +to be revived into the new one? + +Behind the _pylorus_ extends a long conduit or tube--so long as to be +sometimes seven times the length of the whole body, but doubled up +backwards and forwards a number of times, so as to form a large bundle, +which fills the whole cavity of the belly--or as we also call it, the +_abdomen_. This bundle or packet is known to everybody as _the +intestines_, and it is divided into two portions: the _small +intestine_--that is, the slenderer, finer portion which begins at the +_pylorus_, and forms all the doublings of the packet, and the _large +intestine_, which is shorter and thicker also, as its name implies, and +keeps to some extent separate, though it is in reality only a +continuation of the other. This starts at the base of the _abdomen_, +near the right side, goes up in a straight line to the height of the +stomach, below which it passes, making a large bend in front of the +small intestine; after which it descends on the left side to the lower +part of the trunk, where it terminates. + +You will perhaps inquire how the _chyme_ continues to make its way +through all these manifold twists of the intestines; but do not trouble +yourself; it has only to let itself go. That _vermicular movement_ which +we noticed in the _oesophagus_ and in the _stomach_ is found here also. +It reigns, so to speak, from one end of our internal eating-machine to +the other; which eating-machine, by the way, we will now call by its +proper scientific name--_the intestinal canal_; and it is by that +movement the food is carried forward from the first moment it leaves the +mouth, and helped through all its journeyings, till it reaches the +termination of the large intestine. + +If your body were made of glass, so that you could look through it to +watch the intestine at work, it would appear to you like an enormous +worm coiled up into a bundle, heaving and moving with all its rings +at once. You never suspected there was such a movement within you; yet +it has been going on there continually ever since you were born, and +will not cease till you die. Your internal machinery never goes to +sleep, not even when you are sleeping yourself. It is a workshop in +constant operation, providing night and day for your necessities; and +in this respect the inner man sets a first-rate example to the outer +one! You will recollect what I said to you the other day about the +internal republic, and the provinces which are under your sole +government. It would be very disgraceful for the kingdom to be doing +nothing while the republic is working so hard; and a queen who +understands her office will make it a point of honor to banish idleness +from her household; in the houses of her neighbors this word is unknown. + +The _chyme_ once launched into this moving tube, is in no danger +of remaining stationary there; the fear is, of its passing on too +quickly, as you will soon see. But this danger has been provided +against. Along the whole course of its journey, though chiefly at the +commencement, it encounters at intervals certain elastic fleshy valves +which interrupt its progress, and do not allow it to pass till it has +accumulated in sufficient force to push them before it, and so escape. +In consequence of which it is always being checked in its advance; and +during these stoppages a most important work goes on upon it at leisure. + +You must understand first, that the substances of which our food is +composed, and which are afterwards decomposed in the stomach, are not +all invited to enter the blood. Our aliments are something like the +stones which the gold-seekers of California reduce to powder in order +to extract therefrom the hidden particles of gold they contain. The +gold of our food is that portion of it which the blood is able to +appropriate to his own advantage; the rest he rejects as refuse. And +this explains why a small slice of meat nourishes you more than a whole +plateful of salad. Meat is a stone absolutely full of gold, while the +salad has only a few veins of it here and there, and by far the greater +part of the material it sends to the intestines, has, in consequence, +to be thrown away. + +Now it is in the first portion of the small intestine, the part known +by the Latin name _duodenum,_ which signifies twelve (because it +is about the length of twelve finger-breadths), that the division takes +place between the parts which go to nourish the blood, and those which +are useless refuse. It is an important operation as you may suppose, +and were the _chyme_ to pass rapidly through the small intestine +the gold would run the risk of being carried off with the refuse. + +After the delay in the stomach, the food-substances make another halt +in the _duodenum,_ which, being very thin and slender, would have +great difficulty in containing them at the time of their grand entry, +an hour or two after a meal, were it not that it possesses the property +of expanding itself to such an extent, that it swells out on grand +occasions to the usual size of the stomach itself, so that it has +sometimes been considered as a second stomach. And no doubt the +operation which takes place in it gives it a claim to the appellation, +for thereby the finishing stroke is put to the work previously begun +in the stomach, and one may fairly say that, but for this last touch, +very little would be accomplished at all. + +Above the _duodenum_, and hid behind the stomach, is a kind of sponge, +similar in nature to those we have already observed in the mouth. To +this has been given the somewhat ridiculous name of _pancreas_; I call +it ridiculous because it is derived from two Greek words which signify +_all flesh_; whereas the _pancreas_, which is a sponge of the same +description as the salivary glands, presents the appearance of a grayish +granulous mass which is not fleshy at all. Whatever be its name, +however, our sponge communicates with the _duodenum_ through a small +tube, by means of which it pours into the _chyme_, as it accumulates, a +copious supply of a fluid exactly like the _saliva_ of the mouth. + +Just by the place where the tube from the _pancreas_ empties itself into +the _duodenum_, another tube arrives bringing also a fluid, but of a +different sort. This last comes from the liver, where there is a +manufactory of _bile_--an unpleasant yellowish-green liquid, the name of +which you have no doubt heard before, and which plays a very important +part in the transformation of the aliments. + +These new agents, the bile and the liver, are far too important to be +passed over in a few words; I reserve them, therefore, for my next +letter. Meantime, not to leave you longer in suspense, I may say that +the separation between the gold and the refuse in the _chyme_ takes +place as soon as the latter has received the two liquids furnished +by the liver and the _pancreas_. If you ask in what manner the +division is accomplished, I confess, to my shame, that I am not able +to explain it! What takes place there is a chemical process, and +hereafter I shall have occasion to explain the meaning of that phrase. +But the Great Chemist has not in this instance seen fit to divulge to +man the secret of the work. + +Indeed, you must prepare yourself beforehand, my dear child, to meet +with many other mysteries besides this, if we pursue to the end our +study of this flesh and bone which constitute the body of man. And +here I recall what Camille Desmoulins is reported to have said about +St. Just, viz., that he carried his head as high as if it were a +consecrated Host. + +[Footnote: The young Protestant reader who has never lived +in a Catholic country, will perhaps need to be told, that what +is here called Consecrated Host, is the sacramental wafer, or communion +bread of the church. In French called _hostie_, in Italian, _ostia_. + +In all their religious processions, which are very frequent, the host +is carried by the priest highest in authority, in a glass box placed +on a staff about four feet long, which he holds before him and so far +elevated that he has to look up to it. Over his head a richly +embroidered canopy of satin is always carried by several men; and while +these are passing, all good Catholics uncover the head and bend the +knee, wherever they may be. + +It is the custom also for the priest to be called to administer the +sacrament to any one about to die, on which occasion he always walks +under this canopy, dressed in his priestly robes, carrying the host +and preceded by some boys, ringing a bell, when the same ceremony is +observed. In passing a regiment or company of soldiers, the column is +halted, wheeled into line, and with arms presented, the whole line, +officers and men, kneel before it, and the priest usually turns and +offers a benediction. When he goes in the evening to the house of the +dying, it is customary for the people to go out upon the balconies +with lighted lamps and kneel while the host is being carried by.] + +You will read about these two men by-and-by in history. Meantime I +will not bid you do exactly the same as St. Just, because you would be +laughed at; but in one point of view he was not altogether wrong. The +human body is, in very truth, a temple in which the Deity maybe said +to reside, not inactively, not veiling his presence, but living and +moving unceasingly, watching on our behalf over the mysterious +accomplishment of the everlasting laws which equally guide the +_chyme_ in its workings through our frames, and direct the sun +in its course through the heavens. We mortals eat, but it is God who +brings nourishment out of our food. + + + +LETTER XI. + +THE LIVER. + +I fear you will be getting a little weary, my dear, of dwelling so long +on this intestinal tube, where things which looked so well on one's +plate become so transformed that they cannot be recognized, and where +there is nothing to talk about but _chyme_, and _bile_, and the +_pancreas,_ and all sorts of things neither pleasant to the eye nor +agreeable to the ear. + +But what is to be done? It is always the same story with useful things. +The people by whose labor you live in this world, are by no means the +handsomest to look at, and so it is in the little world we carry about +in our bodies. + +Never mind! Keep up your heart. We are getting to the end. We shall +very soon be following the nourishing portion of our food, on its +journey to the blood, and you will find yourself in new scenes. + +First, though, let us say a few words about the liver--the +bile-manufacturer; and to begin with, I will describe the place he +occupies in our interior. + +The interior of the human body is divided into two large compartments, +placed one above the other; the _chest_ and the _abdomen_. These are two +distinct apartments, each containing its own particular class of +tenants: the upper one being occupied by the heart and the lungs (the +respective offices of which I will presently explain to you); while in +the lower are the stomach, the intestines, and all the other machinery +which assists in the process of digestion. These two stories of +apartments are separated as those of our houses are, by a floor placed +just above the pit of the stomach. This floor is a large thin, flat +muscle, stretched like canvas, right across the body; and it is called +the _diaphragm_--another hard word! Never mind; but do your best to +recollect it, for we shall have great need of it when we come to the +lungs. If you had been born in Greece, you would have no difficulty with +the word, for it is Greek for _separation_. It means, in fact, a +_separating partition_, or, as I called it just now, _a floor._ All this +is preparatory to telling you that the liver is hooked to the diaphragm +in the abdomen. It is a very large mass and fills up, by itself alone, +all the right side of the lower compartment, from the top downwards, to +where the bones end which protect the abdomen on each side, and which +are called _the short ribs._ Place your hand there, and you will find +them without difficulty. + +Large as the liver is, it hangs suspended to a mere point of the +diaphragm, and shakes about with even the slightest movement of the +body. It is partly on this account that many people do not like to +sleep lying on the left side, especially after a good dinner, because +in this position the liver weighs upon and oppresses the stomach, like +a stout gentleman asleep in a coach who falls upon and crushes his +companion at every jolt of the vehicle. The liver within you produces, +then, the same effect that a cat, lying on the pit of your stomach +would do, and the result is that you have the nightmare. + +The liver is of a deep-red color. It is an accumulation of excessively +minute atoms, which, when united, form a somewhat compact mass, and +within each of which there is a little cell, invisible to the naked +eye, where an operation of the highest importance to our existence is +mysteriously carried on. It appears a very simple one, it is true, yet +hitherto it has baffled all attempts at explanation. Listen, however; +the subject is well worthy your careful attention, whether it can be +explained or not, and we must look back to take it up from thebeginning. + +I told you about the thousand workmen constantly busied in every part +of our bodies, who call on the blood without ceasing for "more, more." +You will remember further that it is to enable the blood to supply +these constant demands, that we require food. + +This being understood, it is not difficult to see why we grow; the +difficulty is, rather, to explain why we do not continue to grow. + +Consider, for instance, the quantity of food you have eaten during the +last year. Picture to yourself all the bread, meat, vegetables, fruits, +cakes, &c., piled upon a table. Put a whole year's milk into a large +earthenware pan, all the sweetmeats into a large jar, all the soup +into a great tureen, and see what a huge heap you will have collected +together. Then try to recollect how much you have increased in size +with all this nourishment, which has entered your body. But reckoning +in this way--even supposing the little workmen had used only a half +or even a third of the materials in question, and rejected the rest +as refuse--you would have to stoop in order to get in at the door; and +as for your papa, whose heap must have been bigger than yours, his +case would be desperate indeed; and yet he has not grown at all! + +This is very curious, and I dare say you have never thought about it +before. + +Do you know the story of a certain lady called Penelope, who was the +wife of Ulysses, a very celebrated king of whom the world has talked +for the last 3000 years--thanks to a poet called Homer, who did him +the honor of making him his hero! The husband of Penelope had left her +for a long time to go to the wars, and as he did not return, people +tried to persuade her to marry again. For peace and quiet's sake, she +promised to do so when she should have finished a piece of cloth she +was weaving, at which she worked all day long. They thought to get +hold of her very soon, but her importunate lovers were disappointed; +for the faithful wife, determined to await the return of her husband, +unwove every night the portion she had woven during the day; and I +leave you to judge what progress the web made in the course of a year! + +Now, every part of our bodies is a kind of Penelope's web, with this +difference--that here the web unravels at one end as fast as the work +progresses at the other. As the little masons put new bricks to the +house on one side, the old ones crumble away on another--in this manner +the work might go on forever without the house becoming bigger; while, +on the other hand, the house is always being rebuilt. People who are +fond of building, as some are, would quite enjoy having such a mansion +as this on hand! + +At your early age, my love, fewer bricks drop out than are added, and +this is why you grow from year to year. At your papa's age, just the +same number perish and are replaced; and therefore he continues the +same size, although in the course of the year he swallows three times +his own weight of food. But when I say this, do not suppose it is an +offensive remark, or that I think him either too little a man, or too +great an eater; seeing that there are 365 days in the year, and that +a quart of water weighs two pounds: I need not say more! + +But the next question is, what becomes of all the refuse which this +perpetual destruction produces? + +What becomes of it? Have you forgotten our steward who looks after +everything? He is a more active fellow than I have represented him! +To the office of purveyor-general he adds that of universal scavenger. +But in the latter department he obtains help. Wherever he passes along, +troops of little scavengers press forward, like himself always busy; +and while he holds out a new brick to the mason as he hurries by, the +little scavenger slips out the old one and conveys it away. The history +of these scavengers is a very curious one, and we shall have to speak +about it a little further on. They are minute pipes, _i.e. ducts_, +spread all over the body, which they envelope as if with fine net work. +They all communicate together, and end by emptying the whole of their +contents into one large canal, which, in its turn, empties itself into +the great stream of the blood. Imagine all the drains of a great town +flowing into one large one, which should empty itself into the river +on which the town was built, and you will have a fair idea of the whole +transaction. What the river would in such a case be to the town, the +blood is to the body--the universal scavenger, as I said before. But +you will ask further, What does the blood do with all this?--a question +which brings us back once more to the liver. + +You must have seen, just now, that the pockets of our dear steward +would be rapidly overloaded, were he to keep constantly filling them +with the old worn-out materials which the builders rejected, unless +he had some means of emptying them as he went along. Accordingly, a +wise Providence has furnished the body, on all sides, with clusters +of small chambers or cells, in which the blood deposits, as he goes +by, all the refuse he has picked up, and which makes its exit from the +body sometimes in one way, sometimes in another. Now, the cells of the +liver are among these refuse-chambers. One may even consider them as +some of the most important ones. When the blood has run its course +through the lower compartment, I mean the _abdomen_, it collects +from all directions and rushes into a large canal called the _portal +vein_, which conveys it to the liver. As soon as this canal has +entered the liver, it divides and subdivides itself in every direction, +like the limbs and branches of a tree diverging from the trunk; and +very soon the blood finds itself disseminating through an infinity of +small canals or pipes, whose ultimate extremities, a thousand times +finer than the finest hairs of your head, communicate with the tiny +cells of the liver. There, each of the imperceptible little drops, +thus carried into these imperceptibly minute cell-chambers, rids +itself--but no one knows how--of a part of the sweepings it has carried +along with it. Which done, the little drops thread their way back +through other canals as fine as the first, and which go on uniting +more and more to each other, like the branches of a tree on their way +to the trunk--forming at last one large canal, through which the blood +escapes from the liver, once more relieved from its weight of rubbish, +and ready to recommence its work. + +You are going to ask me, "What is all this to me--this history of the +blood and its sweepings? It was the bile you undertook to tell me +about, that liquid you spoke of as so necessary for the transformation +of the food: we were to get out of the intestinal tubes by the help +of the bile, you promised me." + +Well, my little impatient minx, it is the history of the bile that I +have been relating to you, and what is most remarkable about it is +this. You have perhaps heard of those wholesale ragpickers, who +makelarge fortunes by collecting out of the mud and dirt of the streets, +the many valuable things which have been dropped there? Well, the liver +is the master-ragpicker of the body. He fabricates, out of the refuse +of the blood, that bile which is so valuable in the economy of the +human frame. This bile is neither more nor less than the deposit left +by the little drops of blood in the innumerable minute liver-cells. +See what an ingenious arrangement, and in what a simple way two objects +are effected by one operation! + +Now you have learnt the genealogy of the bile, and the double office +of the liver, which benefits the blood by what it takes from it, +benefits the _chyme_ by what it gives it, and is an economist at +the same time--since it only gives back what it has received. This was +what I particularly wished to explain to you: the rest you will easily +learn. + +The bile does not make a long stay in the little cells, it also escapes, +by canals similar to those which carry off the blood, after +itspurification; and which in a similar way unite by degrees together, +until at length they terminate in a single canal, communicating with +a little bag placed close against the liver, where the bile accumulates +between the periods of digestion--so forming a stock on hand, ready +to pour at once into the _duodenum_ when the latter calls for its +assistance. The next time the cook cleans out a fowl, ask her to show +you the little greenish bladder which she calls the gall and which she +takes such care not to burst, because it contains a bitter liquid +which, if spilt upon it, would quite ruin the flavor of the fowl. Such, +precisely, is the bag which holds the bile. Moreover, it is close by +the liver of the fowl that you will find it placed: and you can convince +yourself in a moment by it, that the little provision I tell you of +is always stored away therein. + +We have also within us a multitude of minute electric telegraphs, which +transmit intelligence of all that occurs from one part of the body to +another, in a more wonderful manner even than the telegraphs of man's +making; later we shall see how they work. By their means the little +bag by the liver is made aware in the twinkling of an eye of the +entrance of the _chyme_ into the _duodenum,_ and forthwith the bile +returns for some distance by the canal which brought it, and then +branches off into a larger one which opens into the _duodenum._ + +The liver, on getting this intelligence, sets to work more diligently +than ever, and the bile flows in streams into the _duodenum,_ where it +mixes as it arrives with the current which comes from the _pancreas._ +Thus combined, the two liquids flow over the _chyme,_ which they +saturate on all sides; and here, as I have said, the work of the +intestinal canal ends. What is serviceable for the blood is separated +from the useless refuse, and nothing remains but to get it out of the +intestines. It is true that in their character of tubes these are closed +on all sides. But do not trouble yourself: a means of escape is +prepared. + +Before we part, however, I must apologize for something. I have not +described to you what the bile consists of, or what kind of refuse the +blood leaves in the liver; nevertheless, as you take an interest in +this much-neglected book of nature, you ought to know these things. + +It is, however, very difficult to lead you by the hand through so many +wonder*, where the secrets of nature are all in operation at once, and +to explain each as soon as we meet with it. They combine, and progress +together like the waves of the sea, where one breath suffices to agitate +the whole mass. + +When we have talked about the lungs, we will have another word to say +about the liver. + + + +LETTER XII. THE CHYLE. + +To-day we have to begin by making acquaintance with a new term. I would +willingly have spared you this, if I could, for the word is neither +a pretty, nor a well-chosen one, but we cannot get on without it. + +You are aware now that the learned, unknown sponsors, who gave names +to the different parts of the body, bestowed the odd-enough one of +_chyme_ on that pasty substance which passes out of the stomach when the +cooking is over. We have said quite enough about it, and you know enough +of it I am sure. Well! the people seem to have had quite a fancy for the +word _chyme_, for they adopted it again, with only a very slight +alteration, when they wanted to specify separately the quintessence of +the _chyme_ (the useful part that is), which has to unite with the +blood, and which we have been speaking of as the _gold_ of the aliments +--this then they called _chyle_. I give you the name as I received it, +but have no responsibility in the matter. + +In concluding the last chapter I said we were sure to find there was +a plan for extracting the best part of the _chyme_, viz. the _chyle_, +from the intestinal canal; and a very simple one it is. A complete +regiment of those little scavengers lately described, are drawn up in +battle-array along the whole length of the small intestine, but +especially round about the _duodenum._ There, a thousand minute pipes +pierce in all directions through the coat of the intestine, and suck, +like so many constantly open mouths, the drops of _chyle_ as fast as +they are formed. They are called _chyliferous vessels_ or chyle-bearers, +just as we might call hot-air stoves _caloriferous_ or heat-bearers-- +from the Latin word _fero,_ which means to carry or bear. I mentioned +before that there were, within the intestine, certain elastic valves +which obstruct the progress of the _chyme,_ and oblige it to be +constantly stopping. There are in fact so many of these, and the skin +which lines the intestinal canal is so folded and plaited, that if it +were stretched out at full length on a big table, it would cover at +least as large a surface as that other skin, with which you are so well +acquainted, which entirely clothes the body outside. + +Now, the _chyliferous vessels_ we have been speaking of insinuate +themselves into all the plaits and folds alluded to, and thus they +reach at last the very centre of the _chymous_ paste, and not a single +drop of _chyle_ can escape them. They do their work so well, that the +separation is effected long before the paste reaches the large +intestine; and when that has forced its way through the door which +guards the entrance, and which prevents its ever returning again, the +_chyle_ is already far off on its mission. It has threaded its way along +the little pipes, and, always creeping nearer and nearer, is on the +high-road to the heart, where it is anxiously expected. + +And what becomes of the rest? There is nothing further to be said about +it, but that it shares the fate of everything else which, having +answered its purpose in its place, is no longer wanted and must be got +rid of. Thus in works where iron-stone smelting is carried on, the +refuse that remains after the ore is extracted, though available for +road-making or other purposes, is thrown out of the manufactory as a +useless incumbrance there. + +Our history requires us to follow the fate of that golden aliment the +_chyle,_ which is now in a condition to support the life of the body, +and every drop of which will turn into blood--the blood which beats at +our hearts, nourishes our limbs, and sets at work the fibres of our +brain. + +I ought to tell you first that the _chyle,_ when it leaves the +intestine, is very like milk. It is a white, rather fatty juice, having +the appearance, when you look closely at it, of a kind of _whey,_ +in which a crowd of globules, or little balls if you prefer it, +infinitesimally small, are swimming about. Some people, whose curiosity +nothing can check, have put the tips of their tongue to it; so I am +able to tell you, if you care for the information, that it has rather +a saltish taste. + +At this point it is what may be called new-born blood, and to carry +on the metaphor, blood whose education has yet to be completed. All +the elements of blood are there already, but in confusion and +intermingled, so that they cannot yet be recognised. A wonderful fact, +and one of which I have no explanation to offer you, because among the +many mysteries which are silently going on within us is this, that the +education of the new-born blood begins entirely of itself in the vessels +which are carrying it along. During their very journey, the confused +elements are setting themselves in order and forming into groups. In +short the _chyle,_ when it comes out of the chyliferous vessels, +is already much more like blood than when it entered them, and yet one +cannot account for the change. It is changed, however; its whiteness +has already assumed a rosy tinge, and if it is exposed to the air it +may be seen turning slightly red, as if to give notice to the observer +of what it is about to become. + +You know that all our scavengers uniting together deposit their +sweepings in one large canal, which is called the _thoracic duct._ +The _chyle_ scavengers arrive there just like the rest, and there +our poor friend finds himself confounded for a moment with all the +dross of the body, as sometimes happens to men who devote themselves +to the public good. But the crisis passes in an instant. A little +further off, the _thoracic duct_ pours its whole contents together +into a large vein situated close to the heart, and the blood has no +difficulty in recognising and appropriating what belongs to him. + +Here, my dear little scholar, we conclude the first part of our story. +To eat is to nourish oneself; that is, to furnish all parts of the +body with the substances necessary to them for the proper performance +of their functions. The mouth receives these substances in their crude +condition, the intestinal canal prepares them for use, and the blood +distributes them. + +After the history of the _preparation,_ comes naturally that of the +_distribution._ + +The first is called the DIGESTION. It is the history of the _chyle,_ +which begins between the thumb and forefinger while as yet invisible, +hid in the thousand prisons of our different sorts of food, and ends in +the _thoracic duct, when, disengaged from all previous bonds, purified +and refined by the ordeals of its intestinal life, it leaps into the +blood, carrying with it a renewal of life and power. + +The second history is that of the CIRCULATION. It is the history of +the _Blood,_ that indefatigable traveler, who is constantly +_circulating_ or describing a circle (the Latins called it _circulus_) +through the body; by which I mean that it is continually retracing its +steps, coming out of the heart to return to it, re-entering it only to +leave it again, and so on without intermission, until the hour of death. + +The history of the _Digestion_, which we have just gone through, +goes on quietly from one end to the other without any complication. + +That of the _Circulation_, which we are about to begin, is mixed +up with another history, from which it cannot be kept separate while +the description is going on, although the two histories are in reality +quite distinct from each other. The blood describes two circles, to +speak correctly: 1st. A wide one, which extends from the extremities +of the body to the heart, and back again from the heart to the +extremities. 2d. A more contracted one, which goes from the heart to +the lungs, and back from the lungs to the heart. Whilst circulating +in the lungs, it encounters the air we breathe; and here takes place, +between it and the air, one of the most curious transactions imaginable, +without which the blood would not be able to nourish the body even for +five minutes. This is called RESPIRATION, or the act of breathing. + +Digestion, circulation, respiration, the three histories together form +but one--that of NUTRITION, or the act of nourishing; in other words, +of supporting life. This is what I called _eating_ at first, that +I might not mystify you at the beginning with hard words. But now that +we are growing learned ourselves, we must accustom ourselves to the +terms in use among learned people, especially when they are not more +formidable than those I have just taught you. + +Our next subject for consideration, then, Will be the circulation; and +we will begin with the heart, since that is to the circulation what +the stomach is to the digestion--viz., master of the establishment. +He is a very important person, this heart, as I hardly need tell you. +Even ignorant people speak respectfully of him, and I am sure beforehand +that his history will interest you very much. + +Do you feel as I do, my dear child? I am quite happy at having brought +you thus far on our journey, and at being able to take a rest with you +at the gateway of the new country into which we are about to enter, +like travelers sitting down upon a boundary frontier. What a distance +we have come, since the day when I took you by the hand to conduct you +inside this little body, of which you were making use without knowing +anything about it! How many things we have learned already, and how +many more remain to be learned, of which you have at present no idea! +I assure you I should be almost afraid myself of what is before us +yet, if I did not rely upon my own strong desire to instruct you, and +the tender affection I bear to you. Believe me, the greatest of +constraining powers is love; and when I get bewildered in the midst +of some difficult explanation which will not come out clearly, I have +only to place before me those laughing eyes of yours, where sleeps a +soul that must soon awaken to consciousness, in order to make the +daylight come into my own! + +Must I add, too, that I am not working for you only? We are all placed +in this world to help each other, and in striving to bring down light +into your intellect, and good sentiments into your heart, I am thinking +also of those to whom you, in your turn, may render the same good +service hereafter, provided I have the happiness of succeeding now +with you. This ought to be so, ought it not? You should resolve to be +numbered one day among those who have not lived altogether for +themselves, but who have given the world something worth having as +they passed through it. To-day's labor will have been well employed +if, later on, it turns out that this history of the _chyle_ has +not been told you in vain! + + + +LETTER XIII. + +THE HEART. + +There was once upon a time a banker, a millionaire, who could reckon +his wealth not by millions only, but by hundreds of millions and more; +who was, in fact, so tremendously rich that he did not know what to +do with his money--a difficulty in which nobody had ever been before. + +This man took it into his head to build a palace infinitely superior +to anything that had hitherto been seen. Marbles, carpets, gildings, +silk hangings, pictures, and statues--in fact, the whole mass of +common-place luxuries as one sees them even in the grandest royal +abodes, fell short of his magnificent pretensions. He was an intelligent +man, and thoroughly understood the respect due to his riches; and the +common fate of kings seemed to him far too shabby for the entertainment +of his dynasty, which he looked upon as very superior to all the +families of crowned heads in the world. In consequence he sent to the +four quarters of the globe for the most illustrious professors, the +most skilful engineers, the cleverest and most ingenious workmen in +every department; and giving them unlimited permission as to +expenditure? ordered them to adorn his palace with all the wonders of +science and human industry. + +Science, and human industry, and unlimited means--what will they not +accomplish? No wonder that nothing was talked of for a hundred miles +around but the magic building--of which, by the way, I do not venture +to give you a description, because it would carry me too far away. Let +it suffice to say, that never Emperor of China, Caliph of Bagdad, or +Great Mogul had such a habitation as our banker, and for a very good +reason--he was twenty times as rich as any such gentry as I have named +ever were in their lives. + +When all was finished one trifling flaw was discovered: the place was +not supplied with water. A spring-seeker, who was summoned to the +premises, could only discover a small subterranean watercourse, a sort +of zigzag pipe, formed by nature, between two beds of clay, in which +the rain of the neighborhood collected as in a sort of reservoir. The +water was neither very clear nor very plentiful, as you may imagine; +and the professor appointed to examine it, having begun by tasting it, +made a horrible face, and declared there was no use in proceeding any +further; for it had a stagnant flavor which would not be agreeable to +my lord. + +To the amazement of every body, my lord jumped for joy when he heard +this unpleasant news. It was proposed to him to fetch water from a +river which flowed a few miles' distance off; but he would hear of +nothing of the sort. What he wanted was something new, unexpected, +impossible--that was his object throughout. He took a pen and drew up +at a sitting the following programme, which caused our poor professors +to open their eyes in dismay:-- + +1st. We will use the water on the premises. + +2ndly. It shall flow night day and in all parts of the palace at once. + +3rdly. There shall be plenty of it, and it shall be good. + +The professors looked at each other for some time without speaking, +and the gravest of them, whose fortunes and characters had been long +ago established, suggested that they should simply give my lord and +his money the slip, and so teach him to make fools of people another +time! + +But the youngsters, less easily discouraged, cried out against this +with one accord. They declared that the honor of science was at stake, +and that they ought to return impudence for impudence, by executing +to the letter the impertinent programme! At length, after much +discussion and many propositions made against all hope, and thrown +aside one after the other as impracticable, a sudden inspiration crossed +the brain of an engineer who had not yet spoken; and the following is +what he proposed:-- + +What prevented the water from being sweet and fit to drink, was the +want of movement and air. What had to be done, therefore, was to erect +a pump, but a pump provided with numberless small pipes, extending to +the watercourse in all directions, and so arranged that by means of +them it should be able to draw up the water from all the corners and +windings where it lay stagnating, and then forcing it forward into a +pipe terminating in a rose, like that of a watering-pot, whence it +should gush out to fall down in fine rain, into a reservoir in the +open air. From thence another action of the pump was to bring it back +well aerated, to send it once more into a large pipe with numerous +lesser ramifications, which should convey it into every corner of the +palace. + +Up to this point all seemed practicable, but the hardest part had not +yet come. The great difficulty was how to supply this enormous +consumption with so slender a runnel of water as the one at their +disposal. But our engineer had provided for this by a stroke of genius. + +Under each of the taps (always kept open), which were dispersed all +over the palace, he would place a small cistern, from the bottom of +which should go a pipe communicating with the body of the force-pump +which drew up the water from the original watercourse. By which means +the water which ran from the taps would be taken up again and go back +to feed the reservoir in the open air; whence it would again return +to supply the taps; and so on and on, the same water continually keeping +the game alive, as people call it. Have you not sometimes seen at a +circus or theatre a large army represented by a hundred supernumeraries, +who file in close columns before the audience, going out at one side +of the stage and coming in at the other, following close at each other's +heels indefinitely? By a similar artifice the engineer would change +his meagre little runnel into an inexhaustible fountain. The water +drawn up from the watercourse by each stroke of the pump would fully +compensate for what was used in its passage through the palace by the +inhabitants. Lastly, as it might sometimes happen that the said +inhabitants washed their hands under the taps, the water on its return +to the cisterns, was to pass through a series of small filters, in +order to cleanse it from any impurity it might have contracted by the +way. Always flowing, always limpid, it would soon lose every trace of +its original source, and might defy comparison with the water of any +river in the world! + +A unanimous buzz of congratulations welcomed this plan, at once so +simple and so bold, and our professors thought their troubles were +over, but they were not at the end of their difficulties yet. When it +came to the actual erection of the machine, (naturally a most +complicated one, as it had to set a-going a quintuple system of +pipes--pipes from the water-course to the pump, pipes from the pump +to the reservoir, pipes from the reservoir to the pump, from the pump +to the taps, and from the taps to the pump again,)--our banker, who +had got amused and excited as they went on, conducted them to a small +dark closet, only a few square feet in size, concealed in a corner of +the large apartments, and informed them with a laugh that he had no +other place to offer them. Besides which, he made them understand that +on account of its situation, there could be no question of furnaces +or boilers being set up there (he detested equally coal-smoke, fires, +and explosions)--nor of workmen employed about the machine (it would +not be decent to have them going up and down the front staircase)-- +nor above all, of the frightful brake-wheels always screeching and +grinding, the unwieldy pistons rising and falling with a noise +sufficient to give one the headache. He himself slept near the little +dark closet, and the slightest noise was fatal to his repose. Having +explained all this, the rich man curtly made his bow and retired. + +For once our professors owned themselves beaten. They had come forward +quite proud of their invention, and now they were received, not with +ecstasies of delight, but with fresh demands, more ridiculous even +than the first. They were decidedly being mystified, and were preparing +in consequence to pack up and begone, furious, and swearing by all +their gods that they would never again expose science to see itself +disgraced by a purse-proud vulgarian's scorn; when, lo! happily, a +good fairy, the special friend of learned men, came passing by that +way. She raised her enchanted wand with the tip of her finger, and all +at once a little girl dressed in rags appeared in the midst of our +astonished professors. Without giving them time to recover themselves, +the child put her hand into the little patched waist of her dress, and +drew forth a rounded object, about the size of her closed fist from +which hung a quantity of tubes spreading in all directions. + +"See!" cried she; "here is the machine your banker demands of you." + +Picture to yourself a small closed bag, narrowing to a point at the +end, and separated within into two very distinct compartments by a +fleshy partition which went across the inside from the top to the +bottom. Such was the object held up by the little girl. Prom each of +these compartments issued a thick tube, ramifying into endless smaller +ones; and they were moreover each surmounted by a sort of pouch, into +which ran another tube, of the same description as the first. Each of +these four portions (the two compartments and their pouches) was in +constant but independent motion, distending and contracting alternately; +and by carefully examining the noiseless play of this singular machine, +(the walls of which were, by the magic power of the fairy, rendered +transparent to the bystanders,) the learned assembly were very soon +enabled to convince themselves, that it fulfilled all the +monstrousconditions exacted of them by the fantastic millionaire. + +All was in movement together, I told you; but let us begin at one end. +The right-hand compartment and its pouch represented the first pump; +the pump employed to draw, by the same stroke, the water from the +stagnant channel, and that from the taps. It was perfectly easy to +distinguish the two systems of pipes, and how they united together at +the small pouch on their arrival. When this was distended, a vacuum +was created inside, which was instantly filled by the liquid from the +tube which ran into it, (do not ask me why or how; I will explain that +presently). When it contracted again, the liquid which had just entered +was not able to get back, being prevented from so doing by a very +ingenious and simple contrivance, which requires a brief explanation. + +Take off the lock from your chamber-door, which opens inside; then, +standing outside, push against it with your shoulder, and you will get +in without any difficulty. But when you are in, try to push the door +open again with your shoulder in order to get outside into the passage, +and you will find that you will not be able to pass through, and this +simply because it does not open on that side. + +Which was exactly what happened to the liquid in the pouch! + +The door between the tube and the pouch only opened inwardly, and the +liquid finding itself pressed on all sides in proportion as the pouch +contracted more and more, and unable to return, was obliged at last +to make its way through another similar door which led to the large +compartment below. Here the same game recommenced. The compartment +which had distended itself to receive it, contracted in its turn, and +the liquid finding the road again barred behind it, had no choice but +to force its way through the tube which led to the air-reservoir. + +Here commenced the work of the second pump,--the pump of the left +compartment. The little pouch, when distended, was filled by the liquid +from the reservoir, and then forced it forward into the large +compartment below, always by means of the same process. This compartment +again drove it, by a powerful contraction, into the large conducting +tube charged with the office of its general distribution throughout +the body. At the end of all which, it returned once more into the +right-hand pump as before, to pursue the same course again, &c., &c. + +Thus, as you see, the whole mechanism turned upon two little points +of detail, of the simplest description possible; namely, first, on the +entrance-doors only opening on one side; and secondly, on the elastic +covers of the pouches and compartments distending and contracting +spontaneously. It was the prettiest thing in the world to see this +unpretending-looking little bag working thus, quite naturally, without +a suspicion that it was solving a problem which so many men, proud of +their science, had given up as hopeless. Certainly here was a machine +which made no noise! Once installed in its dark closet, it would have +been necessary to place your hand upon it to find out that it moved +at all. My lord could certainly sleep beside it without disturbance. + +"How much do you want for it?" said they to the poor little beggar +girl. "Name your price; have no fear; we will pay you anything you +wish." + +"I cannot give it to you," replied the child; "I need it too much +myself: IT IS MY HEART. Now that you have seen it, make another like +it, if you can." And she disappeared. + +It is said that the engineer, who longed to see his idea carried out, +tried hard to construct a similar machine with gutta-percha and iron +wires, and to set it in motion by electricity. But history does not +tell us that he succeeded, and we have yet to ask ourselves whether +the richest man in the world, aided by the wisest men in the world, +could ever provide himself with a miracle of wonder, such as the, +ragged child had received as a free gift from the hands of a gracious +Creator. + + + +LETTER XIV. + +THE ARTERIES. + +If you have thoroughly understood the story I last told you, my child, +it will have revealed to you the whole mystery of the _circulation +of the blood,_ and you are at the present moment wiser than all the +learned men of antiquity and the middle ages, for they had none of +them the faintest surmise of the truth. + +It may, perhaps, seem odd to you that men should have existed for +upwards of five thousand years without making inquiry into a matter +which so closely concerned them, and which was so easy to find out. +Is it not almost incredible that so many hearts should have beaten for +so long a period without any of their owners having felt a wish to +know exactly _why?_ Yet so it is. The action of the heart and the +flow of the blood have not been understood for much more than two +hundred years, and the man whose name is attached to this great +discovery richly deserves that we should say a few words about him. + +He was called Harvey. He was an Englishman; physician to King Charles +I., who was beheaded in 1648; and when he first ventured publicly to +teach that the blood was constantly circulating from one end of the +human body to the other, perpetually returning and retracing its steps, +a great scandal was created in the world. He was called a fool,--an +impertinent innovator,--a madman. His words shattered old doctrines, +and he only received for his reward all the petty annoyances which men +are apt to lavish so freely upon any one who tells them something new; +because--do you see?--it is so disagreeable to be disturbed in one's +habits and preconceived ideas. + +Harvey is not the only one in the history of mankind who has committed +the sin of being right in defiance of the opinions of his age. It is +true posterity takes account afterwards of the labors of genius, and +inscribes a fresh name upon her list. But one must pay for this glory +in one's lifetime. One cannot have everything at once. + +This is an old story, my child, but always new nevertheless; and for +my own part it is, I own, one of my pleasures to amuse myself by +reflecting how much cause for laughter three-fourths of the great men +of the present day are providing for the little girls who shall be +alive two centuries hence. Time is a great avenger, and puts many +things and men in their proper places. + +Let us pause here a moment while we are speaking of Harvey. I should +be curious to know what any one of the courtiers of Charles I., bedecked +in feathers, ribbons and laces, would have said to the valet who would +have placed the excellent Harvey, with his insane invention, above his +most gracious majesty, the lord and king of all Great Britain! And yet +what is his most gracious majesty to you to-day? What do you owe to +him? in what does he interest you? While you can never hear the name +of Harvey pronounced without remembering that you are under many +obligations to him! A thousand years hence, when society shall have +made the great progress which may reasonably be expected, the name of +Harvey will be familiar to every one who owns a heart, while that of +Charles I. will be only a vanished shadow; a souvenir lost in the maze +of history. + +Our debt of remembrance paid, let us return to the heart--the little +closed bag which labors so prettily. We must now inquire the real names +of whatever has figured in our story. + +The two great compartments are called _ventricles,_ the two small +pouches _auricles,_ and they are also distinguished as being on the +right or left side;--_right ventricle, left ventricle, right auricle, +left auricle._ + +The inner doors on which depends all the action of the machine, are +called _valvelets._ By-and-bye, when the pump and the steam-engine +are explained to you, you will meet again with these treacherous doors, +which never allow what has once entered to go back again; but then we +shall call them _valves._ + +The air-reservoir, I need scarcely tell you, is the _lung,_ to +which the blood goes to put itself in contact with the air. + +The subterranean watercourse, of which I hope we have talked long +enough, is _the small intestine,_ in which the _chyle_ collects; and +the tubes which run into it are, of course, the _chyliferous vessels,_ +the only channels by which anything reaches the heart which has not +previously gone out from it. + +The tubes of distribution, which run out from the machine in all +directions, are called with us _arteries_; the return tubes, which +bring back the water to the machine, are called _veins._ + +Finally, we have not exactly the _filters_ employed to clear the +water from the impurities contracted as it goes along, for no such +thing exists in us. There are in our case the refuse-chambers of which +I have already spoken, in connexion with the liver, where the blood +disembarrasses itself of any useless materials, and from which it comes +out with clean pockets, so to speak, reverting to the comparison of +which we have already availed ourselves. + +As you see, then, everything comes round again; and the bright idea +which our professors hit upon in order to satisfy the caprice of the +banker is exactly carried out in your own body, only a thousand times +more perfectly than could have been done by them all, even with all +their science added to all his money. + +I mentioned that the shrewdest of the party boasted about making an +artificial heart. But, let me tell you, there is one thing I would +have defied him to imitate, by any expedient he could devise, and that +is the inimitable construction of the _arteries_ and _veins,_ and the +incomprehensible delicacy of their innumerable ramifications. + +Let us talk a little about these marvellous tubes, and begin with the +arteries, which have the most important part to play. + +Did you ever see a doctor try the pulse of his patient? Take hold of +your own wrist and search a little above the thumb. You will soon find +the place and feel something beating against your finger. There is an +artery which passes there, and the little beating you feel is the +rebound of the pulsations, of your heart. Every time that the left +_ventricle,_ by contracting itself, chases the blood into the arteries, +these, of which the tissue is very elastic, become distended all at +once, and then contract again, repeating the process whenever a fresh +gush of blood arrives, so that their movement is exactly regulated by +the movement of the heart. It is true the two movements are in a +contrary direction; that is to say, the artery becomes distended, while +the heart contracts, and contracts when the heart enlarges itself; but +that makes no difference to the doctor. What he wants to know is, with +what force and rapidity the heart of the patient beats, and I will +explain why. It is an interesting point in the history of circulation. + +When you were very little--very little indeed, my dear child--your +heart beat from 130 to 140 times in a minute. Afterwards the beats +sank to 100 per minute; then to fewer still. At present I cannot tell +you the precise number: perhaps, about ninety. When you are a grown-up +young lady, it will beat about eighty times in the minute; when you +are a mother, about seventy-three times; when a grandmother (if such +a blessing be granted you), only from fifty to sixty times, perhaps +even fewer. People tell of an old man of eighty-four whose heart beat +only twenty-nine times in the sixty seconds. + +Observe that in all my calculations I have taken special care to prefix +the word _about_ to the numbers mentioned. And this because, in +point of fact, the heart is a capricious creature, which has no exact +rules to go by. It changes its pace on every occasion--fear, joy, every +emotion which agitates the soul, quickens or retards its movements; +and derangements of health may be detected by its pulsations, which +are infinitely varied in character. In fever, for instance, which is +nothing but a race of the blood at full speed, the hearts of grown-up +people beat as quickly as those of little children; sometimes, indeed, +more quickly still. In certain maladies it goes with great sudden +leaps, like a galloping horse; in others it trots in little jerks; +while in some cases it moves slowly and wearily, and its throbs are +so weak that one can scarcely feel them. + +These pulsations, then, afford important revelations to the doctor. +The heart is for him a gossiping confidant, who lets out the secrets +of illnesses, however closely they may fancy themselves hidden in the +remote depths of the body. When the doctor lays his finger on the +patient's pulse, it is precisely the same thing to him as if he had +laid it on his heart, only with this difference, that the one is much +less difficult to do, and much sooner done than the other. + +The artery of the wrist is in fact a small heart, not only because it +follows all the movements of the large one, but because it carries +forward the work which the other begins, and assists also in propelling +the blood to the furthest extremities of the limbs, driving it on in +its turn at each of its own contractions. Imagine a fire-engine, whose +pipes should take up and drive forwards along their whole length the +water which is thrown upon the fire, and you will have some idea of +the marvellous machine which is at work in our behalf within us. Nor +are you to suppose that the wrist-artery is a specially privileged +one, because it has been chosen to hold intercourse with physicians. +All the others are equally serviceable; and if they cannot all be +used for "feeling the pulse," it is because they are generally more +deeply buried in the flesh, where it is not easy to reach them. + +Observe your mother when she is packing a trunk, and you will see that +whatever she is most afraid maybe spoiled, she is most careful to put +in the middle, so that it may be least exposed to accidents. And this +is what a kind Providence has done with the arteries, which have the +utmost cause to dread accidents; whilst the veins, which are much +better able to bear rough usage, are allowed to wander about freely +just under the skin. But when the bones happen to take up a great deal +of room, and come near the skin themselves, as is the case in the +wrist, the artery is forced, whether he likes it or not, to venture +to the surface, and then we are able to put our fingers upon him. + +And there are others in the same sort of situation; the artery of the +foot for instance. But only just think how far from agreeable it would +be to have to take off your shoe and present your foot to the doctor! + +The artery which passes to the temple, just by the ear, is another +affair. That would answer the purpose very well in fact, and I even +advise you to make use of it when you want to feel your own pulse. It +is more easily found than the other even, and its pulsations are still +more easily perceptible. Nevertheless, when all is said and done, it +is better for the doctor to take his patient by the hand than by the +head. Merely as a matter of good manners. + +I will now make you acquainted with the principal arteries, and the +manner in which they distribute the blood through the body. + +The whole of the blood driven out by the left ventricle at each of its +contractions, passes into one large canal called the _aorta_. The +_aorta_ as it goes away at first ascends; then bends back in a curve; +and from this curve, which is called the _arch of the aorta_ (from its +shape) diverge right and left, certain branch-pipes which carry the +blood into the two arms and on each side of the head; and which are, in +fact, the beginning, or upper end, of those whose pulsations we feel +with our fingers in the two wrists and at the temples. + +The supply to the upper part of the body being secured, the _aorta_ +begins to descend. But now imagine of what importance it must be, that +this head-artery--the foster-father of the whole body--should be +sheltered from every accident. The _aorta_ once divided, death is +inevitable; you might as well have your head cut off at once; and +thus it has been fixed in the best--that is to say, the safest--place. +Of course you know what is meant by the _backbone_ or _spine_, called +also the _vertebral column_, in consequence of its being made like a +sort of column composed of a series of small bones fastened together, +which are named _vertebræ_. Touch it and feel how solid it is, and how +few dangers there can be for anything placed behind it. Well, that is +the rampart which has been given to the _Aorta_. As this descends, it +slips behind the heart and takes up its place in front of the _vertebral +column_ which it follows all the way down the back, just to the top of +the loins. There it is, so to speak, almost unassailable; in fact hardly +any cases are known of the _Aorta_ being wounded; to get at it, it would +be necessary to bestow one of those blows which used to be given in the +time of the Crusades, which cut the body in two. There was an end of the +_Aorta_, as of every thing else then; it was unfortunately not worth +talking about any longer! + +The next time you see a fish on the table, ask to be shown the large +central bone. It is the fish's _vertebral column_, and it will give you +an idea of your own, for it is constructed on the same plan. You will +perceive a blackish thread running all along it--that is _the aorta_. + +As it descends, the _aorta_ sends off on its passage a great number of +arteries which carry the blood into all parts of the body. Arrived at +the loins it forms a fork; dividing into two great branches, which +continue their descent, one on each side the body, down to the very +extremities of the two feet. + +As you perceive, dear child, this is not very difficult to remember. +A large fork, whose two points are at the tips of the feet, the handle +of which curves at the top like the crook of a crozier; from this curve +come four branches, which pass into the two arms and to the two sides +of the head--and this is the whole story. But of course, it would be +another affair were I to enter into the detail of all the ramifications. +Here it is that all engineers, past, present, and future, are baffled, +defeated and outdone! Choose any place you please upon your body, and +run the finest needle you can find into it what will issue from the +puncture? + +"Thanks for the proposal," you say; "I have no occasion to try the +experiment, to discover that blood will come out." + +You say that very readily, young lady; but have you ever asked yourself, +what is implied by your being so sure before hand that you can bring +blood from any part of your body if you choose to prick it, though +never so slightly? It implies that there is not on your whole frame +a spot the size of a needle's point, which has not its own little canal +filled with blood; for if there were such a one, there at any rate the +needle would pass in without tearing the canal, and causing the blood +to flow out. And now count the number of places from the top to the +bottom of your dear little self, on which one could put the point of +a needle, and even when you have counted them all, do not fancy you +have arrived at the number of the tiny tubes of blood. Compared to +these, your needle is a coarse stake, and tears not one but a thousand +of these little tubes in its passage. + +That seems to you rather a strong expression, does it not? But let me +make good my boldness. A needle's point is very fine, I admit; but a +person who could not see it without spectacles must have very poor +sight. Whereas the last subdivisions of the blood-tubes are so +attenuated, that the best eyes in the world, your own included, cannot +distinguish them. You are astonished at this, and yet it is nothing +compared to what follows. + +No doubt you have heard of the microscope,--that wonderful instrument +by which you may see objects a thousand, a hundred thousand, a million +times, if necessary, larger than they really are. With the microscope, +therefore, as a matter of course, we can see a good many of those tiny +canals which elude our unaided sight. But, alas! we discover at the +same time that these are by no means the last subdivisions. The canals +invisible to our naked eyes subdivide themselves again into others, +and these into others again, and so it goes on, till at last--the man +at the microscope can see no more, but the subdivisions still continue. + +You were ready to exclaim, at my talking of thousands of canals being +torn by a needle in passing through; but had I even said millions, it +may be doubted whether I should have spoken the whole truth. + +Besides, when you consider the office of the blood, you can easily +understand that if there were a single atom of the body left unvisited +by him, that atom could never be nourished. Do I say nourished? I have +made here a supposition altogether inadmissible; it could have no +existence at all, since it is the blood only which produces it. + +These imperceptible canals of blood have been called _capillaries_, +from the Latin word, _capillus_, which means a hair; because the +old learned men, who had no suspicion of the wonders hereafter to be +revealed by the microscope, could think of no better way of expressing +their delicacy, than by comparing them to hairs. Very likely they +thought even this a great compliment, but your delicate fair hairs, +fine as they are, are absolute cables--and coarse cables too, believe +me, compared to the _capillary vessels_ which extend to every portion +of your body. + +Observe further, that each of these arterial _capillaries_ is +necessarily composed (being the continuation of the large ones) of +three coats enclosed one within the other, which can be perfectly +distinguished in arteries of a tolerable size; add to this that within +these coats there is blood, and in the blood some thirty substances +we know of, not to speak of those we do not know; and then you will +begin to form some notion of the marvels collected together in each +poor little morsel of your body, however minute a one you may picture +to yourself. + + + +LETTER XV. + +THE NOURISHMENT OF THE ORGANS. + +When I said formerly that our dear and wonderful steward the blood, +was everywhere at once, you little suspected the prodigies involved +in that _everywhere_. But you will have a glimpse of them now, when I +tell you it is at the extremities of the _capillary arteries_ that he +carries on his distribution of goods, and accomplishes a mysterious act +of nutrition; a wonder much greater even than that of which we have just +spoken. Here, indeed, the question is no longer mechanical divisions, +whose delicacy, surprising as it may be, is yet within our powers of +comprehension. What is more surprising still, what moreover we cannot +comprehend at all, is the delicate sensitiveness of tact--I would almost +say of instinct--with which each one of the million millions of tiny +atoms of which our body is composed, draws out of the blood--the common +food of all--exactly that aliment which is necessary to it, leaving the +rest to his neighbor, and this without ever making a mistake. + +You have never thought about this; for children go on living at their +ease, as if it was the simplest thing in the world to do; never +suspecting even that their life is a continued miracle, and never, of +course, therefore, feeling bound to be grateful to the Author of that +miracle. And alas! how many hundreds of people live and die children +in that respect. + +But what would happen, I should like to know, if the eye took to seizing +upon the food of the nail, if the hairs stopped on the way what was +intended for the muscles, if the tongue absorbed what ought to go to +the teeth, and the teeth what ought to go to the tongue! Yet what +prevents their doing so? Can you tell me? They all drink alike out of +the same cup. The same blood goes to furnish them all. The substances +that it brings to the eye are the same as those which it brings to the +nail; and nevertheless the eye takes from it that which makes an eye, +and the nail that which makes a nail. + +How is this done, do you think? that is the question. + +When the doctors reply to this, that each organ has its peculiar +sensibility, which makes it recognize and imbibe from the blood one +particular substance and no other, they are strangely mistaken if they +flatter themselves that they have really answered anything. They have +done nothing but reproduce the question in other words, for it is +precisely that sensibility which requires explanation, and to tell us +that it exists, does not explain much, you must own. If you were to +ask why you had got a headache, and some one were to reply that it was +because your head ached, you would not be much the wiser I fancy. + +Each of our organs, then, may be considered as a distinct being, having +its separate life, and its particular likings. These organs behave +towards the blood like men who recognize some friend in a crowd, and +proceed to seize him by the arm; and when I told you just now that +they never made a mistake, I spoke of their regular course of action +in ordinary circumstances. Like men, they also make mistakes sometimes, +in certain cases; and take one substance for another, or do not +recognize the one they are in need of; an unanswerable proof that at +other times they exercise a sort of discernment, and do not act by a +sort of fatality, as one might be tempted to believe. Look at the +bones, for instance. They are composed of _gelatine_ (which cooks +serve up under the name of meat-jelly, but which would be more properly +called bone-jelly), and of phosphate of lime, a kind of stone of which +we have spoken before, if I remember rightly, and from which they get +all their solidity. Originally, the substance of the bone is entirely +gelatinous, and the phosphate of lime deposits itself therein by +degrees, as time goes on, and always in greater abundance as we advance +in age. + +Properly the bones borrow only gelatine and phosphate of lime from the +blood. But when they come to be broken, their texture or _tissue_ +inflames in the fractured place; and then it changes its tastes, if +I may so express myself; and, lo and behold, extracts from the blood +that which forms certain little fleshy shoots, which unite together +from the two sides of the fracture, and so mend the broken bone. Here is +one exception to the rule. + +Again, in certain diseases, the bones suddenly quarrel with the +phosphate of lime; they will not hear of it any longer, they will not +accept a fresh supply; and as the old wears out by degrees, by reason +of the continual destruction of which I spoke the other day, the bones +become more and more enfeebled, and soon can no longer support the +body. A second exception this. + +Finally, when old age comes on, the bones end by being so much +encumbered with phosphate of lime, that they have no room to admit the +fresh supply which keeps coming to them in the blood. What becomes of +it then? It goes to seek its fortune elsewhere; and there are charitable +souls, who forgetting their instinctive antipathies, consent to give +it hospitality, though much to the prejudice of the poor old man +himself, who is no longer served so well as formerly, by the incautious +servants who have allowed themselves to be thus fatally beguiled; but +no one consults him. It is the arteries especially, and sometimes +the muscles, which take this great liberty, and it is not unusual among +old people to meet with these fairly _ossified_--that is to say, +changed into bone, thanks to the phosphate of lime with which they +have consented to burden themselves. This is a third exception, and +I will spare you any others. + +What may we infer from all this, my dear child? Well, two things. +First, that we know nothing at all about the whole affair; a fact which +at once places us on a footing with the most learned philosophers in +the world. Secondly, that our body is a perpetual miracle; a miracle +which eats and drinks and walks, and which we must not look down upon +for so doing: for God dwells therein. I should have to come back to +this at every turn, if I wanted to fathom everything I have to tell +you about. Each tip of hair which you grow, is an incomprehensible +prodigy which would puzzle us for ever, if we did not call to our aid +those eternal laws which have made us what we are, and to which it is +very just our spirits should submit, since we could not exist for one +second were they to cease from making themselves obeyed in our bodies. + +Reflect on this, my dear little pupil. Young as you may be, you can +already understand from it, that there is above you something which +demands your respect. The good God, to whom your mother makes you pray +every night, on your knees, with folded hands, is not so far off as +you might perhaps suppose. He is not a being of the fancy, secluded +in the depths of that unknown space which men call Heaven, in order +to give it a name. If His all-powerful hand reaches thus into the +innermost recesses of your body, His voice speaks also in your heart, +and to what it says you must listen. + + + +LETTER XVI. + +THE ORGANS. + +Contrary to my custom, my dear child, I made use, in the last chapter, +of a new word, without giving an explanation of it. + +I spoke to you of _our organs_, and we have not yet ascertained what an +_organ_ is. + +You probably knew what I meant, because it is a word which is used in +conversation and pretty well understood by everybody. But I am bent +upon giving you a more exact idea of it, for the trouble will be well +bestowed. If I did not do this at once it was because there is a good +deal to tell about, and that would have carried me too far away from +my subject. + +_Organ_, comes from the Greek word _organon_, and means _instrument_. It +was used particularly to signify instruments of music, so much so that +our word "organ" comes from it. Our bodily organs then, are +_instruments_, or _tools_ if you like it better, which have been given +to us, wherewith to perform all the acts of life; and as there is not +one part of the body which is not of use to us for some purpose or +other, our body is, in point of fact, from head to foot a compound of +_organs_. Thus the hand is the tool which we make use of to lay hold of +anything--so an _organ_; the eye is the instrument of sight--so an +_organ_; the heart is the machine which causes the blood to circulate-- +so an organ; the liver fabricates the bile--it is an organ therefore; +the bones are the framework which support the weight of the body--so +organs; the muscles are the power which sets the bones in movement-- +organs also, therefore; the skin is the armor which protects them--so an +organ: in fact everything within us is an organ. If there was any corner +of our body which was not an organ, it would be useless to us, and we +should not, therefore, have received it, because God makes nothing +without a use. + +Here lies the secret of that great miracle which is called life. I do +not know whether you will be able to understand me thoroughly, but +open your ears, as if some one was going to explain addition to you; +this is not more difficult. + +Life is in reality the total of an addition sum. Each one of our organs +is a distinct being which has its particular nature and special office; +its separate life consequently; and our individual life is the sum +total of all these lesser lives, independent one of the other, but +which nevertheless blend together by a mysterious combination, into +one common life, which is everywhere and nowhere at the same time. It +follows from this, that the more organs a being has, the greater is +the sum total; the more, consequently, is life developed in him. +Remember this when we begin to study life in the lower animals. In +proportion as you find the number of _organs_ diminish, you will +find life diminishing in power, until we arrive at beings who have, +as it were, only one organ apparent, and whose life is so insignificant, +that we have some difficulty in giving an account of it, and are saying +the utmost that can be said in calling it life at all. + +But this comparison of life to the total of an addition sum, is too +dry; and, although it has its appropriate side, yet it might give you +a false idea of life; which is what always happens when one tries to +solve inscrutable questions and hidden mysteries by a matter-of-fact +illustration. + +Let us try for something more to the purpose. + +I told you that the Greek word _organon_ was applied especially +to instruments of music. Well, let us consider our organs as so many +musical instruments. You have, probably, sometimes been at a concert. +Each of the instruments in the orchestra performs its own part, does +it not? The little flute pipes through all its holes; the double-bass +pours thunder from its chords: the violin sighs with his; the cymbals +clash; the Chinese bells dance to their own tinkling; all go at it in +their own fashion, each independently of the other. And yet, when the +orchestra is in good tune together, and well played, you hear but one +sound; and to you the result of all these various noises, each of which +would have no meaning alone, is music composed by some great artist +whom you do not see. It is no longer a flute, a double-bass, or a violin +which you hoar; it is a symphony of Beethoven's, an oratorio of Haydn's, +or Mozart's overture to _Don Juan_. + +Life is just like this. All the instruments are playing together, and +there is but one music; music written by God. + +But wait! when I say _life is just like this_, let us come to an +understanding. Life is _some_thing like it, that is all, for as +to telling you what life is, I shall not attempt it. I know nothing +about it, do you see, though that is a painful confession to have to +make to a pupil; but in this case it does not distress me, and you are +welcome to hunt the world through for a master, who in this matter +does know anything. I could make a hundred other comparisons, but +theywould all fail in some point or other. Shall I tell you where this +one fails? In an orchestra there is always a musician by the side of +the instrument. Now with us we see the instrument well enough, but we +cannot see the musician. + +You are inclined to ask me, perhaps, why I am wasting so much paper +to-day in talking to you about organs, instead of going on tranquilly +with our little history of the circulation. But I told you just now +that the secret of life lies in the organs, and before entering upon +the history of life, I ought to have begun with them. It is there all +the books begin which treat of the subject we are studying together, +and if you had one in your hands at this moment, it would teach you +that all creatures whatsoever are divided into those which have organs +and those which have none--that is, into _organic_ and _inorganic_ +beings [Footnote: A lump of iron is the same throughout. Each of its +parts has the same properties and the same uses. It has no organs, it is +an _inorganic_ being. A rose tree has flowers, which are differently +made from its leaves, and serve a different use: a root which sucks up +the precious food of the earth; a bark which is of a different nature +from the wood, and serves a different purpose. It has organs; it is an +_organic being_: all animals and vegetables are _organic beings_.] (_in_ +stands here for _not_, as _in_complete means not complete). + +This is, in fact, the starting point for the study of nature, and there +are many other things besides which I ought to have told you before +I began. But we went straight ahead, without looking at what we were +leaving behind, satisfied with turning aside from time to time to pay +our debts. + +And while I am making my confession, I ought to tell you all. You would +probably only have listened to me with half an ear, if I had begun at +the beginning. There is a proverb which says--"The appetite comes with +eating." I do not advise you to follow this proverb too closely at +dinner, for it might mislead you sadly. But it is always true when +applied to learning; it is what one knows already that gives one a +taste for learning more. If I have been making you bite at the organs +to-day, which is rather a tough morsel, it was because I fancied that +your appetite had begun to come. Was I wrong? + +Let us now return to the blood which nourishes the organs. + + + +LETTER XVII. + +ARTERIAL AND VENOUS BLOOD. + +It is at the extremity of the capillary arteries, as we have said, +that the incomprehensible prodigy of the nourishment of our organs is +accomplished. This done, the next thing is for the blood to return to +its starting-point; and here recommence those infinitesimally minute +wonders of which we have already spoken. Close upon the capillary +_arteries_ follow the capillary _veins_, equally fine and imperceptible +as the others. These take possession of the blood everywhere at once, +without allowing it a moment's respite, and it is thenceforth on its +road of return, travelling back again to the heart. + +Where do the veins begin? where do the arteries end? No one can say +precisely, since the last ramifications of each elude the eye of man, +however much it may be aided by the admirable instruments which his +genius has invented. Nevertheless, although no one has ever ascertained +the fact by sight, there is one thing I can tell you--namely, that our +minute veins are a continuation of our minute arteries, and that it +is the same canal which as it lengthens out turns from an artery into +a vein, without any interruption; the substances destined for the +nourishment of the organs passing through its walls, as moisture passes +through our skin when we perspire. + +But if nobody has seen this, say you, how can they know it for a fact? + +Let me explain. In man, and in the animals which come nearest to man +in structure, it has never been seen; but it has been seen elsewhere. +This requires a little explanation, and you will not regret my giving +it hereafter. It has its interest, I assure you. + +When you put your hand on your throat, how does it feel to you? +_Warm_, does it not? And when you take hold of a kitten or a bird, +how do they feel? _warm_ in the same way. Now, then, can you tell +me whence comes this warmth? But to save time I will answer the question +myself. It comes from their and your _blood_, which is itself warm, and +we shall soon see why. You have no idea of all the curious facts wrapt +up in that little phrase, "You are warm-blooded;" your blood is warm. +But it has not got warm of itself; bear that well in mind. + +Now if you touch a frog, a lizard, or a fish, how do they feel to you? +Cold, of course, you answer. But I ask why? A question you will answer +in the same way as the other. Because their blood is cold, they are +"cold-blooded." + +Precisely; and while you are about it you may add that, if their blood +be cold, it is because it has not been warmed as yours is. Do not be +impatient, we shall make all this clear at the proper time and place. + +Now in the cold-blooded animals, such as serpents, frogs, tortoises, +lizards, fishes, and others, the blood circulates as it does in us, +and what is more, it does so, thanks to a machinery very similar to +our own. But, as you may imagine, a machine which produces warmth must +be constructed in a more perfect manner than a machine which produces +no warmth; and to speak truth, without flattering you, there is a +little difference between you and a frog, and it seems natural enough +that the body of a frog should be more clumsy in structure than yours. + +It is the old story of the poor man being not so well lodged as the +rich; but putting aside rich and poor, who are all human beings alike, +let us take one of those lovely dolls who walk, and move their arms +and head, and say papa! and mamma! and compare it with a cheap bazaar +doll which you can get for a penny. Both are made, in the main, in one +way. Each has two arms, two legs, a mouth, a nose, eyes, &c.; but what +a difference in the details of the two! and what infinitely more pains +have been bestowed on one than on the other! + +Well, cold-blooded animals are, so to speak, _penny doll_ animals, +by comparison with ourselves. Like us they have arteries and veins, +but there is not near so much workmanship in them; and that marvellous +delicacy of the capillary extremities, which in man and in the +warm-blooded animals drives the close observer to despair, does not +exist to trouble us in these others. It is true that with the naked +eye we are still unable to see everything, even in them; but with the +help of the microscope the whole is laid open to us--the extremities +of the arteries and the extremities of the veins; and it was here that +what I was telling you of, just now, was observed and discovered,-- +namely, that the end of the artery changes into a vein, without any +interruption in the tube. It was these very observations upon fishes and +frogs, which eventually gained the day in favor of Harvey's ideas on the +circulation of the blood, at which the learned men of his own age had +laughed so much. He was dead by that time it is true, as has happened +but too often in such cases, but do not let us pity him too much! He who +has had the rare good-fortune to lay hold of a new truth, and launch it +into the world, is sufficiently recompensed in advance. If he also +craves after the flattering voice of man's approbation, and the toylike +pleasure of personal triumph, he is after all but a child, unworthy of +the great part God has given him the privilege of playing. + +A child, did I say? Then how rude you must have thought me, dear child! +And as a punishment, you are perhaps going to remind me that I have +once more fallen into my old bad habit of wandering away from my +subject. Never mind, I am going to return to it at once. + +How can one distinguish--you will ask me--an artery from a vein, so +as to be able to determine which is a vein and which an artery? + +In many ways, I reply. First of all, an artery, as I told you lately, +is composed of three coats, of which the principal, _i.e._. the +inner one, is tough and elastic, whereby the artery is enabled to force +the blood forward in its turn, but which is also the reason of arterial +cuts being so dangerous; for in such cases the wounded tube remains +wide open; being held so by the stiffer inner coat; and thus the blood +is allowed to run out indefinitely. Now this inner coat is wanting in +the veins, whose walls sink in together when a cut is made in them, +so that it is much easier to stop the flow of the blood in them. + +Furthermore, the veins are furnished inside at intervals with little +doors, similar to those we noticed at the entrance of the _auricles_ and +_ventricles_ of the heart. You remember those important _valvelets_, on +which depends so much of the mechanism; which permit the blood to pass +in one direction, but will not allow it to return back in the +other?--well, the little doors of the veins, which are also called +_valvelets_, do exactly the same work. They open in the direction of the +heart, to allow the blood to pass on, but it finds them fast closed if +it wants to go back; so that as soon as it has forced one passage there +is no longer any hope of its return, and thus by degrees it gets nearer +and nearer to the heart without any possibility of escape. There is +nothing similar to this in the arteries, which the blood traverses in a +single bound from the impetus it receives from the heart. + +Finally--and this is most important--the blood which is found in the +veins is no longer the same as that which fills the heart. + +No longer the same? you exclaim--have we then two sorts of blood in +our bodies? Most certainly, my dear child; but you would not have +suspected it; for when you accidentally prick or cut yourself, or when +your nose bleeds, it is always the same sort of blood that comes +out--that fine red liquid which everybody knows so well by sight. This +is because the blood flows at once from the small arteries and small +veins, and what you see is a mixture of the two. The same mixture +issues from all wounds, whether small or great, and on this account +people are unanimous in declaring that blood is red; a statement which +is not true of either arterial or venous blood, separately. The last +is black, as you might convince yourself if you had courage enough, +and should happen to be in the room with any one who was going to be +bled,--a rare event, happily, in these enlightened days. + +In such a case it is always a vein which is opened, the reason of which +you will understand, after what I said of the danger of cutting the +arteries. You would there, fore see a reddish black jet of liquid spout +from under the lancet; much blacker than red, however--that is +_venous_ blood. When, on the other band, an artery has been accidentally +cut, what comes out is quite different. It is a rosy, frothy fluid, +almost like milk and carmine dissolved in it, which has been whipped up +with a stick; this is called _arterial_ blood. + +Nothing is more simple, as you perceive, than to distinguish an artery +from a vein; you have only to ascertain what is inside of it. When the +blood goes out to our organs to nourish them, it is _arterial_; when it +is returning back after having nourished them, it has become _venous_. +But what--you will ask--is it going to do now at the heart, towards +which it is on its road? It is going to seek there a fresh impetus which +shall send it once more into the lungs, where it will again become +_arterial_, _i. e._ and once more capable of affording nourishment to +the organs. Therein lies the whole secret, and the why and the wherefore +of the CIRCULATION. + +This is easily said, dear child; but suppose that you do not comprehend +it? Well, you need not be ashamed. There is no possibility of +comprehending it until one has learnt what RESPIRATION is--so here we +are stopped short. + +To-morrow, then, when we will begin with the study of this third part +of the History of Nutrition; and if the first two have amused you, I +feel pretty sure you will not find this last one dull. + + + +LETTER XVIII. + +ATMOSPHERIC PRESSURE. + +When we have been laboring very hard, my dear child, and want to rest +for a minute, we say, _Let us take breath_; because breathing is +an action which takes place of itself, requiring neither effort nor +attention on our part. + +But, if it takes place of itself, it does not explain itself; +consequently, when I say to you, _Now, let us take breath_, this +is not a signal for my having a rest, for I have undertaken to explain +Respiration to you. + +If you were a German, I would remind you of what so often happens when +you put a fork into a dish of sour-krout. You want to lay hold of a +little bit merely, but the strips of cabbage-leaf are twisted one +within the other, and hang together in spite of you, so that +withoutintending it you get hold of a whole plateful at once. + +Now this Respiration affair is something like the sour-krout +story--begging your pardon for the comparison. I should have liked to +give you only a small plateful--a child's plateful--of it; but I feel +the explanations coming, hanging one upon the other; and, whether I +will or no, I must treat you like a grown-up person, and we must give +up for once the nice little doll's dinners with which we began. + +In my opinion, you will lose nothing by the change if you will but pay +attention; for about that soft little breath of yours, which is always +coming and going over your pretty lips, there are many more things to +be learnt than you have heard of yet. As I said just now, you will +find you have got hold of a plateful all at once. A good appetite to +you! + +To prevent confusion we will divide the subject into two parts. I shall +explain to you first, _How we breathe?_--a very curious question, +as you will see. And afterwards we will examine, _Why we breathe?_-- +which is still more interesting. + +First, I must tell you that air is heavy, and very heavy too; a thousand +times more so than you may suppose. The air we breathe, through which +we move backwards and forwards, that air is _some_thing, remember, +although we do not see it; and when there is a wind, that is to say, +when the air is in motion, like a stream of water running down a hill, +we are forced to acknowledge its being something, for we see it throw +down the largest trees and carry along the biggest ships. But without +going so far out of the way for examples, try--you who run so well--to +run for two minutes against a strong wind: and then you shall tell me +whether the air is something or nothing. But if it be something it +must have weight, for all substances have; paper as well as lead; with +this sole difference, that the weight of lead is greater in proportion +to its size than that of paper. Now a sheet of paper is very light, +is it not? and you would be puzzled perhaps to say what it weighs. But +many sheets of paper placed one upon the other, end by forming a thick +book which has its undeniable weight; and if some one were to heap +upon your head a pile of large books, like those you see on your papa's +shelves, the end might be that you would be crushed to death. + +In the same way, a small amount of air is by no means heavy; but you +can conceive that a great quantity of it gathered together may end by +weighing a great deal. Now get well into your head the fact, that we, +here, on the surface of the earth, are at the bottom of an immense +mass of air, extending to somewhere about forty or fifty miles above +our heads. Let us say forty to make more sure, for learned men have +not yet been able to calculate the precise height to a nicety; and for +my own part, I think we have done wonders to get so near the mark even +as this. But can you picture to yourself the distance which forty miles +high really is? I will help you to form some idea. + +One mile contains 5,280 feet, and your papa is six feet high. One mile +high would therefore be 880 times as high as your papa, But this is +a mere nothing--only one mile's height. In forty miles there would be +no less than 211,200 feet; and setting papas aside, of whom it would +take 35,200, one on the top of the other, to go so far into the sky, +let us think of the height of the tallest buildings you know; church +and cathedral towers for instance. Now the towers of many parish +churches are 150 feet high; the towers of York Minister not 300. At +that rate it would take 1,408 ordinary parish church-towers, or upwards +of 704 York Minster towers, piled one above the other, to reach to the +end of the forty miles of air above our heads. I leave you to judge +what would be the weight of a mass of paper piled up as high as that. +You may safely grant then, that this mass or pile, or if you like it +better, this _column_ of air (for that is the proper expression), +must be of considerable weight; as is still further made certain by +the fact of its having been weighed, so that I can even name the weight +to you if you wish to hear it. Bear in mind too, that the weight of +a column of air will be in proportion to its _superficial extent_--to +its breadth and width, that is; for, as you may suppose, a column as +large in extent as one of the towers of York Minster will weigh a good +deal more than one the size of a single brick. + +But wait; here is a book on the table which will serve me for a measure, +and as you will probably find the same on your mamma's table, you can +follow my measurement. It is a French Grammar. The back is seven inches +long and four and a quarter wide. That is, there are four and a quarter +rows, each seven inches long. In other words, the back contains +nearly--and let us call it quite, for convenience' sake--thirty inches +side by side. Thirty _square inches_ as it is called. Measure your +mamma's copy and you will see. Now, can you guess the weight of the +column of air forty miles high which this volume supports? Upwards +of four cwt.; 450 lbs., that is to say. If you want to be very exact, +here is the rule. Air presses on all bodies at the rate of fifteen +pounds to every square inch; so now you can make the calculation for +yourself. + +But I suspect you had no idea you were so strong; for I see you tossing +up the book, heavily laden as it is, like a feather. + +Comfort yourself. There is no magic in the matter. If a very strong man +were to push you on one side, could you resist him? Certainly not. But +if another man of equal strength were to push you at the same time on +the other side, what would happen? Well, you would remain quietly in +your place, without troubling yourself more about one than the other, +the two forces mutually destroying each other. And this is the case +here. While the air above your book is weighing down upon it with a +force of 450 lbs., the air below it presses against it underneath with +an equal weight, and this destroys the effect of the other. From 450 +lbs. take 450 lbs., and nothing remains. Your grammar has nothing to +carry after all, and you may toss it about as you please, without +deserving much credit for the effort. + +"What are you telling me?" you inquire. "If I put a stone on the top +of my head, I can feel its weight easily enough; but if I put my hand +on the top of the stone I no longer feel anything. How can the air +below the stone press against it? And talking of columns--how pleasant +it would be, for instance, if the people who go up the Monument were +to have the weight of it on their heads when they get to the top!" + +Well said, little one. And your objection reminds me of an argument +which distracted my head as a lad, when I first heard the pressure of +air explained by a good fellow who did not trouble himself to be quite +as exact as you and I are in our discussions. I was told that the +surface of the body, or the skin of a large man, measured sixteen feet +square, which is equal to the surface of a table four feet long and +four broad. Now, you know that in four feet there are forty-eight +inches, and on the surface of the table are forty-eight rows, with +forty-eight inches in each, or 2,304 square inches; so that a man's +surface is 2,304 square inches, and the weight his body supports is +34,560 lbs., or upwards of fifteen tons--always at the rate of fifteen +pounds to every square inch, you understand. Now, I was constantly +asking myself how it happened that in entering a house one never seemed +to get rid of this almost fabulous weight, since the roof of the house +must naturally interpose itself between the air-column of forty miles +high and the man who would then only have some few feet of air above +his head. The roof would support the rest, that was clear. From whence, +then, came the 34,560 lbs. which seemed to weigh as heavily as before; +since, whether on the threshold of the door, while still under shelter +of the roof, or two steps outside in the open air, under the tremendous +column forty miles high, one never felt a bit lighter, not even to the +extent of the weight of a single sheet of paper? This was a difficulty +from which I could never extricate myself. + +I found out the answer to the riddle afterwards, and a very simple one +it is. + +Air does not, in point of fact, _weigh down_ like a solid fifty +pounds' weight, which has no impulse but to descend, and has nothing +to do with anything above it. It _presses against_ rather, like +a spring, which, having been compressed, tries to resume its natural +position with a force equal to that which holds it back. Ask some one +to show you the spring of a watch, and you will understand this better. +Each atom of air is a spring of matchless elasticity, which nothing +can break, which never wears out, which one can always compress, if +one employs force sufficient, and which is always ready to expand +indefinitely, in proportion as the compressing power is withdrawn. + +Now, consider the column of air outside the door, where there is a +pile of such springs forty miles high. The lower ones have to bear up +all their comrades, which press upon them with their united weight, +and these make desperate efforts to repulse the tremendous pressure, +and to spread out in their turn. They endeavor to escape in every +direction--to the right, to the left, above, below; but caught between +the earth, which will not give way, and the compact mass of all the +columns of air which surrounds the earth in every direction, and of +which the lower part is equally compressed everywhere, they struggle +unceasingly, but in vain; indefatigable, but powerless. You live in +the midst of those little wrestlers, and naturally bear the punishment +of the injury done to them. They press against you as against every +thing else--before, behind, on all sides--with a force equal to thatwith +which they are themselves compressed, or I would say, equal to +the weight by which they are so horribly squeezed and contracted: so +that, in fact, you bear this weight not only on your head and shoulders, +as you might at first suppose, but also all along your body and limbs, +under your arms, under your chin, in the hollow of your nostrils, +everywhere. + +Now we will suppose you to enter the house; and what do you find there? +Outer air, which on its part has got in by the door, the window, and +every little crevice in the wall. The column outside the roof no longer +presses upon it, but what is the gain of that? + +It was compressed when it got in, and the little springs will struggle +as a matter of course, quite as much on this side of the door as on +the other. The protecting roof has so little power that were it not +itself protected by the air outside, the pressure of which keeps it +in its place, the air within would shiver it into a thousand fragments +in its efforts to get loose. + +You laugh; but wait till I explain myself further. I will take the +case of a miniature house to make the matter pleasanter to you; one +fifteen feet long, fifteen feet wide, and with a flat roof, the most +economical plan as regards space. Fifteen feet are five yards, and as +the multiplication table tells us that five times five make twenty-five, +our roof will in this case be twenty-five square yards (_i. e._ +225 square feet) in superficial extent, or _area_; it is not much, +and you will find few as small. + +Would you like to calculate the force with which the millions and +thousand millions of little spring imps imprisoned under that poor +unfortunate roof would press against it? We settled before that the +quantity of them brought to bear upon a square inch had the power to +push at the rate of fifteen pounds. Were they to push against a square +yard (a surface 1296 times greater than the square inch) it would +therefore be 19,440 lbs. This being so for one square yard, calculate +for twenty-five square yards, and you will have the amount of pressure +against our roof--viz. 486,000 lbs--merely that! And now tell me what +cottage roof in the world was ever built so as to be able to stand +against such a weight? + +Perhaps though, you can scarcely appreciate the amount of heaviness, +486,000 lbs. Well, 486,000 lbs. is nearly 217 tons; and one of those +railway trucks that you see laden with coals at the stations can carry, +perhaps, from eight to ten tons, without breaking down. Say ten tons +as an outside estimate, and then think of piling the contents of +twenty-one such trucks on your roof, and yet you would still be short +of the weight of air which is bearing down upon it. I need scarcely +say now that were you to take away the air from within the roof, theair +without would smash both it and the whole cottage flat, as a giant +at a fair strikes an egg flat with one blow of his fist. To show you +how in another way: take a moderate sized column or pillar, such as +you see sometimes in a nobleman's grounds, of about the weight of the +twenty-one tons, and set it up like a chimney on the roof of our +cottage, then walk away to a little distance and watch what will happen! + +There, little Miss Laugher! have you at last learned to value the +weight of the air, or _atmospheric pressure_ as it is more properly +called; since it is the force with which the atmosphere presses against +rather than weighs upon everything on the surface of the globe? It is +no joke, as you perceive, and it affords plenty of subject +forreflection. I have still to prove to you that I have not been making +fun of you with my calculations, and that the weight of air upon a +square inch is really what I have said--viz., fifteen pounds. + +Now, there is a very simple way by which we might get to know your +strength, and tell its amount in figures, if one chose; namely, by +putting a weight on your arms--a heap of books, if you please--and +keep adding and adding to it, until those poor little arms were unable +to bear any more. Then weighing what they had borne, whether we should +find it to be ten or thirty pounds--I cannot guess how much it might +be at this distance--one might safely say, without fear of mistake, +"The strength of this young lady is equal to ten, twenty, or thirty +pounds"--in other words, "she represents a weight of ten, twenty, or +thirty pounds" and by a similar plan people have ascertained the +strength of the air--that is, the weight which it represents. They +have weighed what it is capable of carrying. + +I told you lately that the whole surface of the earth was covered by +an immense army of little imps--otherwise called little air-springs, +which, compressed by the giant mass of their comrades above, all of +whom they have to carry on their backs, are always trying to protect +themselves, by pushing back everything which comes across them. Imagine +the bottom of a well. Our imps are permanently installed there as a +matter of course, and face to face with the water they push against +it, each one doing his best, on all points at once. As the pressure +is equal everywhere therefore, and always the same, there are no signs +of it to be seen. + +Now insert in the water the end of a tube closed below by a cork which +exactly fits the interior, but which can be moved up and down in the +tube by means of a bar of iron or wood which runs through it. This is +called a _piston_, I may as well tell you as we go on. + +When the piston rises in the tube, it drives before it, as it goes, +the air which was already there; and which cannot slip away down the +sides because the piston fits so closely to them all the way along. +The result of this is, that just underneath the piston there is a place +in the water to which the air cannot reach, and at that place the water +has no pressure upon it at all. + +Now see what happens. Pressed upon heavily by the air in every other +part and place, like a mouse hunted by a cat, who finds at last a hole +through which to escape, the poor water darts at this and ascends the +tube close after the piston. + +So far so good; but if the tube is very long, and the piston rises +rather high;--at thirty-three or thirty-four feet above the level of +the water it has to continue its ascent alone. The water parts company, +stopping quietly behind, half-way up the tube. + +"What is the meaning of this?" you will ask. + +It means that the force which presses on the well-water all round the +tube, and thus drives it up, has done all it can, and that our little +air-imps refuse to supply any more. The water which rises in the tube +has a weight of its own of course, and with this weight it presses, +as it is fair it should, on the water below. In proportion as the +piston rises, the column of water which follows it gets bigger and +bigger, and naturally its weight increases at the same time. At last +there comes a moment when this weight becomes such that its pressure +on the water below is equal to that with which the air-imps are pressing +on the water in the well. Thenceforth they may push as they please; +no more water will go up. They are in the same position now that they +were before, when their comrades (afterwards driven out by the piston) +were pressing upon the same point, which had only a moment's freedom; +and this water column of thirty-three or thirty-four feet holds them +in check, to exactly the same extent as the gay fellows whose place +it has taken. + +Nothing is easier now than to calculate, even to a few grains almost, +the force of the pressure of air. One can get at the weight of water, +thank goodness! and it has been ascertained that our water-column will +weigh fifteen pounds if the tube is a square inch in size. You will +comprehend after this that it might be any size you may please to +imagine, without there being the slightest alteration in the height +of the column. The larger it is, the heavier will be the column of +water on the one hand; but on the other, the greater will be the number +of air-imps turned out; so it comes to the same thing in the end. + +If you should feel any doubt about the correctness of this reasoning, +you have only to try the experiment over again, in a well, filled with +mercury for instance. Ask to be shown some pure mercury, which is also +called _Quicksilver_, because one wants to express melted silver, +apt to be constantly on the move; it is often to be met with in houses. +Mercury weighs thirteen and a half times more than water: according +to our calculations, therefore, it would take thirteen and a half times +less of it than of water to bring our little air-imps to reason. And +this is just what you will find happens; you will see the column of +mercury stop short exactly at the moment when it has attained the +orthodox weight of fifteen pounds; that is to say, at a height of +twenty-eight inches. + +On the other hand, take some ether. You know that delicate spirit, +which smells so strong, which makes your hand feel cold if it is put +upon it, and which we give to sick people to inhale. Ether weighs +one-quarter less than water. In a well of ether you would therefore +see something quite different, and your column would rise without being +asked, to something like forty-three feet, exactly up to the point of +weighing--like the others--fifteen pounds to every square inch. Air +will not be replaced with less. + +That, then, is the measure of its strength, or our scales are deceitful. + + + +LETTER XIX. + +THE ACTION OF THE LUNGS. + +I hope I have told you enough, my dear child, to enable you fully to +estimate the force with which air presses upon everything on the surface +of the earth, and consequently upon our own bodies among the rest. + +If you understand this, nothing is easier than to understand how air +comes and goes in our lungs. + +When the cook wants to light her fire with two or three hot coals, +what does she do? + +She takes the bellows and blows it, does she not? + +But if she has no bellows at hand, what does she do? You answer at +once, she blows it herself with all the strength of her lungs. + +By which it would seem--does it not?--that we are a sort of living +bellows, being able, in case of necessity, to act as a substitute for +the wood and leather ones of common use. And if we really possess the +power of doing the work of a bellows, may not this be because we have +within us some little machine of the nature of a bellows? + +Exactly; and this fact gives me the opportunity of making you understand +the action of the lungs by explaining that of the bellows, which is +in everybody's hands, but which three-fourths of the people use, without +troubling themselves to inquire how it is made or acts. + +"A bellows, as you know, is composed of two pieces of board, capable +of being separated and brought together again at will, and united by +a piece of leather so shaped and arranged that it doubles up when the +boards close, the intermediate space forming a firmly-closed box, the +size of which increases or diminishes at every movement of the boards. + +"We take the bellows down to use it, and there are the boards, lying +flat upon each other, the box between them quite small. Is there +anything inside, do you think? + +"Nothing," you answer; "the bellows is empty." + +Do you think so really, my child? Do you think a tumbler is empty, +then, when you have drunk out its contents; and that jelly pots are +empty when all the jelly is eaten? There are not so many empty things +in the world, I assure you, as you suppose. You forget the air--that +monster who is always wanting to stretch himself out, and pushes against +everything he meets. He is an unceremonious gentleman, who takes +possession of every vacant place; as fast as you put a spoonful on +your plate, he takes up the room of the jelly which has been removed, +and at each mouthful you swallow, he slips into the place of the water +which goes away. When you think the glass and pot are empty, they are, +in reality, full of air. You cannot see it; but it is there, you may +rely upon it. + +There is air, then, in the bellows-box, because there is air in every +place where there is nothing else to dispute possession with it. The +quantity is small in this case, no doubt, because the box is small and +cannot hold much. + +But now, look! I separate the boards, and the box, which was small, +becomes large. For once, then, here is a box which must be partially +empty; for it has just, as if by magic, made a space in itself in which +positively there cannot be anything, since there was nothing there +beforehand. + +Ay! but look down at the centre of the upper board. You see a little +hole there, do you not, and below the little hole a small piece of +leather, which seems to close it up? That is a _valve_, one of those +doors, such as we noticed before in the heart, and such as are to be +found, moreover, in most houses, which let people through on one side +but not on the other. This one opens when it is pushed from without, but +lets nothing out which has once got in. Now, the air outside, as I said +before, is always pushing against everything. He pushes as a matter of +course, therefore, against the valve, and as there is nothing behind it +to resist the pressure, in proportion as room is made inside the box, he +enters and fills it with himself. + +But presently some one begins to close the bellows, and he finds himself +caught between the boards; on which these invite him to begone, with +the same sort of politeness displayed by the police, when the hour of +departure comes in a place of public exhibition; when, _i.e._, +they spread out on all sides, and force the crowd before them till +they have found the road to the door. But the air cannot get back by +the way it came in, the door being shut. As, however, it must go out +somewhere, whether it likes it or not, it passes through the tube at +the end of the box (the _nozzle_ of the bellows), and comes out +thence with a rush upon the fire. When it is once gone the bellows can +be distended again, and the process be repeated as before indefinitely. + +And this is just what goes on inside ourselves. Your chest, my child, +is a box which expands and contracts alternately; making a place for +the air by the first effort, and then driving it out by the second. +It is neither more nor less than a bellows, but of a simpler +construction than that used by the cook. The exit pipe serves also for +a door of entrance, and there is but one board instead of two. + +The _exit pipe_ is the _larynx_, of which we spoke before, +when we were talking of swallowing the wrong way, and which communicates +with the air outside, through the nose and mouth at the same time, +allowing us to breathe through either one or the other as we like. + +As to the _board_, I said a few words about it when I was describing the +liver. It is the _diaphragm_--that separating partition--that floor +which is placed between the two stories or divisions of the body--the +belly and the chest. + +But here especially the infinite superiority of the works of God over +the miserable inventions of man comes out in all its grandeur. + +A bellows which was to have the honor of keeping up within us that +miraculous fire--the pre-eminently sacred fire--which we call Life, +required something more than a common board for its foundation. And +accordingly this, of which I am now going to give you a detailed +history, is as marvellous as it is admirable. I fancy that when you +have read my account, you will no longer turn up your nose at the vile +word _diaphragm_. + +Let us first take a peep at the construction of the bellows. + +On each side of the _vertebral column_, from the neck to the loins, +spring twelve long bones, one below the other, bent in the form of bows; +these are called the _ribs_. The first seven pairs of ribs rest, and as +it were, unite, in front, upon a bone called the _sternum_, which you +can trace with your finger down to the pit of the stomach, at which +point the finger sinks in, for there is no more _sternum_, and the last +five ribs on each side no longer unite with those of the opposite one. +For which reason they are called _false ribs_. On the other hand they +are joined to each other at the ends by means of a strip or band of a +substance sufficiently strong, but at the same time flexible, and +somewhat elastic, which is called _cartilage_ or _gristle_. The next +time you see a roasting piece of veal on the table, look well at it, and +you will see at the end a white substance which crackles under your +teeth; that is _gristle_. + +This forms the framework of our bellows, which you may picture to +yourself as a kind of cage, widening towards the bottom and going to +a point at the top, for the arches formed by the upper ribs are smaller +than the others. The whole terminates in a sort of ring, through which +pass, together, the _oesophagus_ and the _trachea_. + +The space between the ribs is occupied by muscles which reach from one +to the other, and the whole framework or cage is shut in below by the +_diaphragm_, that marvellous board whose history I have promised to +relate. + +The _diaphragm_, as I told you some time ago, is a large muscle, thin +and flat, stretched like a cloth between the chest and the _abdomen_. It +is fastened by an infinity of little threads called _fibres_, to the +lower edge of the cage I have just been describing, and it looks at +first sight as if it must be incapable of moving, since it is fixed in +one invariable manner all round the body. + +It moves nevertheless, but not in the same way as the boards of our +bellows. + +Ask your brother to hold two corners of your pocket-handkerchief; take +hold of the other two yourself, and turn the handkerchief so as to +face the wind. The four corners remain in their place, do they not? +but the middle, inflated by the wind, curves and swells out in front +like a ship's sail, which itself is only an immense hand kerchief after +all. Then draw the handkerchief tightly towards you, each to your own +side, and it will recover itself and become flat again. Loosen it a +little and it will curve and swell out again in the middle, and this +maneuver you can go through as often as you choose. + +Which very maneuver the _diaphragm_ is continually performing, of and by +itself. + +In its natural position it bulges upwards in the middle, like a cloth +swollen out by the wind, and thus occupies a portion of the chest at +the expense of the lungs. When air has to be admitted, its _fibres_ +tighten and bring it flat again, as you and your brother brought the +handkerchief flat just now by tightening it. + +The whole space previously occupied by the arch of the _diaphragm_ +is thus given up to the lungs, which, being elastic, instantly stretch +themselves out to it; while air, running in through the nose and mouth, +fills up in proportion the empty place (_vacuum_) created by the +extension of the lungs, exactly as in the case of the bellows. + +But soon the fibres of the _diaphragm_ relax. It rises up again into its +old position, driving back the lungs as it does so; and the air finding +there is now no room for it, goes out by the same way the other came in. +I say _the other_, observe, because the air that goes out is no longer +the same as when it came in; and this is the secret of _why we breathe_; +while the up and down movement of the _diaphragm_ is the explanation of +_how we breathe_. + +As you perceive, then, the mechanism of these bellows of ours, is of +the most simple, and consequently of the most ingenious character, and +leaves far behind it anything we have ever imagined. + +Are you disappointed? Do you feel inclined to exclaim, "Is this all?" +to ask where are the wonders I promised you? to protest that I may +talk as I please about the inflating and flattening of a +pocket-handkerchief? _you_ can see nothing so marvellous in the +matter; nothing worth making your mouth water for. + +A little patience, Mademoiselle! Hitherto we have talked only of the +machine; but there is a goblin inside it, and our fairy tale is going +to begin again. + +There are in some families certain old servants who belong to the +house, more, it may be said, than their masters, in some ways. They +educate the children, and they serve them till death; they live for +them alone, and know so well what they have to do, both by day and +night, that there is no need to give them any orders. Nay, not only +is it unnecessary to give them directions--it is for the most part +labor in vain. They are so completely at home in their business, that +they will go nobody's way but their own. If you wish them to alter +their habits they may obey you for an instant, but it is only to return +into the old groove directly after; for they know better than you do +what you want. + +I was very little when I first read in the story-books of my day, some +bitter complaints of the disappearance of this race of old-fashioned +servants of the good old times. And you very likely may have seen it +said that they are no longer to be met with. Yet there will always be +some, depend upon it, in families, who know how to make and to keep +them. Good old times or not, they have never been found in any other +but these cases. + +Still, _I_ have just such a one as I have described--even I who +am talking to you--and so has your mamma; and what is more, you have +one yourself; and what is more still, everybody else has one. This +servant of the good old times, who will never disappear (and this is +more than one can promise of any other) is the _Diaphragm!_ When +you came into the world, my dear child, and were merely a poor little +lump of flesh, without strength, intelligence, or will; incapable of +giving any orders whatever to those organs of yours, of whose existence +you were not even aware, your _diaphragm_ quietly began his duties, +without leave or inquiry from you, and with your first _breath_ your +life began. Since which he has always gone on, whether you attended +to him or not, and his last effort will be your last sigh. + +When you go to sleep, careless of all that is to happen, until you +awake again, that servant of yours, indefatigable at his post, labors +for you still, and the light breath which half opens your rosy little +lips as it passes through them; that light breath which your happy +mother watches with such pleasure, is his work. Midnight strikes--one +o'clock--two; all around you are buried in sleep--but he is awake +still. Were it otherwise--were he to go to sleep when you do, you +would never awake again! + +This protector of each instant, this faithful guardian of your life, +is, nevertheless, subject to you as a servant to his master. Attend +to him, and he will obey your orders. You can make him go at a great +pace, or slowly, as you choose; or stop him altogether, if the fancy +takes you to do so: but this not for long. The servant of the good old +times is obstinate in the performance of his duties. He will yield to +you in trifles; but do not try to force him over serious matters. I +have read somewhere of a desperate young fellow, chained down in a +dungeon, who killed himself by holding his breath; but I never quite +believed it. Mr. Diaphragm would not allow any one to carry rebellion +so far as that. + +But we have not finished yet, and you do not yet know how appropriate +is the comparison I am making. + +Should any misfortune, any grief, any trifling annoyance even, befall +his master, a good servant suffers with him, and as much as he does; +sometimes even more. Occasionally the master is comforted, while he +remains still disturbed. + +"And the diaphragm?" you ask. + +The diaphragm does precisely the same, my dear child. Yours, especially, +shares in all your griefs to such an extent that, truth to say, he is +not always quite reasonable. The other day when your mamma did not +want to take you into the country with her, he was so sorry for you +that he went into perfect convulsions, and you sobbed and sobbed till +she was obliged to say, "Come, then, you naughty child;" whereupon you +embraced your mamma, and were quite happy again, while he remained +still unappeased, and your poor little chest was shaken more than once +afterwards by his last convulsions. + +Sobbing, you must know, is merely a convulsion--a great shake of the +diaphragm--which is the reason of its causing such a heaving of the +chest. + +It is the same with respect to joy. The joy of the master makes the +servant dance, and so the diaphragm too! Its little internal jumps +are, then, what we call laughter--a thing you are well acquainted with. +Put your hand on your chest next time you laugh (and I hope it will +be soon) and you will feel how it dances--thanks to the diaphragm which +jumps for joy whenever it finds you in good humor. + +Please to observe further, that nothing of all this is done to order. +He starts of himself, poor fellow, without waiting to ask if you will +ever know anything about it; and, in truth, you have known nothing +about it up to the present moment. + +What say you to the diaphragm now, my child? Does not the very name +please you? You scarcely expected to find there--under your lungs--so +good a servant, one so attached to your person, so strongly resembling +in all points the best specimens we know among men. And still we have +not done. I have reserved as a finale for you a new point of resemblance +which will make you open your eyes very wide indeed. + +The old servant is sometimes cross and grumbling. If anything is going +against his grain in the house he has no scruple in saying so; and his +mode of speaking is sometimes rather rude. Nor is it of any use to get +impatient and impose silence on him; he will listen to nothing--it is +his privilege. But let some unforeseen accident happen to his master, +let him see him deeply affected, and in a moment all his anger is over. +He sets himself silently to work again, recalled to order twenty times +sooner by his master's emotion than by his utmost impatience. + +You ask what I am coming to now? My dear child, what I have just told +you is the history of the _hiccup_--the history of the hiccup, neither +more nor less. + +I must first tell you, however, that the _diaphragm_ keeps up +intimate relations with his neighbor below--the stomach. Every time +he rises in the breast the stomach rises behind him; and not only the +stomach, but also its companions, the intestines. All the officials +employed in the business of digestion travel regularly with him; coming +down as well as going up in company. Put your hand upon your abdomen +and breathe strongly and you will feel the rebound of all the movements +of the diaphragm. + +Now, when matters are going on wrongly inside, when too much work has +been imposed on the officials, or work they dislike, or else when they +have been disturbed in their labors, it will sometimes happen that the +_diaphragm_ takes part with his comrades in the abdomen. He gets +angry then, and shakes his master, who cannot help himself a bit. You +must be very well acquainted with these attacks, which are very +fatiguing when they last long. One begs pardon and resists him in vain; +he does as he pleases, without stopping to listen, turning everything +upside down; and do you know the only efficacious plan for calming him +at once? It was a constant source of wonder to me when I was little. +A sudden fright, a start unexpectedly caused by a friendly hand slipping +secretly behind, and laying hold of one, was all-sufficient; disarmed +by the agitation you have undergone, the naughty, stubborn muscle +forgives you, and you are cured. + +Having dwelt so long on the truly wonderful resemblance between the +proceedings of two sorts of beings, whom no one that I know of ever +thought of comparing together before, I will now, my dear child, give +you the key to all these comparisons, which seem so whimsical at first, +but are so striking in reality, and which come to my pen of their own +accord, as it were, in the midst of the explanations I have undertaken +to give you. Many people who would not themselves care for them, will +declare that they are too hard for a little girl to follow. But for +my own part, I find that the eye can take in a mountain as easily as +a fly, and that it is not more difficult to lay hold of great ideas +than of little ones. It is short-sighted people, not children, who +cannot see far before them. Who made the heavens and the earth? God, +your catechism tells you. The same God made both; did he not? We do +not acknowledge two. And if it be the self-same God who made everything, +the hand of the universal Maker will be found everywhere; and from the +highest to the lowest portion of His work the same mind will manifest +itself under a thousand different forms. Not only, either, is each man +separately, one by one, the work of God. The whole human race, taken +in the mass, is also His creation; and the laws by which human +society--that great body of the human race--seeks to regulate itself +for the preservation of its existence, are undoubtedly the same as +those which overruled the organization of our individual bodies. It +is not very astonishing, then, if we find, in the life of human society +around us, details corresponding with each detail of the life of the +human body, or, at any rate, closely resembling them. What would really +be astonishing, would be that mankind as a whole should be differently +constituted from man as an individual, and that human society should +have other appointed conditions of well-being than those of each of +its members. + +So, while I am on the subject, I should like to advise those who wishto +apply themselves to what is called _politics_--that is to say, social +life--to begin their studies of the body social, by studying the body +human, first. They will learn more from it than from the newspapers! + +But you have nothing to do with all this. For the present, take notice +of one thing only; viz., that the hand of the same God has passed over +everything, and that there is neither much presumption nor much merit +in tracing points of comparison between the different parts of His +work. These comparisons are not a mere play of the mind; they really +exist ready made in the very foundations of things. + +Now let us come down a little from these heights and return to our +friends the lungs. I have not spoken about them for some time, and I +have not yet told you how they are constructed. + +I wish I could show you some, but the cook will do so, if you would +like to see them. The _lights_ with which she feeds the cat and +the dog are the lungs of some animal. + +Take up a piece in your hand, and you will find you have got hold of +something _light_ (cooks have not given it its name without a reason), +which is also soft, sinks under your finger if you press it, and rises +again afterwards like a sponge. In fact, the lung, like the sponge, is +composed of an infinity of minute cells, whose elastic sides can be +contracted or expanded at will. They are like so many little chambers, +into every one of which blood and air keep running hastily, each on its +own side, to bid good day to each other, touch hands, and then hurry out +as briskly as they came in. Whether the bit of lights the cat is eating, +comes from an ox, a pig, or a sheep, you may look at it with perfect +confidence; your own lung is precisely like it. You would see nothing +different, could you look into your own chest. + +So much for the _substance_ of the lungs. As to SHAPE, imagine +two large, elongated packets, flat inside, descending right and left, +inside the breast, and bearing the heart, suspended between the two, +in the middle. The extremity of each packet descends below the heart, +and it is in the interval which separates them that the arch of the +diaphragm performs its up and down movement. + +I have already said that air reaches the lungs through the _larynx_. The +_larynx_ (of which we shall speak further when I have explained another +curious thing very valuable to little girls--the voice), the _larynx_ is +a tube composed of five pieces of _cartilage_ (you know now what +_cartilage_ or _gristle_ is), the firm resisting texture of which keeps +it always open. After these five pieces of _cartilage_, come others, and +the tube is continued; but it then takes the name of the _trachea_; the +_larynx_ and _trachea_ constituting the _windpipe_. At its entrance into +the chest, the _trachea_ divides into two branches, which are called +_bronchial tubes_, and which run, one into the right lung, the other +into the left. You sometimes hear people talking about _bronchitis_. It +is an inflammation of these _bronchial tubes_, which are within an inch +or two of the lungs. It is necessary, therefore, to be very careful in +such circumstances, and do exactly what the doctor prescribes, because-- +one step further, and the inflammation extends from the bronchial tubes +into the lungs themselves, with which it is not safe to play tricks. + +Having reached the lungs, the _bronchial tubes_ subdivide into +branches, which ramify again in their turn like the boughs of a tree, +and the whole ramification terminates in imperceptible little tubes, +each of which comes out in one of those little chambers I was talking +about just now. And this is the way in which air gets there at all. + +The venous blood which leaves the heart, arrives on its side by one +large canal, which passes out from the right ventricle, and which is +called the _pulmonary artery_. And, to tell you the truth, while there +is no learned man present to be angry with us, it is a very ill-chosen +name, because it is _venous_ blood which flows in this so-called +_artery_. But the doctors have decided that all the vessels which run +from the heart should be called _arteries_, and all those which go back +to it _veins_, whatever may be the nature of the blood which they +contain. We cannot help it, because they manage all these matters in +their own way; but in that case it was scarcely worth their while to +talk about _arterial_ and _venous_ blood. It would have been better to +have said simply, red blood and black blood. + +Be this as it may, _venous blood_ arrives from the right _ventricle_ +through the _pulmonary artery_. This divides itself, like the _bronchial +tubes_, into thousands of little pipes, whose extremities come creeping +along the partitions of the little chambers in question. + +And here, then, takes place, between the air and the blood, that +mysterious intercourse for the account of which I have kept you waiting +so long; and at the end of which the black blood becomes red, or, in +other words, from venous becomes arterial. I have called it +"intercourse," and this is really the proper phrase; for this +transformation of the blood is accomplished by means of an exchange. +The air gives something to the blood, and the blood gives something +to the air--each giving, in exchange, like two people over a bargain +in the marketplace. + +With your permission, my dear child, we will stop here to-day. We have +now got to the charcoal market, and it is a little black. + + + +LETTER XX. + +CARBON AND OXYGEN. + +Here, then, my dear child, we have arrived at the explanation of that +great mystery, WHY _we breathe._ Keep on the alert, for we are now +entering into a region where everything will be new to you. + +Here we are at the charcoal market, I said to you just now, and no +doubt you concluded that I was beginning another comparison. + +But no such thing; there is no question of comparison or simile here; +I state the fact itself, pure and simple as it stands: it is a +_market,_ for commercial intercourse and exchange are carried on +there, as I told you before, and it is a _charcoal_ market, +because _charcoal_ is, positively, the essential and chief article of +commerce. + +You are astonished, I dare say, and are ready to ask me whether I can +possibly mean real charcoal, charcoal such as the cook puts into the +furnace. Surely, say you, we have nothing like _that_ in our bodies? +Surely we don't eat _that_? + +But I answer yes; real, true charcoal, and you do not dislike it; you +eat of it even daily; nay, you do not swallow a single mouthful of +food which does not contain its proportion of charcoal. + +You laugh; but wait a little and listen. + +When you are toasting a slice of bread for breakfast, and hold it too +near the fire, what happens to it? + +It turns quite black, does it not? + +When mutton-chops are left too long unturned on the gridiron, what +happens to them? + +They turn quite black also. + +When your brother forgets the apples which he has set to roast, what +happens to them? + +They turn quite black, as you have seen more than once. + +It is always black, then, that these things turn, is it not? and a +fine rich _charcoaly_ black, as you may see if you please to +observe charcoal closely, for just such is the color of little burnt +cakes, over-roasted chestnuts, and potatoes in their skins, which have +been dropped into the fire. + +But there is a common term by which we can express more accurately the +misfortune which has befallen all these various things--slices of +bread, mutton-chops, apples, cakes, chestnuts, potatoes, and what-not, +when "burnt," "over-toasted," "over-roasted," or "over-baked." We may +call them _carbonized_, or more simply _charred_ or _charcoaled_; though +the word _charred_ is generally used only for burnt _wood_. But _carbon_ +being the principal ingredient of _charcoal_, and _charcoal_ being one +of the purer forms in which we get at _carbon_, they are almost +synonymous terms, and you may call your burnt food _carbonized_, or +_charred_, or _charcoaled_, whichever you prefer. + +The next question is, how did charcoal or carbon get into the food so +as to justify our talking of its being _carbonized_ or _charred_? Even +when we use charcoal stoves for cooking, the charcoal does not jump out +and get into the mutton-chops, etc., you may be sure. Then it is clear +it must have been in them before they were brought to the fire to be +cooked; and such is indeed the case, only its black face escaped notice +because it was in such gay-looking company, and kept itself hid behind +the others like a needle lost in a match-box. Set fire to the matches, +and you will soon have nothing left but the needle, which will then +strike your eye at once. And so with our burnt food; the fire has +carried off all the other ingredients, and the charcoal is left behind +alone, exposed to everybody's view, as if on purpose to teach them that +it was always there; in the apples, i.e., the potatoes, mutton-chops, +etc., which seemed so tempting when the black rogue was hid, but from +which now, when he is there by himself, they turn away in disgust. + +Charcoal is, in fact, a much more generally distributed substance than +you have been used to suppose, dear child. That which comes from burnt +wood is most easily observed, because there is a much larger proportion +of charcoal in wood than anywhere else; but there is not a morsel, +however small, of any animal or vegetable whatsoever, which does not +contain charcoal. In the sugar which you crunch, in the wine which you +drink, there is charcoal. I could even find some in the water you wash +in if I were to try hard. There is charcoal in the goose-quill which +I hold in my hand at this moment, and in the paper on which I am +writing, and in the handkerchief on my knee. If I hold them all three +in the light of my wax taper, I shall soon see them turn black and +betray the presence of our friend. It exists in the wax taper itself, +as also in the candle, as also in the oil lamp. If I were to hold a +piece of flat glass above their flame, I should collect enough of it +to blacken the tip of anybody's nose who presumed to doubt the fact. +There is a portion of it in the air; a portion of it in the earth. +Where is it not? In short, all the stones of all the buildings in the +world are filled with it from top to bottom. _Charcoal,_ under his more +scientific and important name of _carbon,_ may be called one of the +great lords of the world. His domain is so extensive that one might go +round the world without getting out of it; he is even worse than the +Marquis of Carabas. + +After this you will never, I hope, want to persuade me you do not +eatcharcoal; for, indeed, you would be puzzled to escape doing so. Of +all the things you see on the dinner-table there is but one in which you +will not find it--viz., the salt-cellar; and even while saying this, +I mean only, in the _salt_ itself, for as to the salt-cellar, +clear and transparent as its glass may be, there is charcoal in it! + +Our bodies, therefore, are full of charcoal. Everything that we eat +supplies them with enormous quantities of it, which take up their +quarters in every corner of our organs. It is one of the principal +materials of the vast collection of structures of which I spoke to you +in the early part of these letters, and of which the blood, the steward +of the body, is the universal master-builder. If you remember, I told +you then that these structures fell to pieces of themselves, in +proportion as the workmen went on building, and that the blood, which +brings fresh materials on its arrival from the lungs and heart, carries +away the refuse ones on its return. And, of all these refuse materials, +old charcoal is one of those which takes up the most room, as fresh +charcoal took up a great deal of room in the new materials. The blood, +as he goes back again, has his pockets quite crammed with it, and if +he did not try hard to get rid of it as fast as possible, he would be +disabled from being of any further use. + +Now it is in the lungs that he clears himself of it. He gives it up +to the air, which has need of it for a very interesting operation, of +which I shall tell you more by and bye; and in return the air gives +him something which is quite indispensable to him, for without it he +would not dare to return to the organs, as his authority would no +longer be recognised. + +In the same way, the charcoal-seller goes to market with his charcoal +and receives silver in exchange. + +If he were to go home without money his wife would receive him with +abuse. + +But what is the indispensable thing which the blood obtains in his +marketing? + +Remember its name well: it is OXYGEN. + +And we must speak of it with respect, for we are talking here of a +very great and powerful personage, very superior even to CARBON. If +CARBON be one of the great lords of the world, OXYGEN is its king. + +There is a certain substance, my dear child, of which many people, +especially little girls, do not even know the name, but which yet +constitutes of itself alone a good half of everything we are acquainted +with in the world. And this substance is the very thing I have just +named to you. It is OXYGEN. + +Ascend into the air as high as you can go, viz., to forty miles or so +from the ground, as we said before; _oxygen_ forms the fifth part +of that vast aerial ocean which surrounds the globe on every side. +There it is free--is _itself_--if I may use the expression; it +is in the condition of _gas_; that is to say, it eludes our sight, +though there is no difficulty in ascertaining its presence, when one +knows how to set about it. + +Go down into the depths of the sea. People think they have good reasons +for believing this to be two and a half miles deep on an average, which +would give a pretty little sum total of tons for its whole weight, as +you will be convinced, if you take the trouble of observing the space +it covers on a map of the world;--to say nothing of lakes, rivers, +streams, the water in the clouds, the water scattered throughout the +interior or on the surface of continents, including that with which +you wash your face every morning. + +Oxygen enters in the proportion of eight-ninths into the composition +of this incalculable mass. _Eight-ninths_, you understand, which +is very near being the whole nine; in every nine pounds of water there +are eight pounds of oxygen, the remainder being left for another +substance, of which we shall have occasion to speak presently, and +which is called _hydrogen_. + +The earth on which you tread is full of oxygen. So far as we have +penetrated hitherto into the interior of the globe, we have found king +Oxygen everywhere: hidden under a thousand forms, connected with a +heap of substances, not one of which could exist without him; imprisoned +in a thousand combinations, and always ready to resume his natural +condition if his prison-house be destroyed. The whole surface of the +earth, plains, hills, mountains, towns, deserts, cultivated fields, +everything you would look down upon, if on a clear day you could be +carried high enough in a balloon to take in the whole earth at a +glance:--all that may be considered as an immense reservoir of oxygen, +out of which we should see it escaping in gigantic waves, if some +superhuman chemist were to take it into his head to put our poor little +globe into a retort of the same kind as chemists use among us. To give +you an example; the stones of our fine buildings, in which we have +already discovered the presence of _carbon_, are almost half made +up of _oxygen_. In a stone which weighs 100 lbs. there are 48 +lbs. of oxygen, and the first chemist who passes by could make them +come out of it if he chose, if he were to use a little trouble and +skill. + +I enumerated to you last time many of the substances in which _carbon_ +is to be found; but as regards _oxygen_ we must give up all attempt at +making a list; it would comprehend the whole dictionary. Touch whatever +lies under your hand--in your room--in the house--wherever you may go--I +will almost defy you to put your finger upon anything--metals +excepted--which is not crammed with oxygen. Your very body, to conclude +with, would become so small a thing, were the oxygen it contains +extracted from it, that you would be perfectly amazed. + +So when I told you oxygen was king of the world, I did not say too +much, did I? Between ourselves too, it is a great misfortune that +people live on so complacently in total ignorance of this all-important +material, which is connected with everything, which insinuates itself +everywhere, which we make use of every instant of our lives, which may +almost be said to be in some sort our very selves, since it constitutes +three-fourths of our body, but whose name nevertheless would, I am +certain, make many pretty little mouths pout, if one were to utter it +in a drawing-room. + +This is really the case. Many young ladies who are proud to know who +Caractacus was, would be ashamed to know anything about oxygen. There +is a foolish notion that women have no business with such subjects, +probably because children are supposed not to breathe and mothers are +not required to watch over them? + +This reminds me that we are on the road to explain _respiration,_ +which I had almost forgotten in lifting up this corner of the veil +behind which Nature hides her most valuable secrets from the idle and +ignorant. + +It is _oxygen_ then, which the blood carries off triumphantly from his +interview with the air in the cells of the lungs; and, by the way, it +is, thanks to this oxygen that it returns from the lungs to the heart, +and so from the heart to the organs, with that beautiful rosy tint which +distinguishes _arterial_ from _venous_ blood. + +Now the blood gives out this oxygen on its road every time it performs +the journey, and the perpetual course it performs from the lungs to +the organs, and from the organs to the lungs, has for its chief object +the perpetual renovation of this previous provision, which is as +perpetually consumed. + +Do you ask of what use it is? Does the blood leave it at random in our +organs, and is it one of the materials with which our steward is +constantly providing the little workmen of the body for their various +constructions? + +No, my dear child. The proverb _"One cannot live upon air,"_ is +a very true one, although it is equally true that we cannot live without +air. Air does not nourish our organs; on the contrary, it consumes +them, and what we eat, serves to supply in precisely the same proportion +its insatiable appetite. When we leave off eating, from whatever cause, +the air does not leave off too. He goes on always just the same, and +that is the reason why people who are starved to death are so thin. +(The air has consumed the vital parts.) + +You did not expect this; but now prepare yourself to go on from one +surprise to another. To begin with, I shall have to stop here and +explain to you before we go any further--can you guess what? Nay, I +am sure you cannot; FIRE. + +There is not much connection, you will say, between _fire_ and +_breathing_. + +But there you are mistaken. It is precisely the same thing, as I will +prove to you next time. + + + +LETTER XXI. + +COMBUSTION. + +Have you never, my dear child, whilst warming your little feet on the +hearth in winter-time, asked yourself, _What is fire?_ that great +benefactor of man; fire, without which part of the world would be +uninhabitable by us during at least a third of the year; fire, without +which we could not bake a morsel of bread, and would have to eat our +meat raw; fire, which lights up the night for us, and without which +we should have to go to bed when the hens go to roost; fire, which +subdues metals, and without which we should have neither iron, nor +copper, nor silver, nor anything that is manufactured from those +materials; fire, without which, in short, human industry could not +rise to much higher results than that of the monkey and of the beaver? + +We are all of us, it is true, so much accustomed to fire that we do +not pay much attention to it, and have a sort of persuasion that lucifer +matches have existed from all eternity. But the first men, who were +nearer neighbors to that great discovery whence all others have +originated--the first men treated fire with more respect than we do. +It was to them one of the mighty things of the world. The ancient +Persians made a god of it, and told how Zoroaster, their prophet, went +to seek it in heaven, passing thither from the top of the Himalayas, +the highest chain of mountains in the known world. + +The old Greeks pretended that Prometheus stole it from the gods, to +make a present of it to man, which came to nearly the same thing as +the Persian account. The Romans had their _sacred fire_, which +the celebrated Vestals were bound to keep lighted, on pain of death +to whoever should let it go out. At the present day we do not stand +upon such ceremonies, but warm our feet at it quite familiarly, without +wishing for anything further. But you would see a terrible revolution +in the world if some Prometheus reversed were, some fine morning, to +steal it from us, and carry it back to its ancient owners. Every branch +of human industry would suddenly stop, as if by enchantment, and in +the course of a very few years the poor little framework of human +society, of which we are now so proud, would totally change its aspect, +and the whole world would be turned topsy-turvy. + +But do not be alarmed; there is no danger of the sort. Fire is not a +present once made to man, but liable to be taken away from him at will. +It is a law of nature which existed before the human race came into +being, and which will doubtless continue to exist when the human race +shall have disappeared. The existence of fire is connected in the most +intimate way with that of that great king of the world of whom we spoke +last time--Oxygen. Fire is the wedding-feast of Oxygen with other +substances! + +When kings are married, what rejoicings there are! what a commotion! +what illuminations! It is only right and proper, then, that the king +of the world should have rejoicings and illuminations at his weddings +also. And they have never been wanting. The rejoicings are the warmth +which rejoices us; the illuminations, the flame which gives us light. +But man, in his dealings with nature, is an imperious subject, such +as few earthly kings are troubled with--happily for them! Whenever he +wants warmth and light he forces the king of the world to get married, +and then takes advantage of the feast; nothing worse than that. + +"How so?" you exclaim. "If I want to make a fire with stones or iron, +I should never succeed. Is this because oxygen never unites himself +with those substances, nor with heaps of others which are equally +useless in lighting a fire? Yet you told me that oxygen was to be met +with almost everywhere." + +It is a fair question, my dear child; but my answer is, that what you +said last is precisely the reason why all substances are not fit for +making fire of. When oxygen is already there, as he is in stones, for +instance, the marriage is over--the feast cannot begin again. Kings +are like other people in this respect; their weddings are only +celebrated once. If you had happened to be present at the moment when +oxygen was united to the materials of which stones are composed, you +would have seen a feast of which I should like to have heard some news. +I was not there myself either; but learned men in these latter days +have succeeded in breaking the bonds which united oxygen with the +primitive substances in certain fragments of stone, and with these +substances thus freed, and consequently able to remarry, they have +been enabled to give us, in miniature, the spectacle of the festivities +of a fresh wedding. And I can assure you it is enough to make one +shudder, to think of the time when such a marriage must have taken +place on a large scale. + +With regard to _iron_ the case is quite different. + +You have without doubt heard tell of Louis XIV. (of France), that proud +king who was called _le Grand_, and who is said to have heard +himself compared to the sun, without smiling. It seems that he one day +took it into his head to marry, it is difficult to say why, with Madame +de Maintenon, the old wife of a poor paralytic poet named Scarron, +who, as such, however, was only known by some few farces. Do you suppose +that the palace of Versailles was illuminated in honor of this marriage? +Not a bit of it. It was a disgraceful marriage, which they were bound +to keep secret. The ceremony was conducted mysteriously and without +lighting a single candle more than ordinary. + +I do not pretend to say that oxygen has any of these weaknesses, nor +that he is any more partial to marrying with one body more than with +another. In the good God's great world, outside of the family of man, +they know nothing of our foolish pride, of our little weaknesses. It +is nevertheless a fact that this dear monarch has his preferences, and +that all his marriages are not made in this fashion. + +Leave those pretty little scissors of yours, with which you would try +in vain to make a fire, outside your window for two or three days, and +then observe the dreadful, scaly, red stain which you are sure to find +on them afterwards, and which is called _rust._ Have you any idea +whence it proceeds? I will tell you. It comes from the oxygen, which +has been making one of those cheerless secret marriages with the iron +of your scissors. So there have been no pretty sights nor sounds, no +lights nor cheerful noises to entertain anybody, and though people may +have wished for them ever so much, they have had to do without them. + +I will tell you the true reason of these marriages _incognito._ +It is because oxygen is but feebly attracted by iron, who does not +stand so high in his good graces as many other bodies, and so (to +continue the joke) he unites slowly and languidly with him, as we may +say. + +Now tell me, when you set fire to a bit of paper, how long does it +take to burn? + +Half a minute, at the utmost, you answer. + +Very good. And how long does it take to produce that rust-stain, even +though it is probably not a hundredth part the size of the paper? + +Two or three days, is your reply, for so I told you my self. + +Here is a strange difference indeed; but from it you may discover why +you have not seen any signs of rejoicing or illuminations at the iron +wedding. These are always in proportion to the quantity of oxygen which +is being married at once--and this was--oh, such a slow affair! When +the quantity is very small indeed, the festal illuminations are very +small indeed too, and in fact escape observation altogether. In the +same way that you would not be conscious of little bits of thread laid +delicately one after another on your back, whereas you would plainly +feel a large sheet, were it to fall on your shoulders. Yet what is the +large sheet but a great quantity of little bits of thread? Only in +that case they would all come upon you at once, like the marriage +illuminations of burning paper. + +Wait a little longer and we shall finish. + +What is there, then, in the paper which pleases the oxygen so much +that he unites himself to it so readily, and in such large quantities? + +What is there? Two substances of high degree, who have actually risen +to the dignity of a royal alliance, by the important part they play +in the world; one of these, charcoal or _carbon_, we know quite +well already; the other I have only mentioned to you in connection +with water, HYDROGEN. Thanks to gas companies, everybody in these days +knows _hydrogen,_ at least by name. But before proceeding, I will +just tell you that it is by far the lightest body that is known. It +is forty and a half times lighter than air, which is not very heavy +itself, although in the mass it has its weight, as we have seen. + +The true province of hydrogen is water, where it keeps house with +oxygen, in proportion of one to eight pounds, as you may remember I +stated in my last letter. But beside this, _hydrogen_ and _carbon_ are +in a manner inseparable friends, whom one invariably meets side by side +in all animal and vegetable substances. In wood, coal, oil, tallow, and +spirits of wine; in everything in short that we call _combustibles,_ +because the name of _combustion_ has been given to this marriage of +oxygen with other bodies, hydrogen and carbon keep themselves shut up +very discreetly and very quietly; like two children playing at hide-and- +seek. You have sometimes played at hide-and-seek yourself, no doubt? +Now, if some naughty child had come behind you with a lighted candle, +what would you have done? You would have had to turn out, whether you +liked it or not, and be caught. Well! this is what happens to our two +friends, when you bring the paper to the fire. The heat forces them out, +and the oxygen, which is always at hand, seizes upon them. In a +twinkling they are married, and a beautiful flame springs up into the +air, which lasts till everything has disappeared. + +Hydrogen and carbon! These, then, are the two great combustibles, the +two parents of fire; and as nature has lavished them upon us in what +we may call inexhaustible quantities; when you hear people lamenting +and saying that wood is disappearing, that coal is diminishing, and +that the human race will end by not knowing how to warm themselves, +do not disturb yourself in the least. + +There is more hydrogen in a bucket of water than is wanted to cook a +large dinner. There is as much and more carbon in our stone quarries +than in our coal pits, and when all the woods in the world are cut +down (which I trust will never be!) do you know what we shall do? Why, +we shall take to burning the mountains. The Jura mountains in +Switzerland, for instance, (to take the most favorable case) are great +masses of carbon, without its ever being visible. Everything depends +upon knowing how to make it come out of its hiding place; but that +will de done when it is wanted: more difficult matters have been +accomplished already. As to oxygen, whether carbon comes to him from +a log of wood or from a building stone; whether the hydrogen comes +from a candle or a glass of water, is a matter of perfect indifference +to him. He only considers persons, not their origin, and marries as +willingly in one case as in the other. + +So we have returned to the subject of _respiration_, on which I +always seem to be turning my back; but now the question is, what brings +us to it again? And this is the explanation. + +When the oxygen picked up in the lungs by the blood has traveled with +it to the organs, he finds there two well-known friends--hydrogen and +carbon. + +You smile, and exclaim at once, "Then he marries them, does he?" + +Yes, my dear child; and it is only for that purpose he enters our +bodies at all. And this is why I could not make you understand the +nature of respiration until I had explained that of fire to you. As +I have told you before, it is the same thing. Invite air into your +body by the bellows of your chest, or drive it into the fire by the +kitchen bellows--it is always king Oxygen whom you are sending to his +wedding. + + + +LETTER XXII. + +ANIMAL HEAT. + +Now, then, we have got hold of the secret of respiration; the _oxygen_ +within us unites itself to the _hydrogen_ and _carbon._ + +And for what purpose, do you suppose? + +Unquestionably it must be to make a fire, since they never come together +without doing so. + +But what do people make fires for? I ask next. Well! surely to warm +themselves, do they not? + +And this is the history of your body being warm exactly like a +dining-room stove, where the oxygen in the air forms an alliance with +the hydrogen and carbon of the wood. Nature warms little girls inside, +on precisely the same plan by which men warm their houses in winter. + +Imagine, then, a little stove, furnished with little arms for helping +itself out of the wood-basket as it is wanted, and with little legs +to run and refill it when it is empty; the fire must be always burning +there, and the stove must be always warm. + +Just such a little stove is your body; your mouth being the little +door, by which there constantly enter--not wood, that would hardly be +pleasant--but--hydrogen and carbon under the forms of bread, mutton +broth, cakes, sweetmeats, and all the good things people have learnt +to make with sugar, fat, and flour. There is hydrogen and carbon in +everything we eat, as I have already told you; but sugar, fat, flour, +and _wine_ are the substances which contain them in the greatest +quantities, and consequently they are our best _combustibles._ + +You are surprised, perhaps, at _wine_ being a combustible; wine, +which you think would put out rather than make a fire. + +And it would. But that is only because in it, what is good for burning +is mixed with a great deal of water, which prevents our being able to +set it on fire. But if part of this water is withdrawn, you have +_brandy,_ which lights easily enough; and if part of the remaining +water is withdrawn from the brandy, you have _spirits of wine_, which +takes fire more easily still. If you have ever seen a _spirit-of-wine_ +lamp, you must know something about this. Judge from that what a fire +spirits of wine must make in the body, even when it has a good deal of +water with it; for it is right to tell you that your little stove is +very superior to the one in the dining-room, and that it hunts out for +consumption the smallest portions of combustible matter, in places where +the other would be a good deal puzzled to find them. + +This is not all, however. I have much greater wonders to tell you yet. + +What should you say to a stove, which, summer or winter, night or day, +in rain or sunshine, amid the ice of the pole, or under the sun of the +equator, was able to keep itself constantly in the same condition; +neither hotter nor colder one minute than another, whether you gave +it much or little fuel, at a given moment, and sometimes when you gave +it nothing for whole days together? It would be worthy of a fairy tale, +would it not? Yet the human body is a stove of this description. + +But this requires a little explanation. + +It is rather bold in me, you may think, to assert so freely, that all +the year round, from one end of the earth to the other, the human body +is never colder nor hotter than mine is, for instance, at this present +moment. "Hot" and "cold" is soon said, you argue: but the exact +varieties of _more_ or _less_ are not so easy to measure, and especially +not easy to remember, with reference to so many bodies, scattered over +the face of the whole earth. What may be warmth for one in one case, may +not be equal warmth for another; and even supposing that the same +individual learned man could go and inspect every part of the globe in +succession, how could he possibly recall, while touching the body of a +negro in Senegal, in July, the exact amount of animal heat he had found +in a Greenland Esquimaux in January? + +Be content. I should not have settled the question so cavalierly, if +people had not discovered an infallible method of estimating accurately, +and always in the same manner, the degree of warmth, in other words, +the _temperature_ of the body. + +Let us first see, then, what this method is, though it will oblige us +to digress a little; but you are accustomed to that now, surely; and +besides, if I were to go straight ahead, you would not be able to +follow me. + +Do you ever recollect being very cold? Let mammas look after their +little girls as much as they please, to prevent it, it is sure to +happen to every one some day or other. Now does it not seem at those +times as if the whole body were contracting itself--and when people +are shivering with cold, have they not a shrunk, shrivelled look? When +the weather is very hot, on the contrary, our bodies feel as if they +were swelling and stretching, and one seems to take up more room than +before. This is the case with all bodies. Heat swells, or, as learned +people call it, expands, them: cold shrinks or contracts them. +Furthermore, _mercury_ is one of the things most susceptible of this +action of heat and cold, and we have had recourse to it accordingly, in +the construction of the _thermometer_, [Footnote: _Thermometer_ comes +from two Greek words: _thermos_, heat; and _metron_, measure. The +degrees in the Thermometer about to be described are marked on the +_Centigrade_ principle. [Not the one (Fahrenheit) in general use in the +United States.]] a very useful instrument, which you will hear spoken of +all your life. + +The _thermometer_, or _heat-measure_, consists of a little hollow ball +filled with mercury, out of which rises a small tube of very thin glass, +in which the mercury can move up and down. When the thermometer is +exposed to heat, the heat causes the mercury to expand, so it goes up +the tube; when the thermometer is exposed to cold, the mercury contracts +and sinks again. + +Now suppose you were to melt some ice in the palm of one hand, and try +to dip a finger-tip of the other in a saucepan of boiling water; you +would find a great difference of temperature between the two, would +you not? Which difference of temperature people have succeeded in +measuring with the thermometer, as accurately as your mamma measures +a piece of cloth with her yard measure. + +This is how it is done: + +You surround the ball of mercury with pounded ice, and while it is +melting make a mark at that point in the tube where the mercury has +stopped in its descent. Then plunge the thermometer into boiling water. +Whereupon the mercury goes up, up, up, till at last it reaches a point +beyond which it will not pass. Here a second mark is made, and the +space between the two marks is divided into a hundred perfectly equal +parts, indicated by so many small lines, which are called _degrees_. But +this word _degrees_ has a double meaning in some languages. It means +_steps_ as well as the degrees of measurement we are talking about; +steps being, as you know, the perfectly equal parts into which a +staircase is divided. Fancy the mercury-tube a staircase, then, rising +from the cellar where the melting ice is, up to the garret where the +boiling water is, and let it consist of 100 steps. The mercury goes up +and down this staircase, according as the temperature it encounters +approaches that of the boiling water or of the melting ice; and if you +wish to know exactly how far it is from the cellar or from the garret, +you have only to count the _steps_. Hence arise those expressions which +you so often hear--high temperature and low temperature. These mean, +temperature according to which the mercury goes up or down this +staircase. + +On the actual floor of the cellar where the ice melts, there are yet +no degrees (a floor is not a _step_, you know), so there you find the +word _zero_, which means a cipher or nought. Then you begin to count 1, +2, 3, 4 degrees, marked by lines up to 100, where you reach the garret, +_i.e._ the boiling-water height. + +Of course, if the thermometer be exposed to an amount of cold greater +than that of melting ice, the mercury will sink below the cellar. +Accordingly the staircase is carried below it, with steps (so to speak) +of precisely the same size as those above, and you count as before, +1, 2, 3, &c., as it descends; adding however, to distinguish these +degrees from the others, "_below zero_." You may go on in that +way as far as 40; but there you must stop. At that point the mercury +freezes. He sits down there on his last step, and will not go any +further! + +In the same way if the thermometer is exposed to a heat greater than +that of boiling water, the mercury will rise higher than the garret. +So the staircase is made to go up higher, and always with steps of the +same size, counting from 101 upwards, as far as 350 if you choose; but +no further, observe! If the temperature were raised beyond that, the +mercury would begin to boil, and then, indeed, good-bye to steps and +measured degrees! The gentleman would dance so fast that there would +be no possibility of seeing anything, to say nothing of his flying +away! + +Now nothing is easier than to use the thermometer. You place it in the +situation where you want to measure the heat, and the mercury goes up +or down of itself until it reaches the degree which corresponds with +the temperature of the place. It is much more convenient than your +mamma's yard measure, which has to be moved about over the stuff, and +which is very apt to slip if you do not hold it carefully. Dressmakers +would be delighted to have a measure which only wanted laying upon the +material, and which would unroll itself and stop short just at the +proper point. And this kind of office the thermometer really performs. + +We will suppose to-day to be the 30th of November. I have just carried +the thermometer out of doors; the mercury has fixed itself at the +second degree _below zero_. This tells me that it is freezing +cold. My fingers have told me so already; but exactly to what extent +they could not say. Just now in the room, the mercury was at the 15th +degree _above_ zero, thanks to the stove in which we have a good +fire. In summer-time it rises to 25, 26, or 28 degrees. I once saw it +climb as high as 33 degrees: in the shade of course, you understand; +in the sun it would have been quite another affair. Well! there was +a universal outcry against the heat. Grown-up young ladies whom I try +to teach all sorts of things as I do you, pretended that it was +impossible to work. Yet I should find a still greater heat inside my +body, if I could get the thermometer there. Have no fears, however; +I am not going to make a hole in it: luckily there is one already. I +put the ball of mercury into my mouth. And now I can almost tell without +looking. The mercury was on its way up the staircase as soon as I took +the ball in my hand--and now it has reached the 37th step. + +You can try the experiment on yourself, but I forewarn you that it +ought to be rather hotter with you than with me: the mercury will +probably rise a degree higher. I will not promise that in your +grandpapa's mouth it may not sink a degree--but that will be all. In +different mouths it has, between the 38th and 36th degree, room for +the play of a little variation, but it can no more go beyond these +than a tethered cow can get beyond the circle made by her cord as she +turns round the stake. Go round the world with your thermometer, pop +it into everybody's mouth, wiping it if you choose as you proceed, you +will always find the mercury on guard. Its tethering cord is somewhat +elastic, like everything else about us; but if by any accident it +should exceed its limit by even one degree above or below, it would +be quite as extraordinary as meeting a giant of eight feet, or a dwarf +of three--which one does see occasionally, although the standard of +human height varies generally round the centre of five feet. + +Since there is a fire always kept burning within us, there is no +difficulty in comprehending why our bodies always keep warm. Of course, +however, the fire must be kept brighter in winter than in summer, but +people have no need to be told so. Nature provides for the necessity. +She gives us more appetite in cold than in hot weather; not that we +can perceive much difference in ourselves in this respect from winter +to summer; for our bodies stick to their accustomed habits, and call +out pretty loudly for the same daily rations, though without having +the same need of them. In order to estimate fairly the connexion which +exists between the internal need of food--_i.e.,_ of combustible +matter--and the external temperature, we must compare the Hindoo, who +lives on a pinch of rice a day, between the tropic and the equator, +with the Esquimaux, who, to keep up his 37 degrees of heat, beyond the +polar circle, in a country where European travellers have seen mercury +freeze, sometimes swallows from ten to fifteen pints of whale-oil at +a sitting! Just fancy _whale-oil!_ which is much nastier than +even cod-liver oil, if you ever tasted that; but, on the other hand, +it is a thorough _combustible_, and the poor people are not so +very particular: come what will, the fire must be kept up, and that +briskly. But without going thus into extremes, a friend of mine once +told me that in Portugal, the land of oranges, it is not uncommon to +see gentlemen and ladies (that is to say, those who can eat and drink +what they please) dine standing, in five minutes, on a bit of bread +and whatever else may be handy. Propose this system to the inhabitants +of our colder and damper climate, whose very young ladies, fair and +delicate-looking as they are, need a helping of good roast-beef for +dinner to keep life in them, and they would only laugh at you. But +those who were well instructed could go on to inform you that the +chilly atmosphere of northern countries creates the necessity for a +more active internal fire than is ever needed under the burning sun +of Portugal, and that a mouthful of bread per day will not, in their +case, suffice to maintain the appointed thirty-seven degrees of heat. + +For the same reason, Spaniards drink water, and are satisfied; whereas +English wine-merchants add brandy to a good many foreign wines, or +they would be quite unacceptable from being deficient in combustible. +It is for the same reason, also, that Russians can swallow, without +wincing, bumpers of brandy which would kill a Provençal outright: and +that the Swedish Government has no end of trouble to keep the country +people from converting into brandy the corn that ought to go to the +miller; whilst the Mohammedan Arabs accept without difficulty that +precept of the Koran which forbids the use of wine and spirituous +liquors. It is easy for the Arabs, who are kept warm by their climate, +to do without brandy. It is less easy for the Swedes, who are surrounded +by cold. + +All this comes as a matter of course, and we do the same thing +ourselves, without being unusually sagacious. In January, when the +thermometer goes down to twelve or fifteen degrees below zero, I put +more fuel into my stove than I am doing to-day, with only two degrees +of cold to bear with. There is nothing surprising in all this. + +The wonderful thing is, that when an Englishman goes to India, he takes +his roast beef and his spirits with him, and in a temperature of more +than thirty degrees of heat, quietly heaps up fuel in his stove, just +as if he was in England, or nearly so. You think he will set fire to +the house, perhaps. But no. Send the thermometer to his mouth for +information, and it will only mark down thirty-seven degrees; neither +more nor less than in the mouth of a rice-eater! The stove has more +sense than its owner. It only burns just what hydrogen and carbon it +wants, and takes no more trouble about the remainder than if it had +not been eaten. + +How about the remainder, then? you ask; if it is not consumed for use, +what becomes of it? Do you remember, my dear child, that long ago, +after explaining the office of the bile and the liver, I put off telling +you what the bile _consisted of_, until we had talked about the lungs +and respiration? Well, the time has come now; so listen. + +The hydrogen and carbon which is not consumed by the oxygen in the +blood, is seized upon by the liver, who employs it in the manufacture +of bile. Therefore the greater the amount of unemployed hydrogen and +carbon there is in the blood, the greater is the quantity of bile +manufactured by the liver--that is all. When once the body has attained +to its proper degree of heat, it is in vain you load it with +combustibles; it will not get any warmer, do what you will. Only you +will have cut out so much extra work for the liver, and the poor wretch +will have to get through it as he can. Accordingly, what happens in +the long run to our great eaters and drinkers, whether in India or +elsewhere? The bile-manufacturer, overwhelmed with work, gets worn +out at last, and kicks; and people come home with that miserable +disease, which is called the "liver-complaint." + +This is one explanation of that wonderful uniformity of temperature +which, happily, human imprudence cannot disturb. But the blood has a +second resource for getting rid of its superfluity of hydrogen and +carbon, and herein especially is displayed the beautiful foresight +with which everything about us has been prearranged. We are told that +wolves, when they get hold of a larger piece of meat than they care +to eat at the moment, carry off what they do not want to some corner +and bury it in the ground, whence they get it again when their hunger +returns. Dogs sometimes do the same; and the blood has a similar +instinct. Listen attentively, for this is very interesting. + +I light a candle and you see a bright flame, which will last as long +as there is any tallow below the wick. Can you tell me what it proceeds +from? + +Nay, do not laugh at the question; it is quite to the purpose, I assure +you. + +We know, do we not, that the substances which burn best are those which +are full of hydrogen and carbon? Tallow, then, is one of those +substances. But tell me further, if you please, what is tallow? + +Tallow is _mutton fat_, allow me to say, if you never heard it before. + +Now comes the question, who provided the sheep's fat with such a +quantity of hydrogen and carbon as to qualify it for making candles? + +The sheep's blood undoubtedly, since blood is the purveyor-general of +living bodies--of the sheep's body as well as of our own. + +But how came it that the sheep's blood had so large a stock of these +materials? + +Undoubtedly, again, because there was more of them in the food the +sheep had eaten than the oxygen was able to consume or the liver to +employ. In short, the sheep has lungs and a bile-manufactory, as we +have; oxygen performs the same office for it as for us. What takes +place in its body in the matter of respiration is an exact counterpart +of what happens in ours, and the history of its fat is simply the +history of our own. + +Now do you think it is for our sakes that the sheep's blood deposits +its fat in little pellet-like morsels throughout the body; do you +suppose the poor creature works in this manner merely to have the honor +of providing us with candles? It is not likely. I was talking about +the wolf just now; but there is no need to look beyond ourselves. In +many poor people's cottages there is somewhere an old earthen pot in +which the savings of each day are carefully put by, penny by penny, +as a last resource in time of need. Should a wicked thief succeed in +murdering the owner and laying hold of the treasure, he will squander +in a few hours of brilliant revelry the precious hoard so slowly got +together as a provision for possible needs. And this is what man does, +when he kills the sheep and takes its fat to make candles of! The poor +animal's blood knew well that bad times might come, that grass might +fail, and the combustible matter conveyed into the body become +insufficient to maintain its thirty-nine or forty degrees of heat +(which is the sheep's measure, who is rather hotter than we are). So +it quietly laid up its surplus stock of combustible so conveniently +brought to hand, and destined to be burnt little by little in the +depths of the organs, should times of scarcity arise. But here steps +in man, the universal thief of Nature, and turns it into a beautiful +flame, regardless of cost, and burns in one evening what his victim +had been economizing for so long. To burn for burning's sake, however, +has always been the fate of tallow, the only difference being in the +way it is done. Like the poor man's clumsy pence, which were put by +to be spent some day or other, only in another manner. It is worth +noting here, that some of the Russian soldiers who were in France in +1815 had a very good idea of restoring candles to their original +destiny. As children of the north, driven to get fire wherever they +could, they ate all the candle-ends they could lay hold of, preferring +to burn the tallow, sheep's fashion, inside rather than out! + +Fat is, then, the savings' bank of the blood; there it deposits its +savings, and there it can always find them again in time of need. +Witness the fat pig described by Liebig, the great German chemist, +which having been swallowed up by a landslip, was found alive at the +end of 160 days. Fat was out of the question there, of course; the +animal weighed ten stone less than before. We will take the illustrious +professor's word on trust, but were a few days subtracted from the +account the case would still be a splendid example of the resource +which blood finds in fat when other nourishment fails; for the pig had +certainly been breathing during the whole 160 days, and as, in all +probability, he moved about much slower than usual, his hydrogen and +carbon fire was never extinguished for a single instant; of that I am +perfectly certain, and you shall soon know why. It was well for the +poor fellow himself that he had put by his provisions in time of plenty. +And who suffered? Why, the pig's master, who had looked forward with +pleasure to the rashers of bacon he should cut by and by from the +stores of combustibles in his larder. For once Master Piggy ate his +own bacon himself! + +You understand now, I hope, by what ingenious management that marvellous +stove, called an animal, never burns too much fuel, whatever be the +quantity it is supplied with, and how, on the other hand, it has always +as much as it wants. + +I have now to explain how important it is that it _should_ always +have enough, and that this is not merely a question of heat and cold, +as with dining-room stoves, but one of life and death! Cheer up! I +have only one more word to say about Respiration, and when you have +heard it you will appreciate still better the lesson of economy which +you have learnt from Nature to-day. + + + +LETTER XXIII. + +ACTION OF THE BLOOD UPON THE ORGANS. + +The first time we talked about the Blood, my dear little pupil, I +introduced him to you as the steward of your body, and what a steward +to be sure! Always awake, as you may remember, always in motion; his +pockets ever full of the materials unceasingly required by the +indefatigable builders of that human edifice in which it has pleased +God to house your dear little self. If you wish really to understand +what follows now, we must carry on the simile a little further. + +A steward not only provides the workmen with materials, but gives them +orders as well, and this is part of the blood's business also. He is +not only commissary-general, but _whipper-in_ of the whole household, +and besides the care of giving out all the stores, has the charge to see +that everything is properly done. The unhappy men who purchase +prosperity at the dreadful cost of maintaining slavery, pretend that +their slaves would do no work worth looking at, were there not always +some one behind them with a whip in his hand. Well, our organs are +slaves, and slaves of the worst sort. They would never do anything +at all, if the blood were not everlastingly whipping them up in his +ceaseless rounds. Let him come to a stand-still for one minute, for +a second even, and everything stops short; then we are at once in the +castle of the Sleeping Beauty in the wood. But perhaps I cannot do +better than to compare our bodily machine to a violin--to hit upon +something less dismal than slaves--a violin with blood for its bow. +As long as the bow runs over the strings the violin makes music and +lives; when the bow stops, it is silent and dies. + +You have never yet had a fainting fit, my dear child; it rarely happens +at your age. But you may possibly have seen somebody faint; or, at any +rate, you have heard it talked about. Do you know what takes place in +such cases? Now and then, in consequence of some violent emotion, but +how or why I cannot tell you, all the blood rushes suddenly back towards +the heart, as during an earthquake a river will sometimes flow back +towards its source, leaving its bed dry. Thereupon the face turns +white, as if to give notice that there is no longer anything red below +the skin. The organs, no longer stimulated by the blood, leave off +work altogether. The brain goes to sleep, the muscles relax, +consciousness ceases, and you behold the poor body, from which the +soul seems to have departed, give way on all sides, and fall to the +ground like a corpse. This is not exactly death, but it is yet an +interruption of life. It would be death if nature did not get the upper +hand again, and send back the deserter to his post. + +I may remark here that it was partly on this account that some of the +ancients thought the soul was seated in the blood; not a bad idea for +people who were determined to pronounce where the soul was, when it +is so easy to say one knows nothing about it. But those who placed it +in the breath, and who have bequeathed to us those beautiful +expressions--_yielding up the last breath--giving up the ghost_--were +not wrong neither. + +In point of fact the blood is not the soul of the body; in other words, +does not keep the body alive, otherwise than by keeping up unceasingly +and everywhere that magic fire of which we were talking last time. + +The French people, in their picturesque language, have found an +expression, full of energy, to express the action exercised by the +master workman, who knows how to make his people work: "_Il vous met +le feu sous le ventre._" [Footnote: Literally, _he puts fire under +their bellies;_ but here signifying that he makes it so hot that +the organs are compelled to continue in motion.] This is, to the letter, +the process employed by the blood to make the organs work. It makes +a fire under the belly. Unhappily their work only lasts as long as the +fire which causes the heat, and which is so necessary to life that it +is almost confounded with it. It is the sacred fire of the Roman +Vestals, which must be fed night and day under pain of death should +it go out. Now, if to feed the sacred fire of life, it be necessary +that the blood should everywhere find hydrogen and carbon +_unattached_, that is to say, free and ready to unite themselves +to oxygen, it is no less necessary that he should bring oxygen with +him everywhere. Else there would be no marriage, and therefore no fire. +Oxygen is, then, the talisman which brings the organs to obedience. +Without oxygen he would be a slave-driver without his whip; his orders +would be despised. If the organs were to be deluged with _venous_ +blood--with that black blood which has lost its oxygen, they would not +stir any more than if they had received so much water. They acknowledge +nothing but _arterial_ blood--red blood--blood rich in oxygen. +That is what they respect, and which has authority over them; the other +is a bankrupt who has lost his credit with his cash; those whom he fed +but lately now laugh in his face. And as our good steward spends all +his oxygen every time he goes his rounds, it would soon be over with +him, and, consequently, with us, too, if he had not some method of +replenishing his purse after each journey. Happily the lungs are the +inexhaustible chest to which he always returns to renew his right of +authority; that is, his power of preserving life. When it comes to the +_last sigh_, the last effort of the diaphragm by which the chest +is closed forever, we must bid adieu to life. In yielding up that, we +have in very truth yielded up the ghost. + +This is no joke, as you see, and it would not do to be caught +unprepared, with an inexorable necessity hanging over one, which never +allows a moment's respite. The blood acts like a reasonable being, +therefore, in laying up his stores of combustible in reserve. Moreover, +whether he has done so or not, the fire must go on all the same; that +is absolutely necessary; and if he has no spare fat to feed it with, +when, from any cause, the stomach leaves off working, he makes use of +anything he can lay his hands upon. + +I know a story on this subject which will amuse you. + +There lived, in the reign of Francis I. of France, an honest countryman, +of Périgord, named Bernard Palissy. At that time everybody could not +afford to have earthenware plates, as they have now. It was a +manufacture of which only the Italians had the secret, and Bernard, +who knew something of the matter, from being a glass-worker, took it +into his head to try and find it out entirely by himself. So, without +asking anybody's advice, he turned potter, built ovens, picked up wood +as he could, manufactured his first pots, whether well or ill, made +a beginning, and waited. He had fifteen or sixteen years of it before +he succeeded; fifteen or sixteen years of ruinous experiments, which +would have discouraged a less sturdy heart than his. But he, after he +had succeeded in picking up some money by his church windows, returned +to his work with unconquerable perseverance, insensible to poverty, +deaf to the ridicule of neighbors, and unmoved by the abuse of his +wife, who was furious, as you may suppose, at being forced to play the +heroine without having the least turn for it. And one fine day there +was a grand uproar in La Chapelle-Biron (that was the name of his +village). "Bernard Palissy has gone mad," said everybody; "he is burning +up his house to bake his pots." And upon my word it was true! Wood +happened to be wanting while a batch was in the oven, and Bernard +having begun by using up the garden palisades, took next the large +tables, and at last the floor of the house! What his wife had to say, +I leave you to judge; as for him he listened to nothing; but, fixing +his eyes on the insatiable furnace, threw in one thing after another, +caring only for the risk to his handiwork. The ceiling would have +followed the floor had not his pots been sufficiently baked without. + +And thus, and thus, does the blood, when combustible matter fails him! +He demolishes the house, and throws it, bit by bit, into the fire. The +fat goes into it naturally enough, as I have already explained to you. +It is the fuel-store of the house. It was put by on purpose, and may +be used up without injury. Then comes the turn of the muscles; more +useful without being indispensable. Those are Bernard Palissy's +palisades one may contrive to do without them. They melt away, so to +speak, after a few days' fast, and you find yourself what people call +"nothing but skin and bone." But then, if this condition is prolonged, +and the exhausted flesh cannot supply the demand, the blood does not +hesitate a moment. He boldly falls upon the most important organs, +without stopping to consider; he, too, is devoted solely to his work, +and that, like the baking of pots, never comes to an end by being +completed; if external help does not arrive in time, the house soon +becomes uninhabitable, and life slips away. The man dies of hunger. + +But in the same way that poor Bernard Palissy was in reality working, +all the time, for his wife and children, whose future well-being he +strove for as the final end of all his efforts, though at the risk of +letting them sleep under the bare heavens; so the blood was laboring +up to the last moment for that very life which he at last turned out +of doors; and the work of destruction which caused its final departure +has had in reality the effect of prolonging its stay. Without it, all +would have been over long before. + + + +LETTER XXIV. + +THE WORK OP THE ORGANS. + +Thus much is settled, then. It is the blood which sets everything in +motion throughout the body. The organs are idlers who would do nothing +but for him; they only work when goaded on, if I may use the expression, +by that fire--always on the point of going out--which he is perpetually +coming back to rekindle, thanks to the oxygen he carries with him from +the lungs. + +This will enable me to explain many things, which, although not new +to you, you have probably never tried to account for before. + +To begin with: do you remember what happened to you the other day, +when you tried to overtake your mischievous brother in running, and +he, taking advantage of his school-boy legs, led you mercilessly through +all the garden walks, without having the grace even to let you catch +him at the end? You were quite out of breath; your heart beat so rapidly +it almost hurt you; and you were so hot that the perspiration poured +in great drops down your face, so that your mamma, quite frightened, +took you up in her arms and carried you to the fire; for the coolness +of evening was coming on, and a little girl drenched with perspiration +is soon chilled. + +Tell me now, what connection was there between your overrunning yourself +in a race and the extraordinary degree of heat which came over you so +soon? Your cheeks were cool and fresh when you began to run; what made +them so red all at once, and especially at a moment when the air was +cool and fresh in the garden? + +You open your eyes in surprise; you had never thought of this. No! +that is just the way with little girls. They run; they get hot; it +seems as natural as warming oneself in the sun, and they never ask why +it is so. + +Yet you could almost tell me the "why" yourself, if you stopped to +think about it, now that you are what your school-boy brother would +say "_up to a thing or two;_" but to save time, I will help you. + +You run as a bird flies, without thinking about it. Nevertheless, if +you could see with a magic glass all that takes place in your body +while those active little feet are carrying it like a feather across +the garden, you would be perfectly amazed. One of these days, when we +have finished our present history, I will tell you that other one, +which is equally worth the trouble. It is enough for the present to +know, that a very complicated piece of work is being carried on there, +in which almost all the muscles of the body take part at the same time, +contracting and relaxing in turn, like so many springs, of which each +either drives forward or holds back a part of the machine. In fact, +while your eyes and thoughts are fixed on the butterfly which is +flitting away from you through the air, there is going on within you +such an unheard-of outlay of efforts as could never be got out of our +idlers if the terrible steward did not lash them severely. + +Now, his lash, as we have said often enough, is that eternal fire, the +materials of which he conveys to all parts of the body. On those special +occasions, therefore, he is obliged to make his fire burn much more +briskly than usual--exactly like railway engine-drivers, who increase +the heat of their fire to get up steam in proportion to the speed they +wish to go. + +From this you will understand that it is no great wonder that your +small frame should get heated from such work as racing and chasing; +and that if you pursue it too long, the perspiration which comes out +all over you is sufficiently explained. + +This is not all, however. The fire, whose strength has to be increased, +naturally requires a larger amount of combustible matter than before, +and forasmuch as there is only a certain fixed quantity in each drop +of blood, whenever the muscles want more than usual, the blood itself +must flow to them in greater abundance. Now if it were a question of +supplying only one part of the body (as it is, you may remember, of +supplying the stomach during the progress of digestion), he might +contrive to accomplish his task there by neglecting it elsewhere, and +overflow one organ at his ease, at the expense of all the rest. But +in this case he is wanted everywhere in the same abundance. It is not +a question of taking one muscle's share for the benefit of another. +From one end of the body to the other, all want to be deluged at once. +And remember that these exigencies do not bring a drop more blood into +the body. How is he to get out of his difficulty then, this overwhelmed +steward of ours? Well! just as your mamma manages, my dear, when there +is more to do than usual in the house;--by running quicker than ever +from the cellar to the garret, and from your room to your papa's! That +is called doubling oneself; and this gallant blood doubles itself to +some purpose. He runs and runs and runs, arrives in hurried streams, +and returns full gallop, passing and repassing through the heart, which +empties and fills itself in sudden jerks. Unluckily, the poor heart +is a delicate sort of person, who does not like having his habits +disarranged, and this forced work soon makes him desperate. The other +day, in his despair, he knocked with all his strength against the walls +of his little chamber, to warn his young mistress that he could bear +no more, and that they were both of them in danger. In fact, you ought +to know that if one was infatuated enough to go on running too long, +one might die of it. When you learn ancient history, you will probably +be told of what happened to the soldier of Marathon, who flew like an +arrow from the field of battle to the gates of Athens, that he might +tell his fellow-citizens a quarter of an hour earlier, that his country +was saved; and he fell dead on his arrival. + +But it is not the heart only which suffers by this mad career of the +blood. During each journey it performs it passes through the lungs, +which in their turn are forced to play with hasty jerks. And this is +well for our good steward; for the lungs, filling with air at each +descent of the diaphragm (if you remember what we have said before), +more air, and consequently more oxygen, comes in, and the blood has +by this means a larger stock on hand, ready to help him out in the +unusual waste which is just then going on in the muscles. I spoke just +now of railway steam-engines. See how self-supporting ours is! The +greater the amount of fire wanted, the faster the blood flows; and the +faster the blood flows, the oftener does the coffer re-fill itself, +whence comes the supply of oxygen requisite for keeping up the fire. +All this goes on at once, by one impulse, and the balance between the +receipts and expenditure settles itself of its own accord. How thankful +many families would be if their money-chest would but fill itself in +the same way--in exact proportion as they spend the cash! There is +only one slight drawback, which is, that the diaphragm gets tired with +the unaccustomed gallop it is thus forced into. It falls into +convulsions, therefore, like its neighbor the heart, and the breathing +is stopped, from having been driven too rapidly. An excellent example +for people who want to spend too much at once; showing that Nature +herself cries out against it, even when the only thing wanted is +atmospheric air. + +Now, run if you dare! And, to tell you the truth, it would be a great +pity if you did _not_ dare; for our good God has made little children +for running. They have nimbler blood than we older grandfathers, more +elastic lungs, and consequently more oxygen to spend at a time. But you +must confess that it is a great pity we should run all our lives as many +people do, without having the slightest idea of these admirable +contrivances, thanks to which we are enabled to do it. We can run all +the same, it is true, without the knowledge, the little child as easily +as the little roebuck, which sets a similar machine in motion. But it is +no use talking about the little roebuck; it cannot learn what God has +done for it, but the little child can, if he will. Furthermore, there is +nothing to be really alarmed about, for those great commotions only +occur when we have committed excess; and it is a very good thing, in a +general way, for the blood to give us a stroke of his lash from time to +time. I told you lately that the fire which sets the organs to work is +life; and it is no misfortune to be a little more alive than usual. +Besides which, this increased activity of the internal fire does not +serve us in running only. Every time that a man makes an effort; every +time he lifts a weight, or handles a tool, the blood rushes forward to +deluge the muscles that are thus called into play; the heart beats more +quickly, and the air streams in greater abundance into the lungs. Look +at a man chopping wood. If the log resists too much, if for a minute or +two the man has to strike blow after blow without stopping, you will +soon see him panting for breath, just as if he had been running a race. +On the other hand, he will have gained something from chopping his log +besides the right of warming himself before it at the fire. Blood does +not carry fire only into the muscles; he supplies them with nourishment +also, does he not? Every drop of blood deposits its little offering as +it goes by, and consequently the greater the number that pass along, the +richer is the harvest for the muscle. Look, accordingly, at the laboring +classes. How much healthier and stronger they are than those who do not +work! I speak, of course, of working with one's limbs generally; for +those poor girls who work from morning to night, sitting on their +chairs, are none the better for it, but, on the contrary, worse. There +are also certain worthy fellows who, like myself at the present moment, +drive a pen over sheets of paper for half a day at a time, whose muscles +never get any bigger for it, that is quite clear. Moreover, one +condition has to be fulfilled, which unhappily is not always done. The +more people labor, the more they ought to eat. To you, who have just +been looking at the drama that is performed in the body every time a +muscle is set in motion, this is obvious enough. There is no fire +without smoke, says the proverb. It would have been much better to +have said,--there is no fire without fuel;--and the fuel for our fire +is, as you know, what we eat. Try if you can get one stove to burn +more brightly than another, if you have put less fuel into it. Yet, +alas! this is what many poor wretches are obliged to do but too often; +and then the blood, instead of feeding their muscles, consumes them, +for the reasons I gave, in telling you the story of Bernard Palissy. +Think of this, oh my dear child, when you are grown up, and never +grudge those who work for you their proper share of food. + +Here I see many other lessons crowding up, out of what you have just +learnt. + +And first Nature herself, taken as you find her, shows you that manual +labor is, for us, a most beneficial condition of existence; that it +brings about a re-doubling, an exaltation of life; and that +consequently, we have no need to look down upon those who gain their +bread, as we word it, by the sweat of their brows. I told you this +before, in speaking of the hand, which is of so much more use to those +people than to you; and I repeat it now for another reason, viz.: +because labor elevates him who undertakes it, and creates a real +physical nobility. Barbarians in old times, who knew nothing noble nor +grand but war, despised labor, and left it to their slaves; so much +so, that the name _servile labor_, _i.e._ the labor of slaves, +has stuck to it in some places. As for war, the lot of the ancient +nobility, I scarcely dare to say much against it, however much I should +like to do so on some accounts. For, after all, so long as there are +ruffians to trample on the weak, one is only too glad to find brave +men ready to risk their lives in keeping such rascals down: so long +as there are wolves, we must needs keep shepherds' dogs. But in spite +of everything, the best that can be said in favor of war is, that it +remains a sad but inevitable necessity, and that to get rid of it, +more is wanting than the wish. What a contrast to labor--that contest +of Man with Nature;--that merciful and fruitful war, where victories +are not estimated like other victories, by the number of the slain, +but which, on the contrary, scatters fresh life around it as it spreads; +fresh life in the laborer himself, by the very act of work, fresh life +around him without, by the fruits that work produces! + +Between the man who dies in slaying others, and the man who keeps +others alive by living longer himself, it seems cruel to make invidious +comparisons; but if it be just to honor the first out of respect for +the cause he has defended, whenever that cause is respectable--it is, +to say the least of it, not less just to do equal honor to the second. + +But let us come down from these philosophic heights, and return to +you, dear child; to you, who have nothing to do with war, its massacres +or its laurels. + +It is true, however, that you have nothing to do either, with chopping +wood, and I am not asking you to undertake any such thing. But in the +life of a woman, from the time of her childhood upwards, a thousand +things arise for the hands to do, and the question is, how often you +are likely to feel ashamed of not sending for the servants to do them? +Avoid this false and fatal idea as much as possible. The work of the +hands dishonors no one; it is honorable. To cast it aside altogether +is to make yourself smaller instead of greater; to deprive yourself +of one of the glories and the joys of life. If a good thing is set +before you at dinner, do you send for the servants to eat it? If an +occasion arises for making the blood circulate more rapidly in your +veins, and of increasing the strength and life with, in you into the +bargain, why make _them_ a present of it? Especially when it +cannot be an agreeable present considering that good servants have +plenty of such opportunities from morning to night every day. + +There was once upon a time a Persian prince staying in Paris, who was +taken to a very fashionable ball, that he might see a specimen of +European civilization. I am not talking about a prince in the "Arabian +Nights;" mine lived, I believe, in the time of Louis Philippe. The +beautiful dancers wheeled round, their eyes brilliant with pleasure, +in the arms of elegant cavaliers; one would have said that the whole +of this airy troop, swaying to and fro in time to the lively flourishes +of the music, was animated by one soul; everything seemed full of joy +in that large and splendidly lit hall, and mothers secretly envied +their daughters as they passed and re-passed before them. Our oriental +alone scanned with a disdainful eye this youthful enjoyment. + +When it was ended,--"How is this?" said he to his conductor; "did you +not tell me that I was to see here the most distinguished families of +Paris?" + +"Certainly," replied the other; "among those young ladies who were +just now dancing before you, there were at least twenty of the grandest +heiresses of France." + +"Young ladies who dance! Come, come! In my country we have dancers, +but they are paid for it. Our wives are never permitted to dance +themselves. That is all very well for the common people!" + +Remember, when needful, the contempt of this Persian prince, my dear +child; and let me beg of you, work for yourself. The dance of labor +is worth quite as much as that of the ball-room, when you give your +heart to it. It is even worth more, very often; and next time I will +tell you why. + + + +LETTER XXV. + +CARBONIC ACID. + +We are going to make acquaintance to-day with a new personage, who +well deserves our attention. It is the child of oxygen and carbon, +[Footnote: This is the name learned men have given to Charcoal.] though +not in the same way that you are the child of your parents. + +To tell you how it is made is more than I am able. It is a _gas_, +or if you like the word better, it is an _air_; for when we say +"gas," we mean "air;" only it is always a different sort of air from +the air of the atmosphere, which learned people are not in the habit +of calling _gas_. I cannot, therefore, show you _carbonic acid_ itself, +for it cannot be seen any more than the air which fills an empty glass. +But I can tell you where there is some, and you even probably know it by +its effects, although you have never heard its name. + +Do you remember, on your aunt's wedding-day, that there was a sparkling +wine called champagne, at the grand breakfast? You smile, so I conclude +somebody gave you a little to taste; and if so, you will remember how +sharp it felt to your tongue. Do you remember, too, how the cork flew +out when they were opening the bottle, and how the noise of the "pop!" +startled more little girls than one? It was _carbonic acid_ which +sent the cork flying in that wild way; the carbonic acid which was +imprisoned in the bottle, in desperately close quarters with the wine, +and which accordingly flew out, like a regular goblin, the moment the +iron wire which held down the cork was removed. What sparkled in the +glass, making that pretty white froth which phizzed so gently, as if +inviting you to drink, was the carbonic acid in the wine, making its +escape in thousands of tiny bubbles. What felt so sharp to your tongue +was the same carbonic acid, in its quality of acidity, for thence it +has its name; the word _acid_ being borrowed from a Latin word +signifying the sharp pungent taste, almost _fine-pointed_ as it +were, peculiar to all substances which we call _acids_. + +It is carbonic acid also which causes the froth in beer and in new +wine when bottled. It is he who makes soda-water sparkle and sting the +tongue, and ginger-beer the same, if you happen to like it; and so far +you have no particular reason for thinking ill of him. But beware. It +is with him as with a good many others who have sparkling spirits, who +make conversation effervesce with gayety, and who are very seductive +in society when you have nothing else to do but to laugh over your +glass, but whose society is fatal to the soul which delivers itself +up to them. This charming carbonic acid is a mortal poison to any one +who allows it to get into his lungs. + +You remember what a violent headache your servant suffered from the +other day after ironing all those clothes you had in the wash? She +owed that headache entirely to this work which she did for you. She +had remained too long standing over the coals over which her flat-irons +were being heated. You know already that when charcoal burns, it is +from the carbon uniting with the oxygen of the air; from this union +proceeds that mischievous child, carbonic acid gas, in torrents, and +the poor girl was ill, because she had breathed more of this than was +good for her health. Observe well, that the room-door was open to let +in the fresh air, and that there was a chimney, to allow the carbonic +acid to escape. It was on this account that she got off with only a +headache. Unhappily, there have sometimes been miserable people who, +weary of life, and knowing this, but not knowing or thinking about the +God who overrules every sorrow for good, have shut themselves up in +a room with a brazier of burning charcoal, after taking the fatal +precaution of stopping up every opening by which air could possibly +get in; and when at last, in such a case, uneasy friends have forced +open the well-closed door, they have found nothing within but a corpse. +Then, too, there are those frightful accidents of which we hear so +often, of workmen groping their way down into long disused wells, who +have died as they reached the bottom; or of sudden deaths in coal-pits. +In general these have been owing to the poor victims encountering the +long pent-up carbonic acid gas, whose poisonous breath blasted and +destroyed them at once. + +You may well ask why I am telling you such horrible stories, and what +I am coming to with my carbonic acid? But you have more to do with it +than you think, dear child. You, and I, and everybody we meet, nay, +and the very animals themselves, since their machines are of the same +sort as ours, are all little manufactories of carbonic acid. The thing +is quite clear. Since there is a charcoal fire lit in every part of +our body, there always arises from the union of the oxygen brought by +the blood with the carbon it meets in our organs, that mischievous +child we have been talking about; and our throat is the chimney by +which he gets away. He would kill us outright were he to stop in the +house. + +This is how it comes about: In proportion as the blood loses its oxygen, +it picks up in exchange the carbonic acid produced by combustion, so +that it is quite loaded with it by the time it returns to the lungs. +There it takes in a fresh supply of oxygen, and discharges at the same +time its overplus of carbonic acid, which is driven out of the body +by the contractions of the chest, pell-mell with the air which has +just been made use of in breathing. You are aware that this air is not +the same at its exit as at its entrance to the body, and that if you +try and breathe it over again it will no longer be of the same use to +you. That is because it has lost part of its oxygen and brings back +to you the carbonic acid which it had just carried off. If you take +it in a third time, it will be still worse for you; and in case you +should continue to persist--the oxygen always diminishing, and the +carbonic acid always increasing in quantity--the air which was at first +the means of your life will at last become the cause of your death. +Try, as an experiment, to shut yourself up in a small trunk, where no +fresh air can get in; or even in a narrow closely-shut closet, and you +will soon tell me strange news. There will be no occasion to light a +charcoal fire for you in there. Enough is kept burning in your own +little stove, and you will poison yourself. + +You see now that the dreadful stories I was telling a short time ago +have something to do with you, and that it is a good thing to be warned +beforehand. And now tell me, when a hundred people--or I ought to say, +a hundred manufactories of carbonic acid--are crowded together for a +whole evening, sometimes for a whole night, in a space just big enough +to allow them to go in and come out; tell me, I say, if that is a sort +of thing which can be beneficial to the health of little girls whose +blood flows so fast, and who require so much oxygen; and whether, on +the contrary, it is not one's duty to keep them away from such scenes? + +There may be amusement there, I know; but the best pleasures are those +for which one does not pay too dearly. I have seen the very wax lights +faint and turn pale all at once, in the very midst of those murderous +assemblies, as if to warn the imprudent guests that there was only +just time to open the windows. + +And this reminds me of a point I had nearly forgotten. Wax-candles arc +like ourselves. In order to burn, they must have oxygen, and, like us, +they are extinguished by carbonic acid. But like us also--and indeed +to a greater extent, because they consume much more charcoal at +once--they manufacture carbonic acid. Hence that very illumination +which affords the company so much pleasure and pride is plainly an +additional cause of danger. Each of those wax-lights which is spread +around with such a prodigal hand, the only fear being that there may +not be enough of them, is a hungry intruder employed in devouring with +all his might the scanty amount of oxygen provided for the consumption +of the guests. + +From each of those cheerful flames--the suns, as it were, of the festive +assembly--shoots out a strong jet of carbonic acid, contributing by +so much to swell out the already formidable streams of poisoned gas, +exhaled to the utmost extent by the dancers. And wait--there is still +something else I was forgetting. You dance. And I told you last time +at what cost you have to dance. You have to make the fire burn much +quicker than usual, that is, to consume a great deal more oxygen at +once, and so you double and treble the activity of the carbonic acid +manufacture: and this just at the moment when it would be so convenient +that it should go on as slowly as possible! After this, you need not +be surprised that people should look fagged and exhausted next morning. +What astonishes me is that they are not obliged to lie in bed +altogether, after treating their poor lungs to such an entertainment. +And even if you have spared your legs, you are not much better off, +as you are sure to find out in time, especially if the thing is repeated +too often. + +When I told you just now that the dance of labor was worth as much as +the dance of the ball-room, was I right or wrong? What do you say +yourself? + +I could repeat the same of theatres--places of entertainment specially +adapted for impoverishing the blood, and ruining the health of the +happy mortals who go there, evening after evening, to purchase at the +door the right of filling their lungs with carbonic acid, not to speak +of other poisons. You must see clearly that such places as those are +not fit for little lungs as dainty as yours; and this may help you to +submit with a good grace when you see people going there without you. +Grown-up people escape moreover, because the human machine possesses +a strange elasticity, which enables it to accommodate itself--one +scarcely knows how--to the sometimes very critical positions in which +its lords and masters place it without a thought. But to do this, it +is well that it should be thoroughly formed and established; for you +run a risk of injuring it for ever, if you misuse it too early in life. +Tell this to your dear schoolboy brother, when he wants to smoke his +cigar like a man. If his lungs could speak, they would call out to him +that it was very hard upon them, at their age, to be so treated, and +that he ought at any rate to wait till they had passed their +examinations! + +But I must not get into a dispute with so important an individual, by +throwing stones into a garden which is not under my care. For you, my +dear child, the moral of this day's lesson--which to my mind is much +more alarming than a hobgoblin tale, since it concerns the realities +of every-day life--is clear; and it is this: + +Seek your amusements as far as possible in the fresh air. In the summer, +when the lamp is lit, bid your mamma a sweet good-night, and go to +bed. In the winter do not wait till there is a great quantity of +carbonic acid in the room where the grown-up people are sitting, before +you retire to your own like a reasonable girl, anxious not to do +mischief to that valuable and indefatigable servant, the poor blood! +Not to mention that if she were to injure him too much, she would have +to bear his grumbling for the rest of her life. We cannot change him +as we change other servants. + + + +LETTER XXVI. + +ALIMENTS OF COMBUSTION. + +We have spent a very long time, my dear child, over the little fire, +which goes on burning secretly in every one of us, quietly devouring +what little girls eat with such a good appetite, quite unsuspicious +of what they are doing it for. However, if I mean to finish the history +of our mouthful of bread, I must push on to its last chapter. + +The _whole_ of what we eat is not burnt, as you may easily suppose; for, +if it were, what would the blood have left to feed the body with, and to +repair in due proportion the continual destruction or waste which goes +on in our organs? Our food, or "_aliments_" as the general collection of +different sorts of food is called, are divided into two very distinct +sets: some, which are destined to be burnt, and which are called +_aliments of combustion_; others, which are destined to nourish the +body, and which are called _aliments of nutrition_. I have to tell you +now about these last, and you will find their history by no means +uninteresting. + +Learned men having detected, beyond the possibility of a doubt, the +existence of these two sorts of aliments, one is tempted to think they +ought to have made it known to the cooks, and that ever since so +important a discovery, the dishes on all well-regulated tables should +have been arranged accordingly; aliments of combustion on one side, +aliments of nutrition on the other. It cannot be enough merely to give +your guests a treat; you ought to provide them with everything necessary +for the proper fulfilment of the claims within; and if you give some +nothing but combustibles, leaving the others no share of fuel, how +will they be able to manage? Nobody thinks about this, however; not +even cooks, to begin with, who, as far as fire is concerned, find they +have had quite enough to do with it in their cooking; and as for the +guests, when they have had their dinner they go away satisfied, as a +matter of course, quite as well provided for as if the mistress of the +house had made her calculations, pen in hand, while writing out the +bill of fare, with a view to combustion and nutrition. Now, how is +that? + +It is because the two sorts of aliments are, for the most part, met +with together in everything we eat, so that we swallow them at once +in one mouthful; and have therefore no need to trouble ourselves further +on the subject. There is our bit of bread, for instance. What is bread +made of? Of flour. Bread, then, must contain all that was previously +in the flour. Very good. Now I will teach you how to discover in flour +the aliment of combustion on the one hand, and the aliment of nutrition +on the other. + +Take a handful of flour, and hold it under a small stream of water; +knead it lightly between your fingers. The water will be quite white +as it leaves it, carrying away with it a fine powder, which you could +easily collect if you were to let the water run into a vase, where the +powder would soon settle to the bottom. That powder is starch--the +same starch as washerwomen use for starching linen, and which our +grandfathers employed in powdering their wigs. You had some put on +your own hair one day when you were dressed up as a court-lady of olden +time. Now, starch is an excellent combustible. People have succeeded, +by means which I will not offer to detail here, in ascertaining almost +exactly what it is made of, and they have found in it three of our old +acquaintances, oxygen, hydrogen, and carbon, combined together in such +proportions that 100 ounces of starch contain as follows: + + Ounces. + Carbon 45 + Hydrogen 6 + Oxygen 49 + --- + 100 +I give you the calculation in round numbers, so as not to burden your +memory with fractions; and I will do the same with the other sums I +shall have to go through to-day, this being, let me tell you, an +arithmetical day. Besides, I could scarcely take upon myself to warrant +the absolute correctness of those very precise fractions people +sometimes go into. Even our learned friends squabble now and then as +to which is right or wrong over the 100th part of a grain, more or +less, in making out their balance, and you and I will not offer to +decide between them. I always think we have accomplished wonders in +getting even _near_ the mark, and with their permission we will +stop there. + +Starch, then, of whose weight carbon constitutes nearly one-half, is +of course a first-rate combustible. Indeed, one may almost consider +it the parent, as it were, of at least half our aliments of combustion, +for if (in consequence of a certain operation, which nature has the +power of performing for herself, in certain circumstances) it loses +a portion of its carbon, so that there remain but 36 ounces of it in +the 100 of starch, our starch is turned into something else; now can +you guess what that something is? Neither more nor less than _sugar_! +Witness the grand manufactories at Colmar, in France, where bags of +starch are converted into casks of syrup by a process of nature alone; +so that the inhabitants of the neighborhood sweeten their coffee at +breakfast with what might have been made into rolls, had it been left +alone. And this is not all. Give back this starch-sugar into the hands +of Nature once more by putting it into certain other conditions, and a +new process begins in it. About a third of its carbon will unite itself, +of its own accord, with the two-thirds of its oxygen, so as to make +carbonic acid, (you are acquainted with that gentleman now) which shall +fly off and away, and there will remain--what do you think?--_Alcohol_, +that other combustible we talked about, and which burns even better than +sugar and starch, since in a hundred ounces it contains as follows:-- + + Ounces. + Carbon 53 + Hydrogen 13 + Oxygen 34 + --- + 100 + +All this astonishes you. What would you say then if I were to tell you +that your pocket-handkerchief is composed of entirely the same materials +as starch, and in the same proportions too, and that if a chemist were +to take a fancy, by way of a joke, to make you a tumbler of sugar and +water, or a small glass of brandy out of it, he could do so if he +chose. Wonders are found, you see, in other places besides fairy tales; +and since I have begun this subject I will go on to the end. Know then +that from the log on the fire, to the back of your chair, everything +made of wood, is in pretty nearly the same predicament as your +pocket-handkerchief; and if people are not in the habit of making casks +of syrup and kegs of brandy out of the trees they cut down in the +woods, it is only, I assure you, because such sugar and brandy would +cost more to make than other sorts, and would not be so good in the +end. Should some one ever invent and bring to perfection an economical +process for doing it thoroughly well, sugar-makers and spirit-distillers +will have to be on their guard! + +But we are wandering from our subject. If I have allowed myself to +make this digression, however, it is because I am not sorry to accustom +your mind early to the idea of those wonderful transformations which +nature accomplishes, and of which I could give you many other instances. + +To return to our flour. As soon as all the starch is gone out of it, +there remains in your hand a whitish, elastic substance, which is also +sticky or _glutinous_, so that it makes a very good glue if you choose; +and hence its name of _gluten_, which is the Latin word for glue. + +When dried, this _gluten_ becomes brittle and semi-transparent. +It keeps for an unlimited time in _alcohol_, putrefies very soon +in water exposed to the air, and is easily dissolved in a wash of soda +or potash. Finally 100 ounces of it contain as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +Observe the last material named. It is a new arrival, of which I shall +soon have something to say. + +But where am I leading you? you will ask, with all these uninteresting +details about glue. + +Wait a little and you shall hear. + +You have probably never seen any one bled, which is a pity, as it +happens; for if you had, you might have noticed (provided you had had +the courage to look into the basin), that after a few seconds, the +blood which had been taken away separated itself of its own accord +into two portions; the one a yellowish transparent liquid, the other +an opaque red mass floating on the top, and which is called the +_coagulum_ of the blood or _clot_. This _coagulum_ owes its color to an +infinity of minute red bodies of which we will speak more fully by and +by, and which are retained as if in a net, in the meshes of a peculiar +substance to which I am now going to call your attention. + +That substance is whitish, elastic and sticky; and when dried becomes +brittle and semi-transparent. It keeps for an unlimited time in alcohol, +putrefies very soon in water exposed to the air, and is easily dissolved +in a wash of soda or potash. Finally 100 ounces of it contain as +follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +This substance is called _fibrine_. It goes to form the fibres of those +muscles which are contained in a half formed state in the blood. + +You are laughing by this time I know, and I also know the reason why. +I have told you the same story twice over. You have not forgotten my +wearisome description of _gluten_, and here I am, saying exactly +the same thing of _fibrine_! You conclude I am dreaming, and have +made a mistake! + +But no, I am wide awake, I assure you, and mean what I say. And if +these details are the same in the two cases, it is for the simple +reason that the two bodies are one and the same thing; _gluten_ and +_fibrine_ being in reality but one substance, so that were the most +skilful professor to see the two together dried, he would be puzzled to +say which came from the flour, and which from the blood. I mentioned +that our muscles existed in a half-formed state in the blood. Here is +something further. The _fibres_ of muscles exist previously in full +perfection, in the bread we eat; and when you make little round pills of +the crumbs at your side, it is composed of fibres stolen from your +muscles which enable the particles to stick together; and I say _stolen +from your muscles_, because they are the _gluten_ which you ought to +have eaten. I hope the thought of this may cure you of a foolish habit, +which is sometimes far from agreeable to those who sit by you. + +This, then, is the first great _aliment of nutrition_, and you +may make yourself perfectly easy about the fate of those who eat bread. +If little girls should now and then have to lunch on dry bread, I do +not see that they are much to be pitied. There is the starch to keep +up their fire, and the gluten for their nourishment, and that is all +they require. The porter above is the only one who finds fault. And +in these days porters have become more difficult to please than the +masters themselves. + +Then as to babies who drink nothing but milk, you perhaps wish to know +where they get their share of fibrine. + +And I am obliged to own there is none in the milk itself; but, I +daresay, you know curdled milk or _rennet_? The same separation into two +portions has taken place there which occurs in the blood when drawn from +the arm; underneath is a yellowish transparent liquid,--that is the +_whey_; above a white curd of which cheese is made, and which contains a +great part of what would have made butter. By carefully clearing the +curd from all its buttery particles you obtain a kind of white powder +which is the essential principle of cheese, and to which the pretty name +of _casein_ is given because _caseus_ is the Latin for cheese. I shall +not trouble you now with details about _casein_; but there is one thing +you ought to know. A hundred ounces of _casein_ contain as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7 + Oxygen 13 + Nitrogen 17 + --- + 100 + +Exactly like gluten and fibrine! + +Now, then, you can understand that no particular credit is due to the +blood for manufacturing muscles out of the cheese of the milk which +a little baby sucks. He has much less trouble than the manufacturers +at Colmar have in turning their starch into sugar; because in his case +the new substance is not only composed of the same materials as the +old one, but contains them in exactly the same proportion also. + +We have a second aliment of nutrition, you see, and I must warn you +that it is not found in milk only. It exists in large quantities in +peas, beans, lentils, and kidney-beans, which are actually full of +cheese, however strange this may seem to you. It would not surprise +you so much, however, if you had been in China and had tasted those +delicious little cheeses which are sold in the streets of Canton. They +cannot be distinguished from our own. Only the Chinese (from whom we +shall learn a great many things when we have beaten them so that they +will conclude to be friends with us)--the Chinese, I say, do without +milk altogether. They stew down peas into a thin pulp. They curdle +this pulp just as we do milk, and in the same way they squeeze the +curd well, salt it, and put it into moulds--just as we do--and out +comes a cheese at last--a real cheese, composed of real _casein_! +Put it into the hands of a chemist, and ask him the component parts +of a hundred grains of it, and he will tell you as follows:-- + + Ounces. + Carbon 63 + Hydrogen 7, etc. + +I stop there; for you surely know the list by this time! + +Only the third aliment of nutrition remains to be considered, for there +are but three; and I will tell you in confidence, what is stranger +still, viz., that there is in reality but one! But we have had enough +food for one day, and I do not wish to spoil your appetite. We will +reserve the rest for another meal. + + + +LETTER XXVII. + +ALIMENTS OF NUTRITION (_continued_). + +NITROGEN OR AZOTE. + +There is a favorite conjuring trick, which always amuses people, though +it deceives no one. The conjuror shows you an egg, holds it up to the +light that you may see it is quite fresh, then breaks it; +and--crack--out comes a poor little wet bird, who flies away as well +as he can. + +This trick is repeated in earnest by nature every day, under our very +eyes, without our paying any attention to it. She brings a chicken out +of the egg, which we place under the hen for twenty-two days, instead +of eating it in the shell as we might have done, and we view it as a +matter of course. Yet we do not say here that the bird may not have +come down the conjuror's sleeve, or the hen may not have brought it +from under her wing. It was really in the egg, and its own beak tapped +against the shell from within and cracked it. + +How has this come about? No one can have put that beak, those feathers, +those feet, the whole little body, in short, into the egg while the +hen was sitting upon it, that is certain. It is equally certain, then, +that the liquid inside the egg must have contained materials for all +those things beforehand; and if Nature could manufacture the bones, +muscles, eyes, etc., of the chicken, out of that liquid while in the +egg, she would probably have found no more difficulty in manufacturing +your bones, muscles, eyes, etc., from it had you swallowed the egg +yourself. + +Here, then, is an undeniable _aliment of nutrition_. + +It is called _albumen_, which is the Latin word for _white of egg_. It +is easily recognized by a very obvious characteristic. When exposed to a +temperature varying from sixty to seventy-five degrees of heat, +according to the quantity of water with which it is mixed, _albumen_ +hardens, and changes from a colorless transparent liquid, into that +opaque white substance, which everybody who has eaten "hard-boiled eggs" +is perfectly well acquainted with. + +I will only add one trifling detail. 100 ounces of albumen contain as +follows: + + Ounces. + Carbon 63 + Hydrogen -- + +You can fill up this number yourself, can you not? And knowing the 7 +of hydrogen, you may guess what follows! After what we have talked of +last time, here is already an explanation of the chicken's growth. But +let us go on. + +You recollect that yellowish liquid I spoke about, which lies underneath +the _clot_, or _coagulum_ of the blood? I will tell you its name, that +we may get on more easily afterward. It is called the _serum_, a Latin +word, which, for once, people have not taken the trouble of translating, +and which also means _whey_. Put this _serum_ on the fire, and in +scarcely longer time than it takes to boil an egg hard, it will be full +of an opaque white substance, which is the very _albumen_ we are +speaking of. Our blood, then, contains _white of egg_; it contains in +fact--if you care to know it--sixty-five times more white of egg than +fibrine, for in 1,000 ounces of blood, you will find 195 of _albumen_, +and only three of _fibrine_; of _casein_, none. + +Nevertheless we eat cheese from time to time. And we generally eat +more meat than eggs, and meat is principally composed of fibrine! I +should be a good deal puzzled to make you understand this, if we had +not our grand list to refer to. + + Ounces. + Carbon 63 + Hydrogen 7, etc. + +_Fibrine_, casein_, _albumen_, they are all the same thing in the main. +It is one substance assuming different appearances, according to the +occasion; like actors who play several parts in a piece, and go behind +the scenes from time to time to change their dresses. The usual +appearance of the aliment of nutrition in the blood is _albumen_; and in +the stomach, which is the dressing-room of our actors, _fibrine_ and +_casein_ disguise themselves ingeniously as _albumen_; trusting to +_albumen_ to come forward afterwards as _fibrine_ or _casein_, when +there is either a muscle to be formed, or milk to be produced. + +Know, moreover, that _albumen_ very often comes to us ready dressed, and +it is not only from eggs we get it. As we have already found the +_fibrine_ of the muscle and the _casein_ of milk in vegetables, so we +shall also find there, and that without looking far, the albumen of the +egg. It exists in grass, in salad, and in all the soft parts of +vegetables. The juice of root-vegetables in particular contains +remarkable quantities of it. Boil, for instance, the juice of a turnip, +after straining it quite clear, and you will see a white, opaque +substance produced, exactly like that which you would observe under +similar circumstances in the _serum_ of the blood; real _white of egg_, +that is to say--to call it by the name you are most familiar with--with +all its due proportions of carbon, hydrogen, oxygen, and nitrogen. + +I wonder whether you feel as I do, dear child; for I own that I turn +giddy almost when I look too long into these depths of the mysteries +of nature. Here, for instance, is the substance which is found +everywhere, and everywhere the same--in the grass as in the egg, in +your blood as in turnip-juice! And with this one sole substance which +it has pleased the great Creator to throw broadcast into everything +you eat, He has fashioned all the thousand portions of your frame, +diverse and delicate as they are; never once undoing it, so to speak, +to re-arrange differently the elements of which it is composed. From +time to time it receives some slight impulse which alters its appearance +but not its nature, and that is all. As the chemist found it in the +bit of salad, so he will find it again in the tip of your nose, if you +will trust him with that for examination. We are proud of our personal +appearance sometimes, and smile at ourselves in the looking-glass; we +think the body a very precious thing; but yet when we look deeply into +it we find it merely so much charcoal, water and air. + +This reminds me that we have not yet made acquaintance with the new +personage who was lately introduced upon the scene. _Nitrogen_ or +_azote_, I mean. He plays too important a part to be allowed to remain +in obscurity. + +You have already learnt that oxygen united with hydrogen produces +water. Combined with nitrogen it produces air; but in that case there +is no union of the two. They are merely neighbors, occupying between +them the whole space extending from the earth's surface to forty or +fifty miles above our heads; together everywhere, but everywhere as +entire strangers to each other as two Englishmen who have never been +introduced! I should be a good deal puzzled to say what nitrogen does +in the air: he is there as an inert body, and leaves all the business +to the oxygen. When we breathe, for instance, the nitrogen enters our +lungs together with its inseparable companion, but it goes out as it +went in, without leaving a trace of its passage. Nevertheless, as +sometimes happens among men, the one who does nothing takes up the +most room. Nitrogen alone occupies four-fifths of the atmosphere, where +it is of no other use than to moderate the ardent activity of king +oxygen, who would consume everything were he alone. I can compare it +to nothing better than to the water you mix with wine, which would be +too fiery for your inside if you drank it by itself. This is what +nitrogen does. It puts the drag on the car of combustion; as in society, +the large proportion of quiet people put the drag on the car of progress +(let us for once indulge ourselves in talking like the newspapers!); +and such people are of definite use, however irritating their +interference may appear in some cases. The world would go on too rapidly +if there were nothing but oxygen among men. We have quite enough in +having a fifth of it! + +But what in the world am I talking about? Let us get back to nitrogen +as fast as we can! + +We must not imagine there is no energy in this quiet moderator of +oxygen. Like those calm people who become terrible when once roused, +our nitrogen becomes extremely violent in his actions when he is excited +by another substance, and is bent on forming alliances. Sometimes the +usually cold neighbor unites itself to oxygen in the closest bonds; +in which case the two together form that powerful liquid, _aqua-fortis_, +of which you may have heard, and which corrodes copper, burns the skin, +and devours indiscriminately almost everything it comes in contact with. +Combined with hydrogen, nitrogen forms _ammonia_, which is still often +called by its old name _volatile alkali_; one of the most powerful +bodies in existence, and one for which you would very soon learn to +entertain a proper respect, if somebody were to uncork a bottle of it +under your nose. Finally, nitrogen and carbon combined, produce a quite +foreign substance (_cyanogen_), resembling neither father nor mother in +its actions and powers, to the confusion of all preconceived ideas, when +Gay-Lussac, a Frenchman, introduced it to the world, where it fell like +a bombshell upon the theory of chemical combinations. This impertinent +fellow, combining with hydrogen in his turn, produces _prussic acid_, +the most frightful of poisons; one drop of which placed on the tongue of +a horse strikes it dead as if by lightning. + +You perceive that you must not trust our worthy friend too far. You +have learnt, however, elsewhere, that it is not equally formidable in +all its combinations. Those very substances which, when paired off +into small separate groups, destroy all before them, constitute, all +four together, that precious aliment of nutrition of which we are +formed. Moreover, its real name is "_azotized aliment_" because +it is the presence of nitrogen or azote in it, which, above all, +determines its quality, so that people are in the habit of estimating +the nourishing power of our food by the amount of nitrogen it contains. +In fact, nitrogen seems to be a substance especially inclined towards +everything that has life. His three comrades wander in mighty streams, +so to speak, through every part of creation; but he, except in the +vast domain of the atmosphere, where he reigns in such majestic repose, +is rarely met with, except in animals, or in such portions of plants +as are destined for the support of animal life. + +On this point I will tell you the history of his original name, +_azote_, which you will find curious enough. A short time before +the French Revolution, in 1789, the principal properties of this gas +were made known to the world by a learned Frenchman, who may be almost +considered the father of modern chemistry, and whose name I must beg +you to recollect. [Footnote: Dr. Daniel Rutherford (Edinburgh) +discovered the existence of _Nitrogen_, A. D. 1772; but he never +investigated its character.] He was called _Lavoisier_. While +endeavoring to account satisfactorily for _combustion_, which +before his time people explained any way they could, Lavoisier succeeded +in separating our two friends, the neighbors in the atmosphere, one +from the other, and was the first man in the world who managed to +secure in two bottles--on the one hand, the bubbling oxygen freed from +his tiresome mentor; on the other, the sober *azote, snatched away +from his giddy pupil. What he did with the bottle of oxygen matters +but little to us; but in the bottle of _azote_ he plunged, by way +of experiment, an unfortunate mouse, and subsequently a little bird, +both of whom, finding no oxygen to breathe, died one after the other. +Nothing could live in it, as you may suppose; and Lavoisier thought +it must be right to give so destructive a gas the name of _azote_, +which in Greek means "_opposed to life_." Meantime, science went +on progressing by the gleam of the lamp he had lit, and then followed +the discoveries of his successors, who forced their way into the obscure +laboratory where the elements of living bodies are prepared. And at +last it was ascertained that this _azote_, opposed to life as it +was thought to be, was actually an essential property of life; that +it accompanied it everywhere, and that without it the whole framework +of the animal machine would fall to pieces. It is still known by its +old name, which custom had sanctioned; but I imagine no learned man +can ever utter it now without a feeling of humility, and without the +thought that the future has possibly many contradictions in store for +him also. Besides, nitrogen has to pass through many fine-drawing +processes before it attains that post of honor which has been assigned +to it in the animal kingdom. The animal himself can do nothing with +it, unless it has been previously absorbed and digested by the +vegetable, and the vegetable in its turn could get no good from it, +were it to remain isolated and indifferent in the bosom of the +atmosphere. It is only when it has formed one of those combinations +I have been telling you about, and more particularly the second, which +produces _ammonia_, that it fairly enters upon the round of life. +And then, in the mysterious depths of vegetable existence is organized +that wonderful _quadrille_ of the _aliments of nutrition_, the history +of which has now been sufficiently explained to you. + +The vegetable kingdom, therefore, is simply the great kitchen in which +the dinner of the animal kingdom is being constantly made ready; and +when we eat beef, it is, in fact, the grass which the ox has eaten, +which nourishes us. The animal is only a medium which transmits intact +to us the _albumen_ extracted in his own stomach from the juices +furnished to him in the fields. He is the waiter of the eating-house; +the dishes which he brings us have been given him already cooked in +the kitchen. But to appreciate properly the service he renders us we +must remember that the dishes to be obtained from grass are very, very +small, and that it would be a great fatigue to the stomach if it could +only get at such tiny scraps at a time; as, alas! has sometimes happened +to the famine-stricken poor, who have tried in vain to support life +from the grass in the field. But these minute dishes are brought to +us in the mass whenever we eat beef, and our stomachs benefit +accordingly. Do not forget this, my child; and when mamma asks you to +eat meat, obey her with a good grace; if, that is to say, you wish to +grow up to be a woman. + + + +LETTER XXVIII. + +COMPOSITION OF THE BLOOD. + +One word more before we finish. We must not leave off without bidding +a last farewell to the good servant of whom we have spoken so much; +the model steward so exact in giving back everything he receives--the +factotum of the house in short. We have watched him at work long enough, +but I have not yet described him personally to you, nor told you exactly +what he is composed of. + +And here I shall be obliged to begin again with figures and +calculations, although I am told young people are not very fond of +them. Nevertheless, none of us can manage our affairs properly without +them. Hereafter, when you are at the head of a family, you will be +obliged to practise arithmetic, if you want to know what is going on +in your house. Never allow yourself to look upon what is necessary as +wearisome; the true secret of being punctual in our duties is to throw +our heart and interest into them. + +I choose, therefore, to suppose that you will be interested to know +that 1000 ounces of blood generally contain, (for there are shades of +difference between one sort of blood and another) 870 ounces of the +_serum_ I have been talking about, and 130 ounces of _clot_. At first +sight one would take the quantity of _clot_ to be much greater than it +really is; but in the state you see it, in the basin, it contains a +considerable amount of water, which belongs by right to its companion +_serum_, and which has to be drained away from it before it can be +weighed. + +Now, in our 870 ounces of serum, we shall find, to begin with, 790 of +water; do not be astonished at the quantity. Most of the weight of all +animals is produced by water; they weigh comparatively nothing after +being thoroughly dried in a stove--when they are dead of course--for +neither animal nor plant can live unless saturated with water. This, +by the way, may serve to explain the ease with which we can keep +ourselves floating in water; we are not much more than water ourselves! +Were it not for those abominable bones which are a little bit heavier +than the rest, we should never sink unless a stone were hung round our +necks. + +I repeat then; 790 ounces of water in 870 of _serum_, which leaves 80. +Of this, _albumen_ furnishes seventy, and the ten others, with the +exception of a small portion of fat which floats here and there +ready-made, are _salts_. It would take too long to explain what _salts_ +are here, but there is one sort of salt you know perfectly well; viz., +that which is put on the dinner-table in a salt-cellar. And it is the +most important of all. More than half the ten ounces of salts consist of +it alone, which will make you understand better than before, what I +explained with reference to the stomach; that is, why we put salt in our +food. The porter above is quite up to his business when he asks everyone +who enters to produce his little bit of salt. It is an attention which +the blood appreciates very highly, although table-salt is of no great +use to him in his building operations; but it evidently keeps him in +good humor, and he would work badly without it. It is the same with all +the animals man makes use of, and even the plants he cultivates, find +that salt gives them an appetite. And it would almost seem as if nature +had purposely dealt with us in this matter on a magnificent scale. She +has made salt-magazines of the sea and the bosom of the earth, where it +exists in prodigious masses which cost nothing but the labor of stooping +to pick up, except in countries where a gentleman called a tax-gatherer, +stands by to count the lumps and allow them to pass on by paying a +duty. For my part, if I were the government--this is a secret between +you and me, mind--I would look out for something else to stand in the +place of the salt-tax. It is not well to interpose between man and the +gratuities of Dame Nature, and to make him pay more heavily for the +blood's chosen friend than she meant him to be charged. + +But to proceed, the kitchen-salt being deducted from the ten ounces +of salts-in-general, there remain altogether from four to five ounces, +which contain----. But here I stop, for it puzzles me very much how +to go on! Enough, that to enable you to follow me, you would require +at least as much knowledge of chemistry as will be expected of a young +man who has to pass an examination in medicine. Fancy the contents of +a whole druggist's shop! I will tell you a few names, that you may +have a specimen of the style in use, but I forewarn you that they are +not inviting: _hydrochlorate of ammonia; hydrochlorate of potash; +carbonate of lime; sulphate of potash; phosphate of lime; phosphate +of magnesia; lactate of soda._ I spare you the others, for many +others there are, without counting those which have not yet been +discovered I All these things are to be found, I must tell you, in +fibrine and albumen, but in such minute quantities that it is scarcely +possible to recognize them. + +In the serum, for instance, the gentlemen are so very small, and so +completely entangled one with the other, that it is startling to think +of the skill and patience requisite for making them all out, to say +nothing of affixing the right name--uncouth as it may seem--to each +grain of this almost imperceptible dust! He who first called man an +epitome of creation, scarcely knew how truly he was speaking, for man +bears about in his veins, ascertained samples of at least half the +primitive substances from which all others are made, and if the whole +of them should some day be found to be there, I for one should not be +surprised. + +This is well worth knowing, is it not? and I have not come to the end +of my story yet. + +We have still the 130 ounces of _clot_ to speak about. But their +contents are easily reckoned. Three ounces of fibrine and 127 of +_globules_. + +Here, however, we enter upon such a world of wonders, that I am quite +delighted to be able to finish with it. It will be the masterpiece of +our exhibition! + +You feel quite sure blood is red, do you not? Well! it is no more red +than the water of a stream would be, if you were to fill it with little +red fishes. Suppose the fishes to be very very small, as small as a +grain of sand; and closely crowded together through the whole depth +of the stream: the water would look quite red, would it not? And this +is the way in which blood looks red: only observe one thing; a grain +of sand is a mountain in comparison with the little red fishes in the +blood. If I were to tell you they measured about the 3,200th part of +an inch in diameter, you would not be much the wiser, so I prefer +saying (by way of giving you a more striking idea of their minuteness) +that there would be about a million in such a drop of blood as would +hang on the point of a needle. I say so on the authority of a scientific +Frenchman--M. Bouillet. Not that he ever counted them, as you may +suppose, any more than I have done; but this is as near an approach +as can be made by calculation to the size of those fabulous +blood-fishes, which are the 3,200th part of an inch in diameter. + +These littlest fishes are called _globules_; but they are not +exactly shaped like _little globes_, as the word would lead you +to suppose. They are more like little plates slightly hollowed out on +both sides. The central nucleus is surrounded by a flattened margin +rather bladdery in appearance, of a beautiful red color, formed of a +sort of very soft and very elastic jelly. I scarcely need tell you +that all this was discovered through the microscope, and moreover, by +examining the blood of frogs, in which the globules are much larger +than in ours. [Footnote: Authentic portraits of these globules drawn--so +to speak--by Nature herself, are to be seen on the admirable Photographs +obtained by Bertsch, with the aid of the solar microscope, invented +by himself and Arnaud. There you see them magnified 250,000 times, and +may study them at your ease, and verify my description for yourself +without any fear of being deceived. You must persuade your father to +procure one. This result of photography is among the wonders of modern +science.] + +It was in 1661--rather more than two hundred years ago--that an Italian +and a Dutchman discovered, each by himself in his own country, the +microscopic population of the blood. The name of the Italian is not +very difficult--_Malpighi_. As to the Dutchman's, you must pronounce it +in the best way you can--he was called _Leeuwenhock_. You smile, but he +was nevertheless one of the first men who really comprehended what a +wonderful auxiliary human science had just got hold of in the +microscope, and he has helped to open the eyes of the world to the +marvels of miniature creation. So content yourself, young lady, with +mis-pronouncing his name, and beware of laughing at it! Names are +something like faces, one may live to be ashamed of ridiculing +the wrong one. + +This discovery of the globules of the blood, was destined to throw +great light upon the way in which the _nutrition of the organs_ +was carried on. Modern chemists, who are always fond of investigation, +have examined what they are made of, and can find little else in them +but _albumen_. Out of our 127 ounces of globules, 125 are albumen; +and these, with the 70 ounces which we found before in the serum, make +up the 195 ounces (of albumen) which I told you were contained in the +1,000 ounces of blood. Forgive me all these ounces and figures. Exact +accounts give exact information. + +These globules, then, are composed almost entirely of albumen. Nearly +two-thirds of all the albumen in the blood is concentrated in them; +and you know now the use of albumen, viz., that it is the foundation +of all the buildings of which the blood is the architect. Everything +leads us to believe that the formation of globules in the blood is the +last touch given by nature to that magical provision begun in +thevegetable, continued in the stomach, and finished in the veins, to +which, in combination with carbon, hydrogen, oxygen, and nitrogen, we +are indebted for the subsistence of every portion of our body. Thus +the blood-globules may be considered as albumen which has finished its +education, and is ready to go into the world; while the albumen of the +serum is, like our young friends, the generations in reserve, who are +still at school awaiting their turn. + +This is more than a mere supposition. Scientific men have taken to +themselves, on their own authority, all sorts of rights over animals, +and we profit basely enough by their crimes--I will not withdraw the +word--in order to increase our knowledge. Accordingly, they conceived +the idea of opening the veins of animals, and allowing the blood to +flow until the victim was prostrate and motionless as a corpse. This +done, they proceeded to fill the exhausted veins with blood, similar +to that which had been withdrawn, and with the blood, life was seen +gradually to return, till the animal rose from the ground, walked, and +resumed its disturbed existence, as if nothing had happened. The +interesting part of the experiment to us is, that if serum only, without +globules, be restored to the unfortunate animal, it is of no use +whatever, and the corpse does not revive. + +It is evident, then, that all the power and virtue of the blood lies +in the globules; and according as their number is great or small it +is "rich" or "poor," as it is called; and where their number is not +up to the mark, the blood acts more feebly on the organs, life is +calmer, and people are no longer troubled with emotions--in other +words, with violent heats of the blood. Hence the impassible character +of _lymphatic_ people, who often get on in the struggle of life +better than others, because they are never in a hurry, and know how +to wait for opportunities. You will occasionally hear the word +_lymphatic_, for it has become the fashion, and it is time for +me to explain it; but unluckily the explanation is not in its favor. + +You remember those little scavengers we spoke about formerly, who came +from the depths of all the organs, carrying away with them the worn-out +building materials, and covering the surface of the body with an +inextricable net work of tiny canals. These canals are called +_lymphatic vessels_, in consequence of being filled with a liquid +which is called _lymph_ (_water_, in Latin), but why I cannot +tell you, for it is, in fact, simple _serum_. There was a very +simple way of ascertaining this by making out an inventory of the +contents of the _lymph_ liquid, and when this was done, they were +found to consist of water, albumen, and the salts of serum; there was +even a little fibrine; the only thing wanting was _globules_. + +How the truant serum finds its way into the lymphatic vessels is +probably as follows:--I have already mentioned the inconceivable +delicacy of the capillary vessels, those last ramifications of our +arteries and veins. It needs all the impulsive power of the heart to +enable the blood to force its way through these narrow passages; and +minute as are the globules, it would seem that they have but just room +to pass, for in examining under the microscope a corner of the tongue +of a live frog, the globules have been seen doubling themselves up to +pass through the capillaries, resuming their natural form afterwards. + +It was this, indeed, which made me tell you just now that their margins +were elastic. During this momentary crush, part of the serum being +forced on too fast, oozes through the wall of the over-filled +capillaries, as water oozes through the leathern pipes of a fire-engine, +and hence probably the appearance of serum or _lymph_ in the organs, +where it is immediately sucked up (i. e., _absorbed_) by the lymphatic +vessels. Now, you will easily understand that the larger the proportion +of serum in the blood, the greater will be the quantity to be expelled +in passing through the capillaries, and the more will the lymphatic +vessels swell. In such cases the temperament or constitution is said to +be _lymphatic_. If, on the contrary, the globules are in excess, the +lymphatic vessels receive less serum, and diminish in size. The +temperament is then called _sanguine_, as if there were no serum in the +blood. You shall be judge yourself, knowing what you now do, whether it +would not be more reasonable to call such temperaments _serous_ and +_globulous_. At any rate those names would give people an idea of the +real state of things, and teach them that there were such things as +globules in the blood. + +[Footnote: Here is a summary of the contents of 1000 oz. of blood:-- + + Ounces. + Water................... 790 + Serum. Albumen...................70 870 + Salts.................... 10 + + Fibrine................... 3 + Clot. Globules Albumen.. 125 130 + Coloring matter...... 2 127 + ---- + 1000 + ----] + +To conclude, I must give you an account of the two ounces which still +remain of the 127 of globules, albumen taking up only 125, as you know. +Those two poor little ounces--the remainder of the thousand with which +we started--would you believe it?--they alone have the honor of +conferring upon the blood its beautiful red color. They constitute the +coloring matter of the globules, and you will never guess its chief +element. It is iron; ay, actually iron, young lady--the iron of swords +and bayonets. We often accuse it of tingeing the earth with blood; and +you may now know further, that it reddens blood itself by way of +compensation. Do not trouble yourself as to where it comes from. Our +fields are full of it, our very plants have stores of it. It sometimes +happens that our digestive apparatus, put out of order by other +occupations, fails to make use of the amount of iron offered to it; +in which case the blood is discolored, and the face turns pallid as +wax: this is an illness requiring great care. If it should ever befall +you, you will not be surprised, after to-day's lesson, to hear the +doctor say that you must have some iron. But be easy--you will not +have to swallow it whole! If you will take my advice, you will obey +the doctor's orders as soon as you can. + +Not that looking pale signifies any thing: indeed, some young ladies +think it an advantage. But it is no advantage to any body when the +blood-globules are distressed for want of their proper supply of iron, +and do their work grudgingly, like ill-fed laborers. Nothing can go +on without them, you know, and they are people whom it is not well to +leave too long out of sorts. Else languor comes on; languor which is +the beginning of death: and pray remember that iron, which so often +causes death, is equally useful for keeping it at bay. By sending it +to the discolored globules, you give them back their energy and +brilliancy together. + +I have come here to the end of all that is known with any certainty +about these wonderful globules which are to us the medium of life. +Shall I go further, is the question, and take you with me into the +fields of supposition, so full of noxious weeds? And yet why not? +Science owes its present position to the praiseworthy rule of never +adopting any theory which is not supported by well-established facts; +and I would be the last to advise a change. Were I to tell you, what +I am now going to say to you, at a meeting of the British Association +of Science, they would turn me out of the room, and with very good +reason. Nothing ought to be taught there but what can be proved. But +this is of no consequence to you and me, and we have a right to amuse +ourselves a little, after having worked so hard. + +Well, there is an idea which nothing shall ever drive out of my head, +however imperfectly it may be proved as yet; namely, that each of our +globules is an animated being; and that our life is the mysterious +result of these millions of lesser lives, each of them insignificant +in itself; in the same way that the mighty existence of a nation, is +a compound of crowds of existences, each, for the most part, without +individual importance. Take our own or any other country as an instance; +where millions of brains, many of them by no means first-rate in power, +go to form a national character, the highest (as each _nation_ +is apt to think of itself) in the world. According to this idea, you +must be a sort of nation yourself, my dear child, which is gratifying +to think of on the whole. + +This is much more extraordinary than what I told you some time ago, +of the individual life of the organs, each of which on this new system +would be a province in itself! Do not exclaim too hastily. Whether the +globules are animated or not, it is very certain, let me tell you, +that your life depends entirely upon them; that it is weakened if they +are weakened; that it revives with them; and that whether you attribute +individual life to them or not, makes no alteration in the fact: their +action upon you remains the same. And he must be a very clever man who +can show me the exact difference between action and life. Hereafter, +when we have descended the scale of the animal world together, and are +arrived at the study of what are called microscopic animals, you will +better understand the words which appear so strange to you now. What +little our feeble instruments have revealed to us so far, of the history +of those globules, places them almost on a level with those strange +creatures, inexplicable to us, which are found in innumerable +multitudes, in a variety of liquids. We trace in them the beginning +of organization; their form and size are alike in all individuals of +the same species; and species vary enough to induce one to believe, +that there is a necessary relation between an animal's way of life and +that of its globules. If the microscope has not yet caught them in any +overt living act, who can be surprised? it is only dead blood which +has been submitted to the test. They ought to be observed in the +exercise of their functions, in the living animal itself, as has been +done to some extent in the frog; and if our foolish chat could influence +scientific observers, I would say to them what M. Leverrier said years +ago to the astonished astronomers: "Look yonder; you ought to see a +light there with which you are not yet acquainted!" + +I am carrying you a long way on the wings of my fancy, my dear child; +but have no fears; I will not let you fall. This life of our globules, +which would, after all, be only one mystery the more among many, opens +before our eyes a magnificent vista of the uniformity in the scheme +of creation; which goes on repeating itself, while enlarging its circles +to infinity. We may, all of us, be only so many globules of the great +invisible fabric of humanity, in which we go up and down one after +another; and those vast globes which our telescopes follow through +celestial space, may be but globules of one, as yet unknown, to which +the Almighty alone can give a name. + +Take this page to your father, my dear child, if you do not understand +it rightly; and now, shake hands, my history is ended! + + + +PART SECOND--ANIMALS. + +LETTER XXIX. + +CLASSIFICATION OF ANIMALS. + + +'It is dangerous to show man how much he resembles the beasts, without +at the same time pointing out to him his own greatness. It is also +dangerous to show him his greatness, without pointing out his baseness. +It is more dangerous still to leave him in ignorance of both. But it +is greatly for his advantage to have both set before him.'--_Pensées +de Pascal_. + +The man who wrote that, my dear child, did not trouble himself much +about children. He was one of the gravest specimens of literary +genius--a man who can scarcely be said to have ever been a child +himself; for as the story goes, he was found one day, when only twelve +years old, inventing geometry, and his father only saved him from +trouble, by putting the great book of Euclid into his hands; and, at +sixteen, he wrote a treatise on _Conic Sections_, which was the +wonder of all the learned men of the day. I have not a very clear idea +of what Conic Sections are myself; but I tell you this to show that +Pascal was a very profound and learned man, under whose authority, +therefore, I am very glad to take shelter, now that I am going to set +before you the very startling points of resemblance which exist between +you and the beasts. + +As to your greatness, it delights me to explain it to you. It is not +due to the handsome clothes you wear when you are going out, nor to +the luxurious furniture of mamma's drawing-room, but to the possession +of that young soul which is beginning to dawn within you, as the sun +rises in the morning sky, and pierces through the early mists; in that +growing intelligence which has enabled you to understand so far all +the pretty stories I have told you; in that fresh unsullied conscience, +which congratulates you when you have been good, and reproves you when +you have done wrong: all of them gifts which are not bestowed on the +lower animals, or certainly not to the same extent as upon you--gifts +by which you rise more and more above them, the more they are developed +in yourself. Your baseness--but, begging Pascal's pardon, I cannot +call it baseness--your connecting link with the brute creation lies +in those other gifts of God which you and they share in common--in +those wonders of your organization, which we shall now meet with in +them again, in full perfection at first, and that in every respect; +by which fact you may learn, if you never thought of it before, that +the lower animals come from the same creating hand as yourself, and +ought to be looked upon to some extent as younger brothers, however +distasteful such a notion may seem at first. Societies have been +established of late, both in France and England, for the protection +of animals; and a noble and honorable task they have undertaken, in +spite of the jokes that have been made at their expense. It is a +mischievous cavil to tell people who are doing good in one direction, +that more might have been done somewhere else. Everything hangs together +in the progress of public morality, and you cannot strike a blow at +cruelty to animals without at the same time making a hit at cruelty +to man. And the best argument in favor of the rights of beasts to +protection, will be found in the tour you and I are now going to make +together through the different classes of the animal creation. + +Let us begin with the horse--one of the beasts which oftenest needs +our protection. Give him the mouthful of bread whose history we have +just finished. He accepts it as a treat, and needs no pressing to eat +it. And if it could tell you all its adventures afterwards, you would +find that you were listening to precisely the same story as your own +over again; that nothing was different, nothing wanting. First of +all--teeth to grind it, and a tongue to swallow it with, as a matter +of course. Next a _larynx_, which hides itself to avoid it, and an +oesophagus,* which receives it, just as in your case; a stomach with its +_gastric juices_, the same as yours, in bagpipe form, and its _pylorus_, +like your own; a _lesser intestine_, into which bile pours from a liver +like yours; _chyliferous vessels_ which suck up a milky chyle, as with +you; farther on a _large intestine_; and so on to the end. Nor is this +all:--the horse has also a heart, with its two _ventricles_, and its +double play of valves; a heart which the little girl in our tale might +confidently have exhibited to the engineers as her own, but that it +would have been somewhat too big, of course; into which heart, as into +ours, comes _venous_ blood, to be changed afterwards to _arterial_; in +lungs to which the air keeps rushing, forced thither by the see-saw +action of a _diaphragm_, as faithful a servant to him as to you. +And those lungs like our own, are a charcoal market: the same exchange +takes place there, of carbonic acid for oxygen, as in ours, an +unanswerable proof that the stove inside the horse burns fuel in the +same way as our own: and if you were to place the thermometer inside +his mouth (for we are polite enough to call it his mouth), it would +mark 37 1-2 degrees of heat (centigrade)--a difference from ourselves +not worth mentioning. Finally, if you examine his blood, you will meet +with the same _serum_ and _clot_, the whole company of _hydroclorates, +phosphates, carbonates, &c._, from which we shrank before, and globules +made like your own; having the same construction, and the same life, or +action, if you like it better. I need scarcely add that 100 oz. of its +_fibrine_ and _albumen_ contain: + + Of carbon......... 63 oz. + Of hydrogen........ 7 + +This is understood all along as being the case everywhere, from man +down to the turnip; so that, like you, this noble animal, as the horse +is called, is in point of fact only so much carbon, so much water, and +so much air, joined to a handful of salt, which represents the earth's +share in the bodies of animals. + +You must confess that, if we cannot quite call the horse a +fellow-creature, he is nevertheless very like us. And it is the same +with all those animals which man makes use of as his servants, and +which have really a sort of right to the protection of society, since +they form, to a certain extent, a portion of the human family. I do +not speak here of the dog, who pays his taxes, poor fellow, in his +quality of friend to man. + +When I think of the almost identical organization of man and his +next-door neighbors, I am astonished how it could possibly have come +into the head of a certain learned individual (I will not mention his +name), when drawing up a plan of natural history, to give to man a +separate kingdom, as a sequel to the three kingdoms already +established--the mineral, vegetable, and animal. One might have forgiven +Pascal if such an idea had got into his head after writing his treatise +on Conic Sections; there being nothing in them to throw light on such +a subject. But in a naturalist, an observer who had spent his life in +the study of living creatures, the thing seems almost incredible. +Possibly he had reasons for what he did, but he certainly did not find +them in the subjects of his studies. + +Forgive me, my dear child, for forgetting you in this fit of indignation +upon a point you cannot care much about. It leads me naturally enough +to my present business, which is none of the easiest, but you must +help me by paying attention. I am going to describe the _classification +of the animal kingdom_. + +There are a terrible number of animals, as you know; and if we wish +to study them to any real purpose, we must begin by introducing some +sort of order into the innumerable crowds which throng, pell-mell, +around us for observation. We should otherwise never know where to +begin, or when we had come to an end. + +There are many ways of setting a crowd in order, but they all go upon +the same plan. The individuals composing the crowd are parcelled off +into companies, each company having a distinguishing mark peculiar to +those who compose it. Thus the first division is into a few large +companies, which are afterwards subdivided into smaller ones, and those +into others still less, until the divisions have gone far enough. And +this is what is called a _classification_. + +Let us imagine, as an example, a large crowd in a public garden; I +will soon classify it for you. I shall put the men on one side and the +women on the other. Then--to begin with the women--I shall subdivide +them into married and single. Then among married women I shall make +a company of mammas, and another of those who have no children. Among +the unmarried I shall have a group of those who have never been +married--girls, that is--and another of widows--those who were once +married, but are so no longer. Then, following the girls, I shall +separate them into tall and short. And among the short ones I shall +divide the brunettes from the blondes, and so I shall get at last to +a little blonde girl, whose classification (were she a soldier) in +military rank would be as follows:--_squadron_ of blondes; _company_ of +shorts; _battalion_ of girls; _regiment_ of unmarried women; _division_ +of women. The division of men could be carried out in the same manner; +and thus we should classify our mob into complete military order. This +is easy enough, however; but the classifying of animals is a very +different affair, and I will tell you why. We ourselves require a +classification to study them by, though none was needed for their +creation. The Almighty has formed them all on one uniform plan, around +which He has, if I may so express it, lavished an infinity of +modifications separating species from species, yet without placing +between the different species those fixed barriers which we should +require now to enable us to classify them strictly. You who are learning +the pianoforte have perhaps been told the meaning of a _theme_ of +music--the first idea of the composer who follows it throughout the +piece from one end to the other, embroidering on it, as on a bit of +canvas, a thousand variations melting one into another. Such is pretty +nearly, if we may venture the comparison, the way in which we can +picture to ourselves the Almighty moving through the work of animal +creation. Step in afterwards and divide away into regiments and +battalions, if you please. Nature permits it, but she will never, +to accommodate your classifications, separate what in her is really +united. + +There is still a way, however, and that is to do as I did just now in +the case of the crowd. To take, viz., only one _character_ (as we call a +distinguishing mark in natural history), and to throw together all the +individuals which possess it, the blondes, the shorts, the girls, &c. In +this way it may soon be done; but what is the result? You are in one +class, your eldest sister is in another, your mamma in a third, and your +brother in a different division altogether, a long way from you all. +Such a classification is called _artificial_, and you can see at once +that it is worthless. + +The most natural plan is to put together those that are of the same +family; and the classifications made on this principle are called +_natural_ classifications. + +It is a classification of this sort which has been adopted for the +animal kingdom. People have taken all the animals which possess in +common not one character only, but a collection of characters of the +most important kind, _dominant characters_, as they are called; +and of these animals they have formed, to begin with, large primary +groups; subdividing these afterwards according to the secondary +differences, which distinguish different species in the same group +from each other. + +In this manner all the different sorts of animals are included in +different systematic divisions of one vast whole, through which it is +easy to find one's way, because there is a beginning and an end; and +in which animals of the same family are always grouped side by side. +Were I to mention all the divisions of this immense classification at +once, you would find the account a little long, and not very amusing. +We will go through them by degrees therefore, and, to simplify matters, +will, throughout the whole, only consider those particular characters +which are connected with our special study, the nourishment of life, +that is to say: so that you will always find yourself on well-known +ground. + +I must tell you once for all, however, that it is with this as it is +with grammar. Here and there are--and it cannot be avoided--certain +exceptional cases which keep protesting timidly against the +arbitrariness of rules; but no matter; we must be contented with what +we can get, and be grateful into the bargain to those who have given +us this skillful classification, at once so ingenious and useful, in +spite of its inevitable imperfections. What is impossible is expected +of nobody. You could not understand, even if I wished to explain it +to you, the amount of science, labor and genius requisite for making +out that long list, which, tiresome as it may seem to children, is +absolutely beautiful in the eyes of learned men; too beautiful, perhaps, +and I will tell you why when we have finished. Meantime, as the best +reward we can give to those who have done us some great service is to +teach their names to children, I will tell you, before bidding you +good-bye, to whom we owe this classification, the details of which I +do not enter upon to-day. + +In the first place, we owe the method employed in its establishment, +the method of _natural classification, i.e._, to a learned man +of the last century--a learned Frenchman, Bernard de Jussieu--who tried +it upon plants; another large flock by no means very easy to put in +order, as you may convince yourself any day by studying botany. The +man who applied this system to animals was also a learned Frenchman, +the clearness of the French mind adapting them peculiarly for that +sort of work. And he, too, is one of the glories of that nation. His +labors and discoveries gave a perfectly new impulse to the study of +nature. It was George Cuvier, whose statue you may see at Montbéliard, +if you should ever go there. Not that Cuvier carried through this +gigantic work alone, though the credit of it is justly his due, he +having directed and inspired it. He was assisted by many. But among +his assistants there was one, Laurillard, the most modest, yet the +most active of all, whose name I will mention also, because, like the +others, more or less celebrated, he has never had his reward. [Footnote: +In the earlier editions of this work, there was, in this place, a +severe reproach upon Cuvier for not having given proper credit to +Laurillard. This reproach I have since learned was unjust. M. +Valenciennes himself, one of the most illustrious of the collaborators +of the great Cuvier, has written me a letter in which he defends the +reputation of his friend with a warm indignation which does honor to +both of them; and cites passages in which Cuvier has spoken of +Laurillard, and among others, in the third volume of the _Ossements +Fossiles_, p. 32, ed. of 1822.] + +It only remains for me, therefore, to let the lash, which I was laying +upon the shoulders of another, fall now upon my own, and to deplore +the too great facility with which I had credited, without sufficient +proofs, an assertion which I had otherwise good reason to believe to +be exact--coming to me, as it did, from Montbéliard himself, on the +testimony, it is said, of the family of Laurillard. From this avowal, +a little painful, I confess, my young readers may learn the +inconvenience of rashly condemning others! As I said in the concluding +passage, which truth, only too late, now compels me to suppress--"The +truth is sure to come out at last." + + + +LETTER XXX. + +MAMMALIA. (_Mammals_.) + +Do you remember of my talking of the _vertebral column_ when I was +describing that great artery, the _aorta_, to which it forms a rampart +of defence? I should not have named it without explanation, but that you +had only to pass your hand down your back to find out what it was. Now +the _vertebral column_, or backbone, is one of those _dominant +characters_ which always carries along with it a train of other points +of resemblance in the animals where it is found. It has been chosen, +therefore, as the rallying-point of the first great group. I must tell +you beforehand that there are four of these groups, four large +companies, _i.e._, which naturalists have called by various names; as +Groups, Sections, Primary Divisions and even Branches; in this case +comparing them to four great branches of a tree, going off in different +directions from the same trunk. + +And, first of all, we have to begin with the group of the +_Vertebrata_--vertebrata animals--vertebrata being a word which +explains itself. + +Of course we ourselves belong to this group. In fact, we are at the +head of it; but it descends far below us. It goes on to the frog and +the fish, and includes the monkey, the ox, the fowl and the lizard; +for all these creatures possess the vertebral column. The frog does +not appear to be very much like us at first sight; and yet, by virtue +of its vertebra, it has its points of resemblance to us, which are +worth the trouble of considering. Vertebrated animals are all furnished +with a head, containing a brain, which gives its orders to the whole +body; they have all an internal skeleton, that is to say, a system of +bones linked together, forming a solid base by which all the organs +are supported. I was going to add that they have all four limbs; but +here the serpent glides in to call me to order, and to hiss at our +childish craving for fine-drawn divisions, in perfect order, where +there is an exactly proper place for everything. However, each has, +without exception, a heart, with its network of blood-vessels; red +blood, under its two conditions of arterial and venous; and also a +digestive tube, acting, on the whole, pretty much like our own. I do +not insist, mind, upon this last point, viz., that of the digestive +tube; for we shall see, by-and-by, that it is a character beyond the +pale of the primary groups. It is the fundamental character of the +trunk itself, which necessarily exists, therefore, in all the groups; +and, as I told you in my first letter, you will find it everywhere. + +This is--to let you into the secret at once--the theme on which the +Great Composer has based all His infinite varieties of animal life; +and herein lies the uniformity of the animal creation, that startling +uniformity which has given so much offence to many learned men, and +which is so obvious that it will strike you of itself, I feel sure. +But I reserve this subject to the end of my letters, when you will +have heard all, and be able to judge for yourself. + +It would be plunging back into confusion to attempt to examine all the +vertebrated classes at once. After making a division you must go on. +The groups have, therefore, been subdivided into _five classes_, which +we will study in succession, only naming each now: viz. _mammals_, +_birds_, _reptiles_, _fish_, and _batrachians_. Do not alarm yourself at +this last name: it is a Greek word, meaning simply frogs. + +The mammals are our immediate neighbors. Mammalia are the animals which +produce milk. They bring forth their young alive, and give suck to +them as soon as they are born. This was your first nourishment, my +dear child, so you yourself are a little mammal. + +What I said to you in the last letter about the horse, applies pretty +nearly as well to all mammals. We shall not, therefore, have any great +variations to notice here. Nevertheless, as these are the animals which +interest us most nearly, as they are in fact our nearest of kin, so +to speak, and those with whom we have the most to do, we will now pass +in review the different orders of which their class is composed. I +must explain to you that the _classes_ are subdivided into +_orders_, the orders into _families_, the families into +_genera_, the genera into _species_; as in armies divisions +subdivide into regiments, regiments into battalions, &c. It became +necessary, moreover, to make use of special names, in order to make +these subdivisions comprehensible, and the following are those which +have been adopted. + +ORDER 1. _Bimana (two-handed)_. + +Here we may pass on at once, for we have discussed this order enough +already. We are _bimane_ ourselves, since we have the distinction +of possessing two hands. Yes; that is the pretty title which the +professors have been so polite as to give us, instead of leaving us +simply our proper name of man. Yet it would have been very easy to do +this, seeing that we are the only family, the only genus, and the only +species of the order. In railway travelling, people of distinction +have a reserved carriage to themselves: so we decidedly deserve an +order to ourselves; but that is not quite the same as a separate +kingdom. In short, you are a _bimane_; so make the best you can of it. + +ORDER 2. _Quadrumana (four-handed)_. + +These, as their name indicates, have four hands: two at the end of the +arms, and two at the end of the legs; such are the monkeys. There is +nothing to remark; they are all alike. Stay; I am wrong, though: there +is something, insignificant it is true, but still pointing to deviation. +In some the canine teeth are set forward, _i.e._ project, and are +longer than the rest, and some species, as the ape, for instance, have +just under their cheeks convenient little pockets, which open into the +mouth, and in which they can deposit a reserve of nuts to be devoured +at leisure; these are called _pouches_. + +It is a trifle in itself, but we have here a first example of the +eccentricities of nature in the construction of animals. At one time +she adds a detail; at another she suppresses one. Sometimes she is +pleased to enlarge an organ, as in the canine teeth of the monkey; +sometimes she reduces it; or perhaps here she makes its construction +more simple; there again more complicated: but still it is always the +same organ. So the dressmaker shapes the sleeves of a dress, sometimes +open, sometimes closed, flat or puffed, plain or ornamented, +pagoda-shaped or gigot-formed: but still they are all of them sleeves. + +ORDER 3. _Cheiroptera (wing-handed)_. + +I am quite ashamed of offering you such a word as this, my dear child. +It was a Greek fancy of the learned men, who would not condescend to +use the vulgar name Bats. In the Greek, _cheir_ means hand, and +_pteron_ wing. The Cheiroptera are animals with winged hands; in +fact, the fingers which terminate the fore-limbs of the bat lengthen +as they spread out to an extravagant extent; and are connected together +by a membrane springing from the body, with which they beat the air +as with a wing, and which enables them to fly with such ease that +theyare often taken for birds. + +But, so far from really being a bird, this curious little creature has +the same internal organization as ours, and indeed comes so near us, +though without looking as if it did, that a scientific man, and a very +distinguished one too, placed the bat in the first family of the animal +kingdom, with the monkey, and, you will hardly believe it, with man. +It is found that the bat, like man and the monkey, suckles its young +at the breast; and it was this very character which Linnæus, the leader +of artificial classification, thought of selecting as the distinguishing +mark of his first family in the animal kingdom. It is true that in +honor of the human race he had given that first family a much more +sonorous name than our usual one of _man_--viz. _primates_, the first in +rank--that is, the princes. But, alas! we were to be princes on an +equality with bats; and, for my own part, I prefer being a _bimane_, and +alone. I really believe that it was to put this saucy little creature +back into its proper place that, at the time of the great revolution in +favor of natural classification, the conclave of professors assembled at +the Botanical Gardens in Paris inflicted this horrid name of Cheiroptera +on the bat, ejecting it contemptuously from the overthrown dynasty of +the _primates_. + +I have not been sorry to make you acquainted as we went along, with +this little trait in the history of classification; but beyond it there +is really nothing particular to say about the apparatus for the +nourishment of the deposed bat-princes, which is a plain proof how +nearly it must be like our own. By-the-by, there is one trifling remark +to be made with regard to her teeth. The bats we have in our country +(France), for there are many varieties of species in the world, live +on insects, which they catch in their flight by night. These insects +are often enveloped in a very hard outer case, which molars like ours +would have some difficulty in chewing properly; consequently the molars +of our little friend are fringed with conical points, and with these +she grinds down her prey without difficulty. + +In America there is a large bat, the vampire, which lives on the blood +of animals, and nature has armed it accordingly. It has at the +extremityof its muzzle two sharp beak-like incisors, like the lancets of +a surgeon. The vampire bat, which roams by night like other bats, goes +straight at the large animals it sees asleep, delicately opens a vein +in the throat without waking them, and sucks their blood in long +draughts, taking care, by fanning them with its wings, to lull them +into a cool and balmy slumber. It does not, as you see, make a savage +attack on its victim: it merely inflicts a bite like that of the leech, +but the result may be death. This is the best emblem I know of the +sycophant, who undermines your soul while he fans your vanity; and +observe, while we are on the subject, that this species has always had +the art of insinuating itself among princes. + +ORDER 4. _Carnivora (flesh-eaters)_. + +When translated into English, this word needs no explanation. And here +we have the tribe of bears, wolves, foxes, weasels, dogs, cats, tigers, +lions, of all the fighting animals, _i.e._, those which steep +their muzzles in blood, and live by devouring others. These have a +similar apparatus for nutrition to our own; especially the bear, who, +with the monkey, is the animal most nearly resembling man, seeing that +he has feet like ours, with scarcely any tail, while the monkey has +our hands, without specifying any other points of resemblance. Like +ourselves, too, the bear is omnivorous; that is to say, it eats +everything, vegetables and fruit as well as meat; and nature, which +has given it our diet, has furnished it with molars almost exactly +like our own. Its canine teeth alone differ from ours: they are more +prominent even than those of the _quadrumana_; and this is the +case with all the members of the order, in whom we find them sometimes +developed into actual daggers. But those of them which are purely +carnivorous have molars peculiar to themselves. The lion, for example, +who does not share the bear's taste for carrots, and who would die of +hunger surrounded by the honey and grapes of which the bear is so +fond--the lion, who never takes anything but raw meat between his +teeth, has molars furnished with sharp cutting edges, intended to slice +the meat like the chopping knives used by cooks for making a hash. + +The lion offers another peculiarity, which is common to him with all +the _Carnivora_. Place your finger close to the lower end of your +ear, and work your jaw; you will feel something hard moving backward +and forward against your finger. This is where the lower jaw is set +into a bone of the skull, called the _temporal_, if you care to know its +name; in other words, the bone of the temple. The extremity of the jaw +bends, and forms a kind of little knob, called _condyle_, which fits +into a cavity of the temporal bone. With us the cavity is not very deep, +nor the knob very large, so that it can play very freely; and it is this +which allows us that second movement from side to side, of which I spoke +to you formerly, and thanks to which, our little mills reduce a mouthful +of bread into paste. But this freedom of action has also its +inconveniences. You must never attempt to force too large an article +into your mouth at once--an apple, for instance--the efforts you would +then be obliged to make might easily cause the _condyle_ to slip out of +its little cavity, where its hold is but slight, and to get under the +_temporal bone_; and there you would be with your mouth wide open until +the doctor arrived. The lion, whose voracious jaw opens like the door of +an oven, so that the tamers of wild beasts have no scruple in thrusting +in their whole heads, a mouthful a good deal larger than an apple; the +lion, who has no doctors, would often be liable to this accident--an +irremediable one in his case--if nature had not made a special provision +for him. In order to secure greater firmness and strength, the second +movement is in his case sacrificed by embedding the _condyles_ +deeply in their cavities, where they are fastened in such a fashion +that they can only move up and down, like the handles of a pair of +pincers. This is a restraint which enables the jaw to be safely thrown +open as wide as the fiery impulse of its terrible proprietor impels +it. Less freedom, in exchange for more power, is a bargain which any +one would gladly accept who plays the part of a lion! + +I have here a remark to make. We have now passed in review three orders +besides our own, and have only had to point out a change in the +fastenings of the jaws and in the teeth; and you will find that the +same sort of modifications take place in the whole class of mammals. +This is in fact the essentially movable and variable point in their +apparatus for nutrition. The jaw and its weapons vary their character +from one species to another, according to the nature of their food; +but the modifications generally terminate there, _i.e._ on the +threshold, as it were. The interior arrangements of the house remain +otherwise much the same in all. + +Here, however, in the lion, there is an interior change to be described; +but not in the arrangement of the parts, only in their size; the stomach +in this species being even smaller and weaker in proportion than ours, +and the digestive tube more than twice as short. The digestive tube +of an ordinary sized man is about seven times the length of his body, +whilst that of the lion only measures three times the length of the +animal. This is a natural consequence of the kind of nourishment he +takes. Flesh and blood, on which he lives entirely, is concentrated +_albumen_, prepared beforehand in the bodies of his victims; so +that no great preparation is needed here to convert it into lion's +blood. A professor of chemistry, who has a good assistant, does not +need a very large laboratory. This is the case with the lion; and +nature, which makes nothing in vain, has here economised space. Tame +the monarch of the forest into a domestic animal, and change his food, +and I will wager anything you please that, in the course of a few +generations, his digestive tube will lengthen itself. Examine the +inside of the cat, his little cousin, formed originally on the same +pattern as himself, and, without having ascertained the fact myself, +I am sure that, by dint of feeding it daily on sops and milk from +generation to generation, its digestive tube has become more than three +times the length of its body. + +Here you ought to be told at once a very important fact relative to +the organization of the lower animals, one which places them all very +far below the order of _Bimana_, since there is such an order. +In bestowing intelligence and freedom of action on man, the Almighty +has given him the unspeakable privilege of working in His footsteps--if +I may presume to use the expression--of following up His work of +creation as it came from His hand. Now especially that man begins to +see a little more clearly into the laws of life, he has entered more +directly into the possession of this almost divine privilege, which +the Almighty has graciously vouchsafed him. You can even now have an +ox or a sheep made to order in England, giving your dimensions, as if +you were ordering a cabinet; and in a few years, if you have not asked +actual impossibilities, your commission will be executed to within an +inch. This is not said in reference to the _Carnivora_. But in +bidding you good-bye, my dear little mammal, I could not bear to leave +you under the weight of that debasing title: I wanted also to show you +your greatness. + + + +LETTER XXXI. + +MAMMALIA. _(Mammals)--continued_. + +Let us continue to pass in review the different orders of the class +Mammalia. We may meet elsewhere with facts more important to science, +but nowhere with any so personally interesting to ourselves. + +ORDER 5. _Insectivora (insect-eaters)_. + +This order devours insects, as their name tells you plainly enough. +They feed in the same manner as the bats; consequently they have molars +like theirs, as was necessary. It is an unimportant little family, and +we will not waste much time upon it. The chief of the order is the +hedgehog, a native of our country--not very large, about nine inches +long--which lives in the woods, and which when rolled up into a ball, +with all its quills standing out, looks very much like an enormous +horse-chestnut in its shell. Its canines have not much work to do, +consequently they are very small; but, on the other hand, its two front +incisors are prolonged beyond the others, the better to seize its prey, +which creeps upon the ground. Internally there is nothing to remark +upon. + +Next to the hedgehog I will mention as a curiosity the shrew or +sand-mouse, which, in spite of its name, is no mouse at all, but has +the honor, if honor it be, of being the smallest animal known of the +class Mammalia. + +It is about two inches in length altogether; and if you carefully +examine its little body, you will find that it contains all the organs +you possess yourself--oesophagus, stomach, liver, intestines, veins, +arteries, heart, lungs--nothing is wanting: the machinery is absolutely +the same. + +ORDER 6. _Rodentia (rodents)_. + +Were we to translate this word into its meaning, namely, the _Gnawers_, +there would be some comfort in it, for we would at once know what it +means: but no matter. Rodents, or Gnawers, are rats, hares, rabbits, +beavers, marmosets, squirrels, in fact all the creatures which _nibble_. +To _nibble_, if you do not exactly understand the word, means to chew +with the points of the teeth. The rodents have no other way of eating +but by filing, if one may so say, their food with the points of two +incisors with which both the jaws are provided; these incisors are very +long, much longer even than those of the hedgehog. The next time you see +a rabbit at table, ask to see the head; and you will find that it has +four pretty little teeth, very sharp, shaped like a joiner's chisel; +that is to say, with a "bevelled edge," to use the received expression; +in other words, with one edge thinner than the other. + +Here, then, we begin to diverge from the old model. First, there is a +different fastening, or _articulation_, as it is called, of the jaw. Its +_condyles_, which we saw just now in the _Carnivora_ enlarged +transversely and deeply embedded in the _fossae_ or cavity of the +temporal bone, extend here longitudinally; an arrangement which enables +the jaw to move backward and forward at pleasure, like the arm of the +locksmith when using the file. Furthermore, those little teeth, which +are constantly rubbing against each other, would be very soon worn out, +if, like our own, they were made once for all; accordingly their germ, +or _pulp_, to use the proper term, instead of perishing, as with us, +when the tooth has once come, retains its life, and works on throughout +the life of the animal. They sometimes say of a man who has not eaten +for a long while, that his teeth have grown long. This is a joke with +us; but in the case of a _rodent_ would be too serious a matter to be a +joke; for, as their incisors are always growing, like our nails, they +would soon become too long if the animal ceased for any length of time +to wear them down by eating. It is for this reason that rats and mice +have such incessant appetites, and that with them "all is fish that +comes to the net;" old books, rags, and even planks of wood, which they +will gnaw for want of something better. Come what may, they must keep up +at an equal rate the wear and tear of the incisors, and the internal +growth of the pulp beneath, which is always pushing the tooth forward. +This dull continuous work might otherwise have a terrible result, which +you would never suspect. It is very disastrous for a young lady to lose +a front tooth, as it is called, for it sadly spoils a pretty face; but +for a _rodent_ such a loss is much worse; in fact, it is a death- +warrant. The corresponding tooth, having no longer anything to rub +against, ceases to wear out; and as it does not stop growing on this +account, it lengthens indefinitely, until at last it pushes out beyond +the mouth, and places itself like a bar between the two Remaining teeth +and the food of the animal, who, poor beast, being unable to eat, +ceases to live. + +The canines, whose duty it is to pierce the food, have, of course, no +use in a jaw that grinds, nor are they to be found there. Between the +incisors and the molars there is a large vacant space, which you will +easily detect if you examine a rabbit's head. + +Finally, animals which can fall back in time of need on a plank for +their dinner, require a very different-sized cooking apparatus to that +of the _Carnivora_. Thus the rat, the most perfect sample of the +rodent order, possesses a digestive tube of a prodigious length, through +which the scrapings of wood have plenty of time for travelling, while +the minute nutritive particles they contain are being thoroughly +disengaged; and as every part of the animal organization tends towards +keeping our insatiable rodents in the constant state of voracity +required by its inexorable pulps, nature has given it an enormous heart +whose size exceeds even that of its stomach. + +Perhaps you do not catch at once the connection which exists between +the size of the heart and of the appetite; yet it is very simple. Large +barrels are requisite for those who brew a great deal of beer, and +large hearts for those who make a great deal of blood. Now, it is the +blood, as you know, which carries heat; in other words, life, throughout +the body; when it pours in in torrents, the fire goes twice as fast, +and, consequently, the feeding must be kept up. A medical friend of +mine told me that he once had some rats sent to him--a boxful in +fact--for one of those scientific experiments which one would venture +to condemn more earnestly if their results were not sometimes +beneficial. Next morning there were only two or three animals to be +found, and these had eaten up the others. See the consequence of having +too much heart! + +ORDER 7. _Pachydermata (thick-skinned)_. + +In Greek _pachus_ means thick, and _derma_ skin. _Pachyderms_, +therefore, are thick-skinned animals. It is rather a vague denomination, +as you perceive, and does not tell us much about them; but it appears +that it was not very easy to find a better term. For my own part I +should be very much puzzled to find a name really suitable for such an +irregular company as this, in which all the huge beasts of the +earth--the elephant, the rhinoceros, the hippopotamus--are heaped one +upon the other, side by side with the horse, the ass, and the hog; +begging your pardon for an ugly word. + +All these creatures live on vegetables, with the exception of the hog, +to whom nothing comes amiss; or who, in other words, is _omnivorous_, +like the bear, and also another member of the class _Mammalia_, which I +do not name for fear of making you blush at your companionship. This +assures you that, in the order of the _Pachydermata_, the digestive +apparatus is very fully developed. The horse, for instance, has a very +voluminous stomach, which extends much farther back than the point at +which the oesophagus empties itself; and in which, on close examination, +a sort of contraction is observed which appears to divide it in half, +producing the false effect of there being two stomachs. But, after all, +we do not find, even in this case, any essential difference to remark +upon in the internal arrangements; it is always the teeth we must look +at if we want to have something to say. There, indeed, we have only to +choose; nature has indulged herself in all manner of fantastic freaks. + +To begin with the elephant, the grand master of the order, he presents +us with one of the most oddly-furnished jaws in existence. Every one +knows those two enormous tusks which protrude from his mouth, and which +furnish human industry with nearly the whole store of ivory it has +need of. Those two teeth are the largest, beyond comparison, of any +in the animal kingdom; yet they are two merely ornamental teeth, +perfectly useless in the operation of eating, and very ruinous into +the bargain to the proprietor. All those stores of the blood which +furnish the materials for ivory pass into these tusks, and, as often +happens to people who give way to a taste for luxuries, there is nothing +left wherewith to provide the animal with serviceable teeth. Those +tusks of the elephant are nothing but his upper incisors, the only +ones, observe, which curve in coming out of his jaw. In the lower jaw +he has no incisors at all; canine teeth are entirely wanting; and by +way of dental apparatus, this meagerly-furnished mouth possesses on +each side of either jaw one or two molars, enormous in size, but not +of ivory. They are composed of a number of enamelled upright layers +of tooth-substance (_dentine_), soldered together with a bony +cement; and these are our giant's only resource for chewing the grass, +young shoots, and leaves of trees, which are his natural food. +[Footnote: These teeth are nevertheless very efficient grindstones.] +As a consolation, he has the glory of knowing that he possesses the +very finest teeth in the world, the terror of all who approach him; +and I can compare him to nothing so well as to a vain woman, who is +contented to live on potatoes that she may wear fine clothes and excite +the envy of her neighbors. + +The hippopotamus also has incisors in the upper jaw, which curve as +they come out of the mouth; but these never attain anything like the +size of the elephant's tusks, neither do they hinder the development +of the other teeth, of which this animal has a very respectable +collection. The upper incisors bend downward; those in the lower jaw +stand out horizontally, and terminate in sharp points like +plough-shares; and indeed the hippopotamus uses them for tearing up +the ground in order to get at the roots which form its nutriment. These +are, besides, formidable weapons, with which when enraged the animal +can tear even boats in pieces; for, as you are aware, the hippopotamus +is almost amphibious, and browses on water-plants, and lives in the +great rivers of Africa, its native country. Its name alone would have +told you this had you understood Greek; [Footnote: _Ippos_, a horse, and +_potamos_, a river. The Greeks, who had seen the hippopotamus in the +Nile, in Egypt, named it the river-horse; as afterwards the Romans +called the elephant the ox of Lucania, because they first saw it in +Lucania during the war with Pyrrhus.] but I have no complaint to make +this time, for it was the Greeks themselves who gave it. You would find +it very awkward, would you not? if you had to breakfast at the bottom of +the Thames, and could not swallow a morsel without having your nose +filled with water? But the hippopotamus labors under no such +inconvenience. Its nostrils are provided with two little doors, which it +closes at will, and behind this screen the lungs keep quite quiet while +the animal goes backwards and forwards in the water. There is generally +a hippopotamus in every large menagerie. The next time you visit one +look at him. You will see him with a large stomach almost trailing on +the ground: and no wonder; he needs plenty of room in which to stow away +all the canes, reeds, and water-plants from the bottoms of rivers, which +are not very nutritious food. Accordingly the stomach of the river-horse +presents the appearance not only of two compartments, like that of the +true horse, but looks as if it were divided into three or four. + +To conclude my account of this animal, I must add that the ivory of +its teeth is even more beautiful than that of the elephant's tusks, +and that dentists carve it into very magnificent teeth for their +patients. This is not a matter to interest you much at present, but +we never know what may happen. I advise you, however, never to make +use of hippopotamus's teeth; they turn yellow very quickly, and, when +people are driven to buy teeth, the least they can try for, is to get +good-looking ones for their money. + +I should like to say something about the rhinoceros while we are on +the colossal tribes, but it is a very unsatisfactory subject. The +animal has no canines, sometimes no incisors even; sometimes it has +as many as thirty-six teeth, according to the species, as naturalists +aver; and this is all I have to say about this great lump of flesh, +so misshapen outside, yet so regularly formed within. He it is who +especially deserves the title _pachydermata_, his skin being so +hard and thick that bullets glance off its surface. But this has nothing +to do with our present subject, any more than the horn upon his nose, +whose turn for description may come if I ever give you the history of +the skin and all connected with it. + +The hog also has canines, and very strong ones; but it is in the wild +state, when it is called a boar, that these appear in their real form. +There we find them projecting out of the mouth with a curve, as is so +commonly seen among the _pachydermata_, forming those terrible, +sharp, and pointed tusks which have been so often fatal to the hunter. +The wild boar of the forest is supposed to be the original ancestor +of the domestic pig; and if, as is probable, this is really the case, +we have here a remarkable instance of the effect of man's treatment +upon the organisation of the animals he collects around him. The wild +boar lives only on fruits and roots, which, like the hippopotamus, he +tears up with his tusks, those safeguards of his, amid the many perils +of his life in the woods. In the service of man, on the contrary, he +becomes lazy, cowardly, and greedy; unlearns his energy and +combativeness, eats all that is offered to him in the trough, even +meat, when it happens to be thrown in; and, in order to do this +moreeasily, has recalled toward his mouth those formidable war-tusks of +his, so tremendous as weapons, so useless as teeth; has, in fact, +turned his sword into a fork. It is the case of a Tartar degenerated +into a Chinaman. [Footnote: China, about which we have heard a great +deal of late years, has been several times invaded by the warrior +hordes of Tartary. But at each time, unto the second and third +generations, the vanquishers have taken the effeminate manners, the +costume and the usages of the vanquished, and so many conquests have +only resulted in converting millions of Tartars into Chinese.] + +This suggests to me an idea relative to the horse, the last important +member of the _pachydermata_ which remains to be spoken of. It +also has its canines, but very small ones; they disappear, so to speak, +in a large vacancy between the incisors and the molars, where man +inserts the bit, by means of which the animal has been subdued. Small +as these are, however, these canines indicate that the horse might eat +flesh, canine teeth being the distinctive attribute of the carnivorous +mammals. I have read somewhere, but I do not remember where, that an +unusual development of strength could be produced in the horse by +feeding it on flesh; and the old Greek poets write of a king [Footnote: +Diomed, King of Thrace] in the barbarous ages who gave his horses, +men for food. If I knew some rich professor who was inclined to spend +money in the investigation of a curious fact, I would advise him to +set apart a sum for putting horses on a meat diet, from sire to son, +gradually increasing the quantity; and I would boldly warrant that in +the course of successive generations the canines would become so large +as to impede the entrance of the bit into the mouth, and, moreover, +would make it rather a ticklish office for the groom to place it there. +But let us set aside the teeth the horse might possibly have, in order +to examine those it has already. There are six incisors in each jaw; +these are long and rather projecting teeth, by examining which, the +age of the horse can be detected from certain marks which appear in +them from year to year. The molars are flat, square, furrowed with +bars of enamel, marking out more or less distinct crescents; perfectly +constructed, in short, for chewing hay and oats. Nevertheless, I should +never be surprised to see the enamel crescents become sharp-cutting +in our rich professor's stable; so skillful is the unseen Architect +who created animals, in altering the house when the tenant changes his +habits. + +ORDER 8. _Ruminantia (ruminants)._ + +I shall retain through life a pleasant recollection of the +_ruminants_. Through them I obtained the first prize for natural +history which was ever given in France to the pupils of the learned +university. It is thirty years ago since this happened, and I own, +without any false modesty, that even now the word _ruminant_ rings +very agreeably in my ear. It reminds me of one of the proudest moments +of my life, of the honor done to me by the illustrious Geoffroy St. +Hilaire, when he called me, a little college urchin, up to him, that +he might have a nearer view, as he said, of the baby-professor who had +spoken so well on ruminants. Yes, it is more than thirty years ago, for +alas! it was in 1831. There needed no less an event, as I have told +you before, than the revolution of 1830 in France to induce the big-wigs +of education to sacrifice two hours per week in one class to the study +of natural history. Yes, my dear child, it is only that short time ago +since natural history became one of the subjects of study in French +colleges; and the gray-haired men of the present day finished their +education, as it is called, without having learnt a single word of +what I am now taking the trouble to teach you, a mere child. You see +you have come into the world just at the right time, and will be able +to instruct others in your turn. But before giving lessons to other +people you must first finish learning your own. Forgive me this +involuntary reference to a happy time when I was not much more rational +than you are. And now, let us return to our ruminants--those dear, +good beasts, the nourishing fathers of the human race. + + + +LETTER XXXII. + +MAMMALIA--_continued_. + +ORDER 8. _Ruminants--continued_. + +Every created thing has an appointed part to perform; but there are +some mysterious parts of which we cannot understand the drift. That +of the ruminants, however, is so clearly marked out, that we detect +it at a glance. + +To qualify myself for supplying your young mind with the food I am +going to offer it to-day, I have been obliged, my dear child, to browse +in a good many books of which you could have understood but little +yourself; and I have been forced to ruminate a long time upon what I +have read, and to digest it slowly in my head, which I may say, without +vanity, is of larger capacity than yours; no great wonder at my age. +Now, if I have succeeded in my undertaking, you will benefit by all +the work which has been going on in my mind for the purpose of feeding +yours without over-fatigue to it; and I shall almost have the right +to say that its nourishment has been derived from me. My lamp could +tell you what it has sometimes cost me to supply a single page which +might instruct, without repelling you. + +Now, this is precisely what the _ruminant_ does. The part he has +to perform is to collect in the meadows a sort of food, which would +disgust less well-organized stomachs than his own, to work it well up +within him, and to give it back in a more palatable and less +indigestible form. The little flesh-eaters (_carnivora_) come +afterwards to the feast, and the feast is himself! + +The whole history, then, of the ruminant is to be read in his stomach. +His real office is to digest, and in fact he devotes the best hours +of his days to the perfecting of that beneficent labor, on which the +life of so many weak stomachs depends. Have you ever amused yourself +by watching a large ox lying down in a meadow? Long after he has +finished grazing, his jaw continues to work, turning round and round +like the grindstone of a painter when he is rubbing down his colors. +Look, and you will see that he will remain there for hours together, +motionless and contemplative, absorbed in this incomprehensible +mastication, rolling about in his throat from time to time some +invisible food. Do not laugh at him, however. As you sec him there he +is performing his part in life, he is _ruminating_. + +To ruminate is to chew over again what has been already swallowed; +and, however droll this may seem to you, it is the business which all +ruminants are born to. You remember the monkey's pouch, which serves +him as a larder, whence he takes out his provisions as he wants to +eat. The ruminant has an immense pouch of the same kind, into which, +while he is grazing, he hastily conveys large masses of half-bitten +grass. You probably think he is eating when he has his head down in +the grass; but you are mistaken. This is only a preparatory work; he +is hastily heaping up in his larder the food he intends to eat +by-and-by; only his larder, instead of being, like the monkey's, in +his cheeks, where, indeed, there would not have been half room enough +for those great bundles he tucks in, is in the middle of his body, +close to the extremity of the oesophagus, whose lower wall, being slit +at that part, becomes an imperfectly secure tube, ready to burst open +under pressure, and allow the food to escape between the edges of the +slit; these, otherwise, remaining naturally closed. As soon as the +large bundles of grass come to this part, they press against the walls +of the tube, which they by this means separate, and fall into the +provision-pouch, which bears the name of paunch, or grass-pocket, in +fact. As soon as the paunch is well filled, and the animal sure of his +dinner, he lies down in some quiet corner, where he proceeds gravely +with the important act, which is the real object of his existence. A +little below the entrance to the paunch, and communicating both with +it and the canal of the oesophagus, is a second receptacle, which old +French naturalists, not being much acquainted with Greek, named the +_cap_, on account of its fancied resemblance to the caps worn on +the head, and which we call 'king's hood' or 'honey-comb bag.' This +second stomach now contracts (at least so it is supposed), and thus +retains, as if with a closed fist, a portion of the grass accumulated +in the paunch: of this it forms a pellet, which it sends back into the +oesophagus, and the oesophagus, by continued contractions from below +upwards, returns it to the mouth, where at last the grassy lump is +chewed in good earnest, and to some purpose. There is no necessity for +hurry; the ruminant has no other business on the face of the earth but +this, and thus hour after hour passes away, the food pellets rising +one after another to the onslaught of the teeth. Nor do they go back +again until they have been reduced by long mastication into an almost +liquid paste, which glides through the oesophagus without forcing open +the slit, and falls straight into a third pouch, called by old Frenchmen +the _leaf_, on account of certain large folds, some what like the leaves +of a book, which line the interior; and known to us as the _manyplies_. +From this stomach, No. 3, this grass-pap passes into a fourth and last +bag, which is the real stomach, and where the final work of digestion is +accomplished. This fourth pouch also has a pretty little name of the +old-fashioned sort, like the three others; it is called the _reed_ or +_rennet-bag_, from the property it possesses, in the calf, of turning +milk into curds: and of his four stomachs this is the only one which the +ruminant makes use of at first. As long as the young animal is nursed by +its mother, the other compartments remain inactive and small in size; +they neither grow nor exercise their functions until it begins to eat +grass. Indeed, they would probably entirely disappear, if any one would +go to the expense of keeping the animal on milk all its life. If it +ceased to have anything to ruminate, nature would certainly lose no time +in relieving it of its useless workshop of rumination. + +As it is right to give every one his due, I will mention that we owe +our accurate knowledge of this simple and ingenious mechanism of +_rumination_ to the labors of Flourens, a scientific Frenchman, +who is still alive, and who has made a great many interesting inquiries +into the subject we are now considering, _i. e._, the life of +animals. He is a very clever man into the bargain--so perfect a master +of his own language, that the French Academy has felt itself justified +in opening its doors to him--an unheard-of honor for a member of the +Academy of Sciences. And yet, in spite of all this, I heartily +congratulate you that the discovery of the _paunch_, the _cap_, the +_leaf_, and the _rennet-bag_, was not delayed for his arrival. He is +just the man who might have been tempted, in his capacity of profound +scholar, to have hunted up for them in the _Jardin des racines grecques_ +[Footnote: Your brother can tell you about the _Jardin des racines +grecques_. It is a charming little book, of which every generation of +collegians has learnt, by heart, the commencement; but I have never +known one, even among the most intrepid, who had ever been to the end of +it.], four magnificent names, which would only have bewildered you. + +Beyond the rennet-bag there is no change of conformation to note, +except that the intestinal tube is naturally much longer than ours, +on account of the difference of food: as a general rule, it is ten or +twelve times the length of the body. The sheep, who is able to pick +up a living in the poorest pastures, is indebted for this inestimable +power, which makes him the special blessing of dry and barren countries, +to a still further peculiarity of organization; with him the intestinal +tube is twenty-eight times the length of the body. + +We have seen among the _Carnivora_, whose jaws have so much work +to do, that the condyles of the jawbone are sunk deeply into the fossa +of the temporal bone. The ruminant, whose peaceful mouth is formed for +contending only with grass, is organized quite differently. + +Here the condyle is flattened, and the fossa of the temporal bone very +shallow, presenting to the condyle an almost flat surface, so that the +jawbone is enabled to revolve with ease for the better mastication of +the pellets of grass. This conformation is also to be seen in the +_pachydermata_ who feed upon vegetables. In the horse, especially, +whose food is almost the same as that of the ox, the _articulation_ +(as this joining of the condyle to the temporal bone is called) of the +jaw, is also nearly identical; and it is the same with the teeth, with +very trifling variations, those of all ruminants are constructed on +the same plan as in the horse. The canines only require a separate +notice. + +But first I must tell you that, by some special privilege, the reason +for which I do not undertake to explain, the order of ruminants is the +only one containing animals with horns on their foreheads. Stags, +goats, reindeer, chamois, gazelles, roebucks, oxen, buffaloes, all the +beasts with horned foreheads, belong to the ruminants. Indeed, this +fact would form a very convenient mark of distinction between them and +other animals, were there not exceptions to it. Some ruminants have +no horns; and then, as if in compensation for the deficiency, we find +them provided with canines in the upper jaw, in addition to those +below. + +The ruminant which has the most beautiful canines is the musk-deer, +a pretty little animal inhabiting the highlands of Central Asia, like +the chamois of the Alps. But now that you know who he is, you will +probably often be tempted to wish he had never existed; for it is from +a small pouch below his belly that people obtain that odious musk of +which Oriental beauties are so fond, and which even certain +strong-nerved ladies of our own country are guilty of using in public, +to the great detriment of general health. But enough of this; our +business is with the canines of the musk-deer. They project with a +descending curve from the upper jaw, and would give the animal the +very false appearance of a small wild boar, but for the great delicacy +of its legs, which are more slender than even those of our roebuck, +to whom, with the exception of the horns, it bears a close resemblance, +as its name implies. + +After the musk-deer comes the large family of camels and llamas, which +represent--the former in Asia and Africa, the latter in America--the +irregular groups of ruminants which have canines instead of horns, and +which seem to be placed as intermediates between true ruminants and +the pachydermata. They form the connecting link between the horse and +the ox, and men prefer employing them as beasts of burden to using +them as butcher's meat; though one could eat them in their own country +with less disgust than Europeans feel in making a meal of horseflesh; +so that they might be a very acceptable resource in many cases. The +real fact is, that ruminants with horns and without upper canines have +more delicate flesh than the others, and seem more especially destined +to be eaten. Yet if one had only to look at the stomach, which is, +after all, the distinctive characteristic of the order, camels and +llamas would stand in the first rank as ruminants. Besides the usual +character of four stomachs, their paunch and honeycomb-bag are furnished +with large cells which act as reservoirs, and fill with water whenever +the animal has the chance of drinking freely, and from whence in time +of drought he draws it up into his mouth and swallows it. This is what +makes the camel so valuable to the wandering tribes in the great deserts +of Africa and Asia. He is the only animal who can pass several days +under the burning sun of Sahara without drinking--or rather without +appearing to do so--for he carries his provision of water concealed +from all eyes in the recesses of his body. I dare say you have often +heard stories of Arabs dying of thirst who have opened the stomachs +of their camels in search of a last draught of water. It must be a +terrible thirst to drive a man to such an extremity; for, as you may +imagine, one could not expect the water there to be either fresh or +clear, to say nothing of the great risk there would generally be of +finding the reservoir empty. Such an extreme is never resorted to till +water has failed for a long time, and all the goatskin bottles have +been emptied; and in such a ease it is but too likely that the camel +has followed his master's example, and emptied his water-skins for his +own use. But this is only half the internal fittings of the "ship of +the desert," as the Arabs call him. In the desert it is often as +difficult to find food as water; and nature has equally provided for +this. The hump you see rising upon the camel's back in your +picture-books is his safeguard against starvation. It is a huge mass +of fat. I need say no more. You will remember Mr. Liebeg's pig, which +lived 160 days upon its own bacon. Without going quite such lengths +as that, the camel can keep up his fire for a long time upon the fuel +which the blood obtains from this blessed hump. Since we are talking +of this animal, and he takes a remarkable place in a history of +nutrition, I ought to tell you that camels are classed into two families +by their hump: there is the camel, properly so called, which has two +humps, and the dromedary, which has but one. This latter did not require +such a supply of provisions as the other, for he is very much swifter +of foot, and consequently his journeys are more speedily performed. + +I have nothing particular to say to you about the other ruminants, in +the matter of their organs of nutrition; but I will not quit the subject +without reminding you of one thing which concerns nutrition, not theirs, +however, but ours. It was by the taming of the domestic ruminants--that +unfailing dinner-material which now follows everywhere at the heels +of his master--that human civilisation began. Before that event, man, +driven to depend for his living upon the hazards of the chase, spent +his whole time in seeking for food, and had none to spare for the +pursuit of any other branch of industry. + +Far as we may ascend in the history of ages we shall find shepherd +races. Beyond them there is no history at all, nor could there be. The +first leisure hours of man, and, consequently, his first efforts in +art and literature, date from the period when the ruminant animals, +those special fabricators of nutritive aliments, were gathered around +mankind, and worked out their destiny under the shadow of his tent, +by his direction, and for his benefit. But all this is so distant from +us now, that it is scarcely worth the trouble of thinking about. The +human race is somewhat like those old people who have lost all +recollection of their childhood; and young people are not required to +know what their elders have forgotten. It is well, however, that they +should not be quite ignorant on the subject. When you hear that the +Society for the Prevention of Cruelty to Animals has taken up the cause +of some barbarously-used ox or sheep, do not turn it into ridicule. +Those humble species have supported ours from the first; and you should +recollect, now and then, that human society made its first step forward +when it began to keep flocks and herds. + + + +LETTER XXXIII. + +MAMMALIA--_continued_. + +We come now to animals less familiar to you, and none of which inhabit +Europe. We shall therefore pass more quickly over them. + +ORDER 9. _Marsupialia (pouched)_. + +_Marsupium_ is Latin for purse, pouch, or pocket. The marsupials +are distinguished from other animals by a pouch which the mother has +under her belly, and in which the little ones take refuge at the +slightest alarm. You would be very much interested with their whole +story; but it has nothing to do with our present subject, which we +should soon lose sight of if we once began to wander away. This order, +so easily distinguished otherwise by that singular pouch, unfortunately +for us, offers nothing new for observation. It includes several species, +differing entirely from one another on the subject of nutrition, and +closely resembling some already described. Some are both carnivorous +and insectivorous, and are therefore armed with powerful canines, and +with molars like those of the hedgehog. Others are herbivorous, like +hares, and have almost the jaws of a rodent. Among the former we have +the opossum, celebrated by Florian in one of his prettiest fables. The +opossum inhabits South America. Charming little marsupials are to be +found in the Molucca Isles, whence come the nutmeg and the clove; these +are very like our squirrels, and live as they do, in trees, hunting +after fruit and insects. But the greatest number of marsupials belong +to Australia, the real native land of the order. They form by far the +larger portion of the mammalia with which that country is enriched; +the most celebrated amongst them being the kangaroo; an animal which +is now becoming common in European menageries, and which, excepting +in the matter of its pouch, is nothing but a magnified rabbit, as tall +as a man, and with a tail almost as long as itself. As a rabbit, you +know what its eating apparatus must be; and some day, no doubt, the +French Acclimatisation Society will enable us to judge of its flavor. +It is a kind of meat very likely to be seen on our dinner-tables +by-and-by; and, as you have plenty of time before you, probably you +may eat of it before you die. + +ORDER 10. _Edentata (toothless)_. + +These come more directly within our limits. They are classed according +to their teeth; yet if their name were to be trusted, they ought to +have no teeth at all. Whereas, alas! almost all of them have some, and +I am heartily ashamed of their scientific designation; but how can we +help it? The only really _Edentata, i. e_. toothless animals, amongst +them are the ant-eaters, who, considering the nature of their food, are +not much in want of teeth. They feed among the ant-hills, whence they +get their name; and as they are a tolerable size (from two to three feet +in length), it would really have been quite a hardship upon them to have +been forced to crunch the ants one by one at every meal. To get on +rapidly they catch them with their tongue; but what a tongue! Imagine a +kind of long earthworm, lodged in a snout which is elongated like a +bird's beak, and has a very small opening at the extremity. The ant +eater inserts this long, string-like tongue into the crowded ranks of +its victims, and, as its surface is glutinous, they stick to it by +hundreds at a time, and are swallowed at one gulp without a chance of +escape. This tongue, perfectly unique in its character, stretches out in +its murderous exertions to nearly three times the length of the animal's +long head. What a distance there seems between such a tongue as this and +your own little doorkeeper! But no wonder: we have now reached the +confines of the kingdom of _Mammalia,_ and the face of nature is +beginning to change. + +The Armadillo, for instance, which comes next to the ant-eater, looks +far more like the tortoise or lizard than its noble mammalian brethren. +It is covered with scales; and, to look at it, you would say it was +a reptile, in spite of its higher internal organization. As for teeth, +it has certainly enough of them to give the lie to its name of +_edentata;_ but they are not very serviceable ones. They are called +molars, however, because they are situated in that part of the mouth +which is always assigned to molars; but they are miserable grindstones, +very unlike any of which we have hitherto treated. They are all of them +flattened cylinders, with no enamel bars to strengthen them; are small +and poor, and are placed at rather wide intervals from one another. The +poor armadillo munches with these, as best he can, slugs, tender roots, +and other prey of the same sort, with which he is obliged to content +himself, and which do not require very formidable tools. + +The most questionable member of this class is the Unau, or Two-toed +Sloth. It only wants incisors to be as toothless as ourselves! and the +first time I saw it I took it for a little bear. It is true I was then +younger than you are now; for the bear, who is one of our nearest +neighbors, ought not to have been confounded with the unhappy being +before us, one of the drudges of the animal creation; though M. de +Blainville (who had not my excuse) proposed placing it still nearer +to us, namely, amongst the _Quadrumana_. Observe that instead of hands +it has at the end of its fore-limbs only two enormously curved claws, +which have somewhat the appearance of a gigantic fork accidentally +twisted. Accordingly its illustrious sponsor offered it to the world as +an _irregular quadrumane_. I believe so, indeed! This _quadrumane_ +without hands--this _edentate_ whose molars are preceded by magnificent +canines--this enigma of nature, created for the confusion and despair of +all classification--does, I must in all humility confess, completely +upset the rule I laid down so stringently when speaking of the horse, as +to the objects for which canine teeth were framed. The canine teeth of +the sloth are more developed than its molars, and yet I cannot tell you +what they are there for at all. It feeds upon the leaves of trees; and +old travellers in South America, where it inhabits, have told us that, +when it has once hoisted itself up a tree, it will strip it to its last +leaf, and afterwards drop to the ground to avoid the trouble of crawling +down. This was what first obtained for it the villanous name of sloth, a +title which is certainly justified by its gait when on the ground; for +it is so ill-made that it cannot stand upright on its legs, but moves +clumsily forward by dragging itself on its elbows. It seems, however, +that when once in a tree it is a different creature altogether, and +can scramble lightly from branch to branch. Moreover, if its claws +cannot reasonably be reckoned as hands, they are at all events excellent +hooks; and when it is springing about thus in the forest, suspended +to the branches by its long arms, one might be tempted, while watching +it from below, to decide in favor of M. de Blainville's opinion. I saw +it originally myself in a cage. + +As to the sloth's relationship to the armadillo, this rests upon a +detail which bears directly upon our subject. The molars in both animals +are cylindrical and smooth, this is a trifle, but what would you have? +The animal had to be classed somehow; since naturalists have not had +the wit to make detached companies, as they do in regiments of soldiers. +ORDER 11. _Amphibia (two-lived)_. + +We are going farther and farther away. Here are animals who are nearly +half fishes (_amphis_, _double_, and _bios_,_life_). The _Amphibia_ have +two lives: one in the water, which is their true life, and where they +are in their element; the other upon land, where they can only crawl; +for their paws, which are but half developed, are destined to perform +the office of fins, and the hinder ones are extended flatly behind them, +and act like a fish's tail. They are divided into two families, the seal +and the walrus. The first feed on fish, and have the same internal +organization as the _Carnivora_, as well as the same dental +conformation. Some species have even exactly thirty-two teeth, as we +have. The jaw of the walrus is the least regular, and the incisors are +generally wanting, especially in the full-grown animal; for it appears +they lose them very young, as you lost your milk teeth, only, unluckily +for the walrus, his never grow again. On the other hand, he has two +canines in his upper jaw, which, next to the elephant's tusks, are the +largest we have yet met with. They are sometimes as much as two feet +long, and incline downwards with a curve, like the two bars of a pick- +axe. They would play the walrus the same trick that the incisors of +rodents are apt to do when they have not work enough to wear them down; +that is, stop up the entrance of its mouth, were it not that the lower +jaw is contracted in front, in order to fit into the space between the +two canines, which thus form a sort of passage in which it manoeuvres +freely. As you may suppose, the walrus cannot insert prey of any great +size into this contracted passage; but that is no matter, as he lives +partly on seaweeds, and partly--indeed principally--on shell-fish; his +molars being specially adapted for breaking shells. They are short +massive cylinders--the upper ones fitting into the lower as a pestle +into a mortar. + +After the walrus comes a strange animal which has been ranked among +Cetaceans (we shall see why presently), but which it would be better +not to separate from the Amphibians, since an Amphibian order has been +made, for it crawls from time to time upon land: this is the Manatee, +or Sea-cow. It comes still nearer a fish than the others. Its forelimbs +are absolute fins, with mere vestiges of nails at their edges; it has +no hind ones, and its body, which is quite cylindrical, ends in a fin +tail in the shape of a shovel. The sea-cow feeds on plants and herbage, +and lives at the mouths of great rivers, going up them occasionally +to great distances, their banks serving it for pasture ground. In some +respects it is half brother to the hippopotamus and the great grass +eating _Pachydermata_, to whom it comes so near in internal +organization, and above all in the structure of its molars, that M. +de Blainville seriously proposed ranking it among the elephants, though +as an _irregular elephant_, as you may suppose. But then Cuvier +had even placed the seal among the _Carnivora_, by the side of +the cat, whose whiskers it possessed, and of the dog, whom it resembled +in the formation of its head. A naturalist's office is sometimes very +perplexing, I assure you; and as we are touching on this subject, I +cannot resist telling you that the sea-cow laid claim to, on so many +sides, had by right a free admission to the celebrated order of +_Primates_, although it looks exactly like a large barrel elongated +at the two ends. It suckles its young at the breast like man and the +monkey; and if Linnæus flinched from this rather too absurd parentage, +old navigators were less scrupulous. Observing this creature in the +distance, sporting on the waves, the upper part of its body quite out +of the sea, the sailors, whose eye is not of the most refined, and who +have no objections generally to the marvellous, imagined they saw a +new species of human beings; and hence arose those stories of mermaids +and sirens which have been told from the days of Homer downwards, and +the traditions of which have not yet quite died out in seaport towns. +To have been passed from man to the whale, touching the elephant on +the road, is a long way to travel, especially when, after all, one is +only a huge barrel of amphibious fat; and you may judge from this that +it is not always an easy thing to classify animals. + +ORDER 12. _Cetacea (whale-kind)_. + +Cetaceans are whales; and if I had been consulted on the matter, I +should have joined this order and the last together, under whatever +name was thought most appropriate. The passage from the seal to the +whale through the walrus and the sea-cow is an easy and natural one, +the two latter being obviously the connecting links; and in spite of +certain diversities of food, they form in reality one family-party, +as do the marsupials. + +But it is too late in the day to talk of this, my dear child, and you +and I cannot pretend to alter what is taught in the schools. + +But you are astonished, are you not? to hear that the whale is not a +fish: and no wonder. It is with it, however, as with the armadillo; +it is a fish with a higher organisation inside. The interior of this +enormous mass is a faithful reproduction, as a whole, of that of the +shrew-mouse; and when we come to talk of fishes you will have some +faint idea of the prodigious distance which this places between the +whale and his countrymen of the ocean. + +As far as we are concerned, the chief difference is in their way of +breathing. The cetaceans breathe like ourselves, and are obliged to +come to the surface of the water to take air; while fishes have a +special apparatus, which I will explain to you presently, which enables +them to breathe in the water. This is a disadvantage to the cetacean +in his fish life; nevertheless, of all the mammals (as may easily be +imagined) he is the one who can remain longest under the water. With +us, for instance, the best divers one ever heard of, those who go to +the bottom of the sea after the pearl-oyster, can scarcely stay below +longer than two minutes; and even during that short time the veins of +the head become so overcharged with the blood, which cannot return to +the lungs owing to its forced inactivity, that when the diver comes +back to the surface it is by no means unusual to see him streaming +with blood from both nose and ears. The cetaceans remain under water +for half an hour at a time without seeming to suffer in the least; and +Breschet, a clever French naturalist, has given a very satisfactory +explanation of this wonderful faculty. In dissecting a cetacean, he +discovered all along the vertebral column an extensive network of large +veins, which are not found in other mammals, and which seemed designed +to serve as a refuge place for the blood during the time the animal +remains submerged. According to him, this network would act as a +reservoir, to which any overplus in the head or important organs would +flow through vessels communicating therewith, and which might swell +out as it pleased, without any risk to the inert bed of fat against +which it lies. From thence the blood rushes to the lungs, as soon as +the animal's return to the air enables them to play as usual. It must +be admitted, at the same time, that all this involves the necessity +of a much less active life than that of land mammals, that is to say, +a consumption of oxygen much smaller in proportion than theirs; for +were you to be furnished down your back with the finest network +reservoir in the world for venous blood, it would still not enable you +to remain half an hour without breathing. + +There is nothing remarkable in the digestive apparatus of the cetaceans +except about the mouth, which is, as you know, the essentially variable +point among animals. To begin with, the cetacean tongue has the most +original appearance possible. Indeed, it is not a tongue, but a large +carpet, spread over the floor of the animal's mouth, and bears not the +faintest trace of resemblance to that nimble delicate porter, who does +you such good service. Imagine a thick soft lump absolutely crammed +with fat, and completely immovable, because it is glued down along its +whole length to the bottom of the mouth, and you will have a good idea +of this strange tongue, which in the whale, the largest of the +cetaceans, attains to the length of twenty-five feet and the width of +twelve, and of itself alone furnishes the whale-fishers with from five +to six tons of oil. This is a great deal farther from us than even the +long string which serves as a tongue to the ant-eater; and you feel +at once that we are getting among strangers. + +With respect to teeth, I have now a melancholy piece of news to tell +you. We have done with them; we have seen the last of incisors, canines, +and molars, henceforth you will hear no more about those valuable +instruments. The teeth of the cetaceans, with whom this painful +falling-off begins, are no more teeth than his tongue is a tongue. +They are like so many nails set in a row in the jaw, and can only be +of use in retaining prey, not in grinding it; so that of the many +processes your bit of bread has to go through before it becomes a part +of yourself, there is one which is dispensed with here altogether, +namely, mastication. Cetaceans swallow their food without chewing it. + +Besides, they have not got a whole set even of these unmasticating +teeth. Dolphins and porpoises, those faithful companions of the sailor, +around whose vessel they come playing and tumbling in the seas of all +countries, are the only ones who have them in both jaws. And these are +the small fry of the order; they do not usually exceed six or ten feet +in length. + +The Cachalot, or Spermaceti Whale, an enormous cetacean, which rivals +the true whale in size, and whose head alone forms nearly the half of +its body, has teeth in the lower jaw only. This lower jaw, whose two +sides are joined together for half their length (a new deviation, very +unlike anything we have found before), is so little proportioned to +the gigantic head which contains it, that it is almost lost to sight, +and seems like a small plank slipped under a great square block. + +Such as it is, however, it possesses many very respectable teeth, of +which some weigh as much as two pounds; and with these the cachalot, +whose ferocity is tremendous, tears in pieces everything that comes +near it, sometimes even the boats of the fishermen who risk their lives +in the dangerous pursuit of capturing them. By a singular arrangement, +of which this is the only known instance, there is, opposite each of +the cachalot's teeth, a corresponding cavity in the upper jaw, into +which they fit closely, turning the monster's muzzle into the most +formidable pair of pincers to be found in the animal kingdom. Another +curiosity in the order is the tooth of the Narwhal, a modest cetacean, +who is not much more than twenty feet long! + +I speak of _the tooth_, because the creature has commonly but +one; a cylindrical-pointed tooth, spirally furrowed, whose length +varies from six to ten feet, and which comes straight out from the +extreme front of the upper jaw, like a soldier's pike. There are two +sockets at this extremity of the jaw, each furnished with a tooth-germ; +but as a general rule the germ on the left side is the only one which +develops, the other lying asleep in its socket, where it is choked up +and never appears. Behind this long pike, which, like the tusk of the +elephant, attracts to itself all the ivory in the body, lies a +completely unfurnished mouth; so that the owner of this magnificent +weapon, invaluable as a war-tool, but quite inapplicable to the purpose +of supporting life, is obliged to feed on small fishes and +_mollusks_. We have not yet spoken about these latter, but if you +have ever seen slugs and snails you will know what a _mollusk_ is. + +The same wretched food falls to the lot of the whale also, that giant +of the ocean, whose open mouth forms an aperture twenty feet in extent. +Geoffroy St. Hilaire, in his indefatigable endeavors to trace out +points of resemblance connecting together animals the most unlike in +outward appearance, discovered, along the lower jaw of a young whale, +certain traces of teeth, indicating a last effort on the part of nature +to carry out her usual plan in furnishing the jaws of mammals; but, +like the right-hand tooth of the narwhal, these vain attempts soon +disappear, overgrown and lost in the tissue of the bone, so that the +whale offers us a true type of an _edentate_, classable with the +ant-eater, if one dared, and some people have dared, which by this +time will not surprise you. A classifying professor is utterly +merciless, whether he gets hold of the poor beasts by the mouth or by +the paw: they may protest with all the rest of their body against the +peg on which they are hung; so much the worse for them! If one were +to listen to what they have all got to say, it would be impossible to +classify even one. + +To return to the whale. As a compensation for the teeth which she found +herself unable to give him, nature has manufactured on the two sides +of his upper jaw the most extraordinary apparatus without exception +to be found in the mammal mouth. You know what is called the +_whalebone_ used in stay-making, &c. The name is quite correct; +for those little flexible black strips, which support the figure so +nicely, began life in wandering over the polar or Australasian seas, +fastened to the palate of some monstrous whale. + +On the two sides of the upper jaw the membrane which covers the palate +sends out rows of broad, thin, horny plates, which are from eight to +ten feet long (they have sometimes been seen twenty-five feet) in the +centre of each side, but which decrease gradually towards the +extremities. These are plates of whalebone (sometimes called whale's +whiskers), and the industry of man has turned them to a thousand +different uses; and you will open your eyes in astonishment when I +tell you that 800 or 900 of them have been sometimes counted on each +side of one mouth. Think of the number of stays that could be furnished +from the whalebone plates of one whale! It is true, they were not +exactly designed for this purpose originally. At the tips and on the +edges of these plates, the elastic fibres of which they are composed +unravel and peel off, and hang down from the lip like tufts of +horsehair. The Arctic seas, which the whale inhabits, are, like other +seas, full of innumerable troops of various little sea-animals, and +it is these which are destined to the honor of nourishing this gigantic +mass of flesh. When the colossus wishes to take a meal, he stretches +his mouth to its utmost width, and the salt water rushing in as into +a gulf, carries with it the imprudent little fry, who disappear then +and there for ever, being retained by the fringe-like sieve of the +whalebone. But as, in this way of eating, the stomach of the whale, +however large, would be terribly overgorged with water, he is furnished +with another apparatus for preventing the inconvenience. All the +superfluous water is rejected by the _pharynx_, and springs up +in spouts of fifteen or twenty feet high, through the nostrils, +_i.e._ the nasal openings, sometimes called "vents," sometimes +"blow-holes," which are pierced exactly at the top of the head. This +is a peculiarity common to all cetaceans, who have thence received the +name of "blowers," alluding to the powerful blast which is necessary +to send those majestic columns of water into the air; but it takes a +much milder form with the lesser cetaceans, such as dolphins and +porpoises. There is but a slight jet with them: the water escapes +comparatively quite quietly from the nostril-vents, trickling away +down the animal's sides. + +I hope you consider that I have told you something new this time, my +dear child, and that our machine is beginning to change its appearance +very materially. I told you before that we had reached the outskirts +of the mammal kingdom. When we got to the armadillo we were within a +stone's throw of the reptiles, and here, one step more would take us +to the fishes. But we must first consider the birds, who are a very +superior set of animals to either of the latter; and we have accordingly +an order of mammals (Monotremes) which, as you will now find, opens +the road on that side also. + +There are but two sorts, and both of them are natives of Australia, +which is, as you may have heard, the land of the wonderful in natural +history, and their existence was unknown to the learned men of Europe +till within the last sixty years. The most extraordinary of the two +is the _Ornithorhynchus_, or, to translate the hard Greek word +into English, the _Duck-bill_. Its mouth is a true duck's bill, +a downright horny beak, and its short paws sprawling sideways with a +membrane joining the toes together below, and coming a good deal beyond +them in front, seem intermediate between the flippers of the seal and +the webbed feet of a water-bird. The first naturalist who had anything +to do with the ornithorhynchus, Blumenbach the German, who gave it its +pretty name, did not think it was able to suckle its young, so much +did it differ from mammals in some respects, though looking so like +them on the whole. And presently a report arose in the learned world +that the new animal which had been classed at all risks among mammals +(it having the close fur and almost the body of the otter), a report +arose, I say, that this ornithorhynchus of Blumenbach laid eggs like +a real duck. The uproar in the Academies was tremendous. As early as +1829, indeed, a learned Englishman, Sir Everard Home had sent over to +France an authenticated drawing, as he said, of an ornithorhynchian +egg, to the delight of the hunters after analogies among animal races; +while Cuvier looked sadly askance at the intruder, whose arrival threw +his animal outlines into confusion, there being no place in them for +such a beast. Happily for the poor animal, he has ended by almost +settling the matter for himself. The ornithorhynchian egg has never +turned up. But in the animal's nest have been found baby +ornithorhynchuses, newly born, under two inches long (the full-grown +animal being more than a foot and a half), and not a trace of eggshells +near. Further investigations showed that the mother ornithorhynchus +nursed her young with milk, for curdled milk was found in their +stomachs; so the Australian phenomenon has been restored triumphantly +to the Mammalian order, whence Geoffroy St. Hilaire had excluded both +it and its companion, the _echidna_, a sort of hedgehog, provided +like the ornithorhynchus with a bird-like bill, only more of the +canary-bird sort; and like it, also, approximating to the bird tribe +by other details which do not belong to our subject. And so the matter +stands at present; and all we venture to say is that classification +had a very lucky escape. + +And now, my dear child, that I have made you acquainted in detail with +your nearest neighbors, the last of whom, nevertheless, are strangely +unlike you outside, however they may resemble you within, I shall take +the liberty of going more quickly over the ground, and shall point out +in the mass only the more important changes which lead from one class +of animals to another. I should be found fault with if I tried to make +you too learned, and you yourself might be tempted to tell me, to my +sorrow, that you had heard about enough. + + + +LETTER XXXIV. + +AVES. (_Birds._) + +Tell me, my dear child, when you have seen birds taking their flight +into the air, and going boldly to their object, without a thought of +all the barriers, ditches, rivers, and mountains, which hinder man at +every step in his travels, did it never strike you to wish for their +wings, and imagine how you would fly off if you had them? If you ever +dreamt this dream, do not apologise for it; it is one as old as the +world. 'Oh that I had wings like a dove!' cried the Prophet, nearly +3,000 years ago; and the dialogue of the swallow and the prisoner, so +often sung by poets, has been repeated in prose behind all the +prison-bars on the globe since prisons were first invented. + +Now you will not think it kind on my part, but I must undeceive you +about this fancy, as you will be undeceived some day about many others. +The wings of a dove or swallow would be of no use to you if you had +them, any more than the formidable swords of the middle ages would be +to our modern gentlemen, were any one to put such into their hands. +We are not adapted for them, nor they for us. + +You saw, some time ago, what an amount of muscular exertion was required +for running--what a violent flow of blood, what hurried play of the +lungs. Now in flying it is still worse; for the earth, at any rate, +holds us up quite naturally, whereas the air will not hold up the bird +unless it is beaten vigorously and unremittingly by an untiring wing. +If we men, constructed as we are, had to do such work, we should be +out of breath at once; the heart would cry out immediately for quarter, +and the diaphragm turn red with anger. And only just imagine in what +a critical position a poor wretch launched into the air on the wings +of a swallow would find himself when, at the end of five minutes, his +servants should refuse point-blank to go on working at a height of 500 +feet above the ground! + +But a bird has not these internal rebellions to fear. In the first +place, it has no diaphragm; so here is another friend to whom we must +say good-bye. We shall not meet with him again anywhere. The journey +we are taking together, my dear, is somewhat like the journey of life. +One sets off, surrounded by friends and acquaintances, but whoever +travels on to the end is apt to find himself alone at last; this is +what is happening to the digestive tube, which we shall see losing all +its accessories, one by one, as we gradually advance in our study. +Even now here is one essential fundamental difference in the internal +machinery. The body has only one compartment instead of two; and the +lungs, masters of the whole space, extend freely to its utmost depths. +When a fowl is cut up at table, look along the body, and you will find +lodged in the cavity of the ribs, a long, blackish, and spongy mass: +this is the lungs. There is not, therefore, the same danger of a bird's +getting out of breath as with us; that delicate board which is found +in our bellows is wanting in his. His is set in action solely by the +to-and-fro movement of the ribs, which is produced by muscular +exertions, which are greatly increased during the action of the wings. +From which it follows, that the rapidity of flight itself regulates +the arrival of air, and consequently the expenditure of strength, or, +if you like better, the activity of the fire, since the energy of the +muscles depends, as we have seen, upon the quantity of oxygen that +feeds the internal stove. + +This is not all. These elongated lungs are still not sufficient to +furnish the blood with all the oxygen demanded by this excessive labor +of flight. They are pierced with holes, through which issue pipes which +carry the air all over the body. You know what is said of +spendthrifts?-that they burn the candle at both ends. It is so with +the blood of birds. That fillip which in our case it receives in the +lungs, and which sends it back full of vigor into the arteries, is +repeated in the bird at the other end of the arteries as well. The +capillaries, those delicate vessels at the end of the arteries, plunge +from all sides into little reservoirs of air-lungs, therefore-where +the blood renews its provision of oxygen, and relights its +half-extinguished fire, so that it sends the combustion afresh into +the muscles on its return back to the heart, and sets them going a +second time. + +The natural consequence of this prodigality of combustion is, that +there must be, in proportion, much more oxygen in birds than in us; +and that of all animals a bird is the one most quickly poisoned by his +own carbonic acid when the air is not renewed around him. Therefore, +let me beg you never to think of putting a poor little bird under a +wine-glass, as a child of my acquaintance once did, that she might +examine her little friend more closely. In the twinkling of an eye he +would consume all the oxygen inside his prison, and you would soon see +him fall upon his side and die. + +On the other hand, the temperature of these flying machines, which +consume so much oxygen, is very much higher than ours. It rises to +41°, 42° (centigrade), and sometimes to 44°, 7° higher than with us. +If ever you have taken hold of a little bird, you will have remarked +how warm it makes your hand: this is quite natural, since there is +always a double fire going on within him, to meet the extraordinary +expenditure of strength that is required of him whenever he takes wing. +Besides, do but look at the poor little creature when you have +imprisoned it in a cage! How it goes up! How it comes down! How it +hops from one perch to another, with a quick sudden movement, like +that of a spring when it unbends. There is no apparent cause for this +state of continual agitation; and yet there is a cause, and only too +serious a one. Its fire is not slackened because you have put it into +a cage, and its muscles, lashed furiously on by the double-oxygenized +blood, drive it hap-hazard into a thousand movements, in which it +expends, as best it can, a superabundance of power, which no longer +finds natural employment. Little children, who are the real +singing-birds of our homes, and whose blood also drives much more +energetically along than ours--little children I say--often fare no +better than caged birds in those larger cages we call schools; and +schoolmasters and governesses would scold rather less if they thought +rather more about this. It is right, I do not deny it, that the +rebellious young rogues should be taught in good time not to abandon +themselves, like wild birds, to the mere animal impulses of the blood: +but, in dealing with them, one must also make allowances, as they say, +for the fire within, and know how to open the cage now and then. It +is not for you, however, that I say this, young lady: you are no longer +a little child; but it may happen that you may have some to take care +of some day. Believe me, then, you must not expect too much wisdom +from them, and you must allow them to change their perch every now and +then. It is a law of our Almighty Father that little children, and +little birds, should not stay too long in one place. + +The mechanism of the circulation is here the same as with us, and does +not offer any important peculiarity. Only the left ventricle of the +heart has walls of extreme thickness, which enable it to launch the +blood into the members with greater vigor and rapidity; and the blood +itself, although it is composed of precisely the same materials as +that of the mammals, differs from it nevertheless as regards the +globules. In the first place, they are more numerous; secondly, they +are larger; and finally, instead of being round like a plate, they are +drawn out ovally, and are almost shaped like those long dishes on which +fish is usually served. I shall not attempt to give you the reason of +their size and form. This is hidden from us in the same mystery which +envelopes all the microscopic population of the blood; but is it not +a curious thing, this strange persistency of form in the globules ofall +animals of one class? In all birds they are oval; in all mammals +they are round. In all? Nay, I am wrong. As if the better to hide from +us the key to this riddle, nature has amused herself by making an +exception. Camels and llamas, I forgot to tell you, have also globules +in the form of long dishes, like the hen and the chaffinch. Find out +why, if you can. As to the reason of the number, it is a very simple +one. Since the energy of the blood resides in the globules, it follows +that the most energetic blood will contain the largest amount of +globules. Looking at you, for instance, little monkey, running and +jumping about the garden, I would lay a wager, without counting first, +that there are, in one drop of your blood, some millions more globules +than in one of mine. + +Let us now go on to the digestion, with which, properly, we ought to +have begun; but I preferred pointing out to you, first, the particular +character which is the chief mark of distinction in the organization +of the bird. + +'When hens grow teeth,' says a shrewd proverb, meaning of course, +_never_. Birds have no teeth, and in this respect there is no +variety among them. All, from the first to the last, have uniformly +the same tool to eat with--the bill, that is--which is, in all cases, +composed of the same elements, two jawbones elongated to a point, and +clothed in a horny armour, which makes their edges sharp and cutting. +At the same time were we to review the birds in detail, as we have +done the mammals, you would see that there are almost more modifications +to be observed in this one single instrument than in our thirty-two +teeth. All birds have a beak, but each has his own, organized expressly +with reference to the kind of food needed by its owner. The eagle's +beak, which mangles living prey, is pointed, bent, and hard as steel; +the bill of the duck, which laps up water from ponds and puddles, in +order to get worms and half-decomposed refuse out of it, is soft, and +flattened like a shovel. The woodpecker's, which has to pierce the +trunks of trees, is like a pickaxe; that of the humming-bird, which +has to suck up the juice of flowers from the bottom of their corollas, +is slender as a needle. The swallow feeds on flies, which it snaps up +on the wing, and has a soft bill, which opens like a little oven. The +stork picks up reptiles in the mud of the marshes; its beak is +straight-pointed, cutting as a knife, and resembles a long pair of +pincers. The sparrow feeds especially on hard grains, difficult to +break; accordingly its beak is stumpy, short, and thick, and is arched +on the upper side for still further solidity. But I should never end +if I began to enumerate all the thousand varieties in the bills of +birds. Each variety, too, corresponds with some peculiar sort of life, +and consequently with a general conformation (easily ascertained) of +the animal in which it appears. Give a naturalist the bill of a bird +--only its bill remember--and he will tell you half its history without +fear of being mistaken. + +On the other hand, we must not deceive ourselves as to the real value +of this complaisant bill. Let it transform itself as it pleases into +all manner of forms for the better fulfilment of its task, it makes, +at the best, but a very poor instrument for mastication; nay, to say +the truth, it breaks, cuts, and tears, but it never masticates at all. +Thus the bird's mouthful is far from undergoing as perfect a preparation +as ours does. It is no sooner taken in than it is swallowed, and the +salivary glands, which are still to be found under the tongue, seem +only to be there as a matter of form; what little saliva they produce +is thick and sticky, and has none of the qualities necessary for making +that liquid paste which our tongue sweeps up from every corner of the +mouth. Besides, it must be owned that a bird's tongue would be a very +awkward implement in such a task. Open a hen's bill and you will see +therein a very inferior sort of porter. It is merely a dry hard lance, +as it were, armed with prickles at the point, as ill-qualified for +tasting as for sweeping. So the hen does not waste her time in finding +out the flavor of what is thrown to her. She picks up and swallows +over and over again, without appearing to experience any other pleasure +than that of satisfying her appetite. Birds of prey, it is true, have +rather more convenient tongues, capable, moreover, of tasting up to +a certain point; and the parrot, who is a complete epicure, and chews +his food philosophically, has a charming-little black one, thick, +fleshy, and susceptible--a true porter, in fact-who enables Polly +thoroughly to enjoy her breakfast. But certain birds who live on insects +surpass even the hen in the dryness and hardness of their tongues. +That of the woodpecker, especially, is a model of the kind, and deserves +a few words more than the others. Picture to yourselves a long pin, +terminated by an iron point with barbs like those of fish-hooks. An +ingenious mechanism enables the bird to dart it out with the rapidity +of lightning, far beyond his bill, upon the insects to which he gives +chase. The point pierces them, and the hooks retain them, without any +need of assistance from the bill. I have just told you that this bill +pierces the bark of trees; but it only plays the part of gamekeepers +on grand sporting occasions, who beat the bushes to make the game rise. +The woodpecker's bill routs up the insects by destroying their shelter; +but the real sportsman is the tongue. Good-bye to any notion of a cosy +little chat in such a porter's lodge as that! What could a harpoon +have to say for itself? + +Do not, however, let this miserable entrance-hall alarm you, at the +same time, for the fate of the mouthful thus presented half-dressed +to the œsophagus. You will find it only so much the better treated +within. In the first place, the œsophagus, when half-way down to the +stomach, swells out suddenly and forms a pocket, which is generally +particularly well developed in birds who feed on grain; this is called +the _crop_ in English, in French _jabot_; whence comes the application +of that word to those full shirt-frills which have sometimes been the +fashion. It is the pigeon's _crop_ that gives him the rounded chest over +which he bridles so prettily. The crop is a receptacle where the food +makes a halt: it is something between the pouch of the monkey and the +paunch of the ox; a preparatory stomach, which does not, it is true, +send back the grain to the bill, for the bill could do it no good, but +in which that grain lies until there is room for it further on. + +Prom thence it resumes its journey; but, before reaching the true +stomach, it passes through a second enlargement of the oesophagus, +whose walls are pitted with numberless little cavities, from which +pour over it the juices destined to supply the place of the saliva +that was wanting above. + +It reaches its destination at last, but still hard, and generally +whole. No matter, however. The stomach which receives it, and which +is called the gizzard, is quite a different sort of thing from a useless +membrane, thin and delicate like ours. It is a thick muscle of enormous +power, lined inside with a kind of horny skin, so tough that nothing +can break through it. You may form some idea of the prodigious strength +of this organ, when I tell you that turkey-fowls have been made to +swallow hollow balls of glass, so thick as not to break when dropped +to the ground, and that at the end of a few days they have been found +reduced almost to powder in the uninjured stomach. No fear of +indigestion with such an apparatus as that. Though the grain may not +have been masticated in the bill, what does it signify? There is a +power here, as you see, quite equal to carrying the whole work through. +Thanks, indeed, to the invaluable horn which lines it, fowls which +have no teeth of their own can safely present themselves with as many +and as hard ones as they please. They swallow small pebbles, which rub +against the grain, during the contractions of the gizzard, and act +just as effectually as if they were fixed in the jawbone. Well, this +terrible gizzard performs its crushing work with such energy, that not +only the grain but the pebbles themselves are ground down there, and +end by being pounded into fine sand. When you rear fowls, do not forget, +if you keep them shut up, to put within their reach a store of small +pebbles, so that they may have teeth to run to in time of need. + +You remember the _pylorus_--the porter down below, who keeps the +door of egress from our stomach? He is as badly provided for here as +his fellow-workmen up above; worse in fact. It is a gaping hole, and +we cannot expect a very strict supervision from it. Birds who feed on +fruits profit by this fact to carry vegetables from one country to +another. With such an easy opening, seeds have a good many chances of +passing from the stomach unaltered; and then they drop from the clouds, +as is supposed, hap-hazard, and germinate afterwards, when circumstances +prove favorable, to grow up before the astonished eyes of the natives +into plants of which they have never even heard. The French +Acclimatization Society, which I spoke of lately, and which, though +so modern, has correspondents all over the globe, is at this moment +laboring to effect an exchange between all countries of the natural +productions of their soil. But here you see that nature had thought +of this before, and established her acclimatization society long ago. + +To complete the internal work of digestion, so feebly begun in the +bill, an extremely large liver pours torrents of bile into the duodenum, +and the manufacture of chyle proceeds with that wild rapidity which +characterizes all the living actions of birds. But speaking of this +liver, I think I ought to give you an account of a celebrated dish, +considered a great dainty by epicures, called _pâtés de foies +gras_--_fat liver patties_, to translate it into its meaning. +Very likely you will not care to eat them after hearing my story; but +that will be no great loss to you, for it is a very indigestible sort +of food, and not at all good for children. + +You remember my telling you about Englishmen going to India and coming +back with a liver-complaint, from having eaten and drunk more than the +climate allowed? By an imitation of this process, human +ingenuity--occasionally so cruel--has created the _pâtés de foies +gras_, the glory of Strasburg. I have been in the country, and can +tell you how it is managed. They shut a goose up in a square box, where +there is just room for his body. They open his bill at feeding-time, +and cram down with the finger as much food as can be got in. This is +throttling rather than feeding it. The poor beast, who can use no +resistance, since it cannot move, and who is kept in the dark to prevent +excitement; the poor beast is quite unable to burn all the mass of +combustibles with which the blood soon finds itself loaded. This carries +them to the liver to be turned into bile; but the liver is not equal +to the work, becomes loaded in its turn by unemployed materials, and +grows and grows, till at last, having filled up all the space around +it, it stops the play of the heart and lungs. When the animal is +nearly suffocated they kill it; and this is how we come to have _pâtés +de foies gras_ to eat! If they give us a fit of indigestion +afterwards, it is a vengeance we richly deserve. At Toulouse, where +the same trade is carried on on a large scale, they used formerly to +go even beyond this. They fastened the goose by the feet before the +fire-place, after having put out its eyes. The imitation of the +Englishman's proceeding was still more perfect here, for the fire acted +the part of the Indian sun to perfection. I do not know that part of +the country well enough to tell you whether they have quite given up +this piece of wicked ingenuity; all I can say is, I devoutly hope so. + +The intestine of birds is much shorter than that of mammals. Here +everything is done at full gallop, and the chyle has not to go far +before it is absorbed. I have before me a book, in which I am told +that the wagtails eaten in France can be fattened in twenty-four hours, +if you only know how to set about it, and these birds are not rare; +they belong to the same family as the red-breasts, the tomtits, and +the nightingale. Thrushes and wheatears (ortolans) require, for the +same purpose, four or five days in the same country, left to themselves +to roam about, when the vine keeps open table for them. + +This incredible quickness, not only in digesting, but, what is much +more, in transforming food into fresh living material +(_assimilating_ it, as it is called), has often a fatal result +for the bird. He is prohibited from fasting; his life is a fire of +straw, which must be replenished unceasingly, or it will die out in +the twinkling of an eye. Our own little birds--children--eat oftener +than grown-up people, and if by any accident they are kept waiting +awhile, they soon cry out with hunger. You know this, do you not? Well, +then, if any one should give you a bird to keep in a cage, remember +that you have undertaken a great responsibility, and that it will not +do to be careless with him. To neglect feeding him for one day is to +run the risk of finding him starved to death next morning. With this +warning, I will conclude my chapter on birds. I hope I have not spoken +in vain in behalf of those poor little captive songsters, whose fragile +lives are at the mercy of their young masters and mistresses. + + + +LETTER XXXV. + +REPTILIA. (_Reptiles_.) + +Passing from birds to reptiles is like falling from a torrent into +still water. Life drags on as sluggishly with the second as it dashes +furiously forward with the first. + +I spoke to you just now about a fire of straw: now we have a fire such +as Frenchwomen make in their _chaufferettes_, or foot-stoves. A +handful of charcoal-dust, and a few live embers between two layers of +ashes, is enough for the whole day; which is economical, is it not? +but then it throws out only just warmth enough to keep one's feet +comfortable. And so it is with reptiles. They live at very small +expense. If you feed them once a month they will not complain, for so +slow a fire does not often need replenishing with combustibles. It is +even said that the experiment has been carried so far with tortoises +that they have been made to fast for more than a year, and still the +charcoal fire kept up its languid pace. Of course, on the other hand, +there is not nearly so much oxygen consumed at once upon such a diet +as this. Where a bird would perish twenty times over in five minutes +for want of oxygen, a lizard can remain whole hours with impunity. +Moreover, the animal heat of reptiles is in proportion to their +expenditure of it. Graceful as is the snake (that living jewel so often +copied by bracelet-makers), you feel on touching it an instinctive +horror, caused by the thrill of cold it produces. All the animals we +have considered hitherto have warm blood, and bear within themselves +the source of their heat, which is pretty nearly always the same. But +reptiles are cold-blooded, and heat comes to them chiefly from without. + +If, at the end of a cold winter, we go to some favorable corner to +catch the first rays of spring sunshine, we feel ourselves almost +re-born, as it were, as if a new life had come into us with the +sunbeams. Look at the little lizard you see frisking on the white +stones of the wall; upon him decidedly the sun is darting actual life +from its rays. While the cold lasted he staid squatting in his +hiding-place--not asleep, but annihilated--congealed, so to speak, +like water caught by the frost; no longer digesting, and hardly +breathing, he had ceased to live in reality: and it is no imaginary +regeneration which the return of warmth brings to him. Like those +helpless people who have not the power to carve out their own destinies, +reptiles have within them only an insufficient source of animation; +their life is at the mercy of the sun, and is high or low, according +as that rises or sets in the heavens. At Martinique, where at noonday +it darts its devouring rays perpendicularly upon the cane-fields, and +every one flies into the shade to escape its scorching heat, the +rattlesnake traverses the country, monarch of all he surveys; he strikes +rapidly with a vigorous tail upon the calcined ground; and woe then +to any one who receives his bite! All the fire of the atmosphere has +passed into his frame. Now go to the Zoological Gardens, and see him +there: he crawls languidly under the coverings that shelter him; if +by chance he bites any one, it is with an idle tooth that no longer +knows how to kill; his life was left behind with the sun of the tropics, +and it is little more than a corpse that you are looking at. + +And so among ourselves, my dear child: we meet with people whose whole +power comes from without, who are brilliant and haughty in the sunshine +of good fortune, but crest-fallen, cowardly, and cringing in the cold +days of adversity. Nevertheless, they are constituted originally like +other people: they are neither greater fools as a general rule, nor +less gifted than their neighbors; where they fail is in the heart, but +that is enough to spoil everything. And so with reptiles: the heart +is their weak point also. Like us, they have lungs into which the air +pours without any difficulty, and a heart to send the blood to them; +so it seems at first sight as if there could be nothing to prevent +their resisting the changes of external temperature just as well as +ourselves. There is only one small trifle wanting, and that is a +partition in the middle of the heart; but this one defect is enough +to disorder the whole machinery. + +You know that, with us, the heart is divided into two compartments: +the right ventricle, which receives the venous blood from the organs +and sends it to the lungs; the left ventricle, which receives it (now +become arterial) from the lungs and returns it to the organs. Hence +the double system of veins and arteries, the one going from the heart +to the lungs, the other from the heart to the organs. All this is found +the same in reptiles: except that the partition, which separates our +two ventricles from each other, does not exist in them; and the heart +has only one common room, in which, therefore, arterial and venous +blood become mixed together. It follows from this that, at each +contraction of the heart, it is a mixture of arterial and venous blood +which is sent in the two opposite directions at the same time, and +that the organs receive some which has been used before, while the +lungs have some returned to them which has been regenerated already. +Now, on the one hand, this mixed blood can only keep up an imperfect +combustion in the body (like the live embers between two layers of +ashes that we spoke of lately), and, on the other hand, the air in the +lungs can only act upon a part of the blood it meets with there, the +rest having already undergone the regenerating process. And this +accounts for both the feeble animal heat and the small consumption of +oxygen in reptiles. + +Added to which the lungs of a reptile are coarsely constructed, and +composed of cells enormous in comparison with ours, so that the blood +does not find nearly as many little chambers to rush into for a taste +of air as with us. Moreover, you must understand that there is no such +thing as a diaphragm here: the lungs float loosely in the form of +elongated bags in the one only cavity of the body, and the slight +movement of the ribs does not allow them to dilate sufficiently to +take in much air at a time. + +All these things, taken together, make the reptile a very poor stove, +and render him incapable of any prolonged exertion. The serpent darts +like an arrow upon his prey; but he could not pursue it for half a +mile without stopping, not even over the burning soil of the equator. +The lizard is very nimble, is it not? and the quickness of its movements +rather reminds one of the agility of a bird. But watch it, and you +will see it only moves in jerks, and keeps stopping every minute; it +cannot escape you if there is no hole near into which it can disappear. +In France there is a large green lizard that runs among the vine trees. +If you pursue him he is off like lightning for a second; then he stops +suddenly short. You return to the charge, and he starts afresh, but +only to stop again. At the fourth or fifth attack he is quite out of +breath; you poke him with the stick with which you have been hunting +him, but in vain; there he lies motionless, in spite of his alarm. A +few steps have brought him to the end of his powers, like a man whose +heart is diseased and who cannot go far. This, however, is a peculiarity +common to all reptiles. Each of the three orders of which this third +class of Vertebrata is composed has its own particular history besides. +You must excuse my mentioning the barbarous names that have been given +them, and allow me to call them _tortoises_, _lizards_, and _serpents_, +like other people. The hard names mean no more than these; but they are +Greek, which is always more imposing. + +The slowness of the tortoise has passed into a proverb, which is not +to be wondered at; for they cannot inhale the air, because their ribs +(which are a reptile's only resource for breathing) are condemned to +absolute immobility. The _carapace_, or shell, which the tortoise +carries on his back, and under which it retreats upon the least alarm, +as under a shield, is really formed of its ribs, each of which has +widened itself so as to join on to its neighbor, like the boards of +an inlaid floor, which run one into another. Of course there is no +question of moving up and down with such ribs, and the poor bellows +cannot work at all. How does the tortoise get out of this difficulty +then, you will ask? I answer, it swallows air, as we should swallow +a glass of water. You see its mouth open and then shut again, thereby +taking in an actual mouthful of air, which the sides of the mouth, by +contracting themselves, send straight to the lungs. These, which are +very large, get filled in this way by degrees, and, when they are quite +inflated, they expel the overplus by collapsing, like an over-stretched +spring. You may imagine that this does not produce a very active +respiration, and that a tortoise would be puzzled to run at even a +moderate trot. To be sure, when he has once filled his great lungs +with air, he has enough for a long time. Most tortoises are aquatic, +and, as divers, leave the cetaceans far behind. Méry, an obscure French +naturalist of the days of the Empire, pretended that he had kept in +his house, _for a month_, some tortoises, whose breathing he had +completely stopped. Only imagine from this how far their life must be +below ours, although it is the result of similar actions, performed by +organs which after all are copies (imperfect ones, it is true) of our +own. + +Some tortoises feed on vegetable substances, and some upon fish or +small soft-bodied animals. Like birds, they mash their food with +difficulty, by means of a real bill. Their jawbones are generally +arched forward toward the front, and are furnished with sharp horny +plates, in which a fairly-marked denticulation or notching may sometimes +be traced, as in the bills of birds of prey. Indeed there is one, the +_caretta_, whose hooked and notched beak so completely recalls +the warlike bill of a hawk, that it is usually known by the name of +the "Hawk's-bill Turtle." You ought to know about this tortoise, for +it is the one which furnishes tortoise-shell, that nice material which +is so smooth to the touch, so pretty to look at, and so very fragile, +that it seems only fit for the use of ladies' hands. I could hardly +speak of tortoises without saying something of this one, out of +whose back was carved the handle of your own pretty little penknife. + +Behind this bill of the hawk's-bill there is a tongue, but of the +character of a whale's tongue, and it is fastened underneath to the +bottom of the mouth. At the base of it there is a sort of fleshy pad +or cushion, which serves instead of a soft palate, that being another +detail which is about to disappear from our history. We are now really +entering upon the simplification of the digestive tube, which will, +I forewarn you, end by being nothing more than a perfectly straight +pipe, without any appendages whatever. In tortoises the intestine is +still tolerably long, and is doubled up backwards and forwards many +times in the abdomen; but it is already beginning to lose that variety +of form which its different parts assumed in the higher animals. The +large intestine can no longer be clearly distinguished from the smaller +one, nor this from the stomach, which itself seems to be a continuation +of the oesophagus, without any very distinct boundary line between them. +The porter, who with us keeps the door of the stomach, does his duty +here so badly, that there are certain kinds of tortoises whose +oesophagus is covered with spines, the points inclined backward, to +prevent the food from rising up into the mouth whilst the oesophagus is +driving it down by its contractions. + +In the gray lizards of our walls we find teeth again, but very different +from any that we have hitherto seen. In the first place, they are not +content with their usual place on the edge of the jaws, but encroach +upon the surface of the palate, where they stretch out in close lines. +Besides, they are even still less like teeth than the great nails in +the jaws of the cetaceans. They are little ivory prongs, with the +points turned inwards, analogous to the thorns of the oesophagus in the +tortoise, and serve the lizard solely to retain and bruise his prey. +He lives on insects, especially flies, which he seizes on the wing +with the greatest skill, hastily catching and engulphing them in his +open jaw; they pierce themselves on the little prongs, and are swallowed +promiscuously. The tongue of the lizard has also a curious peculiarity, +which is shared by that of the serpent: it is divided at the end into +two threads, which dart in and out of its mouth, and by means of which +it laps, like a dog, the few drops of water it requires to satisfy its +thirst. I have seen lizards which had been tamed by children greedily +sucking up the saliva from their lips by drawing across them those +little forked tongues of theirs, which, after all, are very soft, and +perfectly inoffensive. + +The tongue of the chameleon, another species of lizard, is still more +curious. You must know that the chameleon is a lumbering lazy animal, +who feeds on flies and other swift insects, and who would, therefore, +be constantly liable to go without his dinner but that his tongue +serves him for a hunting weapon, like those of the wood-pecker and the +ant-eater. When at rest, it is an oval spongy mass, lying comfortably +in the mouth, with nothing formidable in its appearance; but let the +prey come frisking round the chameleon, as if despising so helpless +an enemy, and this great soft tongue is transformed into an active +dart. It shoots forth like an arrow, and will sometimes seize the rash +intruder at half a foot's distance, transferring it with equal rapidity +to the motionless mouth. The blow is so soon struck, that it is very +difficult to see how it all happens. Some say that the chameleon curves +the tip of his tongue by a sudden effort, and then catches his flies +with it, just as you would catch them with your hand. Others maintain +(and this is the general opinion) that the tongue of the chameleon is +terminated by a sort of sticky cushion, on which the flies are caught, +like birds with birdlime. This singular dart is always out-jerked with +such force that, if it strikes against a glass (the experiment has +been tried with chameleons in captivity), it makes a sound as loud as +that of a pea from a pea-shooter; so you may judge if it is not strong +enough to stun a fly. Besides this, too, the chameleon (who is +by-the-by, a hideous little beast) has given endless trouble to +naturalists on another and very different point. It is he who is +so celebrated for his faculty of changing color when any emotion +agitates him; and ever since the days of Aristotle, who lived more than +two thousand years ago, people have been trying to explain this, without +any one being able to flatter himself that he has found out the exact +answer to the riddle. + +But there is a lizard more interesting still, and that is the crocodile. +He stands alone among reptiles. His heart has two ventricles, and you +would think that he ought to be included in the class of warm-blooded +animals. But, no. The separation of the two kinds of blood takes place +in the heart, it is true, and it is really true arterial blood which +the aorta carries away from the left ventricle. But the right ventricle +has two doors of exit. One communicates with the lungs, the other with +the aorta; and the latter has hardly performed its distribution in the +upper part of the body when it meets, as it descends, with a treacherous +tube bringing to it a current of venous blood. In this way only half +the blood that comes from the veins passes on to be regenerated by +contact with the air, and all the hinder part of the body receives +nothing but the mixed blood common to reptiles, while the head and +fore members enjoy the privilege of the superior orders. After this +go and lay down your laws of classification! Nature, while maintaining +amongst all animals the same principle of life--the regeneration of +the blood by oxygen--has in their construction followed many systems +leading to the same result by different combinations, and which seem +to permit the establishment of essential distinctions among them. Here +is an animal who, if I may so express myself, is climbing up from one +system to the other, and you would have to cut him in two before you +could classify him properly, since his fore-quarters have risen to the +warm-blooded animals, while his hind ones are left behind among the +cold-blooded reptiles! + +But there is something which even outdoes this. + +On dry land the crocodile is timid, faltering, a bad walker, incapable +of regular combat, and a man can manage him with a stick. One feels +that he is betrayed by the hinder half of his body, through which +circulates the only half-oxygenized blood. But when once he has plunged +into the water his whole behavior suddenly alters; he is a ferocious +being, high-mettled, indomitable, a savage enemy, redoubling his +exertions, as if the entire mass of his blood had suddenly become +arterial. Geoffroy St. Hilaire, who followed Bonaparte as a scientific +explorer when he set out for the conquest of Egypt, the country of +crocodiles, was deeply struck by studying on the spot this double life, +which seems in a way to maintain two beings in the same body. He +afterwards gave an extremely curious explanation of it in his work on +the crocodiles of Egypt. Here it is; but I forewarn you that you will +not understand it: + +"The crocodile, when it is under water, receives by two canals into +the cavity of the abdomen, a considerable quantity of water, which the +animal can renew at will." + +You are not much the wiser, are you? But wait a moment. We are soon +coming to the fishes, and you will then see what an unlimited scope +nature has allowed herself here. Not satisfied with two systems in one +animal, she appears to have got hold of three. + +If we continue the examination of this privileged reptile, we shall +find many other infractions of the usual rules of his class. His tongue, +certainly, is fastened to his mouth like that of the tortoise, so much +so that the ancient Egyptians told the Greeks he had not got one; but +his set of teeth clearly approach those of the lower mammals. You have +probably heard a great deal of the strength of the crocodile's +formidable teeth. Travellers have given them this reputation; but we +have nothing to do with that now. They stand in battle array, in a +single line, along the whole length of the jaws, into which they are +sunk with genuine fangs, whilst the prongs of our little lizard are +merely fastened to the surface of the bones which support them. Indeed, +in one way, the crocodile is even better provided than the mammals. +He possesses under each tooth one or two germs, the life of which lasts +as long as that of the animal, and which are always there ready +toreplace the previous one should it chance to fall out. There are many +ladies, and (not to be rude) gentlemen as well, who would, I am sure, +give a great deal to have as many teeth at their service. Indeed, they +may possibly think Dame Nature very unjust to have selected this great +villanous beast rather than us as the object of a gift which they would +have been so well able to appreciate. But we must not blame nature too +quickly: she had her reasons. We, during our infancy, have teeth in +reserve. Now, a reptile may be considered as an imperfect rough draft +of a mammal; and the crocodile gives one thoroughly the idea of a +mammal half-finished and fixed for life in a state of childhood. I am +sorry that I cannot enter into full details, that you might see how +far the idea is a just one. Moreover, in his character of a perpetual +child, he is always growing bigger all his life long, and never seems +able to die but by accident, hardly ever, I may really say, from old +age. By specimens kept in captivity, it has been ascertained that +their growth is very slow. Well, imagine their being only from seven +to eight inches long when they come out of the shell, and that +full-grown crocodiles have been found thirty feet in length, and +calculate accordingly. You will not account for it under a century; +and I should like to know what would become of this venerable child +of more than a hundred years old if kind Mother Nature had not left +him our system of milk-teeth to the end? + +A curious peculiarity of these persistent teeth is, that they are +hollow inside, so much so, that the bowls of tobacco-pipes are said +to be made from them in Europe. I mention the fact, although of no +great interest to you, for the benefit of any pipe-merchants who have +not yet thought of sending for such things to Cairo. + +But let us return to the efforts perceptible in the organization of +the crocodile to raise itself to a higher level. The soft palate, as +we called it (Letter VII.), is wanting in other reptiles; but here +there is one which completely closes the entrance of the windpipe (the +larynx). I announced, too, the disappearance of the diaphragm; and we +bewailed together the loss of that servant of the good old times, whose +touching history you must, I am sure, remember. But I reckoned without +this wretched crocodile, who seems determined to give the lie to all +we have been saying. He has a diaphragm, and one which acts well enough +in the main, although it is pierced right through the middle, as if +it were rather ashamed of being there, and wished to make up for +dividing the body into two compartments, against all proper reptile +regulations, by opening a door of communication between them. What +shall I tell you besides? The lungs, not to be behind the rest of this +aristocratic reptile's organization, are hollowed into cells much more +complicated than those of his fellows. You find here no end of nooks +and corners, which multiply opportunities of contact between the air +and the blood, and so give the crocodile almost the respiration of the +mammals, as he has already got pretty nearly their system of +circulation. + +With serpents, again, we fall very low. When we were speaking of the +tortoises I told you that, in proportion as we come down in the scale, +the digestive tube has a tendency to get rid of its accessories, and +to assume the appearance of a perfectly straight tube. If any one were +to cut open a serpent before you, you would see this final condition +almost reached already. In the first place, the soft palate is entirely +suppressed, and the mouth extends straight into the oesophagus, whose +tube seems to run through the whole length of the body without +interruption, with just four or five doublings towards the base, in +that part which represents the intestines. An imperceptible swelling +indicates the place where the real stomach lies within; but in another +sense one may call the oesophagus, and I might almost add the mouth +itself, its stomach. You shall see how. + +The jaws of serpents are even in a more unfinished state than those +of other reptiles. Nature has not taken the time to weld the different +parts of them together; but these begin by not being very firmly joined, +remember, in young mammals. The bones of the head, which support the +jaws, are themselves movable, and can be detached from the skull if +necessary, so as to allow the throat to open extraordinarily wide; +thus it is not uncommon to see a serpent swallow animals much larger +than itself. You will be horrified when I tell you that the anaconda, +one of the giants of the family, swallows large quadrupeds at a single +mouthful. What are our mouthfuls in comparison with his? however, it +must be confessed, that his often take several days to go down. When +the animal has rolled up his prey in his terrible folds, he pounds and +kneads it till it is reduced to a kind of long roll, which he moistens +with a copious slaver to make it slip down more easily. Then, attacking +it at one end, he fastens this very expansive jaw upon it, and the +gigantic mouthful slowly begins its journey; what was left outside the +mouth, advancing little by little, in proportion as the digestion +reduces what has entered to pulp, and sends it farther down. This is +on great occasions; but in the case of more modest prey--a rabbit, for +instance--the mouthful goes in whole at one gulp and remains stationary, +partly in the oesophagus, partly in the stomach, while the powerful +juices distilled by the walls of the latter are dissolving it. + +You can see that a soft palate would have been quite useless here, and +that the serpent has not much need of teeth to chew his food. +Accordingly, his are nothing but simple prongs, like those of the +lizard, and, like his, they extend over the palate, the more effectually +to cut off the return of the swallowed masses of food. About a hundred +and twenty have been counted in the throat of the boa-constrictor; but +their number varies considerably in the different species. They are +not organs of the highest order, and nature is not very particular +about the quantity. + +There is only one tooth among serpents of which she takes any particular +care, and that is the venomous tooth which she has bestowed on certain +species, and which serves them for striking down, as it were, the +animals on which they feed. Let us study it in the rattlesnake, the +most celebrated of this odious race. On each side of the upper jaw you +may see, isolated from the others, and exceeding them all in length, +a very sharp fang pierced through by a tiny canal, which opens into +a gland placed at the root of the tooth. The bone which supports this +little apparatus is very flexible, and when at rest, the fang, falling +back, hides itself in a fold of the gum. When the animal wishes to +bite, it springs up again, and the gland, compressed by the action of +biting, sends into the little canal a jet of poison, which runs through +it into the wound. As far as can be ascertained, this poison paralyses +the victim and disorders the blood, which at once loses its power, +and no longer acts upon the organs as before; still it is only injurious +when it has been carried by the current of circulation into the mass +of the blood; if swallowed, it has no effect whatever on the stomach. +Now do not look at me with such incredulous eyes, as if it were quite +impossible any one should think of swallowing such a thing. You have +no idea what a scientific man is capable of when he comes to close +quarters with nature, for the purpose of extracting one of her secrets. +He has his own fields of battle, where very often as much courage is +displayed as on any other. + +These two fangs, in which lie all the power of the animal, are of the +greatest importance to him, and their want of solidity makes them +liable to remain in the wounds which they have made. In consequence +of this, they enjoy the same privilege as the teeth of the crocodile, +and in a still greater degree even. Behind each poison fang lie in +wait, not one nor two, but several sentinel germs, ready at the first +alarm of a loss to set to work and re-supply the disarmed serpent with +his venomous needle. So the serpent also lives in a state of perpetual +childhood: he is always growing; and I could not tell you the exact +natural limits of his life any more than of that of the crocodile. +They are gentlemen who do not allow themselves to be very closely +studied in a state of freedom. But these also grow very slowly, and +some have been met with whose size had extended quite enormously from +their first start. I ought to tell you, once for all, that this +indefinite growth, joined to extreme longevity, is found in many of +the inferior species whom we have yet to consider. It seems the portion +of these unfinished creatures, in which nature has only as it were +sketched in her work, and who seem vowed to endless youth, in testimony +of the state of childhood they represent, a state transitory among the +superior animals, but permanent with them. It belonged of right, +therefore, to the serpent, which is the most unfinished animal we have +yet met with, and who, at the first glance, seems almost reduced to +a mere digestive tube, lodged between a vertebral column and a series +of small ribs, whose number sometimes reaches three hundred. The liver, +which, with us, presents such a distinct and bulky mass, is here +elongated into a thin cord, which runs the whole length of the +oesophagus +and intestine, to the walls of which it is, to some extent, attached. + +It is the same with the lungs. There is rarely room for the full +development of two in this narrow conduit, where everything has to +follow the shape of the master of the house: one, therefore, is often +merely indicated by a very slight protuberance; the other, presenting +the appearance of a long tube, which extends nearly half-way down the +body, and whose feeble action halts periodically at each of those +monstrous repasts, after which the torpid animal becomes nothing but +a huge digesting machine. We have now reached the extreme limits of +that organization, the most perfect model of which we find in man, and +which is no longer to be recognized in fishes. + + + +LETTER XXXVI. + +PISCES. (_Fishes._) + +We are becoming terribly learned, my poor child, and I am half afraid +you will be getting tired of me. When I was little myself, I had rather +a fancy for breaking open those barking pasteboard dogs you know so +well; to see what was inside them. Why should you not, then, feel a +certain amount of interest in looking with me into the insides of real +animals? Still I cannot conceal from myself that the subject grows +very serious at last, and that while I am busied in struggling to make +myself intelligible through the endless crowd of facts which surround +me, I am apt to neglect chatting with you as we go along. Happily, +however, here is an opportunity for so doing. + +Up to the present time we have lived, as it were, upon the explanations +I gave you whilst studying the action of life in yourself, and all the +organs we have met with since, have been only, properly speaking, +reproductions, more or less exact, of those which you yourself possess. +But, in passing over into the kingdom of fishes, we find ourselves in +the presence of something altogether new, and I must go back to our +old familiar style of talking to open the subject. + +Take a water-bottle half-filled with water, and shake it well, and you +will see a quantity of white froth come to the surface of the liquid. +This is the air which having been drawn in by the water, as it went +up and down in the bottle, is now struggling to fly off again in bubbles +as fast as it can. But the whole of it does not get away; a small +portion remains behind, and melts, as it were, into the water, as a +morsel of sugar would do, taking up its abode therein. This seems odd +to you, but I will tell you how you may convince yourself of the fact. +Get a small white glass bottle, slightly rounded, and thin at the +bottom, if possible; fill it with water, and hold it for a short time +over a lighted taper. If you do this carefully there is no danger. You +will soon see tiny little balls, looking like drops of silver, rise +from the bottom of the bottle, come up to the surface, and burst. This +is the air which was installed in the water, as I described above, and +which is now running away from the heat of the candle, as the +inhabitants run away from a house on fire. After a time the whole will +have passed off, and the little balls will cease to rise. + +But what has all this to do with fishes? you ask. + +A very great deal, I assure you, dear child. If there had been a little +fish in your bottle, before it was exposed to the flame, it would have +found means to make use of that air, whose original presence in the +water you cannot refuse to believe after having seen it come out. It +is with this air that fishes breathe in the water. They do so rather +feebly, I admit; but, as if to make up to them for the small amount +of the air placed at their disposal, it contains more oxygen than that +we breathe ourselves, because oxygen, dissolving more readily in water +than nitrogen, is there in greater proportion. Of course, you do not +suppose that fishes have lungs like ours? I dare say you know the two +large openings on each side of their head, called _gills_, by which the +fishermen string them together to carry them away more easily? It is +there you will find their lungs, to which the name of _branchiae_, or +gills, has been given, because they are so different from other organs +of respiration that it was impossible to use one word for the two. The +arrangement of the gills varies considerably in the different species, +but their general form is the same everywhere. They are composed of a +number of plates, consisting of an infinitude of leaflets, arranged like +a fringe, and suspended by bony arches, into which plates and leaflets +the blood pours from a thousand invisible canals. + +First of all, then, we must see how blood circulates in fishes. + +Like reptiles, their heart has only one ventricle, and yet the arterial +and venous blood go each its separate way without the slightest risk +of being mixed; but this is because fishes have not that double system +of veins and arteries which hitherto we have always met with. The +venous blood goes to the heart, which drives it into the gills, from +whence it passes forward of its own accord, as arterial blood into the +organs, under the remote influence of the original impetus from the +heart, the newly-arrived blood incessantly driving the other before +it into the vessels of circulation. It does not flow very quickly, as +you may suppose; and as the heart is close to the head, its action is +but very feebly felt at the extremity of the body, when this happens +to be very long. Nature has, in consequence, taken pity on the eel, +whose tail is so far from its heart, and provided accordingly. Dr. +Marshall Hall has discovered near the tip a second, reinforcing heart, +so to speak, which has its own pulsations, independent of the pulsations +of the one above, and gives a fresh impetus to the sluggish blood, +[Footnote: Many observers refer this to the lymphatic system.--TR.] +which otherwise, as it would seem, would scarcely be able to accomplish +the long return journey. Finally, even with an additional heart in +thetail, the circulation among fishes is quite on a par with their +respiration. They have a melancholy steward, whose legs are very heavy, +and his pockets very light, and their life comes down a peg lower in +consequence. It is always the same life nevertheless--you must never +lose sight of that fact: it gets low in consequence of the imperfection +of the machine, but without changing its nature, any more than the +light in our different sorts of lighting apparatus. You remember that +comparison of the lamp with which I began my story, and which you could +not at the time see the full value of? From a dungeon lamp up to a +candle, you have always grease burning in the air at the end of the +threads of a wick. It does not burn equally well everywhere, and does +not always give the same amount of light; but that is all the +difference. From the mammal to the fish, it is always hydrogen and +carbon (as we have said of the grease) which oxygen sets on fire in +the human body at the fine-drawn extremities of the blood-vessels; +only the fire is lower in some than others, and the life with it. Let +us now look at the circulation of water in the fish's body. + +The gills communicate with the mouth by a sort of grating, formed by +the bony arches to which the gill-plates are suspended. The fish begins +by swallowing water, which then passes through the grating and +circulates round the innumerable leaflets of which each plate is +composed, and among which creep the blood-vessels. It is through the +thin coats of these leaflets that the mysterious exchange is made of +the unemployed oxygen in the water and the carbonic acid in the blood. +When this is over, the cover which closes the gills opens to let out +the water, and a fresh gulp takes its place; and so on continually. +When the fish is out of the water its gills fall together and dry up; +the course of the blood, already so weak, is interrupted by the breaking +down and shrinking of the vessels, and the animal can no longer breathe; +so that we have here the curious instance of a creature breathing +oxygen like ourselves, who is drowned, if we may use the expression, +in the air in which we find life, and lives in the water in which we +are drowned. While he is in the water matters take another course, and +his gills, moistened and supported, accommodate themselves perfectly +to the contact of the air, which desires nothing better than to give +up its oxygen to the blood, through the coats of the capillaries. +Accordingly you will often see fishes--carps, for example--come to +the surface of the water to inhale the air like a mammal or a reptile. +This is a valuable resource, which supplements the parsimonious +allowance of air given out to them by the water. There are even certain +fishes whose gills, more firmly closed than those of others, have, in +addition, a number of cells, which retain for a considerable time a +sufficient quantity of water to preserve the gills in their natural +state. These fishes can easily take an airing on land, where they +breathe the air as you or I do, and are downright amphibians. + +The most celebrated of these is the _Anabas_, or "climbing-fish." +an Indian fish, which not only can remain many days out of the water, +but also amuses itself by climbing up the palm trees--it is hard to +say how--and establishing itself in the little pools of water left by +the rain at the roots of the leaves. But we need not go to India to +find those wandering fishes. There is one of them living among ourselves +who can walk about in the grass, and I was talking to you about him +only just now--that is the eel. If you ever put eels in a fish-pond +you must, I assure you, try to make it agreeable to them, otherwise +they will have no scruple in setting politeness at defiance and moving +off to seek their fortune elsewhere. In a country walk, when the dew +is on the ground, you yourself may chance to come across one or two +of these gentlemen, who have had their reasons for changing their +residence, and whom you will see gliding so briskly along that they +will deceive you into taking them for snakes if you have not a very +experienced eye; so much so, that in certain parts of France where the +peasants ate snakes formerly, they reconciled themselves to the sickly +idea by christening them _hedgerow-eels_. + +On the other hand, fishes may be drowned in water just as easily as +ourselves if it does not contain air. The little fish who could have +lived very well in the bottle we were just now talking about before +you exposed it to the flame of the taper, would have died in it after +all the air-bubbles had gone off; and I hope I need not tell you why. +In the same way, if you leave fishes too long in a small quantity of +water without renewing it, they suffer exactly as we do if the air +which we breathe is not changed often enough. As soon as they have +consumed what oxygen is in the water, it can no longer keep them alive. +It is then, especially, you will see them come gasping to the surface +to call upon the air for help. Those who keep gold fish in a glass +bowl ought to know this, and to change their water oftener than is +generally done. When we take poor little creatures from their natural +way of life, and set a human providence over them in the place of the +Divine one which has hitherto been their safeguard, the least we can +do is to acquaint ourselves with the laws of their existence, so that +we may not expose them to the risk of suffering by our ignorance. +Finally, there are fishes whose gills, still more greedy of oxygen, +will not act well except in thoroughly aerated water, and who would +soon die in our tanks. This is the case with the trout, who is only +happy in the waters of hilly countries; rich with all the air they +have carried along with them as they fell from rock to rock. Now that +people are beginning to do with fishes what has long since been done +with sheep and oxen--keep them in flocks to have them always ready for +use--you may perhaps hear a good deal said about vessels made expressly +for the carriage of trout, with a thousand inventions besides for +sending air into the water, and you will not have to ask the meaning +of this now. + +I promised last time that I would revert in the chapter of fishes to +that marvellous transformation of the crocodile which has been explained +by the torrent of water he draws into his stomach. You could understand +nothing about it the other day; but after what we have just seen the +explanation suggests itself. Just as the extraordinary activity of +life in birds is explained by that double oxygenization of blood, of +which part takes place in the lungs and part in the reservoirs of air +placed everywhere in the way of the capillaries, so this sudden increase +of energy in the crocodile the moment it plunges into water may be +explained by a second respiration suddenly established in the vast +cavity of the abdomen, by the contact of the capillaries with the water +which penetrates there. Hence the crocodile would then have, like the +bird, a double respiration: only with him the one would be permanent +and from the lungs, the other temporary and from the stomach. By this, +on the one hand, he would rise up to the birds, since the blood +encounters air twice over in its course, while, at the same time, he +would plunge into the world of fishes, since the blood has to seek air +in the water. The above, be it remembered, is only a supposition, and +I ought to add that in this case there would be a good deal of danger +in observing nature at work, for in front of the laboratory, where she +is toiling in secret, stands on guard a row of teeth, by no means +encouraging to indiscreet intruders. At the same time, if there ever +were a legitimate conjecture, this is it. Everything seems to confirm +it; and if it be true, we should have in the crocodile a specimen of +each of the four systems adopted by nature for the mammal, the bird, +the reptile and the fish. At first I spoke of two, then of three; so +that even in my addition I was modestly below the mark, and had really +some grounds for recommending our friends the classifiers to beware +what they asserted in this case. + +Talking of puzzling classifications, this is just the place for +mentioning the _batrachians_, who have been made into a class by +themselves, but who most distinctly belong to two classes at the same +time; not like the crocodile by details borrowed from each, but by a +fundamental change which takes place at a certain period in their +organization. The batrachians are in reality reptiles, but they are +reptiles which begin by being fishes, and real fishes too. + +If you have ever strolled about in the country, you must have often +come across those great pools of water which collect at rainy seasons +in the ruts of deep lanes. Amuse yourself by looking into them in +early summer, and unless the land is too parched and dry, the chances +are that you will see quantities of little black fishes, almost entirely +composed of a long tail joined to a large head, playing jovially in +the muddy waters, and looking as if they had dropped there from the +skies. These are young frogs--_tadpoles_, as we call them--and +they are beginning their apprenticeship of life. Enclosed in each side +of those great heads, they have gills, and they breathe in the same +manner as fishes. Presently the two hind feet begin to bud out and +grow, little by little; then the fore feet; finally, the tail wastes +away till it disappears; and thus insensibly the tadpole is transformed +into a frog. Observe here that the tadpole's gills share the same fate +as his fish-tail; they wither and disappear by slow degrees, and +gradually as they do so, his lungs are developed. The animal changes +his class very quietly, and without ceasing to be genuinely the same, +although it would be impossible at last to recognize the old individual +in the new if you had not heard its history beforehand. This is one +of the most striking exemplifications I know of the mysterious process +by which nature has insensibly raised animals from one class to another, +always improving upon her original plan without ever abandoning it. + +On the shores of certain subterranean lakes which exist in Carniola, +a country subject at this time to Austria, there are to be found +batrachians far more ambitious than our frog--namely, the _proteans_. +These cumulate rather than change: they become reptiles without ceasing +to be fishes, if I may so express it; they develop lungs as they grow +up, and yet keep their gills. I could tell you a thousand other +particulars about these batrachians if I were to examine them all in +succession; for it is a very motley family, in the bosom of which the +transition from reptiles to fishes is in some imperceptible manner +accomplished; from the frog, which the unanimous consent of mankind has +always ranked among reptiles, to the axolotl or siren, who lives in +Mexican lakes; and who, feature for feature, is exactly like a carp, +with four little feet fastened under him. To be quite in order, the +batrachians ought to have followed the reptiles, for their interior +organization is the same; but how could I tell you about their gills +without explaining that there was air in the water? and I did not want, +for the sake of these intruders, whose babyhood-gills only just appear +and disappear, to rob the history of the fishes of its most interesting +points. + +Let us be satisfied, then, with this passing glance at a dubious class, +whose history is only a repetition of two others, and let us return +to our friends the fishes. We have seen how they breathe, now let us +look how they eat. + +The modifications of the digestive apparatus are endless among fishes. +The lampreys, who are placed in the lower ranks of the class, carry +out to its fullest extent the type which we have already seen indicated +in the serpent. The digestive tube is quite straight, without any +perceptible swelling, and does not even go the whole length of the +body. It comes to an end at some distance from the tail. Among some +fishes an odd tendency begins to display itself, which we shall meet +with again farther on. The digestive tube, after going downwards towards +the bottom of the body, as we have seen it do so constantly hitherto, +doubles back, and comes up again to the throat, under which it empties +itself. In most cases the stomach is distinct; but it assumes a thousand +different forms; as if nature had wished to try her hand in all sorts +of ways in the construction of these imperfect vertebrates, before +adopting the definite model which was to serve for the others. + +The liver is enormous, and generally contains a great quantity of oil, +the taste of which you will know if you have ever swallowed a spoonful +of cod-liver oil; but in most fishes its old companion, the +_pancreas_, has disappeared. In its stead you will find, close +by the outlet of the pylorus, the open ends of certain small tubes, +which are shut in at their upper extremity like a "blind alley," and +through which descends into the interstices a thick glairy fluid, given +out from their sides or walls. The result is the same, you see, although +the organ is different; and, remarkably enough, these little tubes are +wanting among fishes, which, like carp, have a species of salivary +glands in their mouths, of which the others show no trace; from which +one may fairly conclude that these glands and tubes mutually supply +each other's places. Here, then, you see an instance of the light which +different animal organisations throw upon each other when they are +compared together. In fact, this one establishes pretty clearly the +real office of the pancreas in the higher races, exhibiting it to us +as an internal salivary gland, intended to complete the work only begun +by those in the mouth, in the case of lazy people who swallow their +food too quickly. + +There is the same diversity in the mouth as in the intestine. Some +fishes, like the skate, have no tongue at all. Others, instead of a +tongue, have a hard dry filament, very nearly immovable, and which one +would think was put there like a stake, to show the place where the +tongue is to be found in the more perfect organisations. There are +even fishes, like the perch and the pike, whose tongue is furnished +with teeth, or rather fangs; an evident sign that it has forfeited the +confidential position occupied by your own good little porter. You +must know also that the perch and the pike, like many other of their +fellows, have teeth all over the mouth. This invasion of the palate +by teeth, which began in the lizard and the serpent, assumes alarming +proportions here. It is not merely the roof of the palate which is +spiked with teeth: above, below, at the sides, everywhere to the very +limits of the oesophagus, the little fangs triumphantly stick out their +slender points. It is impossible, therefore, to state their number. +Nature has scattered them broadcast without counting, just as she has +done with the hairs of the beard round the human mouth; and the +comparison is not so impertinent as you may think. They sometimes form +an actual internal beard, even thicker than our outer one, and which +sprouts from the skin into the bargain. There is one fish whose teeth +are so delicate and so close together that, in passing your finger +over them, you would think you were touching velvet. This does not +refer to the shark, mind. His teeth are sharp-cutting notched blades, +hard as steel, arranged in threatening rows round the entrance of his +mouth, and cut a man in two as easily as your incisors do a piece of +apple. Others, such as the skate, have their mouths paved--that is the +proper term--with perfectly flat teeth. The first time your mamma is +sending to buy fish beg her to let you have a skate's head to look at. +You will be interested to see the small square ivory plates laid close +adjoining each other, like the tiles of a church floor. It is in fact +a regular hall-pavement, over which the visitors glide untouched, and +are then swallowed down in the lump; thus entering straight into the +house without having been stopped by the inscription nature has placed +over your door and mine--"Speak to the Porter." + +But all this is nothing compared to the lamprey's entrance-hall, which +differs from ours in quite another way. The lamprey, as I have already +told you, ranks almost lowest among fishes, and consequently among +vertebrate animals, of which fishes form the rear-guard. Indeed, it +is almost stretching a point to consider her worthy to bear the proud +title of a vertebrate at all; for the vertebral column, so clearly +marked in other fishes, where it forms the large central bone, is only +faintly indicated in certain species of lampreys, by a soft thread (or +filament), which is rather a membrane than a bony chaplet, and at the +top of this mockery of a vertebral column is the creature's mouth. If +you ever had leeches on, you will remember the sharp sting you felt +when the little beasts bit you. Well, the lamprey feeds herself just +in the same way as the leech does. Her mouth forms a completely circular +ring, which sticks to the prey, and through which runs backward and +forward a small tongue armed with lancets. This darts out to pierce +the skin, and draws in the blood as it retreats. Round your lips well; +dip them so into a glass of water, and draw back your tongue, and you +will at once feel the water rise into your mouth. It is by a similar +sort of proceeding that leeches relieve people of the blood they want +to get rid of; and in the same way the lamprey draws out the blood of +the animals upon which she fastens. + +What a long way we have come already! How very far we find ourselves +here from the little mouths we first talked about as chewing their +eatables so prettily! With the lamprey we bid adieu to the class +Vertebrata--the nobility of the animal kingdom--among whom nevertheless +we must distinguish between the peer, who approaches nearest the person +of his sovereign, and the inferior provincial lords who live at a +hundred miles' distance. There is only one step from the lamprey to +the _mollusks_ or soft-bodied animals, and this is the course +which animal organisation seems really to have taken in its progress. +But nature never moves forward in a single straight line. In passing +from the mollusk to the fish to get thence to the higher vertebrates, +she turned aside in another direction toward a class of animals which +rises far above mollusks, but which leads to nothing beyond. + +One would think there had been a check here, as if the creative power, +having discovered that it was going in a wrong direction, had retraced +its steps; if it be allowable to apply common ideas and expressions +to our conceptions of that Great Intelligence which has arranged the +plan of the mysterious ladder of animal life. + +The animals we must examine next, on account of their superiority to +the rest, are insects. Small as the ant is, it would not be right to +let her be preceded by the oyster. + + + +LETTER XXXVII. + +INSECTA. (_Insects._) + +Before speaking of insects, my dear child, it will be necessary, in +the first place, to tell you to what primary division they belong and +on what characters this division has been established. And here I find +myself in a difficulty. We have been but too learned already, and now +we run the risk of becoming still more so, if we commence an attack +on the three primary divisions which follow the vertebrates. We shall +have to encounter terrible names and tedious details, besides having +to take into account a thousand things of which we have not yet spoken. +We are going on quietly with the history of the feeding machine which +occupies the middle of the body, and learned men never looked in that +direction for the establishment of their divisions; between ourselves, +it was not accommodating enough. They have fallen back upon the +locomotive apparatus (_movement machine_) which affects the body +all over, and which they have proclaimed to be the leading feature of +the animal organization, without noticing however that it is, after +all, but the servant of the other. It is true that the great divisions +are more easily established upon this point than the other, because +the differences are more decided. It separates what the other unites, +and thus it is that nature carries on that beautiful combination which +the Germans have so accurately named "_Unity in Variety_" that +is to say, she is always at work, as I have already told you, on the +same canvas, but always embroidering it with a different pattern. +Wait! I have something to promise, if you are very good, and if this +history (that of the feeding machine) should have given you a taste +for inquiry. I will tell you another time the history of the movement +machine, and there the classification of our learned men will come in +naturally very well. In the meantime we will do as they do, and just +shut our eyes to their divisions, in which the feeding machine can +have no interest, because they were established without reference to +it. We will content ourselves, then, without further pretension to +science, with modestly examining the last transformations of our pet +machine in the principal groups of the inferior animals; of which +groups I will now tell you the names in their proper order. They are +as follows: Insects, Crustaceans, Mollusks, Worms, and Zoophytes. You +must take these names on trust; those which you do not understand will +be explained in their places. + +1. _Insects._--I know not where it was I once read that there are +said to be something like a hundred thousand different species of +insects; and I verily believe this is not all. Of course we shall not +attempt to review the whole of this formidable battalion. Let us take +one of those you are most familiar with--the cockchafer, for instance-- +and examine what goes on in his inside. The history is nearly that of +all the others. + +"Fly away, cockchafer, fly!" says the song; and surely it is a bird +that we have here, and a bird which will appear to you even more +wonderful than those of which I have already spoken, when you have +considered the simplicity, and at the same time the strength, of his +organization. His mode of flight is rather lumbering, it is true; he +is, in comparison with the large flies, what the ox is to the deer; +but when you contrast the weight of his thick body with the delicacy +and narrow dimensions of the two membranes which sustain him in the +air, you may well ask yourself how those little morsels of wings, thin +as gold-beater's skin, can carry such a mass along. In fact, they only +accomplish this feat of strength by dint of an excess of activity +almost startling to think of. When you run as fast as you can, how +many times, think you, do you move your legs in one second? You would +be somewhat puzzled to say; and so should I: but I defy you to count +ten. Now the bird makes his wing move much oftener when he beats the +air with rapid blows as he flies; but even he does not strike a hundred +strokes in a second: and what is this to the feats of the cockchafer's +wing? It is not hundreds but thousands of times that he flaps his wings +in a second; and here let me hint, by-the-by, that when people seriously +wish to find out a method of travelling in the air, they will lay aside +balloons, of which they can make nothing in their present condition, +and will set to work to fabricate machines with wings which shall beat +the air as fast as those of the cockchafer. This sounds extravagant, +but I have seen an electric pile fixed in a stand with glass feet, +which caused a little hammer to beat thousands of times in a second: +and surely the hammer could have been made to communicate its movement +to a small wing! Forgive me this little castle in the air! The idea +came into my head a long while ago, and the cockchafer has just reminded +me of it. I will not, however, pursue the subject, neither will I offer +to explain the method used for counting the beats of an insect's wing. +That would carry us farther than would be desirable. + +To return to our little animal. I leave you to imagine the enormous +amount of strength required for such precipitate motion. We have spoken +of the rapid course of the blood in birds during flight: who shall +calculate its comparative rate in this fabulously wonderful locomotive, +the cockchafer? And if we lift up the cuirass which encases it, what +do we behold? Not a single trace of all the complicated +circulation-apparatus you have learnt to know so well; neither heart +nor veins nor arteries; only a quantity of whitish liquid, equally +distributed throughout the whole internal cavity. Not a trace of lungs, +nor any apparent means of renovation for this seemingly motionless +blood; for blood it is, in spite of its color, or, at any rate, blood +in its first stage of formation. It also has its globules--ill-formed, +it is true, and altogether in balls--like those found in the chyle +with us; which chyle, be it observed, is the same color as the blood +of insects, and may also be considered blood in its apprenticeship. +By what magic, then, is this raw, imperfectly-formed steward, who seems +altogether stationary, enabled to accomplish exploits which would +stagger his higher-bred compeers, agile and perfected as they are? +Where does he pick up the oxygen necessary for such repeated movements, +it being an established fact that no animal can move at all without +consuming oxygen, and that the quantity consumed is in proportion to +the rate of motion? Look under his wings for an answer. There, all +along his body, you will observe a number of small holes, pierced in +a line, at regular distances, and furnished with shutters of two kinds. +They are the mouths of what are called _tracheæ_, or breathing +tubes: and from them branch out a multitude of little canals, which, +spreading in endless ramifications through every part of the body, +convey to the whole mass of the blood, from all directions, the air +which makes its way into them through the tracheal holes. In this case, +you see, it is not the blood which seeks the air, but the air which +seeks the blood; whence arises a new system of circulation, whose +action is all the more energetic because it is unintermitting, and +makes itself felt everywhere at the same time. A little while ago we +were wondering at the twofold respiration of birds; yet this is far +less surprising than the universally-diffused respiration of insects, +who may well be able to do without lungs, seeing that their whole body +is one vast lung in itself. + +For the rest, do not trust to appearances, nor imagine that the blood +of our friend the cockchafer in reality remains motionless around the +air-tubes, idly drinking in the oxygen which is brought to it. Though +not flowing in enclosed canals, it is not the less continually displaced +by regular currents, which sweep through and renew this apparently +stagnant pool. Nor is this the only instance of such a current presented +to us by nature. + +Guess, however, if you can, where you will have to look for the +counterpart to the circulation of the cockchafer. In ocean itself! +But, remember, nothing is absolutely little or great in nature, who +applies her laws indifferently to a world as to an atom. The blood of +our world is water, which contains in itself all the germs of fertility, +and without which, as I have already told you, life is impossible +either in the animal or vegetable kingdom. The water of brooks, streams, +and rivers, flows along in channels, which, when figured in a map, +present to the eye of the beholder an exact picture of the system of +circulation found in the vertebrated animals. But the waters of the +sea are borne along, like the blood of insects, by a secret circulation, +which cannot be represented on the map; _i.e._ by immense currents +everlastingly in action, some on the surface, some in the mid-heart +of the ocean, which drive it in ceaseless course from the equator to +the poles, from the poles to the equator; so that the Supreme +Intelligence, in His overruling providence, has ordained the same law +to set in movement the immensity of ocean, and to effect circulation +in the cockchafer's few drops of blood. In the latter we find the +moving agent to be a long tube, which runs the whole length of the +back, and is called the dorsal vessel (from the Latin _dorsum_, +back). I told you that the cockchafer had no heart under his cuirass, +but I spoke too hastily. The dorsal vessel is a _true heart_, but +a heart devoid of veins or arteries, and thrown into the midst of the +blood. It dilates and contracts like ours, sucks in the blood by means +of side-valves, which act as our own do, and drives it back again into +the mass by that valve at its extremities, which opens near the head. +From thence arises a continued to-and-fro movement, which sends the +blood from the head to the tail, and brings it back again from the +tail to the head. But who would recognise, in this simple primitive +organisation, where all seems to go on of its own accord, as it were, +the same machine, with all its complicated movements, that we have +been so long considering? + +Well, in this apparently universal shipwreck of all the organs we know +so well, there is yet one which survives, and remains the same as ever, +namely, the digestive tube. I began by saying the insect is a bird. +His digestive tube is formed upon the same pattern as that of birds, +so that naturalists have bestowed the same names on the various parts +in each of them. After the oesophagus comes a crop (_jabot_), very +distinctly indicated; then a gizzard with thick coats, in which the +food is ground down. The hen, if you remember, swallows small pebbles, +which perform in her gizzard the office of the teeth in our mouths. +The cockchafer has no need to swallow anything. His gizzard is furnished +with little pieces of horn; real teeth, fixed in their places, which +have a great advantage over the chance teeth picked up at random by +the hen. I pointed out to you in birds, between the crop and the +gizzard, a swelling or enlargement of the digestive tube, pitted with +small holes, where the food is moistened by juices. The same enlargement +is found here, covered all over with a multitude of small tubes, which +might easily be mistaken for hairs, from which also falls a perfect +shower of juices. The only difference is, that it comes after the +gizzard, instead of before it, as in birds. Some naturalists, +considering that the manufacture of chyle takes place here, have called +it the _chylific ventricle;_ [Footnote: The corresponding +protuberance of the birds bears a name, somewhat similar, but stillmore +barbarous. I had passed it over in silence, because, I make the +confession in all humility, I do not understand it; but a remorse now +seizes me: it is called the _Ventricule succenturie._] a somewhat +barbarous name, but one which explains itself, and might with truth +be applied to the _duodenum_ of the higher animals. Bile is poured +in close to the hinder end of it, but you must not look for the liver; +it has disappeared, or rather its form is entirely changed. You remember +what the _pancreas_ had become in fishes; _i.e._ a row of tubes giving +out a _salivary fluid._ Such is exactly the appearance of the liver in +the cockchafer. + +Instead of that fleshy substance on which hitherto the office of +preparing the bile had devolved, you see nothing but a floating bundle +of long loose tubes, which, opening into the intestines, pour in their +bile. The organ is transformed, but we recognise it again by the office +it performs, which continues the same. As to the _pancreas_ it is +wanting here, as in the fish with salivary glands; but in its place +in many insects other tubes, acting also as glands, pour saliva into +the _pharynx; i. e._, the cavity at the back of the throat. + +As you see, therefore, everything is found complete in this tube of +a few inches long; and you can also distinguish there a small and a +large intestine. We are speaking of the cockchafer, which feeds on the +leaves of trees; and it is for this reason I name some inches as the +length of the digestive tube. This would not be longer than the body +itself, had it been destined, as in the case of many other insects, +to receive animal food. In fact, the law which we have shown to exist +with regard to the ox and the lion, rules also over the insect-world; +and whilst a radical change seems to have been made in the rest of the +organisation, here everything is in its place, and we find ourselves +in the same system. + +Was I not justified in asserting that the unity of the animal plan is +to be found in the digestive tube? and that this is the unchanging +basis upon which the Creator of the animal world had raised his varied +constructions? + +How would it be, then, if we were to take the insect from its +starting-point when it is only a worm, that is to say, merely and +simply a digestive tube? for I am only telling you a small portion of +its history here; a history you must know, which reveals a miracle +still more wonderful than the transformation of the little tadpole +into the frog! There is a brilliant-colored fly which comes buzzing +about the meat-safe--the bluebottle--do you know her? It is on her +account that we put large covers of iron wire over the dishes of meat; +but, perhaps, you never troubled yourself to think why. + +But the truth is, she only comes there to deposit her eggs in the good +roast-meat; and if she could get near enough to do so, you would soon +afterwards see it swarming with little white worms, which would entirely +take away all your appetite. These worms are only flies out at nurse, +and they will find their wings by-and-by if you only give them time +enough. Disgusting as they may appear on a dining-table, I assure you +they deserve more interest than you may think. When we come to speak +of worms, we will ask of them to let out the secret of the mysterious +transformations of animals. + +In the meantime, let us finish the observations we were making on the +_perfect insect_, as this little creature is called when he has +passed through the intermediate stages which separate him from the +undeveloped condition. Forgive me, my dear child, here I am speaking +to you as if you were a grown-up woman! This is because it is so +difficult to explain things of this sort in any other way. And now +that you have been introduced into the midst of the wonders of creation, +you ought to familiarise yourself with the ideas and terms they have +suggested to mankind. I began with you as a child, and great would be +my triumph if I could leave you a grown-up girl! And I flatter myself +that I have so far set your brain, to work, under pretence of amusing +you, that this hope is not altogether unfounded. I found it necessary +to say this to you in confidence, because I have just read over our +first conversations, and perceive that I have insensibly put you on +a different diet from the one I began with. I am obliged to comfort +myself by remembering that you have grown older since, and that you +are now acquainted with a great many things which you had never heard +spoken of then. And this is the secret of all transformations. We crept +on at first over ground that was quite unknown to us; but as we went +along, our wings must have begun to grow, and we are now able to fly +a little! + +Do not be afraid, however; I will exercise your tiny butterfly-wings +very carefully just at present. We have only to examine what becomes +of the _chyle_ of the cockchafer after it has been prepared in +the pretty little tube so finely wrought. We men have _chyliferous_ +vessels which draw up chyle from the intestines and throw it within +a short distance of the heart, into the torrent of blood, where its +education is completed. But the cockchafer, who has no other vessels +than his air-pipes, and the _dorsal tube_, which has no communication +with the intestines, what is he to do? Do not distress yourself about +him. Make a tube of a bit of linen, well sewn together, and fill it with +water. Sew it together as firmly as you may on all sides, the water will +have no difficulty in escaping through the meshes. And this is just what +happens with the little tubes found in animals, the coats of which are +formed of interwoven fibres. By-the-by, from thence comes their name of +"_tissue_," which they share in common with all the solid substances of +the body, for all were once supposed to have the same general structure. +The intestine of the cockchafer floats, did I not say? in the lake of +blood which fills the whole cavity of the body. Well, then, the chyle +has only to penetrate through these coats, to go where it is wanted. +Hence it is not at all surprising that this blood should be white; and I +have very good reasons just now for comparing it to our _chyle_. It is, +indeed, chyle arriving directly from the place of its manufacture, +without undergoing any other process; by which you may see that this +little machine (of the digestive organs of the cockchafer), though +differing in appearance so entirely from our own, is reducible to the +same elements of construction, and that life is maintained by the same +process as with us; namely, by the action of the air upon the albumen +extracted from food. The cockchafer, it is true, is much further removed +from being a fellow-creature of ours than even the horse; but the +principle of life is the same with him as with us. And this is quite +enough to cause children, who can feel and reason, to think twice before +they begin to torture, by way of amusement, a creature whose life the +God of goodness has subjected to the same conditions as our own. I speak +this to those miserable little executioners who make toys of suffering +animals: but the case is different with agriculturists, who have +necessarily to contend with the devourers of their harvests, and whom, +I admit, it would not be reasonable to bind down by the maxim of Uncle +Toby. + +[Footnote: I have introduced my Uncle Toby, who really has nothing +to do here, in order to make you acquainted with a few lines of Sterne, +which I wish I could place before the eyes of every child in the world. + +"Go!" said he, one day at table, to an enormous fly which had been +buzzing around his nose and had cruelly tormented him all dinner time. +After many attempts, he finally caught him in his hand. "Go! I will +not do thee any harm," said my Uncle Toby, rising and crossing the +room with the fly in his hand; "I would not hurt a hair of your head. +Go!" said he, opening the window and his hand at the same moment, to +let the fly escape; "go, poor little devil; away with you; why should +I do you any harm? the world is certainly large enough to contain both +of us!"] + +But now to finish with the cockchafer. We have got to examine one very +important part of his body, that which in other animals has been the +one most talked about ever since we began our study: I mean the mouth. +You know that this is the essentially variable point in the digestive +tube; so that you will not be much surprised, should we find he has +something altogether new. The mouth of the cockchafer is composed of +a great number of small pieces placed externally round the entrance +to the _alimentary canal_; but the names of these, as they would +not interest you, I will not enter upon with you; more especially as +they refer to such tiny morsels, that you would have great difficulty +in finding them again on the owner. Of these pieces only two are worth +our attention. These are two bits of extremely hard horn, placed one +on each side of the animal, which are called "_mandibles_" and +which serve the cockchafer to cut up the leaves which he eats. Fancy +your share of teeth being two huge things fixed in the two corners of +your mouth, each advancing alone against the other till they meet under +the nose! You would then attack your tarts with the weapons of the +cockchafer! You would not, however, be able to bite them straight +through from the top to the bottom, as is done by all the animals whom +we have yet seen. It is this which so peculiarly distinguishes the +insect's manner of feeding; for we have already been taught by the +bird and the tortoise, that it is possible to eat with two pieces of +horn. The cockchafer now shows us how to eat sideways; but this is +merely an accessory detail. It does not affect what happens after the +mouthful is swallowed. All insects, however, have not this peculiarity. +The cockchafer belongs to the category of grinding insects as they are +called, who bite their food: but there is the category of the sucking +insects (or suckers), whose food consists of liquids; and these insects +are furnished in a different manner. + +In the innocent butterfly, who lives on the juice of flowers, the +digestive tube terminates externally in a sort of _trunk,_ twisted +in several convolutions, which is nothing more than an exaggerated +elongation of the two jaws, which become hollow within, and form a +tube when joined together. When the insect alights on a flower, he +suddenly unrolls this trunk, and sucks in the juices from the depth +of its "corolla," as you would drink up liquid with a straw from the +bottom of a small vial. Amuse yourself some summer's day by watching +a butterfly in his labors amongst the flowers: sometimes he stops +still, but oftener he is contented to hover over them; and, as he does +so, you will see a little loose thread, as it were, move backwards and +forwards as fast as possible: this is his trunk, which he darts out, +while flying, into the corolla of the flowers, but which scarcely seems +to touch them, so delicate is its approach. + +Less inoffensive far is the trunk of the mosquito-gnat, and of all the +detestable troop of blood-sucking flies. It is always a tube; but this +tube is no longer a simple straw, but a sheath furnished with stilettos +of such exquisite delicacy and temper, that nothing is comparable to +them; and these, as they play up and down, pierce the skin of the +victim, like the lancets of the lamprey, and, like them, draw in blood +as they retreat. + +Finally, amongst the _parasites,_ the last and lowest group of +insects, the stiletto-sheath is reduced to the size of a kind of little +tube-shaped beak, which, when not in use, folds down like the fangs +of the rattlesnake. + +You do not know, perhaps, what a parasite is. The word comes from the +Greek, and signifies literally, "_that which moves round the +corn._" The Greeks applied it to those shameless paupers who, to +escape honest labor, made their way into the houses of the great, and +enjoyed themselves at their expense. These parasites are little animals +which settle themselves on large ones, to suck in, without having +worked for it, the blood which the others have manufactured. The wolf +hunts, fights, and tears its victim in pieces; and then, by means of +that interior labor which I have spent so much time in describing, +transforms it into nourishing liquid: and when all this is accomplished, +the little flea, who lives hidden among his hairs, coolly draws out +for his own use the valuable blood obtained with so much effort. There +are many parasites in the world, my dear child--yourself, for instance, +to begin with--who are perfectly happy to chew your bread without +asking where the corn comes from which made it. But you have heart +enough to see plainly that this indifference ought not to last, and +that it is not honorable to go on living in this indefinite manner at +other people's cost only. + +You will some day have duties to fulfil, which you should accustom +yourself to think of now, in order that you may prepare yourself for +them beforehand, so that it may never hereafter be said of you that +you passed through the midst of human society, taking from it all you +needed, without giving it back anything in return, I advise you to +conjure up this idea when the time comes to leave off playing and begin +preparing to be of use. The sort of thing is not always very amusing, +I admit, but you must look upon it as the ladder by which you will be +enabled to rise from the degradation of a parasitical life. If you +were in a well, and some one were to let down a real ladder for you +to get up by, I do not think you would complain of the difficulty of +using it. It is for you, then, to consider whether you would like to +remain for ever in your present condition; for those who learn nothing, +who _submit_ to nothing, who are good for nothing, but to show +off and amuse themselves--these remain parasites all their lives in +reality, however little they may sometimes seem to suspect it. + +At your age, however, there is still no disgrace in the matter. God +shows us by the insects that little things are allowed to be +parasitical; but on this subject I must return to a point in the history +of animals which I touched upon before. I told you, in speaking of the +crocodile, that the perfect state of the inferior animals is found +represented in the infancy or less perfect state of those above them: +and I may say the same again with regard to insects. All the young of +the mammalia begin life as parasites, at least, as sucking animals: +for they all live at first on their mother's milk, which is nothing +more than blood in a peculiar state. But the name of parasite among +insects is generally confined to those which take up their abode on +the bodies of their hosts; though in common justice it might equally +well be applied to the gnat and his relations, who, when once full, +make their bow and are off, like the kitten when he has finished +sucking. Well, without meaning to find fault, if we descend to the +lower ranks of the mammals, we shall find among them many parasites +in the received sense of the word. You remember the pouch to which the +marsupials owe their odd name. The young kangaroo remains hidden for +months in the pouch of its mother, feeding continually all the time; +and it is then a strict parasite. During the four following months it +goes in and out, and strolls about between meals, like other young +ones of its class, and is then an animal at nurse affording thus a +twofold example of the tendency of the great Creator to repeat Himself +in His conceptions, here using for the infancy of the mammal the system +invented for adult insects--elsewhere repeating the butterfly in the +humming-bird, who may fairly be called a vertebrated butterfly, and +reproducing the gnat in the vampire-bat, which I look upon as an +enlarged and perfected revise of the original pattern, whence comes +the scourge of our sweet summer nights. + +And now, surely, I have said enough about these parasites, whose very +name, I suspect, will make you shudder after my impertinent application +of it. Never mind: it depends entirely upon yourself to get rid of +whatever you find humiliating in the position I have hinted at. Do all +you can to bring happiness to the parents on whom you live at present, +and who give their life-blood so willingly for your good. God has made +you very different from those little animals who have neither heart +nor reason to guide them. Do not be like them, then, in conduct. By +a little obedience and love--child as you are--you can pay them back +what you owe, and they will never complain of the bargain. + + + +LETTER XXXVIII. + +CRUSTACEA--MOLLUSCA. (_Crustaceans and Mollusks._) + +_Crustaceans._ + +Crustaceans consist of cray-fish, crabs, lobsters, and prawns, who may +be considered cousins-german of insects, among which more than one +naturalist has thought they ought to be placed. Like them they are +divided into _grinders_, having the same action of the mandibles; +and _suckers_, who are also parasites, and have tubular sheaths +containing stilettos. Mammals and birds are the victims of parasitical +insects; fishes have been reserved for the crustaceans, who do not +disdain also to fasten upon their humble neighbors, the mollusks; and +even among themselves the little ones settle down on the great. A few +live on land, but an immense majority in water, and seem destined to +represent, in the aquatic world, the aerial class of insects, from +whom, however, they differ in many ways. + +The first difference is in that stony crust with which they are +enveloped, like the cockchafer in his horny cuirass, and which you +must know well enough if you have ever eaten lobster. Wherever we meet +with horn in insects, we find stone in crustaceans. The jaws are stony, +and the teeth of the stomach also. They are constructed on the same +plan, only the materials are changed. + +The digestive tube is less complicated, and consists merely of one +large stomach, instead of that series of stomachs by which insects +approach the organisation of birds. On the other hand, if among some +of them the liver is reduced to simple tubes, floating loosely in the +body, as we have just seen it in the cockchafer among insects, these +tubes are generally so profusely multiplied, and press so closely +against each other, that they form a large compact lump--a true liver, +to sum up all--from which issues, as from ours, a _choledochian +canal_, a bile duct, _i. e._, which passes out into the intestine at the +entrance of the pylorus. + +You recollect that canal of the liver which I was afraid to tell you +the name of because it was so ugly? Well, this is that formidable name! +Now that you have swallowed so many others, you must be strong enough +to digest this. + +No chyliferous vessels have been found in crustaceans, whence one may +conclude that the chyle leaves the intestine by oozing from it, just +as it does in insects. There it gives rise to an almost transparent +sort of blood, a kind of sap, or lymph, which is put in motion by a +genuine circulation-apparatus; a real heart, with all its canals. This +heart has only one ventricle, and only sends blood in one direction, +as in the case of fishes; but there is an essential difference between +them, which we must point out. The heart of fishes may be called a +venous heart, since it only receives venous blood, which passes thence +to the gills, while that of crustaceans is an arterial heart. It +receives the blood directly it leaves the respiratory organ, and sends +it, not into one aorta, but into several arteries, which set out at +once, each in its own direction, to nourish the various quarters of +the body. This greatly resembles the system of circulation, with which +we are already acquainted. The veins only are unsatisfactory. They +form a kind of transition between the uncertain currents which convey +the blood of insects from one end to the other of the cavity in which +these strange organs lie bathed, and the closed canals of the higher +animals. But they are not canals, properly speaking. The irregular +intervals which separate the organs, more numerous here, are enclosed +by membranes, between which the venous blood pours, and naturally the +chyle also. The whole thus arrives at certain excavations formed at +the place where the legs are jointed on to the body--reservoirs, so +to speak--where the real canals come to carry it off and convey it +away into the gills. + +It is, in fact, by means of gills that crustaceans breathe in their +character of aquatic animals. These gills are made nearly upon the +same model as we have already seen in those of fishes; and although +their form and arrangement differ in different species, yet the +principle is always the same: they are tufts of leaflets springing +from stems, up and down which run two tubes; one which brings the blood +from the venous reservoirs, the other which carries it to the heart. +Crabs, lobsters, and crayfish, who are the "file-leaders" of the +crustacean tribe, have gills enclosed in the body, as fishes have; but +the circulation of the water goes in a contrary direction to theirs, +as does that of the blood. Instead of entering at the mouth and going +out at the sides, as we have seen, it enters at the edge of the bony +shell which covers over the body and comes out near the mouth--a merely +accidental detail which does not in any way alter the play of the +apparatus. All these animals are equally adapted for swimming and for +walking, crabs especially, their gills accommodating themselves without +difficulty to contact with the outer air, as we have seen among certain +fishes; so that one might class them with amphibians. There is even one +crab who has acquired the name of _land-crab_, because, although he has +got gills, he dies in water, the small amount of air he can get out of +it at a time being insufficient for him, and who, therefore, lives +constantly on land. It is true that he seeks out damp spots, for his +gills would also fail him if they became parched, and, like the fishes +who make excursions on dry land, he is provided with an internal +reservoir, which is always filled with a certain quantity of water. + +Some aquatic crustaceans have the labor simplified by external gills, +which hang down into the water, sometimes depending from the stomach, +sometimes from the legs. In France you sometimes see at a table certain +little animals, very like shrimps (_squillæ_), the bases of whose +hinder legs are fringed by slender tufts, which are in fact their +gills. They find themselves placed there just within reach of the +venous blood; for in the body opposite the bases of the legs are little +cavities in which it accumulates. Now these gills can only act when +under water, and so the squillæ dies as soon as he is removed from +that protecting element. For the same reason they cannot be kept long, +nor travel far, much to the regret of those who like them and live at +some distance from the sea. + +There are other crustaceans, next-door neighbors of the squilla, whose +gills are still more simplified. Here the legs themselves are turned +into extremely thin plates, which play the part of gills, and are thus +organs for two purposes, serving at the same time to swim and breathe +with. + +We have in our house one little crustacean, the only one I know of who +associates with men, and that is the wood-louse. You must know the +little grizzly beast, which rolls itself up into a ball whenever it +thinks itself in danger, and who would be taken for an insect by anyone +who was not taught otherwise. The wood-louse has neither gills hanging +down outside, nor anything inside her body which resembles the breathing +apparatus of her great relations. But, on examining her closely, you +will perceive all along her stomach a series of little plates, which +are her breathing-organs, and which come under the class of gills, +because, like other gills, they require a certain degree of moisture +to make them act properly. You will never, therefore, see a wood-louse +strutting about in the sunshine, where he would dry up far too quickly; +but if ever you get into a dark, damp corner, there you have every +chance of finding one. + +Animals who breathe through their legs and through their stomachs! You +are astonished, and ask, What are we coming to? What would you say, +then, if I were to go really to the depths of the crustacean world? +We should find there such extraordinary beings as you can form no +notion of, for they all live down below in the sea, and have no special +breathing-organ at all, inasmuch as they breathe through the whole +surface of the body. Do not exclaim yet! I will soon show you one whom +you know perfectly well, and who has no other way of breathing. + +But we must keep to the higher crustaceans, if we want to judge of the +class. By going too low, we run the risk of not seeing clearly. Animal +creation is here on a system of experiments: and they are so endlessly +multiplied, and exhibit such a profusion both of deceptive resemblances, +and of differences which disappear by transformations, that +classification no longer knows which way to turn. Worms, crustaceans, +mollusks; to which group do these and those belong? To which ever we +like to refer them, for these groups represent nothing definitely +determined in the plan of creation; and though easy to be distinguished +from each other in the higher branches, they become confused together +in the lower, like mountain summits which spring from a common base, +at the foot of which they are all united together. + +On this account, my dear child, you will, I am sure, excuse me now and +henceforth, from entering into details of all the horrible beasts which +swarm in the shallows of the animal world, and whom learned men have +in their wonderful wisdom muffled up in terrible names, in order to +prevent children from coming near them! What would you have thought +of the poor little squilla, so prettily baptised by the fishermen, if +I had taught you that it belonged to the order of _Stomatopoda_? +You will scarcely be able to pronounce the word; but that is no fault +of mine, it is spelt so. + +We will content ourselves, then, with having taken a glance at the +most clearly marked individuals; and as I said to you just now, it is +by them that we will arrange our inventory of the groups. Here, as you +may have already remarked, instead of continuing to wander from the +original model whose gradual deterioration we have been following all +this time from one class to another, it would seem that we are retracing +our steps, and regaining some portion of the lost ground. This is +because insects, as I have already stated, are an exceptional case--an +idea apart from the great general plan--a by-lane turning off from one +side of the great line of animal creation. + +The crustacean, less perfectly worked out than the insect assuredly, +but more regular, forms, so to speak, the connecting line between that +tiny masterpiece of fancy, so incomplete in its exquisite organisation, +and the shapeless but better constituted lump of the mollusk, who +conceals under his heavy shell the sacred deposit of real organs, those +which we expect to find always and everywhere. An insect outside, +though less refined it is true, a mollusk within, the crustacean reminds +me of what among us is called an _amateur_--that mild lover of +the arts who holds a middle place, as it were, between the artist and +the common citizen. + +I regret that you are not at present quite able to appreciate my +comparison fully: but put it by, in reserve, if possible, in your +memory; you will find out hereafter how just it is, and it will, +perhaps, help to prevent you from always setting the lively, noisy +artist, above the quiet and silent citizen. Let this, however, be +between you and me. If they could hear us talking, neither artist nor +citizen would forgive me, and the amateur still less. + +_Mollusks._ + +There is one mollusk universally well known--namely, the oyster--so +we will choose him for discussion. To look on one's plate at that +little mass of soft, compact substance, one feels inclined to ask what +there can possibly be in common between it and us; and if you were to +declare that there was not the faintest trace of resemblance between +the organization of the oyster and our own, I should not be surprised. +Wiser people than you have been caught tripping there; not that they +were ignorant of the points in which the oyster resembled us, but they +paid no attention to them. Viewing it in other respects, they declared +that it was of a structure completely different to our own; and that, +in the construction of this machine, the Creator had worked upon a +particular plan, laid aside afterwards as useless for any other purpose. + +I should like to get hold of one of those Academicians, with thirty-six +plans, and confound him before you, in proof of his relationship to +the oyster, by showing you at one sitting that there is an oyster in +himself; nay, further, that he is nothing but an oyster, revised, +amended, and considerably enlarged. And do not imagine that I am only +using a figure of speech here, as the professors of rhetoric call it; +which would be in bad taste: I am speaking literally, and to prove the +existence of the oyster in question in our Academician, I shall only +ask permission to perform a slight operation upon him. You exclaim at +this; but do not alarm yourself, for it is only an operation on paper, +he will not die from it. See now, I cut off his head, his two arms, +and his legs; I take out of his body the vertebral column and the ribs; +I gently place what remains between two shells; and ... there is my +oyster. I willingly admit that it is more carefully elaborated and +richer in details than its sisters in the oyster beds; but all the +principal organs are to be found in them also, and they positively are +beings of a similar construction: you shall judge for yourself. + +The mouth--for there is a mouth, though one must look closer than the +oystermen do to discover it--the mouth is exactly what the gullet +(oesophagus) would be in a man whose head had been cut off; that is, +a truncated tube. Then comes the stomach, situated in the very midst +of the liver; which latter may easily be distinguished, even by the +most cursory glance at luncheon, from its dark color. The intestine +also goes right through the liver, doubling backwards and forwards +several times: and thus the digestive tube supplies itself with bile +from the cask (to borrow a commercial expression); and this saves the +expense of a bile-duct (choledochian canal), which would be an +unnecessary mode of conveyance in this case. The animal lives in water; +consequently, instead of lungs he has gills: [Footnote: The land-snail +has lungs.] these are those thin, finely-streaked plates which make +a fringe at the very edge of the shell. Finally, on leaving the gills +the blood is received by an arterial heart, with only one ventricle +like that of the crustaceans, in the shape of a small pear, similar +to ours, having an auricle, and an aorta, branching out so as to +distribute the blood throughout the whole body. And now what do we +find here, let me ask you, in this mutilated man, reduced to the soft +portions of the trunk, whom I have been imagining? A heart, with its +arteries; lungs; a liver; an intestine; a stomach and an oesophagus: +that is to say, merely and simply the organs of nutrition. That is +all, or very nearly so. + +As you perceive, then, all the elements of our own feeding-machine lie +between the two shells of a mollusk; in a rough state as yet, it is +true; incomplete, and unruly; as in the case of the intestine, for +instance, which in many of these creatures passes without ceremony +through the heart: but even so they are quite sufficiently indicated +to prevent their being mistaken. Now this machine, it is in vain to +deny it, is the animal itself; but it lives at first, and it is this +which dies in it last. The other matter (the locomotive power), +important as it may seem to us in higher races, only holds a secondary +position in reality: the proof of which is, that here is an animal +reduced absolutely to a mere feeding-machine, who still lives, whilst +there yet remains to be found one who has nothing left but his +movement-machine, and who can yet exist. We cannot disown this primitive +animal, for we have it within ourselves; lost, so to speak, in the +midst of the accessory organs which are successively added to it in +proportion as we rise in the animal scale, but still preserving its +own life, its personality, if I may use the expression. Listen to this, +for here is a history well worth hearing. + +I will explain to you, hereafter, how all the actions of the +movement-machine are performed by means of a network of nervous threads +(filaments), whose centre of impulsion is in the brain. How our will +acts upon the brain, and gives its orders to the muscles through the +nervous fibres, I will not offer to explain: it is a fact, let that +suffice us. You say to your foot, "Forward!" and off it starts; "Halt!" +and it stops. Here is an organ under command, a servant of the brain, +where we rule ourselves: with or without explanation, no one will ever +dispute this. The oyster, who has neither head nor brain, has, as his +only instrument of action, certain little masses of nervous substance +scattered right and left, which are called _ganglions_. These +communicate with each other and with the organs by nervous cords, which +are interlaced in all directions, without having any common centre, +and which give the impetus to all parts of the animal. + +Well, the human oyster presents to us exactly the same nervous +organisation. It has its ganglions and its nerves to itself, which are +put into communication with the brain by some threads strayed among +his own, but which are not under its orders, and which treat with it +on equal terms. You remember, perhaps, the little republic talked about +when we first entered the digestive tube; you have now the explanation +of it. This republic is the original animal; it is the feeding-machine. +I cannot describe it, and the kingdom of which you are queen, better +than by comparing them to two States having diplomatic relations with +each other, who exchange dispatches and reciprocal influences; and as +to the importance of these respective influences, if one were to compare +them I scarcely know to which side the balance could incline. + +We shall return elsewhere to this detail, one of the most interesting +of our organisation, and which here finds its natural explanation. For +the present I will content myself with reminding you that, since the +earliest days of human civilisation, all philosophers, all poets, and +all moralists, whether sacred or profane, have borne witness to that +double life within us, that inward being, blind and deaf, whose +disordered impulses so often carry trouble into those higher regions +where will and reason sit enthroned. Behold him taken in his lair at +last, this mysterious being. I have just unveiled his origin to you. +And here, dear child, I must shelter myself behind a profession of +faith. There will not be wanting people to tell you that it is degrading +man far too much to look so low for the sources of his organisation, +and that this sentence--_the human oyster_--which expresses my +idea so well, is neither more nor less than blasphemy. Let them talk, +but adopt their opinion only when they have proved to you that man had +a special Creator, and that the oyster came from a different hand from +ourselves. I should like to know with what face we could venture to +complain, poor worms that we are, because it has seemed good to our +common Father to carry forward in us his previous creations, and in +what respect human dignity would suffer from this contact with a being +who, like us, is one of the works of God. That human pride may suffer +thereby, I admit, and I am glad it should; but if God has included all +creation in His love, we may well include it all in our respect. Whence +comes our superiority at all, but from the gratuitous gifts of Him who +has made us what we are? Is it to lose it, then, to find ourselves +side by side with inferiors whom the Divine benevolence has visited +like ourselves? Surely not. But enough of the oyster, who has never, +that I am aware of, heard such strange discussions sounding in his +ears before. I have no time nor courage now to speak of the other +mollusks, who offer more or less the same system of organs which I +have just described. I must hasten on to the Worms, who give us the +last clue to the great enigma of the animal machine. + + + +LETTER XXXIX. + +VERMES--ZOOPHYTA. (_Worms and Zoophytes_). + +_Worms._ + +The worm of worms, the one you know best, is the earthworm: so he shall +have the honor of representing his group. + +He will not take much time to describe. He is, in brief, a tube, open +at both ends, so as to allow food to come in and go out. That is all. + +I talked to you before about the ruminants, those food-manufacturers +who are employed in cooking victuals for the stomach, and in disengaging +albumen from the coarse materials among which it is apparently lost, +so as to give it out again in a more acceptable form. The ruminant has +other workmen under him, whom I keep in store for you as the last of +the eaters, and who prepare the raw material for him*. These are the +vegetables, who seek out the elements of albumen in earth, water, and +air, those final sources of all alimentation. The earthworm also is +a _preparer_, but in a peculiar way. Look along the garden-walks +in summer-time, after rainy weather: you will see here and there, +little heaps of earth moulded into small sticks, like dough which has +been passed through a tube. [Footnote: M. Mace's account of the +earthworm's life seems founded on the assumption that it extracts its +nourishment from the earth itself, i.e., from inorganic matter, as +_vegetables_ do, to use his own words. But this notion is so +entirely at variance with present received opinions, and also with the +fact that the animal possesses a gizzard for digesting, as well as an +intestinal canal, that it has been necessary to make considerable +alterations in the description. To dismiss his theory of the primitive +animal, etc., altogether, was, however, impossible, without omitting +the whole chapter; but as young heads are not likely to trouble +themselves about it, and it is very innocent in itself, it will do no +harm; subject to this warning, that M. Macé has taken the earthworm +for a more simply organised creature than it really is.--TR.] This is +the damp soil which the worm has passed through his tube, after +extracting from it, during its passage, the various elements of +fertility he requires for the support of his life. This is what makes +him so particularly fond of garden soil, because it is richer in animal +and vegetable matter than common earth, and proves therefore more +nourishing food. The worm, then, feeds on the fat of the earth, which +he converts into azotic aliment for the use of moles, hens and Chinese. +It only figures, it is true, for want of something better, in Chinese +cookery, so profusely hospitable for all that; but the hen doats upon +it, and you do not despise it yourself when it comes back to you in +the form of a chicken's wing, that second transformation of the matter +of which the soil of your garden is composed. It is told of certain +savage tribes, the victims of constant scarcity, that they swallow +little balls of clay in order to keep down their hunger; and during +the great famines in India the distracted inhabitants may, we are told, +be seen digging up the banks of the rivers to feed on the fertile clay +in which the splendid vegetation of their country is developed. This +is a desperate trial of that primeval system of alimentation which +answers perfectly with the worm, but becomes a cruel mockery in the +case of an organisation as exacting as that of man. Let us examine a +little more closely, then, this wonderful tube. + +At first sight one notices, to begin with, that it is composed of +perfectly distinct rings, all quite alike. Inside as well as out each +of these rings is an exact repetition of the other. They are all formed +of circular muscles, enclosed between two coats, which extend from one +to the other. A series of ganglions, arranged in the form of a necklace +along the whole length of the body, set in motion the muscular system +of the rings, each of which possesses its local centre of impulsion. +Each feeds itself in its place from the nourishing juices with which +it is in contact, the interior coat enjoying the double property of +distilling digestive juices and absorbing digested ones. These juices +pass through the muscular partition, and proceed to bathe the outer +coat, which plays, at the same time, the part of coat and lung, and +affords a passage to the air through its soft, damp surface, like that +of gills. From all this results a fine red blood, such as we have not +met with since we left the reptiles, and which is manufactured in all +parts of the body at once. + +Each of these rings, then, the worm's only organs, is a little eating +machine to and for itself, and at the same time a little movement +machine also; in fact, a complete animal. Each one could, if necessary, +nourish itself and live apart; and this is what he really does. Learn +hence, to despise nothing in nature. One tramples an earthworm under +foot, and there below one's heel lies a little revealer of secrets, +whose organisation throws the most unexpected light upon one of the +greatest mysteries in our own life. + +I said to you before, and I felt at the time that it was rather beyond +you, that "each one of our organs is a distinct being, which has its +particular nature and special office, its separate life consequently; +and our individual life is the sum total of all these lesser lives, +independent one of the other, but which nevertheless blend together, +by a mysterious combination, into one common life, which is diffused +everywhere, but can be apprehended nowhere in particular." + +The study of the worm admirably explains this out-of-the-way sentence. +And here observe my adjective--my out-of-the-way--for it is a case in +point. We may call it a literary worm; a worm of four rings, each +perfect in itself, but yet compounded together into a whole with its +own idea. + +That which makes this idea of life most difficult to comprehend is, +that one cannot prove it by a direct experiment, since there is not +one of our organs which could exist separately from the others. Although +independent in their special action, yet these multiplied lives are +nevertheless in a state of absolute and mutual dependence, from the +imperative need they have of each other to make them act, each having +for its share only one particular function, the effect of which extends +to all the others. This is called the division of labor; and if you +still do not understand me clearly, I will explain it in another way. +The heart sends to all the organs--does it not?--the blood, without +which they could not live: separated from the heart, the lungs would +die immediately. It is to the lungs the blood goes to find the air, +without which it could not maintain life. Separated from the lungs, +the heart would die immediately. There is nothing belonging to us which +can avoid the inexorable requirements of blood and air; +consequently, there is nothing which can live an isolated life. + +I will borrow a simile from human society which you will understand +at once. In civilised countries, where division of labor is established, +the tailor makes clothes, the mason makes houses, and the baker makes +bread. If you could throw them each alone by himself into a wood, the +mason would not be able to dress himself, the baker would sleep in the +open air, and the tailor would not know how to make bread. Or rather, +as not one of them can carry on his trade without the co-operation of +a multitude of hands, they could none of them do anything at all. Each +completely independent in his work, yet each dependent upon the others, +both for living, and even for being able to work, our workmen can only +act when they remain bound in close union with the vast society of +which they form a part; and our organs--those other laborers whom you +have seen working for so long--our organs are just in the same +predicament. But in the primitive societies, among savage tribes, where +each man can make his clothes, his house, his bread (when he has any), +and everything else for himself, you might take such an individual if +you liked, and separate him from the rest of the tribe, and he would +go on living as before. And so with the rings of the worm, that +primitive society of organs. Each of them is a universal workman, who +knows how to make everything. Separate him from his fellows, it will +not disturb him at all, and he will go on living as if nothing was +thematter. + +I still remember some profound reflections I indulged in one day some +years ago whilst leaning on my spade and looking at a worm that I had +just cut in two, and whose two halves were walking off one on each +side. + +"There was only one creature here just now," I said to myself, "and +now there are two! Have I had power, then, to create one with a stroke +of the spade?" + +I had not then got hold of the key which I now give you, and to which +no possible objection can be raised. If there are two beings after the +stroke of the spade it is because there were two before. Nay, there +were even many more, if we may trust to the "Manual of Zoology" by +Milne Edwards, a very good book, excellent for an old scholar like +myself, and which I have found very useful in my country-home, as it +has enabled me to relate to you one after another the mysterious wonders +of life. + +He says that, "if one cuts an earthworm across into two, three, ten, +or even twenty morsels, each of these morsels will go on living in the +same way as the whole, and will form a new individual." + +Twenty! that seems to me a great many, because, as far as I can trust +to my brief observations as a gardener, it is necessary that some of +the rings should remain united together and afford each other mutual +support, in order to succeed in repairing the bleeding breaches; but +I would much rather believe it than try the operation. My mind is easy +when I am defending the plants that I have sown in my garden from the +gluttonous worm who would rob them of their food; but it would not be +so if I were cutting them up on my table to learn something about them. + +Besides, there is no need of an operation to convince oneself of the +particular life of each ring. There is one worm, well known by name +at least, though happily not to be met with every day, and that is the +tape-worm, who establishes himself in the intestine of man, and lives +on the chyme, as the other worm does on garden-mould. They call him +the _Solitary_ worm in France; and if ever one might suppose a +creature appropriately named, it would surely be him; for certainly +there is not much society to be looked for in the dwelling he chooses +for himself! But it happens that this pretended _solitary_ worm, +with his unlimited chain of rings, is only a long row of perfectly +distinct beings, so distinct indeed that, from time to time, some of +the rings let themselves go, fall off like ripe fruit, and go away to +live elsewhere, ready to become the nucleus of a new set, if a happy +accident carries them into another intestine, the only place favorable +to their development. + +At last, then, here is a corner of the curtain raised; here we see the +associated organs which constitute an animal, living for once a life +positively and in all respects their own. We are now satisfied about +this; and when at another time we find them bound together in the +chains of a union too ingenious to be severed with impunity--which we +shall discover by seeing their action stop at the moment of separation-- +we shall know the cause. + +Do not think, my dear child, that a wretched earthworm can prove nothing +as regards other creatures. The worm is the starting-point of all the +organisations which come after him. Of what is he composed? Of a +tubewhich is itself composed of rings. Well, it is upon this very tube +that the whole animal machine has been founded: and these rings, as +they expand and modify themselves in a thousand different ways, give +birth to all those varieties of being which drive classifiers to +despair, because they will not understand that there ought only to be +one animal, since there is only one Creator of animals. Now, this +animal is a digestive tube served by organs; it is a worm, _i.e.,_ +which goes on constantly embellishing itself. I said to you long ago, +and at a time when you scarcely knew anything, "Have you ever observed +a worm or a leech in motion? You see a successive swelling up of the +whole surface of its body as the creature gradually pushes forward, +as if there was something in its inside rolling along from the tail +to the head. Such is precisely the appearance which the oesophagus +would present to you as the food passes down it, if you had the +opportunity of seeing it in action; and this has been called the +_vermicular_ movement, in consequence of its resemblance to the +movement of a worm." + +And afterwards, in speaking of the intestine: + +"If your body were made of glass, so that you could look through it +to watch the intestine at work, it would appear to you like an enormous +worm, coiled up into a bundle, heaving and moving with all its rings +at once." + +You have now got hold of the secret, namely, that from the beginning +to the end of the digestive tube, its movements are those of a worm. +What a wonder! and that the worm is a digestive tube which can walk. +This worm, or this tube, whichever you please to call it, has never +ceased crawling under our eyes since we began this study. Lost sight +of in man in the midst of the riches he has picked up on his road, +invisible and coiled backward and forward in his palace like an Eastern +despot who leaves everything to be done by his slaves; behold him here +in his first stage naked, shivering in the air, forced to go off himself +and alone to his pasture--ground! But in the coarse earth with which +he fills himself I can already see the delicate chyme which his numerous +servants will prepare for him later on, and into which the heart-tree +will one day send down its roots--the chyliferous vessels. + +A short time ago I called the oyster the primitive animal, but I was +in too great a hurry. The worm is the real primitive animal. He is to +be found in the oyster, as the oyster is to be found in us; and that +poor little beast is, by comparison, an animal of high pretension, who +would be shocked, I am sure, if he could understand what we are saying, +and heard us assert that he is nothing but an embellished worm. + +_Zoophytes._ + +Two centuries ago it was believed that below the worm, animal life, +properly so called, ceased, and the creatures whom I am about to +introduce you to were supposed to be animated plants rather than living +organisms. Hence their name was especially chosen to express that +double nature by which they were thought to have a share in two kingdoms +at one time--viz., the animal and vegetable--_zoon_ in Greek +meaning animal, and _phuton_ a plant. Zoophytes were set down as +animal plants. + +And although later discoveries have long ago established the fact of +the complete animality of zoophytes, the old name is still in general +use. But you must not let it deceive you. Zoophytes are animals every +inch of them, however low in the organic scale, and although many of +the compound ones imitate the growth of plants and shrubs so exactly +in their mode of spreading that it is only by the closest observation +we can persuade ourselves they do not belong to the vegetable kingdom. +Of these there are the delicate buff-colored, prettily-branched, horny +specimens found on the shore, which make so beautiful a variety in +seaweed pictures among the red and green colors of the real seaweed; +but of these also are those wonderful stony shrubs which grow on the +submerged rocks of islands in warm seas, and the material which you +know so well by the name of coral--the very coral of which the necklaces +and bracelets in the jeweller's window are composed. + +In all cases of compound zoophytes, however, there is one great point +which they have in common with the worm, viz., that there is an +association of distinct lives acting unanimously; or, rather, to the +same end. Plainly as this is seen in the worm, it is still more obvious +in the zoophyte. There is no need here either of cutting them up +yourself or of taking other people's dissecting operations upon trust. +It is enough to use your eyes, with the help, it is true, now and then, +of the microscope's clearer sight. + +You know the old oak-tree which stands on the outskirts of the wood, +and is called among the country folk _the patriarch_? Now, this +is clearly not an individual, but a nation. It is not a tree; it is +a forest. Nay, may I not call it a green field? For this trunk, so +truly venerable from ages of growth that one feels inclined to bow to +it as one goes by, is, in fact, a collection of structures, accumulated +by countless generations of fleeting herbs, _i.e.,_ leaves, not +one of which has lived for the space of a whole year round. Every +spring some thousands and thousands of buds open to the sun; each one, +therefore, affording a passage to a little green point; and this point +is an oak, who comes into the world, like the first oak, the grandfather +who formerly came forth from an acorn, under the form of an herb or +tender leaf, which a sheep might have browsed upon. Yet it is so +thoroughly an oak, that you have only to take out the bud carefully +before it has expanded and fasten it into another one's place upon a +tree of the same family, though of a different species, and it will +produce an oak of the same sort as its old companions, and which will, +as it progresses, look quite a stranger among the indigenous branches. +This is the secret of what the gardeners call _grafting_, and I +advise you to try the operation upon rose-trees, for nothing is more +amusing. When the autumnal frosts set in, all these troops of new +little oaks die, and deliver up their leaves to the wind; but they +leave behind, as their summer's work, a tiny morsel of new wood, upon +which, if you look carefully, you will see a fresh bud dawning--the +hope of the coming season. And thus the great life of the tree is +perpetuated from century to century by an uninterrupted succession of +transient lives, reminding one in all respects of the life of a nation; +and the similitude is complete in the evergreen trees, where the new +leaf makes its appearance before the old one has quitted the stem. + +And such is the life of the great stone trees and shrubs of various +kinds which grow under tropical seas, and whose makers and inhabitants +are the coral polyps, the undoubted heads of the Zoophyte race. + +But before considering the _polypidom,_ or external dwelling +(otherwise called the _coeneciun,_ or "common house"), you must +learn something of its originator, the little _polyp,_ who lives +inside, and belongs to a family so widely spread over the face of the +earth, that there are scarcely any waters, whether salt or fresh, +without them. + +In your own neighborhood, if you know how to look for them, are to be +found on the banks of ponds, or along the borders of streams which lie +sleeping in roadside ditches, extraordinary beings which, a hundred +years and more ago, completely bewildered the good Dutch naturalist +Trembley, who had taken it into his head to study them. Picture to +yourself some very tiny bags made of a kind of jelly; gray, brown, or, +most commonly of all, green in color, always transparent, and fastened +by their base to the stalks of _carex,_ water-lentils, or the +confervas, which grow in still water. A hunter on the watch, this bag +shoots out on all sides a number of slender threads, like so many +whip-lashes, arranged within a circle round the edge of its opening +or mouth; and with these whip-lashes all the animalcules which come +within reach are entwined, stifled, and carried away to the ever-yawning +little gulf, where they are digested in less than no time. Whatever +will not digest comes out afterwards by the way it went in. Of what +becomes of the results of this digestion it is impossible to form an +idea. Were you to cut up the bag and put little morsels of it under +the best microscope possible, you would see positively nothing but +solid jelly, without the least sign of any organisation whatever. But +this is not all. Replace these morsels in the water, and come back +tolook at them at the end of five, twenty, or thirty hours. Each one of +them will have become a perfect bag, ready to multiply itself afresh +if you submit it to the same operation. Sometimes, on some part of the +original bag, there suddenly appears a little raised spot, like that +which came on your baby brother's arm the other day after he had been +vaccinated. What would you have said, if this ugly spot had grown +larger and larger without stopping; if it had assumed legs, arms, and +a head, and so become another baby, growing from the arm of the first +one? Yet this is just what the spots do which come on the bag I have +been telling you of; and people have come across bags of a larger +species still--between one and two inches in size, in fact--which in +this way carried twelve young ones on their backs, if one is allowed +to talk of stomachs having _backs_. You perceive at once that +this commencement of animal life is not even a digestive tube, and +that nothing in it can he found but a stomach, opening straight to the +air above and closed up below. + +It was Réaumur, the originator of the famous thermometer, who gave a +name to the wonderful bags discovered by Trembley. Aristotle had +previously bestowed the title of _polypus_ (many feet) upon a +mollusk outwardly formed upon a similar model [Footnote: This is the +cuttle-fish, called _polypus_ by old naturalists. We shall speak +of it fully hereafter in the history of the movement machine.] with +large whips disposed regularly in a circle round the mouth, and intended +for a similar use, only that they have another function besides; that +of carrying the body along in the capacity of feet by clinging on to +the rocks with their suckers as they go. Réaumur transferred this name +to the newcomers, and called them fresh-water polyps, to the infinite +amusement of Voltaire, who had declared that they were only blades of +grass; a new proof, among many others, that in natural history all the +intellect in the world is not worth a pair of good eyes. + +But it was soon found out that, in collecting these bits of living +jelly near the Hague, Trembley had laid his hands on little beings of +immense importance on the surface of the globe, and that he had +discovered under his microscope the explanation of a mystery which had +spread itself, setting human science at defiance, over some thousands +of square miles. + +I talked to you just now of the jeweller's coral, of which ornaments +so becoming to dark-haired people are made. That is one of the stony +polypidoms I spoke of as stone trees found at the bottom of the sea, +where it grows attached to the rocks in the form of a charming little +shrub, stretching its red branches in all directions. The Greeks, who +were never at a loss, relate that Perseus one day laid down upon the +sea-shore the famous head of Medusa, the sight of which had the property +of turning everything to stone, and that the nymphs, in sport, showed +it to the coral shrubs; a fact which explained everything quite +naturally. Without exactly holding this mythological explanation, +modern philosophers had not got much farther, and coral was still a +puzzle to them, which they were not fond of troubling themselves about; +till, roused by Trembley's revelations, they examined it more carefully, +and discovered in its soft extremities (hitherto unnoticed) those same +living jelly-bags or sacs, with their circlets of legs, or rather arms, +charged with supplying them with food. These were marine polyps, which +grow, like those in fresh water, one upon another, but each in its own +crusty cell; and like the buds of the oak, these buds of the stony +tree form each its special deposit, which it bequeaths in dying to the +general mass. In short, as the tender shoot of the oak is filled by +degrees with the wood which forms within it, and hardens into a branch, +that goes on increasing by perpetually new growths, so the jelly polyp +of the polypidom hardens below into stone and dies incessantly at the +base, while it lives on indefinitely above in its constantly-renewed +summit. + +Do not get tired of all this phantasmagoria, my dear pupil: it is a +matter of the highest interest. Here is the point of junction--the +bond, as it were, between the three kingdoms: an animal growing +vegetable-wise produces a mineral mass, extracted from the waters of +the sea by an infinity of little living crucibles, who carry on under +our eyes the work begun in the first ages of the globe, and quietly +manufacture continents for the use of future generations. This ought +to console you, my dear child, for being little. It is by little things +that God loves to effect what is truly great. He did not seek out the +elephant or the whale to form these worlds; He chose workmen no bigger +than a pin's head. I have spoken to you about jeweller's coral, which +is made into toys or presents for ladies to adorn themselves with; but +its brethren, the madrepores of the Pacific Ocean play a very different +part. They have formed in front of the shores of New Holland a barrier +of reefs three hundred leagues in extent and twenty wide. What are all +our buildings after this?--those pyramids and cathedrals which seem +so gigantic to us? This ever-increasing wave of coral polypidoms will +one day shut against navigators the entrance to one part of the sea's +tropical region; and lands not to be found on the map to-day will then +lie stretched out under the sun, covered with plants and animals; and +this in places where ships now plough the ocean. Know, also, that a +great portion of the soil which we tread under foot has no other origin. +It was manufactured formerly in the sea by infinite myriads of beings, +often infinitely small. Each one, whether polype or shell, produced +its grain of stone, and from all these grains God, who directed their +work, has made our country. + +But it is time to bring this chattering to a close, for it will never +end if I do not force myself to stop. I leave it with regret; but all +these paths through which I have threaded my way one after another +without counting them, have already made a volume which may possibly +be considered too large for you. There are many other zoophytes besides +the coral polypes, and all of them beautiful and curious. They all +inhabit the fertile depths of the waters where God has deposited the +first germs of life. I cannot describe them to you now. But to make +amends, I will give you a piece of advice which will perhaps make some +people stare. Ask your papa to lend you Michelet's book, _The Sea_, +and look there for what is said about the mysterious animals which lie +hid beneath the waves. His book was not written for you as this one +is: and if, in spite of all my good intentions, I have not always +succeeded in being as comprehensible as I meant to be, Michelet, who +never thought about little people when he took up his pen, will +certainly startle you now and then. But do not be disheartened by a +word. You will find there, that which will be forever plain to you, +the poesy of nature, and children comprehend that better than learned +men. + + + +LETTER XL. + +THE NOURISHMENT OF PLANTS. + +One more word before we part about the last of the eaters, about +Vegetables. They will furnish you with a new and very clearly marked +proof of the uniformity of the fundamental conditions to which the +Author of life has subjected all organised beings. + +Let us look once more at this oak, of whose manner of growth I was +obliged to give you a sketch beforehand, in order to show you the ties +which unite it with its immediate neighbors in the animal kingdom. How +does it feed? I need not tell you this. It feeds by its roots, which +suck up in the bosom of the earth the water charged with the juices +which form its nourishment. Are you aware that every large branch had +its subterranean fellow or representative, and that the annual shoot +at the top of the tree is reproduced at the base by fresh fibres, which +extend themselves in the soil of the earth, in proportion as their +sisters above make their way in the air? And thus, by means of organs +ever young, the life and progress of the great association is kept up, +while those members whose day of work is over still remain there as +the supports of the edifice. It is the same with human societies. They +are sustained by what is old, but they live and progress only by what +is young. The sap, then, which is the name given to the moisture or +water sucked in by the young roots, having once got into the cells of +which the tissue of the fibres is composed, passes from one to another, +and travels thus to the top of the tree, where it is wanted by the +leaves. + +There is no obvious machinery here, however, to impel it forward. It +journeys on of itself, as it were, under the action of laws which have +never been satisfactorily explained, but all of which are dependent +on the vital force or life-power of the tree, inasmuch as without it +there is no circulation. One agent, but by no means the principal, or +it would act as well in a dead tree as a living one, is _capillary +attraction_; and, if you wish to know what that is, you have only +to think of what happens to a towel, if you hang it upon a peg, and +leave the end of it soaking in water. Does not the "wet" seem to climb +up it thread by thread, till it is damp from one end to the other? A +little in this way--but these similes are very imperfect, and will not +bear close application--the sap rises in a tree, stealing up branch +by branch; and it is then called _ascending sap_. [Footnote: M. Macé +speaks of this sap as the _blood of the tree_, and of the leaves only as +_lungs_. These statements have been modified so as to meet the fact that +_ascending sap_ consists of, and conveys the raw elements of _food_ to, +the leaves; that in the leaves this food is _digested_, as well as +brought in contact with the air, and that it is thus converted into that +nourishing fluid, the _descending sap_, which certainly plays the part +of steward to the tree as our blood does to us, and therefore may now be +called the blood of the tree. It must be remembered, however, that each +tree has its own sort of steward, as the case of the _Euphorbia_ (quoted +afterwards) plainly shows. The analogy with the more general substance +of blood is therefore not very complete.-TR.] + +It arrives at last at the leaves, which it enters as our food enters +our stomachs, and for the same purpose; for in them takes place, as +in all true stomachs, that process of digestion by which the elements +of the crude sap-food are decomposed from their first condition, and +converted into a nourishing chyle; in each tree of a sort "after its +kind." + +But more than this. Like the outer coat of the earthworm, the coat of +the leaf affords a passage to air and moisture through its surface; +and here, therefore, takes place that mysterious exchange which is +everywhere the essential condition of life. Here is the charcoal-market +as before, only the bargainers have changed parts. The air, which in +the other case received the _carbon,_ delivers it up, now, and +receives oxygen in exchange; exactly the reverse of its traffic with +animals. In other words, the tree inhales through its leaves the +carbonic acid gas thrown into the atmosphere by our lungs. On its own +responsibility it breaks through the alliance between the carbon and +oxygen contracted in our organs; keeps the carbon for its own use, to +restore it to us another day under the form of wood, or, by the aid +of the charcoal-burner, in the pure and simple state of charcoal; and +sets at liberty the oxygen, which once more goes off in search of new +lungs and a fresh alliance. Thus a constant equilibrium is maintained +in the atmosphere; and thus, by a system of perpetual rotation or +everlasting merry-go-round, the same substances serve, indefinitely, +to support life of every opposite description. + +Now there are two things to be remembered in this inverted respiration +of vegetables. In the first place, it occurs only in the parts which +are _green_. Flowers, fruit, the root, and every part of any other +color, do as we do when we breathe; _i.e._ deprive the air of its +oxygen, charging it with carbonic acid instead. For which reason, +by-the-by, we ought not to keep flowers in a bedroom at night. Charming +as they are, they are _poisoners_, and a headache is what we may +fairly expect after sleeping shut in with them in the same room. It +is almost as bad to allow green boughs to remain there either, for, +in the dark, even the green parts cease to purify the air, and begin +like the others to manufacture carbonic acid, at the expense of course +of their carbon, which thus by degrees is used up. Now, as it is the +carbon which constitutes the solid fibres of plants and produces their +green color, they soon become yellow and limp when deprived of light. +You may, perhaps, have wondered why the gardener amused himself with +smothering his poor lettuces by tying them up at top like a knot of +"back hair," instead of letting them grow freely in the air and +sunshine. It is, my dear, to make them more tender and delicate for +you to eat; and those beautiful, crisp, yellow leaves, so delicious +to the tooth, would have been green and tough, had they not slowly and +quietly let out a great portion of their store of carbon in darkness +during the last few days, before being gathered. Even without playing +the gardener, you may assure yourself of this fact in a still more +simple manner. Put a flat board upon the lawn and leave it there for +three days; then take it up again, and you will find just where the +board has prevented the light from reaching the grass, a yellow mark +so distinctly traced as to be seen from the other end of the garden. + +But to return to the sap, which we left undergoing a change from air +and solar influences in the leaves. The ascending sap was to all +appearance only clear water. When it returns from the leaves, charged +with carbon, it is a thick juice having almost the consistency, and +sometimes even the color of milk, and is possessed of properties +altogether new. The most striking example that I can give you of +thedifference of the two states of sap is the Euphorbia of the Canary +Islands, whose digestive or descending sap is a violent poison. When +the natives of the country are accidentally pressed by thirst, they +carefully remove the bark in which the fatal juice circulates, and are +then able to refresh themselves safely by sucking the stem, which +yields only the watery sap sucked from the ground, and as yet unaltered +and harmless. + +Each of these two saps, in fact, has its path distinctly traced for +it: the first rises through the wood, the second descends through the +bark, whence it is called descending sap. If you wish to satisfy +yourself of this, fasten a rather tight knot of pack-thread round a +young branch, and after a time you will see it pine below the knot and +become swollen above it, an unanswerable proof that the nutritive +juices flowed downward through the bark; for the wood inside the branch +will have been uninjured by the strangling pressure. Remember this, +my dear, when you are playing in the garden, and do not injure the +bark of the young trees your father likes so much to see flourishing. +It is by the bark that they are nourished, and you might even kill +them by treating it too roughly. + +And now I must show you how the nutrition is carried on, or, if you +like better, how the tree grows by means of this descending sap. See: +here is a fir tree, which has just been cut down to the ground. Now, +if you like, I will tell you in a moment how old it is. I will even +tell you the age of every branch, little and big ones both, without +making a mistake in a single year; and you know as well as I do that +I am no conjuror. You see these small circles so delicately drawn, as +it were, upon the face of the sawn trunk, each wider than the last, +as if they were composed of a set of tubes, of unequal sizes, fitting +exactly into each other. Now count them; and you will perhaps find +twenty-five; and as each of these circles represents the work of one +year, you will know that the tree is twenty-five years old. In spring, +when the sap begins to move more briskly, it deposits everywhere between +the wood and the bark, from the trunk to the farthest boughs of the +tree, a uniform layer of a thick liquid, which moulds itself exactly +upon the wood already formed. This layer stiffens during the year; it +gets filled with the carbon left in it atom after atom, by each drop +of the descending sap as it goes by, and thus insensibly becoming +organised and hardened. When winter arrives to interrupt the work, it +will have formed two _ligneous, i.e._ woody layers, as they are +called. Of these, one belongs to the wood, and will never move again +so long as the tree lasts, for it will be covered over, and as it were +buried, by the successive layers yet to come; while, on the contrary, +the other (layer) belongs to the bark, and is doomed to find itself +perpetually forced outwards by the fresh layers, which will after a +while insinuate themselves between it and the wood. + +It is for this reason that the bark of old trunks of trees is so deeply +furrowed, and that the dry scales may be picked off the surface without +the slightest injury to the tree. It is part of the original bark, +dead long ago. The old wood also is dead inside, and even when it is +altogether gone, the glad youthful branches growing green in the +sunshine will scarcely find it out! This accounts for those oaks which +time has hollowed without destroying, as those of Allonville in +Normandy, in which mass is said, and which is moreover the greenest +tree in the country. But without going so far, who has not seen those +hollow old willows, sometimes pierced with holes letting in daylight, +yet proudly crowned above by a forest of young boughs, as green and +full of vigor as if the trunk were still in its prime? What was dead +has departed, but all that has life in it remains, and that is enough +for the tree. + +Need I add that the descending sap, this steward of the vegetable, has +also his workmen to supply with materials, as in our case, and that +he is always falling in on his road with organs, all of which want +different things from him? That here a flower has to be formed, there +a fruit, there a leaf, or a bit of wood, and so on: and that a +mysterious intelligence--the same that we have found everywhere +else--presides over all these varied constructions, the materials for +which are mixed together pell-mell, in the imperceptible thread of sap +which oozes from the leaf to the bark? I recollect just as I am about +to conclude, my dear child, that I once told you, you were a small +temple in which God perpetually attests His presence, by a permanent +miracle. You may now henceforth look upon a tree as something more +than a bit of wood, yielding a pleasant shade. God is in it also. + + +CONCLUSION. + +And now, my dear little pupil, to what conclusion do we come from all +this? To that which I announced to you from the first. Throughout the +length and breadth of creation, from the highest to the lowest grade, +every living thing is subject to the same law. Everything eats, and +eats nearly in the same manner, since everywhere the same substances +furnish the feast. I laid down in my first letter that our feeding +machine was reproduced even to the farthest limits of the animal +kingdom, though always becoming more simple as the species descends +in the scale. And afterwards, where we began the study of animals, I +told you that in this machine lay the uniformity of their construction. +Was I not right? and what could I add to all the proofs which have +developed themselves one after another, to establish the fact of this +uniformity of plan in the animal machine, in all its essential points? +And it will be to the lasting renown of the illustrious Geoffroy St. +Hilaire that it was, in the face of all the Academies and under the +fire of very learned indignation, he proclaimed this truth, which one +cannot lose sight of without losing one's way in a crowd of arbitrary +fancies. + +I return, then, to the definition which I gave you in speaking of the +worm, and which is the final word of the ideas I have been endeavoring +to make you understand. _An animal is a digestive tube served by +organs._ + +In the first place it must eat, and for this therefore the Creator +provided first. All the rest came afterwards in order to enable it to +eat more readily, to secure its prey more easily, and to make the most +of it when eaten. The movement machine, therefore, whose history I +have promised you, is only an assistant, and not the principal feature +of the organisation, and it is not by it, therefore, that the question +can be decided, whether God has made three, four, or five animals, or +whether he has only made one. + +And now, my dear little pupil, I will bid you adieu, or rather say as +the French do, "Au revoir," which means "Good-bye till we meet again," +begging you to excuse any awkward expressions that may have escaped +me, as also my having now and then talked about things because they +have interested me, without perhaps sufficiently considering whether +they might have an equal interest for you. Yet, while the pen is still +in my hand, I will not leave you my concluding definition of an animal +without adding a word of explanation. You know nothing about such +matters yourself, but to some people my words might have the air of +a parody upon another definition, applied by those grave gentlemen the +Philosophers to man, whom they have denominated _An intelligence +served by organs_. My definition is applicable only to the animal, +and not to man, observe. Man in the natural, physical machinery of his +body, is very decidedly an animal; yet as certainly is he, by the +divine reflection which shines within him, something much more and +greater; but _what_, is so far beyond the reach of definitionthat I +shall not attempt to give you one. "Man," as Jesus Christ has +said, "lives not by bread alone, but by every word that proccedeth out +of the mouth of God." What it is that is nourished in us by that word, +is precisely what I cannot attempt to define for you; yet I think you +have understood my meaning. + +Go, then, and eat your food in peace, like the pretty little animal +that you are; but do not forget to nourish also the other part of your +being; that indeed which is of the most importance, and which enables +you to ascend to your Creator. + +THE END. + + + +POSTSCRIPT. + +In going through the preceding pages (Part II) with a comparative +anatomist, it became evident that some few popular and other errors +and misconceptions had crept into this portion of M. Macé's usually +clear and accurate work. + +Naturally it was not in his power to verify all the statements he had +to make on so many and such varied subjects, and he appears occasionally +to have trusted to works of old-fashioned or doubtful authority. + +In these cases I have considered it desirable to make such corrections +as should secure the trustworthiness of the descriptions as far as +they pretend to go. + +It would not, however, have been in my power to accomplish this, but +for the kind and efficient aid I have received from a scientific student +of these subjects; and I am glad of this opportunity of acknowledging +how much I am indebted to him for his assistance in making the necessary +alterations, as well as for confirming the correctness of the greater +portion of the work. + +MARGARET GATTY. + +January, 1865. January, 1865. + + + + + +End of Project Gutenberg's The History of a Mouthful of Bread, by Jean Mace + +*** END OF THE PROJECT GUTENBERG EBOOK THE HISTORY OF A MOUTHFUL OF BREAD *** + +This file should be named 8brd110.txt or 8brd110.zip +Corrected EDITIONS of our eBooks get a new NUMBER, 8brd111.txt +VERSIONS based on separate sources get new LETTER, 8brd110a.txt + +Juliet Sutherland, Charles Franks and the Online Distributed +Proofreading Team. + +Project Gutenberg eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the US +unless a copyright notice is included. Thus, we usually do not +keep eBooks in compliance with any particular paper edition. + +We are now trying to release all our eBooks one year in advance +of the official release dates, leaving time for better editing. +Please be encouraged to tell us about any error or corrections, +even years after the official publication date. + +Please note neither this listing nor its contents are final til +midnight of the last day of the month of any such announcement. +The official release date of all Project Gutenberg eBooks is at +Midnight, Central Time, of the last day of the stated month. A +preliminary version may often be posted for suggestion, comment +and editing by those who wish to do so. + +Most people start at our Web sites at: +http://gutenberg.net or +http://promo.net/pg + +These Web sites include award-winning information about Project +Gutenberg, including how to donate, how to help produce our new +eBooks, and how to subscribe to our email newsletter (free!). + + +Those of you who want to download any eBook before announcement +can get to them as follows, and just download by date. This is +also a good way to get them instantly upon announcement, as the +indexes our cataloguers produce obviously take a while after an +announcement goes out in the Project Gutenberg Newsletter. + +http://www.ibiblio.org/gutenberg/etext03 or +ftp://ftp.ibiblio.org/pub/docs/books/gutenberg/etext03 + +Or /etext02, 01, 00, 99, 98, 97, 96, 95, 94, 93, 92, 92, 91 or 90 + +Just search by the first five letters of the filename you want, +as it appears in our Newsletters. + + +Information about Project Gutenberg (one page) + +We produce about two million dollars for each hour we work. The +time it takes us, a rather conservative estimate, is fifty hours +to get any eBook selected, entered, proofread, edited, copyright +searched and analyzed, the copyright letters written, etc. Our +projected audience is one hundred million readers. If the value +per text is nominally estimated at one dollar then we produce $2 +million dollars per hour in 2002 as we release over 100 new text +files per month: 1240 more eBooks in 2001 for a total of 4000+ +We are already on our way to trying for 2000 more eBooks in 2002 +If they reach just 1-2% of the world's population then the total +will reach over half a trillion eBooks given away by year's end. + +The Goal of Project Gutenberg is to Give Away 1 Trillion eBooks! +This is ten thousand titles each to one hundred million readers, +which is only about 4% of the present number of computer users. + +Here is the briefest record of our progress (* means estimated): + +eBooks Year Month + + 1 1971 July + 10 1991 January + 100 1994 January + 1000 1997 August + 1500 1998 October + 2000 1999 December + 2500 2000 December + 3000 2001 November + 4000 2001 October/November + 6000 2002 December* + 9000 2003 November* +10000 2004 January* + + +The Project Gutenberg Literary Archive Foundation has been created +to secure a future for Project Gutenberg into the next millennium. + +We need your donations more than ever! + +As of February, 2002, contributions are being solicited from people +and organizations in: Alabama, Alaska, Arkansas, Connecticut, +Delaware, District of Columbia, Florida, Georgia, Hawaii, Illinois, +Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, +Michigan, Mississippi, Missouri, Montana, Nebraska, Nevada, New +Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, +Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South +Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West +Virginia, Wisconsin, and Wyoming. + +We have filed in all 50 states now, but these are the only ones +that have responded. + +As the requirements for other states are met, additions to this list +will be made and fund raising will begin in the additional states. +Please feel free to ask to check the status of your state. + +In answer to various questions we have received on this: + +We are constantly working on finishing the paperwork to legally +request donations in all 50 states. If your state is not listed and +you would like to know if we have added it since the list you have, +just ask. + +While we cannot solicit donations from people in states where we are +not yet registered, we know of no prohibition against accepting +donations from donors in these states who approach us with an offer to +donate. + +International donations are accepted, but we don't know ANYTHING about +how to make them tax-deductible, or even if they CAN be made +deductible, and don't have the staff to handle it even if there are +ways. + +Donations by check or money order may be sent to: + +Project Gutenberg Literary Archive Foundation +PMB 113 +1739 University Ave. +Oxford, MS 38655-4109 + +Contact us if you want to arrange for a wire transfer or payment +method other than by check or money order. + +The Project Gutenberg Literary Archive Foundation has been approved by +the US Internal Revenue Service as a 501(c)(3) organization with EIN +[Employee Identification Number] 64-622154. Donations are +tax-deductible to the maximum extent permitted by law. As fund-raising +requirements for other states are met, additions to this list will be +made and fund-raising will begin in the additional states. + +We need your donations more than ever! + +You can get up to date donation information online at: + +http://www.gutenberg.net/donation.html + + +*** + +If you can't reach Project Gutenberg, +you can always email directly to: + +Michael S. Hart <hart@pobox.com> + +Prof. Hart will answer or forward your message. + +We would prefer to send you information by email. + + +**The Legal Small Print** + + +(Three Pages) + +***START**THE SMALL PRINT!**FOR PUBLIC DOMAIN EBOOKS**START*** +Why is this "Small Print!" statement here? You know: lawyers. +They tell us you might sue us if there is something wrong with +your copy of this eBook, even if you got it for free from +someone other than us, and even if what's wrong is not our +fault. So, among other things, this "Small Print!" statement +disclaims most of our liability to you. It also tells you how +you may distribute copies of this eBook if you want to. + +*BEFORE!* YOU USE OR READ THIS EBOOK +By using or reading any part of this PROJECT GUTENBERG-tm +eBook, you indicate that you understand, agree to and accept +this "Small Print!" statement. If you do not, you can receive +a refund of the money (if any) you paid for this eBook by +sending a request within 30 days of receiving it to the person +you got it from. If you received this eBook on a physical +medium (such as a disk), you must return it with your request. + +ABOUT PROJECT GUTENBERG-TM EBOOKS +This PROJECT GUTENBERG-tm eBook, like most PROJECT GUTENBERG-tm eBooks, +is a "public domain" work distributed by Professor Michael S. Hart +through the Project Gutenberg Association (the "Project"). +Among other things, this means that no one owns a United States copyright +on or for this work, so the Project (and you!) can copy and +distribute it in the United States without permission and +without paying copyright royalties. Special rules, set forth +below, apply if you wish to copy and distribute this eBook +under the "PROJECT GUTENBERG" trademark. + +Please do not use the "PROJECT GUTENBERG" trademark to market +any commercial products without permission. + +To create these eBooks, the Project expends considerable +efforts to identify, transcribe and proofread public domain +works. Despite these efforts, the Project's eBooks and any +medium they may be on may contain "Defects". Among other +things, Defects may take the form of incomplete, inaccurate or +corrupt data, transcription errors, a copyright or other +intellectual property infringement, a defective or damaged +disk or other eBook medium, a computer virus, or computer +codes that damage or cannot be read by your equipment. + +LIMITED WARRANTY; DISCLAIMER OF DAMAGES +But for the "Right of Replacement or Refund" described below, +[1] Michael Hart and the Foundation (and any other party you may +receive this eBook from as a PROJECT GUTENBERG-tm eBook) disclaims +all liability to you for damages, costs and expenses, including +legal fees, and [2] YOU HAVE NO REMEDIES FOR NEGLIGENCE OR +UNDER STRICT LIABILITY, OR FOR BREACH OF WARRANTY OR CONTRACT, +INCLUDING BUT NOT LIMITED TO INDIRECT, CONSEQUENTIAL, PUNITIVE +OR INCIDENTAL DAMAGES, EVEN IF YOU GIVE NOTICE OF THE +POSSIBILITY OF SUCH DAMAGES. + +If you discover a Defect in this eBook within 90 days of +receiving it, you can receive a refund of the money (if any) +you paid for it by sending an explanatory note within that +time to the person you received it from. If you received it +on a physical medium, you must return it with your note, and +such person may choose to alternatively give you a replacement +copy. If you received it electronically, such person may +choose to alternatively give you a second opportunity to +receive it electronically. + +THIS EBOOK IS OTHERWISE PROVIDED TO YOU "AS-IS". NO OTHER +WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, ARE MADE TO YOU AS +TO THE EBOOK OR ANY MEDIUM IT MAY BE ON, INCLUDING BUT NOT +LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A +PARTICULAR PURPOSE. + +Some states do not allow disclaimers of implied warranties or +the exclusion or limitation of consequential damages, so the +above disclaimers and exclusions may not apply to you, and you +may have other legal rights. + +INDEMNITY +You will indemnify and hold Michael Hart, the Foundation, +and its trustees and agents, and any volunteers associated +with the production and distribution of Project Gutenberg-tm +texts harmless, from all liability, cost and expense, including +legal fees, that arise directly or indirectly from any of the +following that you do or cause: [1] distribution of this eBook, +[2] alteration, modification, or addition to the eBook, +or [3] any Defect. + +DISTRIBUTION UNDER "PROJECT GUTENBERG-tm" +You may distribute copies of this eBook electronically, or by +disk, book or any other medium if you either delete this +"Small Print!" and all other references to Project Gutenberg, +or: + +[1] Only give exact copies of it. Among other things, this + requires that you do not remove, alter or modify the + eBook or this "small print!" statement. You may however, + if you wish, distribute this eBook in machine readable + binary, compressed, mark-up, or proprietary form, + including any form resulting from conversion by word + processing or hypertext software, but only so long as + *EITHER*: + + [*] The eBook, when displayed, is clearly readable, and + does *not* contain characters other than those + intended by the author of the work, although tilde + (~), asterisk (*) and underline (_) characters may + be used to convey punctuation intended by the + author, and additional characters may be used to + indicate hypertext links; OR + + [*] The eBook may be readily converted by the reader at + no expense into plain ASCII, EBCDIC or equivalent + form by the program that displays the eBook (as is + the case, for instance, with most word processors); + OR + + [*] You provide, or agree to also provide on request at + no additional cost, fee or expense, a copy of the + eBook in its original plain ASCII form (or in EBCDIC + or other equivalent proprietary form). + +[2] Honor the eBook refund and replacement provisions of this + "Small Print!" statement. + +[3] Pay a trademark license fee to the Foundation of 20% of the + gross profits you derive calculated using the method you + already use to calculate your applicable taxes. If you + don't derive profits, no royalty is due. Royalties are + payable to "Project Gutenberg Literary Archive Foundation" + the 60 days following each date you prepare (or were + legally required to prepare) your annual (or equivalent + periodic) tax return. Please contact us beforehand to + let us know your plans and to work out the details. + +WHAT IF YOU *WANT* TO SEND MONEY EVEN IF YOU DON'T HAVE TO? +Project Gutenberg is dedicated to increasing the number of +public domain and licensed works that can be freely distributed +in machine readable form. + +The Project gratefully accepts contributions of money, time, +public domain materials, or royalty free copyright licenses. +Money should be paid to the: +"Project Gutenberg Literary Archive Foundation." + +If you are interested in contributing scanning equipment or +software or other items, please contact Michael Hart at: +hart@pobox.com + +[Portions of this eBook's header and trailer may be reprinted only +when distributed free of all fees. Copyright (C) 2001, 2002 by +Michael S. Hart. Project Gutenberg is a TradeMark and may not be +used in any sales of Project Gutenberg eBooks or other materials be +they hardware or software or any other related product without +express permission.] + +*END THE SMALL PRINT! FOR PUBLIC DOMAIN EBOOKS*Ver.02/11/02*END* + diff --git a/old/8brd110.zip b/old/8brd110.zip Binary files differnew file mode 100644 index 0000000..a0c19fc --- /dev/null +++ b/old/8brd110.zip |