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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/25509-8.txt b/25509-8.txt new file mode 100644 index 0000000..ef50030 --- /dev/null +++ b/25509-8.txt @@ -0,0 +1,10356 @@ +The Project Gutenberg EBook of The World's Greatest Books - Volume 15 - +Science, by Various + +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 World's Greatest Books - Volume 15 - Science + +Author: Various + +Editor: John Alexander Hammerton + +Release Date: May 17, 2008 [EBook #25509] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK WORLD'S GREATEST BOOKS-VOLUME 15 *** + + + + +Produced by Kevin Handy, John Hagerson, Greg Bergquist and +the Online Distributed Proofreading Team at +https://www.pgdp.net + + + + + + +[Illustration: William Harvey] + + + + +THE WORLD'S +GREATEST +BOOKS + +JOINT EDITORS + +ARTHUR MEE +Editor and Founder of the Book of Knowledge + +J.A. HAMMERTON +Editor of Harmsworth's Universal Encyclopaedia + +VOL. XV + +SCIENCE + +WM. H. WISE & Co. + + + + +_Table of Contents_ + + +PORTRAIT OF WILLIAM HARVEY _Frontispiece_ + + PAGE + +BRAMWELL, JOHN MILNE + Hypnotism: Its History, Practice and Theory 1 + + +BUFFON, COMTE DE + Natural History 12 + + +CHAMBERS, ROBERT + Vestiges of Creation 22 + + +CUVIER, GEORGES + The Surface of the Globe 33 + + +DARWIN, CHARLES + The Origin of Species 43 + + +DAVY, SIR HUMPHRY + Elements of Chemical Philosophy 64 + + +FARADAY, MICHAEL + Experimental Researches in Electricity 75 + The Chemical History of a Candle 85 + + +FOREL, AUGUSTE + The Senses of Insects 95 + + +GALILEO + Dialogues on the System of the World 105 + + +GALTON, SIR FRANCIS + Essays in Eugenics 111 + + +HAECKEL, ERNST + The Evolution of Man 123 + + +HARVEY, WILLIAM + On the Motion of the Heart and Blood 136 + + +HERSCHEL, SIR JOHN + Outlines of Astronomy 146 + + +HUMBOLDT, ALEXANDER VON + Cosmos, a Sketch of the Universe 158 + + +HUTTON, JAMES + The Theory of the Earth 170 + + +LAMARCK + Zoological Philosophy 179 + + +LAVATER, JOHANN + Physiogonomical Fragments 191 + + +LIEBIG, JUSTUS VON + Animal Chemistry 203 + + +LYELL, SIR CHARLES + The Principles of Geology 215 + + +MAXWELL, JAMES CLERK + A Treatise on Electricity and Magnetism 227 + + +METCHNIKOFF, ELIE + The Nature of Man 238 + The Prolongation of Life 246 + + +MILLER, HUGH + The Old Red Sandstone 255 + + +NEWTON, SIR ISAAC + Principia 267 + + +OWEN, SIR RICHARD + Anatomy of Vertebrates 280 + + +VIRCHOW, RUDOLF + Cellular Pathology 292 + + * * * * * + +A Complete Index of THE WORLD'S GREATEST BOOKS will be found at the end +of Volume XX. + + + + +_Acknowledgment_ + + +Acknowledgment and thanks for the use of the following selections are +herewith tendered to the Open Court Publishing Company, La Salle, Ill., +for "Senses of Insects," by Auguste Forel; to G.P. Putnam's Sons, New +York, for "Prolongation of Human Life" and "Nature of Man," by Elie +Metchnikoff; and to the De La More Press, London, for "Hypnotism, &c.," +by Dr. Bramwell. + + + + +_Science_ + +JOHN MILNE BRAMWELL + +Hypnotism: Its History, Practice and Theory + + John Milne Bramwell was born in Perth, Scotland, May 11, 1852. The + son of a physician, he studied medicine in Edinburgh, and after + obtaining his degree of M.B., in 1873, he settled at Goole, + Yorkshire. Fired by the unfinished work of Braid, Bernheim and + Liébeault, he began, in 1889, a series of hypnotic researches, + which, together with a number of successful experiments he had + privately conducted, created considerable stir in the medical + world. Abandoning his general practice and settling in London in + 1892, Dr. Bramwell became one of the foremost authorities in the + country on hypnotism as a curative agent. His Works include many + valuable treatises, the most important being "Hypnotism: its + History, Practice and Theory," published in 1903, and here + summarised for the WORLD'S GREATEST BOOKS by Dr. Bramwell himself. + + +_I.--Pioneers of Hypnotism_ + +Just as chemistry arose from alchemy, astronomy from astrology, so +hypnotism had its origin in mesmerism. Phenomena such as Mesmer +described had undoubtedly been observed from early times, but to his +work, which extended from 1756 to his death, in 1815, we owe the +scientific interest which, after much error and self-deception, finally +led to what we now term hypnotism. + +John Elliotson (1791-1868), the foremost physician of his day, was the +leader of the mesmeric movement in England. In 1837, after seeing +Dupotet's work, he commenced to experiment at University College +Hospital, and continued, with remarkable success, until ordered to +desist by the council of the college. Elliotson felt the insult keenly, +indignantly resigned his appointments, and never afterwards entered the +hospital he had done so much to establish. Despite the persistent and +virulent attacks of the medical press, he continued his mesmeric +researches up to the time of his death, sacrificing friends, income and +reputation to his beliefs. + +The fame of mesmerism spread to India, where, in 1845, James Esdaile +(1808-1859), a surgeon in the East India Company, determined to +investigate the subject. He was in charge of the Native Hospital at +Hooghly, and successfully mesmerised a convict before a painful +operation. Encouraged by this, he persevered, and, at the end of a year, +reported 120 painless operations to the government. Investigations were +instituted, and Esdaile was placed in charge of a hospital at Calcutta, +for the express purpose of mesmeric practice; he continued to occupy +similar posts until he left India in 1851. He recorded 261 painless +capital operations and many thousand minor ones, and reduced the +mortality for the removal of the enormous tumours of elephantiasis from +50 to 5 per cent. + +According to Elliotson and Esdaile, the phenomena of mesmerism were +entirely physical in origin. They were supposed to be due to the action +of a vital curative fluid, or peculiar physical force, which, under +certain circumstances, could be transmitted from one human being to +another. This was usually termed the "od," or "odylic," force; various +inanimate objects, such as metals, crystals and magnets, were supposed +to possess it, and to be capable of inducing and terminating the +mesmeric state, or of exciting or arresting its phenomena. + +The name of James Braid (1795-1860) is familiar to all students of +hypnotism. Braid was a Scottish surgeon, practising in Manchester, where +he had already gained a high reputation as a skilful surgeon, when, in +1841, he first began to investigate mesmerism. He successfully +demonstrated that the phenomena were entirely subjective. He published +"Neurypnology, or the Rationale of Nervous Sleep," in 1843, and invented +the terminology we now use. This was followed by other more or less +important works, of which I have been able to trace forty-one, but all +have been long out of print. + +During the eighteen years Braid devoted to the study of hypnotism, his +views underwent many changes and modifications. In his first theory, he +explained hypnosis from a physical standpoint; in the second, he +considered it to be a condition of involuntary monoideism and +concentration, while his third theory differed from both. He recognised +that reason and volition were unimpaired, and that the attention could +be simultaneously directed to more points than one. The condition, +therefore, was not one of monoideism. He realised more and more that the +state was a conscious one, and that the losses of memory which followed +on waking could always be restored in subsequent hypnoses. Finally, he +described as "double consciousness" the condition he had first termed +"hypnotic," then "monoideistic." + +Braid maintained an active interest in hypnotism up to his death, and, +indeed, three days before it, sent his last MS. to Dr. Azam, of +Bordeaux, "as a mark of esteem and regard." Sympathetic notices appeared +in the press after his death, all of which bore warm testimony to his +professional character. Although hypnotic work practically ceased in +England at Braid's death, the torch he had lighted passed into France. + +In 1860, Dr. A.A. Liébeault (1823-1900) began to study hypnotism +seriously, and four years later gave up general practice, settled in +Nancy, and practised hypnotism gratuitously among the poor. For twenty +years his labours were unrecognised, then Bernheim (one of whose +patients Liébeault had cured) came to see him, and soon became a zealous +pupil. The fame of the Nancy school spread, Liébeault's name became +known throughout the world, and doctors flocked to study the new +therapeutic method. + +While Liébeault's work may justly be regarded as a continuation of +Braid's, there exists little difference between the theories of Charcot +and the Salpêtrière school and those of the later mesmerists. + + +_II.--Theory of Hypnotism_ + +The following is a summary of Braid's latest theories: (1) Hypnosis +could not be induced by physical means alone. (2) Hypnotic and so-called +mesmeric phenomena were subjective in origin, and both were excited by +direct or by indirect suggestion. (3) Hypnosis was characterised by +physical as well as by psychical changes. (4) The simultaneous +appearance of several phenomena was recognised, and much importance was +attached to the intelligent action of a secondary consciousness. (5) +Volition was unimpaired, moral sense increased, and suggested crime +impossible. (6) _Rapport_ was a purely artificial condition created by +suggestion. (7) The importance of direct verbal suggestion was fully +recognised, as also the mental influence of physical methods. Suggestion +was regarded as the device used for exciting the phenomena, and not +considered as sufficient to explain them. (8) Important differences +existed between hypnosis and normal sleep. (9) Hypnotic phenomena might +be induced without the subject having passed through any condition +resembling sleep. (10) The mentally healthy were the easiest, the +hysterical the most difficult, to influence. + +In England, during Braid's lifetime, his earlier views were largely +adopted by certain well-known men of science, particularly by Professors +W.B. Carpenter and J. Hughes Bennett, but they appear to have known +little or nothing of his latest theories. Bennett's description of the +probable mental and physical conditions involved in the state Braid +described as "monoideism" is specially worthy of note. Not only is it +interesting in itself, but it serves also as a standard of comparison +with which to measure the theories of later observers, who have +attempted to explain hypnosis by cerebral inhibition, psychical +automatism, or both these conditions combined. + +(a) _Physiological._--According to Bennett, hypnosis was characterised +by alterations in the functional activity of the nerve tubes of the +white matter of the cerebral lobes. He suggested that a certain +proportion of these became paralysed through continued monotonous +stimulation; while the action of others was consequently exalted. As +these tubes connected the cerebral ganglion-cells, suspension of their +functions was assumed to bring with it interruption of the connection +between the ganglion-cells. + +(b) _Psychical._--From the psychical side, he explained the phenomena of +hypnosis by the action of predominant and unchecked ideas. These were +able to obtain prominence from the fact that other ideas, which, under +ordinary circumstances, would have controlled their development, did not +arise, because the portion of the brain with which the latter were +associated had its action temporarily suspended--_i.e._, the connection +between the ganglion-cells was broken, owing to the interrupted +connection between the "fibres of association." Thus, he said, the +remembrance of a sensation could always be called up by the brain; but, +under ordinary circumstances, from the exercise of judgment, comparison, +and other mental faculties, we knew it was only a remembrance. When +these faculties were exhausted, the suggested idea predominated, and the +individual believed in its reality. Thus, he attributed to the faculties +of the mind a certain power of correcting the fallacies which each of +them was likely to fall into; just as the illusions of one sense were +capable of being detected by the healthy use of the other senses. There +were mental and sensorial illusions, the former caused by predominant +ideas and corrected by proper reasoning, the latter caused by perversion +of one sense and corrected by the right application of the others. + +In hypnosis, according to this theory, a suggested idea obtained +prominence and caused mental and sensorial illusions, because the check +action--the inhibitory power--of certain higher centres had been +temporarily suspended. These theories were first published by Professor +Bennett in 1851. + + +_III.--Hypnotic Induction_ + +The methods by which hypnosis is induced have been classed as follows: +(1) physical; (2) psychical; (3) those of the magnetisers. The modern +operator, whatever his theories may be, borrows his technique from +Mesmer and Liébeault with equal impartiality, and thus renders +classification impossible. The members of the Nancy school, while +asserting that everything is due to suggestion, do not hesitate to use +physical means, and, if these fail, Bernheim has recourse to narcotics. + +The following is now my usual method: I rarely begin treatment the first +time I see a patient, but confine myself to making his acquaintance, +hearing his account of his case, and ascertaining his mental attitude +with regard to suggestion. I usually find, from the failure of other +methods of treatment, that he is more or less sceptical as to the chance +of being benefited. I endeavour to remove all erroneous ideas, and +refuse to begin treatment until the patient is satisfied of the safety +and desirability of the experiment. I never say I am certain of being +able to influence him, but explain how much depends on his mental +attitude and power of carrying out my directions. I further explain to +the patient that next time he comes to see me I shall ask him to close +his eyes, to concentrate his attention on some drowsy mental picture, +and try to turn it away from me. I then make suggestions of two kinds: +the first refer to the condition I wish to induce while he is actually +in the armchair, thus, "Each time you see me, you will find it easier to +concentrate your attention on something restful. I do not wish you to go +to sleep, but if you can get into the drowsy condition preceding natural +sleep, my suggestions are more likely to be responded to." I explain +that I do not expect this to happen at once, although it does occur in +rare instances, but it is the repetition of the suggestions made in this +particular way which brings about the result. Thus, from the very first +treatment, the patient is subjected to two distinct processes, the +object of one being to induce the drowsy, suggestible condition, that of +the other to cure or relieve disease. + +I wish particularly to mention that although I speak of hypnotism and +hypnosis--and it is almost impossible to avoid doing so--I rarely +attempt to induce so-called hypnosis, and find that patients respond to +treatment as readily, and much more quickly, now that I start curative +suggestions and treatment simultaneously, than they did in the days when +I waited until hypnosis was induced before making curative suggestions. + +I have obtained good results in treating all forms of hysteria, +including _grande hysterie_, neurasthenia, certain forms of insanity, +dipsomania and chronic alcoholism, morphinomania and other drug habits, +vicious and degenerate children, obsessions, stammering, chorea, +seasickness, and all other forms of functional nervous disturbances. + +It is impossible to discuss the different theories in detail here, but I +will briefly summarise the more important points, (1) Hypnotism, as a +science, rests on the recognition of the subjective nature of its +phenomena. (2) The theories of Charcot and the Salpêtrière school are +practically a reproduction of mesmeric error. (3) Liébeault and his +followers combated the views of the Salpêtrière school and successfully +substituted their own, of which the following are the important points: +(_a_) Hypnosis is a physiological condition, which can be induced in the +healthy. (_b_) In everyone there is a tendency to respond to suggestion, +but in hypnosis this condition is artificially increased. (_c_) +Suggestion explains all. Despite the fact that the members of the Nancy +school regard the condition as purely physiological and simply an +exaggeration of the normal, they consider it, in its profound stages at +all events, a form of automatism. + +These and other views of the Nancy school have been questioned by +several observers. As Myers justly pointed out, although suggestion is +the artifice used to excite the phenomena, it does not create the +condition on which they depend. The peculiar state which enables the +phenomena to be evoked is the essential thing, not the signal which +precedes their appearance. + +Within recent times another theory has arisen, which, instead of +explaining hypnotism by the arrested action of some of the brain centres +which subserve normal life, attempts to do so by the arousing of certain +powers over which we normally have little or no control. This theory +appears under different names, "Double Consciousness," "Das Doppel-Ich," +etc., and the principle on which it depends is largely admitted by +science. William James, for example, says: "In certain persons, at +least, the total possible consciousness may be split into parts which +co-exist, but mutually ignore each other." + +The clearest statement of this view was given by the late Frederic +Myers; he suggested that the stream of consciousness in which we +habitually lived was not our only one. Possibly our habitual +consciousness might be a mere selection from a multitude of thoughts +and sensations--some, at least, equally conscious with those we +empirically knew. No primacy was granted by this theory to the ordinary +waking self, except that among potential selves it appeared the fittest +to meet the needs of common life. As a rule, the waking life was +remembered in hypnosis, and the hypnotic life forgotten in the waking +state; this destroyed any claim of the primary memory to be the sole +memory. The self below the threshold of ordinary consciousness Myers +termed the "subliminal consciousness," and the empirical self of common +experience the "supraliminal." He held that to the subliminal +consciousness and memory a far wider range, both of physiological and +psychical activity, was open than to the supraliminal. The latter was +inevitably limited by the need of concentration upon recollections +useful in the struggle for existence; while the former included much +that was too rudimentary to be retained in the supraliminal memory of an +organism so advanced as that of man. The recollection of processes now +performed automatically and needing no supervision, passed out of the +supraliminal memory, but might be retained by the subliminal. The +subliminal, or hypnotic, self could exercise over the vaso-motor and +circulatory systems a degree of control unparalleled in waking life. + +Thus, according to the Nancy school, the deeply hypnotised subject +responds automatically to suggestion before his intellectual centres +have had time to bring their inhibitory action into play; but, on the +other hand, in the subliminal consciousness theory, volition and +consciousness are recognised to be unimpaired in hypnosis. + + +_IV.--Curative Value of Hypnotism_ + +The intelligent action of the secondary self may be illustrated by the +execution of certain post-hypnotic acts. Thus, one of my patients who, +at a later period, consented to become the subject of experiment, +developed an enormously increased power of time appreciation. If told, +during hypnosis, for example, that she was to perform some specific act +in the waking state at the expiration of a complicated number of +minutes, as, for example, 40,825, she generally carried out the +suggestion with absolute accuracy. In this and similar experiments, +three points were noted. (1) The arithmetical problems were far beyond +her normal powers; (2) she normally possessed no special faculty for +appreciating time; (3) her waking consciousness retained no recollection +of the experimental suggestions or of anything else that had occurred +during hypnosis. + +It is difficult to estimate the exact value of suggestion in connection +with other forms of treatment. There are one or two broad facts which +ought to be kept in mind. + +1. Suggestion is a branch of medicine, which is sometimes combined by +those who practise it with other forms of treatment. Thus it is often +difficult to say what proportion of the curative results is due to +hypnotism and what to other remedies. + +2. On the other hand, many cases of functional nervous disorder have +recovered under suggestive treatment after the continued failure of +other methods. Further, the diseases which are frequently cured are +often those in which drugs are of little or no avail. For example, what +medicine would one prescribe for a man in good physical health who had +suddenly become the prey of an obsession? Such patients are rarely +insane; they recognise that the idea which torments them is morbid; but +yet they are powerless to get rid of it. + +3. In estimating the results of suggestive treatment, it must not be +forgotten that the majority of cases are extremely unfavourable ones. As +the value of suggestion and its freedom from danger become more fully +recognised, it will doubtless be employed in earlier stages of disease. + +4. It should be clearly understood that the object of all suggestive +treatment ought to be the development of the patient's will power and +control of his own organism. Much disease would be prevented if we could +develop and control moral states. + + + + +BUFFON + +Natural History + + Georges Louis Leclerc, created in 1773 Comte de Buffon, was born at + Montbard, in France, on September 7, 1707. Evincing a marked bent + for science he became, in 1739, director of the Jardin du Roi and + the King's Museum in Paris. He had long contemplated the + preparation of a complete History of Nature, and now proceeded to + carry out the work. The first three volumes of the "Histoire + Naturelle, Générale et Particulière" appeared in 1749, and other + volumes followed at frequent intervals until his death at Paris on + April 16, 1788. Buffon's immense enterprise was greeted with + abounding praise by most of his contemporaries. On July 1, 1752, he + was elected to the French Academy in succession to Languet de + Gergy, Archbishop of Sens, and, at his reception on August 25 in + the following year, pronounced the oration in which occurred the + memorable aphorism, "Le style est l'homme même" (The style is the + very man). Buffon also anticipated Thomas Carlyle's definition of + genius ("which means the transcendent capacity of taking trouble, + first of all") by his famous axiom, "Le génie n'est autre chose + qu'une grande aptitude à la patience." + + +_Scope of the Work_ + +Buffon planned his "Natural History" on an encyclopaedic scale. His +point of view was unique. Natural history in its widest sense, he tells +us, embraces every object in the visible universe. The obvious divisions +of the subject, therefore, are, first, the earth, the air, and the +water; then the animals--quadrupeds, birds, fishes, and so +on--inhabiting each of these "elements," to use the phrase of his day. +Now, Buffon argued, if man were required to give some account of the +animals by which he was surrounded, of course he would begin with those +with which he was most familiar, as the horse, the dog, the cow. From +these he would proceed to the creatures with which he was less familiar, +and finally deal--through the medium of travellers' tales and other +sources of information--with the denizens of field, forest and flood in +foreign lands. In similar fashion he would consider the plants, +minerals, and other products of Nature, in addition to recounting the +marvels revealed to him by astronomy. + +Whatever its defects on the scientific side, Buffon's plan was +simplicity itself, and was adopted largely, if not entirely, in +consequence of his contempt--real or affected--for the systematic method +of the illustrious Linnæus. Having charted his course, the rest was +plain sailing. He starts with the physical globe, discussing the +formation of the planets, the features of the earth--mountains, rivers, +seas, lakes, tides, currents, winds, volcanoes, earthquakes, islands, +and so forth--and the effects of the encroachment and retreat of the +ocean. + +Animate nature next concerns him. After comparing animals, plants and +minerals, he proceeds to study man literally from the cradle to the +grave, garnishing the narrative with those incursions into the domains +of psychology, physiology and hygiene, which, his detractors insinuated, +rendered his work specially attractive and popular. + + +_I.--The Four-Footed Animals_ + +Such questions occupied the first three volumes, and the ground was now +cleared for the celebrated treatise on Quadrupeds, which filled no fewer +than twelve volumes, published at various dates from 1753 (vol. iv.) to +1767 (vol. xv., containing the New World monkeys, indexes, and the +like). Buffon's _modus operandi_ saved him from capital blunders. Though +inordinately vain--"I know but five great geniuses," he once said; +"Newton, Bacon, Leibniz, Montesquieu, and myself"--he was quite +conscious of his own limitations, and had the common-sense to entrust to +Daubenton the description of the anatomy and other technical matters as +to which his own knowledge was comparatively defective. He reserved to +himself what may be called the "literary" aspect of his theme, recording +the place of each animal in history, and relating its habits with such +gusto as his ornate and grandiose style permitted. + +After a preliminary dissertation on the nature of animals, Buffon +plunges into an account of those that have been domesticated or tamed. +Preference of place is given to the horse, and his method of treatment +is curiously anticipatory of modern lines. Beginning with some notice of +the horse in history, he goes on to describe its appearance and habits +and the varieties of the genus, ending (by the hand of Daubenton) with +an account of its structure and physiology. As evidence of the pains he +took to collect authority for his statements, it is of interest to +mention that he illustrates the running powers of the English horse by +citing the instance of Thornhill, the postmaster of Stilton, who, in +1745, wagered he would ride the distance from Stilton to London thrice +in fifteen consecutive hours. Setting out from Stilton, and using eight +different horses, he accomplished his task in 3 hours 51 minutes. In the +return journey he used six horses, and took 3 hours 52 minutes. For the +third race he confined his choice of horses to those he had already +ridden, and, selecting seven, achieved the distance in 3 hours 49 +minutes. He performed the undertaking in 11 hours and 32 minutes. "I +doubt," comments Buffon, "whether in the Olympic Games there was ever +witnessed such rapid racing as that displayed by Mr. Thornhill." + +Justice having been done to it, the horse gives place to the ass, ox, +sheep, goat, pig, dog, and cat, with which he closes the account of the +domesticated animals, to which three volumes are allotted. It is +noteworthy that Buffon frequently, if not always, gives the synonyms of +the animals' names in other languages, and usually supports his textual +statements by footnote references to his authorities. + +When he comes to the Carnivores--"les animaux nuisibles"--the defects of +Buffon's higgledy-piggledy plan are almost ludicrously evident, for +flesh-eaters, fruit-eaters, insect-eaters, and gnawers rub shoulders +with colossal indifference. Doubtless, however, this is to us all the +more conspicuous, because use and wont have made readers of the present +day acquainted with the advantages of classification, which it is but +fair to recognise has been elaborated and perfected since Buffon's time. + +As his gigantic task progressed, Buffon's difficulties increased. At the +beginning of vol. xii. (1764) he intimates that, with a view to break +the monotony of a narrative in which uniformity is an unavoidable +feature, he will in future, from time to time, interrupt the general +description by discourses on Nature and its effects on a grand scale. +This will, he naively adds, enable him to resume "with renewed courage" +his account of details the investigation of which demands "the calmest +patience, and affords no scope for genius." + + +_II.--The Birds_ + +Scarcely had he finished the twelve volumes of Quadrupeds when Buffon +turned to the Birds. If this section were less exacting, yet it made +enormous claims upon his attention, and nine volumes were occupied +before the history of the class was concluded. Publication of "Des +Oiseaux" was begun in 1770, and continued intermittently until 1783. But +troubles dogged the great naturalist. The relations between him and +Daubenton had grown acute, and the latter, unwilling any longer to put +up with Buffon's love of vainglory, withdrew from the enterprise to +which his co-operation had imparted so much value. Serious illness, +also, and the death of Buffon's wife, caused a long suspension of his +labours, which were, however, lightened by the assistance of Guéneau de +Montbéliard. + +One stroke of luck he had, which no one will begrudge the weary Titan. +James Bruce, of Kinnaird, on his return from Abyssinia in 1773, spent +some time with Buffon at his château in Montbard, and placed at his +disposal several of the remarkable discoveries he had made during his +travels. Buffon was not slow to appreciate this godsend. Not only did +he, quite properly, make the most of Bruce's disinterested help, but he +also expressed the confident hope that the British Government would +command the publication of Bruce's "precious" work. He went on to pay a +compliment to the English, and so commit them to this enterprise. "That +respectable nation," he asserts, "which excels all others in discovery, +can but add to its glory in promptly communicating to the world the +results of the excellent travellers' researches." + +Still unfettered by any scheme of classification, either scientific or +logical, Buffon begins his account of the birds with the eagles and +owls. To indicate his course throughout the vast class, it will suffice +to name a few of the principal birds in the order in which he takes them +after the birds of prey. These, then, are the ostrich, bustard, game +birds, pigeons, crows, singing birds, humming birds, parrots, cuckoos, +swallows, woodpeckers, toucans, kingfishers, storks, cranes, secretary +bird, herons, ibis, curlews, plovers, rails, diving birds, pelicans, +cormorants, geese, gulls, and penguins. With the volume dealing with the +picarian birds (woodpeckers) Buffon announces the withdrawal of Guéneau +de Montbéliard, and his obligations for advice and help to the Abbé +Bexon (1748-1784), Canon of Sainte Chapelle in Paris. + + +_III.--Supplement and Sequel_ + +At the same time that the Birds volumes were passing through the press, +Buffon also issued periodically seven volumes of a supplement +(1774-1789), the last appearing posthumously under the editorship of +Count Lacépède. This consisted of an olla podrida of all sorts of +papers, such as would have won the heart of Charles Godfrey Leland. The +nature of the hotchpotch will be understood from a recital of some of +its contents, in their chronological order. It opened with an +introduction to the history of minerals, partly theoretical (concerning +light, heat, fire, air, water, earth, and the law of attraction), and +partly experimental (body heat, heat in minerals, the nature of +platinum, the ductility of iron). Then were discussed incandescence, +fusion, ships' guns, the strength and resistance of wood, the +preservation of forests and reafforestation, the cooling of the earth, +the temperature of planets, additional observations on quadrupeds +already described, accounts of animals not noticed before, such as the +tapir, quagga, gnu, nylghau, many antelopes, the vicuña, Cape ant-eater, +star-nosed mole, sea-lion, and others; the probabilities of life (a +subject on which the author plumed himself), and his essay on the Epochs +of Nature. + +Nor did these concurrent series of books exhaust his boundless energy +and ingenuity, for in the five years preceding his death (1783-1788), he +produced his "Natural History of Minerals" in five volumes, the last of +which was mainly occupied with electricity, magnetism, and the +loadstone. It is true that the researches of modern chemists have +wrought havoc with Buffon's work in this field; but this was his +misfortune rather than his fault, and leaves untouched the quantity of +his output. + +Buffon invoked the aid of the artist almost from the first, and his +"Natural History" is illustrated by hundreds of full-page copper-plate +engravings, and embellished with numerous elegant headpiece designs. The +figures of the animals are mostly admirable examples of portraiture, +though the classical backgrounds lend a touch of the grotesque to many +of the compositions. Illustrations of anatomy, physiology, and other +features of a technical character are to be numbered by the score, and +are, of course, indispensable in such a work. The _editio princeps_ is +cherished by collectors because of the 1,008 coloured plates ("Planches +Enluminées") in folio, the text itself being in quarto, by the younger +Daubenton, whose work was spiritedly engraved by Martinet. Apparently +anxious to illustrate one section exhaustively rather than several +sections in a fragmentary manner, the artist devoted himself chiefly to +the birds, which monopolise probably nine-tenths of the plates, and to +which he may also have been attracted by their gorgeous plumages. + +As soon as the labourer's task was over, his scientific friends thought +the best monument which they could raise to his memory was to complete +his "Natural History." This duty was discharged by two men, who, both +well qualified, worked, however, on independent lines. Count Lacépède, +adhering to the format of the original, added two volumes on the +Reptiles (1788-1789), five on the Fishes (1798-1803), and one on the +Cetaceans (1804). Sonnini de Manoncourt (1751-1812), feeling that this +edition, though extremely handsome, was cumbersome, undertook an +entirely new edition in octavo. This was begun in 1797, and finished in +1808. It occupied 127 volumes, and, Lacépède's treatises not being +available, Sonnini himself dealt with the Fishes (thirteen volumes) and +Whales (one volume), P.A. Latreille with the Crustaceans and Insects +(fourteen volumes), Denys-Montfort with the Molluscs (six volumes), F.M. +Dandin with the Reptiles (eight volumes), and C.F. Brisseau-Mirbel and +N. Jolyclerc with the Plants (eighteen volumes). Sonnini's edition +constituted the cope-stone of Buffon's work, and remained the best +edition, until the whole structure was thrown down by the views of later +naturalists, who revolutionised zoology. + + +_IV.--Place and Doctrine_ + +Buffon may justly be acclaimed as the first populariser of natural +history. He was, however, unscientific in his opposition to systems, +which, in point of fact, essentially elucidated the important doctrine +that a continuous succession of forms runs throughout the animal +kingdom. His recognition of this principle was, indeed, one of his +greatest services to the science. + +Another of his wise generalisations was that Nature proceeds by unknown +gradations, and consequently cannot adapt herself to formal analysis, +since she passes from one species to another, and often from one genus +to another, by shades of difference so delicate as to be wholly +imperceptible. + +In Buffon's eyes Nature is an infinitely diversified whole which it is +impossible to break up and classify. "The animal combines all the powers +of Nature; the forces animating it are peculiarly its own; it wishes, +does, resolves, works, and communicates by its senses with the most +distant objects. One's self is a centre where everything agrees, a point +where all the universe is reflected, a world in miniature." In natural +history, accordingly, each animal or plant ought to have its own +biography and description. + +Life, Buffon also held, abides in organic molecules. "Living beings are +made up of these molecules, which exist in countless numbers, which may +be separated but cannot be destroyed, which pierce into brute matter, +and, working there, develop, it may be animals, it may be plants, +according to the nature of the matter in which they are lodged. These +indestructible molecules circulate throughout the universe, pass from +one being to another, minister to the continuance of life, provide for +nutrition and the growth of the individual, and determine the +reproduction of the species." + +Buffon further taught that the quantity and quality of life pass from +lower to higher stages--in Tennysonian phrase, men "rise on +stepping-stones of their dead selves to higher things"--and showed the +unity and structure of all beings, of whom man is the most perfect type. + +It has been claimed that Buffon in a measure anticipated Lamarck and +Darwin. He had already foreseen the mutability of species, but had not +succeeded in proving it for varieties and races. If he asserted that the +species of dog, jackal, wolf and fox were derived from a single one of +these species, that the horse came from the zebra, and so on, this was +far from being tantamount to a demonstration of the doctrine. In fact, +he put forward the mutability of species rather as probable theory than +as established truth, deeming it the corollary of his views on the +succession and connection of beings in a continuous series. + +Some case may be made out for regarding Buffon as the founder of +zoogeography; at all events he was the earliest to determine the natural +habitat of each species. He believed that species changed with climate, +but that no kind was found throughout all the globe. Man alone has the +privilege of being everywhere and always the same, because the human +race is one. The white man (European or Caucasian), the black man +(Ethiopian), the yellow man (Mongol), and the red man (American) are +only varieties of the human species. As the Scots express it with wonted +pith, "We're a' Jock Tamson's bairns." + +As to his geological works, Buffon expounded two theories of the +formation of the globe. In his "Théorie de la Terre" he supported the +Neptunists, who attributed the phenomena of the earth to the action of +water. In his "Epoques de la Nature" he amplified the doctrines of +Leibniz, and laid down the following propositions: (1) The earth is +elevated at the equator and depressed at the poles in accordance with +the laws of gravitation and centrifugal force; (2) it possesses an +internal heat, apart from that received from the sun; (3) its own heat +is insufficient to maintain life; (4) the substances of which the earth +is composed are of the nature of glass, or can be converted into glass +as the result of heat and fusion--that is, are verifiable; (5) +everywhere on the surface, including mountains, exist enormous +quantities of shells and other maritime remains. + +To the theses just enumerated Buffon added what he called the +"monuments," or what Hugh Miller, a century later, more aptly described +as the Testimony of the Rocks. From a consideration of all these things, +Buffon at length arrived at his succession of the Epochs, or Seven Ages +of Nature, namely: (1) the Age of fluidity, or incandescence, when the +earth and planets assumed their shape; (2) the Age of cooling, or +consolidation, when the rocky interior of the earth and the great +vitrescible masses at its surface were formed; (3) the Age when the +waters covered the face of the earth; (4) the Age when the waters +retreated and volcanoes became active; (5) the Age when the elephant, +hippopotamus, rhinoceros, and other giants roamed through the northern +hemisphere; (6) the Age of the division of the land into the vast areas +now styled the Old and the New Worlds; and (7) the Age when Man +appeared. + + + + +ROBERT CHAMBERS + +Vestiges of Creation + + Robert Chambers was born in Peebles, Scotland, July 10, 1802, and + died at St. Andrews on March 17, 1871. He was partner with his + brother in the publishing firm of W. & R. Chambers, was editor of + "Chambers's Journal," and was author of several works when he + published anonymously, in October 1844, the work by which his name + will always be remembered, "Vestiges of the Natural History of + Creation." His previous works, some thirty in number, did not deal + with science, and his labour in preparing his masterpiece was + commensurate with the courage which such an undertaking involved. + When the book was published, such interest and curiosity as to its + authorship were aroused that we have to go back to the publication + of "Waverley" for a parallel. Little else was talked about in + scientific circles. The work was violently attacked by many hostile + critics, F.W. Newman, author of an early review, being a + conspicuous exception. In the historical introduction to the + "Origin of Species," Darwin speaks of the "brilliant and powerful + style" of the "Vestiges," and says that "it did excellent service + in this country in calling attention to the subject, in removing + prejudice, and in thus preparing the ground for the reception of + analogous views." Darwin's idea of selection as the key to the + history of species does not occur in the "Vestiges," which belongs + to the Lamarckian school of unexamined belief in the hereditary + transmission of the effects of use and disuse. + + +_I.--The Reign of Universal Law_ + +The stars are suns, and we can trace amongst them the working of the +laws which govern our sun and his family. In these universal laws we +must perceive intelligence; something of which the laws are but as the +expressions of the will and power. The laws of Nature cannot be regarded +as primary or independent causes of the phenomena of the physical world. +We come, in short, to a Being beyond Nature--its author, its God; +infinite, inconceivable, it may be, and yet one whom these very laws +present to us with attributes showing that our nature is in some way a +faint and far-cast shadow of His, while all the gentlest and the most +beautiful of our emotions lead us to believe that we are as children in +His care and as vessels in His hand. Let it then be understood--and this +for the reader's special attention--that when natural law is spoken of +here, reference is made only to the mode in which the Divine Power is +exercised. It is but another phrase for the action of the ever-present +and sustaining God. + +Viewing Nature in this light, the pursuit of science is but the seeking +of a deeper acquaintance with the Infinite. The endeavour to explain any +events in her history, however grand or mysterious these may be, is only +to sit like a child at a mother's knee, and fondly ask of the things +which passed before we were born; and in modesty and reverence we may +even inquire if there be any trace of the origin of that marvellous +arrangement of the universe which is presented to our notice. In this +inquiry we first perceive the universe to consist of a boundless +multitude of bodies with vast empty spaces between. We know of certain +motions among these bodies; of other and grander translations we are +beginning to get some knowledge. Besides this idea of locality and +movement, we have the equally certain one of a former soft and more +diffused state of the materials of these bodies; also a tolerably clear +one as to gravitation having been the determining cause of both locality +and movement. From these ideas the general one naturally suggested to us +is--a former stage in the frame of material things, perhaps only a point +in progress from some other, or a return from one like the +present--universal space occupied with gasiform matter. This, however, +was of irregular constitution, so that gravitation caused it to break up +and gather into patches, producing at once the relative localities of +astral and solar systems, and the movements which they have since +observed, in themselves and with regard to each other--from the daily +spinning of single bodies on their own axes, to the mazy dances of vast +families of orbs, which come to periods only in millions of years. + +How grand, yet how simple the whole of this process--for a God only to +conceive and do, and yet for man, after all, to trace out and ponder +upon. Truly must we be in some way immediate to the august Father, who +can think all this, and so come into His presence and council, albeit +only to fall prostrate and mutely adore. + +Not only are the orbs of space inextricably connected in the manner +which has been described, but the constitution of the whole is uniform, +for all consist of the same chemical elements. And now, in our version +of the romance of Nature, we descend from the consideration of +orb-filled space and the character of the universal elements, to trace +the history of our own globe. And we find that this falls significantly +into connection with the primary order of things suggested by Laplace's +theory of the origin of the solar system in a vast nebula or fire-mist, +which for ages past has been condensing under the influence of +gravitation and the radiation of its heat. + + +_II.--History of the Earth's Crust_ + +When we study the earth's crust we find that it consists of layers or +strata, laid down in succession, the earlier under the influence of +heat, the later under the influence of water. These strata in their +order might be described as a record of the state of life upon our +planet from an early to a comparatively recent period. It is truly such +a record, but not one perfectly complete. + +Nevertheless, we find a noteworthy and significant sequence. We learn +that there was dry land long before the occurrence of the first fossils +of land plants and animals. In different geographical formations we +find various species, though sometimes the same species is found in +different formations, having survived the great earth changes which the +record of the rocks indicates. There is an unbroken succession of animal +life from the beginning to the present epoch. Low down, where the +records of life begin, we find an era of backboneless animals only, and +the animal forms there found, though various, are all humble in their +respective lines of gradation. + +The early fishes were low, both with respect to their class as fishes, +and the order to which they belong--that of the cartilaginous or gristly +fishes. In all the orders of ancient animals there is an ascending +gradation of character from first to last. Further, there is a +succession from low to high types in fossil plants, from the earliest +strata in which they are found to the highest. Several of the most +important living species have left no record of themselves in any +formation beyond what are, comparatively speaking, modern. Such are the +sheep and the goat, and such, above all, is our own species. Compared +with many humbler animals, man is a being, as it were, of yesterday. + +Thus concludes the wondrous section of the earth's history which is told +by geology. It takes up our globe at an early stage in the formation of +its crust--conducts it through what we have every reason to believe were +vast spaces of time, in the course of which many superficial changes +took place, and vegetable and animal life was gradually evolved--and +drops it just at the point when man was apparently about to enter on the +scene. The compilation of such a history, from materials of so +extraordinary a character, and the powerful nature of the evidence which +these materials afford, are calculated to excite our admiration, and the +result must be allowed to exalt the dignity of science as a product of +man's industry and his reason. + +It is now to be remarked that there is nothing in the whole series of +operations displayed in inorganic geology which may not be accounted for +by the agency of the ordinary forces of Nature. Those movements of +subterranean force which thrust up mountain ranges and upheaved +continents stand in inextricable connection, on the one hand, with the +volcanoes which are yet belching forth lavas and shaking large tracts of +ground, as, on the other, with the primitive incandescent state of the +earth. Those forces which disintegrated the early rocks, of which +detritus formed new beds at the bottom of the sea, are still seen at +work to the same effect. + +To bring these truths the more nearly before us, it is possible to make +a substance resembling basalt in a furnace; limestone and sandstone have +both been formed from suitable materials in appropriate receptacles; the +phenomena of cleavage have, with the aid of electricity, been simulated +on a small scale, and by the same agent crystals are formed. In short, +the remark which was made regarding the indifference of the cosmical +laws to the scale on which they operated is to be repeated regarding the +geological. + +A common furnace will sometimes exemplify the operation of forces which +have produced the Giant's Causeway; and in a sloping ploughed field +after rain we may often observe, at the lower end of a furrow, a handful +of washed and neatly deposited mud or sand, capable of serving as an +illustration of the way in which Nature has produced the deltas of the +Nile and Ganges. In the ripple-marks on sandy beaches of the present day +we see Nature's exact repetition of the operations by which she +impressed similar features on the sandstones of the carboniferous era. +Even such marks as wind-slanted rain would in our day produce on +tide-deserted sands have been read upon tablets of the ancient strata. + +It is the same Nature--that is to say, God through or in the manner of +Nature--working everywhere and in all time, causing the wind to blow, +and the rain to fall, and the tide to ebb and flow, inconceivable ages +before the birth of our race, as now. So also we learn from the conifers +of those old ages that there were winter and summer upon earth, before +any of us lived to liken the one to all that is genial in our own +nature, or to say that the other breathed no airs so unkind as man's +ingratitude. Let no one suppose there is any necessary disrespect for +the Creator in thus tracing His laws in their minute and familiar +operations. There is really no true great and small, grand and familiar, +in Nature. Such only appear when we thrust ourselves in as a point from +which to start in judging. Let us pass, if possible, beyond immediate +impressions, and see all in relation to Cause, and we shall chastenedly +admit that the whole is alike worshipful. + +The Creator, then, is seen to have formed our earth, and effected upon +it a long and complicated series of changes, in the same manner in which +we find that he conducts the affairs of Nature before our living eyes; +that is, in the manner of natural law. This is no rash or unauthorised +affirmation. It is what we deduce from the calculation of a Newton and a +Laplace on the one hand, and from the industrious observation of facts +by a Murchison and a Lyell on the other. It is a point of stupendous +importance in human knowledge; here at once is the whole region of the +inorganic taken out of the dominion of marvel, and placed under an idea +of Divine regulation. + + +_III.--The History of the Earth's Life_ + +Mixed up, however, with the geological changes, and apparently as final +object connected with the formation of the globe itself, there is +another set of phenomena presented in the course of our history--the +coming into existence, namely, of a long suite of living things, +vegetable and animal, terminating in the families which we still see +occupying the surface. The question arises: In what manner has this set +of phenomena originated? Can we touch at and rest for a moment on the +possibility of plants and animals having likewise been produced in a +natural way, thus assigning immediate causes of but one character for +everything revealed to our sensual observation; or are we at once to +reject this idea, and remain content, either to suppose that creative +power here acted in a different way, or to believe unexaminingly that +the inquiry is one beyond our powers? Taking the last question first, I +would reply that I am extremely loth to imagine that there is anything +in Nature which we should, for any reason, refrain from examining. If we +can infer aught from the past history of science, it is that the whole +of Nature is a legitimate field for the exercise of our intellectual +faculties; that there is a connection between this knowledge and our +well-being; and that, if we may judge from things once despaired of by +our inquiring reason, but now made clear and simple, there is none of +Nature's mysteries which we may not hopefully attempt to penetrate. To +remain idly content to presume a various class of immediate causes for +organic Nature seems to me, on this ground, equally objectionable. + +With respect to the other question the idea has several times arisen +that some natural course was observed in the production of organic +things, and this even before we were permitted to attain clear +conclusions regarding inorganic nature. It was always set quickly aside +as unworthy of serious consideration. The case is different now, when we +have admitted law in the whole domain of the inorganic. + +Otherwise, the absurdities into which we should be led must strike every +reflecting mind. The Eternal Sovereign arranges a solar or an astral +system, by dispositions imparted primordially to matter; he causes, by +the same means, vast oceans to join and continents to rise, and all the +grand meteoric agencies to proceed in ceaseless alternation, so as to +fit the earth for a residence of organic beings. But when, in the course +of these operations, fuci and corals are to be, for the first time, +placed in these oceans, a change in his plan of administration is +required. It is not easy to say what is presumed to be the mode of his +operations. The ignorant believe the very hand of Deity to be at work. +Amongst the learned, we hear of "creative fiats," "interferences," +"interpositions of the creative energy," all of them very obscure +phrases, apparently not susceptible of a scientific explanation, but all +tending simply to this: that the work was done in a marvellous way, and +not in the way of Nature. + +But we need not assume two totally distinct modes of the exercise of the +divine power--one in the course of inorganic nature and the other in +intimately connected course of organic nature. + +Indeed, when all the evidence is surveyed, it seems difficult to resist +the impression that vestiges, at least, are seen of the manner and +method of the Creator in this part of His work. It appears to be a case +in which rigid proof is hardly to be looked for. But such evidences as +exist are remarkably consistent and harmonious. The theory pointed to +consorts with everything else which we have learned accurately regarding +the history of the universe. Science has not one positive affirmation on +the other side. Indeed, the view opposed to it is not one in which +science is concerned; it appears as merely one of the prejudices formed +in the non-age of our race. + +For the history, then, of organic nature, I embrace, not as a proved +fact, but as a rational interpretation of things as far as science has +revealed them, the idea of progressive development. We contemplate the +simplest and most primitive types of being as giving birth to a type +superior to it; this again producing the next higher, and so on to the +highest. We contemplate, in short, a universal gestation of Nature, like +that of the individual being, and attended as little by circumstances of +a miraculous kind as the silent advance of an ordinary mother from one +week to another of her pregnancy. + +Thus simple--after ages of marvelling--appears organic creation, while +yet the whole phenomena are, in another point of view, wonders of the +highest kind, being the undoubted results of ordinances arguing the +highest attributes of foresight, skill and goodness on the part of their +Divine Author. + +If, finally, we study the mind of man, we find that its Almighty Author +has destined it, like everything else, to be developed from inherent +qualities. + +Thus the whole appears complete on one principle. The masses of space +are formed by law; law makes them in due time theatres of existence for +plants and animals; sensation, disposition, intellect, are all in like +manner sustained in action by law. + +It is most interesting to observe into how small a field the whole of +the mysteries of Nature thus ultimately resolve themselves. The +inorganic has been thought to have one final comprehensive +law--gravitation. The organic, the other great department of mundane +things, rests in like manner on one law, and that is--development. Nor +may even these be after all twain, but only branches of one still more +comprehensive law, the expression of a unity flowing immediately from +the One who is first and last. + + +_IV.--The Future and its Meaning_ + +The question whether the human race will ever advance far beyond its +present position in intellect and morals is one which has engaged much +attention. Judging from the past, we cannot reasonably doubt that great +advances are yet to be made; but, if the principle of development be +admitted, these are certain, whatever may be the space of time required +for their realisation. A progression resembling development may be +traced in human nature, both in the individual and in large groups of +men. Not only so, but by the work of our thoughtful brains and busy +hands we modify external nature in a way never known before. The +physical improvements wrought by man upon the earth's surface I conceive +as at once preparations for, and causes of, the possible development of +higher types of humanity, beings less strong in the impulsive parts of +our nature, more strong in the reasoning and moral, more fitted for the +delights of social life, because society will then present less to dread +and more to love. + +The history and constitution of the world have now been hypothetically +explained, according to the best lights which a humble individual has +found within the reach of his perceptive and reasoning faculties. + +We have seen a system in which all is regularity and order, and all +flows from, and is obedient to, a divine code of laws of unbending +operation. We are to understand from what has been laid before us that +man, with his varied mental powers and impulses, is a natural problem of +which the elements can be taken cognisance of by science, and that all +the secular destinies of our race, from generation to generation, are +but evolutions of a law statuted and sustained in action by an all-wise +Deity. + +There may be a faith derived from this view of Nature sufficient to +sustain us under all sense of the imperfect happiness, the calamities, +the woes and pains of this sphere of being. For let us but fully and +truly consider what a system is here laid open to view and we cannot +well doubt that we are in the hands of One who is both able and willing +to do us the most entire justice. Surely, in such a faith we may well +rest at ease, even though life should have been to us but a protracted +malady. Thinking of all the contingencies of this world as to be in time +melted into or lost in some greater system, to which the present is only +subsidiary, let us wait the end with patience and be of good cheer. + + + + +GEORGES CUVIER + +The Surface of the Globe + + Georges Cuvier was born Aug. 24, 1769, at Montbéliard, France. He + had a brilliant academic career at Stuttgart Academy, and in 1795, + at the age of twenty-six, he was appointed assistant professor of + comparative anatomy at the Museum d'Histoire Naturelle in Paris, + and was elected a member of the National Institute. From this date + onwards to his death in 1832, his scientific industry was + remarkable. Both as zoologist and palæontologist he must be + regarded as one of the greatest pioneers of science. He filled many + important scientific posts, including the chair of Natural History + in the Collège de France, and a professorship at the Jardin des + Plantes. In 1808 he was made member of the Council of the Imperial + University; and in 1814, President of the Council of Public + Instruction. In 1826 he was made grand officer of the Legion of + Honour, and five years later was made a peer of France. The + "Discours sur les Révolutions de la Surface du Globe," published in + 1825, is essentially a preliminary discourse to the author's + celebrated work, "Recherches sur les Ossemens fossiles de + Quadrupèdes." It is an endeavour to trace the relationship between + the changes which have taken place on the surface of the globe and + the changes which have taken place in its animal inhabitants, with + especial reference to the evidence afforded by fossil remains of + quadrupeds. "It is apparent," Cuvier writes, "that the bones of + quadrupeds conduct us, by various reasonings, to more precise + results than any other relics of organised bodies." The two books + together may be considered the first really scientific + palæontology. + + +_I.--Effects of Geological Change_ + +My first object will be to show how the fossil remains of the +terrestrial animals are connected with the theory of the earth. I shall +afterwards explain the principles by which fossil bones may be +identified. I shall give a rapid sketch of new species discovered by the +application of these principles. I shall then show how far these +varieties may extend, owing to the influence of the climate and +domestication. I shall then conceive myself justified in concluding that +the more considerable differences which I have discovered are the +results of very important catastrophes. Afterwards I shall explain the +peculiar influence which my researches should exercise on the received +opinions concerning the revolutions of the globe. Finally, I shall +examine how far the civil and religious history of nations accords with +the results of observation on the physical history of the earth. + +When we traverse those fertile plains, where tranquil waters cherish, as +they flow, an abundant vegetation, and where the soil, trod by a +numerous people, adorned with flourishing villages, rich cities, and +superb monuments, is never disturbed save by the ravages of war, or the +oppression of power, we can hardly believe that Nature has also had her +internal commotions. But our opinions change when we dig into this +apparently peaceful soil, or ascend its neighboring hills. The lowest +and most level soils are composed of horizontal strata, and all contain +marine productions to an innumerable extent. The hills to a very +considerable height are composed of similar strata and similar +productions. The shells are sometimes so numerous as to form the entire +mass of the soil, and all quarters of the globe exhibit the same +phenomenon. + +The time is past when ignorance could maintain that these remains of +organised bodies resulted from the caprice of Nature, and were +productions formed in the bosom of the earth by its generative powers; +for a scrupulous comparison of the remains shows not the slightest +difference between the fossil shells and those that are now found in the +ocean. It is clear, then, that they inhabited the sea, and that they +were deposited by the sea in the places where they are now found; and it +follows, too, that the sea rested in these places long enough to form +regular, dense, vast deposits of aquatic animals. + +The bed of the sea, accordingly, must have undergone some change either +in extent or situation. + +Further, we find under the horizontal strata, _inclined_ strata. Thus +the sea, previously to the formation of the horizontal strata, must have +formed others, which have been broken, inclined, and overturned by some +unknown causes. + +More than this, we find that the fossils vary with the depth of the +strata, and that the fossils of the deeper and more ancient strata +exhibit a formation proper to themselves; and we find in some of the +strata, too, remains of terrestrial life. + +The evidence is thus plain that the animal life in the sea has varied, +and that parts of the earth's surface have been alternately dry land and +ocean. The very soil, which terrestrial animals at present inhabit has a +history of previous animal life, and then submersion under the sea. + +The reiterated irruptions and retreats of the sea have not all been +gradual, but, on the contrary, they have been produced by sudden +catastrophes. The last catastrophe, which inundated and again left dry +our present continents, left in the northern countries the carcasses of +large quadrupeds, which were frozen, and which are preserved even to the +present day, with their skin, hair and flesh. Had they not been frozen +the moment they were killed, they must have putrefied; and, on the other +hand, the intense frost could not have been the ordinary climatic +condition, for they could not have existed at such low temperatures. In +the same instant, then, in which these animals perished the climate +which they inhabited must have undergone a complete revolution. + +The ruptures, the inclinations, the overturnings of the more ancient +strata, likewise point to sudden and violent changes. + +Animal life, then, has been frequently disturbed on this earth by +terrific catastrophes. Living beings innumerable have perished. The +inhabitants of the dry land have been engulfed by deluges; and the +tenants of the water, deserted by their element, have been left to +perish from drought. + +Even ancient rocks formed or deposited before the appearance of life on +the earth show signs of terrific violence. + +It has been maintained by some that the causes now at work altering the +face of the world are sufficient to account for all the changes through +which it has passed: but that is not so. None of the agents Nature now +employs--rain, thaw, rivers, seas, volcanoes--would have been adequate +to produce her ancient works. + +To explain the external crust of the world, we require causes other than +those present in operation, and a thousand extraordinary theories have +been advanced. Thus, according to one philosopher, the earth has +received in the beginning a uniform light crust which caused the abysses +of the ocean, and was broken to produce the Deluge. Another supposed the +Deluge to be caused by the momentary suspension of the cohesion of +minerals. + +Even accomplished scientists and philosophers have advanced impossible +and contradictory theories. + +All attempts at explanation have been stultified by an ignorance of the +facts to be explained, or by a partial survey of them, and especially by +a neglect of the evidence afforded by fossils. How was it possible not +to perceive that the theory of the earth owes its origin to fossils +alone? They alone, in truth, inform us with any certainty that the earth +has not always had the same covering, since they certainly must have +lived upon its surface before they were buried in its depths. If there +were only strata without fossils, one might maintain that the strata had +all been formed together. Hitherto, in fact, philosophers have been at +variance on every point save one, and that is that the sea has changed +its bed; and how could this have been known except for fossils? + +From this consideration I was led to study fossils; and since the field +was immense I was obliged to specialise in one department of fossils, +and selected for study the fossil bones of quadrupeds. I made this +selection because only from a study of fossil quadrupeds can one hope to +ascertain the number and periods and contents of irruptions of the sea; +and because, since the number of quadrupeds is limited, and most +quadrupeds known, we have better means of assuring ourselves if the +fossil remains are remains of extinct or extant animals. Animals such as +the griffin, the cartazonon, the unicorn, never lived, and there are +probably very few quadrupeds now living which have not been found by +man. + +But though the study of fossil quadruped be enlightening, it has its own +special difficulties. One great difficulty arises from the fact that it +is very rare to find a fossil skeleton approaching to a complete state. + +Fortunately, however, there is a principle in comparative anatomy which +lessens this difficulty. Every organised being constitutes a complete +and compact system with all its parts in mutual correspondence. None of +its parts can be changed without changing other parts, and consequently +each part, taken separately, indicates the others. + +Thus, if the intestines of an animal are made to digest raw flesh, its +jaws must be likewise constructed to devour prey, its claws to seize and +tear it, its teeth to rend it, its limbs to overtake it, its organs of +sense to discern it afar. Again, in order to enable the jaw to seize +with facility, a certain form of condyle is necessary, and the zygomatic +arch must be well developed to give attachment to the masseter muscle. +Again, the muscles of the neck must be powerful, whence results a +special form in the vertebræ and the occiput, where the muscles are +attached. Yet again, in order that the claws may be effective, the +toe-bones must have a certain form, and must have muscles and tendons +distributed in a certain way. In a word, the form of the tooth +necessitates the form of the condyle, of the shoulder-blade, and of the +claws, of the femur, and of all the other bones, and all the other bones +taken separately will give the tooth. In this manner anyone who is +scientifically acquainted with the laws of organic economy may from a +fragment reconstruct the whole animal. The mark of a cloven hoof is +sufficient to tell the form of the teeth and jaws and vertebræ and +leg-bones and thigh-bones and pelvis of the animal. The least fragment +of bone, the smallest apophysis, has a determinative character in +relation to the class, the order, the genus, and species to which it may +belong. This is so true that, if we have only a single extremity of bone +well preserved, we may, with application and a skilful use of analogy +and exact comparison, determine all those points with as much certainty +as if we were in possession of the entire animal. By the application of +these principles we have identified and classified the fossil remains of +more than one hundred and fifty mammalia. + + +_II.--What the Fossils Teach_ + +An examination of the fossils on the lines I have indicated shows that +out of one hundred and fifty mammiferous and oviparous quadrupeds, +ninety are unknown to present naturalists, and that in the older layers +such oviparous quadrupeds as the ichthyosauri and plesiosauri abound. +The fossil elephant, the rhinoceros, the hippopotamus, and the mastodons +are not found in the more ancient layers. In fact, the species which +appear the same as ours are found only in superficial deposits. + +Now, it cannot be held that the present races of animals differ from +the ancient races merely by modifications produced by local +circumstances and change of climate--for if species gradually changed, +we must find traces of these gradual modifications, and between the +palæotheria and the present species we should have discovered some +intermediate formation; but to the present time none of these have +appeared. + +Why have not the bowels of the earth preserved the monuments of so +remarkable a genealogy unless it be that the species of former ages were +as constant as our own, or at least because the catastrophe that +destroyed them had not left them time to give evidence of the changes? + +Further, an examination of animals shows that though their superficial +characteristics, such as colour and size, are changeable, yet their more +radical characteristics do not change. Even the artificial breeding of +domestic animals can produce only a limited degree of variation. The +maximum variation known at the present time in the animal kingdom is +seen in dogs, but in all the varieties the relations of the bones remain +the same and the shape of the teeth undergoes no palpable change. + +I know that some naturalists rely much on the thousands of ages which +they can accumulate with a stroke of the pen; but there is nothing which +proves that time will effect any more than climate and a state of +domestication. I have endeavoured to collect the most ancient documents +of the forms of animals. I have examined the engravings of animals +including birds on the numerous columns brought from Egypt to Rome. M. +Saint Hilaire collected all the mummies of animals he could obtain in +Egypt--cats, ibises, birds of prey, dogs, monkeys, crocodiles, etc.--and +we cannot find any more difference between them and those of the present +day than between human mummies of that date and skeletons of the present +day. + +There is nothing, then, in known facts which can support the opinion +that the new genera discovered among fossils--the palæotheria, +anoplotheria, megalonyces, mastodontes, pterodactyli, ichthyosauri, +etc.--could have been the sources of any animals now existing, which +would differ only by the influence of time or climate. + +As yet no human bones have been discovered in the regular layers of the +surface of the earth, so that man probably did not exist in the +countries where fossil bones are found at the epoch of the revolutions +which buried these bones, for there cannot be assigned any reason why +mankind should have escaped such overwhelming catastrophes, or why human +remains should not be discovered. Man _may_ have inhabited some confined +tract of country which escaped the catastrophe, but his establishment in +the countries where the fossil remains of land animals are found--that +is to say, in the greatest part of Europe, Asia, and America--is +necessarily posterior not only to the revolutions which covered these +bones, but even to those which have laid open the strata which envelop +them; whence it is clear that we can draw neither from the bones +themselves nor from the rocks which cover them any argument in favour of +the antiquity of the human species in these different countries. On the +contrary, in closely examining what has taken place on the surface of +the globe, since it was left dry for the last time, we clearly see that +the last revolution, and consequently the establishment of present +society, cannot be very ancient. An examination of the amount of +alluvial matter deposited by rivers, of the progress of downs, and of +other changes on the surface of the earth, informs us clearly that the +present state of things did not commence at a very remote period. + +The history of nations confirms the testimony of the fossils and of the +rocks. The chronology of none of the nations of the West can be traced +unbroken farther back than 3,000 years. The Pentateuch, the most ancient +document the world possesses, and all subsequent writings allude to a +universal deluge, and the Pentateuch and Vedas and Chou-king date this +catastrophe as not more than 5,400 years before our time. Is it possible +that mere chance gave a result so striking as to make the traditional +origin of the Assyrian, Indian, and Chinese monarchies agree in being as +remote as 4,000 or 5,000 years back? Would the ideas of nations with so +little inter-communication, whose language, religion, and laws have +nothing in common, agree on this point if they were not founded on +truth? Even the American Indians have their Noah or Deucalion, like the +Indians, Babylonians, and Greeks. + +It may be said that the long existence of ancient nations is attested by +their progress in astronomy. But this progress has been much +exaggerated. But what would this astronomy prove even if it were more +perfect? Have we calculated the progress which a science would make in +the bosom of nations which had no other? If among the multitude of +persons solely occupied with astronomy, even then, all that these people +knew might have been discovered in a few centuries, when only 300 years +intervened between Copernicus and Laplace. + +Again, it has been pretended that the zodiacal figures on ancient +temples give proof of a remote antiquity; but the question is very +complicated, and there are as many opinions as writers, and certainly no +conclusions against the newness of continents and nations can be based +on such evidence. The zodiac itself has been considered a proof of +antiquity, but the arguments brought forward are undoubtedly unsound. + +Even if these various astronomical proofs were as certain as they are +unconvincing, what conclusion could we draw against the great +catastrophe so indisputably demonstrated? We should only have the right +to conclude that astronomy was among the sciences preserved by those +persons whom the catastrophe spared. + +In conclusion, if there be anything determined in geology, it is that +the surface of our globe has been subjected to a revolution within 5,000 +years, and that this revolution buried the countries formerly inhabited +by man and modern animals, and left the bottom of the former sea dry as +a habitation for the few individuals it spared. Consequently, our +present human societies have arisen since this catastrophe. + +But the countries now inhabited had been inhabited before, as fossils +show, by animals, if not by mankind, and had been overwhelmed by a +previous deluge; and, indeed, judging by the different orders of animal +fossils we find, they had perhaps undergone two or three irruptions of +the sea. + + + + +CHARLES DARWIN + +The Origin of Species + + Charles Robert Darwin was born at Shrewsbury, England, Feb. 12, + 1809, of a family distinguished on both sides. Abandoning medicine + for natural history, he joined H.M.S. Beagle in 1831 on the five + years' voyage, which he described in "The Voyage of the Beagle," + and to which he refers in the introduction to his masterpiece. The + "Origin of Species" containing, in the idea of natural selection, + the distinctive contribution of Darwin to the theory of organic + evolution, was published in November, 1859. In only one brief + sentence did he there allude to man, but twelve years later he + published the "Descent of Man," in which the principles of the + earlier volume found their logical outcome. In other works Darwin + added vastly to our knowledge of coral reefs, organic variation, + earthworms, and the comparative expression of the emotions in man + and animals. Darwin died in ignorance of the work upon variation + done by his great contemporary, Gregor Mendel, whose work was + rediscovered in 1900. "Mendelism" necessitates much modification of + Darwin's work, which, however, remains the maker of the greatest + epoch in the study of life and the most important contribution to + that study ever made. Its immortal author died on April 19, 1882, + and was buried in Westminster Abbey. + + +_I.--Creation or Evolution?_ + +When on board H.M.S. Beagle as naturalist, I was much struck with +certain facts in the distribution of the organic beings inhabiting South +America, and in the geographical relations of the present to the past +inhabitants of that continent. These facts, as will be seen in the +latter chapters of this volume, seemed to throw some light on the origin +of species--that mystery of mysteries, as it has been called by one of +our greatest philosophers. On my return home, in 1837, it occurred to me +that something might perhaps be made out on this question by patiently +accumulating and reflecting on all sorts of facts which could possibly +have any bearing on it. After five years' work, I allowed myself to +speculate on the subject, and drew up some short notes; these I enlarged +in 1844 into a sketch of the conclusions which then seemed to me +probable. From that period to the present day I have steadily pursued +the same object. I hope that I may be excused for entering on these +personal details, as I give them to show that I have not been hasty in +coming to a decision. + +In considering the origin of species, it is quite conceivable that a +naturalist, reflecting on the mutual affinities of organic beings, on +their embryological relations, their geographical distribution, +geological succession, and other such facts, might come to the +conclusion that species had not been independently created, but had +descended, like varieties, from other species. Nevertheless, such a +conclusion, even if well founded, would be unsatisfactory, until it +could be shown how the innumerable species inhabiting this world have +been modified so as to acquire that perfection of structure and +co-adaptation which justly excites our admiration. + +Naturalists continually refer to external conditions, such as climate, +food, etc., as the only possible cause of variation. In one limited +sense, as we shall hereafter see, this may be true; but it is +preposterous to attribute to mere external conditions the structure, for +instance, of the woodpecker, with its feet, tail, beak, and tongue, so +admirably adapted to catch insects under the bark of trees. In the case +of the mistletoe, which draws its nourishment from certain trees, which +has seeds that must be transported by certain birds, and which has +flowers with separate sexes absolutely requiring the agency of certain +insects to bring pollen from one flower to the other, it is equally +preposterous to account for the structure of the parasite, with its +relations to several distinct organic beings, by the effects of external +conditions, or of habit, or of the volition of the plant itself. + +It is, therefore, of the highest importance to gain a clear insight into +the means of modification and co-adaptation. At the beginning of my +observations it seemed to me probable that a careful study of +domesticated animals and of cultivated plants would offer the best +chance of making out this obscure problem. Nor have I been disappointed; +in this and in all other perplexing cases I have invariably found that +our knowledge, imperfect though it be, of variation under domestication, +afforded the best and safest clue. I may venture to express my +conviction of the high value of such studies, although they have been +very commonly neglected by naturalists. + +Although much remains obscure, and will long remain obscure, I can +entertain no doubt, after the most deliberate study and dispassionate +judgment of which I am capable, that the view which most naturalists +until recently entertained, and which I formerly entertained--namely, +that each species has been independently created--is erroneous. I am +fully convinced that species are not immutable, but that those belonging +to what are called the same genera are lineal descendants of some other +and generally extinct species, in the same manner as the acknowledged +varieties of any one species are the descendants of that species. +Furthermore, I am also convinced that Natural Selection has been the +most important, but not the exclusive, means of modification. + + +_II.--Variation and Selection_ + +All living beings vary more or less from one another, and though +variations which are not inherited are unimportant for us, the number +and diversity of inheritable deviations of structure, both those of +slight and those of considerable physiological importance, are endless. + +No breeder doubts how strong is the tendency to inheritance; that like +produces like is his fundamental belief. Doubts have been thrown on +this principle only by theoretical writers. When any deviation of +structure often appears, and we see it in the father and child, we +cannot tell whether it may not be due to the same cause having acted on +both; but when amongst individuals, apparently exposed to the same +conditions, any very rare deviation, due to some extraordinary +combination of circumstances, appears in the parent--say, once amongst +several million individuals--and it re-appears in the child, the mere +doctrine of chances almost compels us to attribute its reappearance to +inheritance. + +Everyone must have heard of cases of albinism, prickly skin, hairy +bodies, etc., appearing in members of the same family. If strange and +rare deviations of structure are really inherited, less strange and +commoner deviations may be freely admitted to be inheritable. Perhaps +the correct way of viewing the whole subject would be to look at the +inheritance of every character whatever as the rule, and non-inheritance +as the anomaly. + +The laws governing inheritance are for the most part unknown. No one can +say why the same peculiarity in different individuals of the same +species, or in different species, is sometimes inherited and sometimes +not so; why the child often reverts in certain characters to its +grandfather or grandmother, or more remote ancestor; why a peculiarity +is often transmitted from one sex to both sexes, or to one sex alone, +more commonly but not exclusively to the like sex. + +The fact of heredity being given, we have evidence derived from human +practice as to the influence of selection. There are large numbers of +domesticated races of animals and plants admirably suited in various +ways to man's use or fancy--adapted to the environment of which his need +and inclination are the most essential constituents. We cannot suppose +that all the breeds were suddenly produced as perfect and as useful as +we now see them; indeed, in many cases, we know that this has not been +their history. The key is man's power of accumulative selection. Nature +gives successive variations; man adds them up in certain directions +useful to him. In this sense he may be said to have made for himself +useful breeds. + +The great power of this principle of selection is not hypothetical. It +is certain that several of our eminent breeders have, even within a +single lifetime, modified to a large extent their breeds of cattle and +sheep. What English breeders have actually effected is proved by the +enormous prices given for animals with a good pedigree; and these have +been exported to almost every quarter of the world. The same principles +are followed by horticulturists, and we see an astonishing improvement +in many florists' flowers, when the flowers of the present day are +compared with drawings made only twenty or thirty years ago. + +The practice of selection is far from being a modern discovery. The +principle of selection I find distinctly given in an ancient Chinese +encyclopædia. Explicit rules are laid down by some of the Roman +classical writers. It is clear that the breeding of domestic animals was +carefully attended to in ancient times, and is now attended to by the +lowest savages. It would, indeed, have been a strange fact had attention +not been paid to breeding, for the inheritance of good and bad qualities +is so obvious. + +Study of the origin of our domestic races of animals and plants leads to +the following conclusions. Changed conditions of life are of the highest +possible importance in causing variability, both by acting directly on +the organisation, and indirectly by affecting the reproductive system. +Spontaneous variation of unknown origin plays its part. Some, perhaps a +great, effect may be attributed to the increased use or disuse of parts. + +The final result is thus rendered infinitely complex. In some cases the +intercrossing of aboriginally distinct species appears to have played +an important part in the origin of our breeds. When several breeds have +once been formed in any country, their occasional intercrossing, with +the aid of selection, has, no doubt, largely aided in the formation of +new sub-breeds; but the importance of crossing has been much +exaggerated, both in regard to animals and to those plants which are +propagated by seed. Over all these causes of change, the accumulative +action of selection, whether applied methodically and quickly, or +unconsciously and slowly, but more efficiently, seems to have been the +predominant power. + + +_III.--Variation Under Nature_ + +Before applying these principles to organic beings in a state of nature, +we must ascertain whether these latter are subject to any variation. We +find variation everywhere. Individual differences, though of small +interest to the systematist, are of the highest importance for us, for +they are often inherited; and they thus afford materials for natural +selection to act and accumulate, in the same manner as man accumulates +in any given direction individual differences in his domesticated +productions. Further, what we call varieties cannot really be +distinguished from species in the long run, a fact which we can clearly +understand if species once existed as varieties, and thus originated. +But the facts are utterly inexplicable if species are independent +creations. + +How have all the exquisite adaptations of one part of the body to +another part, and to the conditions of life, and of one organic being to +another being, been perfected? For everywhere we find these beautiful +adaptations. + +The answer is to be found in the struggle for life. Owing to this +struggle, variations, however slight, and from whatever cause +proceeding, if they be in any degree profitable to the individuals of a +species in their infinitely complex relations to other organic beings +and to their physical conditions of life, will tend to the preservation +of such individuals, and will generally be inherited by the offspring. +The offspring, also, will thus have a better chance of surviving, for, +of the many individuals of any species which are periodically born, but +a small number can survive. I have called this principle, by which each +slight variation, if useful, is preserved, by the term Natural +Selection, in order to mark its relation to man's power of selection. +But the expression, often used by Mr. Herbert Spencer, of the Survival +of the Fittest, is more accurate. + +We have seen that man, by selection, can certainly produce great +results, and can adapt organic beings to his own uses, through the +accumulation of slight but useful variations given to him by the hand of +Nature. Natural Selection is a power incessantly ready for action, and +is as immeasurably superior to man's feeble efforts as the works of +Nature are to those of Art. + +All organic beings are exposed to severe competition. Nothing is easier +than to admit in words the truth of the universal struggle for life, or +more difficult--at least, I have found it so--than constantly to bear +this conclusion in mind. Yet, unless it be thoroughly engrained in the +mind, the whole economy of Nature, with every fact of distribution, +rarity, abundance, extinction, and variation, will be dimly seen or +quite misunderstood. We behold the face of Nature bright with gladness; +we often see superabundance of food. We do not see, or we forget, that +the birds which are idly singing round us mostly live on insects or +seeds, and are thus constantly destroying life; or we forget how largely +these songsters, or their eggs, or their nestlings, are destroyed by +birds or beasts of prey. We do not always bear in mind that, though food +may be superabundant, it is not so at all seasons of each recurring +year. + +A struggle for existence, the term being used in a large, general, and +metaphorical sense, inevitably follows from the high rate at which all +organic beings tend to increase. + +Every being, which during its natural lifetime produces several eggs or +seeds, must suffer destruction during some period of its life, and +during some season or occasional year; otherwise, on the principle of +geometrical increase, its numbers would quickly become so inordinately +great that no country could support the product. Hence, as more +individuals are produced than can possibly survive, there must in every +case be a struggle for existence, either one individual with another of +the same species, or with the individuals of distinct species, or with +the physical conditions of life. It is the doctrine of Malthus applied +with manifold force to the whole animal and vegetable kingdoms; for in +this case there can be no artificial increase of food, and no prudential +restraint from marriage. Although some species may be now increasing, +more or less rapidly, in numbers, all cannot do so, for the world would +not hold them. + +There is no exception to the rule that every organic being naturally +increases at so high a rate that, if not destroyed, the earth would soon +be covered by the progeny of a single pair. Even slow-breeding man has +doubled in twenty-five years, and at this rate, in less than a thousand +years, there would literally not be standing-room for his progeny. +Linnæus has calculated that if an annual plant produced only two +seeds--and there is no plant so unproductive as this--and their +seedlings next year produced two, and so on, then in twenty years there +would be a million plants. The elephant is reckoned the slowest breeder +of all known animals, and I have taken some pains to estimate its +probable minimum rate of natural increase. It will be safest to assume +that it begins breeding when thirty years old, and goes on breeding +until ninety years old, bringing forth six young in the interval, and +surviving till one hundred years old. If this be so, after a period of +from 740 to 750 years there would be nearly nineteen million elephants +alive, descended from the first pair. + +The causes which check the natural tendency of each species to increase +are most obscure. Eggs or very young animals seem generally to suffer +most, but this is not invariably the case. With plants there is a vast +destruction of seeds. The amount of food for each species of course +gives the extreme limit to which each can increase; but very frequently +it is not the obtaining food, but the serving as prey to other animals, +which determines the average number of a species. Climate is important, +and periodical seasons of extreme cold or drought seem to be the most +effective of all checks. + +The relations of all animals and plants to each other in the struggle +for existence are most complex, and often unexpected. Battle within +battle must be continually recurring with varying success; and yet in +the long run the forces are so nicely balanced that the face of Nature +remains for long periods of time uniform, though assuredly the merest +trifle would give the victory to one organic being over another. +Nevertheless, so profound is our ignorance, and so high our presumption, +that we marvel when we hear of the extinction of an organic being; and +as we do not see the cause, we invoke cataclysms to desolate the world, +or invent laws on the duration of the forms of life! + +The struggle for life is most severe between individuals and varieties +of the same species. The competition is most severe between allied forms +which fill nearly the same place in the economy of Nature. But great is +our ignorance on the mutual relations of all organic beings. All that we +can do is to keep steadily in mind that each organic being is striving +to increase in a geometrical ratio; that each at some period of its +life, during some season of the year, during each generation or at +intervals, has to struggle for life and to suffer great destruction. +When we reflect on this struggle, we may console ourselves with the full +belief that the war of Nature is not incessant, that no fear is felt, +that death is generally prompt, and that the vigorous, the healthy, and +the happy survive and multiply. + + +_IV.--The Survival of the Fittest_ + +How will the struggle for existence act in regard to variation? Can the +principle of selection, which we have seen is so potent in the hands of +man, apply under Nature? I think we shall see that it can act most +efficiently. Let the endless number of slight variations and individual +differences occurring in our domestic productions, and, in a lesser +degree, in those under Nature, be borne in mind, as well as the strength +of the hereditary tendency. Under domestication, it may be truly said +that the whole organisation becomes in some degree plastic. + +But the variability, which we almost universally meet with in our +domestic productions, is not directly produced by man; he can neither +originate variations nor prevent their occurrence; he can only preserve +and accumulate such as do occur. Unintentionally he exposes organic +beings to new and changing conditions of life, and variability ensues; +but similar changes of condition might and do occur under Nature. + +Let it also be borne in mind how infinitely complex and close-fitting +are the mutual relations of all organic beings to each other and to +their physical conditions of life, and consequently what infinitely +varied diversities of structure might be of use to each being under +changing conditions of life. Can it, then, be thought improbable, seeing +what variations useful to man have undoubtedly occurred, that other +variations, useful in some way to each being in the great complex battle +of life, should occur in the course of many successive generations? If +such do occur, can we doubt, remembering that many more individuals are +born than can possibly survive, that individuals having any advantage +over others, would have the best chance of surviving and of procreating +their kind? On the other hand, we may feel sure that any variation in +the least degree injurious would be rigidly destroyed. This preservation +of favourable individual differences and variations, and the destruction +of those which are injurious, I have called Natural Selection, or the +Survival of the Fittest. + +The term is too frequently misapprehended. Variations neither useful nor +injurious would not be affected by natural selection. It is not asserted +that natural selection induces variability. It implies only the +preservation of such varieties as arise and are beneficial to the being +under its conditions of life. Again, it has been said that I speak of +natural selection as an active Power or Deity; but who objects to an +author speaking of the attraction of gravity as ruling the movements of +the planets? It is difficult to avoid personifying the word Nature; but +I mean by Nature only the aggregate action and product of many natural +laws, and by laws the sequence of events as ascertained by us. + +As man can produce, and certainly has produced, a great result by his +methodical and unconscious means of selection, what may not natural +selection effect? Man can act only on external and visible characters; +Nature, if I may be allowed to personify the natural preservation or +survival of the fittest, cares nothing for appearances, except in so far +as they are useful to any being. She can act on every internal organ, on +every shade of constitutional difference, on the whole machinery of +life. Man selects only for his own good; Nature only for that of the +being which she tends. Every selected character is fully exercised by +her, as is implied by the fact of their selection. Man keeps the natives +of many climates in the same country; he seldom exercises each selected +character in some peculiar and fitting manner; he feeds a long and a +short-beaked pigeon on the same food; he does not exercise a long-backed +or long-legged quadruped in any peculiar manner; he exposes sheep with +long and short wool to the same climate. + +Man does not allow the most vigorous males to struggle for the females. +He does not rigidly destroy all inferior animals, but protects during +each varying season, as far as lies in his power, all his productions. +He often begins his selection by some half-monstrous form; or at least +by some modification prominent enough to catch the eye or to be plainly +useful to him. + +But under Nature, the slightest differences of structure or constitution +may well turn the nicely-balanced scale in the struggle for life, and so +be preserved. How fleeting are the wishes and efforts of man! How short +his time! And, consequently, how poor will be his results compared with +those accumulated by Nature during whole geological periods! Can we +wonder that Nature's productions should be far "truer" in character than +man's productions; that they should be infinitely better adapted to the +most complex conditions of life, and should plainly bear the stamp of +far higher workmanship? + +It may metaphorically be said that natural selection is daily and hourly +scrutinising, throughout the world, the slightest variations; rejecting +those that are bad, preserving and adding up all that are good; silently +and insensibly working, whenever and wherever opportunity offers, at the +improvement of each organic being in relation to its organic and +inorganic conditions of life. We see nothing of these slow changes in +progress until the hand of time has marked the lapse of ages, and then +so imperfect is our view into long-past geological ages that we see only +that the forms of life are now different from what they formerly were. + +Although natural selection can act only through and for the good of +each being, yet characters and structures, which we are apt to consider +as of very trifling importance, may thus be acted on. + +Natural selection will modify the structure of the young in relation to +the parent, and of the parent in relation to the young. In social +animals it will adapt the structure of each individual for the benefit +of the whole community, if the community profits by the selected change. +What natural selection cannot do is to modify the structure of one +species, without giving it any advantage, for the good of another +species; and though statements to this effect may be found in works of +natural history, I cannot find one case which will bear investigation. + +A structure used only once in an animal's life, if of high importance to +it, might be modified to any extent by natural selection; for instance, +the great jaws possessed by certain insects, used exclusively for +opening the cocoon, or the hard tip to the beak of unhatched birds, used +for breaking the egg. It has been asserted that of the best short-beaked +tumbler pigeons a greater number perish in the egg than are able to get +out of it; so that fanciers assist in the act of hatching. Now, if +Nature had to make the beak of a full-grown pigeon very short for the +bird's own advantage, the process of modification would be very slow, +and there would be simultaneously the most rigorous selection of all the +young birds within the egg, for all with weak beaks would inevitably +perish; or more easily broken shells might be selected, the thickness of +the shell being known to vary like every other structure. + +With all beings there must be much fortuitous destruction, which can +have little or no influence on the course of natural selection. For +instance, a vast number of eggs or seeds are annually devoured, and +these could be modified through natural selection only if they varied +in some manner which protected them from their enemies. Yet many of +these eggs or seeds would perhaps, if not destroyed, have yielded +individuals better adapted to their conditions of life than any of those +which happened to survive. So, again, a vast number of mature animals +and plants, whether or not they be the best adapted to their conditions, +must be annually destroyed by accidental causes, which would not be in +the least degree mitigated by certain changes of structure or +constitution which would in other ways be beneficial to the species. + +But let the destruction of the adults be ever so heavy, if the number +which can exist in any district be not wholly kept down by such +causes--or, again, let the destruction of eggs or seeds be so great that +only a hundredth or a thousandth part are developed--yet of those which +do survive, the best adapted individuals, supposing there is any +variability in a favourable direction, will tend to propagate their kind +in larger numbers than the less well adapted. + +On our theory the continued existence of lowly organisms offers no +difficulty; for natural selection does not necessarily include +progressive development; it only takes advantage of such variations as +arise and are beneficial to each creature under its complex relations of +life. + +The mere lapse of time by itself does nothing, either for or against +natural selection. I state this because it has been erroneously asserted +that the element of time has been assumed by me to play an all-important +part in modifying species, as if all the forms of life were necessarily +undergoing change through some innate law. + + +_V.--Sexual Selection_ + +This form of selection depends, not on a struggle for existence in +relation to other organic beings or to external conditions, but on a +struggle between the individuals of one sex, generally the males, for +the possession of the other sex. The result is not death to the +unsuccessful competitor, but few or no offspring. Sexual selection is, +therefore, less rigorous than natural selection. Generally, the most +vigorous males, those which are best fitted for their places in Nature, +will leave most progeny. But, in many cases, victory depends not so much +on general vigour as on having special weapons, confined to the male +sex. A hornless stag or spurless cock would have a poor chance of +leaving numerous offspring. Sexual selection, by always allowing the +victor to breed, might surely give indomitable courage, length to the +spur, and strength to the wing to strike in the spurred leg, in nearly +the same manner as does the brutal cock-fighter by the careful selection +of his best cocks. + +How low in the scale of Nature the law of battle descends I know not. +Male alligators have been described as fighting, bellowing, and whirling +round, like Indians in a war-dance, for the possession of the females; +male salmons have been observed fighting all day long; male stag-beetles +sometimes bear wounds from the mandibles of other males; the males of +certain other insects have been frequently seen fighting for a +particular female who sits by, an apparently unconcerned beholder of the +struggle, and then retires with the conqueror. The war is, perhaps, +severest between the males of the polygamous animals, and these seem +oftenest provided with special weapons. The males of carnivorous animals +are already well armed, though to them special means of defence may be +given through means of sexual selection, as the mane of the lion and the +hooked jaw of the salmon. The shield may be as important for victory as +the sword or spear. + +Amongst birds, the contest is often of a more peaceful character. All +those who have attended to the subject believe that there is the +severest rivalry between the males of many species to attract, by +singing, the females. The rock-thrush of Guiana, birds of paradise, and +some others, congregate; and successive males display with the most +elaborate care, and show off in the best manner, their gorgeous plumage; +they likewise perform strange antics before the females, which, standing +by as spectators, at last choose the most attractive partner. + +If man can in a short time give beauty and an elegant carriage to his +bantams, according to his standard of beauty, I can see no good reason +to doubt that female birds, by selecting, during thousands of +generations, the most melodious or beautiful males, according to their +standard of beauty, might produce a marked effect. + + +_VI.--The Struggle for Existence_ + +Under domestication we see much variability, caused, or at least +excited, by changed conditions of life; but often in so obscure a manner +that we are tempted to consider the variations as spontaneous. +Variability is governed by many complex laws--by correlated growth, +compensation, the increased use and disuse of parts, and the definite +action of the surrounding conditions. There is much difficulty in +ascertaining how largely our domestic productions have been modified; +but we may safely infer that the amount has been large, and that +modifications can be inherited for long periods. As long as the +conditions of life remain the same, we have reason to believe that a +modification, which has already been inherited for many generations, may +continue to be inherited for an almost infinite number of generations. +On the other hand, we have evidence that variability, when it has once +come into play, does not cease under domestication for a very long +period; nor do we know that it ever ceases, for new varieties are still +occasionally produced by our oldest domesticated productions. + +Variability is not actually caused by man; he only unintentionally +exposes organic beings to new conditions of life, and then Nature acts +on the organisation and causes it to vary. But man can and does select +the variations given to him by Nature, and thus accumulates them in any +desired manner. He thus adapts animals and plants for his own benefit or +pleasure. He may do this methodically, or he may do it unconsciously by +preserving the individuals most useful or pleasing to him without an +intention of altering the breed. + +It is certain that he can influence the character of a breed by +selecting, in each successive generation, individual differences so +slight as to be inappreciable except by an educated eye. This +unconscious process of selection has been the agency in the formation of +the most distinct and useful domestic breeds. That many breeds produced +by man have to a large extent the character of natural species is shown +by the inextricable doubts whether many of them are varieties or +aboriginally distinct species. + +There is no reason why the principles which have acted so efficiently +under domestication should not have acted under Nature. In the survival +of favoured individuals and races, during the constantly recurrent +struggle for existence, we see a powerful and ever-acting form of +selection. The struggle for existence inevitably follows from the high +geometrical ratio of increase which is common to all organic beings. +This high rate of increase is proved by calculation; by the rapid +increase of many animals and plants during a succession of peculiar +seasons and when naturalised in new countries. More individuals are born +than can possibly survive. A grain in the balance may determine which +individuals shall live and which shall die; which variety or species +shall increase in number, and which shall decrease, or finally become +extinct. + +As the individuals of the same species come in all respects into the +closest competition with each other, the struggle will generally be +most severe between them; it will be almost equally severe between the +varieties of the same species, and next in severity between the species +of the same genus. On the other hand, the struggle will often be severe +between beings remote in the scale of Nature. The slightest advantage in +certain individuals, at any age or during any season, over those with +which they come into competition, or better adaptation, in however +slight a degree, to the surrounding physical conditions, will, in the +long run, turn the balance. + +With animals having separated sexes, there will be in most cases a +struggle between the males for the possession of the females. The most +vigorous males, or those which have most successfully struggled with +their conditions of life, will generally leave most progeny. But success +will often depend on the males having special weapons, or means of +defence, or charms; and a slight advantage will lead to victory. + +As geology plainly proclaims that each land has undergone great physical +changes, we might have expected to find that organic beings have varied +under Nature in the same way as they have varied under domestication. +And if there has been any variability under Nature, it would be an +unaccountable fact if natural selection had not come into play. It has +often been asserted, but the assertion is incapable of proof, that the +amount of variation under Nature is a strictly limited quantity. Man, +though acting on external characters alone, and often capriciously, can +produce within a short period a great result by adding up mere +individual differences in his domestic productions; and everyone admits +that species present individual differences. But, besides such +differences, all naturalists admit that natural varieties exist, which +are considered sufficiently distinct to be worthy of record in +systematic works. + +No one has drawn any clear distinction between individual differences +and slight varieties, or between more plainly marked varieties and +sub-species and species. On separate continents, and on different parts +of the same continent when divided by barriers of any kind, what a +multitude of forms exist which some experienced naturalists rank as +varieties, others as geographical races or sub-species, and others as +distinct, though closely allied species! + +If, then, animals and plants do vary, let it be ever so slightly or +slowly, why should not variations or individuals, differences which are +in any way beneficial, be preserved and accumulated through natural +selection, or the survival of the fittest? If man can, by patience, +select variations useful to him, why, under changing and complex +conditions of life, should not variations useful to Nature's living +products often arise, and be preserved, or selected? What limit can be +put to this power, acting during long ages and rigidly scrutinising the +whole constitution, structure, and habits of each creature--favouring +the good and rejecting the bad? I can see no limit to this power, in +slowly and beautifully adapting each form to the most complex relations +of life. + +In the future I see open fields for far more important researches. +Psychology will be based on the foundation already well laid by Mr. +Herbert Spencer--that of the necessary acquirement of each mental power +and capacity by gradation. Much light will be thrown on the origin of +man and his history. + +Authors of the highest eminence seem to be fully satisfied with the view +that each species has been independently created. To my mind it accords +better with what we know of the laws impressed on matter by the Creator +that the production and extinction of the past and present inhabitants +of the world should have been due to secondary causes, like those +determining the birth and death of the individual. When I view all +beings not as special creations, but as the lineal descendants of some +few beings which lived long before the first bed of the Cambrian system +was deposited, they seem to me to become ennobled. Judging from the +past, we may safely infer that not one living species will transmit its +unaltered likeness to a distant futurity. + +Of the species now living very few will transmit progeny of any kind to +a far distant futurity; for the manner in which all organic beings are +grouped shows that the greater number of species in each genus, and all +the species in many genera, have left no descendants, but have become +utterly extinct. We can so far take a prophetic glance into futurity as +to foretell that it will be the common and widely-spread species, +belonging to the larger and dominant groups within each class, which +will ultimately prevail and procreate new and dominant species. As all +the living forms of life are the lineal descendants of those which lived +long before the Cambrian epoch, we may feel certain that the ordinary +succession by generation has never once been broken, and that no +cataclysm has desolated the whole world. We may look with some +confidence to a secure future of great length. As natural selection +works solely by and for the good of each being, all corporeal and mental +endowments will tend to progress towards perfection. + +It is interesting to contemplate a tangled bank, clothed with many +plants of many kinds, with birds singing on the bushes, with various +insects flitting about, and with worms crawling through the damp earth, +and to reflect that these elaborately constructed forms, so different +from each other, and dependent upon each other in so complex a manner, +have all been produced by laws acting around us. These laws, taken in +the largest sense, being Growth with Reproduction; Inheritance, which is +almost implied by reproduction; Variability from the indirect and direct +action of the conditions of life, and from use and disuse; a ratio of +increase so high as to lead to a struggle for life, and, as a +consequence, to Natural Selection, entailing Divergence of Character +and the Extinction of less improved forms. Thus, from the war of Nature, +from famine and death, the most exalted object which we are capable of +conceiving, namely, the production of the higher animals, directly +follows. There is grandeur in this view of life, with its several +powers, having been originally breathed by the Creator into a few forms, +or into one; and that, whilst this planet has gone cycling on according +to the fixed law of gravity, from so simple a beginning endless forms +most beautiful and most wonderful have been, and are being, evolved. + + + + +SIR HUMPHRY DAVY + +Elements of Chemical Philosophy + + Humphry Davy, the celebrated natural philosopher, was born Dec. 17, + 1778, at Penzance, England. At the age of seventeen he became an + apothecary's apprentice, and at the age of nineteen assistant at + Dr. Beddoes's pneumatic institution at Bristol. During researches + at the pneumatic institution he discovered the physiological + effects of "laughing gas," and made so considerable a reputation as + a chemist that at the age of twenty-two he was appointed lecturer, + and a year later professor, at the Royal Institution. For ten + years, from 1803, he was engaged in agricultural researches, and in + 1813 published his "Elements of Agricultural Chemistry." During the + same decade he conducted important investigations into the nature + of chemical combination, and succeeded in isolating the elements + potassium, sodium, strontium, magnesium, and chlorine. In 1812 he + was knighted, and married Mrs. Apreece, _née_ Jane Kerr. In 1815 he + investigated the nature of fire-damp and invented the Davy safety + lamp. In 1818 he received a baronetcy, and two years later was + elected President of the Royal Society. On May 29, 1829, he died at + Geneva. Davy's "Elements of Chemical Philosophy," of which a + summary is given here, was published in one volume in 1812, being + the substance of lectures delivered before the Board of + Agriculture. + + +_I.--Forms and Changes of Matter_ + +The forms and appearances of the beings and substances of the external +world are almost infinitely various, and they are in a state of +continued alteration. In general, matter is found in four forms, as (1) +solids, (2) fluids, (3) gases, (4) ethereal substances. + +1. _Solids._ Solids retain whatever mechanical form is given to them; +their parts are separated with difficulty, and cannot readily be made to +unite after separation. They may be either elastic or non-elastic, and +differ in hardness, in colour, in opacity, in density, in weight, and, +if crystalline, in crystalline form. + +2. _Fluids._ Fluids, when in small masses, assume the spherical form; +their parts possess freedom of motion; they differ in density and +tenacity, in colour, and in opacity. They are usually regarded as +incompressible; at least, a very great mechanical force is required to +compress them. + +3. _Gases._ Gases exist free in the atmosphere, but may be confined. +Their parts are highly movable; they are compressible and expansible, +and their volumes are inversely as the weight compressing them. All +known gases are transparent, and present only two or three varieties of +colour; they differ materially in density. + +4. _Ethereal Substances._ Ethereal substances are known to us only in +their states of motion when acting upon our organs of sense, or upon +other matter, and are not susceptible of being confined. It cannot be +doubted that there is such matter in motion in space. Ethereal matter +differs either in its nature, or in its affections by motion, for it +produces different effects; for instance, radiant heat, and different +kinds of light. + +All these forms of matter are under the influence of active forces, such +as gravitation, cohesion, heat, chemical and electrical attraction, and +these we must now consider. + +1. _Gravitation._ When a stone is thrown into the atmosphere, it rapidly +descends towards the earth. This is owing to gravitation. All the great +bodies in the universe are urged towards each other by a similar force. +Bodies mutually gravitate towards each other, but the smaller body +proportionately more than the larger one; hence the power of gravity is +said to vary directly as the mass. Gravitation also varies with +distance, and acts inversely as the square of the distance. + +2. _Cohesion._ Cohesion is the force which preserves the forms of +solids, and gives globularity to fluids. It is usually said to act only +at the surface of bodies or by their immediate contact; but this does +not seem to be the case. It certainly acts with much greater energy at +small distances, but the spherical form of minute portions of fluid +matter can be produced only by the attractions of all the parts of which +they are composed, for each other; and most of these attractions must be +exerted at sensible distances, so that gravitation and cohesion may be +mere modifications of the same general power of attraction. + +3. _Heat._ When a body which occasions the sensation of heat on our +organs is brought into contact with another body which has no such +effect, the hot body contracts and loses to a certain extent its power +of communicating heat; and the other body expands. Different solids and +fluids expand very differently when heated, and the expansive power of +liquids, in general, is greater than that of solids. + +It is evident that the density of bodies must be diminished by +expansion; and in the case of fluids and gases, the parts of which are +mobile, many important phenomena depend upon this circumstance. For +instance, if heat be applied to fluids and gases, the heated parts +change their places and rise, and the currents in the ocean and +atmosphere are due principally to this movement. There are very few +exceptions to the law of the expansion of bodies at the time they become +capable of communicating the sensation of heat, and these exceptions +seem to depend upon some chemical change in the constitution of bodies, +or on their crystalline arrangements. + +The power which bodies possess of communicating or receiving heat is +known as _temperature_, and the temparature of a body is said to be high +or low with respect to another in proportion as it occasions an +expansion or contraction of its parts. + +When equal volumes of different bodies of different temperatures are +suffered to remain in contact till they acquire the same temperature, it +is found that this temperature is not a mean one, as it would be in the +case of equal volumes of the same body. Thus if a pint of quicksilver +at 100° be mixed with a pint of water at 50°, the resulting temperature +is not 75°, but 70°; the mercury has lost thirty degrees, whereas the +water has only gained twenty degrees. This difference is said to depend +on the different _capacities_ of bodies for heat. + +Not only do different bodies vary in their capacity for heat, but they +likewise acquire heat with very different degrees of celerity. This last +difference depends on the different power of bodies for _conducting_ +heat, and it will be found that as a rule the densest bodies, with the +least capacity for heat, are the best conductors. + +Heat, or the power of repulsion, may be considered as the _antagonist_ +power to the attraction of cohesion. Thus solids by a certain increase +of temperature become fluids, and fluids gases; and, _vice versâ_, by a +diminution of temperature, gases become fluids, and fluids solids. + +Proofs of the conversion of solids, fluids, or gases into ethereal +substances are not distinct. Heated bodies become luminous and give off +radiant heat, which affects the bodies at a distance, and it may +therefore be held that particles are thrown off from heated bodies with +great velocity, which, by acting on our organs, produce the sensations +of heat or light, and that their motion, communicated to the particles +of other bodies, has the power of expanding them. It may, however, be +said that the radiant matters emitted by bodies in ignition are specific +substances, and that common matter is not susceptible of assuming this +form; or it may be contended that the phenomena of radiation do in fact, +depend upon motions communicated to subtile matter everywhere existing +in space. + +The temperatures at which bodies change their states from fluids to +solids, though in general definite, are influenced by a few +circumstances such as motion and pressure. + +When solids are converted into fluids, or fluids into gases, there is +always a loss of heat of temperature; and, _vice versâ_, when gases are +converted into fluids, or fluids into solids, there is an increase of +heat of temperature, and in this case it is said that _latent_ heat is +absorbed or given out. + +The expansion due to heat has been accounted for by supposing a subtile +fluid, or _caloric_, capable of combining with bodies and of separating +their parts from each other, and the absorption and liberation of latent +heat can be explained on this principle. But many other facts are +incompatible with the theory. For instance, metal may be kept hot for +any length of time by friction, so that if _caloric_ be pressed out it +must exist in an inexhaustible quantity. Delicate experiments have shown +that bodies, when heated, do not increase in weight. + +It seems possible to account for all the phenomena of heat, if it be +supposed that in solids the particles are in a constant state of +vibratory motion, the particles of the hottest bodies moving with the +greatest velocity and through the greatest space; that in fluids and +gases the particles have not only vibratory motion, but also a motion +round their own axes with different velocities, and that in ethereal +substances the particles move round their own axes and separate from +each other, penetrating in right lines through space. Temperature may be +conceived to depend upon the velocity of the vibrations, increase of +capacity on the motion being performed in greater space; and the +diminution of temperature during the conversion of solids into fluids or +gases may be explained on the idea of the loss of vibratory motion in +consequence of the revolution of particles round their axes at the +moment when the body becomes fluid or aeriform, or from the loss of +rapidity of vibration in consequence of the motion of particles through +greater space. + +4. _Chemical Attraction._ Oil and water will not _combine_; they are +said to have no chemical _attraction_ or _affinity_ for each other. But +if oil and solution of potassa in water be mixed, the oil and the +solution blend and form a soap; and they are said to attract each other +chemically or to have a _chemical affinity_ for each other. It is a +general character of chemical combination that it changes the qualities +of the bodies. Thus, corrosive and pungent substances may become mild +and tasteless; solids may become fluids, and solids and fluids gases. + +No body will act chemically upon another body at any sensible distance; +apparent contact is necessary for chemical action. A freedom of motion +in the parts of the bodies or a want of cohesion greatly assists action, +and it was formerly believed that bodies cannot act chemically upon each +other unless one of them be fluid or gaseous. + +Different bodies unite with different degrees of force, and hence one +body is capable of separating others from certain of their combinations, +and in consequence mutual decompositions of different compounds take +place. This has been called _double affinity_, or _complex chemical +affinity_. + +As in all well-known compounds the proportions of the elements are in +certain definite ratios to each other, it is evident that these ratios +may be expressed by numbers; and if one number be employed to denote the +smallest quantity in which a body combines, all other quantities of the +same body will be multiples of this number, and the smallest proportions +into which the undecomposed bodies enter into union being known, the +constitution of the compounds they form may be learnt, and the element +which unites chemically in the smallest quantity being expressed by +unity, all the other elements may be represented by the relations of +their quantities to unity. + +5. _Electrical Attraction._ A piece of dry silk briskly rubbed against a +warm plate of polished flint glass acquires the property of adhering to +the glass, and both the silk and the glass, if apart from each other, +attract light substances. The bodies are said to be _electrically +excited_. Probably, all bodies which differ from each other become +electrically excited when rubbed and pressed together. The electrical +excitement seems of two kinds. A pith-ball touched by glass excited by +silk repels a pith-ball touched by silk excited by metals. Electrical +excitement of the same nature as that in glass excited by silk is known +as _vitreous_ or _positive_, and electrical excitement of the opposite +nature is known as _resinous_ or _negative_. + +A rod of glass touched by an electrified body is electrified only round +the point of contact. A rod of metal, on the contrary, suspended on a +rod of glass and brought into contact with an electrical surface, +instantly becomes electrical throughout. The glass is said to be a +_non-conductor_, or _insulating substance_; the metal a _conductor_. + +When a non-conductor or imperfect conductor, provided it be a thin plate +of matter placed upon a conductor, is brought in contact with an excited +electrical body, the surface opposite to that of contact gains the +opposite electricity from that of the excited body, and if the plate be +removed it is found to possess two surfaces in opposite states. If a +conductor be brought into the neighbourhood of an excited body--the air, +which is a non-conductor, being between them--that extremity of the +conductor which is opposite to the excited body gains the opposite +electricity; and the other extremity, if opposite to a body connected +with the ground, gains the same electricity, and the middle point is not +electrical at all. This is known as _induced_ electricity. + +The common exhibition of electrical effects is in attractions and +repulsions; but electricity also produces chemical phenomena. If a piece +of zinc and copper in contact with each other at one point be placed in +contact at other points with the same portion of water, the zinc will +corrode, and attract oxygen from the water much more rapidly than if it +had not been in contact with the copper; and if sulphuric acid be added, +globules of inflammable air are given off from the copper, though it is +not dissolved or acted upon. + +Chemical phenomena in connection with electrical effects can be shown +even better by combinations in which the electrical effects are +increased by alterations of different metals and fluids--the so-called +_voltaic batteries_. Such are the decomposing powers of such batteries +that not even insoluble compounds are capable of resisting their energy, +for even glass, sulphate of baryta, fluorspar, etc., are slowly acted +upon, and the alkaline, earthy, or acid matter carried to the poles in +the common order. + +The most powerful voltaic combinations are formed by substances that act +chemically with most energy upon each other, and such substances as +undergo no chemical changes in the combination exhibit no electrical +powers. Hence it was supposed that the electrical powers of metals were +entirely due to chemical changes; but this is not the case, for contact +produces electricity even when no chemical change can be observed. + + +_II.--Radiant or Ethereal Matter_ + +When similar thermometers are placed in different parts of the solar +beam, it is found that different effects are produced in the differently +coloured rays. The greatest heat is exhibited in the red rays, the least +in the violet rays; and in a space beyond the red rays, where there is +no visible light, the increase of temperature is greatest of all. + +From these facts it is evident that matter set in motion by the sun has +the power of producing heat without light, and that its rays are less +refrangible than the visible rays. The invisible rays that produce heat +are capable of reflection as well as refraction in the same manner as +the visible rays. + +Rays capable of producing heat with and without light proceed not only +from the sun, but also from bodies at the surface of the globe under +peculiar agencies or changes. If, for instance, a thermometer be held +near an ignited body, it receives an impression connected with an +elevation of temperature; this is partly produced by the conducting +powers of the air, and partly by an impulse which is instantaneously +communicated, even to a considerable distance. This effect is called the +radiation of terrestrial heat. + +The manner in which the temperatures of bodies are affected by rays +producing heat is different for different substances, and is very much +connected with their colours. The bodies that absorb most light, and +reflect least, are most heated when exposed either to solar or +terrestrial rays. Black bodies are, in general, more heated than red; +red more than green; green more than yellow; and yellow more than white. +Metals are less heated than earthy or stony bodies, or than animal or +vegetable matters. Polished surfaces are less heated than rough +surfaces. + +The bodies that have their temperatures most easily raised by heat rays +are likewise those that are most easily cooled by their own radiation, +or that at the same temperature emit most heat-making rays. Metals +radiate less heat than glass, glass less than vegetable substances, and +charcoal has the highest radiating powers of any body as yet made the +subject of experiment. + +Radiant matter has the power of producing chemical changes partly +through its heating power, and partly through some other specific and +peculiar influence. Thus chlorine and hydrogen detonate when a mixture +of them is exposed to the solar beams, even though the heat is +inadequate to produce detonation. + +If moistened silver be exposed to the different rays of the solar +spectrum, it will be found that no effect is produced upon it by the +least refrangible rays which occasion heat without light; that a slight +discoloration only will be produced by the red rays; that the effect of +blackening will be greater towards the violet end of the spectrum; and +that in a space beyond the violet, where there is no sensible heat or +light, the chemical effect will be very distinct. There seem to be rays, +therefore, more refrangible than the rays producing light and heat. + +The general facts of the refraction and effects of the solar beam offer +an analogy to the agencies of electricity. + +In general, in Nature the effects of the solar rays are very compounded. +Healthy vegetation depends upon the presence of the solar beams or of +light, and while the heat gives fluidity and mobility to the vegetable +juices, chemical effects are likewise occasioned, oxygen is separated +from them, and inflammable compounds are formed. Plants deprived of +light become white and contain an excess of saccharine and aqueous +particles; and flowers owe the variety of their hues to the influence of +the solar beams. Even animals require the presence of the rays of the +sun, and their colours seem to depend upon the chemical influence of +these rays. + +Two hypotheses have been invented to account for the principal +operations of radiant matter. In the first it is supposed that the +universe contains a highly rare elastic substance, which, when put into +a state of undulation, produces those effects on our organs of sight +which constitute the sensations of vision and other phenomena caused by +solar and terrestrial rays. In the second it is conceived that particles +are emitted from luminous or heat-making bodies with great velocity, and +that they produce their effects by communicating their motions to +substances, or by entering into them and changing their composition. + +Newton has attempted to explain the different refrangibility of the rays +of light by supposing them composed of particles differing in size. The +same great man has put the query whether light and common matter are not +convertible into each other; and, adopting the idea that the phenomena +of sensible heat depend upon vibrations of the particles of bodies, +supposes that a certain intensity of vibrations may send off particles +into free space, and that particles in rapid motion in right lines, in +losing their own motion, may communicate a vibratory motion to the +particles of terrestrial bodies. + + + + +MICHAEL FARADAY + +Experimental Researches in Electricity + + Michael Faraday was the son of a Yorkshire blacksmith, and was born + in London on September 22, 1791. At the age of twenty he became + assistant to Sir Humphry Davy, whose lectures he had attended at + the Royal Institution. Here he worked for the rest of his laborious + life, which closed on August 25, 1867. The fame of Faraday, among + those whose studies qualify them for a verdict, has risen steadily + since his death, great though it then was. His researches were of + truly epoch-making character, and he was the undisputed founder of + the modern science of electricity, which is rapidly coming to + dominate chemistry itself. Faraday excelled as a lecturer, and + could stand even the supreme test of lecturing to children. + Faraday's "Experimental Researches in Electricity" is a record of + some of the most brilliant experiments in the history of science. + In the course of his investigations he made discoveries which have + had momentous consequences. His discovery of the mutual relation of + magnets and of wires conducting electric currents was the beginning + of the modern dynamo and all that it involves; while his + discoveries of electric induction and of electrolysis were of equal + significance. Most of the researches are too technical for + epitomisation; but those given are representative of his manner and + methods. + + +_I.--Atmospheric Magnetism_ + +It is to me an impossible thing to perceive that two-ninths of the +atmosphere by weight is a highly magnetic body, subject to great changes +in its magnetic character, by variations in its temperature and +condensation or rarefaction, without being persuaded that it has much to +do with the variable disposition of the magnetic forces upon the surface +of the earth. + +The earth is a spheroidal body consisting of paramagnetic and +diamagnetic substances irregularly disposed and intermingled; but for +the present the whole may be considered a mighty compound magnet. The +magnetic force of this great magnet is known to us only on the surface +of the earth and water of our planet, and the variations in the magnetic +lines of force which pass in or across this surface can be measured by +their action on small standard magnets; but these variations are limited +in their information, and do not tell us whether the cause is in the air +above or the earth beneath. + +The lines of force issue from the earth in the northern and southern +parts and coalesce with each other over the equatorial, as would be the +case in a globe having one or two short magnets adjusted in relation to +its axis, and it is probable that the lines of force in their circuitous +course may extend through space to tens of thousands of miles. The lines +proceed through space with a certain degree of facility, but there may +be variations in space, _e.g._, variations in its temperature which +affect its power of transmitting the magnetic influence. + +Between the earth and space, however, is interposed the atmosphere, and +at the bottom of the atmosphere we live. The atmosphere consists of four +volumes of nitrogen and one of oxygen uniformly mixed and acting +magnetically as a single medium. The _nitrogen_ of the air is, as +regards the magnetic force, neither paramagnetic nor diamagnetic, +whether dense or rare, or at high or low temperatures. + +The _oxygen_ of the air, on the other hand, is highly paramagnetic, +being, bulk for bulk, equivalent to a solution of protosulphate of iron, +containing of the crystallised salt seventeen times the weight of the +oxygen. It becomes less paramagnetic, volume for volume, as it is +rarefied, and apparently in the simple proportion of its rarefaction, +the temperature remaining the same. When its temperature is raised--the +expansion consequent thereon being permitted--it loses very greatly its +paramagnetic force, and there is sufficient reason to conclude that when +its temperature is lowered its paramagnetic condition is exalted. These +characters oxygen preserves even when mingled with the nitrogen in the +air. + +Hence the atmosphere is a highly magnetic medium, and this medium is +changed in its magnetic relations by every change in its density and +temperature, and must affect both the intensity and direction of the +magnetic force emanating from the earth, and may account for the +variations which we find in terrestrial magnetic power. + +We may expect as the sun leaves us on the west some magnetic effect +correspondent to that of the approach of a body of cold air from the +east. Again, the innumerable circumstances that break up more or less +any average arrangement of the air temperatures may be expected to give +not merely differences in the regularity, direction, and degree of +magnetic variation, but, because of vicinity, differences so large as to +be many times greater than the mean difference for a given short period, +and they may also cause irregularities in the times of their occurrence. +Yet again, the atmosphere diminishes in density upwards, and this +diminution will affect the transmission of the electric force. + +The result of the _annual variation_ that may be expected from the +magnetic constitution and condition of the atmosphere seems to me to be +of the following kind. + +Since the axis of the earth's rotation is inclined 23° 28' to the plane +of the ecliptic, the two hemispheres will become alternately warmer and +cooler than each other. The air of the cooled hemisphere will conduct +magnetic influence more freely than if in the mean state, and the lines +of force passing through it will increase in amount, whilst in the other +hemisphere the warmed air will conduct with less readiness than before, +and the intensity will diminish. In addition to this effect of +temperature, there ought to be another due to the increase of the +ponderable portion of the air in the cooled hemisphere, consequent on +its contraction and the coincident expansion of the air in the warmer +half, both of which circumstances tend to increase the variation in +power of the two hemispheres from the normal state. Then, as the earth +rolls on its annual journey, that which was at one time the cooler +becomes the warmer hemisphere, and in its turn sinks as far below the +average magnetic intensity as it before had stood above it, while the +other hemisphere changes its magnetic condition from less to more +intense. + + +_II.--Electro-Chemical Action_ + +The theory of definite electrolytical or electro-chemical action appears +to me to touch immediately upon the absolute quantity of electricity +belonging to different bodies. As soon as we perceive that chemical +powers are definite for each body, and that the electricity which we can +loosen from each body has definite chemical action which can be +measured, we seem to have found the link which connects the proportion +of that we have evolved to the proportion belonging to the particles in +their natural state. + +Now, it is wonderful to observe how small a quantity of a compound body +is decomposed by a certain quantity of electricity. One grain of water, +for instance, acidulated to facilitate conduction, will require an +electric current to be continued for three minutes and three-quarters to +effect its decomposition, and the current must be powerful enough to +keep a platina wire 1/104 inch in thickness red hot in the air during +the whole time, and to produce a very brilliant and constant star of +light if interrupted anywhere by charcoal points. It will not be too +much to say that this necessary quantity of electricity is equal to a +very powerful flash of lightning; and yet when it has performed its full +work of electrolysis, it has separated the elements of only a single +grain of water. + +On the other hand, the relation between the conduction of the +electricity and the decomposition of the water is so close that one +cannot take place without the other. If the water be altered only in +that degree which consists in its having the solid instead of the fluid +state, the conduction is stopped and the decomposition is stopped with +it. Whether the conduction be considered as depending upon the +decomposition or not, still the relation of the two functions is equally +intimate. + +Considering this close and twofold relation--namely, that without +decomposition transmission of electricity does not occur, and that for a +given definite quantity of electricity passed an equally definite and +constant quantity of water or other matter is decomposed; considering +also that the agent, which is electricity, is simply employed in +overcoming electrical powers in the body subjected to its action, it +seems a probable and almost a natural consequence that the quantity +which passes is the equivalent of that of the particles separated; +_i.e._, that if the electrical power which holds the elements of a grain +of water in combination, or which makes a grain of oxygen and hydrogen +in the right proportions unite into water when they are made to combine, +could be thrown into a current, it would exactly equal the current +required for the separation of that grain of water into its elements +again; in other words, that the electricity which decomposes and that +which is evolved by the decomposition of a certain quantity of matter +are alike. + +This view of the subject gives an almost overwhelming idea of the +extraordinary quantity or degree of electric power which naturally +belongs to the particles of matter, and the idea may be illustrated by +reference to the voltaic pile. + +The source of the electricity in the voltaic instrument is due almost +entirely to chemical action. Substances interposed between its metals +are all electrolytes, and the current cannot be transmitted without +their decomposition. If, now, a voltaic trough have its extremities +connected by a body capable of being decomposed, such as water, we shall +have a continuous current through the apparatus, and we may regard the +part where the acid is acting on the plates and the part where the +current is acting upon the water as the reciprocals of each other. In +both parts we have the two conditions, _inseparable in such bodies as +these_: the passing of a current, and decomposition. In the one case we +have decomposition associated with a current; in the other, a current +followed by decomposition. + +Let us apply this in support of my surmise respecting the enormous +electric power of each particle or atom of matter. + +Two wires, one of platina, and one of zinc, each one-eighteenth of an +inch in diameter, placed five-sixteenths of an inch apart, and immersed +to the depth of five-eighths of an inch in acid, consisting of one drop +of oil of vitriol and four ounces of distilled water at a temperature of +about 60° Fahrenheit, and connected at the other ends by a copper wire +eighteen feet long, and one-eighteenth of an inch in thickness, yielded +as much electricity in little more than three seconds of time as a +Leyden battery charged by thirty turns of a very large and powerful +plate electric machine in full action. This quantity, although +sufficient if passed at once through the head of a rat or cat to have +killed it, as by a flash of lightning, was evolved by the mutual action +of so small a portion of the zinc wire and water in contact with it that +the loss of weight by either would be inappreciable; and as to the water +which could be decomposed by that current, it must have been insensible +in quantity, for no trace of hydrogen appeared upon the surface of the +platina during these three seconds. It would appear that 800,000 such +charges of the Leyden battery would be necessary to decompose a single +grain of water; or, if I am right, to equal the quantity of electricity +which is naturally associated with the elements of that grain of water, +endowing them with their mutual chemical affinity. + +This theory of the definite evolution and the equivalent definite action +of electricity beautifully harmonises the associated theories of +definite proportions and electro-chemical affinity. + +According to it, the equivalent weights of bodies are simply those +quantities of them which contain equal quantities of electricity, or +have naturally equal electric powers, it being the electricity which +_determines_ the equivalent number, _because_ it determines the +combining force. Or, if we adopt the atomic theory or phraseology, then +the atoms of bodies which are equivalent to each other in their ordinary +chemical action have equal quantities of electricity naturally +associated with them. I cannot refrain from recalling here the beautiful +idea put forth, I believe, by Berzelius in his development of his views +of the electro-chemical theory of affinity, that the heat and light +evolved during cases of powerful combination are the consequence of the +electric discharge which is at the moment taking place. The idea is in +perfect accordance with the view I have taken of the quantity of +electricity associated with the particles of matter. + +The definite production of electricity in association with its definite +action proves, I think, that the current of electricity in the voltaic +pile is sustained by chemical decomposition, or, rather, by chemical +action, and not by contact only. But here, as elsewhere, I beg to +reserve my opinion as to the real action of contact. + +Admitting, however, that chemical action is the source of electricity, +what an infinitely small fraction of that which is active do we obtain +and employ in our voltaic batteries! Zinc and platina wires +one-eighteenth of an inch in diameter and about half an inch long, +dipped into dilute sulphuric acid, so weak that it is not sensibly sour +to the tongue, or scarcely sensitive to our most delicate test papers, +will evolve more electricity in one-twentieth of a minute than any man +would willingly allow to pass through his body at once. + +The chemical energy represented by the satisfaction of the chemical +affinities of a grain of water and four grains of zinc can evolve +electricity equal in quantity to that of a powerful thunderstorm. Nor is +it merely true that the quantity is active; it can be directed--made to +perform its full equivalent duty. Is there not, then, great reason to +believe that, by a closer investigation of the development and action of +this subtile agent, we shall be able to increase the power of our +batteries, or to invent new instruments which shall a thousandfold +surpass in energy those we at present possess? + + +_III.--The Gymnotus, or Electric Eel_ + +Wonderful as are the laws and phenomena of electricity when made evident +to us in inorganic or dead matter, their interest can bear scarcely any +comparison with that which attaches to the same force when connected +with the nervous system and with life. + +The existence of animals able to give the same concussion to the living +system as the electrical machine, the voltaic battery, and the +thunderstorm being made known to us by various naturalists, it became +important to identify their electricity with the electricity produced by +man from dead matter. In the case of the _Torpedo_ [a fish belonging to +the family of Electric Rings] this identity has been fully proved, but +in the case of the _Gymnotus_ the proof has not been quite complete, and +I thought it well to obtain a specimen of the latter fish. + +A gymnotus being obtained, I conducted a series of experiments. Besides +the hands two kinds of collectors of electricity were used--one with a +copper disc for contact with the fish, and the other with a plate of +copper bent into saddle shape, so that it might enclose a certain +extent of the back and sides of the fish. These conductors, being put +over the fish, collected power sufficient to produce many electric +effects. + +SHOCK. The shock was very powerful when the hands were placed one near +the head and the other near the tail, and the nearer the hands were +together, within certain limits, the less powerful was the shock. The +disc conductors conveyed the shock very well when the hands were wetted. + +GALVANOMETER. A galvanometer was readily affected by using the saddle +conductors, applied to the anterior and posterior parts of the gymnotus. +A powerful discharge of the fish caused a deflection of thirty or forty +degrees. The deflection was constantly in a given direction, the +electric current being always from the anterior part of the animal +through the galvanometer wire to the posterior parts. The former were, +therefore, for the time externally positive and the latter negative. + +MAKING A MAGNET. When a little helix containing twenty-two feet of +silked wire wound on a quill was put into a circuit, and an annealed +steel needle placed in the helix, the needle became a magnet; and the +direction of its polarity in every cast indicated a current from the +anterior to the posterior parts of the gymnotus. + +CHEMICAL DECOMPOSITION. Polar decomposition of a solution of iodide of +potassium was easily obtained. + +EVOLUTION OF HEAT. Using a Harris' thermo-electrometer, we thought we +were able, in one instance, to observe a feeble elevation of +temperature. + +SPARK. By suitable apparatus a spark was obtained four times. + +Such were the general electric phenomena obtained from the gymnotus, and +on several occasions many of the phenomena were obtained together. Thus, +a magnet was made, a galvanometer deflected, and, perhaps, a wire heated +by one single discharge of the electric force of the animal. When the +shock is strong, it is like that of a large Leyden battery charged to a +low degree, or that of a good voltaic battery of, perhaps, one hundred +or more pairs of plates, of which the circuit is completed for a moment +only. + +I endeavoured by experiment to form some idea of the quantity of +electricity, and came to the conclusion that a single medium discharge +of the fish is at least equal to the electricity of a Leyden battery of +fifteen jars, containing 3,500 square inches of glass coated on both +sides, charged to its highest degree. This conclusion is in perfect +accordance with the degree of deflection which the discharge can produce +in a galvanometer needle, and also with the amount of chemical +decomposition produced in the electrolysing experiments. + +The gymnotus frequently gives a double and even a triple shock, with +scarcely a sensible interval between each discharge. + +As at the moment of shock the anterior parts are positive and the +posterior negative, it may be concluded that there is a current from the +former to the latter through every part of the water which surrounds the +animal, to a considerable distance from its body. The shock which is +felt, therefore, when the hands are in the most favourable position is +the effect of a very small portion only of the electricity which the +animal discharges at the moment, by far the largest portion passing +through the surrounding water. + +This enormous external current must be accompanied by some effect within +the fish _equivalent_ to a current, the direction of which is from the +tail towards the head, and equal to the sum of _all these external_ +forces. Whether the process of evolving or exciting the electricity +within the fish includes the production of the internal current, which +is not necessarily so quick and momentary as the external one, we cannot +at present say; but at the time of the shock the animal does not +apparently feel the electric sensation which he causes in those around +him. + +The gymnotus can stun and kill fish which are in very various relations +to its own body. The extent of surface which the fish that is about to +be struck offers to the water conducting the electricity increases the +effect of the shock, and the larger the fish, accordingly, the greater +must be the shock to which it will be subjected. + + + + +The Chemical History of a Candle + + "The Chemical History of a Candle" was the most famous course in + the long and remarkable series of Christmas lectures, "adapted to a + juvenile auditory," at the Royal Institution, and remains a + rarely-approached model of what such lectures should be. They were + illustrated by experiments and specimens, but did not depend upon + these for coherence and interest. They were delivered in 1860-61, + and have just been translated, though all but half-a-century old, + into German. + + +_I.--Candles and their Flames_ + +There is not a law under which any part of this universe is governed +that does not come into play in the phenomena of the chemical history of +a candle. There is no better door by which you can enter into the study +of natural philosophy than by considering the physical phenomena of a +candle. + +And now, my boys and girls, I must first tell you of what candles are +made. Some are great curiosities. I have here some bits of timber, +branches of trees particularly famous for their burning. And here you +see a piece of that very curious substance taken out of some of the bogs +in Ireland, called _candle-wood_--a hard, strong, excellent wood, +evidently fitted for good work as a resister of force, and yet withal +burning so well that, where it is found, they make splinters of it, and +torches, since it burns like a candle, and gives a very good light +indeed. And in this wood we have one of the most beautiful illustrations +of the general nature of a candle that I can possibly give. The fuel +provided, the means of bringing that fuel to the place of chemical +action, the regular and gradual supply of air to that place of +action--heat and light all produced by a little piece of wood of this +kind, forming, in fact, a natural candle. + +But we must speak of candles as they are in commerce. Here are a couple +of candles commonly called dips. They are made of lengths of cotton cut +off, hung up by a loop, dipped into melted tallow, taken out again and +cooled; then re-dipped until there is an accumulation of tallow round +the cotton. However, a candle, you know, is not now a greasy thing like +an ordinary tallow candle, but a clean thing; and you may almost scrape +off and pulverise the drops which fall from it without soiling anything. + +The candle I have in my hand is a stearine candle, made of stearine from +tallow. Then here is a sperm candle, which comes from the purified oil +of the spermaceti whale. Here, also, are yellow beeswax and refined +beeswax from which candles are made. Here, too, is that curious +substance called paraffin, and some paraffin candles made of paraffin +obtained from the bogs of Ireland. I have here also a substance brought +from Japan, a sort of wax which a kind friend has sent me, and which +forms a new material for the manufacture of candles. + +Now, as to the light of the candle. We will light one or two, and set +them at work in the performance of their proper function. You observe a +candle is a very different thing from a lamp. With a lamp you take a +little oil, fill your vessel, put in a little moss, or some cotton +prepared by artificial means, and then light the top of the wick. When +the flame runs down the cotton to the oil, it gets stopped, but it goes +on burning in the part above. Now, I have no doubt you will ask, how is +it that the oil, which will not burn of itself, gets up to the top of +the cotton, where it will burn? We shall presently examine that; but +there is a much more wonderful thing about the burning of a candle than +this. You have here a solid substance with no vessel to contain it; and +how is it that this solid substance can get up to the place where the +flame is? Or, when it is made a fluid, then how is it that it keeps +together? This is a wonderful thing about a candle. + +You see, then, in the first instance, that a beautiful cup is formed. As +the air comes to the candle, it moves upwards by the force of the +current which the heat of the candle produces, and it so cools all the +sides of the wax, tallow, or fuel as to keep the edge much cooler than +the part within; the part within melts by the flame that runs down the +wick as far as it can go before it is stopped, but the part on the +outside does not melt. If I made a current in one direction, my cup +would be lopsided, and the fluid would consequently run over--for the +same force of gravity which holds worlds together, holds this fluid in a +horizontal position. You see, therefore, that the cup is formed by this +beautifully regular ascending current of air playing upon all sides, +which keeps the exterior of the candle cool. No fuel would serve for a +candle which has not the property of giving this cup, except such fuel +as the Irish bogwood, where the material itself is like a sponge, and +holds its own fuel. + +You see now why you have such a bad result if you burn those beautiful +fluted candles, which are irregular, intermittent in their shape, and +cannot therefore have that nicely-formed edge to the cup which is the +great beauty in a candle. I hope you will now see that the perfection of +a process--that is, its utility--is the better point of beauty about it. +It is not the best-looking thing, but the best-acting thing which is the +most advantageous to us. This good-looking candle is a bad burning one. +There will be a guttering round about it because of the irregularity of +the stream of air and the badness of the cup which is formed thereby. + +You may see some pretty examples of the action of the ascending current +when you have a little gutter run down the side of a candle, making it +thicker there than it is elsewhere. As the candle goes on burning, that +keeps its place and forms a little pillar sticking up by the side, +because, as it rises higher above the rest of the wax or fuel, the air +gets better round it, and it is more cooled and better able to resist +the action of the heat at a little distance. Now, the greatest mistakes +and faults with regard to candles, as in many other things, often bring +with them instruction which we should not receive if they had not +occurred. You will always remember that whenever a result happens, +especially if it be new, you should say: "What is the cause? Why does it +occur?" And you will in the course of time find out the reason. + +Then there is another point about these candles which will answer a +question--that is, as to the way in which this fluid gets out of the +cup, up to the wick, and into the place of combustion. You know that the +flames on these burning wicks in candles made of beeswax, stearine, or +spermaceti, do not run down to the wax or other matter, and melt it all +away, but keep to their own right place. They are fenced off from the +fluid below, and do not encroach on the cup at the sides. + +I cannot imagine a more beautiful example than the condition of +adjustment under which a candle makes one part subserve to the other to +the very end of its action. A combustible thing like that, burning away +gradually, never being intruded upon by the flame, is a very beautiful +sight; especially when you come to learn what a vigorous thing flame is, +what power it has of destroying the wax itself when it gets hold of it, +and of disturbing its proper form if it come only too near. + +But how does the flame get hold of the fuel? There is a beautiful point +about that. It is by what is called capillary attraction that the fuel +is conveyed to the part where combustion goes on, and is deposited +there, not in a careless way, but very beautifully in the very midst of +the centre of action which takes place around it. + + +_II.--The Brightness of the Candle_ + +Air is absolutely necessary for combustion; and, what is more, I must +have you understand that _fresh_ air is necessary, or else we should be +imperfect in our reasoning and our experiments. Here is a jar of air. I +place it over a candle, and it burns very nicely in it at first, showing +that what I have said about it is true; but there will soon be a change. +See how the flame is drawing upwards, presently fading, and at last +going out. And going out, why? Not because it wants air merely, for the +jar is as full now as it was before, but it wants pure, fresh air. The +jar is full of air, partly changed, partly not changed; but it does not +contain sufficient of the fresh air for combustion. + +Suppose I take a candle, and examine that part of it which appears +brightest to our eyes. Why, there I get these black particles, which are +just the smoke of the candle; and this brings to mind that old +employment which Dean Swift recommended to servants for their amusement, +namely, writing on the ceiling of a room with a candle. But what is that +black substance? Why, it is the same carbon which exists in the candle. +It evidently existed in the candle, or else we should not have had it +here. You would hardly think that all those substances which fly about +London in the form of soots and blacks are the very beauty and life of +the flame. Here is a piece of wire gauze which will not let the flame go +through it, and I think you will see, almost immediately, that, when I +bring it low enough to touch that part of the flame which is otherwise +so bright, it quells and quenches it at once, and allows a volume of +smoke to rise up. + +Whenever a substance burns without assuming the vaporous state--whether +it becomes liquid or remains solid--it becomes exceedingly luminous. +What I say is applicable to all substances--whether they burn or whether +they do not burn--that they are exceedingly bright if they retain their +solid state when heated, and that it is to this presence of solid +particles in the candle-flame that it owes its brilliancy. + +I have here a piece of carbon, or charcoal, which will burn and give us +light exactly in the same manner as if it were burnt as part of a +candle. The heat that is in the flame of a candle decomposes the vapour +of the wax, and sets free the carbon particles--they rise up heated and +glowing as this now glows, and then enter into the air. But the +particles when burnt never pass off from a candle in the form of carbon. +They go off into the air as a perfectly invisible substance, about which +we shall know hereafter. + +Is it not beautiful to think that such a process is going on, and that +such a dirty thing as charcoal can become so incandescent? You see, it +comes to this--that all bright flames contain these solid particles; all +things that burn and produce solid particles, either during the time +they are burning, as in the candle, or immediately after being burnt, as +in the case of the gunpowder and iron-filings--all these things give us +this glorious and beautiful light. + + +_III.--The Products of Combustion_ + +We observe that there are certain products as the result of the +combustion of a candle, and that of these products one portion may be +considered as charcoal, or soot; that charcoal, when afterwards burnt, +produces some other product--carbonic acid, as we shall see; and it +concerns us very much now to ascertain what yet a third product is. + +Suppose I take a candle and place it under a jar. You see that the sides +of the jar become cloudy, and the light begins to burn feebly. It is the +products, you see, which make the light so dim, and this is the same +thing which makes the sides of the jar so opaque. If you go home and +take a spoon that has been in the cold air, and hold it over a +candle--not so as to soot it--you will find that it becomes dim, just as +that jar is dim. If you can get a silver dish, or something of that +kind, you will make the experiment still better. It is _water_ which +causes the dimness, and we can make it, without difficulty, assume the +form of a liquid. + +And so we can go on with almost all combustible substances, and we find +that if they burn with a flame, as a candle, they produce water. You may +make these experiments yourselves. The head of a poker is a very good +thing to try with, and if it remains cold long enough over the candle, +you may get water condensed in drops on it; or a spoon, or a ladle, or +anything else may be used, provided it be clean, and can carry off the +heat, and so condense the water. + +And now--to go into the history of this wonderful production of water +from combustibles, and by combustion--I must first of all tell you that +this water may exist in different conditions; and although you may now +be acquainted with all its forms, they still require us to give a little +attention to them for the present, so that we may perceive how the +water, whilst it goes through its protean changes, is entirely and +absolutely the same thing, whether it is produced from a candle, by +combustion, or from the rivers or ocean. + +First of all, water, when at the coldest, is ice. Now, we speak of water +as water; whether it be in its solid, or liquid, or gaseous state, we +speak of it chemically as water. + +We shall not in future be deceived, therefore, by any changes that are +produced in water. Water is the same everywhere, whether produced from +the ocean or from the flame of the candle. Where, then, is this water +which we get from a candle? It evidently comes, as to part of it, from +the candle; but is it within the candle beforehand? No! It is not in the +candle; and it is not in the air round about the candle, which is +necessary for its combustion. It is neither in one nor the other, but it +comes from their conjoint action, a part from the candle, a part from +the air. And this we have now to trace. + +If we decompose water we can obtain from it a gas. This is hydrogen--a +body classed amongst those things in chemistry which we call elements, +because we can get nothing else out of them. A candle is not an +elementary body, because we can get carbon out of it; we can get this +hydrogen out of it, or at least out of the water which it supplies. And +this gas has been so named hydrogen because it is that element which, in +association with another, generates water. + +Hydrogen gives rise to no substance that can become solid, either during +combustion or afterwards, as a product of its combustion. But when it +burns it produces water only; and if we take a cold glass and put it +over the flame, it becomes damp, and you have water produced immediately +in appreciable quantity, and nothing is produced by its combustion but +the same water which you have seen the flame of a candle produce. This +hydrogen is the only thing in Nature that furnishes water as the sole +product of combustion. + +Water can be decomposed by electricity, and then we find that its other +constituent is the gas oxygen in which, as can easily be shown, a candle +or a lamp burns much more brilliantly than it does in air, but produces +the same products as when it burns in air. We thus find that oxygen is +a constituent of the air, and by burning something in the air we can +remove the oxygen therefrom, leaving behind for our study the nitrogen, +which constitutes about four-fifths of the air, the oxygen accounting +for nearly all the rest. + +The other great product of the burning of a candle is carbonic acid--a +gas formed by the union of the carbon of the candle and the oxygen of +the air. Whenever carbon burns, whether in a candle or in a living +creature, it produces carbonic acid. + + +_IV.--Combustion and Respiration_ + +Now I must take you to a very interesting part of our subject--to the +relation between the combustion of a candle and that living kind of +combustion which goes on within us. In every one of us there is a living +process of combustion going on very similar to that of a candle. For it +is not merely true in a poetical sense--the relation of the life of man +to a taper. A candle will burn some four, five, six, or seven hours. +What, then, must be the daily amount of carbon going up into the air in +the way of carbonic acid? What a quantity of carbon must go from each of +us in respiration! A man in twenty-four hours converts as much as seven +ounces of carbon into carbonic acid; a milch cow will convert seventy +ounces, and a horse seventy-nine ounces, solely by the act of +respiration. That is, the horse in twenty-four hours burns seventy-nine +ounces of charcoal, or carbon, in his organs of respiration to supply +his natural warmth in that time. + +All the warm-blooded animals get their warmth in this way, by the +conversion of carbon; not in a free state, but in a state of +combination. And what an extraordinary notion this gives us of the +alterations going out in our atmosphere! As much as 5,000,000 pounds of +carbonic acid is formed by respiration in London alone in twenty-four +hours. And where does all this go? Up into the air. If the carbon had +been like lead or iron, which, in burning, produces a solid substance, +what would happen? Combustion would not go on. As charcoal burns, it +becomes a vapour and passes off into the atmosphere, which is the great +vehicle, the great carrier, for conveying it away to other places. Then, +what becomes of it? + +Wonderful is it to find that the change produced by respiration, which +seems so injurious to us, for we cannot breathe air twice over, is the +very life and support of plants and vegetables that grow upon the +surface of the earth. It is the same also under the surface in the great +bodies of water, for fishes and other animals respire upon the same +principle, though not exactly by contact with the open air. They respire +by the oxygen which is dissolved from the air by the water, and form +carbonic acid; and they all move about to produce the one great work of +making the animal and vegetable kingdoms subservient to each other. + +All the plants growing upon the surface of the earth absorb carbon. +These leaves are taking up their carbon from the atmosphere, to which we +have given it in the form of carbonic acid, and they are prospering. +Give them a pure air like ours, and they could not live in it; give them +carbon with other matters, and they live and rejoice. So are we made +dependent not merely upon our fellow-creatures, but upon our +fellow-existers, all Nature being tied by the laws that make one part +conduce to the good of the other. + + + + +AUGUSTE FOREL + +The Senses of Insects + + Auguste Forel, who in 1909 retired from the Chair of Morbid + Psychology in the University of Zürich, was born on September 1, + 1848, and is one of the greatest students of the minds and senses + of the lower animals and mankind. Among his most famous works are + his "Hygiene of Nerves and Mind," his great treatise on the whole + problem of sex in human life, of which a cheap edition entitled + "Sexual Ethics" is published, his work on hypnotism, and his + numerous contributions to the psychology of insects. The chief + studies of this remarkable and illustrious student and thinker for + many decades past have been those of the senses and mental + faculties of insects. He has recorded the fact that his study of + the beehive led him to his present views as to the right + constitution of the state--views which may be described as + socialism with a difference. His work on insects has served the + study of human psychology, and is in itself the most important + contribution to insect psychology ever made by a single student. + Only within the last two years has the work of Forel, long famous + on the European Continent, begun to be known abroad. + + +_I.--Insect Activity and Instinct_ + +This subject is one of great interest, as much from the standpoint of +biology as from that of comparative psychology. The very peculiar +mechanism of instincts always has its starting-point in sensations. To +comprehend this mechanism it is essential to understand thoroughly the +organs of sense and their special functions. + +It is further necessary to study the co-ordination which exists between +the action of the different senses, and leads to their intimate +connection with the functions of the nerve-centres, that is to say, with +the specially instinctive intelligence of insects. The whole question +is, therefore, a chapter of comparative psychology, a chapter in which +it is necessary to take careful note of every factor, to place oneself, +so to speak, on a level with the mind of an insect, and, above all, to +avoid the anthropomorphic errors with which works upon the subject are +filled. + +At the same time the other extreme must equally be +avoided--"anthropophobia," which at all costs desires to see in every +living organism a "machine," forgetting that a "machine" which lives, +that is to say, which grows, takes in nutriment, and strikes a balance +between income and expenditure, which, in a word, continually +reconstructs itself, is not a "machine," but something entirely +different. In other words, it is necessary to steer clear of two +dangers. We must avoid (1) identifying the mind of an insect with our +own, but, above all, (2) imagining that we, with what knowledge we +possess, can reconstruct the mind by our chemical and physical laws. + +On the other hand, we have to recognise the fact that this mind, and the +sensory functions which put it on its guard, are derived, just as with +our human selves, from the primitive protoplasmic life. This life, so +far as it is specialised in the nervous system by nerve irritability and +its connections with the muscular system, is manifested under two +aspects. These may be likened to two branches of one trunk. + +(_a_) _Automatic_ or _instinctive_ activity. This, though perfected by +repetition, is definitely inherited. It is uncontrollable and constant +in effect, adapted to the circumstances of the special life of the race +in question. It is this curious instinctive adaptation--which is so +intelligent when it carries out its proper task, so stupid and incapable +when diverted to some other purpose--that has deceived so many +scientists and philosophers by its insidious analogy with humanly +constructed machines. + +But, automatic as it may appear, instinct is not invariable. In the +first place, it presents a racial evolution which of itself alone +already demonstrates a certain degree of plasticity from generation to +generation. It presents, further, individual variations which are more +distinct as it is less deeply fixed by heredity. Thus the divergent +instincts of two varieties, _e.g._, of insects, present more individual +variability and adaptability than do those instincts common to all +species of a genus. In short, if we carefully study the behaviour of +each individual of a species of insects with a developed brain (as has +been done by P. Huber, Lubbock, Wasmann, and myself, among others, for +bees, wasps, and ants), we are not long in finding noteworthy +differences, especially when we put the instinct under abnormal +conditions. We then force the nervous activity of these insects to +present a second and plastic aspect, which to a large extent has been +hidden from us under their enormously developed instinct. + +(_b_) The _plastic_ or _adaptive_ activity is by no means, as has been +so often suggested, a derivative of instinct. It is primitive. It is +even the fundamental condition of the evolution of life. The living +being is distinguished by its power of adaptation; even the amoeba is +plastic. But in order that one individual may adapt itself to a host of +conditions and possibilities, as is the case with the higher mammals and +especially with man, the brain requires an enormous quantity of nerve +elements. But this is not the case with the fixed and specialised +adaptation of instinct. + +In secondary automatism, or habit, which we observe in ourselves, it is +easy to study how this activity, derived from plastic activity, and ever +becoming more prompt, complex, and sure (technical habits), necessitates +less and less expenditure of nerve effort. It is very difficult to +understand how inherited instinct, hereditary automatism, could have +originated from the plastic activities of our ancestors. It seems as if +a very slow selection, among individuals best adapted in consequence of +fortunate parentage, might perhaps account for it. + +To sum up, every animal possesses two kinds of activity in varying +degrees, sometimes one, sometimes the other predominating. In the lowest +beings they are both rudimentary. In insects, special automatic activity +reaches the summit of development and predominance; in man, on the +contrary, with his great brain development, plastic activity is elevated +to an extraordinary height, above all by language, and before all by +written language, which substitutes graphic fixation for secondary +automatism, and allows the accumulation outside the brain of the +knowledge of past generations, thus serving his plastic activity, at +once the adapter and combiner of what the past has bequeathed to it. + +According to the families, _genera_, and species of insects, the +development of different senses varies extremely. We meet with most +striking contrasts, and contrasts which have not been sufficiently +noticed. Certain insects, dragon-flies, for instance, live almost +entirely by means of sight. Others are blind, or almost blind, and +subsist exclusively by smell and taste (insects inhabiting caves, most +working ants). Hearing is well developed in certain forms (crickets, +locusts), but most insects appear not to hear, or to hear with +difficulty. Despite their thick, chitinous skeleton, almost all insects +have extremely sensitive touch, especially in the antennæ, but not +confined thereto. + +It is absolutely necessary to bear in mind the mental faculties of +insects in order to judge with a fair degree of accuracy how they use +their senses. We shall return to that point when summing up. + + +_II.--The Vision of Insects_ + +In vision we are dealing with a certain definite stimulus--light, with +its two modifications, colour and motion. Insects have two sets of +organs for vision, the faceted eye and the so-called simple eye, or +ocellus. These have been historically derived from one and the same +organ. In order to exercise the function of sight the facets need a +greater pencil of light rays by night than by day. To obtain the same +result we dilate the pupil. But nocturnal insects are dazzled by the +light of day, and diurnal insects cannot see by night, for neither +possess the faculty of accommodation. Insects are specially able to +perceive motion, but there are only very few insects that can see +distinctly. + +For example, I watched one day a wasp chasing a fly on the wall of a +veranda, as is the habit of this insect at the end of summer and in the +autumn. She dashed violently in flight at the flies sitting on the wall, +which mostly escaped. She continued her pursuit with remarkable +pertinacity, and succeeded on several occasions in catching a fly, which +she killed, mutilated, and bore away to her nest. Each time she quickly +returned to continue the hunt. + +In one spot of the wall was stuck a black nail, which was just the size +of a fly, and I saw the wasp very frequently deceived by this nail, upon +which she sprang, leaving it as soon as she perceived her error on +touching it. Nevertheless, she made the same mistake with the nail +shortly after. I have often made similar observations. We may certainly +conclude that the wasp saw something of the size of a fly, but without +distinguishing the details; therefore she saw it indistinctly. Evidently +a wasp does not only perceive motion; she also distinguishes the size of +objects. When I put dead flies on a table to be carried off by another +wasp, she took them, one after another, as well as spiders and other +insects of but little different size placed by their side. On the other +hand, she took no notice of insects much larger or much smaller put +among the flies. + +Most entomologists have observed with what ingenuity and sureness +dragon-flies distinguish, follow, and catch the smallest insects on the +wing. Of all insects, they have the best sight. Their enormous convex +eyes have the greatest number of facets. Their number has been estimated +at 12,000, and even at 17,000. Their aerial chases resemble those of the +swallows. By trying to catch them at the edge of a large pond, one can +easily convince oneself that the dragon-flies amuse themselves by making +sport of the hunter; they will always allow one to approach just near +enough to miss catching them. It can be seen to what degree they are +able to measure the distance and reach of their enemy. + +It is an absolute fact that dragon-flies, unless it is cold or in the +evening, always manage to fly at just that distance at which the student +cannot touch them; and they see perfectly well whether one is armed with +a net or has nothing but his hands; one might even say that they measure +the length of the handle of the net, for the possession of a long handle +is no advantage. They fly just out of reach of one's instrument, +whatever trouble one may give oneself by hiding it from them and +suddenly lunging as they fly off. Whoever watches butterflies and flies +will soon see that these insects also can measure the distance of such +objects as are not far from them. The males and females of bees and ants +distinguish one another on the wing. It is rare for an individual to +lose sight of the swarm or to miss what it pursues flying. It has been +proved that the sense of smell has nothing to do with this matter. Thus +insects, though without any power of accommodation for light or +distance, are able to perceive objects at different distances. + +It is known that many insects will blindly fly and dash against a lamp +at night, until they burn themselves. It has often been wrongly thought +that they are fascinated. We ought first to remember that natural +lights, concentrated at one point like our artificial lights, are +extremely rare in Nature. The light of day, which is the light of wild +animals, is not concentrated at one point. Insects, when they are in +darkness--underground, beneath bark or leaves--are accustomed to reach +the open air, where the light is everywhere diffused, by directing +themselves towards the luminous point. At night, when they fly towards a +lamp, they are evidently deceived, and their small brains cannot +comprehend the novelty of this light concentrated at one spot. +Consequently, their fruitless efforts are again and again renewed +against the flame, and the poor innocents end by burning themselves. +Several domestic insects, which have become little by little adapted to +artificial light in the course of generations, no longer allow +themselves to be deceived thereby. This is the case with house-flies. + +Bees distinguish all colours, and seldom confound any but blue and +green; while wasps scarcely react to differences of colour, but note +better the shape of an object, and note, for instance, where the place +of honey is; so that a change of colour on the disc whereon the honey is +placed hardly upsets them. Further, wasps have a better sense of smell +than bees. + +The chief discovery regarding the vision of insects made in the last +thirty years is that of Lubbock, who proved that ants perceive the +ultra-violet rays of the spectrum, which we are unable, or almost +unable, to perceive. + +It has lately been proved also that many insects appreciate light by the +skin. + +They do not see as clearly as we do; but when they possess +well-developed compound eyes they appreciate size, and more or less +distinctly the contours of objects. + +Ants have a great faculty for recognition, which probably testifies to +their vision and visual memory. Lubbock observed ants which actually +recognised each other after more than a year of separation. + + +_III.--Smell, Taste, Hearing, Pain_ + +Smell is very important in insects. It is difficult for us to judge of, +since man is of all the vertebrates except the whales, perhaps, the one +in which this sense is most rudimentary. We can evidently, therefore, +form only a feeble idea of the world of knowledge imparted by a smell to +a dog, a mole, a hedgehog, or an insect. The instruments of smell are +the antennæ. A poor ant without antennæ is as lost as a blind man who is +also deaf and dumb. This appears from its complete social inactivity, +its isolation, its incapacity to guide itself and to find its food. It +can, therefore, be boldly supposed that the antennæ and their power of +smell, as much on contact as at a distance, constitute the social sense +of ants, the sense which allows them to recognise one another, to tend +to their larvæ, and mutually help one another, and also the sense which +awakens their greedy appetites, their violent hatred for every being +foreign to the colony, the sense which principally guides them--a little +helped by vision, especially in certain species--in the long and patient +travels which they have to undertake, which makes them find their way +back, find their plant-lice, and all their other means of subsistence. + +As the philosopher Herbert Spencer has well pointed out, the visceral +sensations of man, and those internal senses which, like smell, can only +make an impression of one kind as regards space--two simultaneous odours +can only be appreciated by us as a mixture--are precisely those by which +we can gain little or no information relative to space. Our vision, on +the contrary, which localises the rays from various distant points of +space on various distinct points of our retina at the same time, is our +most relational sense, that which gives us the most vast ideas of space. + +But the antennæ of insects are an olfactory organ turned inside out, +prominent in space, and, further, very mobile. This allows us to suppose +that the sense of smell may be much more relational than ours, that the +sensations thence derived give them ideas of space and of direction +which may be qualitatively different from ours. + +Taste exists in insects, and has been very widely written on, but +somewhat inconclusively. The organs of taste probably are to be found in +the jaws and at the base of the tongue. This sense can be observed in +ants, bees, and wasps; and everyone has seen how caterpillars especially +recognise by taste the plants which suit them. + +Much has been written on the hearing of insects; but, in my judgment, +only crickets and several other insects of that class appear to perceive +sounds. Erroneous views have been due to confusing hearing with +mechanical vibrations. + +We must not forget that the specialisation of the organ of hearing has +reached in man a delicacy of detail which is evidently not found again +in lower vertebrates. + +Pain is much less developed in insects than in warm-blooded vertebrates. +Otherwise, one could not see either an ant, with its abdomen or antennæ +cut off, gorge itself with honey; or a humble-bee, in which the antennæ +and all the front of the head had been removed, go to find and pillage +flowers; or a spider, the foot of which had been broken, feed +immediately on this, its own foot, as I myself have seen; or, finally, a +caterpillar, wounded at the "tail" end, devour itself, beginning behind, +as I have observed more than once. + + +_IV.--Insect Reason and Passions_ + +Insects reason, and the most intelligent among them, the social +hymenoptera, especially the wasps and ants, even reason much more than +one is tempted to believe when one observes the regularly recurring +mechanism of their instincts. To observe and understand these +reasonings well, it is necessary to mislead their instinct. Further, one +may remark little bursts of plastic judgment, of combinations--extremely +limited, it is true--which, in forcing them an instant from the beaten +track of their automatism, help them to overcome difficulties, and to +decide between two dangers. From the point of view of instinct and +intelligence, or rather of reason, there are not, therefore, absolute +contrasts between the insect, the mammal, and the man. + +Finally, insects have passions which are more or less bound up with +their instincts. And these passions vary enormously, according to the +species. I have noted the following passions or traits of character +among ants: choler, hatred, devotion, activity, perseverance, and +gluttony. I have added thereto the discouragement which is sometimes +shown in a striking manner at the time of a defeat, and which can become +real despair; the fear which is shown among ants when they are alone, +while it disappears when they are numerous. I can add further the +momentary temerity whereby certain ants, knowing the enemy to be +weakened and discouraged, hurl themselves alone in the midst of the +black masses of enemies larger than themselves, hustling them without +taking the least further precaution. + +When we study the manners of an insect, it is necessary for us to take +account of its mental faculties as well as of its sense organs. +Intelligent insects make better use of their senses, especially by +combining them in various ways. It is possible to study such insects in +their homes in a more varied and more complete manner, allowing greater +accuracy of observations. + + + + +GALILEO + +Dialogues on the System of the World + + Galileo Galilei, famous as an astronomer and as an experimental + physicist, was born at Pisa, in Italy, Feb. 18, 1564. His talents + were most multifarious and remarkable; but his mathematical and + mechanical genius was dominant from the first. As a child he + constructed mechanical toys, and as a young man he made one of his + most important discoveries, which was that of the pendulum as an + agent in the measurement of time, and invented the hydrostatic + balance, by which the specific gravity of solid bodies might be + ascertained. At the age of 24 a learned treatise on the centre of + gravity of solids led to a lectureship at Pisa University. Driven + from Pisa by the enmity of Aristotelians, he went to Padua + University, where he invented a kind of thermometer, a proportional + compass, a microscope, and a telescope. The last invention bore + fruit in astronomical discoveries, and in 1610 he discovered four + of the moons of Jupiter. His promulgation of the Copernican + doctrine led to renewed attacks by the Aristotelians, and to + censure by the Inquisition. (See Religion, vol. xiii.) + Notwithstanding this censure, he published in 1632 his "Dialogues + on the System of the World." The interlocutors in the "Dialogues," + with the exception of Salviatus, who expounds the views of the + author himself, represent two of Galileo's early friends. For the + "Dialogues" he was sentenced by the Inquisition to incarceration at + its pleasure, and enjoined to recite penitential psalms once a week + for three years. His life thereafter was full of sorrow, and in + 1637 blindness added to his woes; but the fire of his genius still + burnt on till his death on January 8, 1642. + + +_Does the Earth Move_ + +SALVIATUS: Now, let Simplicius propound those doubts which dissuade him +from believing that the earth may move, as the other planets, round a +fixed centre. + +SIMPLICIUS: The first and greatest difficulty is that it is impossible +both to be in a centre and to be far from it. If the earth move in a +circle it cannot remain in the centre of the zodiac; but Aristotle, +Ptolemy and others have proved that it is in the centre of the zodiac. + +SALVIATUS: There is no question that the earth cannot be in the centre +of a circle round whose circumference it moves. But tell me what centre +do you mean? + +SIMPLICIUS: I mean the centre of the universe, of the whole world, of +the starry sphere. + +SALVIATUS: No one has ever proved that the universe is finite and +figurative; but granting that it is finite and spherical, and has +therefore a centre, we have still to give reasons why we should believe +that the earth is at its centre. + +SIMPLICIUS: Aristotle has proved in a hundred ways that the universe is +finite and spherical. + +SALVIATUS: Aristotle's proof that the universe was finite and spherical +was derived essentially from the consideration that it moved; and seeing +that centre and figure were inferred by Aristotle from its mobility, it +will be reasonable if we endeavour to find from the circular motions of +mundane bodies the centre's proper place. Aristotle himself came to the +conclusion that all the celestial spheres revolve round the earth, which +is placed at the centre of the universe. But tell me, Simplicius, +supposing Aristotle found that one of the two propositions must be +false, and that either the celestial spheres do not revolve or that the +earth is not the centre round which they revolve, which proposition +would he prefer to give up? + +SIMPLICIUS: I believe that the Peripatetics---- + +SALVIATUS: I do not ask the Peripatetics, I ask Aristotle. As for the +Peripatetics, they, as humble vassals of Aristotle, would deny all the +experiments and all the observations in the world; nay, would also +refuse to see them, and would say that the universe is as Aristotle +writeth, and not as Nature will have it; for, deprived of the shield of +his authority, with what do you think they would appear in the field? +Tell me, therefore, what Aristotle himself would do. + +SIMPLICIUS: To tell you the truth, I do not know how to decide which is +the lesser inconvenience. + +SALVIATUS: Seeing you do not know, let us examine which would be the +more rational choice, and let us assume that Aristotle would have chosen +so. Granting with Aristotle that the universe has a spherical figure and +moveth circularly round a centre, it is reasonable to believe that the +starry orbs move round the centre of the universe or round some separate +centre? + +SIMPLICIUS: I would say that it were much more reasonable to believe +that they move with the universe round the centre of the universe. + +SALVIATUS: But they move round the sun and not round the earth; +therefore the sun and not the earth is the centre of the universe. + +SIMPLICIUS: Whence, then, do you argue that it is the sun and not the +earth that is the centre of the planetary revolutions? + +SALVIATUS: I infer that the earth is not the centre of the planetary +revolutions because the planets are at different times at very different +distances from the earth. For instance, Venus, when it is farthest off, +is six times more remote from us than when it is nearest, and Mars rises +almost eight times as high at one time as at another. + +SIMPLICIUS: And what are the signs that the planets revolve round the +sun as centre? + +SALVIATUS: We find that the three superior planets--Mars, Jupiter, and +Saturn--are always nearest to the earth when they are in opposition to +the sun, and always farthest off when they are in conjunction; and so +great is this approximation and recession that Mars, when near, appears +very nearly sixty times greater than when remote. Venus and Mercury also +certainly revolve round the sun, since they never move far from it, and +appear now above and now below it. + +SAGREDUS: I expect that more wonderful things depend on the annual +revolution than upon the diurnal rotation of the earth. + +SALVIATUS: YOU do not err therein. The effect of the diurnal rotation of +the earth is to make the universe seem to rotate in the opposite +direction; but the annual motion complicates the particular motions of +all the planets. But to return to my proposition. I affirm that the +centre of the celestial convolutions of the five planets--Saturn, +Jupiter, Mars, Venus, and Mercury, and likewise of the earth--is the +sun. + +As for the moon, it goes round the earth, and yet does not cease to go +round the sun with the earth. It being true, then, that the five planets +do move about the sun as a centre, rest seems with so much more reason +to belong to the said sun than to the earth, inasmuch as in a movable +sphere it is more reasonable that the centre stand still than any place +remote from the centre. + +To the earth, therefore, may a yearly revolution be assigned, leaving +the sun at rest. And if that be so, it follows that the diurnal motion +likewise belongs to the earth; for if the sun stood still and the earth +did not rotate, the year would consist of six months of day and six +months of night. You may consider, likewise, how, in conformity with +this scheme, the precipitate motion of twenty-four hours is taken away +from the universe; and how the fixed stars, which are so many suns, are +made, like our sun, to enjoy perpetual rest. + +SAGREDUS: The scheme is simple and satisfactory; but, tell me, how is it +that Pythagoras and Copernicus, who first brought it forward, could make +so few converts? + +SALVIATUS: If you know what frivolous reasons serve to make the vulgar, +contumacious and indisposed to hearken, you would not wonder at the +paucity of converts. The number of thick skulls is infinite, and we need +neither record their follies nor endeavour to interest them in subtle +and sublime ideas. No demonstrations can enlighten stupid brains. + +My wonder, Sagredus, is different from yours. You wonder that so few are +believers in the Pythagorean hypothesis; I wonder that there are any to +embrace it. Nor can I sufficiently admire the super-eminence of those +men's wits that have received and held it to be true, and with the +sprightliness of their judgments have offered such violence to their +senses that they have been able to prefer that which their reason +asserted to that which sensible experience manifested. I cannot find any +bounds for my admiration how that reason was able, in Aristarchus and +Copernicus, to commit such a rape upon their senses, as in despite +thereof to make herself mistress of their credulity. + +SAGREDUS: Will there still be strong opposition to the Copernican +system? + +SALVIATUS: Undoubtedly; for there are evident and sensible facts to +oppose it, requiring a sense more sublime than the common and vulgar +senses to assist reason. + +SAGREDUS: Let us, then, join battle with those antagonistic facts. + +SALVIATUS: I am ready. In the first place, Mars himself charges hotly +against the truth of the Copernican system. According to the Copernican +system, that planet should appear sixty times as large when at its +nearest as when at its farthest; but this diversity of magnitude is not +to be seen. The same difficulty is seen in the case of Venus. Further, +if Venus be dark, and shine only with reflected light, like the moon, it +should show lunar phases; but these do not appear. + +Further, again, the moon prevents the whole order of the Copernican +system by revolving round the earth instead of round the sun. And there +are other serious and curious difficulties admitted by Copernicus +himself. But even the three great difficulties I have named are not +real. As a matter of fact, Mars and Venus do vary in magnitude as +required by theory, and Venus does change its shape exactly like the +moon. + +SAGREDUS: But how came this to be concealed from Copernicus and revealed +to you? + + + + +SIR FRANCIS GALTON + +Essays in Eugenics + + Sir Francis Galton, born at Birmingham, England, in 1822, was a + grandson of Dr. Erasmus Darwin. He graduated from Trinity College, + Cambridge, in 1844. Galton travelled in the north of Africa, on the + White Nile and in the western portion of South Africa between 1844 + and 1850. Like his immortal cousin, Charles Darwin, Sir Francis + Galton is a striking instance of a man of great and splendid + inheritance, who, also inheriting wealth, devotes it and his powers + to the cause of humanity. He published several books on heredity, + the first of which was "Hereditary Genius." The next "Inquiries + into Human Faculty," which was followed by "Natural Inheritance." + The "Essays in Eugenics" include all the most recent work of Sir + Francis Galton since his return to the subject of eugenics in 1901. + This volume has just been published by the Eugenics Education + Society, of which Sir Francis Galton is the honorary president. As + epitomised for this work, the "Essays" have been made to include a + still later study by the author, which will be included in future + editions of the book. The epitome has been prepared by special + permission of the Eugenics Education Society, and those responsible + hope that it will serve in some measure to neutralise the + outrageous, gross, and often wilful misrepresentations of eugenics + of which many popular writers are guilty. + + +_I.--The Aims and Methods of Eugenics_ + +The following essays help to show something of the progress of eugenics +during the last few years, and to explain my own views upon its aims and +methods, which often have been, and still sometimes are, absurdly +misrepresented. The practice of eugenics has already obtained a +considerable hold on popular estimation, and is steadily acquiring the +status of a practical question, and not that of a mere vision in Utopia. + +The power by which eugenic reform must chiefly be effected is that of +public opinion, which is amply strong enough for that purpose whenever +it shall be roused. Public opinion has done as much as this on many past +occasions and in various countries, of which much evidence is given in +the essay on restrictions in marriage. It is now ordering our acts more +intimately than we are apt to suspect, because the dictates of public +opinion become so thoroughly assimilated that they seem to be the +original and individual to those who are guided by them. By comparing +the current ideas at widely different epochs and under widely different +civilisations, we are able to ascertain what part of our convictions is +really innate and permanent, and what part has been acquired and is +transient. + +It is, above all things, needful for the successful progress of eugenics +that its advocates should move discreetly and claim no more efficacy on +its behalf than the future will justify; otherwise a reaction will be +justified. A great deal of investigation is still needed to show the +limit of practical eugenics, yet enough has been already determined to +justify large efforts being made to instruct the public in an +authoritative way, with the results hitherto obtained by sound +reasoning, applied to the undoubted facts of social experience. + +The word "eugenics" was coined and used by me in my book "Human +Faculty," published as long ago as 1883. In it I emphasised the +essential brotherhood of mankind, heredity being to my mind a very real +thing; also the belief that we are born to act, and not to wait for help +like able-bodied idlers, whining for doles. Individuals appear to me as +finite detachments from an infinite ocean of being, temporarily endowed +with executive powers. This is the only answer I can give to myself in +reply to the perpetually recurring questions of "why? whence? and +whither?" The immediate "whither?" does not seem wholly dark, as some +little information may be gleaned concerning the direction in which +Nature, so far as we know of it, is now moving--namely, towards the +evolution of mind, body, and character in increasing energy and +co-adaptation. + +The ideas have long held my fancy that we men may be the chief, and +perhaps the only executives on earth; that we are detached on active +service with, it may be only illusory, powers of free-will. Also that we +are in some way accountable for our success or failure to further +certain obscure ends, to be guessed as best we can; that though our +instructions are obscure they are sufficiently clear to justify our +interference with the pitiless course of Nature whenever it seems +possible to attain the goal towards which it moves by gentler and +kindlier ways. + +There are many questions which must be studied if we are to be guided +aright towards the possible improvement of mankind under the existing +conditions of law and sentiment. We must study human variety, and the +distribution of qualities in a nation. We must compare the +classification of a population according to social status with the +classification which we would make purely in terms of natural quality. +We must study with the utmost care the descent of qualities in a +population, and the consequences of that marked tendency to marriage +within the class which distinguishes all classes. Something is to be +learnt from the results of examinations in universities and colleges. + +It is desirable to study the degree of correspondence that may exist +between promise in youth, as shown in examinations, and subsequent +performance. Let me add that I think the neglect of this inquiry by the +vast army of highly educated persons who are connected with the present +huge system of competitive examination to be gross and unpardonable. +Until this problem is solved we cannot possibly estimate the value of +the present elaborate system of examinations. + + +_II.--Restrictions in Marriage_ + +It is necessary to meet an objection that has been repeatedly urged +against the possible adoption of any system of eugenics, namely, that +human nature would never brook interference with the freedom of +marriage. But the question is how far have marriage restrictions proved +effective when sanctified by the religion of the time, by custom, and by +law. I appeal from armchair criticism to historical facts. It will be +found that, with scant exceptions, marriage customs are based on social +expediency and not on natural instincts. This we learn when we study the +fact of monogamy, and the severe prohibition of polygamy, in many times +and places, due not to any natural instinct against the practice, but to +consideration of the social well-being. We find the same when we study +endogamy, exogamy, Australian marriages, and the control of marriage by +taboo. + +The institution of marriage, as now sanctified by religion and +safeguarded by law in the more highly civilised nations, may not be +ideally perfect, nor may it be universally accepted in future times, but +it is the best that has hitherto been devised for the parties primarily +concerned, for their children, for home life, and for society. The +degree of kinship within which marriage is prohibited is, with one +exception, quite in accordance with modern sentiment, the exception +being the disallowal of marriage with the sister of a deceased wife, the +propriety of which is greatly disputed and need not be discussed here. +The marriage of a brother and sister would excite a feeling of loathing +among us that seems implanted by nature, but which, further inquiry will +show, has mainly arisen from tradition and custom. + +The evidence proves that there is no instinctive repugnance felt +universally by man to marriage within the prohibited degrees, but that +its present strength is mainly due to what I may call immaterial +considerations. It is quite conceivable that a non-eugenic marriage +should hereafter excite no less loathing than that of a brother and +sister would do now. + +The dictates of religion in respect to the opposite duties of leading +celibate lives, and of continuing families, have been contradictory. In +many nations it is and has been considered a disgrace to bear no +children, and in other nations celibacy has been raised to the rank of a +virtue of the highest order. During the fifty or so generations that +have elapsed since the establishment of Christianity, the nunneries and +monasteries, and the celibate lives of Catholic priests, have had vast +social effects, how far for good and how far for evil need not be +discussed here. The point I wish to enforce is the potency, not only of +the religious sense in aiding or deterring marriage, but more especially +the influence and authority of ministers of religion in enforcing +celibacy. They have notoriously used it when aid has been invoked by +members of the family on grounds that are not religious at all, but +merely of family expediency. Thus at some times and in some Christian +nations, every girl who did not marry while still young was practically +compelled to enter a nunnery, from which escape was afterwards +impossible. + +It is easy to let the imagination run wild on the supposition of a +whole-hearted acceptance of eugenics as a national religion; that is, of +the thorough conviction by a nation that no worthier object exists for +man than the improvement of his own race, and when efforts as great as +those by which nunneries and monasteries were endowed and maintained +should be directed to fulfil an opposite purpose. I will not enter +further into this. Suffice it to say, that the history of conventual +life affords abundant evidence on a very large scale of the power of +religious authority in directing and withstanding the tendencies of +human nature towards freedom in marriage. + +Seven different forms of marriage restriction may be cited to show what +is possible. They are monogamy, endogamy, exogamy, Australian marriages, +taboo, prohibited degrees, and celibacy. It can be shown under each of +these heads how powerful are the various combinations of immaterial +motives upon marriage selection, how they may all become hallowed by +religion, accepted as custom, and enforced by law. Persons who are born +under their various rules live under them without any objection. They +are unconscious of their restrictions, as we are unaware of the tension +of the atmosphere. The subservience of civilised races to their several +religious superstitions, customs, authority, and the rest, is frequently +as abject as that of barbarians. + +The same classes of motives that direct other races direct ours; so a +knowledge of their customs helps us to realise the wide range of what we +may ourselves hereafter adopt, for reasons as satisfactory to us in +those future times, as theirs are or were to them at the time when they +prevailed. + + +_III.--Eugenic Qualities of Primary Importance_ + +The following is offered as a contribution to the art of justly +appraising the eugenic values of different qualities. It may fairly be +assumed that the presence of certain inborn traits is requisite before a +claim to eugenic rank can be justified, because these qualities are +needed to bring out the full values of such special faculties as broadly +distinguish philosophers, artists, financiers, soldiers, and other +representative classes. The method adopted for discovering the qualities +in question is to consider groups of individuals, and to compare the +qualities that distinguish such groups as flourish or prosper from +others of the same kind that decline or decay. This method has the +advantage of giving results more free from the possibility of bias than +those derived from examples of individual cases. + +In what follows I shall use the word "community" in its widest sense, +as including any group of persons who are connected by a common +interest--families, schools, clubs, sects, municipalities, nations, and +all intermediate social units. Whatever qualities increase the +prosperity of most or every one of these, will, as I hold, deserve a +place in the first rank of eugenic importance. + +Most of us have experience, either by direct observation or through +historical reading, of the working of several communities, and are +capable of forming a correct picture in our minds of the salient +characteristics of those that, on the one hand, are eminently +prosperous, and of those that, on the other hand, are as eminently +decadent. I have little doubt that the reader will agree with me that +the members of prospering communities are, as a rule, conspicuously +strenuous, and that those of decaying or decadent ones are conspicuously +slack. A prosperous community is distinguished by the alertness of its +members, by their busy occupations, by their taking pleasure in their +work, by their doing it thoroughly, and by an honest pride in their +community as a whole. The members of a decaying community are, for the +most part, languid and indolent; their very gestures are dawdling and +slouching, the opposite of smart. They shirk work when they can do so, +and scamp what they undertake. A prosperous community is remarkable for +the variety of the solid interests in which some or other of its members +are eagerly engaged, but the questions that agitate a decadent community +are for the most part of a frivolous order. + +Prosperous communities are also notable for enjoyment of life; for +though their members must work hard in order to procure the necessary +luxuries of an advanced civilisation, they are endowed with so large a +store of energy that, when their daily toil is over, enough of it +remains unexpended to allow them to pursue their special hobbies during +the remainder of the day. In a decadent community the men tire easily, +and soon sink into drudgery; there is consequently much languor among +them, and little enjoyment of life. + +I have studied the causes of civic prosperity in various directions and +from many points of view, and the conclusion at which I have arrived is +emphatic, namely, that chief among those causes is a large capacity for +labour--mental, bodily, or both--combined with eagerness for work. The +course of evolution in animals shows that this view is correct in +general. The huge lizards, incapable of rapid action, unless it be brief +in duration and associated with long terms of repose, have been +supplanted by birds and mammals possessed of powers of long endurance. +These latter are so constituted as to require work, becoming restless +and suffering in health when precluded from exertion. + +We must not, however, overlook the fact that the influence of +circumstance on a community is a powerful factor in raising its tone. A +cause that catches the popular feeling will often rouse a potentially +capable nation from apathy into action. A good officer, backed by +adequate supplies of food and with funds for the regular payment of his +troops, will change a regiment even of ill-developed louts and hooligans +into a fairly smart and well-disciplined corps. But with better material +as a foundation, the influence of a favourable environment is +correspondingly increased, and is less liable to impairment whenever the +environment changes and becomes less propitious. Hence, it follows that +a sound mind and body, enlightened, I should add, with an intelligence +above the average, and combined with a natural capacity and zeal for +work, are essential elements in eugenics. For however famous a man may +become in other respects, he cannot, I think, be justly termed eugenic +if deficient in the qualities I have just named. + +Eugenists justly claim to be true philanthropists, or lovers of mankind, +and should bestir themselves in their special province as eagerly as +the philanthropists, in the current and very restricted meaning of that +word, have done in theirs. They should interest themselves in such +families of civic worth as they come across, especially in those that +are large, making friends both with the parents and the children, and +showing themselves disposed to help to a reasonable degree, as +opportunity may offer, whenever help is really needful. They should +compare their own notes with those of others who are similarly engaged. +They should regard such families as an eager horticulturist regards beds +of seedlings of some rare variety of plant, but with an enthusiasm of a +far more patriotic kind. For, since it has been shown that about 10 per +cent. of the individuals born in one generation provide half the next +generation, large families that are also eugenic may prove of primary +importance to the nation and become its most valuable asset. + + +_IV.--Practical Eugenics_ + +The following are some views of my own relating to that large province +of eugenics which is concerned with favouring the families of those who +are exceptionally fit for citizenship. Consequently, little or nothing +will here be said relating to what has been well termed by Dr. Saleeby +"negative" eugenics, namely, the hindrance of the marriages and the +production of offspring by the exceptionally unfit. The latter is +unquestionably the more pressing subject, but it will soon be forced on +the attention of the legislature by the recent report of the Royal +Commission on the Feeble-minded. + +Whatever scheme of action is proposed for adoption must be neither +Utopian nor extravagant, but accordant throughout with British sentiment +and practice. + +By "worth" I mean the civic worthiness, or the value to the state, of a +person. Speaking only for myself, if I had to classify persons according +to worth, I should consider each of them under the three heads of +physique, ability and character, subject to the provision that +inferiority in any one of the three should outweigh superiority in the +other two. I rank physique first, because it is not only very valuable +in itself and allied to many other good qualities, but has the +additional merit of being easily rated. Ability I place second on +similar grounds, and character third, though in real importance it +stands first of all. + +The power of social opinion is apt to be underrated rather than +overrated. Like the atmosphere which we breathe and in which we move, +social opinion operates powerfully without our being conscious of its +weight. Everyone knows that governments, manners, and beliefs which were +thought to be right, decorous, and true at one period have been judged +wrong, indecorous, and false at another; and that views which we have +heard expressed by those in authority over us in early life tend to +become axiomatic and unchangeable in mature life. + +In circumscribed communities especially, social approval and disapproval +exert a potent force. Is it, then, I ask, too much to expect that when a +public opinion in favour of eugenics has once taken sure hold of such +communities, the result will be manifested in sundry and very effective +modes of action which are as yet untried? + +Speaking for myself only, I look forward to local eugenic action in +numerous directions, of which I will now specify one. It is the +accumulation of considerable funds to start young couples of "worthy" +qualities in their married life, and to assist them and their families +at critical times. The charitable gifts to those who are the reverse of +"worthy" are enormous in amount. I am not prepared to say how much of +this is judiciously spent, or in what ways, but merely quote the fact to +justify the inference that many persons who are willing to give freely +at the prompting of a sentiment based upon compassion might be +persuaded to give largely also in response to the more virile desire of +promoting the natural gifts and the national efficiency of future +generations. + + +_V.--Eugenics as a Factor in Religion_ + +Eugenics strengthen the sense of social duty in so many important +particulars that the conclusions derived from its study ought to find a +welcome home in every tolerant religion. It promotes a far-sighted +philanthropy, the acceptance of parentage as a serious responsibility, +and a higher conception of patriotism. The creed of eugenics is founded +upon the idea of evolution; not on a passive form of it, but on one that +can, to some extent, direct its own course. + +Purely passive, or what may be styled mechanical evolution displays the +awe-inspiring spectacle of a vast eddy of organic turmoil, originating +we know not how, and travelling we know not whither. It forms a +continuous whole, but it is moulded by blind and wasteful +processes--namely, by an extravagant production of raw material and the +ruthless rejection of all that is superfluous, through the blundering +steps of trial and error. + +The condition at each successive moment of this huge system, as it +issues from the already quiet past and is about to invade the still +undisturbed future, is one of violent internal commotion. Its elements +are in constant flux and change. + +Evolution is in any case a grand phantasmagoria, but it assumes an +infinitely more interesting aspect under the knowledge that the +intelligent action of the human will is, in some small measure, capable +of guiding its course. Man has the power of doing this largely so far as +the evolution of humanity is concerned; he has already affected the +quality and distribution of organic life so widely that the changes on +the surface of the earth, merely through his disforestings and +agriculture, would be recognisable from a distance as great as that of +the moon. + +As regards the practical side of eugenics, we need not linger to reopen +the unending argument whether man possesses any creative power of will +at all, or whether his will is not also predetermined by blind forces or +by intelligent agencies behind the veil, and whether the belief that man +can act independently is more than a mere illusion. + +Eugenic belief extends the function of philanthropy to future +generations; it renders its action more pervading than hitherto, by +dealing with families and societies in their entirety, and it enforces +the importance of the marriage covenant by directing serious attention +to the probable quality of the future offspring. It sternly forbids all +forms of sentimental charity that are harmful to the race, while it +eagerly seeks opportunity for acts of personal kindness. It strongly +encourages love and interest in family and race. In brief, eugenics is a +virile creed, full of hopefulness, and appealing to many of the noblest +feelings of our nature. + + + + +ERNST HAECKEL + +The Evolution of Man + + Ernst Haeckel, who was born in Potsdam, Germany, Feb. 16, 1834, + descends from a long line of lawyers and politicians. To his + father's annoyance, he turned to science, and graduated in + medicine. After a long tour in Italy in 1859, during which he + wavered between art and science, he decided for zoology, and made a + masterly study of a little-known group of sea-animalcules, the + Radiolaria. In 1861 he began to teach zoology at Jena University. + Darwin's "Origin of Species" had just been translated into German, + and he took up the defence of Darwinism against almost the whole of + his colleagues. His first large work on evolution, "General + Morphology," was published in 1866. He has since published + forty-two distinct works. He is not only a master of zoology, but + has a good command of botany and embryology. Haeckel's "Evolution + of Man" (Anthropogenie), is generally accepted as being his most + important production. Published in 1874, at a time when the theory + of natural evolution had few supporters in Germany, the work was + hailed with a storm of controversy, one celebrated critic declaring + that it was a blot on the escutcheon of Germany. From the hands of + English scientists, however, the treatise received a warm welcome. + Darwin said he would probably never have written his "Descent of + Man" had Haeckel published his work earlier. + + +_I.--The Science of Man_ + +The natural history of mankind, or anthropology, must always excite the +most lively interest, and no part of the science is more attractive than +that which deals with the question of man's origin. In order to study +this with full profit, we must combine the results of two sciences, +ontogeny (or embryology) and phylogeny (the science of evolution). We do +this because we have now discovered that the forms through which the +embryo passes in its development correspond roughly to the series of +forms in its ancestral development. The correspondence is by no means +complete or precise, since the embryonic life itself has been modified +in the course of time; but the general law is now very widely accepted. +I have called it "the biogenetic law," and will constantly appeal to it +in the course of this study. + +It is only in recent times that the two sciences have advanced +sufficiently to reveal the correspondence of the two series of forms. +Aristotle provided a good foundation for embryology, and made some +interesting discoveries, but no progress was made in the science for +2,000 years after him. Then the Reformation brought some liberty of +research, and in the seventeenth century several works were written on +embryology. + +For more than a hundred years the science was still hampered by the lack +of good microscopes. It was generally believed that all the organs of +the body existed, packed in a tiny point of space, in the germ. About +the middle of the eighteenth century, Caspar Friedrich Wolff discovered +the true development; but his work was ignored, and it was only fifty +years later that modern embryology began to work on the right line. K.E. +von Baer made it clear that the fertilised ovum divides into a group of +cells, and that the various organs of the body are developed from these +layers of cells, in the way I shall presently describe. + +The science of phylogeny, or, as it is popularly called, the evolution +of species, had an equally slow growth. On the ground of the Mosaic +narrative, no less than in view of the actual appearance of the living +world, the great naturalist Linné (1735) set up the dogma of the +unchangeability of species. Even when quite different remains of animals +were discovered by the advancing science of geology, they were forced +into the existing narrow framework of science by Cuvier. Sir Charles +Lyell completely undid the fallacious work of Cuvier, but in the +meantime the zoologists themselves were moving toward the doctrine of +evolution. + +Jean Lamarck made the first systematic attempt to expound the theory in +his "Zoological Philosophy" (1809). He suggested that animals modified +their organs by use or disuse, and that the effect of this was +inherited. In the course of time these inherited modifications reached +such a pitch that the organism fell into a new "species." Goethe also +made some remarkable contributions to the science of evolution. But it +was reserved for Charles Darwin to win an enduring place in science for +the theory. "The Origin of Species" (1859) not only sustained it with a +wealth of positive knowledge which Lamarck did not command, but it +provided a more luminous explanation in the doctrine of natural +selection. Huxley (1863) followed with an application of the law to man, +and in 1866 I gave a comprehensive sketch of its application throughout +the whole animal world. In 1874 I published the first edition of the +present work. + +The doctrine of evolution is now a vital part of biology, and we might +accept the evolution of man as a special deduction from the general law. +Three great groups of evidence impose that law on us. The first group +consists of the facts of palæontology, or the fossil record of past +animal life. Imperfect as the record is, it shows us a broad divergence +of successively changing types from a simple common root, and in some +cases exhibits the complete transition from one type to another. The +next document is the evidence of comparative anatomy. This science +groups the forms of living animals in such a way that we seem to have +the same gradual divergence of types from simple common ancestors. In +particular, it discovers certain rudimentary organs in the higher +animals, which can only be understood as the shrunken relics of organs +that were once useful to a remote ancestor. Thus, man has still the +rudiment of the third eyelid of his shark-ancestor. The third document +is the evidence of embryology, which shows us the higher organism +substantially reproducing, in its embryonic development, the long +series of ancestral forms. + + +_II.--Man's Embryonic Development_ + +The first stage in the development of any animal is the tiny speck of +plasm, hardly visible to the naked eye, which we call the ovum, or +egg-cell. It is a single cell, recalling the earliest single-celled +ancestor of all animals. In its immature form it is not unlike certain +microscopic animalcules known as _amoeboe_. In its mature form it is +about 1/125th of an inch in diameter. + +When the male germ has blended with the female in the ovum, the new cell +slowly divides into two, with a very complicated division of the +material composing its nucleus. The two cells divide into four, the four +into eight, and so on until we have a round cluster of cells, something +like a blackberry in shape. + +This _morula_, as I have called it, reproduces the next stage in the +development of life. As all animals pass through it, our biogenetic law +forces us to see in it an ancestral stage; and in point of fact we have +animals of this type living in Nature to-day. The round cluster becomes +filled with fluid, and we have a hollow sphere of cells, which I call +the _blastula_. The corresponding early ancestor I name the _Blastæa_, +and again we find examples of it, like the _Volvox_ of the ponds, in +Nature to-day. + +The next step is very important. The hollow sphere closes in on itself, +as when an india rubber ball is pressed into the form of a cup. We have +then a vase-shaped body with two layers of cells, an inner and an outer, +and an opening. The inner layer we call the entoderm, the outer the +ectoderm; and the "primitive mouth" is known as the blastopore. In the +higher animals a good deal of food-yolk is stored up in the germ, and so +the vase-shaped structure has been flattened and altered. It has, +however, been shown that all embryos pass through this stage +(gastrulation), and we again infer the existence of a common ancestor of +that type--the _Gastræa_. The lowest group of many-celled animals--the +corals, jelly-fishes, and anemones--are essentially of that structure. + +The embryo now consists of two layers of cells, the "germ-layers," an +inner and outer. As the higher embryo develops, a third layer of cells +now pushes between the two. We may say, broadly, that from this middle +layer are developed most of the animal organs of the body; from the +internal germ-layer is developed the lining of the alimentary canal and +its dependent glands; from the outer layer are formed the skin and the +nervous system--which developed originally in the skin. + +The embryo of man and all the other higher animals now develops a +cavity, a pair of pouches, by the folding of the layer at the primitive +mouth. Sir E. Ray Lankester, and Professor Balfour, and other students, +traced this formation through the whole embryonic world, and we are +therefore again obliged to see in it a reminiscence of an ancestral +form--a primitive worm-like animal, of a type we shall see later. The +next step is the formation of the first trace of what will ultimately be +the backbone. It consists at first of a membraneous tube, formed by the +folding of the inner layer along the axis of the embryo-body. Later this +tube will become cartilage, and in the higher animals the cartilage will +give place to bone. + +The other organs of the body now gradually form from the germ-layers, +principally by the folding of the layers into tubes. A light area +appears on the surface of the germ. A streak or groove forms along its +axis, and becomes the nerve-cord running along the back. Cube-shaped +structures make their appearance on either side of it; these prove to be +the rudiments of the vertebræ--or separate bones of the backbone--and +gradually close round the cord. The heart is at first merely a +spindle-shaped enlargement of the main ventral blood-vessel. The nose is +at first only a pair of depressions in the skin above the mouth. + +When the human embryo is only a quarter of an inch in length, it has +gill-clefts and gill-arches in the throat like a fish, and no limbs. The +heart--as yet with only the simple two-chambered structure of a fish's +heart--is up in the throat--as in the fish--and the principal arteries +run to the gill-slits. These structures never have any utility in man or +the other land-animals, though the embryo always has them for a time. +They point clearly to a fish ancestor. + +Later, they break up, the limbs sprout out like blunt fins at the sides, +and the long tail begins to decrease. By the twelfth week the human +frame is perfectly formed, though less than two inches long. Last of +all, it retains its resemblance to the ape. In the embryonic apparatus, +too, man closely resembles the higher ape. + + +_III.--Our Ancestral Tree_ + +The series of forms which we thus trace in man's embryonic development +corresponds to the ancestral series which we would assign to man on the +evidence of palæontology and comparative anatomy. At one time, the +tracing of this ancestral series encountered a very serious check. When +we examined the groups of living animals, we found none that illustrated +or explained the passage from the non-backboned--invertebrate--to the +backboned--vertebrate--animals. This gap was filled some years ago by +the discovery of the lancelet--_Amphioxus_--and the young of the +sea-squirt--_Ascidia_. The lancelet has a slender rod of cartilage along +its back, and corresponds very closely with the ideal I have sketched of +our primitive backboned ancestor. It may be an offshoot from the same +group. The sea-squirt further illustrates the origin of the backbone, +since it has a similar rod of cartilage in its youth, and loses it, by +degeneration, in its maturity. + +In this way the chief difficulty was overcome, and it was possible to +sketch the probable series of our ancestors. It must be well understood +that not only is the whole series conjectural, but no living animal must +be regarded as an ancestral form. The parental types have long been +extinct, and we may, at the most, use very conservative living types to +illustrate their nature, just as, in the matter of languages, German is +not the parent, but the cousin of Anglo-Saxon, or Greek of Latin. The +original parental languages are lost. But a language like Sanscrit +survives to give us a good idea of the type. + +The law of evolution is based on such a mass of evidence that we may +justly draw deductions from it, where the direct evidence is incomplete. +This is especially necessary in the early part of our ancestral tree, +because the fossil record quite fails us. For millions of years the +early soft-bodied animals left no trace in the primitive mud, which time +has hardened into rocks, and we are restricted to the evidence of +embryology and of comparative zoology. This suffices to give us a +general idea of the line of development. + +In nature to-day, one of the lowest animal forms is a tiny speck of +living plasm called the _amoeba_. We have still more elementary forms, +such as the minute particles which make up the bluish film on damp +rocks, but they are of a vegetal character, or below it. They give us +some idea of the very earliest forms of life; minute living particles, +with no organs, down to the ten-thousandth part of an inch in diameter. +The amoeba represents the lowest animal, and, as we saw, the ovum in +many cases resembles an amoeba. We therefore take some such one-celled +creature as our first animal ancestor. Taking food in at all parts of +its surface, having no permanent organs of locomotion, and reproducing +by merely splitting into two, it exhibits the lowest level of animal +life. + +The next step in development would be the clustering together of these +primitive microbes as they divided. This is actually the stage that +comes next in the development of the germ, and it is the next stage +upward in the existing animal world. We assume that these clusters of +microbes--or cells, as we will now call them--bent inward, as we saw the +embryo do, and became two-layered, cup-shaped organisms, with a hollow +interior (primitive stomach) and an aperture (primitive mouth). The +inner cells now do the work of digestion alone; the outer cells effect +locomotion, by means of lashes like oars, and are sensitive. This is, in +the main, the structure of the next great group of animals, the hydra, +coral, meduca, and anemone. They have remained at this level, though +they have developed, special organs for stinging their prey and bringing +the food into their mouths. + +Both zoology and the appearance of the embryo point to a worm-like +animal as the next stage. Constant swimming in the water would give the +animal a definite head, with special groups of nerve-cells, a definite +tail, and a two-sided or evenly-balanced body. + +We mean that those animals would be fittest to live, and multiply most, +which developed this organisation. Sense-organs would now appear in the +head, in the form of simple depressions, lined with sensitive cells, as +they do in the embryo; and a clump of nerve-cells within would represent +the primitive brain. In the vast and varied worm-group we find +illustrations of nearly every step in this process of evolution. + +The highest type of worm-like creature, the acorn-headed +worm--_Balanoglossus_--takes us an important step further. It has +gill-openings for breathing, and a cord of cartilage down its back. We +saw that the human embryo has a gill-apparatus, and that, comparing the +lancelet and the sea-squirt, the backbone must have begun as a string of +cartilage-cells. We are now on firmer ground, for there is no doubt that +all the higher land-animals come from a fish ancestor. The shark, one of +the most primitive of fishes in organisation, probably best suggests +this ancestor to us. In fact, in the embryonic development of the human +face there is a clear suggestion of the shark. + +Up to this period the story of evolution had run its course in the sea. +The area of dry land was now increasing, and certain of the primitive +fishes adapted themselves to living on land. They walked on their fins, +and used their floating-bladders--large air-bladders in the fish, for +rising in the water--to breathe air. We not only have fishes of this +type in Australia to-day, but we have the fossil remains of similar +fishes in the Old Red Sandstone rocks. From mud-fish the amphibian would +naturally develop, as it did in the coal-forest period. Walking on the +fins would strengthen the main stem, the broad paddle would become +useless, and we should get in time the bony five-toed limb. We have many +of these giant salamander forms in the rocks. + +The reptile now evolved from the amphibian, and a vast reptile +population spread over the earth. From one of these early reptiles the +birds were evolved. Geology furnishes the missing link between the bird +and the reptile in the _Archæopteryx_, a bird with teeth, claws on its +wings, and a reptilian tail. From another primitive reptile the +important group of the mammals was evolved. We find what seem to be the +transitional types in the rocks of South Africa. The scales gave way to +tufts of hair, the heart evolved a fourth chamber, and thus supplied +purer blood (warm blood), the brain profited by the richer food, and the +mother began to suckle the young. We have still a primitive mammal of +this type in the duck-mole, or duck-billed platypus (_Ornithorhyncus_) +of Australia. There are grounds for thinking that the next stage was an +opossum-like animal, and this led on to the lowest ape-like being, the +lemur. Judging from the fossil remains, the black lemur of Madagascar +best suggests this ancestor. + +The apes of the Old and New Worlds now diverged from this level, and +some branch of the former gave rise to the man-like apes and man. In +bodily structure and embryonic development the large apes come very +close to man, and two recent discoveries have put their +blood-relationship beyond question. One is that experiments in the +transfusion of blood show that the blood of the man-like ape and man +have the same action on the blood of lower animals. The other is that we +have discovered, in Java, several bones of a being which stands just +midway between the highest living ape and lowest living race of men. +This ape-man (_Pithecanthropus_) represents the last of our animal and +first of our human ancestors. + + +_IV.--Evolution of Separate Organs_ + +So far, we have seen how the human body as a whole develops through a +long series of extinct ancestors. We may now take the various systems of +organs one by one, and, if we are careful to consult embryology as well +as zoology, we can trace the manner of their development. It is, in +accordance with our biogenetic law, the same in the embryo, as a rule, +as in the story of past evolution. + +We take first the nervous system. In the lowest animals, as in the early +stages of the embryo, there are no nerve-cells. In the embryo the +nerve-cells develop from the outer, or skin layer, of cells. This, +though strange as regards the human nervous system, is a correct +preservation of the primitive seat of the nerves. It was the surface of +the animal that needed to be sensitive in the primitive organism. Later, +when definite connecting nerves were formed, only special points in the +surface, protected by coverings which did not interfere with the +sensitiveness, needed to be exposed, and the nerves transmitted the +impressions to the central brain. + +This development is found in the animal world to-day. In such animals as +the hydra we find the first crude beginning of unorganised nerve-cells. +In the jelly-fish we find nerve-cells clustered into definite sensitive +organs. In the lower worms we have the beginning of organs of smell and +vision. They are at first merely blind, sensitive pits in the skin, as +in the embryo. The ear has a peculiar origin. Up to the fish level there +is no power of hearing. There is merely a little stone rolling in a +sensitive bed, to warn the animal of its movement from side to side. In +the higher animals this evolves into the ear. + +The glands of the skin (sweat, fat, tears, etc.) appear at first as +blunt, simple ingrowths. The hair first appears in tufts, representing +the scales, from underneath which they were probably evolved. The thin +coat of hair on the human body to-day is an ancestral inheritance. This +is well shown by the direction of the hairs on the arm. As on the ape's +arm, both on the upper and lower arm, they grow toward the elbow. The +ape finds this useful in rain, using his arms like a thatched roof, and +on our arm this can only be a reminiscence of the habits of an ape +ancestor. + +We have seen how the spinal cord first appears as a tube in the axis of +the back, and the cartilaginous column closes round it. All bone appears +first as membrane, then cartilage, and finally ossifies. This is the +order both in past evolution and in present embryonic development. The +brain is at first a bulbous expansion of the spinal nerve-cord. It is at +first simple, but gradually, both in the scale of nature and in the +embryo, divides into five parts. One of these parts, the cerebrum, is +mainly connected with mental life. We find it increasing in size, in +proportion to the animal's intelligence, until in man it comes to cover +the whole of the brain. When we remove it from the head of the mammal, +without killing the animal, we find all mental life suspended, and the +whole vitality used in vegetative functions. + +In the evolution of the bony system we find the same correspondence of +embryology and evolution. The main column is at first a rod of +cartilage. In time the separate cubes appear which are to form the +vertebræ of the flexible column. The skull develops in the same way. +Just as the brain is a specially modified part of the nerve-rod, the +skull is only a modified part of the vertebral column. The bones that +compose it are modified vertebræ, as Goethe long ago suspected. The +skull of the shark gives us a hint of the way in which the modification +took place, and the formation of the skull in the embryo confirms it. + +That adult man is devoid of that prolongation of the vertebral column +which we call a tail is not a distinctive peculiarity. The higher apes +are equally without it. We find, however, that the human embryo has a +long tail, much longer than the legs, when they are developing. At +times, moreover, children are born with tails--perfect tails, with +nerves and muscles, which they move briskly under emotion, and these +have to be amputated. The development of the limb from the fin offers no +serious difficulty to the osteologist. All the higher animals descend +from a five-toed ancestor. The whale has taken again to the water, and +reconverted its limb into a paddle. The bones of the front feet still +remain under the flesh. Animals of the horse type have had the central +toe strengthened, for running purposes, at the expense of the rest. The +serpent has lost its limbs from disuse, but in the python a rudimentary +limb-bone is still preserved. + +The alimentary system, blood-vessel system, and reproductive system +have been evolved gradually in the same way. The stomach is at first the +whole cavity in the animal. Later it becomes a straight, simple tube, +strengthened by a gullet in front. The liver is an outgrowth from this +tube; the stomach proper is a bulbous expansion of its central part, +later provided with a valve. The kidneys are at first simple channels in +the skin for drainage, then closed tubes, which branch out more and +more, and then gather into our compact kidneys. We thus see that the +building up of the human body from a single cell is a substantial +epitome of the long story of evolution, which occupied many millions of +years. We find man bearing in his body to-day traces of organs which +were useful to a remote ancestor, but of no advantage, and often a +source of mischief to himself. We learn that the origin of man, instead +of being placed a few thousand years ago, must be traced back to the +point where, hundreds of thousands of years ago, he diverged from his +ape-cousins, though he retains to-day the plainest traces of that +relationship. Body and mind--for the development of mind follows with +the utmost precision on the development of brain--he is the culmination +of a long process of development. His spirit is a form of energy +inseparably bound up with the substance of his body. His evolution has +been controlled by the same "eternal, iron laws" as the development of +any other body--the laws of heredity and adaptation. + + + + +WILLIAM HARVEY + +On the Motion of the Heart and Blood + + William Harvey, the discoverer of the circulation of the blood, was + born at Folkestone, England, on April 1, 1578. After graduating + from Caius College, Cambridge, he studied at Padua, where he had + the celebrated anatomist, Fabricius of Aquapendente, for his + master. In 1615 he was elected Lumleian lecturer at the College of + Physicians, and three years later was appointed physician + extraordinary to King James I. In 1628, twelve years after his + first statement of it in his lectures, he published at Frankfurt, + in Latin, "An Anatomical Disquisition on the Motion of the Heart + and Blood," in which he maintained that there is a circulation of + the blood. Moreover, he distinguished between the pulmonary + circulation, from the right side of the heart to the left through + the lungs, and the systemic circulation from the left side of the + heart to the right through the rest of the body. Further, he + maintained that it was the office of the heart to maintain this + circulation by its alternate _diastole_ (expansion) and _systole_ + (contraction) throughout life. This discovery was, says Sir John + Simon, the most important ever made in physiological science. It is + recorded that after his publication of it Harvey lost most of his + practice. Harvey died on June 3, 1657. + + +_I.--Motions of the Heart in Living Animals_ + +When first I gave my mind to vivisections as a means of discovering the +motions and uses of the heart, I found the task so truly arduous that I +was almost tempted to think, with Fracastorius, that the motion of the +heart was only to be comprehended by God. For I could neither rightly +perceive at first when the systole and when the diastole took place, nor +when and where dilation and contraction occurred, by reason of the +rapidity of the motion, which, in many animals, is accomplished in the +twinkling of an eye, coming and going like a flash of lightning. At +length it appeared that these things happen together or at the same +instant: the tension of the heart, the pulse of its apex, which is felt +externally by its striking against the chest, the thickening of its +walls, and the forcible expulsion of the blood it contains by the +constriction of its ventricles. + +Hence the very opposite of the opinions commonly received appears to be +true; inasmuch as it is generally believed that when the heart strikes +the breast and the pulse is felt without, the heart is dilated in its +ventricles and is filled with blood. But the contrary of this is the +fact; that is to say, the heart is in the act of contracting and being +emptied. Whence the motion, which is generally regarded as the diastole +of the heart, is in truth its systole. And in like manner the intrinsic +motion of the heart is not the diastole but the systole; neither is it +in the diastole that the heart grows firm and tense, but in the systole; +for then alone when tense is it moved and made vigorous. When it acts +and becomes tense the blood is expelled; when it relaxes and sinks +together it receives the blood in the manner and wise which will by and +by be explained. + +From divers facts it is also manifest, in opposition to commonly +received opinions, that the diastole of the arteries corresponds with +the time of the heart's systole; and that the arteries are filled and +distended by the blood forced into them by the contraction of the +ventricles. It is in virtue of one and the same cause, therefore, that +all the arteries of the body pulsate, _viz._, the contraction of the +left ventricle in the same way as the pulmonary artery pulsates by the +contraction of the right ventricle. + +I am persuaded it will be found that the motion of the heart is as +follows. First of all, the auricle contracts and throws the blood into +the ventricle, which, being filled, the heart raises itself straightway, +makes all its fibres tense, contracts the ventricles and performs a +beat, by which beat it immediately sends the blood supplied to it by the +auricle into the arteries; the right ventricle sending its charge into +the lungs by the vessel called _vena arteriosa_, but which, in structure +and function, and all things else, is an artery; the left ventricle +sending its charge into the aorta, and through this by the arteries to +the body at large. + +The grand cause of hesitation and error in this subject appears to me to +have been the intimate connection between the heart and the lungs. When +men saw both the pulmonary artery and the pulmonary veins losing +themselves in the lungs, of course it became a puzzle to them to know +how the right ventricle should distribute the blood to the body, or the +left draw it from the _venæ cavæ_. Or they have hesitated because they +did not perceive the route by which the blood is transferred from the +veins to the arteries, in consequence of the intimate connection between +the heart and lungs. And that this difficulty puzzled anatomists not a +little when in their dissections they found the pulmonary artery and +left ventricle full of black and clotted blood, plainly appears when +they felt themselves compelled to affirm that the blood made its way +from the right to the left ventricle by sweating through the septum of +the heart. + +Had anatomists only been as conversant with the dissection of the lower +animals as they are with that of the human body, the matters that have +hitherto kept them in perplexity of doubt would, in my opinion, have met +them freed from every kind of difficulty. And first in fishes, in which +the heart consists of but a single ventricle, they having no lungs, the +thing is sufficiently manifest. Here the sac, which is situated at the +base of the heart, and is the part analogous to the auricle in man, +plainly throws the blood into the heart, and the heart in its turn +conspicuously transmits it by a pipe or artery, or vessel analogous to +an artery; these are facts which are confirmed by simple ocular +experiment. I have seen, farther, that the same thing obtained most +obviously. + +And since we find that in the greater number of animals, in all indeed +at a certain period of their existence, the channels for the +transmission of the blood through the heart are so conspicuous, we have +still to inquire wherefore in some creatures--those, namely, that have +warm blood and that have attained to the adult age, man among the +number--we should not conclude that the same thing is accomplished +through the substance of the lungs, which, in the embryo, and at a time +when the functions of these organs is in abeyance, Nature effects by +direct passages, and which indeed she seems compelled to adopt through +want of a passage by the lungs; or wherefore it should be better (for +Nature always does that which is best) that she should close up the +various open routes which she had formerly made use of in the embryo, +and still uses in all other animals; not only opening up no new apparent +channels for the passage of the blood therefore, but even entirely +shutting up those which formerly existed in the embryos of those animals +that have lungs. For while the lungs are yet in a state of inaction, +Nature uses the two ventricles of the heart as if they formed but one +for the transmission of the blood. The condition of the embryos of those +animals which have lungs is the same as that of those animals which have +no lungs. + +Thus, by studying the structure of the animals who are nearer to and +further from ourselves in their modes of life and in the construction of +their bodies, we can prepare ourselves to understand the nature of the +pulmonary circulation in ourselves, and of the systemic circulation +also. + + +_II.--Systemic Circulation_ + +What remains to be said is of so novel and unheard of a character that I +not only fear injury to myself from the envy of a few, but I tremble +lest I have mankind at large for my enemies, so much do wont and custom +that become as another nature, and doctrine once sown that hath struck +deep root, and respect for antiquity, influence all men. + +And, sooth to say, when I surveyed my mass of evidence, whether derived +from vivisections and my previous reflections on them, or from the +ventricles of the heart and the vessels that enter into and issue from +them, the symmetry and size of these conduits--for Nature, doing nothing +in vain, would never have given them so large a relative size without a +purpose; or from the arrangement and intimate structure of the valves in +particular and of the many other parts of the heart in general, with +many things besides; and frequently and seriously bethought me and long +revolved in my mind what might be the quantity of blood which was +transmitted, in how short a time its passage might be effected and the +like; and not finding it possible that this could be supplied by the +juices of the ingested aliment without the veins on the one hand +becoming drained, and the arteries on the other getting ruptured through +the excessive charge of blood, unless the blood should somehow find its +way from the arteries into the veins, and so return to the right side of +the heart; when I say, I surveyed all this evidence, I began to think +whether there might not be _a motion as it were in a circle_. + +Now this I afterwards found to be true; and I finally saw that the +blood, forced by the action of the left ventricle into the arteries, was +distributed to the body at large, and its several parts, in the same +manner as it is sent through the lungs, impelled by the right ventricle +into the pulmonary artery; and that it then passed through the veins and +along the _vena cava_, and so round to the left ventricle in the manner +already indicated; which motion we may be allowed to call circular, in +the same way as Aristotle says that the air and the rain emulate the +circular motion of the superior bodies. For the moist earth, warmed by +the sun, evaporates; the vapours drawn upwards are condensed, and +descending in the form of rain moisten the earth again. And by this +arrangement are generations of living things produced; and in like +manner, too, are tempests and meteors engendered by the circular motion +of the sun. + +And so in all likelihood does it come to pass in the body through the +motion of the blood. The various parts are nourished, cherished, +quickened by the warmer, more perfect, vaporous, spirituous, and, as I +may say, alimentive blood; which, on the contrary, in contact with these +parts becomes cooled, coagulated, and, so to speak, effete; whence it +returns to its sovereign, the heart, as if to its source, or to the +inmost home of the body, there to recover its state of excellence or +perfection. Here it resumes its due fluidity, and receives an infusion +of natural heat--powerful, fervid, a kind of treasury of life--and is +impregnated with spirits and, it might be said, with balsam; and thence +it is again dispersed. And all this depends upon the motion and action +of the heart. + + +_Confirmations of the Theory_ + +Three points present themselves for confirmation, which, being +established, I conceive that the truth I contend for will follow +necessarily and appear as a thing obvious to all. + +The first point is this. The blood is incessantly transmitted by the +action of the heart from the _vena cava_ to the arteries in such +quantity that it cannot be supplied from the ingesta, and in such wise +that the whole mass must very quickly pass through the organ. + +Let us assume the quantity of blood which the left ventricle of the +heart will contain when distended to be, say, two ounces (in the dead +body I have found it to contain upwards of two ounces); and let us +suppose, as approaching the truth, that the fourth part of its charge +is thrown into the artery at each contraction. Now, in the course of +half an hour the heart will have made more than one thousand beats. +Multiplying the number of drachms propelled by the number of pulses, we +shall have one thousand half-ounces sent from this organ into the +artery; a larger quantity than is contained in the whole body. This +truth, indeed, presents itself obviously before us when we consider what +happens in the dissection of living animals. The great artery need not +be divided, but a very small branch only (as Galen even proves in regard +to man), to have the whole of the blood in the body, as well that of the +veins as of the arteries, drained away in the course of no long +time--some half hour or less. + +The second point is this. The blood, under the influence of the arterial +pulse, enters, and is impelled in a continuous, equable, and incessant +stream through every part and member of the body in much larger quantity +than were sufficient for nutrition, or than the whole mass of fluids +could supply. + +I have here to cite certain experiments. Ligatures are either very tight +or of middling tightness. A ligature I designate as tight, or perfect, +when it is drawn so close about an extremity that no vessel can be felt +pulsating beyond it. Such ligatures are employed in the removal of +tumours; and in these cases, all afflux of nutriment and heat being +prevented by the ligature, we see the tumours dwindle and die, and +finally drop off. Now let anyone make an experiment upon the arm of a +man, either using such a fillet as is employed in bloodletting, or +grasping the limb tightly with his hand; let a ligature be thrown about +the extremity and drawn as tightly as can be borne. It will first be +perceived that beyond the ligature the arteries do not pulsate, while +above it the artery begins to rise higher at each diastole and to swell +with a kind of tide as it strove to break through and overcome the +obstacle to its current. + +Then let the ligature be brought to that state of middling tightness +which is used in bleeding, and it will be seen that the hand and arm +will instantly become deeply suffused and extended, and the veins show +themselves tumid and knotted. Which is as much as to say that when the +arteries pulsate the blood is flowing through them, but where they do +not pulsate they cease from transmitting anything. The veins again being +compressed, nothing can flow through them; the certain indication of +which is that below the ligature they are much more tumid than above it. + +Whence is this blood? It must needs arrive by the arteries. For that it +cannot flow in by the veins appears from the fact that the blood cannot +be forced towards the heart unless the ligature be removed. Further, +when we see the veins below the ligature instantly swell up and become +gorged when from extreme tightness it is somewhat relaxed, the arteries +meanwhile continuing unaffected, this is an obvious indication that the +blood passes from the arteries into the veins, and not from the veins +into the arteries, and that there is either an anastomosis of the two +orders of vessels, or pores in the flesh and solid parts generally that +are permeable to the blood. + +And now we understand wherefore in phlebotomy we apply our fillet above +the part that is punctured, not below it. Did the flow come from above, +not from below, the bandage in this case would not only be of no +service, but would prove a positive hindrance. And further, if we +calculate how many ounces flow through one arm or how many pass in +twenty or thirty pulsations under the medium ligature, we shall perceive +that a circulation is absolutely necessary, seeing that the quantity +cannot be supplied immediately from the ingesta, and is vastly more than +can be requisite for the mere nutrition of the parts. + +And the third point to be confirmed is this. That the veins return this +blood to the heart incessantly from all parts and members of the body. + +This position will be made sufficiently clear from the valves which are +found in the cavities of the veins themselves, from the uses of these, +and from experiments cognisable by the senses. The celebrated Hieronymus +Fabricius, of Aquapendente, first gave representations of the valves in +the veins, which consist of raised or loose portions of the inner +membranes of these vessels of extreme delicacy and a sigmoid, or +semi-lunar shape. Their office is by no means explained when we are told +that it is to hinder the blood, by its weight, from flowing into +inferior parts; for the edges of the valves in the jugular veins hang +downwards, and are so contrived that they prevent the blood from rising +upwards. + +The valves, in a word, do not invariably look upwards, but always +towards the trunks of the veins--towards the seat of the heart. They are +solely made and instituted lest, instead of advancing from the extreme +to the central parts of the body, the blood should rather proceed along +the veins from the centre to the extremities; but the delicate valves, +while they readily open in the right direction, entirely prevent all +such contrary motion, being so situated and arranged that if anything +escapes, or is less perfectly obstructed by the flaps of the one above, +the fluid passing, as it were, by the chinks between the flaps, it is +immediately received on the convexity of the one beneath, which is +placed transversely with reference to the former, and so is effectually +hindered from getting any farther. And this I have frequently +experienced in my dissections of veins. If I attempted to pass a probe +from the trunk of the veins into one of the smaller branches, whatever +care I took I found it impossible to introduce it far any way by reason +of the valves; whilst, on the contrary, it was most easy to push it +along in the opposite direction, from without inwards, or from the +branches towards the trunks and roots. + +And now I may be allowed to give in brief my view of the circulation of +the blood, and to propose it for general adoption. + + +_The Conclusion_ + +Since all things, both argument and ocular demonstration, show that the +blood passes through the lungs and heart by the action of the +ventricles; and is sent for distribution to all parts of the body, where +it makes its way into the veins and pores of the flesh; and then flows +by the veins from the circumference on every side to the centre, from +the lesser to the greater veins; and is by them finally discharged into +the _vena cava_ and right auricle of the heart, and this in such a +quantity or in such a flux and reflux, thither by the arteries, hither +by the veins, as cannot possibly be supplied by the ingesta, and is much +greater than can be required for mere purposes of nutrition; therefore, +it is absolutely necessary to conclude that the blood in the animal body +is impelled in a circle and is in a state of ceaseless motion; and that +this is the act, or function, which the heart performs by means of its +pulse, and that it is the sole and only end of the motion and +contraction of the heart. For it would be very difficult to explain in +any other way to what purpose all is constructed and arranged as we have +seen it to be. + + + + +SIR JOHN HERSCHEL + +Outlines of Astronomy + + Sir John Frederick William Herschel, only child--and, as an + astronomer, almost the only rival--of Sir William Herschel, was + born at Slough, in Ireland, on March 7, 1792. At first privately + educated, in 1813 he graduated from St. John's College, Cambridge, + as senior wrangler and first Smith's prizeman. He chose the law as + his profession; but in 1816 reported that, under his father's + direction, he was going "to take up stargazing." He then began a + re-examination of his father's double stars. In 1825 he wrote that + he was going to take nebulæ under his especial charge. He embarked + in 1833 with his family for the Cape; and his work at Feldhausen, + six miles from Cape Town, marked the beginning of southern sidereal + astronomy. The result of his four years' work there was published + in 1847. From 1855 he devoted himself at Collingwood to the + collection and revival of his father's and his own labours. His + "Outlines of Astronomy," published in 1849, and founded on an + earlier "Treatise on Astronomy" of 1833, was an outstanding + success. Herschel's long and happy life, every day of which added + its share to his scientific services, came to an end on May 11, + 1871. + + +_I.--The Wonders of the Milky Way_ + +There is no science which draws more largely than does astronomy on that +intellectual liberality which is ready to adopt whatever is demonstrated +or concede whatever is rendered highly probable, however new and +uncommon the points of view may be in which objects the most familiar +may thereby become placed. Almost all its conclusions stand in open and +striking contradiction with those of superficial and vulgar observation, +and with what appears to everyone the most positive evidence of his +senses. + +There is hardly anything which sets in a stronger light the inherent +power of truth over the mind of man, when opposed by no motives of +interest or passion, than the perfect readiness with which all its +conclusions are assented to as soon as their evidence is clearly +apprehended, and the tenacious hold they acquire over our belief when +once admitted. + +If the comparison of the apparent magnitude of the stars with their +number leads to no immediately obvious conclusion, it is otherwise when +we view them in connection with their local distribution over the +heavens. If indeed we confine ourselves to the three or four brightest +classes, we shall find them distributed with a considerable approach to +impartiality over the sphere; a marked preference, however, being +observable, especially in the southern hemisphere, to a zone or belt +passing through _epsilon_ Orionis and _alpha_ Crucis. But if we take in +the whole amount visible to the naked eye we shall perceive a great +increase of numbers as we approach the borders of the Milky Way. And +when we come to telescopic magnitudes we find them crowded beyond +imagination along the extent of that circle and of the branches which it +sends off from it; so that, in fact, its whole light is composed of +nothing but stars of every magnitude from such as are visible to the +naked eye down to the smallest points of light perceptible with the best +telescopes. + +These phenomena agree with the supposition that the stars of our +firmament, instead of being scattered indifferently in all directions +through space, form a stratum of which the thickness is small in +comparison with its length and breadth; and in which the earth occupies +a place somewhere about the middle of its thickness and near the point +where it subdivides into two principal laminæ inclined at a small angle +to each other. For it is certain that to an eye so situated the apparent +density of the stars, supposing them pretty equally scattered through +the space they occupy, would be least in the direction of the visual ray +perpendicular to the lamina, and greatest in that of its breadth; +increasing rapidly in passing from one to the other direction, just as +we see a slight haze in the atmosphere thickening into a decided +fog-bank near the horizon by the rapid increase of the mere length of +the visual ray. + +Such is the view of the construction of the starry firmament taken by +Sir William Herschel, whose powerful telescopes first effected a +complete analysis of this wonderful zone, and demonstrated the fact of +its entirely consisting of stars. + +So crowded are they in some parts of it that by counting the stars in a +single field of his telescope he was led to conclude that 50,000 had +passed under his review in a zone two degrees in breadth during a single +hour's observation. The immense distances at which the remoter regions +must be situated will sufficiently account for the vast predominance of +small magnitudes which are observed in it. + +The process of gauging the heavens was devised by Sir William Herschel +for this purpose. It consisted simply in counting the stars of all +magnitudes which occur in single fields of view, of fifteen minutes in +diameter, visible through a reflecting telescope of 18 inches aperture, +and 20 feet focal length, with a magnifying power of 180 degrees, the +points of observation being very numerous and taken indiscriminately in +every part of the surface of the sphere visible in our latitudes. + +On a comparison of many hundred such "gauges," or local enumerations, it +appears that the density of starlight (or the number of stars existing +on an average of several such enumerations in any one immediate +neighbourhood) is least in the pole of the Galactic circle [_i.e._, the +great circle to which the course of the Milky Way most nearly conforms: +_gala_ = milk], and increases on all sides down to the Milky Way itself, +where it attains its maximum. The progressive rate of increase in +proceeding from the pole is at first slow, but becomes more and more +rapid as we approach the plane of that circle, according to a law from +which it appears that the mean density of the stars in the galactic +circle exceeds, in a ratio of very nearly 30 to 1, that in its pole, and +in a proportion of more than 4 to 1 that in a direction 15 degrees +inclined to its plane. + +As we ascend from the galactic plane we perceive that the density +decreases with great rapidity. So far we can perceive no flaw in this +reasoning if only it be granted (1) that the level planes are continuous +and of equal density throughout; and (2) that an absolute and definite +limit is set to telescopic vision, beyond which, if stars exist, they +elude our sight, and are to us as if they existed not. It would appear +that, with an almost exactly similar law of apparent density in the two +hemispheres, the southern were somewhat richer in stars than the +northern, which may arise from our situation not being precisely in the +middle of its thickness, but somewhat nearer to its northern surface. + + +_II.--Penetrating Infinite Space_ + +When examined with powerful telescopes, the constitution of this +wonderful zone is found to be no less various than its aspect to the +naked eye is irregular. In some regions the stars of which it is +composed are scattered with remarkable uniformity over immense tracts, +while in others the irregularity of their distribution is quite as +striking, exhibiting a rapid succession of closely clustering rich +patches separated by comparatively poor intervals, and indeed in some +instances absolutely dark and _completely_ void of any star even of the +smallest telescopic magnitude. In some places not more than 40 or 50 +stars on an average occur in a "gauge" field of 15 minutes, while in +others a similar average gives a result of 400 or 500. + +Nor is less variety observable in the character of its different +regions in respect of the magnitude of the stars they exhibit, and the +proportional numbers of the larger and smaller magnitudes associated +together, than in respect of their aggregate numbers. In some, for +instance, extremely minute stars, though never altogether wanting, occur +in numbers so moderate as to lead us irresistibly to the conclusion that +in these regions we are _fairly through_ the starry stratum, since it is +impossible otherwise (supposing their light not intercepted) that the +numbers of the smaller magnitudes should not go on increasing _ad +infinitum_. + +In such cases, moreover, the ground of the heavens, as seen between the +stars, is for the most part perfectly dark, which again would not be the +case if innumerable multitudes of stars, too minute to be individually +discernible, existed beyond. In other regions we are presented with the +phenomenon of an almost uniform degree of brightness of the individual +stars, accompanied with a very even distribution of them over the ground +of the heavens, both the larger and smaller magnitudes being strikingly +deficient. In such cases it is equally impossible not to perceive that +we are looking through a sheet of stars nearly of a size and of no great +thickness compared with the distance which separates them from us. Were +it otherwise we should be driven to suppose the more distant stars were +uniformly the larger, so as to compensate by their intrinsic brightness +for their greater distance, a supposition contrary to all probability. + +In others again, and that not infrequently, we are presented with a +double phenomenon of the same kind--_viz._, a tissue, as it were, of +large stars spread over another of very small ones, the intermediate +magnitudes being wanting, and the conclusion here seems equally evident +that in such cases we look through two sidereal sheets separated by a +starless interval. + +Throughout by far the larger portion of the extent of the Milky Way in +both hemispheres the general blackness of the ground of the heavens on +which its stars are projected, and the absence of that innumerable +multitude and excessive crowding of the smallest visible magnitudes, and +of glare produced by the aggregate light of multitudes too small to +affect the eye singly, which the contrary supposition would appear to +necessitate, must, we think, be considered unequivocal indications that +its dimensions, _in directions where those conditions obtain_, are not +only not infinite, but that the space-penetrating power of our +telescopes suffices fairly to pierce through and beyond it. + +It is but right, however, to warn our readers that this conclusion has +been controverted, and that by an authority not lightly to be put aside, +on the ground of certain views taken by Olbers as to a defect of perfect +transparency in the celestial spaces, in virtue of which the light of +the more distant stars is enfeebled more than in proportion to their +distance. The extinction of light thus originating proceeding in +geometrical ratio, while the distance increases in arithmetical, a +limit, it is argued, is placed to the space-penetrating power of +telescopes far within that which distance alone, apart from such +obscuration, would assign. + +It must suffice here to observe that the objection alluded to, if +applicable to any, is equally so to every part of the galaxy. We are not +at liberty to argue that at one part of its circumference our view is +limited by this sort of cosmical veil, which extinguishes the smaller +magnitudes, cuts off the nebulous light of distant masses, and closes +our view in impenetrable darkness; while at another we are compelled, by +the clearest evidence telescopes can afford, to believe that star-strewn +vistas _lie open_, exhausting their powers and stretching out beyond +their utmost reach, as is proved by that very phenomenon which the +existence of such a veil would render impossible--_viz._, infinite +increase of number and diminution of magnitude, terminating in complete +irresolvable nebulosity. + +Such is, in effect, the spectacle afforded by a very large portion of +the Milky Way in that interesting region near its point of bifurcation +in Scorpio, where, through the hollows and deep recesses of its +complicated structure, we behold what has all the appearance of a wide +and indefinitely prolonged area strewed over with discontinuous masses +and clouds of stars, which the telescope at last refuses to analyse. +Whatever other conclusions we may draw, this must anyhow be regarded as +the direction of the greatest linear extension of the ground-plan of the +galaxy. And it would appear to follow also that in those regions where +that zone is clearly resolved into stars well separated and _seen +projected on a black ground_, and where, by consequence, it is certain, +if the foregoing views be correct, that we look out beyond them into +space, the smallest visible stars appear as such not by reason of +excessive distance, but of inferiority of size or brightness. + + +_III.--Variable, Temporary and Binary Stars_ + +Wherever we can trace the law of periodicity we are strongly impressed +with the idea of rotatory or orbitual motion. Among the stars are +several which, though in no way distinguishable from others by any +apparent change of place, nor by any difference of appearance in +telescopes, yet undergo a more or less regular periodical increase and +diminution of lustre, involving in one or two cases a complete +extinction and revival. These are called periodic stars. The longest +known, and one of the most remarkable, is the star _Omicron_ in the +constellation Cetus (sometimes called Mira Ceti), which was first +noticed as variable by Fabricius in 1596. It appears about twelve times +in eleven years, remains at its greatest brightness about a fortnight, +being then on some occasions equal to a large star of the second +magnitude, decreases during about three months, till it becomes +completely invisible to the naked eye, in which state it remains about +five months, and continues increasing during the remainder of its +period. Such is the general course of its phases. But the mean period +above assigned would appear to be subject to a cyclical fluctuation +embracing eighty-eight such periods, and having the effect of gradually +lengthening and shortening alternately those intervals to the extent of +twenty-five days one way and the other. The irregularities in the degree +of brightness attained at the maximum are also periodical. + +Such irregularities prepare us for other phenomena of stellar variation +which have hitherto been reduced to no law of periodicity--the phenomena +of temporary stars which have appeared from time to time in different +parts of the heavens blazing forth with extraordinary lustre, and after +remaining awhile, apparently immovable, have died away and left no +trace. In the years 945, 1264, and 1572 brilliant stars appeared in the +region of the heavens between Cepheus and Cassiopeia; and we may suspect +them, with Goodricke, to be one and the same star with a period of 312, +or perhaps 156 years. The appearance of the star of 1572 was so sudden +that Tycho Brahe, a celebrated Dutch astronomer, returning one evening +from his laboratory to his dwellinghouse, was surprised to find a group +of country people gazing at a star which he was sure did not exist half +an hour before. This was the star in question. It was then as bright as +Sirius, and continued to increase till it surpassed Jupiter when +brightest, and was visible at midday. It began to diminish in December +of the same year, and in March 1574 had entirely disappeared. + +In 1803 it was announced by Sir William Herschel that there exist +sidereal systems composed of two stars revolving about each other in +regular orbits, and constituting which may be called, to distinguish +them from double stars, which are only optically double, binary stars. +That which since then has been most assiduously watched, and has offered +phenomena of the greatest interest, is _gamma Virginis_. It is a star of +the vulgar third magnitude, and its component individuals are very +nearly equal, and, as it would seem, in some slight degree variable. It +has been known to consist of two stars since the beginning of the +eighteenth century, the distance being then between six and seven +seconds, so that any tolerably good telescope would resolve it. When +observed by Herschel in 1780 it was 5.66 seconds, and continued to +decrease gradually and regularly, till at length, in 1836, the two stars +had approached so closely as to appear perfectly round and single under +the highest magnifying power which could be applied to most excellent +instruments--the great refractor of Pulkowa alone, with a magnifying +power of a thousand, continuing to indicate, by the wedge-shaped form of +the disc of the star, its composite nature. + +By estimating the ratio of its length to its breadth, and measuring the +former, M. Struve concludes that at this epoch the distance of the two +stars, centre from centre, might be stated at .22 seconds. From that +time the star again opened, and is now again a perfectly easily +separable star. This very remarkable diminution, and subsequent +increase, of distance has been accompanied by a corresponding and +equally remarkable increase and subsequent diminution of relative +angular motion. Thus in 1783 the apparent angular motion hardly amounted +to half a degree per annum; while in 1830 it had decreased to 5 degrees, +in 1834 to 20 degrees, in 1835 to 40 degrees, and about the middle of +1836 to upwards of 70 degrees per annum, or at the rate of a degree in +five days. + +This is in entire conformity with the principles of dynamics, which +establish a necessary connection between the angular velocity and the +distance, as well in the apparent as in the real orbit of one body +revolving about another under the influence of mutual attraction; the +former varying inversely as the square of the latter, in both orbits, +whatever be the curve described and whatever the law of the attractive +force. + +It is not with the revolutions of bodies of a planetary or cometary +nature round a solar centre that we are concerned; it is that of sun +round sun--each perhaps, at least in some binary systems, where the +individuals are very remote and their period of revolution very long, +accompanied by its train of planets and their satellites, closely +shrouded from our view by the splendour of their respective suns, and +crowded into a space bearing hardly a greater proportion to the enormous +interval which separates them than the distances of the satellites of +our planets from their primaries bear to their distances from the sun +itself. + +A less distinctly characterised subordination would be incompatible with +the stability of their systems and with the planetary nature of their +orbits. Unless close under the protecting wing of their immediate +superior, the sweep of their other sun, in its perihelion passage round +their own, might carry them off or whirl them into orbits utterly +incompatible with conditions necessary for the existence of their +inhabitants. + + +_IV.--The Nebulæ_ + +It is to Sir William Herschel that we owe the most complete analysis of +the great variety of those objects which are generally classed as +nebulæ. The great power of his telescopes disclosed the existence of an +immense number of these objects before unknown, and showed them to be +distributed over the heavens not by any means uniformly, but with a +marked preference to a certain district extending over the northern pole +of the galactic circle. In this region, occupying about one-eighth of +the surface of the sphere, one-third of the entire nebulous contents of +the heavens are situated. + +The resolvable nebulæ can, of course, only be considered as clusters +either too remote, or consisting of stars intrinsically too faint, to +affect us by their individual light, unless where two or three happen to +be close enough to make a joint impression and give the idea of a point +brighter than the rest. They are almost universally round or oval, their +loose appendages and irregularities of form being, as it were, +extinguished by the distance, and only the general figure of the +condensed parts being discernible. It is under the appearance of objects +of this character that all the greater globular clusters exhibit +themselves in telescopes of insufficient optical power to show them +well. + +The first impression which Halley and other early discoverers of +nebulous objects received from their peculiar aspect was that of a +phosphorescent vapour (like the matter of a comet's tail), or a gaseous +and, so to speak, elementary form of luminous sidereal matter. Admitting +the existence of such a medium, Sir W. Herschel was led to speculate on +its gradual subsidence and condensation, by the effect of its own +gravity, into more or less regular spherical or spheroidal forms, denser +(as they must in that case be) towards the centre. + +Assuming that in the progress of this subsidence local centres of +condensation subordinate to the general tendency would not be wanting, +he conceived that in this way solid nuclei might arise whose local +gravitation still further condensing, and so absorbing the nebulous +matter each in its immediate neighbourhood, might ultimately become +stars, and the whole nebula finally take on the state of a cluster of +stars. + +Among the multitude of nebulæ revealed by his telescope every stage of +this process might be considered as displayed to our eyes, and in every +modification of form to which the general principle might be conceived +to apply. The more or less advanced state of a nebula towards its +segregation into discrete stars, and of these stars themselves towards a +denser state of aggregation round a central nucleus, would thus be in +some sort an indication of age. + + + + +ALEXANDER VON HUMBOLDT + +Cosmos, a Sketch of the Universe + + Frederick Henry Alexander von Humboldt was born in Berlin on + September 14, 1769. In 1788 he made the acquaintance of George + Forster, one of Captain Cook's companions, and geological + excursions made with him were the occasion of his first + publications, a book on the nature of basalt. His work in the + administration of mines in the principalities of Bayreuth and + Anspach furnished materials for a treatise on fossil flora; and in + 1827, when he was residing in Paris, he gave to the world his + "Voyage to the Equinoctial Regions of the New Continent," which + embodies the results of his investigations in South America. Two + years later he organised an expedition to Asiatic Russia, charging + himself with all the scientific observations. But his principal + interest lay in the accomplishment of that physical description of + the universe for which all his previous studies had been a + preparation, and which during the years 1845 to 1848 appeared under + the comprehensive title of "Cosmos, or Sketch of a Physical + Description of the Universe." Humboldt died on May 6, 1859. + + +_I.--The Physical Study of the World_ + +The natural world may be opposed to the intellectual, or nature to art +taking the latter term in its higher sense as embracing the +manifestations of the intellectual power of man; but these +distinctions--which are indicated in most cultivated languages--must not +be suffered to lead to such a separation of the domain of physics from +that of the intellect as would reduce the physics of the universe to a +mere assemblage of empirical specialities. Science only begins for man +from the moment when his mind lays hold of matter--when he tries to +subject the mass accumulated by experience to rational combinations. + +Science is mind applied to nature. The external world only exists for us +so far as we conceive it within ourselves, and as it shapes itself +within us into the form of a contemplation of nature. As intelligence +and language, thought and the signs of thought, are united by secret and +indissoluble links, so, and almost without our being conscious of it, +the external world and our ideas and feelings melt into each other. +"External phenomena are translated," as Hegel expresses it in his +"Philosophy of History," "in our internal representation of them." The +objective world, thought by us, reflected in us, is subjected to the +unchanging, necessary, and all-conditioning forms of our intellectual +being. + +The activity of the mind exerts itself on the elements furnished to it +by the perceptions of the senses. Thus, in the youth of nations there +manifests itself in the simplest intuition of natural facts, in the +first efforts made to comprehend them, the germ of the philosophy of +nature. + +If the study of physical phenomena be regarded in its bearings not on +the material wants of man, but on his general intellectual progress, its +highest result is found in the knowledge of those mutual relations which +link together the general forces of nature. It is the intuitive and +intimate persuasion of the existence of these relations which at once +enlarges and elevates our views and enhances our enjoyment. Such +extended views are the growth of observation, of meditation, and of the +spirit of the age, which is ever reflected in the operations of the +human mind whatever may be their direction. + +From the time when man, in interrogating nature, began to experiment or +to produce phenomena under definite conditions, and to collect and +record the fruits of his experience--so that investigation might no +longer be restricted by the short limits of a single life--the +philosophy of nature laid aside the vague and poetic forms with which +she had at first been clothed, and has adopted a more severe character. + +The history of science teaches us how inexact and incomplete +observations have led, through false inductions, to that great number +of erroneous physical views which have been perpetuated as popular +prejudices among all classes of society. Thus, side by side with a solid +and scientific knowledge of phenomena, there has been preserved a system +of pretended results of observation, the more difficult to shake because +it takes no account of any of the facts by which it is overturned. + +This empiricism--melancholy inheritance of earlier times--invariably +maintains whatever axioms it has laid down; it is arrogant, as is +everything that is narrow-minded; while true physical philosophy, +founded on science, doubts because it seeks to investigate +thoroughly--distinguishes between that which is certain and that which +is simply probable--and labours incessantly to bring its theories nearer +to perfection by extending the circle of observation. This assemblage of +incomplete dogmas bequeathed from one century to another, this system of +physics made up of popular prejudices, is not only injurious because it +perpetuates error with all the obstinacy of ill-observed facts, but also +because it hinders the understanding from rising to the level of great +views of nature. + +Instead of seeking to discover the _mean_ state around which, in the +midst of apparent independence and irregularity, the phenomena really +and invariably oscillate, this false science delights in multiplying +apparent exceptions to the dominion of fixed laws, and seeks, in organic +forms and the phenomena of nature, other marvels than those presented by +internal progressive development, and by regular order and succession. +Ever disinclined to recognise in the present the analogy of the past, it +is always disposed to believe the order of nature suspended by +perturbations, of which it places the seat, as if by chance, sometimes +in the interior of the earth, sometimes in the remote regions of space. + + +_II.--The Inductive Method_ + +The generalisation of laws which were first applied to smaller groups of +phenomena advances by successive gradations, and their empire is +extended, and their evidence strengthened, so long as the reasoning +process is directed to really analogous phenomena. Empirical +investigation begins by single perceptions, which are afterwards classed +according to their analogy or dissimilarity. Observation is succeeded at +a much later epoch by experiment, in which phenomena are made to arise +under conditions previously determined on by the experimentalist, guided +by preliminary hypotheses, or a more or less just intuition of the +connection of natural objects and forces. + +The results obtained by observation and experiment lead by the path of +induction and analogy to the discovery of empirical laws, and these +successive phases in the application of human intellect have marked +different epochs in the life of nations. It has been by adhering closely +to this inductive path that the great mass of facts has been accumulated +which now forms the solid foundation of the natural sciences. + +Two forms of abstraction govern the whole of this class of +knowledge--_viz._, the determination of quantitative relations, +according to number and magnitude; and relations of quality, embracing +the specific properties of heterogeneous matter. + +The first of these forms, more accessible to the exercise of thought, +belongs to the domain of mathematics; the other, more difficult to +seize, and apparently more mysterious, to that of chemistry. In order to +submit phenomena to calculation, recourse is had to a hypothetical +construction of matter by a combination of molecules and atoms whose +number, form, position, and polarity determine, modify, and vary the +phenomena. + +We are yet very far from the time when a reasonable hope could be +entertained of reducing all that is perceived by our senses to the unity +of a single principle; but the partial solution of the problem--the +tendency towards a general comprehension of the phenomena of the +universe--does not the less continue to be the high and enduring aim of +all natural investigation. + + +_III.--Distribution of Matter in Space_ + +A physical cosmography, or picture of the universe, should begin, not +with the earth, but with the regions of space--the distribution of +matter in the universe. + +We see matter existing in space partly in the form of rotating and +revolving spheroids, differing greatly in density and magnitude, and +partly in the form of self-luminous vapour dispersed in shining nebulous +spots or patches. The nebulæ present themselves to the eye in the form +of round, or nebulous discs, of small apparent magnitude, either single +or in pairs, which are sometimes connected by a thread of light; when +their diameters are greater their forms vary--some are elongated, others +have several branches, some are fan-shaped, some annular, the ring being +well defined and the interior dark. They are supposed to be undergoing +various and progressive changes of form, as condensation proceeds around +one or more nuclei in conformity with the laws of gravitation. Between +two and three thousand of such unresolvable nebulæ have already been +counted, and their positions determined. + +If we leave the consideration of the attenuated vaporous matter of the +immeasurable regions of space, whether existing in a dispersed state as +a cosmical ether without form or limits, or in the shape of nebulæ, and +pass to those portions of the universe which are condensed into solid +spheres or spheroids, we approach a class of phenomena exclusively +designated as stars or as the sidereal universe. Here, too, we find +different degrees of solidity or density in the agglomerated matter. + +If we compare the regions of space to one of the island-studded seas of +our planet, we may imagine we see matter distributed in groups, whether +of unresolvable nebulæ of different ages condensed around one or more +nuclei, or in clusters of stars, or in stars scattered singly. Our +cluster of stars, or the island in space to which we belong, forms a +lens-shaped, flattened, and everywhere detached stratum, whose major +axis is estimated at seven or eight hundred, and its minor axis at a +hundred and fifty times, the distance of Sirius. If we assume that the +parallax of Sirius does not exceed that accurately determined for the +brightest stars in Centaur (0.9128 sec.), it will follow that light +traverses one distance of Sirius in three years, while nine years and a +quarter are required for the transmission of the light of the star 61 +Cygni, whose considerable proper motion might lead to the inference of +great proximity. + +Our cluster of stars is a disc of comparatively small thickness divided, +at about a third its length, into two branches; we are supposed to be +near this division, and nearer to the region of Sirius than to that of +the constellation of the Eagle; almost in the middle of the starry +stratum in the direction of its thickness. + +The place of our solar system and the form of the whole lens are +inferred from a kind of scale--_i.e._, from the different number of +stars seen in equal telescopic fields of view. The greater or less +number of stars measures the relative depth of the stratum in different +directions; giving in each case, like the marks on a sounding-line, the +comparative length of visual ray required to reach the bottom; or, more +properly, as above and below do not here apply, the outer limit of the +sidereal stratum. + +In the direction of the major axis, where the greater number of stars +are placed behind each other, the remoter ones appear closely crowded +together, and, as it were, united by a milky radiance, and present a +zone or belt projected on the visible celestial vault. This narrow belt +is divided into branches; and its beautiful, but not uniform brightness, +is interrupted by some dark places. As seen by us on the apparent +concave celestial sphere, it deviates only a few degrees from a great +circle, we being near the middle of the entire starry cluster, and +almost in the plane of the Milky Way. If out planetary system were far +outside the cluster, the Milky Way would appear to telescopic vision as +a ring, and at a still greater distance as a resolvable disc-shaped +nebula. + + +_IV.--On Earth History_ + +The succession and relative age of different geological formations are +traced partly by the order of superposition of sedimentary strata, of +metamorphic beds, and of conglomerates, but most securely by the +presence of organic remains and their diversities of structure. In the +fossiliferous strata are inhumed the remains of the floras and faunas of +past ages. As we descend from stratum to stratum to study the relations +of superposition, we ascend in the order of time, and new worlds of +animal and vegetable existence present themselves to the view. + +In our ignorance of the laws under which new organic forms appear from +time to time upon the surface of the globe, we employ the expression +"new creations" when we desire to refer to the historical phenomena of +the variations which have taken place at intervals in the animals and +plants that have inhabited the basins of the primitive seas and the +uplifted continents. + +It has sometimes happened that extinct species have been preserved +entire, even to the minutest details of their tissues and articulations. +In the lower beds of the Secondary Period, the lias of Lyme Regis, a +sepia has been found so wonderfully preserved that a part of the black +fluid with which the animal was provided myriads of years ago to conceal +itself from its enemies has actually served at the present time to draw +its picture. In other cases such traces alone remain as the impression +which the feet of animals have left on wet sand or mud over which they +passed when alive, or the remains of their undigested food (coprolites). + +The analytical study of the animal and vegetable kingdoms of the +primitive world has given rise to two distinct branches of science; one +purely morphological, which occupies itself in natural and physiological +descriptions, and in the endeavour to fill up from extinct forms the +chasms which present themselves in the series of existing species; the +other branch, more especially geological considers the relations of the +fossil remains to the superposition and relative age of the sedimentary +beds in which they are found. The first long predominated; and the +superficial manner which then prevailed of comparing fossil and existing +species led to errors of which traces still remain in the strange +denominations which were given to certain natural objects. Writers +attempted to identify all extinct forms with living species, as, in the +sixteenth century, the animals of the New World were confounded by false +analogies with those of the Old. + +In studying the relative age of fossils by the order of superposition of +the strata in which they are found, important relations have been +discovered between families and species (the latter always few in +numbers) which have disappeared and those which are still living. All +observations concur in showing that the fossil floras and faunas differ +from the present animal and vegetable forms the more widely in +proportion as the sedimentary beds to which they belong are lower, or +more ancient. + +Thus great variations have successively taken place in the general +types of organic life, and these grand phenomena, which were first +pointed out by Cuvier, offer numerical relations which Deshayes and +Lyell have made the object of researches by which they have been +conducted to important results, especially as regards the numerous and +well-preserved fossils of the Tertiary formation. Agassiz, who has +examined 1,700 species of fossil fishes, and who estimates at 8,000 the +number of living species which have been described, or which are +preserved in our collections, affirms that, with the exception of one +small fossil fish peculiar to the argillaceous geodes of Greenland, he +has never met in the Transition, Secondary, or Tertiary strata with any +example of this class specifically identical with any living fish; and +he adds the important remark that even in the lower Tertiary formations +a third of the fossil fishes of the _calcaire grossier_ and of the +London clay belong to extinct families. + +We have seen that fishes, which are the oldest vertebrates, first appear +in the Silurian strata, and are found in all the succeeding formations +up to the birds of the Tertiary Period. Reptiles begin in like manner in +the magnesian limestone, and if we now add that the first mammalia are +met with in Oolite, the Stonefield slate; and that the first remains of +birds have been found in the deposits of the cretaceous period, we shall +have indicated the inferior limits, according to our present knowledge, +of the four great divisions of the vertebrates. + +In regard to invertebrate animals, we find corals and some shells +associated in the oldest formations with very highly organised +cephalopodes and crustaceans, so that widely different orders of this +part of the animal kingdom appear intermingled; there are, nevertheless, +many isolated groups belonging to the same order in which determinate +laws are discoverable. Whole mountains are sometimes found to consist of +a single species of fossil goniatites, trilobites, or nummulites. + +Where different genera are intermingled, there often exists a +systematic relation between the series of organic forms and the +superposition of the formations; and it has been remarked that the +association of certain families and species follows a regular law in the +superimposed strata of which the whole constitutes one formation. It has +been found that the waters in the most distant parts of the globe were +inhabited at the same epochs by testaceous animals corresponding, at +least in generic character, with European fossils. + +Strata defined by their fossil contents, or by the fragments of other +rocks which they include, form a geological horizon by which the +geologist may recognise his position, and obtain safe conclusions in +regard to the identity or relative antiquity of formations, the +periodical repetition of certain strata--their parallelism--or their +entire suppression. If we would thus comprehend in its greatest +simplicity the general type of the sedentary formations, we find in +proceeding successively from below upwards: (1) The Transition group, +including the Silurian and Devonian (Old Red Sandstone) systems; (2) the +Lower Trias, comprising mountain limestone, the coal measures, the lower +new red sandstone, and the magnesian limestone; (3) the Upper Trias, +composing the bunter, or variegated sandstone, the muschelkalk, and the +Keuper sandstone; (4) the Oolitic, or Jurassic series, including Lias; +(5) the Cretaceous series; (6) the Tertiary group, as represented in its +three stages by the _calcaire grossier_ and other beds of the Paris +basin, the lignites, or brown coal of Germany, and the sub-Apennine +group of Italy. + +To these succeed transported soils (_alluvium_), containing the gigantic +bones of ancient mammalia, such as the mastodons, the dinotherium, and +the megatheroid animals, among which is the mylodon of Owen, an animal +upwards of eleven feet in length, allied to the sloth. Associated with +these extinct species are found the fossil remains of animals still +living: elephants, rhinoceroses, oxen, horses, and deer. Near Bogota, at +an elevation of 8,200 French feet above the level of the sea, there is a +field filled with the bones of mastodon (_Campo de Gigantes_), in which +I have had careful excavations made. The bones found on the table-lands +of Mexico belong to the true elephants of extinct species. The minor +range of the Himalaya, the Sewalik hills, contain, besides numerous +mastodons, the sivatherium and the gigantic land-tortoise +(_Colossochelys_), more than twelve feet in length and six in height, as +well as remains belonging to still existing species of elephants, +rhinoceroses, and giraffes. It is worthy of notice that these fossils +are found in a zone which enjoys the tropical climate supposed to have +prevailed at the period of the mastodons. + + +_V.--The Permanence of Science_ + +It has sometimes been regarded as a discouraging consideration that, +while works of literature being fast-rooted in the depths of human +feeling, imagination and reason suffer little from the lapse of time, it +is otherwise with works which treat of subjects dependent on the +progress of experimental knowledge. The improvement of instruments, and +the continued enlargement of the field of observation, render +investigations into natural phenomena and physical laws liable to become +antiquated, to lose their interest, and to cease to be read. + +Let none who are deeply penetrated with a true and genuine love of +nature, and with a lively appreciation of the true charm and dignity of +the study of her laws, ever view with discouragement or regret that +which is connected with the enlargement of the boundaries of our +knowledge. Many and important portions of this knowledge, both as +regards the phenomena of the celestial spaces and those belonging to our +own planet, are already based on foundations too firm to be lightly +shaken; although in other portions general laws will doubtless take the +place of those which are more limited in their application, new forces +will be discovered, and substances considered as simple will be +decomposed, while others will become known. + + + + +JAMES HUTTON + +The Theory of the Earth + + James Hutton, the notable Scotch geologist, was born at Edinburgh + on June 3, 1726. In 1743 he was apprenticed to a Writer to the + Signet; but his apprenticeship was of short duration and in the + following year he began to study medicine at Edinburgh University, + and in 1749 graduated as an M.D. Later he determined to study + agriculture, and went, in 1752, to live with a Norfolk farmer to + learn practical farming. He did not devote himself entirely to + agriculture, but gave a considerable amount of his time to chemical + and geological researches. His geological researches culminated in + his great work, "The Theory of the Earth," published at Edinburgh + in 1795. In this work he propounds the theory that the present + continents have been formed at the bottom of the sea by the + precipitation of the detritus of former continents, and that the + precipitate had been hardened by heat and elevated above the sea by + the expansive power of heat. He died on March 26, 1797. Other works + are his "Theory of Rain," "Elements of Agriculture," "Natural + Philosophy," and "Nature of Coal." + + +_I.--Origin and Consolidation of the Land_ + +The solid surface of the earth is mainly composed of gravel, of +calcareous, and argillaceous strata. Sand is separated by streams and +currents, gravel is formed by the attrition of stones agitated in water, +and argillaceous strata are deposited by water containing argillaceous +material. Accordingly, the solid earth would seem to have been mainly +produced by water, wind, and tides, and this theory is confirmed by the +discovery that all the masses of marble and limestone are composed of +the calcareous matter of marine bodies. All these materials were, in the +first place, deposited at the bottom of the sea, and we have to +consider, firstly, how they were consolidated; and secondly, how they +came to be dry land, elevated above the sea. + +It is plain that consolidation may have been effected either through +the concretion of substances dissolved in water or through fusion by +fire. Consolidation through the concretion of substances dissolved in +the sea is unlikely, for, in the first place, there are strata, such as +siliceous matter, which are insoluble, and which could not therefore +have been in solution; and, in the second place, the appearance of the +strata is contrary to this supposition. Consolidation was probably +effected by heat and fusion. All the substances in the earth may be +rendered fluid by heat, and all the appearances in the earth's crust are +consistent with the consolidation and crystallisation of fused +substances. Not only so, but we find rents and separations and veins in +the strata, such as would naturally occur in strata consolidated by the +cooling of fused masses, and other phenomena pointing to fusion by heat. +We may conclude, then, that all the solid strata of the globe have been +hardened from a state of fusion. + +But how were these strata raised up from the bottom of the sea and +transformed into dry land? Even as heat was the consolidating power, so +heat was also probably the elevating power. The power of heat for the +expansion of bodies is, as we know, unlimited, and the expansive power +of heat was certainly competent to raise the strata above the sea. Heat +was certainly competent, and if we examine the crust of the earth we +find evidence that heat was used. + +If the strata cemented by the heat of fusion were created by the +expansive power of heat acting from below, we should expect to find +every species of fracture, dislocation, and contortion in those bodies, +and every degree of departure from a horizontal towards a vertical +position. And this is just what we do find. From horizontal, the strata +are frequently found vertical; from continuous, broken, and separated in +every possible direction; and from a plane, bent and doubled. The theory +is confirmed by an examination of the veins and fissures of the earth +which contain matter foreign to the strata they traverse, and evidently +forced into them as a fluid under great pressure. Active volcanoes, and +extinct volcanoes, and the marks everywhere of volcanic action likewise +support the theory of expansion and elevation by heat. A volcano is not +made on purpose to frighten superstitious people into fits of piety and +devotion; it is to be considered as a spiracle of a subterranean +furnace. + +Such being the manner of the formation of the crust of the world, can we +form any judgment of its duration and durability? If we could measure +the rate of the attrition of the present continents, we might estimate +the duration of the older continents whose attrition supplied the +material for the present dry land. But as we cannot measure the +wearing-away of the land, we can merely state generally, first, that the +present dry land required an indefinitely long period for its formation; +second, that the previous dry land which supplied material for its +formation required equal time to make; third, that there is at present +land forming at the bottom of the sea which in time will appear above +the surface; fourth, that we find no vestige of a beginning, or of an +end. + +Granite has in its own nature no claim to originality, for it is found +to vary greatly in its composition. But, further, it is certain that +granite, or a species of the same kind of stone, is found stratified. It +is the _granit feuilletée_ of M. de Sauffure, and, if I mistake not, is +called _gneiss_ by the Germans. Granite being thus found stratified, the +masses of this stone cannot be allowed to any right of priority over the +schistus, its companion in Alpine countries. + +Lack of stratification, then, cannot be considered a proof of primitive +rock. Nor can lack of organized bodies, such as shells, in these rocks, +be considered a proof; for the traces of organized bodies may be +obliterated by the many subsequent operations of the mineral region. In +any case, signs of organized bodies are sometimes found in "primitive" +mountains. + +Nor can metallic veins, found plentifully in "primitive" mountains, +prove anything, for mineral veins are found in various strata. + +We maintain that _all_ the land was produced from fused substances +elevated from the bottom of the sea. But we do not hold that all parts +of the earth have undergone exactly similar and simultaneous +vicissitudes; and in respect to the changes which various parts of the +land have undergone we may distinguish between primary and secondary +strata. Nothing is more certain than that there have been several +repeated operations of the mineralising power exerted upon the strata in +particular places, and all those mineral operations tend to +consolidation. It is quite possible that "primitive" masses which differ +from the ordinary strata of the globe have been twice subjected to +mineral operations, having been first consolidated and raised as land, +and then submerged in order to be again fused and elevated. + + +_II.--The Nature of Mineral Coal_ + +Mineral, or fossil, coal is a species of stratum distinguished by its +inflammable and combustible nature. We find that it differs in respect +to its purity, and also in respect to its inflammability. As is well +known, some coals have almost no earthy ash, some a great deal; and, +again, some coals burn with much smoke and fire, while others burn like +coke. Where, then, did coal come from, and how can we account for its +different species? + +A substance proper for the formation of coaly matter is found in +vegetable bodies. But how did it become mixed with earthy matter? + +Vegetable bodies may be resolved into bituminous or coaly matter either +by means of fire or by means of water. Both may be used by nature in +the formation of coal. + +By the force of subterranean heat vegetable matter may have been charred +at the bottom of the sea, and the oleaginous, bituminous, and fuliginous +substances diffused through the sea as a result of the burning may have +been deposited at the bottom of the sea as coal. Further, the bituminous +matter from the smoke of vegetable substances burned on land would +ultimately be deposited from the atmosphere and settle at the bottom of +the sea. + +Many of the rivers contain in solution an immense quantity of +inflammable vegetable substance, and this is carried into the sea, and +precipitated there. + +From these two sources, then, the sea gets bituminous material, and this +material, condensed and consolidated by compression and by heat, at the +bottom of the sea, would form a black body of a most uniform structure, +breaking with a polished surface, and burning with more or less smoke or +flame in proportion as it be distilled less or more by subterranean +heat. And such a body exactly represents our purest fossil coal, which +gives the most heat and leaves the least ash. + +In some cases the bituminous material in suspension in the sea would be +mixed more or less with argillaceous, calcareous, and other earthy +substances; and these being precipitated along with the bituminous +matter would form layers of impure coal with a considerable amount of +ash. + +But there is still a third source of coal. Vegetable bodies macerated in +water, and consolidated by compression, form a body almost +indistinguishable from some species of coal, as is seen in peat +compressed under a great load of earth; and there can be no doubt that +coal sometimes originates in this way, for much fossil coal shows +abundance of vegetable bodies in its composition. + +There remains only to consider the change in the disposition of coal +strata. Coal strata, which had been originally in a horizontal position, +are now found sometimes standing erect, even perpendicular. This, also, +is consistent with our theory of the earth. Indeed, there is not a +substance in the mineral kingdom in which the action of subterranean +heat is better shown. These strata are evidently a deposit of +inflammable substances which all come originally from vegetable bodies. +In this stage of their formation they must all contain volatile +oleaginous constituents. But some coal strata contain no volatile +constituents, and the disappearance of the volatile oleaginous +substances must have been produced by distillation, proceeding perhaps +under the restraining force of immense compression. + +We cannot doubt that such distillation does take place in the mineral +regions, when we consider that in most places of the earth we find the +evident effects of such distillation in the naphtha and petroleum that +are constantly emitted along with water in certain springs. We have, +therefore, sufficient proof of this operation of distillation. + + +_III.--The Disintegration and Dissolution of Land_ + +Whether we examine the mountain or the plain, whether we consider the +disintegration of the rocks or the softer strata of the earth, whether +we regard the shores of seas or the central plains of continents, +whether we contemplate fertile lands or deserts, we find evidence of a +general dissolution and decay of the solid surface of the globe. Every +great river and deep valley gives evidence of the attrition of the land. +The purpose of the dry land is to sustain a system of plants and +animals; and for this purpose a soil is required, and to make a soil the +solid strata must be crumbled down. The earth is nothing more than an +indefinite number of soils and situations suitable for various animals +and plants, and it must consist of both solid rock and tender earth, of +both moist and dry districts; for all these are requisite for the world +we inhabit. + +But not only is the solid rock crumbling into soil by the action of air +and water, but the soil gradually progresses towards the sea, and sooner +or later the sea must swallow up the land. Vegetation and masses of +solid rock retard the seaward flow of the soil; but they merely retard, +they cannot wholly prevent. In proportion as the mountains are +diminished, the haugh, or plain, between them grows more wide, and also +on a lower level; but while there is a river running on a plain, and +floods produced in the seasons of rain, there is nothing stable in the +constitution of the surface of the land. + +The theory of the earth which I propound is founded upon the great +catastrophes that can happen to the earth. It supposes strata raised +from the bottom of the sea and elevated into mountainous continents. +But, between the catastrophes, it requires nothing further than the +ordinary everyday effects of air and water. Every shower of rain, every +stream, participates in the dissolution of the land, and helps to +transport to the sea the material for future continents. + +The prodigious waste of the land we see in places has seemed to some to +require some other explanation; but I maintain that the natural +operations of air and water would suffice in time to produce the effects +observed. It is true that the wastage would be slow; but slow +destruction of rock with gradual formation of soil is just what is +required in the economy of nature. A world sustaining plants and animals +requires continents which endure for more than a day. + +If this continent of land, first collected in the sea, is to remain a +habitable earth, and to resist the moving waters of the globe, certain +degrees of solidity or consolidation must be given to that collection of +loose materials; and certain degrees of hardness must be given to +bodies which are soft and incoherent, and consequently so extremely +perishable in the situation in which they are now placed. + +But, at the same time that this earth must have solidity and hardness to +resist the sudden changes which its moving fluids would occasion, it +must be made subject to decay and waste upon the surface exposed to the +atmosphere; for such an earth as were made incapable of change, or not +subject to decay, would not afford that fertile soil which is required +in the system of this world--a soil on which depends the growth of +plants and life of animals--the end of its intention. + +Now, we find this earth endued precisely with such degree of hardness +and consolidation as qualifies it at the same time to be a fruitful +earth, and to maintain its station with all the permanency compatible +with the nature of things, which are not formed to remain unchangeable. + +Thus we have a view of the most perfect wisdom in the contrivance of +that constitution by which the earth is made to answer, in the best +manner possible, the purpose of its intention, that is, to maintain and +perpetuate a system of vegetation, or the various races of useful +plants, or a system of living animals, which are in their turn +subservient to a system still infinitely more important--I mean a system +of intellect. Without fertility in the earth, many races of plants and +animals would soon perish, or be extinct; and with permanency in our +land it were impossible for the various tribes of plants and animals to +be dispersed over the surface of a changing earth. The fact is that +fertility, adequate to the various ends in view, is found in all the +quarters of the world, or in every country of the earth; and the +permanency of our land is such as to make it appear unalterable to +mankind in general and even to impose upon men of science, who have +endeavoured to persuade us that this earth is not to change. + +Nothing but supreme power and wisdom could have reconciled those two +opposite ends of intention, so as both to be equally pursued in the +system of nature, and so equally attained as to be imperceptible to +common observation, and at the same time a proper object of the human +understanding. + + + + +LAMARCK + +Zoological Philosophy + + Jean Baptiste de Monet, Chevalier de Lamarck, was born in Picardy, + France, Aug. I, 1744, the cadet of an ancient but impoverished + house. It was his father's desire that he should enter the Church, + but his inclination was for a military life; and having, at the age + of seventeen, joined the French army under De Broglie, he had + within twenty-four hours the good fortune so to distinguish himself + as to win his commission. When the Museum of Natural History was + brought into existence in 1794 he was sufficiently well-known as a + naturalist to be entrusted with the care of the collections of + invertebrates, comprising insects, molluscs, polyps, and worms. + Here he continued to lecture until his death in 1829. Haeckel, + classifying him in the front rank with Goethe and Darwin, + attributes to him "the imperishable glory of having been the first + to raise the theory of descent to the rank of an independent + scientific theory." The form of his theory was announced in 1801, + but was not given in detail to the world until 1809, by the + publication of his "Zoological Philosophy" ("Philosophie + Zoologique"). The Lamarckian theory of the hereditary transmission + of characters acquired by use, disuse, etc., has still a following, + though it is controverted by the schools of Darwin and Weissmann. + Lamarck died on December 18, 1829. + + +_I.--The Ladder of Life_ + +If we look backwards down the ladder of animal forms we find a +progressive degradation in the organisation of the creatures comprised; +the organisation of their bodies becomes simpler, the number of their +faculties less. This well-recognised fact throws a light upon the order +in which nature has produced the animals; but it leaves unexplained the +fact that this gradation, though sustained, is irregular. The reason +will become clear if we consider the effects produced by the infinite +diversity of conditions in different parts of the globe upon the +general form, the limbs, and the very organisation of the animals in +question. + +It will, in fact, be evident that the state in which we find all animals +is the product, on the one hand, of the growing composition of the +organisation which tends to form a regular gradation; and that, for the +rest, it results from a multitude of circumstances which tend +continually to destroy the regularity of the gradation in the +increasingly composite nature of the organism. + +Not that circumstances can effect any modification directly. But changed +circumstances produce changed wants, changed wants changed actions. If +the new wants become constant the animals acquire new habits, which are +no less constant than the wants which gave rise to them. And such new +habits will necessitate the use of one member rather than another, or +even the cessation of the use of a member which has lost its utility. + +We will look at some familiar examples of either case. Among vegetables, +which have no actions, and therefore no habits properly so called, great +differences in the development of the parts do none the less arise as a +consequence of changed circumstances; and these differences cause the +development of certain of them, while they attenuate others and cause +them to disappear. But all this is caused by changes in the nutrition of +the plant, in its absorptions and transpirations, in the quantity of +heat and light, of air and moisture, which it habitually receives; and, +lastly, by the superiority which certain of its vital movements may +assert over the others. There may arise between individuals of the same +species, of which some are placed in favourable, others amid +unfavourable, conditions, a difference which by degrees becomes very +notable. + +Suppose that circumstances keep certain individuals in an ill-nourished +or languid state. Their internal organisation will at length be +modified, and these individuals will engender offspring which will +perpetuate the modifications thus acquired, and thus will in the end +give place to a race quite distinct from that of which the individual +members come together always under circumstances favourable to their +development. + +For instance, if a seed of some meadow flower is carried to dry and +stony ground, where it is exposed to the winds and there germinates, the +consequence will be that the plant and its immediate offspring, being +always ill-nourished, will give rise to a race really different from +that which lives in the field; yet this, none the less, will be its +progenitor. The individuals of this race will be dwarfed; and their +organs, some being increased at the expense of the rest, will show +distinctive proportions. What nature does in a long time we do every day +ourselves. Every botanist knows that the vegetables transplanted to our +gardens out of their native soil undergo such changes as render them at +last unrecognisable. + +Consider, again, the varieties among our domestic fowls and pigeons, all +of them brought into existence by being raised in diverse circumstances +and different countries, and such as might be sought in vain in a state +of nature. It is matter of common knowledge that if we raise a bird in a +cage, and keep it there for five or six years, it will be unable to fly +if restored to liberty. There has, indeed, been no change as yet in the +form of its members; but if for a long series of generations individuals +of the same race had been kept caged for a considerable time, there is +no room for doubt that the very form of their limbs would little by +little have undergone notable alteration. Much more would this be the +case if their captivity had been accompanied by a marked change of +climate, and if these individuals had by degrees accustomed themselves +to other sorts of food and to other measures for acquiring it. Such +circumstances, taken constantly together, would have formed insensibly a +new and clearly denned race. + +The following example shows, in regard to plants, how the change of +some important circumstance may tend to change the various parts of +these living bodies. + +So long as the _ranunculus aquatilis_, the water buttercup, is under +water its leaves are all finely indented, and the divisions are +furnished with capillaries; but as soon as the stalk of the plant +reaches the surface the leaves, which develop in the air, are broadened +out, rounded, and simply lobed. If the plant manages to spring up in a +soil that is merely moist, and not covered with water, the stems will be +short, and none of the leaves will show these indentations and +capillaries. You have then the _ranunculus hederaceus_, which botanists +regard as a distinct species. + +Among animals changes take place more slowly, and it is therefore more +difficult to determine their cause. The strongest influence, no doubt, +is that of environment. Places far apart are different, and--which is +too commonly ignored--a given place changes its climate and quality with +time, though so slowly in respect of human life that we attribute to it +perfect stability. Hence it arises that we have not only extreme +changes, but also shadowy ones between the extremes. + +Everywhere the order of things changes so gradually that man cannot +observe the change directly, and the animal tribes in every place +preserve their habits for a long time; whence arises the apparent +constancy of what we call species--a constancy which has given birth in +us to the idea that these races are as old as nature. + +But the surface of the habitable globe varies in nature, situation, and +climate, in every variety of degrees. The naturalist will perceive that +just in proportion as the environment is notably changed will the +species change their characters. + +It must always be recognised: + +(1) That every considerable and constant change in the environment of a +race of animals works a real change in their wants. + +(2) That every change in their wants necessitates new actions to supply +them, and consequently new habits. + +(3) That every new want calling for new actions for its satisfaction +affects the animal in one of two ways. Either it has to make more +frequent use of some particular member, and this will develop the part +and cause it to increase in size; or it must employ new members which +will grow in the animal insensibly in response to the inward yearning to +satisfy these wants. And this I will presently prove from known facts. + +How the new wants have been able to attain satisfaction, and how the new +habits have been acquired, it will be easy to see if regard be had to +the two following laws, which observation has always confirmed. + + FIRST LAW.--In every animal which has not arrived at the term of + its developments, the more frequent and sustained use of any organ + strengthens, develops, and enlarges that organ, and gives it a + power commensurate with the duration of this employment of it. On + the other hand, constant disuse of such organ weakens it by + degrees, causes it to deteriorate, and progressively diminishes its + faculties, so that in the end it disappears. + + SECOND LAW.--All qualities naturally acquired by individuals as the + result of circumstances to which their race is exposed for a + considerable time, or as a consequence of a predominant employment + or the disuse of a certain organ, nature preserves to individual + offspring; provided that the acquired modifications are common to + the two sexes, or, at least, to both parents of the individual + offspring. + +Naturalists have observed that the members of animals are adapted to +their use, and thence have concluded hitherto that the formation of the +members has led to their appropriate employment. Now, this is an error. +For observation plainly shows that, on the contrary, the development of +the members has been caused by their need and use; that these have +caused them to come into existence where they were wanting. + +But let us examine the facts which bear upon the effects of employment +or disuse of organs resulting from the habits which a race has been +compelled to form. + + +_II.--The Penalties of Disuse_ + +Permanent disuse of an organ as a consequence of acquired habits +gradually impoverishes it, and in the end causes it to disappear, or +even annihilates it altogether. + +Thus vertebrates, which, in spite of innumerable particular +distinctions, are alike in the plan of their organisation, are generally +armed with teeth. Yet those of them which by circumstances have acquired +the habit of swallowing their prey without mastication have been liable +to leave their teeth undeveloped. Consequently, the teeth have either +remained hidden between the bony plates of the jaws, or have even been, +in the course of time, annihilated. + +The whale was supposed to have no teeth at all till M. Geoffrey found +them hidden in the jaws of the foetus. He has also found in birds the +groove in which teeth might be placed, but without any trace of the +teeth themselves. A similar case to that of the whale is the ant-eater +(_nyomecophaga_), which has long given up the practice of mastication. + +Eyes in the head are an essential part of the organisation of +vertebrates. Yet the mole, which habitually makes no use of the sense of +sight, has eyes so small that they can hardly be seen; and the aspalax, +whose habits-resemble a mole's, has totally lost its sight, and shows +but vestiges of eyes. So also the proteus, which inhabits dark caves +under water. + +In such cases, since the animals in question belong to a type of which +eyes are an essential part, it is clear that the impoverishment, and +even the total disappearance, of these organs are the results of long +continued disuse. + +With hearing, the case is otherwise. Sound traverses everything. +Therefore, wherever an animal dwells it may exercise this faculty. And +so no vertebrate lacks it, and we never find it re-appearing in any of +the lower ranges. Sight disappears, re-appears, and disappears again, +according as circumstances deny or permit its exercise. + +Four legs attached to its skeleton are part of the reptile type; and +serpents, particularly as between them and the fishes come the +batrachians--frogs, etc.--ought to have four legs. + +But serpents, having acquired the habit of gliding along the ground, and +concealing themselves amid the grass, their bodies, as a consequence of +constantly repeated efforts to lengthen themselves out in order to pass +through narrow passages, have acquired considerable length of body which +is out of all proportion to their breadth. + +Now, feet would have been useless to these animals, and consequently +would have remained unemployed; for long legs would have interfered with +their desire to go on their bellies; and short legs, being limited in +number to four, would have been incapable of moving their bodies. Thus +total disuse among these races of animals has caused the parts which +have fallen into disuse totally to disappear. + +Many insects, which by their order and genus should have wings, lack +them more or less completely for similar reasons. + + +_III.--The Advantages of Use_ + +The frequent use of an organ, if constant and habitual, increases its +powers, develops it, and makes it acquire dimensions and potency such +as are not found among animals which use it less. + +Of this principle, the web-feet of some birds, the long legs and neck of +the stork, are examples. Similarly, the elongated tongue of the +ant-eater, and those of lizards and serpents. + +Such wants, and the sustained efforts to satisfy them, have also +resulted in the displacement of organs. Fishes which swim habitually in +great masses of water, since they need to see right and left of them, +have the eyes one upon either side of the head. Their bodies, more or +less flat, according to species, have their edges perpendicular to the +plane of the water; and their eyes are so placed as to be one on either +side of the flattened body. But those whose habits bring them constantly +to the banks, especially sloping banks, have been obliged to lie over +upon the flattened surface in order to approach more nearly. In this +position, in which more light falls on the upper than on the under +surface, and their attention is more particularly fixed upon what is +going on above than on what is going on below them, this want has forced +one of the eyes to undergo a kind of displacement, and to keep the +strange position which it occupies in the head of a sole or a turbot. +The situation is not symmetrical because the mutation is not complete. +In the case of the skate, however, it is complete; for in these fish the +transverse flattening of the body is quite horizontal, no less than that +of the head. And so the eyes of a skate are not only placed both of them +on the upper surface, but have become symmetrical. + +Serpents need principally to see things above them, and, in response to +this need, the eyes are placed so high up at the sides of the head that +they can see easily what is above them on either side, while they can +see in front of them but a very little distance. To compensate for this, +the tongue, with which they test bodies in their line of march, has been +rendered by this habit thin, long, and very contractile, and even, in +most species, has been split so as to be able to test more than one +object at a time. The same custom has resulted similarly in the +formation of an opening at the end of the muzzle by which the tongue may +be protruded without any necessity for the opening of the jaws. + +The effect of use is curiously illustrated in the form and figure of the +giraffe. This animal, the largest of mammals, is found in the interior +of Africa, where the ground is scorched and destitute of grass, and has +to browse on the foliage of trees. From the continual stretching thus +necessitated over a great space of time in all the individuals of the +race, it has resulted that the fore legs have become longer than the +hind legs, and that the neck has become so elongated that the giraffe, +without standing on its hind legs, can raise its head to a height of +nearly twenty feet. Observation of all animals will furnish similar +examples. + +None, perhaps, is more striking than that of the kangaroo. This animal, +which carries its young in an abdominal pouch, has acquired the habit of +carrying itself upright upon its hind legs and tail, and of moving from +place to place in a series of leaps, during which, in order not to hurt +its little ones, it preserves its upright posture. Observe the result. + +(1) Its front limbs, which it uses very little, resting on them only in +the instant during which it quits its erect posture, have never acquired +a development in proportion to the other parts; they have remained thin, +little, and weak. + +(2) The hind legs, almost continually in action, whether to bear the +weight of the whole body or to execute its leaps, have, on the contrary, +obtained a considerable development; they are very big and very strong. + +(3) Finally, the tail, which we observe to be actively employed, both to +support the animal's weight and to execute its principal movements, has +acquired at its base a thickness and a strength that are extremely +remarkable. + +When the will determines an animal to a certain action, the organs +concerned are forthwith stimulated by a flow of subtle fluids, which are +the determining cause of organic changes and developments. And +multiplied repetitions of such acts strengthen, extend, and even call +into being the organs necessary to them. Now, every change in an organ +which has been acquired by habitual use sufficient to originate it is +reproduced in the offspring if it is common to both the individuals +which have come together for the reproduction of their species. In the +end, this change is propagated and passes to all the individuals which +come after and are submitted to the same conditions, without its being +necessary that they should acquire it in the original manner. + +For the rest, in the union of disparate couples, the disparity is +necessarily opposed to the constant propagation of such qualities and +outward forms. This is why man, who is exposed to such diversity of +conditions, does not preserve and propagate the qualities or the +accidental defects which he has been in the way of acquiring. Such +peculiarities will be produced only in case two individuals who share +them unite; these will produce offspring bearing similar +characteristics, and, if successive generations restrict themselves to +similar unions, a distinct race will then be formed. But perpetual +intermixture will cause all characters acquired through particular +circumstances to disappear. If it were not for the distances which +separate the races of men, such intermixture would quickly obliterate +all national distinctions. + + +_IV.--The Conclusion_ + +Here, then, is the conclusion to which we have come. It is a fact that +every genus and species of animal has its characteristic habits combined +with an organisation perfectly in harmony with them. From the +consideration of this fact one of two conclusions must follow, and that +though neither of them can be proved. + +(1) The conclusion admitted hitherto--that nature (or its Author) in +creating the animals has foreseen all the possible sets of circumstances +in which they would have to live, has given to each species a constant +organisation, and has shaped its parts in a determined and invariable +way so that every species is compelled to live in the districts and the +climates where it is actually formed, and to keep the habits by which it +is actually known. + +(2) My own conclusion--that nature has produced in succession all the +animal species, beginning with the more imperfect, or the simpler, and +ending with the more perfect; that in so doing it has gradually +complicated their organisation; and that of these animals, dispersed +over the habitable globe, every species has acquired, under the +influence of the circumstances amid which it is found, the habits and +modifications of form which we associate with it. + +To prove that the second of these hypotheses is unfounded, it will be +necessary, first, to prove that the surface of the globe never varies in +character, in exposure, situation, whether elevated or sheltered, +climate, etc.; and, secondly, to prove that no part of the animal world +undergoes, even in the course of long periods of time, any modification +through change of circumstances, or as a consequence of a changed manner +of life and action. + +Now, a single fact which establishes that an animal, after a long period +of domestication, differs from the wild stock from which it derives, and +that among the various domesticated members of a species may be found +differences no less marked between individuals which, have been +subjected to one use and those which have been subjected to another, +makes it certain that the former conclusion is not consistent with the +laws of nature, and that the second is. + +Everything, therefore, concurs to prove my assertion, to wit--that it is +not form, whether of the body or of the parts, which gives rise to the +habits of animals and their manner of life; but that, on the contrary, +in the habits, the manner of living, and all the other circumstances of +environment, we have those things which in the course of time have built +up animal bodies with all their members. With new forms new faculties +have been acquired, and little by little nature has come to shape +animals and all living things in their present forms. + + + + +JOHANN LAVATER + +Physiognomical Fragments + + Johann Caspar Lavater, the Swiss theologian, poet, and + physiognomist, was born at Zürich on November 15, 1741. He began + his public life at the age of twenty-one as a political reformer. + Five years later he appeared as a poet, and published a volume of + poetry which was very favourably received. During the next five + years he produced a religious work, which was considered heretical, + although its mystic, religious enthusiasm appealed to a + considerable audience. His fame, however, rests neither on his + poetry nor on his theology, but on his physiognomical studies, + published in four volumes between 1775-78 under the title + "Physiognomical Fragments for the Advancement of Human Knowledge + and Human Life" ("Physiognomische Fragmente zur Beförderung des + Menschenkenntniss und Menschenliebe"). The book is diffuse and + inconsequent, but it contains many shrewd observations with respect + to physiognomy and has had no little influence on popular opinion + in this matter. Lavater died on January 2, 1801. + + +_I.--The Truth of Physiognomy_ + +There can be no doubt of the truth of physiognomy. All countenances, all +forms, all created beings, are not only different from each other in +their classes, races, kinds, but are also individually distinct. It is +indisputable that all men estimate all things whatever by their external +temporary superficies--that is to say, by their physiognomy. Is not all +nature physiognomy, superficies and contents, body and spirit, external +effect and internal power? There is not a man who does not judge of all +things that pass through his hands by their physiognomy--there is not a +man who does not more or less, the first time he is in company with a +stranger, observe, estimate, compare, judge him according to +appearances. When each apple, each apricot, has a physiognomy peculiar +to itself, shall man, the lord of the earth, have none? + +Man is the most perfect of all earthly creatures. In no other creature +are so wonderfully united the animal, the intellectual, and the moral. +And man's organisation peculiarly distinguishes him from all other +beings, and shows him to be infinitely superior to all those other +visible organisms by which he is surrounded. His head, especially his +face, convinces the accurate observer, who is capable of investigating +truth, of the greatness and superiority of his intellectual qualities. +The eye, the expression, the cheeks, the mouth, the forehead, whether +considered in a state of entire rest, or during their innumerable +varieties of motion--in fine, whatever is understood by physiognomy--are +the most expressive, the most convincing picture of interior sensations, +desires, passions, will, and of all those properties which so much exalt +moral above animal life. + +Although the physiological, intellectual, and moral are united in man, +yet it is plain that each of these has its peculiar station where it +more especially unfolds itself and acts. + +It is, beyond contradiction, evident that, though physiological or +animal life displays itself through all the body, and especially through +all the animal parts, yet it acts more conspicuously in the arm, from +the shoulder to the ends of the fingers. + +It is not less evident that intellectual life, or the powers of the +understanding and the mind, make themselves most apparent in the +circumference and form of the solid parts of the head, especially the +forehead; though they will discover themselves to the attentive and +accurate eye in every part and point of the human body, by the +congeniality and harmony of the various parts. Is there any occasion to +prove that the power of thinking resides not in the foot, nor in the +hand, nor in the back, but in the head and its internal parts? + +The moral life of man particularly reveals itself in the lines, marks, +and transitions of the countenance. His moral powers and desires, his +irritability, sympathy, and antipathy, his facility of attracting or +repelling the objects that surround him--these are all summed up in, and +painted upon, his countenance when at rest. + +Not only do mental and moral traits evince themselves in the +physiognomy, but also health and sickness; and I believe that by +repeatedly examining the firm parts and outlines of the bodies and +countenances of the sick, disease might be diagnosed, and even that +liability to disease might be predicted in particular cases. + +The same vital powers that make the heart beat and the fingers move, +roof the skull and arch the finger-nails. From the head to the back, +from the shoulder to the arm, from the arm to the hand, from the hand to +the finger, each depends on the other, and all on a determinate effect +of a determinate power. Through all nature each determinate power is +productive of only such and such determinate effects. The finger of one +body is not adapted to the hand of another body. The blood in the +extremity of the finger has the character of the blood in the heart. The +same congeniality is found in the nerves and in the bones. One spirit +lives in all. Each member of the body, too, is in proportion to the +whole of which it is a part. As from the length of the smallest member, +the smallest joint of the finger, the proportion of the whole, the +length and breadth of the body may be found; so also may the form of the +whole be found from the form of each single part. When the head is long, +all is long; when the head is round, all is round; when the head is +square, all is square. + +One form, one mind, one root appertain to all. Each organised body is so +much a whole that, without discord, destruction, or deformity, nothing +can be added or subtracted. Those, therefore, who maintain that +conclusion cannot be drawn from a part to the whole labour under error, +failing to comprehend the harmony of nature. + + +_II.--Physiognomy and the Features_ + +The Forehead. The form, height, arching, proportion, obliquity, and +position of the skull, or bone of the forehead, show the propensity of +thought, power of thought, and sensibility of man. The position, colour, +wrinkles, tension of the skin of the forehead, show the passions and +present state of the mind. The bones indicate the power, the skin the +application of power. + +I consider the outline and position of the forehead to be the most +important feature in physiognomy. We may divide foreheads into three +principal classes--the retreating, the perpendicular, and the +projecting, and each of these classes has a multitude of variations. + +A few facts with respect to foreheads may now be given. + +The higher the forehead, the more comprehension and the less activity. + +The more compressed, short, and firm the forehead, the more compression +and firmness, and the less volatility in the man. + +The more curved and cornerless the outline, the more tender and flexible +the character; and the more rectilinear, the more pertinacious and +severe the character. + +Perfect perpendicularity implies lack of understanding, but gently +arched at top, capacity for cold, tranquil, profound thought. + +A projecting forehead indicates imbecility, immaturity, weakness, +stupidity. + +A retreating forehead, in general, denotes superior imagination, wit, +acuteness. + +A forehead round and prominent above, straight below, and, on the whole, +perpendicular, shows much understanding, life, sensibility, ardour. + +An oblique, rectilinear forehead is ardent and vigorous. + +Arched foreheads appear properly to be feminine. + +A forehead neither too perpendicular nor too retreating, but a happy +mean, indicates the post-perfect character of wisdom. + +I might also state it as an axiom that straight lines considered as +such, and curves considered as such, are related as power and weakness, +obstinacy and flexibility, understanding and sensation. + +I have seen no man with sharp, projecting eyebones who was not inclined +to vigorous thinking and wise planning. + +Yet, even lacking sharpness, a head may be excellent if the forehead +sink like a perpendicular wall upon horizontal eyebrows, and be greatly +rounded towards the temples. + +Perpendicular foreheads, projecting so as not to rest immediately upon +the nose, and small, wrinkled, short, and shining, indicate little +imagination, little understanding, little sensation. + +Foreheads with many angular, knotty protuberances denote perseverance +and much vigorous, firm, harsh, oppressive, ardent activity. + +It is a sure sign of a clear, sound understanding and a good temperament +when the profile of the forehead has two proportionate arches, the lower +of which projects. + +Eyebones with well-marked, firm arches I never saw but in noble and +great men. + +Square foreheads with extensive temples and firm eyebones show +circumspection and steadiness of character. + +Perpendicular wrinkles, if natural, denote application and power. +Horizontal wrinkles and those broken in the middle or at the extremities +generally denote negligence or want of power. + +Perpendicular, deep indentings in the forehead between the eyebrows, I +never met save in men of sound understanding and free and noble minds, +unless there were some positively contradictory feature. + +A blue frontal vein, in the form of a Y, when in an open, smooth, +well-arched forehead, I have only found in men of extraordinary talents +and of ardent and generous character. + +The following are the traits of a perfectly beautiful, intelligent, and +noble forehead. + +In length it must equal the nose, or the under part of the face. In +breadth it must be either oval at the top-like the foreheads of most of +the great men of England--or nearly square. It must be free from +unevenness and wrinkles, yet be able to wrinkle when deep in thought, +afflicted by pain, or moved by indignation. It must retreat above and +project beneath. The eyebones must be simple, horizontal, and, if seen +from above, must present a simple curve. There should be a small cavity +in the centre, from above to below, and traversing the forehead so as to +separate it into four divisions perceptible in a clear descending light. +The skin must be more clear on the forehead than in other parts of the +countenance. + +Foreheads short, wrinkled, and knotty, are incapable of durable +friendship. + +Be not discouraged though a friend, an enemy, a child, or a brother +transgress, for so long as he have a good, well-proportioned, open +forehead there is still hope of improvement. + +THE EYES AND EYEBROWS. Blue eyes are generally more indicative of +weakness and effeminacy than brown or black. Certainly there are many +powerful men with blue eyes, but I find more strength, manhood, thought +with brown. + +Choleric men have eyes of every colour, but rather brown or greenish +than blue. A propensity to green is an almost decisive token of ardour, +fire, and courage. + +Wide open eyes, with the white visible, I have often observed both in +the timid and phlegmatic, and in the courageous and rash. + +Meeting eyebrows were supposed to be the mark of craft, but I do not +believe them to have this significance. Angular, strong, interrupted +eyebrows denote fire and productive activity. The nearer the eyebrows to +the eyes, the more earnest, deep, and firm the character. Eyebrows +remote from each other denote warm, open, quick sensations. White +eyebrows signify weakness; and dark brown, firmness. The motion of the +eyebrows contains numerous expressions, especially of ignoble passions. + +THE NOSE. I have generally considered the nose the foundation or +abutment of the brain, for upon this the whole power of the arch of the +forehead rests. A beautiful nose will never be found accompanying an +ugly countenance. An ugly person may have fine eyes, but not a handsome +nose. + +I have never seen a nose with a broad back, whether arched or +rectilinear, that did not belong to an extraordinary man. Such a nose +was possessed by Swift, Cæsar Borgia, Titian, etc. Small nostrils are +usually an indubitable sign of unenterprising timidity. The open, +breathing nostril is as certain a token of sensibility. + +THE MOUTH AND LIPS. The contents of the mind are communicated to the +mouth. How full of character is the mouth! As are the lips, so is the +character. Firm lips, firm character; weak lips, weak character. +Well-defined, large, and proportionate lips, the middle line of which is +equally serpentine on both sides, and easy to be drawn, are never seen +in a bad, mean, common, false, vicious countenance. A lipless mouth, +resembling a single line, denotes coldness, industry, a love of order, +precision, house-wifery, and, if it be drawn upwards at the two ends, +affectation, pretension, vanity, malice. Very fleshy lips have always to +contend with sensuality and indolence. Calm lips, well closed, without +constraint, and well delineated, certainly betoken consideration, +discretion, and firmness. Openness of mouth speaks complaint, and +closeness, endurance. + +THE CHIN. From numerous experiments, I am convinced that the projecting +chin ever denotes something positive, and the retreating something +negative. The presence or absence of strength in man is often signified +by the chin. + +I have never seen sharp indentings in the middle of the chin save in men +of cool understanding, unless when something evidently contradictory +appeared in the countenance. The soft, fat, double chin generally points +out the epicure; and the angular chin is seldom found save in discreet, +well-disposed, firm men. Flatness of chin speaks the cold and dry; +smallness, fear; and roundness, with a dimple, benevolence. + +SKULLS. HOW much may the anatomist see in the mere skull of man! How +much more the physiognomist! And how much more still the anatomist who +is a physiognomist! If shown the bald head of Cæsar, as painted by +Rubens or Titian or Michael Angelo, what man would fail to notice the +rocky capacity which characterises it, and to realise that more ardour +and energy must be expected than from a smooth, round, flat head? How +characteristic is the skull of Charles XII.! How different from the +skull of his biographer Voltaire! Compare the skull of Judas with the +skull of Christ, after Holbein, and I doubt whether anyone would fail to +guess which is the skull of the wicked betrayer and which the skull of +the innocent betrayed. And who is unacquainted with the statement in +Herodotus that it was possible on the field of battle to distinguish the +skulls of the effeminate Medes from the skulls of the manly Persians? +Each nation, indeed, has its own characteristic skull. + + +_III.--Nation, Sex, and Family_ + +NATIONAL PHYSIOGNOMY. It is undeniable that there is a national +physiognomy as well as national character. Compare a negro and an +Englishman, a native of Lapland and an Italian, a Frenchman and an +inhabitant of Tierra del Fuego. Examine their forms, countenances, +characters, and minds. This difference will be easily seen, though it +will sometimes be very difficult to describe it scientifically. + +The following infinitely little is what I have hitherto observed in the +foreigners with whom I have conversed. + +I am least able to characterise the French, They have no traits so bold +as the English, nor so minute as the Germans. I know them chiefly by +their teeth and their laugh. The Italians I discover by the nose, small +eyes, and projecting chin. The English by their foreheads and eyebrows. +The Dutch by the rotundity of their heads and the weakness of the hair. +The Germans by the angles and wrinkles round the eyes and in the cheeks. +The Russians by the snub nose and their light-coloured or black hair. + +I shall now say a word concerning Englishmen in particular. Englishmen +have the shortest and best-arched foreheads--that is to say, they are +arched only upwards, and, towards the eyebrows, either gently recline or +are rectilinear. They seldom have pointed, usually round, full noses. +Their lips are usually large, well defined, beautifully curved. Their +chins are round and full. The outline of their faces is in general +large, and they never have those numerous angles and wrinkles by which +the Germans are so especially distinguished. Their complexion is fairer +than that of the Germans. + +All Englishwomen whom I have known personally, or by portrait, appear to +be composed of marrow and nerve. They are inclined to be tall, slender, +soft, and as distant from all that is harsh, rigorous, or stubborn as +heaven is from earth. + +The Swiss have generally no common physiognomy or national character, +the aspect of fidelity excepted. They are as different from each other +as nations the most remote. + +THE PHYSIOGNOMICAL RELATION OF THE SEXES. Generally speaking, how much +more pure, tender, delicate, irritable, affectionate, flexible, and +patient is woman than man. The primary matter of which woman is +constituted appears to account for this difference. All her organs are +tender, yielding, easily wounded, sensible, and receptive; they are made +for maternity and affection. Among a thousand women, there is hardly one +without these feminine characteristics. + +This tenderness and sensibility, the light texture of their fibres and +organs, render them easy to tempt and to subdue, and yet their charms +are more potent than the strength of man. Truly sensible of purity, +beauty and symmetry, woman does not always take time to reflect on +spiritual life, spiritual death, spiritual corruption. + +The woman does not think profoundly; profound thought is the prerogative +of the man; but women feel more. They rule with tender looks, tears, and +sighs, but not with passion and threats, unless they are monstrosities. +They are capable of the sweetest sensibility, the deepest emotion, the +utmost humility, and ardent enthusiasm. In their faces are signs of +sanctity which every man honours. + +Owing to their extreme sensibility and their incapacity for accurate +inquiry and firm decision, they may easily become fanatics. + +The love of women, strong as it is, is very changeable; but their hatred +is almost incurable, and is only to be overcome by persistent and artful +flattery. Men usually see things as a whole, whereas women take more +interest in details. + +Women have less physical courage than men. Man hears the bursting +thunders, views the destructive bolt with serene aspect, and stands +erect amid the fearful majesty of the torrent. But woman trembles at the +lightning and thunder, and seeks refuge in the arms of man. + +Woman is formed for pity and religion; and a woman without religion is +monstrous; and a woman who is a freethinker is more disgusting than a +woman with a beard. + +Woman is not a foundation on which to build. She is the gold, silver, +precious stones, wood, hay, stubble--the materials for building on the +male foundation. She is the leaven, or, more expressly, she is oil to +the vinegar of man. Man singly is but half a man, only half human--a +king without a kingdom. Woman must rest upon the man, and man can be +what he ought to be only in conjunction with the woman. + +Some of the principal physiognomical contrasts may be summarised here. + +Man is the most firm; woman the most flexible. + +Man is the straightest; woman the most bending. + +Man stands steadfast; woman gently retreats. + +Man surveys and observes; woman glances and feels. + +Man is serious; woman is gay. + +Man is the tallest and broadest; woman the smallest and weakest. + +Man is rough and hard; woman is smooth and soft. + +Man is brown; woman is fair. + +The hair of the man is strong and short; the hair of woman is pliant and +long. + +Man has most straight lines; woman most curved. + +The countenance of man, taken in profile, is not so often perpendicular +as that of woman. + +FAMILY PHYSIOGNOMY. The resemblance between parents and children is very +commonly remarkable. Family physiognomical resemblance is as undeniable +as national physiognomical resemblance. To doubt this is to doubt what +is self-evident. + +When children, as they increase in years, visibly increase in their +physical resemblance to their parents, we cannot doubt that resemblance +in character also increases. Howsoever much the character of children +may seem to differ from that of their parents, yet this difference will +be found to be due to great difference in external circumstances. + + + + +JUSTUS VON LIEBIG + +Animal Chemistry + + Baron Freiherr Justus von Liebig, one of the most illustrious + chemists of his age, was born on May 12, 1803, at Darmstadt, + Germany, the son of a drysalter. It was in his father's business + that his interest in chemistry first awoke, and at fifteen he + became an apothecary's assistant. Subsequently, he went to + Erlangen, where he took his doctorate in 1822; and afterwards, in + Paris, was admitted to the laboratory of Gay-Lussac as a private + pupil. In 1824 he was appointed a teacher of chemistry in the + University of Giessen in his native state. Here he lived for + twenty-eight years a quiet life of incessant industry, while his + fame spread throughout Europe. In 1845 he was raised to the + hereditary rank of baron, and seven years later was appointed by + the Bavarian government to the professorship of chemistry in the + University of Munich. Here he died on April 18, 1873. The treatise + on "Animal Chemistry, or Organic Chemistry in its Relations to + Physiology and Pathology," published in 1842, sums up the results + of Liebig's investigations into the immediate products of animal + life. He was the first to demonstrate that the only source of + animal heat is that produced by the oxidation of the tissues. + + +_I.--Chemical Needs of Life_ + +Animals, unlike plants, require highly organised atoms for nutriment; +they can subsist only upon parts of an organism. All parts of the animal +body are produced from the fluid circulating within its organism. A +destruction of the animal body is constantly proceeding, every motion is +the result of a transformation of its structure; every thought, every +sensation is accompanied by a change in the composition of the substance +of the brain. Food is applied either in the increase of the mass of a +structure (nutrition) or in the replacement of a structure wasted +(reproduction). + +Equally important is the continual absorption of oxygen from the +atmosphere. All vital activity results from the mutual action of the +oxygen of the atmosphere and the elements of food. According to +Lavoisier, an adult man takes into his system every year 827 lb. of +oxygen, and yet he does not increase in weight. What, then, becomes of +this oxygen?--for no part of it is again expired as oxygen. The carbon +and hydrogen of certain parts of the body have entered into combination +with the oxygen introduced through the lungs and through the skin, and +have been given out in the form of carbonic acid and the vapour of +water. + +Now, an adult inspires 32-1/2 oz. of oxygen daily; this will convert the +carbon of 24 lb. of blood (80 per cent. water) into carbonic acid. He +must, therefore, take as much nutriment as will supply the daily loss. +And, in fact, it is found that he does so; for the average amount of +carbon in the daily food of an adult man is 14 oz., which requires 37 +oz. of oxygen for its conversion into carbonic acid. The amount of food +necessary for the support of the animal body must be in direct ratio to +the quantity of oxygen taken into the system. A bird deprived of food +dies on the third day; while a serpent, which inspires a mere trace of +oxygen, can live without food for three months. The number of +respirations is less in a state of rest than in exercise, and the amount +of food necessary in both conditions must vary also. + +The capacity of the chest being a constant quantity, we inspire the same +volume of air whether at the pole or at the equator; but the weight of +air, and consequently of oxygen, varies with the temperature. Thus, an +adult man takes into the system daily 46,000 cubic inches of oxygen, +which, if the temperature be 77° F., weighs 32-1/2 oz., but when the +temperature sinks to freezing-point will weigh 35 oz. It is obvious, +also, that in an equal number of respirations we consume more oxygen at +the level of the sea than on a mountain. The quantity of oxygen inspired +and carbonic acid expired must, therefore, vary with the height of the +barometer. In our climate the difference between summer and winter in +the carbon expired, and therefore necessary for food, is as much as +one-eighth. + + +_II.--The Cause of Animal Heat_ + +Now, the mutual action between the elements of food and the oxygen of +the air is the source of animal heat. + +This heat is wholly due to the combustion of the carbon and hydrogen in +the food consumed. Animal heat exists only in those parts of the body +through which arterial blood (and with it oxygen in solution) +circulates; hair, wool, or feathers, do not possess an elevated +temperature. + +As animal heat depends upon respired oxygen, it will vary according to +the respiratory apparatus of the animal. Thus the temperature of a child +is 102° F., while that of an adult is 99-1/2° F. That of birds is higher +than that of quadrupeds or that of fishes or amphibia, whose proper +temperature is 3° F higher than the medium in which they live. All +animals, strictly speaking, are warm-blooded; but in those only which +possess lungs is their temperature quite independent of the surrounding +medium. The temperature of the human body is the same in the torrid as +in the frigid zone; but the colder the surrounding medium the greater +the quantity of fuel necessary to maintain its heat. + +The human body may be aptly compared to the furnace of a laboratory +destined to effect certain operations. It signifies nothing what +intermediate forms the food, or fuel, of the furnace may assume; it is +finally converted into carbonic acid and water. But in order to sustain +a fixed temperature in the furnace we must vary the quantity of fuel +according to the external temperature. + +In the animal body the food is the fuel; with a proper supply of oxygen +we obtain the heat given out during its oxidation or combustion. In +winter, when we take exercise in a cold atmosphere, and when +consequently the amount of inspired oxygen increases, the necessity for +food containing carbon and hydrogen increases in the same ratio; and by +gratifying the appetite thus excited, we obtain the most efficient +protection against the most piercing cold. A starving man is soon frozen +to death; and everyone knows that the animals of prey in the Arctic +regions far exceed in voracity those in the torrid zone. In cold and +temperate climates, the air, which incessantly strives to consume the +body, urges man to laborious efforts in order to furnish the means of +resistance to its action, while in hot climates the necessity of labour +to provide food is far less urgent. + +Our clothing is merely the equivalent for a certain amount of food. + +The more warmly we are clothed the less food we require. If in hunting +or fishing we were exposed to the same degree of cold as the Samoyedes +we could with ease consume ten pounds of flesh, and perhaps half a dozen +tallow candles into the bargain. The macaroni of the Italian, and the +train oil of the Greenlander and the Russian, are fitted to administer +to their comfort in the climate in which they have been born. + +The whole process of respiration appears most clearly developed in the +case of a man exposed to starvation. Currie mentions the case of an +individual who was unable to swallow, and whose body lost 100 lb. in one +month. The more fat an animal contains the longer will it be able to +exist without food, for the fat will be consumed before the oxygen of +the air acts upon the other parts of the body. + +There are various causes by which force or motion may be produced. But +in the animal body we recognise as the ultimate cause of all force only +one cause, the chemical action which the elements of the food and the +oxygen of the air mutually exercise on each other. The only known +ultimate cause of vital force, either in animals or in plants, is a +chemical process. If this be prevented, the phenomena of life do not +manifest themselves, or they cease to be recognisable by our senses. If +the chemical action be impeded, the vital phenomena must take new forms. + +The heat evolved by the combustion of carbon in the body is sufficient +to account for all the phenomena of animal heat. The 14 oz. of carbon +which in an adult are daily converted into carbonic acid disengage a +quantity of heat which would convert 24 lb. of water, at the temperature +of the body, into vapour. And if we assume that the quantity of water +vaporised through the skin and lungs amounts to 3 lb., then we have +still a large quantity of heat to sustain the temperature of the body. + + +_III.--The Chemistry of Blood-Making_ + +Physiologists conceive that the various organs in the body have +originally been formed from blood. If this be admitted, it is obvious +that those substances alone can be considered nutritious that are +capable of being transformed into blood. + +When blood is allowed to stand, it coagulates and separates into a +watery fluid called serum, and into the clot, which consists principally +of fibrine. These two bodies contain, in all, seven elements, among +which sulphur, phosphorus, and nitrogen are found; they contain also the +earth of bones. The serum holds in solution common salt and other salts +of potash and soda, of which the acids are carbonic, phosphoric, and +sulphuric acids. Serum, when heated, coagulates into a white mass called +albumen. This substance, along with the fibrine and a red colouring +matter in which iron is a constituent, constitute the globules of blood. + +Analysis has shown that fibrine and albumen are perfectly identical in +chemical composition. They may be mutually converted into each other. In +the process of nutrition both may be converted into muscular fibre, and +muscular fibre is capable of being reconverted into blood. + +All parts of the animal body which form parts of organs contain +nitrogen. The principal ingredients of blood contain 17 per cent. of +nitrogen, and there is no part of an active organ that contains less +than 17 per cent. of this element. + +The nutritive process is simplest in the case of the carnivora, for +their nutriment is chemically identical in composition with their own +tissues. The digestive apparatus of graminivorous animals is less +simple, and their food contains very little nitrogen. From what +constituents of vegetables is their blood produced? + +Chemical researches have shown that all such parts of vegetables as can +afford nutriment to animals contain certain constituents which are rich +in nitrogen; and experience proves that animals require for their +nutrition less of these parts of plants in proportion as they abound in +the nitrogenised constituents. These important products are specially +abundant in the seeds of the different kinds of grain, and of peas, +beans, and lentils. They exist, however, in all plants, without +exception, and in every part of plants in larger or smaller quantity. +The nitrogenised compounds of vegetables are called vegetable fibrine, +vegetable albumen, and vegetable casein. All other nitrogenised +compounds occurring in plants are either rejected by animals or else +they occur in the food in such very small proportion that they cannot +possibly contribute to the increase of mass in the animal body. + +The chemical analysis of these three substances has led to the +interesting result that they contain the same organic elements, united +in the same proportion by weight; and--which is more remarkable--that +they are identical in composition with the chief constituents of +blood--animal fibrine and animal albumen. By identity, be it remarked, +is not here meant merely similarity, but that even in regard to the +presence and relative amounts of sulphur, phosphorus, and phosphate of +lime no difference can be observed. + +How beautifully simple then, by the aid of these discoveries, appears +the process of nutrition in animals, the formation of their organs, in +which vitality chiefly resides. Those vegetable constituents which are +used by animals to form blood contain the essential ingredients of blood +ready formed. In point of fact, vegetables produce in their organism the +blood of all animals; for the carnivora, in consuming the blood and +flesh of the graminivora, consume, strictly speaking, the vegetable +principles which have served for the nourishment of the latter. In this +sense we may say the animal organism gives to blood only its form; and, +further, that it is incapable of forming blood out of other compounds +which do not contain the chief ingredients of that fluid. + +Animal and vegetable life are, therefore, closely related, for the first +substance capable of affording nutriment to animals is the last product +of the creative energy of vegetables. The seemingly miraculous in the +nutritive power of vegetables disappears in a great degree, for the +production of the constituents of blood cannot appear more surprising +than the occurrence of the principal ingredient of butter in palm-oil +and of horse-fat and train-oil in certain of the oily seeds. + + +_IV.--Food the Fuel of Life_ + +We have still to account for the use in food of substances which are +destitute of nitrogen but are known to be necessary to animal life. Such +substances are starch, sugar, gum, and pectine. In all of these we find +a great excess of carbon, with oxygen and hydrogen in the same +proportion as water. They therefore add an excess of carbon to the +nitrogenised constituents of food, and they cannot possibly be employed +in the production of blood, because the nitrogenised compounds contained +in the food already contain exactly the amount of carbon which is +required for the production of fibrine and albumen. Now, it can be shown +that very little of the excess of this carbon is ever expelled in the +form either of solid or liquid compounds; it must be expelled, +therefore, in the gaseous state. In short, these compounds are solely +expended in the production of animal heat, being converted by the oxygen +of the air into carbonic acid and water. The food of carnivorous animals +does not contain non-nitrogenised matters, so that the carbon and +hydrogen necessary for the production of animal heat are furnished in +them from the waste of their tissues. + +The transformed matters of the organs are obviously unfit for the +further nourishment of the body--that is, for the increase or +reproduction of the mass. They pass through the absorbent and lymphatic +vessels into the veins, and their accumulation in these would soon put a +stop to the nutritive process were it not that the blood has to pass +through a filtering apparatus, as it were, before reaching the heart. +The venous blood, before returning to the heart, is made to pass through +the liver and the kidneys, which separate from it all substances +incapable of contributing to nutrition. The new compounds containing the +nitrogen of the transformed organs, being utterly incapable of further +application in the system, are expelled from the body. Those which +contain the carbon of the transformed tissues are collected in the +gall-bladder as bile, a compound of soda which, being mixed with water, +passes through the duodenum and mixes with chyme. All the soda of the +bile, and ninety-nine-hundredths of the carbonaceous matter which it +contains, retain the capacity of re-absorption by the absorbents of the +small and large intestines--a capacity which has been proved by direct +experiment. + +The globules of the blood, which in themselves can be shown to take no +share in the nutritive process, serve to transport the oxygen which they +give up in their passage through the capillary vessels. Here the current +of oxygen meets with the carbonaceous substances of the transformed +tissues, and converts their carbon into carbonic acid, their hydrogen +into water. Every portion of these substances which escapes this process +of oxidation is sent back into the circulation in the form of bile, +which by degrees completely disappears. + +It is obvious that in the system of the graminivora, whose food contains +relatively so small a proportion of the constituents of blood, the +process of metamorphosis in existing tissues, and consequently their +restoration or reproduction, must go on far less rapidly than in the +carnivora. Otherwise, a vegetation a thousand times as luxuriant would +not suffice for their sustenance. Sugar, gum, and starch, which form so +large a proportion of their food, would then be no longer necessary to +support life in these animals, because in that case the products of +waste, or metamorphosis of organised tissues, would contain enough +carbon to support the respiratory process. + +When exercise is denied to graminivorous and omnivorous animals this is +tantamount to a deficient supply of oxygen. The carbon of the food, not +meeting with a sufficient supply of oxygen to consume it, passes into +other compounds containing a large excess of carbon--or, in other words, +fat is produced. Fat is thus an abnormal production, resulting from a +disproportion of carbon in the food to that of the oxygen respired by +the lungs or absorbed by the skin. Wild animals in a state of nature do +not contain fat. The production of fat is always a consequence of a +deficient supply of oxygen, for oxygen is absolutely indispensable for +the dissipation of excess of carbon in the food. + + +_V.--Animal Life-Chemistry_ + +The substances of which the food of man is composed may be divided into +two classes--into nitrogenised and non-nitrogenised. The former are +capable of conversion into blood, the latter incapable of this +transformation. Out of those substances which are adapted to the +formation of blood are formed all the organised tissues. The other class +of substances in the normal state of health serve to support the process +of respiration. The former may be called the plastic elements of +nutrition; the latter, elements of respiration. + +Among the former we may reckon--vegetable fibrine, vegetable albumen, +vegetable casein, animal flesh, animal blood. + +Among the elements of respiration in our food are--fat, starch, gum, +cane sugar, grape-sugar, sugar of milk, pectine, bassorine, wine, beer, +spirits. + +The nitrogenised constituents of vegetable food have a composition +identical with that of the constituents of the blood. + +No nitrogenised compound the composition of which differs from that of +fibrine, albumen, and casein, is capable of supporting the vital process +in animals. + +The animal organism undoubtedly possesses the power of forming from the +constituents of its blood the substance of its membranes and cellular +tissue, of the nerves and brain, of the organic part of cartilages and +bones. But the blood must be supplied to it ready in everything but its +form--that is, in its chemical composition. If this is not done, a +period is put to the formation of blood, and, consequently, to life. + +The whole life of animals consists of a conflict between chemical forces +and the vital power. In the normal state of the body of an adult these +stand in equilibrium: that is, there is equilibrium between the +manifestations of the causes of waste and the causes of supply. Every +mechanical or chemical agency which disturbs the restoration of this +equilibrium is a cause of disease. + +Death is that condition in which chemical or mechanical powers gain the +ascendancy, and all resistance on the part of the vital force ceases. +This resistance never entirely departs from living tissues during life. +Such deficiency in resistance is, in fact, a deficiency in resistance to +the action of the oxygen of the atmosphere. + +Disease occurs when the sum of vital force, which tends to neutralise +all causes of disturbance, is weaker than the acting cause of +disturbance. + +Should there be formed in the diseased parts, in consequence of the +change of matter, from the elements of the blood or of the tissue, new +products which the neighbouring parts cannot employ for their own vital +functions; should the surrounding parts, moreover, be unable to convey +these products to other parts where they may undergo transformation, +then these new products will suffer, at the place where they have been +formed, a process of decomposition analogous to putrefaction. + +In certain cases, medicine removes these diseased conditions by exciting +in the vicinity of the diseased part, or in any convenient situation, an +artificial diseased state (as by blisters), thus diminishing by means of +artificial disturbance the resistance offered to the external causes of +change in these parts by the vital force. The physician succeeds in +putting an end to the original diseased condition when the disturbance +artificially excited (or the diminution of resistance in another part) +exceeds in amount the diseased state to be overcome. + +The accelerated change of matter and the elevated temperature in the +diseased part show that the resistance offered by the vital force to the +action of oxygen is feebler than in the healthy state. But this +resistance only ceases entirely when death takes place. By the +artificial diminution of resistance in another part, the resistance in +the diseased organ is not, indeed, directly strengthened; but the +chemical action, the cause of the change of matter, is diminished in the +diseased part, being directed to another part, where the physician has +succeeded in producing a still more feeble resistance to the change of +matter, to the action of oxygen. + + + + +SIR CHARLES LYELL + +The Principles of Geology + + Sir Charles Lyell, the distinguished geologist, was born at + Kinnordy, Forfarshire, Scotland, Nov. 14, 1797. It was at Oxford + that his scientific interest was first aroused, and after taking an + M.A. degree in 1821 he continued his scientific studies, becoming + an active member of the Geological and Linnæan Societies of London. + In 1826 he was elected a fellow of the Royal Society, and two years + later went with Sir Roderick Murchison on a tour of Europe, and + gathered evidence for the theory of geological uniformity which he + afterwards promulgated. In 1830 he published his great work, + "Principles of Geology: Being an Attempt to Explain the Former + Changes of the Earth's Surface by References to Causes now in + Action," which converted almost the whole geological world to the + doctrine of uniformitarianism, and may be considered the foundation + of modern geology. Lyell died in London on February 22, 1875. + Besides his great work, he also published "The Elements of + Geology," "The Antiquity of Man," "Travels in North America," and + "The Student's Elements of Geology." + + +_I.--Uniformity in Geological Development_ + +According to the speculations of some writers, there have been in the +past history of the planet alternate periods of tranquillity and +convulsion, the former enduring for ages, and resembling the state of +things now experienced by man; the other brief, transient, and +paroxysmal, giving rise to new mountains, seas, and valleys, +annihilating one set of organic beings, and ushering in the creation of +another. These theories, however, are not borne out by a fair +interpretation of geological monuments; but, on the contrary, nature +indicates no such cataclysms, but rather progressive uniformity. + +Igneous rocks have been supposed to afford evidence of ancient paroxysms +of nature, but we cannot consider igneous rocks proof of any +exceptional paroxysms. Rather, we find ourselves compelled to regard +igneous rocks as an aggregate effect of innumerable eruptions, of +various degrees of violence, at various times, and to consider mountain +chains as the accumulative results of these eruptions. The incumbent +crust of the earth is never allowed to attain that strength and +coherence which would be necessary in order to allow the volcanic force +to accumulate and form an explosive charge capable of producing a grand +paroxysmal eruption. The subterranean power, on the contrary, displays, +even in its most energetic efforts, an intermittent and mitigated +intensity. There are no proofs that the igneous rocks were produced more +abundantly at remote periods. + +Nor can we find proof of catastrophic discontinuity when we examine +fossil plants and fossil animals. On the contrary, we find a progressive +development of organic life at successive geological periods. + +In Palæozoic strata the entire want of plants of the most complex +organisation is very striking, for not a single dicotyledonous +angiosperm has yet been found, and only one undoubted monocotyledon. In +Secondary, or Mesozoic, times, palms and some other monocotyledons +appeared; but not till the Upper Cretaceous era do we meet with the +principal classes and orders of the vegetable kingdom as now known. +Through the Tertiary ages the forms were perpetually changing, but +always becoming more and more like, generically and specifically, to +those now in being. On the whole, therefore, we find progressive +development of plant life in the course of the ages. + +In the case of animal life, progression is equally evident. +Palæontological research leads to the conclusion that the invertebrate +animals flourished before the vertebrate, and that in the latter class +fish, reptiles, birds, and mammalia made their appearance in a +chronological order analogous to that in which they would be arranged +zoologically according to an advancing scale of perfection in their +organisation. In regard to the mammalia themselves, they have been +divided by Professor Owen into four sub-classes by reference to +modifications of their brain. The two lowest are met with in the +Secondary strata. The next in grade is found in Tertiary strata. And the +highest of all, of which man is the sole representative, has not yet +been detected in deposits older than the Post-Tertiary. + +It is true that in passing from the older to the newer members of the +Tertiary system we meet with many chasms, but none which separate +entirely, by a broad line of demarcation, one state of the organic world +from another. There are no signs of an abrupt termination of one fauna +and flora, and the starting into life of new and wholly distinct forms. +Although we are far from being able to demonstrate geologically an +insensible transition from the Eocene to the Miocene, or even from the +latter to the recent fauna, yet the more we enlarge and perfect our +general survey the more nearly do we approximate to such a continuous +series, and the more gradually are we conducted from times when many of +the genera and nearly all the species were extinct to those in which +scarcely a single species flourished which we do not know to exist at +present. We must remember, too, that many gaps in animal and floral life +were due to ordinary climatic and geological factors. We could, under no +circumstances, expect to meet with a complete ascending series. + +The great vicissitudes in climate which the earth undoubtedly +experienced, as shown by geological records, have been held to be +themselves proof of sudden violent revolutions in the life-history of +the world. But all the great climatic vicissitudes can be accounted for +by the action of factors still, in operation--subsidences and elevations +of land, alterations in the relative proportions and position of land +and water, variations in the relative position of our planet to the sun +and other heavenly bodies. + +Altogether, the conclusion is inevitable that from the remotest period +there has been one uniform and continuous system of change in the +animate and inanimate world, and accordingly every fact collected +respecting the factors at present at work in forming and changing the +world, affords a key to the interpretation of its part. And thus, +although we are mere sojourners on the surface of the planet, chained to +a mere point in space, enduring but for a moment of time, the human mind +is enabled not only to number worlds beyond the unassisted ken of mortal +eye, but to trace the events of indefinite ages before the creation of +our race, and to penetrate into the dark secrets of the ocean and the +heart of the solid globe. + + +_II.--Changes in the Inorganic World now in Progress_ + +The great agents of change in the inorganic world may be divided into +two principal classes--the aqueous and the igneous. To the aqueous +belong rain, rivers, springs, currents, and tides, and the action of +frost and snow; to the igneous, volcanoes and earthquakes. Both these +classes are instruments of degradation as well as of reproduction. But +they may also be regarded as antagonist forces, since the aqueous agents +are incessantly labouring to reduce the inequalities of the earth's +surface to a level; while the igneous are equally active in restoring +the unevenness of the external crust, partly by heaping up new matter in +certain localities, and partly by depressing one portion of the earth's +envelope and forcing out another. + +We will treat in the first place of the aqueous agents. + +RAIN AND RIVERS. When one considers that in some parts of the world as +much as 500 or 600 inches of rain may fall annually, it is easy to +believe that rain _qua_ rain may be a denuding and plastic agent, and in +some parts of the world we find evidence of its action in earth pillars +or pyramids. The best example of earth pillars is seen near Botzen, in +the Tyrol, where there are hundreds of columns of indurated mud, varying +in height from 20 feet to 100 feet. These columns are usually capped by +a single stone, and have been separated by rain from the terrace of +which they once formed a part. + +As a rule, however, rain acts through rivers. The power of rivers to +denude and transport is exemplified daily. Even a comparatively small +stream when swollen by rain may move rocks tons in weight, and may +transport thousands of tons of gravel. The greatest damage is done when +rivers are dammed by landslips or by ice. In 1818 the River Dranse was +blocked by ice, and its upper part became a lake. In the hot season the +barrier of ice gave way, and the torrent swept before it rocks, forests, +houses, bridges, and cultivated land. For the greater part of its course +the flood resembled a moving mass of rock and mud rather than of water. +Some fragments of granite rock of enormous size, which might be compared +to houses, were torn out and borne down for a quarter of a mile. + +The rivers of unmelted ice called the glaciers act more slowly, but they +also have the power of transporting gravel, sand, and boulders to great +distances, and of polishing and scoring their rocky channels. Icebergs, +too, are potent geological agents. Many of them are loaded with 50,000 +to 100,000 tons of rock and earth, which they may carry great distances. +Also in their course they must break, and polish, and scratch the peaks +and points of submarine mountains. + +Coast ice, likewise, may transport rocks and earth. Springs also must be +considered as geological agents affecting the face of the globe. + +But running water not only denudes it, but also creates land, for +lakes, seas, rivers are seen to form deltas. That Egypt was the gift of +the Nile was the opinion of the Egyptian priests, and there can be no +doubt that the fertility of the alluvial plain above Cairo, and the very +existence of the delta below that city, are due to the action of that +great river, and to its power of transporting mud from the interior of +Africa and depositing it on its inundated plains as well as on that +space which has been reclaimed from the Mediterranean and converted into +land. The delta of the Ganges and Brahmapootra is more than double that +of the Nile. Even larger is the delta of the Mississippi, which has been +calculated to be 12,300 square miles in area. + +TIDES AND CURRENTS. The transporting and destroying and constructive +power of tides and currents is, in many respects, analogous to that of +rivers, but extends to wider areas, and is, therefore, of more +geological importance. The chief influence of the ocean is exerted at +moderate depths below the surface on all areas which are slowly rising, +or attempting, as it were, to rise above the sea; but its influence is +also seen round the coast of every continent and island. + + * * * * * + +We shall now consider the igneous agents that act on the earth's +surface. These agents are chiefly volcanoes and earthquakes, and we find +that both usually occur in particular parts of the world. At various +times and at various places within historical times volcanic eruptions +and earthquakes have both proved their potency to alter the face of the +earth. + +The principal geological facts and theories with regard to volcanoes and +earthquakes are as follows. + +The primary causes of the volcano and the earthquake are to a great +extent the same, and connected with the development of heat and chemical +action at various depths in the interior of the globe. + +Volcanic heat has been supposed to be the result of the original high +temperature of the molten planet, and the planet has been supposed to +lose heat by radiation. Recent inquiries, however, suggest that the +apparent loss of heat may arise from the excessive local development of +volcanic action. + +Whatever the original shape of our planet, it must in time have become +spheroidal by the gradual operation of centrifugal force acting on +yielding materials brought successively within its action by aqueous and +igneous causes. + +The heat in mines and artesian wells increases as we descend, but not in +uniform ratio in different regions. Increase at a uniform ratio would +imply such heat in the central nucleus as must instantly fuse the crust. + +Assuming that there are good astronomical grounds for inferring the +original fluidity of the planet, yet such pristine fluidity need not +affect the question of volcanic heat, for the volcanic action of +successive periods belongs to a much more modern state of the globe, and +implies the melting of different parts of the solid crust one after the +other. + +The supposed great energy of the volcanic forces in the remoter periods +is by no means borne out by geological observations on the quantity of +lava produced by single eruptions in those several periods. + +The old notion that the crystalline rocks, whether stratified or +unstratified, such as granite and gneiss, were produced in the lower +parts of the earth's crust at the expense of a central nucleus slowly +cooling from a state of fusion by heat has now had to be given up, now +that granite is found to be of all ages, and now that we know the +metamorphic rocks to be altered sedimentary strata, implying the +denudation of a previously solidified crust. + +The powerful agency of steam or aqueous vapour in volcanic eruptions +leads us to compare its power of propelling lava to the surface with +that which it exerts in driving water up the pipe of an Icelandic +geyser. Various gases also, rendered liquid by pressure at great depths, +may aid in causing volcanic outbursts, and in fissuring and convulsing +the rocks during earthquakes. + +The chemical character of the products of recent eruptions suggests that +large bodies of salt water gain access to the volcanic foci. Although +this may not be the primary cause of volcanic eruptions, which are +probably due to the aqueous vapour intimately mixed with molten rock, +yet once the crust is shattered through, the force and frequency of +eruptions may depend in some measure on the proximity of large bodies of +water. + +The permanent elevation and subsidence of land now observed, and which +may have been going on through past ages, may be connected with the +expansion and contraction of parts of the solid crust, some of which +have been cooling from time to time, while others have been gaining +heat. + +In the preservation of the average proportion of land and sea, the +igneous agents exert a conservative power, restoring the unevenness of +the surface which the levelling power of water in motion would tend to +destroy. If the diameter of the planet remains always the same, the +downward movements of the crust must be somewhat in excess, to +counterbalance the effects of volcanoes and mineral springs, which are +always ejecting material so as to raise the level of the surface of the +earth. Subterranean movements, therefore, however destructive they may +be during great earthquakes, are essential to the well-being of the +habitable surface, and even to the very existence of terrestrial and +aquatic species. + + +_III.--Changes of the Organic World now in Progress_ + +In 1809 Lamarck introduced the idea of transmutation of species, +suggesting that by changes in habitat, climate, and manner of living one +species may, in the course of generations, be transformed into a new +and distinct species. + +In England, however, the idea remained dormant till in 1844 a work +entitled the "Vestiges of Creation" reinforced it with many new facts. +In this work the unity of plan exhibited by the whole organic creation, +fossil and recent, and the mutual affinities of all the different +classes of the animal and vegetable kingdoms, were declared to be in +harmony with the idea of new forms having proceeded from older ones by +the gradually modifying influence of environment. In 1858 the theory was +put on a new and sound basis by Wallace and Darwin, who added the +conception of natural selection, suggesting that variations in species +are naturally produced, and that the variety fittest to survive in the +severe struggle for existence must survive, and transmit the +advantageous variation, implying the gradual evolution of new species. +Further, Darwin showed that other varieties may be perpetuated by sexual +selection. + +On investigating the geographical distribution of animals and plants we +find that the extent to which the species of mammalia, birds, insects, +landshells, and plants (whether flowering or cryptogamous) agree with +continental species; or the degree in which those of different islands +of the same group agree with each other has an unmistakable relation to +the known facilities enjoyed by each class of crossing the ocean. Such a +relationship accords well with the theory of variation and natural +selection, but with no other hypothesis yet suggested for explaining the +origin of species. + +From what has been said of the changes which are always going on in the +habitable surface of the world, and the manner in which some species are +constantly extending their range at the expense of others, it is evident +that the species existing at any particular period may, in the course of +ages, become extinct one after the other. + +If such, then, be the law of the organic world, if every species is +continually losing some of its varieties, and every genus some of its +species, it follows that the transitional links which once, according to +the doctrine of transmutation, must have existed, will, in the great +majority of cases, be missing. We learn from geological investigations +that throughout an indefinite lapse of ages the whole animate creation +has been decimated again and again. Sometimes a single representative +alone remains of a type once dominant, or of which the fossil species +may be reckoned by hundreds. We rarely find that whole orders have +disappeared, yet this is notably the case in the class of reptiles, +which has lost some orders characterised by a higher organisation than +any now surviving in that class. Certain genera of plants and animals +which seem to have been wholly wanting, and others which were feebly +represented in the Tertiary period, are now rich in species, and appear +to be in such perfect harmony with the present conditions of existence +that they present us with countless varieties, confounding the zoologist +or botanist who undertakes to describe or classify them. + +We have only to reflect on the causes of extinction, and we at once +foresee the time when even in these genera so many gaps will occur, so +many transitional forms will be lost, that there will no longer be any +difficulty in assigning definite limits to each surviving species. The +blending, therefore, of one generic or specific form into another must +be an exception to the general rule, whether in our own time or in any +period of the past, because the forms surviving at any given moment will +have been exposed for a long succession of antecedent periods to those +powerful causes of extinction which are slowly but incessantly at work +in the organic and inorganic worlds. + +They who imagine that, if the theory of transmutation be true, we ought +to discover in a fossil state all the intermediate links by which the +most dissimilar types have been formerly connected together, expect a +permanence and completeness of records such as is never found. We do not +find even that all recently extinct plants have left memorials of their +existence in the crust of the earth; and ancient archives are certainly +extremely defective. To one who is aware of the extreme imperfection of +the geological record, the discovery of one or two missing links is a +fact of small significance; but each new form rescued from oblivion is +an earnest of the former existence of hundreds of species, the greater +part of which are irrevocably lost. + +A somewhat serious cause of disquiet and alarm arises out of the +supposed bearing of this doctrine of the origin of species by +transmutation on the origin of man, and his place in nature. It is +clearly seen that there is such a close affinity, such an identity in +all essential points, in our corporeal structure, and in many of our +instincts and passions with those of the lower animals--that man is so +completely subjected to the same general laws of reproduction, increase, +growth, disease, and death--that if progressive development, spontaneous +variation, and natural selection have for millions of years directed the +changes of the rest of the organic world, we cannot expect to find that +the human race has been exempted from the same continuous process of +evolution. + +Such a near bond of connection between man and the rest of the animate +creation is regarded by many as derogatory to our dignity. But we have +already had to exchange the pleasing conceptions indulged in by poets +and theologians as to the high position in the scale of being held by +our early progenitors for humble and more lowly beginnings, the joint +labours of the geologist and archæologist having left us in no doubt of +the ignorance and barbarism of Palæolithic man. + +It is well, too, to remember that the high place we have reached in the +scale of being has been gained step by step, by a conscientious study +of natural phenomena, and by fearlessly teaching the doctrines to which +they point. It is by faithfully weighing evidence without regard to +preconceived notions, by earnestly and patiently searching for what is +true, not what we wish to be true, that we have attained to that +dignity, which we may in vain hope to claim through the rank of an ideal +parentage. + + + + +JAMES CLERK MAXWELL + +A Treatise on Electricity and Magnetism + + James Clerk Maxwell, the first professor of experimental physics at + Cambridge, was born at Edinburgh on November 13, 1831, and before + he was fifteen was already famous as a writer of scientific papers. + In 1854 he graduated at Cambridge as second wrangler. Two years + later he became professor of natural philosophy at Marischal + College, Aberdeen. Vacating his chair in 1860 for one at King's + College, London, Maxwell contributed largely to scientific + literature. His great lifework, however, is his famous "Treatise on + Electricity and Magnetism," which was published in 1873, and is, in + the words of a critic, "one of the most splendid monuments ever + raised by the genius of a single individual." It was in this work + that he constructed his famous theory if electricity in which + "action at a distance" should be replaced by "action through a + medium," and first enunciated the principles of an electro-magnetic + theory of light which has formed the basis of nearly all modern + physical science. He died on November 5, 1879. + + +_I.--The Nature of Electricity_ + +Let a piece of glass and a piece of resin be rubbed together. They will +be found to attract each other. If a second piece of glass be rubbed +with a second piece of resin, it will be found that the two pieces of +glass repel each other and that the two pieces of resin are also +repelled from one another, while each piece of glass attracts each piece +of resin. These phenomena of attraction and repulsion are called +electrical phenomena, and the bodies which exhibit them are said to be +"electrified," or to be "charged with electricity." + +Bodies may be electrified in many other ways, as well as by friction. +When bodies not previously electrified are observed to be acted on by an +electrified body, it is because they have become "electrified by +induction." If a metal vessel be electrified by induction, and a second +metallic body be suspended by silk threads near it, and a metal wire be +brought to touch simultaneously the electrified body and the second +body, this latter body will be found to be electrified. Electricity has +been transferred from one body to the other by means of the wire. + +There are many other manifestations of electricity, all of which have +been more or less studied, and they lead to the formation of theories of +its nature, theories which fit in, to a greater or less extent, with the +observed facts. The electrification of a body is a physical quantity +capable of measurement, and two or more electrifications can be combined +experimentally with a result of the same kind as when two quantities are +added algebraically. We, therefore, are entitled to use language fitted +to deal with electrification as a quantity as well as a quality, and to +speak of any electrified body as "charged with a certain quantity of +positive or negative electricity." + +While admitting electricity to the rank of a physical quantity, we must +not too hastily assume that it is, or is not, a substance, or that it +is, or is not, a form of energy, or that it belongs to any known +category of physical quantities. All that we have proved is that it +cannot be created or annihilated, so that if the total quantity of +electricity within a closed surface is increased or diminished, the +increase or diminution must have passed in or out through the closed +surface. + +This is true of matter, but it is not true of heat, for heat may be +increased or diminished within a closed surface, without passing in or +out through the surface, by the transformation of some form of energy +into heat, or of heat into some other form of energy. It is not true +even of energy in general if we admit the immediate action of bodies at +a distance. + +There is, however, another reason which warrants us in asserting that +electricity, as a physical quantity, synonymous with the total +electrification of a body, is not, like heat, a form of energy. An +electrified system has a certain amount of energy, and this energy can +be calculated. The physical qualities, "electricity" and "potential," +when multiplied together, produce the quantity, "energy." It is +impossible, therefore, that electricity and energy should be quantities +of the same category, for electricity is only one of the factors of +energy, the other factor being "potential." + +Electricity is treated as a substance in most theories of the subject, +but as there are two kinds of electrification, which, being combined, +annul each other, a distinction has to be drawn between free electricity +and combined electricity, for we cannot conceive of two substances +annulling each other. In the two-fluid theory, all bodies, in their +unelectrified state, are supposed to be charged with equal quantities of +positive and negative electricity. These quantities are supposed to be +so great than no process of electrification has ever yet deprived a body +of all the electricity of either kind. The two electricities are called +"fluids" because they are capable of being transferred from one body to +another, and are, within conducting bodies, extremely mobile. + +In the one-fluid theory everything is the same as in the theory of two +fluids, except that, instead of supposing the two substances equal and +opposite in all respects, one of them, generally the negative one, has +been endowed with the properties and name of ordinary matter, while the +other retains the name of the electric fluid. The particles of the fluid +are supposed to repel each other according to the law of the inverse +square of the distance, and to attract those of matter according to the +same law. Those of matter are supposed to repel each other and attract +those of electricity. This theory requires us, however, to suppose the +mass of the electric fluid so small that no attainable positive or +negative electrification has yet perceptibly increased or diminished the +mass or the weight of a body, and it has not yet been able to assign +sufficient reasons why the positive rather than the negative +electrification should be supposed due to an _excess_ quantity of +electricity. + +For my own part, I look for additional light on the nature of +electricity from a study of what takes place in the space intervening +between the electrified bodies. Some of the phenomena are explained +equally by all the theories, while others merely indicate the peculiar +difficulties of each theory. We may conceive the relation into which the +electrified bodies are thrown, either as the result of the state of the +intervening medium, or as the result of a direct action between the +electrified bodies at a distance. If we adopt the latter conception, we +may determine the law of the action, but we can go no further in +speculating on its cause. + +If, on the other hand, we adopt the conception of action through a +medium, we are led to inquire into the nature of that action in each +part of the medium. If we calculate on this hypothesis the total energy +residing in the medium, we shall find it equal to the energy due to the +electrification of the conductors on the hypothesis of direct action at +a distance. Hence, the two hypotheses are mathematically equivalent. + +On the hypothesis that the mechanical action observed between +electrified bodies is exerted through and by means of the medium, as the +action of one body on another by means of the tension of a rope or the +pressure of a rod, we find that the medium must be in a state of +mechanical stress. The nature of the stress is, as Faraday pointed out, +a tension along the lines of force combined with an equal pressure in +all directions at right angles to these lines. This distribution of +stress is the only one consistent with the observed mechanical action on +the electrified bodies, and also with the observed equilibrium of the +fluid dielectric which surrounds them. I have, therefore, assumed the +actual existence of this state of stress. + +Every case of electrification or discharge may be considered as a +motion in a closed circuit, such that at every section of the circuit +the same quantity of electricity crosses in the same time; and this is +the case, not only in the voltaic current, where it has always been +recognised, but in those cases in which electricity has been generally +supposed to be accumulated in certain places. We are thus led to a very +remarkable consequence of the theory which we are examining, namely, +that the motions of electricity are like those of an _incompressible_ +fluid, so that the total quantity within an imaginary fixed closed +surface remains always the same. + +The peculiar features of the theory as developed in this book are as +follows. + +That the energy of electrification resides in the dielectric medium, +whether that medium be solid or gaseous, dense or rare, or even deprived +of ordinary gross matter, provided that it be still capable of +transmitting electrical action. + +That the energy in any part of the medium is stored up in the form of a +constraint called polarisation, dependent on the resultant electromotive +force (the difference of potentials between two conductors) at the +place. + +That electromotive force acting on a dielectric produces what we call +electric displacement. + +That in fluid dielectrics the electric polarisation is accompanied by a +tension in the direction of the lines of force combined with an equal +pressure in all directions at right angles to the lines of force. + +That the surfaces of any elementary portion into which we may conceive +the volume of the dielectric divided must be conceived to be +electrified, so that the surface density at any point of the surface is +equal in magnitude to the displacement through that point of the surface +_reckoned inwards_. + +That, whatever electricity may be, the phenomena which we have called +electric displacement is a movement of electricity in the same sense as +the transference of a definite quantity of electricity through a wire. + + +_II.--Theories of Magnetism_ + +Certain bodies--as, for instance, the iron ore called loadstone, the +earth itself, and pieces of steel which have been subjected to certain +treatment--are found to possess the following properties, and are called +magnets. + +If a magnet be suspended so as to turn freely about a vertical axis, it +will in general tend to set itself in a certain azimuth, and, if +disturbed from this position, it will oscillate about it. + +It is found that the force which acts on the body tends to cause a +certain line in the body--called the axis of the magnet--to become +parallel to a certain line in space, called the "direction of the +magnetic force." + +The ends of a long thin magnet are commonly called its poles, and like +poles repel each other; while unlike poles attract each other. The +repulsion between the two magnetic poles is in the straight line joining +them, and is numerically equal to the products of the strength of the +poles divided by the square of the distance between them; that is, it +varies as the inverse square of the distance. Since the form of the law +of magnetic action is identical with that of electric action, the same +reasons which can be given for attributing electric phenomena to the +action of one "fluid," or two "fluids" can also be used in favour of the +existence of a magnetic matter, fluid or otherwise, provided new laws +are introduced to account for the actual facts. + +At all parts of the earth's surface, except some parts of the polar +regions, one end of a magnet points in a northerly direction and the +other in a southerly one. Now a bar of iron held parallel to the +direction of the earth's magnetic force is found to become magnetic. Any +piece of soft iron placed in a magnetic field is found to exhibit +magnetic properties. These are phenomena of _induced_ magnetism. Poisson +supposes the magnetism of iron to consist in a separation of the +magnetic fluids within each magnetic molecule. Weber's theory differs +from this in assuming that the molecules of the iron are always magnets, +even before the application of the magnetising force, but that in +ordinary iron the magnetic axes of the molecules are turned +indifferently in every direction, so that the iron as a whole exhibits +no magnetic properties; and this theory agrees very well with what is +observed. + +The theories establish the fact that magnetisation is a phenomenon, not +of large masses of iron, but of molecules; that is to say, of portions +of the substance so small that we cannot by any mechanical method cut +them in two, so as to obtain a north pole separate from the south pole. +We have arrived at no explanation, however, of the nature of a magnetic +molecule, and we have therefore to consider the hypothesis of +Ampère--that the magnetism of the molecule is due to an electric current +constantly circulating in some closed path within it. + +Ampère concluded that if magnetism is to be explained by means of +electric currents, these currents must circulate within the molecules of +the magnet, and cannot flow from one molecule to another. As we cannot +experimentally measure the magnetic action at a point within the +molecule, this hypothesis cannot be disproved in the same way that we +can disprove the hypothesis of sensible currents within the magnet. In +spite of its apparent complexity, Ampère's theory greatly extends our +mathematical vision into the interior of the molecules. + + +_III.--The Electro-Magnetic Theory of Light_ + +We explain electro-magnetic phenomena by means of mechanical action +transmitted from one body to another by means of a medium occupying the +space between them. The undulatory theory of light also assumes the +existence of a medium. We have to show that the properties of the +electro-magnetic medium are identical with those of the luminiferous +medium. + +To fill all space with a new medium whenever any new phenomena are to be +explained is by no means philosophical, but if the study of two +different branches of science has independently suggested the idea of a +medium; and if the properties which must be attributed to the medium in +order to account for electro-magnetic phenomena are of the same kind as +those which we attribute to the luminiferous medium in order to account +for the phenomena of light, the evidence for the physical existence of +the medium is considerably strengthened. + +According to the theory of emission, the transmission of light energy is +effected by the actual transference of light-corpuscles from the +luminous to the illuminated body. According to the theory of undulation +there is a material medium which fills the space between the two bodies, +and it is by the action of contiguous parts of this medium that the +energy is passed on, from one portion to the next, till it reaches the +illuminated body. The luminiferous medium is therefore, during the +passage of light through it, a receptacle of energy. This energy is +supposed to be partly potential and partly kinetic, and our theory +agrees with the undulatory theory in assuming the existence of a medium +capable of becoming a receptacle for two forms of energy. + +Now, the properties of bodies are capable of quantitative measurement. +We therefore obtain the numerical value of some property of the +medium--such as the velocity with which a disturbance is propagated in +it, which can be calculated from experiments, and also observed directly +in the case of light. If it be found that the velocity of propagation of +electro-magnetic disturbance is the same as the velocity of light, we +have strong reasons for believing that light is an electro-magnetic +phenomenon. + +It is, in fact, found that the velocity of light and the velocity of +propagation of electro-magnetic disturbance are quantities of the same +order of magnitude. Neither of them can be said to have been determined +accurately enough to say that one is greater than the other. In the +meantime, our theory asserts that the quantities are equal, and assigns +a physical reason for this equality, and it is not contradicted by the +comparison of the results, such as they are. + +Lorenz has deduced from Kirchoff's equations of electric currents a new +set of equations, indicating that the distribution of force in the +electro-magnetic field may be considered as arising from the mutual +action of contiguous elements, and that waves, consisting of transverse +electric currents, may be propagated, with a velocity comparable with +that of light, in non-conducting media. These conclusions are similar to +my own, though obtained by an entirely different method. + +The most important step in establishing a relation between electric and +magnetic phenomena and those of light must be the discovery of some +instance in which one set of phenomena is affected by the other. Faraday +succeeded in establishing such a relation, and the experiments by which +he did so are described in the nineteen series of his "Experimental +Researches." Suffice it to state here that he showed that in the case of +aray of plane-polarised light the effect of the magnetic force is to +turn the plane of polarisation round the direction of the ray as an +axis, through a certain angle. + +The action of magnetism on polarised light leads to the conclusion that +in a medium under the action of a magnetic force, something belonging to +the same mathematical class as an angular velocity, whose axis is in the +direction of the magnetic force, forms part of the phenomenon. This +angular velocity cannot be any portion of the medium of sensible +dimensions rotating as a whole. We must, therefore, conceive the +rotation to be that of very small portions of the medium, each rotating +on its own axis. + +This is the hypothesis of molecular vortices. The displacements of the +medium during the propagation of light will produce a disturbance of the +vortices, and the vortices, when so disturbed, may react on the medium +so as to affect the propagation of the ray. The theory proposed is of a +provisional kind, resting as it does on unproved hypotheses relating to +the nature of molecular vortices, and the mode in which they are +affected by the displacement of the medium. + + +_IV.--Action at a Distance_ + +There appears to be some prejudice, or _a priori_ objection, against the +hypothesis of a medium in which the phenomena of radiation of light and +heat, and the electric actions at a distance, take place. It is true +that at one time those who speculated as to the cause of physical +phenomena were in the habit of accounting for each kind of action at a +distance by means of a special æthereal fluid, whose function and +property it was to produce these actions. They filled all space three +and four times over with æthers of different kinds, the properties of +which consisted merely to "save appearances," so that more rational +inquirers were willing to accept not only Newton's definite law of +attraction at a distance, but even the dogma of Cotes that action at a +distance is one of the primary properties of matter, and that no +explanation can be more intelligible than this fact. Hence the +undulatory theory of light has met with much opposition, directed not +against its failure to explain the phenomena, but against its assumption +of the existence of a medium in which light is propagated. + +The mathematical expression for electro-dynamic action led, in the mind +of Gauss, to the conviction that a theory of the propagation of electric +action would in time be found to be the very keystone of +electro-dynamics. Now, we are unable to conceive of propagation in time, +except either as the flight of a material substance through space or as +the propagation of a condition of motion or stress in a medium already +existing in space. + +In the theory of Neumann, the mathematical conception called potential, +which we are unable to conceive as a material substance, is supposed to +be projected from one particle to another, in a manner which is quite +independent of a medium, and which, as Neumann has himself pointed out, +is extremely different from that of the propagation of light. In other +theories it would appear that the action is supposed to be propagated in +a manner somewhat more similar to that of light. + +But in all these theories the question naturally occurs: "If something +is transmitted from one particle to another at a distance, what is its +condition after it had left the one particle, and before it reached the +other?" If this something is the potential energy of the two particles, +as in Neumann's theory, how are we to conceive this energy as existing +in a point of space coinciding neither with the one particle nor with +the other? In fact, whenever energy is transmitted from one body to +another in time, there must be a medium or substance in which the energy +exists after it leaves one body, and before it reaches the other, for +energy, as Torricelli remarked, "is a quintessence of so subtile a +nature that it cannot be contained in any vessel except the inmost +substance of material things." + +Hence all these theories lead to the conception of a medium in which the +propagation takes place, and if we admit this medium as an hypothesis, I +think we ought to endeavour to construct a mental representation of all +the details of its action, and this has been my constant aim in this +treatise. + + + + +ELIE METCHNIKOFF + +The Nature of Man + + Elie Metchnikoff, Sub-Director of the Pasteur Institute in Paris, + was born May 15, 1845, in the province of Kharkov, Russia, and has + worked at the Pasteur Institute since 1888. The greater part of + Metchnikoff's work is concerned with the most intimate processes of + the body, and notably the means by which it defends itself from the + living agents of disease. He is, indeed, the author of a standard + treatise entitled "Immunity in Infective Diseases." His early work + in zoology led him to study the water-flea, and thence to discover + that the white cells of the human blood oppose, consume, and + destroy invading microbes. Latterly, Metchnikoff has devoted + himself in some measure to more general and especially + philosophical studies, the outcome of which is best represented by + the notable volume on "The Nature of Man," which was published at + Paris in 1903. + + +_I.--Disharmonies in Nature_ + +Notwithstanding the real advance made by science, it cannot be disputed +that a general uneasiness disturbs the whole world to-day, and the +frequency of suicide is increased greatly among civilised peoples. Yet +if science turns to study human nature, there may be grounds for hope. +The Greeks held human nature and the human body in high esteem, and +among the Romans such a philosopher as Seneca said, "Take nature as your +guide, for so reason bids you and advises you; to live happily is to +live naturally." In our own day Herbert Spencer has expressed again the +Greek ideal, seeking the foundation of morality in human nature itself. + +But it has often been taught that human nature is composed of two +hostile elements, a body and a soul. The soul alone was to be honoured, +while the body was regarded as the vile source of evils. This doctrine +has had many disastrous consequences, and it is not surprising that in +consequence of it celibacy should have been regarded as the ideal state. +Art fell from the Greek ideal until the Renaissance, with its return to +that ideal, brought new vigour. When the ancient spirit was born again +its influence reached science and even religion, and the Reformation was +a defence of human nature. The Lutheran doctrines resumed the principle +of a "development as complete as possible of all the natural powers" of +man, and compulsory celibacy was abolished. + +The historical diversity of opinion regarding human nature is what has +led me to the attempt to give an exposition of human nature in its +strength and in its weakness. But, before dealing with the man himself, +we must survey the lower forms of life. + +The facts of the organised world, before the appearnace of man, teach us +that though we find change and development, development does not always +take a progressive march. We are bound to believe, for instance, that +the latest products of evolution are not human beings, but certain +parasites which live only upon, or in, the human body. The law in nature +is not of constant progress, but of constant tendency towards +adaptation. Exquisite adaptations, or harmonies, in nature are +constantly met with in the world of living beings. But, on the other +hand, any close investigation of organisation and life reveals that +beside many most perfect harmonies, there are facts which prove the +existence of incomplete harmony, or even absolute disharmony. +Rudimentary and useless organs are widely distributed. Many insects are +exquisitely adapted for sucking the nectar of flowers; many others would +wish to do the same, but their want of adaptation baffles them. + +It is plain that an instinct, or any other form of disharmony, leading +to destruction, cannot increase or even endure very long. The perversion +of the maternal instinct, tending to abandonment of the young, is +destructive to the stock. In consequence, individuals affected by it do +not have the opportunity of transmitting the perversion. If all rabbits, +or a majority of them, left their young to die through neglect, it is +evident that the species would soon die out. On the contrary, mothers +guided by their instinct to nourish and foster their offspring will +produce a vigorous generation capable of transmitting the healthy +maternal instinct so essential for the preservation of the species. For +such a reason harmonious characters are more abundant in nature than +injurious peculiarities. The latter, because they are injurious to the +individual and to the species, cannot perpetuate themselves +indefinitely. + +In this way there comes about a constant selection of characters. The +useful qualities are handed down and preserved, while noxious characters +perish and so disappear. Although disharmonies tend to the destruction +of a species, they may themselves disappear without having destroyed the +race in which they occur. + +This continuous process of natural selection, which offers so good an +explanation of the transmutation and origin of species by means of +preservation of useful and destruction of harmful characters, was +discovered by Darwin and Wallace, and was established by the splendid +researches of the former of these. + +Long before the appearance of man on the face of the earth, there were +some happy beings well adapted to their environment, and some unhappy +creatures that followed disharmonious instincts so as to imperil or to +destroy their lives. Were such creatures capable of reflection and +communication, plainly the fortunate among them, such as orchids and +certain wasps, would be on the side of the optimists; they would declare +this the best of all possible worlds, and insist that to secure +happiness it is necessary only to follow natural instincts. On the other +hand, the disharmonious creatures, those ill adapted to the conditions +of life, would be pessimistic philosophers. Consider the case of the +ladybird, driven by hunger and with a preference for honey, which +searches for it on flowers and meets only with failure, or of insects +driven by their instincts into the flames, only to lose their wings and +their lives; such creatures, plainly, would express as their idea of the +world that it was fashioned abominably, and that existence was a +mistake. + + +_II.--Disharmonies in Man_ + +As for man, the creature most interesting to us, in what category does +he fall? Is he a being whose nature is in harmony with the conditions in +which he has to live, or is he out of harmony with his environment? A +critical examination is needed to answer these questions, and to such an +examination the pages to follow are devoted. + +Science has proved that man is closely akin to the higher monkeys or +anthropoid apes--a fact which we must reckon with if we are to +understand human nature. The details of anatomy which show the kinship +between man and the apes are numerous and astonishing. All the facts +brought to light during the last forty years have supported this truth, +and no single fact has been brought against it. Quite lately it has been +shown that there are remarkable characters in the blood, such that, +though by certain tests the fluid part of human blood can be readily +distinguished from that of any other creature, the anthropoid apes, and +they alone, furnish an exception to this rule. There is thus verily a +close blood-relationship between the human species and the anthropoid +apes. + +But how man arose we do not know. It is probable that he owes his origin +to a mutation--a sudden change comparable with that which De Vries +observed in the case of the evening primrose. The new creature possessed +a brain of abnormal size placed in a spacious cranium which allowed a +rapid development of intellectual faculties. This peculiarity would be +transmitted to the descendants, and as it was a very considerable +advantage in the struggle for existence, the new race would hold its +own, propagate, and prevail. + +Although he is a recent arrival on the earth, man has already made great +progress, as compared with his ancestors the anthropoid apes, and we +learn the same if we compare the higher and lower races of mankind. Yet +there remain many disharmonies in the organisation of man, as, for +instance, in his digestive system. A simple instance of this kind is +furnished by the wisdom teeth. The complete absence of all four wisdom +teeth has no influence on mastication, and their presence is very +frequently the source of illness and danger. In man they are indeed +rudimentary organs, providing another proof of our simian origin. The +vermiform appendix, so frequently the cause of illness and death, is +another rudimentary organ in the human body, together with the part of +the digestive canal to which it is attached. The organ is a very old +part of the constitution of mammals, and it is because it has been +preserved long after its function has disappeared that we find it +occurring in the body of man. + +I believe that not only the appendix, but a very large part of the +alimentary canal is superfluous, and worse than superfluous. It is, of +course, of great importance to the horse, the rabbit, and some other +mammals that live exclusively on grain and herbage. The latter part of +the alimentary canal, however, must be regarded as one of the organs +possessed by man and yet harmful to his health and life. It is the cause +of a series of misfortunes. The human stomach also is of little value, +and can easily be dispensed with, as surgery has proved. It is because +we inherit our alimentary canal from creatures of different dietetic +habits that it is impossible for us to take our nutriment in the most +perfect form. If we were only to eat substances that could be almost +completely absorbed, serious complications would be produced. A +satisfactory system of diet has to make allowance for this, and in +consequence of the structure of the alimentary canal has to include in +the food bulky and indigestible materials, such as vegetables. Lastly, +it may be noted that the instinct of appetite in man is largely +aberrant. The widespread results of alcoholism show plainly the +prevalent existence in man of a want of harmony between the instinct for +choosing food and the instinct of preservation. + +Far stronger than the social instinct, and far older, is the love of +life and the instinct of self-preservation. Devices for the protection +of life were developed long before the evolution of mankind, and it is +quite certain that animals, even those highest in the scale of life, are +unconscious of the inevitability of death and the ultimate fate of all +living things. This knowledge is a human acquisition. It has long been +recognised that the old attach a higher value to life than do the young. +The instinctive love of life and fear of death are of importance in the +study of human nature, impossible to over-estimate. + +The instinctive love of life is preserved in the aged in its strongest +form. I have carefully studied the aged to make certain on this point. +It is a terrible disharmony that the instinctive love of life should +manifest itself so strongly when death is felt to be so near at hand. +Hence the religions of all times have been concerned with the problem of +death. + + +_III.--Science the Only Remedy for Human Disharmonies_ + +In religion and in philosophy throughout their whole history we find +attempts to combat the ills arising from the disharmonies of the human +constitution. + +Ancient and modern philosophies, like ancient and modern religions, have +concerned themselves with the attempt to remedy the ills of human +existence, and instinctive fear of death has always ensured that great +attention has been paid to the doctrine of immortality. + +Science, the youngest daughter of knowledge, has begun to investigate +the great problems affecting humanity. Her first steps, taken along the +lines first clearly laid down by Bacon, were slow and halting. But +medical science has lately made great progress, and has gone very far to +control disease, especially in consequence of the work of Pasteur. It is +said that science has failed because, for instance, tuberculosis +persists, but tuberculosis is propagated not because of the failure of +science, but because of the ignorance and stupidity of the population. +To diminish the spread of tuberculosis, of typhoid fever, of dysentery, +and of many other diseases, it is necessary only to follow the rules of +scientific hygiene without waiting for specific remedies. + +Science offers us much hope also when it is directed to the study of old +age and the phenomena which lead to death. + +Man, who is the descendant of some anthropoid ape, has inherited a +constitution adapted to an environment very different from that which +now surrounds him. He is possessed of a brain very much more highly +developed than that of his ancestors, and has entered on a new path in +the evolution of the higher organisms. The sudden change in his natural +conditions has brought about a large series of organic disharmonies, +which become more and more acutely felt as he becomes more intelligent +and more sensitive; and thus there has arisen a number of sorrows which +poor humanity has tried to relieve by all the means in its power. +Humanity in its misery has put question after question to science, and +has lost patience at the slowness of the advance of knowledge. It has +declared that the answers already found by science are futile and of +little interest. But science, confident of its methods, has quietly +continued to work. Little by little the answers to some of the +questions that have been set have begun to appear. + +Man, because of the fundamental disharmonies in his constitution, does +not develop normally. The earlier phases of his development are passed +through with little trouble; but after maturity greater or lesser +abnormality begins, and ends in old age and death that are premature and +pathological. Is not the goal of existence the accomplishment of a +complete and physiological cycle in which occurs a normal old age, +ending in the loss of the instinct of life and the appearance of the +instinct of death? But before attaining the normal end, coming after the +appearance of the instinct of death, a normal life must be lived; a life +filled all through with the feeling that comes from the accomplishment +of function. Science has been able to tell us that man, the descendant +of animals, has good and evil qualities in his nature, and that his life +is made unhappy by the evil qualities. + +But the constitution of man is not immutable, and perhaps it may be +changed for the better. Morality should be based not on human nature in +its existing condition, but on ideal human nature, as it may be in the +future. Before all things, it is necessary to try to amend the evolution +of human life, that is to say, to transform its disharmonies into +harmonies. This task can be undertaken only by science, and to science +the opportunity of accomplishing it must be given. Before it is possible +to reach the goal mankind must be persuaded that science is all-powerful +and that the deeply-rooted existing superstitions are pernicious. It +will be necessary to reform many customs and many institutions that now +seem to rest on enduring foundations. The abandonment of much that is +habitual, and a revolution in the mode of education, will require long +and painful effort. But the conviction that science alone is able to +redress the disharmonies of the human constitution will lead directly to +the improvement of education and to the solidarity of mankind. + + + + +The Prolongation of Life + + Professor Metchnikoff's volume, on "The Prolongation of Life: + Studies in Optimistic Philosophy," was published in 1907, and is in + some respects the most original of his works. In it he carries much + further the arguments and the studies to which he made brief + allusion in "The Nature of Man," and he lays down certain + principles for the prolongation of life which have been put into + practice by a large number of people during the last two or three + years, and are steadily gaining more attention. Sour milk as an + article of diet appears to have a peculiar value in arresting the + supposed senile changes which are largely due to auto-intoxication + or self-poisoning. + + +_I.--Senile Debility_ + +When we study old age in man and the lower animals, we observe certain +features common to both. But often among vertebrates there are found +animals whose bodies withstand the ravages of time much better than that +of man. I think it a fair inference that senility, that precocious +senescence which is one of the greatest sorrows of humanity, is not so +profoundly seated in the constitution of the higher animals as has +generally been supposed. The first facts which we must accept are that +human beings who reach extreme old age may preserve their mental +qualities, notwithstanding serious physical decay, and that certain of +the higher animals can resist the influence of time much longer than is +the case with man under present conditions. + +Many theories have been advanced regarding the cause of senility. It is +certain that many parts of the body continue to thrive and grow even in +old age, as, for instance, the nails and hair. But I believe that I have +proved that in many parts of the body, especially the higher elements, +such as nervous and muscular cells, there is a destruction due to the +activity of the white cells of the blood. I have shown also that the +blanching of the hair in old age is due to the activity of these white +cells, which destroy the hair pigment. Progressive muscular debility is +an accompaniment of old age; physical work is seldom given to men over +sixty years of age, as it is notorious that they are less capable of it. +Their muscular movements are feebler, and soon bring on fatigue; their +actions are slow and painful. Even old men whose mental vigour is +unimpaired admit their muscular weakness. The physical correlate of this +condition is an actual atrophy of the muscles, and has for long been +known to observers. I have found that the cause of this atrophy is the +consumption of the muscle fibres by what I call phagocytes, or eating +cells, a certain kind of white blood cells. + +In the case of certain diseases we find symptoms, which look like +precocious senility, due to the poison of the disease. It is no mere +analogy to suppose that human senescence is the result of a slow but +chronic poisoning of the organism. Such poisons, if not completely +destroyed or got rid of, weaken the tissues, the functions of which +become altered or enfeebled in which the latter have the advantage. But +we must make further studies before we can answer the question whether +our senescence can be ameliorated. + +The duration of the life of animals varies within very wide limits. As a +general rule, small animals do not live so long as large ones, but there +is no absolute relation between size and longevity, since parrots, +ravens, and geese live much longer than many mammals, and than some much +larger birds. Buffon long ago argued that the total duration of life +bore some definite relation to the length of the period of growth, but +further inquiry shows that such a relation cannot be established. +Nevertheless, there is something intrinsic in each kind of animal which +sets a definite limit to the length of years it can attain. The purely +physiological conditions which determine this limit leave room for a +considerable amount of variation in longevity. Duration of life, +therefore, is a character which can be influenced by the environment. + +The duration of life in mammals is relatively shorter than in birds, and +in the so-called cold-blooded vertebrates. No indication as to the cause +of this difference can be found elsewhere than in the organs of +digestion. Mammals are the only group of vertebrate animals in which the +large intestine is much developed. This part of the alimentary canal is +not important, for it fulfils no notable digestive function. On the +other hand, it accommodates among the intestinal flora many microbes +which damage health by poisoning the body with their products. Among the +intestinal flora there are many microbes which are inoffensive, but +others are known to have pernicious properties, and auto-intoxication, +or self-poisoning, is the cause of the ill-health which may be traced to +their activity. It is indubitable that the intestinal microbes or their +poisons may reach the system generally, and bring harm to it. I infer +from the facts that the more the digestive tract is charged with +microbes, the more it is a source of harm capable of shortening life. As +the large intestine not only is that part of the digestive tube most +richly charged with microbes, but is relatively more capacious in +mammals than in any other vertebrates, it is a just inference that the +duration of life of mammals has been notably shortened as the result of +chronic poisoning from an abundant intestinal flora. + +When we come to study the duration of human life, it is impossible to +accept the view that the high mortality between the ages of seventy and +seventy-five indicates a natural limit to human life. The fact that many +men from seventy to seventy-five years old are well preserved, both +physically and intellectually, makes it impossible to regard that age as +the natural limit of human life. Philosophers such as Plato, poets such +as Goethe and Victor Hugo, artists such as Michael Angelo, Titian, and +Franz Hals, produced some of their most important works when they had +passed what some regard as the limit of life. Moreover, deaths of people +at that age are rarely due to senile debility. Centenarians are really +not rare. In France, for instance, nearly 150 centenarians die every +year, and extreme longevity is not limited to the white races. Women +more frequently become centenarians than men--a fact which supports the +general proposition that male mortality is always greater than that of +the other sex. + +It has been noticed that most centenarians have been people who were +poor or in humble circumstances, and whose life has been extremely +simple. It may well be said that great riches do not bring a very long +life. Poverty generally brings with it sobriety, especially in old age, +and sobriety is certainly favourable to long life. + + +_II.--The Study of Natural Death_ + +It is surprising to find how little science really knows about death. By +natural death I mean to denote death due to the nature of the organism, +and not to disease. We may ask whether natural death really occurs, +since death so frequently comes by accident or by disease; and certainly +the longevity of many plants is amazing. Such ages as three, four, and +five thousand years are attributed to the baobab at Cape Verd, certain +cypresses, and the sequoias of California. It is plain that among the +lower and higher plants there are cases where natural death does not +exist; and, further, so far as I can ascertain, it looks as if poisons +produced by their own bodies were the cause of natural death among the +higher plants where it does occur. + +In the human race cases of what may be called natural death are +extremely rare; the death of old people is usually due to infectious +disease, particularly pneumonia, or to apoplexy. The close analogy +between natural death and sleep supports my view that it is due to an +auto-intoxication of the organism, since it is very probable that sleep +is due to "poisoning" by the products of organic activity. + +Although the duration of the life of man is one of the longest amongst +mammals, men find it too short. Ought we to listen to the cry of +humanity that life is too short, and that it will be well to prolong it? +If the question were merely one of prolonging the life of old people, +without modifying old age itself, the answer would be doubtful. It must +be understood, however, that the prolongation of life will be associated +with the preservation of intelligence and of the power to work. When we +have reduced or abolished such causes of precocious senility as +intemperance and disease, it will no longer be necessary to give +pensions at the age of sixty or seventy years. The cost of supporting +the old, instead of increasing, will diminish progressively. We must use +all our endeavors to allow men to complete their normal course of life, +and to make it possible for old men to play their parts as advisers and +judges, endowed with their long experience of life. + +From time immemorial suggestions have been made for the prolongation of +life. Many elixirs have been sought and supposed to have been found, but +general hygienic measures have been the most successful in prolonging +life and in lessening the ills of old age. That is the teaching of Sir +Herman Weber, himself of very great age, who advises general hygienic +principles, and especially moderation in all respects. He advises us to +avoid alcohol and other stimulants, as well as narcotics and soothing +drugs. Certainly the prolongation of life which has come to pass in +recent centuries must be attributed to the advance of hygiene; and if +hygiene was able to prolong life when little developed, as was the case +until recently, we may well believe that with our greater knowledge a +much better result will be obtained. + + +_III.--The Use of Lactic Acid_ + +The general measures of hygiene directed against infectious diseases +play a part in prolonging the lives of old people; but, in addition to +the microbes which invade the body from outside, there is a rich source +of harm in microbes which inhabit the body. The most important of these +belong to the intestinal flora which is abundant and varied. Now the +attempt to destroy the intestinal microbes by the use of chemical agents +has little chance of success, and the intestine itself may be harmed +more than the microbes. If, however, we observe the new-born child we +find that, when suckled by its mother, its intestinal microbes are very +different and much fewer than if it be fed with cows' milk. I am +strongly convinced that it is advantageous to protect ourselves by +cooking all kinds of food which, like cows' milk, are exposed to the +air. It is well-known that other means--as, for instance, the use of +lactic acid--will prevent food outside the body from going bad. Now as +lactic fermentation serves so well to arrest putrefaction in general, +why should it not be used for the same purpose within the digestive +tube? It has been clearly proved that the microbes which produce lactic +acid can, and do, control the growth of other microbes within the body, +and that the lactic microbe is so much at home in the human body that it +is to be found there several weeks after it has been swallowed. + +From time immemorial human beings have absorbed quantities of lactic +microbes by consuming in the uncooked condition substances such as +soured milk, kephir, sauerkraut, or salted cucumbers, which have +undergone lactic fermentation. By these means they have unknowingly +lessened the evil consequences of intestinal putrefaction. The fact that +so many races make soured milk and use it copiously is an excellent +testimony to its usefulness, and critical inquiry shows that longevity, +with few traces of senility, is conspicuous amongst peoples who use sour +milk extensively. + +A reader who has little knowledge of such matters may be surprised by my +recommendation to absorb large quantities of microbes, as the general +belief is that microbes are all harmful. This belief, however, is +erroneous. There are many useful microbes, amongst which the lactic +bacilli have an honourable place. If it be true that our precocious and +unhappy old age is due to poisoning of the tissues, the greater part of +the poison coming from the large intestine, inhabited by numberless +microbes, it is clear that agents which arrest intestinal putrefaction +must at the same time postpone and ameliorate old age. This theoretical +view is confirmed by the collection of facts regarding races which live +chiefly on soured milk, and amongst which great ages are common. + + +_IV.--An Ideal Old Age_ + +As I have shown in the "Nature of Man," the human constitution as it +exists to-day, being the result of a long evolution and containing a +large animal element, cannot furnish the basis of rational morality. The +conception which has come down from antiquity to modern times, of a +harmonious activity of all the organs, is no longer appropriate to +mankind. Organs which are in course of atrophy must not be re-awakened, +and many natural characters which, perhaps, were useful in the case of +animals, must be made to disappear in men. + +Human nature which, like the constitutions of other organisms, is +subject to evolution, must be modified according to a definite ideal. +Just as a gardener or stock-raiser is not content with the existing +nature of the plants and animals with which he is occupied, but modifies +them to suit his purposes, so also the scientific philosopher must not +think of existing human nature as immutable, but must try to modify it +for the advantage of mankind. As bread is the chief article in the human +food, attempts to improve cereals have been made for a very long time, +but in order to obtain results much knowledge is necessary. To modify +the nature of plants, it is necessary to understand them well, and it is +necessary to have an ideal to be aimed at. In the case of mankind the +ideal of human nature, towards which we ought to press, may be formed. +In my opinion this ideal is "orthobiosis"--that is to say, the +development of human life, so that it passes through a long period of +old age in active and vigorous health, leading to a final period in +which there shall be present a sense of satiety of life, and a wish for +death. + +Just as we must study the nature of plants before trying to realise our +ideal, so also varied and profound knowledge is the first requisite for +the ideal of moral conduct. It is necessary not only to know the +structure and functions of the human organism, but to have exact ideas +on human life as it is in society. Scientific knowledge is so +indispensable for moral conduct that ignorance must be placed among the +most immoral acts. A mother who rears her child in defiance of good +hygiene, from want of knowledge, is acting immorally towards her +offspring, notwithstanding her feeling of sympathy. And this also is +true of a government which remains in ignorance of the laws which +regulate human life and human society. + +If the human race come to adopt the principles of orthobiosis, a +considerable change in the qualities of men of different ages will +follow. Old age will be postponed so much that men of from sixty to +seventy years of age will retain their vigour, and will not require to +ask assistance in the fashion now necessary. On the other hand, young +men of twenty-one years of age will no longer be thought mature or ready +to fulfil functions so difficult as taking a share in public affairs. +The view which I set forth in the "Nature of Man" regarding the danger +which comes from the present interference of young men in political +affairs has since then been confirmed in the most striking fashion. + +It is easily intelligible that in the new conditions such modern idols +as universal suffrage, public opinion, and the _referendum_, in which +the ignorant masses are called on to decide questions which demand +varied and profound knowledge, will last no longer than the old idols. +The progress of human knowledge will bring about the replacement of such +institutions by others, in which applied morality will be controlled by +the really competent persons. I permit myself to suppose that in these +times scientific training will be much more general than it is just now, +and that it will occupy the place which it deserves in education and in +life. + +Our intelligence informs us that man is capable of much, and, therefore, +we hope that he may be able to modify his own nature and transform his +disharmonies into harmonies. It is only human will that can attain this +ideal. + + + + +HUGH MILLER + +The Old Red Sandstone + + Hugh Miller was born in Cromarty, in the North of Scotland, October + 10, 1802. From the time he was seventeen until he was thirty-four, + he worked as a common stone-mason, although devoting his leisure + hours to independent researches in natural history, for which he + formed a taste early in life. He became interested in journalism, + and was editor of the Edinburgh "Witness," when, in 1840, he + published the contents of the volume issued a year later as "The + Old Red Sandstone." The book deals with its author's most + distinctive work, namely, finding fossils that tell much of the + history of the Lower Old Red Sandstone, and fixing in the + geological scale the place to which the larger beds of remains + found in the system belong. Besides being a practical and original + geologist, Miller had a fine imaginative power, which enabled him + to reconstruct the past from its ruinous relics. The fact that he + unfortunately set himself the task of combating the theory of + evolution, which was fast gaining ground in his day, should not + blind us to the high value of his geological experiences. The + results of his observations provide some of the most cogent proofs + of the theory he disputed. Late in life Miller's mind gave way, and + he put an end to his own life on December 24, 1856. + + +_I.--A Stone-mason's Researches_ + +My advice to young working men desirous of bettering their +circumstances, and adding to the amount of their enjoyment, is to seek +happiness in study. Learn to make a right use of your eyes; the +commonest things are worth looking at--even stones, weeds, and the most +familiar animals. There are none of the intellectual or moral faculties, +the exercise of which does not lead to enjoyment; hence it is that +happiness bears so little reference to station. + +Twenty years ago I made my first acquaintance with a life of labour and +restraint. I was but a slim, loose-jointed boy at the time, fond of the +pretty intangibilities of romance, and of dreaming when broad awake; +and, woful change! I was now going to work in a quarry. I was going to +exchange all my day-dreams for the kind of life in which men toil every +day that they may be enabled to eat, and eat every day that they may be +enabled to toil! + +That first day was no very formidable beginning of the course of life I +had so much dreaded. To be sure, my hands were a little sore, and I felt +nearly as much fatigued as if I had been climbing among the rocks; but I +had wrought and been useful, and had yet enjoyed the day fully as much +as usual. I was as light of heart next morning as any of my +brother-workmen. That night, arising out of my employment, I found I had +food enough for thought without once thinking of the unhappiness of a +life of labour. + +In the course of the day I picked up a nodular mass of blue limestone, +and laid it open by a stroke of the hammer. Wonderful to relate, it +contained inside a beautifully finished piece of sculpture, one of the +volutes, apparently, of an Ionic capital. Was there another such +curiosity in the whole world? I broke open a few other nodules of +similar appearance, and found that there might be. In one of these there +were what seemed to be scales of fishes and the impressions of a few +minute bivalves, prettily striated; in the centre of another there was +actually a piece of decayed wood. + +Of all nature's riddles these seemed to me to be at once the most +interesting and the most difficult to expound. I treasured them +carefully up, and was told by one of the workmen to whom I showed them +that there was a part of the shore, about two miles further to the west, +where curiously shaped stones, somewhat like the heads of +boarding-pikes, were occasionally picked up, and that in his father's +day the country people called them thunderbolts. Our first half-holiday +I employed in visiting the place where the thunderbolts had fallen so +thickly, and found it a richer scene of wonder than I could have +fancied even in my dreams. + +My first year of labour came to a close, and I found that the amount of +my happiness had not been less than in the last of my boyhood. My +knowledge had increased in more than the ratio of former seasons; and as +I had acquired the skill of at least the common mechanic, I had fitted +myself for independence. + +My curiosity, once fully awakened, remained awake, and my opportunities +of gratifying it have been tolerably ample. I have been an explorer of +caves and ravines, a loiterer along sea-shores, a climber among rocks, a +labourer in quarries. My profession was a wandering one. I remember +passing direct, on one occasion, from the wild western coast of +Ross-shire, where the Old Red Sandstone leans at a high angle against +the prevailing quartz of the district, to where, on the southern skirts +of Midlothian, the Mountain Limestone rises amid the coal. I have +resided one season on a raised beach of the Moray Firth. I have spent +the season immediately following amid the ancient granite and contorted +schists of the central Highlands. In the north I have laid open by +thousands the shells and lignites of the oolite; in the south I have +disinterred from their matrices of stone or of shale the huge reds and +tree ferns of the carboniferous period. + +I advise the stone-mason to acquaint himself with geology. Much of his +time must be spent amid the rocks and quarries of widely separated +localities, and so, in the course of a few years he may pass over the +whole geological scale, and this, too, with opportunities of observation +at every stage which can be shared with him by only the gentleman of +fortune who devotes his whole time to study. Nay, in some respects, his +advantages are superior to those of the amateur, for the man whose +employments have to be carried on in the same formation for months, +perhaps years, enjoys better opportunities of arriving at just +conclusions. There are formations which yield their organisms slowly to +the discoverer, and the proofs which establish their place in the +geological scale more tardily still. I was acquainted with the Old Red +Sandstone of Ross and Cromarty for nearly ten years ere I ascertained +that it is richly fossiliferous; I was acquainted with it for nearly ten +years more ere I could assign its fossils to their exact place in the +scale. Nature is vast and knowledge limited, and no individual need +despair of adding to the general fund. + + +_II.--Bridging Life's Gaps_ + +"The Old Red Sandstone," says a Scottish geologist in a digest of some +recent geological discoveries, "has hitherto been considered as +remarkably barren of fossils." Only a few years have gone by since men +of no low standing in the science disputed the very existence of this +formation--or system, rather, for it contains at least three distinct +formations. There are some of our British geologists who still regard it +as a sort of debatable tract, entitled to no independent status, a sort +of common which should be divided. + +It will be found, however, that this hitherto neglected system yields in +importance to none of the others, whether we take into account its +amazing depth, the great extent to which it is developed both at home +and abroad, the interesting links which it furnishes in the geological +scale, or the vast period of time which it represents. There are +localities in which the depth of the Old Red Sandstone fully equals the +elevation of Mount Etna over the level of the sea, and in which it +contains three distinct groups of organic remains, the one rising in +beautiful progression over the other. + +My first statement regarding the system must be much the reverse of the +one just quoted, for the fossils are remarkably numerous and in a state +of high preservation. I have a hundred solid proofs by which to +establish the truth of the assertion within less than a yard of me. Half +my closet walls are covered with the peculiar fossils of the Lower Old +Red Sandstone; and certainly a stranger assemblage of forms has rarely +been grouped together--creatures whose very type is lost, fantastic and +uncouth, which puzzle the naturalist to assign them even to their class; +boat-like animals, furnished with oars and a rudder; fish, plated over, +like the tortoise, above and below, with a strong armour of bone, and +furnished with but one solitary rudder-like fin; other fish with the +membranes of their fins thickly covered with scales; creatures bristling +over with thorns; others glistening in an enamelled coat, as if +beautifully japanned; the tail in every instance among the less +equivocal shapes formed not equally, as in existing fish, on each side +the central vertebral column, but chiefly on the lower side--the column +sending out its diminished vertebræ to the extreme termination of the +fin. All the forms testify of a remote antiquity. The figures on a +Chinese vase or an Egyptian obelisk are scarce more unlike what now +exists in nature than are the fossils of the Lower Old Red Sandstone. + +Lamarck, on the strength of a few striking facts which prove that to a +certain extent the instincts of species may be improved and heightened, +has concluded that there is a natural progress from the inferior orders +of being towards the superior, and that the offspring of creatures low +in the scale may belong to a different and nobler species a few thousand +years hence. Never was there a fancy so wild and extravagant. The +principle of adaptation still leaves the vegetable a vegetable, and the +dog a dog. It is true that it is a law of nature that the chain of being +is in some degree a continuous chain, and the various classes of +existence shade into each other. All the animal families have their +connecting links. Geology abounds with creatures of the intermediate +class. + +Fishes seem to have been the master existences of two great geological +systems, mayhap of three, ere the age of reptiles began. Now, fishes +differ very much among themselves, some ranking nearly as low as worms, +some nearly as high as reptiles; and we find in the Old Red Sandstone +series of links which are wanting in the present creation, and the +absence of which occasions a wide gap between the two grand divisions of +fishes, the bony and the cartilaginous. + +Of all the organisms of the system one of the most extraordinary is the +pterichthys, or winged fish, which the writer had the pleasure of +introducing to the acquaintance of geologists. Had Lamarck been the +discoverer he would unquestionably have held that he had caught a fish +almost in the act of wishing itself into a bird. There are wings which +want only feathers, a body which seems to have been as well adapted for +passing through the air as through water, and a tail with which to +steer. + +My first idea regarding it was that I had discovered a connecting +link-between the tortoise and the fish. I submitted some of my specimens +to Mr. Murchison, and they furnished him with additional data by which +to construct the calculations he was then making respecting fossils, and +they added a new and very singular link to the chain of existence in its +relation to human knowledge. Agassiz confirmed the conclusions of +Murchison in almost every particular, deciding at once that the creature +must have been a fish. + +Next to the pterichthys of the Lower Old Red Sandstone I shall place its +contemporary the coccosteus of Agassiz--a fish which in some respects +must have resembled it. Both were covered with an armour of thickly +tubercled bony plates, and both furnished with a vertebrated tail. The +coccosteus seems to have been most abundant. Another of the families of +the ichthyolites of the Old Red Sandstone--the cephalaspis--seems +almost to constitute a connecting link between fishes and crustaceans. +In the present creation fishes are either osseous or cartilaginous, that +is, with bony skeletons, or with a framework of elastic, +semi-transparent animal matter, like the shark; and the ichthyolites of +the Old Red Sandstone unite these characteristics, resembling in some +respects the osseous and in others the cartilaginous tribes. Agassiz at +once confirmed my suspicion that the ichthyolites of the Old Red +Sandstone were intermediate. Though it required skill to determine the +place of the pterichthys and coccosteus there could be no mistaking the +osteolepis--it must have been a fish, and a handsome one, too. But while +its head resembled the heads of the bony fishes, its tail differed in no +respects from the tails of the cartilaginous ones. And so through the +discovery of extinct species the gaps between existing species have been +bridged. + + +_III.--Place-Fixing in the Dim Past_ + +The next step was to fix the exact place of the ichthyolites in the +geological scale, and this I was enabled to do by finding a large and +complete bed _in situ_. Its true place is a little more than a hundred +feet above the top, and not much more than a hundred yards above the +base of the great conglomerate. + +The Old Red Sandstone in Scotland and in England has its lower, middle, +and upper groups--three distinct formations. As the pterichthys and +coccosteus are the characteristic ichthyolites of the Lower Old Red +formation, so the cephalaspis distinguishes the middle or coronstone +division of the system in England. When we pass to the upper formation, +we find the holoptychius the most characteristic fossil. + +These fossils are found in a degree of entireness which depends less on +their age than on the nature of the rock in which they occur. Limestone +is the preserving salt of the geological world, and the conservative +qualities of the shales and stratified clays of the Lower Old Red +Sandstone are not much inferior to limestone itself; while in the Upper +Old Red the beds of consolidated sand are much less conservative of +organic remains. The older fossils, therefore, can be described almost +as minutely as the existence of the present creation, whereas the newer +fossils exist, except in a few rare cases, as fragments, and demand the +powers of a Cuvier or an Agassiz to restore them to their original +combinations. On the other hand, while the organisms of the Lower Old +Red are numerous and well preserved, those of the Upper Old Red are much +greater in individual size. In short, the fish of the lower ocean must +have ranged in size between a stickleback and a cod; whereas some of the +fish of the ocean of the Upper Sandstone were covered with scales as +large as oyster shells, and were armed with teeth that rivalled in size +those of the crocodile. + + +_IV.--Fish as Nature's Last Word_ + +I will now attempt to present to the reader the Old Red Sandstone as it +existed in time--during the succeeding periods of its formation, and +when its existences lived and moved as the denizens of primeval oceans. +We pass from the cemetery with its heaps of bones to the ancient city +full of life and animation in all its streets and dwellings. + +Before we commence our picture, two great geological periods have come +to their close, and the floor of the widely spread ocean is occupied to +the depth of many thousand feet by the remains of bygone existences. The +rocks of these two earlier periods are those of the Cambrian and +Silurian groups. The lower--Cambrian, representative of the first +glimmering twilight of being--must be regarded as a period of +uncertainty. It remains for future discoverers to determine regarding +the shapes of life that burrowed in its ooze or careered through the +incumbent waters. + +There is less doubt respecting the existences of the Silurian rocks. +Four distinct platforms of being range in it, the one over the other, +like the stories of a building. Life abounded on all these platforms, +and in shapes the most wonderful. In the period of the Upper Silurian +fish, properly so called, and of a very perfect organisation, had taken +precedence of the crustacean. These most ancient beings of their class +were cartilaginous fishes, and they appear to have been introduced by +myriads. Such are the remains of what seem to have been the first +vertebrata. + +The history of the period represented by the Old Red Sandstone seems, in +what now forms the northern half of Scotland, to have opened amid +confusion and turmoil. The finely laminated Tilestones of England were +deposited evidently in a calm sea. During the contemporary period the +space which now includes Orkney, Lochness, Dingwall, Gamrie, and many a +thousand square miles besides, was the scene of a shallow ocean, +perplexed by powerful currents and agitated by waves. A vast stratum of +water-rolled pebbles, varying in depth from a hundred feet to a hundred +yards, remains, in a thousand different localities, to testify to the +disturbing agencies of this time of commotion, though it is difficult to +conceive how the bottom of any sea could have been so violently and +equally agitated for so greatly extended a space. + +The period of this shallow and stormy ocean passed, and the bottom, +composed of the identical conglomerate which now forms the summit of +some of our loftiest mountains, sank to a depth so profound as to be +little affected by tides and tempests. During this second period there +took place a vast deposit of coarse sandstone strata, and the subsidence +continued until fully ninety feet had overlaid the conglomerate in +waters perfectly undisturbed. And here we find the first proof that this +ancient ocean literally swarmed with life--that its bottom was covered +with miniature forests of algae, and its waters darkened by immense +shoals of fish. I have seen the ichthyolite bed where they were as +thickly covered with fossil remains as I have ever seen a fishing-bank +covered with herrings. + +At this period some terrible catastrophe involved in sudden destruction +the fish of an area at least a hundred miles from boundary to boundary, +perhaps much more. The same platform in Orkney as in Cromarty is strewn +thick with remains which exhibit unequivocally the marks of violent +death. In what could it have originated? By what quiet but potent agency +of destruction could the innumerable existences of an area perhaps ten +thousand miles in extent be annihilated at once, and yet the medium in +which they lived be left undisturbed by its operations? The thought has +often struck me that calcined lime, cast out as ashes from some distant +crater and carried by the winds, might have been the cause of the widely +spread destruction to which the fossil organisms testify. I have seen +the fish of a small trouting stream, over which a bridge was in the +course of building, destroyed in a single hour, for a full mile below +the erection, by a few troughfuls of lime that fell into the water when +the centring was removed. + +The period of death passed, and over the innumerable dead there settled +a soft muddy sediment. For an unknown space of time, represented in the +formation by a deposit about fifty feet in thickness, the waters of the +depopulated area seem to have remained devoid of life. A few scales and +plates then begin to appear. The fish that had existed outside the chasm +seem to have gradually gained upon it as their numbers increased. + +The work of deposition went on and sandstone was overlaid by stratified +clay. This upper bed had also its organisms, but the circumstances were +less favourable to the preservation of entire ichthyolites than those in +which the organisms were wrapped up in their stony coverings. Age +followed age, generations were entombed in ever-growing depositions. +Vast periods passed, and it seemed as if the power of the Creator had +reached its extreme limit when fishes had been called into existence, +and our planet was destined to be the dwelling-place of no nobler +inhabitants. + +The curtain rises, and the scene is new. The myriads of the lower +formation have disappeared, and we are surrounded on an upper platform +by the existences of a later creation. Shoals of cephalaspides, +feathered with fins, sweep past. We see the distant gleam of scales, +that some of the coats glitter with enamel, that others bristle over +with minute thorny points. A huge crustacean, of uncouth proportions, +stalks over the weedy bottoms, or burrows in the hollows of the banks. +Ages and centuries pass--who can sum up their number?--for the depth of +this middle formation greatly exceeds that of the other two. + +The curtain rises. A last day had at length come to the period of the +middle formation, and in an ocean roughened by waves and agitated by +currents we find new races of existences. We may mark the clumsy bulk of +the Holoptychius conspicuous in the group. The shark family have their +representative as before; a new variety of the pterichthys spreads out +its spear-like wings at every alarm, like its predecessor of the lower +formation. Fish still remained the lords of creation, and their bulk, at +least, had become immensely more great. We began with an age of dwarfs, +we end with an age of giants, which is carried on into the lower coal +measures. We pursue our history no further? + +Has the last scene in the series arisen? Cuvier asked the question, +hesitated, and then decided in the negative, for he was too intimately +acquainted with the works of the Creator to think of limiting His power, +and he could anticipate a coming period in which man would have to +resign his post of honour to some nobler and wiser creature, the monarch +of a better and happier world. + + + + +SIR ISAAC NEWTON + +Principia + + Sir Isaac Newton was born at Woolsthorpe, Lincolnshire, England, + Dec. 25, 1642, the son of a small landed proprietor. For the famous + episode of the falling apple, Voltaire, who admirably explained his + system for his countrymen, is responsible. It was in 1680 that + Newton discovered how to calculate the orbit of a body moving under + a central force, and showed that if the force varied as the inverse + square of the distance, the orbit would be an ellipse with the + centre of force in one focus. The great discovery, which made the + writing of his "Philosophiæ Naturalis Principia Mathematica" + possible, was that the attraction between two spheres is the same + as it would be if we supposed each sphere condensed to a point at + its centre. The book was published as a whole in 1687. Of its + author it was said by Lagrange that not only was he the greatest + genius that ever existed, but also the most fortunate, "for we + cannot find more than once a system of the world to establish." + Newton died on March 20, 1727. + + +Our design (writes Newton in his preface) not respecting arts but +philosophy, and our subject not manual but natural powers, we consider +those things which relate to gravity, levity, elastic force, the +resistance of fluids and the like forces, whether attractive or +impulsive; and, therefore, we offer this work as the mathematical +principles of philosophy, for all the difficulty of philosophy seems to +consist in this--from the phenomena of motions to investigate the forces +of nature, and from these forces to demonstrate the other phenomena, and +to this end the general propositions in the first and second book are +directed. In the third book, we give an example of this in the +explication of the system of the world; for by the propositions +mathematically demonstrated in the former books, we in the third derive +from the celestial phenomena the forces of gravity with which bodies +tend to the sun and the several planets. Then from these forces, by +other propositions which are also mathematical, we deduce the motions of +the planets, the comets, the moon, and the sea. + +Upon this subject I had (he says) composed the third book in a popular +method, that it might be read by many, but afterward, considering that +such as had not sufficiently entered into the principles could not +easily discern the strength of the consequences, nor lay aside the +prejudices to which they had been many years accustomed, therefore, to +prevent the disputes which might be raised upon such accounts, I chose +to reduce the substance of this book into the form of Propositions (in +the mathematical way). So that this third book is composed both "in +popular method" and in the form of mathematical propositions. + + +_Books I and II_ + +The principle of universal gravitation, namely, "That every particle of +matter is attracted by or gravitates to every other particle of matter +with a force inversely proportional to the squares of their distances," +is the discovery which characterises the "Principia." This principle the +author deduced from the motion of the moon and the three laws of Kepler; +and these laws in turn Newton, by his greater law, demonstrated to be +true. + +From the first law of Kepler, namely, the proportionality of the areas +to the times of their description, Newton inferred that the force which +retained the planet in its orbit was always directed to the sun. From +the second, namely, that every planet moves in an ellipse with the sun +as one of foci, he drew the more general inference that the force by +which the planet moves round that focus varies inversely as the square +of its distance therefrom. He demonstrated that a planet acted upon by +such a force could not move in any other curve than a conic section; and +he showed when the moving body would describe a circular, an elliptical, +a parabolic, or hyperbolic orbit. He demonstrated, too, that this force +or attracting, gravitating power resided in even the least particle; but +that in spherical masses it operates as if confined to their centres, so +that one sphere or body will act upon another sphere or body with a +force directly proportional to the quantity of matter and inversely as +the square of the distance between their centres, and that their +velocities of mutual approach will be in the inverse ratio of their +quantities of matter. Thus he outlined the universal law. + + +_The System of the World_ + +It was the ancient opinion of not a few (writes Newton in Book III.) in +the earliest ages of philosophy that the fixed stars stood immovable in +the highest parts of the world; that under the fixed stars the planets +were carried about the sun; that the earth, as one of the planets, +described an annual course about the sun, while, by a diurnal motion, it +was in the meantime revolved about its own axis; and that the sun, as +the common fire which served to warm the whole, was fixed in the centre +of the universe. It was from the Egyptians that the Greeks derived their +first, as well as their soundest notions of philosophy. It is not to be +denied that Anaxagoras, Democritus and others would have it that the +earth possessed the centre of the world, but it was agreed on both sides +that the motions of the celestial bodies were performed in spaces +altogether free and void of resistance. The whim of solid orbs was[1] of +later date, introduced by Endoxus, Calippus and Aristotle, when the +ancient philosophy began to decline. + +As it was the unavoidable consequence of the hypothesis of solid orbs +while it prevailed that the comets must be thrust down below the moon, +so no sooner had the late observations of astronomers restored the +comets to their ancient places in the higher heavens than these +celestial spaces were at once cleared of the encumbrance of solid orbs, +which by these observations were broken to pieces and discarded for +ever. + +Whence it was that the planets came to be retained within any certain +bounds in these free spaces, and to be drawn off from the rectilinear +courses, which, left to themselves, they should have pursued, into +regular revolutions in curvilinear orbits, are questions which we do not +know how the ancients explained; and probably it was to give some sort +of satisfaction to this difficulty that solid orbs were introduced. + +The later philosophers pretend to account for it either by the action of +certain vortices, as Kepler and Descartes, or by some other principle of +impulse or attraction, for it is most certain that these effects must +proceed from the action of some force or other. This we will call by the +general name of a centripetal force, as it is a force which is directed +to some centre; and, as it regards more particularly a body in that +centre, we call it circum-solar, circum-terrestrial, circum-jovial. + + +_Centre-Seeking Forces_ + +That by means of centripetal forces the planets may be retained in +certain orbits we may easily understand if we consider the motions of +projectiles, for a stone projected is by the pressure of its own weight +forced out of the rectilinear path, which, by the projection alone, it +should have pursued, and made to describe a curve line in the air; and +through that crooked way is at last brought down to the ground, and the +greater the velocity is with which it is projected the further it goes +before it falls to earth. We can, therefore, suppose the velocity to be +so increased that it would describe an arc of 1, 2, 5, 10, 100, 1,000 +miles before it arrived at the earth, till, at last, exceeding the +limits of the earth, it should pass quite by it without touching it. + +And because the celestial motions are scarcely retarded by the little or +no resistance of the spaces in which they are performed, to keep up the +parity of cases, let us suppose either that there is no air about the +earth or, at least, that it is endowed with little or no power of +resisting. + +And since the areas which by this motion it describes by a radius drawn +to the centre of the earth have previously been shown to be proportional +to the times in which they are described, its velocity when it returns +to the point from which it started will be no less than at first; and, +retaining the same velocity, it will describe the same curve over and +over by the same law. + +But if we now imagine bodies to be projected in the directions of lines +parallel to the horizon from greater heights, as from 5, 10, 100, 1,000 +or more miles, or, rather, as many semi-diameters of the earth, those +bodies, according to their different velocity and the different force of +gravity in different heights, will describe arcs either concentric with +the earth or variously eccentric, and go on revolving through the +heavens in those trajectories just as the planets do in their orbs. + +As when a stone is projected obliquely, the perpetual deflection thereof +towards the earth is a proof of its gravitation to the earth no less +certain than its direct descent when suffered to fall freely from rest, +so the deviation of bodies moving in free spaces from rectilinear paths +and perpetual deflection therefrom towards any place, is a sure +indication of the existence of some force which from all quarters impels +those bodies towards that place. + +That there are centripetal forces actually directed to the bodies of +the sun, of the earth, and other planets, I thus infer. + +The moon revolves about our earth, and by radii drawn to its centre +describes areas nearly proportional to the times in which they are +described, as is evident from its velocity compared with its apparent +diameter; for its motion is slower when its diameter is less (and +therefore its distance greater), and its motion is swifter when its +diameter is greater. + +The revolutions of the satellites of Jupiter about the planet are more +regular; for they describe circles concentric with Jupiter by equable +motions, as exactly as our senses can distinguish. + +And so the satellites of Saturn are revolved about this planet with +motions nearly circular and equable, scarcely disturbed by any +eccentricity hitherto observed. + +That Venus and Mercury are revolved about the sun is demonstrable from +their moon-like appearances. And Venus, with a motion almost uniform, +describes an orb nearly circular and concentric with the sun. But +Mercury, with a more eccentric motion, makes remarkable approaches to +the sun and goes off again by turns; but it is always swifter as it is +near to the sun, and therefore by a radius drawn to the sun still +describes areas proportional to the times. + +Lastly, that the earth describes about the sun, or the sun about the +earth, by a radius from one to the other, areas exactly proportional to +the times is demonstrable from the apparent diameter of the sun compared +with its apparent motion. + +These are astronomical experiments; from which it follows that there are +centripetal forces actually directed to the centres of the earth, of +Jupiter, of Saturn, and of the sun.[2] + +That these forces decrease in the duplicate proportion of the distances +from the centre of every planet appears by Cor. vi., Prop. iv., Book +I.[3] for the periodic times of the satellites of Jupiter are one to +another in the sesquiplicate proportion of their distances from the +centre of this planet. Cassini assures us that the same proportion is +observed in the circum-Saturnal planets. In the circum-solar planets +Mercury and Venus, the same proportional holds with great accuracy. + +That Mars is revolved about the sun is demonstrated from the phases +which it shows and the proportion of its apparent diameters; for from +its appearing full near conjunction with the sun and gibbous in its +quadratures,[4] it is certain that it travels round the sun. And since +its diameter appears about five times greater when in opposition to the +sun than when in conjunction therewith, and its distance from the earth +is reciprocally as its apparent diameter, that distance will be about +five times less when in opposition to than when in conjunction with the +sun; but in both cases its distance from the sun will be nearly about +the same with the distance which is inferred from its gibbous appearance +in the quadratures. And as it encompasses the sun at almost equal +distances, but in respect of the earth is very unequally distant, so by +radii drawn to the sun it describes areas nearly uniform; but by radii +drawn to the earth it is sometimes swift, sometimes stationary, and +sometimes retrograde. + +That Jupiter in a higher orbit than Mars is likewise revolved about the +sun with a motion nearly equable as well in distance as in the areas +described, I infer from Mr. Flamsted's observations of the eclipses of +the innermost satellite; and the same thing may be concluded of Saturn +from his satellite by the observations of Mr. Huyghens and Mr. Halley. + +If Jupiter was viewed from the sun it would never appear retrograde or +stationary, as it is seen sometimes from the earth, but always to go +forward with a motion nearly uniform. And from the very great inequality +of its apparent geocentric motion we infer--as it has been previously +shown that we may infer--that the force by which Jupiter is turned out +of a rectilinear course and made to revolve in an orbit is not directed +to the centre of the earth. And the same argument holds good in Mars and +in Saturn. Another centre of these forces is, therefore, to be looked +for, about which the areas described by radii intervening may be +equable; and that this is the sun, we have proved already in Mars and +Saturn nearly, but accurately enough in Jupiter. + +The distances of the planets from the sun come out the same whether, +with Tycho, we place the earth in the centre of the system, or the sun +with Copernicus; and we have already proved that, these distances are +true in Jupiter. Kepler and Bullialdus have with great care determined +the distances of the planets from the sun, and hence it is that their +tables agree best with the heavens. And in all the planets, in Jupiter +and Mars, in Saturn and the earth, as well as in Venus and Mercury, the +cubes of their distances are as the squares of their periodic times; +and, therefore, the centripetal circum-solar force throughout all the +planetary regions decreases in the duplicate proportion of the distances +from the sun. Neglecting those little fractions which may have arisen +from insensible errors of observation, we shall always find the said +proportion to hold exactly; for the distances of Saturn, Jupiter, Mars, +the Earth, Venus, and Mercury from the sun, drawn from the observations +of astronomers, are (Kepler) as the numbers 951,000, 519,650, 152,350, +100,000, 70,000, 38,806; or (Bullialdus) as the numbers 954,198, +522,520, 152,350, 100,000, 72,398, 38,585; and from the periodic times +they come out 953,806, 520,116, 152,399, 100,000, 72,333, 38,710. Their +distances, according to Kepler and Bullialdus, scarcely differ by any +sensible quantity, and where they differ most the differences drawn from +the periodic times fall in between them. + + +_Earth as a Centre_ + +That the circum-terrestrial force likewise decreases in the duplicate +proportion of the distances, I infer thus: + +The mean distance of the moon from the centre of the earth is, we may +assume, sixty semi-diameters of the earth; and its periodic time in +respect of the fixed stars 27 days 7 hr. 43 min. Now, it has been shown +in a previous book that a body revolved in our air, near the surface of +the earth supposed at rest, by means of a centripetal force which should +be to the same force at the distance of the moon in the reciprocal +duplicate proportion of the distances from the centre of the earth, that +is, as 3,600 to 1, would (secluding the resistance of the air) complete +a revolution in 1 hr. 24 min. 27 sec. + +Suppose the circumference of the earth to be 123,249,600 Paris feet, +then the same body deprived of its circular motion and falling by the +impulse of the same centripetal force as before would in one second of +time describe 15-1/12 Paris feet. This we infer by a calculus formed +upon Prop. xxxvi. ("To determine the times of the descent of a body +falling from a given place"), and it agrees with the results of Mr. +Huyghens's experiments of pendulums, by which he demonstrated that +bodies falling by all the centripetal force with which (of whatever +nature it is) they are impelled near the surface of the earth do in one +second of time describe 15-1/12 Paris feet. + +But if the earth is supposed to move, the earth and moon together will +be revolved about their common centre of gravity. And the moon (by Prop, +lx.) will in the same periodic time, 27 days 7 hr. 43 min., with the +same circum-terrestrial force diminished in the duplicate proportion of +the distance, describe an orbit whose semi-diameter is to the +semi-diameter of the former orbit, that is, to the sixty semi-diameters +of the earth, as the sum of both the bodies of the earth and moon to the +first of two mean proportionals between this sum and the body of the +earth; that is, if we suppose the moon (on account of its mean apparent +diameter 31-1/2 min.) to be about 1/42 of the earth, as 43 to (42 + +42^2)^1/3 or as about 128 to 127. And, therefore, the semi-diameter of +the orbit--that is, the distance of the centres of the moon and +earth--will in this case be 60-1/2 semi-diameters of the earth, almost +the same with that assigned by Copernicus; and, therefore, the duplicate +proportion of the decrement of the force holds good in this distance. +(The action of the sun is here disregarded as inconsiderable.) + +This proportion of the decrement of the forces is confirmed from the +eccentricity of the planets, and the very slow motion of their apsides; +for in no other proportion, it has been established, could the +circum-solar planets once in every revolution descend to their least, +and once ascend to their greatest distance from the sun, and the places +of those distances remain immovable. A small error from the duplicate +proportion would produce a motion of the apsides considerable in every +revolution, but in many enormous. + + +_The Tides_ + +While the planets are thus revolved in orbits about remote centres, in +the meantime they make their several rotations about their proper axes: +the sun in 26 days, Jupiter in 9 hr. 56 min., Mars in 24-2/3 hr., Venus +in 23 hr., and in like manner is the moon revolved about its axis in 27 +days 7 hr. 43 min.; so that this diurnal motion is equal to the mean +motion of the moon in its orbit; upon which account the same face of the +moon always respects the centre about which this mean motion is +performed--that is, the exterior focus of the moon's orbit nearly. + +By reason of the diurnal revolutions of the planets the matter which +they contain endeavours to recede from the axis of this motion; and +hence the fluid parts, rising higher towards the equator than about the +poles, would lay the solid parts about the equator under water if those +parts did not rise also; upon which account the planets are something +thicker about the equator than about the poles. + +And from the diurnal motion and the attractions of the sun and moon our +sea ought twice to rise and twice to fall every day, as well lunar as +solar. But the two motions which the two luminaries raise will not +appear distinguished but will make a certain mixed motion. In the +conjunction or opposition of the luminaries their forces will be +conjoined and bring on the greatest flood and ebb. In the quadratures +the sun will raise the waters which the moon depresseth and depress the +waters which the moon raiseth; and from the difference of their forces +the smallest of all tides will follow. + +But the effects of the lumniaries depend upon their distances from the +earth, for when they are less distant their effects are greater and when +more distant their effects are less, and that in the triplicate +proportion of their apparent diameters. Therefore it is that the sun in +winter time, being then in its perigee, has a greater effect, whether +added to or subtracted from that of the moon, than in the summer season, +and every month the moon, while in the perigee raiseth higher tides than +at the distance of fifteen days before or after when it is in its +apogee. + +The fixed stars being at such vast distances from one another, can +neither attract each other sensibly nor be attracted by our sun. + + +_Comets_ + +There are three hypotheses about comets. For some will have it that they +are generated and perish as often as they appear and vanish; others that +they come from the regions of the fixed stars, and are near by us in +their passage through the sytem of our planets; and, lastly, others that +they are bodies perpetually revolving about the sun in very eccentric +orbits. + +In the first case, the comets, according to their different velocities, +will move in conic sections of all sorts; in the second they will +describe hyperbolas; and in either of the two will frequent +indifferently all quarters of the heavens, as well those about the poles +as those towards the ecliptic; in the third their motions will be +performed in eclipses very eccentric and very nearly approaching to +parabolas. But (if the law of the planets is observed) their orbits will +not much decline from the plane of the ecliptic; and, so far as I could +hitherto observe, the third case obtains; for the comets do indeed +chiefly frequent the zodiac, and scarcely ever attain to a heliocentric +latitude of 40 degrees. And that they move in orbits very nearly +parabolical, I infer from their velocity; for the velocity with which a +parabola is described is everywhere to the velocity with which a comet +or planet may be revolved about the sun in a circle at the same +distance in the subduplicate ratio of 2 to 1; and, by my computation, +the velocity of comets is found to be much about the same. I examined +the thing by inferring nearly the velocities from the distances, and the +distances both from the parallaxes and the phenomena of the tails, and +never found the errors of excess or defect in the velocities greater +than what might have arisen from the errors in the distances collected +after that manner. + + + + +SIR RICHARD OWEN + +Anatomy of Vertebrates + + Sir Richard Owen, the great naturalist, was born July 20, 1804, at + Lancaster, England, and received his early education at the grammar + school of that town. Thence he went to Edinburgh University. In + 1826 he was admitted a member of the English College of Surgeons, + and in 1829 was lecturing at St. Bartholomew's Hospital, London, + where he had completed his studies. His "Memoir on the Pearly + Nautillus," published in 1832, placed him, says Huxley, "at a bound + in the front rank of anatomical monographers," and for sixty-two + years the flow of his contributions to scientific literature never + ceased. In 1856 he was appointed to take charge of the natural + history departments of the British Museum, and before long set + forth views as to the inadequacy of the existing accommodation, + which led ultimately to the foundation of the buildings now devoted + to this purpose in South Kensington. Owen died on December 18, + 1892. His great book, "Comparative Anatomy and Physiology of the + Vertebrates," was completed in 1868, and since Cuvier's + "Comparative Anatomy," is the most monumental treatise on the + subject by any one man. Although much of the classification adopted + by Owen has not been accepted by other zoologists, yet the work + contains an immense amount of information, most of which was gained + from Owen's own personal observations and dissections. + + +_I.--Biological Questions of 1830_ + +At the close of my studies at the Jardin des Plantes, Paris, in 1831, I +returned strongly moved to lines of research bearing upon the then +prevailing phases of thought on some biological questions. + +The great master in whose dissecting rooms I was privileged to work held +that species were not permanent as a fact established inductively on a +wide basis of observation, by which comparative osteology had been +created. Camper and Hunter suspected the species might be transitory; +but Cuvier, in defining the characters of his anaplotherium and +palæotherium, etc., proved the fact. Of the relation of past to present +species, Cuvier had not an adequate basis for a decided opinion. +Observation of changes in the relative position of land and sea +suggested to him one condition of the advent of new species on an island +or continent where old species had died out. This view he illustrates by +a hypothetical case of such succession, but expressly states: "I do not +assert that a new creation was necessary to produce the species now +existing, but only that they did not exist in the same regions, and must +have come from elsewhere." Geoffrey Saint Hilaire opposed to Cuvier's +inductive treatment of the question the following expression of belief: +"I have no doubt that existing animals are directly descended from the +animals of the antediluvian world," but added, "it is my belief that the +season has not yet arrived for a really satisfying knowledge of +geology." + +The main collateral questions argued in their debates appeared to me to +be the following: + +Unity of plan or final purpose, as a governing condition of organic +development? + +Series of species, uninterrupted or broken by intervals? + +Extinction, cataclysmal or regulated? + +Development, by epigenesis or evolution? + +Primary life, by miracle or secondary law? + +Cuvier held the work of organisation to be guided and governed by final +purpose or adaptation. Geoffrey denied the evidence of design and +contended for the principle which he called "unity of composition," as +the law of organisation. Most of his illustrations were open to the +demonstration of inaccuracy; and the language by which disciples of the +kindred school of Schelling illustrated in the animal structure the +transcendental idea of the whole in every part seemed little better than +mystical jargon. With Cuvier, answerable parts occurred in the +zoological scale because they had to perform similar functions. + +As, however, my observations and comparisons accumulated, they enforced +a reconsideration of Cuvier's conclusions. To demonstrate the evidence +of the community of organisation I found the artifice of an archetype +vertebrate animal essential; and from the demonstration of its +principle, which I then satisfied myself was associated with and +dominated by that of "adaptation to purpose," the step was inevitable to +the conception of the operation of a secondary cause of the entire +series of species, such cause being the servant of predetermining +intelligent will. + +But besides "derivation" or "filiation" another principle influencing +organisation became recognisable, to which I gave the name of +"irrelative repetition," or "vegetative repetition." The demonstrated +constitution of the vertebrate endoskeleton as a series of essentially +similar segments appeared to me to illustrate the law of irrelative +repetition. + +These results of inductive research swayed me in rejecting direct or +miraculous creation, and in recognising a "natural law or secondary +cause" as operative in the production of species "in orderly succession +and progression." + + +_II.--Succession of Species, Broken or Linked?_ + +To the hypothesis that existing are modifications of extinct species, +Cuvier replied that traces of modification were due from the fossil +world. "You ought," he said, "to be able to show the intermediate forms +between the palæotherium and existing hoofed quadrupeds." + +The progress of palæontology since 1830 has brought to light many +missing links unknown to the founder of the science. The discovery of +the remains of the hipparion supplied one of the links required by +Cuvier, and it is significant that the remains of such three-toed horses +are found only in deposits of that tertiary period which intervene +between the older palæotherian one and the newer strata in which the +modern horse first appears to have lost its lateral hooflets. + +The molar series of the horse includes six large complex grinders +individually recognisable by developmental characters. The +representative of the first premolar is minute and soon shod. Its +homologue in palæotherium is functionally developed and retained, that +type-dentition being adhered to. In hipparion this tooth is smaller than +in palæotherium, but functional and permanent. The transitory and +singularly small and simple denticle in the horse exemplifies the +rudiment of an ancestral structure in the same degree as do the hoofless +splint-bones; just as the spurious hoofs dangling therefrom in hipparion +are retained rudiments of the functionally developed lateral hoofs in +the broader foot of palæotherium. + +Other missing links of this series of species have also been supplied. + +How then is the origin of these intermediate gradations to be +interpreted? If the alternative--species by miracle or by law--be +applied to palæotherium, paloplotherium, anchitherium, hipparion, equus, +I accept the latter without misgiving, and recognise such law as +continuously operative throughout tertiary time. + +In respect to its law of operation we may suppose Lamarck to say, "as +the surface of the earth consolidated, the larger and more produced +mid-hoof of the old three-toed pachyderius took a greater share in +sustaining the animal's weight; and more blood being required to meet +the greater demand of the more active mid-toe, it grew; whilst, the +side-toes, losing their share of nourishment and becoming more and more +withdrawn from use, shrank"--and so on. Mr. Darwin, I conceive, would +modify this by saying that some individuals of palæotherium happening to +be born with a larger and longer middle toe, and with shorter and +smaller side-toes, such variety was better adapted to prevailing altered +conditions of the earth's surface than the parental form; and so on, +until finally the extreme equine modifications of foot came to be +"naturally selected." But the hypothesis of appetency and volition, as +of natural selection, are less applicable, less intelligible, in +connection with the changes in the teeth. + +I must further observe that to say the palæotherium has graduated into +equus by "natural selection" is an explanation of the process of the +same kind and value as that by which the secretion of bile was +attributed to the "appetency" of the liver for the elements of bile. +One's surprise is that such explanatory devices should not have died out +with the "archeus faber," the "nisus formations," and other +self-deceiving, world-beguiling simulacra of science, with the last +century; and that a resuscitation should have had any success in the +present. + +What, then, are the facts on which any reasonable or intelligible +conception can be formed of the mode of operation of the derivative law +exemplified in the series linking on palæotherium to equus? A very +significant one is the following. A modern horse occasionally comes into +the world with the supplementary ancestral hoofs. From Valerius Maximus, +who attributes the variety to Bucephalus downwards, such "polydactyle" +horses have been noted as monsters and marvels. In one of the latest +examples, the inner splint-bone, answering to the second metacarpal of +the pentadactyle foot, supported phalanges and a terminal hoof +resembling the corresponding one in hipparion. And the pairing of horses +with the meterpodials bearing, according to type, phalanges and hoofs +might restore the race of hipparions. + +Now, the fact suggesting such possibility teaches that the change would +be sudden and considerable; it opposes the idea that species are +transmuted by minute and slow degrees. It also shows that a species +might originate independently of the operation of any external +influence; that change of structure would precede that of use and +habit; that appetency, impulse, ambient medium, fortuitous fitness of +surrounding circumstances, or a personified "selecting nature" would +have had no share in the transmutative act. + +Thus I have been led to recognise species as exemplifying the continuous +operation of natural law, or secondary cause; and that not only +successively but progressively; "from the first embodiment of the +vertebrate idea under its old ichthyic vestment until it became arrayed +in the glorious garb of the human form." + + +_III.--Extinction--Cataclysmal or Regulated_ + +If the species of palæothere, paloplothere, anchithere, hipparion, and +horse be severally deemed due to remotely and successively repeated acts +of creation; the successive going out of such species must have been as +miraculous as their coming in. Accordingly, in Cuvier's "Discourse on +Revolutions of the Earth's Surface" we have a section of "Proofs that +these revolutions have been numerous," and another of "Proofs that these +revolutions have been sudden." But as the discoveries of palæontologists +have supplied the links between the species held to have perished by the +cataclysms, so each successive parcel of geological truth has tended to +dissipate the belief in the unusually sudden and violent nature of the +changes recognisable in the earth's surface. In specially directing my +attention to this moot point, whilst engaged in investigations of fossil +remains, I was led to recognise one cause of extinction as being due to +defeat in the contest which the individual of each species had to +maintain against the surrounding agencies which might militate against +its existence. This principle has received a large and most instructive +accession of illustrations from the labours of Charles Darwin; but he +aims to apply it not only to the extinction but to the origin of +species. + +Although I fail to recognise proof of the latter bearing of the battle +of life, the concurrence of so much evidence in favour of extinction by +law is, in like measure, corroborative of the truth of the ascription of +the origin of species to a secondary cause. + +What spectacle can be more beautiful than that of the inhabitants of the +calm expanse of water of an atoll encircled by its ring of coral rock! +Leaving locomotive frequenters of the calcarious basin out of the +question, we may ask, Was direct creation after the dying out of its +result as a "rugose coral" repeated to constitute the succeeding and +superseding "tabulate coral"? Must we also invoke the miraculous power +to initiate every distinct species of both rugosa and tabulata? These +grand old groups have had their day and are utterly gone. When we +endeavour to conceive or realise such mode of origin, not of them only +but of their manifold successors, the miracle, by the very +multiplication of its manifestations, becomes incredible--inconsistent +with any worthy conception of an all-seeing, all-provident Omnipotence. + +Being unable to accept the volitional hypothesis (of Lamarck) or the +selective force exerted by outward circumstances (Darwin), I deem an +innate tendency to deviate from parental type, operating through periods +of adequate duration, to be the most probable way of operation of the +secondary law whereby species have been derived one from another. + +According to my derivative hypothesis a change takes place first in the +structure of the animal, and this, when sufficiently advanced, may lead +to modifications of habits. But species owe as little to the accidental +concurrence of environing circumstances as kosmos depends upon a +fortuitous concourse of atoms. A purposive route of development and +change of correlation and inter-dependence, manifesting intelligent +will, is as determinable in the succession of races as in the +development and organisation of the individual. + +Derivation holds that every species changes in time, by virtue of +inherent tendencies thereto. Natural selection holds that no such change +can take place without the influence of altered external circumstances +educing or eliciting such change. + +Derivation sees among the effects of the innate tendency to change, +irrespective of altered surrounding circumstances, a manifestation of +creative power in the variety and beauty of the results; and, in the +ultimate forthcoming of a being susceptible of appreciating such beauty, +evidence of the preordaining of such relation of power to the +appreciation. Natural selection acknowledges that if power or beauty, in +itself, should be a purpose in creation, it would be absolutely fatal to +it as a hypothesis. + +Natural selection sees grandeur in the "view of life, with its several +powers, having been originally breathed by the Creator into a few forms +or into one." Derivation sees, therein, a narrow invocation of a special +miracle and an unworthy limitation of creative power, the grandeur of +which is manifested daily, hourly, in calling into life many forms, by +conversion of physical and chemical into vital modes of force, under as +many diversified conditions of the requisite elements to be so combined. + +Natural selection leaves the subsequent origin and succession of species +to the fortuitous concurrence of outward conditions; derivation +recognises a purpose in the defined and preordained course, due to +innate capacity or power of change, by which homogeneously-created +protozoa have risen to the higher forms of plants and animals. + +The hypothesis of derivation rests upon conclusions from four great +series of inductively established facts, together with a probable result +of facts of a fifth class; the hypothesis of natural selection totters +on the extension of a conjectural condition explanatory of extinction to +the origination of species, inapplicable in that extension to the +majority of organisms, and not known or observed to apply to the origin +of any species. + + +_IV.--Epigenesis or Evolution?_ + +The derivative origin of species, then, being at present the most +admissible one, and the retrospective survey of such species showing +convergence, as time recedes, to more simplified or generalised +organisations, the result to which the suggested train of thought +inevitably leads is very analogous in each instance. If to kosmos or the +mundane system have been allotted powers equivalent to the development +of the several grades of life, may not the demonstrated series of +conversions of force have also included that into the vital form? + +In the last century, physiologists were divided as to the principle +guiding the work of organic development. + +The "evolutionists" contended that the new being preexisted in a +complete state of formation, needing only to be vivified by impregnation +in order to commence the series of expansions or disencasings, +culminating in the independent individual. + +The "epigenesists" held that both the germ and its subsequent organs +were built up of juxtaposed molecules according to the operation of a +developmental force, or "nisus formations." + +At the present day the question may seem hardly worth the paper on which +it is referred to. Nevertheless, "pre-existence of germs" and evolution +are logically inseparable from the idea of species by primary +miraculously-created individuals. Cuvier, therefore, maintained both as +firmly as did Haller. In the debates of 1830 I remained the thrall of +that dogma in regard to the origin of single-celled organisms whether in +or out of body. Every result of formfaction, I believed, with most +physiologists, to be the genetic outcome of a pre-existing "cell." The +first was due to miraculous interposition and suspension of ordinary +laws; it contained potentially all future possible cells. +Cell-development exemplified evolution of pre-existing germs, the +progeny of the primary cell. They progagated themselves by +self-division, or by "proliferation" of minutes granules or atoms, +which, when properly nourished, again multiplied by self-division, and +grew to the likeness of the parent cells. + +It seems to me more consistent with the present phase of dynamical +science and the observed graduations of living things to suppose the +sarcode or the "protogenal" jelly-speck should be formable through the +concurrence of conditions favouring such combination of their elements, +and involving a change of force productive of their contractions and +extensions, molecular attractions, and repulsions--and the sarcode has +so become, from the period when its irrelative repetitions resulted in +the vast indefinite masses of the "eozoon," exemplifying the earliest +process of "formification" or organic crystallisation--than that all +existing sarcodes or "protogenes" are the result of genetic descent from +a germ or cell due to a primary act of miraculous interposition. + +I prefer, while indulging in such speculations, to consider the various +daily nomogeneously developed forms of protozoal or protistal jellies, +sarcodes, and single-celled organisms, to have been as many roots from +which the higher grades have ramified than that the origin of the whole +organic creation is to be referred, as the Egyptian priests did that of +the universe, to a single egg. + +Amber or steel, when magnetised, seem to exercise "selection"; they do +not attract all substances alike. A speck of protogenal jelly or +sarcode, if alive, shows analogous relations to certain substances; but +the soft yielding tissue allows the part next the attractive matter to +move thereto, and then, by retraction, to draw such matter into the +sarcodal mass, which overspreads, dissolves, and assimilates it. The +term "living" in the one case is correlative with the term "magnetic" in +the other. A man perceives ripe fruit; he stretches out his hand, +plucks, masticates, swallows, and digests it. + +The question then arises whether the difference between such series of +actions in the man and the attractive and assimilative movement of the +amæba be greater or less than the difference between these acts of the +amæba and the attracting and retaining acts of the magnet. + +The question, I think, may be put with some confidence as to the quality +of the ultimate reply whether the amæbal phenomena are so much more +different, or so essentially different, from the magnetic phenomena than +they are from the mammalian phenomena, as to necessitate the invocation +of a special miracle for their manifestation. It is analogically +conceivable that the same cause which has endowed His world with power +convertible into magnetic, electric, thermotic and other forms or modes +of force, has also added the conditions of conversion into the vital +force. + +From protozoa or protista to plants and animals the graduation is closer +than from magnetised iron to vitalised sarcode. From reflex acts of the +nervous system animals rise to sentient and volitional ones. And with +the ascent are associated brain-cells progressively increasing in size +and complexity. Thought relates to the "brain" of man as does +electricity to the nervous "battery" of the torpedo; both are forms of +force and the results of action of their respective organs. + +Each sensation affects a cerebral fibre, and, in so affecting it, gives +it the faculty of repeating the action, wherein memory consists and +sensation in a dream. + +If the hypothesis of an abstract entity produces psychological phenomena +by playing upon the brain as a musician upon his instrument be rejected, +and these phenomena be held to be the result of cerebral actions, an +objection is made that the latter view is "materialistic" and adverse to +the notion of an independent, indivisible, "immaterial," mental +principle or soul. + +But in the endeavour to comprehend clearly and explain the functions of +the combination of forces called "brain," the physiologist is hindered +and troubled by the views of the nature of those cerebral forces which +the needs of dogmatic theology have imposed on mankind. How long +physiologists would have entertained the notion of a "life," or "vital +principle," as a distinct entity if freed from this baneful influence +may be questioned; but it can be truly affirmed that physiology has now +established and does accept the truth of that statement of Locke--"the +life, whether of a material or immaterial substance, is not the +substance itself, but an affection of it." + + + + +RUDOLF VIRCHOW + +Cellular Pathology + + Rudolf Virchow, the son of a small farmer and shopkeeper, was born + at Schivelbein, in Pomerania, on October 13, 1821. He graduated in + medicine at Berlin, and was appointed lecturer at the University, + but his political enthusiasm brought him into disfavour. In 1849 he + was removed to Wurzburg, where he was made professor of pathology, + but in 1856 he returned to Berlin as Professor and Director of the + Pathological Institute, and there acquired world-wide fame. His + celebrated work, "Cellular Pathology as based on Histology," + published in 1856, marks a distinct epoch in the science. Virchow + established what Lord Lister describes as "the true and fertile + doctrine that every morbid structure consists of cells which have + been derived from pre-existing cells as a progeny." Virchow was not + only distinguished as a pathologist, he also gained considerable + fame as an archæologist and anthropologist. During the wars of 1866 + and 1870-71, he equipped and drilled hospital corps and ambulance + squads, and superintended hospital trains and the Berlin military + hospital. War over, he directed his attention to sanitation and the + sewage problems of Berlin. Virchow was a voluminous author on a + variety of subjects, perhaps his most well-known works being + "Famine Fever" and "Freedom of Science." He died on September 5, + 1902. + + +_The Cell and the Tissues_ + +The chief point in the application of Histology to Pathology is to +obtain recognition of the fact that the cell is really the ultimate +morphological element in which there is any manifestation of life. + +In certain respects animal cells differ from vegetable cells; but in +essentials they are the same; both consist of matter of a nitrogenous +nature. + +When we examine a simple cell, we find we can distinguish morphological +parts. In the first place, we find in the cell a round or oval body +known as the nucleus. Occasionally the nucleus is stallate or angular; +but as a rule, so long as cells have vital power, the nucleus maintains +a nearly constant round or oval shape. The nucleus in its turn, in +completely developed cells, very constantly encloses another structure +within itself--the so-called nucleolus. With regard to the question of +vital form, it cannot be said of the nucleolus that it appears to be an +absolute essential, and in a considerable number of young cells it has +as yet escaped detection. On the other hand, we regularly meet with it +in fully-developed, older forms, and it therefore seems to mark a higher +degree of development in the cell. + +According to the view which was put forward in the first instance by +Schleiden, and accepted by Schwann, the connection between the three +co-existent cell-constituents was long thought to be of this nature: +that the nucleolus was the first to show itself in the development of +tissues, by separating out of a formative fluid (blastema, +cyto-blastema), that it quickly attained a certain size, that then fine +granules were precipitated out of the blastema and settled around it, +and that about these there condensed a membrane. In this way a nucleus +was formed about which new matter gradually gathered, and in due time +produced a little membrane. This theory of the formation of the cell is +designated the theory of free cell formation--a theory which has been +now almost entirely abandoned. + +It is highly probable that the nucleus plays an extremely important part +within the cell--a part less connected with the function and specific +office of the cell, than with its maintenance and multiplication as a +living part. The specific (animal) function is most distinctly +manifested in muscles, nerves, and gland cells, the peculiar actions of +which--contraction, sensation, and secretion--appear to be connected in +no direct manner with the nuclei. But the permanency of the cell as an +element seems to depend on nucleus, for all cells which lose their +nuclei quickly die, and break up, and disappear. + +Every organism, whether vegetable or animal, must be regarded as a +progressive total, made up of a larger or smaller number of similar or +dissimilar cells. Just as a tree constitutes a mass arranged in a +definite manner in which, in every single part, in the leaves as in the +root, in the trunk as in the blossom, cells are discovered to be the +ultimate elements, so it is with the forms of animal life. Every animal +presents itself as a sum of vital unities, every one of which manifests +all the characteristics of life. The characteristics and unity of life +cannot be limited to any one particular spot in an organism (for +instance, to the brain of a man) but are to be found only in the +definite, constantly recurring structure, which every individual element +displays. A so-called individual always represents an arrangement of a +social kind, in which a number of individual existences are mutually +dependent, but in such a way that every element has its own special +action, and even though it derive its stimulus to activity from other +parts, yet alone affects the actual performance of its duties. + +Between cells there is a greater or less amount of a homogeneous +substance--the _intercellular substance_. According to Schwann, the +intercellular substance was cyto-blastema destined for the development +of new cells; I believe this is not so, I believe that the intercellular +substance is dependent in a certain definite manner upon the cells, and +that certain parts of it belong to one cell and parts to another. + +At various times, fibres, globules, and elementary granules, have been +regarded as histological starting-points. Now, however, we have +established the general principle that no development of any kind begins +_de novo_ and that as spontaneous generation is impossible in the case +of entire organisms, so also it is impossible in the case of individual +parts. No cell can build itself up out of non-cellular material. Where a +cell arises, there a cell must have previously existed (omnis cellula e +cellula), just as an animal can spring only from an animal, and a plant +only from a plant. No developed tissues can be traced back to anything +but a cell. + +If we wish to classify tissues, a very simple division offers itself. We +have (a) tissues which consist exclusively of cells, where cell lies +close to cell. (b) Tissues in which the cells are separated by a certain +amount of intercellular substance. (c) Tissues of a high or peculiar +type, such as the nervous and muscular systems and vessels. An example +of the first class is seen in the _epithelial_ tissues. In these, cell +lies close to cell, with nothing between. + +The second class is exemplified in the _connective_ tissues--tissues +composed of intercellular substance in which at certain intervals cells +lie embedded. + +Muscles, nerves, and vessels form a somewhat heterogeneous group. The +idea suggests itself that we have in all three structures to deal with +real tubes filled with more or less movable contents. This view is, +however, inadequate, since we cannot regard the blood as analogous to +the medullary substance of the nerve, or contractile substance of a +muscular fasciculus. + +The elements of muscle have generally been regarded as the most simple. +If we examine an ordinary red muscle, we find it to be composed of a +number of cylindrical fibres, marked with transverse and longitudinal +striæ. If, now, we add acetic acid, we discover also tolerably large +nuclei with nucleoli. Thus we obtain an appearance like an elongated +cell, and there is a tendency to regard the primitive fasciculus as +having sprung from a single cell. To this view I am much inclined. + +Pathological tissues arise from normal tissues; and there is no form of +morbid growth which cannot in its elements be traced back to some model +which had previously maintained an independent existence in the economy. +A classification, also, of pathological growths may be made on exactly +the same plan as that which we have suggested in the case of the normal +tissues. + + +_Nutrition, Blood, and Lymph. Pus_ + +Nutritive material is carried to the tissues by the blood; but the +material is accepted by the tissues only in accordance with their +requirements for the moment, and is conveyed to the individual districts +in suitable quantities. The muscular elements of the arteries have the +most important influence upon the quantity of the blood distributed, and +their elastic elements ensure an equable stream; but it is chiefly the +simple homogeneous membrane of the capillaries that influences the +permeation of the fluids. Not all the peculiarities, however, in the +interchange of nutritive material are to be attributed to the capillary +wall, for no doubt there are chemical affinities which enable certain +parts specially to attract certain substances from the blood. We know, +for example, that a number of substances are introduced into the body +which have special affinities for the nerve tissues, and that certain +materials are excreted by certain organs. We are therefore compelled to +consider the individual elements as active agents of the attraction. If +the living element be altered by disease, then it loses its power of +specific attraction. + +I do not regard the blood as the cause of chronic dyscrasiæ; for I do +not regard the blood as a permanent tissue independently regenerating +and propagating itself, but as a fluid in a state of constant dependence +upon other parts. I consider that every dyscrasia _is dependent upon a +permanent supply of noxious ingredients from certain sources_. As a +continual ingestion of injurious food is capable of vitiating the blood, +in like manner persistent disease in a definite organ is able to furnish +the blood with a continual supply of morbid materials. + +The essential point, therefore, is to search for the _local sources_ of +the different dyscrasiæ which cause disorders of the blood, for every +permanent change which takes place in the condition of the circulating +juices must be derived from definite organs or tissues. + +The blood contains certain morphological elements. It contains a +substance, _fibrine_, which appears as fibrillac when the blood clots, +and red and colourless blood corpuscles. + +The red blood corpuscles contain no nuclei except at certain periods of +the development of the embyro. They are lighter or darker red according +to the oxygen they contain. When treated with concentrated fluids they +shrivel; when treated with diluted fluids they swell. They are rather +coin-shaped, and when a drop of blood is quiet they are usually found +aggregated in rows, like rouleaux of money. + +The colourless corpuscles are much less numerous than the red +corpuscles--only one to 300--but they are larger, and contain nuclei. +When blood coagulates the white corpuscles sink more slowly and appear +as a lighter coloured layer on the top of the clot. + +Pus cells are very like colourless corpuscles, and the relation between +the two has been much debated. A pus cell can be distinguished from a +colourless blood cell only by its mode of origin. If it have an origin +external to the blood, it must be pus; if it originate in the blood, it +must be considered to be a blood cell. + +In the early stages of its development, a white blood corpuscle is seen +to modify by division; but in fully-developed blood such division is +never seen. It is probable that colourless white corpuscles are given to +the adult blood by the lymphatic glands. Every irritation of a part +which is freely connected with lymphatic glands increases the number of +colourless cells in the blood. Any excessive increase from this source I +have designated _leucocytosis_. + +In the first months of the embryo the red cell multiplies by division. +In adult life the mode of its multiplication is unknown. They, also, are +probably formed in the lymphatic glands and spleen. + +In a disease I have named _leukæmia_, the colourless blood cells +increase in number enormously. In such cases there is always disease of +the spleen, and very often of the lymphatic glands. + +These facts can hardly, I think, be interpreted in any other manner than +by supposing that the spleen and lymphatic glands are intimately +concerned in the production of the formed elements of the blood. + +By _pyæmia_ is meant pus corpuscles in the blood. But most cases of +so-called pyæmia are really cases in which there is an increase of white +blood corpuscles, and it is doubtful whether such a condition as pus in +the blood does ever occur. In the extremely rare cases, in which pus +breaks through into the veins, purulent ingredients may, without doubt, +be conveyed into the blood, but in such cases the introduction of pus +occurs for the most part but once, and there is no persistent pyæmia. +Even when clots in veins break down and form matter like pus, it will be +found that the matter is not really pus, and contains no pus cells. + +_Chlorosis_ is a condition in which there is a diminution of the +cellular elements of the blood, due probably to their deficient +formation in the spleen and lymphatic glands. + + +_The Vital Processes and Their Relation to Disease. Inflammation_ + +The study of the histology of the nervous system shows that in all parts +of the body a splitting up into a number of small centres takes place, +and that nowhere does a single central point susceptible of anatomical +demonstration exist from which the operations of the body are directed. +We find in the nervous systems definite little cells which serve as +centres of motion, but we do not find any single ganglion cell in which +alone all movement in the end originates. The most various individual +motor apparatuses are connected with the most various individual motor +ganglion cells. Sensations are certainly collected in definite ganglion +cells. Still, among them, too, we do not find any single ganglion cell +which can be in any way designated the centre of all sensation, but we +again meet with a great number of very minute centres. All the +operations which have their source in the nervous system, and there +certainly are a very great number of them, do not allow us to recognise +a unity anywhere else than in our own consciousness. An anatomical or +physiological unity has at least as yet been nowhere demonstrated. + +When we talk of life we mean vital activity. Now, every vital action +supposes an excitation or irritation. The irritability of the part is +the criterion by which we judge whether it be alive or not. Our notion +of the death of a part is based upon nothing more or less than +this--that we can no longer detect any irritability in it. If we now +proceed with our analysis of what is to be included in the notion of +excitability, we at once discover, that the different actions which can +be provoked by the influence of any external agency are essentially of +three kinds. The result of an excitation or irritation may, according to +circumstances, be either a merely functional process, or a more or less +increased nutrition of the part, _or_ a formative process giving rise to +a greater or less number of new elements. These differences manifest +themselves more or less distinctly according as the particular tissues +are more or less capable of responding to the one or other kinds of +excitation. It certainly cannot be denied that the processes may not be +distinctly defined, and that between the nutritive and formative +processes, and also between the functional and nutritive ones there are +transitional stages; still, when they are typically performed, there is +a very marked difference between them, and considerable differences in +the internal changes undergone by the excited parts. + +In inflammation all three irritative processes occur side by side. +Indeed, we may frequently see that when the organ itself is made up of +different parts, one part of the tissue undergoes functional or +nutritive, another formative, changes. If we consider what happens in a +muscle we see that a chemical or traumatic stimulus produces a +functional irritation of the primitive fasciculi, with contraction of +the muscle followed by nutritive changes. On the other hand, in the +interstitial connective tissue which binds the individual fasciculi of +the muscle together, real new formations are readily produced, commonly +pus. In this manner the three forms of irritation may be distinguished +in one part. + +The formative process is always preceded by nutritive enlargement due to +irritation of the part, and has no connection with irritation of the +nerves. Of course there may be also an irritation of the nerves, but +this, if we do not take function into account, has no causal connection +with the processes going on in the tissue proper, but is merely a +collateral effect of the original disturbance. + +Besides these active processes of function, nutrition, and new +formation, there occur passive processes. Passive processes are called +those changes in cells whereby they either lose a portion of their +substance, or are so completely destroyed, that a loss of substance, a +diminution of the sum total of the constituents of the body is produced. +To this class belong fatty degeneration of cells, affection of arteries, +calcification, and ossification of arteries, amyloid degeneration, and +so forth. + +It will now be necessary to consider inflammation at more length. The +theory of inflammation has passed through various stages. At first heat +was considered as its essential and dominant feature, then redness, +then exudative swelling; while the speculative neuropathologists +consider pain the _fons et origo_ of the condition. + +Personally, I believe that irritation must be taken as the +starting-point in the consideration of inflammation. We cannot conceive +of inflammation without an irritating stimulus, and the first question +is, what conception we are to form of such a stimulus. + +An inflammatory stimulus is a stimulus which acts either directly or +through the medium of the blood upon the composition and constitution of +a part in such a way as to enable it to attract to itself a larger +quantity of matter than usual and to transform it according to +circumstances. Every form of inflammation with which we are acquainted +may be explained in this way. It may be assumed that inflammation begins +from the moment that this increased absorption of matters into the +tissue takes place, and the further transformation of these matters +commences. + +It must be noticed that hyperæmia is not the essential feature of +inflammation, for inflammation occurs in non-vascular as well as in +vascular parts, and the inflammatory processes are practically the same +in both instances. + +Nor is inflammatory exudation the essential feature of inflammation. I +am of the opinion that there is no specific inflammatory exudation at +all, but that the exudation we meet with is composed essentially of the +material which has been generated in the inflamed part itself, through +the change in its condition, and of the transuded fluid derived from the +vessels. If, therefore, a part possess a great number of vessels, and +particularly if they are superficial, it will be able to furnish an +exudation, since the fluid which transudes from the blood conveys the +special product of the tissue along with it to the surface. If this is +not the case, there will be no exudation, but the whole process will be +limited to the occurrence in the real substance of the tissue of the +special changes which have been induced by the inflammatory stimulus. + +In this manner, two forms of inflammation can be distinguished, the +_purely parenchymatous inflammation_, where the process runs its course +in the interior of the tissue, without our being able to detect the +presence of any free fluid which has escaped from the blood; and the +secretory (exudative) inflammation, where an increased escape of fluid +takes place from the blood, and conveys the peculiar parenchymatous +matters along with it to the surface of the organs. That there are two +kinds of inflammation is shown by the fact that they occur for the most +part in different organs. Every parenchymatous inflammation tends to +alter the histological and functional character of an organ. Every +inflammation with free exudation generally affords a certain relief to +the parts by conveying away from it a great part of the noxious matters +with which it is clogged. + + +_New Formations_ + +I at present entirely reject the blastema doctrine in its original form, +and in its place I put the _doctrine of the continuous development of +tissues out of one another_. My first doubts of the blastema doctrine +date from my researches on tubercle. I found the tubercles never +exhibited a discernible exudation; but always organised elements +unpreceded by amorphous matter. I also found that the discharge from +scrofulous glands and from inflamed lymphatic glands is not an exudation +capable of organisation but merely débris, developed from the ordinary +cells of the glands. + +Until, however, the cellular nature of the body had been demonstrated, +it seemed necessary in some instances to postulate a blastema or +exudation to account for certain new formations. But the moment I could +show the universality of cells--the moment I could show that bone +corpuscles were real cells, and that connective tissues contained +cells--from that moment cellular material for the building of new +formations was apparent. In fact, the more observers increased the more +distinctly was it shown that by far the greater number of new formations +arise from the connective tissue. In almost all cases new formations may +be seen to be formed by a process of ordinary cell division from +previously existing cells. In some cases the cells continue to resemble +the parent cells; in other cases they become different. All new +formations built of cells which continue true to the parent type we may +call homologous new formations; while those which depart from the parent +type or undergo degenerative changes we may designate heterologous. In a +narrower sense of the word heterologous new formations are alone +destructive. The homologous ones may accidentally become very injurious, +but still they do not possess what can properly be called a destructive +or malignant character. On the other hand, every kind of heterologous +formation whenever it has not its seat in entirely superficial parts, +has a certain degree of malignity, and even superficial affections, +though entirely confined to the most external layers of epidermis, may +gradually exercise a very detrimental effect. Indeed, suppuration is of +this nature, for suppuration is simply a process of proliferation by +means of which cells are produced which do not acquire that degree of +consolidation or permanent connection with each other which is necessary +for the existence of the body. Pus is not the solvent of cells: but is +itself dissolved tissues. A part becomes soft and liquefies, while +suppurating, but it is not the pus which causes this softening; on the +contrary, it is the pus which is produced as the result of the +proliferation of tissues. + +A suppurative change of this nature takes place in all heterologous new +formations. The form of ulceration which is presented by cancer in its +latest stages bears so great a resemblance to suppurative ulceration +that the two things have long since been compared. The difference +between suppuration and suppuration lies in the differing duration of +the life of different cells. A cancer cell is capable of existing longer +than a pus corpuscle, and a cancerous tumour may last for months yet +still contain the whole of its elements intact. We are as yet able in +the case of very few elements to state with absolute certainty the +average length of their life. But among all pathological new formations +with fluid intercellular substance there is not a single one which is +able to preserve its existence for any length of time--not a single one +whose elements can become permanent constituents of the body, or exist +as long as the individual. The tumour as a whole may last; but its +individual elements perish. If we examine a tumour after it has existed +for perhaps a year, we usually find that the elements first formed no +longer exist in the centre; but that in the centre they are +disintegrating, dissolved by fatty changes. If a tumour be seated on a +surface, it often presents in the centre of its most prominent part a +navel-like depression, and the parts under this display a dense cicatrix +which no longer bears the original character of the new formation. +Heterologous new formations must be considered parasitical in their +nature, since every one of their elements will withdraw matters from the +body which might be used for better purposes, and since even its first +development implies the destruction of its parent structures. + +In view of origin of new formations it were well to create a +nomenclature showing their histological basis; but new names must not be +introduced too suddenly, and it must be noted that there are certain +tumours whose histological pedigree is still uncertain. + + +_Printed in the United States of America_ + +FOOTNOTES: + +[1] Azure transparent spheres conceived by the ancients to surround the +earth one within another, and to carry the heavenly bodies in their +revolutions. + +[2] Book I., Prop. i. The areas which revolving bodies describe by radii +drawn to an immovable centre of force do lie in the same immovable +planes and are proportional to the times in which they are described. + +Prop. ii. Every body that moves in any curve line described in a plane +and by a radius drawn to a point either immovable or moving forward with +a uniform rectilinear motion describes about that point areas +proportional to the times is urged by a centripetal force directed to +that point. + +Prop. iii. Every body that, by a radius drawn to another body, howsoever +moved, describes areas about that centre proportional to the times is +urged by a force compounded out of the centripetal force tending to that +other body and of all the accelerative force by which that other body is +impelled. + +[3] If the periodic times are in the sesquiplicate ratio of the radii, +and therefore the velocities reciprocally in the subduplicate ratio of +the radii, the centripetal forces will be in the duplicate ratio of the +radii inversely; and the converse. + +[4] _i.e._, showing convexity when in such a position as that, to an +observer on the earth, a line drawn between it and the sun would subtend +an angle of _90_° or thereabouts. + + +TRANSCRIBER NOTE: + +Variant spelling and punctuation have been preserved. + + + + + +End of the Project Gutenberg EBook of The World's Greatest Books - Volume 15 +- Science, by Various + +*** END OF THIS PROJECT GUTENBERG EBOOK WORLD'S GREATEST BOOKS-VOLUME 15 *** + +***** This file should be named 25509-8.txt or 25509-8.zip ***** +This and all associated files of various formats will be found in: + https://www.gutenberg.org/2/5/5/0/25509/ + +Produced by Kevin Handy, John Hagerson, Greg Bergquist and +the Online Distributed Proofreading Team at +https://www.pgdp.net + + +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. 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Hammerton. + </title> + <style type="text/css"> +/*<![CDATA[ XML blockout */ +<!-- + p { margin-top: .75em; + text-align: justify; + margin-bottom: .75em; + text-indent: 1em; + line-height: 130%; + } + sup {font-size: 60%; vertical-align: 1ex;} + h1,h2,h3 { + text-align: center; /* all headings centered */ + clear: both; + } + hr { width: 33%; + margin-top: 2em; + margin-bottom: 2em; + margin-left: auto; + margin-right: auto; + clear: both; + } + + table {margin-left: auto; margin-right: auto;} + .tda {padding-left: 2em; text-align: left; padding-bottom: 1em;} + .tdb {padding-left: 2em; text-align: left;} + .tdc {text-align: right; padding-bottom: 1em;} + body{margin-left: 10%; + margin-right: 10%; + } + + a {text-decoration: none; } + .pagenum {display: inline; font-size: small; text-align: right; + position: absolute; right: 2%; text-indent: 0em; + padding: 1px 3px; font-style: normal; + font-variant: normal; font-weight: normal; text-decoration: none; + color: #444; background-color: #EEE;} + + .blockquot{margin-left: 5%; margin-right: 10%; font-size: 90%;} + .tnote {margin-left: 10%; + margin-right: 10%; + margin-top: 5em; + margin-bottom: 5em; + padding: 0em 1em 1em 1em; + background-color: #f6f2f2; + color: black; + border: solid 1px; + font-size: 90%;} + + .center {text-align: center; text-indent: 0em;} + .smcap {font-variant: small-caps;} + .book {text-align: center; text-indent: 0em; margin-top: 1.5em;} + .subchap {text-align: center; margin-top: 2em; text-indent: 0em;} + .caption {font-weight: bold;} + .above, .below { font-size: 70%;} + .above { vertical-align: 0.7ex;} + .below { vertical-align: -0.3ex;} + .radic {letter-spacing: -0.10em;} + .radicand {text-decoration: overline;} + + .figcenter {margin: auto; text-align: center;} + + .footnotes {border: dashed 1px;} + .footnote {margin-left: 10%; margin-right: 10%; font-size: 0.9em;} + .footnote .label {position: absolute; right: 84%; text-align: right;} + .fnanchor {vertical-align: super; font-size: 70%; text-decoration: none; line-height: 70%;} + + + // --> + /* XML end ]]>*/ + </style> + </head> +<body> + + +<pre> + +The Project Gutenberg EBook of The World's Greatest Books - Volume 15 - +Science, by Various + +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 World's Greatest Books - Volume 15 - Science + +Author: Various + +Editor: John Alexander Hammerton + +Release Date: May 17, 2008 [EBook #25509] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK WORLD'S GREATEST BOOKS-VOLUME 15 *** + + + + +Produced by Kevin Handy, John Hagerson, Greg Bergquist and +the Online Distributed Proofreading Team at +https://www.pgdp.net + + + + + + +</pre> + +<div class="figcenter" style="width: 400px;"> +<img src="images/frontis.jpg" width="400" height="460" alt="William Harvey" title="" /> +<span class="caption"><a name="William_Harvey" id="William_Harvey"></a>William Harvey</span> +</div> +<hr /> +<div class="figcenter" style="width: 400px;"> +<img src="images/title.jpg" width="400" height="632" alt="" title="" /> +</div> + +<hr /> +<h1> +THE WORLD'S<br /> +GREATEST<br /> +BOOKS</h1> + +<p class="center"><br /><br /><br />JOINT EDITORS<br /> + +ARTHUR MEE<br /> +<small>Editor and Founder of the Book of Knowledge</small><br /> + +J.A. HAMMERTON<br /> +<small>Editor of Harmsworth's Universal Encyclopaedia</small><br /><br /><br /></p> + +<p class="center"><big>VOL. XV</big><br /><br /> + +<big>SCIENCE</big><br /><br /></p> + +<p class="center"><br /><br /><span class="smcap">WM. H. WISE & Co.</span> +</p> +<hr /> + + +<h2><i>Table of Contents</i></h2> +<div class='center'> +<table border="0" cellpadding="2" cellspacing="2" summary="Conents"> +<tr><td align='left'><span class="smcap">Portrait of William Harvey</span></td><td align='right'><i><a href="#William_Harvey">Frontispiece</a></i></td></tr> +<tr><td align='left'><span class="smcap">Bramwell, John Milne</span></td><td align='right'><small>PAGE</small></td></tr> +<tr><td class='tda'><a href="#Hypnotism_Its_History_Practice_and_Theory">Hypnotism: Its History, Practice and Theory</a></td><td class="tdc">1</td></tr> +<tr><td align='left'><span class="smcap">Buffon, Comte de</span></td></tr> +<tr><td class='tda'><a href="#Natural_History">Natural History</a></td><td class="tdc">12</td></tr> +<tr><td align='left'><span class="smcap">Chambers, Robert</span></td></tr> +<tr><td class='tda'><a href="#Vestiges_of_Creation">Vestiges of Creation</a></td><td class="tdc">22</td></tr> +<tr><td align='left'><span class="smcap">Cuvier, Georges</span></td></tr> +<tr><td class='tda'><a href="#The_Surface_of_the_Globe">The Surface of the Globe</a></td><td class="tdc">33</td></tr> +<tr><td align='left'><span class="smcap">Darwin, Charles</span></td></tr> +<tr><td class='tda'><a href="#The_Origin_of_Species">The Origin of Species</a></td><td class="tdc">43</td></tr> +<tr><td align='left'><span class="smcap">Davy, Sir Humphry</span></td></tr> +<tr><td class='tda'><a href="#Elements_of_Chemical_Philosophy">Elements of Chemical Philosophy</a></td><td class="tdc">64</td></tr> +<tr><td align='left'><span class="smcap">Faraday, Michael</span></td></tr> +<tr><td class='tdb'><a href="#Experimental_Researches_in_Electricity">Experimental Researches in Electricity</a></td><td class="tdc">75</td></tr> +<tr><td class='tda'><a href="#The_Chemical_History_of_a_Candle">The Chemical History of a Candle</a></td><td class="tdc">85</td></tr> +<tr><td align='left'><span class="smcap">Forel, Auguste</span></td></tr> +<tr><td class='tda'><a href="#The_Senses_of_Insects">The Senses of Insects</a></td><td class="tdc">95</td></tr> +<tr><td align='left'><span class="smcap">Galileo</span></td></tr> +<tr><td class='tda'><a href="#Dialogues_on_the_System_of_the_World">Dialogues on the System of the World</a></td><td class="tdc">105</td></tr> +<tr><td align='left'><span class="smcap">Galton, Sir Francis</span></td></tr> +<tr><td class='tda'><a href="#Essays_in_Eugenics">Essays in Eugenics</a></td><td class="tdc">111</td></tr> +<tr><td align='left'><span class="smcap">Haeckel, Ernst</span></td></tr> +<tr><td class='tda'><a href="#The_Evolution_of_Man">The Evolution of Man</a></td><td class="tdc">123</td></tr> +<tr><td align='left'><span class="smcap">Harvey, William</span></td></tr> +<tr><td class='tda'><a href="#On_the_Motion_of_the_Heart_and_Blood">On the Motion of the Heart and Blood</a></td><td class="tdc">136</td></tr> +<tr><td align='left'><span class="smcap">Herschel, Sir John</span></td></tr> +<tr><td class='tda'><a href="#Outlines_of_Astronomy">Outlines of Astronomy</a></td><td class="tdc">146</td></tr> +<tr><td align='left'><span class="smcap">Humboldt, Alexander von</span></td></tr> +<tr><td class='tda'><a href="#Cosmos_a_Sketch_of_the_Universe">Cosmos, a Sketch of the Universe</a></td><td class="tdc">158</td></tr> +<tr><td align='left'><span class="smcap">Hutton, James</span></td></tr> +<tr><td class='tda'><a href="#The_Theory_of_the_Earth">The Theory of the Earth</a></td><td class="tdc">170</td></tr> +<tr><td align='left'><span class="smcap">Lamarck</span></td></tr> +<tr><td class='tda'><a href="#Zoological_Philosophy">Zoological Philosophy</a></td><td class="tdc">179</td></tr> +<tr><td align='left'><span class="smcap">Lavater, Johann</span></td></tr> +<tr><td class='tda'><a href="#Physiognomical_Fragments">Physiogonomical Fragments</a></td><td class="tdc">191</td></tr> +<tr><td align='left'><span class="smcap">Liebig, Justus von</span></td></tr> +<tr><td class='tda'><a href="#Animal_Chemistry">Animal Chemistry</a></td><td class="tdc">203</td></tr> +<tr><td align='left'><span class="smcap">Lyell, Sir Charles</span></td></tr> +<tr><td class='tda'><a href="#The_Principles_of_Geology">The Principles of Geology</a></td><td class="tdc">215</td></tr> +<tr><td align='left'><span class="smcap">Maxwell, James Clerk</span></td></tr> +<tr><td class='tda'><a href="#A_Treatise_on_Electricity_and_Magnetism">A Treatise on Electricity and Magnetism</a></td><td class="tdc">227</td></tr> +<tr><td align='left'><span class="smcap">Metchnikoff, Elie</span></td></tr> +<tr><td class='tdb'><a href="#The_Nature_of_Man">The Nature of Man</a></td><td class="tdc">238</td></tr> +<tr><td class='tda'><a href="#The_Prolongation_of_Life">The Prolongation of Life</a></td><td class="tdc">246</td></tr> +<tr><td align='left'><span class="smcap">Miller, Hugh</span></td></tr> +<tr><td class='tda'><a href="#The_Old_Red_Sandstone">The Old Red Sandstone</a></td><td class="tdc">255</td></tr> +<tr><td align='left'><span class="smcap">Newton, Sir Isaac</span></td></tr> +<tr><td class='tda'><a href="#Principia">Principia</a></td><td class="tdc">267</td></tr> +<tr><td align='left'><span class="smcap">Owen, Sir Richard</span></td></tr> +<tr><td class='tda'><a href="#Anatomy_of_Vertebrates">Anatomy of Vertebrates</a></td><td class="tdc">280</td></tr> +<tr><td align='left'><span class="smcap">Virchow, Rudolf</span></td></tr> +<tr><td class='tda'><a href="#Cellular_Pathology">Cellular Pathology</a></td><td class="tdc">292</td></tr> +</table></div> + +<hr /> + +<p class="center">A Complete Index of <span class="smcap">The World's Greatest Books</span> will be found at the end +of Volume XX.</p> + + + +<hr /> +<h2><i>Acknowledgment</i></h2> + + +<p>Acknowledgment and thanks for the use of the following selections are +herewith tendered to the Open Court Publishing Company, La Salle, Ill., +for "Senses of Insects," by Auguste Forel; to G.P. Putnam's Sons, New +York, for "Prolongation of Human Life" and "Nature of Man," by Elie +Metchnikoff; and to the De La More Press, London, for "Hypnotism, &c.," +by Dr. Bramwell.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_1" id="Page_1">[Pg 1]</a></span></p> +<h2><i>Science</i></h2> + +<h3>JOHN MILNE BRAMWELL</h3> + +<p class="book"><big><a name="Hypnotism_Its_History_Practice_and_Theory" id="Hypnotism_Its_History_Practice_and_Theory"></a>Hypnotism: Its History, Practice and Theory</big></p> + +<div class="blockquot"><p>John Milne Bramwell was born in Perth, Scotland, May 11, 1852. The +son of a physician, he studied medicine in Edinburgh, and after +obtaining his degree of M.B., in 1873, he settled at Goole, +Yorkshire. Fired by the unfinished work of Braid, Bernheim and +Liébeault, he began, in 1889, a series of hypnotic researches, +which, together with a number of successful experiments he had +privately conducted, created considerable stir in the medical +world. Abandoning his general practice and settling in London in +1892, Dr. Bramwell became one of the foremost authorities in the +country on hypnotism as a curative agent. His Works include many +valuable treatises, the most important being "Hypnotism: its +History, Practice and Theory," published in 1903, and here +summarised for the <span class="smcap">World's Greatest Books</span> by Dr. Bramwell himself.</p></div> + + +<p class="subchap"><i>I.—Pioneers of Hypnotism</i></p> + +<p><span class="smcap">Just</span> as chemistry arose from alchemy, astronomy from astrology, so +hypnotism had its origin in mesmerism. Phenomena such as Mesmer +described had undoubtedly been observed from early times, but to his +work, which extended from 1756 to his death, in 1815, we owe the +scientific interest which, after much error and self-deception, finally +led to what we now term hypnotism.</p> + +<p>John Elliotson (1791–1868), the foremost physician of his day, was the +leader of the mesmeric movement in England. In 1837, after seeing +Dupotet's work, he commenced to experiment at University College +Hospital, and continued, with remarkable success, until ordered to +desist by the council of the college. Elliotson felt the<span class='pagenum'><a name="Page_2" id="Page_2">[Pg 2]</a></span> insult keenly, +indignantly resigned his appointments, and never afterwards entered the +hospital he had done so much to establish. Despite the persistent and +virulent attacks of the medical press, he continued his mesmeric +researches up to the time of his death, sacrificing friends, income and +reputation to his beliefs.</p> + +<p>The fame of mesmerism spread to India, where, in 1845, James Esdaile +(1808–1859), a surgeon in the East India Company, determined to +investigate the subject. He was in charge of the Native Hospital at +Hooghly, and successfully mesmerised a convict before a painful +operation. Encouraged by this, he persevered, and, at the end of a year, +reported 120 painless operations to the government. Investigations were +instituted, and Esdaile was placed in charge of a hospital at Calcutta, +for the express purpose of mesmeric practice; he continued to occupy +similar posts until he left India in 1851. He recorded 261 painless +capital operations and many thousand minor ones, and reduced the +mortality for the removal of the enormous tumours of elephantiasis from +50 to 5 per cent.</p> + +<p>According to Elliotson and Esdaile, the phenomena of mesmerism were +entirely physical in origin. They were supposed to be due to the action +of a vital curative fluid, or peculiar physical force, which, under +certain circumstances, could be transmitted from one human being to +another. This was usually termed the "od," or "odylic," force; various +inanimate objects, such as metals, crystals and magnets, were supposed +to possess it, and to be capable of inducing and terminating the +mesmeric state, or of exciting or arresting its phenomena.</p> + +<p>The name of James Braid (1795–1860) is familiar to all students of +hypnotism. Braid was a Scottish surgeon, practising in Manchester, where +he had already gained a high reputation as a skilful surgeon, when, in +1841, he first began to investigate mesmerism. He<span class='pagenum'><a name="Page_3" id="Page_3">[Pg 3]</a></span> successfully +demonstrated that the phenomena were entirely subjective. He published +"Neurypnology, or the Rationale of Nervous Sleep," in 1843, and invented +the terminology we now use. This was followed by other more or less +important works, of which I have been able to trace forty-one, but all +have been long out of print.</p> + +<p>During the eighteen years Braid devoted to the study of hypnotism, his +views underwent many changes and modifications. In his first theory, he +explained hypnosis from a physical standpoint; in the second, he +considered it to be a condition of involuntary monoideism and +concentration, while his third theory differed from both. He recognised +that reason and volition were unimpaired, and that the attention could +be simultaneously directed to more points than one. The condition, +therefore, was not one of monoideism. He realised more and more that the +state was a conscious one, and that the losses of memory which followed +on waking could always be restored in subsequent hypnoses. Finally, he +described as "double consciousness" the condition he had first termed +"hypnotic," then "monoideistic."</p> + +<p>Braid maintained an active interest in hypnotism up to his death, and, +indeed, three days before it, sent his last MS. to Dr. Azam, of +Bordeaux, "as a mark of esteem and regard." Sympathetic notices appeared +in the press after his death, all of which bore warm testimony to his +professional character. Although hypnotic work practically ceased in +England at Braid's death, the torch he had lighted passed into France.</p> + +<p>In 1860, Dr. A.A. Liébeault (1823–1900) began to study hypnotism +seriously, and four years later gave up general practice, settled in +Nancy, and practised hypnotism gratuitously among the poor. For twenty +years his labours were unrecognised, then Bernheim (one of whose +patients Liébeault had cured) came to see him, and soon became a zealous +pupil. The fame of the<span class='pagenum'><a name="Page_4" id="Page_4">[Pg 4]</a></span> Nancy school spread, Liébeault's name became +known throughout the world, and doctors flocked to study the new +therapeutic method.</p> + +<p>While Liébeault's work may justly be regarded as a continuation of +Braid's, there exists little difference between the theories of Charcot +and the Salpêtrière school and those of the later mesmerists.</p> + + +<p class="subchap"><i>II.—Theory of Hypnotism</i></p> + +<p>The following is a summary of Braid's latest theories: (1) Hypnosis +could not be induced by physical means alone. (2) Hypnotic and so-called +mesmeric phenomena were subjective in origin, and both were excited by +direct or by indirect suggestion. (3) Hypnosis was characterised by +physical as well as by psychical changes. (4) The simultaneous +appearance of several phenomena was recognised, and much importance was +attached to the intelligent action of a secondary consciousness. (5) +Volition was unimpaired, moral sense increased, and suggested crime +impossible. (6) <i>Rapport</i> was a purely artificial condition created by +suggestion. (7) The importance of direct verbal suggestion was fully +recognised, as also the mental influence of physical methods. Suggestion +was regarded as the device used for exciting the phenomena, and not +considered as sufficient to explain them. (8) Important differences +existed between hypnosis and normal sleep. (9) Hypnotic phenomena might +be induced without the subject having passed through any condition +resembling sleep. (10) The mentally healthy were the easiest, the +hysterical the most difficult, to influence.</p> + +<p>In England, during Braid's lifetime, his earlier views were largely +adopted by certain well-known men of science, particularly by Professors +W.B. Carpenter and J. Hughes Bennett, but they appear to have known +little or nothing of his latest theories. Bennett's<span class='pagenum'><a name="Page_5" id="Page_5">[Pg 5]</a></span> description of the +probable mental and physical conditions involved in the state Braid +described as "monoideism" is specially worthy of note. Not only is it +interesting in itself, but it serves also as a standard of comparison +with which to measure the theories of later observers, who have +attempted to explain hypnosis by cerebral inhibition, psychical +automatism, or both these conditions combined.</p> + +<p>(a) <i>Physiological.</i>—According to Bennett, hypnosis was characterised +by alterations in the functional activity of the nerve tubes of the +white matter of the cerebral lobes. He suggested that a certain +proportion of these became paralysed through continued monotonous +stimulation; while the action of others was consequently exalted. As +these tubes connected the cerebral ganglion-cells, suspension of their +functions was assumed to bring with it interruption of the connection +between the ganglion-cells.</p> + +<p>(b) <i>Psychical.</i>—From the psychical side, he explained the phenomena of +hypnosis by the action of predominant and unchecked ideas. These were +able to obtain prominence from the fact that other ideas, which, under +ordinary circumstances, would have controlled their development, did not +arise, because the portion of the brain with which the latter were +associated had its action temporarily suspended—<i>i.e.</i>, the connection +between the ganglion-cells was broken, owing to the interrupted +connection between the "fibres of association." Thus, he said, the +remembrance of a sensation could always be called up by the brain; but, +under ordinary circumstances, from the exercise of judgment, comparison, +and other mental faculties, we knew it was only a remembrance. When +these faculties were exhausted, the suggested idea predominated, and the +individual believed in its reality. Thus, he attributed to the faculties +of the mind a certain power of correcting the fallacies which each of +them was likely to fall into; just as the<span class='pagenum'><a name="Page_6" id="Page_6">[Pg 6]</a></span> illusions of one sense were +capable of being detected by the healthy use of the other senses. There +were mental and sensorial illusions, the former caused by predominant +ideas and corrected by proper reasoning, the latter caused by perversion +of one sense and corrected by the right application of the others.</p> + +<p>In hypnosis, according to this theory, a suggested idea obtained +prominence and caused mental and sensorial illusions, because the check +action—the inhibitory power—of certain higher centres had been +temporarily suspended. These theories were first published by Professor +Bennett in 1851.</p> + + +<p class="subchap"><i>III.—Hypnotic Induction</i></p> + +<p>The methods by which hypnosis is induced have been classed as follows: +(1) physical; (2) psychical; (3) those of the magnetisers. The modern +operator, whatever his theories may be, borrows his technique from +Mesmer and Liébeault with equal impartiality, and thus renders +classification impossible. The members of the Nancy school, while +asserting that everything is due to suggestion, do not hesitate to use +physical means, and, if these fail, Bernheim has recourse to narcotics.</p> + +<p>The following is now my usual method: I rarely begin treatment the first +time I see a patient, but confine myself to making his acquaintance, +hearing his account of his case, and ascertaining his mental attitude +with regard to suggestion. I usually find, from the failure of other +methods of treatment, that he is more or less sceptical as to the chance +of being benefited. I endeavour to remove all erroneous ideas, and +refuse to begin treatment until the patient is satisfied of the safety +and desirability of the experiment. I never say I am certain of being +able to influence him, but explain how much depends on his mental +attitude and power of carrying out my directions. I further explain to +the patient<span class='pagenum'><a name="Page_7" id="Page_7">[Pg 7]</a></span> that next time he comes to see me I shall ask him to close +his eyes, to concentrate his attention on some drowsy mental picture, +and try to turn it away from me. I then make suggestions of two kinds: +the first refer to the condition I wish to induce while he is actually +in the armchair, thus, "Each time you see me, you will find it easier to +concentrate your attention on something restful. I do not wish you to go +to sleep, but if you can get into the drowsy condition preceding natural +sleep, my suggestions are more likely to be responded to." I explain +that I do not expect this to happen at once, although it does occur in +rare instances, but it is the repetition of the suggestions made in this +particular way which brings about the result. Thus, from the very first +treatment, the patient is subjected to two distinct processes, the +object of one being to induce the drowsy, suggestible condition, that of +the other to cure or relieve disease.</p> + +<p>I wish particularly to mention that although I speak of hypnotism and +hypnosis—and it is almost impossible to avoid doing so—I rarely +attempt to induce so-called hypnosis, and find that patients respond to +treatment as readily, and much more quickly, now that I start curative +suggestions and treatment simultaneously, than they did in the days when +I waited until hypnosis was induced before making curative suggestions.</p> + +<p>I have obtained good results in treating all forms of hysteria, +including <i>grande hysterie</i>, neurasthenia, certain forms of insanity, +dipsomania and chronic alcoholism, morphinomania and other drug habits, +vicious and degenerate children, obsessions, stammering, chorea, +seasickness, and all other forms of functional nervous disturbances.</p> + +<p>It is impossible to discuss the different theories in detail here, but I +will briefly summarise the more important points, (1) Hypnotism, as a +science, rests on the recognition of the subjective nature of its +<span class='pagenum'><a name="Page_8" id="Page_8">[Pg 8]</a></span>phenomena. (2) The theories of Charcot and the Salpêtrière school are +practically a reproduction of mesmeric error. (3) Liébeault and his +followers combated the views of the Salpêtrière school and successfully +substituted their own, of which the following are the important points: +(<i>a</i>) Hypnosis is a physiological condition, which can be induced in the +healthy. (<i>b</i>) In everyone there is a tendency to respond to suggestion, +but in hypnosis this condition is artificially increased. (<i>c</i>) +Suggestion explains all. Despite the fact that the members of the Nancy +school regard the condition as purely physiological and simply an +exaggeration of the normal, they consider it, in its profound stages at +all events, a form of automatism.</p> + +<p>These and other views of the Nancy school have been questioned by +several observers. As Myers justly pointed out, although suggestion is +the artifice used to excite the phenomena, it does not create the +condition on which they depend. The peculiar state which enables the +phenomena to be evoked is the essential thing, not the signal which +precedes their appearance.</p> + +<p>Within recent times another theory has arisen, which, instead of +explaining hypnotism by the arrested action of some of the brain centres +which subserve normal life, attempts to do so by the arousing of certain +powers over which we normally have little or no control. This theory +appears under different names, "Double Consciousness," "Das Doppel-Ich," +etc., and the principle on which it depends is largely admitted by +science. William James, for example, says: "In certain persons, at +least, the total possible consciousness may be split into parts which +co-exist, but mutually ignore each other."</p> + +<p>The clearest statement of this view was given by the late Frederic +Myers; he suggested that the stream of consciousness in which we +habitually lived was not our only one. Possibly our habitual +consciousness might<span class='pagenum'><a name="Page_9" id="Page_9">[Pg 9]</a></span> be a mere selection from a multitude of thoughts +and sensations—some, at least, equally conscious with those we +empirically knew. No primacy was granted by this theory to the ordinary +waking self, except that among potential selves it appeared the fittest +to meet the needs of common life. As a rule, the waking life was +remembered in hypnosis, and the hypnotic life forgotten in the waking +state; this destroyed any claim of the primary memory to be the sole +memory. The self below the threshold of ordinary consciousness Myers +termed the "subliminal consciousness," and the empirical self of common +experience the "supraliminal." He held that to the subliminal +consciousness and memory a far wider range, both of physiological and +psychical activity, was open than to the supraliminal. The latter was +inevitably limited by the need of concentration upon recollections +useful in the struggle for existence; while the former included much +that was too rudimentary to be retained in the supraliminal memory of an +organism so advanced as that of man. The recollection of processes now +performed automatically and needing no supervision, passed out of the +supraliminal memory, but might be retained by the subliminal. The +subliminal, or hypnotic, self could exercise over the vaso-motor and +circulatory systems a degree of control unparalleled in waking life.</p> + +<p>Thus, according to the Nancy school, the deeply hypnotised subject +responds automatically to suggestion before his intellectual centres +have had time to bring their inhibitory action into play; but, on the +other hand, in the subliminal consciousness theory, volition and +consciousness are recognised to be unimpaired in hypnosis.</p> + + +<p class="subchap"><i>IV.—Curative Value of Hypnotism</i></p> + +<p>The intelligent action of the secondary self may be illustrated by the +execution of certain post-hypnotic acts.<span class='pagenum'><a name="Page_10" id="Page_10">[Pg 10]</a></span> Thus, one of my patients who, +at a later period, consented to become the subject of experiment, +developed an enormously increased power of time appreciation. If told, +during hypnosis, for example, that she was to perform some specific act +in the waking state at the expiration of a complicated number of +minutes, as, for example, 40,825, she generally carried out the +suggestion with absolute accuracy. In this and similar experiments, +three points were noted. (1) The arithmetical problems were far beyond +her normal powers; (2) she normally possessed no special faculty for +appreciating time; (3) her waking consciousness retained no recollection +of the experimental suggestions or of anything else that had occurred +during hypnosis.</p> + +<p>It is difficult to estimate the exact value of suggestion in connection +with other forms of treatment. There are one or two broad facts which +ought to be kept in mind.</p> + +<p>1. Suggestion is a branch of medicine, which is sometimes combined by +those who practise it with other forms of treatment. Thus it is often +difficult to say what proportion of the curative results is due to +hypnotism and what to other remedies.</p> + +<p>2. On the other hand, many cases of functional nervous disorder have +recovered under suggestive treatment after the continued failure of +other methods. Further, the diseases which are frequently cured are +often those in which drugs are of little or no avail. For example, what +medicine would one prescribe for a man in good physical health who had +suddenly become the prey of an obsession? Such patients are rarely +insane; they recognise that the idea which torments them is morbid; but +yet they are powerless to get rid of it.</p> + +<p>3. In estimating the results of suggestive treatment, it must not be +forgotten that the majority of cases are extremely unfavourable ones. As +the value of suggestion and its freedom from danger become more fully<span class='pagenum'><a name="Page_11" id="Page_11">[Pg 11]</a></span> +recognised, it will doubtless be employed in earlier stages of disease.</p> + +<p>4. It should be clearly understood that the object of all suggestive +treatment ought to be the development of the patient's will power and +control of his own organism. Much disease would be prevented if we could +develop and control moral states.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_12" id="Page_12">[Pg 12]</a></span></p> +<h3>BUFFON</h3> + +<p class="book"><big><a name="Natural_History" id="Natural_History"></a>Natural History</big></p> + +<div class="blockquot"><p>Georges Louis Leclerc, created in 1773 Comte de Buffon, was born at +Montbard, in France, on September 7, 1707. Evincing a marked bent +for science he became, in 1739, director of the Jardin du Roi and +the King's Museum in Paris. He had long contemplated the +preparation of a complete History of Nature, and now proceeded to +carry out the work. The first three volumes of the "Histoire +Naturelle, Générale et Particulière" appeared in 1749, and other +volumes followed at frequent intervals until his death at Paris on +April 16, 1788. Buffon's immense enterprise was greeted with +abounding praise by most of his contemporaries. On July 1, 1752, he +was elected to the French Academy in succession to Languet de +Gergy, Archbishop of Sens, and, at his reception on August 25 in +the following year, pronounced the oration in which occurred the +memorable aphorism, "Le style est l'homme même" (The style is the +very man). Buffon also anticipated Thomas Carlyle's definition of +genius ("which means the transcendent capacity of taking trouble, +first of all") by his famous axiom, "Le génie n'est autre chose +qu'une grande aptitude à la patience."</p></div> + +<p class="subchap"><i>Scope of the Work</i></p> + +<p><span class="smcap">Buffon</span> planned his "Natural History" on an encyclopaedic scale. His +point of view was unique. Natural history in its widest sense, he tells +us, embraces every object in the visible universe. The obvious divisions +of the subject, therefore, are, first, the earth, the air, and the +water; then the animals—quadrupeds, birds, fishes, and so +on—inhabiting each of these "elements," to use the phrase of his day. +Now, Buffon argued, if man were required to give some account of the +animals by which he was surrounded, of course he would begin with those +with which he was most familiar, as the horse, the dog, the cow. From +these he would proceed to the creatures with which he was less familiar, +and finally<span class='pagenum'><a name="Page_13" id="Page_13">[Pg 13]</a></span> deal—through the medium of travellers' tales and other +sources of information—with the denizens of field, forest and flood in +foreign lands. In similar fashion he would consider the plants, +minerals, and other products of Nature, in addition to recounting the +marvels revealed to him by astronomy.</p> + +<p>Whatever its defects on the scientific side, Buffon's plan was +simplicity itself, and was adopted largely, if not entirely, in +consequence of his contempt—real or affected—for the systematic method +of the illustrious Linnæus. Having charted his course, the rest was +plain sailing. He starts with the physical globe, discussing the +formation of the planets, the features of the earth—mountains, rivers, +seas, lakes, tides, currents, winds, volcanoes, earthquakes, islands, +and so forth—and the effects of the encroachment and retreat of the +ocean.</p> + +<p>Animate nature next concerns him. After comparing animals, plants and +minerals, he proceeds to study man literally from the cradle to the +grave, garnishing the narrative with those incursions into the domains +of psychology, physiology and hygiene, which, his detractors insinuated, +rendered his work specially attractive and popular.</p> + + +<p class="subchap"><i>I.—The Four-Footed Animals</i></p> + +<p>Such questions occupied the first three volumes, and the ground was now +cleared for the celebrated treatise on Quadrupeds, which filled no fewer +than twelve volumes, published at various dates from 1753 (vol. iv.) to +1767 (vol. xv., containing the New World monkeys, indexes, and the +like). Buffon's <i>modus operandi</i> saved him from capital blunders. Though +inordinately vain—"I know but five great geniuses," he once said; +"Newton, Bacon, Leibniz, Montesquieu, and myself"—he was quite +conscious of his own limitations, and had the common-sense to entrust to +Daubenton the description of<span class='pagenum'><a name="Page_14" id="Page_14">[Pg 14]</a></span> the anatomy and other technical matters as +to which his own knowledge was comparatively defective. He reserved to +himself what may be called the "literary" aspect of his theme, recording +the place of each animal in history, and relating its habits with such +gusto as his ornate and grandiose style permitted.</p> + +<p>After a preliminary dissertation on the nature of animals, Buffon +plunges into an account of those that have been domesticated or tamed. +Preference of place is given to the horse, and his method of treatment +is curiously anticipatory of modern lines. Beginning with some notice of +the horse in history, he goes on to describe its appearance and habits +and the varieties of the genus, ending (by the hand of Daubenton) with +an account of its structure and physiology. As evidence of the pains he +took to collect authority for his statements, it is of interest to +mention that he illustrates the running powers of the English horse by +citing the instance of Thornhill, the postmaster of Stilton, who, in +1745, wagered he would ride the distance from Stilton to London thrice +in fifteen consecutive hours. Setting out from Stilton, and using eight +different horses, he accomplished his task in 3 hours 51 minutes. In the +return journey he used six horses, and took 3 hours 52 minutes. For the +third race he confined his choice of horses to those he had already +ridden, and, selecting seven, achieved the distance in 3 hours 49 +minutes. He performed the undertaking in 11 hours and 32 minutes. "I +doubt," comments Buffon, "whether in the Olympic Games there was ever +witnessed such rapid racing as that displayed by Mr. Thornhill."</p> + +<p>Justice having been done to it, the horse gives place to the ass, ox, +sheep, goat, pig, dog, and cat, with which he closes the account of the +domesticated animals, to which three volumes are allotted. It is +noteworthy that Buffon frequently, if not always, gives the synonyms of +the animals' names in other languages, and usually <span class='pagenum'><a name="Page_15" id="Page_15">[Pg 15]</a></span>supports his textual +statements by footnote references to his authorities.</p> + +<p>When he comes to the Carnivores—"les animaux nuisibles"—the defects of +Buffon's higgledy-piggledy plan are almost ludicrously evident, for +flesh-eaters, fruit-eaters, insect-eaters, and gnawers rub shoulders +with colossal indifference. Doubtless, however, this is to us all the +more conspicuous, because use and wont have made readers of the present +day acquainted with the advantages of classification, which it is but +fair to recognise has been elaborated and perfected since Buffon's time.</p> + +<p>As his gigantic task progressed, Buffon's difficulties increased. At the +beginning of vol. xii. (1764) he intimates that, with a view to break +the monotony of a narrative in which uniformity is an unavoidable +feature, he will in future, from time to time, interrupt the general +description by discourses on Nature and its effects on a grand scale. +This will, he naively adds, enable him to resume "with renewed courage" +his account of details the investigation of which demands "the calmest +patience, and affords no scope for genius."</p> + + +<p class="subchap"><i>II.—The Birds</i></p> + +<p>Scarcely had he finished the twelve volumes of Quadrupeds when Buffon +turned to the Birds. If this section were less exacting, yet it made +enormous claims upon his attention, and nine volumes were occupied +before the history of the class was concluded. Publication of "Des +Oiseaux" was begun in 1770, and continued intermittently until 1783. But +troubles dogged the great naturalist. The relations between him and +Daubenton had grown acute, and the latter, unwilling any longer to put +up with Buffon's love of vainglory, withdrew from the enterprise to +which his co-operation had imparted so much value. Serious illness, +also, and the death of<span class='pagenum'><a name="Page_16" id="Page_16">[Pg 16]</a></span> Buffon's wife, caused a long suspension of his +labours, which were, however, lightened by the assistance of Guéneau de +Montbéliard.</p> + +<p>One stroke of luck he had, which no one will begrudge the weary Titan. +James Bruce, of Kinnaird, on his return from Abyssinia in 1773, spent +some time with Buffon at his château in Montbard, and placed at his +disposal several of the remarkable discoveries he had made during his +travels. Buffon was not slow to appreciate this godsend. Not only did +he, quite properly, make the most of Bruce's disinterested help, but he +also expressed the confident hope that the British Government would +command the publication of Bruce's "precious" work. He went on to pay a +compliment to the English, and so commit them to this enterprise. "That +respectable nation," he asserts, "which excels all others in discovery, +can but add to its glory in promptly communicating to the world the +results of the excellent travellers' researches."</p> + +<p>Still unfettered by any scheme of classification, either scientific or +logical, Buffon begins his account of the birds with the eagles and +owls. To indicate his course throughout the vast class, it will suffice +to name a few of the principal birds in the order in which he takes them +after the birds of prey. These, then, are the ostrich, bustard, game +birds, pigeons, crows, singing birds, humming birds, parrots, cuckoos, +swallows, woodpeckers, toucans, kingfishers, storks, cranes, secretary +bird, herons, ibis, curlews, plovers, rails, diving birds, pelicans, +cormorants, geese, gulls, and penguins. With the volume dealing with the +picarian birds (woodpeckers) Buffon announces the withdrawal of Guéneau +de Montbéliard, and his obligations for advice and help to the Abbé +Bexon (1748–1784), Canon of Sainte Chapelle in Paris.</p> + + +<p><span class='pagenum'><a name="Page_17" id="Page_17">[Pg 17]</a></span></p><p class="subchap"><i>III.—Supplement and Sequel</i></p> + +<p>At the same time that the Birds volumes were passing through the press, +Buffon also issued periodically seven volumes of a supplement +(1774–1789), the last appearing posthumously under the editorship of +Count Lacépède. This consisted of an olla podrida of all sorts of +papers, such as would have won the heart of Charles Godfrey Leland. The +nature of the hotchpotch will be understood from a recital of some of +its contents, in their chronological order. It opened with an +introduction to the history of minerals, partly theoretical (concerning +light, heat, fire, air, water, earth, and the law of attraction), and +partly experimental (body heat, heat in minerals, the nature of +platinum, the ductility of iron). Then were discussed incandescence, +fusion, ships' guns, the strength and resistance of wood, the +preservation of forests and reafforestation, the cooling of the earth, +the temperature of planets, additional observations on quadrupeds +already described, accounts of animals not noticed before, such as the +tapir, quagga, gnu, nylghau, many antelopes, the vicuña, Cape ant-eater, +star-nosed mole, sea-lion, and others; the probabilities of life (a +subject on which the author plumed himself), and his essay on the Epochs +of Nature.</p> + +<p>Nor did these concurrent series of books exhaust his boundless energy +and ingenuity, for in the five years preceding his death (1783–1788), he +produced his "Natural History of Minerals" in five volumes, the last of +which was mainly occupied with electricity, magnetism, and the +loadstone. It is true that the researches of modern chemists have +wrought havoc with Buffon's work in this field; but this was his +misfortune rather than his fault, and leaves untouched the quantity of +his output.</p> + +<p>Buffon invoked the aid of the artist almost from the first, and his +"Natural History" is illustrated by <span class='pagenum'><a name="Page_18" id="Page_18">[Pg 18]</a></span>hundreds of full-page copper-plate +engravings, and embellished with numerous elegant headpiece designs. The +figures of the animals are mostly admirable examples of portraiture, +though the classical backgrounds lend a touch of the grotesque to many +of the compositions. Illustrations of anatomy, physiology, and other +features of a technical character are to be numbered by the score, and +are, of course, indispensable in such a work. The <i>editio princeps</i> is +cherished by collectors because of the 1,008 coloured plates ("Planches +Enluminées") in folio, the text itself being in quarto, by the younger +Daubenton, whose work was spiritedly engraved by Martinet. Apparently +anxious to illustrate one section exhaustively rather than several +sections in a fragmentary manner, the artist devoted himself chiefly to +the birds, which monopolise probably nine-tenths of the plates, and to +which he may also have been attracted by their gorgeous plumages.</p> + +<p>As soon as the labourer's task was over, his scientific friends thought +the best monument which they could raise to his memory was to complete +his "Natural History." This duty was discharged by two men, who, both +well qualified, worked, however, on independent lines. Count Lacépède, +adhering to the format of the original, added two volumes on the +Reptiles (1788–1789), five on the Fishes (1798–1803), and one on the +Cetaceans (1804). Sonnini de Manoncourt (1751–1812), feeling that this +edition, though extremely handsome, was cumbersome, undertook an +entirely new edition in octavo. This was begun in 1797, and finished in +1808. It occupied 127 volumes, and, Lacépède's treatises not being +available, Sonnini himself dealt with the Fishes (thirteen volumes) and +Whales (one volume), P.A. Latreille with the Crustaceans and Insects +(fourteen volumes), Denys-Montfort with the Molluscs (six volumes), F.M. +Dandin with the Reptiles (eight volumes), and C.F. Brisseau-Mirbel and +N. Jolyclerc with the Plants (eighteen <span class='pagenum'><a name="Page_19" id="Page_19">[Pg 19]</a></span>volumes). Sonnini's edition +constituted the cope-stone of Buffon's work, and remained the best +edition, until the whole structure was thrown down by the views of later +naturalists, who revolutionised zoology.</p> + + +<p class="subchap"><i>IV.—Place and Doctrine</i></p> + +<p>Buffon may justly be acclaimed as the first populariser of natural +history. He was, however, unscientific in his opposition to systems, +which, in point of fact, essentially elucidated the important doctrine +that a continuous succession of forms runs throughout the animal +kingdom. His recognition of this principle was, indeed, one of his +greatest services to the science.</p> + +<p>Another of his wise generalisations was that Nature proceeds by unknown +gradations, and consequently cannot adapt herself to formal analysis, +since she passes from one species to another, and often from one genus +to another, by shades of difference so delicate as to be wholly +imperceptible.</p> + +<p>In Buffon's eyes Nature is an infinitely diversified whole which it is +impossible to break up and classify. "The animal combines all the powers +of Nature; the forces animating it are peculiarly its own; it wishes, +does, resolves, works, and communicates by its senses with the most +distant objects. One's self is a centre where everything agrees, a point +where all the universe is reflected, a world in miniature." In natural +history, accordingly, each animal or plant ought to have its own +biography and description.</p> + +<p>Life, Buffon also held, abides in organic molecules. "Living beings are +made up of these molecules, which exist in countless numbers, which may +be separated but cannot be destroyed, which pierce into brute matter, +and, working there, develop, it may be animals, it may be plants, +according to the nature of the matter in which they are lodged. These +indestructible molecules circulate<span class='pagenum'><a name="Page_20" id="Page_20">[Pg 20]</a></span> throughout the universe, pass from +one being to another, minister to the continuance of life, provide for +nutrition and the growth of the individual, and determine the +reproduction of the species."</p> + +<p>Buffon further taught that the quantity and quality of life pass from +lower to higher stages—in Tennysonian phrase, men "rise on +stepping-stones of their dead selves to higher things"—and showed the +unity and structure of all beings, of whom man is the most perfect type.</p> + +<p>It has been claimed that Buffon in a measure anticipated Lamarck and +Darwin. He had already foreseen the mutability of species, but had not +succeeded in proving it for varieties and races. If he asserted that the +species of dog, jackal, wolf and fox were derived from a single one of +these species, that the horse came from the zebra, and so on, this was +far from being tantamount to a demonstration of the doctrine. In fact, +he put forward the mutability of species rather as probable theory than +as established truth, deeming it the corollary of his views on the +succession and connection of beings in a continuous series.</p> + +<p>Some case may be made out for regarding Buffon as the founder of +zoogeography; at all events he was the earliest to determine the natural +habitat of each species. He believed that species changed with climate, +but that no kind was found throughout all the globe. Man alone has the +privilege of being everywhere and always the same, because the human +race is one. The white man (European or Caucasian), the black man +(Ethiopian), the yellow man (Mongol), and the red man (American) are +only varieties of the human species. As the Scots express it with wonted +pith, "We're a' Jock Tamson's bairns."</p> + +<p>As to his geological works, Buffon expounded two theories of the +formation of the globe. In his "Théorie de la Terre" he supported the +Neptunists, who <span class='pagenum'><a name="Page_21" id="Page_21">[Pg 21]</a></span>attributed the phenomena of the earth to the action of +water. In his "Epoques de la Nature" he amplified the doctrines of +Leibniz, and laid down the following propositions: (1) The earth is +elevated at the equator and depressed at the poles in accordance with +the laws of gravitation and centrifugal force; (2) it possesses an +internal heat, apart from that received from the sun; (3) its own heat +is insufficient to maintain life; (4) the substances of which the earth +is composed are of the nature of glass, or can be converted into glass +as the result of heat and fusion—that is, are verifiable; (5) +everywhere on the surface, including mountains, exist enormous +quantities of shells and other maritime remains.</p> + +<p>To the theses just enumerated Buffon added what he called the +"monuments," or what Hugh Miller, a century later, more aptly described +as the Testimony of the Rocks. From a consideration of all these things, +Buffon at length arrived at his succession of the Epochs, or Seven Ages +of Nature, namely: (1) the Age of fluidity, or incandescence, when the +earth and planets assumed their shape; (2) the Age of cooling, or +consolidation, when the rocky interior of the earth and the great +vitrescible masses at its surface were formed; (3) the Age when the +waters covered the face of the earth; (4) the Age when the waters +retreated and volcanoes became active; (5) the Age when the elephant, +hippopotamus, rhinoceros, and other giants roamed through the northern +hemisphere; (6) the Age of the division of the land into the vast areas +now styled the Old and the New Worlds; and (7) the Age when Man +appeared.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_22" id="Page_22">[Pg 22]</a></span></p> +<h3>ROBERT CHAMBERS</h3> + +<p class="book"><big><a name="Vestiges_of_Creation" id="Vestiges_of_Creation"></a>Vestiges of Creation</big></p> + +<div class="blockquot"><p>Robert Chambers was born in Peebles, Scotland, July 10, 1802, and +died at St. Andrews on March 17, 1871. He was partner with his +brother in the publishing firm of W. & R. Chambers, was editor of +"Chambers's Journal," and was author of several works when he +published anonymously, in October 1844, the work by which his name +will always be remembered, "Vestiges of the Natural History of +Creation." His previous works, some thirty in number, did not deal +with science, and his labour in preparing his masterpiece was +commensurate with the courage which such an undertaking involved. +When the book was published, such interest and curiosity as to its +authorship were aroused that we have to go back to the publication +of "Waverley" for a parallel. Little else was talked about in +scientific circles. The work was violently attacked by many hostile +critics, F.W. Newman, author of an early review, being a +conspicuous exception. In the historical introduction to the +"Origin of Species," Darwin speaks of the "brilliant and powerful +style" of the "Vestiges," and says that "it did excellent service +in this country in calling attention to the subject, in removing +prejudice, and in thus preparing the ground for the reception of +analogous views." Darwin's idea of selection as the key to the +history of species does not occur in the "Vestiges," which belongs +to the Lamarckian school of unexamined belief in the hereditary +transmission of the effects of use and disuse.</p></div> + + +<p class="subchap"><i>I.—The Reign of Universal Law</i></p> + +<p><span class="smcap">The</span> stars are suns, and we can trace amongst them the working of the +laws which govern our sun and his family. In these universal laws we +must perceive intelligence; something of which the laws are but as the +expressions of the will and power. The laws of Nature cannot be regarded +as primary or independent causes of the phenomena of the physical world. +We come, in short, to a Being beyond Nature—its author, its God; +infinite, inconceivable, it may be, and yet one whom<span class='pagenum'><a name="Page_23" id="Page_23">[Pg 23]</a></span> these very laws +present to us with attributes showing that our nature is in some way a +faint and far-cast shadow of His, while all the gentlest and the most +beautiful of our emotions lead us to believe that we are as children in +His care and as vessels in His hand. Let it then be understood—and this +for the reader's special attention—that when natural law is spoken of +here, reference is made only to the mode in which the Divine Power is +exercised. It is but another phrase for the action of the ever-present +and sustaining God.</p> + +<p>Viewing Nature in this light, the pursuit of science is but the seeking +of a deeper acquaintance with the Infinite. The endeavour to explain any +events in her history, however grand or mysterious these may be, is only +to sit like a child at a mother's knee, and fondly ask of the things +which passed before we were born; and in modesty and reverence we may +even inquire if there be any trace of the origin of that marvellous +arrangement of the universe which is presented to our notice. In this +inquiry we first perceive the universe to consist of a boundless +multitude of bodies with vast empty spaces between. We know of certain +motions among these bodies; of other and grander translations we are +beginning to get some knowledge. Besides this idea of locality and +movement, we have the equally certain one of a former soft and more +diffused state of the materials of these bodies; also a tolerably clear +one as to gravitation having been the determining cause of both locality +and movement. From these ideas the general one naturally suggested to us +is—a former stage in the frame of material things, perhaps only a point +in progress from some other, or a return from one like the +present—universal space occupied with gasiform matter. This, however, +was of irregular constitution, so that gravitation caused it to break up +and gather into patches, producing at once the relative localities of +astral and solar systems, and the movements which they have since +<span class='pagenum'><a name="Page_24" id="Page_24">[Pg 24]</a></span>observed, in themselves and with regard to each other—from the daily +spinning of single bodies on their own axes, to the mazy dances of vast +families of orbs, which come to periods only in millions of years.</p> + +<p>How grand, yet how simple the whole of this process—for a God only to +conceive and do, and yet for man, after all, to trace out and ponder +upon. Truly must we be in some way immediate to the august Father, who +can think all this, and so come into His presence and council, albeit +only to fall prostrate and mutely adore.</p> + +<p>Not only are the orbs of space inextricably connected in the manner +which has been described, but the constitution of the whole is uniform, +for all consist of the same chemical elements. And now, in our version +of the romance of Nature, we descend from the consideration of +orb-filled space and the character of the universal elements, to trace +the history of our own globe. And we find that this falls significantly +into connection with the primary order of things suggested by Laplace's +theory of the origin of the solar system in a vast nebula or fire-mist, +which for ages past has been condensing under the influence of +gravitation and the radiation of its heat.</p> + + +<p class="subchap"><i>II.—History of the Earth's Crust</i></p> + +<p>When we study the earth's crust we find that it consists of layers or +strata, laid down in succession, the earlier under the influence of +heat, the later under the influence of water. These strata in their +order might be described as a record of the state of life upon our +planet from an early to a comparatively recent period. It is truly such +a record, but not one perfectly complete.</p> + +<p>Nevertheless, we find a noteworthy and significant sequence. We learn +that there was dry land long before the occurrence of the first fossils +of land plants and animals. In different geographical formations we +find<span class='pagenum'><a name="Page_25" id="Page_25">[Pg 25]</a></span> various species, though sometimes the same species is found in +different formations, having survived the great earth changes which the +record of the rocks indicates. There is an unbroken succession of animal +life from the beginning to the present epoch. Low down, where the +records of life begin, we find an era of backboneless animals only, and +the animal forms there found, though various, are all humble in their +respective lines of gradation.</p> + +<p>The early fishes were low, both with respect to their class as fishes, +and the order to which they belong—that of the cartilaginous or gristly +fishes. In all the orders of ancient animals there is an ascending +gradation of character from first to last. Further, there is a +succession from low to high types in fossil plants, from the earliest +strata in which they are found to the highest. Several of the most +important living species have left no record of themselves in any +formation beyond what are, comparatively speaking, modern. Such are the +sheep and the goat, and such, above all, is our own species. Compared +with many humbler animals, man is a being, as it were, of yesterday.</p> + +<p>Thus concludes the wondrous section of the earth's history which is told +by geology. It takes up our globe at an early stage in the formation of +its crust—conducts it through what we have every reason to believe were +vast spaces of time, in the course of which many superficial changes +took place, and vegetable and animal life was gradually evolved—and +drops it just at the point when man was apparently about to enter on the +scene. The compilation of such a history, from materials of so +extraordinary a character, and the powerful nature of the evidence which +these materials afford, are calculated to excite our admiration, and the +result must be allowed to exalt the dignity of science as a product of +man's industry and his reason.</p> + +<p>It is now to be remarked that there is nothing in the<span class='pagenum'><a name="Page_26" id="Page_26">[Pg 26]</a></span> whole series of +operations displayed in inorganic geology which may not be accounted for +by the agency of the ordinary forces of Nature. Those movements of +subterranean force which thrust up mountain ranges and upheaved +continents stand in inextricable connection, on the one hand, with the +volcanoes which are yet belching forth lavas and shaking large tracts of +ground, as, on the other, with the primitive incandescent state of the +earth. Those forces which disintegrated the early rocks, of which +detritus formed new beds at the bottom of the sea, are still seen at +work to the same effect.</p> + +<p>To bring these truths the more nearly before us, it is possible to make +a substance resembling basalt in a furnace; limestone and sandstone have +both been formed from suitable materials in appropriate receptacles; the +phenomena of cleavage have, with the aid of electricity, been simulated +on a small scale, and by the same agent crystals are formed. In short, +the remark which was made regarding the indifference of the cosmical +laws to the scale on which they operated is to be repeated regarding the +geological.</p> + +<p>A common furnace will sometimes exemplify the operation of forces which +have produced the Giant's Causeway; and in a sloping ploughed field +after rain we may often observe, at the lower end of a furrow, a handful +of washed and neatly deposited mud or sand, capable of serving as an +illustration of the way in which Nature has produced the deltas of the +Nile and Ganges. In the ripple-marks on sandy beaches of the present day +we see Nature's exact repetition of the operations by which she +impressed similar features on the sandstones of the carboniferous era. +Even such marks as wind-slanted rain would in our day produce on +tide-deserted sands have been read upon tablets of the ancient strata.</p> + +<p>It is the same Nature—that is to say, God through or in the manner of +Nature—working everywhere and<span class='pagenum'><a name="Page_27" id="Page_27">[Pg 27]</a></span> in all time, causing the wind to blow, +and the rain to fall, and the tide to ebb and flow, inconceivable ages +before the birth of our race, as now. So also we learn from the conifers +of those old ages that there were winter and summer upon earth, before +any of us lived to liken the one to all that is genial in our own +nature, or to say that the other breathed no airs so unkind as man's +ingratitude. Let no one suppose there is any necessary disrespect for +the Creator in thus tracing His laws in their minute and familiar +operations. There is really no true great and small, grand and familiar, +in Nature. Such only appear when we thrust ourselves in as a point from +which to start in judging. Let us pass, if possible, beyond immediate +impressions, and see all in relation to Cause, and we shall chastenedly +admit that the whole is alike worshipful.</p> + +<p>The Creator, then, is seen to have formed our earth, and effected upon +it a long and complicated series of changes, in the same manner in which +we find that he conducts the affairs of Nature before our living eyes; +that is, in the manner of natural law. This is no rash or unauthorised +affirmation. It is what we deduce from the calculation of a Newton and a +Laplace on the one hand, and from the industrious observation of facts +by a Murchison and a Lyell on the other. It is a point of stupendous +importance in human knowledge; here at once is the whole region of the +inorganic taken out of the dominion of marvel, and placed under an idea +of Divine regulation.</p> + + +<p class="subchap"><i>III.—The History of the Earth's Life</i></p> + +<p>Mixed up, however, with the geological changes, and apparently as final +object connected with the formation of the globe itself, there is +another set of phenomena presented in the course of our history—the +coming into existence, namely, of a long suite of living things, +<span class='pagenum'><a name="Page_28" id="Page_28">[Pg 28]</a></span>vegetable and animal, terminating in the families which we still see +occupying the surface. The question arises: In what manner has this set +of phenomena originated? Can we touch at and rest for a moment on the +possibility of plants and animals having likewise been produced in a +natural way, thus assigning immediate causes of but one character for +everything revealed to our sensual observation; or are we at once to +reject this idea, and remain content, either to suppose that creative +power here acted in a different way, or to believe unexaminingly that +the inquiry is one beyond our powers? Taking the last question first, I +would reply that I am extremely loth to imagine that there is anything +in Nature which we should, for any reason, refrain from examining. If we +can infer aught from the past history of science, it is that the whole +of Nature is a legitimate field for the exercise of our intellectual +faculties; that there is a connection between this knowledge and our +well-being; and that, if we may judge from things once despaired of by +our inquiring reason, but now made clear and simple, there is none of +Nature's mysteries which we may not hopefully attempt to penetrate. To +remain idly content to presume a various class of immediate causes for +organic Nature seems to me, on this ground, equally objectionable.</p> + +<p>With respect to the other question the idea has several times arisen +that some natural course was observed in the production of organic +things, and this even before we were permitted to attain clear +conclusions regarding inorganic nature. It was always set quickly aside +as unworthy of serious consideration. The case is different now, when we +have admitted law in the whole domain of the inorganic.</p> + +<p>Otherwise, the absurdities into which we should be led must strike every +reflecting mind. The Eternal Sovereign arranges a solar or an astral +system, by dispositions imparted primordially to matter; he causes, by<span class='pagenum'><a name="Page_29" id="Page_29">[Pg 29]</a></span> +the same means, vast oceans to join and continents to rise, and all the +grand meteoric agencies to proceed in ceaseless alternation, so as to +fit the earth for a residence of organic beings. But when, in the course +of these operations, fuci and corals are to be, for the first time, +placed in these oceans, a change in his plan of administration is +required. It is not easy to say what is presumed to be the mode of his +operations. The ignorant believe the very hand of Deity to be at work. +Amongst the learned, we hear of "creative fiats," "interferences," +"interpositions of the creative energy," all of them very obscure +phrases, apparently not susceptible of a scientific explanation, but all +tending simply to this: that the work was done in a marvellous way, and +not in the way of Nature.</p> + +<p>But we need not assume two totally distinct modes of the exercise of the +divine power—one in the course of inorganic nature and the other in +intimately connected course of organic nature.</p> + +<p>Indeed, when all the evidence is surveyed, it seems difficult to resist +the impression that vestiges, at least, are seen of the manner and +method of the Creator in this part of His work. It appears to be a case +in which rigid proof is hardly to be looked for. But such evidences as +exist are remarkably consistent and harmonious. The theory pointed to +consorts with everything else which we have learned accurately regarding +the history of the universe. Science has not one positive affirmation on +the other side. Indeed, the view opposed to it is not one in which +science is concerned; it appears as merely one of the prejudices formed +in the non-age of our race.</p> + +<p>For the history, then, of organic nature, I embrace, not as a proved +fact, but as a rational interpretation of things as far as science has +revealed them, the idea of progressive development. We contemplate the +simplest and most primitive types of being as giving birth to a<span class='pagenum'><a name="Page_30" id="Page_30">[Pg 30]</a></span> type +superior to it; this again producing the next higher, and so on to the +highest. We contemplate, in short, a universal gestation of Nature, like +that of the individual being, and attended as little by circumstances of +a miraculous kind as the silent advance of an ordinary mother from one +week to another of her pregnancy.</p> + +<p>Thus simple—after ages of marvelling—appears organic creation, while +yet the whole phenomena are, in another point of view, wonders of the +highest kind, being the undoubted results of ordinances arguing the +highest attributes of foresight, skill and goodness on the part of their +Divine Author.</p> + +<p>If, finally, we study the mind of man, we find that its Almighty Author +has destined it, like everything else, to be developed from inherent +qualities.</p> + +<p>Thus the whole appears complete on one principle. The masses of space +are formed by law; law makes them in due time theatres of existence for +plants and animals; sensation, disposition, intellect, are all in like +manner sustained in action by law.</p> + +<p>It is most interesting to observe into how small a field the whole of +the mysteries of Nature thus ultimately resolve themselves. The +inorganic has been thought to have one final comprehensive +law—gravitation. The organic, the other great department of mundane +things, rests in like manner on one law, and that is—development. Nor +may even these be after all twain, but only branches of one still more +comprehensive law, the expression of a unity flowing immediately from +the One who is first and last.</p> + + +<p class="subchap"><i>IV.—The Future and its Meaning</i></p> + +<p>The question whether the human race will ever advance far beyond its +present position in intellect and morals is one which has engaged much +attention. Judging<span class='pagenum'><a name="Page_31" id="Page_31">[Pg 31]</a></span> from the past, we cannot reasonably doubt that great +advances are yet to be made; but, if the principle of development be +admitted, these are certain, whatever may be the space of time required +for their realisation. A progression resembling development may be +traced in human nature, both in the individual and in large groups of +men. Not only so, but by the work of our thoughtful brains and busy +hands we modify external nature in a way never known before. The +physical improvements wrought by man upon the earth's surface I conceive +as at once preparations for, and causes of, the possible development of +higher types of humanity, beings less strong in the impulsive parts of +our nature, more strong in the reasoning and moral, more fitted for the +delights of social life, because society will then present less to dread +and more to love.</p> + +<p>The history and constitution of the world have now been hypothetically +explained, according to the best lights which a humble individual has +found within the reach of his perceptive and reasoning faculties.</p> + +<p>We have seen a system in which all is regularity and order, and all +flows from, and is obedient to, a divine code of laws of unbending +operation. We are to understand from what has been laid before us that +man, with his varied mental powers and impulses, is a natural problem of +which the elements can be taken cognisance of by science, and that all +the secular destinies of our race, from generation to generation, are +but evolutions of a law statuted and sustained in action by an all-wise +Deity.</p> + +<p>There may be a faith derived from this view of Nature sufficient to +sustain us under all sense of the imperfect happiness, the calamities, +the woes and pains of this sphere of being. For let us but fully and +truly consider what a system is here laid open to view and we cannot +well doubt that we are in the hands of One who is both able and willing +to do us the most entire justice. Surely,<span class='pagenum'><a name="Page_32" id="Page_32">[Pg 32]</a></span> in such a faith we may well +rest at ease, even though life should have been to us but a protracted +malady. Thinking of all the contingencies of this world as to be in time +melted into or lost in some greater system, to which the present is only +subsidiary, let us wait the end with patience and be of good cheer.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_33" id="Page_33">[Pg 33]</a></span></p> +<h3>GEORGES CUVIER</h3> + +<p class="book"><big><a name="The_Surface_of_the_Globe" id="The_Surface_of_the_Globe"></a>The Surface of the Globe</big></p> + +<div class="blockquot"><p>Georges Cuvier was born Aug. 24, 1769, at Montbéliard, France. He +had a brilliant academic career at Stuttgart Academy, and in 1795, +at the age of twenty-six, he was appointed assistant professor of +comparative anatomy at the Museum d'Histoire Naturelle in Paris, +and was elected a member of the National Institute. From this date +onwards to his death in 1832, his scientific industry was +remarkable. Both as zoologist and palæontologist he must be +regarded as one of the greatest pioneers of science. He filled many +important scientific posts, including the chair of Natural History +in the Collège de France, and a professorship at the Jardin des +Plantes. In 1808 he was made member of the Council of the Imperial +University; and in 1814, President of the Council of Public +Instruction. In 1826 he was made grand officer of the Legion of +Honour, and five years later was made a peer of France. The +"Discours sur les Révolutions de la Surface du Globe," published in +1825, is essentially a preliminary discourse to the author's +celebrated work, "Recherches sur les Ossemens fossiles de +Quadrupèdes." It is an endeavour to trace the relationship between +the changes which have taken place on the surface of the globe and +the changes which have taken place in its animal inhabitants, with +especial reference to the evidence afforded by fossil remains of +quadrupeds. "It is apparent," Cuvier writes, "that the bones of +quadrupeds conduct us, by various reasonings, to more precise +results than any other relics of organised bodies." The two books +together may be considered the first really scientific +palæontology.</p></div> + + +<p class="subchap"><i>I.—Effects of Geological Change</i></p> + +<p><span class="smcap">My</span> first object will be to show how the fossil remains of the +terrestrial animals are connected with the theory of the earth. I shall +afterwards explain the principles by which fossil bones may be +identified. I shall give a rapid sketch of new species discovered by the +application of these principles. I shall then show how<span class='pagenum'><a name="Page_34" id="Page_34">[Pg 34]</a></span> far these +varieties may extend, owing to the influence of the climate and +domestication. I shall then conceive myself justified in concluding that +the more considerable differences which I have discovered are the +results of very important catastrophes. Afterwards I shall explain the +peculiar influence which my researches should exercise on the received +opinions concerning the revolutions of the globe. Finally, I shall +examine how far the civil and religious history of nations accords with +the results of observation on the physical history of the earth.</p> + +<p>When we traverse those fertile plains, where tranquil waters cherish, as +they flow, an abundant vegetation, and where the soil, trod by a +numerous people, adorned with flourishing villages, rich cities, and +superb monuments, is never disturbed save by the ravages of war, or the +oppression of power, we can hardly believe that Nature has also had her +internal commotions. But our opinions change when we dig into this +apparently peaceful soil, or ascend its neighboring hills. The lowest +and most level soils are composed of horizontal strata, and all contain +marine productions to an innumerable extent. The hills to a very +considerable height are composed of similar strata and similar +productions. The shells are sometimes so numerous as to form the entire +mass of the soil, and all quarters of the globe exhibit the same +phenomenon.</p> + +<p>The time is past when ignorance could maintain that these remains of +organised bodies resulted from the caprice of Nature, and were +productions formed in the bosom of the earth by its generative powers; +for a scrupulous comparison of the remains shows not the slightest +difference between the fossil shells and those that are now found in the +ocean. It is clear, then, that they inhabited the sea, and that they +were deposited by the sea in the places where they are now found; and it +follows, too, that the sea rested in these places long<span class='pagenum'><a name="Page_35" id="Page_35">[Pg 35]</a></span> enough to form +regular, dense, vast deposits of aquatic animals.</p> + +<p>The bed of the sea, accordingly, must have undergone some change either +in extent or situation.</p> + +<p>Further, we find under the horizontal strata, <i>inclined</i> strata. Thus +the sea, previously to the formation of the horizontal strata, must have +formed others, which have been broken, inclined, and overturned by some +unknown causes.</p> + +<p>More than this, we find that the fossils vary with the depth of the +strata, and that the fossils of the deeper and more ancient strata +exhibit a formation proper to themselves; and we find in some of the +strata, too, remains of terrestrial life.</p> + +<p>The evidence is thus plain that the animal life in the sea has varied, +and that parts of the earth's surface have been alternately dry land and +ocean. The very soil, which terrestrial animals at present inhabit has a +history of previous animal life, and then submersion under the sea.</p> + +<p>The reiterated irruptions and retreats of the sea have not all been +gradual, but, on the contrary, they have been produced by sudden +catastrophes. The last catastrophe, which inundated and again left dry +our present continents, left in the northern countries the carcasses of +large quadrupeds, which were frozen, and which are preserved even to the +present day, with their skin, hair and flesh. Had they not been frozen +the moment they were killed, they must have putrefied; and, on the other +hand, the intense frost could not have been the ordinary climatic +condition, for they could not have existed at such low temperatures. In +the same instant, then, in which these animals perished the climate +which they inhabited must have undergone a complete revolution.</p> + +<p>The ruptures, the inclinations, the overturnings of the more ancient +strata, likewise point to sudden and violent changes.</p> + +<p><span class='pagenum'><a name="Page_36" id="Page_36">[Pg 36]</a></span></p><p>Animal life, then, has been frequently disturbed on this earth by +terrific catastrophes. Living beings innumerable have perished. The +inhabitants of the dry land have been engulfed by deluges; and the +tenants of the water, deserted by their element, have been left to +perish from drought.</p> + +<p>Even ancient rocks formed or deposited before the appearance of life on +the earth show signs of terrific violence.</p> + +<p>It has been maintained by some that the causes now at work altering the +face of the world are sufficient to account for all the changes through +which it has passed: but that is not so. None of the agents Nature now +employs—rain, thaw, rivers, seas, volcanoes—would have been adequate +to produce her ancient works.</p> + +<p>To explain the external crust of the world, we require causes other than +those present in operation, and a thousand extraordinary theories have +been advanced. Thus, according to one philosopher, the earth has +received in the beginning a uniform light crust which caused the abysses +of the ocean, and was broken to produce the Deluge. Another supposed the +Deluge to be caused by the momentary suspension of the cohesion of +minerals.</p> + +<p>Even accomplished scientists and philosophers have advanced impossible +and contradictory theories.</p> + +<p>All attempts at explanation have been stultified by an ignorance of the +facts to be explained, or by a partial survey of them, and especially by +a neglect of the evidence afforded by fossils. How was it possible not +to perceive that the theory of the earth owes its origin to fossils +alone? They alone, in truth, inform us with any certainty that the earth +has not always had the same covering, since they certainly must have +lived upon its surface before they were buried in its depths. If there +were only strata without fossils, one might maintain that the strata had +all been formed together. Hitherto, in fact, philosophers have been at +variance on every<span class='pagenum'><a name="Page_37" id="Page_37">[Pg 37]</a></span> point save one, and that is that the sea has changed +its bed; and how could this have been known except for fossils?</p> + +<p>From this consideration I was led to study fossils; and since the field +was immense I was obliged to specialise in one department of fossils, +and selected for study the fossil bones of quadrupeds. I made this +selection because only from a study of fossil quadrupeds can one hope to +ascertain the number and periods and contents of irruptions of the sea; +and because, since the number of quadrupeds is limited, and most +quadrupeds known, we have better means of assuring ourselves if the +fossil remains are remains of extinct or extant animals. Animals such as +the griffin, the cartazonon, the unicorn, never lived, and there are +probably very few quadrupeds now living which have not been found by +man.</p> + +<p>But though the study of fossil quadruped be enlightening, it has its own +special difficulties. One great difficulty arises from the fact that it +is very rare to find a fossil skeleton approaching to a complete state.</p> + +<p>Fortunately, however, there is a principle in comparative anatomy which +lessens this difficulty. Every organised being constitutes a complete +and compact system with all its parts in mutual correspondence. None of +its parts can be changed without changing other parts, and consequently +each part, taken separately, indicates the others.</p> + +<p>Thus, if the intestines of an animal are made to digest raw flesh, its +jaws must be likewise constructed to devour prey, its claws to seize and +tear it, its teeth to rend it, its limbs to overtake it, its organs of +sense to discern it afar. Again, in order to enable the jaw to seize +with facility, a certain form of condyle is necessary, and the zygomatic +arch must be well developed to give attachment to the masseter muscle. +Again, the muscles of the neck must be powerful, whence results a +special form<span class='pagenum'><a name="Page_38" id="Page_38">[Pg 38]</a></span> in the vertebræ and the occiput, where the muscles are +attached. Yet again, in order that the claws may be effective, the +toe-bones must have a certain form, and must have muscles and tendons +distributed in a certain way. In a word, the form of the tooth +necessitates the form of the condyle, of the shoulder-blade, and of the +claws, of the femur, and of all the other bones, and all the other bones +taken separately will give the tooth. In this manner anyone who is +scientifically acquainted with the laws of organic economy may from a +fragment reconstruct the whole animal. The mark of a cloven hoof is +sufficient to tell the form of the teeth and jaws and vertebræ and +leg-bones and thigh-bones and pelvis of the animal. The least fragment +of bone, the smallest apophysis, has a determinative character in +relation to the class, the order, the genus, and species to which it may +belong. This is so true that, if we have only a single extremity of bone +well preserved, we may, with application and a skilful use of analogy +and exact comparison, determine all those points with as much certainty +as if we were in possession of the entire animal. By the application of +these principles we have identified and classified the fossil remains of +more than one hundred and fifty mammalia.</p> + + +<p class="subchap"><i>II.—What the Fossils Teach</i></p> + +<p>An examination of the fossils on the lines I have indicated shows that +out of one hundred and fifty mammiferous and oviparous quadrupeds, +ninety are unknown to present naturalists, and that in the older layers +such oviparous quadrupeds as the ichthyosauri and plesiosauri abound. +The fossil elephant, the rhinoceros, the hippopotamus, and the mastodons +are not found in the more ancient layers. In fact, the species which +appear the same as ours are found only in superficial deposits.</p> + +<p>Now, it cannot be held that the present races of animals<span class='pagenum'><a name="Page_39" id="Page_39">[Pg 39]</a></span> differ from +the ancient races merely by modifications produced by local +circumstances and change of climate—for if species gradually changed, +we must find traces of these gradual modifications, and between the +palæotheria and the present species we should have discovered some +intermediate formation; but to the present time none of these have +appeared.</p> + +<p>Why have not the bowels of the earth preserved the monuments of so +remarkable a genealogy unless it be that the species of former ages were +as constant as our own, or at least because the catastrophe that +destroyed them had not left them time to give evidence of the changes?</p> + +<p>Further, an examination of animals shows that though their superficial +characteristics, such as colour and size, are changeable, yet their more +radical characteristics do not change. Even the artificial breeding of +domestic animals can produce only a limited degree of variation. The +maximum variation known at the present time in the animal kingdom is +seen in dogs, but in all the varieties the relations of the bones remain +the same and the shape of the teeth undergoes no palpable change.</p> + +<p>I know that some naturalists rely much on the thousands of ages which +they can accumulate with a stroke of the pen; but there is nothing which +proves that time will effect any more than climate and a state of +domestication. I have endeavoured to collect the most ancient documents +of the forms of animals. I have examined the engravings of animals +including birds on the numerous columns brought from Egypt to Rome. M. +Saint Hilaire collected all the mummies of animals he could obtain in +Egypt—cats, ibises, birds of prey, dogs, monkeys, crocodiles, etc.—and +we cannot find any more difference between them and those of the present +day than between human mummies of that date and skeletons of the present +day.</p> + +<p>There is nothing, then, in known facts which can support<span class='pagenum'><a name="Page_40" id="Page_40">[Pg 40]</a></span> the opinion +that the new genera discovered among fossils—the palæotheria, +anoplotheria, megalonyces, mastodontes, pterodactyli, ichthyosauri, +etc.—could have been the sources of any animals now existing, which +would differ only by the influence of time or climate.</p> + +<p>As yet no human bones have been discovered in the regular layers of the +surface of the earth, so that man probably did not exist in the +countries where fossil bones are found at the epoch of the revolutions +which buried these bones, for there cannot be assigned any reason why +mankind should have escaped such overwhelming catastrophes, or why human +remains should not be discovered. Man <i>may</i> have inhabited some confined +tract of country which escaped the catastrophe, but his establishment in +the countries where the fossil remains of land animals are found—that +is to say, in the greatest part of Europe, Asia, and America—is +necessarily posterior not only to the revolutions which covered these +bones, but even to those which have laid open the strata which envelop +them; whence it is clear that we can draw neither from the bones +themselves nor from the rocks which cover them any argument in favour of +the antiquity of the human species in these different countries. On the +contrary, in closely examining what has taken place on the surface of +the globe, since it was left dry for the last time, we clearly see that +the last revolution, and consequently the establishment of present +society, cannot be very ancient. An examination of the amount of +alluvial matter deposited by rivers, of the progress of downs, and of +other changes on the surface of the earth, informs us clearly that the +present state of things did not commence at a very remote period.</p> + +<p>The history of nations confirms the testimony of the fossils and of the +rocks. The chronology of none of the nations of the West can be traced +unbroken farther back than 3,000 years. The Pentateuch, the most ancient +document the world possesses, and all subsequent writings<span class='pagenum'><a name="Page_41" id="Page_41">[Pg 41]</a></span> allude to a +universal deluge, and the Pentateuch and Vedas and Chou-king date this +catastrophe as not more than 5,400 years before our time. Is it possible +that mere chance gave a result so striking as to make the traditional +origin of the Assyrian, Indian, and Chinese monarchies agree in being as +remote as 4,000 or 5,000 years back? Would the ideas of nations with so +little inter-communication, whose language, religion, and laws have +nothing in common, agree on this point if they were not founded on +truth? Even the American Indians have their Noah or Deucalion, like the +Indians, Babylonians, and Greeks.</p> + +<p>It may be said that the long existence of ancient nations is attested by +their progress in astronomy. But this progress has been much +exaggerated. But what would this astronomy prove even if it were more +perfect? Have we calculated the progress which a science would make in +the bosom of nations which had no other? If among the multitude of +persons solely occupied with astronomy, even then, all that these people +knew might have been discovered in a few centuries, when only 300 years +intervened between Copernicus and Laplace.</p> + +<p>Again, it has been pretended that the zodiacal figures on ancient +temples give proof of a remote antiquity; but the question is very +complicated, and there are as many opinions as writers, and certainly no +conclusions against the newness of continents and nations can be based +on such evidence. The zodiac itself has been considered a proof of +antiquity, but the arguments brought forward are undoubtedly unsound.</p> + +<p>Even if these various astronomical proofs were as certain as they are +unconvincing, what conclusion could we draw against the great +catastrophe so indisputably demonstrated? We should only have the right +to conclude that astronomy was among the sciences preserved by those +persons whom the catastrophe spared.</p> + +<p><span class='pagenum'><a name="Page_42" id="Page_42">[Pg 42]</a></span></p><p>In conclusion, if there be anything determined in geology, it is that +the surface of our globe has been subjected to a revolution within 5,000 +years, and that this revolution buried the countries formerly inhabited +by man and modern animals, and left the bottom of the former sea dry as +a habitation for the few individuals it spared. Consequently, our +present human societies have arisen since this catastrophe.</p> + +<p>But the countries now inhabited had been inhabited before, as fossils +show, by animals, if not by mankind, and had been overwhelmed by a +previous deluge; and, indeed, judging by the different orders of animal +fossils we find, they had perhaps undergone two or three irruptions of +the sea.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_43" id="Page_43">[Pg 43]</a></span></p> +<h3>CHARLES DARWIN</h3> + +<p class="book"><big><a name="The_Origin_of_Species" id="The_Origin_of_Species"></a>The Origin of Species</big></p> + +<div class="blockquot"><p>Charles Robert Darwin was born at Shrewsbury, England, Feb. 12, +1809, of a family distinguished on both sides. Abandoning medicine +for natural history, he joined H.M.S. Beagle in 1831 on the five +years' voyage, which he described in "The Voyage of the Beagle," +and to which he refers in the introduction to his masterpiece. The +"Origin of Species" containing, in the idea of natural selection, +the distinctive contribution of Darwin to the theory of organic +evolution, was published in November, 1859. In only one brief +sentence did he there allude to man, but twelve years later he +published the "Descent of Man," in which the principles of the +earlier volume found their logical outcome. In other works Darwin +added vastly to our knowledge of coral reefs, organic variation, +earthworms, and the comparative expression of the emotions in man +and animals. Darwin died in ignorance of the work upon variation +done by his great contemporary, Gregor Mendel, whose work was +rediscovered in 1900. "Mendelism" necessitates much modification of +Darwin's work, which, however, remains the maker of the greatest +epoch in the study of life and the most important contribution to +that study ever made. Its immortal author died on April 19, 1882, +and was buried in Westminster Abbey.</p></div> + + +<p class="subchap"><i>I.—Creation or Evolution?</i></p> + +<p><span class="smcap">When</span> on board H.M.S. Beagle as naturalist, I was much struck with +certain facts in the distribution of the organic beings inhabiting South +America, and in the geographical relations of the present to the past +inhabitants of that continent. These facts, as will be seen in the +latter chapters of this volume, seemed to throw some light on the origin +of species—that mystery of mysteries, as it has been called by one of +our greatest philosophers. On my return home, in 1837, it occurred to me +that something might perhaps be made out on this question by patiently +accumulating and reflecting on<span class='pagenum'><a name="Page_44" id="Page_44">[Pg 44]</a></span> all sorts of facts which could possibly +have any bearing on it. After five years' work, I allowed myself to +speculate on the subject, and drew up some short notes; these I enlarged +in 1844 into a sketch of the conclusions which then seemed to me +probable. From that period to the present day I have steadily pursued +the same object. I hope that I may be excused for entering on these +personal details, as I give them to show that I have not been hasty in +coming to a decision.</p> + +<p>In considering the origin of species, it is quite conceivable that a +naturalist, reflecting on the mutual affinities of organic beings, on +their embryological relations, their geographical distribution, +geological succession, and other such facts, might come to the +conclusion that species had not been independently created, but had +descended, like varieties, from other species. Nevertheless, such a +conclusion, even if well founded, would be unsatisfactory, until it +could be shown how the innumerable species inhabiting this world have +been modified so as to acquire that perfection of structure and +co-adaptation which justly excites our admiration.</p> + +<p>Naturalists continually refer to external conditions, such as climate, +food, etc., as the only possible cause of variation. In one limited +sense, as we shall hereafter see, this may be true; but it is +preposterous to attribute to mere external conditions the structure, for +instance, of the woodpecker, with its feet, tail, beak, and tongue, so +admirably adapted to catch insects under the bark of trees. In the case +of the mistletoe, which draws its nourishment from certain trees, which +has seeds that must be transported by certain birds, and which has +flowers with separate sexes absolutely requiring the agency of certain +insects to bring pollen from one flower to the other, it is equally +preposterous to account for the structure of the parasite, with its +relations to several distinct organic beings, by the effects of external +conditions, or of habit, or of the volition of the plant itself<span class='pagenum'><a name="Page_45" id="Page_45">[Pg 45]</a></span>.</p> + +<p>It is, therefore, of the highest importance to gain a clear insight into +the means of modification and co-adaptation. At the beginning of my +observations it seemed to me probable that a careful study of +domesticated animals and of cultivated plants would offer the best +chance of making out this obscure problem. Nor have I been disappointed; +in this and in all other perplexing cases I have invariably found that +our knowledge, imperfect though it be, of variation under domestication, +afforded the best and safest clue. I may venture to express my +conviction of the high value of such studies, although they have been +very commonly neglected by naturalists.</p> + +<p>Although much remains obscure, and will long remain obscure, I can +entertain no doubt, after the most deliberate study and dispassionate +judgment of which I am capable, that the view which most naturalists +until recently entertained, and which I formerly entertained—namely, +that each species has been independently created—is erroneous. I am +fully convinced that species are not immutable, but that those belonging +to what are called the same genera are lineal descendants of some other +and generally extinct species, in the same manner as the acknowledged +varieties of any one species are the descendants of that species. +Furthermore, I am also convinced that Natural Selection has been the +most important, but not the exclusive, means of modification.</p> + + +<p class="subchap"><i>II.—Variation and Selection</i></p> + +<p>All living beings vary more or less from one another, and though +variations which are not inherited are unimportant for us, the number +and diversity of inheritable deviations of structure, both those of +slight and those of considerable physiological importance, are endless.</p> + +<p>No breeder doubts how strong is the tendency to inheritance; that like +produces like is his fundamental <span class='pagenum'><a name="Page_46" id="Page_46">[Pg 46]</a></span>belief. Doubts have been thrown on +this principle only by theoretical writers. When any deviation of +structure often appears, and we see it in the father and child, we +cannot tell whether it may not be due to the same cause having acted on +both; but when amongst individuals, apparently exposed to the same +conditions, any very rare deviation, due to some extraordinary +combination of circumstances, appears in the parent—say, once amongst +several million individuals—and it re-appears in the child, the mere +doctrine of chances almost compels us to attribute its reappearance to +inheritance.</p> + +<p>Everyone must have heard of cases of albinism, prickly skin, hairy +bodies, etc., appearing in members of the same family. If strange and +rare deviations of structure are really inherited, less strange and +commoner deviations may be freely admitted to be inheritable. Perhaps +the correct way of viewing the whole subject would be to look at the +inheritance of every character whatever as the rule, and non-inheritance +as the anomaly.</p> + +<p>The laws governing inheritance are for the most part unknown. No one can +say why the same peculiarity in different individuals of the same +species, or in different species, is sometimes inherited and sometimes +not so; why the child often reverts in certain characters to its +grandfather or grandmother, or more remote ancestor; why a peculiarity +is often transmitted from one sex to both sexes, or to one sex alone, +more commonly but not exclusively to the like sex.</p> + +<p>The fact of heredity being given, we have evidence derived from human +practice as to the influence of selection. There are large numbers of +domesticated races of animals and plants admirably suited in various +ways to man's use or fancy—adapted to the environment of which his need +and inclination are the most essential constituents. We cannot suppose +that all the breeds were suddenly produced as perfect and as useful as +we now see them; indeed, in many cases, we know that this<span class='pagenum'><a name="Page_47" id="Page_47">[Pg 47]</a></span> has not been +their history. The key is man's power of accumulative selection. Nature +gives successive variations; man adds them up in certain directions +useful to him. In this sense he may be said to have made for himself +useful breeds.</p> + +<p>The great power of this principle of selection is not hypothetical. It +is certain that several of our eminent breeders have, even within a +single lifetime, modified to a large extent their breeds of cattle and +sheep. What English breeders have actually effected is proved by the +enormous prices given for animals with a good pedigree; and these have +been exported to almost every quarter of the world. The same principles +are followed by horticulturists, and we see an astonishing improvement +in many florists' flowers, when the flowers of the present day are +compared with drawings made only twenty or thirty years ago.</p> + +<p>The practice of selection is far from being a modern discovery. The +principle of selection I find distinctly given in an ancient Chinese +encyclopædia. Explicit rules are laid down by some of the Roman +classical writers. It is clear that the breeding of domestic animals was +carefully attended to in ancient times, and is now attended to by the +lowest savages. It would, indeed, have been a strange fact had attention +not been paid to breeding, for the inheritance of good and bad qualities +is so obvious.</p> + +<p>Study of the origin of our domestic races of animals and plants leads to +the following conclusions. Changed conditions of life are of the highest +possible importance in causing variability, both by acting directly on +the organisation, and indirectly by affecting the reproductive system. +Spontaneous variation of unknown origin plays its part. Some, perhaps a +great, effect may be attributed to the increased use or disuse of parts.</p> + +<p>The final result is thus rendered infinitely complex. In some cases the +intercrossing of aboriginally distinct<span class='pagenum'><a name="Page_48" id="Page_48">[Pg 48]</a></span> species appears to have played +an important part in the origin of our breeds. When several breeds have +once been formed in any country, their occasional intercrossing, with +the aid of selection, has, no doubt, largely aided in the formation of +new sub-breeds; but the importance of crossing has been much +exaggerated, both in regard to animals and to those plants which are +propagated by seed. Over all these causes of change, the accumulative +action of selection, whether applied methodically and quickly, or +unconsciously and slowly, but more efficiently, seems to have been the +predominant power.</p> + + +<p class="subchap"><i>III.—Variation Under Nature</i></p> + +<p>Before applying these principles to organic beings in a state of nature, +we must ascertain whether these latter are subject to any variation. We +find variation everywhere. Individual differences, though of small +interest to the systematist, are of the highest importance for us, for +they are often inherited; and they thus afford materials for natural +selection to act and accumulate, in the same manner as man accumulates +in any given direction individual differences in his domesticated +productions. Further, what we call varieties cannot really be +distinguished from species in the long run, a fact which we can clearly +understand if species once existed as varieties, and thus originated. +But the facts are utterly inexplicable if species are independent +creations.</p> + +<p>How have all the exquisite adaptations of one part of the body to +another part, and to the conditions of life, and of one organic being to +another being, been perfected? For everywhere we find these beautiful +adaptations.</p> + +<p>The answer is to be found in the struggle for life. Owing to this +struggle, variations, however slight, and from whatever cause +proceeding, if they be in any degree<span class='pagenum'><a name="Page_49" id="Page_49">[Pg 49]</a></span> profitable to the individuals of a +species in their infinitely complex relations to other organic beings +and to their physical conditions of life, will tend to the preservation +of such individuals, and will generally be inherited by the offspring. +The offspring, also, will thus have a better chance of surviving, for, +of the many individuals of any species which are periodically born, but +a small number can survive. I have called this principle, by which each +slight variation, if useful, is preserved, by the term Natural +Selection, in order to mark its relation to man's power of selection. +But the expression, often used by Mr. Herbert Spencer, of the Survival +of the Fittest, is more accurate.</p> + +<p>We have seen that man, by selection, can certainly produce great +results, and can adapt organic beings to his own uses, through the +accumulation of slight but useful variations given to him by the hand of +Nature. Natural Selection is a power incessantly ready for action, and +is as immeasurably superior to man's feeble efforts as the works of +Nature are to those of Art.</p> + +<p>All organic beings are exposed to severe competition. Nothing is easier +than to admit in words the truth of the universal struggle for life, or +more difficult—at least, I have found it so—than constantly to bear +this conclusion in mind. Yet, unless it be thoroughly engrained in the +mind, the whole economy of Nature, with every fact of distribution, +rarity, abundance, extinction, and variation, will be dimly seen or +quite misunderstood. We behold the face of Nature bright with gladness; +we often see superabundance of food. We do not see, or we forget, that +the birds which are idly singing round us mostly live on insects or +seeds, and are thus constantly destroying life; or we forget how largely +these songsters, or their eggs, or their nestlings, are destroyed by +birds or beasts of prey. We do not always bear in mind that, though food +may be superabundant, it is not so at all seasons of each recurring +year.</p> + +<p><span class='pagenum'><a name="Page_50" id="Page_50">[Pg 50]</a></span></p><p>A struggle for existence, the term being used in a large, general, and +metaphorical sense, inevitably follows from the high rate at which all +organic beings tend to increase.</p> + +<p>Every being, which during its natural lifetime produces several eggs or +seeds, must suffer destruction during some period of its life, and +during some season or occasional year; otherwise, on the principle of +geometrical increase, its numbers would quickly become so inordinately +great that no country could support the product. Hence, as more +individuals are produced than can possibly survive, there must in every +case be a struggle for existence, either one individual with another of +the same species, or with the individuals of distinct species, or with +the physical conditions of life. It is the doctrine of Malthus applied +with manifold force to the whole animal and vegetable kingdoms; for in +this case there can be no artificial increase of food, and no prudential +restraint from marriage. Although some species may be now increasing, +more or less rapidly, in numbers, all cannot do so, for the world would +not hold them.</p> + +<p>There is no exception to the rule that every organic being naturally +increases at so high a rate that, if not destroyed, the earth would soon +be covered by the progeny of a single pair. Even slow-breeding man has +doubled in twenty-five years, and at this rate, in less than a thousand +years, there would literally not be standing-room for his progeny. +Linnæus has calculated that if an annual plant produced only two +seeds—and there is no plant so unproductive as this—and their +seedlings next year produced two, and so on, then in twenty years there +would be a million plants. The elephant is reckoned the slowest breeder +of all known animals, and I have taken some pains to estimate its +probable minimum rate of natural increase. It will be safest to assume +that it begins breeding when thirty years old, and goes on<span class='pagenum'><a name="Page_51" id="Page_51">[Pg 51]</a></span> breeding +until ninety years old, bringing forth six young in the interval, and +surviving till one hundred years old. If this be so, after a period of +from 740 to 750 years there would be nearly nineteen million elephants +alive, descended from the first pair.</p> + +<p>The causes which check the natural tendency of each species to increase +are most obscure. Eggs or very young animals seem generally to suffer +most, but this is not invariably the case. With plants there is a vast +destruction of seeds. The amount of food for each species of course +gives the extreme limit to which each can increase; but very frequently +it is not the obtaining food, but the serving as prey to other animals, +which determines the average number of a species. Climate is important, +and periodical seasons of extreme cold or drought seem to be the most +effective of all checks.</p> + +<p>The relations of all animals and plants to each other in the struggle +for existence are most complex, and often unexpected. Battle within +battle must be continually recurring with varying success; and yet in +the long run the forces are so nicely balanced that the face of Nature +remains for long periods of time uniform, though assuredly the merest +trifle would give the victory to one organic being over another. +Nevertheless, so profound is our ignorance, and so high our presumption, +that we marvel when we hear of the extinction of an organic being; and +as we do not see the cause, we invoke cataclysms to desolate the world, +or invent laws on the duration of the forms of life!</p> + +<p>The struggle for life is most severe between individuals and varieties +of the same species. The competition is most severe between allied forms +which fill nearly the same place in the economy of Nature. But great is +our ignorance on the mutual relations of all organic beings. All that we +can do is to keep steadily in mind that each organic being is striving +to increase in a geometrical ratio; that each at some period of its +life, <span class='pagenum'><a name="Page_52" id="Page_52">[Pg 52]</a></span>during some season of the year, during each generation or at +intervals, has to struggle for life and to suffer great destruction. +When we reflect on this struggle, we may console ourselves with the full +belief that the war of Nature is not incessant, that no fear is felt, +that death is generally prompt, and that the vigorous, the healthy, and +the happy survive and multiply.</p> + + +<p class="subchap"><i>IV.—The Survival of the Fittest</i></p> + +<p>How will the struggle for existence act in regard to variation? Can the +principle of selection, which we have seen is so potent in the hands of +man, apply under Nature? I think we shall see that it can act most +efficiently. Let the endless number of slight variations and individual +differences occurring in our domestic productions, and, in a lesser +degree, in those under Nature, be borne in mind, as well as the strength +of the hereditary tendency. Under domestication, it may be truly said +that the whole organisation becomes in some degree plastic.</p> + +<p>But the variability, which we almost universally meet with in our +domestic productions, is not directly produced by man; he can neither +originate variations nor prevent their occurrence; he can only preserve +and accumulate such as do occur. Unintentionally he exposes organic +beings to new and changing conditions of life, and variability ensues; +but similar changes of condition might and do occur under Nature.</p> + +<p>Let it also be borne in mind how infinitely complex and close-fitting +are the mutual relations of all organic beings to each other and to +their physical conditions of life, and consequently what infinitely +varied diversities of structure might be of use to each being under +changing conditions of life. Can it, then, be thought improbable, seeing +what variations useful to man have undoubtedly occurred, that other +variations, useful in some way to each being in the great complex battle +of life, should<span class='pagenum'><a name="Page_53" id="Page_53">[Pg 53]</a></span> occur in the course of many successive generations? If +such do occur, can we doubt, remembering that many more individuals are +born than can possibly survive, that individuals having any advantage +over others, would have the best chance of surviving and of procreating +their kind? On the other hand, we may feel sure that any variation in +the least degree injurious would be rigidly destroyed. This preservation +of favourable individual differences and variations, and the destruction +of those which are injurious, I have called Natural Selection, or the +Survival of the Fittest.</p> + +<p>The term is too frequently misapprehended. Variations neither useful nor +injurious would not be affected by natural selection. It is not asserted +that natural selection induces variability. It implies only the +preservation of such varieties as arise and are beneficial to the being +under its conditions of life. Again, it has been said that I speak of +natural selection as an active Power or Deity; but who objects to an +author speaking of the attraction of gravity as ruling the movements of +the planets? It is difficult to avoid personifying the word Nature; but +I mean by Nature only the aggregate action and product of many natural +laws, and by laws the sequence of events as ascertained by us.</p> + +<p>As man can produce, and certainly has produced, a great result by his +methodical and unconscious means of selection, what may not natural +selection effect? Man can act only on external and visible characters; +Nature, if I may be allowed to personify the natural preservation or +survival of the fittest, cares nothing for appearances, except in so far +as they are useful to any being. She can act on every internal organ, on +every shade of constitutional difference, on the whole machinery of +life. Man selects only for his own good; Nature only for that of the +being which she tends. Every selected character is fully exercised by +her, as is implied by the fact of their selection. Man keeps the natives +of many climates<span class='pagenum'><a name="Page_54" id="Page_54">[Pg 54]</a></span> in the same country; he seldom exercises each selected +character in some peculiar and fitting manner; he feeds a long and a +short-beaked pigeon on the same food; he does not exercise a long-backed +or long-legged quadruped in any peculiar manner; he exposes sheep with +long and short wool to the same climate.</p> + +<p>Man does not allow the most vigorous males to struggle for the females. +He does not rigidly destroy all inferior animals, but protects during +each varying season, as far as lies in his power, all his productions. +He often begins his selection by some half-monstrous form; or at least +by some modification prominent enough to catch the eye or to be plainly +useful to him.</p> + +<p>But under Nature, the slightest differences of structure or constitution +may well turn the nicely-balanced scale in the struggle for life, and so +be preserved. How fleeting are the wishes and efforts of man! How short +his time! And, consequently, how poor will be his results compared with +those accumulated by Nature during whole geological periods! Can we +wonder that Nature's productions should be far "truer" in character than +man's productions; that they should be infinitely better adapted to the +most complex conditions of life, and should plainly bear the stamp of +far higher workmanship?</p> + +<p>It may metaphorically be said that natural selection is daily and hourly +scrutinising, throughout the world, the slightest variations; rejecting +those that are bad, preserving and adding up all that are good; silently +and insensibly working, whenever and wherever opportunity offers, at the +improvement of each organic being in relation to its organic and +inorganic conditions of life. We see nothing of these slow changes in +progress until the hand of time has marked the lapse of ages, and then +so imperfect is our view into long-past geological ages that we see only +that the forms of life are now different from what they formerly were.</p> + +<p><span class='pagenum'><a name="Page_55" id="Page_55">[Pg 55]</a></span></p><p>Although natural selection can act only through and for the good of +each being, yet characters and structures, which we are apt to consider +as of very trifling importance, may thus be acted on.</p> + +<p>Natural selection will modify the structure of the young in relation to +the parent, and of the parent in relation to the young. In social +animals it will adapt the structure of each individual for the benefit +of the whole community, if the community profits by the selected change. +What natural selection cannot do is to modify the structure of one +species, without giving it any advantage, for the good of another +species; and though statements to this effect may be found in works of +natural history, I cannot find one case which will bear investigation.</p> + +<p>A structure used only once in an animal's life, if of high importance to +it, might be modified to any extent by natural selection; for instance, +the great jaws possessed by certain insects, used exclusively for +opening the cocoon, or the hard tip to the beak of unhatched birds, used +for breaking the egg. It has been asserted that of the best short-beaked +tumbler pigeons a greater number perish in the egg than are able to get +out of it; so that fanciers assist in the act of hatching. Now, if +Nature had to make the beak of a full-grown pigeon very short for the +bird's own advantage, the process of modification would be very slow, +and there would be simultaneously the most rigorous selection of all the +young birds within the egg, for all with weak beaks would inevitably +perish; or more easily broken shells might be selected, the thickness of +the shell being known to vary like every other structure.</p> + +<p>With all beings there must be much fortuitous destruction, which can +have little or no influence on the course of natural selection. For +instance, a vast number of eggs or seeds are annually devoured, and +these could be modified through natural selection only if they varied<span class='pagenum'><a name="Page_56" id="Page_56">[Pg 56]</a></span> +in some manner which protected them from their enemies. Yet many of +these eggs or seeds would perhaps, if not destroyed, have yielded +individuals better adapted to their conditions of life than any of those +which happened to survive. So, again, a vast number of mature animals +and plants, whether or not they be the best adapted to their conditions, +must be annually destroyed by accidental causes, which would not be in +the least degree mitigated by certain changes of structure or +constitution which would in other ways be beneficial to the species.</p> + +<p>But let the destruction of the adults be ever so heavy, if the number +which can exist in any district be not wholly kept down by such +causes—or, again, let the destruction of eggs or seeds be so great that +only a hundredth or a thousandth part are developed—yet of those which +do survive, the best adapted individuals, supposing there is any +variability in a favourable direction, will tend to propagate their kind +in larger numbers than the less well adapted.</p> + +<p>On our theory the continued existence of lowly organisms offers no +difficulty; for natural selection does not necessarily include +progressive development; it only takes advantage of such variations as +arise and are beneficial to each creature under its complex relations of +life.</p> + +<p>The mere lapse of time by itself does nothing, either for or against +natural selection. I state this because it has been erroneously asserted +that the element of time has been assumed by me to play an all-important +part in modifying species, as if all the forms of life were necessarily +undergoing change through some innate law.</p> + + +<p class="subchap"><i>V.—Sexual Selection</i></p> + +<p>This form of selection depends, not on a struggle for existence in +relation to other organic beings or to external conditions, but on a +struggle between the individuals<span class='pagenum'><a name="Page_57" id="Page_57">[Pg 57]</a></span> of one sex, generally the males, for +the possession of the other sex. The result is not death to the +unsuccessful competitor, but few or no offspring. Sexual selection is, +therefore, less rigorous than natural selection. Generally, the most +vigorous males, those which are best fitted for their places in Nature, +will leave most progeny. But, in many cases, victory depends not so much +on general vigour as on having special weapons, confined to the male +sex. A hornless stag or spurless cock would have a poor chance of +leaving numerous offspring. Sexual selection, by always allowing the +victor to breed, might surely give indomitable courage, length to the +spur, and strength to the wing to strike in the spurred leg, in nearly +the same manner as does the brutal cock-fighter by the careful selection +of his best cocks.</p> + +<p>How low in the scale of Nature the law of battle descends I know not. +Male alligators have been described as fighting, bellowing, and whirling +round, like Indians in a war-dance, for the possession of the females; +male salmons have been observed fighting all day long; male stag-beetles +sometimes bear wounds from the mandibles of other males; the males of +certain other insects have been frequently seen fighting for a +particular female who sits by, an apparently unconcerned beholder of the +struggle, and then retires with the conqueror. The war is, perhaps, +severest between the males of the polygamous animals, and these seem +oftenest provided with special weapons. The males of carnivorous animals +are already well armed, though to them special means of defence may be +given through means of sexual selection, as the mane of the lion and the +hooked jaw of the salmon. The shield may be as important for victory as +the sword or spear.</p> + +<p>Amongst birds, the contest is often of a more peaceful character. All +those who have attended to the subject believe that there is the +severest rivalry between the males of many species to attract, by +singing, the<span class='pagenum'><a name="Page_58" id="Page_58">[Pg 58]</a></span> females. The rock-thrush of Guiana, birds of paradise, and +some others, congregate; and successive males display with the most +elaborate care, and show off in the best manner, their gorgeous plumage; +they likewise perform strange antics before the females, which, standing +by as spectators, at last choose the most attractive partner.</p> + +<p>If man can in a short time give beauty and an elegant carriage to his +bantams, according to his standard of beauty, I can see no good reason +to doubt that female birds, by selecting, during thousands of +generations, the most melodious or beautiful males, according to their +standard of beauty, might produce a marked effect.</p> + + +<p class="subchap"><i>VI.—The Struggle for Existence</i></p> + +<p>Under domestication we see much variability, caused, or at least +excited, by changed conditions of life; but often in so obscure a manner +that we are tempted to consider the variations as spontaneous. +Variability is governed by many complex laws—by correlated growth, +compensation, the increased use and disuse of parts, and the definite +action of the surrounding conditions. There is much difficulty in +ascertaining how largely our domestic productions have been modified; +but we may safely infer that the amount has been large, and that +modifications can be inherited for long periods. As long as the +conditions of life remain the same, we have reason to believe that a +modification, which has already been inherited for many generations, may +continue to be inherited for an almost infinite number of generations. +On the other hand, we have evidence that variability, when it has once +come into play, does not cease under domestication for a very long +period; nor do we know that it ever ceases, for new varieties are still +occasionally produced by our oldest domesticated productions.</p> + +<p>Variability is not actually caused by man; he only <span class='pagenum'><a name="Page_59" id="Page_59">[Pg 59]</a></span>unintentionally +exposes organic beings to new conditions of life, and then Nature acts +on the organisation and causes it to vary. But man can and does select +the variations given to him by Nature, and thus accumulates them in any +desired manner. He thus adapts animals and plants for his own benefit or +pleasure. He may do this methodically, or he may do it unconsciously by +preserving the individuals most useful or pleasing to him without an +intention of altering the breed.</p> + +<p>It is certain that he can influence the character of a breed by +selecting, in each successive generation, individual differences so +slight as to be inappreciable except by an educated eye. This +unconscious process of selection has been the agency in the formation of +the most distinct and useful domestic breeds. That many breeds produced +by man have to a large extent the character of natural species is shown +by the inextricable doubts whether many of them are varieties or +aboriginally distinct species.</p> + +<p>There is no reason why the principles which have acted so efficiently +under domestication should not have acted under Nature. In the survival +of favoured individuals and races, during the constantly recurrent +struggle for existence, we see a powerful and ever-acting form of +selection. The struggle for existence inevitably follows from the high +geometrical ratio of increase which is common to all organic beings. +This high rate of increase is proved by calculation; by the rapid +increase of many animals and plants during a succession of peculiar +seasons and when naturalised in new countries. More individuals are born +than can possibly survive. A grain in the balance may determine which +individuals shall live and which shall die; which variety or species +shall increase in number, and which shall decrease, or finally become +extinct.</p> + +<p>As the individuals of the same species come in all respects into the +closest competition with each other, the<span class='pagenum'><a name="Page_60" id="Page_60">[Pg 60]</a></span> struggle will generally be +most severe between them; it will be almost equally severe between the +varieties of the same species, and next in severity between the species +of the same genus. On the other hand, the struggle will often be severe +between beings remote in the scale of Nature. The slightest advantage in +certain individuals, at any age or during any season, over those with +which they come into competition, or better adaptation, in however +slight a degree, to the surrounding physical conditions, will, in the +long run, turn the balance.</p> + +<p>With animals having separated sexes, there will be in most cases a +struggle between the males for the possession of the females. The most +vigorous males, or those which have most successfully struggled with +their conditions of life, will generally leave most progeny. But success +will often depend on the males having special weapons, or means of +defence, or charms; and a slight advantage will lead to victory.</p> + +<p>As geology plainly proclaims that each land has undergone great physical +changes, we might have expected to find that organic beings have varied +under Nature in the same way as they have varied under domestication. +And if there has been any variability under Nature, it would be an +unaccountable fact if natural selection had not come into play. It has +often been asserted, but the assertion is incapable of proof, that the +amount of variation under Nature is a strictly limited quantity. Man, +though acting on external characters alone, and often capriciously, can +produce within a short period a great result by adding up mere +individual differences in his domestic productions; and everyone admits +that species present individual differences. But, besides such +differences, all naturalists admit that natural varieties exist, which +are considered sufficiently distinct to be worthy of record in +systematic works.</p> + +<p>No one has drawn any clear distinction between <span class='pagenum'><a name="Page_61" id="Page_61">[Pg 61]</a></span>individual differences +and slight varieties, or between more plainly marked varieties and +sub-species and species. On separate continents, and on different parts +of the same continent when divided by barriers of any kind, what a +multitude of forms exist which some experienced naturalists rank as +varieties, others as geographical races or sub-species, and others as +distinct, though closely allied species!</p> + +<p>If, then, animals and plants do vary, let it be ever so slightly or +slowly, why should not variations or individuals, differences which are +in any way beneficial, be preserved and accumulated through natural +selection, or the survival of the fittest? If man can, by patience, +select variations useful to him, why, under changing and complex +conditions of life, should not variations useful to Nature's living +products often arise, and be preserved, or selected? What limit can be +put to this power, acting during long ages and rigidly scrutinising the +whole constitution, structure, and habits of each creature—favouring +the good and rejecting the bad? I can see no limit to this power, in +slowly and beautifully adapting each form to the most complex relations +of life.</p> + +<p>In the future I see open fields for far more important researches. +Psychology will be based on the foundation already well laid by Mr. +Herbert Spencer—that of the necessary acquirement of each mental power +and capacity by gradation. Much light will be thrown on the origin of +man and his history.</p> + +<p>Authors of the highest eminence seem to be fully satisfied with the view +that each species has been independently created. To my mind it accords +better with what we know of the laws impressed on matter by the Creator +that the production and extinction of the past and present inhabitants +of the world should have been due to secondary causes, like those +determining the birth and death of the individual. When I view all +beings not as special creations, but as the lineal descendants of<span class='pagenum'><a name="Page_62" id="Page_62">[Pg 62]</a></span> some +few beings which lived long before the first bed of the Cambrian system +was deposited, they seem to me to become ennobled. Judging from the +past, we may safely infer that not one living species will transmit its +unaltered likeness to a distant futurity.</p> + +<p>Of the species now living very few will transmit progeny of any kind to +a far distant futurity; for the manner in which all organic beings are +grouped shows that the greater number of species in each genus, and all +the species in many genera, have left no descendants, but have become +utterly extinct. We can so far take a prophetic glance into futurity as +to foretell that it will be the common and widely-spread species, +belonging to the larger and dominant groups within each class, which +will ultimately prevail and procreate new and dominant species. As all +the living forms of life are the lineal descendants of those which lived +long before the Cambrian epoch, we may feel certain that the ordinary +succession by generation has never once been broken, and that no +cataclysm has desolated the whole world. We may look with some +confidence to a secure future of great length. As natural selection +works solely by and for the good of each being, all corporeal and mental +endowments will tend to progress towards perfection.</p> + +<p>It is interesting to contemplate a tangled bank, clothed with many +plants of many kinds, with birds singing on the bushes, with various +insects flitting about, and with worms crawling through the damp earth, +and to reflect that these elaborately constructed forms, so different +from each other, and dependent upon each other in so complex a manner, +have all been produced by laws acting around us. These laws, taken in +the largest sense, being Growth with Reproduction; Inheritance, which is +almost implied by reproduction; Variability from the indirect and direct +action of the conditions of life, and from use and disuse; a ratio of +increase so high as to lead to a struggle for life, and, as a +consequence, to Natural<span class='pagenum'><a name="Page_63" id="Page_63">[Pg 63]</a></span> Selection, entailing Divergence of Character +and the Extinction of less improved forms. Thus, from the war of Nature, +from famine and death, the most exalted object which we are capable of +conceiving, namely, the production of the higher animals, directly +follows. There is grandeur in this view of life, with its several +powers, having been originally breathed by the Creator into a few forms, +or into one; and that, whilst this planet has gone cycling on according +to the fixed law of gravity, from so simple a beginning endless forms +most beautiful and most wonderful have been, and are being, evolved.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_64" id="Page_64">[Pg 64]</a></span></p> +<h3>SIR HUMPHRY DAVY</h3> + +<p class="book"><big><a name="Elements_of_Chemical_Philosophy" id="Elements_of_Chemical_Philosophy"></a>Elements of Chemical Philosophy</big></p> + +<div class="blockquot"><p>Humphry Davy, the celebrated natural philosopher, was born Dec. 17, +1778, at Penzance, England. At the age of seventeen he became an +apothecary's apprentice, and at the age of nineteen assistant at +Dr. Beddoes's pneumatic institution at Bristol. During researches +at the pneumatic institution he discovered the physiological +effects of "laughing gas," and made so considerable a reputation as +a chemist that at the age of twenty-two he was appointed lecturer, +and a year later professor, at the Royal Institution. For ten +years, from 1803, he was engaged in agricultural researches, and in +1813 published his "Elements of Agricultural Chemistry." During the +same decade he conducted important investigations into the nature +of chemical combination, and succeeded in isolating the elements +potassium, sodium, strontium, magnesium, and chlorine. In 1812 he +was knighted, and married Mrs. Apreece, <i>née</i> Jane Kerr. In 1815 he +investigated the nature of fire-damp and invented the Davy safety +lamp. In 1818 he received a baronetcy, and two years later was +elected President of the Royal Society. On May 29, 1829, he died at +Geneva. Davy's "Elements of Chemical Philosophy," of which a +summary is given here, was published in one volume in 1812, being +the substance of lectures delivered before the Board of +Agriculture.</p></div> + + +<p class="subchap"><i>I.—Forms and Changes of Matter</i></p> + +<p><span class="smcap">The</span> forms and appearances of the beings and substances of the external +world are almost infinitely various, and they are in a state of +continued alteration. In general, matter is found in four forms, as (1) +solids, (2) fluids, (3) gases, (4) ethereal substances.</p> + +<p>1. <i>Solids.</i> Solids retain whatever mechanical form is given to them; +their parts are separated with difficulty, and cannot readily be made to +unite after separation. They may be either elastic or non-elastic, and +differ in hardness, in colour, in opacity, in density, in weight, and, +if crystalline, in crystalline form.</p> + +<p><span class='pagenum'><a name="Page_65" id="Page_65">[Pg 65]</a></span></p><p>2. <i>Fluids.</i> Fluids, when in small masses, assume the spherical form; +their parts possess freedom of motion; they differ in density and +tenacity, in colour, and in opacity. They are usually regarded as +incompressible; at least, a very great mechanical force is required to +compress them.</p> + +<p>3. <i>Gases.</i> Gases exist free in the atmosphere, but may be confined. +Their parts are highly movable; they are compressible and expansible, +and their volumes are inversely as the weight compressing them. All +known gases are transparent, and present only two or three varieties of +colour; they differ materially in density.</p> + +<p>4. <i>Ethereal Substances.</i> Ethereal substances are known to us only in +their states of motion when acting upon our organs of sense, or upon +other matter, and are not susceptible of being confined. It cannot be +doubted that there is such matter in motion in space. Ethereal matter +differs either in its nature, or in its affections by motion, for it +produces different effects; for instance, radiant heat, and different +kinds of light.</p> + +<p>All these forms of matter are under the influence of active forces, such +as gravitation, cohesion, heat, chemical and electrical attraction, and +these we must now consider.</p> + +<p>1. <i>Gravitation.</i> When a stone is thrown into the atmosphere, it rapidly +descends towards the earth. This is owing to gravitation. All the great +bodies in the universe are urged towards each other by a similar force. +Bodies mutually gravitate towards each other, but the smaller body +proportionately more than the larger one; hence the power of gravity is +said to vary directly as the mass. Gravitation also varies with +distance, and acts inversely as the square of the distance.</p> + +<p>2. <i>Cohesion.</i> Cohesion is the force which preserves the forms of +solids, and gives globularity to fluids. It is usually said to act only +at the surface of bodies or by their immediate contact; but this does +not seem to be the<span class='pagenum'><a name="Page_66" id="Page_66">[Pg 66]</a></span> case. It certainly acts with much greater energy at +small distances, but the spherical form of minute portions of fluid +matter can be produced only by the attractions of all the parts of which +they are composed, for each other; and most of these attractions must be +exerted at sensible distances, so that gravitation and cohesion may be +mere modifications of the same general power of attraction.</p> + +<p>3. <i>Heat.</i> When a body which occasions the sensation of heat on our +organs is brought into contact with another body which has no such +effect, the hot body contracts and loses to a certain extent its power +of communicating heat; and the other body expands. Different solids and +fluids expand very differently when heated, and the expansive power of +liquids, in general, is greater than that of solids.</p> + +<p>It is evident that the density of bodies must be diminished by +expansion; and in the case of fluids and gases, the parts of which are +mobile, many important phenomena depend upon this circumstance. For +instance, if heat be applied to fluids and gases, the heated parts +change their places and rise, and the currents in the ocean and +atmosphere are due principally to this movement. There are very few +exceptions to the law of the expansion of bodies at the time they become +capable of communicating the sensation of heat, and these exceptions +seem to depend upon some chemical change in the constitution of bodies, +or on their crystalline arrangements.</p> + +<p>The power which bodies possess of communicating or receiving heat is +known as <i>temperature</i>, and the temparature of a body is said to be high +or low with respect to another in proportion as it occasions an +expansion or contraction of its parts.</p> + +<p>When equal volumes of different bodies of different temperatures are +suffered to remain in contact till they acquire the same temperature, it +is found that this temperature is not a mean one, as it would be in the +case of<span class='pagenum'><a name="Page_67" id="Page_67">[Pg 67]</a></span> equal volumes of the same body. Thus if a pint of quicksilver +at 100° be mixed with a pint of water at 50°, the resulting temperature +is not 75°, but 70°; the mercury has lost thirty degrees, whereas the +water has only gained twenty degrees. This difference is said to depend +on the different <i>capacities</i> of bodies for heat.</p> + +<p>Not only do different bodies vary in their capacity for heat, but they +likewise acquire heat with very different degrees of celerity. This last +difference depends on the different power of bodies for <i>conducting</i> +heat, and it will be found that as a rule the densest bodies, with the +least capacity for heat, are the best conductors.</p> + +<p>Heat, or the power of repulsion, may be considered as the <i>antagonist</i> +power to the attraction of cohesion. Thus solids by a certain increase +of temperature become fluids, and fluids gases; and, <i>vice versâ</i>, by a +diminution of temperature, gases become fluids, and fluids solids.</p> + +<p>Proofs of the conversion of solids, fluids, or gases into ethereal +substances are not distinct. Heated bodies become luminous and give off +radiant heat, which affects the bodies at a distance, and it may +therefore be held that particles are thrown off from heated bodies with +great velocity, which, by acting on our organs, produce the sensations +of heat or light, and that their motion, communicated to the particles +of other bodies, has the power of expanding them. It may, however, be +said that the radiant matters emitted by bodies in ignition are specific +substances, and that common matter is not susceptible of assuming this +form; or it may be contended that the phenomena of radiation do in fact, +depend upon motions communicated to subtile matter everywhere existing +in space.</p> + +<p>The temperatures at which bodies change their states from fluids to +solids, though in general definite, are influenced by a few +circumstances such as motion and pressure.</p> + +<p>When solids are converted into fluids, or fluids into<span class='pagenum'><a name="Page_68" id="Page_68">[Pg 68]</a></span> gases, there is +always a loss of heat of temperature; and, <i>vice versâ</i>, when gases are +converted into fluids, or fluids into solids, there is an increase of +heat of temperature, and in this case it is said that <i>latent</i> heat is +absorbed or given out.</p> + +<p>The expansion due to heat has been accounted for by supposing a subtile +fluid, or <i>caloric</i>, capable of combining with bodies and of separating +their parts from each other, and the absorption and liberation of latent +heat can be explained on this principle. But many other facts are +incompatible with the theory. For instance, metal may be kept hot for +any length of time by friction, so that if <i>caloric</i> be pressed out it +must exist in an inexhaustible quantity. Delicate experiments have shown +that bodies, when heated, do not increase in weight.</p> + +<p>It seems possible to account for all the phenomena of heat, if it be +supposed that in solids the particles are in a constant state of +vibratory motion, the particles of the hottest bodies moving with the +greatest velocity and through the greatest space; that in fluids and +gases the particles have not only vibratory motion, but also a motion +round their own axes with different velocities, and that in ethereal +substances the particles move round their own axes and separate from +each other, penetrating in right lines through space. Temperature may be +conceived to depend upon the velocity of the vibrations, increase of +capacity on the motion being performed in greater space; and the +diminution of temperature during the conversion of solids into fluids or +gases may be explained on the idea of the loss of vibratory motion in +consequence of the revolution of particles round their axes at the +moment when the body becomes fluid or aeriform, or from the loss of +rapidity of vibration in consequence of the motion of particles through +greater space.</p> + +<p>4. <i>Chemical Attraction.</i> Oil and water will not <i>combine</i>; they are +said to have no chemical <i>attraction</i> or <i>affinity</i> for each other. But +if oil and solution of potassa<span class='pagenum'><a name="Page_69" id="Page_69">[Pg 69]</a></span> in water be mixed, the oil and the +solution blend and form a soap; and they are said to attract each other +chemically or to have a <i>chemical affinity</i> for each other. It is a +general character of chemical combination that it changes the qualities +of the bodies. Thus, corrosive and pungent substances may become mild +and tasteless; solids may become fluids, and solids and fluids gases.</p> + +<p>No body will act chemically upon another body at any sensible distance; +apparent contact is necessary for chemical action. A freedom of motion +in the parts of the bodies or a want of cohesion greatly assists action, +and it was formerly believed that bodies cannot act chemically upon each +other unless one of them be fluid or gaseous.</p> + +<p>Different bodies unite with different degrees of force, and hence one +body is capable of separating others from certain of their combinations, +and in consequence mutual decompositions of different compounds take +place. This has been called <i>double affinity</i>, or <i>complex chemical +affinity</i>.</p> + +<p>As in all well-known compounds the proportions of the elements are in +certain definite ratios to each other, it is evident that these ratios +may be expressed by numbers; and if one number be employed to denote the +smallest quantity in which a body combines, all other quantities of the +same body will be multiples of this number, and the smallest proportions +into which the undecomposed bodies enter into union being known, the +constitution of the compounds they form may be learnt, and the element +which unites chemically in the smallest quantity being expressed by +unity, all the other elements may be represented by the relations of +their quantities to unity.</p> + +<p>5. <i>Electrical Attraction.</i> A piece of dry silk briskly rubbed against a +warm plate of polished flint glass acquires the property of adhering to +the glass, and both the silk and the glass, if apart from each other, +attract light substances. The bodies are said to be <i>electrically<span class='pagenum'><a name="Page_70" id="Page_70">[Pg 70]</a></span> +excited</i>. Probably, all bodies which differ from each other become +electrically excited when rubbed and pressed together. The electrical +excitement seems of two kinds. A pith-ball touched by glass excited by +silk repels a pith-ball touched by silk excited by metals. Electrical +excitement of the same nature as that in glass excited by silk is known +as <i>vitreous</i> or <i>positive</i>, and electrical excitement of the opposite +nature is known as <i>resinous</i> or <i>negative</i>.</p> + +<p>A rod of glass touched by an electrified body is electrified only round +the point of contact. A rod of metal, on the contrary, suspended on a +rod of glass and brought into contact with an electrical surface, +instantly becomes electrical throughout. The glass is said to be a +<i>non-conductor</i>, or <i>insulating substance</i>; the metal a <i>conductor</i>.</p> + +<p>When a non-conductor or imperfect conductor, provided it be a thin plate +of matter placed upon a conductor, is brought in contact with an excited +electrical body, the surface opposite to that of contact gains the +opposite electricity from that of the excited body, and if the plate be +removed it is found to possess two surfaces in opposite states. If a +conductor be brought into the neighbourhood of an excited body—the air, +which is a non-conductor, being between them—that extremity of the +conductor which is opposite to the excited body gains the opposite +electricity; and the other extremity, if opposite to a body connected +with the ground, gains the same electricity, and the middle point is not +electrical at all. This is known as <i>induced</i> electricity.</p> + +<p>The common exhibition of electrical effects is in attractions and +repulsions; but electricity also produces chemical phenomena. If a piece +of zinc and copper in contact with each other at one point be placed in +contact at other points with the same portion of water, the zinc will +corrode, and attract oxygen from the water much more rapidly than if it +had not been in contact with the copper; and if sulphuric acid be added, +globules of <span class='pagenum'><a name="Page_71" id="Page_71">[Pg 71]</a></span>inflammable air are given off from the copper, though it is +not dissolved or acted upon.</p> + +<p>Chemical phenomena in connection with electrical effects can be shown +even better by combinations in which the electrical effects are +increased by alterations of different metals and fluids—the so-called +<i>voltaic batteries</i>. Such are the decomposing powers of such batteries +that not even insoluble compounds are capable of resisting their energy, +for even glass, sulphate of baryta, fluorspar, etc., are slowly acted +upon, and the alkaline, earthy, or acid matter carried to the poles in +the common order.</p> + +<p>The most powerful voltaic combinations are formed by substances that act +chemically with most energy upon each other, and such substances as +undergo no chemical changes in the combination exhibit no electrical +powers. Hence it was supposed that the electrical powers of metals were +entirely due to chemical changes; but this is not the case, for contact +produces electricity even when no chemical change can be observed.</p> + + +<p class="subchap"><i>II.—Radiant or Ethereal Matter</i></p> + +<p>When similar thermometers are placed in different parts of the solar +beam, it is found that different effects are produced in the differently +coloured rays. The greatest heat is exhibited in the red rays, the least +in the violet rays; and in a space beyond the red rays, where there is +no visible light, the increase of temperature is greatest of all.</p> + +<p>From these facts it is evident that matter set in motion by the sun has +the power of producing heat without light, and that its rays are less +refrangible than the visible rays. The invisible rays that produce heat +are capable of reflection as well as refraction in the same manner as +the visible rays.</p> + +<p>Rays capable of producing heat with and without light<span class='pagenum'><a name="Page_72" id="Page_72">[Pg 72]</a></span> proceed not only +from the sun, but also from bodies at the surface of the globe under +peculiar agencies or changes. If, for instance, a thermometer be held +near an ignited body, it receives an impression connected with an +elevation of temperature; this is partly produced by the conducting +powers of the air, and partly by an impulse which is instantaneously +communicated, even to a considerable distance. This effect is called the +radiation of terrestrial heat.</p> + +<p>The manner in which the temperatures of bodies are affected by rays +producing heat is different for different substances, and is very much +connected with their colours. The bodies that absorb most light, and +reflect least, are most heated when exposed either to solar or +terrestrial rays. Black bodies are, in general, more heated than red; +red more than green; green more than yellow; and yellow more than white. +Metals are less heated than earthy or stony bodies, or than animal or +vegetable matters. Polished surfaces are less heated than rough +surfaces.</p> + +<p>The bodies that have their temperatures most easily raised by heat rays +are likewise those that are most easily cooled by their own radiation, +or that at the same temperature emit most heat-making rays. Metals +radiate less heat than glass, glass less than vegetable substances, and +charcoal has the highest radiating powers of any body as yet made the +subject of experiment.</p> + +<p>Radiant matter has the power of producing chemical changes partly +through its heating power, and partly through some other specific and +peculiar influence. Thus chlorine and hydrogen detonate when a mixture +of them is exposed to the solar beams, even though the heat is +inadequate to produce detonation.</p> + +<p>If moistened silver be exposed to the different rays of the solar +spectrum, it will be found that no effect is produced upon it by the +least refrangible rays which occasion heat without light; that a slight +discoloration only<span class='pagenum'><a name="Page_73" id="Page_73">[Pg 73]</a></span> will be produced by the red rays; that the effect of +blackening will be greater towards the violet end of the spectrum; and +that in a space beyond the violet, where there is no sensible heat or +light, the chemical effect will be very distinct. There seem to be rays, +therefore, more refrangible than the rays producing light and heat.</p> + +<p>The general facts of the refraction and effects of the solar beam offer +an analogy to the agencies of electricity.</p> + +<p>In general, in Nature the effects of the solar rays are very compounded. +Healthy vegetation depends upon the presence of the solar beams or of +light, and while the heat gives fluidity and mobility to the vegetable +juices, chemical effects are likewise occasioned, oxygen is separated +from them, and inflammable compounds are formed. Plants deprived of +light become white and contain an excess of saccharine and aqueous +particles; and flowers owe the variety of their hues to the influence of +the solar beams. Even animals require the presence of the rays of the +sun, and their colours seem to depend upon the chemical influence of +these rays.</p> + +<p>Two hypotheses have been invented to account for the principal +operations of radiant matter. In the first it is supposed that the +universe contains a highly rare elastic substance, which, when put into +a state of undulation, produces those effects on our organs of sight +which constitute the sensations of vision and other phenomena caused by +solar and terrestrial rays. In the second it is conceived that particles +are emitted from luminous or heat-making bodies with great velocity, and +that they produce their effects by communicating their motions to +substances, or by entering into them and changing their composition.</p> + +<p>Newton has attempted to explain the different refrangibility of the rays +of light by supposing them composed of particles differing in size. The +same great man has put the query whether light and common matter are not +convertible into each other; and, adopting the idea<span class='pagenum'><a name="Page_74" id="Page_74">[Pg 74]</a></span> that the phenomena +of sensible heat depend upon vibrations of the particles of bodies, +supposes that a certain intensity of vibrations may send off particles +into free space, and that particles in rapid motion in right lines, in +losing their own motion, may communicate a vibratory motion to the +particles of terrestrial bodies.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_75" id="Page_75">[Pg 75]</a></span></p> +<h3>MICHAEL FARADAY</h3> + +<p class="book"><big><a name="Experimental_Researches_in_Electricity" id="Experimental_Researches_in_Electricity"></a>Experimental Researches in Electricity</big></p> + +<div class="blockquot"><p>Michael Faraday was the son of a Yorkshire blacksmith, and was born +in London on September 22, 1791. At the age of twenty he became +assistant to Sir Humphry Davy, whose lectures he had attended at +the Royal Institution. Here he worked for the rest of his laborious +life, which closed on August 25, 1867. The fame of Faraday, among +those whose studies qualify them for a verdict, has risen steadily +since his death, great though it then was. His researches were of +truly epoch-making character, and he was the undisputed founder of +the modern science of electricity, which is rapidly coming to +dominate chemistry itself. Faraday excelled as a lecturer, and +could stand even the supreme test of lecturing to children. +Faraday's "Experimental Researches in Electricity" is a record of +some of the most brilliant experiments in the history of science. +In the course of his investigations he made discoveries which have +had momentous consequences. His discovery of the mutual relation of +magnets and of wires conducting electric currents was the beginning +of the modern dynamo and all that it involves; while his +discoveries of electric induction and of electrolysis were of equal +significance. Most of the researches are too technical for +epitomisation; but those given are representative of his manner and +methods.</p></div> + + +<p class="subchap"><i>I.—Atmospheric Magnetism</i></p> + +<p><span class="smcap">It</span> is to me an impossible thing to perceive that two-ninths of the +atmosphere by weight is a highly magnetic body, subject to great changes +in its magnetic character, by variations in its temperature and +condensation or rarefaction, without being persuaded that it has much to +do with the variable disposition of the magnetic forces upon the surface +of the earth.</p> + +<p>The earth is a spheroidal body consisting of paramagnetic and +diamagnetic substances irregularly disposed and intermingled; but for +the present the whole may be<span class='pagenum'><a name="Page_76" id="Page_76">[Pg 76]</a></span> considered a mighty compound magnet. The +magnetic force of this great magnet is known to us only on the surface +of the earth and water of our planet, and the variations in the magnetic +lines of force which pass in or across this surface can be measured by +their action on small standard magnets; but these variations are limited +in their information, and do not tell us whether the cause is in the air +above or the earth beneath.</p> + +<p>The lines of force issue from the earth in the northern and southern +parts and coalesce with each other over the equatorial, as would be the +case in a globe having one or two short magnets adjusted in relation to +its axis, and it is probable that the lines of force in their circuitous +course may extend through space to tens of thousands of miles. The lines +proceed through space with a certain degree of facility, but there may +be variations in space, <i>e.g.</i>, variations in its temperature which +affect its power of transmitting the magnetic influence.</p> + +<p>Between the earth and space, however, is interposed the atmosphere, and +at the bottom of the atmosphere we live. The atmosphere consists of four +volumes of nitrogen and one of oxygen uniformly mixed and acting +magnetically as a single medium. The <i>nitrogen</i> of the air is, as +regards the magnetic force, neither paramagnetic nor diamagnetic, +whether dense or rare, or at high or low temperatures.</p> + +<p>The <i>oxygen</i> of the air, on the other hand, is highly paramagnetic, +being, bulk for bulk, equivalent to a solution of protosulphate of iron, +containing of the crystallised salt seventeen times the weight of the +oxygen. It becomes less paramagnetic, volume for volume, as it is +rarefied, and apparently in the simple proportion of its rarefaction, +the temperature remaining the same. When its temperature is raised—the +expansion consequent thereon being permitted—it loses very greatly its +paramagnetic force, and there is sufficient reason to conclude that when +its temperature is lowered its paramagnetic<span class='pagenum'><a name="Page_77" id="Page_77">[Pg 77]</a></span> condition is exalted. These +characters oxygen preserves even when mingled with the nitrogen in the +air.</p> + +<p>Hence the atmosphere is a highly magnetic medium, and this medium is +changed in its magnetic relations by every change in its density and +temperature, and must affect both the intensity and direction of the +magnetic force emanating from the earth, and may account for the +variations which we find in terrestrial magnetic power.</p> + +<p>We may expect as the sun leaves us on the west some magnetic effect +correspondent to that of the approach of a body of cold air from the +east. Again, the innumerable circumstances that break up more or less +any average arrangement of the air temperatures may be expected to give +not merely differences in the regularity, direction, and degree of +magnetic variation, but, because of vicinity, differences so large as to +be many times greater than the mean difference for a given short period, +and they may also cause irregularities in the times of their occurrence. +Yet again, the atmosphere diminishes in density upwards, and this +diminution will affect the transmission of the electric force.</p> + +<p>The result of the <i>annual variation</i> that may be expected from the +magnetic constitution and condition of the atmosphere seems to me to be +of the following kind.</p> + +<p>Since the axis of the earth's rotation is inclined 23° 28' to the plane +of the ecliptic, the two hemispheres will become alternately warmer and +cooler than each other. The air of the cooled hemisphere will conduct +magnetic influence more freely than if in the mean state, and the lines +of force passing through it will increase in amount, whilst in the other +hemisphere the warmed air will conduct with less readiness than before, +and the intensity will diminish. In addition to this effect of +temperature, there ought to be another due to the increase of the +ponderable portion of the air in the cooled hemisphere, consequent on +its contraction and the coincident expansion of the air in the warmer +half, both of which <span class='pagenum'><a name="Page_78" id="Page_78">[Pg 78]</a></span>circumstances tend to increase the variation in +power of the two hemispheres from the normal state. Then, as the earth +rolls on its annual journey, that which was at one time the cooler +becomes the warmer hemisphere, and in its turn sinks as far below the +average magnetic intensity as it before had stood above it, while the +other hemisphere changes its magnetic condition from less to more +intense.</p> + + +<p class="subchap"><i>II.—Electro-Chemical Action</i></p> + +<p>The theory of definite electrolytical or electro-chemical action appears +to me to touch immediately upon the absolute quantity of electricity +belonging to different bodies. As soon as we perceive that chemical +powers are definite for each body, and that the electricity which we can +loosen from each body has definite chemical action which can be +measured, we seem to have found the link which connects the proportion +of that we have evolved to the proportion belonging to the particles in +their natural state.</p> + +<p>Now, it is wonderful to observe how small a quantity of a compound body +is decomposed by a certain quantity of electricity. One grain of water, +for instance, acidulated to facilitate conduction, will require an +electric current to be continued for three minutes and three-quarters to +effect its decomposition, and the current must be powerful enough to +keep a platina wire <span class="above">1</span>⁄<span class="below">104</span> inch in thickness red hot in the air during +the whole time, and to produce a very brilliant and constant star of +light if interrupted anywhere by charcoal points. It will not be too +much to say that this necessary quantity of electricity is equal to a +very powerful flash of lightning; and yet when it has performed its full +work of electrolysis, it has separated the elements of only a single +grain of water.</p> + +<p>On the other hand, the relation between the conduction<span class='pagenum'><a name="Page_79" id="Page_79">[Pg 79]</a></span> of the +electricity and the decomposition of the water is so close that one +cannot take place without the other. If the water be altered only in +that degree which consists in its having the solid instead of the fluid +state, the conduction is stopped and the decomposition is stopped with +it. Whether the conduction be considered as depending upon the +decomposition or not, still the relation of the two functions is equally +intimate.</p> + +<p>Considering this close and twofold relation—namely, that without +decomposition transmission of electricity does not occur, and that for a +given definite quantity of electricity passed an equally definite and +constant quantity of water or other matter is decomposed; considering +also that the agent, which is electricity, is simply employed in +overcoming electrical powers in the body subjected to its action, it +seems a probable and almost a natural consequence that the quantity +which passes is the equivalent of that of the particles separated; +<i>i.e.</i>, that if the electrical power which holds the elements of a grain +of water in combination, or which makes a grain of oxygen and hydrogen +in the right proportions unite into water when they are made to combine, +could be thrown into a current, it would exactly equal the current +required for the separation of that grain of water into its elements +again; in other words, that the electricity which decomposes and that +which is evolved by the decomposition of a certain quantity of matter +are alike.</p> + +<p>This view of the subject gives an almost overwhelming idea of the +extraordinary quantity or degree of electric power which naturally +belongs to the particles of matter, and the idea may be illustrated by +reference to the voltaic pile.</p> + +<p>The source of the electricity in the voltaic instrument is due almost +entirely to chemical action. Substances interposed between its metals +are all electrolytes, and the current cannot be transmitted without +their decomposition. If, now, a voltaic trough have its extremities<span class='pagenum'><a name="Page_80" id="Page_80">[Pg 80]</a></span> +connected by a body capable of being decomposed, such as water, we shall +have a continuous current through the apparatus, and we may regard the +part where the acid is acting on the plates and the part where the +current is acting upon the water as the reciprocals of each other. In +both parts we have the two conditions, <i>inseparable in such bodies as +these</i>: the passing of a current, and decomposition. In the one case we +have decomposition associated with a current; in the other, a current +followed by decomposition.</p> + +<p>Let us apply this in support of my surmise respecting the enormous +electric power of each particle or atom of matter.</p> + +<p>Two wires, one of platina, and one of zinc, each one-eighteenth of an +inch in diameter, placed five-sixteenths of an inch apart, and immersed +to the depth of five-eighths of an inch in acid, consisting of one drop +of oil of vitriol and four ounces of distilled water at a temperature of +about 60° Fahrenheit, and connected at the other ends by a copper wire +eighteen feet long, and one-eighteenth of an inch in thickness, yielded +as much electricity in little more than three seconds of time as a +Leyden battery charged by thirty turns of a very large and powerful +plate electric machine in full action. This quantity, although +sufficient if passed at once through the head of a rat or cat to have +killed it, as by a flash of lightning, was evolved by the mutual action +of so small a portion of the zinc wire and water in contact with it that +the loss of weight by either would be inappreciable; and as to the water +which could be decomposed by that current, it must have been insensible +in quantity, for no trace of hydrogen appeared upon the surface of the +platina during these three seconds. It would appear that 800,000 such +charges of the Leyden battery would be necessary to decompose a single +grain of water; or, if I am right, to equal the quantity of electricity +which is naturally associated with the elements<span class='pagenum'><a name="Page_81" id="Page_81">[Pg 81]</a></span> of that grain of water, +endowing them with their mutual chemical affinity.</p> + +<p>This theory of the definite evolution and the equivalent definite action +of electricity beautifully harmonises the associated theories of +definite proportions and electro-chemical affinity.</p> + +<p>According to it, the equivalent weights of bodies are simply those +quantities of them which contain equal quantities of electricity, or +have naturally equal electric powers, it being the electricity which +<i>determines</i> the equivalent number, <i>because</i> it determines the +combining force. Or, if we adopt the atomic theory or phraseology, then +the atoms of bodies which are equivalent to each other in their ordinary +chemical action have equal quantities of electricity naturally +associated with them. I cannot refrain from recalling here the beautiful +idea put forth, I believe, by Berzelius in his development of his views +of the electro-chemical theory of affinity, that the heat and light +evolved during cases of powerful combination are the consequence of the +electric discharge which is at the moment taking place. The idea is in +perfect accordance with the view I have taken of the quantity of +electricity associated with the particles of matter.</p> + +<p>The definite production of electricity in association with its definite +action proves, I think, that the current of electricity in the voltaic +pile is sustained by chemical decomposition, or, rather, by chemical +action, and not by contact only. But here, as elsewhere, I beg to +reserve my opinion as to the real action of contact.</p> + +<p>Admitting, however, that chemical action is the source of electricity, +what an infinitely small fraction of that which is active do we obtain +and employ in our voltaic batteries! Zinc and platina wires +one-eighteenth of an inch in diameter and about half an inch long, +dipped into dilute sulphuric acid, so weak that it is not sensibly sour +to the tongue, or scarcely sensitive to our most<span class='pagenum'><a name="Page_82" id="Page_82">[Pg 82]</a></span> delicate test papers, +will evolve more electricity in one-twentieth of a minute than any man +would willingly allow to pass through his body at once.</p> + +<p>The chemical energy represented by the satisfaction of the chemical +affinities of a grain of water and four grains of zinc can evolve +electricity equal in quantity to that of a powerful thunderstorm. Nor is +it merely true that the quantity is active; it can be directed—made to +perform its full equivalent duty. Is there not, then, great reason to +believe that, by a closer investigation of the development and action of +this subtile agent, we shall be able to increase the power of our +batteries, or to invent new instruments which shall a thousandfold +surpass in energy those we at present possess?</p> + + +<p class="subchap"><i>III.—The Gymnotus, or Electric Eel</i></p> + +<p>Wonderful as are the laws and phenomena of electricity when made evident +to us in inorganic or dead matter, their interest can bear scarcely any +comparison with that which attaches to the same force when connected +with the nervous system and with life.</p> + +<p>The existence of animals able to give the same concussion to the living +system as the electrical machine, the voltaic battery, and the +thunderstorm being made known to us by various naturalists, it became +important to identify their electricity with the electricity produced by +man from dead matter. In the case of the <i>Torpedo</i> [a fish belonging to +the family of Electric Rings] this identity has been fully proved, but +in the case of the <i>Gymnotus</i> the proof has not been quite complete, and +I thought it well to obtain a specimen of the latter fish.</p> + +<p>A gymnotus being obtained, I conducted a series of experiments. Besides +the hands two kinds of collectors of electricity were used—one with a +copper disc for contact with the fish, and the other with a plate of +copper<span class='pagenum'><a name="Page_83" id="Page_83">[Pg 83]</a></span> bent into saddle shape, so that it might enclose a certain +extent of the back and sides of the fish. These conductors, being put +over the fish, collected power sufficient to produce many electric +effects.</p> + +<p><span class="smcap">Shock.</span> The shock was very powerful when the hands were placed one near +the head and the other near the tail, and the nearer the hands were +together, within certain limits, the less powerful was the shock. The +disc conductors conveyed the shock very well when the hands were wetted.</p> + +<p><span class="smcap">Galvanometer.</span> A galvanometer was readily affected by using the saddle +conductors, applied to the anterior and posterior parts of the gymnotus. +A powerful discharge of the fish caused a deflection of thirty or forty +degrees. The deflection was constantly in a given direction, the +electric current being always from the anterior part of the animal +through the galvanometer wire to the posterior parts. The former were, +therefore, for the time externally positive and the latter negative.</p> + +<p><span class="smcap">Making a Magnet.</span> When a little helix containing twenty-two feet of +silked wire wound on a quill was put into a circuit, and an annealed +steel needle placed in the helix, the needle became a magnet; and the +direction of its polarity in every cast indicated a current from the +anterior to the posterior parts of the gymnotus.</p> + +<p><span class="smcap">Chemical Decomposition.</span> Polar decomposition of a solution of iodide of +potassium was easily obtained.</p> + +<p><span class="smcap">Evolution of Heat.</span> Using a Harris' thermo-electrometer, we thought we +were able, in one instance, to observe a feeble elevation of +temperature.</p> + +<p><span class="smcap">Spark.</span> By suitable apparatus a spark was obtained four times.</p> + +<p>Such were the general electric phenomena obtained from the gymnotus, and +on several occasions many of the phenomena were obtained together. Thus, +a magnet was made, a galvanometer deflected, and, perhaps, a wire heated +by one single discharge of the electric<span class='pagenum'><a name="Page_84" id="Page_84">[Pg 84]</a></span> force of the animal. When the +shock is strong, it is like that of a large Leyden battery charged to a +low degree, or that of a good voltaic battery of, perhaps, one hundred +or more pairs of plates, of which the circuit is completed for a moment +only.</p> + +<p>I endeavoured by experiment to form some idea of the quantity of +electricity, and came to the conclusion that a single medium discharge +of the fish is at least equal to the electricity of a Leyden battery of +fifteen jars, containing 3,500 square inches of glass coated on both +sides, charged to its highest degree. This conclusion is in perfect +accordance with the degree of deflection which the discharge can produce +in a galvanometer needle, and also with the amount of chemical +decomposition produced in the electrolysing experiments.</p> + +<p>The gymnotus frequently gives a double and even a triple shock, with +scarcely a sensible interval between each discharge.</p> + +<p>As at the moment of shock the anterior parts are positive and the +posterior negative, it may be concluded that there is a current from the +former to the latter through every part of the water which surrounds the +animal, to a considerable distance from its body. The shock which is +felt, therefore, when the hands are in the most favourable position is +the effect of a very small portion only of the electricity which the +animal discharges at the moment, by far the largest portion passing +through the surrounding water.</p> + +<p>This enormous external current must be accompanied by some effect within +the fish <i>equivalent</i> to a current, the direction of which is from the +tail towards the head, and equal to the sum of <i>all these external</i> +forces. Whether the process of evolving or exciting the electricity +within the fish includes the production of the internal current, which +is not necessarily so quick and momentary as the external one, we cannot +at present say; but at the time of the shock the animal does not +apparently feel the<span class='pagenum'><a name="Page_85" id="Page_85">[Pg 85]</a></span> electric sensation which he causes in those around +him.</p> + +<p>The gymnotus can stun and kill fish which are in very various relations +to its own body. The extent of surface which the fish that is about to +be struck offers to the water conducting the electricity increases the +effect of the shock, and the larger the fish, accordingly, the greater +must be the shock to which it will be subjected.</p> + + + +<hr /> +<p class="book"><big><a name="The_Chemical_History_of_a_Candle" id="The_Chemical_History_of_a_Candle"></a>The Chemical History of a Candle</big></p> + +<div class="blockquot"><p>"The Chemical History of a Candle" was the most famous course in +the long and remarkable series of Christmas lectures, "adapted to a +juvenile auditory," at the Royal Institution, and remains a +rarely-approached model of what such lectures should be. They were +illustrated by experiments and specimens, but did not depend upon +these for coherence and interest. They were delivered in 1860–61, +and have just been translated, though all but half-a-century old, +into German.</p></div> + + +<p class="subchap"><i>I.—Candles and their Flames</i></p> + +<p><span class="smcap">There</span> is not a law under which any part of this universe is governed +that does not come into play in the phenomena of the chemical history of +a candle. There is no better door by which you can enter into the study +of natural philosophy than by considering the physical phenomena of a +candle.</p> + +<p>And now, my boys and girls, I must first tell you of what candles are +made. Some are great curiosities. I have here some bits of timber, +branches of trees particularly famous for their burning. And here you +see a piece of that very curious substance taken out of some of the bogs +in Ireland, called <i>candle-wood</i>—a hard, strong, excellent wood, +evidently fitted for good work as a resister of force, and yet withal +burning so well that, where it is found, they make splinters of it, and<span class='pagenum'><a name="Page_86" id="Page_86">[Pg 86]</a></span> +torches, since it burns like a candle, and gives a very good light +indeed. And in this wood we have one of the most beautiful illustrations +of the general nature of a candle that I can possibly give. The fuel +provided, the means of bringing that fuel to the place of chemical +action, the regular and gradual supply of air to that place of +action—heat and light all produced by a little piece of wood of this +kind, forming, in fact, a natural candle.</p> + +<p>But we must speak of candles as they are in commerce. Here are a couple +of candles commonly called dips. They are made of lengths of cotton cut +off, hung up by a loop, dipped into melted tallow, taken out again and +cooled; then re-dipped until there is an accumulation of tallow round +the cotton. However, a candle, you know, is not now a greasy thing like +an ordinary tallow candle, but a clean thing; and you may almost scrape +off and pulverise the drops which fall from it without soiling anything.</p> + +<p>The candle I have in my hand is a stearine candle, made of stearine from +tallow. Then here is a sperm candle, which comes from the purified oil +of the spermaceti whale. Here, also, are yellow beeswax and refined +beeswax from which candles are made. Here, too, is that curious +substance called paraffin, and some paraffin candles made of paraffin +obtained from the bogs of Ireland. I have here also a substance brought +from Japan, a sort of wax which a kind friend has sent me, and which +forms a new material for the manufacture of candles.</p> + +<p>Now, as to the light of the candle. We will light one or two, and set +them at work in the performance of their proper function. You observe a +candle is a very different thing from a lamp. With a lamp you take a +little oil, fill your vessel, put in a little moss, or some cotton +prepared by artificial means, and then light the top of the wick. When +the flame runs down the cotton to the oil, it gets stopped, but it goes +on burning in the part above.<span class='pagenum'><a name="Page_87" id="Page_87">[Pg 87]</a></span> Now, I have no doubt you will ask, how is +it that the oil, which will not burn of itself, gets up to the top of +the cotton, where it will burn? We shall presently examine that; but +there is a much more wonderful thing about the burning of a candle than +this. You have here a solid substance with no vessel to contain it; and +how is it that this solid substance can get up to the place where the +flame is? Or, when it is made a fluid, then how is it that it keeps +together? This is a wonderful thing about a candle.</p> + +<p>You see, then, in the first instance, that a beautiful cup is formed. As +the air comes to the candle, it moves upwards by the force of the +current which the heat of the candle produces, and it so cools all the +sides of the wax, tallow, or fuel as to keep the edge much cooler than +the part within; the part within melts by the flame that runs down the +wick as far as it can go before it is stopped, but the part on the +outside does not melt. If I made a current in one direction, my cup +would be lopsided, and the fluid would consequently run over—for the +same force of gravity which holds worlds together, holds this fluid in a +horizontal position. You see, therefore, that the cup is formed by this +beautifully regular ascending current of air playing upon all sides, +which keeps the exterior of the candle cool. No fuel would serve for a +candle which has not the property of giving this cup, except such fuel +as the Irish bogwood, where the material itself is like a sponge, and +holds its own fuel.</p> + +<p>You see now why you have such a bad result if you burn those beautiful +fluted candles, which are irregular, intermittent in their shape, and +cannot therefore have that nicely-formed edge to the cup which is the +great beauty in a candle. I hope you will now see that the perfection of +a process—that is, its utility—is the better point of beauty about it. +It is not the best-looking thing, but the best-acting thing which is the +most advantageous to us. This good-looking candle is a bad burning one.<span class='pagenum'><a name="Page_88" id="Page_88">[Pg 88]</a></span> +There will be a guttering round about it because of the irregularity of +the stream of air and the badness of the cup which is formed thereby.</p> + +<p>You may see some pretty examples of the action of the ascending current +when you have a little gutter run down the side of a candle, making it +thicker there than it is elsewhere. As the candle goes on burning, that +keeps its place and forms a little pillar sticking up by the side, +because, as it rises higher above the rest of the wax or fuel, the air +gets better round it, and it is more cooled and better able to resist +the action of the heat at a little distance. Now, the greatest mistakes +and faults with regard to candles, as in many other things, often bring +with them instruction which we should not receive if they had not +occurred. You will always remember that whenever a result happens, +especially if it be new, you should say: "What is the cause? Why does it +occur?" And you will in the course of time find out the reason.</p> + +<p>Then there is another point about these candles which will answer a +question—that is, as to the way in which this fluid gets out of the +cup, up to the wick, and into the place of combustion. You know that the +flames on these burning wicks in candles made of beeswax, stearine, or +spermaceti, do not run down to the wax or other matter, and melt it all +away, but keep to their own right place. They are fenced off from the +fluid below, and do not encroach on the cup at the sides.</p> + +<p>I cannot imagine a more beautiful example than the condition of +adjustment under which a candle makes one part subserve to the other to +the very end of its action. A combustible thing like that, burning away +gradually, never being intruded upon by the flame, is a very beautiful +sight; especially when you come to learn what a vigorous thing flame is, +what power it has of destroying the wax itself when it gets hold of it, +and of disturbing its proper form if it come only too near.</p> + +<p><span class='pagenum'><a name="Page_89" id="Page_89">[Pg 89]</a></span></p><p>But how does the flame get hold of the fuel? There is a beautiful point +about that. It is by what is called capillary attraction that the fuel +is conveyed to the part where combustion goes on, and is deposited +there, not in a careless way, but very beautifully in the very midst of +the centre of action which takes place around it.</p> + + +<p class="subchap"><i>II.—The Brightness of the Candle</i></p> + +<p>Air is absolutely necessary for combustion; and, what is more, I must +have you understand that <i>fresh</i> air is necessary, or else we should be +imperfect in our reasoning and our experiments. Here is a jar of air. I +place it over a candle, and it burns very nicely in it at first, showing +that what I have said about it is true; but there will soon be a change. +See how the flame is drawing upwards, presently fading, and at last +going out. And going out, why? Not because it wants air merely, for the +jar is as full now as it was before, but it wants pure, fresh air. The +jar is full of air, partly changed, partly not changed; but it does not +contain sufficient of the fresh air for combustion.</p> + +<p>Suppose I take a candle, and examine that part of it which appears +brightest to our eyes. Why, there I get these black particles, which are +just the smoke of the candle; and this brings to mind that old +employment which Dean Swift recommended to servants for their amusement, +namely, writing on the ceiling of a room with a candle. But what is that +black substance? Why, it is the same carbon which exists in the candle. +It evidently existed in the candle, or else we should not have had it +here. You would hardly think that all those substances which fly about +London in the form of soots and blacks are the very beauty and life of +the flame. Here is a piece of wire gauze which will not let the flame go +through it, and I think you will see, almost immediately, that, when I +bring it low enough to touch that part<span class='pagenum'><a name="Page_90" id="Page_90">[Pg 90]</a></span> of the flame which is otherwise +so bright, it quells and quenches it at once, and allows a volume of +smoke to rise up.</p> + +<p>Whenever a substance burns without assuming the vaporous state—whether +it becomes liquid or remains solid—it becomes exceedingly luminous. +What I say is applicable to all substances—whether they burn or whether +they do not burn—that they are exceedingly bright if they retain their +solid state when heated, and that it is to this presence of solid +particles in the candle-flame that it owes its brilliancy.</p> + +<p>I have here a piece of carbon, or charcoal, which will burn and give us +light exactly in the same manner as if it were burnt as part of a +candle. The heat that is in the flame of a candle decomposes the vapour +of the wax, and sets free the carbon particles—they rise up heated and +glowing as this now glows, and then enter into the air. But the +particles when burnt never pass off from a candle in the form of carbon. +They go off into the air as a perfectly invisible substance, about which +we shall know hereafter.</p> + +<p>Is it not beautiful to think that such a process is going on, and that +such a dirty thing as charcoal can become so incandescent? You see, it +comes to this—that all bright flames contain these solid particles; all +things that burn and produce solid particles, either during the time +they are burning, as in the candle, or immediately after being burnt, as +in the case of the gunpowder and iron-filings—all these things give us +this glorious and beautiful light.</p> + + +<p class="subchap"><i>III.—The Products of Combustion</i></p> + +<p>We observe that there are certain products as the result of the +combustion of a candle, and that of these products one portion may be +considered as charcoal, or soot; that charcoal, when afterwards burnt, +produces<span class='pagenum'><a name="Page_91" id="Page_91">[Pg 91]</a></span> some other product—carbonic acid, as we shall see; and it +concerns us very much now to ascertain what yet a third product is.</p> + +<p>Suppose I take a candle and place it under a jar. You see that the sides +of the jar become cloudy, and the light begins to burn feebly. It is the +products, you see, which make the light so dim, and this is the same +thing which makes the sides of the jar so opaque. If you go home and +take a spoon that has been in the cold air, and hold it over a +candle—not so as to soot it—you will find that it becomes dim, just as +that jar is dim. If you can get a silver dish, or something of that +kind, you will make the experiment still better. It is <i>water</i> which +causes the dimness, and we can make it, without difficulty, assume the +form of a liquid.</p> + +<p>And so we can go on with almost all combustible substances, and we find +that if they burn with a flame, as a candle, they produce water. You may +make these experiments yourselves. The head of a poker is a very good +thing to try with, and if it remains cold long enough over the candle, +you may get water condensed in drops on it; or a spoon, or a ladle, or +anything else may be used, provided it be clean, and can carry off the +heat, and so condense the water.</p> + +<p>And now—to go into the history of this wonderful production of water +from combustibles, and by combustion—I must first of all tell you that +this water may exist in different conditions; and although you may now +be acquainted with all its forms, they still require us to give a little +attention to them for the present, so that we may perceive how the +water, whilst it goes through its protean changes, is entirely and +absolutely the same thing, whether it is produced from a candle, by +combustion, or from the rivers or ocean.</p> + +<p>First of all, water, when at the coldest, is ice. Now, we speak of water +as water; whether it be in its solid,<span class='pagenum'><a name="Page_92" id="Page_92">[Pg 92]</a></span> or liquid, or gaseous state, we +speak of it chemically as water.</p> + +<p>We shall not in future be deceived, therefore, by any changes that are +produced in water. Water is the same everywhere, whether produced from +the ocean or from the flame of the candle. Where, then, is this water +which we get from a candle? It evidently comes, as to part of it, from +the candle; but is it within the candle beforehand? No! It is not in the +candle; and it is not in the air round about the candle, which is +necessary for its combustion. It is neither in one nor the other, but it +comes from their conjoint action, a part from the candle, a part from +the air. And this we have now to trace.</p> + +<p>If we decompose water we can obtain from it a gas. This is hydrogen—a +body classed amongst those things in chemistry which we call elements, +because we can get nothing else out of them. A candle is not an +elementary body, because we can get carbon out of it; we can get this +hydrogen out of it, or at least out of the water which it supplies. And +this gas has been so named hydrogen because it is that element which, in +association with another, generates water.</p> + +<p>Hydrogen gives rise to no substance that can become solid, either during +combustion or afterwards, as a product of its combustion. But when it +burns it produces water only; and if we take a cold glass and put it +over the flame, it becomes damp, and you have water produced immediately +in appreciable quantity, and nothing is produced by its combustion but +the same water which you have seen the flame of a candle produce. This +hydrogen is the only thing in Nature that furnishes water as the sole +product of combustion.</p> + +<p>Water can be decomposed by electricity, and then we find that its other +constituent is the gas oxygen in which, as can easily be shown, a candle +or a lamp burns much more brilliantly than it does in air, but produces +the same products as when it burns in air. We thus find<span class='pagenum'><a name="Page_93" id="Page_93">[Pg 93]</a></span> that oxygen is +a constituent of the air, and by burning something in the air we can +remove the oxygen therefrom, leaving behind for our study the nitrogen, +which constitutes about four-fifths of the air, the oxygen accounting +for nearly all the rest.</p> + +<p>The other great product of the burning of a candle is carbonic acid—a +gas formed by the union of the carbon of the candle and the oxygen of +the air. Whenever carbon burns, whether in a candle or in a living +creature, it produces carbonic acid.</p> + + +<p class="subchap"><i>IV.—Combustion and Respiration</i></p> + +<p>Now I must take you to a very interesting part of our subject—to the +relation between the combustion of a candle and that living kind of +combustion which goes on within us. In every one of us there is a living +process of combustion going on very similar to that of a candle. For it +is not merely true in a poetical sense—the relation of the life of man +to a taper. A candle will burn some four, five, six, or seven hours. +What, then, must be the daily amount of carbon going up into the air in +the way of carbonic acid? What a quantity of carbon must go from each of +us in respiration! A man in twenty-four hours converts as much as seven +ounces of carbon into carbonic acid; a milch cow will convert seventy +ounces, and a horse seventy-nine ounces, solely by the act of +respiration. That is, the horse in twenty-four hours burns seventy-nine +ounces of charcoal, or carbon, in his organs of respiration to supply +his natural warmth in that time.</p> + +<p>All the warm-blooded animals get their warmth in this way, by the +conversion of carbon; not in a free state, but in a state of +combination. And what an extraordinary notion this gives us of the +alterations going out in our atmosphere! As much as 5,000,000 pounds of +carbonic acid is formed by respiration in London alone<span class='pagenum'><a name="Page_94" id="Page_94">[Pg 94]</a></span> in twenty-four +hours. And where does all this go? Up into the air. If the carbon had +been like lead or iron, which, in burning, produces a solid substance, +what would happen? Combustion would not go on. As charcoal burns, it +becomes a vapour and passes off into the atmosphere, which is the great +vehicle, the great carrier, for conveying it away to other places. Then, +what becomes of it?</p> + +<p>Wonderful is it to find that the change produced by respiration, which +seems so injurious to us, for we cannot breathe air twice over, is the +very life and support of plants and vegetables that grow upon the +surface of the earth. It is the same also under the surface in the great +bodies of water, for fishes and other animals respire upon the same +principle, though not exactly by contact with the open air. They respire +by the oxygen which is dissolved from the air by the water, and form +carbonic acid; and they all move about to produce the one great work of +making the animal and vegetable kingdoms subservient to each other.</p> + +<p>All the plants growing upon the surface of the earth absorb carbon. +These leaves are taking up their carbon from the atmosphere, to which we +have given it in the form of carbonic acid, and they are prospering. +Give them a pure air like ours, and they could not live in it; give them +carbon with other matters, and they live and rejoice. So are we made +dependent not merely upon our fellow-creatures, but upon our +fellow-existers, all Nature being tied by the laws that make one part +conduce to the good of the other.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_95" id="Page_95">[Pg 95]</a></span></p> +<h3>AUGUSTE FOREL</h3> + +<p class="book"><big><a name="The_Senses_of_Insects" id="The_Senses_of_Insects"></a>The Senses of Insects</big></p> + +<div class="blockquot"><p>Auguste Forel, who in 1909 retired from the Chair of Morbid +Psychology in the University of Zürich, was born on September 1, +1848, and is one of the greatest students of the minds and senses +of the lower animals and mankind. Among his most famous works are +his "Hygiene of Nerves and Mind," his great treatise on the whole +problem of sex in human life, of which a cheap edition entitled +"Sexual Ethics" is published, his work on hypnotism, and his +numerous contributions to the psychology of insects. The chief +studies of this remarkable and illustrious student and thinker for +many decades past have been those of the senses and mental +faculties of insects. He has recorded the fact that his study of +the beehive led him to his present views as to the right +constitution of the state—views which may be described as +socialism with a difference. His work on insects has served the +study of human psychology, and is in itself the most important +contribution to insect psychology ever made by a single student. +Only within the last two years has the work of Forel, long famous +on the European Continent, begun to be known abroad.</p></div> + + +<p class="subchap"><i>I.—Insect Activity and Instinct</i></p> + +<p>This subject is one of great interest, as much from the standpoint of +biology as from that of comparative psychology. The very peculiar +mechanism of instincts always has its starting-point in sensations. To +comprehend this mechanism it is essential to understand thoroughly the +organs of sense and their special functions.</p> + +<p>It is further necessary to study the co-ordination which exists between +the action of the different senses, and leads to their intimate +connection with the functions of the nerve-centres, that is to say, with +the specially instinctive intelligence of insects. The whole question +is, therefore, a chapter of comparative psychology, a chapter in which +it is necessary to take careful note of<span class='pagenum'><a name="Page_96" id="Page_96">[Pg 96]</a></span> every factor, to place oneself, +so to speak, on a level with the mind of an insect, and, above all, to +avoid the anthropomorphic errors with which works upon the subject are +filled.</p> + +<p>At the same time the other extreme must equally be +avoided—"anthropophobia," which at all costs desires to see in every +living organism a "machine," forgetting that a "machine" which lives, +that is to say, which grows, takes in nutriment, and strikes a balance +between income and expenditure, which, in a word, continually +reconstructs itself, is not a "machine," but something entirely +different. In other words, it is necessary to steer clear of two +dangers. We must avoid (1) identifying the mind of an insect with our +own, but, above all, (2) imagining that we, with what knowledge we +possess, can reconstruct the mind by our chemical and physical laws.</p> + +<p>On the other hand, we have to recognise the fact that this mind, and the +sensory functions which put it on its guard, are derived, just as with +our human selves, from the primitive protoplasmic life. This life, so +far as it is specialised in the nervous system by nerve irritability and +its connections with the muscular system, is manifested under two +aspects. These may be likened to two branches of one trunk.</p> + +<p>(<i>a</i>) <i>Automatic</i> or <i>instinctive</i> activity. This, though perfected by +repetition, is definitely inherited. It is uncontrollable and constant +in effect, adapted to the circumstances of the special life of the race +in question. It is this curious instinctive adaptation—which is so +intelligent when it carries out its proper task, so stupid and incapable +when diverted to some other purpose—that has deceived so many +scientists and philosophers by its insidious analogy with humanly +constructed machines.</p> + +<p>But, automatic as it may appear, instinct is not invariable. In the +first place, it presents a racial evolution which of itself alone +already demonstrates a certain<span class='pagenum'><a name="Page_97" id="Page_97">[Pg 97]</a></span> degree of plasticity from generation to +generation. It presents, further, individual variations which are more +distinct as it is less deeply fixed by heredity. Thus the divergent +instincts of two varieties, <i>e.g.</i>, of insects, present more individual +variability and adaptability than do those instincts common to all +species of a genus. In short, if we carefully study the behaviour of +each individual of a species of insects with a developed brain (as has +been done by P. Huber, Lubbock, Wasmann, and myself, among others, for +bees, wasps, and ants), we are not long in finding noteworthy +differences, especially when we put the instinct under abnormal +conditions. We then force the nervous activity of these insects to +present a second and plastic aspect, which to a large extent has been +hidden from us under their enormously developed instinct.</p> + +<p>(<i>b</i>) The <i>plastic</i> or <i>adaptive</i> activity is by no means, as has been +so often suggested, a derivative of instinct. It is primitive. It is +even the fundamental condition of the evolution of life. The living +being is distinguished by its power of adaptation; even the amoeba is +plastic. But in order that one individual may adapt itself to a host of +conditions and possibilities, as is the case with the higher mammals and +especially with man, the brain requires an enormous quantity of nerve +elements. But this is not the case with the fixed and specialised +adaptation of instinct.</p> + +<p>In secondary automatism, or habit, which we observe in ourselves, it is +easy to study how this activity, derived from plastic activity, and ever +becoming more prompt, complex, and sure (technical habits), necessitates +less and less expenditure of nerve effort. It is very difficult to +understand how inherited instinct, hereditary automatism, could have +originated from the plastic activities of our ancestors. It seems as if +a very slow selection, among individuals best adapted in consequence of +fortunate parentage, might perhaps account for it.</p> + +<p><span class='pagenum'><a name="Page_98" id="Page_98">[Pg 98]</a></span></p><p>To sum up, every animal possesses two kinds of activity in varying +degrees, sometimes one, sometimes the other predominating. In the lowest +beings they are both rudimentary. In insects, special automatic activity +reaches the summit of development and predominance; in man, on the +contrary, with his great brain development, plastic activity is elevated +to an extraordinary height, above all by language, and before all by +written language, which substitutes graphic fixation for secondary +automatism, and allows the accumulation outside the brain of the +knowledge of past generations, thus serving his plastic activity, at +once the adapter and combiner of what the past has bequeathed to it.</p> + +<p>According to the families, <i>genera</i>, and species of insects, the +development of different senses varies extremely. We meet with most +striking contrasts, and contrasts which have not been sufficiently +noticed. Certain insects, dragon-flies, for instance, live almost +entirely by means of sight. Others are blind, or almost blind, and +subsist exclusively by smell and taste (insects inhabiting caves, most +working ants). Hearing is well developed in certain forms (crickets, +locusts), but most insects appear not to hear, or to hear with +difficulty. Despite their thick, chitinous skeleton, almost all insects +have extremely sensitive touch, especially in the antennæ, but not +confined thereto.</p> + +<p>It is absolutely necessary to bear in mind the mental faculties of +insects in order to judge with a fair degree of accuracy how they use +their senses. We shall return to that point when summing up.</p> + + +<p class="subchap"><i>II.—The Vision of Insects</i></p> + +<p>In vision we are dealing with a certain definite stimulus—light, with +its two modifications, colour and motion. Insects have two sets of +organs for vision, the faceted eye and the so-called simple eye, or +ocellus.<span class='pagenum'><a name="Page_99" id="Page_99">[Pg 99]</a></span> These have been historically derived from one and the same +organ. In order to exercise the function of sight the facets need a +greater pencil of light rays by night than by day. To obtain the same +result we dilate the pupil. But nocturnal insects are dazzled by the +light of day, and diurnal insects cannot see by night, for neither +possess the faculty of accommodation. Insects are specially able to +perceive motion, but there are only very few insects that can see +distinctly.</p> + +<p>For example, I watched one day a wasp chasing a fly on the wall of a +veranda, as is the habit of this insect at the end of summer and in the +autumn. She dashed violently in flight at the flies sitting on the wall, +which mostly escaped. She continued her pursuit with remarkable +pertinacity, and succeeded on several occasions in catching a fly, which +she killed, mutilated, and bore away to her nest. Each time she quickly +returned to continue the hunt.</p> + +<p>In one spot of the wall was stuck a black nail, which was just the size +of a fly, and I saw the wasp very frequently deceived by this nail, upon +which she sprang, leaving it as soon as she perceived her error on +touching it. Nevertheless, she made the same mistake with the nail +shortly after. I have often made similar observations. We may certainly +conclude that the wasp saw something of the size of a fly, but without +distinguishing the details; therefore she saw it indistinctly. Evidently +a wasp does not only perceive motion; she also distinguishes the size of +objects. When I put dead flies on a table to be carried off by another +wasp, she took them, one after another, as well as spiders and other +insects of but little different size placed by their side. On the other +hand, she took no notice of insects much larger or much smaller put +among the flies.</p> + +<p>Most entomologists have observed with what ingenuity and sureness +dragon-flies distinguish, follow, and catch the smallest insects on the +wing. Of all insects,<span class='pagenum'><a name="Page_100" id="Page_100">[Pg 100]</a></span> they have the best sight. Their enormous convex +eyes have the greatest number of facets. Their number has been estimated +at 12,000, and even at 17,000. Their aerial chases resemble those of the +swallows. By trying to catch them at the edge of a large pond, one can +easily convince oneself that the dragon-flies amuse themselves by making +sport of the hunter; they will always allow one to approach just near +enough to miss catching them. It can be seen to what degree they are +able to measure the distance and reach of their enemy.</p> + +<p>It is an absolute fact that dragon-flies, unless it is cold or in the +evening, always manage to fly at just that distance at which the student +cannot touch them; and they see perfectly well whether one is armed with +a net or has nothing but his hands; one might even say that they measure +the length of the handle of the net, for the possession of a long handle +is no advantage. They fly just out of reach of one's instrument, +whatever trouble one may give oneself by hiding it from them and +suddenly lunging as they fly off. Whoever watches butterflies and flies +will soon see that these insects also can measure the distance of such +objects as are not far from them. The males and females of bees and ants +distinguish one another on the wing. It is rare for an individual to +lose sight of the swarm or to miss what it pursues flying. It has been +proved that the sense of smell has nothing to do with this matter. Thus +insects, though without any power of accommodation for light or +distance, are able to perceive objects at different distances.</p> + +<p>It is known that many insects will blindly fly and dash against a lamp +at night, until they burn themselves. It has often been wrongly thought +that they are fascinated. We ought first to remember that natural +lights, concentrated at one point like our artificial lights, are +extremely rare in Nature. The light of day, which is the light of wild +animals, is not concentrated at one point. Insects, when they are in +darkness—underground, <span class='pagenum'><a name="Page_101" id="Page_101">[Pg 101]</a></span>beneath bark or leaves—are accustomed to reach +the open air, where the light is everywhere diffused, by directing +themselves towards the luminous point. At night, when they fly towards a +lamp, they are evidently deceived, and their small brains cannot +comprehend the novelty of this light concentrated at one spot. +Consequently, their fruitless efforts are again and again renewed +against the flame, and the poor innocents end by burning themselves. +Several domestic insects, which have become little by little adapted to +artificial light in the course of generations, no longer allow +themselves to be deceived thereby. This is the case with house-flies.</p> + +<p>Bees distinguish all colours, and seldom confound any but blue and +green; while wasps scarcely react to differences of colour, but note +better the shape of an object, and note, for instance, where the place +of honey is; so that a change of colour on the disc whereon the honey is +placed hardly upsets them. Further, wasps have a better sense of smell +than bees.</p> + +<p>The chief discovery regarding the vision of insects made in the last +thirty years is that of Lubbock, who proved that ants perceive the +ultra-violet rays of the spectrum, which we are unable, or almost +unable, to perceive.</p> + +<p>It has lately been proved also that many insects appreciate light by the +skin.</p> + +<p>They do not see as clearly as we do; but when they possess +well-developed compound eyes they appreciate size, and more or less +distinctly the contours of objects.</p> + +<p>Ants have a great faculty for recognition, which probably testifies to +their vision and visual memory. Lubbock observed ants which actually +recognised each other after more than a year of separation.</p> + + +<p><span class='pagenum'><a name="Page_102" id="Page_102">[Pg 102]</a></span></p><p class="subchap"><i>III.—Smell, Taste, Hearing, Pain</i></p> + +<p>Smell is very important in insects. It is difficult for us to judge of, +since man is of all the vertebrates except the whales, perhaps, the one +in which this sense is most rudimentary. We can evidently, therefore, +form only a feeble idea of the world of knowledge imparted by a smell to +a dog, a mole, a hedgehog, or an insect. The instruments of smell are +the antennæ. A poor ant without antennæ is as lost as a blind man who is +also deaf and dumb. This appears from its complete social inactivity, +its isolation, its incapacity to guide itself and to find its food. It +can, therefore, be boldly supposed that the antennæ and their power of +smell, as much on contact as at a distance, constitute the social sense +of ants, the sense which allows them to recognise one another, to tend +to their larvæ, and mutually help one another, and also the sense which +awakens their greedy appetites, their violent hatred for every being +foreign to the colony, the sense which principally guides them—a little +helped by vision, especially in certain species—in the long and patient +travels which they have to undertake, which makes them find their way +back, find their plant-lice, and all their other means of subsistence.</p> + +<p>As the philosopher Herbert Spencer has well pointed out, the visceral +sensations of man, and those internal senses which, like smell, can only +make an impression of one kind as regards space—two simultaneous odours +can only be appreciated by us as a mixture—are precisely those by which +we can gain little or no information relative to space. Our vision, on +the contrary, which localises the rays from various distant points of +space on various distinct points of our retina at the same time, is our +most relational sense, that which gives us the most vast ideas of space.</p> + +<p>But the antennæ of insects are an olfactory organ<span class='pagenum'><a name="Page_103" id="Page_103">[Pg 103]</a></span> turned inside out, +prominent in space, and, further, very mobile. This allows us to suppose +that the sense of smell may be much more relational than ours, that the +sensations thence derived give them ideas of space and of direction +which may be qualitatively different from ours.</p> + +<p>Taste exists in insects, and has been very widely written on, but +somewhat inconclusively. The organs of taste probably are to be found in +the jaws and at the base of the tongue. This sense can be observed in +ants, bees, and wasps; and everyone has seen how caterpillars especially +recognise by taste the plants which suit them.</p> + +<p>Much has been written on the hearing of insects; but, in my judgment, +only crickets and several other insects of that class appear to perceive +sounds. Erroneous views have been due to confusing hearing with +mechanical vibrations.</p> + +<p>We must not forget that the specialisation of the organ of hearing has +reached in man a delicacy of detail which is evidently not found again +in lower vertebrates.</p> + +<p>Pain is much less developed in insects than in warm-blooded vertebrates. +Otherwise, one could not see either an ant, with its abdomen or antennæ +cut off, gorge itself with honey; or a humble-bee, in which the antennæ +and all the front of the head had been removed, go to find and pillage +flowers; or a spider, the foot of which had been broken, feed +immediately on this, its own foot, as I myself have seen; or, finally, a +caterpillar, wounded at the "tail" end, devour itself, beginning behind, +as I have observed more than once.</p> + + +<p class="subchap"><i>IV.—Insect Reason and Passions</i></p> + +<p>Insects reason, and the most intelligent among them, the social +hymenoptera, especially the wasps and ants, even reason much more than +one is tempted to believe when one observes the regularly recurring +mechanism<span class='pagenum'><a name="Page_104" id="Page_104">[Pg 104]</a></span> of their instincts. To observe and understand these +reasonings well, it is necessary to mislead their instinct. Further, one +may remark little bursts of plastic judgment, of combinations—extremely +limited, it is true—which, in forcing them an instant from the beaten +track of their automatism, help them to overcome difficulties, and to +decide between two dangers. From the point of view of instinct and +intelligence, or rather of reason, there are not, therefore, absolute +contrasts between the insect, the mammal, and the man.</p> + +<p>Finally, insects have passions which are more or less bound up with +their instincts. And these passions vary enormously, according to the +species. I have noted the following passions or traits of character +among ants: choler, hatred, devotion, activity, perseverance, and +gluttony. I have added thereto the discouragement which is sometimes +shown in a striking manner at the time of a defeat, and which can become +real despair; the fear which is shown among ants when they are alone, +while it disappears when they are numerous. I can add further the +momentary temerity whereby certain ants, knowing the enemy to be +weakened and discouraged, hurl themselves alone in the midst of the +black masses of enemies larger than themselves, hustling them without +taking the least further precaution.</p> + +<p>When we study the manners of an insect, it is necessary for us to take +account of its mental faculties as well as of its sense organs. +Intelligent insects make better use of their senses, especially by +combining them in various ways. It is possible to study such insects in +their homes in a more varied and more complete manner, allowing greater +accuracy of observations.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_105" id="Page_105">[Pg 105]</a></span></p> +<h3>GALILEO</h3> + +<p class="book"><big><a name="Dialogues_on_the_System_of_the_World" id="Dialogues_on_the_System_of_the_World"></a>Dialogues on the System of the World</big></p> + +<div class="blockquot"><p>Galileo Galilei, famous as an astronomer and as an experimental +physicist, was born at Pisa, in Italy, Feb. 18, 1564. His talents +were most multifarious and remarkable; but his mathematical and +mechanical genius was dominant from the first. As a child he +constructed mechanical toys, and as a young man he made one of his +most important discoveries, which was that of the pendulum as an +agent in the measurement of time, and invented the hydrostatic +balance, by which the specific gravity of solid bodies might be +ascertained. At the age of 24 a learned treatise on the centre of +gravity of solids led to a lectureship at Pisa University. Driven +from Pisa by the enmity of Aristotelians, he went to Padua +University, where he invented a kind of thermometer, a proportional +compass, a microscope, and a telescope. The last invention bore +fruit in astronomical discoveries, and in 1610 he discovered four +of the moons of Jupiter. His promulgation of the Copernican +doctrine led to renewed attacks by the Aristotelians, and to +censure by the Inquisition. (<a href="https://www.gutenberg.org/files/13620/13620-h/13620-h.htm">See Religion, vol. xiii.</a>) +Notwithstanding this censure, he published in 1632 his "Dialogues +on the System of the World." The interlocutors in the "Dialogues," +with the exception of Salviatus, who expounds the views of the +author himself, represent two of Galileo's early friends. For the +"Dialogues" he was sentenced by the Inquisition to incarceration at +its pleasure, and enjoined to recite penitential psalms once a week +for three years. His life thereafter was full of sorrow, and in +1637 blindness added to his woes; but the fire of his genius still +burnt on till his death on January 8, 1642.</p></div> + + +<p class="subchap"><i>Does the Earth Move</i></p> + +<p><span class="smcap">Salviatus:</span> Now, let Simplicius propound those doubts which dissuade him +from believing that the earth may move, as the other planets, round a +fixed centre.</p> + +<p><span class="smcap">Simplicius:</span> The first and greatest difficulty is that it is impossible +both to be in a centre and to be far from it. If the earth move in a +circle it cannot remain in the centre of the zodiac; but Aristotle, +Ptolemy<span class='pagenum'><a name="Page_106" id="Page_106">[Pg 106]</a></span> and others have proved that it is in the centre of the zodiac.</p> + +<p><span class="smcap">Salviatus:</span> There is no question that the earth cannot be in the centre +of a circle round whose circumference it moves. But tell me what centre +do you mean?</p> + +<p><span class="smcap">Simplicius:</span> I mean the centre of the universe, of the whole world, of +the starry sphere.</p> + +<p><span class="smcap">Salviatus:</span> No one has ever proved that the universe is finite and +figurative; but granting that it is finite and spherical, and has +therefore a centre, we have still to give reasons why we should believe +that the earth is at its centre.</p> + +<p><span class="smcap">Simplicius:</span> Aristotle has proved in a hundred ways that the universe is +finite and spherical.</p> + +<p><span class="smcap">Salviatus:</span> Aristotle's proof that the universe was finite and spherical +was derived essentially from the consideration that it moved; and seeing +that centre and figure were inferred by Aristotle from its mobility, it +will be reasonable if we endeavour to find from the circular motions of +mundane bodies the centre's proper place. Aristotle himself came to the +conclusion that all the celestial spheres revolve round the earth, which +is placed at the centre of the universe. But tell me, Simplicius, +supposing Aristotle found that one of the two propositions must be +false, and that either the celestial spheres do not revolve or that the +earth is not the centre round which they revolve, which proposition +would he prefer to give up?</p> + +<p><span class="smcap">Simplicius:</span> I believe that the Peripatetics——</p> + +<p><span class="smcap">Salviatus:</span> I do not ask the Peripatetics, I ask Aristotle. As for the +Peripatetics, they, as humble vassals of Aristotle, would deny all the +experiments and all the observations in the world; nay, would also +refuse to see them, and would say that the universe is as Aristotle +writeth, and not as Nature will have it; for, deprived of the shield of +his authority, with what do you think they would appear in the field? +Tell me, therefore, what Aristotle himself would do.</p> + +<p><span class='pagenum'><a name="Page_107" id="Page_107">[Pg 107]</a></span></p><p><span class="smcap">Simplicius:</span> To tell you the truth, I do not know how to decide which is +the lesser inconvenience.</p> + +<p><span class="smcap">Salviatus:</span> Seeing you do not know, let us examine which would be the +more rational choice, and let us assume that Aristotle would have chosen +so. Granting with Aristotle that the universe has a spherical figure and +moveth circularly round a centre, it is reasonable to believe that the +starry orbs move round the centre of the universe or round some separate +centre?</p> + +<p><span class="smcap">Simplicius:</span> I would say that it were much more reasonable to believe +that they move with the universe round the centre of the universe.</p> + +<p><span class="smcap">Salviatus:</span> But they move round the sun and not round the earth; +therefore the sun and not the earth is the centre of the universe.</p> + +<p><span class="smcap">Simplicius:</span> Whence, then, do you argue that it is the sun and not the +earth that is the centre of the planetary revolutions?</p> + +<p><span class="smcap">Salviatus:</span> I infer that the earth is not the centre of the planetary +revolutions because the planets are at different times at very different +distances from the earth. For instance, Venus, when it is farthest off, +is six times more remote from us than when it is nearest, and Mars rises +almost eight times as high at one time as at another.</p> + +<p><span class="smcap">Simplicius:</span> And what are the signs that the planets revolve round the +sun as centre?</p> + +<p><span class="smcap">Salviatus:</span> We find that the three superior planets—Mars, Jupiter, and +Saturn—are always nearest to the earth when they are in opposition to +the sun, and always farthest off when they are in conjunction; and so +great is this approximation and recession that Mars, when near, appears +very nearly sixty times greater than when remote. Venus and Mercury also +certainly revolve round the sun, since they never move far from it, and +appear now above and now below it.</p> + +<p><span class='pagenum'><a name="Page_108" id="Page_108">[Pg 108]</a></span></p><p><span class="smcap">Sagredus:</span> I expect that more wonderful things depend on the annual +revolution than upon the diurnal rotation of the earth.</p> + +<p><span class="smcap">Salviatus:</span> YOU do not err therein. The effect of the diurnal rotation of +the earth is to make the universe seem to rotate in the opposite +direction; but the annual motion complicates the particular motions of +all the planets. But to return to my proposition. I affirm that the +centre of the celestial convolutions of the five planets—Saturn, +Jupiter, Mars, Venus, and Mercury, and likewise of the earth—is the +sun.</p> + +<p>As for the moon, it goes round the earth, and yet does not cease to go +round the sun with the earth. It being true, then, that the five planets +do move about the sun as a centre, rest seems with so much more reason +to belong to the said sun than to the earth, inasmuch as in a movable +sphere it is more reasonable that the centre stand still than any place +remote from the centre.</p> + +<p>To the earth, therefore, may a yearly revolution be assigned, leaving +the sun at rest. And if that be so, it follows that the diurnal motion +likewise belongs to the earth; for if the sun stood still and the earth +did not rotate, the year would consist of six months of day and six +months of night. You may consider, likewise, how, in conformity with +this scheme, the precipitate motion of twenty-four hours is taken away +from the universe; and how the fixed stars, which are so many suns, are +made, like our sun, to enjoy perpetual rest.</p> + +<p><span class="smcap">Sagredus:</span> The scheme is simple and satisfactory; but, tell me, how is it +that Pythagoras and Copernicus, who first brought it forward, could make +so few converts?</p> + +<p><span class="smcap">Salviatus:</span> If you know what frivolous reasons serve to make the vulgar, +contumacious and indisposed to hearken, you would not wonder at the +paucity of converts. The number of thick skulls is infinite, and we need +neither record their follies nor endeavour to interest<span class='pagenum'><a name="Page_109" id="Page_109">[Pg 109]</a></span> them in subtle +and sublime ideas. No demonstrations can enlighten stupid brains.</p> + +<p>My wonder, Sagredus, is different from yours. You wonder that so few are +believers in the Pythagorean hypothesis; I wonder that there are any to +embrace it. Nor can I sufficiently admire the super-eminence of those +men's wits that have received and held it to be true, and with the +sprightliness of their judgments have offered such violence to their +senses that they have been able to prefer that which their reason +asserted to that which sensible experience manifested. I cannot find any +bounds for my admiration how that reason was able, in Aristarchus and +Copernicus, to commit such a rape upon their senses, as in despite +thereof to make herself mistress of their credulity.</p> + +<p><span class="smcap">Sagredus:</span> Will there still be strong opposition to the Copernican +system?</p> + +<p><span class="smcap">Salviatus:</span> Undoubtedly; for there are evident and sensible facts to +oppose it, requiring a sense more sublime than the common and vulgar +senses to assist reason.</p> + +<p><span class="smcap">Sagredus:</span> Let us, then, join battle with those antagonistic facts.</p> + +<p><span class="smcap">Salviatus:</span> I am ready. In the first place, Mars himself charges hotly +against the truth of the Copernican system. According to the Copernican +system, that planet should appear sixty times as large when at its +nearest as when at its farthest; but this diversity of magnitude is not +to be seen. The same difficulty is seen in the case of Venus. Further, +if Venus be dark, and shine only with reflected light, like the moon, it +should show lunar phases; but these do not appear.</p> + +<p>Further, again, the moon prevents the whole order of the Copernican +system by revolving round the earth instead of round the sun. And there +are other serious and curious difficulties admitted by Copernicus +himself. But even the three great difficulties I have named are not<span class='pagenum'><a name="Page_110" id="Page_110">[Pg 110]</a></span> +real. As a matter of fact, Mars and Venus do vary in magnitude as +required by theory, and Venus does change its shape exactly like the +moon.</p> + +<p><span class="smcap">Sagredus:</span> But how came this to be concealed from Copernicus and revealed +to you?</p> + + + +<hr /><p><span class='pagenum'><a name="Page_111" id="Page_111">[Pg 111]</a></span></p> +<h3>SIR FRANCIS GALTON</h3> + +<p class="book"><big><a name="Essays_in_Eugenics" id="Essays_in_Eugenics"></a>Essays in Eugenics</big></p> + +<div class="blockquot"><p>Sir Francis Galton, born at Birmingham, England, in 1822, was a +grandson of Dr. Erasmus Darwin. He graduated from Trinity College, +Cambridge, in 1844. Galton travelled in the north of Africa, on the +White Nile and in the western portion of South Africa between 1844 +and 1850. Like his immortal cousin, Charles Darwin, Sir Francis +Galton is a striking instance of a man of great and splendid +inheritance, who, also inheriting wealth, devotes it and his powers +to the cause of humanity. He published several books on heredity, +the first of which was "Hereditary Genius." The next "Inquiries +into Human Faculty," which was followed by "Natural Inheritance." +The "Essays in Eugenics" include all the most recent work of Sir +Francis Galton since his return to the subject of eugenics in 1901. +This volume has just been published by the Eugenics Education +Society, of which Sir Francis Galton is the honorary president. As +epitomised for this work, the "Essays" have been made to include a +still later study by the author, which will be included in future +editions of the book. The epitome has been prepared by special +permission of the Eugenics Education Society, and those responsible +hope that it will serve in some measure to neutralise the +outrageous, gross, and often wilful misrepresentations of eugenics +of which many popular writers are guilty.</p></div> + + +<p class="subchap"><i>I.—The Aims and Methods of Eugenics</i></p> + +<p><span class="smcap">The</span> following essays help to show something of the progress of eugenics +during the last few years, and to explain my own views upon its aims and +methods, which often have been, and still sometimes are, absurdly +misrepresented. The practice of eugenics has already obtained a +considerable hold on popular estimation, and is steadily acquiring the +status of a practical question, and not that of a mere vision in Utopia.</p> + +<p>The power by which eugenic reform must chiefly be effected is that of +public opinion, which is amply strong<span class='pagenum'><a name="Page_112" id="Page_112">[Pg 112]</a></span> enough for that purpose whenever +it shall be roused. Public opinion has done as much as this on many past +occasions and in various countries, of which much evidence is given in +the essay on restrictions in marriage. It is now ordering our acts more +intimately than we are apt to suspect, because the dictates of public +opinion become so thoroughly assimilated that they seem to be the +original and individual to those who are guided by them. By comparing +the current ideas at widely different epochs and under widely different +civilisations, we are able to ascertain what part of our convictions is +really innate and permanent, and what part has been acquired and is +transient.</p> + +<p>It is, above all things, needful for the successful progress of eugenics +that its advocates should move discreetly and claim no more efficacy on +its behalf than the future will justify; otherwise a reaction will be +justified. A great deal of investigation is still needed to show the +limit of practical eugenics, yet enough has been already determined to +justify large efforts being made to instruct the public in an +authoritative way, with the results hitherto obtained by sound +reasoning, applied to the undoubted facts of social experience.</p> + +<p>The word "eugenics" was coined and used by me in my book "Human +Faculty," published as long ago as 1883. In it I emphasised the +essential brotherhood of mankind, heredity being to my mind a very real +thing; also the belief that we are born to act, and not to wait for help +like able-bodied idlers, whining for doles. Individuals appear to me as +finite detachments from an infinite ocean of being, temporarily endowed +with executive powers. This is the only answer I can give to myself in +reply to the perpetually recurring questions of "why? whence? and +whither?" The immediate "whither?" does not seem wholly dark, as some +little information may be gleaned concerning the direction in which +Nature, so far as we know of it, is now moving—namely,<span class='pagenum'><a name="Page_113" id="Page_113">[Pg 113]</a></span> towards the +evolution of mind, body, and character in increasing energy and +co-adaptation.</p> + +<p>The ideas have long held my fancy that we men may be the chief, and +perhaps the only executives on earth; that we are detached on active +service with, it may be only illusory, powers of free-will. Also that we +are in some way accountable for our success or failure to further +certain obscure ends, to be guessed as best we can; that though our +instructions are obscure they are sufficiently clear to justify our +interference with the pitiless course of Nature whenever it seems +possible to attain the goal towards which it moves by gentler and +kindlier ways.</p> + +<p>There are many questions which must be studied if we are to be guided +aright towards the possible improvement of mankind under the existing +conditions of law and sentiment. We must study human variety, and the +distribution of qualities in a nation. We must compare the +classification of a population according to social status with the +classification which we would make purely in terms of natural quality. +We must study with the utmost care the descent of qualities in a +population, and the consequences of that marked tendency to marriage +within the class which distinguishes all classes. Something is to be +learnt from the results of examinations in universities and colleges.</p> + +<p>It is desirable to study the degree of correspondence that may exist +between promise in youth, as shown in examinations, and subsequent +performance. Let me add that I think the neglect of this inquiry by the +vast army of highly educated persons who are connected with the present +huge system of competitive examination to be gross and unpardonable. +Until this problem is solved we cannot possibly estimate the value of +the present elaborate system of examinations.</p> + + +<p><span class='pagenum'><a name="Page_114" id="Page_114">[Pg 114]</a></span></p><p class="subchap"><i>II.—Restrictions in Marriage</i></p> + +<p>It is necessary to meet an objection that has been repeatedly urged +against the possible adoption of any system of eugenics, namely, that +human nature would never brook interference with the freedom of +marriage. But the question is how far have marriage restrictions proved +effective when sanctified by the religion of the time, by custom, and by +law. I appeal from armchair criticism to historical facts. It will be +found that, with scant exceptions, marriage customs are based on social +expediency and not on natural instincts. This we learn when we study the +fact of monogamy, and the severe prohibition of polygamy, in many times +and places, due not to any natural instinct against the practice, but to +consideration of the social well-being. We find the same when we study +endogamy, exogamy, Australian marriages, and the control of marriage by +taboo.</p> + +<p>The institution of marriage, as now sanctified by religion and +safeguarded by law in the more highly civilised nations, may not be +ideally perfect, nor may it be universally accepted in future times, but +it is the best that has hitherto been devised for the parties primarily +concerned, for their children, for home life, and for society. The +degree of kinship within which marriage is prohibited is, with one +exception, quite in accordance with modern sentiment, the exception +being the disallowal of marriage with the sister of a deceased wife, the +propriety of which is greatly disputed and need not be discussed here. +The marriage of a brother and sister would excite a feeling of loathing +among us that seems implanted by nature, but which, further inquiry will +show, has mainly arisen from tradition and custom.</p> + +<p>The evidence proves that there is no instinctive repugnance felt +universally by man to marriage within the prohibited degrees, but that +its present strength is mainly<span class='pagenum'><a name="Page_115" id="Page_115">[Pg 115]</a></span> due to what I may call immaterial +considerations. It is quite conceivable that a non-eugenic marriage +should hereafter excite no less loathing than that of a brother and +sister would do now.</p> + +<p>The dictates of religion in respect to the opposite duties of leading +celibate lives, and of continuing families, have been contradictory. In +many nations it is and has been considered a disgrace to bear no +children, and in other nations celibacy has been raised to the rank of a +virtue of the highest order. During the fifty or so generations that +have elapsed since the establishment of Christianity, the nunneries and +monasteries, and the celibate lives of Catholic priests, have had vast +social effects, how far for good and how far for evil need not be +discussed here. The point I wish to enforce is the potency, not only of +the religious sense in aiding or deterring marriage, but more especially +the influence and authority of ministers of religion in enforcing +celibacy. They have notoriously used it when aid has been invoked by +members of the family on grounds that are not religious at all, but +merely of family expediency. Thus at some times and in some Christian +nations, every girl who did not marry while still young was practically +compelled to enter a nunnery, from which escape was afterwards +impossible.</p> + +<p>It is easy to let the imagination run wild on the supposition of a +whole-hearted acceptance of eugenics as a national religion; that is, of +the thorough conviction by a nation that no worthier object exists for +man than the improvement of his own race, and when efforts as great as +those by which nunneries and monasteries were endowed and maintained +should be directed to fulfil an opposite purpose. I will not enter +further into this. Suffice it to say, that the history of conventual +life affords abundant evidence on a very large scale of the power of +religious authority in directing and withstanding the tendencies of +human nature towards freedom in marriage.</p> + +<p>Seven different forms of marriage restriction may be<span class='pagenum'><a name="Page_116" id="Page_116">[Pg 116]</a></span> cited to show what +is possible. They are monogamy, endogamy, exogamy, Australian marriages, +taboo, prohibited degrees, and celibacy. It can be shown under each of +these heads how powerful are the various combinations of immaterial +motives upon marriage selection, how they may all become hallowed by +religion, accepted as custom, and enforced by law. Persons who are born +under their various rules live under them without any objection. They +are unconscious of their restrictions, as we are unaware of the tension +of the atmosphere. The subservience of civilised races to their several +religious superstitions, customs, authority, and the rest, is frequently +as abject as that of barbarians.</p> + +<p>The same classes of motives that direct other races direct ours; so a +knowledge of their customs helps us to realise the wide range of what we +may ourselves hereafter adopt, for reasons as satisfactory to us in +those future times, as theirs are or were to them at the time when they +prevailed.</p> + + +<p class="subchap"><i>III.—Eugenic Qualities of Primary Importance</i></p> + +<p>The following is offered as a contribution to the art of justly +appraising the eugenic values of different qualities. It may fairly be +assumed that the presence of certain inborn traits is requisite before a +claim to eugenic rank can be justified, because these qualities are +needed to bring out the full values of such special faculties as broadly +distinguish philosophers, artists, financiers, soldiers, and other +representative classes. The method adopted for discovering the qualities +in question is to consider groups of individuals, and to compare the +qualities that distinguish such groups as flourish or prosper from +others of the same kind that decline or decay. This method has the +advantage of giving results more free from the possibility of bias than +those derived from examples of individual cases.</p> + +<p><span class='pagenum'><a name="Page_117" id="Page_117">[Pg 117]</a></span></p><p>In what follows I shall use the word "community" in its widest sense, +as including any group of persons who are connected by a common +interest—families, schools, clubs, sects, municipalities, nations, and +all intermediate social units. Whatever qualities increase the +prosperity of most or every one of these, will, as I hold, deserve a +place in the first rank of eugenic importance.</p> + +<p>Most of us have experience, either by direct observation or through +historical reading, of the working of several communities, and are +capable of forming a correct picture in our minds of the salient +characteristics of those that, on the one hand, are eminently +prosperous, and of those that, on the other hand, are as eminently +decadent. I have little doubt that the reader will agree with me that +the members of prospering communities are, as a rule, conspicuously +strenuous, and that those of decaying or decadent ones are conspicuously +slack. A prosperous community is distinguished by the alertness of its +members, by their busy occupations, by their taking pleasure in their +work, by their doing it thoroughly, and by an honest pride in their +community as a whole. The members of a decaying community are, for the +most part, languid and indolent; their very gestures are dawdling and +slouching, the opposite of smart. They shirk work when they can do so, +and scamp what they undertake. A prosperous community is remarkable for +the variety of the solid interests in which some or other of its members +are eagerly engaged, but the questions that agitate a decadent community +are for the most part of a frivolous order.</p> + +<p>Prosperous communities are also notable for enjoyment of life; for +though their members must work hard in order to procure the necessary +luxuries of an advanced civilisation, they are endowed with so large a +store of energy that, when their daily toil is over, enough of it +remains unexpended to allow them to pursue their special hobbies during +the remainder of the day. In a<span class='pagenum'><a name="Page_118" id="Page_118">[Pg 118]</a></span> decadent community the men tire easily, +and soon sink into drudgery; there is consequently much languor among +them, and little enjoyment of life.</p> + +<p>I have studied the causes of civic prosperity in various directions and +from many points of view, and the conclusion at which I have arrived is +emphatic, namely, that chief among those causes is a large capacity for +labour—mental, bodily, or both—combined with eagerness for work. The +course of evolution in animals shows that this view is correct in +general. The huge lizards, incapable of rapid action, unless it be brief +in duration and associated with long terms of repose, have been +supplanted by birds and mammals possessed of powers of long endurance. +These latter are so constituted as to require work, becoming restless +and suffering in health when precluded from exertion.</p> + +<p>We must not, however, overlook the fact that the influence of +circumstance on a community is a powerful factor in raising its tone. A +cause that catches the popular feeling will often rouse a potentially +capable nation from apathy into action. A good officer, backed by +adequate supplies of food and with funds for the regular payment of his +troops, will change a regiment even of ill-developed louts and hooligans +into a fairly smart and well-disciplined corps. But with better material +as a foundation, the influence of a favourable environment is +correspondingly increased, and is less liable to impairment whenever the +environment changes and becomes less propitious. Hence, it follows that +a sound mind and body, enlightened, I should add, with an intelligence +above the average, and combined with a natural capacity and zeal for +work, are essential elements in eugenics. For however famous a man may +become in other respects, he cannot, I think, be justly termed eugenic +if deficient in the qualities I have just named.</p> + +<p>Eugenists justly claim to be true philanthropists, or lovers of mankind, +and should bestir themselves in their<span class='pagenum'><a name="Page_119" id="Page_119">[Pg 119]</a></span> special province as eagerly as +the philanthropists, in the current and very restricted meaning of that +word, have done in theirs. They should interest themselves in such +families of civic worth as they come across, especially in those that +are large, making friends both with the parents and the children, and +showing themselves disposed to help to a reasonable degree, as +opportunity may offer, whenever help is really needful. They should +compare their own notes with those of others who are similarly engaged. +They should regard such families as an eager horticulturist regards beds +of seedlings of some rare variety of plant, but with an enthusiasm of a +far more patriotic kind. For, since it has been shown that about 10 per +cent. of the individuals born in one generation provide half the next +generation, large families that are also eugenic may prove of primary +importance to the nation and become its most valuable asset.</p> + + +<p class="subchap"><i>IV.—Practical Eugenics</i></p> + +<p>The following are some views of my own relating to that large province +of eugenics which is concerned with favouring the families of those who +are exceptionally fit for citizenship. Consequently, little or nothing +will here be said relating to what has been well termed by Dr. Saleeby +"negative" eugenics, namely, the hindrance of the marriages and the +production of offspring by the exceptionally unfit. The latter is +unquestionably the more pressing subject, but it will soon be forced on +the attention of the legislature by the recent report of the Royal +Commission on the Feeble-minded.</p> + +<p>Whatever scheme of action is proposed for adoption must be neither +Utopian nor extravagant, but accordant throughout with British sentiment +and practice.</p> + +<p>By "worth" I mean the civic worthiness, or the value to the state, of a +person. Speaking only for myself, if I had to classify persons according +to worth, I should<span class='pagenum'><a name="Page_120" id="Page_120">[Pg 120]</a></span> consider each of them under the three heads of +physique, ability and character, subject to the provision that +inferiority in any one of the three should outweigh superiority in the +other two. I rank physique first, because it is not only very valuable +in itself and allied to many other good qualities, but has the +additional merit of being easily rated. Ability I place second on +similar grounds, and character third, though in real importance it +stands first of all.</p> + +<p>The power of social opinion is apt to be underrated rather than +overrated. Like the atmosphere which we breathe and in which we move, +social opinion operates powerfully without our being conscious of its +weight. Everyone knows that governments, manners, and beliefs which were +thought to be right, decorous, and true at one period have been judged +wrong, indecorous, and false at another; and that views which we have +heard expressed by those in authority over us in early life tend to +become axiomatic and unchangeable in mature life.</p> + +<p>In circumscribed communities especially, social approval and disapproval +exert a potent force. Is it, then, I ask, too much to expect that when a +public opinion in favour of eugenics has once taken sure hold of such +communities, the result will be manifested in sundry and very effective +modes of action which are as yet untried?</p> + +<p>Speaking for myself only, I look forward to local eugenic action in +numerous directions, of which I will now specify one. It is the +accumulation of considerable funds to start young couples of "worthy" +qualities in their married life, and to assist them and their families +at critical times. The charitable gifts to those who are the reverse of +"worthy" are enormous in amount. I am not prepared to say how much of +this is judiciously spent, or in what ways, but merely quote the fact to +justify the inference that many persons who are willing to give freely +at the prompting of a sentiment based upon<span class='pagenum'><a name="Page_121" id="Page_121">[Pg 121]</a></span> compassion might be +persuaded to give largely also in response to the more virile desire of +promoting the natural gifts and the national efficiency of future +generations.</p> + + +<p class="subchap"><i>V.—Eugenics as a Factor in Religion</i></p> + +<p>Eugenics strengthen the sense of social duty in so many important +particulars that the conclusions derived from its study ought to find a +welcome home in every tolerant religion. It promotes a far-sighted +philanthropy, the acceptance of parentage as a serious responsibility, +and a higher conception of patriotism. The creed of eugenics is founded +upon the idea of evolution; not on a passive form of it, but on one that +can, to some extent, direct its own course.</p> + +<p>Purely passive, or what may be styled mechanical evolution displays the +awe-inspiring spectacle of a vast eddy of organic turmoil, originating +we know not how, and travelling we know not whither. It forms a +continuous whole, but it is moulded by blind and wasteful +processes—namely, by an extravagant production of raw material and the +ruthless rejection of all that is superfluous, through the blundering +steps of trial and error.</p> + +<p>The condition at each successive moment of this huge system, as it +issues from the already quiet past and is about to invade the still +undisturbed future, is one of violent internal commotion. Its elements +are in constant flux and change.</p> + +<p>Evolution is in any case a grand phantasmagoria, but it assumes an +infinitely more interesting aspect under the knowledge that the +intelligent action of the human will is, in some small measure, capable +of guiding its course. Man has the power of doing this largely so far as +the evolution of humanity is concerned; he has already affected the +quality and distribution of organic life so widely that the changes on +the surface of the earth, merely through his disforestings and +agriculture, would<span class='pagenum'><a name="Page_122" id="Page_122">[Pg 122]</a></span> be recognisable from a distance as great as that of +the moon.</p> + +<p>As regards the practical side of eugenics, we need not linger to reopen +the unending argument whether man possesses any creative power of will +at all, or whether his will is not also predetermined by blind forces or +by intelligent agencies behind the veil, and whether the belief that man +can act independently is more than a mere illusion.</p> + +<p>Eugenic belief extends the function of philanthropy to future +generations; it renders its action more pervading than hitherto, by +dealing with families and societies in their entirety, and it enforces +the importance of the marriage covenant by directing serious attention +to the probable quality of the future offspring. It sternly forbids all +forms of sentimental charity that are harmful to the race, while it +eagerly seeks opportunity for acts of personal kindness. It strongly +encourages love and interest in family and race. In brief, eugenics is a +virile creed, full of hopefulness, and appealing to many of the noblest +feelings of our nature.</p> + + +<hr /><p><span class='pagenum'><a name="Page_123" id="Page_123">[Pg 123]</a></span></p> +<h3>ERNST HAECKEL</h3> + +<p class="book"><big><a name="The_Evolution_of_Man" id="The_Evolution_of_Man"></a>The Evolution of Man</big></p> + +<div class="blockquot"><p>Ernst Haeckel, who was born in Potsdam, Germany, Feb. 16, 1834, +descends from a long line of lawyers and politicians. To his +father's annoyance, he turned to science, and graduated in +medicine. After a long tour in Italy in 1859, during which he +wavered between art and science, he decided for zoology, and made a +masterly study of a little-known group of sea-animalcules, the +Radiolaria. In 1861 he began to teach zoology at Jena University. +Darwin's "Origin of Species" had just been translated into German, +and he took up the defence of Darwinism against almost the whole of +his colleagues. His first large work on evolution, "General +Morphology," was published in 1866. He has since published +forty-two distinct works. He is not only a master of zoology, but +has a good command of botany and embryology. Haeckel's "Evolution +of Man" (Anthropogenie), is generally accepted as being his most +important production. Published in 1874, at a time when the theory +of natural evolution had few supporters in Germany, the work was +hailed with a storm of controversy, one celebrated critic declaring +that it was a blot on the escutcheon of Germany. From the hands of +English scientists, however, the treatise received a warm welcome. +Darwin said he would probably never have written his "Descent of +Man" had Haeckel published his work earlier.</p></div> + + +<p class="subchap"><i>I.—The Science of Man</i></p> + +<p><span class="smcap">The</span> natural history of mankind, or anthropology, must always excite the +most lively interest, and no part of the science is more attractive than +that which deals with the question of man's origin. In order to study +this with full profit, we must combine the results of two sciences, +ontogeny (or embryology) and phylogeny (the science of evolution). We do +this because we have now discovered that the forms through which the +embryo passes in its development correspond roughly to the series of +forms in its ancestral development. The correspondence is by no means +complete or precise, since the<span class='pagenum'><a name="Page_124" id="Page_124">[Pg 124]</a></span> embryonic life itself has been modified +in the course of time; but the general law is now very widely accepted. +I have called it "the biogenetic law," and will constantly appeal to it +in the course of this study.</p> + +<p>It is only in recent times that the two sciences have advanced +sufficiently to reveal the correspondence of the two series of forms. +Aristotle provided a good foundation for embryology, and made some +interesting discoveries, but no progress was made in the science for +2,000 years after him. Then the Reformation brought some liberty of +research, and in the seventeenth century several works were written on +embryology.</p> + +<p>For more than a hundred years the science was still hampered by the lack +of good microscopes. It was generally believed that all the organs of +the body existed, packed in a tiny point of space, in the germ. About +the middle of the eighteenth century, Caspar Friedrich Wolff discovered +the true development; but his work was ignored, and it was only fifty +years later that modern embryology began to work on the right line. K.E. +von Baer made it clear that the fertilised ovum divides into a group of +cells, and that the various organs of the body are developed from these +layers of cells, in the way I shall presently describe.</p> + +<p>The science of phylogeny, or, as it is popularly called, the evolution +of species, had an equally slow growth. On the ground of the Mosaic +narrative, no less than in view of the actual appearance of the living +world, the great naturalist Linné (1735) set up the dogma of the +unchangeability of species. Even when quite different remains of animals +were discovered by the advancing science of geology, they were forced +into the existing narrow framework of science by Cuvier. Sir Charles +Lyell completely undid the fallacious work of Cuvier, but in the +meantime the zoologists themselves were moving toward the doctrine of +evolution.</p> + +<p>Jean Lamarck made the first systematic attempt to<span class='pagenum'><a name="Page_125" id="Page_125">[Pg 125]</a></span> expound the theory in +his "Zoological Philosophy" (1809). He suggested that animals modified +their organs by use or disuse, and that the effect of this was +inherited. In the course of time these inherited modifications reached +such a pitch that the organism fell into a new "species." Goethe also +made some remarkable contributions to the science of evolution. But it +was reserved for Charles Darwin to win an enduring place in science for +the theory. "The Origin of Species" (1859) not only sustained it with a +wealth of positive knowledge which Lamarck did not command, but it +provided a more luminous explanation in the doctrine of natural +selection. Huxley (1863) followed with an application of the law to man, +and in 1866 I gave a comprehensive sketch of its application throughout +the whole animal world. In 1874 I published the first edition of the +present work.</p> + +<p>The doctrine of evolution is now a vital part of biology, and we might +accept the evolution of man as a special deduction from the general law. +Three great groups of evidence impose that law on us. The first group +consists of the facts of palæontology, or the fossil record of past +animal life. Imperfect as the record is, it shows us a broad divergence +of successively changing types from a simple common root, and in some +cases exhibits the complete transition from one type to another. The +next document is the evidence of comparative anatomy. This science +groups the forms of living animals in such a way that we seem to have +the same gradual divergence of types from simple common ancestors. In +particular, it discovers certain rudimentary organs in the higher +animals, which can only be understood as the shrunken relics of organs +that were once useful to a remote ancestor. Thus, man has still the +rudiment of the third eyelid of his shark-ancestor. The third document +is the evidence of embryology, which shows us the higher organism +substantially reproducing,<span class='pagenum'><a name="Page_126" id="Page_126">[Pg 126]</a></span> in its embryonic development, the long +series of ancestral forms.</p> + + +<p class="subchap"><i>II.—Man's Embryonic Development</i></p> + +<p>The first stage in the development of any animal is the tiny speck of +plasm, hardly visible to the naked eye, which we call the ovum, or +egg-cell. It is a single cell, recalling the earliest single-celled +ancestor of all animals. In its immature form it is not unlike certain +microscopic animalcules known as <i>amœboe</i>. In its mature form it is +about <span class="above">1</span>⁄<span class="below">125</span>th of an inch in diameter.</p> + +<p>When the male germ has blended with the female in the ovum, the new cell +slowly divides into two, with a very complicated division of the +material composing its nucleus. The two cells divide into four, the four +into eight, and so on until we have a round cluster of cells, something +like a blackberry in shape.</p> + +<p>This <i>morula</i>, as I have called it, reproduces the next stage in the +development of life. As all animals pass through it, our biogenetic law +forces us to see in it an ancestral stage; and in point of fact we have +animals of this type living in Nature to-day. The round cluster becomes +filled with fluid, and we have a hollow sphere of cells, which I call +the <i>blastula</i>. The corresponding early ancestor I name the <i>Blastæa</i>, +and again we find examples of it, like the <i>Volvox</i> of the ponds, in +Nature to-day.</p> + +<p>The next step is very important. The hollow sphere closes in on itself, +as when an india rubber ball is pressed into the form of a cup. We have +then a vase-shaped body with two layers of cells, an inner and an outer, +and an opening. The inner layer we call the entoderm, the outer the +ectoderm; and the "primitive mouth" is known as the blastopore. In the +higher animals a good deal of food-yolk is stored up in the germ, and so +the vase-shaped structure has been flattened and altered. It<span class='pagenum'><a name="Page_127" id="Page_127">[Pg 127]</a></span> has, +however, been shown that all embryos pass through this stage +(gastrulation), and we again infer the existence of a common ancestor of +that type—the <i>Gastræa</i>. The lowest group of many-celled animals—the +corals, jelly-fishes, and anemones—are essentially of that structure.</p> + +<p>The embryo now consists of two layers of cells, the "germ-layers," an +inner and outer. As the higher embryo develops, a third layer of cells +now pushes between the two. We may say, broadly, that from this middle +layer are developed most of the animal organs of the body; from the +internal germ-layer is developed the lining of the alimentary canal and +its dependent glands; from the outer layer are formed the skin and the +nervous system—which developed originally in the skin.</p> + +<p>The embryo of man and all the other higher animals now develops a +cavity, a pair of pouches, by the folding of the layer at the primitive +mouth. Sir E. Ray Lankester, and Professor Balfour, and other students, +traced this formation through the whole embryonic world, and we are +therefore again obliged to see in it a reminiscence of an ancestral +form—a primitive worm-like animal, of a type we shall see later. The +next step is the formation of the first trace of what will ultimately be +the backbone. It consists at first of a membraneous tube, formed by the +folding of the inner layer along the axis of the embryo-body. Later this +tube will become cartilage, and in the higher animals the cartilage will +give place to bone.</p> + +<p>The other organs of the body now gradually form from the germ-layers, +principally by the folding of the layers into tubes. A light area +appears on the surface of the germ. A streak or groove forms along its +axis, and becomes the nerve-cord running along the back. Cube-shaped +structures make their appearance on either side of it; these prove to be +the rudiments of the vertebræ—or separate bones of the backbone—and +gradually<span class='pagenum'><a name="Page_128" id="Page_128">[Pg 128]</a></span> close round the cord. The heart is at first merely a +spindle-shaped enlargement of the main ventral blood-vessel. The nose is +at first only a pair of depressions in the skin above the mouth.</p> + +<p>When the human embryo is only a quarter of an inch in length, it has +gill-clefts and gill-arches in the throat like a fish, and no limbs. The +heart—as yet with only the simple two-chambered structure of a fish's +heart—is up in the throat—as in the fish—and the principal arteries +run to the gill-slits. These structures never have any utility in man or +the other land-animals, though the embryo always has them for a time. +They point clearly to a fish ancestor.</p> + +<p>Later, they break up, the limbs sprout out like blunt fins at the sides, +and the long tail begins to decrease. By the twelfth week the human +frame is perfectly formed, though less than two inches long. Last of +all, it retains its resemblance to the ape. In the embryonic apparatus, +too, man closely resembles the higher ape.</p> + + +<p class="subchap"><i>III.—Our Ancestral Tree</i></p> + +<p>The series of forms which we thus trace in man's embryonic development +corresponds to the ancestral series which we would assign to man on the +evidence of palæontology and comparative anatomy. At one time, the +tracing of this ancestral series encountered a very serious check. When +we examined the groups of living animals, we found none that illustrated +or explained the passage from the non-backboned—invertebrate—to the +backboned—vertebrate—animals. This gap was filled some years ago by +the discovery of the lancelet—<i>Amphioxus</i>—and the young of the +sea-squirt—<i>Ascidia</i>. The lancelet has a slender rod of cartilage along +its back, and corresponds very closely with the ideal I have sketched of +our primitive backboned ancestor. It may be an offshoot from the same +group. The sea-squirt<span class='pagenum'><a name="Page_129" id="Page_129">[Pg 129]</a></span> further illustrates the origin of the backbone, +since it has a similar rod of cartilage in its youth, and loses it, by +degeneration, in its maturity.</p> + +<p>In this way the chief difficulty was overcome, and it was possible to +sketch the probable series of our ancestors. It must be well understood +that not only is the whole series conjectural, but no living animal must +be regarded as an ancestral form. The parental types have long been +extinct, and we may, at the most, use very conservative living types to +illustrate their nature, just as, in the matter of languages, German is +not the parent, but the cousin of Anglo-Saxon, or Greek of Latin. The +original parental languages are lost. But a language like Sanscrit +survives to give us a good idea of the type.</p> + +<p>The law of evolution is based on such a mass of evidence that we may +justly draw deductions from it, where the direct evidence is incomplete. +This is especially necessary in the early part of our ancestral tree, +because the fossil record quite fails us. For millions of years the +early soft-bodied animals left no trace in the primitive mud, which time +has hardened into rocks, and we are restricted to the evidence of +embryology and of comparative zoology. This suffices to give us a +general idea of the line of development.</p> + +<p>In nature to-day, one of the lowest animal forms is a tiny speck of +living plasm called the <i>amœba</i>. We have still more elementary forms, +such as the minute particles which make up the bluish film on damp +rocks, but they are of a vegetal character, or below it. They give us +some idea of the very earliest forms of life; minute living particles, +with no organs, down to the ten-thousandth part of an inch in diameter. +The amoeba represents the lowest animal, and, as we saw, the ovum in +many cases resembles an amoeba. We therefore take some such one-celled +creature as our first animal ancestor. Taking food in at all parts of +its surface, having no permanent organs of locomotion, and reproducing +by<span class='pagenum'><a name="Page_130" id="Page_130">[Pg 130]</a></span> merely splitting into two, it exhibits the lowest level of animal +life.</p> + +<p>The next step in development would be the clustering together of these +primitive microbes as they divided. This is actually the stage that +comes next in the development of the germ, and it is the next stage +upward in the existing animal world. We assume that these clusters of +microbes—or cells, as we will now call them—bent inward, as we saw the +embryo do, and became two-layered, cup-shaped organisms, with a hollow +interior (primitive stomach) and an aperture (primitive mouth). The +inner cells now do the work of digestion alone; the outer cells effect +locomotion, by means of lashes like oars, and are sensitive. This is, in +the main, the structure of the next great group of animals, the hydra, +coral, meduca, and anemone. They have remained at this level, though +they have developed, special organs for stinging their prey and bringing +the food into their mouths.</p> + +<p>Both zoology and the appearance of the embryo point to a worm-like +animal as the next stage. Constant swimming in the water would give the +animal a definite head, with special groups of nerve-cells, a definite +tail, and a two-sided or evenly-balanced body.</p> + +<p>We mean that those animals would be fittest to live, and multiply most, +which developed this organisation. Sense-organs would now appear in the +head, in the form of simple depressions, lined with sensitive cells, as +they do in the embryo; and a clump of nerve-cells within would represent +the primitive brain. In the vast and varied worm-group we find +illustrations of nearly every step in this process of evolution.</p> + +<p>The highest type of worm-like creature, the acorn-headed +worm—<i>Balanoglossus</i>—takes us an important step further. It has +gill-openings for breathing, and a cord of cartilage down its back. We +saw that the human embryo has a gill-apparatus, and that, comparing<span class='pagenum'><a name="Page_131" id="Page_131">[Pg 131]</a></span> the +lancelet and the sea-squirt, the backbone must have begun as a string of +cartilage-cells. We are now on firmer ground, for there is no doubt that +all the higher land-animals come from a fish ancestor. The shark, one of +the most primitive of fishes in organisation, probably best suggests +this ancestor to us. In fact, in the embryonic development of the human +face there is a clear suggestion of the shark.</p> + +<p>Up to this period the story of evolution had run its course in the sea. +The area of dry land was now increasing, and certain of the primitive +fishes adapted themselves to living on land. They walked on their fins, +and used their floating-bladders—large air-bladders in the fish, for +rising in the water—to breathe air. We not only have fishes of this +type in Australia to-day, but we have the fossil remains of similar +fishes in the Old Red Sandstone rocks. From mud-fish the amphibian would +naturally develop, as it did in the coal-forest period. Walking on the +fins would strengthen the main stem, the broad paddle would become +useless, and we should get in time the bony five-toed limb. We have many +of these giant salamander forms in the rocks.</p> + +<p>The reptile now evolved from the amphibian, and a vast reptile +population spread over the earth. From one of these early reptiles the +birds were evolved. Geology furnishes the missing link between the bird +and the reptile in the <i>Archæopteryx</i>, a bird with teeth, claws on its +wings, and a reptilian tail. From another primitive reptile the +important group of the mammals was evolved. We find what seem to be the +transitional types in the rocks of South Africa. The scales gave way to +tufts of hair, the heart evolved a fourth chamber, and thus supplied +purer blood (warm blood), the brain profited by the richer food, and the +mother began to suckle the young. We have still a primitive mammal of +this type in the duck-mole, or duck-billed platypus (<i>Ornithorhyncus</i>) +of Australia. There are grounds for thinking that<span class='pagenum'><a name="Page_132" id="Page_132">[Pg 132]</a></span> the next stage was an +opossum-like animal, and this led on to the lowest ape-like being, the +lemur. Judging from the fossil remains, the black lemur of Madagascar +best suggests this ancestor.</p> + +<p>The apes of the Old and New Worlds now diverged from this level, and +some branch of the former gave rise to the man-like apes and man. In +bodily structure and embryonic development the large apes come very +close to man, and two recent discoveries have put their +blood-relationship beyond question. One is that experiments in the +transfusion of blood show that the blood of the man-like ape and man +have the same action on the blood of lower animals. The other is that we +have discovered, in Java, several bones of a being which stands just +midway between the highest living ape and lowest living race of men. +This ape-man (<i>Pithecanthropus</i>) represents the last of our animal and +first of our human ancestors.</p> + + +<p class="subchap"><i>IV.—Evolution of Separate Organs</i></p> + +<p>So far, we have seen how the human body as a whole develops through a +long series of extinct ancestors. We may now take the various systems of +organs one by one, and, if we are careful to consult embryology as well +as zoology, we can trace the manner of their development. It is, in +accordance with our biogenetic law, the same in the embryo, as a rule, +as in the story of past evolution.</p> + +<p>We take first the nervous system. In the lowest animals, as in the early +stages of the embryo, there are no nerve-cells. In the embryo the +nerve-cells develop from the outer, or skin layer, of cells. This, +though strange as regards the human nervous system, is a correct +preservation of the primitive seat of the nerves. It was the surface of +the animal that needed to be sensitive in the primitive organism. Later, +when definite connecting<span class='pagenum'><a name="Page_133" id="Page_133">[Pg 133]</a></span> nerves were formed, only special points in the +surface, protected by coverings which did not interfere with the +sensitiveness, needed to be exposed, and the nerves transmitted the +impressions to the central brain.</p> + +<p>This development is found in the animal world to-day. In such animals as +the hydra we find the first crude beginning of unorganised nerve-cells. +In the jelly-fish we find nerve-cells clustered into definite sensitive +organs. In the lower worms we have the beginning of organs of smell and +vision. They are at first merely blind, sensitive pits in the skin, as +in the embryo. The ear has a peculiar origin. Up to the fish level there +is no power of hearing. There is merely a little stone rolling in a +sensitive bed, to warn the animal of its movement from side to side. In +the higher animals this evolves into the ear.</p> + +<p>The glands of the skin (sweat, fat, tears, etc.) appear at first as +blunt, simple ingrowths. The hair first appears in tufts, representing +the scales, from underneath which they were probably evolved. The thin +coat of hair on the human body to-day is an ancestral inheritance. This +is well shown by the direction of the hairs on the arm. As on the ape's +arm, both on the upper and lower arm, they grow toward the elbow. The +ape finds this useful in rain, using his arms like a thatched roof, and +on our arm this can only be a reminiscence of the habits of an ape +ancestor.</p> + +<p>We have seen how the spinal cord first appears as a tube in the axis of +the back, and the cartilaginous column closes round it. All bone appears +first as membrane, then cartilage, and finally ossifies. This is the +order both in past evolution and in present embryonic development. The +brain is at first a bulbous expansion of the spinal nerve-cord. It is at +first simple, but gradually, both in the scale of nature and in the +embryo, divides into five parts. One of these parts, the cerebrum, is +mainly connected with mental life. We find it <span class='pagenum'><a name="Page_134" id="Page_134">[Pg 134]</a></span>increasing in size, in +proportion to the animal's intelligence, until in man it comes to cover +the whole of the brain. When we remove it from the head of the mammal, +without killing the animal, we find all mental life suspended, and the +whole vitality used in vegetative functions.</p> + +<p>In the evolution of the bony system we find the same correspondence of +embryology and evolution. The main column is at first a rod of +cartilage. In time the separate cubes appear which are to form the +vertebræ of the flexible column. The skull develops in the same way. +Just as the brain is a specially modified part of the nerve-rod, the +skull is only a modified part of the vertebral column. The bones that +compose it are modified vertebræ, as Goethe long ago suspected. The +skull of the shark gives us a hint of the way in which the modification +took place, and the formation of the skull in the embryo confirms it.</p> + +<p>That adult man is devoid of that prolongation of the vertebral column +which we call a tail is not a distinctive peculiarity. The higher apes +are equally without it. We find, however, that the human embryo has a +long tail, much longer than the legs, when they are developing. At +times, moreover, children are born with tails—perfect tails, with +nerves and muscles, which they move briskly under emotion, and these +have to be amputated. The development of the limb from the fin offers no +serious difficulty to the osteologist. All the higher animals descend +from a five-toed ancestor. The whale has taken again to the water, and +reconverted its limb into a paddle. The bones of the front feet still +remain under the flesh. Animals of the horse type have had the central +toe strengthened, for running purposes, at the expense of the rest. The +serpent has lost its limbs from disuse, but in the python a rudimentary +limb-bone is still preserved.</p> + +<p>The alimentary system, blood-vessel system, and <span class='pagenum'><a name="Page_135" id="Page_135">[Pg 135]</a></span>reproductive system +have been evolved gradually in the same way. The stomach is at first the +whole cavity in the animal. Later it becomes a straight, simple tube, +strengthened by a gullet in front. The liver is an outgrowth from this +tube; the stomach proper is a bulbous expansion of its central part, +later provided with a valve. The kidneys are at first simple channels in +the skin for drainage, then closed tubes, which branch out more and +more, and then gather into our compact kidneys. We thus see that the +building up of the human body from a single cell is a substantial +epitome of the long story of evolution, which occupied many millions of +years. We find man bearing in his body to-day traces of organs which +were useful to a remote ancestor, but of no advantage, and often a +source of mischief to himself. We learn that the origin of man, instead +of being placed a few thousand years ago, must be traced back to the +point where, hundreds of thousands of years ago, he diverged from his +ape-cousins, though he retains to-day the plainest traces of that +relationship. Body and mind—for the development of mind follows with +the utmost precision on the development of brain—he is the culmination +of a long process of development. His spirit is a form of energy +inseparably bound up with the substance of his body. His evolution has +been controlled by the same "eternal, iron laws" as the development of +any other body—the laws of heredity and adaptation.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_136" id="Page_136">[Pg 136]</a></span></p> +<h3>WILLIAM HARVEY</h3> + +<p class="book"><big><a name="On_the_Motion_of_the_Heart_and_Blood" id="On_the_Motion_of_the_Heart_and_Blood"></a>On the Motion of the Heart and Blood</big></p> + +<div class="blockquot"><p>William Harvey, the discoverer of the circulation of the blood, was +born at Folkestone, England, on April 1, 1578. After graduating +from Caius College, Cambridge, he studied at Padua, where he had +the celebrated anatomist, Fabricius of Aquapendente, for his +master. In 1615 he was elected Lumleian lecturer at the College of +Physicians, and three years later was appointed physician +extraordinary to King James I. In 1628, twelve years after his +first statement of it in his lectures, he published at Frankfurt, +in Latin, "An Anatomical Disquisition on the Motion of the Heart +and Blood," in which he maintained that there is a circulation of +the blood. Moreover, he distinguished between the pulmonary +circulation, from the right side of the heart to the left through +the lungs, and the systemic circulation from the left side of the +heart to the right through the rest of the body. Further, he +maintained that it was the office of the heart to maintain this +circulation by its alternate <i>diastole</i> (expansion) and <i>systole</i> +(contraction) throughout life. This discovery was, says Sir John +Simon, the most important ever made in physiological science. It is +recorded that after his publication of it Harvey lost most of his +practice. Harvey died on June 3, 1657.</p></div> + + +<p class="subchap"><i>I.—Motions of the Heart in Living Animals</i></p> + +<p><span class="smcap">When</span> first I gave my mind to vivisections as a means of discovering the +motions and uses of the heart, I found the task so truly arduous that I +was almost tempted to think, with Fracastorius, that the motion of the +heart was only to be comprehended by God. For I could neither rightly +perceive at first when the systole and when the diastole took place, nor +when and where dilation and contraction occurred, by reason of the +rapidity of the motion, which, in many animals, is accomplished in the +twinkling of an eye, coming and going like a flash of lightning. At +length it appeared that these things happen together or at the same +instant: the tension of<span class='pagenum'><a name="Page_137" id="Page_137">[Pg 137]</a></span> the heart, the pulse of its apex, which is felt +externally by its striking against the chest, the thickening of its +walls, and the forcible expulsion of the blood it contains by the +constriction of its ventricles.</p> + +<p>Hence the very opposite of the opinions commonly received appears to be +true; inasmuch as it is generally believed that when the heart strikes +the breast and the pulse is felt without, the heart is dilated in its +ventricles and is filled with blood. But the contrary of this is the +fact; that is to say, the heart is in the act of contracting and being +emptied. Whence the motion, which is generally regarded as the diastole +of the heart, is in truth its systole. And in like manner the intrinsic +motion of the heart is not the diastole but the systole; neither is it +in the diastole that the heart grows firm and tense, but in the systole; +for then alone when tense is it moved and made vigorous. When it acts +and becomes tense the blood is expelled; when it relaxes and sinks +together it receives the blood in the manner and wise which will by and +by be explained.</p> + +<p>From divers facts it is also manifest, in opposition to commonly +received opinions, that the diastole of the arteries corresponds with +the time of the heart's systole; and that the arteries are filled and +distended by the blood forced into them by the contraction of the +ventricles. It is in virtue of one and the same cause, therefore, that +all the arteries of the body pulsate, <i>viz.</i>, the contraction of the +left ventricle in the same way as the pulmonary artery pulsates by the +contraction of the right ventricle.</p> + +<p>I am persuaded it will be found that the motion of the heart is as +follows. First of all, the auricle contracts and throws the blood into +the ventricle, which, being filled, the heart raises itself straightway, +makes all its fibres tense, contracts the ventricles and performs a +beat, by which beat it immediately sends the blood supplied to it by the +auricle into the arteries; the right ventricle<span class='pagenum'><a name="Page_138" id="Page_138">[Pg 138]</a></span> sending its charge into +the lungs by the vessel called <i>vena arteriosa</i>, but which, in structure +and function, and all things else, is an artery; the left ventricle +sending its charge into the aorta, and through this by the arteries to +the body at large.</p> + +<p>The grand cause of hesitation and error in this subject appears to me to +have been the intimate connection between the heart and the lungs. When +men saw both the pulmonary artery and the pulmonary veins losing +themselves in the lungs, of course it became a puzzle to them to know +how the right ventricle should distribute the blood to the body, or the +left draw it from the <i>venæ cavæ</i>. Or they have hesitated because they +did not perceive the route by which the blood is transferred from the +veins to the arteries, in consequence of the intimate connection between +the heart and lungs. And that this difficulty puzzled anatomists not a +little when in their dissections they found the pulmonary artery and +left ventricle full of black and clotted blood, plainly appears when +they felt themselves compelled to affirm that the blood made its way +from the right to the left ventricle by sweating through the septum of +the heart.</p> + +<p>Had anatomists only been as conversant with the dissection of the lower +animals as they are with that of the human body, the matters that have +hitherto kept them in perplexity of doubt would, in my opinion, have met +them freed from every kind of difficulty. And first in fishes, in which +the heart consists of but a single ventricle, they having no lungs, the +thing is sufficiently manifest. Here the sac, which is situated at the +base of the heart, and is the part analogous to the auricle in man, +plainly throws the blood into the heart, and the heart in its turn +conspicuously transmits it by a pipe or artery, or vessel analogous to +an artery; these are facts which are confirmed by simple ocular +experiment. I have seen, farther, that the same thing obtained most +obviously.</p> + +<p>And since we find that in the greater number of <span class='pagenum'><a name="Page_139" id="Page_139">[Pg 139]</a></span>animals, in all indeed +at a certain period of their existence, the channels for the +transmission of the blood through the heart are so conspicuous, we have +still to inquire wherefore in some creatures—those, namely, that have +warm blood and that have attained to the adult age, man among the +number—we should not conclude that the same thing is accomplished +through the substance of the lungs, which, in the embryo, and at a time +when the functions of these organs is in abeyance, Nature effects by +direct passages, and which indeed she seems compelled to adopt through +want of a passage by the lungs; or wherefore it should be better (for +Nature always does that which is best) that she should close up the +various open routes which she had formerly made use of in the embryo, +and still uses in all other animals; not only opening up no new apparent +channels for the passage of the blood therefore, but even entirely +shutting up those which formerly existed in the embryos of those animals +that have lungs. For while the lungs are yet in a state of inaction, +Nature uses the two ventricles of the heart as if they formed but one +for the transmission of the blood. The condition of the embryos of those +animals which have lungs is the same as that of those animals which have +no lungs.</p> + +<p>Thus, by studying the structure of the animals who are nearer to and +further from ourselves in their modes of life and in the construction of +their bodies, we can prepare ourselves to understand the nature of the +pulmonary circulation in ourselves, and of the systemic circulation +also.</p> + + +<p class="subchap"><i>II.—Systemic Circulation</i></p> + +<p>What remains to be said is of so novel and unheard of a character that I +not only fear injury to myself from the envy of a few, but I tremble +lest I have mankind at large for my enemies, so much do wont and custom +that<span class='pagenum'><a name="Page_140" id="Page_140">[Pg 140]</a></span> become as another nature, and doctrine once sown that hath struck +deep root, and respect for antiquity, influence all men.</p> + +<p>And, sooth to say, when I surveyed my mass of evidence, whether derived +from vivisections and my previous reflections on them, or from the +ventricles of the heart and the vessels that enter into and issue from +them, the symmetry and size of these conduits—for Nature, doing nothing +in vain, would never have given them so large a relative size without a +purpose; or from the arrangement and intimate structure of the valves in +particular and of the many other parts of the heart in general, with +many things besides; and frequently and seriously bethought me and long +revolved in my mind what might be the quantity of blood which was +transmitted, in how short a time its passage might be effected and the +like; and not finding it possible that this could be supplied by the +juices of the ingested aliment without the veins on the one hand +becoming drained, and the arteries on the other getting ruptured through +the excessive charge of blood, unless the blood should somehow find its +way from the arteries into the veins, and so return to the right side of +the heart; when I say, I surveyed all this evidence, I began to think +whether there might not be <i>a motion as it were in a circle</i>.</p> + +<p>Now this I afterwards found to be true; and I finally saw that the +blood, forced by the action of the left ventricle into the arteries, was +distributed to the body at large, and its several parts, in the same +manner as it is sent through the lungs, impelled by the right ventricle +into the pulmonary artery; and that it then passed through the veins and +along the <i>vena cava</i>, and so round to the left ventricle in the manner +already indicated; which motion we may be allowed to call circular, in +the same way as Aristotle says that the air and the rain emulate the +circular motion of the superior bodies. For the moist earth, warmed by +the sun, evaporates; the<span class='pagenum'><a name="Page_141" id="Page_141">[Pg 141]</a></span> vapours drawn upwards are condensed, and +descending in the form of rain moisten the earth again. And by this +arrangement are generations of living things produced; and in like +manner, too, are tempests and meteors engendered by the circular motion +of the sun.</p> + +<p>And so in all likelihood does it come to pass in the body through the +motion of the blood. The various parts are nourished, cherished, +quickened by the warmer, more perfect, vaporous, spirituous, and, as I +may say, alimentive blood; which, on the contrary, in contact with these +parts becomes cooled, coagulated, and, so to speak, effete; whence it +returns to its sovereign, the heart, as if to its source, or to the +inmost home of the body, there to recover its state of excellence or +perfection. Here it resumes its due fluidity, and receives an infusion +of natural heat—powerful, fervid, a kind of treasury of life—and is +impregnated with spirits and, it might be said, with balsam; and thence +it is again dispersed. And all this depends upon the motion and action +of the heart.</p> + + +<p class="subchap"><i>Confirmations of the Theory</i></p> + +<p>Three points present themselves for confirmation, which, being +established, I conceive that the truth I contend for will follow +necessarily and appear as a thing obvious to all.</p> + +<p>The first point is this. The blood is incessantly transmitted by the +action of the heart from the <i>vena cava</i> to the arteries in such +quantity that it cannot be supplied from the ingesta, and in such wise +that the whole mass must very quickly pass through the organ.</p> + +<p>Let us assume the quantity of blood which the left ventricle of the +heart will contain when distended to be, say, two ounces (in the dead +body I have found it to contain upwards of two ounces); and let us +suppose, as approaching the truth, that the fourth part of its charge<span class='pagenum'><a name="Page_142" id="Page_142">[Pg 142]</a></span> +is thrown into the artery at each contraction. Now, in the course of +half an hour the heart will have made more than one thousand beats. +Multiplying the number of drachms propelled by the number of pulses, we +shall have one thousand half-ounces sent from this organ into the +artery; a larger quantity than is contained in the whole body. This +truth, indeed, presents itself obviously before us when we consider what +happens in the dissection of living animals. The great artery need not +be divided, but a very small branch only (as Galen even proves in regard +to man), to have the whole of the blood in the body, as well that of the +veins as of the arteries, drained away in the course of no long +time—some half hour or less.</p> + +<p>The second point is this. The blood, under the influence of the arterial +pulse, enters, and is impelled in a continuous, equable, and incessant +stream through every part and member of the body in much larger quantity +than were sufficient for nutrition, or than the whole mass of fluids +could supply.</p> + +<p>I have here to cite certain experiments. Ligatures are either very tight +or of middling tightness. A ligature I designate as tight, or perfect, +when it is drawn so close about an extremity that no vessel can be felt +pulsating beyond it. Such ligatures are employed in the removal of +tumours; and in these cases, all afflux of nutriment and heat being +prevented by the ligature, we see the tumours dwindle and die, and +finally drop off. Now let anyone make an experiment upon the arm of a +man, either using such a fillet as is employed in bloodletting, or +grasping the limb tightly with his hand; let a ligature be thrown about +the extremity and drawn as tightly as can be borne. It will first be +perceived that beyond the ligature the arteries do not pulsate, while +above it the artery begins to rise higher at each diastole and to swell +with a kind of tide as it strove to break through and overcome the +obstacle to its current.</p> + +<p><span class='pagenum'><a name="Page_143" id="Page_143">[Pg 143]</a></span></p><p>Then let the ligature be brought to that state of middling tightness +which is used in bleeding, and it will be seen that the hand and arm +will instantly become deeply suffused and extended, and the veins show +themselves tumid and knotted. Which is as much as to say that when the +arteries pulsate the blood is flowing through them, but where they do +not pulsate they cease from transmitting anything. The veins again being +compressed, nothing can flow through them; the certain indication of +which is that below the ligature they are much more tumid than above it.</p> + +<p>Whence is this blood? It must needs arrive by the arteries. For that it +cannot flow in by the veins appears from the fact that the blood cannot +be forced towards the heart unless the ligature be removed. Further, +when we see the veins below the ligature instantly swell up and become +gorged when from extreme tightness it is somewhat relaxed, the arteries +meanwhile continuing unaffected, this is an obvious indication that the +blood passes from the arteries into the veins, and not from the veins +into the arteries, and that there is either an anastomosis of the two +orders of vessels, or pores in the flesh and solid parts generally that +are permeable to the blood.</p> + +<p>And now we understand wherefore in phlebotomy we apply our fillet above +the part that is punctured, not below it. Did the flow come from above, +not from below, the bandage in this case would not only be of no +service, but would prove a positive hindrance. And further, if we +calculate how many ounces flow through one arm or how many pass in +twenty or thirty pulsations under the medium ligature, we shall perceive +that a circulation is absolutely necessary, seeing that the quantity +cannot be supplied immediately from the ingesta, and is vastly more than +can be requisite for the mere nutrition of the parts.</p> + +<p>And the third point to be confirmed is this. That the<span class='pagenum'><a name="Page_144" id="Page_144">[Pg 144]</a></span> veins return this +blood to the heart incessantly from all parts and members of the body.</p> + +<p>This position will be made sufficiently clear from the valves which are +found in the cavities of the veins themselves, from the uses of these, +and from experiments cognisable by the senses. The celebrated Hieronymus +Fabricius, of Aquapendente, first gave representations of the valves in +the veins, which consist of raised or loose portions of the inner +membranes of these vessels of extreme delicacy and a sigmoid, or +semi-lunar shape. Their office is by no means explained when we are told +that it is to hinder the blood, by its weight, from flowing into +inferior parts; for the edges of the valves in the jugular veins hang +downwards, and are so contrived that they prevent the blood from rising +upwards.</p> + +<p>The valves, in a word, do not invariably look upwards, but always +towards the trunks of the veins—towards the seat of the heart. They are +solely made and instituted lest, instead of advancing from the extreme +to the central parts of the body, the blood should rather proceed along +the veins from the centre to the extremities; but the delicate valves, +while they readily open in the right direction, entirely prevent all +such contrary motion, being so situated and arranged that if anything +escapes, or is less perfectly obstructed by the flaps of the one above, +the fluid passing, as it were, by the chinks between the flaps, it is +immediately received on the convexity of the one beneath, which is +placed transversely with reference to the former, and so is effectually +hindered from getting any farther. And this I have frequently +experienced in my dissections of veins. If I attempted to pass a probe +from the trunk of the veins into one of the smaller branches, whatever +care I took I found it impossible to introduce it far any way by reason +of the valves; whilst, on the contrary, it was most easy to push it +along in the opposite direction, from<span class='pagenum'><a name="Page_145" id="Page_145">[Pg 145]</a></span> without inwards, or from the +branches towards the trunks and roots.</p> + +<p>And now I may be allowed to give in brief my view of the circulation of +the blood, and to propose it for general adoption.</p> + + +<p class="subchap"><i>The Conclusion</i></p> + +<p>Since all things, both argument and ocular demonstration, show that the +blood passes through the lungs and heart by the action of the +ventricles; and is sent for distribution to all parts of the body, where +it makes its way into the veins and pores of the flesh; and then flows +by the veins from the circumference on every side to the centre, from +the lesser to the greater veins; and is by them finally discharged into +the <i>vena cava</i> and right auricle of the heart, and this in such a +quantity or in such a flux and reflux, thither by the arteries, hither +by the veins, as cannot possibly be supplied by the ingesta, and is much +greater than can be required for mere purposes of nutrition; therefore, +it is absolutely necessary to conclude that the blood in the animal body +is impelled in a circle and is in a state of ceaseless motion; and that +this is the act, or function, which the heart performs by means of its +pulse, and that it is the sole and only end of the motion and +contraction of the heart. For it would be very difficult to explain in +any other way to what purpose all is constructed and arranged as we have +seen it to be.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_146" id="Page_146">[Pg 146]</a></span></p> +<h3>SIR JOHN HERSCHEL</h3> + +<p class="book"><big><a name="Outlines_of_Astronomy" id="Outlines_of_Astronomy"></a>Outlines of Astronomy</big></p> + +<div class="blockquot"><p>Sir John Frederick William Herschel, only child—and, as an +astronomer, almost the only rival—of Sir William Herschel, was +born at Slough, in Ireland, on March 7, 1792. At first privately +educated, in 1813 he graduated from St. John's College, Cambridge, +as senior wrangler and first Smith's prizeman. He chose the law as +his profession; but in 1816 reported that, under his father's +direction, he was going "to take up stargazing." He then began a +re-examination of his father's double stars. In 1825 he wrote that +he was going to take nebulæ under his especial charge. He embarked +in 1833 with his family for the Cape; and his work at Feldhausen, +six miles from Cape Town, marked the beginning of southern sidereal +astronomy. The result of his four years' work there was published +in 1847. From 1855 he devoted himself at Collingwood to the +collection and revival of his father's and his own labours. His +"Outlines of Astronomy," published in 1849, and founded on an +earlier "Treatise on Astronomy" of 1833, was an outstanding +success. Herschel's long and happy life, every day of which added +its share to his scientific services, came to an end on May 11, +1871.</p></div> + + +<p class="subchap"><i>I.—The Wonders of the Milky Way</i></p> + +<p><span class="smcap">There</span> is no science which draws more largely than does astronomy on that +intellectual liberality which is ready to adopt whatever is demonstrated +or concede whatever is rendered highly probable, however new and +uncommon the points of view may be in which objects the most familiar +may thereby become placed. Almost all its conclusions stand in open and +striking contradiction with those of superficial and vulgar observation, +and with what appears to everyone the most positive evidence of his +senses.</p> + +<p>There is hardly anything which sets in a stronger light the inherent +power of truth over the mind of man, when opposed by no motives of +interest or passion, than<span class='pagenum'><a name="Page_147" id="Page_147">[Pg 147]</a></span> the perfect readiness with which all its +conclusions are assented to as soon as their evidence is clearly +apprehended, and the tenacious hold they acquire over our belief when +once admitted.</p> + +<p>If the comparison of the apparent magnitude of the stars with their +number leads to no immediately obvious conclusion, it is otherwise when +we view them in connection with their local distribution over the +heavens. If indeed we confine ourselves to the three or four brightest +classes, we shall find them distributed with a considerable approach to +impartiality over the sphere; a marked preference, however, being +observable, especially in the southern hemisphere, to a zone or belt +passing through <i>epsilon</i> Orionis and <i>alpha</i> Crucis. But if we take in +the whole amount visible to the naked eye we shall perceive a great +increase of numbers as we approach the borders of the Milky Way. And +when we come to telescopic magnitudes we find them crowded beyond +imagination along the extent of that circle and of the branches which it +sends off from it; so that, in fact, its whole light is composed of +nothing but stars of every magnitude from such as are visible to the +naked eye down to the smallest points of light perceptible with the best +telescopes.</p> + +<p>These phenomena agree with the supposition that the stars of our +firmament, instead of being scattered indifferently in all directions +through space, form a stratum of which the thickness is small in +comparison with its length and breadth; and in which the earth occupies +a place somewhere about the middle of its thickness and near the point +where it subdivides into two principal laminæ inclined at a small angle +to each other. For it is certain that to an eye so situated the apparent +density of the stars, supposing them pretty equally scattered through +the space they occupy, would be least in the direction of the visual ray +perpendicular to the lamina, and greatest in that of its breadth; +increasing rapidly<span class='pagenum'><a name="Page_148" id="Page_148">[Pg 148]</a></span> in passing from one to the other direction, just as +we see a slight haze in the atmosphere thickening into a decided +fog-bank near the horizon by the rapid increase of the mere length of +the visual ray.</p> + +<p>Such is the view of the construction of the starry firmament taken by +Sir William Herschel, whose powerful telescopes first effected a +complete analysis of this wonderful zone, and demonstrated the fact of +its entirely consisting of stars.</p> + +<p>So crowded are they in some parts of it that by counting the stars in a +single field of his telescope he was led to conclude that 50,000 had +passed under his review in a zone two degrees in breadth during a single +hour's observation. The immense distances at which the remoter regions +must be situated will sufficiently account for the vast predominance of +small magnitudes which are observed in it.</p> + +<p>The process of gauging the heavens was devised by Sir William Herschel +for this purpose. It consisted simply in counting the stars of all +magnitudes which occur in single fields of view, of fifteen minutes in +diameter, visible through a reflecting telescope of 18 inches aperture, +and 20 feet focal length, with a magnifying power of 180 degrees, the +points of observation being very numerous and taken indiscriminately in +every part of the surface of the sphere visible in our latitudes.</p> + +<p>On a comparison of many hundred such "gauges," or local enumerations, it +appears that the density of starlight (or the number of stars existing +on an average of several such enumerations in any one immediate +neighbourhood) is least in the pole of the Galactic circle [<i>i.e.</i>, the +great circle to which the course of the Milky Way most nearly conforms: +<i>gala</i> = milk], and increases on all sides down to the Milky Way itself, +where it attains its maximum. The progressive rate of increase in +proceeding from the pole is at first slow, but becomes more<span class='pagenum'><a name="Page_149" id="Page_149">[Pg 149]</a></span> and more +rapid as we approach the plane of that circle, according to a law from +which it appears that the mean density of the stars in the galactic +circle exceeds, in a ratio of very nearly 30 to 1, that in its pole, and +in a proportion of more than 4 to 1 that in a direction 15 degrees +inclined to its plane.</p> + +<p>As we ascend from the galactic plane we perceive that the density +decreases with great rapidity. So far we can perceive no flaw in this +reasoning if only it be granted (1) that the level planes are continuous +and of equal density throughout; and (2) that an absolute and definite +limit is set to telescopic vision, beyond which, if stars exist, they +elude our sight, and are to us as if they existed not. It would appear +that, with an almost exactly similar law of apparent density in the two +hemispheres, the southern were somewhat richer in stars than the +northern, which may arise from our situation not being precisely in the +middle of its thickness, but somewhat nearer to its northern surface.</p> + + +<p class="subchap"><i>II.—Penetrating Infinite Space</i></p> + +<p>When examined with powerful telescopes, the constitution of this +wonderful zone is found to be no less various than its aspect to the +naked eye is irregular. In some regions the stars of which it is +composed are scattered with remarkable uniformity over immense tracts, +while in others the irregularity of their distribution is quite as +striking, exhibiting a rapid succession of closely clustering rich +patches separated by comparatively poor intervals, and indeed in some +instances absolutely dark and <i>completely</i> void of any star even of the +smallest telescopic magnitude. In some places not more than 40 or 50 +stars on an average occur in a "gauge" field of 15 minutes, while in +others a similar average gives a result of 400 or 500.</p> + +<p>Nor is less variety observable in the character of its<span class='pagenum'><a name="Page_150" id="Page_150">[Pg 150]</a></span> different +regions in respect of the magnitude of the stars they exhibit, and the +proportional numbers of the larger and smaller magnitudes associated +together, than in respect of their aggregate numbers. In some, for +instance, extremely minute stars, though never altogether wanting, occur +in numbers so moderate as to lead us irresistibly to the conclusion that +in these regions we are <i>fairly through</i> the starry stratum, since it is +impossible otherwise (supposing their light not intercepted) that the +numbers of the smaller magnitudes should not go on increasing <i>ad +infinitum</i>.</p> + +<p>In such cases, moreover, the ground of the heavens, as seen between the +stars, is for the most part perfectly dark, which again would not be the +case if innumerable multitudes of stars, too minute to be individually +discernible, existed beyond. In other regions we are presented with the +phenomenon of an almost uniform degree of brightness of the individual +stars, accompanied with a very even distribution of them over the ground +of the heavens, both the larger and smaller magnitudes being strikingly +deficient. In such cases it is equally impossible not to perceive that +we are looking through a sheet of stars nearly of a size and of no great +thickness compared with the distance which separates them from us. Were +it otherwise we should be driven to suppose the more distant stars were +uniformly the larger, so as to compensate by their intrinsic brightness +for their greater distance, a supposition contrary to all probability.</p> + +<p>In others again, and that not infrequently, we are presented with a +double phenomenon of the same kind—<i>viz.</i>, a tissue, as it were, of +large stars spread over another of very small ones, the intermediate +magnitudes being wanting, and the conclusion here seems equally evident +that in such cases we look through two sidereal sheets separated by a +starless interval.</p> + +<p>Throughout by far the larger portion of the extent of<span class='pagenum'><a name="Page_151" id="Page_151">[Pg 151]</a></span> the Milky Way in +both hemispheres the general blackness of the ground of the heavens on +which its stars are projected, and the absence of that innumerable +multitude and excessive crowding of the smallest visible magnitudes, and +of glare produced by the aggregate light of multitudes too small to +affect the eye singly, which the contrary supposition would appear to +necessitate, must, we think, be considered unequivocal indications that +its dimensions, <i>in directions where those conditions obtain</i>, are not +only not infinite, but that the space-penetrating power of our +telescopes suffices fairly to pierce through and beyond it.</p> + +<p>It is but right, however, to warn our readers that this conclusion has +been controverted, and that by an authority not lightly to be put aside, +on the ground of certain views taken by Olbers as to a defect of perfect +transparency in the celestial spaces, in virtue of which the light of +the more distant stars is enfeebled more than in proportion to their +distance. The extinction of light thus originating proceeding in +geometrical ratio, while the distance increases in arithmetical, a +limit, it is argued, is placed to the space-penetrating power of +telescopes far within that which distance alone, apart from such +obscuration, would assign.</p> + +<p>It must suffice here to observe that the objection alluded to, if +applicable to any, is equally so to every part of the galaxy. We are not +at liberty to argue that at one part of its circumference our view is +limited by this sort of cosmical veil, which extinguishes the smaller +magnitudes, cuts off the nebulous light of distant masses, and closes +our view in impenetrable darkness; while at another we are compelled, by +the clearest evidence telescopes can afford, to believe that star-strewn +vistas <i>lie open</i>, exhausting their powers and stretching out beyond +their utmost reach, as is proved by that very phenomenon which the +existence of such a veil would render impossible—<i>viz.</i>, infinite +increase of number and diminution<span class='pagenum'><a name="Page_152" id="Page_152">[Pg 152]</a></span> of magnitude, terminating in complete +irresolvable nebulosity.</p> + +<p>Such is, in effect, the spectacle afforded by a very large portion of +the Milky Way in that interesting region near its point of bifurcation +in Scorpio, where, through the hollows and deep recesses of its +complicated structure, we behold what has all the appearance of a wide +and indefinitely prolonged area strewed over with discontinuous masses +and clouds of stars, which the telescope at last refuses to analyse. +Whatever other conclusions we may draw, this must anyhow be regarded as +the direction of the greatest linear extension of the ground-plan of the +galaxy. And it would appear to follow also that in those regions where +that zone is clearly resolved into stars well separated and <i>seen +projected on a black ground</i>, and where, by consequence, it is certain, +if the foregoing views be correct, that we look out beyond them into +space, the smallest visible stars appear as such not by reason of +excessive distance, but of inferiority of size or brightness.</p> + + +<p class="subchap"><i>III.—Variable, Temporary and Binary Stars</i></p> + +<p>Wherever we can trace the law of periodicity we are strongly impressed +with the idea of rotatory or orbitual motion. Among the stars are +several which, though in no way distinguishable from others by any +apparent change of place, nor by any difference of appearance in +telescopes, yet undergo a more or less regular periodical increase and +diminution of lustre, involving in one or two cases a complete +extinction and revival. These are called periodic stars. The longest +known, and one of the most remarkable, is the star <i>Omicron</i> in the +constellation Cetus (sometimes called Mira Ceti), which was first +noticed as variable by Fabricius in 1596. It appears about twelve times +in eleven years, remains at its greatest brightness about a fortnight, +being then on some occasions<span class='pagenum'><a name="Page_153" id="Page_153">[Pg 153]</a></span> equal to a large star of the second +magnitude, decreases during about three months, till it becomes +completely invisible to the naked eye, in which state it remains about +five months, and continues increasing during the remainder of its +period. Such is the general course of its phases. But the mean period +above assigned would appear to be subject to a cyclical fluctuation +embracing eighty-eight such periods, and having the effect of gradually +lengthening and shortening alternately those intervals to the extent of +twenty-five days one way and the other. The irregularities in the degree +of brightness attained at the maximum are also periodical.</p> + +<p>Such irregularities prepare us for other phenomena of stellar variation +which have hitherto been reduced to no law of periodicity—the phenomena +of temporary stars which have appeared from time to time in different +parts of the heavens blazing forth with extraordinary lustre, and after +remaining awhile, apparently immovable, have died away and left no +trace. In the years 945, 1264, and 1572 brilliant stars appeared in the +region of the heavens between Cepheus and Cassiopeia; and we may suspect +them, with Goodricke, to be one and the same star with a period of 312, +or perhaps 156 years. The appearance of the star of 1572 was so sudden +that Tycho Brahe, a celebrated Dutch astronomer, returning one evening +from his laboratory to his dwellinghouse, was surprised to find a group +of country people gazing at a star which he was sure did not exist half +an hour before. This was the star in question. It was then as bright as +Sirius, and continued to increase till it surpassed Jupiter when +brightest, and was visible at midday. It began to diminish in December +of the same year, and in March 1574 had entirely disappeared.</p> + +<p>In 1803 it was announced by Sir William Herschel that there exist +sidereal systems composed of two stars revolving about each other in +regular orbits, and <span class='pagenum'><a name="Page_154" id="Page_154">[Pg 154]</a></span>constituting which may be called, to distinguish +them from double stars, which are only optically double, binary stars. +That which since then has been most assiduously watched, and has offered +phenomena of the greatest interest, is <i>gamma Virginis</i>. It is a star of +the vulgar third magnitude, and its component individuals are very +nearly equal, and, as it would seem, in some slight degree variable. It +has been known to consist of two stars since the beginning of the +eighteenth century, the distance being then between six and seven +seconds, so that any tolerably good telescope would resolve it. When +observed by Herschel in 1780 it was 5.66 seconds, and continued to +decrease gradually and regularly, till at length, in 1836, the two stars +had approached so closely as to appear perfectly round and single under +the highest magnifying power which could be applied to most excellent +instruments—the great refractor of Pulkowa alone, with a magnifying +power of a thousand, continuing to indicate, by the wedge-shaped form of +the disc of the star, its composite nature.</p> + +<p>By estimating the ratio of its length to its breadth, and measuring the +former, M. Struve concludes that at this epoch the distance of the two +stars, centre from centre, might be stated at .22 seconds. From that +time the star again opened, and is now again a perfectly easily +separable star. This very remarkable diminution, and subsequent +increase, of distance has been accompanied by a corresponding and +equally remarkable increase and subsequent diminution of relative +angular motion. Thus in 1783 the apparent angular motion hardly amounted +to half a degree per annum; while in 1830 it had decreased to 5 degrees, +in 1834 to 20 degrees, in 1835 to 40 degrees, and about the middle of +1836 to upwards of 70 degrees per annum, or at the rate of a degree in +five days.</p> + +<p>This is in entire conformity with the principles of dynamics, which +establish a necessary connection <span class='pagenum'><a name="Page_155" id="Page_155">[Pg 155]</a></span>between the angular velocity and the +distance, as well in the apparent as in the real orbit of one body +revolving about another under the influence of mutual attraction; the +former varying inversely as the square of the latter, in both orbits, +whatever be the curve described and whatever the law of the attractive +force.</p> + +<p>It is not with the revolutions of bodies of a planetary or cometary +nature round a solar centre that we are concerned; it is that of sun +round sun—each perhaps, at least in some binary systems, where the +individuals are very remote and their period of revolution very long, +accompanied by its train of planets and their satellites, closely +shrouded from our view by the splendour of their respective suns, and +crowded into a space bearing hardly a greater proportion to the enormous +interval which separates them than the distances of the satellites of +our planets from their primaries bear to their distances from the sun +itself.</p> + +<p>A less distinctly characterised subordination would be incompatible with +the stability of their systems and with the planetary nature of their +orbits. Unless close under the protecting wing of their immediate +superior, the sweep of their other sun, in its perihelion passage round +their own, might carry them off or whirl them into orbits utterly +incompatible with conditions necessary for the existence of their +inhabitants.</p> + + +<p class="subchap"><i>IV.—The Nebulæ</i></p> + +<p>It is to Sir William Herschel that we owe the most complete analysis of +the great variety of those objects which are generally classed as +nebulæ. The great power of his telescopes disclosed the existence of an +immense number of these objects before unknown, and showed them to be +distributed over the heavens not by any means uniformly, but with a +marked preference to a certain district extending over the northern pole +of the galactic<span class='pagenum'><a name="Page_156" id="Page_156">[Pg 156]</a></span> circle. In this region, occupying about one-eighth of +the surface of the sphere, one-third of the entire nebulous contents of +the heavens are situated.</p> + +<p>The resolvable nebulæ can, of course, only be considered as clusters +either too remote, or consisting of stars intrinsically too faint, to +affect us by their individual light, unless where two or three happen to +be close enough to make a joint impression and give the idea of a point +brighter than the rest. They are almost universally round or oval, their +loose appendages and irregularities of form being, as it were, +extinguished by the distance, and only the general figure of the +condensed parts being discernible. It is under the appearance of objects +of this character that all the greater globular clusters exhibit +themselves in telescopes of insufficient optical power to show them +well.</p> + +<p>The first impression which Halley and other early discoverers of +nebulous objects received from their peculiar aspect was that of a +phosphorescent vapour (like the matter of a comet's tail), or a gaseous +and, so to speak, elementary form of luminous sidereal matter. Admitting +the existence of such a medium, Sir W. Herschel was led to speculate on +its gradual subsidence and condensation, by the effect of its own +gravity, into more or less regular spherical or spheroidal forms, denser +(as they must in that case be) towards the centre.</p> + +<p>Assuming that in the progress of this subsidence local centres of +condensation subordinate to the general tendency would not be wanting, +he conceived that in this way solid nuclei might arise whose local +gravitation still further condensing, and so absorbing the nebulous +matter each in its immediate neighbourhood, might ultimately become +stars, and the whole nebula finally take on the state of a cluster of +stars.</p> + +<p>Among the multitude of nebulæ revealed by his telescope every stage of +this process might be considered as displayed to our eyes, and in every +modification of form<span class='pagenum'><a name="Page_157" id="Page_157">[Pg 157]</a></span> to which the general principle might be conceived +to apply. The more or less advanced state of a nebula towards its +segregation into discrete stars, and of these stars themselves towards a +denser state of aggregation round a central nucleus, would thus be in +some sort an indication of age.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_158" id="Page_158">[Pg 158]</a></span></p> +<h3>ALEXANDER VON HUMBOLDT</h3> + +<p class="book"><big><a name="Cosmos_a_Sketch_of_the_Universe" id="Cosmos_a_Sketch_of_the_Universe"></a>Cosmos, a Sketch of the Universe</big></p> + +<div class="blockquot"><p>Frederick Henry Alexander von Humboldt was born in Berlin on +September 14, 1769. In 1788 he made the acquaintance of George +Forster, one of Captain Cook's companions, and geological +excursions made with him were the occasion of his first +publications, a book on the nature of basalt. His work in the +administration of mines in the principalities of Bayreuth and +Anspach furnished materials for a treatise on fossil flora; and in +1827, when he was residing in Paris, he gave to the world his +"Voyage to the Equinoctial Regions of the New Continent," which +embodies the results of his investigations in South America. Two +years later he organised an expedition to Asiatic Russia, charging +himself with all the scientific observations. But his principal +interest lay in the accomplishment of that physical description of +the universe for which all his previous studies had been a +preparation, and which during the years 1845 to 1848 appeared under +the comprehensive title of "Cosmos, or Sketch of a Physical +Description of the Universe." Humboldt died on May 6, 1859.</p></div> + + +<p class="subchap"><i>I.—The Physical Study of the World</i></p> + +<p><span class="smcap">The</span> natural world may be opposed to the intellectual, or nature to art +taking the latter term in its higher sense as embracing the +manifestations of the intellectual power of man; but these +distinctions—which are indicated in most cultivated languages—must not +be suffered to lead to such a separation of the domain of physics from +that of the intellect as would reduce the physics of the universe to a +mere assemblage of empirical specialities. Science only begins for man +from the moment when his mind lays hold of matter—when he tries to +subject the mass accumulated by experience to rational combinations.</p> + +<p>Science is mind applied to nature. The external world only exists for us +so far as we conceive it within ourselves, and as it shapes itself +within us into the form of<span class='pagenum'><a name="Page_159" id="Page_159">[Pg 159]</a></span> a contemplation of nature. As intelligence +and language, thought and the signs of thought, are united by secret and +indissoluble links, so, and almost without our being conscious of it, +the external world and our ideas and feelings melt into each other. +"External phenomena are translated," as Hegel expresses it in his +"Philosophy of History," "in our internal representation of them." The +objective world, thought by us, reflected in us, is subjected to the +unchanging, necessary, and all-conditioning forms of our intellectual +being.</p> + +<p>The activity of the mind exerts itself on the elements furnished to it +by the perceptions of the senses. Thus, in the youth of nations there +manifests itself in the simplest intuition of natural facts, in the +first efforts made to comprehend them, the germ of the philosophy of +nature.</p> + +<p>If the study of physical phenomena be regarded in its bearings not on +the material wants of man, but on his general intellectual progress, its +highest result is found in the knowledge of those mutual relations which +link together the general forces of nature. It is the intuitive and +intimate persuasion of the existence of these relations which at once +enlarges and elevates our views and enhances our enjoyment. Such +extended views are the growth of observation, of meditation, and of the +spirit of the age, which is ever reflected in the operations of the +human mind whatever may be their direction.</p> + +<p>From the time when man, in interrogating nature, began to experiment or +to produce phenomena under definite conditions, and to collect and +record the fruits of his experience—so that investigation might no +longer be restricted by the short limits of a single life—the +philosophy of nature laid aside the vague and poetic forms with which +she had at first been clothed, and has adopted a more severe character.</p> + +<p>The history of science teaches us how inexact and incomplete +observations have led, through false inductions,<span class='pagenum'><a name="Page_160" id="Page_160">[Pg 160]</a></span> to that great number +of erroneous physical views which have been perpetuated as popular +prejudices among all classes of society. Thus, side by side with a solid +and scientific knowledge of phenomena, there has been preserved a system +of pretended results of observation, the more difficult to shake because +it takes no account of any of the facts by which it is overturned.</p> + +<p>This empiricism—melancholy inheritance of earlier times—invariably +maintains whatever axioms it has laid down; it is arrogant, as is +everything that is narrow-minded; while true physical philosophy, +founded on science, doubts because it seeks to investigate +thoroughly—distinguishes between that which is certain and that which +is simply probable—and labours incessantly to bring its theories nearer +to perfection by extending the circle of observation. This assemblage of +incomplete dogmas bequeathed from one century to another, this system of +physics made up of popular prejudices, is not only injurious because it +perpetuates error with all the obstinacy of ill-observed facts, but also +because it hinders the understanding from rising to the level of great +views of nature.</p> + +<p>Instead of seeking to discover the <i>mean</i> state around which, in the +midst of apparent independence and irregularity, the phenomena really +and invariably oscillate, this false science delights in multiplying +apparent exceptions to the dominion of fixed laws, and seeks, in organic +forms and the phenomena of nature, other marvels than those presented by +internal progressive development, and by regular order and succession. +Ever disinclined to recognise in the present the analogy of the past, it +is always disposed to believe the order of nature suspended by +perturbations, of which it places the seat, as if by chance, sometimes +in the interior of the earth, sometimes in the remote regions of space.</p> + + +<p><span class='pagenum'><a name="Page_161" id="Page_161">[Pg 161]</a></span></p><p class="subchap"><i>II.—The Inductive Method</i></p> + +<p>The generalisation of laws which were first applied to smaller groups of +phenomena advances by successive gradations, and their empire is +extended, and their evidence strengthened, so long as the reasoning +process is directed to really analogous phenomena. Empirical +investigation begins by single perceptions, which are afterwards classed +according to their analogy or dissimilarity. Observation is succeeded at +a much later epoch by experiment, in which phenomena are made to arise +under conditions previously determined on by the experimentalist, guided +by preliminary hypotheses, or a more or less just intuition of the +connection of natural objects and forces.</p> + +<p>The results obtained by observation and experiment lead by the path of +induction and analogy to the discovery of empirical laws, and these +successive phases in the application of human intellect have marked +different epochs in the life of nations. It has been by adhering closely +to this inductive path that the great mass of facts has been accumulated +which now forms the solid foundation of the natural sciences.</p> + +<p>Two forms of abstraction govern the whole of this class of +knowledge—<i>viz.</i>, the determination of quantitative relations, +according to number and magnitude; and relations of quality, embracing +the specific properties of heterogeneous matter.</p> + +<p>The first of these forms, more accessible to the exercise of thought, +belongs to the domain of mathematics; the other, more difficult to +seize, and apparently more mysterious, to that of chemistry. In order to +submit phenomena to calculation, recourse is had to a hypothetical +construction of matter by a combination of molecules and atoms whose +number, form, position, and polarity determine, modify, and vary the +phenomena.</p> + +<p><span class='pagenum'><a name="Page_162" id="Page_162">[Pg 162]</a></span></p><p>We are yet very far from the time when a reasonable hope could be +entertained of reducing all that is perceived by our senses to the unity +of a single principle; but the partial solution of the problem—the +tendency towards a general comprehension of the phenomena of the +universe—does not the less continue to be the high and enduring aim of +all natural investigation.</p> + + +<p class="subchap"><i>III.—Distribution of Matter in Space</i></p> + +<p>A physical cosmography, or picture of the universe, should begin, not +with the earth, but with the regions of space—the distribution of +matter in the universe.</p> + +<p>We see matter existing in space partly in the form of rotating and +revolving spheroids, differing greatly in density and magnitude, and +partly in the form of self-luminous vapour dispersed in shining nebulous +spots or patches. The nebulæ present themselves to the eye in the form +of round, or nebulous discs, of small apparent magnitude, either single +or in pairs, which are sometimes connected by a thread of light; when +their diameters are greater their forms vary—some are elongated, others +have several branches, some are fan-shaped, some annular, the ring being +well defined and the interior dark. They are supposed to be undergoing +various and progressive changes of form, as condensation proceeds around +one or more nuclei in conformity with the laws of gravitation. Between +two and three thousand of such unresolvable nebulæ have already been +counted, and their positions determined.</p> + +<p>If we leave the consideration of the attenuated vaporous matter of the +immeasurable regions of space, whether existing in a dispersed state as +a cosmical ether without form or limits, or in the shape of nebulæ, and +pass to those portions of the universe which are condensed into solid +spheres or spheroids, we approach a class of phenomena exclusively +designated as stars or<span class='pagenum'><a name="Page_163" id="Page_163">[Pg 163]</a></span> as the sidereal universe. Here, too, we find +different degrees of solidity or density in the agglomerated matter.</p> + +<p>If we compare the regions of space to one of the island-studded seas of +our planet, we may imagine we see matter distributed in groups, whether +of unresolvable nebulæ of different ages condensed around one or more +nuclei, or in clusters of stars, or in stars scattered singly. Our +cluster of stars, or the island in space to which we belong, forms a +lens-shaped, flattened, and everywhere detached stratum, whose major +axis is estimated at seven or eight hundred, and its minor axis at a +hundred and fifty times, the distance of Sirius. If we assume that the +parallax of Sirius does not exceed that accurately determined for the +brightest stars in Centaur (0.9128 sec.), it will follow that light +traverses one distance of Sirius in three years, while nine years and a +quarter are required for the transmission of the light of the star 61 +Cygni, whose considerable proper motion might lead to the inference of +great proximity.</p> + +<p>Our cluster of stars is a disc of comparatively small thickness divided, +at about a third its length, into two branches; we are supposed to be +near this division, and nearer to the region of Sirius than to that of +the constellation of the Eagle; almost in the middle of the starry +stratum in the direction of its thickness.</p> + +<p>The place of our solar system and the form of the whole lens are +inferred from a kind of scale—<i>i.e.</i>, from the different number of +stars seen in equal telescopic fields of view. The greater or less +number of stars measures the relative depth of the stratum in different +directions; giving in each case, like the marks on a sounding-line, the +comparative length of visual ray required to reach the bottom; or, more +properly, as above and below do not here apply, the outer limit of the +sidereal stratum.</p> + +<p>In the direction of the major axis, where the greater<span class='pagenum'><a name="Page_164" id="Page_164">[Pg 164]</a></span> number of stars +are placed behind each other, the remoter ones appear closely crowded +together, and, as it were, united by a milky radiance, and present a +zone or belt projected on the visible celestial vault. This narrow belt +is divided into branches; and its beautiful, but not uniform brightness, +is interrupted by some dark places. As seen by us on the apparent +concave celestial sphere, it deviates only a few degrees from a great +circle, we being near the middle of the entire starry cluster, and +almost in the plane of the Milky Way. If out planetary system were far +outside the cluster, the Milky Way would appear to telescopic vision as +a ring, and at a still greater distance as a resolvable disc-shaped +nebula.</p> + + +<p class="subchap"><i>IV.—On Earth History</i></p> + +<p>The succession and relative age of different geological formations are +traced partly by the order of superposition of sedimentary strata, of +metamorphic beds, and of conglomerates, but most securely by the +presence of organic remains and their diversities of structure. In the +fossiliferous strata are inhumed the remains of the floras and faunas of +past ages. As we descend from stratum to stratum to study the relations +of superposition, we ascend in the order of time, and new worlds of +animal and vegetable existence present themselves to the view.</p> + +<p>In our ignorance of the laws under which new organic forms appear from +time to time upon the surface of the globe, we employ the expression +"new creations" when we desire to refer to the historical phenomena of +the variations which have taken place at intervals in the animals and +plants that have inhabited the basins of the primitive seas and the +uplifted continents.</p> + +<p>It has sometimes happened that extinct species have been preserved +entire, even to the minutest details of their tissues and articulations. +In the lower beds of the<span class='pagenum'><a name="Page_165" id="Page_165">[Pg 165]</a></span> Secondary Period, the lias of Lyme Regis, a +sepia has been found so wonderfully preserved that a part of the black +fluid with which the animal was provided myriads of years ago to conceal +itself from its enemies has actually served at the present time to draw +its picture. In other cases such traces alone remain as the impression +which the feet of animals have left on wet sand or mud over which they +passed when alive, or the remains of their undigested food (coprolites).</p> + +<p>The analytical study of the animal and vegetable kingdoms of the +primitive world has given rise to two distinct branches of science; one +purely morphological, which occupies itself in natural and physiological +descriptions, and in the endeavour to fill up from extinct forms the +chasms which present themselves in the series of existing species; the +other branch, more especially geological considers the relations of the +fossil remains to the superposition and relative age of the sedimentary +beds in which they are found. The first long predominated; and the +superficial manner which then prevailed of comparing fossil and existing +species led to errors of which traces still remain in the strange +denominations which were given to certain natural objects. Writers +attempted to identify all extinct forms with living species, as, in the +sixteenth century, the animals of the New World were confounded by false +analogies with those of the Old.</p> + +<p>In studying the relative age of fossils by the order of superposition of +the strata in which they are found, important relations have been +discovered between families and species (the latter always few in +numbers) which have disappeared and those which are still living. All +observations concur in showing that the fossil floras and faunas differ +from the present animal and vegetable forms the more widely in +proportion as the sedimentary beds to which they belong are lower, or +more ancient.</p> + +<p>Thus great variations have successively taken place in<span class='pagenum'><a name="Page_166" id="Page_166">[Pg 166]</a></span> the general +types of organic life, and these grand phenomena, which were first +pointed out by Cuvier, offer numerical relations which Deshayes and +Lyell have made the object of researches by which they have been +conducted to important results, especially as regards the numerous and +well-preserved fossils of the Tertiary formation. Agassiz, who has +examined 1,700 species of fossil fishes, and who estimates at 8,000 the +number of living species which have been described, or which are +preserved in our collections, affirms that, with the exception of one +small fossil fish peculiar to the argillaceous geodes of Greenland, he +has never met in the Transition, Secondary, or Tertiary strata with any +example of this class specifically identical with any living fish; and +he adds the important remark that even in the lower Tertiary formations +a third of the fossil fishes of the <i>calcaire grossier</i> and of the +London clay belong to extinct families.</p> + +<p>We have seen that fishes, which are the oldest vertebrates, first appear +in the Silurian strata, and are found in all the succeeding formations +up to the birds of the Tertiary Period. Reptiles begin in like manner in +the magnesian limestone, and if we now add that the first mammalia are +met with in Oolite, the Stonefield slate; and that the first remains of +birds have been found in the deposits of the cretaceous period, we shall +have indicated the inferior limits, according to our present knowledge, +of the four great divisions of the vertebrates.</p> + +<p>In regard to invertebrate animals, we find corals and some shells +associated in the oldest formations with very highly organised +cephalopodes and crustaceans, so that widely different orders of this +part of the animal kingdom appear intermingled; there are, nevertheless, +many isolated groups belonging to the same order in which determinate +laws are discoverable. Whole mountains are sometimes found to consist of +a single species of fossil goniatites, trilobites, or nummulites.</p> + +<p><span class='pagenum'><a name="Page_167" id="Page_167">[Pg 167]</a></span></p><p>Where different genera are intermingled, there often exists a +systematic relation between the series of organic forms and the +superposition of the formations; and it has been remarked that the +association of certain families and species follows a regular law in the +superimposed strata of which the whole constitutes one formation. It has +been found that the waters in the most distant parts of the globe were +inhabited at the same epochs by testaceous animals corresponding, at +least in generic character, with European fossils.</p> + +<p>Strata defined by their fossil contents, or by the fragments of other +rocks which they include, form a geological horizon by which the +geologist may recognise his position, and obtain safe conclusions in +regard to the identity or relative antiquity of formations, the +periodical repetition of certain strata—their parallelism—or their +entire suppression. If we would thus comprehend in its greatest +simplicity the general type of the sedentary formations, we find in +proceeding successively from below upwards: (1) The Transition group, +including the Silurian and Devonian (Old Red Sandstone) systems; (2) the +Lower Trias, comprising mountain limestone, the coal measures, the lower +new red sandstone, and the magnesian limestone; (3) the Upper Trias, +composing the bunter, or variegated sandstone, the muschelkalk, and the +Keuper sandstone; (4) the Oolitic, or Jurassic series, including Lias; +(5) the Cretaceous series; (6) the Tertiary group, as represented in its +three stages by the <i>calcaire grossier</i> and other beds of the Paris +basin, the lignites, or brown coal of Germany, and the sub-Apennine +group of Italy.</p> + +<p>To these succeed transported soils (<i>alluvium</i>), containing the gigantic +bones of ancient mammalia, such as the mastodons, the dinotherium, and +the megatheroid animals, among which is the mylodon of Owen, an animal +upwards of eleven feet in length, allied to the sloth. Associated with +these extinct species are found the fossil<span class='pagenum'><a name="Page_168" id="Page_168">[Pg 168]</a></span> remains of animals still +living: elephants, rhinoceroses, oxen, horses, and deer. Near Bogota, at +an elevation of 8,200 French feet above the level of the sea, there is a +field filled with the bones of mastodon (<i>Campo de Gigantes</i>), in which +I have had careful excavations made. The bones found on the table-lands +of Mexico belong to the true elephants of extinct species. The minor +range of the Himalaya, the Sewalik hills, contain, besides numerous +mastodons, the sivatherium and the gigantic land-tortoise +(<i>Colossochelys</i>), more than twelve feet in length and six in height, as +well as remains belonging to still existing species of elephants, +rhinoceroses, and giraffes. It is worthy of notice that these fossils +are found in a zone which enjoys the tropical climate supposed to have +prevailed at the period of the mastodons.</p> + + +<p class="subchap"><i>V.—The Permanence of Science</i></p> + +<p>It has sometimes been regarded as a discouraging consideration that, +while works of literature being fast-rooted in the depths of human +feeling, imagination and reason suffer little from the lapse of time, it +is otherwise with works which treat of subjects dependent on the +progress of experimental knowledge. The improvement of instruments, and +the continued enlargement of the field of observation, render +investigations into natural phenomena and physical laws liable to become +antiquated, to lose their interest, and to cease to be read.</p> + +<p>Let none who are deeply penetrated with a true and genuine love of +nature, and with a lively appreciation of the true charm and dignity of +the study of her laws, ever view with discouragement or regret that +which is connected with the enlargement of the boundaries of our +knowledge. Many and important portions of this knowledge, both as +regards the phenomena of the celestial spaces and those belonging to our +own planet, are <span class='pagenum'><a name="Page_169" id="Page_169">[Pg 169]</a></span>already based on foundations too firm to be lightly +shaken; although in other portions general laws will doubtless take the +place of those which are more limited in their application, new forces +will be discovered, and substances considered as simple will be +decomposed, while others will become known.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_170" id="Page_170">[Pg 170]</a></span></p> +<h3>JAMES HUTTON</h3> + +<p class="book"><big><a name="The_Theory_of_the_Earth" id="The_Theory_of_the_Earth"></a>The Theory of the Earth</big></p> + +<div class="blockquot"><p>James Hutton, the notable Scotch geologist, was born at Edinburgh +on June 3, 1726. In 1743 he was apprenticed to a Writer to the +Signet; but his apprenticeship was of short duration and in the +following year he began to study medicine at Edinburgh University, +and in 1749 graduated as an M.D. Later he determined to study +agriculture, and went, in 1752, to live with a Norfolk farmer to +learn practical farming. He did not devote himself entirely to +agriculture, but gave a considerable amount of his time to chemical +and geological researches. His geological researches culminated in +his great work, "The Theory of the Earth," published at Edinburgh +in 1795. In this work he propounds the theory that the present +continents have been formed at the bottom of the sea by the +precipitation of the detritus of former continents, and that the +precipitate had been hardened by heat and elevated above the sea by +the expansive power of heat. He died on March 26, 1797. Other works +are his "Theory of Rain," "Elements of Agriculture," "Natural +Philosophy," and "Nature of Coal."</p></div> + + +<p class="subchap"><i>I.—Origin and Consolidation of the Land</i></p> + +<p><span class="smcap">The</span> solid surface of the earth is mainly composed of gravel, of +calcareous, and argillaceous strata. Sand is separated by streams and +currents, gravel is formed by the attrition of stones agitated in water, +and argillaceous strata are deposited by water containing argillaceous +material. Accordingly, the solid earth would seem to have been mainly +produced by water, wind, and tides, and this theory is confirmed by the +discovery that all the masses of marble and limestone are composed of +the calcareous matter of marine bodies. All these materials were, in the +first place, deposited at the bottom of the sea, and we have to +consider, firstly, how they were consolidated; and secondly, how they +came to be dry land, elevated above the sea.</p> + +<p><span class='pagenum'><a name="Page_171" id="Page_171">[Pg 171]</a></span></p><p>It is plain that consolidation may have been effected either through +the concretion of substances dissolved in water or through fusion by +fire. Consolidation through the concretion of substances dissolved in +the sea is unlikely, for, in the first place, there are strata, such as +siliceous matter, which are insoluble, and which could not therefore +have been in solution; and, in the second place, the appearance of the +strata is contrary to this supposition. Consolidation was probably +effected by heat and fusion. All the substances in the earth may be +rendered fluid by heat, and all the appearances in the earth's crust are +consistent with the consolidation and crystallisation of fused +substances. Not only so, but we find rents and separations and veins in +the strata, such as would naturally occur in strata consolidated by the +cooling of fused masses, and other phenomena pointing to fusion by heat. +We may conclude, then, that all the solid strata of the globe have been +hardened from a state of fusion.</p> + +<p>But how were these strata raised up from the bottom of the sea and +transformed into dry land? Even as heat was the consolidating power, so +heat was also probably the elevating power. The power of heat for the +expansion of bodies is, as we know, unlimited, and the expansive power +of heat was certainly competent to raise the strata above the sea. Heat +was certainly competent, and if we examine the crust of the earth we +find evidence that heat was used.</p> + +<p>If the strata cemented by the heat of fusion were created by the +expansive power of heat acting from below, we should expect to find +every species of fracture, dislocation, and contortion in those bodies, +and every degree of departure from a horizontal towards a vertical +position. And this is just what we do find. From horizontal, the strata +are frequently found vertical; from continuous, broken, and separated in +every possible direction; and from a plane, bent and doubled. The theory +is confirmed by an examination of the veins and fissures<span class='pagenum'><a name="Page_172" id="Page_172">[Pg 172]</a></span> of the earth +which contain matter foreign to the strata they traverse, and evidently +forced into them as a fluid under great pressure. Active volcanoes, and +extinct volcanoes, and the marks everywhere of volcanic action likewise +support the theory of expansion and elevation by heat. A volcano is not +made on purpose to frighten superstitious people into fits of piety and +devotion; it is to be considered as a spiracle of a subterranean +furnace.</p> + +<p>Such being the manner of the formation of the crust of the world, can we +form any judgment of its duration and durability? If we could measure +the rate of the attrition of the present continents, we might estimate +the duration of the older continents whose attrition supplied the +material for the present dry land. But as we cannot measure the +wearing-away of the land, we can merely state generally, first, that the +present dry land required an indefinitely long period for its formation; +second, that the previous dry land which supplied material for its +formation required equal time to make; third, that there is at present +land forming at the bottom of the sea which in time will appear above +the surface; fourth, that we find no vestige of a beginning, or of an +end.</p> + +<p>Granite has in its own nature no claim to originality, for it is found +to vary greatly in its composition. But, further, it is certain that +granite, or a species of the same kind of stone, is found stratified. It +is the <i>granit feuilletée</i> of M. de Sauffure, and, if I mistake not, is +called <i>gneiss</i> by the Germans. Granite being thus found stratified, the +masses of this stone cannot be allowed to any right of priority over the +schistus, its companion in Alpine countries.</p> + +<p>Lack of stratification, then, cannot be considered a proof of primitive +rock. Nor can lack of organized bodies, such as shells, in these rocks, +be considered a proof; for the traces of organized bodies may be +<span class='pagenum'><a name="Page_173" id="Page_173">[Pg 173]</a></span>obliterated by the many subsequent operations of the mineral region. In +any case, signs of organized bodies are sometimes found in "primitive" +mountains.</p> + +<p>Nor can metallic veins, found plentifully in "primitive" mountains, +prove anything, for mineral veins are found in various strata.</p> + +<p>We maintain that <i>all</i> the land was produced from fused substances +elevated from the bottom of the sea. But we do not hold that all parts +of the earth have undergone exactly similar and simultaneous +vicissitudes; and in respect to the changes which various parts of the +land have undergone we may distinguish between primary and secondary +strata. Nothing is more certain than that there have been several +repeated operations of the mineralising power exerted upon the strata in +particular places, and all those mineral operations tend to +consolidation. It is quite possible that "primitive" masses which differ +from the ordinary strata of the globe have been twice subjected to +mineral operations, having been first consolidated and raised as land, +and then submerged in order to be again fused and elevated.</p> + + +<p class="subchap"><i>II.—The Nature of Mineral Coal</i></p> + +<p>Mineral, or fossil, coal is a species of stratum distinguished by its +inflammable and combustible nature. We find that it differs in respect +to its purity, and also in respect to its inflammability. As is well +known, some coals have almost no earthy ash, some a great deal; and, +again, some coals burn with much smoke and fire, while others burn like +coke. Where, then, did coal come from, and how can we account for its +different species?</p> + +<p>A substance proper for the formation of coaly matter is found in +vegetable bodies. But how did it become mixed with earthy matter?</p> + +<p>Vegetable bodies may be resolved into bituminous or coaly matter either +by means of fire or by means of<span class='pagenum'><a name="Page_174" id="Page_174">[Pg 174]</a></span> water. Both may be used by nature in +the formation of coal.</p> + +<p>By the force of subterranean heat vegetable matter may have been charred +at the bottom of the sea, and the oleaginous, bituminous, and fuliginous +substances diffused through the sea as a result of the burning may have +been deposited at the bottom of the sea as coal. Further, the bituminous +matter from the smoke of vegetable substances burned on land would +ultimately be deposited from the atmosphere and settle at the bottom of +the sea.</p> + +<p>Many of the rivers contain in solution an immense quantity of +inflammable vegetable substance, and this is carried into the sea, and +precipitated there.</p> + +<p>From these two sources, then, the sea gets bituminous material, and this +material, condensed and consolidated by compression and by heat, at the +bottom of the sea, would form a black body of a most uniform structure, +breaking with a polished surface, and burning with more or less smoke or +flame in proportion as it be distilled less or more by subterranean +heat. And such a body exactly represents our purest fossil coal, which +gives the most heat and leaves the least ash.</p> + +<p>In some cases the bituminous material in suspension in the sea would be +mixed more or less with argillaceous, calcareous, and other earthy +substances; and these being precipitated along with the bituminous +matter would form layers of impure coal with a considerable amount of +ash.</p> + +<p>But there is still a third source of coal. Vegetable bodies macerated in +water, and consolidated by compression, form a body almost +indistinguishable from some species of coal, as is seen in peat +compressed under a great load of earth; and there can be no doubt that +coal sometimes originates in this way, for much fossil coal shows +abundance of vegetable bodies in its composition.</p> + +<p>There remains only to consider the change in the <span class='pagenum'><a name="Page_175" id="Page_175">[Pg 175]</a></span>disposition of coal +strata. Coal strata, which had been originally in a horizontal position, +are now found sometimes standing erect, even perpendicular. This, also, +is consistent with our theory of the earth. Indeed, there is not a +substance in the mineral kingdom in which the action of subterranean +heat is better shown. These strata are evidently a deposit of +inflammable substances which all come originally from vegetable bodies. +In this stage of their formation they must all contain volatile +oleaginous constituents. But some coal strata contain no volatile +constituents, and the disappearance of the volatile oleaginous +substances must have been produced by distillation, proceeding perhaps +under the restraining force of immense compression.</p> + +<p>We cannot doubt that such distillation does take place in the mineral +regions, when we consider that in most places of the earth we find the +evident effects of such distillation in the naphtha and petroleum that +are constantly emitted along with water in certain springs. We have, +therefore, sufficient proof of this operation of distillation.</p> + + +<p class="subchap"><i>III.—The Disintegration and Dissolution of Land</i></p> + +<p>Whether we examine the mountain or the plain, whether we consider the +disintegration of the rocks or the softer strata of the earth, whether +we regard the shores of seas or the central plains of continents, +whether we contemplate fertile lands or deserts, we find evidence of a +general dissolution and decay of the solid surface of the globe. Every +great river and deep valley gives evidence of the attrition of the land. +The purpose of the dry land is to sustain a system of plants and +animals; and for this purpose a soil is required, and to make a soil the +solid strata must be crumbled down. The earth is nothing more than an +indefinite number of soils and situations suitable for various animals +and plants, and<span class='pagenum'><a name="Page_176" id="Page_176">[Pg 176]</a></span> it must consist of both solid rock and tender earth, of +both moist and dry districts; for all these are requisite for the world +we inhabit.</p> + +<p>But not only is the solid rock crumbling into soil by the action of air +and water, but the soil gradually progresses towards the sea, and sooner +or later the sea must swallow up the land. Vegetation and masses of +solid rock retard the seaward flow of the soil; but they merely retard, +they cannot wholly prevent. In proportion as the mountains are +diminished, the haugh, or plain, between them grows more wide, and also +on a lower level; but while there is a river running on a plain, and +floods produced in the seasons of rain, there is nothing stable in the +constitution of the surface of the land.</p> + +<p>The theory of the earth which I propound is founded upon the great +catastrophes that can happen to the earth. It supposes strata raised +from the bottom of the sea and elevated into mountainous continents. +But, between the catastrophes, it requires nothing further than the +ordinary everyday effects of air and water. Every shower of rain, every +stream, participates in the dissolution of the land, and helps to +transport to the sea the material for future continents.</p> + +<p>The prodigious waste of the land we see in places has seemed to some to +require some other explanation; but I maintain that the natural +operations of air and water would suffice in time to produce the effects +observed. It is true that the wastage would be slow; but slow +destruction of rock with gradual formation of soil is just what is +required in the economy of nature. A world sustaining plants and animals +requires continents which endure for more than a day.</p> + +<p>If this continent of land, first collected in the sea, is to remain a +habitable earth, and to resist the moving waters of the globe, certain +degrees of solidity or consolidation must be given to that collection of +loose materials; and certain degrees of hardness must be given to<span class='pagenum'><a name="Page_177" id="Page_177">[Pg 177]</a></span> +bodies which are soft and incoherent, and consequently so extremely +perishable in the situation in which they are now placed.</p> + +<p>But, at the same time that this earth must have solidity and hardness to +resist the sudden changes which its moving fluids would occasion, it +must be made subject to decay and waste upon the surface exposed to the +atmosphere; for such an earth as were made incapable of change, or not +subject to decay, would not afford that fertile soil which is required +in the system of this world—a soil on which depends the growth of +plants and life of animals—the end of its intention.</p> + +<p>Now, we find this earth endued precisely with such degree of hardness +and consolidation as qualifies it at the same time to be a fruitful +earth, and to maintain its station with all the permanency compatible +with the nature of things, which are not formed to remain unchangeable.</p> + +<p>Thus we have a view of the most perfect wisdom in the contrivance of +that constitution by which the earth is made to answer, in the best +manner possible, the purpose of its intention, that is, to maintain and +perpetuate a system of vegetation, or the various races of useful +plants, or a system of living animals, which are in their turn +subservient to a system still infinitely more important—I mean a system +of intellect. Without fertility in the earth, many races of plants and +animals would soon perish, or be extinct; and with permanency in our +land it were impossible for the various tribes of plants and animals to +be dispersed over the surface of a changing earth. The fact is that +fertility, adequate to the various ends in view, is found in all the +quarters of the world, or in every country of the earth; and the +permanency of our land is such as to make it appear unalterable to +mankind in general and even to impose upon men of science, who have +endeavoured to persuade us that this earth is not to change.</p> + +<p><span class='pagenum'><a name="Page_178" id="Page_178">[Pg 178]</a></span></p><p>Nothing but supreme power and wisdom could have reconciled those two +opposite ends of intention, so as both to be equally pursued in the +system of nature, and so equally attained as to be imperceptible to +common observation, and at the same time a proper object of the human +understanding.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_179" id="Page_179">[Pg 179]</a></span></p> +<h3>LAMARCK</h3> + +<p class="book"><big><a name="Zoological_Philosophy" id="Zoological_Philosophy"></a>Zoological Philosophy</big></p> + +<div class="blockquot"><p>Jean Baptiste de Monet, Chevalier de Lamarck, was born in Picardy, +France, Aug. I, 1744, the cadet of an ancient but impoverished +house. It was his father's desire that he should enter the Church, +but his inclination was for a military life; and having, at the age +of seventeen, joined the French army under De Broglie, he had +within twenty-four hours the good fortune so to distinguish himself +as to win his commission. When the Museum of Natural History was +brought into existence in 1794 he was sufficiently well-known as a +naturalist to be entrusted with the care of the collections of +invertebrates, comprising insects, molluscs, polyps, and worms. +Here he continued to lecture until his death in 1829. Haeckel, +classifying him in the front rank with Goethe and Darwin, +attributes to him "the imperishable glory of having been the first +to raise the theory of descent to the rank of an independent +scientific theory." The form of his theory was announced in 1801, +but was not given in detail to the world until 1809, by the +publication of his "Zoological Philosophy" ("Philosophie +Zoologique"). The Lamarckian theory of the hereditary transmission +of characters acquired by use, disuse, etc., has still a following, +though it is controverted by the schools of Darwin and Weissmann. +Lamarck died on December 18, 1829.</p></div> + + +<p class="subchap"><i>I.—The Ladder of Life</i></p> + +<p><span class="smcap">If</span> we look backwards down the ladder of animal forms we find a +progressive degradation in the organisation of the creatures comprised; +the organisation of their bodies becomes simpler, the number of their +faculties less. This well-recognised fact throws a light upon the order +in which nature has produced the animals; but it leaves unexplained the +fact that this gradation, though sustained, is irregular. The reason +will become clear if we consider the effects produced by the infinite +diversity of conditions in different parts of the globe<span class='pagenum'><a name="Page_180" id="Page_180">[Pg 180]</a></span> upon the +general form, the limbs, and the very organisation of the animals in +question.</p> + +<p>It will, in fact, be evident that the state in which we find all animals +is the product, on the one hand, of the growing composition of the +organisation which tends to form a regular gradation; and that, for the +rest, it results from a multitude of circumstances which tend +continually to destroy the regularity of the gradation in the +increasingly composite nature of the organism.</p> + +<p>Not that circumstances can effect any modification directly. But changed +circumstances produce changed wants, changed wants changed actions. If +the new wants become constant the animals acquire new habits, which are +no less constant than the wants which gave rise to them. And such new +habits will necessitate the use of one member rather than another, or +even the cessation of the use of a member which has lost its utility.</p> + +<p>We will look at some familiar examples of either case. Among vegetables, +which have no actions, and therefore no habits properly so called, great +differences in the development of the parts do none the less arise as a +consequence of changed circumstances; and these differences cause the +development of certain of them, while they attenuate others and cause +them to disappear. But all this is caused by changes in the nutrition of +the plant, in its absorptions and transpirations, in the quantity of +heat and light, of air and moisture, which it habitually receives; and, +lastly, by the superiority which certain of its vital movements may +assert over the others. There may arise between individuals of the same +species, of which some are placed in favourable, others amid +unfavourable, conditions, a difference which by degrees becomes very +notable.</p> + +<p>Suppose that circumstances keep certain individuals in an ill-nourished +or languid state. Their internal organisation will at length be +modified, and these individuals will engender offspring which will +perpetuate the<span class='pagenum'><a name="Page_181" id="Page_181">[Pg 181]</a></span> modifications thus acquired, and thus will in the end +give place to a race quite distinct from that of which the individual +members come together always under circumstances favourable to their +development.</p> + +<p>For instance, if a seed of some meadow flower is carried to dry and +stony ground, where it is exposed to the winds and there germinates, the +consequence will be that the plant and its immediate offspring, being +always ill-nourished, will give rise to a race really different from +that which lives in the field; yet this, none the less, will be its +progenitor. The individuals of this race will be dwarfed; and their +organs, some being increased at the expense of the rest, will show +distinctive proportions. What nature does in a long time we do every day +ourselves. Every botanist knows that the vegetables transplanted to our +gardens out of their native soil undergo such changes as render them at +last unrecognisable.</p> + +<p>Consider, again, the varieties among our domestic fowls and pigeons, all +of them brought into existence by being raised in diverse circumstances +and different countries, and such as might be sought in vain in a state +of nature. It is matter of common knowledge that if we raise a bird in a +cage, and keep it there for five or six years, it will be unable to fly +if restored to liberty. There has, indeed, been no change as yet in the +form of its members; but if for a long series of generations individuals +of the same race had been kept caged for a considerable time, there is +no room for doubt that the very form of their limbs would little by +little have undergone notable alteration. Much more would this be the +case if their captivity had been accompanied by a marked change of +climate, and if these individuals had by degrees accustomed themselves +to other sorts of food and to other measures for acquiring it. Such +circumstances, taken constantly together, would have formed insensibly a +new and clearly denned race.</p> + +<p>The following example shows, in regard to plants, how<span class='pagenum'><a name="Page_182" id="Page_182">[Pg 182]</a></span> the change of +some important circumstance may tend to change the various parts of +these living bodies.</p> + +<p>So long as the <i>ranunculus aquatilis</i>, the water buttercup, is under +water its leaves are all finely indented, and the divisions are +furnished with capillaries; but as soon as the stalk of the plant +reaches the surface the leaves, which develop in the air, are broadened +out, rounded, and simply lobed. If the plant manages to spring up in a +soil that is merely moist, and not covered with water, the stems will be +short, and none of the leaves will show these indentations and +capillaries. You have then the <i>ranunculus hederaceus</i>, which botanists +regard as a distinct species.</p> + +<p>Among animals changes take place more slowly, and it is therefore more +difficult to determine their cause. The strongest influence, no doubt, +is that of environment. Places far apart are different, and—which is +too commonly ignored—a given place changes its climate and quality with +time, though so slowly in respect of human life that we attribute to it +perfect stability. Hence it arises that we have not only extreme +changes, but also shadowy ones between the extremes.</p> + +<p>Everywhere the order of things changes so gradually that man cannot +observe the change directly, and the animal tribes in every place +preserve their habits for a long time; whence arises the apparent +constancy of what we call species—a constancy which has given birth in +us to the idea that these races are as old as nature.</p> + +<p>But the surface of the habitable globe varies in nature, situation, and +climate, in every variety of degrees. The naturalist will perceive that +just in proportion as the environment is notably changed will the +species change their characters.</p> + +<p>It must always be recognised:</p> + +<p>(1) That every considerable and constant change in the environment of a +race of animals works a real change in their wants.</p> + +<p><span class='pagenum'><a name="Page_183" id="Page_183">[Pg 183]</a></span></p><p>(2) That every change in their wants necessitates new actions to supply +them, and consequently new habits.</p> + +<p>(3) That every new want calling for new actions for its satisfaction +affects the animal in one of two ways. Either it has to make more +frequent use of some particular member, and this will develop the part +and cause it to increase in size; or it must employ new members which +will grow in the animal insensibly in response to the inward yearning to +satisfy these wants. And this I will presently prove from known facts.</p> + +<p>How the new wants have been able to attain satisfaction, and how the new +habits have been acquired, it will be easy to see if regard be had to +the two following laws, which observation has always confirmed.</p> + +<div class="blockquot"><p><span class="smcap">First Law.</span>—In every animal which has not arrived at the term of +its developments, the more frequent and sustained use of any organ +strengthens, develops, and enlarges that organ, and gives it a +power commensurate with the duration of this employment of it. On +the other hand, constant disuse of such organ weakens it by +degrees, causes it to deteriorate, and progressively diminishes its +faculties, so that in the end it disappears.</p> + +<p><span class="smcap">Second Law.</span>—All qualities naturally acquired by individuals as the +result of circumstances to which their race is exposed for a +considerable time, or as a consequence of a predominant employment +or the disuse of a certain organ, nature preserves to individual +offspring; provided that the acquired modifications are common to +the two sexes, or, at least, to both parents of the individual +offspring.</p></div> + +<p>Naturalists have observed that the members of animals are adapted to +their use, and thence have concluded hitherto that the formation of the +members has led to their appropriate employment. Now, this is an error. +For observation plainly shows that, on the contrary, the<span class='pagenum'><a name="Page_184" id="Page_184">[Pg 184]</a></span> development of +the members has been caused by their need and use; that these have +caused them to come into existence where they were wanting.</p> + +<p>But let us examine the facts which bear upon the effects of employment +or disuse of organs resulting from the habits which a race has been +compelled to form.</p> + + +<p class="subchap"><i>II.—The Penalties of Disuse</i></p> + +<p>Permanent disuse of an organ as a consequence of acquired habits +gradually impoverishes it, and in the end causes it to disappear, or +even annihilates it altogether.</p> + +<p>Thus vertebrates, which, in spite of innumerable particular +distinctions, are alike in the plan of their organisation, are generally +armed with teeth. Yet those of them which by circumstances have acquired +the habit of swallowing their prey without mastication have been liable +to leave their teeth undeveloped. Consequently, the teeth have either +remained hidden between the bony plates of the jaws, or have even been, +in the course of time, annihilated.</p> + +<p>The whale was supposed to have no teeth at all till M. Geoffrey found +them hidden in the jaws of the foetus. He has also found in birds the +groove in which teeth might be placed, but without any trace of the +teeth themselves. A similar case to that of the whale is the ant-eater +(<i>nyomecophaga</i>), which has long given up the practice of mastication.</p> + +<p>Eyes in the head are an essential part of the organisation of +vertebrates. Yet the mole, which habitually makes no use of the sense of +sight, has eyes so small that they can hardly be seen; and the aspalax, +whose habits-resemble a mole's, has totally lost its sight, and shows +but vestiges of eyes. So also the proteus, which inhabits dark caves +under water.</p> + +<p>In such cases, since the animals in question belong to a type of which +eyes are an essential part, it is clear that<span class='pagenum'><a name="Page_185" id="Page_185">[Pg 185]</a></span> the impoverishment, and +even the total disappearance, of these organs are the results of long +continued disuse.</p> + +<p>With hearing, the case is otherwise. Sound traverses everything. +Therefore, wherever an animal dwells it may exercise this faculty. And +so no vertebrate lacks it, and we never find it re-appearing in any of +the lower ranges. Sight disappears, re-appears, and disappears again, +according as circumstances deny or permit its exercise.</p> + +<p>Four legs attached to its skeleton are part of the reptile type; and +serpents, particularly as between them and the fishes come the +batrachians—frogs, etc.—ought to have four legs.</p> + +<p>But serpents, having acquired the habit of gliding along the ground, and +concealing themselves amid the grass, their bodies, as a consequence of +constantly repeated efforts to lengthen themselves out in order to pass +through narrow passages, have acquired considerable length of body which +is out of all proportion to their breadth.</p> + +<p>Now, feet would have been useless to these animals, and consequently +would have remained unemployed; for long legs would have interfered with +their desire to go on their bellies; and short legs, being limited in +number to four, would have been incapable of moving their bodies. Thus +total disuse among these races of animals has caused the parts which +have fallen into disuse totally to disappear.</p> + +<p>Many insects, which by their order and genus should have wings, lack +them more or less completely for similar reasons.</p> + + +<p class="subchap"><i>III.—The Advantages of Use</i></p> + +<p>The frequent use of an organ, if constant and habitual, increases its +powers, develops it, and makes it <span class='pagenum'><a name="Page_186" id="Page_186">[Pg 186]</a></span>acquire dimensions and potency such +as are not found among animals which use it less.</p> + +<p>Of this principle, the web-feet of some birds, the long legs and neck of +the stork, are examples. Similarly, the elongated tongue of the +ant-eater, and those of lizards and serpents.</p> + +<p>Such wants, and the sustained efforts to satisfy them, have also +resulted in the displacement of organs. Fishes which swim habitually in +great masses of water, since they need to see right and left of them, +have the eyes one upon either side of the head. Their bodies, more or +less flat, according to species, have their edges perpendicular to the +plane of the water; and their eyes are so placed as to be one on either +side of the flattened body. But those whose habits bring them constantly +to the banks, especially sloping banks, have been obliged to lie over +upon the flattened surface in order to approach more nearly. In this +position, in which more light falls on the upper than on the under +surface, and their attention is more particularly fixed upon what is +going on above than on what is going on below them, this want has forced +one of the eyes to undergo a kind of displacement, and to keep the +strange position which it occupies in the head of a sole or a turbot. +The situation is not symmetrical because the mutation is not complete. +In the case of the skate, however, it is complete; for in these fish the +transverse flattening of the body is quite horizontal, no less than that +of the head. And so the eyes of a skate are not only placed both of them +on the upper surface, but have become symmetrical.</p> + +<p>Serpents need principally to see things above them, and, in response to +this need, the eyes are placed so high up at the sides of the head that +they can see easily what is above them on either side, while they can +see in front of them but a very little distance. To compensate for this, +the tongue, with which they test bodies in their line of march, has been +rendered by this habit thin, long, and<span class='pagenum'><a name="Page_187" id="Page_187">[Pg 187]</a></span> very contractile, and even, in +most species, has been split so as to be able to test more than one +object at a time. The same custom has resulted similarly in the +formation of an opening at the end of the muzzle by which the tongue may +be protruded without any necessity for the opening of the jaws.</p> + +<p>The effect of use is curiously illustrated in the form and figure of the +giraffe. This animal, the largest of mammals, is found in the interior +of Africa, where the ground is scorched and destitute of grass, and has +to browse on the foliage of trees. From the continual stretching thus +necessitated over a great space of time in all the individuals of the +race, it has resulted that the fore legs have become longer than the +hind legs, and that the neck has become so elongated that the giraffe, +without standing on its hind legs, can raise its head to a height of +nearly twenty feet. Observation of all animals will furnish similar +examples.</p> + +<p>None, perhaps, is more striking than that of the kangaroo. This animal, +which carries its young in an abdominal pouch, has acquired the habit of +carrying itself upright upon its hind legs and tail, and of moving from +place to place in a series of leaps, during which, in order not to hurt +its little ones, it preserves its upright posture. Observe the result.</p> + +<p>(1) Its front limbs, which it uses very little, resting on them only in +the instant during which it quits its erect posture, have never acquired +a development in proportion to the other parts; they have remained thin, +little, and weak.</p> + +<p>(2) The hind legs, almost continually in action, whether to bear the +weight of the whole body or to execute its leaps, have, on the contrary, +obtained a considerable development; they are very big and very strong.</p> + +<p>(3) Finally, the tail, which we observe to be actively employed, both to +support the animal's weight and to execute its principal movements, has +acquired at its base<span class='pagenum'><a name="Page_188" id="Page_188">[Pg 188]</a></span> a thickness and a strength that are extremely +remarkable.</p> + +<p>When the will determines an animal to a certain action, the organs +concerned are forthwith stimulated by a flow of subtle fluids, which are +the determining cause of organic changes and developments. And +multiplied repetitions of such acts strengthen, extend, and even call +into being the organs necessary to them. Now, every change in an organ +which has been acquired by habitual use sufficient to originate it is +reproduced in the offspring if it is common to both the individuals +which have come together for the reproduction of their species. In the +end, this change is propagated and passes to all the individuals which +come after and are submitted to the same conditions, without its being +necessary that they should acquire it in the original manner.</p> + +<p>For the rest, in the union of disparate couples, the disparity is +necessarily opposed to the constant propagation of such qualities and +outward forms. This is why man, who is exposed to such diversity of +conditions, does not preserve and propagate the qualities or the +accidental defects which he has been in the way of acquiring. Such +peculiarities will be produced only in case two individuals who share +them unite; these will produce offspring bearing similar +characteristics, and, if successive generations restrict themselves to +similar unions, a distinct race will then be formed. But perpetual +intermixture will cause all characters acquired through particular +circumstances to disappear. If it were not for the distances which +separate the races of men, such intermixture would quickly obliterate +all national distinctions.</p> + + +<p class="subchap"><i>IV.—The Conclusion</i></p> + +<p>Here, then, is the conclusion to which we have come. It is a fact that +every genus and species of animal has its characteristic habits combined +with an organisation<span class='pagenum'><a name="Page_189" id="Page_189">[Pg 189]</a></span> perfectly in harmony with them. From the +consideration of this fact one of two conclusions must follow, and that +though neither of them can be proved.</p> + +<p>(1) The conclusion admitted hitherto—that nature (or its Author) in +creating the animals has foreseen all the possible sets of circumstances +in which they would have to live, has given to each species a constant +organisation, and has shaped its parts in a determined and invariable +way so that every species is compelled to live in the districts and the +climates where it is actually formed, and to keep the habits by which it +is actually known.</p> + +<p>(2) My own conclusion—that nature has produced in succession all the +animal species, beginning with the more imperfect, or the simpler, and +ending with the more perfect; that in so doing it has gradually +complicated their organisation; and that of these animals, dispersed +over the habitable globe, every species has acquired, under the +influence of the circumstances amid which it is found, the habits and +modifications of form which we associate with it.</p> + +<p>To prove that the second of these hypotheses is unfounded, it will be +necessary, first, to prove that the surface of the globe never varies in +character, in exposure, situation, whether elevated or sheltered, +climate, etc.; and, secondly, to prove that no part of the animal world +undergoes, even in the course of long periods of time, any modification +through change of circumstances, or as a consequence of a changed manner +of life and action.</p> + +<p>Now, a single fact which establishes that an animal, after a long period +of domestication, differs from the wild stock from which it derives, and +that among the various domesticated members of a species may be found +differences no less marked between individuals which, have been +subjected to one use and those which have been subjected to another, +makes it certain that the<span class='pagenum'><a name="Page_190" id="Page_190">[Pg 190]</a></span> former conclusion is not consistent with the +laws of nature, and that the second is.</p> + +<p>Everything, therefore, concurs to prove my assertion, to wit—that it is +not form, whether of the body or of the parts, which gives rise to the +habits of animals and their manner of life; but that, on the contrary, +in the habits, the manner of living, and all the other circumstances of +environment, we have those things which in the course of time have built +up animal bodies with all their members. With new forms new faculties +have been acquired, and little by little nature has come to shape +animals and all living things in their present forms.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_191" id="Page_191">[Pg 191]</a></span></p> +<h3>JOHANN LAVATER</h3> + +<p class="book"><big><a name="Physiognomical_Fragments" id="Physiognomical_Fragments"></a>Physiognomical Fragments</big></p> + +<div class="blockquot"><p>Johann Caspar Lavater, the Swiss theologian, poet, and +physiognomist, was born at Zürich on November 15, 1741. He began +his public life at the age of twenty-one as a political reformer. +Five years later he appeared as a poet, and published a volume of +poetry which was very favourably received. During the next five +years he produced a religious work, which was considered heretical, +although its mystic, religious enthusiasm appealed to a +considerable audience. His fame, however, rests neither on his +poetry nor on his theology, but on his physiognomical studies, +published in four volumes between 1775–78 under the title +"Physiognomical Fragments for the Advancement of Human Knowledge +and Human Life" ("Physiognomische Fragmente zur Beförderung des +Menschenkenntniss und Menschenliebe"). The book is diffuse and +inconsequent, but it contains many shrewd observations with respect +to physiognomy and has had no little influence on popular opinion +in this matter. Lavater died on January 2, 1801.</p></div> + + +<p class="subchap"><i>I.—The Truth of Physiognomy</i></p> + +<p><span class="smcap">There</span> can be no doubt of the truth of physiognomy. All countenances, all +forms, all created beings, are not only different from each other in +their classes, races, kinds, but are also individually distinct. It is +indisputable that all men estimate all things whatever by their external +temporary superficies—that is to say, by their physiognomy. Is not all +nature physiognomy, superficies and contents, body and spirit, external +effect and internal power? There is not a man who does not judge of all +things that pass through his hands by their physiognomy—there is not a +man who does not more or less, the first time he is in company with a +stranger, observe, estimate, compare, judge him according to +appearances. When each apple, each apricot, has a physiognomy <span class='pagenum'><a name="Page_192" id="Page_192">[Pg 192]</a></span>peculiar +to itself, shall man, the lord of the earth, have none?</p> + +<p>Man is the most perfect of all earthly creatures. In no other creature +are so wonderfully united the animal, the intellectual, and the moral. +And man's organisation peculiarly distinguishes him from all other +beings, and shows him to be infinitely superior to all those other +visible organisms by which he is surrounded. His head, especially his +face, convinces the accurate observer, who is capable of investigating +truth, of the greatness and superiority of his intellectual qualities. +The eye, the expression, the cheeks, the mouth, the forehead, whether +considered in a state of entire rest, or during their innumerable +varieties of motion—in fine, whatever is understood by physiognomy—are +the most expressive, the most convincing picture of interior sensations, +desires, passions, will, and of all those properties which so much exalt +moral above animal life.</p> + +<p>Although the physiological, intellectual, and moral are united in man, +yet it is plain that each of these has its peculiar station where it +more especially unfolds itself and acts.</p> + +<p>It is, beyond contradiction, evident that, though physiological or +animal life displays itself through all the body, and especially through +all the animal parts, yet it acts more conspicuously in the arm, from +the shoulder to the ends of the fingers.</p> + +<p>It is not less evident that intellectual life, or the powers of the +understanding and the mind, make themselves most apparent in the +circumference and form of the solid parts of the head, especially the +forehead; though they will discover themselves to the attentive and +accurate eye in every part and point of the human body, by the +congeniality and harmony of the various parts. Is there any occasion to +prove that the power of thinking resides not in the foot, nor in the +hand, nor in the back, but in the head and its internal parts?</p> + +<p><span class='pagenum'><a name="Page_193" id="Page_193">[Pg 193]</a></span></p><p>The moral life of man particularly reveals itself in the lines, marks, +and transitions of the countenance. His moral powers and desires, his +irritability, sympathy, and antipathy, his facility of attracting or +repelling the objects that surround him—these are all summed up in, and +painted upon, his countenance when at rest.</p> + +<p>Not only do mental and moral traits evince themselves in the +physiognomy, but also health and sickness; and I believe that by +repeatedly examining the firm parts and outlines of the bodies and +countenances of the sick, disease might be diagnosed, and even that +liability to disease might be predicted in particular cases.</p> + +<p>The same vital powers that make the heart beat and the fingers move, +roof the skull and arch the finger-nails. From the head to the back, +from the shoulder to the arm, from the arm to the hand, from the hand to +the finger, each depends on the other, and all on a determinate effect +of a determinate power. Through all nature each determinate power is +productive of only such and such determinate effects. The finger of one +body is not adapted to the hand of another body. The blood in the +extremity of the finger has the character of the blood in the heart. The +same congeniality is found in the nerves and in the bones. One spirit +lives in all. Each member of the body, too, is in proportion to the +whole of which it is a part. As from the length of the smallest member, +the smallest joint of the finger, the proportion of the whole, the +length and breadth of the body may be found; so also may the form of the +whole be found from the form of each single part. When the head is long, +all is long; when the head is round, all is round; when the head is +square, all is square.</p> + +<p>One form, one mind, one root appertain to all. Each organised body is so +much a whole that, without discord, destruction, or deformity, nothing +can be added or subtracted. Those, therefore, who maintain that +conclusion<span class='pagenum'><a name="Page_194" id="Page_194">[Pg 194]</a></span> cannot be drawn from a part to the whole labour under error, +failing to comprehend the harmony of nature.</p> + + +<p class="subchap"><i>II.—Physiognomy and the Features</i></p> + +<p>The Forehead. The form, height, arching, proportion, obliquity, and +position of the skull, or bone of the forehead, show the propensity of +thought, power of thought, and sensibility of man. The position, colour, +wrinkles, tension of the skin of the forehead, show the passions and +present state of the mind. The bones indicate the power, the skin the +application of power.</p> + +<p>I consider the outline and position of the forehead to be the most +important feature in physiognomy. We may divide foreheads into three +principal classes—the retreating, the perpendicular, and the +projecting, and each of these classes has a multitude of variations.</p> + +<p>A few facts with respect to foreheads may now be given.</p> + +<p>The higher the forehead, the more comprehension and the less activity.</p> + +<p>The more compressed, short, and firm the forehead, the more compression +and firmness, and the less volatility in the man.</p> + +<p>The more curved and cornerless the outline, the more tender and flexible +the character; and the more rectilinear, the more pertinacious and +severe the character.</p> + +<p>Perfect perpendicularity implies lack of understanding, but gently +arched at top, capacity for cold, tranquil, profound thought.</p> + +<p>A projecting forehead indicates imbecility, immaturity, weakness, +stupidity.</p> + +<p>A retreating forehead, in general, denotes superior imagination, wit, +acuteness.</p> + +<p>A forehead round and prominent above, straight below, and, on the whole, +perpendicular, shows much understanding, life, sensibility, ardour.</p> + +<p><span class='pagenum'><a name="Page_195" id="Page_195">[Pg 195]</a></span></p><p>An oblique, rectilinear forehead is ardent and vigorous.</p> + +<p>Arched foreheads appear properly to be feminine.</p> + +<p>A forehead neither too perpendicular nor too retreating, but a happy +mean, indicates the post-perfect character of wisdom.</p> + +<p>I might also state it as an axiom that straight lines considered as +such, and curves considered as such, are related as power and weakness, +obstinacy and flexibility, understanding and sensation.</p> + +<p>I have seen no man with sharp, projecting eyebones who was not inclined +to vigorous thinking and wise planning.</p> + +<p>Yet, even lacking sharpness, a head may be excellent if the forehead +sink like a perpendicular wall upon horizontal eyebrows, and be greatly +rounded towards the temples.</p> + +<p>Perpendicular foreheads, projecting so as not to rest immediately upon +the nose, and small, wrinkled, short, and shining, indicate little +imagination, little understanding, little sensation.</p> + +<p>Foreheads with many angular, knotty protuberances denote perseverance +and much vigorous, firm, harsh, oppressive, ardent activity.</p> + +<p>It is a sure sign of a clear, sound understanding and a good temperament +when the profile of the forehead has two proportionate arches, the lower +of which projects.</p> + +<p>Eyebones with well-marked, firm arches I never saw but in noble and +great men.</p> + +<p>Square foreheads with extensive temples and firm eyebones show +circumspection and steadiness of character.</p> + +<p>Perpendicular wrinkles, if natural, denote application and power. +Horizontal wrinkles and those broken in the middle or at the extremities +generally denote negligence or want of power.</p> + +<p>Perpendicular, deep indentings in the forehead <span class='pagenum'><a name="Page_196" id="Page_196">[Pg 196]</a></span>between the eyebrows, I +never met save in men of sound understanding and free and noble minds, +unless there were some positively contradictory feature.</p> + +<p>A blue frontal vein, in the form of a Y, when in an open, smooth, +well-arched forehead, I have only found in men of extraordinary talents +and of ardent and generous character.</p> + +<p>The following are the traits of a perfectly beautiful, intelligent, and +noble forehead.</p> + +<p>In length it must equal the nose, or the under part of the face. In +breadth it must be either oval at the top-like the foreheads of most of +the great men of England—or nearly square. It must be free from +unevenness and wrinkles, yet be able to wrinkle when deep in thought, +afflicted by pain, or moved by indignation. It must retreat above and +project beneath. The eyebones must be simple, horizontal, and, if seen +from above, must present a simple curve. There should be a small cavity +in the centre, from above to below, and traversing the forehead so as to +separate it into four divisions perceptible in a clear descending light. +The skin must be more clear on the forehead than in other parts of the +countenance.</p> + +<p>Foreheads short, wrinkled, and knotty, are incapable of durable +friendship.</p> + +<p>Be not discouraged though a friend, an enemy, a child, or a brother +transgress, for so long as he have a good, well-proportioned, open +forehead there is still hope of improvement.</p> + +<p><span class="smcap">The Eyes and Eyebrows.</span> Blue eyes are generally more indicative of +weakness and effeminacy than brown or black. Certainly there are many +powerful men with blue eyes, but I find more strength, manhood, thought +with brown.</p> + +<p>Choleric men have eyes of every colour, but rather brown or greenish +than blue. A propensity to green is an almost decisive token of ardour, +fire, and courage.</p> + +<p><span class='pagenum'><a name="Page_197" id="Page_197">[Pg 197]</a></span></p><p>Wide open eyes, with the white visible, I have often observed both in +the timid and phlegmatic, and in the courageous and rash.</p> + +<p>Meeting eyebrows were supposed to be the mark of craft, but I do not +believe them to have this significance. Angular, strong, interrupted +eyebrows denote fire and productive activity. The nearer the eyebrows to +the eyes, the more earnest, deep, and firm the character. Eyebrows +remote from each other denote warm, open, quick sensations. White +eyebrows signify weakness; and dark brown, firmness. The motion of the +eyebrows contains numerous expressions, especially of ignoble passions.</p> + +<p><span class="smcap">The Nose.</span> I have generally considered the nose the foundation or +abutment of the brain, for upon this the whole power of the arch of the +forehead rests. A beautiful nose will never be found accompanying an +ugly countenance. An ugly person may have fine eyes, but not a handsome +nose.</p> + +<p>I have never seen a nose with a broad back, whether arched or +rectilinear, that did not belong to an extraordinary man. Such a nose +was possessed by Swift, Cæsar Borgia, Titian, etc. Small nostrils are +usually an indubitable sign of unenterprising timidity. The open, +breathing nostril is as certain a token of sensibility.</p> + +<p><span class="smcap">The Mouth and Lips.</span> The contents of the mind are communicated to the +mouth. How full of character is the mouth! As are the lips, so is the +character. Firm lips, firm character; weak lips, weak character. +Well-defined, large, and proportionate lips, the middle line of which is +equally serpentine on both sides, and easy to be drawn, are never seen +in a bad, mean, common, false, vicious countenance. A lipless mouth, +resembling a single line, denotes coldness, industry, a love of order, +precision, house-wifery, and, if it be drawn upwards at the two ends, +affectation, pretension, vanity, malice. Very fleshy lips have always to +contend with sensuality and<span class='pagenum'><a name="Page_198" id="Page_198">[Pg 198]</a></span> indolence. Calm lips, well closed, without +constraint, and well delineated, certainly betoken consideration, +discretion, and firmness. Openness of mouth speaks complaint, and +closeness, endurance.</p> + +<p><span class="smcap">The Chin.</span> From numerous experiments, I am convinced that the projecting +chin ever denotes something positive, and the retreating something +negative. The presence or absence of strength in man is often signified +by the chin.</p> + +<p>I have never seen sharp indentings in the middle of the chin save in men +of cool understanding, unless when something evidently contradictory +appeared in the countenance. The soft, fat, double chin generally points +out the epicure; and the angular chin is seldom found save in discreet, +well-disposed, firm men. Flatness of chin speaks the cold and dry; +smallness, fear; and roundness, with a dimple, benevolence.</p> + +<p><span class="smcap">Skulls.</span> HOW much may the anatomist see in the mere skull of man! How +much more the physiognomist! And how much more still the anatomist who +is a physiognomist! If shown the bald head of Cæsar, as painted by +Rubens or Titian or Michael Angelo, what man would fail to notice the +rocky capacity which characterises it, and to realise that more ardour +and energy must be expected than from a smooth, round, flat head? How +characteristic is the skull of Charles XII.! How different from the +skull of his biographer Voltaire! Compare the skull of Judas with the +skull of Christ, after Holbein, and I doubt whether anyone would fail to +guess which is the skull of the wicked betrayer and which the skull of +the innocent betrayed. And who is unacquainted with the statement in +Herodotus that it was possible on the field of battle to distinguish the +skulls of the effeminate Medes from the skulls of the manly Persians? +Each nation, indeed, has its own characteristic skull.</p> + + +<p><span class='pagenum'><a name="Page_199" id="Page_199">[Pg 199]</a></span></p><p class="subchap"><i>III.—Nation, Sex, and Family</i></p> + +<p><span class="smcap">National Physiognomy.</span> It is undeniable that there is a national +physiognomy as well as national character. Compare a negro and an +Englishman, a native of Lapland and an Italian, a Frenchman and an +inhabitant of Tierra del Fuego. Examine their forms, countenances, +characters, and minds. This difference will be easily seen, though it +will sometimes be very difficult to describe it scientifically.</p> + +<p>The following infinitely little is what I have hitherto observed in the +foreigners with whom I have conversed.</p> + +<p>I am least able to characterise the French, They have no traits so bold +as the English, nor so minute as the Germans. I know them chiefly by +their teeth and their laugh. The Italians I discover by the nose, small +eyes, and projecting chin. The English by their foreheads and eyebrows. +The Dutch by the rotundity of their heads and the weakness of the hair. +The Germans by the angles and wrinkles round the eyes and in the cheeks. +The Russians by the snub nose and their light-coloured or black hair.</p> + +<p>I shall now say a word concerning Englishmen in particular. Englishmen +have the shortest and best-arched foreheads—that is to say, they are +arched only upwards, and, towards the eyebrows, either gently recline or +are rectilinear. They seldom have pointed, usually round, full noses. +Their lips are usually large, well defined, beautifully curved. Their +chins are round and full. The outline of their faces is in general +large, and they never have those numerous angles and wrinkles by which +the Germans are so especially distinguished. Their complexion is fairer +than that of the Germans.</p> + +<p>All Englishwomen whom I have known personally, or by portrait, appear to +be composed of marrow and nerve. They are inclined to be tall, slender, +soft, and as distant<span class='pagenum'><a name="Page_200" id="Page_200">[Pg 200]</a></span> from all that is harsh, rigorous, or stubborn as +heaven is from earth.</p> + +<p>The Swiss have generally no common physiognomy or national character, +the aspect of fidelity excepted. They are as different from each other +as nations the most remote.</p> + +<p><span class="smcap">The Physiognomical Relation of the Sexes.</span> Generally speaking, how much +more pure, tender, delicate, irritable, affectionate, flexible, and +patient is woman than man. The primary matter of which woman is +constituted appears to account for this difference. All her organs are +tender, yielding, easily wounded, sensible, and receptive; they are made +for maternity and affection. Among a thousand women, there is hardly one +without these feminine characteristics.</p> + +<p>This tenderness and sensibility, the light texture of their fibres and +organs, render them easy to tempt and to subdue, and yet their charms +are more potent than the strength of man. Truly sensible of purity, +beauty and symmetry, woman does not always take time to reflect on +spiritual life, spiritual death, spiritual corruption.</p> + +<p>The woman does not think profoundly; profound thought is the prerogative +of the man; but women feel more. They rule with tender looks, tears, and +sighs, but not with passion and threats, unless they are monstrosities. +They are capable of the sweetest sensibility, the deepest emotion, the +utmost humility, and ardent enthusiasm. In their faces are signs of +sanctity which every man honours.</p> + +<p>Owing to their extreme sensibility and their incapacity for accurate +inquiry and firm decision, they may easily become fanatics.</p> + +<p>The love of women, strong as it is, is very changeable; but their hatred +is almost incurable, and is only to be overcome by persistent and artful +flattery. Men usually see things as a whole, whereas women take more +interest in details.</p> + +<p><span class='pagenum'><a name="Page_201" id="Page_201">[Pg 201]</a></span></p><p>Women have less physical courage than men. Man hears the bursting +thunders, views the destructive bolt with serene aspect, and stands +erect amid the fearful majesty of the torrent. But woman trembles at the +lightning and thunder, and seeks refuge in the arms of man.</p> + +<p>Woman is formed for pity and religion; and a woman without religion is +monstrous; and a woman who is a freethinker is more disgusting than a +woman with a beard.</p> + +<p>Woman is not a foundation on which to build. She is the gold, silver, +precious stones, wood, hay, stubble—the materials for building on the +male foundation. She is the leaven, or, more expressly, she is oil to +the vinegar of man. Man singly is but half a man, only half human—a +king without a kingdom. Woman must rest upon the man, and man can be +what he ought to be only in conjunction with the woman.</p> + +<p>Some of the principal physiognomical contrasts may be summarised here.</p> + +<p>Man is the most firm; woman the most flexible.</p> + +<p>Man is the straightest; woman the most bending.</p> + +<p>Man stands steadfast; woman gently retreats.</p> + +<p>Man surveys and observes; woman glances and feels.</p> + +<p>Man is serious; woman is gay.</p> + +<p>Man is the tallest and broadest; woman the smallest and weakest.</p> + +<p>Man is rough and hard; woman is smooth and soft.</p> + +<p>Man is brown; woman is fair.</p> + +<p>The hair of the man is strong and short; the hair of woman is pliant and +long.</p> + +<p>Man has most straight lines; woman most curved.</p> + +<p>The countenance of man, taken in profile, is not so often perpendicular +as that of woman.</p> + +<p><span class="smcap">Family Physiognomy.</span> The resemblance between parents and children is very +commonly remarkable. Family physiognomical resemblance is as undeniable +as<span class='pagenum'><a name="Page_202" id="Page_202">[Pg 202]</a></span> national physiognomical resemblance. To doubt this is to doubt what +is self-evident.</p> + +<p>When children, as they increase in years, visibly increase in their +physical resemblance to their parents, we cannot doubt that resemblance +in character also increases. Howsoever much the character of children +may seem to differ from that of their parents, yet this difference will +be found to be due to great difference in external circumstances.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_203" id="Page_203">[Pg 203]</a></span></p> +<h3>JUSTUS VON LIEBIG</h3> + +<p class="book"><big><a name="Animal_Chemistry" id="Animal_Chemistry"></a>Animal Chemistry</big></p> + +<div class="blockquot"><p>Baron Freiherr Justus von Liebig, one of the most illustrious +chemists of his age, was born on May 12, 1803, at Darmstadt, +Germany, the son of a drysalter. It was in his father's business +that his interest in chemistry first awoke, and at fifteen he +became an apothecary's assistant. Subsequently, he went to +Erlangen, where he took his doctorate in 1822; and afterwards, in +Paris, was admitted to the laboratory of Gay-Lussac as a private +pupil. In 1824 he was appointed a teacher of chemistry in the +University of Giessen in his native state. Here he lived for +twenty-eight years a quiet life of incessant industry, while his +fame spread throughout Europe. In 1845 he was raised to the +hereditary rank of baron, and seven years later was appointed by +the Bavarian government to the professorship of chemistry in the +University of Munich. Here he died on April 18, 1873. The treatise +on "Animal Chemistry, or Organic Chemistry in its Relations to +Physiology and Pathology," published in 1842, sums up the results +of Liebig's investigations into the immediate products of animal +life. He was the first to demonstrate that the only source of +animal heat is that produced by the oxidation of the tissues.</p></div> + + +<p class="subchap"><i>I.—Chemical Needs of Life</i></p> + +<p><span class="smcap">Animals</span>, unlike plants, require highly organised atoms for nutriment; +they can subsist only upon parts of an organism. All parts of the animal +body are produced from the fluid circulating within its organism. A +destruction of the animal body is constantly proceeding, every motion is +the result of a transformation of its structure; every thought, every +sensation is accompanied by a change in the composition of the substance +of the brain. Food is applied either in the increase of the mass of a +structure (nutrition) or in the replacement of a structure wasted +(reproduction).</p> + +<p>Equally important is the continual absorption of oxygen<span class='pagenum'><a name="Page_204" id="Page_204">[Pg 204]</a></span> from the +atmosphere. All vital activity results from the mutual action of the +oxygen of the atmosphere and the elements of food. According to +Lavoisier, an adult man takes into his system every year 827 lb. of +oxygen, and yet he does not increase in weight. What, then, becomes of +this oxygen?—for no part of it is again expired as oxygen. The carbon +and hydrogen of certain parts of the body have entered into combination +with the oxygen introduced through the lungs and through the skin, and +have been given out in the form of carbonic acid and the vapour of +water.</p> + +<p>Now, an adult inspires 32<span class="above">1</span>⁄<span class="below">2</span> oz. of oxygen daily; this will convert the +carbon of 24 lb. of blood (80 per cent. water) into carbonic acid. He +must, therefore, take as much nutriment as will supply the daily loss. +And, in fact, it is found that he does so; for the average amount of +carbon in the daily food of an adult man is 14 oz., which requires 37 +oz. of oxygen for its conversion into carbonic acid. The amount of food +necessary for the support of the animal body must be in direct ratio to +the quantity of oxygen taken into the system. A bird deprived of food +dies on the third day; while a serpent, which inspires a mere trace of +oxygen, can live without food for three months. The number of +respirations is less in a state of rest than in exercise, and the amount +of food necessary in both conditions must vary also.</p> + +<p>The capacity of the chest being a constant quantity, we inspire the same +volume of air whether at the pole or at the equator; but the weight of +air, and consequently of oxygen, varies with the temperature. Thus, an +adult man takes into the system daily 46,000 cubic inches of oxygen, +which, if the temperature be 77° F., weighs 32<span class="above">1</span>⁄<span class="below">2</span> oz., but when the +temperature sinks to freezing-point will weigh 35 oz. It is obvious, +also, that in an equal number of respirations we consume more oxygen at +the level of the sea than on a mountain. The quantity of oxygen inspired +and carbonic acid expired must, therefore,<span class='pagenum'><a name="Page_205" id="Page_205">[Pg 205]</a></span> vary with the height of the +barometer. In our climate the difference between summer and winter in +the carbon expired, and therefore necessary for food, is as much as +one-eighth.</p> + + +<p class="subchap"><i>II.—The Cause of Animal Heat</i></p> + +<p>Now, the mutual action between the elements of food and the oxygen of +the air is the source of animal heat.</p> + +<p>This heat is wholly due to the combustion of the carbon and hydrogen in +the food consumed. Animal heat exists only in those parts of the body +through which arterial blood (and with it oxygen in solution) +circulates; hair, wool, or feathers, do not possess an elevated +temperature.</p> + +<p>As animal heat depends upon respired oxygen, it will vary according to +the respiratory apparatus of the animal. Thus the temperature of a child +is 102° F., while that of an adult is 99<span class="above">1</span>⁄<span class="below">2</span>° F. That of birds is higher +than that of quadrupeds or that of fishes or amphibia, whose proper +temperature is 3° F higher than the medium in which they live. All +animals, strictly speaking, are warm-blooded; but in those only which +possess lungs is their temperature quite independent of the surrounding +medium. The temperature of the human body is the same in the torrid as +in the frigid zone; but the colder the surrounding medium the greater +the quantity of fuel necessary to maintain its heat.</p> + +<p>The human body may be aptly compared to the furnace of a laboratory +destined to effect certain operations. It signifies nothing what +intermediate forms the food, or fuel, of the furnace may assume; it is +finally converted into carbonic acid and water. But in order to sustain +a fixed temperature in the furnace we must vary the quantity of fuel +according to the external temperature.</p> + +<p>In the animal body the food is the fuel; with a proper<span class='pagenum'><a name="Page_206" id="Page_206">[Pg 206]</a></span> supply of oxygen +we obtain the heat given out during its oxidation or combustion. In +winter, when we take exercise in a cold atmosphere, and when +consequently the amount of inspired oxygen increases, the necessity for +food containing carbon and hydrogen increases in the same ratio; and by +gratifying the appetite thus excited, we obtain the most efficient +protection against the most piercing cold. A starving man is soon frozen +to death; and everyone knows that the animals of prey in the Arctic +regions far exceed in voracity those in the torrid zone. In cold and +temperate climates, the air, which incessantly strives to consume the +body, urges man to laborious efforts in order to furnish the means of +resistance to its action, while in hot climates the necessity of labour +to provide food is far less urgent.</p> + +<p>Our clothing is merely the equivalent for a certain amount of food.</p> + +<p>The more warmly we are clothed the less food we require. If in hunting +or fishing we were exposed to the same degree of cold as the Samoyedes +we could with ease consume ten pounds of flesh, and perhaps half a dozen +tallow candles into the bargain. The macaroni of the Italian, and the +train oil of the Greenlander and the Russian, are fitted to administer +to their comfort in the climate in which they have been born.</p> + +<p>The whole process of respiration appears most clearly developed in the +case of a man exposed to starvation. Currie mentions the case of an +individual who was unable to swallow, and whose body lost 100 lb. in one +month. The more fat an animal contains the longer will it be able to +exist without food, for the fat will be consumed before the oxygen of +the air acts upon the other parts of the body.</p> + +<p>There are various causes by which force or motion may be produced. But +in the animal body we recognise as the ultimate cause of all force only +one cause, the chemical action which the elements of the food and the<span class='pagenum'><a name="Page_207" id="Page_207">[Pg 207]</a></span> +oxygen of the air mutually exercise on each other. The only known +ultimate cause of vital force, either in animals or in plants, is a +chemical process. If this be prevented, the phenomena of life do not +manifest themselves, or they cease to be recognisable by our senses. If +the chemical action be impeded, the vital phenomena must take new forms.</p> + +<p>The heat evolved by the combustion of carbon in the body is sufficient +to account for all the phenomena of animal heat. The 14 oz. of carbon +which in an adult are daily converted into carbonic acid disengage a +quantity of heat which would convert 24 lb. of water, at the temperature +of the body, into vapour. And if we assume that the quantity of water +vaporised through the skin and lungs amounts to 3 lb., then we have +still a large quantity of heat to sustain the temperature of the body.</p> + + +<p class="subchap"><i>III.—The Chemistry of Blood-Making</i></p> + +<p>Physiologists conceive that the various organs in the body have +originally been formed from blood. If this be admitted, it is obvious +that those substances alone can be considered nutritious that are +capable of being transformed into blood.</p> + +<p>When blood is allowed to stand, it coagulates and separates into a +watery fluid called serum, and into the clot, which consists principally +of fibrine. These two bodies contain, in all, seven elements, among +which sulphur, phosphorus, and nitrogen are found; they contain also the +earth of bones. The serum holds in solution common salt and other salts +of potash and soda, of which the acids are carbonic, phosphoric, and +sulphuric acids. Serum, when heated, coagulates into a white mass called +albumen. This substance, along with the fibrine and a red colouring +matter in which iron is a constituent, constitute the globules of blood.</p> + +<p>Analysis has shown that fibrine and albumen are <span class='pagenum'><a name="Page_208" id="Page_208">[Pg 208]</a></span>perfectly identical in +chemical composition. They may be mutually converted into each other. In +the process of nutrition both may be converted into muscular fibre, and +muscular fibre is capable of being reconverted into blood.</p> + +<p>All parts of the animal body which form parts of organs contain +nitrogen. The principal ingredients of blood contain 17 per cent. of +nitrogen, and there is no part of an active organ that contains less +than 17 per cent. of this element.</p> + +<p>The nutritive process is simplest in the case of the carnivora, for +their nutriment is chemically identical in composition with their own +tissues. The digestive apparatus of graminivorous animals is less +simple, and their food contains very little nitrogen. From what +constituents of vegetables is their blood produced?</p> + +<p>Chemical researches have shown that all such parts of vegetables as can +afford nutriment to animals contain certain constituents which are rich +in nitrogen; and experience proves that animals require for their +nutrition less of these parts of plants in proportion as they abound in +the nitrogenised constituents. These important products are specially +abundant in the seeds of the different kinds of grain, and of peas, +beans, and lentils. They exist, however, in all plants, without +exception, and in every part of plants in larger or smaller quantity. +The nitrogenised compounds of vegetables are called vegetable fibrine, +vegetable albumen, and vegetable casein. All other nitrogenised +compounds occurring in plants are either rejected by animals or else +they occur in the food in such very small proportion that they cannot +possibly contribute to the increase of mass in the animal body.</p> + +<p>The chemical analysis of these three substances has led to the +interesting result that they contain the same organic elements, united +in the same proportion by weight; and—which is more remarkable—that +they are identical in composition with the chief constituents of +blood—animal fibrine and animal albumen. By identity, be it <span class='pagenum'><a name="Page_209" id="Page_209">[Pg 209]</a></span>remarked, +is not here meant merely similarity, but that even in regard to the +presence and relative amounts of sulphur, phosphorus, and phosphate of +lime no difference can be observed.</p> + +<p>How beautifully simple then, by the aid of these discoveries, appears +the process of nutrition in animals, the formation of their organs, in +which vitality chiefly resides. Those vegetable constituents which are +used by animals to form blood contain the essential ingredients of blood +ready formed. In point of fact, vegetables produce in their organism the +blood of all animals; for the carnivora, in consuming the blood and +flesh of the graminivora, consume, strictly speaking, the vegetable +principles which have served for the nourishment of the latter. In this +sense we may say the animal organism gives to blood only its form; and, +further, that it is incapable of forming blood out of other compounds +which do not contain the chief ingredients of that fluid.</p> + +<p>Animal and vegetable life are, therefore, closely related, for the first +substance capable of affording nutriment to animals is the last product +of the creative energy of vegetables. The seemingly miraculous in the +nutritive power of vegetables disappears in a great degree, for the +production of the constituents of blood cannot appear more surprising +than the occurrence of the principal ingredient of butter in palm-oil +and of horse-fat and train-oil in certain of the oily seeds.</p> + + +<p class="subchap"><i>IV.—Food the Fuel of Life</i></p> + +<p>We have still to account for the use in food of substances which are +destitute of nitrogen but are known to be necessary to animal life. Such +substances are starch, sugar, gum, and pectine. In all of these we find +a great excess of carbon, with oxygen and hydrogen in the same +proportion as water. They therefore add an excess of carbon to the +nitrogenised constituents of food,<span class='pagenum'><a name="Page_210" id="Page_210">[Pg 210]</a></span> and they cannot possibly be employed +in the production of blood, because the nitrogenised compounds contained +in the food already contain exactly the amount of carbon which is +required for the production of fibrine and albumen. Now, it can be shown +that very little of the excess of this carbon is ever expelled in the +form either of solid or liquid compounds; it must be expelled, +therefore, in the gaseous state. In short, these compounds are solely +expended in the production of animal heat, being converted by the oxygen +of the air into carbonic acid and water. The food of carnivorous animals +does not contain non-nitrogenised matters, so that the carbon and +hydrogen necessary for the production of animal heat are furnished in +them from the waste of their tissues.</p> + +<p>The transformed matters of the organs are obviously unfit for the +further nourishment of the body—that is, for the increase or +reproduction of the mass. They pass through the absorbent and lymphatic +vessels into the veins, and their accumulation in these would soon put a +stop to the nutritive process were it not that the blood has to pass +through a filtering apparatus, as it were, before reaching the heart. +The venous blood, before returning to the heart, is made to pass through +the liver and the kidneys, which separate from it all substances +incapable of contributing to nutrition. The new compounds containing the +nitrogen of the transformed organs, being utterly incapable of further +application in the system, are expelled from the body. Those which +contain the carbon of the transformed tissues are collected in the +gall-bladder as bile, a compound of soda which, being mixed with water, +passes through the duodenum and mixes with chyme. All the soda of the +bile, and ninety-nine-hundredths of the carbonaceous matter which it +contains, retain the capacity of re-absorption by the absorbents of the +small and large intestines—a capacity which has been proved by direct +experiment.</p> + +<p><span class='pagenum'><a name="Page_211" id="Page_211">[Pg 211]</a></span></p><p>The globules of the blood, which in themselves can be shown to take no +share in the nutritive process, serve to transport the oxygen which they +give up in their passage through the capillary vessels. Here the current +of oxygen meets with the carbonaceous substances of the transformed +tissues, and converts their carbon into carbonic acid, their hydrogen +into water. Every portion of these substances which escapes this process +of oxidation is sent back into the circulation in the form of bile, +which by degrees completely disappears.</p> + +<p>It is obvious that in the system of the graminivora, whose food contains +relatively so small a proportion of the constituents of blood, the +process of metamorphosis in existing tissues, and consequently their +restoration or reproduction, must go on far less rapidly than in the +carnivora. Otherwise, a vegetation a thousand times as luxuriant would +not suffice for their sustenance. Sugar, gum, and starch, which form so +large a proportion of their food, would then be no longer necessary to +support life in these animals, because in that case the products of +waste, or metamorphosis of organised tissues, would contain enough +carbon to support the respiratory process.</p> + +<p>When exercise is denied to graminivorous and omnivorous animals this is +tantamount to a deficient supply of oxygen. The carbon of the food, not +meeting with a sufficient supply of oxygen to consume it, passes into +other compounds containing a large excess of carbon—or, in other words, +fat is produced. Fat is thus an abnormal production, resulting from a +disproportion of carbon in the food to that of the oxygen respired by +the lungs or absorbed by the skin. Wild animals in a state of nature do +not contain fat. The production of fat is always a consequence of a +deficient supply of oxygen, for oxygen is absolutely indispensable for +the dissipation of excess of carbon in the food.</p> + + +<p><span class='pagenum'><a name="Page_212" id="Page_212">[Pg 212]</a></span></p><p class="subchap"><i>V.—Animal Life-Chemistry</i></p> + +<p>The substances of which the food of man is composed may be divided into +two classes—into nitrogenised and non-nitrogenised. The former are +capable of conversion into blood, the latter incapable of this +transformation. Out of those substances which are adapted to the +formation of blood are formed all the organised tissues. The other class +of substances in the normal state of health serve to support the process +of respiration. The former may be called the plastic elements of +nutrition; the latter, elements of respiration.</p> + +<p>Among the former we may reckon—vegetable fibrine, vegetable albumen, +vegetable casein, animal flesh, animal blood.</p> + +<p>Among the elements of respiration in our food are—fat, starch, gum, +cane sugar, grape-sugar, sugar of milk, pectine, bassorine, wine, beer, +spirits.</p> + +<p>The nitrogenised constituents of vegetable food have a composition +identical with that of the constituents of the blood.</p> + +<p>No nitrogenised compound the composition of which differs from that of +fibrine, albumen, and casein, is capable of supporting the vital process +in animals.</p> + +<p>The animal organism undoubtedly possesses the power of forming from the +constituents of its blood the substance of its membranes and cellular +tissue, of the nerves and brain, of the organic part of cartilages and +bones. But the blood must be supplied to it ready in everything but its +form—that is, in its chemical composition. If this is not done, a +period is put to the formation of blood, and, consequently, to life.</p> + +<p>The whole life of animals consists of a conflict between chemical forces +and the vital power. In the normal state of the body of an adult these +stand in equilibrium: that is, there is equilibrium between the +<span class='pagenum'><a name="Page_213" id="Page_213">[Pg 213]</a></span>manifestations of the causes of waste and the causes of supply. Every +mechanical or chemical agency which disturbs the restoration of this +equilibrium is a cause of disease.</p> + +<p>Death is that condition in which chemical or mechanical powers gain the +ascendancy, and all resistance on the part of the vital force ceases. +This resistance never entirely departs from living tissues during life. +Such deficiency in resistance is, in fact, a deficiency in resistance to +the action of the oxygen of the atmosphere.</p> + +<p>Disease occurs when the sum of vital force, which tends to neutralise +all causes of disturbance, is weaker than the acting cause of +disturbance.</p> + +<p>Should there be formed in the diseased parts, in consequence of the +change of matter, from the elements of the blood or of the tissue, new +products which the neighbouring parts cannot employ for their own vital +functions; should the surrounding parts, moreover, be unable to convey +these products to other parts where they may undergo transformation, +then these new products will suffer, at the place where they have been +formed, a process of decomposition analogous to putrefaction.</p> + +<p>In certain cases, medicine removes these diseased conditions by exciting +in the vicinity of the diseased part, or in any convenient situation, an +artificial diseased state (as by blisters), thus diminishing by means of +artificial disturbance the resistance offered to the external causes of +change in these parts by the vital force. The physician succeeds in +putting an end to the original diseased condition when the disturbance +artificially excited (or the diminution of resistance in another part) +exceeds in amount the diseased state to be overcome.</p> + +<p>The accelerated change of matter and the elevated temperature in the +diseased part show that the resistance offered by the vital force to the +action of oxygen is feebler than in the healthy state. But this +resistance only ceases entirely when death takes place. By the +artificial<span class='pagenum'><a name="Page_214" id="Page_214">[Pg 214]</a></span> diminution of resistance in another part, the resistance in +the diseased organ is not, indeed, directly strengthened; but the +chemical action, the cause of the change of matter, is diminished in the +diseased part, being directed to another part, where the physician has +succeeded in producing a still more feeble resistance to the change of +matter, to the action of oxygen.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_215" id="Page_215">[Pg 215]</a></span></p> +<h3>SIR CHARLES LYELL</h3> + +<p class="book"><big><a name="The_Principles_of_Geology" id="The_Principles_of_Geology"></a>The Principles of Geology</big></p> + +<div class="blockquot"><p>Sir Charles Lyell, the distinguished geologist, was born at +Kinnordy, Forfarshire, Scotland, Nov. 14, 1797. It was at Oxford +that his scientific interest was first aroused, and after taking an +M.A. degree in 1821 he continued his scientific studies, becoming +an active member of the Geological and Linnæan Societies of London. +In 1826 he was elected a fellow of the Royal Society, and two years +later went with Sir Roderick Murchison on a tour of Europe, and +gathered evidence for the theory of geological uniformity which he +afterwards promulgated. In 1830 he published his great work, +"Principles of Geology: Being an Attempt to Explain the Former +Changes of the Earth's Surface by References to Causes now in +Action," which converted almost the whole geological world to the +doctrine of uniformitarianism, and may be considered the foundation +of modern geology. Lyell died in London on February 22, 1875. +Besides his great work, he also published "The Elements of +Geology," "The Antiquity of Man," "Travels in North America," and +"The Student's Elements of Geology."</p></div> + + +<p class="subchap"><i>I.—Uniformity in Geological Development</i></p> + +<p><span class="smcap">According</span> to the speculations of some writers, there have been in the +past history of the planet alternate periods of tranquillity and +convulsion, the former enduring for ages, and resembling the state of +things now experienced by man; the other brief, transient, and +paroxysmal, giving rise to new mountains, seas, and valleys, +annihilating one set of organic beings, and ushering in the creation of +another. These theories, however, are not borne out by a fair +interpretation of geological monuments; but, on the contrary, nature +indicates no such cataclysms, but rather progressive uniformity.</p> + +<p>Igneous rocks have been supposed to afford evidence of ancient paroxysms +of nature, but we cannot consider<span class='pagenum'><a name="Page_216" id="Page_216">[Pg 216]</a></span> igneous rocks proof of any +exceptional paroxysms. Rather, we find ourselves compelled to regard +igneous rocks as an aggregate effect of innumerable eruptions, of +various degrees of violence, at various times, and to consider mountain +chains as the accumulative results of these eruptions. The incumbent +crust of the earth is never allowed to attain that strength and +coherence which would be necessary in order to allow the volcanic force +to accumulate and form an explosive charge capable of producing a grand +paroxysmal eruption. The subterranean power, on the contrary, displays, +even in its most energetic efforts, an intermittent and mitigated +intensity. There are no proofs that the igneous rocks were produced more +abundantly at remote periods.</p> + +<p>Nor can we find proof of catastrophic discontinuity when we examine +fossil plants and fossil animals. On the contrary, we find a progressive +development of organic life at successive geological periods.</p> + +<p>In Palæozoic strata the entire want of plants of the most complex +organisation is very striking, for not a single dicotyledonous +angiosperm has yet been found, and only one undoubted monocotyledon. In +Secondary, or Mesozoic, times, palms and some other monocotyledons +appeared; but not till the Upper Cretaceous era do we meet with the +principal classes and orders of the vegetable kingdom as now known. +Through the Tertiary ages the forms were perpetually changing, but +always becoming more and more like, generically and specifically, to +those now in being. On the whole, therefore, we find progressive +development of plant life in the course of the ages.</p> + +<p>In the case of animal life, progression is equally evident. +Palæontological research leads to the conclusion that the invertebrate +animals flourished before the vertebrate, and that in the latter class +fish, reptiles, birds, and mammalia made their appearance in a +chronological order analogous to that in which they would be arranged<span class='pagenum'><a name="Page_217" id="Page_217">[Pg 217]</a></span> +zoologically according to an advancing scale of perfection in their +organisation. In regard to the mammalia themselves, they have been +divided by Professor Owen into four sub-classes by reference to +modifications of their brain. The two lowest are met with in the +Secondary strata. The next in grade is found in Tertiary strata. And the +highest of all, of which man is the sole representative, has not yet +been detected in deposits older than the Post-Tertiary.</p> + +<p>It is true that in passing from the older to the newer members of the +Tertiary system we meet with many chasms, but none which separate +entirely, by a broad line of demarcation, one state of the organic world +from another. There are no signs of an abrupt termination of one fauna +and flora, and the starting into life of new and wholly distinct forms. +Although we are far from being able to demonstrate geologically an +insensible transition from the Eocene to the Miocene, or even from the +latter to the recent fauna, yet the more we enlarge and perfect our +general survey the more nearly do we approximate to such a continuous +series, and the more gradually are we conducted from times when many of +the genera and nearly all the species were extinct to those in which +scarcely a single species flourished which we do not know to exist at +present. We must remember, too, that many gaps in animal and floral life +were due to ordinary climatic and geological factors. We could, under no +circumstances, expect to meet with a complete ascending series.</p> + +<p>The great vicissitudes in climate which the earth undoubtedly +experienced, as shown by geological records, have been held to be +themselves proof of sudden violent revolutions in the life-history of +the world. But all the great climatic vicissitudes can be accounted for +by the action of factors still, in operation—subsidences and elevations +of land, alterations in the relative proportions and position of land +and water, variations in the relative<span class='pagenum'><a name="Page_218" id="Page_218">[Pg 218]</a></span> position of our planet to the sun +and other heavenly bodies.</p> + +<p>Altogether, the conclusion is inevitable that from the remotest period +there has been one uniform and continuous system of change in the +animate and inanimate world, and accordingly every fact collected +respecting the factors at present at work in forming and changing the +world, affords a key to the interpretation of its part. And thus, +although we are mere sojourners on the surface of the planet, chained to +a mere point in space, enduring but for a moment of time, the human mind +is enabled not only to number worlds beyond the unassisted ken of mortal +eye, but to trace the events of indefinite ages before the creation of +our race, and to penetrate into the dark secrets of the ocean and the +heart of the solid globe.</p> + + +<p class="subchap"><i>II.—Changes in the Inorganic World now in Progress</i></p> + +<p>The great agents of change in the inorganic world may be divided into +two principal classes—the aqueous and the igneous. To the aqueous +belong rain, rivers, springs, currents, and tides, and the action of +frost and snow; to the igneous, volcanoes and earthquakes. Both these +classes are instruments of degradation as well as of reproduction. But +they may also be regarded as antagonist forces, since the aqueous agents +are incessantly labouring to reduce the inequalities of the earth's +surface to a level; while the igneous are equally active in restoring +the unevenness of the external crust, partly by heaping up new matter in +certain localities, and partly by depressing one portion of the earth's +envelope and forcing out another.</p> + +<p>We will treat in the first place of the aqueous agents.</p> + +<p><span class="smcap">Rain and Rivers.</span> When one considers that in some parts of the world as +much as 500 or 600 inches of rain<span class='pagenum'><a name="Page_219" id="Page_219">[Pg 219]</a></span> may fall annually, it is easy to +believe that rain <i>qua</i> rain may be a denuding and plastic agent, and in +some parts of the world we find evidence of its action in earth pillars +or pyramids. The best example of earth pillars is seen near Botzen, in +the Tyrol, where there are hundreds of columns of indurated mud, varying +in height from 20 feet to 100 feet. These columns are usually capped by +a single stone, and have been separated by rain from the terrace of +which they once formed a part.</p> + +<p>As a rule, however, rain acts through rivers. The power of rivers to +denude and transport is exemplified daily. Even a comparatively small +stream when swollen by rain may move rocks tons in weight, and may +transport thousands of tons of gravel. The greatest damage is done when +rivers are dammed by landslips or by ice. In 1818 the River Dranse was +blocked by ice, and its upper part became a lake. In the hot season the +barrier of ice gave way, and the torrent swept before it rocks, forests, +houses, bridges, and cultivated land. For the greater part of its course +the flood resembled a moving mass of rock and mud rather than of water. +Some fragments of granite rock of enormous size, which might be compared +to houses, were torn out and borne down for a quarter of a mile.</p> + +<p>The rivers of unmelted ice called the glaciers act more slowly, but they +also have the power of transporting gravel, sand, and boulders to great +distances, and of polishing and scoring their rocky channels. Icebergs, +too, are potent geological agents. Many of them are loaded with 50,000 +to 100,000 tons of rock and earth, which they may carry great distances. +Also in their course they must break, and polish, and scratch the peaks +and points of submarine mountains.</p> + +<p>Coast ice, likewise, may transport rocks and earth. Springs also must be +considered as geological agents affecting the face of the globe.</p> + +<p>But running water not only denudes it, but also creates<span class='pagenum'><a name="Page_220" id="Page_220">[Pg 220]</a></span> land, for +lakes, seas, rivers are seen to form deltas. That Egypt was the gift of +the Nile was the opinion of the Egyptian priests, and there can be no +doubt that the fertility of the alluvial plain above Cairo, and the very +existence of the delta below that city, are due to the action of that +great river, and to its power of transporting mud from the interior of +Africa and depositing it on its inundated plains as well as on that +space which has been reclaimed from the Mediterranean and converted into +land. The delta of the Ganges and Brahmapootra is more than double that +of the Nile. Even larger is the delta of the Mississippi, which has been +calculated to be 12,300 square miles in area.</p> + +<p><span class="smcap">Tides and Currents.</span> The transporting and destroying and constructive +power of tides and currents is, in many respects, analogous to that of +rivers, but extends to wider areas, and is, therefore, of more +geological importance. The chief influence of the ocean is exerted at +moderate depths below the surface on all areas which are slowly rising, +or attempting, as it were, to rise above the sea; but its influence is +also seen round the coast of every continent and island.</p> + +<hr /> + +<p>We shall now consider the igneous agents that act on the earth's +surface. These agents are chiefly volcanoes and earthquakes, and we find +that both usually occur in particular parts of the world. At various +times and at various places within historical times volcanic eruptions +and earthquakes have both proved their potency to alter the face of the +earth.</p> + +<p>The principal geological facts and theories with regard to volcanoes and +earthquakes are as follows.</p> + +<p>The primary causes of the volcano and the earthquake are to a great +extent the same, and connected with the development of heat and chemical +action at various depths in the interior of the globe.</p> + +<p><span class='pagenum'><a name="Page_221" id="Page_221">[Pg 221]</a></span></p><p>Volcanic heat has been supposed to be the result of the original high +temperature of the molten planet, and the planet has been supposed to +lose heat by radiation. Recent inquiries, however, suggest that the +apparent loss of heat may arise from the excessive local development of +volcanic action.</p> + +<p>Whatever the original shape of our planet, it must in time have become +spheroidal by the gradual operation of centrifugal force acting on +yielding materials brought successively within its action by aqueous and +igneous causes.</p> + +<p>The heat in mines and artesian wells increases as we descend, but not in +uniform ratio in different regions. Increase at a uniform ratio would +imply such heat in the central nucleus as must instantly fuse the crust.</p> + +<p>Assuming that there are good astronomical grounds for inferring the +original fluidity of the planet, yet such pristine fluidity need not +affect the question of volcanic heat, for the volcanic action of +successive periods belongs to a much more modern state of the globe, and +implies the melting of different parts of the solid crust one after the +other.</p> + +<p>The supposed great energy of the volcanic forces in the remoter periods +is by no means borne out by geological observations on the quantity of +lava produced by single eruptions in those several periods.</p> + +<p>The old notion that the crystalline rocks, whether stratified or +unstratified, such as granite and gneiss, were produced in the lower +parts of the earth's crust at the expense of a central nucleus slowly +cooling from a state of fusion by heat has now had to be given up, now +that granite is found to be of all ages, and now that we know the +metamorphic rocks to be altered sedimentary strata, implying the +denudation of a previously solidified crust.</p> + +<p>The powerful agency of steam or aqueous vapour in volcanic eruptions +leads us to compare its power of propelling lava to the surface with +that which it exerts in<span class='pagenum'><a name="Page_222" id="Page_222">[Pg 222]</a></span> driving water up the pipe of an Icelandic +geyser. Various gases also, rendered liquid by pressure at great depths, +may aid in causing volcanic outbursts, and in fissuring and convulsing +the rocks during earthquakes.</p> + +<p>The chemical character of the products of recent eruptions suggests that +large bodies of salt water gain access to the volcanic foci. Although +this may not be the primary cause of volcanic eruptions, which are +probably due to the aqueous vapour intimately mixed with molten rock, +yet once the crust is shattered through, the force and frequency of +eruptions may depend in some measure on the proximity of large bodies of +water.</p> + +<p>The permanent elevation and subsidence of land now observed, and which +may have been going on through past ages, may be connected with the +expansion and contraction of parts of the solid crust, some of which +have been cooling from time to time, while others have been gaining +heat.</p> + +<p>In the preservation of the average proportion of land and sea, the +igneous agents exert a conservative power, restoring the unevenness of +the surface which the levelling power of water in motion would tend to +destroy. If the diameter of the planet remains always the same, the +downward movements of the crust must be somewhat in excess, to +counterbalance the effects of volcanoes and mineral springs, which are +always ejecting material so as to raise the level of the surface of the +earth. Subterranean movements, therefore, however destructive they may +be during great earthquakes, are essential to the well-being of the +habitable surface, and even to the very existence of terrestrial and +aquatic species.</p> + + +<p class="subchap"><i>III.—Changes of the Organic World now in Progress</i></p> + +<p>In 1809 Lamarck introduced the idea of transmutation of species, +suggesting that by changes in habitat, climate, and manner of living one +species may, in the course of<span class='pagenum'><a name="Page_223" id="Page_223">[Pg 223]</a></span> generations, be transformed into a new +and distinct species.</p> + +<p>In England, however, the idea remained dormant till in 1844 a work +entitled the "Vestiges of Creation" reinforced it with many new facts. +In this work the unity of plan exhibited by the whole organic creation, +fossil and recent, and the mutual affinities of all the different +classes of the animal and vegetable kingdoms, were declared to be in +harmony with the idea of new forms having proceeded from older ones by +the gradually modifying influence of environment. In 1858 the theory was +put on a new and sound basis by Wallace and Darwin, who added the +conception of natural selection, suggesting that variations in species +are naturally produced, and that the variety fittest to survive in the +severe struggle for existence must survive, and transmit the +advantageous variation, implying the gradual evolution of new species. +Further, Darwin showed that other varieties may be perpetuated by sexual +selection.</p> + +<p>On investigating the geographical distribution of animals and plants we +find that the extent to which the species of mammalia, birds, insects, +landshells, and plants (whether flowering or cryptogamous) agree with +continental species; or the degree in which those of different islands +of the same group agree with each other has an unmistakable relation to +the known facilities enjoyed by each class of crossing the ocean. Such a +relationship accords well with the theory of variation and natural +selection, but with no other hypothesis yet suggested for explaining the +origin of species.</p> + +<p>From what has been said of the changes which are always going on in the +habitable surface of the world, and the manner in which some species are +constantly extending their range at the expense of others, it is evident +that the species existing at any particular period may, in the course of +ages, become extinct one after the other.</p> + +<p><span class='pagenum'><a name="Page_224" id="Page_224">[Pg 224]</a></span></p><p>If such, then, be the law of the organic world, if every species is +continually losing some of its varieties, and every genus some of its +species, it follows that the transitional links which once, according to +the doctrine of transmutation, must have existed, will, in the great +majority of cases, be missing. We learn from geological investigations +that throughout an indefinite lapse of ages the whole animate creation +has been decimated again and again. Sometimes a single representative +alone remains of a type once dominant, or of which the fossil species +may be reckoned by hundreds. We rarely find that whole orders have +disappeared, yet this is notably the case in the class of reptiles, +which has lost some orders characterised by a higher organisation than +any now surviving in that class. Certain genera of plants and animals +which seem to have been wholly wanting, and others which were feebly +represented in the Tertiary period, are now rich in species, and appear +to be in such perfect harmony with the present conditions of existence +that they present us with countless varieties, confounding the zoologist +or botanist who undertakes to describe or classify them.</p> + +<p>We have only to reflect on the causes of extinction, and we at once +foresee the time when even in these genera so many gaps will occur, so +many transitional forms will be lost, that there will no longer be any +difficulty in assigning definite limits to each surviving species. The +blending, therefore, of one generic or specific form into another must +be an exception to the general rule, whether in our own time or in any +period of the past, because the forms surviving at any given moment will +have been exposed for a long succession of antecedent periods to those +powerful causes of extinction which are slowly but incessantly at work +in the organic and inorganic worlds.</p> + +<p>They who imagine that, if the theory of transmutation be true, we ought +to discover in a fossil state all<span class='pagenum'><a name="Page_225" id="Page_225">[Pg 225]</a></span> the intermediate links by which the +most dissimilar types have been formerly connected together, expect a +permanence and completeness of records such as is never found. We do not +find even that all recently extinct plants have left memorials of their +existence in the crust of the earth; and ancient archives are certainly +extremely defective. To one who is aware of the extreme imperfection of +the geological record, the discovery of one or two missing links is a +fact of small significance; but each new form rescued from oblivion is +an earnest of the former existence of hundreds of species, the greater +part of which are irrevocably lost.</p> + +<p>A somewhat serious cause of disquiet and alarm arises out of the +supposed bearing of this doctrine of the origin of species by +transmutation on the origin of man, and his place in nature. It is +clearly seen that there is such a close affinity, such an identity in +all essential points, in our corporeal structure, and in many of our +instincts and passions with those of the lower animals—that man is so +completely subjected to the same general laws of reproduction, increase, +growth, disease, and death—that if progressive development, spontaneous +variation, and natural selection have for millions of years directed the +changes of the rest of the organic world, we cannot expect to find that +the human race has been exempted from the same continuous process of +evolution.</p> + +<p>Such a near bond of connection between man and the rest of the animate +creation is regarded by many as derogatory to our dignity. But we have +already had to exchange the pleasing conceptions indulged in by poets +and theologians as to the high position in the scale of being held by +our early progenitors for humble and more lowly beginnings, the joint +labours of the geologist and archæologist having left us in no doubt of +the ignorance and barbarism of Palæolithic man.</p> + +<p>It is well, too, to remember that the high place we have reached in the +scale of being has been gained step by<span class='pagenum'><a name="Page_226" id="Page_226">[Pg 226]</a></span> step, by a conscientious study +of natural phenomena, and by fearlessly teaching the doctrines to which +they point. It is by faithfully weighing evidence without regard to +preconceived notions, by earnestly and patiently searching for what is +true, not what we wish to be true, that we have attained to that +dignity, which we may in vain hope to claim through the rank of an ideal +parentage.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_227" id="Page_227">[Pg 227]</a></span></p> +<h3>JAMES CLERK MAXWELL</h3> + +<p class="book"><big><a name="A_Treatise_on_Electricity_and_Magnetism" id="A_Treatise_on_Electricity_and_Magnetism"></a>A Treatise on Electricity and Magnetism</big></p> + +<div class="blockquot"><p>James Clerk Maxwell, the first professor of experimental physics at +Cambridge, was born at Edinburgh on November 13, 1831, and before +he was fifteen was already famous as a writer of scientific papers. +In 1854 he graduated at Cambridge as second wrangler. Two years +later he became professor of natural philosophy at Marischal +College, Aberdeen. Vacating his chair in 1860 for one at King's +College, London, Maxwell contributed largely to scientific +literature. His great lifework, however, is his famous "Treatise on +Electricity and Magnetism," which was published in 1873, and is, in +the words of a critic, "one of the most splendid monuments ever +raised by the genius of a single individual." It was in this work +that he constructed his famous theory if electricity in which +"action at a distance" should be replaced by "action through a +medium," and first enunciated the principles of an electro-magnetic +theory of light which has formed the basis of nearly all modern +physical science. He died on November 5, 1879.</p></div> + + +<p class="subchap"><i>I.—The Nature of Electricity</i></p> + +<p><span class="smcap">Let</span> a piece of glass and a piece of resin be rubbed together. They will +be found to attract each other. If a second piece of glass be rubbed +with a second piece of resin, it will be found that the two pieces of +glass repel each other and that the two pieces of resin are also +repelled from one another, while each piece of glass attracts each piece +of resin. These phenomena of attraction and repulsion are called +electrical phenomena, and the bodies which exhibit them are said to be +"electrified," or to be "charged with electricity."</p> + +<p>Bodies may be electrified in many other ways, as well as by friction. +When bodies not previously electrified are observed to be acted on by an +electrified body, it is because they have become "electrified by +induction." If a metal vessel be electrified by induction, and a second<span class='pagenum'><a name="Page_228" id="Page_228">[Pg 228]</a></span> +metallic body be suspended by silk threads near it, and a metal wire be +brought to touch simultaneously the electrified body and the second +body, this latter body will be found to be electrified. Electricity has +been transferred from one body to the other by means of the wire.</p> + +<p>There are many other manifestations of electricity, all of which have +been more or less studied, and they lead to the formation of theories of +its nature, theories which fit in, to a greater or less extent, with the +observed facts. The electrification of a body is a physical quantity +capable of measurement, and two or more electrifications can be combined +experimentally with a result of the same kind as when two quantities are +added algebraically. We, therefore, are entitled to use language fitted +to deal with electrification as a quantity as well as a quality, and to +speak of any electrified body as "charged with a certain quantity of +positive or negative electricity."</p> + +<p>While admitting electricity to the rank of a physical quantity, we must +not too hastily assume that it is, or is not, a substance, or that it +is, or is not, a form of energy, or that it belongs to any known +category of physical quantities. All that we have proved is that it +cannot be created or annihilated, so that if the total quantity of +electricity within a closed surface is increased or diminished, the +increase or diminution must have passed in or out through the closed +surface.</p> + +<p>This is true of matter, but it is not true of heat, for heat may be +increased or diminished within a closed surface, without passing in or +out through the surface, by the transformation of some form of energy +into heat, or of heat into some other form of energy. It is not true +even of energy in general if we admit the immediate action of bodies at +a distance.</p> + +<p>There is, however, another reason which warrants us in asserting that +electricity, as a physical quantity, synonymous with the total +electrification of a body, is<span class='pagenum'><a name="Page_229" id="Page_229">[Pg 229]</a></span> not, like heat, a form of energy. An +electrified system has a certain amount of energy, and this energy can +be calculated. The physical qualities, "electricity" and "potential," +when multiplied together, produce the quantity, "energy." It is +impossible, therefore, that electricity and energy should be quantities +of the same category, for electricity is only one of the factors of +energy, the other factor being "potential."</p> + +<p>Electricity is treated as a substance in most theories of the subject, +but as there are two kinds of electrification, which, being combined, +annul each other, a distinction has to be drawn between free electricity +and combined electricity, for we cannot conceive of two substances +annulling each other. In the two-fluid theory, all bodies, in their +unelectrified state, are supposed to be charged with equal quantities of +positive and negative electricity. These quantities are supposed to be +so great than no process of electrification has ever yet deprived a body +of all the electricity of either kind. The two electricities are called +"fluids" because they are capable of being transferred from one body to +another, and are, within conducting bodies, extremely mobile.</p> + +<p>In the one-fluid theory everything is the same as in the theory of two +fluids, except that, instead of supposing the two substances equal and +opposite in all respects, one of them, generally the negative one, has +been endowed with the properties and name of ordinary matter, while the +other retains the name of the electric fluid. The particles of the fluid +are supposed to repel each other according to the law of the inverse +square of the distance, and to attract those of matter according to the +same law. Those of matter are supposed to repel each other and attract +those of electricity. This theory requires us, however, to suppose the +mass of the electric fluid so small that no attainable positive or +negative electrification has yet perceptibly increased or diminished the +mass or the weight of a body, and it has not yet been<span class='pagenum'><a name="Page_230" id="Page_230">[Pg 230]</a></span> able to assign +sufficient reasons why the positive rather than the negative +electrification should be supposed due to an <i>excess</i> quantity of +electricity.</p> + +<p>For my own part, I look for additional light on the nature of +electricity from a study of what takes place in the space intervening +between the electrified bodies. Some of the phenomena are explained +equally by all the theories, while others merely indicate the peculiar +difficulties of each theory. We may conceive the relation into which the +electrified bodies are thrown, either as the result of the state of the +intervening medium, or as the result of a direct action between the +electrified bodies at a distance. If we adopt the latter conception, we +may determine the law of the action, but we can go no further in +speculating on its cause.</p> + +<p>If, on the other hand, we adopt the conception of action through a +medium, we are led to inquire into the nature of that action in each +part of the medium. If we calculate on this hypothesis the total energy +residing in the medium, we shall find it equal to the energy due to the +electrification of the conductors on the hypothesis of direct action at +a distance. Hence, the two hypotheses are mathematically equivalent.</p> + +<p>On the hypothesis that the mechanical action observed between +electrified bodies is exerted through and by means of the medium, as the +action of one body on another by means of the tension of a rope or the +pressure of a rod, we find that the medium must be in a state of +mechanical stress. The nature of the stress is, as Faraday pointed out, +a tension along the lines of force combined with an equal pressure in +all directions at right angles to these lines. This distribution of +stress is the only one consistent with the observed mechanical action on +the electrified bodies, and also with the observed equilibrium of the +fluid dielectric which surrounds them. I have, therefore, assumed the +actual existence of this state of stress.</p> + +<p><span class='pagenum'><a name="Page_231" id="Page_231">[Pg 231]</a></span></p><p>Every case of electrification or discharge may be considered as a +motion in a closed circuit, such that at every section of the circuit +the same quantity of electricity crosses in the same time; and this is +the case, not only in the voltaic current, where it has always been +recognised, but in those cases in which electricity has been generally +supposed to be accumulated in certain places. We are thus led to a very +remarkable consequence of the theory which we are examining, namely, +that the motions of electricity are like those of an <i>incompressible</i> +fluid, so that the total quantity within an imaginary fixed closed +surface remains always the same.</p> + +<p>The peculiar features of the theory as developed in this book are as +follows.</p> + +<p>That the energy of electrification resides in the dielectric medium, +whether that medium be solid or gaseous, dense or rare, or even deprived +of ordinary gross matter, provided that it be still capable of +transmitting electrical action.</p> + +<p>That the energy in any part of the medium is stored up in the form of a +constraint called polarisation, dependent on the resultant electromotive +force (the difference of potentials between two conductors) at the +place.</p> + +<p>That electromotive force acting on a dielectric produces what we call +electric displacement.</p> + +<p>That in fluid dielectrics the electric polarisation is accompanied by a +tension in the direction of the lines of force combined with an equal +pressure in all directions at right angles to the lines of force.</p> + +<p>That the surfaces of any elementary portion into which we may conceive +the volume of the dielectric divided must be conceived to be +electrified, so that the surface density at any point of the surface is +equal in magnitude to the displacement through that point of the surface +<i>reckoned inwards</i>.</p> + +<p>That, whatever electricity may be, the phenomena which we have called +electric displacement is a movement<span class='pagenum'><a name="Page_232" id="Page_232">[Pg 232]</a></span> of electricity in the same sense as +the transference of a definite quantity of electricity through a wire.</p> + + +<p class="subchap"><i>II.—Theories of Magnetism</i></p> + +<p>Certain bodies—as, for instance, the iron ore called loadstone, the +earth itself, and pieces of steel which have been subjected to certain +treatment—are found to possess the following properties, and are called +magnets.</p> + +<p>If a magnet be suspended so as to turn freely about a vertical axis, it +will in general tend to set itself in a certain azimuth, and, if +disturbed from this position, it will oscillate about it.</p> + +<p>It is found that the force which acts on the body tends to cause a +certain line in the body—called the axis of the magnet—to become +parallel to a certain line in space, called the "direction of the +magnetic force."</p> + +<p>The ends of a long thin magnet are commonly called its poles, and like +poles repel each other; while unlike poles attract each other. The +repulsion between the two magnetic poles is in the straight line joining +them, and is numerically equal to the products of the strength of the +poles divided by the square of the distance between them; that is, it +varies as the inverse square of the distance. Since the form of the law +of magnetic action is identical with that of electric action, the same +reasons which can be given for attributing electric phenomena to the +action of one "fluid," or two "fluids" can also be used in favour of the +existence of a magnetic matter, fluid or otherwise, provided new laws +are introduced to account for the actual facts.</p> + +<p>At all parts of the earth's surface, except some parts of the polar +regions, one end of a magnet points in a northerly direction and the +other in a southerly one. Now a bar of iron held parallel to the +direction of the earth's magnetic force is found to become magnetic. Any +piece of soft iron placed in a magnetic field is found to<span class='pagenum'><a name="Page_233" id="Page_233">[Pg 233]</a></span> exhibit +magnetic properties. These are phenomena of <i>induced</i> magnetism. Poisson +supposes the magnetism of iron to consist in a separation of the +magnetic fluids within each magnetic molecule. Weber's theory differs +from this in assuming that the molecules of the iron are always magnets, +even before the application of the magnetising force, but that in +ordinary iron the magnetic axes of the molecules are turned +indifferently in every direction, so that the iron as a whole exhibits +no magnetic properties; and this theory agrees very well with what is +observed.</p> + +<p>The theories establish the fact that magnetisation is a phenomenon, not +of large masses of iron, but of molecules; that is to say, of portions +of the substance so small that we cannot by any mechanical method cut +them in two, so as to obtain a north pole separate from the south pole. +We have arrived at no explanation, however, of the nature of a magnetic +molecule, and we have therefore to consider the hypothesis of +Ampère—that the magnetism of the molecule is due to an electric current +constantly circulating in some closed path within it.</p> + +<p>Ampère concluded that if magnetism is to be explained by means of +electric currents, these currents must circulate within the molecules of +the magnet, and cannot flow from one molecule to another. As we cannot +experimentally measure the magnetic action at a point within the +molecule, this hypothesis cannot be disproved in the same way that we +can disprove the hypothesis of sensible currents within the magnet. In +spite of its apparent complexity, Ampère's theory greatly extends our +mathematical vision into the interior of the molecules.</p> + + +<p class="subchap"><i>III.—The Electro-Magnetic Theory of Light</i></p> + +<p>We explain electro-magnetic phenomena by means of mechanical action +transmitted from one body to another<span class='pagenum'><a name="Page_234" id="Page_234">[Pg 234]</a></span> by means of a medium occupying the +space between them. The undulatory theory of light also assumes the +existence of a medium. We have to show that the properties of the +electro-magnetic medium are identical with those of the luminiferous +medium.</p> + +<p>To fill all space with a new medium whenever any new phenomena are to be +explained is by no means philosophical, but if the study of two +different branches of science has independently suggested the idea of a +medium; and if the properties which must be attributed to the medium in +order to account for electro-magnetic phenomena are of the same kind as +those which we attribute to the luminiferous medium in order to account +for the phenomena of light, the evidence for the physical existence of +the medium is considerably strengthened.</p> + +<p>According to the theory of emission, the transmission of light energy is +effected by the actual transference of light-corpuscles from the +luminous to the illuminated body. According to the theory of undulation +there is a material medium which fills the space between the two bodies, +and it is by the action of contiguous parts of this medium that the +energy is passed on, from one portion to the next, till it reaches the +illuminated body. The luminiferous medium is therefore, during the +passage of light through it, a receptacle of energy. This energy is +supposed to be partly potential and partly kinetic, and our theory +agrees with the undulatory theory in assuming the existence of a medium +capable of becoming a receptacle for two forms of energy.</p> + +<p>Now, the properties of bodies are capable of quantitative measurement. +We therefore obtain the numerical value of some property of the +medium—such as the velocity with which a disturbance is propagated in +it, which can be calculated from experiments, and also observed directly +in the case of light. If it be found that the velocity of propagation of +electro-magnetic disturbance is the same as the velocity of light, we +have strong<span class='pagenum'><a name="Page_235" id="Page_235">[Pg 235]</a></span> reasons for believing that light is an electro-magnetic +phenomenon.</p> + +<p>It is, in fact, found that the velocity of light and the velocity of +propagation of electro-magnetic disturbance are quantities of the same +order of magnitude. Neither of them can be said to have been determined +accurately enough to say that one is greater than the other. In the +meantime, our theory asserts that the quantities are equal, and assigns +a physical reason for this equality, and it is not contradicted by the +comparison of the results, such as they are.</p> + +<p>Lorenz has deduced from Kirchoff's equations of electric currents a new +set of equations, indicating that the distribution of force in the +electro-magnetic field may be considered as arising from the mutual +action of contiguous elements, and that waves, consisting of transverse +electric currents, may be propagated, with a velocity comparable with +that of light, in non-conducting media. These conclusions are similar to +my own, though obtained by an entirely different method.</p> + +<p>The most important step in establishing a relation between electric and +magnetic phenomena and those of light must be the discovery of some +instance in which one set of phenomena is affected by the other. Faraday +succeeded in establishing such a relation, and the experiments by which +he did so are described in the nineteen series of his "Experimental +Researches." Suffice it to state here that he showed that in the case of +aray of plane-polarised light the effect of the magnetic force is to +turn the plane of polarisation round the direction of the ray as an +axis, through a certain angle.</p> + +<p>The action of magnetism on polarised light leads to the conclusion that +in a medium under the action of a magnetic force, something belonging to +the same mathematical class as an angular velocity, whose axis is in the +direction of the magnetic force, forms part of the phenomenon. This +angular velocity cannot be any <span class='pagenum'><a name="Page_236" id="Page_236">[Pg 236]</a></span>portion of the medium of sensible +dimensions rotating as a whole. We must, therefore, conceive the +rotation to be that of very small portions of the medium, each rotating +on its own axis.</p> + +<p>This is the hypothesis of molecular vortices. The displacements of the +medium during the propagation of light will produce a disturbance of the +vortices, and the vortices, when so disturbed, may react on the medium +so as to affect the propagation of the ray. The theory proposed is of a +provisional kind, resting as it does on unproved hypotheses relating to +the nature of molecular vortices, and the mode in which they are +affected by the displacement of the medium.</p> + + +<p class="subchap"><i>IV.—Action at a Distance</i></p> + +<p>There appears to be some prejudice, or <i>a priori</i> objection, against the +hypothesis of a medium in which the phenomena of radiation of light and +heat, and the electric actions at a distance, take place. It is true +that at one time those who speculated as to the cause of physical +phenomena were in the habit of accounting for each kind of action at a +distance by means of a special æthereal fluid, whose function and +property it was to produce these actions. They filled all space three +and four times over with æthers of different kinds, the properties of +which consisted merely to "save appearances," so that more rational +inquirers were willing to accept not only Newton's definite law of +attraction at a distance, but even the dogma of Cotes that action at a +distance is one of the primary properties of matter, and that no +explanation can be more intelligible than this fact. Hence the +undulatory theory of light has met with much opposition, directed not +against its failure to explain the phenomena, but against its assumption +of the existence of a medium in which light is propagated.</p> + +<p>The mathematical expression for electro-dynamic action<span class='pagenum'><a name="Page_237" id="Page_237">[Pg 237]</a></span> led, in the mind +of Gauss, to the conviction that a theory of the propagation of electric +action would in time be found to be the very keystone of +electro-dynamics. Now, we are unable to conceive of propagation in time, +except either as the flight of a material substance through space or as +the propagation of a condition of motion or stress in a medium already +existing in space.</p> + +<p>In the theory of Neumann, the mathematical conception called potential, +which we are unable to conceive as a material substance, is supposed to +be projected from one particle to another, in a manner which is quite +independent of a medium, and which, as Neumann has himself pointed out, +is extremely different from that of the propagation of light. In other +theories it would appear that the action is supposed to be propagated in +a manner somewhat more similar to that of light.</p> + +<p>But in all these theories the question naturally occurs: "If something +is transmitted from one particle to another at a distance, what is its +condition after it had left the one particle, and before it reached the +other?" If this something is the potential energy of the two particles, +as in Neumann's theory, how are we to conceive this energy as existing +in a point of space coinciding neither with the one particle nor with +the other? In fact, whenever energy is transmitted from one body to +another in time, there must be a medium or substance in which the energy +exists after it leaves one body, and before it reaches the other, for +energy, as Torricelli remarked, "is a quintessence of so subtile a +nature that it cannot be contained in any vessel except the inmost +substance of material things."</p> + +<p>Hence all these theories lead to the conception of a medium in which the +propagation takes place, and if we admit this medium as an hypothesis, I +think we ought to endeavour to construct a mental representation of all +the details of its action, and this has been my constant aim in this +treatise.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_238" id="Page_238">[Pg 238]</a></span></p> +<h3>ELIE METCHNIKOFF</h3> + +<p class="book"><big><a name="The_Nature_of_Man" id="The_Nature_of_Man"></a>The Nature of Man</big></p> + +<div class="blockquot"><p>Elie Metchnikoff, Sub-Director of the Pasteur Institute in Paris, +was born May 15, 1845, in the province of Kharkov, Russia, and has +worked at the Pasteur Institute since 1888. The greater part of +Metchnikoff's work is concerned with the most intimate processes of +the body, and notably the means by which it defends itself from the +living agents of disease. He is, indeed, the author of a standard +treatise entitled "Immunity in Infective Diseases." His early work +in zoology led him to study the water-flea, and thence to discover +that the white cells of the human blood oppose, consume, and +destroy invading microbes. Latterly, Metchnikoff has devoted +himself in some measure to more general and especially +philosophical studies, the outcome of which is best represented by +the notable volume on "The Nature of Man," which was published at +Paris in 1903.</p></div> + + +<p class="subchap"><i>I.—Disharmonies in Nature</i></p> + +<p><span class="smcap">Notwithstanding</span> the real advance made by science, it cannot be disputed +that a general uneasiness disturbs the whole world to-day, and the +frequency of suicide is increased greatly among civilised peoples. Yet +if science turns to study human nature, there may be grounds for hope. +The Greeks held human nature and the human body in high esteem, and +among the Romans such a philosopher as Seneca said, "Take nature as your +guide, for so reason bids you and advises you; to live happily is to +live naturally." In our own day Herbert Spencer has expressed again the +Greek ideal, seeking the foundation of morality in human nature itself.</p> + +<p>But it has often been taught that human nature is composed of two +hostile elements, a body and a soul. The soul alone was to be honoured, +while the body was regarded as the vile source of evils. This doctrine +has had many disastrous consequences, and it is not surprising<span class='pagenum'><a name="Page_239" id="Page_239">[Pg 239]</a></span> that in +consequence of it celibacy should have been regarded as the ideal state. +Art fell from the Greek ideal until the Renaissance, with its return to +that ideal, brought new vigour. When the ancient spirit was born again +its influence reached science and even religion, and the Reformation was +a defence of human nature. The Lutheran doctrines resumed the principle +of a "development as complete as possible of all the natural powers" of +man, and compulsory celibacy was abolished.</p> + +<p>The historical diversity of opinion regarding human nature is what has +led me to the attempt to give an exposition of human nature in its +strength and in its weakness. But, before dealing with the man himself, +we must survey the lower forms of life.</p> + +<p>The facts of the organised world, before the appearnace of man, teach us +that though we find change and development, development does not always +take a progressive march. We are bound to believe, for instance, that +the latest products of evolution are not human beings, but certain +parasites which live only upon, or in, the human body. The law in nature +is not of constant progress, but of constant tendency towards +adaptation. Exquisite adaptations, or harmonies, in nature are +constantly met with in the world of living beings. But, on the other +hand, any close investigation of organisation and life reveals that +beside many most perfect harmonies, there are facts which prove the +existence of incomplete harmony, or even absolute disharmony. +Rudimentary and useless organs are widely distributed. Many insects are +exquisitely adapted for sucking the nectar of flowers; many others would +wish to do the same, but their want of adaptation baffles them.</p> + +<p>It is plain that an instinct, or any other form of disharmony, leading +to destruction, cannot increase or even endure very long. The perversion +of the maternal instinct, tending to abandonment of the young, is +destructive to the stock. In consequence, individuals<span class='pagenum'><a name="Page_240" id="Page_240">[Pg 240]</a></span> affected by it do +not have the opportunity of transmitting the perversion. If all rabbits, +or a majority of them, left their young to die through neglect, it is +evident that the species would soon die out. On the contrary, mothers +guided by their instinct to nourish and foster their offspring will +produce a vigorous generation capable of transmitting the healthy +maternal instinct so essential for the preservation of the species. For +such a reason harmonious characters are more abundant in nature than +injurious peculiarities. The latter, because they are injurious to the +individual and to the species, cannot perpetuate themselves +indefinitely.</p> + +<p>In this way there comes about a constant selection of characters. The +useful qualities are handed down and preserved, while noxious characters +perish and so disappear. Although disharmonies tend to the destruction +of a species, they may themselves disappear without having destroyed the +race in which they occur.</p> + +<p>This continuous process of natural selection, which offers so good an +explanation of the transmutation and origin of species by means of +preservation of useful and destruction of harmful characters, was +discovered by Darwin and Wallace, and was established by the splendid +researches of the former of these.</p> + +<p>Long before the appearance of man on the face of the earth, there were +some happy beings well adapted to their environment, and some unhappy +creatures that followed disharmonious instincts so as to imperil or to +destroy their lives. Were such creatures capable of reflection and +communication, plainly the fortunate among them, such as orchids and +certain wasps, would be on the side of the optimists; they would declare +this the best of all possible worlds, and insist that to secure +happiness it is necessary only to follow natural instincts. On the other +hand, the disharmonious creatures, those ill adapted to the conditions +of life, would be pessimistic philosophers. Consider the case of the +ladybird, driven by hunger and<span class='pagenum'><a name="Page_241" id="Page_241">[Pg 241]</a></span> with a preference for honey, which +searches for it on flowers and meets only with failure, or of insects +driven by their instincts into the flames, only to lose their wings and +their lives; such creatures, plainly, would express as their idea of the +world that it was fashioned abominably, and that existence was a +mistake.</p> + + +<p class="subchap"><i>II.—Disharmonies in Man</i></p> + +<p>As for man, the creature most interesting to us, in what category does +he fall? Is he a being whose nature is in harmony with the conditions in +which he has to live, or is he out of harmony with his environment? A +critical examination is needed to answer these questions, and to such an +examination the pages to follow are devoted.</p> + +<p>Science has proved that man is closely akin to the higher monkeys or +anthropoid apes—a fact which we must reckon with if we are to +understand human nature. The details of anatomy which show the kinship +between man and the apes are numerous and astonishing. All the facts +brought to light during the last forty years have supported this truth, +and no single fact has been brought against it. Quite lately it has been +shown that there are remarkable characters in the blood, such that, +though by certain tests the fluid part of human blood can be readily +distinguished from that of any other creature, the anthropoid apes, and +they alone, furnish an exception to this rule. There is thus verily a +close blood-relationship between the human species and the anthropoid +apes.</p> + +<p>But how man arose we do not know. It is probable that he owes his origin +to a mutation—a sudden change comparable with that which De Vries +observed in the case of the evening primrose. The new creature possessed +a brain of abnormal size placed in a spacious cranium which allowed a +rapid development of intellectual faculties. This peculiarity would be +transmitted to<span class='pagenum'><a name="Page_242" id="Page_242">[Pg 242]</a></span> the descendants, and as it was a very considerable +advantage in the struggle for existence, the new race would hold its +own, propagate, and prevail.</p> + +<p>Although he is a recent arrival on the earth, man has already made great +progress, as compared with his ancestors the anthropoid apes, and we +learn the same if we compare the higher and lower races of mankind. Yet +there remain many disharmonies in the organisation of man, as, for +instance, in his digestive system. A simple instance of this kind is +furnished by the wisdom teeth. The complete absence of all four wisdom +teeth has no influence on mastication, and their presence is very +frequently the source of illness and danger. In man they are indeed +rudimentary organs, providing another proof of our simian origin. The +vermiform appendix, so frequently the cause of illness and death, is +another rudimentary organ in the human body, together with the part of +the digestive canal to which it is attached. The organ is a very old +part of the constitution of mammals, and it is because it has been +preserved long after its function has disappeared that we find it +occurring in the body of man.</p> + +<p>I believe that not only the appendix, but a very large part of the +alimentary canal is superfluous, and worse than superfluous. It is, of +course, of great importance to the horse, the rabbit, and some other +mammals that live exclusively on grain and herbage. The latter part of +the alimentary canal, however, must be regarded as one of the organs +possessed by man and yet harmful to his health and life. It is the cause +of a series of misfortunes. The human stomach also is of little value, +and can easily be dispensed with, as surgery has proved. It is because +we inherit our alimentary canal from creatures of different dietetic +habits that it is impossible for us to take our nutriment in the most +perfect form. If we were only to eat substances that could be almost +completely absorbed, serious complications would be produced. A<span class='pagenum'><a name="Page_243" id="Page_243">[Pg 243]</a></span> +satisfactory system of diet has to make allowance for this, and in +consequence of the structure of the alimentary canal has to include in +the food bulky and indigestible materials, such as vegetables. Lastly, +it may be noted that the instinct of appetite in man is largely +aberrant. The widespread results of alcoholism show plainly the +prevalent existence in man of a want of harmony between the instinct for +choosing food and the instinct of preservation.</p> + +<p>Far stronger than the social instinct, and far older, is the love of +life and the instinct of self-preservation. Devices for the protection +of life were developed long before the evolution of mankind, and it is +quite certain that animals, even those highest in the scale of life, are +unconscious of the inevitability of death and the ultimate fate of all +living things. This knowledge is a human acquisition. It has long been +recognised that the old attach a higher value to life than do the young. +The instinctive love of life and fear of death are of importance in the +study of human nature, impossible to over-estimate.</p> + +<p>The instinctive love of life is preserved in the aged in its strongest +form. I have carefully studied the aged to make certain on this point. +It is a terrible disharmony that the instinctive love of life should +manifest itself so strongly when death is felt to be so near at hand. +Hence the religions of all times have been concerned with the problem of +death.</p> + + +<p class="subchap"><i>III.—Science the Only Remedy for Human Disharmonies</i></p> + +<p>In religion and in philosophy throughout their whole history we find +attempts to combat the ills arising from the disharmonies of the human +constitution.</p> + +<p>Ancient and modern philosophies, like ancient and modern religions, have +concerned themselves with the<span class='pagenum'><a name="Page_244" id="Page_244">[Pg 244]</a></span> attempt to remedy the ills of human +existence, and instinctive fear of death has always ensured that great +attention has been paid to the doctrine of immortality.</p> + +<p>Science, the youngest daughter of knowledge, has begun to investigate +the great problems affecting humanity. Her first steps, taken along the +lines first clearly laid down by Bacon, were slow and halting. But +medical science has lately made great progress, and has gone very far to +control disease, especially in consequence of the work of Pasteur. It is +said that science has failed because, for instance, tuberculosis +persists, but tuberculosis is propagated not because of the failure of +science, but because of the ignorance and stupidity of the population. +To diminish the spread of tuberculosis, of typhoid fever, of dysentery, +and of many other diseases, it is necessary only to follow the rules of +scientific hygiene without waiting for specific remedies.</p> + +<p>Science offers us much hope also when it is directed to the study of old +age and the phenomena which lead to death.</p> + +<p>Man, who is the descendant of some anthropoid ape, has inherited a +constitution adapted to an environment very different from that which +now surrounds him. He is possessed of a brain very much more highly +developed than that of his ancestors, and has entered on a new path in +the evolution of the higher organisms. The sudden change in his natural +conditions has brought about a large series of organic disharmonies, +which become more and more acutely felt as he becomes more intelligent +and more sensitive; and thus there has arisen a number of sorrows which +poor humanity has tried to relieve by all the means in its power. +Humanity in its misery has put question after question to science, and +has lost patience at the slowness of the advance of knowledge. It has +declared that the answers already found by science are futile and of +little interest. But science, confident of its methods, has quietly +continued to work. Little by little<span class='pagenum'><a name="Page_245" id="Page_245">[Pg 245]</a></span> the answers to some of the +questions that have been set have begun to appear.</p> + +<p>Man, because of the fundamental disharmonies in his constitution, does +not develop normally. The earlier phases of his development are passed +through with little trouble; but after maturity greater or lesser +abnormality begins, and ends in old age and death that are premature and +pathological. Is not the goal of existence the accomplishment of a +complete and physiological cycle in which occurs a normal old age, +ending in the loss of the instinct of life and the appearance of the +instinct of death? But before attaining the normal end, coming after the +appearance of the instinct of death, a normal life must be lived; a life +filled all through with the feeling that comes from the accomplishment +of function. Science has been able to tell us that man, the descendant +of animals, has good and evil qualities in his nature, and that his life +is made unhappy by the evil qualities.</p> + +<p>But the constitution of man is not immutable, and perhaps it may be +changed for the better. Morality should be based not on human nature in +its existing condition, but on ideal human nature, as it may be in the +future. Before all things, it is necessary to try to amend the evolution +of human life, that is to say, to transform its disharmonies into +harmonies. This task can be undertaken only by science, and to science +the opportunity of accomplishing it must be given. Before it is possible +to reach the goal mankind must be persuaded that science is all-powerful +and that the deeply-rooted existing superstitions are pernicious. It +will be necessary to reform many customs and many institutions that now +seem to rest on enduring foundations. The abandonment of much that is +habitual, and a revolution in the mode of education, will require long +and painful effort. But the conviction that science alone is able to +redress the disharmonies of the human constitution will lead directly to +the improvement of education and to the solidarity of mankind.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_246" id="Page_246">[Pg 246]</a></span></p> +<p class="book"><big><a name="The_Prolongation_of_Life" id="The_Prolongation_of_Life"></a>The Prolongation of Life</big></p> + +<div class="blockquot"><p>Professor Metchnikoff's volume, on "The Prolongation of Life: +Studies in Optimistic Philosophy," was published in 1907, and is in +some respects the most original of his works. In it he carries much +further the arguments and the studies to which he made brief +allusion in "The Nature of Man," and he lays down certain +principles for the prolongation of life which have been put into +practice by a large number of people during the last two or three +years, and are steadily gaining more attention. Sour milk as an +article of diet appears to have a peculiar value in arresting the +supposed senile changes which are largely due to auto-intoxication +or self-poisoning.</p></div> + + +<p class="subchap"><i>I.—Senile Debility</i></p> + +<p>When we study old age in man and the lower animals, we observe certain +features common to both. But often among vertebrates there are found +animals whose bodies withstand the ravages of time much better than that +of man. I think it a fair inference that senility, that precocious +senescence which is one of the greatest sorrows of humanity, is not so +profoundly seated in the constitution of the higher animals as has +generally been supposed. The first facts which we must accept are that +human beings who reach extreme old age may preserve their mental +qualities, notwithstanding serious physical decay, and that certain of +the higher animals can resist the influence of time much longer than is +the case with man under present conditions.</p> + +<p>Many theories have been advanced regarding the cause of senility. It is +certain that many parts of the body continue to thrive and grow even in +old age, as, for instance, the nails and hair. But I believe that I have +proved that in many parts of the body, especially the higher elements, +such as nervous and muscular cells, there is a destruction due to the +activity of the white cells of the blood. I have shown also that the +blanching of the hair in old age is<span class='pagenum'><a name="Page_247" id="Page_247">[Pg 247]</a></span> due to the activity of these white +cells, which destroy the hair pigment. Progressive muscular debility is +an accompaniment of old age; physical work is seldom given to men over +sixty years of age, as it is notorious that they are less capable of it. +Their muscular movements are feebler, and soon bring on fatigue; their +actions are slow and painful. Even old men whose mental vigour is +unimpaired admit their muscular weakness. The physical correlate of this +condition is an actual atrophy of the muscles, and has for long been +known to observers. I have found that the cause of this atrophy is the +consumption of the muscle fibres by what I call phagocytes, or eating +cells, a certain kind of white blood cells.</p> + +<p>In the case of certain diseases we find symptoms, which look like +precocious senility, due to the poison of the disease. It is no mere +analogy to suppose that human senescence is the result of a slow but +chronic poisoning of the organism. Such poisons, if not completely +destroyed or got rid of, weaken the tissues, the functions of which +become altered or enfeebled in which the latter have the advantage. But +we must make further studies before we can answer the question whether +our senescence can be ameliorated.</p> + +<p>The duration of the life of animals varies within very wide limits. As a +general rule, small animals do not live so long as large ones, but there +is no absolute relation between size and longevity, since parrots, +ravens, and geese live much longer than many mammals, and than some much +larger birds. Buffon long ago argued that the total duration of life +bore some definite relation to the length of the period of growth, but +further inquiry shows that such a relation cannot be established. +Nevertheless, there is something intrinsic in each kind of animal which +sets a definite limit to the length of years it can attain. The purely +physiological conditions which determine this limit leave room for a +considerable amount of variation in longevity. Duration of life, +<span class='pagenum'><a name="Page_248" id="Page_248">[Pg 248]</a></span>therefore, is a character which can be influenced by the environment.</p> + +<p>The duration of life in mammals is relatively shorter than in birds, and +in the so-called cold-blooded vertebrates. No indication as to the cause +of this difference can be found elsewhere than in the organs of +digestion. Mammals are the only group of vertebrate animals in which the +large intestine is much developed. This part of the alimentary canal is +not important, for it fulfils no notable digestive function. On the +other hand, it accommodates among the intestinal flora many microbes +which damage health by poisoning the body with their products. Among the +intestinal flora there are many microbes which are inoffensive, but +others are known to have pernicious properties, and auto-intoxication, +or self-poisoning, is the cause of the ill-health which may be traced to +their activity. It is indubitable that the intestinal microbes or their +poisons may reach the system generally, and bring harm to it. I infer +from the facts that the more the digestive tract is charged with +microbes, the more it is a source of harm capable of shortening life. As +the large intestine not only is that part of the digestive tube most +richly charged with microbes, but is relatively more capacious in +mammals than in any other vertebrates, it is a just inference that the +duration of life of mammals has been notably shortened as the result of +chronic poisoning from an abundant intestinal flora.</p> + +<p>When we come to study the duration of human life, it is impossible to +accept the view that the high mortality between the ages of seventy and +seventy-five indicates a natural limit to human life. The fact that many +men from seventy to seventy-five years old are well preserved, both +physically and intellectually, makes it impossible to regard that age as +the natural limit of human life. Philosophers such as Plato, poets such +as Goethe and Victor Hugo, artists such as Michael Angelo, Titian, and +Franz Hals, produced some of their most important<span class='pagenum'><a name="Page_249" id="Page_249">[Pg 249]</a></span> works when they had +passed what some regard as the limit of life. Moreover, deaths of people +at that age are rarely due to senile debility. Centenarians are really +not rare. In France, for instance, nearly 150 centenarians die every +year, and extreme longevity is not limited to the white races. Women +more frequently become centenarians than men—a fact which supports the +general proposition that male mortality is always greater than that of +the other sex.</p> + +<p>It has been noticed that most centenarians have been people who were +poor or in humble circumstances, and whose life has been extremely +simple. It may well be said that great riches do not bring a very long +life. Poverty generally brings with it sobriety, especially in old age, +and sobriety is certainly favourable to long life.</p> + + +<p class="subchap"><i>II.—The Study of Natural Death</i></p> + +<p>It is surprising to find how little science really knows about death. By +natural death I mean to denote death due to the nature of the organism, +and not to disease. We may ask whether natural death really occurs, +since death so frequently comes by accident or by disease; and certainly +the longevity of many plants is amazing. Such ages as three, four, and +five thousand years are attributed to the baobab at Cape Verd, certain +cypresses, and the sequoias of California. It is plain that among the +lower and higher plants there are cases where natural death does not +exist; and, further, so far as I can ascertain, it looks as if poisons +produced by their own bodies were the cause of natural death among the +higher plants where it does occur.</p> + +<p>In the human race cases of what may be called natural death are +extremely rare; the death of old people is usually due to infectious +disease, particularly pneumonia, or to apoplexy. The close analogy +between natural death and sleep supports my view that it is due to an +<span class='pagenum'><a name="Page_250" id="Page_250">[Pg 250]</a></span>auto-intoxication of the organism, since it is very probable that sleep +is due to "poisoning" by the products of organic activity.</p> + +<p>Although the duration of the life of man is one of the longest amongst +mammals, men find it too short. Ought we to listen to the cry of +humanity that life is too short, and that it will be well to prolong it? +If the question were merely one of prolonging the life of old people, +without modifying old age itself, the answer would be doubtful. It must +be understood, however, that the prolongation of life will be associated +with the preservation of intelligence and of the power to work. When we +have reduced or abolished such causes of precocious senility as +intemperance and disease, it will no longer be necessary to give +pensions at the age of sixty or seventy years. The cost of supporting +the old, instead of increasing, will diminish progressively. We must use +all our endeavors to allow men to complete their normal course of life, +and to make it possible for old men to play their parts as advisers and +judges, endowed with their long experience of life.</p> + +<p>From time immemorial suggestions have been made for the prolongation of +life. Many elixirs have been sought and supposed to have been found, but +general hygienic measures have been the most successful in prolonging +life and in lessening the ills of old age. That is the teaching of Sir +Herman Weber, himself of very great age, who advises general hygienic +principles, and especially moderation in all respects. He advises us to +avoid alcohol and other stimulants, as well as narcotics and soothing +drugs. Certainly the prolongation of life which has come to pass in +recent centuries must be attributed to the advance of hygiene; and if +hygiene was able to prolong life when little developed, as was the case +until recently, we may well believe that with our greater knowledge a +much better result will be obtained.</p> + + +<p><span class='pagenum'><a name="Page_251" id="Page_251">[Pg 251]</a></span></p><p class="subchap"><i>III.—The Use of Lactic Acid</i></p> + +<p>The general measures of hygiene directed against infectious diseases +play a part in prolonging the lives of old people; but, in addition to +the microbes which invade the body from outside, there is a rich source +of harm in microbes which inhabit the body. The most important of these +belong to the intestinal flora which is abundant and varied. Now the +attempt to destroy the intestinal microbes by the use of chemical agents +has little chance of success, and the intestine itself may be harmed +more than the microbes. If, however, we observe the new-born child we +find that, when suckled by its mother, its intestinal microbes are very +different and much fewer than if it be fed with cows' milk. I am +strongly convinced that it is advantageous to protect ourselves by +cooking all kinds of food which, like cows' milk, are exposed to the +air. It is well-known that other means—as, for instance, the use of +lactic acid—will prevent food outside the body from going bad. Now as +lactic fermentation serves so well to arrest putrefaction in general, +why should it not be used for the same purpose within the digestive +tube? It has been clearly proved that the microbes which produce lactic +acid can, and do, control the growth of other microbes within the body, +and that the lactic microbe is so much at home in the human body that it +is to be found there several weeks after it has been swallowed.</p> + +<p>From time immemorial human beings have absorbed quantities of lactic +microbes by consuming in the uncooked condition substances such as +soured milk, kephir, sauerkraut, or salted cucumbers, which have +undergone lactic fermentation. By these means they have unknowingly +lessened the evil consequences of intestinal putrefaction. The fact that +so many races make soured milk and use it copiously is an excellent +testimony to its<span class='pagenum'><a name="Page_252" id="Page_252">[Pg 252]</a></span> usefulness, and critical inquiry shows that longevity, +with few traces of senility, is conspicuous amongst peoples who use sour +milk extensively.</p> + +<p>A reader who has little knowledge of such matters may be surprised by my +recommendation to absorb large quantities of microbes, as the general +belief is that microbes are all harmful. This belief, however, is +erroneous. There are many useful microbes, amongst which the lactic +bacilli have an honourable place. If it be true that our precocious and +unhappy old age is due to poisoning of the tissues, the greater part of +the poison coming from the large intestine, inhabited by numberless +microbes, it is clear that agents which arrest intestinal putrefaction +must at the same time postpone and ameliorate old age. This theoretical +view is confirmed by the collection of facts regarding races which live +chiefly on soured milk, and amongst which great ages are common.</p> + + +<p class="subchap"><i>IV.—An Ideal Old Age</i></p> + +<p>As I have shown in the "Nature of Man," the human constitution as it +exists to-day, being the result of a long evolution and containing a +large animal element, cannot furnish the basis of rational morality. The +conception which has come down from antiquity to modern times, of a +harmonious activity of all the organs, is no longer appropriate to +mankind. Organs which are in course of atrophy must not be re-awakened, +and many natural characters which, perhaps, were useful in the case of +animals, must be made to disappear in men.</p> + +<p>Human nature which, like the constitutions of other organisms, is +subject to evolution, must be modified according to a definite ideal. +Just as a gardener or stock-raiser is not content with the existing +nature of the plants and animals with which he is occupied, but modifies +them to suit his purposes, so also the scientific philosopher must not +think of existing human nature as <span class='pagenum'><a name="Page_253" id="Page_253">[Pg 253]</a></span>immutable, but must try to modify it +for the advantage of mankind. As bread is the chief article in the human +food, attempts to improve cereals have been made for a very long time, +but in order to obtain results much knowledge is necessary. To modify +the nature of plants, it is necessary to understand them well, and it is +necessary to have an ideal to be aimed at. In the case of mankind the +ideal of human nature, towards which we ought to press, may be formed. +In my opinion this ideal is "orthobiosis"—that is to say, the +development of human life, so that it passes through a long period of +old age in active and vigorous health, leading to a final period in +which there shall be present a sense of satiety of life, and a wish for +death.</p> + +<p>Just as we must study the nature of plants before trying to realise our +ideal, so also varied and profound knowledge is the first requisite for +the ideal of moral conduct. It is necessary not only to know the +structure and functions of the human organism, but to have exact ideas +on human life as it is in society. Scientific knowledge is so +indispensable for moral conduct that ignorance must be placed among the +most immoral acts. A mother who rears her child in defiance of good +hygiene, from want of knowledge, is acting immorally towards her +offspring, notwithstanding her feeling of sympathy. And this also is +true of a government which remains in ignorance of the laws which +regulate human life and human society.</p> + +<p>If the human race come to adopt the principles of orthobiosis, a +considerable change in the qualities of men of different ages will +follow. Old age will be postponed so much that men of from sixty to +seventy years of age will retain their vigour, and will not require to +ask assistance in the fashion now necessary. On the other hand, young +men of twenty-one years of age will no longer be thought mature or ready +to fulfil functions so difficult as taking a share in public affairs. +The view which I<span class='pagenum'><a name="Page_254" id="Page_254">[Pg 254]</a></span> set forth in the "Nature of Man" regarding the danger +which comes from the present interference of young men in political +affairs has since then been confirmed in the most striking fashion.</p> + +<p>It is easily intelligible that in the new conditions such modern idols +as universal suffrage, public opinion, and the <i>referendum</i>, in which +the ignorant masses are called on to decide questions which demand +varied and profound knowledge, will last no longer than the old idols. +The progress of human knowledge will bring about the replacement of such +institutions by others, in which applied morality will be controlled by +the really competent persons. I permit myself to suppose that in these +times scientific training will be much more general than it is just now, +and that it will occupy the place which it deserves in education and in +life.</p> + +<p>Our intelligence informs us that man is capable of much, and, therefore, +we hope that he may be able to modify his own nature and transform his +disharmonies into harmonies. It is only human will that can attain this +ideal.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_255" id="Page_255">[Pg 255]</a></span></p> +<h3>HUGH MILLER</h3> + +<p class="book"><big><a name="The_Old_Red_Sandstone" id="The_Old_Red_Sandstone"></a>The Old Red Sandstone</big></p> + +<div class="blockquot"><p>Hugh Miller was born in Cromarty, in the North of Scotland, October +10, 1802. From the time he was seventeen until he was thirty-four, +he worked as a common stone-mason, although devoting his leisure +hours to independent researches in natural history, for which he +formed a taste early in life. He became interested in journalism, +and was editor of the Edinburgh "Witness," when, in 1840, he +published the contents of the volume issued a year later as "The +Old Red Sandstone." The book deals with its author's most +distinctive work, namely, finding fossils that tell much of the +history of the Lower Old Red Sandstone, and fixing in the +geological scale the place to which the larger beds of remains +found in the system belong. Besides being a practical and original +geologist, Miller had a fine imaginative power, which enabled him +to reconstruct the past from its ruinous relics. The fact that he +unfortunately set himself the task of combating the theory of +evolution, which was fast gaining ground in his day, should not +blind us to the high value of his geological experiences. The +results of his observations provide some of the most cogent proofs +of the theory he disputed. Late in life Miller's mind gave way, and +he put an end to his own life on December 24, 1856.</p></div> + + +<p class="subchap"><i>I.—A Stone-mason's Researches</i></p> + +<p><span class="smcap">My</span> advice to young working men desirous of bettering their +circumstances, and adding to the amount of their enjoyment, is to seek +happiness in study. Learn to make a right use of your eyes; the +commonest things are worth looking at—even stones, weeds, and the most +familiar animals. There are none of the intellectual or moral faculties, +the exercise of which does not lead to enjoyment; hence it is that +happiness bears so little reference to station.</p> + +<p>Twenty years ago I made my first acquaintance with a life of labour and +restraint. I was but a slim, loose-jointed boy at the time, fond of the +pretty intangibilities<span class='pagenum'><a name="Page_256" id="Page_256">[Pg 256]</a></span> of romance, and of dreaming when broad awake; +and, woful change! I was now going to work in a quarry. I was going to +exchange all my day-dreams for the kind of life in which men toil every +day that they may be enabled to eat, and eat every day that they may be +enabled to toil!</p> + +<p>That first day was no very formidable beginning of the course of life I +had so much dreaded. To be sure, my hands were a little sore, and I felt +nearly as much fatigued as if I had been climbing among the rocks; but I +had wrought and been useful, and had yet enjoyed the day fully as much +as usual. I was as light of heart next morning as any of my +brother-workmen. That night, arising out of my employment, I found I had +food enough for thought without once thinking of the unhappiness of a +life of labour.</p> + +<p>In the course of the day I picked up a nodular mass of blue limestone, +and laid it open by a stroke of the hammer. Wonderful to relate, it +contained inside a beautifully finished piece of sculpture, one of the +volutes, apparently, of an Ionic capital. Was there another such +curiosity in the whole world? I broke open a few other nodules of +similar appearance, and found that there might be. In one of these there +were what seemed to be scales of fishes and the impressions of a few +minute bivalves, prettily striated; in the centre of another there was +actually a piece of decayed wood.</p> + +<p>Of all nature's riddles these seemed to me to be at once the most +interesting and the most difficult to expound. I treasured them +carefully up, and was told by one of the workmen to whom I showed them +that there was a part of the shore, about two miles further to the west, +where curiously shaped stones, somewhat like the heads of +boarding-pikes, were occasionally picked up, and that in his father's +day the country people called them thunderbolts. Our first half-holiday +I employed in visiting the place where the thunderbolts had fallen so +thickly, and<span class='pagenum'><a name="Page_257" id="Page_257">[Pg 257]</a></span> found it a richer scene of wonder than I could have +fancied even in my dreams.</p> + +<p>My first year of labour came to a close, and I found that the amount of +my happiness had not been less than in the last of my boyhood. My +knowledge had increased in more than the ratio of former seasons; and as +I had acquired the skill of at least the common mechanic, I had fitted +myself for independence.</p> + +<p>My curiosity, once fully awakened, remained awake, and my opportunities +of gratifying it have been tolerably ample. I have been an explorer of +caves and ravines, a loiterer along sea-shores, a climber among rocks, a +labourer in quarries. My profession was a wandering one. I remember +passing direct, on one occasion, from the wild western coast of +Ross-shire, where the Old Red Sandstone leans at a high angle against +the prevailing quartz of the district, to where, on the southern skirts +of Midlothian, the Mountain Limestone rises amid the coal. I have +resided one season on a raised beach of the Moray Firth. I have spent +the season immediately following amid the ancient granite and contorted +schists of the central Highlands. In the north I have laid open by +thousands the shells and lignites of the oolite; in the south I have +disinterred from their matrices of stone or of shale the huge reds and +tree ferns of the carboniferous period.</p> + +<p>I advise the stone-mason to acquaint himself with geology. Much of his +time must be spent amid the rocks and quarries of widely separated +localities, and so, in the course of a few years he may pass over the +whole geological scale, and this, too, with opportunities of observation +at every stage which can be shared with him by only the gentleman of +fortune who devotes his whole time to study. Nay, in some respects, his +advantages are superior to those of the amateur, for the man whose +employments have to be carried on in the same formation for months, +perhaps years, enjoys better opportunities<span class='pagenum'><a name="Page_258" id="Page_258">[Pg 258]</a></span> of arriving at just +conclusions. There are formations which yield their organisms slowly to +the discoverer, and the proofs which establish their place in the +geological scale more tardily still. I was acquainted with the Old Red +Sandstone of Ross and Cromarty for nearly ten years ere I ascertained +that it is richly fossiliferous; I was acquainted with it for nearly ten +years more ere I could assign its fossils to their exact place in the +scale. Nature is vast and knowledge limited, and no individual need +despair of adding to the general fund.</p> + + +<p class="subchap"><i>II.—Bridging Life's Gaps</i></p> + +<p>"The Old Red Sandstone," says a Scottish geologist in a digest of some +recent geological discoveries, "has hitherto been considered as +remarkably barren of fossils." Only a few years have gone by since men +of no low standing in the science disputed the very existence of this +formation—or system, rather, for it contains at least three distinct +formations. There are some of our British geologists who still regard it +as a sort of debatable tract, entitled to no independent status, a sort +of common which should be divided.</p> + +<p>It will be found, however, that this hitherto neglected system yields in +importance to none of the others, whether we take into account its +amazing depth, the great extent to which it is developed both at home +and abroad, the interesting links which it furnishes in the geological +scale, or the vast period of time which it represents. There are +localities in which the depth of the Old Red Sandstone fully equals the +elevation of Mount Etna over the level of the sea, and in which it +contains three distinct groups of organic remains, the one rising in +beautiful progression over the other.</p> + +<p>My first statement regarding the system must be much the reverse of the +one just quoted, for the fossils are remarkably numerous and in a state +of high preservation.<span class='pagenum'><a name="Page_259" id="Page_259">[Pg 259]</a></span> I have a hundred solid proofs by which to +establish the truth of the assertion within less than a yard of me. Half +my closet walls are covered with the peculiar fossils of the Lower Old +Red Sandstone; and certainly a stranger assemblage of forms has rarely +been grouped together—creatures whose very type is lost, fantastic and +uncouth, which puzzle the naturalist to assign them even to their class; +boat-like animals, furnished with oars and a rudder; fish, plated over, +like the tortoise, above and below, with a strong armour of bone, and +furnished with but one solitary rudder-like fin; other fish with the +membranes of their fins thickly covered with scales; creatures bristling +over with thorns; others glistening in an enamelled coat, as if +beautifully japanned; the tail in every instance among the less +equivocal shapes formed not equally, as in existing fish, on each side +the central vertebral column, but chiefly on the lower side—the column +sending out its diminished vertebræ to the extreme termination of the +fin. All the forms testify of a remote antiquity. The figures on a +Chinese vase or an Egyptian obelisk are scarce more unlike what now +exists in nature than are the fossils of the Lower Old Red Sandstone.</p> + +<p>Lamarck, on the strength of a few striking facts which prove that to a +certain extent the instincts of species may be improved and heightened, +has concluded that there is a natural progress from the inferior orders +of being towards the superior, and that the offspring of creatures low +in the scale may belong to a different and nobler species a few thousand +years hence. Never was there a fancy so wild and extravagant. The +principle of adaptation still leaves the vegetable a vegetable, and the +dog a dog. It is true that it is a law of nature that the chain of being +is in some degree a continuous chain, and the various classes of +existence shade into each other. All the animal families have their +connecting links. Geology abounds with creatures of the intermediate +class.</p> + +<p><span class='pagenum'><a name="Page_260" id="Page_260">[Pg 260]</a></span></p><p>Fishes seem to have been the master existences of two great geological +systems, mayhap of three, ere the age of reptiles began. Now, fishes +differ very much among themselves, some ranking nearly as low as worms, +some nearly as high as reptiles; and we find in the Old Red Sandstone +series of links which are wanting in the present creation, and the +absence of which occasions a wide gap between the two grand divisions of +fishes, the bony and the cartilaginous.</p> + +<p>Of all the organisms of the system one of the most extraordinary is the +pterichthys, or winged fish, which the writer had the pleasure of +introducing to the acquaintance of geologists. Had Lamarck been the +discoverer he would unquestionably have held that he had caught a fish +almost in the act of wishing itself into a bird. There are wings which +want only feathers, a body which seems to have been as well adapted for +passing through the air as through water, and a tail with which to +steer.</p> + +<p>My first idea regarding it was that I had discovered a connecting +link-between the tortoise and the fish. I submitted some of my specimens +to Mr. Murchison, and they furnished him with additional data by which +to construct the calculations he was then making respecting fossils, and +they added a new and very singular link to the chain of existence in its +relation to human knowledge. Agassiz confirmed the conclusions of +Murchison in almost every particular, deciding at once that the creature +must have been a fish.</p> + +<p>Next to the pterichthys of the Lower Old Red Sandstone I shall place its +contemporary the coccosteus of Agassiz—a fish which in some respects +must have resembled it. Both were covered with an armour of thickly +tubercled bony plates, and both furnished with a vertebrated tail. The +coccosteus seems to have been most abundant. Another of the families of +the ichthyolites of the Old Red Sandstone—the cephalaspis—seems<span class='pagenum'><a name="Page_261" id="Page_261">[Pg 261]</a></span> +almost to constitute a connecting link between fishes and crustaceans. +In the present creation fishes are either osseous or cartilaginous, that +is, with bony skeletons, or with a framework of elastic, +semi-transparent animal matter, like the shark; and the ichthyolites of +the Old Red Sandstone unite these characteristics, resembling in some +respects the osseous and in others the cartilaginous tribes. Agassiz at +once confirmed my suspicion that the ichthyolites of the Old Red +Sandstone were intermediate. Though it required skill to determine the +place of the pterichthys and coccosteus there could be no mistaking the +osteolepis—it must have been a fish, and a handsome one, too. But while +its head resembled the heads of the bony fishes, its tail differed in no +respects from the tails of the cartilaginous ones. And so through the +discovery of extinct species the gaps between existing species have been +bridged.</p> + + +<p class="subchap"><i>III.—Place-Fixing in the Dim Past</i></p> + +<p>The next step was to fix the exact place of the ichthyolites in the +geological scale, and this I was enabled to do by finding a large and +complete bed <i>in situ</i>. Its true place is a little more than a hundred +feet above the top, and not much more than a hundred yards above the +base of the great conglomerate.</p> + +<p>The Old Red Sandstone in Scotland and in England has its lower, middle, +and upper groups—three distinct formations. As the pterichthys and +coccosteus are the characteristic ichthyolites of the Lower Old Red +formation, so the cephalaspis distinguishes the middle or coronstone +division of the system in England. When we pass to the upper formation, +we find the holoptychius the most characteristic fossil.</p> + +<p>These fossils are found in a degree of entireness which depends less on +their age than on the nature of the rock in which they occur. Limestone +is the preserving salt of<span class='pagenum'><a name="Page_262" id="Page_262">[Pg 262]</a></span> the geological world, and the conservative +qualities of the shales and stratified clays of the Lower Old Red +Sandstone are not much inferior to limestone itself; while in the Upper +Old Red the beds of consolidated sand are much less conservative of +organic remains. The older fossils, therefore, can be described almost +as minutely as the existence of the present creation, whereas the newer +fossils exist, except in a few rare cases, as fragments, and demand the +powers of a Cuvier or an Agassiz to restore them to their original +combinations. On the other hand, while the organisms of the Lower Old +Red are numerous and well preserved, those of the Upper Old Red are much +greater in individual size. In short, the fish of the lower ocean must +have ranged in size between a stickleback and a cod; whereas some of the +fish of the ocean of the Upper Sandstone were covered with scales as +large as oyster shells, and were armed with teeth that rivalled in size +those of the crocodile.</p> + + +<p class="subchap"><i>IV.—Fish as Nature's Last Word</i></p> + +<p>I will now attempt to present to the reader the Old Red Sandstone as it +existed in time—during the succeeding periods of its formation, and +when its existences lived and moved as the denizens of primeval oceans. +We pass from the cemetery with its heaps of bones to the ancient city +full of life and animation in all its streets and dwellings.</p> + +<p>Before we commence our picture, two great geological periods have come +to their close, and the floor of the widely spread ocean is occupied to +the depth of many thousand feet by the remains of bygone existences. The +rocks of these two earlier periods are those of the Cambrian and +Silurian groups. The lower—Cambrian, representative of the first +glimmering twilight of being—must be regarded as a period of +uncertainty. It remains<span class='pagenum'><a name="Page_263" id="Page_263">[Pg 263]</a></span> for future discoverers to determine regarding +the shapes of life that burrowed in its ooze or careered through the +incumbent waters.</p> + +<p>There is less doubt respecting the existences of the Silurian rocks. +Four distinct platforms of being range in it, the one over the other, +like the stories of a building. Life abounded on all these platforms, +and in shapes the most wonderful. In the period of the Upper Silurian +fish, properly so called, and of a very perfect organisation, had taken +precedence of the crustacean. These most ancient beings of their class +were cartilaginous fishes, and they appear to have been introduced by +myriads. Such are the remains of what seem to have been the first +vertebrata.</p> + +<p>The history of the period represented by the Old Red Sandstone seems, in +what now forms the northern half of Scotland, to have opened amid +confusion and turmoil. The finely laminated Tilestones of England were +deposited evidently in a calm sea. During the contemporary period the +space which now includes Orkney, Lochness, Dingwall, Gamrie, and many a +thousand square miles besides, was the scene of a shallow ocean, +perplexed by powerful currents and agitated by waves. A vast stratum of +water-rolled pebbles, varying in depth from a hundred feet to a hundred +yards, remains, in a thousand different localities, to testify to the +disturbing agencies of this time of commotion, though it is difficult to +conceive how the bottom of any sea could have been so violently and +equally agitated for so greatly extended a space.</p> + +<p>The period of this shallow and stormy ocean passed, and the bottom, +composed of the identical conglomerate which now forms the summit of +some of our loftiest mountains, sank to a depth so profound as to be +little affected by tides and tempests. During this second period there +took place a vast deposit of coarse sandstone strata, and the subsidence +continued until fully ninety feet had<span class='pagenum'><a name="Page_264" id="Page_264">[Pg 264]</a></span> overlaid the conglomerate in +waters perfectly undisturbed. And here we find the first proof that this +ancient ocean literally swarmed with life—that its bottom was covered +with miniature forests of algae, and its waters darkened by immense +shoals of fish. I have seen the ichthyolite bed where they were as +thickly covered with fossil remains as I have ever seen a fishing-bank +covered with herrings.</p> + +<p>At this period some terrible catastrophe involved in sudden destruction +the fish of an area at least a hundred miles from boundary to boundary, +perhaps much more. The same platform in Orkney as in Cromarty is strewn +thick with remains which exhibit unequivocally the marks of violent +death. In what could it have originated? By what quiet but potent agency +of destruction could the innumerable existences of an area perhaps ten +thousand miles in extent be annihilated at once, and yet the medium in +which they lived be left undisturbed by its operations? The thought has +often struck me that calcined lime, cast out as ashes from some distant +crater and carried by the winds, might have been the cause of the widely +spread destruction to which the fossil organisms testify. I have seen +the fish of a small trouting stream, over which a bridge was in the +course of building, destroyed in a single hour, for a full mile below +the erection, by a few troughfuls of lime that fell into the water when +the centring was removed.</p> + +<p>The period of death passed, and over the innumerable dead there settled +a soft muddy sediment. For an unknown space of time, represented in the +formation by a deposit about fifty feet in thickness, the waters of the +depopulated area seem to have remained devoid of life. A few scales and +plates then begin to appear. The fish that had existed outside the chasm +seem to have gradually gained upon it as their numbers increased.</p> + +<p>The work of deposition went on and sandstone was<span class='pagenum'><a name="Page_265" id="Page_265">[Pg 265]</a></span> overlaid by stratified +clay. This upper bed had also its organisms, but the circumstances were +less favourable to the preservation of entire ichthyolites than those in +which the organisms were wrapped up in their stony coverings. Age +followed age, generations were entombed in ever-growing depositions. +Vast periods passed, and it seemed as if the power of the Creator had +reached its extreme limit when fishes had been called into existence, +and our planet was destined to be the dwelling-place of no nobler +inhabitants.</p> + +<p>The curtain rises, and the scene is new. The myriads of the lower +formation have disappeared, and we are surrounded on an upper platform +by the existences of a later creation. Shoals of cephalaspides, +feathered with fins, sweep past. We see the distant gleam of scales, +that some of the coats glitter with enamel, that others bristle over +with minute thorny points. A huge crustacean, of uncouth proportions, +stalks over the weedy bottoms, or burrows in the hollows of the banks. +Ages and centuries pass—who can sum up their number?—for the depth of +this middle formation greatly exceeds that of the other two.</p> + +<p>The curtain rises. A last day had at length come to the period of the +middle formation, and in an ocean roughened by waves and agitated by +currents we find new races of existences. We may mark the clumsy bulk of +the Holoptychius conspicuous in the group. The shark family have their +representative as before; a new variety of the pterichthys spreads out +its spear-like wings at every alarm, like its predecessor of the lower +formation. Fish still remained the lords of creation, and their bulk, at +least, had become immensely more great. We began with an age of dwarfs, +we end with an age of giants, which is carried on into the lower coal +measures. We pursue our history no further?</p> + +<p>Has the last scene in the series arisen? Cuvier asked the question, +hesitated, and then decided in the<span class='pagenum'><a name="Page_266" id="Page_266">[Pg 266]</a></span> negative, for he was too intimately +acquainted with the works of the Creator to think of limiting His power, +and he could anticipate a coming period in which man would have to +resign his post of honour to some nobler and wiser creature, the monarch +of a better and happier world.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_267" id="Page_267">[Pg 267]</a></span></p> +<h3>SIR ISAAC NEWTON</h3> + +<p class="book"><big><a name="Principia" id="Principia"></a>Principia</big></p> + +<div class="blockquot"><p>Sir Isaac Newton was born at Woolsthorpe, Lincolnshire, England, +Dec. 25, 1642, the son of a small landed proprietor. For the famous +episode of the falling apple, Voltaire, who admirably explained his +system for his countrymen, is responsible. It was in 1680 that +Newton discovered how to calculate the orbit of a body moving under +a central force, and showed that if the force varied as the inverse +square of the distance, the orbit would be an ellipse with the +centre of force in one focus. The great discovery, which made the +writing of his "Philosophiæ Naturalis Principia Mathematica" +possible, was that the attraction between two spheres is the same +as it would be if we supposed each sphere condensed to a point at +its centre. The book was published as a whole in 1687. Of its +author it was said by Lagrange that not only was he the greatest +genius that ever existed, but also the most fortunate, "for we +cannot find more than once a system of the world to establish." +Newton died on March 20, 1727.</p></div> + + +<p><span class="smcap">Our</span> design (writes Newton in his preface) not respecting arts but +philosophy, and our subject not manual but natural powers, we consider +those things which relate to gravity, levity, elastic force, the +resistance of fluids and the like forces, whether attractive or +impulsive; and, therefore, we offer this work as the mathematical +principles of philosophy, for all the difficulty of philosophy seems to +consist in this—from the phenomena of motions to investigate the forces +of nature, and from these forces to demonstrate the other phenomena, and +to this end the general propositions in the first and second book are +directed. In the third book, we give an example of this in the +explication of the system of the world; for by the propositions +mathematically demonstrated in the former books, we in the third derive +from the celestial phenomena the forces of gravity with which bodies +tend<span class='pagenum'><a name="Page_268" id="Page_268">[Pg 268]</a></span> to the sun and the several planets. Then from these forces, by +other propositions which are also mathematical, we deduce the motions of +the planets, the comets, the moon, and the sea.</p> + +<p>Upon this subject I had (he says) composed the third book in a popular +method, that it might be read by many, but afterward, considering that +such as had not sufficiently entered into the principles could not +easily discern the strength of the consequences, nor lay aside the +prejudices to which they had been many years accustomed, therefore, to +prevent the disputes which might be raised upon such accounts, I chose +to reduce the substance of this book into the form of Propositions (in +the mathematical way). So that this third book is composed both "in +popular method" and in the form of mathematical propositions.</p> + + +<p class="subchap"><i>Books I and II</i></p> + +<p>The principle of universal gravitation, namely, "That every particle of +matter is attracted by or gravitates to every other particle of matter +with a force inversely proportional to the squares of their distances," +is the discovery which characterises the "Principia." This principle the +author deduced from the motion of the moon and the three laws of Kepler; +and these laws in turn Newton, by his greater law, demonstrated to be +true.</p> + +<p>From the first law of Kepler, namely, the proportionality of the areas +to the times of their description, Newton inferred that the force which +retained the planet in its orbit was always directed to the sun. From +the second, namely, that every planet moves in an ellipse with the sun +as one of foci, he drew the more general inference that the force by +which the planet moves round that focus varies inversely as the square +of its distance therefrom. He demonstrated that a planet acted upon by<span class='pagenum'><a name="Page_269" id="Page_269">[Pg 269]</a></span> +such a force could not move in any other curve than a conic section; and +he showed when the moving body would describe a circular, an elliptical, +a parabolic, or hyperbolic orbit. He demonstrated, too, that this force +or attracting, gravitating power resided in even the least particle; but +that in spherical masses it operates as if confined to their centres, so +that one sphere or body will act upon another sphere or body with a +force directly proportional to the quantity of matter and inversely as +the square of the distance between their centres, and that their +velocities of mutual approach will be in the inverse ratio of their +quantities of matter. Thus he outlined the universal law.</p> + + +<p class="subchap"><i>The System of the World</i></p> + +<p>It was the ancient opinion of not a few (writes Newton in Book III.) in +the earliest ages of philosophy that the fixed stars stood immovable in +the highest parts of the world; that under the fixed stars the planets +were carried about the sun; that the earth, as one of the planets, +described an annual course about the sun, while, by a diurnal motion, it +was in the meantime revolved about its own axis; and that the sun, as +the common fire which served to warm the whole, was fixed in the centre +of the universe. It was from the Egyptians that the Greeks derived their +first, as well as their soundest notions of philosophy. It is not to be +denied that Anaxagoras, Democritus and others would have it that the +earth possessed the centre of the world, but it was agreed on both sides +that the motions of the celestial bodies were performed in spaces +altogether free and void of resistance. The whim of solid orbs was<a name="FNanchor_1_1" id="FNanchor_1_1"></a><a href="#Footnote_1_1" class="fnanchor">[1]</a> of +later date, introduced by Endoxus, Calippus and Aristotle, when the +ancient philosophy began to decline.</p> + +<p><span class='pagenum'><a name="Page_270" id="Page_270">[Pg 270]</a></span></p><p>As it was the unavoidable consequence of the hypothesis of solid orbs +while it prevailed that the comets must be thrust down below the moon, +so no sooner had the late observations of astronomers restored the +comets to their ancient places in the higher heavens than these +celestial spaces were at once cleared of the encumbrance of solid orbs, +which by these observations were broken to pieces and discarded for +ever.</p> + +<p>Whence it was that the planets came to be retained within any certain +bounds in these free spaces, and to be drawn off from the rectilinear +courses, which, left to themselves, they should have pursued, into +regular revolutions in curvilinear orbits, are questions which we do not +know how the ancients explained; and probably it was to give some sort +of satisfaction to this difficulty that solid orbs were introduced.</p> + +<p>The later philosophers pretend to account for it either by the action of +certain vortices, as Kepler and Descartes, or by some other principle of +impulse or attraction, for it is most certain that these effects must +proceed from the action of some force or other. This we will call by the +general name of a centripetal force, as it is a force which is directed +to some centre; and, as it regards more particularly a body in that +centre, we call it circum-solar, circum-terrestrial, circum-jovial.</p> + + +<p class="subchap"><i>Centre-Seeking Forces</i></p> + +<p>That by means of centripetal forces the planets may be retained in +certain orbits we may easily understand if we consider the motions of +projectiles, for a stone projected is by the pressure of its own weight +forced out of the rectilinear path, which, by the projection alone, it +should have pursued, and made to describe a curve line in the air; and +through that crooked way is at last brought down to the ground, and the +greater the velocity is with which it is projected the further it goes +before it<span class='pagenum'><a name="Page_271" id="Page_271">[Pg 271]</a></span> falls to earth. We can, therefore, suppose the velocity to be +so increased that it would describe an arc of 1, 2, 5, 10, 100, 1,000 +miles before it arrived at the earth, till, at last, exceeding the +limits of the earth, it should pass quite by it without touching it.</p> + +<p>And because the celestial motions are scarcely retarded by the little or +no resistance of the spaces in which they are performed, to keep up the +parity of cases, let us suppose either that there is no air about the +earth or, at least, that it is endowed with little or no power of +resisting.</p> + +<p>And since the areas which by this motion it describes by a radius drawn +to the centre of the earth have previously been shown to be proportional +to the times in which they are described, its velocity when it returns +to the point from which it started will be no less than at first; and, +retaining the same velocity, it will describe the same curve over and +over by the same law.</p> + +<p>But if we now imagine bodies to be projected in the directions of lines +parallel to the horizon from greater heights, as from 5, 10, 100, 1,000 +or more miles, or, rather, as many semi-diameters of the earth, those +bodies, according to their different velocity and the different force of +gravity in different heights, will describe arcs either concentric with +the earth or variously eccentric, and go on revolving through the +heavens in those trajectories just as the planets do in their orbs.</p> + +<p>As when a stone is projected obliquely, the perpetual deflection thereof +towards the earth is a proof of its gravitation to the earth no less +certain than its direct descent when suffered to fall freely from rest, +so the deviation of bodies moving in free spaces from rectilinear paths +and perpetual deflection therefrom towards any place, is a sure +indication of the existence of some force which from all quarters impels +those bodies towards that place.</p> + +<p>That there are centripetal forces actually directed to<span class='pagenum'><a name="Page_272" id="Page_272">[Pg 272]</a></span> the bodies of +the sun, of the earth, and other planets, I thus infer.</p> + +<p>The moon revolves about our earth, and by radii drawn to its centre +describes areas nearly proportional to the times in which they are +described, as is evident from its velocity compared with its apparent +diameter; for its motion is slower when its diameter is less (and +therefore its distance greater), and its motion is swifter when its +diameter is greater.</p> + +<p>The revolutions of the satellites of Jupiter about the planet are more +regular; for they describe circles concentric with Jupiter by equable +motions, as exactly as our senses can distinguish.</p> + +<p>And so the satellites of Saturn are revolved about this planet with +motions nearly circular and equable, scarcely disturbed by any +eccentricity hitherto observed.</p> + +<p>That Venus and Mercury are revolved about the sun is demonstrable from +their moon-like appearances. And Venus, with a motion almost uniform, +describes an orb nearly circular and concentric with the sun. But +Mercury, with a more eccentric motion, makes remarkable approaches to +the sun and goes off again by turns; but it is always swifter as it is +near to the sun, and therefore by a radius drawn to the sun still +describes areas proportional to the times.</p> + +<p>Lastly, that the earth describes about the sun, or the sun about the +earth, by a radius from one to the other, areas exactly proportional to +the times is demonstrable from the apparent diameter of the sun compared +with its apparent motion.</p> + +<p>These are astronomical experiments; from which it follows that there are +centripetal forces actually directed to the centres of the earth, of +Jupiter, of Saturn, and of the sun.<a name="FNanchor_2_2" id="FNanchor_2_2"></a><a href="#Footnote_2_2" class="fnanchor">[2]</a></p> + +<p><span class='pagenum'><a name="Page_273" id="Page_273">[Pg 273]</a></span></p><p>That these forces decrease in the duplicate proportion of the distances +from the centre of every planet appears by Cor. vi., Prop. iv., Book +I.<a name="FNanchor_3_3" id="FNanchor_3_3"></a><a href="#Footnote_3_3" class="fnanchor">[3]</a> for the periodic times of the satellites of Jupiter are one to +another in the sesquiplicate proportion of their distances from the +centre of this planet. Cassini assures us that the same proportion is +observed in the circum-Saturnal planets. In the circum-solar planets +Mercury and Venus, the same proportional holds with great accuracy.</p> + +<p>That Mars is revolved about the sun is demonstrated from the phases +which it shows and the proportion of its apparent diameters; for from +its appearing full near conjunction with the sun and gibbous in its +quadratures,<a name="FNanchor_4_4" id="FNanchor_4_4"></a><a href="#Footnote_4_4" class="fnanchor">[4]</a> it is certain that it travels round the sun. And since +its diameter appears about five times greater when in opposition to the +sun than when in conjunction therewith, and its distance from the earth +is reciprocally as its apparent diameter, that distance will be about +five times less when in opposition to than when in conjunction with the +sun; but in both cases its distance from the sun will be nearly about +the same with the distance which is inferred from its gibbous appearance +in the quadratures.<span class='pagenum'><a name="Page_274" id="Page_274">[Pg 274]</a></span> And as it encompasses the sun at almost equal +distances, but in respect of the earth is very unequally distant, so by +radii drawn to the sun it describes areas nearly uniform; but by radii +drawn to the earth it is sometimes swift, sometimes stationary, and +sometimes retrograde.</p> + +<p>That Jupiter in a higher orbit than Mars is likewise revolved about the +sun with a motion nearly equable as well in distance as in the areas +described, I infer from Mr. Flamsted's observations of the eclipses of +the innermost satellite; and the same thing may be concluded of Saturn +from his satellite by the observations of Mr. Huyghens and Mr. Halley.</p> + +<p>If Jupiter was viewed from the sun it would never appear retrograde or +stationary, as it is seen sometimes from the earth, but always to go +forward with a motion nearly uniform. And from the very great inequality +of its apparent geocentric motion we infer—as it has been previously +shown that we may infer—that the force by which Jupiter is turned out +of a rectilinear course and made to revolve in an orbit is not directed +to the centre of the earth. And the same argument holds good in Mars and +in Saturn. Another centre of these forces is, therefore, to be looked +for, about which the areas described by radii intervening may be +equable; and that this is the sun, we have proved already in Mars and +Saturn nearly, but accurately enough in Jupiter.</p> + +<p>The distances of the planets from the sun come out the same whether, +with Tycho, we place the earth in the centre of the system, or the sun +with Copernicus; and we have already proved that, these distances are +true in Jupiter. Kepler and Bullialdus have with great care determined +the distances of the planets from the sun, and hence it is that their +tables agree best with the heavens. And in all the planets, in Jupiter +and Mars, in Saturn and the earth, as well as in Venus and Mercury, the +cubes of their distances are as the squares of their periodic times; +and, therefore, the centripetal <span class='pagenum'><a name="Page_275" id="Page_275">[Pg 275]</a></span>circum-solar force throughout all the +planetary regions decreases in the duplicate proportion of the distances +from the sun. Neglecting those little fractions which may have arisen +from insensible errors of observation, we shall always find the said +proportion to hold exactly; for the distances of Saturn, Jupiter, Mars, +the Earth, Venus, and Mercury from the sun, drawn from the observations +of astronomers, are (Kepler) as the numbers 951,000, 519,650, 152,350, +100,000, 70,000, 38,806; or (Bullialdus) as the numbers 954,198, +522,520, 152,350, 100,000, 72,398, 38,585; and from the periodic times +they come out 953,806, 520,116, 152,399, 100,000, 72,333, 38,710. Their +distances, according to Kepler and Bullialdus, scarcely differ by any +sensible quantity, and where they differ most the differences drawn from +the periodic times fall in between them.</p> + + +<p class="subchap"><i>Earth as a Centre</i></p> + +<p>That the circum-terrestrial force likewise decreases in the duplicate +proportion of the distances, I infer thus:</p> + +<p>The mean distance of the moon from the centre of the earth is, we may +assume, sixty semi-diameters of the earth; and its periodic time in +respect of the fixed stars 27 days 7 hr. 43 min. Now, it has been shown +in a previous book that a body revolved in our air, near the surface of +the earth supposed at rest, by means of a centripetal force which should +be to the same force at the distance of the moon in the reciprocal +duplicate proportion of the distances from the centre of the earth, that +is, as 3,600 to 1, would (secluding the resistance of the air) complete +a revolution in 1 hr. 24 min. 27 sec.</p> + +<p>Suppose the circumference of the earth to be 123,249,600 Paris feet, +then the same body deprived of its circular motion and falling by the +impulse of the same centripetal force as before would in one second of +time describe 15<span class="above">1</span>⁄<span class="below">12</span> Paris feet. This we infer by a calculus<span class='pagenum'><a name="Page_276" id="Page_276">[Pg 276]</a></span> formed +upon Prop. xxxvi. ("To determine the times of the descent of a body +falling from a given place"), and it agrees with the results of Mr. +Huyghens's experiments of pendulums, by which he demonstrated that +bodies falling by all the centripetal force with which (of whatever +nature it is) they are impelled near the surface of the earth do in one +second of time describe 15<span class="above">1</span>⁄<span class="below">12</span> Paris feet.</p> + +<p>But if the earth is supposed to move, the earth and moon together will +be revolved about their common centre of gravity. And the moon (by Prop, +lx.) will in the same periodic time, 27 days 7 hr. 43 min., with the +same circum-terrestrial force diminished in the duplicate proportion of +the distance, describe an orbit whose semi-diameter is to the +semi-diameter of the former orbit, that is, to the sixty semi-diameters +of the earth, as the sum of both the bodies of the earth and moon to the +first of two mean proportionals between this sum and the body of the +earth; that is, if we suppose the moon (on account of its mean apparent +diameter 31<span class="above">1</span>⁄<span class="below">2</span> min.) to be about <span class="above">1</span>⁄<span class="below">42</span> of the earth, as 43 to +<span class="radic"><sup>3</sup>√</span><span class="radicand"><small>42 + 42</small><sup>2</sup></span> +or as about 128 to 127. And, therefore, the semi-diameter of +the orbit—that is, the distance of the centres of the moon and +earth—will in this case be 60<span class="above">1</span>⁄<span class="below">2</span> semi-diameters of the earth, almost +the same with that assigned by Copernicus; and, therefore, the duplicate +proportion of the decrement of the force holds good in this distance. +(The action of the sun is here disregarded as inconsiderable.)</p> + +<p>This proportion of the decrement of the forces is confirmed from the +eccentricity of the planets, and the very slow motion of their apsides; +for in no other proportion, it has been established, could the +circum-solar planets once in every revolution descend to their least, +and once ascend to their greatest distance from the sun, and the places +of those distances remain immovable. A small error from the duplicate +proportion would produce a<span class='pagenum'><a name="Page_277" id="Page_277">[Pg 277]</a></span> motion of the apsides considerable in every +revolution, but in many enormous.</p> + + +<p class="subchap"><i>The Tides</i></p> + +<p>While the planets are thus revolved in orbits about remote centres, in +the meantime they make their several rotations about their proper axes: +the sun in 26 days, Jupiter in 9 hr. 56 min., Mars in 24<span class="above">2</span>⁄<span class="below">3</span> hr., Venus +in 23 hr., and in like manner is the moon revolved about its axis in 27 +days 7 hr. 43 min.; so that this diurnal motion is equal to the mean +motion of the moon in its orbit; upon which account the same face of the +moon always respects the centre about which this mean motion is +performed—that is, the exterior focus of the moon's orbit nearly.</p> + +<p>By reason of the diurnal revolutions of the planets the matter which +they contain endeavours to recede from the axis of this motion; and +hence the fluid parts, rising higher towards the equator than about the +poles, would lay the solid parts about the equator under water if those +parts did not rise also; upon which account the planets are something +thicker about the equator than about the poles.</p> + +<p>And from the diurnal motion and the attractions of the sun and moon our +sea ought twice to rise and twice to fall every day, as well lunar as +solar. But the two motions which the two luminaries raise will not +appear distinguished but will make a certain mixed motion. In the +conjunction or opposition of the luminaries their forces will be +conjoined and bring on the greatest flood and ebb. In the quadratures +the sun will raise the waters which the moon depresseth and depress the +waters which the moon raiseth; and from the difference of their forces +the smallest of all tides will follow.</p> + +<p>But the effects of the lumniaries depend upon their distances from the +earth, for when they are less distant their effects are greater and when +more distant their<span class='pagenum'><a name="Page_278" id="Page_278">[Pg 278]</a></span> effects are less, and that in the triplicate +proportion of their apparent diameters. Therefore it is that the sun in +winter time, being then in its perigee, has a greater effect, whether +added to or subtracted from that of the moon, than in the summer season, +and every month the moon, while in the perigee raiseth higher tides than +at the distance of fifteen days before or after when it is in its +apogee.</p> + +<p>The fixed stars being at such vast distances from one another, can +neither attract each other sensibly nor be attracted by our sun.</p> + + +<p class="subchap"><i>Comets</i></p> + +<p>There are three hypotheses about comets. For some will have it that they +are generated and perish as often as they appear and vanish; others that +they come from the regions of the fixed stars, and are near by us in +their passage through the sytem of our planets; and, lastly, others that +they are bodies perpetually revolving about the sun in very eccentric +orbits.</p> + +<p>In the first case, the comets, according to their different velocities, +will move in conic sections of all sorts; in the second they will +describe hyperbolas; and in either of the two will frequent +indifferently all quarters of the heavens, as well those about the poles +as those towards the ecliptic; in the third their motions will be +performed in eclipses very eccentric and very nearly approaching to +parabolas. But (if the law of the planets is observed) their orbits will +not much decline from the plane of the ecliptic; and, so far as I could +hitherto observe, the third case obtains; for the comets do indeed +chiefly frequent the zodiac, and scarcely ever attain to a heliocentric +latitude of 40 degrees. And that they move in orbits very nearly +parabolical, I infer from their velocity; for the velocity with which a +parabola is described is everywhere to the velocity with which a comet +or planet may be revolved about the sun in<span class='pagenum'><a name="Page_279" id="Page_279">[Pg 279]</a></span> a circle at the same +distance in the subduplicate ratio of 2 to 1; and, by my computation, +the velocity of comets is found to be much about the same. I examined +the thing by inferring nearly the velocities from the distances, and the +distances both from the parallaxes and the phenomena of the tails, and +never found the errors of excess or defect in the velocities greater +than what might have arisen from the errors in the distances collected +after that manner.</p> + + + +<hr /><p><span class='pagenum'><a name="Page_280" id="Page_280">[Pg 280]</a></span></p> +<h3>SIR RICHARD OWEN</h3> + +<p class="book"><big><a name="Anatomy_of_Vertebrates" id="Anatomy_of_Vertebrates"></a>Anatomy of Vertebrates</big></p> + +<div class="blockquot"><p>Sir Richard Owen, the great naturalist, was born July 20, 1804, at +Lancaster, England, and received his early education at the grammar +school of that town. Thence he went to Edinburgh University. In +1826 he was admitted a member of the English College of Surgeons, +and in 1829 was lecturing at St. Bartholomew's Hospital, London, +where he had completed his studies. His "Memoir on the Pearly +Nautillus," published in 1832, placed him, says Huxley, "at a bound +in the front rank of anatomical monographers," and for sixty-two +years the flow of his contributions to scientific literature never +ceased. In 1856 he was appointed to take charge of the natural +history departments of the British Museum, and before long set +forth views as to the inadequacy of the existing accommodation, +which led ultimately to the foundation of the buildings now devoted +to this purpose in South Kensington. Owen died on December 18, +1892. His great book, "Comparative Anatomy and Physiology of the +Vertebrates," was completed in 1868, and since Cuvier's +"Comparative Anatomy," is the most monumental treatise on the +subject by any one man. Although much of the classification adopted +by Owen has not been accepted by other zoologists, yet the work +contains an immense amount of information, most of which was gained +from Owen's own personal observations and dissections.</p></div> + + +<p class="subchap"><i>I.—Biological Questions of 1830</i></p> + +<p><span class="smcap">At</span> the close of my studies at the Jardin des Plantes, Paris, in 1831, I +returned strongly moved to lines of research bearing upon the then +prevailing phases of thought on some biological questions.</p> + +<p>The great master in whose dissecting rooms I was privileged to work held +that species were not permanent as a fact established inductively on a +wide basis of observation, by which comparative osteology had been +created. Camper and Hunter suspected the species might be transitory; +but Cuvier, in defining the <span class='pagenum'><a name="Page_281" id="Page_281">[Pg 281]</a></span>characters of his anaplotherium and +palæotherium, etc., proved the fact. Of the relation of past to present +species, Cuvier had not an adequate basis for a decided opinion. +Observation of changes in the relative position of land and sea +suggested to him one condition of the advent of new species on an island +or continent where old species had died out. This view he illustrates by +a hypothetical case of such succession, but expressly states: "I do not +assert that a new creation was necessary to produce the species now +existing, but only that they did not exist in the same regions, and must +have come from elsewhere." Geoffrey Saint Hilaire opposed to Cuvier's +inductive treatment of the question the following expression of belief: +"I have no doubt that existing animals are directly descended from the +animals of the antediluvian world," but added, "it is my belief that the +season has not yet arrived for a really satisfying knowledge of +geology."</p> + +<p>The main collateral questions argued in their debates appeared to me to +be the following:</p> + +<p>Unity of plan or final purpose, as a governing condition of organic +development?</p> + +<p>Series of species, uninterrupted or broken by intervals?</p> + +<p>Extinction, cataclysmal or regulated?</p> + +<p>Development, by epigenesis or evolution?</p> + +<p>Primary life, by miracle or secondary law?</p> + +<p>Cuvier held the work of organisation to be guided and governed by final +purpose or adaptation. Geoffrey denied the evidence of design and +contended for the principle which he called "unity of composition," as +the law of organisation. Most of his illustrations were open to the +demonstration of inaccuracy; and the language by which disciples of the +kindred school of Schelling illustrated in the animal structure the +transcendental idea of the whole in every part seemed little better than +mystical jargon. With Cuvier, answerable parts occurred in the +zoological scale because they had to perform similar functions.</p> + +<p><span class='pagenum'><a name="Page_282" id="Page_282">[Pg 282]</a></span></p><p>As, however, my observations and comparisons accumulated, they enforced +a reconsideration of Cuvier's conclusions. To demonstrate the evidence +of the community of organisation I found the artifice of an archetype +vertebrate animal essential; and from the demonstration of its +principle, which I then satisfied myself was associated with and +dominated by that of "adaptation to purpose," the step was inevitable to +the conception of the operation of a secondary cause of the entire +series of species, such cause being the servant of predetermining +intelligent will.</p> + +<p>But besides "derivation" or "filiation" another principle influencing +organisation became recognisable, to which I gave the name of +"irrelative repetition," or "vegetative repetition." The demonstrated +constitution of the vertebrate endoskeleton as a series of essentially +similar segments appeared to me to illustrate the law of irrelative +repetition.</p> + +<p>These results of inductive research swayed me in rejecting direct or +miraculous creation, and in recognising a "natural law or secondary +cause" as operative in the production of species "in orderly succession +and progression."</p> + + +<p class="subchap"><i>II.—Succession of Species, Broken or Linked?</i></p> + +<p>To the hypothesis that existing are modifications of extinct species, +Cuvier replied that traces of modification were due from the fossil +world. "You ought," he said, "to be able to show the intermediate forms +between the palæotherium and existing hoofed quadrupeds."</p> + +<p>The progress of palæontology since 1830 has brought to light many +missing links unknown to the founder of the science. The discovery of +the remains of the hipparion supplied one of the links required by +Cuvier, and it is significant that the remains of such three-toed horses +are found only in deposits of that tertiary period<span class='pagenum'><a name="Page_283" id="Page_283">[Pg 283]</a></span> which intervene +between the older palæotherian one and the newer strata in which the +modern horse first appears to have lost its lateral hooflets.</p> + +<p>The molar series of the horse includes six large complex grinders +individually recognisable by developmental characters. The +representative of the first premolar is minute and soon shod. Its +homologue in palæotherium is functionally developed and retained, that +type-dentition being adhered to. In hipparion this tooth is smaller than +in palæotherium, but functional and permanent. The transitory and +singularly small and simple denticle in the horse exemplifies the +rudiment of an ancestral structure in the same degree as do the hoofless +splint-bones; just as the spurious hoofs dangling therefrom in hipparion +are retained rudiments of the functionally developed lateral hoofs in +the broader foot of palæotherium.</p> + +<p>Other missing links of this series of species have also been supplied.</p> + +<p>How then is the origin of these intermediate gradations to be +interpreted? If the alternative—species by miracle or by law—be +applied to palæotherium, paloplotherium, anchitherium, hipparion, equus, +I accept the latter without misgiving, and recognise such law as +continuously operative throughout tertiary time.</p> + +<p>In respect to its law of operation we may suppose Lamarck to say, "as +the surface of the earth consolidated, the larger and more produced +mid-hoof of the old three-toed pachyderius took a greater share in +sustaining the animal's weight; and more blood being required to meet +the greater demand of the more active mid-toe, it grew; whilst, the +side-toes, losing their share of nourishment and becoming more and more +withdrawn from use, shrank"—and so on. Mr. Darwin, I conceive, would +modify this by saying that some individuals of palæotherium happening to +be born with a larger and longer middle toe, and with shorter and +smaller side-toes, such variety was better adapted to prevailing altered +<span class='pagenum'><a name="Page_284" id="Page_284">[Pg 284]</a></span>conditions of the earth's surface than the parental form; and so on, +until finally the extreme equine modifications of foot came to be +"naturally selected." But the hypothesis of appetency and volition, as +of natural selection, are less applicable, less intelligible, in +connection with the changes in the teeth.</p> + +<p>I must further observe that to say the palæotherium has graduated into +equus by "natural selection" is an explanation of the process of the +same kind and value as that by which the secretion of bile was +attributed to the "appetency" of the liver for the elements of bile. +One's surprise is that such explanatory devices should not have died out +with the "archeus faber," the "nisus formations," and other +self-deceiving, world-beguiling simulacra of science, with the last +century; and that a resuscitation should have had any success in the +present.</p> + +<p>What, then, are the facts on which any reasonable or intelligible +conception can be formed of the mode of operation of the derivative law +exemplified in the series linking on palæotherium to equus? A very +significant one is the following. A modern horse occasionally comes into +the world with the supplementary ancestral hoofs. From Valerius Maximus, +who attributes the variety to Bucephalus downwards, such "polydactyle" +horses have been noted as monsters and marvels. In one of the latest +examples, the inner splint-bone, answering to the second metacarpal of +the pentadactyle foot, supported phalanges and a terminal hoof +resembling the corresponding one in hipparion. And the pairing of horses +with the meterpodials bearing, according to type, phalanges and hoofs +might restore the race of hipparions.</p> + +<p>Now, the fact suggesting such possibility teaches that the change would +be sudden and considerable; it opposes the idea that species are +transmuted by minute and slow degrees. It also shows that a species +might originate independently of the operation of any external +influence; that change of structure would precede that of use and<span class='pagenum'><a name="Page_285" id="Page_285">[Pg 285]</a></span> +habit; that appetency, impulse, ambient medium, fortuitous fitness of +surrounding circumstances, or a personified "selecting nature" would +have had no share in the transmutative act.</p> + +<p>Thus I have been led to recognise species as exemplifying the continuous +operation of natural law, or secondary cause; and that not only +successively but progressively; "from the first embodiment of the +vertebrate idea under its old ichthyic vestment until it became arrayed +in the glorious garb of the human form."</p> + + +<p class="subchap"><i>III.—Extinction—Cataclysmal or Regulated</i></p> + +<p>If the species of palæothere, paloplothere, anchithere, hipparion, and +horse be severally deemed due to remotely and successively repeated acts +of creation; the successive going out of such species must have been as +miraculous as their coming in. Accordingly, in Cuvier's "Discourse on +Revolutions of the Earth's Surface" we have a section of "Proofs that +these revolutions have been numerous," and another of "Proofs that these +revolutions have been sudden." But as the discoveries of palæontologists +have supplied the links between the species held to have perished by the +cataclysms, so each successive parcel of geological truth has tended to +dissipate the belief in the unusually sudden and violent nature of the +changes recognisable in the earth's surface. In specially directing my +attention to this moot point, whilst engaged in investigations of fossil +remains, I was led to recognise one cause of extinction as being due to +defeat in the contest which the individual of each species had to +maintain against the surrounding agencies which might militate against +its existence. This principle has received a large and most instructive +accession of illustrations from the labours of Charles Darwin; but he +aims to apply it not only to the extinction but to the origin of +species.</p> + +<p>Although I fail to recognise proof of the latter bearing<span class='pagenum'><a name="Page_286" id="Page_286">[Pg 286]</a></span> of the battle +of life, the concurrence of so much evidence in favour of extinction by +law is, in like measure, corroborative of the truth of the ascription of +the origin of species to a secondary cause.</p> + +<p>What spectacle can be more beautiful than that of the inhabitants of the +calm expanse of water of an atoll encircled by its ring of coral rock! +Leaving locomotive frequenters of the calcarious basin out of the +question, we may ask, Was direct creation after the dying out of its +result as a "rugose coral" repeated to constitute the succeeding and +superseding "tabulate coral"? Must we also invoke the miraculous power +to initiate every distinct species of both rugosa and tabulata? These +grand old groups have had their day and are utterly gone. When we +endeavour to conceive or realise such mode of origin, not of them only +but of their manifold successors, the miracle, by the very +multiplication of its manifestations, becomes incredible—inconsistent +with any worthy conception of an all-seeing, all-provident Omnipotence.</p> + +<p>Being unable to accept the volitional hypothesis (of Lamarck) or the +selective force exerted by outward circumstances (Darwin), I deem an +innate tendency to deviate from parental type, operating through periods +of adequate duration, to be the most probable way of operation of the +secondary law whereby species have been derived one from another.</p> + +<p>According to my derivative hypothesis a change takes place first in the +structure of the animal, and this, when sufficiently advanced, may lead +to modifications of habits. But species owe as little to the accidental +concurrence of environing circumstances as kosmos depends upon a +fortuitous concourse of atoms. A purposive route of development and +change of correlation and inter-dependence, manifesting intelligent +will, is as determinable in the succession of races as in the +development and organisation of the individual.</p> + +<p>Derivation holds that every species changes in time, by<span class='pagenum'><a name="Page_287" id="Page_287">[Pg 287]</a></span> virtue of +inherent tendencies thereto. Natural selection holds that no such change +can take place without the influence of altered external circumstances +educing or eliciting such change.</p> + +<p>Derivation sees among the effects of the innate tendency to change, +irrespective of altered surrounding circumstances, a manifestation of +creative power in the variety and beauty of the results; and, in the +ultimate forthcoming of a being susceptible of appreciating such beauty, +evidence of the preordaining of such relation of power to the +appreciation. Natural selection acknowledges that if power or beauty, in +itself, should be a purpose in creation, it would be absolutely fatal to +it as a hypothesis.</p> + +<p>Natural selection sees grandeur in the "view of life, with its several +powers, having been originally breathed by the Creator into a few forms +or into one." Derivation sees, therein, a narrow invocation of a special +miracle and an unworthy limitation of creative power, the grandeur of +which is manifested daily, hourly, in calling into life many forms, by +conversion of physical and chemical into vital modes of force, under as +many diversified conditions of the requisite elements to be so combined.</p> + +<p>Natural selection leaves the subsequent origin and succession of species +to the fortuitous concurrence of outward conditions; derivation +recognises a purpose in the defined and preordained course, due to +innate capacity or power of change, by which homogeneously-created +protozoa have risen to the higher forms of plants and animals.</p> + +<p>The hypothesis of derivation rests upon conclusions from four great +series of inductively established facts, together with a probable result +of facts of a fifth class; the hypothesis of natural selection totters +on the extension of a conjectural condition explanatory of extinction to +the origination of species, inapplicable in that extension to the +majority of organisms, and not known or observed to apply to the origin +of any species.</p> + + +<p><span class='pagenum'><a name="Page_288" id="Page_288">[Pg 288]</a></span></p><p class="subchap"><i>IV.—Epigenesis or Evolution?</i></p> + +<p>The derivative origin of species, then, being at present the most +admissible one, and the retrospective survey of such species showing +convergence, as time recedes, to more simplified or generalised +organisations, the result to which the suggested train of thought +inevitably leads is very analogous in each instance. If to kosmos or the +mundane system have been allotted powers equivalent to the development +of the several grades of life, may not the demonstrated series of +conversions of force have also included that into the vital form?</p> + +<p>In the last century, physiologists were divided as to the principle +guiding the work of organic development.</p> + +<p>The "evolutionists" contended that the new being preexisted in a +complete state of formation, needing only to be vivified by impregnation +in order to commence the series of expansions or disencasings, +culminating in the independent individual.</p> + +<p>The "epigenesists" held that both the germ and its subsequent organs +were built up of juxtaposed molecules according to the operation of a +developmental force, or "nisus formations."</p> + +<p>At the present day the question may seem hardly worth the paper on which +it is referred to. Nevertheless, "pre-existence of germs" and evolution +are logically inseparable from the idea of species by primary +miraculously-created individuals. Cuvier, therefore, maintained both as +firmly as did Haller. In the debates of 1830 I remained the thrall of +that dogma in regard to the origin of single-celled organisms whether in +or out of body. Every result of formfaction, I believed, with most +physiologists, to be the genetic outcome of a pre-existing "cell." The +first was due to miraculous interposition and suspension of ordinary +laws; it contained potentially all future possible cells. +Cell-development exemplified<span class='pagenum'><a name="Page_289" id="Page_289">[Pg 289]</a></span> evolution of pre-existing germs, the +progeny of the primary cell. They progagated themselves by +self-division, or by "proliferation" of minutes granules or atoms, +which, when properly nourished, again multiplied by self-division, and +grew to the likeness of the parent cells.</p> + +<p>It seems to me more consistent with the present phase of dynamical +science and the observed graduations of living things to suppose the +sarcode or the "protogenal" jelly-speck should be formable through the +concurrence of conditions favouring such combination of their elements, +and involving a change of force productive of their contractions and +extensions, molecular attractions, and repulsions—and the sarcode has +so become, from the period when its irrelative repetitions resulted in +the vast indefinite masses of the "eozoon," exemplifying the earliest +process of "formification" or organic crystallisation—than that all +existing sarcodes or "protogenes" are the result of genetic descent from +a germ or cell due to a primary act of miraculous interposition.</p> + +<p>I prefer, while indulging in such speculations, to consider the various +daily nomogeneously developed forms of protozoal or protistal jellies, +sarcodes, and single-celled organisms, to have been as many roots from +which the higher grades have ramified than that the origin of the whole +organic creation is to be referred, as the Egyptian priests did that of +the universe, to a single egg.</p> + +<p>Amber or steel, when magnetised, seem to exercise "selection"; they do +not attract all substances alike. A speck of protogenal jelly or +sarcode, if alive, shows analogous relations to certain substances; but +the soft yielding tissue allows the part next the attractive matter to +move thereto, and then, by retraction, to draw such matter into the +sarcodal mass, which overspreads, dissolves, and assimilates it. The +term "living" in the one case is correlative with the term "magnetic" in +the<span class='pagenum'><a name="Page_290" id="Page_290">[Pg 290]</a></span> other. A man perceives ripe fruit; he stretches out his hand, +plucks, masticates, swallows, and digests it.</p> + +<p>The question then arises whether the difference between such series of +actions in the man and the attractive and assimilative movement of the +amæba be greater or less than the difference between these acts of the +amæba and the attracting and retaining acts of the magnet.</p> + +<p>The question, I think, may be put with some confidence as to the quality +of the ultimate reply whether the amæbal phenomena are so much more +different, or so essentially different, from the magnetic phenomena than +they are from the mammalian phenomena, as to necessitate the invocation +of a special miracle for their manifestation. It is analogically +conceivable that the same cause which has endowed His world with power +convertible into magnetic, electric, thermotic and other forms or modes +of force, has also added the conditions of conversion into the vital +force.</p> + +<p>From protozoa or protista to plants and animals the graduation is closer +than from magnetised iron to vitalised sarcode. From reflex acts of the +nervous system animals rise to sentient and volitional ones. And with +the ascent are associated brain-cells progressively increasing in size +and complexity. Thought relates to the "brain" of man as does +electricity to the nervous "battery" of the torpedo; both are forms of +force and the results of action of their respective organs.</p> + +<p>Each sensation affects a cerebral fibre, and, in so affecting it, gives +it the faculty of repeating the action, wherein memory consists and +sensation in a dream.</p> + +<p>If the hypothesis of an abstract entity produces psychological phenomena +by playing upon the brain as a musician upon his instrument be rejected, +and these phenomena be held to be the result of cerebral actions, an +objection is made that the latter view is "materialistic" and adverse to +the notion of an independent, indivisible, "immaterial," mental +principle or soul.</p> + +<p><span class='pagenum'><a name="Page_291" id="Page_291">[Pg 291]</a></span></p><p>But in the endeavour to comprehend clearly and explain the functions of +the combination of forces called "brain," the physiologist is hindered +and troubled by the views of the nature of those cerebral forces which +the needs of dogmatic theology have imposed on mankind. How long +physiologists would have entertained the notion of a "life," or "vital +principle," as a distinct entity if freed from this baneful influence +may be questioned; but it can be truly affirmed that physiology has now +established and does accept the truth of that statement of Locke—"the +life, whether of a material or immaterial substance, is not the +substance itself, but an affection of it."</p> + + + +<hr /><p><span class='pagenum'><a name="Page_292" id="Page_292">[Pg 292]</a></span></p> +<h3>RUDOLF VIRCHOW</h3> + +<p class="book"><big><a name="Cellular_Pathology" id="Cellular_Pathology"></a>Cellular Pathology</big></p> + +<div class="blockquot"><p>Rudolf Virchow, the son of a small farmer and shopkeeper, was born +at Schivelbein, in Pomerania, on October 13, 1821. He graduated in +medicine at Berlin, and was appointed lecturer at the University, +but his political enthusiasm brought him into disfavour. In 1849 he +was removed to Wurzburg, where he was made professor of pathology, +but in 1856 he returned to Berlin as Professor and Director of the +Pathological Institute, and there acquired world-wide fame. His +celebrated work, "Cellular Pathology as based on Histology," +published in 1856, marks a distinct epoch in the science. Virchow +established what Lord Lister describes as "the true and fertile +doctrine that every morbid structure consists of cells which have +been derived from pre-existing cells as a progeny." Virchow was not +only distinguished as a pathologist, he also gained considerable +fame as an archæologist and anthropologist. During the wars of 1866 +and 1870–71, he equipped and drilled hospital corps and ambulance +squads, and superintended hospital trains and the Berlin military +hospital. War over, he directed his attention to sanitation and the +sewage problems of Berlin. Virchow was a voluminous author on a +variety of subjects, perhaps his most well-known works being +"Famine Fever" and "Freedom of Science." He died on September 5, +1902.</p></div> + + +<p class="subchap"><i>The Cell and the Tissues</i></p> + +<p><span class="smcap">The</span> chief point in the application of Histology to Pathology is to +obtain recognition of the fact that the cell is really the ultimate +morphological element in which there is any manifestation of life.</p> + +<p>In certain respects animal cells differ from vegetable cells; but in +essentials they are the same; both consist of matter of a nitrogenous +nature.</p> + +<p>When we examine a simple cell, we find we can distinguish morphological +parts. In the first place, we find in the cell a round or oval body +known as the nucleus. Occasionally the nucleus is stallate or angular; +but as a<span class='pagenum'><a name="Page_293" id="Page_293">[Pg 293]</a></span> rule, so long as cells have vital power, the nucleus maintains +a nearly constant round or oval shape. The nucleus in its turn, in +completely developed cells, very constantly encloses another structure +within itself—the so-called nucleolus. With regard to the question of +vital form, it cannot be said of the nucleolus that it appears to be an +absolute essential, and in a considerable number of young cells it has +as yet escaped detection. On the other hand, we regularly meet with it +in fully-developed, older forms, and it therefore seems to mark a higher +degree of development in the cell.</p> + +<p>According to the view which was put forward in the first instance by +Schleiden, and accepted by Schwann, the connection between the three +co-existent cell-constituents was long thought to be of this nature: +that the nucleolus was the first to show itself in the development of +tissues, by separating out of a formative fluid (blastema, +cyto-blastema), that it quickly attained a certain size, that then fine +granules were precipitated out of the blastema and settled around it, +and that about these there condensed a membrane. In this way a nucleus +was formed about which new matter gradually gathered, and in due time +produced a little membrane. This theory of the formation of the cell is +designated the theory of free cell formation—a theory which has been +now almost entirely abandoned.</p> + +<p>It is highly probable that the nucleus plays an extremely important part +within the cell—a part less connected with the function and specific +office of the cell, than with its maintenance and multiplication as a +living part. The specific (animal) function is most distinctly +manifested in muscles, nerves, and gland cells, the peculiar actions of +which—contraction, sensation, and secretion—appear to be connected in +no direct manner with the nuclei. But the permanency of the cell as an +element seems to depend on nucleus, for all cells which lose their +nuclei quickly die, and break up, and disappear.</p> + +<p><span class='pagenum'><a name="Page_294" id="Page_294">[Pg 294]</a></span></p><p>Every organism, whether vegetable or animal, must be regarded as a +progressive total, made up of a larger or smaller number of similar or +dissimilar cells. Just as a tree constitutes a mass arranged in a +definite manner in which, in every single part, in the leaves as in the +root, in the trunk as in the blossom, cells are discovered to be the +ultimate elements, so it is with the forms of animal life. Every animal +presents itself as a sum of vital unities, every one of which manifests +all the characteristics of life. The characteristics and unity of life +cannot be limited to any one particular spot in an organism (for +instance, to the brain of a man) but are to be found only in the +definite, constantly recurring structure, which every individual element +displays. A so-called individual always represents an arrangement of a +social kind, in which a number of individual existences are mutually +dependent, but in such a way that every element has its own special +action, and even though it derive its stimulus to activity from other +parts, yet alone affects the actual performance of its duties.</p> + +<p>Between cells there is a greater or less amount of a homogeneous +substance—the <i>intercellular substance</i>. According to Schwann, the +intercellular substance was cyto-blastema destined for the development +of new cells; I believe this is not so, I believe that the intercellular +substance is dependent in a certain definite manner upon the cells, and +that certain parts of it belong to one cell and parts to another.</p> + +<p>At various times, fibres, globules, and elementary granules, have been +regarded as histological starting-points. Now, however, we have +established the general principle that no development of any kind begins +<i>de novo</i> and that as spontaneous generation is impossible in the case +of entire organisms, so also it is impossible in the case of individual +parts. No cell can build itself up out of non-cellular material. Where a +cell arises, there a cell must have previously existed (omnis cellula e +cellula), just<span class='pagenum'><a name="Page_295" id="Page_295">[Pg 295]</a></span> as an animal can spring only from an animal, and a plant +only from a plant. No developed tissues can be traced back to anything +but a cell.</p> + +<p>If we wish to classify tissues, a very simple division offers itself. We +have (a) tissues which consist exclusively of cells, where cell lies +close to cell. (b) Tissues in which the cells are separated by a certain +amount of intercellular substance. (c) Tissues of a high or peculiar +type, such as the nervous and muscular systems and vessels. An example +of the first class is seen in the <i>epithelial</i> tissues. In these, cell +lies close to cell, with nothing between.</p> + +<p>The second class is exemplified in the <i>connective</i> tissues—tissues +composed of intercellular substance in which at certain intervals cells +lie embedded.</p> + +<p>Muscles, nerves, and vessels form a somewhat heterogeneous group. The +idea suggests itself that we have in all three structures to deal with +real tubes filled with more or less movable contents. This view is, +however, inadequate, since we cannot regard the blood as analogous to +the medullary substance of the nerve, or contractile substance of a +muscular fasciculus.</p> + +<p>The elements of muscle have generally been regarded as the most simple. +If we examine an ordinary red muscle, we find it to be composed of a +number of cylindrical fibres, marked with transverse and longitudinal +striæ. If, now, we add acetic acid, we discover also tolerably large +nuclei with nucleoli. Thus we obtain an appearance like an elongated +cell, and there is a tendency to regard the primitive fasciculus as +having sprung from a single cell. To this view I am much inclined.</p> + +<p>Pathological tissues arise from normal tissues; and there is no form of +morbid growth which cannot in its elements be traced back to some model +which had previously maintained an independent existence in the economy. +A classification, also, of pathological growths may<span class='pagenum'><a name="Page_296" id="Page_296">[Pg 296]</a></span> be made on exactly +the same plan as that which we have suggested in the case of the normal +tissues.</p> + + +<p class="subchap"><i>Nutrition, Blood, and Lymph. Pus</i></p> + +<p>Nutritive material is carried to the tissues by the blood; but the +material is accepted by the tissues only in accordance with their +requirements for the moment, and is conveyed to the individual districts +in suitable quantities. The muscular elements of the arteries have the +most important influence upon the quantity of the blood distributed, and +their elastic elements ensure an equable stream; but it is chiefly the +simple homogeneous membrane of the capillaries that influences the +permeation of the fluids. Not all the peculiarities, however, in the +interchange of nutritive material are to be attributed to the capillary +wall, for no doubt there are chemical affinities which enable certain +parts specially to attract certain substances from the blood. We know, +for example, that a number of substances are introduced into the body +which have special affinities for the nerve tissues, and that certain +materials are excreted by certain organs. We are therefore compelled to +consider the individual elements as active agents of the attraction. If +the living element be altered by disease, then it loses its power of +specific attraction.</p> + +<p>I do not regard the blood as the cause of chronic dyscrasiæ; for I do +not regard the blood as a permanent tissue independently regenerating +and propagating itself, but as a fluid in a state of constant dependence +upon other parts. I consider that every dyscrasia <i>is dependent upon a +permanent supply of noxious ingredients from certain sources</i>. As a +continual ingestion of injurious food is capable of vitiating the blood, +in like manner persistent disease in a definite organ is able to furnish +the blood with a continual supply of morbid materials.</p> + +<p>The essential point, therefore, is to search for the <i>local<span class='pagenum'><a name="Page_297" id="Page_297">[Pg 297]</a></span> sources</i> of +the different dyscrasiæ which cause disorders of the blood, for every +permanent change which takes place in the condition of the circulating +juices must be derived from definite organs or tissues.</p> + +<p>The blood contains certain morphological elements. It contains a +substance, <i>fibrine</i>, which appears as fibrillac when the blood clots, +and red and colourless blood corpuscles.</p> + +<p>The red blood corpuscles contain no nuclei except at certain periods of +the development of the embyro. They are lighter or darker red according +to the oxygen they contain. When treated with concentrated fluids they +shrivel; when treated with diluted fluids they swell. They are rather +coin-shaped, and when a drop of blood is quiet they are usually found +aggregated in rows, like rouleaux of money.</p> + +<p>The colourless corpuscles are much less numerous than the red +corpuscles—only one to 300—but they are larger, and contain nuclei. +When blood coagulates the white corpuscles sink more slowly and appear +as a lighter coloured layer on the top of the clot.</p> + +<p>Pus cells are very like colourless corpuscles, and the relation between +the two has been much debated. A pus cell can be distinguished from a +colourless blood cell only by its mode of origin. If it have an origin +external to the blood, it must be pus; if it originate in the blood, it +must be considered to be a blood cell.</p> + +<p>In the early stages of its development, a white blood corpuscle is seen +to modify by division; but in fully-developed blood such division is +never seen. It is probable that colourless white corpuscles are given to +the adult blood by the lymphatic glands. Every irritation of a part +which is freely connected with lymphatic glands increases the number of +colourless cells in the blood. Any excessive increase from this source I +have designated <i>leucocytosis</i>.</p> + +<p>In the first months of the embryo the red cell multiplies<span class='pagenum'><a name="Page_298" id="Page_298">[Pg 298]</a></span> by division. +In adult life the mode of its multiplication is unknown. They, also, are +probably formed in the lymphatic glands and spleen.</p> + +<p>In a disease I have named <i>leukæmia</i>, the colourless blood cells +increase in number enormously. In such cases there is always disease of +the spleen, and very often of the lymphatic glands.</p> + +<p>These facts can hardly, I think, be interpreted in any other manner than +by supposing that the spleen and lymphatic glands are intimately +concerned in the production of the formed elements of the blood.</p> + +<p>By <i>pyæmia</i> is meant pus corpuscles in the blood. But most cases of +so-called pyæmia are really cases in which there is an increase of white +blood corpuscles, and it is doubtful whether such a condition as pus in +the blood does ever occur. In the extremely rare cases, in which pus +breaks through into the veins, purulent ingredients may, without doubt, +be conveyed into the blood, but in such cases the introduction of pus +occurs for the most part but once, and there is no persistent pyæmia. +Even when clots in veins break down and form matter like pus, it will be +found that the matter is not really pus, and contains no pus cells.</p> + +<p><i>Chlorosis</i> is a condition in which there is a diminution of the +cellular elements of the blood, due probably to their deficient +formation in the spleen and lymphatic glands.</p> + + +<p class="subchap"><i>The Vital Processes and Their Relation to Disease. Inflammation</i></p> + +<p>The study of the histology of the nervous system shows that in all parts +of the body a splitting up into a number of small centres takes place, +and that nowhere does a single central point susceptible of anatomical +demonstration exist from which the operations of the body are directed. +We find in the nervous systems <span class='pagenum'><a name="Page_299" id="Page_299">[Pg 299]</a></span>definite little cells which serve as +centres of motion, but we do not find any single ganglion cell in which +alone all movement in the end originates. The most various individual +motor apparatuses are connected with the most various individual motor +ganglion cells. Sensations are certainly collected in definite ganglion +cells. Still, among them, too, we do not find any single ganglion cell +which can be in any way designated the centre of all sensation, but we +again meet with a great number of very minute centres. All the +operations which have their source in the nervous system, and there +certainly are a very great number of them, do not allow us to recognise +a unity anywhere else than in our own consciousness. An anatomical or +physiological unity has at least as yet been nowhere demonstrated.</p> + +<p>When we talk of life we mean vital activity. Now, every vital action +supposes an excitation or irritation. The irritability of the part is +the criterion by which we judge whether it be alive or not. Our notion +of the death of a part is based upon nothing more or less than +this—that we can no longer detect any irritability in it. If we now +proceed with our analysis of what is to be included in the notion of +excitability, we at once discover, that the different actions which can +be provoked by the influence of any external agency are essentially of +three kinds. The result of an excitation or irritation may, according to +circumstances, be either a merely functional process, or a more or less +increased nutrition of the part, <i>or</i> a formative process giving rise to +a greater or less number of new elements. These differences manifest +themselves more or less distinctly according as the particular tissues +are more or less capable of responding to the one or other kinds of +excitation. It certainly cannot be denied that the processes may not be +distinctly defined, and that between the nutritive and formative +processes, and also between the functional and nutritive ones there are +transitional stages; still, when they are<span class='pagenum'><a name="Page_300" id="Page_300">[Pg 300]</a></span> typically performed, there is +a very marked difference between them, and considerable differences in +the internal changes undergone by the excited parts.</p> + +<p>In inflammation all three irritative processes occur side by side. +Indeed, we may frequently see that when the organ itself is made up of +different parts, one part of the tissue undergoes functional or +nutritive, another formative, changes. If we consider what happens in a +muscle we see that a chemical or traumatic stimulus produces a +functional irritation of the primitive fasciculi, with contraction of +the muscle followed by nutritive changes. On the other hand, in the +interstitial connective tissue which binds the individual fasciculi of +the muscle together, real new formations are readily produced, commonly +pus. In this manner the three forms of irritation may be distinguished +in one part.</p> + +<p>The formative process is always preceded by nutritive enlargement due to +irritation of the part, and has no connection with irritation of the +nerves. Of course there may be also an irritation of the nerves, but +this, if we do not take function into account, has no causal connection +with the processes going on in the tissue proper, but is merely a +collateral effect of the original disturbance.</p> + +<p>Besides these active processes of function, nutrition, and new +formation, there occur passive processes. Passive processes are called +those changes in cells whereby they either lose a portion of their +substance, or are so completely destroyed, that a loss of substance, a +diminution of the sum total of the constituents of the body is produced. +To this class belong fatty degeneration of cells, affection of arteries, +calcification, and ossification of arteries, amyloid degeneration, and +so forth.</p> + +<p>It will now be necessary to consider inflammation at more length. The +theory of inflammation has passed through various stages. At first heat +was considered as its essential and dominant feature, then redness, +then<span class='pagenum'><a name="Page_301" id="Page_301">[Pg 301]</a></span> exudative swelling; while the speculative neuropathologists +consider pain the <i>fons et origo</i> of the condition.</p> + +<p>Personally, I believe that irritation must be taken as the +starting-point in the consideration of inflammation. We cannot conceive +of inflammation without an irritating stimulus, and the first question +is, what conception we are to form of such a stimulus.</p> + +<p>An inflammatory stimulus is a stimulus which acts either directly or +through the medium of the blood upon the composition and constitution of +a part in such a way as to enable it to attract to itself a larger +quantity of matter than usual and to transform it according to +circumstances. Every form of inflammation with which we are acquainted +may be explained in this way. It may be assumed that inflammation begins +from the moment that this increased absorption of matters into the +tissue takes place, and the further transformation of these matters +commences.</p> + +<p>It must be noticed that hyperæmia is not the essential feature of +inflammation, for inflammation occurs in non-vascular as well as in +vascular parts, and the inflammatory processes are practically the same +in both instances.</p> + +<p>Nor is inflammatory exudation the essential feature of inflammation. I +am of the opinion that there is no specific inflammatory exudation at +all, but that the exudation we meet with is composed essentially of the +material which has been generated in the inflamed part itself, through +the change in its condition, and of the transuded fluid derived from the +vessels. If, therefore, a part possess a great number of vessels, and +particularly if they are superficial, it will be able to furnish an +exudation, since the fluid which transudes from the blood conveys the +special product of the tissue along with it to the surface. If this is +not the case, there will be no exudation, but the whole process will be +limited to the occurrence in the real substance of the tissue of the +special<span class='pagenum'><a name="Page_302" id="Page_302">[Pg 302]</a></span> changes which have been induced by the inflammatory stimulus.</p> + +<p>In this manner, two forms of inflammation can be distinguished, the +<i>purely parenchymatous inflammation</i>, where the process runs its course +in the interior of the tissue, without our being able to detect the +presence of any free fluid which has escaped from the blood; and the +secretory (exudative) inflammation, where an increased escape of fluid +takes place from the blood, and conveys the peculiar parenchymatous +matters along with it to the surface of the organs. That there are two +kinds of inflammation is shown by the fact that they occur for the most +part in different organs. Every parenchymatous inflammation tends to +alter the histological and functional character of an organ. Every +inflammation with free exudation generally affords a certain relief to +the parts by conveying away from it a great part of the noxious matters +with which it is clogged.</p> + + +<p class="subchap"><i>New Formations</i></p> + +<p>I at present entirely reject the blastema doctrine in its original form, +and in its place I put the <i>doctrine of the continuous development of +tissues out of one another</i>. My first doubts of the blastema doctrine +date from my researches on tubercle. I found the tubercles never +exhibited a discernible exudation; but always organised elements +unpreceded by amorphous matter. I also found that the discharge from +scrofulous glands and from inflamed lymphatic glands is not an exudation +capable of organisation but merely débris, developed from the ordinary +cells of the glands.</p> + +<p>Until, however, the cellular nature of the body had been demonstrated, +it seemed necessary in some instances to postulate a blastema or +exudation to account for certain new formations. But the moment I could +show the universality of cells—the moment I could show that bone<span class='pagenum'><a name="Page_303" id="Page_303">[Pg 303]</a></span> +corpuscles were real cells, and that connective tissues contained +cells—from that moment cellular material for the building of new +formations was apparent. In fact, the more observers increased the more +distinctly was it shown that by far the greater number of new formations +arise from the connective tissue. In almost all cases new formations may +be seen to be formed by a process of ordinary cell division from +previously existing cells. In some cases the cells continue to resemble +the parent cells; in other cases they become different. All new +formations built of cells which continue true to the parent type we may +call homologous new formations; while those which depart from the parent +type or undergo degenerative changes we may designate heterologous. In a +narrower sense of the word heterologous new formations are alone +destructive. The homologous ones may accidentally become very injurious, +but still they do not possess what can properly be called a destructive +or malignant character. On the other hand, every kind of heterologous +formation whenever it has not its seat in entirely superficial parts, +has a certain degree of malignity, and even superficial affections, +though entirely confined to the most external layers of epidermis, may +gradually exercise a very detrimental effect. Indeed, suppuration is of +this nature, for suppuration is simply a process of proliferation by +means of which cells are produced which do not acquire that degree of +consolidation or permanent connection with each other which is necessary +for the existence of the body. Pus is not the solvent of cells: but is +itself dissolved tissues. A part becomes soft and liquefies, while +suppurating, but it is not the pus which causes this softening; on the +contrary, it is the pus which is produced as the result of the +proliferation of tissues.</p> + +<p>A suppurative change of this nature takes place in all heterologous new +formations. The form of ulceration which is presented by cancer in its +latest stages bears so great a resemblance to suppurative ulceration +that the<span class='pagenum'><a name="Page_304" id="Page_304">[Pg 304]</a></span> two things have long since been compared. The difference +between suppuration and suppuration lies in the differing duration of +the life of different cells. A cancer cell is capable of existing longer +than a pus corpuscle, and a cancerous tumour may last for months yet +still contain the whole of its elements intact. We are as yet able in +the case of very few elements to state with absolute certainty the +average length of their life. But among all pathological new formations +with fluid intercellular substance there is not a single one which is +able to preserve its existence for any length of time—not a single one +whose elements can become permanent constituents of the body, or exist +as long as the individual. The tumour as a whole may last; but its +individual elements perish. If we examine a tumour after it has existed +for perhaps a year, we usually find that the elements first formed no +longer exist in the centre; but that in the centre they are +disintegrating, dissolved by fatty changes. If a tumour be seated on a +surface, it often presents in the centre of its most prominent part a +navel-like depression, and the parts under this display a dense cicatrix +which no longer bears the original character of the new formation. +Heterologous new formations must be considered parasitical in their +nature, since every one of their elements will withdraw matters from the +body which might be used for better purposes, and since even its first +development implies the destruction of its parent structures.</p> + +<p>In view of origin of new formations it were well to create a +nomenclature showing their histological basis; but new names must not be +introduced too suddenly, and it must be noted that there are certain +tumours whose histological pedigree is still uncertain.</p> + + +<p class='center'> +<i>Printed in the United States of America</i><br /><br /><br /> +</p> + +<div class="footnotes"><h3>FOOTNOTES:</h3> + +<div class="footnote"><p><a name="Footnote_1_1" id="Footnote_1_1"></a><a href="#FNanchor_1_1"><span class="label">[1]</span></a> Azure transparent spheres conceived by the ancients to +surround the earth one within another, and to carry the heavenly bodies +in their revolutions.</p></div> + +<div class="footnote"><p><a name="Footnote_2_2" id="Footnote_2_2"></a><a href="#FNanchor_2_2"><span class="label">[2]</span></a> Book I., Prop. i. The areas which revolving bodies describe +by radii drawn to an immovable centre of force do lie in the same +immovable planes and are proportional to the times in which they are +described. +</p><p> +Prop. ii. Every body that moves in any curve line described in a plane +and by a radius drawn to a point either immovable or moving forward with +a uniform rectilinear motion describes about that point areas +proportional to the times is urged by a centripetal force directed to +that point. +</p><p> +Prop. iii. Every body that, by a radius drawn to another body, howsoever +moved, describes areas about that centre proportional to the times is +urged by a force compounded out of the centripetal force tending to that +other body and of all the accelerative force by which that other body is +impelled.</p></div> + +<div class="footnote"><p><a name="Footnote_3_3" id="Footnote_3_3"></a><a href="#FNanchor_3_3"><span class="label">[3]</span></a> If the periodic times are in the sesquiplicate ratio of the +radii, and therefore the velocities reciprocally in the subduplicate +ratio of the radii, the centripetal forces will be in the duplicate +ratio of the radii inversely; and the converse.</p></div> + +<div class="footnote"><p><a name="Footnote_4_4" id="Footnote_4_4"></a><a href="#FNanchor_4_4"><span class="label">[4]</span></a> <i>i.e.</i>, showing convexity when in such a position as that, +to an observer on the earth, a line drawn between it and the sun would +subtend an angle of <i>90</i>° or thereabouts.</p></div> +</div> + +<div class="tnote"> +<h3>Transcriber Notes:</h3> +<p class="center">Variant spelling and punctuation have been preserved.<br /><br /> +Image quality of the Frontispiece is poor.</p> +</div> + + + + + + + +<pre> + + + + + +End of the Project Gutenberg EBook of The World's Greatest Books - Volume 15 +- Science, by Various + +*** END OF THIS PROJECT GUTENBERG EBOOK WORLD'S GREATEST BOOKS-VOLUME 15 *** + +***** This file should be named 25509-h.htm or 25509-h.zip ***** +This and all associated files of various formats will be found in: + https://www.gutenberg.org/2/5/5/0/25509/ + +Produced by Kevin Handy, John Hagerson, Greg Bergquist and +the Online Distributed Proofreading Team at +https://www.pgdp.net + + +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. 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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 World's Greatest Books - Volume 15 - Science + +Author: Various + +Editor: John Alexander Hammerton + +Release Date: May 17, 2008 [EBook #25509] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK WORLD'S GREATEST BOOKS-VOLUME 15 *** + + + + +Produced by Kevin Handy, John Hagerson, Greg Bergquist and +the Online Distributed Proofreading Team at +https://www.pgdp.net + + + + + + +[Illustration: William Harvey] + + + + +THE WORLD'S +GREATEST +BOOKS + +JOINT EDITORS + +ARTHUR MEE +Editor and Founder of the Book of Knowledge + +J.A. HAMMERTON +Editor of Harmsworth's Universal Encyclopaedia + +VOL. XV + +SCIENCE + +WM. H. WISE & Co. + + + + +_Table of Contents_ + + +PORTRAIT OF WILLIAM HARVEY _Frontispiece_ + + PAGE + +BRAMWELL, JOHN MILNE + Hypnotism: Its History, Practice and Theory 1 + + +BUFFON, COMTE DE + Natural History 12 + + +CHAMBERS, ROBERT + Vestiges of Creation 22 + + +CUVIER, GEORGES + The Surface of the Globe 33 + + +DARWIN, CHARLES + The Origin of Species 43 + + +DAVY, SIR HUMPHRY + Elements of Chemical Philosophy 64 + + +FARADAY, MICHAEL + Experimental Researches in Electricity 75 + The Chemical History of a Candle 85 + + +FOREL, AUGUSTE + The Senses of Insects 95 + + +GALILEO + Dialogues on the System of the World 105 + + +GALTON, SIR FRANCIS + Essays in Eugenics 111 + + +HAECKEL, ERNST + The Evolution of Man 123 + + +HARVEY, WILLIAM + On the Motion of the Heart and Blood 136 + + +HERSCHEL, SIR JOHN + Outlines of Astronomy 146 + + +HUMBOLDT, ALEXANDER VON + Cosmos, a Sketch of the Universe 158 + + +HUTTON, JAMES + The Theory of the Earth 170 + + +LAMARCK + Zoological Philosophy 179 + + +LAVATER, JOHANN + Physiogonomical Fragments 191 + + +LIEBIG, JUSTUS VON + Animal Chemistry 203 + + +LYELL, SIR CHARLES + The Principles of Geology 215 + + +MAXWELL, JAMES CLERK + A Treatise on Electricity and Magnetism 227 + + +METCHNIKOFF, ELIE + The Nature of Man 238 + The Prolongation of Life 246 + + +MILLER, HUGH + The Old Red Sandstone 255 + + +NEWTON, SIR ISAAC + Principia 267 + + +OWEN, SIR RICHARD + Anatomy of Vertebrates 280 + + +VIRCHOW, RUDOLF + Cellular Pathology 292 + + * * * * * + +A Complete Index of THE WORLD'S GREATEST BOOKS will be found at the end +of Volume XX. + + + + +_Acknowledgment_ + + +Acknowledgment and thanks for the use of the following selections are +herewith tendered to the Open Court Publishing Company, La Salle, Ill., +for "Senses of Insects," by Auguste Forel; to G.P. Putnam's Sons, New +York, for "Prolongation of Human Life" and "Nature of Man," by Elie +Metchnikoff; and to the De La More Press, London, for "Hypnotism, &c.," +by Dr. Bramwell. + + + + +_Science_ + +JOHN MILNE BRAMWELL + +Hypnotism: Its History, Practice and Theory + + John Milne Bramwell was born in Perth, Scotland, May 11, 1852. The + son of a physician, he studied medicine in Edinburgh, and after + obtaining his degree of M.B., in 1873, he settled at Goole, + Yorkshire. Fired by the unfinished work of Braid, Bernheim and + Liebeault, he began, in 1889, a series of hypnotic researches, + which, together with a number of successful experiments he had + privately conducted, created considerable stir in the medical + world. Abandoning his general practice and settling in London in + 1892, Dr. Bramwell became one of the foremost authorities in the + country on hypnotism as a curative agent. His Works include many + valuable treatises, the most important being "Hypnotism: its + History, Practice and Theory," published in 1903, and here + summarised for the WORLD'S GREATEST BOOKS by Dr. Bramwell himself. + + +_I.--Pioneers of Hypnotism_ + +Just as chemistry arose from alchemy, astronomy from astrology, so +hypnotism had its origin in mesmerism. Phenomena such as Mesmer +described had undoubtedly been observed from early times, but to his +work, which extended from 1756 to his death, in 1815, we owe the +scientific interest which, after much error and self-deception, finally +led to what we now term hypnotism. + +John Elliotson (1791-1868), the foremost physician of his day, was the +leader of the mesmeric movement in England. In 1837, after seeing +Dupotet's work, he commenced to experiment at University College +Hospital, and continued, with remarkable success, until ordered to +desist by the council of the college. Elliotson felt the insult keenly, +indignantly resigned his appointments, and never afterwards entered the +hospital he had done so much to establish. Despite the persistent and +virulent attacks of the medical press, he continued his mesmeric +researches up to the time of his death, sacrificing friends, income and +reputation to his beliefs. + +The fame of mesmerism spread to India, where, in 1845, James Esdaile +(1808-1859), a surgeon in the East India Company, determined to +investigate the subject. He was in charge of the Native Hospital at +Hooghly, and successfully mesmerised a convict before a painful +operation. Encouraged by this, he persevered, and, at the end of a year, +reported 120 painless operations to the government. Investigations were +instituted, and Esdaile was placed in charge of a hospital at Calcutta, +for the express purpose of mesmeric practice; he continued to occupy +similar posts until he left India in 1851. He recorded 261 painless +capital operations and many thousand minor ones, and reduced the +mortality for the removal of the enormous tumours of elephantiasis from +50 to 5 per cent. + +According to Elliotson and Esdaile, the phenomena of mesmerism were +entirely physical in origin. They were supposed to be due to the action +of a vital curative fluid, or peculiar physical force, which, under +certain circumstances, could be transmitted from one human being to +another. This was usually termed the "od," or "odylic," force; various +inanimate objects, such as metals, crystals and magnets, were supposed +to possess it, and to be capable of inducing and terminating the +mesmeric state, or of exciting or arresting its phenomena. + +The name of James Braid (1795-1860) is familiar to all students of +hypnotism. Braid was a Scottish surgeon, practising in Manchester, where +he had already gained a high reputation as a skilful surgeon, when, in +1841, he first began to investigate mesmerism. He successfully +demonstrated that the phenomena were entirely subjective. He published +"Neurypnology, or the Rationale of Nervous Sleep," in 1843, and invented +the terminology we now use. This was followed by other more or less +important works, of which I have been able to trace forty-one, but all +have been long out of print. + +During the eighteen years Braid devoted to the study of hypnotism, his +views underwent many changes and modifications. In his first theory, he +explained hypnosis from a physical standpoint; in the second, he +considered it to be a condition of involuntary monoideism and +concentration, while his third theory differed from both. He recognised +that reason and volition were unimpaired, and that the attention could +be simultaneously directed to more points than one. The condition, +therefore, was not one of monoideism. He realised more and more that the +state was a conscious one, and that the losses of memory which followed +on waking could always be restored in subsequent hypnoses. Finally, he +described as "double consciousness" the condition he had first termed +"hypnotic," then "monoideistic." + +Braid maintained an active interest in hypnotism up to his death, and, +indeed, three days before it, sent his last MS. to Dr. Azam, of +Bordeaux, "as a mark of esteem and regard." Sympathetic notices appeared +in the press after his death, all of which bore warm testimony to his +professional character. Although hypnotic work practically ceased in +England at Braid's death, the torch he had lighted passed into France. + +In 1860, Dr. A.A. Liebeault (1823-1900) began to study hypnotism +seriously, and four years later gave up general practice, settled in +Nancy, and practised hypnotism gratuitously among the poor. For twenty +years his labours were unrecognised, then Bernheim (one of whose +patients Liebeault had cured) came to see him, and soon became a zealous +pupil. The fame of the Nancy school spread, Liebeault's name became +known throughout the world, and doctors flocked to study the new +therapeutic method. + +While Liebeault's work may justly be regarded as a continuation of +Braid's, there exists little difference between the theories of Charcot +and the Salpetriere school and those of the later mesmerists. + + +_II.--Theory of Hypnotism_ + +The following is a summary of Braid's latest theories: (1) Hypnosis +could not be induced by physical means alone. (2) Hypnotic and so-called +mesmeric phenomena were subjective in origin, and both were excited by +direct or by indirect suggestion. (3) Hypnosis was characterised by +physical as well as by psychical changes. (4) The simultaneous +appearance of several phenomena was recognised, and much importance was +attached to the intelligent action of a secondary consciousness. (5) +Volition was unimpaired, moral sense increased, and suggested crime +impossible. (6) _Rapport_ was a purely artificial condition created by +suggestion. (7) The importance of direct verbal suggestion was fully +recognised, as also the mental influence of physical methods. Suggestion +was regarded as the device used for exciting the phenomena, and not +considered as sufficient to explain them. (8) Important differences +existed between hypnosis and normal sleep. (9) Hypnotic phenomena might +be induced without the subject having passed through any condition +resembling sleep. (10) The mentally healthy were the easiest, the +hysterical the most difficult, to influence. + +In England, during Braid's lifetime, his earlier views were largely +adopted by certain well-known men of science, particularly by Professors +W.B. Carpenter and J. Hughes Bennett, but they appear to have known +little or nothing of his latest theories. Bennett's description of the +probable mental and physical conditions involved in the state Braid +described as "monoideism" is specially worthy of note. Not only is it +interesting in itself, but it serves also as a standard of comparison +with which to measure the theories of later observers, who have +attempted to explain hypnosis by cerebral inhibition, psychical +automatism, or both these conditions combined. + +(a) _Physiological._--According to Bennett, hypnosis was characterised +by alterations in the functional activity of the nerve tubes of the +white matter of the cerebral lobes. He suggested that a certain +proportion of these became paralysed through continued monotonous +stimulation; while the action of others was consequently exalted. As +these tubes connected the cerebral ganglion-cells, suspension of their +functions was assumed to bring with it interruption of the connection +between the ganglion-cells. + +(b) _Psychical._--From the psychical side, he explained the phenomena of +hypnosis by the action of predominant and unchecked ideas. These were +able to obtain prominence from the fact that other ideas, which, under +ordinary circumstances, would have controlled their development, did not +arise, because the portion of the brain with which the latter were +associated had its action temporarily suspended--_i.e._, the connection +between the ganglion-cells was broken, owing to the interrupted +connection between the "fibres of association." Thus, he said, the +remembrance of a sensation could always be called up by the brain; but, +under ordinary circumstances, from the exercise of judgment, comparison, +and other mental faculties, we knew it was only a remembrance. When +these faculties were exhausted, the suggested idea predominated, and the +individual believed in its reality. Thus, he attributed to the faculties +of the mind a certain power of correcting the fallacies which each of +them was likely to fall into; just as the illusions of one sense were +capable of being detected by the healthy use of the other senses. There +were mental and sensorial illusions, the former caused by predominant +ideas and corrected by proper reasoning, the latter caused by perversion +of one sense and corrected by the right application of the others. + +In hypnosis, according to this theory, a suggested idea obtained +prominence and caused mental and sensorial illusions, because the check +action--the inhibitory power--of certain higher centres had been +temporarily suspended. These theories were first published by Professor +Bennett in 1851. + + +_III.--Hypnotic Induction_ + +The methods by which hypnosis is induced have been classed as follows: +(1) physical; (2) psychical; (3) those of the magnetisers. The modern +operator, whatever his theories may be, borrows his technique from +Mesmer and Liebeault with equal impartiality, and thus renders +classification impossible. The members of the Nancy school, while +asserting that everything is due to suggestion, do not hesitate to use +physical means, and, if these fail, Bernheim has recourse to narcotics. + +The following is now my usual method: I rarely begin treatment the first +time I see a patient, but confine myself to making his acquaintance, +hearing his account of his case, and ascertaining his mental attitude +with regard to suggestion. I usually find, from the failure of other +methods of treatment, that he is more or less sceptical as to the chance +of being benefited. I endeavour to remove all erroneous ideas, and +refuse to begin treatment until the patient is satisfied of the safety +and desirability of the experiment. I never say I am certain of being +able to influence him, but explain how much depends on his mental +attitude and power of carrying out my directions. I further explain to +the patient that next time he comes to see me I shall ask him to close +his eyes, to concentrate his attention on some drowsy mental picture, +and try to turn it away from me. I then make suggestions of two kinds: +the first refer to the condition I wish to induce while he is actually +in the armchair, thus, "Each time you see me, you will find it easier to +concentrate your attention on something restful. I do not wish you to go +to sleep, but if you can get into the drowsy condition preceding natural +sleep, my suggestions are more likely to be responded to." I explain +that I do not expect this to happen at once, although it does occur in +rare instances, but it is the repetition of the suggestions made in this +particular way which brings about the result. Thus, from the very first +treatment, the patient is subjected to two distinct processes, the +object of one being to induce the drowsy, suggestible condition, that of +the other to cure or relieve disease. + +I wish particularly to mention that although I speak of hypnotism and +hypnosis--and it is almost impossible to avoid doing so--I rarely +attempt to induce so-called hypnosis, and find that patients respond to +treatment as readily, and much more quickly, now that I start curative +suggestions and treatment simultaneously, than they did in the days when +I waited until hypnosis was induced before making curative suggestions. + +I have obtained good results in treating all forms of hysteria, +including _grande hysterie_, neurasthenia, certain forms of insanity, +dipsomania and chronic alcoholism, morphinomania and other drug habits, +vicious and degenerate children, obsessions, stammering, chorea, +seasickness, and all other forms of functional nervous disturbances. + +It is impossible to discuss the different theories in detail here, but I +will briefly summarise the more important points, (1) Hypnotism, as a +science, rests on the recognition of the subjective nature of its +phenomena. (2) The theories of Charcot and the Salpetriere school are +practically a reproduction of mesmeric error. (3) Liebeault and his +followers combated the views of the Salpetriere school and successfully +substituted their own, of which the following are the important points: +(_a_) Hypnosis is a physiological condition, which can be induced in the +healthy. (_b_) In everyone there is a tendency to respond to suggestion, +but in hypnosis this condition is artificially increased. (_c_) +Suggestion explains all. Despite the fact that the members of the Nancy +school regard the condition as purely physiological and simply an +exaggeration of the normal, they consider it, in its profound stages at +all events, a form of automatism. + +These and other views of the Nancy school have been questioned by +several observers. As Myers justly pointed out, although suggestion is +the artifice used to excite the phenomena, it does not create the +condition on which they depend. The peculiar state which enables the +phenomena to be evoked is the essential thing, not the signal which +precedes their appearance. + +Within recent times another theory has arisen, which, instead of +explaining hypnotism by the arrested action of some of the brain centres +which subserve normal life, attempts to do so by the arousing of certain +powers over which we normally have little or no control. This theory +appears under different names, "Double Consciousness," "Das Doppel-Ich," +etc., and the principle on which it depends is largely admitted by +science. William James, for example, says: "In certain persons, at +least, the total possible consciousness may be split into parts which +co-exist, but mutually ignore each other." + +The clearest statement of this view was given by the late Frederic +Myers; he suggested that the stream of consciousness in which we +habitually lived was not our only one. Possibly our habitual +consciousness might be a mere selection from a multitude of thoughts +and sensations--some, at least, equally conscious with those we +empirically knew. No primacy was granted by this theory to the ordinary +waking self, except that among potential selves it appeared the fittest +to meet the needs of common life. As a rule, the waking life was +remembered in hypnosis, and the hypnotic life forgotten in the waking +state; this destroyed any claim of the primary memory to be the sole +memory. The self below the threshold of ordinary consciousness Myers +termed the "subliminal consciousness," and the empirical self of common +experience the "supraliminal." He held that to the subliminal +consciousness and memory a far wider range, both of physiological and +psychical activity, was open than to the supraliminal. The latter was +inevitably limited by the need of concentration upon recollections +useful in the struggle for existence; while the former included much +that was too rudimentary to be retained in the supraliminal memory of an +organism so advanced as that of man. The recollection of processes now +performed automatically and needing no supervision, passed out of the +supraliminal memory, but might be retained by the subliminal. The +subliminal, or hypnotic, self could exercise over the vaso-motor and +circulatory systems a degree of control unparalleled in waking life. + +Thus, according to the Nancy school, the deeply hypnotised subject +responds automatically to suggestion before his intellectual centres +have had time to bring their inhibitory action into play; but, on the +other hand, in the subliminal consciousness theory, volition and +consciousness are recognised to be unimpaired in hypnosis. + + +_IV.--Curative Value of Hypnotism_ + +The intelligent action of the secondary self may be illustrated by the +execution of certain post-hypnotic acts. Thus, one of my patients who, +at a later period, consented to become the subject of experiment, +developed an enormously increased power of time appreciation. If told, +during hypnosis, for example, that she was to perform some specific act +in the waking state at the expiration of a complicated number of +minutes, as, for example, 40,825, she generally carried out the +suggestion with absolute accuracy. In this and similar experiments, +three points were noted. (1) The arithmetical problems were far beyond +her normal powers; (2) she normally possessed no special faculty for +appreciating time; (3) her waking consciousness retained no recollection +of the experimental suggestions or of anything else that had occurred +during hypnosis. + +It is difficult to estimate the exact value of suggestion in connection +with other forms of treatment. There are one or two broad facts which +ought to be kept in mind. + +1. Suggestion is a branch of medicine, which is sometimes combined by +those who practise it with other forms of treatment. Thus it is often +difficult to say what proportion of the curative results is due to +hypnotism and what to other remedies. + +2. On the other hand, many cases of functional nervous disorder have +recovered under suggestive treatment after the continued failure of +other methods. Further, the diseases which are frequently cured are +often those in which drugs are of little or no avail. For example, what +medicine would one prescribe for a man in good physical health who had +suddenly become the prey of an obsession? Such patients are rarely +insane; they recognise that the idea which torments them is morbid; but +yet they are powerless to get rid of it. + +3. In estimating the results of suggestive treatment, it must not be +forgotten that the majority of cases are extremely unfavourable ones. As +the value of suggestion and its freedom from danger become more fully +recognised, it will doubtless be employed in earlier stages of disease. + +4. It should be clearly understood that the object of all suggestive +treatment ought to be the development of the patient's will power and +control of his own organism. Much disease would be prevented if we could +develop and control moral states. + + + + +BUFFON + +Natural History + + Georges Louis Leclerc, created in 1773 Comte de Buffon, was born at + Montbard, in France, on September 7, 1707. Evincing a marked bent + for science he became, in 1739, director of the Jardin du Roi and + the King's Museum in Paris. He had long contemplated the + preparation of a complete History of Nature, and now proceeded to + carry out the work. The first three volumes of the "Histoire + Naturelle, Generale et Particuliere" appeared in 1749, and other + volumes followed at frequent intervals until his death at Paris on + April 16, 1788. Buffon's immense enterprise was greeted with + abounding praise by most of his contemporaries. On July 1, 1752, he + was elected to the French Academy in succession to Languet de + Gergy, Archbishop of Sens, and, at his reception on August 25 in + the following year, pronounced the oration in which occurred the + memorable aphorism, "Le style est l'homme meme" (The style is the + very man). Buffon also anticipated Thomas Carlyle's definition of + genius ("which means the transcendent capacity of taking trouble, + first of all") by his famous axiom, "Le genie n'est autre chose + qu'une grande aptitude a la patience." + + +_Scope of the Work_ + +Buffon planned his "Natural History" on an encyclopaedic scale. His +point of view was unique. Natural history in its widest sense, he tells +us, embraces every object in the visible universe. The obvious divisions +of the subject, therefore, are, first, the earth, the air, and the +water; then the animals--quadrupeds, birds, fishes, and so +on--inhabiting each of these "elements," to use the phrase of his day. +Now, Buffon argued, if man were required to give some account of the +animals by which he was surrounded, of course he would begin with those +with which he was most familiar, as the horse, the dog, the cow. From +these he would proceed to the creatures with which he was less familiar, +and finally deal--through the medium of travellers' tales and other +sources of information--with the denizens of field, forest and flood in +foreign lands. In similar fashion he would consider the plants, +minerals, and other products of Nature, in addition to recounting the +marvels revealed to him by astronomy. + +Whatever its defects on the scientific side, Buffon's plan was +simplicity itself, and was adopted largely, if not entirely, in +consequence of his contempt--real or affected--for the systematic method +of the illustrious Linnaeus. Having charted his course, the rest was +plain sailing. He starts with the physical globe, discussing the +formation of the planets, the features of the earth--mountains, rivers, +seas, lakes, tides, currents, winds, volcanoes, earthquakes, islands, +and so forth--and the effects of the encroachment and retreat of the +ocean. + +Animate nature next concerns him. After comparing animals, plants and +minerals, he proceeds to study man literally from the cradle to the +grave, garnishing the narrative with those incursions into the domains +of psychology, physiology and hygiene, which, his detractors insinuated, +rendered his work specially attractive and popular. + + +_I.--The Four-Footed Animals_ + +Such questions occupied the first three volumes, and the ground was now +cleared for the celebrated treatise on Quadrupeds, which filled no fewer +than twelve volumes, published at various dates from 1753 (vol. iv.) to +1767 (vol. xv., containing the New World monkeys, indexes, and the +like). Buffon's _modus operandi_ saved him from capital blunders. Though +inordinately vain--"I know but five great geniuses," he once said; +"Newton, Bacon, Leibniz, Montesquieu, and myself"--he was quite +conscious of his own limitations, and had the common-sense to entrust to +Daubenton the description of the anatomy and other technical matters as +to which his own knowledge was comparatively defective. He reserved to +himself what may be called the "literary" aspect of his theme, recording +the place of each animal in history, and relating its habits with such +gusto as his ornate and grandiose style permitted. + +After a preliminary dissertation on the nature of animals, Buffon +plunges into an account of those that have been domesticated or tamed. +Preference of place is given to the horse, and his method of treatment +is curiously anticipatory of modern lines. Beginning with some notice of +the horse in history, he goes on to describe its appearance and habits +and the varieties of the genus, ending (by the hand of Daubenton) with +an account of its structure and physiology. As evidence of the pains he +took to collect authority for his statements, it is of interest to +mention that he illustrates the running powers of the English horse by +citing the instance of Thornhill, the postmaster of Stilton, who, in +1745, wagered he would ride the distance from Stilton to London thrice +in fifteen consecutive hours. Setting out from Stilton, and using eight +different horses, he accomplished his task in 3 hours 51 minutes. In the +return journey he used six horses, and took 3 hours 52 minutes. For the +third race he confined his choice of horses to those he had already +ridden, and, selecting seven, achieved the distance in 3 hours 49 +minutes. He performed the undertaking in 11 hours and 32 minutes. "I +doubt," comments Buffon, "whether in the Olympic Games there was ever +witnessed such rapid racing as that displayed by Mr. Thornhill." + +Justice having been done to it, the horse gives place to the ass, ox, +sheep, goat, pig, dog, and cat, with which he closes the account of the +domesticated animals, to which three volumes are allotted. It is +noteworthy that Buffon frequently, if not always, gives the synonyms of +the animals' names in other languages, and usually supports his textual +statements by footnote references to his authorities. + +When he comes to the Carnivores--"les animaux nuisibles"--the defects of +Buffon's higgledy-piggledy plan are almost ludicrously evident, for +flesh-eaters, fruit-eaters, insect-eaters, and gnawers rub shoulders +with colossal indifference. Doubtless, however, this is to us all the +more conspicuous, because use and wont have made readers of the present +day acquainted with the advantages of classification, which it is but +fair to recognise has been elaborated and perfected since Buffon's time. + +As his gigantic task progressed, Buffon's difficulties increased. At the +beginning of vol. xii. (1764) he intimates that, with a view to break +the monotony of a narrative in which uniformity is an unavoidable +feature, he will in future, from time to time, interrupt the general +description by discourses on Nature and its effects on a grand scale. +This will, he naively adds, enable him to resume "with renewed courage" +his account of details the investigation of which demands "the calmest +patience, and affords no scope for genius." + + +_II.--The Birds_ + +Scarcely had he finished the twelve volumes of Quadrupeds when Buffon +turned to the Birds. If this section were less exacting, yet it made +enormous claims upon his attention, and nine volumes were occupied +before the history of the class was concluded. Publication of "Des +Oiseaux" was begun in 1770, and continued intermittently until 1783. But +troubles dogged the great naturalist. The relations between him and +Daubenton had grown acute, and the latter, unwilling any longer to put +up with Buffon's love of vainglory, withdrew from the enterprise to +which his co-operation had imparted so much value. Serious illness, +also, and the death of Buffon's wife, caused a long suspension of his +labours, which were, however, lightened by the assistance of Gueneau de +Montbeliard. + +One stroke of luck he had, which no one will begrudge the weary Titan. +James Bruce, of Kinnaird, on his return from Abyssinia in 1773, spent +some time with Buffon at his chateau in Montbard, and placed at his +disposal several of the remarkable discoveries he had made during his +travels. Buffon was not slow to appreciate this godsend. Not only did +he, quite properly, make the most of Bruce's disinterested help, but he +also expressed the confident hope that the British Government would +command the publication of Bruce's "precious" work. He went on to pay a +compliment to the English, and so commit them to this enterprise. "That +respectable nation," he asserts, "which excels all others in discovery, +can but add to its glory in promptly communicating to the world the +results of the excellent travellers' researches." + +Still unfettered by any scheme of classification, either scientific or +logical, Buffon begins his account of the birds with the eagles and +owls. To indicate his course throughout the vast class, it will suffice +to name a few of the principal birds in the order in which he takes them +after the birds of prey. These, then, are the ostrich, bustard, game +birds, pigeons, crows, singing birds, humming birds, parrots, cuckoos, +swallows, woodpeckers, toucans, kingfishers, storks, cranes, secretary +bird, herons, ibis, curlews, plovers, rails, diving birds, pelicans, +cormorants, geese, gulls, and penguins. With the volume dealing with the +picarian birds (woodpeckers) Buffon announces the withdrawal of Gueneau +de Montbeliard, and his obligations for advice and help to the Abbe +Bexon (1748-1784), Canon of Sainte Chapelle in Paris. + + +_III.--Supplement and Sequel_ + +At the same time that the Birds volumes were passing through the press, +Buffon also issued periodically seven volumes of a supplement +(1774-1789), the last appearing posthumously under the editorship of +Count Lacepede. This consisted of an olla podrida of all sorts of +papers, such as would have won the heart of Charles Godfrey Leland. The +nature of the hotchpotch will be understood from a recital of some of +its contents, in their chronological order. It opened with an +introduction to the history of minerals, partly theoretical (concerning +light, heat, fire, air, water, earth, and the law of attraction), and +partly experimental (body heat, heat in minerals, the nature of +platinum, the ductility of iron). Then were discussed incandescence, +fusion, ships' guns, the strength and resistance of wood, the +preservation of forests and reafforestation, the cooling of the earth, +the temperature of planets, additional observations on quadrupeds +already described, accounts of animals not noticed before, such as the +tapir, quagga, gnu, nylghau, many antelopes, the vicuna, Cape ant-eater, +star-nosed mole, sea-lion, and others; the probabilities of life (a +subject on which the author plumed himself), and his essay on the Epochs +of Nature. + +Nor did these concurrent series of books exhaust his boundless energy +and ingenuity, for in the five years preceding his death (1783-1788), he +produced his "Natural History of Minerals" in five volumes, the last of +which was mainly occupied with electricity, magnetism, and the +loadstone. It is true that the researches of modern chemists have +wrought havoc with Buffon's work in this field; but this was his +misfortune rather than his fault, and leaves untouched the quantity of +his output. + +Buffon invoked the aid of the artist almost from the first, and his +"Natural History" is illustrated by hundreds of full-page copper-plate +engravings, and embellished with numerous elegant headpiece designs. The +figures of the animals are mostly admirable examples of portraiture, +though the classical backgrounds lend a touch of the grotesque to many +of the compositions. Illustrations of anatomy, physiology, and other +features of a technical character are to be numbered by the score, and +are, of course, indispensable in such a work. The _editio princeps_ is +cherished by collectors because of the 1,008 coloured plates ("Planches +Enluminees") in folio, the text itself being in quarto, by the younger +Daubenton, whose work was spiritedly engraved by Martinet. Apparently +anxious to illustrate one section exhaustively rather than several +sections in a fragmentary manner, the artist devoted himself chiefly to +the birds, which monopolise probably nine-tenths of the plates, and to +which he may also have been attracted by their gorgeous plumages. + +As soon as the labourer's task was over, his scientific friends thought +the best monument which they could raise to his memory was to complete +his "Natural History." This duty was discharged by two men, who, both +well qualified, worked, however, on independent lines. Count Lacepede, +adhering to the format of the original, added two volumes on the +Reptiles (1788-1789), five on the Fishes (1798-1803), and one on the +Cetaceans (1804). Sonnini de Manoncourt (1751-1812), feeling that this +edition, though extremely handsome, was cumbersome, undertook an +entirely new edition in octavo. This was begun in 1797, and finished in +1808. It occupied 127 volumes, and, Lacepede's treatises not being +available, Sonnini himself dealt with the Fishes (thirteen volumes) and +Whales (one volume), P.A. Latreille with the Crustaceans and Insects +(fourteen volumes), Denys-Montfort with the Molluscs (six volumes), F.M. +Dandin with the Reptiles (eight volumes), and C.F. Brisseau-Mirbel and +N. Jolyclerc with the Plants (eighteen volumes). Sonnini's edition +constituted the cope-stone of Buffon's work, and remained the best +edition, until the whole structure was thrown down by the views of later +naturalists, who revolutionised zoology. + + +_IV.--Place and Doctrine_ + +Buffon may justly be acclaimed as the first populariser of natural +history. He was, however, unscientific in his opposition to systems, +which, in point of fact, essentially elucidated the important doctrine +that a continuous succession of forms runs throughout the animal +kingdom. His recognition of this principle was, indeed, one of his +greatest services to the science. + +Another of his wise generalisations was that Nature proceeds by unknown +gradations, and consequently cannot adapt herself to formal analysis, +since she passes from one species to another, and often from one genus +to another, by shades of difference so delicate as to be wholly +imperceptible. + +In Buffon's eyes Nature is an infinitely diversified whole which it is +impossible to break up and classify. "The animal combines all the powers +of Nature; the forces animating it are peculiarly its own; it wishes, +does, resolves, works, and communicates by its senses with the most +distant objects. One's self is a centre where everything agrees, a point +where all the universe is reflected, a world in miniature." In natural +history, accordingly, each animal or plant ought to have its own +biography and description. + +Life, Buffon also held, abides in organic molecules. "Living beings are +made up of these molecules, which exist in countless numbers, which may +be separated but cannot be destroyed, which pierce into brute matter, +and, working there, develop, it may be animals, it may be plants, +according to the nature of the matter in which they are lodged. These +indestructible molecules circulate throughout the universe, pass from +one being to another, minister to the continuance of life, provide for +nutrition and the growth of the individual, and determine the +reproduction of the species." + +Buffon further taught that the quantity and quality of life pass from +lower to higher stages--in Tennysonian phrase, men "rise on +stepping-stones of their dead selves to higher things"--and showed the +unity and structure of all beings, of whom man is the most perfect type. + +It has been claimed that Buffon in a measure anticipated Lamarck and +Darwin. He had already foreseen the mutability of species, but had not +succeeded in proving it for varieties and races. If he asserted that the +species of dog, jackal, wolf and fox were derived from a single one of +these species, that the horse came from the zebra, and so on, this was +far from being tantamount to a demonstration of the doctrine. In fact, +he put forward the mutability of species rather as probable theory than +as established truth, deeming it the corollary of his views on the +succession and connection of beings in a continuous series. + +Some case may be made out for regarding Buffon as the founder of +zoogeography; at all events he was the earliest to determine the natural +habitat of each species. He believed that species changed with climate, +but that no kind was found throughout all the globe. Man alone has the +privilege of being everywhere and always the same, because the human +race is one. The white man (European or Caucasian), the black man +(Ethiopian), the yellow man (Mongol), and the red man (American) are +only varieties of the human species. As the Scots express it with wonted +pith, "We're a' Jock Tamson's bairns." + +As to his geological works, Buffon expounded two theories of the +formation of the globe. In his "Theorie de la Terre" he supported the +Neptunists, who attributed the phenomena of the earth to the action of +water. In his "Epoques de la Nature" he amplified the doctrines of +Leibniz, and laid down the following propositions: (1) The earth is +elevated at the equator and depressed at the poles in accordance with +the laws of gravitation and centrifugal force; (2) it possesses an +internal heat, apart from that received from the sun; (3) its own heat +is insufficient to maintain life; (4) the substances of which the earth +is composed are of the nature of glass, or can be converted into glass +as the result of heat and fusion--that is, are verifiable; (5) +everywhere on the surface, including mountains, exist enormous +quantities of shells and other maritime remains. + +To the theses just enumerated Buffon added what he called the +"monuments," or what Hugh Miller, a century later, more aptly described +as the Testimony of the Rocks. From a consideration of all these things, +Buffon at length arrived at his succession of the Epochs, or Seven Ages +of Nature, namely: (1) the Age of fluidity, or incandescence, when the +earth and planets assumed their shape; (2) the Age of cooling, or +consolidation, when the rocky interior of the earth and the great +vitrescible masses at its surface were formed; (3) the Age when the +waters covered the face of the earth; (4) the Age when the waters +retreated and volcanoes became active; (5) the Age when the elephant, +hippopotamus, rhinoceros, and other giants roamed through the northern +hemisphere; (6) the Age of the division of the land into the vast areas +now styled the Old and the New Worlds; and (7) the Age when Man +appeared. + + + + +ROBERT CHAMBERS + +Vestiges of Creation + + Robert Chambers was born in Peebles, Scotland, July 10, 1802, and + died at St. Andrews on March 17, 1871. He was partner with his + brother in the publishing firm of W. & R. Chambers, was editor of + "Chambers's Journal," and was author of several works when he + published anonymously, in October 1844, the work by which his name + will always be remembered, "Vestiges of the Natural History of + Creation." His previous works, some thirty in number, did not deal + with science, and his labour in preparing his masterpiece was + commensurate with the courage which such an undertaking involved. + When the book was published, such interest and curiosity as to its + authorship were aroused that we have to go back to the publication + of "Waverley" for a parallel. Little else was talked about in + scientific circles. The work was violently attacked by many hostile + critics, F.W. Newman, author of an early review, being a + conspicuous exception. In the historical introduction to the + "Origin of Species," Darwin speaks of the "brilliant and powerful + style" of the "Vestiges," and says that "it did excellent service + in this country in calling attention to the subject, in removing + prejudice, and in thus preparing the ground for the reception of + analogous views." Darwin's idea of selection as the key to the + history of species does not occur in the "Vestiges," which belongs + to the Lamarckian school of unexamined belief in the hereditary + transmission of the effects of use and disuse. + + +_I.--The Reign of Universal Law_ + +The stars are suns, and we can trace amongst them the working of the +laws which govern our sun and his family. In these universal laws we +must perceive intelligence; something of which the laws are but as the +expressions of the will and power. The laws of Nature cannot be regarded +as primary or independent causes of the phenomena of the physical world. +We come, in short, to a Being beyond Nature--its author, its God; +infinite, inconceivable, it may be, and yet one whom these very laws +present to us with attributes showing that our nature is in some way a +faint and far-cast shadow of His, while all the gentlest and the most +beautiful of our emotions lead us to believe that we are as children in +His care and as vessels in His hand. Let it then be understood--and this +for the reader's special attention--that when natural law is spoken of +here, reference is made only to the mode in which the Divine Power is +exercised. It is but another phrase for the action of the ever-present +and sustaining God. + +Viewing Nature in this light, the pursuit of science is but the seeking +of a deeper acquaintance with the Infinite. The endeavour to explain any +events in her history, however grand or mysterious these may be, is only +to sit like a child at a mother's knee, and fondly ask of the things +which passed before we were born; and in modesty and reverence we may +even inquire if there be any trace of the origin of that marvellous +arrangement of the universe which is presented to our notice. In this +inquiry we first perceive the universe to consist of a boundless +multitude of bodies with vast empty spaces between. We know of certain +motions among these bodies; of other and grander translations we are +beginning to get some knowledge. Besides this idea of locality and +movement, we have the equally certain one of a former soft and more +diffused state of the materials of these bodies; also a tolerably clear +one as to gravitation having been the determining cause of both locality +and movement. From these ideas the general one naturally suggested to us +is--a former stage in the frame of material things, perhaps only a point +in progress from some other, or a return from one like the +present--universal space occupied with gasiform matter. This, however, +was of irregular constitution, so that gravitation caused it to break up +and gather into patches, producing at once the relative localities of +astral and solar systems, and the movements which they have since +observed, in themselves and with regard to each other--from the daily +spinning of single bodies on their own axes, to the mazy dances of vast +families of orbs, which come to periods only in millions of years. + +How grand, yet how simple the whole of this process--for a God only to +conceive and do, and yet for man, after all, to trace out and ponder +upon. Truly must we be in some way immediate to the august Father, who +can think all this, and so come into His presence and council, albeit +only to fall prostrate and mutely adore. + +Not only are the orbs of space inextricably connected in the manner +which has been described, but the constitution of the whole is uniform, +for all consist of the same chemical elements. And now, in our version +of the romance of Nature, we descend from the consideration of +orb-filled space and the character of the universal elements, to trace +the history of our own globe. And we find that this falls significantly +into connection with the primary order of things suggested by Laplace's +theory of the origin of the solar system in a vast nebula or fire-mist, +which for ages past has been condensing under the influence of +gravitation and the radiation of its heat. + + +_II.--History of the Earth's Crust_ + +When we study the earth's crust we find that it consists of layers or +strata, laid down in succession, the earlier under the influence of +heat, the later under the influence of water. These strata in their +order might be described as a record of the state of life upon our +planet from an early to a comparatively recent period. It is truly such +a record, but not one perfectly complete. + +Nevertheless, we find a noteworthy and significant sequence. We learn +that there was dry land long before the occurrence of the first fossils +of land plants and animals. In different geographical formations we +find various species, though sometimes the same species is found in +different formations, having survived the great earth changes which the +record of the rocks indicates. There is an unbroken succession of animal +life from the beginning to the present epoch. Low down, where the +records of life begin, we find an era of backboneless animals only, and +the animal forms there found, though various, are all humble in their +respective lines of gradation. + +The early fishes were low, both with respect to their class as fishes, +and the order to which they belong--that of the cartilaginous or gristly +fishes. In all the orders of ancient animals there is an ascending +gradation of character from first to last. Further, there is a +succession from low to high types in fossil plants, from the earliest +strata in which they are found to the highest. Several of the most +important living species have left no record of themselves in any +formation beyond what are, comparatively speaking, modern. Such are the +sheep and the goat, and such, above all, is our own species. Compared +with many humbler animals, man is a being, as it were, of yesterday. + +Thus concludes the wondrous section of the earth's history which is told +by geology. It takes up our globe at an early stage in the formation of +its crust--conducts it through what we have every reason to believe were +vast spaces of time, in the course of which many superficial changes +took place, and vegetable and animal life was gradually evolved--and +drops it just at the point when man was apparently about to enter on the +scene. The compilation of such a history, from materials of so +extraordinary a character, and the powerful nature of the evidence which +these materials afford, are calculated to excite our admiration, and the +result must be allowed to exalt the dignity of science as a product of +man's industry and his reason. + +It is now to be remarked that there is nothing in the whole series of +operations displayed in inorganic geology which may not be accounted for +by the agency of the ordinary forces of Nature. Those movements of +subterranean force which thrust up mountain ranges and upheaved +continents stand in inextricable connection, on the one hand, with the +volcanoes which are yet belching forth lavas and shaking large tracts of +ground, as, on the other, with the primitive incandescent state of the +earth. Those forces which disintegrated the early rocks, of which +detritus formed new beds at the bottom of the sea, are still seen at +work to the same effect. + +To bring these truths the more nearly before us, it is possible to make +a substance resembling basalt in a furnace; limestone and sandstone have +both been formed from suitable materials in appropriate receptacles; the +phenomena of cleavage have, with the aid of electricity, been simulated +on a small scale, and by the same agent crystals are formed. In short, +the remark which was made regarding the indifference of the cosmical +laws to the scale on which they operated is to be repeated regarding the +geological. + +A common furnace will sometimes exemplify the operation of forces which +have produced the Giant's Causeway; and in a sloping ploughed field +after rain we may often observe, at the lower end of a furrow, a handful +of washed and neatly deposited mud or sand, capable of serving as an +illustration of the way in which Nature has produced the deltas of the +Nile and Ganges. In the ripple-marks on sandy beaches of the present day +we see Nature's exact repetition of the operations by which she +impressed similar features on the sandstones of the carboniferous era. +Even such marks as wind-slanted rain would in our day produce on +tide-deserted sands have been read upon tablets of the ancient strata. + +It is the same Nature--that is to say, God through or in the manner of +Nature--working everywhere and in all time, causing the wind to blow, +and the rain to fall, and the tide to ebb and flow, inconceivable ages +before the birth of our race, as now. So also we learn from the conifers +of those old ages that there were winter and summer upon earth, before +any of us lived to liken the one to all that is genial in our own +nature, or to say that the other breathed no airs so unkind as man's +ingratitude. Let no one suppose there is any necessary disrespect for +the Creator in thus tracing His laws in their minute and familiar +operations. There is really no true great and small, grand and familiar, +in Nature. Such only appear when we thrust ourselves in as a point from +which to start in judging. Let us pass, if possible, beyond immediate +impressions, and see all in relation to Cause, and we shall chastenedly +admit that the whole is alike worshipful. + +The Creator, then, is seen to have formed our earth, and effected upon +it a long and complicated series of changes, in the same manner in which +we find that he conducts the affairs of Nature before our living eyes; +that is, in the manner of natural law. This is no rash or unauthorised +affirmation. It is what we deduce from the calculation of a Newton and a +Laplace on the one hand, and from the industrious observation of facts +by a Murchison and a Lyell on the other. It is a point of stupendous +importance in human knowledge; here at once is the whole region of the +inorganic taken out of the dominion of marvel, and placed under an idea +of Divine regulation. + + +_III.--The History of the Earth's Life_ + +Mixed up, however, with the geological changes, and apparently as final +object connected with the formation of the globe itself, there is +another set of phenomena presented in the course of our history--the +coming into existence, namely, of a long suite of living things, +vegetable and animal, terminating in the families which we still see +occupying the surface. The question arises: In what manner has this set +of phenomena originated? Can we touch at and rest for a moment on the +possibility of plants and animals having likewise been produced in a +natural way, thus assigning immediate causes of but one character for +everything revealed to our sensual observation; or are we at once to +reject this idea, and remain content, either to suppose that creative +power here acted in a different way, or to believe unexaminingly that +the inquiry is one beyond our powers? Taking the last question first, I +would reply that I am extremely loth to imagine that there is anything +in Nature which we should, for any reason, refrain from examining. If we +can infer aught from the past history of science, it is that the whole +of Nature is a legitimate field for the exercise of our intellectual +faculties; that there is a connection between this knowledge and our +well-being; and that, if we may judge from things once despaired of by +our inquiring reason, but now made clear and simple, there is none of +Nature's mysteries which we may not hopefully attempt to penetrate. To +remain idly content to presume a various class of immediate causes for +organic Nature seems to me, on this ground, equally objectionable. + +With respect to the other question the idea has several times arisen +that some natural course was observed in the production of organic +things, and this even before we were permitted to attain clear +conclusions regarding inorganic nature. It was always set quickly aside +as unworthy of serious consideration. The case is different now, when we +have admitted law in the whole domain of the inorganic. + +Otherwise, the absurdities into which we should be led must strike every +reflecting mind. The Eternal Sovereign arranges a solar or an astral +system, by dispositions imparted primordially to matter; he causes, by +the same means, vast oceans to join and continents to rise, and all the +grand meteoric agencies to proceed in ceaseless alternation, so as to +fit the earth for a residence of organic beings. But when, in the course +of these operations, fuci and corals are to be, for the first time, +placed in these oceans, a change in his plan of administration is +required. It is not easy to say what is presumed to be the mode of his +operations. The ignorant believe the very hand of Deity to be at work. +Amongst the learned, we hear of "creative fiats," "interferences," +"interpositions of the creative energy," all of them very obscure +phrases, apparently not susceptible of a scientific explanation, but all +tending simply to this: that the work was done in a marvellous way, and +not in the way of Nature. + +But we need not assume two totally distinct modes of the exercise of the +divine power--one in the course of inorganic nature and the other in +intimately connected course of organic nature. + +Indeed, when all the evidence is surveyed, it seems difficult to resist +the impression that vestiges, at least, are seen of the manner and +method of the Creator in this part of His work. It appears to be a case +in which rigid proof is hardly to be looked for. But such evidences as +exist are remarkably consistent and harmonious. The theory pointed to +consorts with everything else which we have learned accurately regarding +the history of the universe. Science has not one positive affirmation on +the other side. Indeed, the view opposed to it is not one in which +science is concerned; it appears as merely one of the prejudices formed +in the non-age of our race. + +For the history, then, of organic nature, I embrace, not as a proved +fact, but as a rational interpretation of things as far as science has +revealed them, the idea of progressive development. We contemplate the +simplest and most primitive types of being as giving birth to a type +superior to it; this again producing the next higher, and so on to the +highest. We contemplate, in short, a universal gestation of Nature, like +that of the individual being, and attended as little by circumstances of +a miraculous kind as the silent advance of an ordinary mother from one +week to another of her pregnancy. + +Thus simple--after ages of marvelling--appears organic creation, while +yet the whole phenomena are, in another point of view, wonders of the +highest kind, being the undoubted results of ordinances arguing the +highest attributes of foresight, skill and goodness on the part of their +Divine Author. + +If, finally, we study the mind of man, we find that its Almighty Author +has destined it, like everything else, to be developed from inherent +qualities. + +Thus the whole appears complete on one principle. The masses of space +are formed by law; law makes them in due time theatres of existence for +plants and animals; sensation, disposition, intellect, are all in like +manner sustained in action by law. + +It is most interesting to observe into how small a field the whole of +the mysteries of Nature thus ultimately resolve themselves. The +inorganic has been thought to have one final comprehensive +law--gravitation. The organic, the other great department of mundane +things, rests in like manner on one law, and that is--development. Nor +may even these be after all twain, but only branches of one still more +comprehensive law, the expression of a unity flowing immediately from +the One who is first and last. + + +_IV.--The Future and its Meaning_ + +The question whether the human race will ever advance far beyond its +present position in intellect and morals is one which has engaged much +attention. Judging from the past, we cannot reasonably doubt that great +advances are yet to be made; but, if the principle of development be +admitted, these are certain, whatever may be the space of time required +for their realisation. A progression resembling development may be +traced in human nature, both in the individual and in large groups of +men. Not only so, but by the work of our thoughtful brains and busy +hands we modify external nature in a way never known before. The +physical improvements wrought by man upon the earth's surface I conceive +as at once preparations for, and causes of, the possible development of +higher types of humanity, beings less strong in the impulsive parts of +our nature, more strong in the reasoning and moral, more fitted for the +delights of social life, because society will then present less to dread +and more to love. + +The history and constitution of the world have now been hypothetically +explained, according to the best lights which a humble individual has +found within the reach of his perceptive and reasoning faculties. + +We have seen a system in which all is regularity and order, and all +flows from, and is obedient to, a divine code of laws of unbending +operation. We are to understand from what has been laid before us that +man, with his varied mental powers and impulses, is a natural problem of +which the elements can be taken cognisance of by science, and that all +the secular destinies of our race, from generation to generation, are +but evolutions of a law statuted and sustained in action by an all-wise +Deity. + +There may be a faith derived from this view of Nature sufficient to +sustain us under all sense of the imperfect happiness, the calamities, +the woes and pains of this sphere of being. For let us but fully and +truly consider what a system is here laid open to view and we cannot +well doubt that we are in the hands of One who is both able and willing +to do us the most entire justice. Surely, in such a faith we may well +rest at ease, even though life should have been to us but a protracted +malady. Thinking of all the contingencies of this world as to be in time +melted into or lost in some greater system, to which the present is only +subsidiary, let us wait the end with patience and be of good cheer. + + + + +GEORGES CUVIER + +The Surface of the Globe + + Georges Cuvier was born Aug. 24, 1769, at Montbeliard, France. He + had a brilliant academic career at Stuttgart Academy, and in 1795, + at the age of twenty-six, he was appointed assistant professor of + comparative anatomy at the Museum d'Histoire Naturelle in Paris, + and was elected a member of the National Institute. From this date + onwards to his death in 1832, his scientific industry was + remarkable. Both as zoologist and palaeontologist he must be + regarded as one of the greatest pioneers of science. He filled many + important scientific posts, including the chair of Natural History + in the College de France, and a professorship at the Jardin des + Plantes. In 1808 he was made member of the Council of the Imperial + University; and in 1814, President of the Council of Public + Instruction. In 1826 he was made grand officer of the Legion of + Honour, and five years later was made a peer of France. The + "Discours sur les Revolutions de la Surface du Globe," published in + 1825, is essentially a preliminary discourse to the author's + celebrated work, "Recherches sur les Ossemens fossiles de + Quadrupedes." It is an endeavour to trace the relationship between + the changes which have taken place on the surface of the globe and + the changes which have taken place in its animal inhabitants, with + especial reference to the evidence afforded by fossil remains of + quadrupeds. "It is apparent," Cuvier writes, "that the bones of + quadrupeds conduct us, by various reasonings, to more precise + results than any other relics of organised bodies." The two books + together may be considered the first really scientific + palaeontology. + + +_I.--Effects of Geological Change_ + +My first object will be to show how the fossil remains of the +terrestrial animals are connected with the theory of the earth. I shall +afterwards explain the principles by which fossil bones may be +identified. I shall give a rapid sketch of new species discovered by the +application of these principles. I shall then show how far these +varieties may extend, owing to the influence of the climate and +domestication. I shall then conceive myself justified in concluding that +the more considerable differences which I have discovered are the +results of very important catastrophes. Afterwards I shall explain the +peculiar influence which my researches should exercise on the received +opinions concerning the revolutions of the globe. Finally, I shall +examine how far the civil and religious history of nations accords with +the results of observation on the physical history of the earth. + +When we traverse those fertile plains, where tranquil waters cherish, as +they flow, an abundant vegetation, and where the soil, trod by a +numerous people, adorned with flourishing villages, rich cities, and +superb monuments, is never disturbed save by the ravages of war, or the +oppression of power, we can hardly believe that Nature has also had her +internal commotions. But our opinions change when we dig into this +apparently peaceful soil, or ascend its neighboring hills. The lowest +and most level soils are composed of horizontal strata, and all contain +marine productions to an innumerable extent. The hills to a very +considerable height are composed of similar strata and similar +productions. The shells are sometimes so numerous as to form the entire +mass of the soil, and all quarters of the globe exhibit the same +phenomenon. + +The time is past when ignorance could maintain that these remains of +organised bodies resulted from the caprice of Nature, and were +productions formed in the bosom of the earth by its generative powers; +for a scrupulous comparison of the remains shows not the slightest +difference between the fossil shells and those that are now found in the +ocean. It is clear, then, that they inhabited the sea, and that they +were deposited by the sea in the places where they are now found; and it +follows, too, that the sea rested in these places long enough to form +regular, dense, vast deposits of aquatic animals. + +The bed of the sea, accordingly, must have undergone some change either +in extent or situation. + +Further, we find under the horizontal strata, _inclined_ strata. Thus +the sea, previously to the formation of the horizontal strata, must have +formed others, which have been broken, inclined, and overturned by some +unknown causes. + +More than this, we find that the fossils vary with the depth of the +strata, and that the fossils of the deeper and more ancient strata +exhibit a formation proper to themselves; and we find in some of the +strata, too, remains of terrestrial life. + +The evidence is thus plain that the animal life in the sea has varied, +and that parts of the earth's surface have been alternately dry land and +ocean. The very soil, which terrestrial animals at present inhabit has a +history of previous animal life, and then submersion under the sea. + +The reiterated irruptions and retreats of the sea have not all been +gradual, but, on the contrary, they have been produced by sudden +catastrophes. The last catastrophe, which inundated and again left dry +our present continents, left in the northern countries the carcasses of +large quadrupeds, which were frozen, and which are preserved even to the +present day, with their skin, hair and flesh. Had they not been frozen +the moment they were killed, they must have putrefied; and, on the other +hand, the intense frost could not have been the ordinary climatic +condition, for they could not have existed at such low temperatures. In +the same instant, then, in which these animals perished the climate +which they inhabited must have undergone a complete revolution. + +The ruptures, the inclinations, the overturnings of the more ancient +strata, likewise point to sudden and violent changes. + +Animal life, then, has been frequently disturbed on this earth by +terrific catastrophes. Living beings innumerable have perished. The +inhabitants of the dry land have been engulfed by deluges; and the +tenants of the water, deserted by their element, have been left to +perish from drought. + +Even ancient rocks formed or deposited before the appearance of life on +the earth show signs of terrific violence. + +It has been maintained by some that the causes now at work altering the +face of the world are sufficient to account for all the changes through +which it has passed: but that is not so. None of the agents Nature now +employs--rain, thaw, rivers, seas, volcanoes--would have been adequate +to produce her ancient works. + +To explain the external crust of the world, we require causes other than +those present in operation, and a thousand extraordinary theories have +been advanced. Thus, according to one philosopher, the earth has +received in the beginning a uniform light crust which caused the abysses +of the ocean, and was broken to produce the Deluge. Another supposed the +Deluge to be caused by the momentary suspension of the cohesion of +minerals. + +Even accomplished scientists and philosophers have advanced impossible +and contradictory theories. + +All attempts at explanation have been stultified by an ignorance of the +facts to be explained, or by a partial survey of them, and especially by +a neglect of the evidence afforded by fossils. How was it possible not +to perceive that the theory of the earth owes its origin to fossils +alone? They alone, in truth, inform us with any certainty that the earth +has not always had the same covering, since they certainly must have +lived upon its surface before they were buried in its depths. If there +were only strata without fossils, one might maintain that the strata had +all been formed together. Hitherto, in fact, philosophers have been at +variance on every point save one, and that is that the sea has changed +its bed; and how could this have been known except for fossils? + +From this consideration I was led to study fossils; and since the field +was immense I was obliged to specialise in one department of fossils, +and selected for study the fossil bones of quadrupeds. I made this +selection because only from a study of fossil quadrupeds can one hope to +ascertain the number and periods and contents of irruptions of the sea; +and because, since the number of quadrupeds is limited, and most +quadrupeds known, we have better means of assuring ourselves if the +fossil remains are remains of extinct or extant animals. Animals such as +the griffin, the cartazonon, the unicorn, never lived, and there are +probably very few quadrupeds now living which have not been found by +man. + +But though the study of fossil quadruped be enlightening, it has its own +special difficulties. One great difficulty arises from the fact that it +is very rare to find a fossil skeleton approaching to a complete state. + +Fortunately, however, there is a principle in comparative anatomy which +lessens this difficulty. Every organised being constitutes a complete +and compact system with all its parts in mutual correspondence. None of +its parts can be changed without changing other parts, and consequently +each part, taken separately, indicates the others. + +Thus, if the intestines of an animal are made to digest raw flesh, its +jaws must be likewise constructed to devour prey, its claws to seize and +tear it, its teeth to rend it, its limbs to overtake it, its organs of +sense to discern it afar. Again, in order to enable the jaw to seize +with facility, a certain form of condyle is necessary, and the zygomatic +arch must be well developed to give attachment to the masseter muscle. +Again, the muscles of the neck must be powerful, whence results a +special form in the vertebrae and the occiput, where the muscles are +attached. Yet again, in order that the claws may be effective, the +toe-bones must have a certain form, and must have muscles and tendons +distributed in a certain way. In a word, the form of the tooth +necessitates the form of the condyle, of the shoulder-blade, and of the +claws, of the femur, and of all the other bones, and all the other bones +taken separately will give the tooth. In this manner anyone who is +scientifically acquainted with the laws of organic economy may from a +fragment reconstruct the whole animal. The mark of a cloven hoof is +sufficient to tell the form of the teeth and jaws and vertebrae and +leg-bones and thigh-bones and pelvis of the animal. The least fragment +of bone, the smallest apophysis, has a determinative character in +relation to the class, the order, the genus, and species to which it may +belong. This is so true that, if we have only a single extremity of bone +well preserved, we may, with application and a skilful use of analogy +and exact comparison, determine all those points with as much certainty +as if we were in possession of the entire animal. By the application of +these principles we have identified and classified the fossil remains of +more than one hundred and fifty mammalia. + + +_II.--What the Fossils Teach_ + +An examination of the fossils on the lines I have indicated shows that +out of one hundred and fifty mammiferous and oviparous quadrupeds, +ninety are unknown to present naturalists, and that in the older layers +such oviparous quadrupeds as the ichthyosauri and plesiosauri abound. +The fossil elephant, the rhinoceros, the hippopotamus, and the mastodons +are not found in the more ancient layers. In fact, the species which +appear the same as ours are found only in superficial deposits. + +Now, it cannot be held that the present races of animals differ from +the ancient races merely by modifications produced by local +circumstances and change of climate--for if species gradually changed, +we must find traces of these gradual modifications, and between the +palaeotheria and the present species we should have discovered some +intermediate formation; but to the present time none of these have +appeared. + +Why have not the bowels of the earth preserved the monuments of so +remarkable a genealogy unless it be that the species of former ages were +as constant as our own, or at least because the catastrophe that +destroyed them had not left them time to give evidence of the changes? + +Further, an examination of animals shows that though their superficial +characteristics, such as colour and size, are changeable, yet their more +radical characteristics do not change. Even the artificial breeding of +domestic animals can produce only a limited degree of variation. The +maximum variation known at the present time in the animal kingdom is +seen in dogs, but in all the varieties the relations of the bones remain +the same and the shape of the teeth undergoes no palpable change. + +I know that some naturalists rely much on the thousands of ages which +they can accumulate with a stroke of the pen; but there is nothing which +proves that time will effect any more than climate and a state of +domestication. I have endeavoured to collect the most ancient documents +of the forms of animals. I have examined the engravings of animals +including birds on the numerous columns brought from Egypt to Rome. M. +Saint Hilaire collected all the mummies of animals he could obtain in +Egypt--cats, ibises, birds of prey, dogs, monkeys, crocodiles, etc.--and +we cannot find any more difference between them and those of the present +day than between human mummies of that date and skeletons of the present +day. + +There is nothing, then, in known facts which can support the opinion +that the new genera discovered among fossils--the palaeotheria, +anoplotheria, megalonyces, mastodontes, pterodactyli, ichthyosauri, +etc.--could have been the sources of any animals now existing, which +would differ only by the influence of time or climate. + +As yet no human bones have been discovered in the regular layers of the +surface of the earth, so that man probably did not exist in the +countries where fossil bones are found at the epoch of the revolutions +which buried these bones, for there cannot be assigned any reason why +mankind should have escaped such overwhelming catastrophes, or why human +remains should not be discovered. Man _may_ have inhabited some confined +tract of country which escaped the catastrophe, but his establishment in +the countries where the fossil remains of land animals are found--that +is to say, in the greatest part of Europe, Asia, and America--is +necessarily posterior not only to the revolutions which covered these +bones, but even to those which have laid open the strata which envelop +them; whence it is clear that we can draw neither from the bones +themselves nor from the rocks which cover them any argument in favour of +the antiquity of the human species in these different countries. On the +contrary, in closely examining what has taken place on the surface of +the globe, since it was left dry for the last time, we clearly see that +the last revolution, and consequently the establishment of present +society, cannot be very ancient. An examination of the amount of +alluvial matter deposited by rivers, of the progress of downs, and of +other changes on the surface of the earth, informs us clearly that the +present state of things did not commence at a very remote period. + +The history of nations confirms the testimony of the fossils and of the +rocks. The chronology of none of the nations of the West can be traced +unbroken farther back than 3,000 years. The Pentateuch, the most ancient +document the world possesses, and all subsequent writings allude to a +universal deluge, and the Pentateuch and Vedas and Chou-king date this +catastrophe as not more than 5,400 years before our time. Is it possible +that mere chance gave a result so striking as to make the traditional +origin of the Assyrian, Indian, and Chinese monarchies agree in being as +remote as 4,000 or 5,000 years back? Would the ideas of nations with so +little inter-communication, whose language, religion, and laws have +nothing in common, agree on this point if they were not founded on +truth? Even the American Indians have their Noah or Deucalion, like the +Indians, Babylonians, and Greeks. + +It may be said that the long existence of ancient nations is attested by +their progress in astronomy. But this progress has been much +exaggerated. But what would this astronomy prove even if it were more +perfect? Have we calculated the progress which a science would make in +the bosom of nations which had no other? If among the multitude of +persons solely occupied with astronomy, even then, all that these people +knew might have been discovered in a few centuries, when only 300 years +intervened between Copernicus and Laplace. + +Again, it has been pretended that the zodiacal figures on ancient +temples give proof of a remote antiquity; but the question is very +complicated, and there are as many opinions as writers, and certainly no +conclusions against the newness of continents and nations can be based +on such evidence. The zodiac itself has been considered a proof of +antiquity, but the arguments brought forward are undoubtedly unsound. + +Even if these various astronomical proofs were as certain as they are +unconvincing, what conclusion could we draw against the great +catastrophe so indisputably demonstrated? We should only have the right +to conclude that astronomy was among the sciences preserved by those +persons whom the catastrophe spared. + +In conclusion, if there be anything determined in geology, it is that +the surface of our globe has been subjected to a revolution within 5,000 +years, and that this revolution buried the countries formerly inhabited +by man and modern animals, and left the bottom of the former sea dry as +a habitation for the few individuals it spared. Consequently, our +present human societies have arisen since this catastrophe. + +But the countries now inhabited had been inhabited before, as fossils +show, by animals, if not by mankind, and had been overwhelmed by a +previous deluge; and, indeed, judging by the different orders of animal +fossils we find, they had perhaps undergone two or three irruptions of +the sea. + + + + +CHARLES DARWIN + +The Origin of Species + + Charles Robert Darwin was born at Shrewsbury, England, Feb. 12, + 1809, of a family distinguished on both sides. Abandoning medicine + for natural history, he joined H.M.S. Beagle in 1831 on the five + years' voyage, which he described in "The Voyage of the Beagle," + and to which he refers in the introduction to his masterpiece. The + "Origin of Species" containing, in the idea of natural selection, + the distinctive contribution of Darwin to the theory of organic + evolution, was published in November, 1859. In only one brief + sentence did he there allude to man, but twelve years later he + published the "Descent of Man," in which the principles of the + earlier volume found their logical outcome. In other works Darwin + added vastly to our knowledge of coral reefs, organic variation, + earthworms, and the comparative expression of the emotions in man + and animals. Darwin died in ignorance of the work upon variation + done by his great contemporary, Gregor Mendel, whose work was + rediscovered in 1900. "Mendelism" necessitates much modification of + Darwin's work, which, however, remains the maker of the greatest + epoch in the study of life and the most important contribution to + that study ever made. Its immortal author died on April 19, 1882, + and was buried in Westminster Abbey. + + +_I.--Creation or Evolution?_ + +When on board H.M.S. Beagle as naturalist, I was much struck with +certain facts in the distribution of the organic beings inhabiting South +America, and in the geographical relations of the present to the past +inhabitants of that continent. These facts, as will be seen in the +latter chapters of this volume, seemed to throw some light on the origin +of species--that mystery of mysteries, as it has been called by one of +our greatest philosophers. On my return home, in 1837, it occurred to me +that something might perhaps be made out on this question by patiently +accumulating and reflecting on all sorts of facts which could possibly +have any bearing on it. After five years' work, I allowed myself to +speculate on the subject, and drew up some short notes; these I enlarged +in 1844 into a sketch of the conclusions which then seemed to me +probable. From that period to the present day I have steadily pursued +the same object. I hope that I may be excused for entering on these +personal details, as I give them to show that I have not been hasty in +coming to a decision. + +In considering the origin of species, it is quite conceivable that a +naturalist, reflecting on the mutual affinities of organic beings, on +their embryological relations, their geographical distribution, +geological succession, and other such facts, might come to the +conclusion that species had not been independently created, but had +descended, like varieties, from other species. Nevertheless, such a +conclusion, even if well founded, would be unsatisfactory, until it +could be shown how the innumerable species inhabiting this world have +been modified so as to acquire that perfection of structure and +co-adaptation which justly excites our admiration. + +Naturalists continually refer to external conditions, such as climate, +food, etc., as the only possible cause of variation. In one limited +sense, as we shall hereafter see, this may be true; but it is +preposterous to attribute to mere external conditions the structure, for +instance, of the woodpecker, with its feet, tail, beak, and tongue, so +admirably adapted to catch insects under the bark of trees. In the case +of the mistletoe, which draws its nourishment from certain trees, which +has seeds that must be transported by certain birds, and which has +flowers with separate sexes absolutely requiring the agency of certain +insects to bring pollen from one flower to the other, it is equally +preposterous to account for the structure of the parasite, with its +relations to several distinct organic beings, by the effects of external +conditions, or of habit, or of the volition of the plant itself. + +It is, therefore, of the highest importance to gain a clear insight into +the means of modification and co-adaptation. At the beginning of my +observations it seemed to me probable that a careful study of +domesticated animals and of cultivated plants would offer the best +chance of making out this obscure problem. Nor have I been disappointed; +in this and in all other perplexing cases I have invariably found that +our knowledge, imperfect though it be, of variation under domestication, +afforded the best and safest clue. I may venture to express my +conviction of the high value of such studies, although they have been +very commonly neglected by naturalists. + +Although much remains obscure, and will long remain obscure, I can +entertain no doubt, after the most deliberate study and dispassionate +judgment of which I am capable, that the view which most naturalists +until recently entertained, and which I formerly entertained--namely, +that each species has been independently created--is erroneous. I am +fully convinced that species are not immutable, but that those belonging +to what are called the same genera are lineal descendants of some other +and generally extinct species, in the same manner as the acknowledged +varieties of any one species are the descendants of that species. +Furthermore, I am also convinced that Natural Selection has been the +most important, but not the exclusive, means of modification. + + +_II.--Variation and Selection_ + +All living beings vary more or less from one another, and though +variations which are not inherited are unimportant for us, the number +and diversity of inheritable deviations of structure, both those of +slight and those of considerable physiological importance, are endless. + +No breeder doubts how strong is the tendency to inheritance; that like +produces like is his fundamental belief. Doubts have been thrown on +this principle only by theoretical writers. When any deviation of +structure often appears, and we see it in the father and child, we +cannot tell whether it may not be due to the same cause having acted on +both; but when amongst individuals, apparently exposed to the same +conditions, any very rare deviation, due to some extraordinary +combination of circumstances, appears in the parent--say, once amongst +several million individuals--and it re-appears in the child, the mere +doctrine of chances almost compels us to attribute its reappearance to +inheritance. + +Everyone must have heard of cases of albinism, prickly skin, hairy +bodies, etc., appearing in members of the same family. If strange and +rare deviations of structure are really inherited, less strange and +commoner deviations may be freely admitted to be inheritable. Perhaps +the correct way of viewing the whole subject would be to look at the +inheritance of every character whatever as the rule, and non-inheritance +as the anomaly. + +The laws governing inheritance are for the most part unknown. No one can +say why the same peculiarity in different individuals of the same +species, or in different species, is sometimes inherited and sometimes +not so; why the child often reverts in certain characters to its +grandfather or grandmother, or more remote ancestor; why a peculiarity +is often transmitted from one sex to both sexes, or to one sex alone, +more commonly but not exclusively to the like sex. + +The fact of heredity being given, we have evidence derived from human +practice as to the influence of selection. There are large numbers of +domesticated races of animals and plants admirably suited in various +ways to man's use or fancy--adapted to the environment of which his need +and inclination are the most essential constituents. We cannot suppose +that all the breeds were suddenly produced as perfect and as useful as +we now see them; indeed, in many cases, we know that this has not been +their history. The key is man's power of accumulative selection. Nature +gives successive variations; man adds them up in certain directions +useful to him. In this sense he may be said to have made for himself +useful breeds. + +The great power of this principle of selection is not hypothetical. It +is certain that several of our eminent breeders have, even within a +single lifetime, modified to a large extent their breeds of cattle and +sheep. What English breeders have actually effected is proved by the +enormous prices given for animals with a good pedigree; and these have +been exported to almost every quarter of the world. The same principles +are followed by horticulturists, and we see an astonishing improvement +in many florists' flowers, when the flowers of the present day are +compared with drawings made only twenty or thirty years ago. + +The practice of selection is far from being a modern discovery. The +principle of selection I find distinctly given in an ancient Chinese +encyclopaedia. Explicit rules are laid down by some of the Roman +classical writers. It is clear that the breeding of domestic animals was +carefully attended to in ancient times, and is now attended to by the +lowest savages. It would, indeed, have been a strange fact had attention +not been paid to breeding, for the inheritance of good and bad qualities +is so obvious. + +Study of the origin of our domestic races of animals and plants leads to +the following conclusions. Changed conditions of life are of the highest +possible importance in causing variability, both by acting directly on +the organisation, and indirectly by affecting the reproductive system. +Spontaneous variation of unknown origin plays its part. Some, perhaps a +great, effect may be attributed to the increased use or disuse of parts. + +The final result is thus rendered infinitely complex. In some cases the +intercrossing of aboriginally distinct species appears to have played +an important part in the origin of our breeds. When several breeds have +once been formed in any country, their occasional intercrossing, with +the aid of selection, has, no doubt, largely aided in the formation of +new sub-breeds; but the importance of crossing has been much +exaggerated, both in regard to animals and to those plants which are +propagated by seed. Over all these causes of change, the accumulative +action of selection, whether applied methodically and quickly, or +unconsciously and slowly, but more efficiently, seems to have been the +predominant power. + + +_III.--Variation Under Nature_ + +Before applying these principles to organic beings in a state of nature, +we must ascertain whether these latter are subject to any variation. We +find variation everywhere. Individual differences, though of small +interest to the systematist, are of the highest importance for us, for +they are often inherited; and they thus afford materials for natural +selection to act and accumulate, in the same manner as man accumulates +in any given direction individual differences in his domesticated +productions. Further, what we call varieties cannot really be +distinguished from species in the long run, a fact which we can clearly +understand if species once existed as varieties, and thus originated. +But the facts are utterly inexplicable if species are independent +creations. + +How have all the exquisite adaptations of one part of the body to +another part, and to the conditions of life, and of one organic being to +another being, been perfected? For everywhere we find these beautiful +adaptations. + +The answer is to be found in the struggle for life. Owing to this +struggle, variations, however slight, and from whatever cause +proceeding, if they be in any degree profitable to the individuals of a +species in their infinitely complex relations to other organic beings +and to their physical conditions of life, will tend to the preservation +of such individuals, and will generally be inherited by the offspring. +The offspring, also, will thus have a better chance of surviving, for, +of the many individuals of any species which are periodically born, but +a small number can survive. I have called this principle, by which each +slight variation, if useful, is preserved, by the term Natural +Selection, in order to mark its relation to man's power of selection. +But the expression, often used by Mr. Herbert Spencer, of the Survival +of the Fittest, is more accurate. + +We have seen that man, by selection, can certainly produce great +results, and can adapt organic beings to his own uses, through the +accumulation of slight but useful variations given to him by the hand of +Nature. Natural Selection is a power incessantly ready for action, and +is as immeasurably superior to man's feeble efforts as the works of +Nature are to those of Art. + +All organic beings are exposed to severe competition. Nothing is easier +than to admit in words the truth of the universal struggle for life, or +more difficult--at least, I have found it so--than constantly to bear +this conclusion in mind. Yet, unless it be thoroughly engrained in the +mind, the whole economy of Nature, with every fact of distribution, +rarity, abundance, extinction, and variation, will be dimly seen or +quite misunderstood. We behold the face of Nature bright with gladness; +we often see superabundance of food. We do not see, or we forget, that +the birds which are idly singing round us mostly live on insects or +seeds, and are thus constantly destroying life; or we forget how largely +these songsters, or their eggs, or their nestlings, are destroyed by +birds or beasts of prey. We do not always bear in mind that, though food +may be superabundant, it is not so at all seasons of each recurring +year. + +A struggle for existence, the term being used in a large, general, and +metaphorical sense, inevitably follows from the high rate at which all +organic beings tend to increase. + +Every being, which during its natural lifetime produces several eggs or +seeds, must suffer destruction during some period of its life, and +during some season or occasional year; otherwise, on the principle of +geometrical increase, its numbers would quickly become so inordinately +great that no country could support the product. Hence, as more +individuals are produced than can possibly survive, there must in every +case be a struggle for existence, either one individual with another of +the same species, or with the individuals of distinct species, or with +the physical conditions of life. It is the doctrine of Malthus applied +with manifold force to the whole animal and vegetable kingdoms; for in +this case there can be no artificial increase of food, and no prudential +restraint from marriage. Although some species may be now increasing, +more or less rapidly, in numbers, all cannot do so, for the world would +not hold them. + +There is no exception to the rule that every organic being naturally +increases at so high a rate that, if not destroyed, the earth would soon +be covered by the progeny of a single pair. Even slow-breeding man has +doubled in twenty-five years, and at this rate, in less than a thousand +years, there would literally not be standing-room for his progeny. +Linnaeus has calculated that if an annual plant produced only two +seeds--and there is no plant so unproductive as this--and their +seedlings next year produced two, and so on, then in twenty years there +would be a million plants. The elephant is reckoned the slowest breeder +of all known animals, and I have taken some pains to estimate its +probable minimum rate of natural increase. It will be safest to assume +that it begins breeding when thirty years old, and goes on breeding +until ninety years old, bringing forth six young in the interval, and +surviving till one hundred years old. If this be so, after a period of +from 740 to 750 years there would be nearly nineteen million elephants +alive, descended from the first pair. + +The causes which check the natural tendency of each species to increase +are most obscure. Eggs or very young animals seem generally to suffer +most, but this is not invariably the case. With plants there is a vast +destruction of seeds. The amount of food for each species of course +gives the extreme limit to which each can increase; but very frequently +it is not the obtaining food, but the serving as prey to other animals, +which determines the average number of a species. Climate is important, +and periodical seasons of extreme cold or drought seem to be the most +effective of all checks. + +The relations of all animals and plants to each other in the struggle +for existence are most complex, and often unexpected. Battle within +battle must be continually recurring with varying success; and yet in +the long run the forces are so nicely balanced that the face of Nature +remains for long periods of time uniform, though assuredly the merest +trifle would give the victory to one organic being over another. +Nevertheless, so profound is our ignorance, and so high our presumption, +that we marvel when we hear of the extinction of an organic being; and +as we do not see the cause, we invoke cataclysms to desolate the world, +or invent laws on the duration of the forms of life! + +The struggle for life is most severe between individuals and varieties +of the same species. The competition is most severe between allied forms +which fill nearly the same place in the economy of Nature. But great is +our ignorance on the mutual relations of all organic beings. All that we +can do is to keep steadily in mind that each organic being is striving +to increase in a geometrical ratio; that each at some period of its +life, during some season of the year, during each generation or at +intervals, has to struggle for life and to suffer great destruction. +When we reflect on this struggle, we may console ourselves with the full +belief that the war of Nature is not incessant, that no fear is felt, +that death is generally prompt, and that the vigorous, the healthy, and +the happy survive and multiply. + + +_IV.--The Survival of the Fittest_ + +How will the struggle for existence act in regard to variation? Can the +principle of selection, which we have seen is so potent in the hands of +man, apply under Nature? I think we shall see that it can act most +efficiently. Let the endless number of slight variations and individual +differences occurring in our domestic productions, and, in a lesser +degree, in those under Nature, be borne in mind, as well as the strength +of the hereditary tendency. Under domestication, it may be truly said +that the whole organisation becomes in some degree plastic. + +But the variability, which we almost universally meet with in our +domestic productions, is not directly produced by man; he can neither +originate variations nor prevent their occurrence; he can only preserve +and accumulate such as do occur. Unintentionally he exposes organic +beings to new and changing conditions of life, and variability ensues; +but similar changes of condition might and do occur under Nature. + +Let it also be borne in mind how infinitely complex and close-fitting +are the mutual relations of all organic beings to each other and to +their physical conditions of life, and consequently what infinitely +varied diversities of structure might be of use to each being under +changing conditions of life. Can it, then, be thought improbable, seeing +what variations useful to man have undoubtedly occurred, that other +variations, useful in some way to each being in the great complex battle +of life, should occur in the course of many successive generations? If +such do occur, can we doubt, remembering that many more individuals are +born than can possibly survive, that individuals having any advantage +over others, would have the best chance of surviving and of procreating +their kind? On the other hand, we may feel sure that any variation in +the least degree injurious would be rigidly destroyed. This preservation +of favourable individual differences and variations, and the destruction +of those which are injurious, I have called Natural Selection, or the +Survival of the Fittest. + +The term is too frequently misapprehended. Variations neither useful nor +injurious would not be affected by natural selection. It is not asserted +that natural selection induces variability. It implies only the +preservation of such varieties as arise and are beneficial to the being +under its conditions of life. Again, it has been said that I speak of +natural selection as an active Power or Deity; but who objects to an +author speaking of the attraction of gravity as ruling the movements of +the planets? It is difficult to avoid personifying the word Nature; but +I mean by Nature only the aggregate action and product of many natural +laws, and by laws the sequence of events as ascertained by us. + +As man can produce, and certainly has produced, a great result by his +methodical and unconscious means of selection, what may not natural +selection effect? Man can act only on external and visible characters; +Nature, if I may be allowed to personify the natural preservation or +survival of the fittest, cares nothing for appearances, except in so far +as they are useful to any being. She can act on every internal organ, on +every shade of constitutional difference, on the whole machinery of +life. Man selects only for his own good; Nature only for that of the +being which she tends. Every selected character is fully exercised by +her, as is implied by the fact of their selection. Man keeps the natives +of many climates in the same country; he seldom exercises each selected +character in some peculiar and fitting manner; he feeds a long and a +short-beaked pigeon on the same food; he does not exercise a long-backed +or long-legged quadruped in any peculiar manner; he exposes sheep with +long and short wool to the same climate. + +Man does not allow the most vigorous males to struggle for the females. +He does not rigidly destroy all inferior animals, but protects during +each varying season, as far as lies in his power, all his productions. +He often begins his selection by some half-monstrous form; or at least +by some modification prominent enough to catch the eye or to be plainly +useful to him. + +But under Nature, the slightest differences of structure or constitution +may well turn the nicely-balanced scale in the struggle for life, and so +be preserved. How fleeting are the wishes and efforts of man! How short +his time! And, consequently, how poor will be his results compared with +those accumulated by Nature during whole geological periods! Can we +wonder that Nature's productions should be far "truer" in character than +man's productions; that they should be infinitely better adapted to the +most complex conditions of life, and should plainly bear the stamp of +far higher workmanship? + +It may metaphorically be said that natural selection is daily and hourly +scrutinising, throughout the world, the slightest variations; rejecting +those that are bad, preserving and adding up all that are good; silently +and insensibly working, whenever and wherever opportunity offers, at the +improvement of each organic being in relation to its organic and +inorganic conditions of life. We see nothing of these slow changes in +progress until the hand of time has marked the lapse of ages, and then +so imperfect is our view into long-past geological ages that we see only +that the forms of life are now different from what they formerly were. + +Although natural selection can act only through and for the good of +each being, yet characters and structures, which we are apt to consider +as of very trifling importance, may thus be acted on. + +Natural selection will modify the structure of the young in relation to +the parent, and of the parent in relation to the young. In social +animals it will adapt the structure of each individual for the benefit +of the whole community, if the community profits by the selected change. +What natural selection cannot do is to modify the structure of one +species, without giving it any advantage, for the good of another +species; and though statements to this effect may be found in works of +natural history, I cannot find one case which will bear investigation. + +A structure used only once in an animal's life, if of high importance to +it, might be modified to any extent by natural selection; for instance, +the great jaws possessed by certain insects, used exclusively for +opening the cocoon, or the hard tip to the beak of unhatched birds, used +for breaking the egg. It has been asserted that of the best short-beaked +tumbler pigeons a greater number perish in the egg than are able to get +out of it; so that fanciers assist in the act of hatching. Now, if +Nature had to make the beak of a full-grown pigeon very short for the +bird's own advantage, the process of modification would be very slow, +and there would be simultaneously the most rigorous selection of all the +young birds within the egg, for all with weak beaks would inevitably +perish; or more easily broken shells might be selected, the thickness of +the shell being known to vary like every other structure. + +With all beings there must be much fortuitous destruction, which can +have little or no influence on the course of natural selection. For +instance, a vast number of eggs or seeds are annually devoured, and +these could be modified through natural selection only if they varied +in some manner which protected them from their enemies. Yet many of +these eggs or seeds would perhaps, if not destroyed, have yielded +individuals better adapted to their conditions of life than any of those +which happened to survive. So, again, a vast number of mature animals +and plants, whether or not they be the best adapted to their conditions, +must be annually destroyed by accidental causes, which would not be in +the least degree mitigated by certain changes of structure or +constitution which would in other ways be beneficial to the species. + +But let the destruction of the adults be ever so heavy, if the number +which can exist in any district be not wholly kept down by such +causes--or, again, let the destruction of eggs or seeds be so great that +only a hundredth or a thousandth part are developed--yet of those which +do survive, the best adapted individuals, supposing there is any +variability in a favourable direction, will tend to propagate their kind +in larger numbers than the less well adapted. + +On our theory the continued existence of lowly organisms offers no +difficulty; for natural selection does not necessarily include +progressive development; it only takes advantage of such variations as +arise and are beneficial to each creature under its complex relations of +life. + +The mere lapse of time by itself does nothing, either for or against +natural selection. I state this because it has been erroneously asserted +that the element of time has been assumed by me to play an all-important +part in modifying species, as if all the forms of life were necessarily +undergoing change through some innate law. + + +_V.--Sexual Selection_ + +This form of selection depends, not on a struggle for existence in +relation to other organic beings or to external conditions, but on a +struggle between the individuals of one sex, generally the males, for +the possession of the other sex. The result is not death to the +unsuccessful competitor, but few or no offspring. Sexual selection is, +therefore, less rigorous than natural selection. Generally, the most +vigorous males, those which are best fitted for their places in Nature, +will leave most progeny. But, in many cases, victory depends not so much +on general vigour as on having special weapons, confined to the male +sex. A hornless stag or spurless cock would have a poor chance of +leaving numerous offspring. Sexual selection, by always allowing the +victor to breed, might surely give indomitable courage, length to the +spur, and strength to the wing to strike in the spurred leg, in nearly +the same manner as does the brutal cock-fighter by the careful selection +of his best cocks. + +How low in the scale of Nature the law of battle descends I know not. +Male alligators have been described as fighting, bellowing, and whirling +round, like Indians in a war-dance, for the possession of the females; +male salmons have been observed fighting all day long; male stag-beetles +sometimes bear wounds from the mandibles of other males; the males of +certain other insects have been frequently seen fighting for a +particular female who sits by, an apparently unconcerned beholder of the +struggle, and then retires with the conqueror. The war is, perhaps, +severest between the males of the polygamous animals, and these seem +oftenest provided with special weapons. The males of carnivorous animals +are already well armed, though to them special means of defence may be +given through means of sexual selection, as the mane of the lion and the +hooked jaw of the salmon. The shield may be as important for victory as +the sword or spear. + +Amongst birds, the contest is often of a more peaceful character. All +those who have attended to the subject believe that there is the +severest rivalry between the males of many species to attract, by +singing, the females. The rock-thrush of Guiana, birds of paradise, and +some others, congregate; and successive males display with the most +elaborate care, and show off in the best manner, their gorgeous plumage; +they likewise perform strange antics before the females, which, standing +by as spectators, at last choose the most attractive partner. + +If man can in a short time give beauty and an elegant carriage to his +bantams, according to his standard of beauty, I can see no good reason +to doubt that female birds, by selecting, during thousands of +generations, the most melodious or beautiful males, according to their +standard of beauty, might produce a marked effect. + + +_VI.--The Struggle for Existence_ + +Under domestication we see much variability, caused, or at least +excited, by changed conditions of life; but often in so obscure a manner +that we are tempted to consider the variations as spontaneous. +Variability is governed by many complex laws--by correlated growth, +compensation, the increased use and disuse of parts, and the definite +action of the surrounding conditions. There is much difficulty in +ascertaining how largely our domestic productions have been modified; +but we may safely infer that the amount has been large, and that +modifications can be inherited for long periods. As long as the +conditions of life remain the same, we have reason to believe that a +modification, which has already been inherited for many generations, may +continue to be inherited for an almost infinite number of generations. +On the other hand, we have evidence that variability, when it has once +come into play, does not cease under domestication for a very long +period; nor do we know that it ever ceases, for new varieties are still +occasionally produced by our oldest domesticated productions. + +Variability is not actually caused by man; he only unintentionally +exposes organic beings to new conditions of life, and then Nature acts +on the organisation and causes it to vary. But man can and does select +the variations given to him by Nature, and thus accumulates them in any +desired manner. He thus adapts animals and plants for his own benefit or +pleasure. He may do this methodically, or he may do it unconsciously by +preserving the individuals most useful or pleasing to him without an +intention of altering the breed. + +It is certain that he can influence the character of a breed by +selecting, in each successive generation, individual differences so +slight as to be inappreciable except by an educated eye. This +unconscious process of selection has been the agency in the formation of +the most distinct and useful domestic breeds. That many breeds produced +by man have to a large extent the character of natural species is shown +by the inextricable doubts whether many of them are varieties or +aboriginally distinct species. + +There is no reason why the principles which have acted so efficiently +under domestication should not have acted under Nature. In the survival +of favoured individuals and races, during the constantly recurrent +struggle for existence, we see a powerful and ever-acting form of +selection. The struggle for existence inevitably follows from the high +geometrical ratio of increase which is common to all organic beings. +This high rate of increase is proved by calculation; by the rapid +increase of many animals and plants during a succession of peculiar +seasons and when naturalised in new countries. More individuals are born +than can possibly survive. A grain in the balance may determine which +individuals shall live and which shall die; which variety or species +shall increase in number, and which shall decrease, or finally become +extinct. + +As the individuals of the same species come in all respects into the +closest competition with each other, the struggle will generally be +most severe between them; it will be almost equally severe between the +varieties of the same species, and next in severity between the species +of the same genus. On the other hand, the struggle will often be severe +between beings remote in the scale of Nature. The slightest advantage in +certain individuals, at any age or during any season, over those with +which they come into competition, or better adaptation, in however +slight a degree, to the surrounding physical conditions, will, in the +long run, turn the balance. + +With animals having separated sexes, there will be in most cases a +struggle between the males for the possession of the females. The most +vigorous males, or those which have most successfully struggled with +their conditions of life, will generally leave most progeny. But success +will often depend on the males having special weapons, or means of +defence, or charms; and a slight advantage will lead to victory. + +As geology plainly proclaims that each land has undergone great physical +changes, we might have expected to find that organic beings have varied +under Nature in the same way as they have varied under domestication. +And if there has been any variability under Nature, it would be an +unaccountable fact if natural selection had not come into play. It has +often been asserted, but the assertion is incapable of proof, that the +amount of variation under Nature is a strictly limited quantity. Man, +though acting on external characters alone, and often capriciously, can +produce within a short period a great result by adding up mere +individual differences in his domestic productions; and everyone admits +that species present individual differences. But, besides such +differences, all naturalists admit that natural varieties exist, which +are considered sufficiently distinct to be worthy of record in +systematic works. + +No one has drawn any clear distinction between individual differences +and slight varieties, or between more plainly marked varieties and +sub-species and species. On separate continents, and on different parts +of the same continent when divided by barriers of any kind, what a +multitude of forms exist which some experienced naturalists rank as +varieties, others as geographical races or sub-species, and others as +distinct, though closely allied species! + +If, then, animals and plants do vary, let it be ever so slightly or +slowly, why should not variations or individuals, differences which are +in any way beneficial, be preserved and accumulated through natural +selection, or the survival of the fittest? If man can, by patience, +select variations useful to him, why, under changing and complex +conditions of life, should not variations useful to Nature's living +products often arise, and be preserved, or selected? What limit can be +put to this power, acting during long ages and rigidly scrutinising the +whole constitution, structure, and habits of each creature--favouring +the good and rejecting the bad? I can see no limit to this power, in +slowly and beautifully adapting each form to the most complex relations +of life. + +In the future I see open fields for far more important researches. +Psychology will be based on the foundation already well laid by Mr. +Herbert Spencer--that of the necessary acquirement of each mental power +and capacity by gradation. Much light will be thrown on the origin of +man and his history. + +Authors of the highest eminence seem to be fully satisfied with the view +that each species has been independently created. To my mind it accords +better with what we know of the laws impressed on matter by the Creator +that the production and extinction of the past and present inhabitants +of the world should have been due to secondary causes, like those +determining the birth and death of the individual. When I view all +beings not as special creations, but as the lineal descendants of some +few beings which lived long before the first bed of the Cambrian system +was deposited, they seem to me to become ennobled. Judging from the +past, we may safely infer that not one living species will transmit its +unaltered likeness to a distant futurity. + +Of the species now living very few will transmit progeny of any kind to +a far distant futurity; for the manner in which all organic beings are +grouped shows that the greater number of species in each genus, and all +the species in many genera, have left no descendants, but have become +utterly extinct. We can so far take a prophetic glance into futurity as +to foretell that it will be the common and widely-spread species, +belonging to the larger and dominant groups within each class, which +will ultimately prevail and procreate new and dominant species. As all +the living forms of life are the lineal descendants of those which lived +long before the Cambrian epoch, we may feel certain that the ordinary +succession by generation has never once been broken, and that no +cataclysm has desolated the whole world. We may look with some +confidence to a secure future of great length. As natural selection +works solely by and for the good of each being, all corporeal and mental +endowments will tend to progress towards perfection. + +It is interesting to contemplate a tangled bank, clothed with many +plants of many kinds, with birds singing on the bushes, with various +insects flitting about, and with worms crawling through the damp earth, +and to reflect that these elaborately constructed forms, so different +from each other, and dependent upon each other in so complex a manner, +have all been produced by laws acting around us. These laws, taken in +the largest sense, being Growth with Reproduction; Inheritance, which is +almost implied by reproduction; Variability from the indirect and direct +action of the conditions of life, and from use and disuse; a ratio of +increase so high as to lead to a struggle for life, and, as a +consequence, to Natural Selection, entailing Divergence of Character +and the Extinction of less improved forms. Thus, from the war of Nature, +from famine and death, the most exalted object which we are capable of +conceiving, namely, the production of the higher animals, directly +follows. There is grandeur in this view of life, with its several +powers, having been originally breathed by the Creator into a few forms, +or into one; and that, whilst this planet has gone cycling on according +to the fixed law of gravity, from so simple a beginning endless forms +most beautiful and most wonderful have been, and are being, evolved. + + + + +SIR HUMPHRY DAVY + +Elements of Chemical Philosophy + + Humphry Davy, the celebrated natural philosopher, was born Dec. 17, + 1778, at Penzance, England. At the age of seventeen he became an + apothecary's apprentice, and at the age of nineteen assistant at + Dr. Beddoes's pneumatic institution at Bristol. During researches + at the pneumatic institution he discovered the physiological + effects of "laughing gas," and made so considerable a reputation as + a chemist that at the age of twenty-two he was appointed lecturer, + and a year later professor, at the Royal Institution. For ten + years, from 1803, he was engaged in agricultural researches, and in + 1813 published his "Elements of Agricultural Chemistry." During the + same decade he conducted important investigations into the nature + of chemical combination, and succeeded in isolating the elements + potassium, sodium, strontium, magnesium, and chlorine. In 1812 he + was knighted, and married Mrs. Apreece, _nee_ Jane Kerr. In 1815 he + investigated the nature of fire-damp and invented the Davy safety + lamp. In 1818 he received a baronetcy, and two years later was + elected President of the Royal Society. On May 29, 1829, he died at + Geneva. Davy's "Elements of Chemical Philosophy," of which a + summary is given here, was published in one volume in 1812, being + the substance of lectures delivered before the Board of + Agriculture. + + +_I.--Forms and Changes of Matter_ + +The forms and appearances of the beings and substances of the external +world are almost infinitely various, and they are in a state of +continued alteration. In general, matter is found in four forms, as (1) +solids, (2) fluids, (3) gases, (4) ethereal substances. + +1. _Solids._ Solids retain whatever mechanical form is given to them; +their parts are separated with difficulty, and cannot readily be made to +unite after separation. They may be either elastic or non-elastic, and +differ in hardness, in colour, in opacity, in density, in weight, and, +if crystalline, in crystalline form. + +2. _Fluids._ Fluids, when in small masses, assume the spherical form; +their parts possess freedom of motion; they differ in density and +tenacity, in colour, and in opacity. They are usually regarded as +incompressible; at least, a very great mechanical force is required to +compress them. + +3. _Gases._ Gases exist free in the atmosphere, but may be confined. +Their parts are highly movable; they are compressible and expansible, +and their volumes are inversely as the weight compressing them. All +known gases are transparent, and present only two or three varieties of +colour; they differ materially in density. + +4. _Ethereal Substances._ Ethereal substances are known to us only in +their states of motion when acting upon our organs of sense, or upon +other matter, and are not susceptible of being confined. It cannot be +doubted that there is such matter in motion in space. Ethereal matter +differs either in its nature, or in its affections by motion, for it +produces different effects; for instance, radiant heat, and different +kinds of light. + +All these forms of matter are under the influence of active forces, such +as gravitation, cohesion, heat, chemical and electrical attraction, and +these we must now consider. + +1. _Gravitation._ When a stone is thrown into the atmosphere, it rapidly +descends towards the earth. This is owing to gravitation. All the great +bodies in the universe are urged towards each other by a similar force. +Bodies mutually gravitate towards each other, but the smaller body +proportionately more than the larger one; hence the power of gravity is +said to vary directly as the mass. Gravitation also varies with +distance, and acts inversely as the square of the distance. + +2. _Cohesion._ Cohesion is the force which preserves the forms of +solids, and gives globularity to fluids. It is usually said to act only +at the surface of bodies or by their immediate contact; but this does +not seem to be the case. It certainly acts with much greater energy at +small distances, but the spherical form of minute portions of fluid +matter can be produced only by the attractions of all the parts of which +they are composed, for each other; and most of these attractions must be +exerted at sensible distances, so that gravitation and cohesion may be +mere modifications of the same general power of attraction. + +3. _Heat._ When a body which occasions the sensation of heat on our +organs is brought into contact with another body which has no such +effect, the hot body contracts and loses to a certain extent its power +of communicating heat; and the other body expands. Different solids and +fluids expand very differently when heated, and the expansive power of +liquids, in general, is greater than that of solids. + +It is evident that the density of bodies must be diminished by +expansion; and in the case of fluids and gases, the parts of which are +mobile, many important phenomena depend upon this circumstance. For +instance, if heat be applied to fluids and gases, the heated parts +change their places and rise, and the currents in the ocean and +atmosphere are due principally to this movement. There are very few +exceptions to the law of the expansion of bodies at the time they become +capable of communicating the sensation of heat, and these exceptions +seem to depend upon some chemical change in the constitution of bodies, +or on their crystalline arrangements. + +The power which bodies possess of communicating or receiving heat is +known as _temperature_, and the temparature of a body is said to be high +or low with respect to another in proportion as it occasions an +expansion or contraction of its parts. + +When equal volumes of different bodies of different temperatures are +suffered to remain in contact till they acquire the same temperature, it +is found that this temperature is not a mean one, as it would be in the +case of equal volumes of the same body. Thus if a pint of quicksilver +at 100 deg. be mixed with a pint of water at 50 deg., the resulting temperature +is not 75 deg., but 70 deg.; the mercury has lost thirty degrees, whereas the +water has only gained twenty degrees. This difference is said to depend +on the different _capacities_ of bodies for heat. + +Not only do different bodies vary in their capacity for heat, but they +likewise acquire heat with very different degrees of celerity. This last +difference depends on the different power of bodies for _conducting_ +heat, and it will be found that as a rule the densest bodies, with the +least capacity for heat, are the best conductors. + +Heat, or the power of repulsion, may be considered as the _antagonist_ +power to the attraction of cohesion. Thus solids by a certain increase +of temperature become fluids, and fluids gases; and, _vice versa_, by a +diminution of temperature, gases become fluids, and fluids solids. + +Proofs of the conversion of solids, fluids, or gases into ethereal +substances are not distinct. Heated bodies become luminous and give off +radiant heat, which affects the bodies at a distance, and it may +therefore be held that particles are thrown off from heated bodies with +great velocity, which, by acting on our organs, produce the sensations +of heat or light, and that their motion, communicated to the particles +of other bodies, has the power of expanding them. It may, however, be +said that the radiant matters emitted by bodies in ignition are specific +substances, and that common matter is not susceptible of assuming this +form; or it may be contended that the phenomena of radiation do in fact, +depend upon motions communicated to subtile matter everywhere existing +in space. + +The temperatures at which bodies change their states from fluids to +solids, though in general definite, are influenced by a few +circumstances such as motion and pressure. + +When solids are converted into fluids, or fluids into gases, there is +always a loss of heat of temperature; and, _vice versa_, when gases are +converted into fluids, or fluids into solids, there is an increase of +heat of temperature, and in this case it is said that _latent_ heat is +absorbed or given out. + +The expansion due to heat has been accounted for by supposing a subtile +fluid, or _caloric_, capable of combining with bodies and of separating +their parts from each other, and the absorption and liberation of latent +heat can be explained on this principle. But many other facts are +incompatible with the theory. For instance, metal may be kept hot for +any length of time by friction, so that if _caloric_ be pressed out it +must exist in an inexhaustible quantity. Delicate experiments have shown +that bodies, when heated, do not increase in weight. + +It seems possible to account for all the phenomena of heat, if it be +supposed that in solids the particles are in a constant state of +vibratory motion, the particles of the hottest bodies moving with the +greatest velocity and through the greatest space; that in fluids and +gases the particles have not only vibratory motion, but also a motion +round their own axes with different velocities, and that in ethereal +substances the particles move round their own axes and separate from +each other, penetrating in right lines through space. Temperature may be +conceived to depend upon the velocity of the vibrations, increase of +capacity on the motion being performed in greater space; and the +diminution of temperature during the conversion of solids into fluids or +gases may be explained on the idea of the loss of vibratory motion in +consequence of the revolution of particles round their axes at the +moment when the body becomes fluid or aeriform, or from the loss of +rapidity of vibration in consequence of the motion of particles through +greater space. + +4. _Chemical Attraction._ Oil and water will not _combine_; they are +said to have no chemical _attraction_ or _affinity_ for each other. But +if oil and solution of potassa in water be mixed, the oil and the +solution blend and form a soap; and they are said to attract each other +chemically or to have a _chemical affinity_ for each other. It is a +general character of chemical combination that it changes the qualities +of the bodies. Thus, corrosive and pungent substances may become mild +and tasteless; solids may become fluids, and solids and fluids gases. + +No body will act chemically upon another body at any sensible distance; +apparent contact is necessary for chemical action. A freedom of motion +in the parts of the bodies or a want of cohesion greatly assists action, +and it was formerly believed that bodies cannot act chemically upon each +other unless one of them be fluid or gaseous. + +Different bodies unite with different degrees of force, and hence one +body is capable of separating others from certain of their combinations, +and in consequence mutual decompositions of different compounds take +place. This has been called _double affinity_, or _complex chemical +affinity_. + +As in all well-known compounds the proportions of the elements are in +certain definite ratios to each other, it is evident that these ratios +may be expressed by numbers; and if one number be employed to denote the +smallest quantity in which a body combines, all other quantities of the +same body will be multiples of this number, and the smallest proportions +into which the undecomposed bodies enter into union being known, the +constitution of the compounds they form may be learnt, and the element +which unites chemically in the smallest quantity being expressed by +unity, all the other elements may be represented by the relations of +their quantities to unity. + +5. _Electrical Attraction._ A piece of dry silk briskly rubbed against a +warm plate of polished flint glass acquires the property of adhering to +the glass, and both the silk and the glass, if apart from each other, +attract light substances. The bodies are said to be _electrically +excited_. Probably, all bodies which differ from each other become +electrically excited when rubbed and pressed together. The electrical +excitement seems of two kinds. A pith-ball touched by glass excited by +silk repels a pith-ball touched by silk excited by metals. Electrical +excitement of the same nature as that in glass excited by silk is known +as _vitreous_ or _positive_, and electrical excitement of the opposite +nature is known as _resinous_ or _negative_. + +A rod of glass touched by an electrified body is electrified only round +the point of contact. A rod of metal, on the contrary, suspended on a +rod of glass and brought into contact with an electrical surface, +instantly becomes electrical throughout. The glass is said to be a +_non-conductor_, or _insulating substance_; the metal a _conductor_. + +When a non-conductor or imperfect conductor, provided it be a thin plate +of matter placed upon a conductor, is brought in contact with an excited +electrical body, the surface opposite to that of contact gains the +opposite electricity from that of the excited body, and if the plate be +removed it is found to possess two surfaces in opposite states. If a +conductor be brought into the neighbourhood of an excited body--the air, +which is a non-conductor, being between them--that extremity of the +conductor which is opposite to the excited body gains the opposite +electricity; and the other extremity, if opposite to a body connected +with the ground, gains the same electricity, and the middle point is not +electrical at all. This is known as _induced_ electricity. + +The common exhibition of electrical effects is in attractions and +repulsions; but electricity also produces chemical phenomena. If a piece +of zinc and copper in contact with each other at one point be placed in +contact at other points with the same portion of water, the zinc will +corrode, and attract oxygen from the water much more rapidly than if it +had not been in contact with the copper; and if sulphuric acid be added, +globules of inflammable air are given off from the copper, though it is +not dissolved or acted upon. + +Chemical phenomena in connection with electrical effects can be shown +even better by combinations in which the electrical effects are +increased by alterations of different metals and fluids--the so-called +_voltaic batteries_. Such are the decomposing powers of such batteries +that not even insoluble compounds are capable of resisting their energy, +for even glass, sulphate of baryta, fluorspar, etc., are slowly acted +upon, and the alkaline, earthy, or acid matter carried to the poles in +the common order. + +The most powerful voltaic combinations are formed by substances that act +chemically with most energy upon each other, and such substances as +undergo no chemical changes in the combination exhibit no electrical +powers. Hence it was supposed that the electrical powers of metals were +entirely due to chemical changes; but this is not the case, for contact +produces electricity even when no chemical change can be observed. + + +_II.--Radiant or Ethereal Matter_ + +When similar thermometers are placed in different parts of the solar +beam, it is found that different effects are produced in the differently +coloured rays. The greatest heat is exhibited in the red rays, the least +in the violet rays; and in a space beyond the red rays, where there is +no visible light, the increase of temperature is greatest of all. + +From these facts it is evident that matter set in motion by the sun has +the power of producing heat without light, and that its rays are less +refrangible than the visible rays. The invisible rays that produce heat +are capable of reflection as well as refraction in the same manner as +the visible rays. + +Rays capable of producing heat with and without light proceed not only +from the sun, but also from bodies at the surface of the globe under +peculiar agencies or changes. If, for instance, a thermometer be held +near an ignited body, it receives an impression connected with an +elevation of temperature; this is partly produced by the conducting +powers of the air, and partly by an impulse which is instantaneously +communicated, even to a considerable distance. This effect is called the +radiation of terrestrial heat. + +The manner in which the temperatures of bodies are affected by rays +producing heat is different for different substances, and is very much +connected with their colours. The bodies that absorb most light, and +reflect least, are most heated when exposed either to solar or +terrestrial rays. Black bodies are, in general, more heated than red; +red more than green; green more than yellow; and yellow more than white. +Metals are less heated than earthy or stony bodies, or than animal or +vegetable matters. Polished surfaces are less heated than rough +surfaces. + +The bodies that have their temperatures most easily raised by heat rays +are likewise those that are most easily cooled by their own radiation, +or that at the same temperature emit most heat-making rays. Metals +radiate less heat than glass, glass less than vegetable substances, and +charcoal has the highest radiating powers of any body as yet made the +subject of experiment. + +Radiant matter has the power of producing chemical changes partly +through its heating power, and partly through some other specific and +peculiar influence. Thus chlorine and hydrogen detonate when a mixture +of them is exposed to the solar beams, even though the heat is +inadequate to produce detonation. + +If moistened silver be exposed to the different rays of the solar +spectrum, it will be found that no effect is produced upon it by the +least refrangible rays which occasion heat without light; that a slight +discoloration only will be produced by the red rays; that the effect of +blackening will be greater towards the violet end of the spectrum; and +that in a space beyond the violet, where there is no sensible heat or +light, the chemical effect will be very distinct. There seem to be rays, +therefore, more refrangible than the rays producing light and heat. + +The general facts of the refraction and effects of the solar beam offer +an analogy to the agencies of electricity. + +In general, in Nature the effects of the solar rays are very compounded. +Healthy vegetation depends upon the presence of the solar beams or of +light, and while the heat gives fluidity and mobility to the vegetable +juices, chemical effects are likewise occasioned, oxygen is separated +from them, and inflammable compounds are formed. Plants deprived of +light become white and contain an excess of saccharine and aqueous +particles; and flowers owe the variety of their hues to the influence of +the solar beams. Even animals require the presence of the rays of the +sun, and their colours seem to depend upon the chemical influence of +these rays. + +Two hypotheses have been invented to account for the principal +operations of radiant matter. In the first it is supposed that the +universe contains a highly rare elastic substance, which, when put into +a state of undulation, produces those effects on our organs of sight +which constitute the sensations of vision and other phenomena caused by +solar and terrestrial rays. In the second it is conceived that particles +are emitted from luminous or heat-making bodies with great velocity, and +that they produce their effects by communicating their motions to +substances, or by entering into them and changing their composition. + +Newton has attempted to explain the different refrangibility of the rays +of light by supposing them composed of particles differing in size. The +same great man has put the query whether light and common matter are not +convertible into each other; and, adopting the idea that the phenomena +of sensible heat depend upon vibrations of the particles of bodies, +supposes that a certain intensity of vibrations may send off particles +into free space, and that particles in rapid motion in right lines, in +losing their own motion, may communicate a vibratory motion to the +particles of terrestrial bodies. + + + + +MICHAEL FARADAY + +Experimental Researches in Electricity + + Michael Faraday was the son of a Yorkshire blacksmith, and was born + in London on September 22, 1791. At the age of twenty he became + assistant to Sir Humphry Davy, whose lectures he had attended at + the Royal Institution. Here he worked for the rest of his laborious + life, which closed on August 25, 1867. The fame of Faraday, among + those whose studies qualify them for a verdict, has risen steadily + since his death, great though it then was. His researches were of + truly epoch-making character, and he was the undisputed founder of + the modern science of electricity, which is rapidly coming to + dominate chemistry itself. Faraday excelled as a lecturer, and + could stand even the supreme test of lecturing to children. + Faraday's "Experimental Researches in Electricity" is a record of + some of the most brilliant experiments in the history of science. + In the course of his investigations he made discoveries which have + had momentous consequences. His discovery of the mutual relation of + magnets and of wires conducting electric currents was the beginning + of the modern dynamo and all that it involves; while his + discoveries of electric induction and of electrolysis were of equal + significance. Most of the researches are too technical for + epitomisation; but those given are representative of his manner and + methods. + + +_I.--Atmospheric Magnetism_ + +It is to me an impossible thing to perceive that two-ninths of the +atmosphere by weight is a highly magnetic body, subject to great changes +in its magnetic character, by variations in its temperature and +condensation or rarefaction, without being persuaded that it has much to +do with the variable disposition of the magnetic forces upon the surface +of the earth. + +The earth is a spheroidal body consisting of paramagnetic and +diamagnetic substances irregularly disposed and intermingled; but for +the present the whole may be considered a mighty compound magnet. The +magnetic force of this great magnet is known to us only on the surface +of the earth and water of our planet, and the variations in the magnetic +lines of force which pass in or across this surface can be measured by +their action on small standard magnets; but these variations are limited +in their information, and do not tell us whether the cause is in the air +above or the earth beneath. + +The lines of force issue from the earth in the northern and southern +parts and coalesce with each other over the equatorial, as would be the +case in a globe having one or two short magnets adjusted in relation to +its axis, and it is probable that the lines of force in their circuitous +course may extend through space to tens of thousands of miles. The lines +proceed through space with a certain degree of facility, but there may +be variations in space, _e.g._, variations in its temperature which +affect its power of transmitting the magnetic influence. + +Between the earth and space, however, is interposed the atmosphere, and +at the bottom of the atmosphere we live. The atmosphere consists of four +volumes of nitrogen and one of oxygen uniformly mixed and acting +magnetically as a single medium. The _nitrogen_ of the air is, as +regards the magnetic force, neither paramagnetic nor diamagnetic, +whether dense or rare, or at high or low temperatures. + +The _oxygen_ of the air, on the other hand, is highly paramagnetic, +being, bulk for bulk, equivalent to a solution of protosulphate of iron, +containing of the crystallised salt seventeen times the weight of the +oxygen. It becomes less paramagnetic, volume for volume, as it is +rarefied, and apparently in the simple proportion of its rarefaction, +the temperature remaining the same. When its temperature is raised--the +expansion consequent thereon being permitted--it loses very greatly its +paramagnetic force, and there is sufficient reason to conclude that when +its temperature is lowered its paramagnetic condition is exalted. These +characters oxygen preserves even when mingled with the nitrogen in the +air. + +Hence the atmosphere is a highly magnetic medium, and this medium is +changed in its magnetic relations by every change in its density and +temperature, and must affect both the intensity and direction of the +magnetic force emanating from the earth, and may account for the +variations which we find in terrestrial magnetic power. + +We may expect as the sun leaves us on the west some magnetic effect +correspondent to that of the approach of a body of cold air from the +east. Again, the innumerable circumstances that break up more or less +any average arrangement of the air temperatures may be expected to give +not merely differences in the regularity, direction, and degree of +magnetic variation, but, because of vicinity, differences so large as to +be many times greater than the mean difference for a given short period, +and they may also cause irregularities in the times of their occurrence. +Yet again, the atmosphere diminishes in density upwards, and this +diminution will affect the transmission of the electric force. + +The result of the _annual variation_ that may be expected from the +magnetic constitution and condition of the atmosphere seems to me to be +of the following kind. + +Since the axis of the earth's rotation is inclined 23 deg. 28' to the plane +of the ecliptic, the two hemispheres will become alternately warmer and +cooler than each other. The air of the cooled hemisphere will conduct +magnetic influence more freely than if in the mean state, and the lines +of force passing through it will increase in amount, whilst in the other +hemisphere the warmed air will conduct with less readiness than before, +and the intensity will diminish. In addition to this effect of +temperature, there ought to be another due to the increase of the +ponderable portion of the air in the cooled hemisphere, consequent on +its contraction and the coincident expansion of the air in the warmer +half, both of which circumstances tend to increase the variation in +power of the two hemispheres from the normal state. Then, as the earth +rolls on its annual journey, that which was at one time the cooler +becomes the warmer hemisphere, and in its turn sinks as far below the +average magnetic intensity as it before had stood above it, while the +other hemisphere changes its magnetic condition from less to more +intense. + + +_II.--Electro-Chemical Action_ + +The theory of definite electrolytical or electro-chemical action appears +to me to touch immediately upon the absolute quantity of electricity +belonging to different bodies. As soon as we perceive that chemical +powers are definite for each body, and that the electricity which we can +loosen from each body has definite chemical action which can be +measured, we seem to have found the link which connects the proportion +of that we have evolved to the proportion belonging to the particles in +their natural state. + +Now, it is wonderful to observe how small a quantity of a compound body +is decomposed by a certain quantity of electricity. One grain of water, +for instance, acidulated to facilitate conduction, will require an +electric current to be continued for three minutes and three-quarters to +effect its decomposition, and the current must be powerful enough to +keep a platina wire 1/104 inch in thickness red hot in the air during +the whole time, and to produce a very brilliant and constant star of +light if interrupted anywhere by charcoal points. It will not be too +much to say that this necessary quantity of electricity is equal to a +very powerful flash of lightning; and yet when it has performed its full +work of electrolysis, it has separated the elements of only a single +grain of water. + +On the other hand, the relation between the conduction of the +electricity and the decomposition of the water is so close that one +cannot take place without the other. If the water be altered only in +that degree which consists in its having the solid instead of the fluid +state, the conduction is stopped and the decomposition is stopped with +it. Whether the conduction be considered as depending upon the +decomposition or not, still the relation of the two functions is equally +intimate. + +Considering this close and twofold relation--namely, that without +decomposition transmission of electricity does not occur, and that for a +given definite quantity of electricity passed an equally definite and +constant quantity of water or other matter is decomposed; considering +also that the agent, which is electricity, is simply employed in +overcoming electrical powers in the body subjected to its action, it +seems a probable and almost a natural consequence that the quantity +which passes is the equivalent of that of the particles separated; +_i.e._, that if the electrical power which holds the elements of a grain +of water in combination, or which makes a grain of oxygen and hydrogen +in the right proportions unite into water when they are made to combine, +could be thrown into a current, it would exactly equal the current +required for the separation of that grain of water into its elements +again; in other words, that the electricity which decomposes and that +which is evolved by the decomposition of a certain quantity of matter +are alike. + +This view of the subject gives an almost overwhelming idea of the +extraordinary quantity or degree of electric power which naturally +belongs to the particles of matter, and the idea may be illustrated by +reference to the voltaic pile. + +The source of the electricity in the voltaic instrument is due almost +entirely to chemical action. Substances interposed between its metals +are all electrolytes, and the current cannot be transmitted without +their decomposition. If, now, a voltaic trough have its extremities +connected by a body capable of being decomposed, such as water, we shall +have a continuous current through the apparatus, and we may regard the +part where the acid is acting on the plates and the part where the +current is acting upon the water as the reciprocals of each other. In +both parts we have the two conditions, _inseparable in such bodies as +these_: the passing of a current, and decomposition. In the one case we +have decomposition associated with a current; in the other, a current +followed by decomposition. + +Let us apply this in support of my surmise respecting the enormous +electric power of each particle or atom of matter. + +Two wires, one of platina, and one of zinc, each one-eighteenth of an +inch in diameter, placed five-sixteenths of an inch apart, and immersed +to the depth of five-eighths of an inch in acid, consisting of one drop +of oil of vitriol and four ounces of distilled water at a temperature of +about 60 deg. Fahrenheit, and connected at the other ends by a copper wire +eighteen feet long, and one-eighteenth of an inch in thickness, yielded +as much electricity in little more than three seconds of time as a +Leyden battery charged by thirty turns of a very large and powerful +plate electric machine in full action. This quantity, although +sufficient if passed at once through the head of a rat or cat to have +killed it, as by a flash of lightning, was evolved by the mutual action +of so small a portion of the zinc wire and water in contact with it that +the loss of weight by either would be inappreciable; and as to the water +which could be decomposed by that current, it must have been insensible +in quantity, for no trace of hydrogen appeared upon the surface of the +platina during these three seconds. It would appear that 800,000 such +charges of the Leyden battery would be necessary to decompose a single +grain of water; or, if I am right, to equal the quantity of electricity +which is naturally associated with the elements of that grain of water, +endowing them with their mutual chemical affinity. + +This theory of the definite evolution and the equivalent definite action +of electricity beautifully harmonises the associated theories of +definite proportions and electro-chemical affinity. + +According to it, the equivalent weights of bodies are simply those +quantities of them which contain equal quantities of electricity, or +have naturally equal electric powers, it being the electricity which +_determines_ the equivalent number, _because_ it determines the +combining force. Or, if we adopt the atomic theory or phraseology, then +the atoms of bodies which are equivalent to each other in their ordinary +chemical action have equal quantities of electricity naturally +associated with them. I cannot refrain from recalling here the beautiful +idea put forth, I believe, by Berzelius in his development of his views +of the electro-chemical theory of affinity, that the heat and light +evolved during cases of powerful combination are the consequence of the +electric discharge which is at the moment taking place. The idea is in +perfect accordance with the view I have taken of the quantity of +electricity associated with the particles of matter. + +The definite production of electricity in association with its definite +action proves, I think, that the current of electricity in the voltaic +pile is sustained by chemical decomposition, or, rather, by chemical +action, and not by contact only. But here, as elsewhere, I beg to +reserve my opinion as to the real action of contact. + +Admitting, however, that chemical action is the source of electricity, +what an infinitely small fraction of that which is active do we obtain +and employ in our voltaic batteries! Zinc and platina wires +one-eighteenth of an inch in diameter and about half an inch long, +dipped into dilute sulphuric acid, so weak that it is not sensibly sour +to the tongue, or scarcely sensitive to our most delicate test papers, +will evolve more electricity in one-twentieth of a minute than any man +would willingly allow to pass through his body at once. + +The chemical energy represented by the satisfaction of the chemical +affinities of a grain of water and four grains of zinc can evolve +electricity equal in quantity to that of a powerful thunderstorm. Nor is +it merely true that the quantity is active; it can be directed--made to +perform its full equivalent duty. Is there not, then, great reason to +believe that, by a closer investigation of the development and action of +this subtile agent, we shall be able to increase the power of our +batteries, or to invent new instruments which shall a thousandfold +surpass in energy those we at present possess? + + +_III.--The Gymnotus, or Electric Eel_ + +Wonderful as are the laws and phenomena of electricity when made evident +to us in inorganic or dead matter, their interest can bear scarcely any +comparison with that which attaches to the same force when connected +with the nervous system and with life. + +The existence of animals able to give the same concussion to the living +system as the electrical machine, the voltaic battery, and the +thunderstorm being made known to us by various naturalists, it became +important to identify their electricity with the electricity produced by +man from dead matter. In the case of the _Torpedo_ [a fish belonging to +the family of Electric Rings] this identity has been fully proved, but +in the case of the _Gymnotus_ the proof has not been quite complete, and +I thought it well to obtain a specimen of the latter fish. + +A gymnotus being obtained, I conducted a series of experiments. Besides +the hands two kinds of collectors of electricity were used--one with a +copper disc for contact with the fish, and the other with a plate of +copper bent into saddle shape, so that it might enclose a certain +extent of the back and sides of the fish. These conductors, being put +over the fish, collected power sufficient to produce many electric +effects. + +SHOCK. The shock was very powerful when the hands were placed one near +the head and the other near the tail, and the nearer the hands were +together, within certain limits, the less powerful was the shock. The +disc conductors conveyed the shock very well when the hands were wetted. + +GALVANOMETER. A galvanometer was readily affected by using the saddle +conductors, applied to the anterior and posterior parts of the gymnotus. +A powerful discharge of the fish caused a deflection of thirty or forty +degrees. The deflection was constantly in a given direction, the +electric current being always from the anterior part of the animal +through the galvanometer wire to the posterior parts. The former were, +therefore, for the time externally positive and the latter negative. + +MAKING A MAGNET. When a little helix containing twenty-two feet of +silked wire wound on a quill was put into a circuit, and an annealed +steel needle placed in the helix, the needle became a magnet; and the +direction of its polarity in every cast indicated a current from the +anterior to the posterior parts of the gymnotus. + +CHEMICAL DECOMPOSITION. Polar decomposition of a solution of iodide of +potassium was easily obtained. + +EVOLUTION OF HEAT. Using a Harris' thermo-electrometer, we thought we +were able, in one instance, to observe a feeble elevation of +temperature. + +SPARK. By suitable apparatus a spark was obtained four times. + +Such were the general electric phenomena obtained from the gymnotus, and +on several occasions many of the phenomena were obtained together. Thus, +a magnet was made, a galvanometer deflected, and, perhaps, a wire heated +by one single discharge of the electric force of the animal. When the +shock is strong, it is like that of a large Leyden battery charged to a +low degree, or that of a good voltaic battery of, perhaps, one hundred +or more pairs of plates, of which the circuit is completed for a moment +only. + +I endeavoured by experiment to form some idea of the quantity of +electricity, and came to the conclusion that a single medium discharge +of the fish is at least equal to the electricity of a Leyden battery of +fifteen jars, containing 3,500 square inches of glass coated on both +sides, charged to its highest degree. This conclusion is in perfect +accordance with the degree of deflection which the discharge can produce +in a galvanometer needle, and also with the amount of chemical +decomposition produced in the electrolysing experiments. + +The gymnotus frequently gives a double and even a triple shock, with +scarcely a sensible interval between each discharge. + +As at the moment of shock the anterior parts are positive and the +posterior negative, it may be concluded that there is a current from the +former to the latter through every part of the water which surrounds the +animal, to a considerable distance from its body. The shock which is +felt, therefore, when the hands are in the most favourable position is +the effect of a very small portion only of the electricity which the +animal discharges at the moment, by far the largest portion passing +through the surrounding water. + +This enormous external current must be accompanied by some effect within +the fish _equivalent_ to a current, the direction of which is from the +tail towards the head, and equal to the sum of _all these external_ +forces. Whether the process of evolving or exciting the electricity +within the fish includes the production of the internal current, which +is not necessarily so quick and momentary as the external one, we cannot +at present say; but at the time of the shock the animal does not +apparently feel the electric sensation which he causes in those around +him. + +The gymnotus can stun and kill fish which are in very various relations +to its own body. The extent of surface which the fish that is about to +be struck offers to the water conducting the electricity increases the +effect of the shock, and the larger the fish, accordingly, the greater +must be the shock to which it will be subjected. + + + + +The Chemical History of a Candle + + "The Chemical History of a Candle" was the most famous course in + the long and remarkable series of Christmas lectures, "adapted to a + juvenile auditory," at the Royal Institution, and remains a + rarely-approached model of what such lectures should be. They were + illustrated by experiments and specimens, but did not depend upon + these for coherence and interest. They were delivered in 1860-61, + and have just been translated, though all but half-a-century old, + into German. + + +_I.--Candles and their Flames_ + +There is not a law under which any part of this universe is governed +that does not come into play in the phenomena of the chemical history of +a candle. There is no better door by which you can enter into the study +of natural philosophy than by considering the physical phenomena of a +candle. + +And now, my boys and girls, I must first tell you of what candles are +made. Some are great curiosities. I have here some bits of timber, +branches of trees particularly famous for their burning. And here you +see a piece of that very curious substance taken out of some of the bogs +in Ireland, called _candle-wood_--a hard, strong, excellent wood, +evidently fitted for good work as a resister of force, and yet withal +burning so well that, where it is found, they make splinters of it, and +torches, since it burns like a candle, and gives a very good light +indeed. And in this wood we have one of the most beautiful illustrations +of the general nature of a candle that I can possibly give. The fuel +provided, the means of bringing that fuel to the place of chemical +action, the regular and gradual supply of air to that place of +action--heat and light all produced by a little piece of wood of this +kind, forming, in fact, a natural candle. + +But we must speak of candles as they are in commerce. Here are a couple +of candles commonly called dips. They are made of lengths of cotton cut +off, hung up by a loop, dipped into melted tallow, taken out again and +cooled; then re-dipped until there is an accumulation of tallow round +the cotton. However, a candle, you know, is not now a greasy thing like +an ordinary tallow candle, but a clean thing; and you may almost scrape +off and pulverise the drops which fall from it without soiling anything. + +The candle I have in my hand is a stearine candle, made of stearine from +tallow. Then here is a sperm candle, which comes from the purified oil +of the spermaceti whale. Here, also, are yellow beeswax and refined +beeswax from which candles are made. Here, too, is that curious +substance called paraffin, and some paraffin candles made of paraffin +obtained from the bogs of Ireland. I have here also a substance brought +from Japan, a sort of wax which a kind friend has sent me, and which +forms a new material for the manufacture of candles. + +Now, as to the light of the candle. We will light one or two, and set +them at work in the performance of their proper function. You observe a +candle is a very different thing from a lamp. With a lamp you take a +little oil, fill your vessel, put in a little moss, or some cotton +prepared by artificial means, and then light the top of the wick. When +the flame runs down the cotton to the oil, it gets stopped, but it goes +on burning in the part above. Now, I have no doubt you will ask, how is +it that the oil, which will not burn of itself, gets up to the top of +the cotton, where it will burn? We shall presently examine that; but +there is a much more wonderful thing about the burning of a candle than +this. You have here a solid substance with no vessel to contain it; and +how is it that this solid substance can get up to the place where the +flame is? Or, when it is made a fluid, then how is it that it keeps +together? This is a wonderful thing about a candle. + +You see, then, in the first instance, that a beautiful cup is formed. As +the air comes to the candle, it moves upwards by the force of the +current which the heat of the candle produces, and it so cools all the +sides of the wax, tallow, or fuel as to keep the edge much cooler than +the part within; the part within melts by the flame that runs down the +wick as far as it can go before it is stopped, but the part on the +outside does not melt. If I made a current in one direction, my cup +would be lopsided, and the fluid would consequently run over--for the +same force of gravity which holds worlds together, holds this fluid in a +horizontal position. You see, therefore, that the cup is formed by this +beautifully regular ascending current of air playing upon all sides, +which keeps the exterior of the candle cool. No fuel would serve for a +candle which has not the property of giving this cup, except such fuel +as the Irish bogwood, where the material itself is like a sponge, and +holds its own fuel. + +You see now why you have such a bad result if you burn those beautiful +fluted candles, which are irregular, intermittent in their shape, and +cannot therefore have that nicely-formed edge to the cup which is the +great beauty in a candle. I hope you will now see that the perfection of +a process--that is, its utility--is the better point of beauty about it. +It is not the best-looking thing, but the best-acting thing which is the +most advantageous to us. This good-looking candle is a bad burning one. +There will be a guttering round about it because of the irregularity of +the stream of air and the badness of the cup which is formed thereby. + +You may see some pretty examples of the action of the ascending current +when you have a little gutter run down the side of a candle, making it +thicker there than it is elsewhere. As the candle goes on burning, that +keeps its place and forms a little pillar sticking up by the side, +because, as it rises higher above the rest of the wax or fuel, the air +gets better round it, and it is more cooled and better able to resist +the action of the heat at a little distance. Now, the greatest mistakes +and faults with regard to candles, as in many other things, often bring +with them instruction which we should not receive if they had not +occurred. You will always remember that whenever a result happens, +especially if it be new, you should say: "What is the cause? Why does it +occur?" And you will in the course of time find out the reason. + +Then there is another point about these candles which will answer a +question--that is, as to the way in which this fluid gets out of the +cup, up to the wick, and into the place of combustion. You know that the +flames on these burning wicks in candles made of beeswax, stearine, or +spermaceti, do not run down to the wax or other matter, and melt it all +away, but keep to their own right place. They are fenced off from the +fluid below, and do not encroach on the cup at the sides. + +I cannot imagine a more beautiful example than the condition of +adjustment under which a candle makes one part subserve to the other to +the very end of its action. A combustible thing like that, burning away +gradually, never being intruded upon by the flame, is a very beautiful +sight; especially when you come to learn what a vigorous thing flame is, +what power it has of destroying the wax itself when it gets hold of it, +and of disturbing its proper form if it come only too near. + +But how does the flame get hold of the fuel? There is a beautiful point +about that. It is by what is called capillary attraction that the fuel +is conveyed to the part where combustion goes on, and is deposited +there, not in a careless way, but very beautifully in the very midst of +the centre of action which takes place around it. + + +_II.--The Brightness of the Candle_ + +Air is absolutely necessary for combustion; and, what is more, I must +have you understand that _fresh_ air is necessary, or else we should be +imperfect in our reasoning and our experiments. Here is a jar of air. I +place it over a candle, and it burns very nicely in it at first, showing +that what I have said about it is true; but there will soon be a change. +See how the flame is drawing upwards, presently fading, and at last +going out. And going out, why? Not because it wants air merely, for the +jar is as full now as it was before, but it wants pure, fresh air. The +jar is full of air, partly changed, partly not changed; but it does not +contain sufficient of the fresh air for combustion. + +Suppose I take a candle, and examine that part of it which appears +brightest to our eyes. Why, there I get these black particles, which are +just the smoke of the candle; and this brings to mind that old +employment which Dean Swift recommended to servants for their amusement, +namely, writing on the ceiling of a room with a candle. But what is that +black substance? Why, it is the same carbon which exists in the candle. +It evidently existed in the candle, or else we should not have had it +here. You would hardly think that all those substances which fly about +London in the form of soots and blacks are the very beauty and life of +the flame. Here is a piece of wire gauze which will not let the flame go +through it, and I think you will see, almost immediately, that, when I +bring it low enough to touch that part of the flame which is otherwise +so bright, it quells and quenches it at once, and allows a volume of +smoke to rise up. + +Whenever a substance burns without assuming the vaporous state--whether +it becomes liquid or remains solid--it becomes exceedingly luminous. +What I say is applicable to all substances--whether they burn or whether +they do not burn--that they are exceedingly bright if they retain their +solid state when heated, and that it is to this presence of solid +particles in the candle-flame that it owes its brilliancy. + +I have here a piece of carbon, or charcoal, which will burn and give us +light exactly in the same manner as if it were burnt as part of a +candle. The heat that is in the flame of a candle decomposes the vapour +of the wax, and sets free the carbon particles--they rise up heated and +glowing as this now glows, and then enter into the air. But the +particles when burnt never pass off from a candle in the form of carbon. +They go off into the air as a perfectly invisible substance, about which +we shall know hereafter. + +Is it not beautiful to think that such a process is going on, and that +such a dirty thing as charcoal can become so incandescent? You see, it +comes to this--that all bright flames contain these solid particles; all +things that burn and produce solid particles, either during the time +they are burning, as in the candle, or immediately after being burnt, as +in the case of the gunpowder and iron-filings--all these things give us +this glorious and beautiful light. + + +_III.--The Products of Combustion_ + +We observe that there are certain products as the result of the +combustion of a candle, and that of these products one portion may be +considered as charcoal, or soot; that charcoal, when afterwards burnt, +produces some other product--carbonic acid, as we shall see; and it +concerns us very much now to ascertain what yet a third product is. + +Suppose I take a candle and place it under a jar. You see that the sides +of the jar become cloudy, and the light begins to burn feebly. It is the +products, you see, which make the light so dim, and this is the same +thing which makes the sides of the jar so opaque. If you go home and +take a spoon that has been in the cold air, and hold it over a +candle--not so as to soot it--you will find that it becomes dim, just as +that jar is dim. If you can get a silver dish, or something of that +kind, you will make the experiment still better. It is _water_ which +causes the dimness, and we can make it, without difficulty, assume the +form of a liquid. + +And so we can go on with almost all combustible substances, and we find +that if they burn with a flame, as a candle, they produce water. You may +make these experiments yourselves. The head of a poker is a very good +thing to try with, and if it remains cold long enough over the candle, +you may get water condensed in drops on it; or a spoon, or a ladle, or +anything else may be used, provided it be clean, and can carry off the +heat, and so condense the water. + +And now--to go into the history of this wonderful production of water +from combustibles, and by combustion--I must first of all tell you that +this water may exist in different conditions; and although you may now +be acquainted with all its forms, they still require us to give a little +attention to them for the present, so that we may perceive how the +water, whilst it goes through its protean changes, is entirely and +absolutely the same thing, whether it is produced from a candle, by +combustion, or from the rivers or ocean. + +First of all, water, when at the coldest, is ice. Now, we speak of water +as water; whether it be in its solid, or liquid, or gaseous state, we +speak of it chemically as water. + +We shall not in future be deceived, therefore, by any changes that are +produced in water. Water is the same everywhere, whether produced from +the ocean or from the flame of the candle. Where, then, is this water +which we get from a candle? It evidently comes, as to part of it, from +the candle; but is it within the candle beforehand? No! It is not in the +candle; and it is not in the air round about the candle, which is +necessary for its combustion. It is neither in one nor the other, but it +comes from their conjoint action, a part from the candle, a part from +the air. And this we have now to trace. + +If we decompose water we can obtain from it a gas. This is hydrogen--a +body classed amongst those things in chemistry which we call elements, +because we can get nothing else out of them. A candle is not an +elementary body, because we can get carbon out of it; we can get this +hydrogen out of it, or at least out of the water which it supplies. And +this gas has been so named hydrogen because it is that element which, in +association with another, generates water. + +Hydrogen gives rise to no substance that can become solid, either during +combustion or afterwards, as a product of its combustion. But when it +burns it produces water only; and if we take a cold glass and put it +over the flame, it becomes damp, and you have water produced immediately +in appreciable quantity, and nothing is produced by its combustion but +the same water which you have seen the flame of a candle produce. This +hydrogen is the only thing in Nature that furnishes water as the sole +product of combustion. + +Water can be decomposed by electricity, and then we find that its other +constituent is the gas oxygen in which, as can easily be shown, a candle +or a lamp burns much more brilliantly than it does in air, but produces +the same products as when it burns in air. We thus find that oxygen is +a constituent of the air, and by burning something in the air we can +remove the oxygen therefrom, leaving behind for our study the nitrogen, +which constitutes about four-fifths of the air, the oxygen accounting +for nearly all the rest. + +The other great product of the burning of a candle is carbonic acid--a +gas formed by the union of the carbon of the candle and the oxygen of +the air. Whenever carbon burns, whether in a candle or in a living +creature, it produces carbonic acid. + + +_IV.--Combustion and Respiration_ + +Now I must take you to a very interesting part of our subject--to the +relation between the combustion of a candle and that living kind of +combustion which goes on within us. In every one of us there is a living +process of combustion going on very similar to that of a candle. For it +is not merely true in a poetical sense--the relation of the life of man +to a taper. A candle will burn some four, five, six, or seven hours. +What, then, must be the daily amount of carbon going up into the air in +the way of carbonic acid? What a quantity of carbon must go from each of +us in respiration! A man in twenty-four hours converts as much as seven +ounces of carbon into carbonic acid; a milch cow will convert seventy +ounces, and a horse seventy-nine ounces, solely by the act of +respiration. That is, the horse in twenty-four hours burns seventy-nine +ounces of charcoal, or carbon, in his organs of respiration to supply +his natural warmth in that time. + +All the warm-blooded animals get their warmth in this way, by the +conversion of carbon; not in a free state, but in a state of +combination. And what an extraordinary notion this gives us of the +alterations going out in our atmosphere! As much as 5,000,000 pounds of +carbonic acid is formed by respiration in London alone in twenty-four +hours. And where does all this go? Up into the air. If the carbon had +been like lead or iron, which, in burning, produces a solid substance, +what would happen? Combustion would not go on. As charcoal burns, it +becomes a vapour and passes off into the atmosphere, which is the great +vehicle, the great carrier, for conveying it away to other places. Then, +what becomes of it? + +Wonderful is it to find that the change produced by respiration, which +seems so injurious to us, for we cannot breathe air twice over, is the +very life and support of plants and vegetables that grow upon the +surface of the earth. It is the same also under the surface in the great +bodies of water, for fishes and other animals respire upon the same +principle, though not exactly by contact with the open air. They respire +by the oxygen which is dissolved from the air by the water, and form +carbonic acid; and they all move about to produce the one great work of +making the animal and vegetable kingdoms subservient to each other. + +All the plants growing upon the surface of the earth absorb carbon. +These leaves are taking up their carbon from the atmosphere, to which we +have given it in the form of carbonic acid, and they are prospering. +Give them a pure air like ours, and they could not live in it; give them +carbon with other matters, and they live and rejoice. So are we made +dependent not merely upon our fellow-creatures, but upon our +fellow-existers, all Nature being tied by the laws that make one part +conduce to the good of the other. + + + + +AUGUSTE FOREL + +The Senses of Insects + + Auguste Forel, who in 1909 retired from the Chair of Morbid + Psychology in the University of Zuerich, was born on September 1, + 1848, and is one of the greatest students of the minds and senses + of the lower animals and mankind. Among his most famous works are + his "Hygiene of Nerves and Mind," his great treatise on the whole + problem of sex in human life, of which a cheap edition entitled + "Sexual Ethics" is published, his work on hypnotism, and his + numerous contributions to the psychology of insects. The chief + studies of this remarkable and illustrious student and thinker for + many decades past have been those of the senses and mental + faculties of insects. He has recorded the fact that his study of + the beehive led him to his present views as to the right + constitution of the state--views which may be described as + socialism with a difference. His work on insects has served the + study of human psychology, and is in itself the most important + contribution to insect psychology ever made by a single student. + Only within the last two years has the work of Forel, long famous + on the European Continent, begun to be known abroad. + + +_I.--Insect Activity and Instinct_ + +This subject is one of great interest, as much from the standpoint of +biology as from that of comparative psychology. The very peculiar +mechanism of instincts always has its starting-point in sensations. To +comprehend this mechanism it is essential to understand thoroughly the +organs of sense and their special functions. + +It is further necessary to study the co-ordination which exists between +the action of the different senses, and leads to their intimate +connection with the functions of the nerve-centres, that is to say, with +the specially instinctive intelligence of insects. The whole question +is, therefore, a chapter of comparative psychology, a chapter in which +it is necessary to take careful note of every factor, to place oneself, +so to speak, on a level with the mind of an insect, and, above all, to +avoid the anthropomorphic errors with which works upon the subject are +filled. + +At the same time the other extreme must equally be +avoided--"anthropophobia," which at all costs desires to see in every +living organism a "machine," forgetting that a "machine" which lives, +that is to say, which grows, takes in nutriment, and strikes a balance +between income and expenditure, which, in a word, continually +reconstructs itself, is not a "machine," but something entirely +different. In other words, it is necessary to steer clear of two +dangers. We must avoid (1) identifying the mind of an insect with our +own, but, above all, (2) imagining that we, with what knowledge we +possess, can reconstruct the mind by our chemical and physical laws. + +On the other hand, we have to recognise the fact that this mind, and the +sensory functions which put it on its guard, are derived, just as with +our human selves, from the primitive protoplasmic life. This life, so +far as it is specialised in the nervous system by nerve irritability and +its connections with the muscular system, is manifested under two +aspects. These may be likened to two branches of one trunk. + +(_a_) _Automatic_ or _instinctive_ activity. This, though perfected by +repetition, is definitely inherited. It is uncontrollable and constant +in effect, adapted to the circumstances of the special life of the race +in question. It is this curious instinctive adaptation--which is so +intelligent when it carries out its proper task, so stupid and incapable +when diverted to some other purpose--that has deceived so many +scientists and philosophers by its insidious analogy with humanly +constructed machines. + +But, automatic as it may appear, instinct is not invariable. In the +first place, it presents a racial evolution which of itself alone +already demonstrates a certain degree of plasticity from generation to +generation. It presents, further, individual variations which are more +distinct as it is less deeply fixed by heredity. Thus the divergent +instincts of two varieties, _e.g._, of insects, present more individual +variability and adaptability than do those instincts common to all +species of a genus. In short, if we carefully study the behaviour of +each individual of a species of insects with a developed brain (as has +been done by P. Huber, Lubbock, Wasmann, and myself, among others, for +bees, wasps, and ants), we are not long in finding noteworthy +differences, especially when we put the instinct under abnormal +conditions. We then force the nervous activity of these insects to +present a second and plastic aspect, which to a large extent has been +hidden from us under their enormously developed instinct. + +(_b_) The _plastic_ or _adaptive_ activity is by no means, as has been +so often suggested, a derivative of instinct. It is primitive. It is +even the fundamental condition of the evolution of life. The living +being is distinguished by its power of adaptation; even the amoeba is +plastic. But in order that one individual may adapt itself to a host of +conditions and possibilities, as is the case with the higher mammals and +especially with man, the brain requires an enormous quantity of nerve +elements. But this is not the case with the fixed and specialised +adaptation of instinct. + +In secondary automatism, or habit, which we observe in ourselves, it is +easy to study how this activity, derived from plastic activity, and ever +becoming more prompt, complex, and sure (technical habits), necessitates +less and less expenditure of nerve effort. It is very difficult to +understand how inherited instinct, hereditary automatism, could have +originated from the plastic activities of our ancestors. It seems as if +a very slow selection, among individuals best adapted in consequence of +fortunate parentage, might perhaps account for it. + +To sum up, every animal possesses two kinds of activity in varying +degrees, sometimes one, sometimes the other predominating. In the lowest +beings they are both rudimentary. In insects, special automatic activity +reaches the summit of development and predominance; in man, on the +contrary, with his great brain development, plastic activity is elevated +to an extraordinary height, above all by language, and before all by +written language, which substitutes graphic fixation for secondary +automatism, and allows the accumulation outside the brain of the +knowledge of past generations, thus serving his plastic activity, at +once the adapter and combiner of what the past has bequeathed to it. + +According to the families, _genera_, and species of insects, the +development of different senses varies extremely. We meet with most +striking contrasts, and contrasts which have not been sufficiently +noticed. Certain insects, dragon-flies, for instance, live almost +entirely by means of sight. Others are blind, or almost blind, and +subsist exclusively by smell and taste (insects inhabiting caves, most +working ants). Hearing is well developed in certain forms (crickets, +locusts), but most insects appear not to hear, or to hear with +difficulty. Despite their thick, chitinous skeleton, almost all insects +have extremely sensitive touch, especially in the antennae, but not +confined thereto. + +It is absolutely necessary to bear in mind the mental faculties of +insects in order to judge with a fair degree of accuracy how they use +their senses. We shall return to that point when summing up. + + +_II.--The Vision of Insects_ + +In vision we are dealing with a certain definite stimulus--light, with +its two modifications, colour and motion. Insects have two sets of +organs for vision, the faceted eye and the so-called simple eye, or +ocellus. These have been historically derived from one and the same +organ. In order to exercise the function of sight the facets need a +greater pencil of light rays by night than by day. To obtain the same +result we dilate the pupil. But nocturnal insects are dazzled by the +light of day, and diurnal insects cannot see by night, for neither +possess the faculty of accommodation. Insects are specially able to +perceive motion, but there are only very few insects that can see +distinctly. + +For example, I watched one day a wasp chasing a fly on the wall of a +veranda, as is the habit of this insect at the end of summer and in the +autumn. She dashed violently in flight at the flies sitting on the wall, +which mostly escaped. She continued her pursuit with remarkable +pertinacity, and succeeded on several occasions in catching a fly, which +she killed, mutilated, and bore away to her nest. Each time she quickly +returned to continue the hunt. + +In one spot of the wall was stuck a black nail, which was just the size +of a fly, and I saw the wasp very frequently deceived by this nail, upon +which she sprang, leaving it as soon as she perceived her error on +touching it. Nevertheless, she made the same mistake with the nail +shortly after. I have often made similar observations. We may certainly +conclude that the wasp saw something of the size of a fly, but without +distinguishing the details; therefore she saw it indistinctly. Evidently +a wasp does not only perceive motion; she also distinguishes the size of +objects. When I put dead flies on a table to be carried off by another +wasp, she took them, one after another, as well as spiders and other +insects of but little different size placed by their side. On the other +hand, she took no notice of insects much larger or much smaller put +among the flies. + +Most entomologists have observed with what ingenuity and sureness +dragon-flies distinguish, follow, and catch the smallest insects on the +wing. Of all insects, they have the best sight. Their enormous convex +eyes have the greatest number of facets. Their number has been estimated +at 12,000, and even at 17,000. Their aerial chases resemble those of the +swallows. By trying to catch them at the edge of a large pond, one can +easily convince oneself that the dragon-flies amuse themselves by making +sport of the hunter; they will always allow one to approach just near +enough to miss catching them. It can be seen to what degree they are +able to measure the distance and reach of their enemy. + +It is an absolute fact that dragon-flies, unless it is cold or in the +evening, always manage to fly at just that distance at which the student +cannot touch them; and they see perfectly well whether one is armed with +a net or has nothing but his hands; one might even say that they measure +the length of the handle of the net, for the possession of a long handle +is no advantage. They fly just out of reach of one's instrument, +whatever trouble one may give oneself by hiding it from them and +suddenly lunging as they fly off. Whoever watches butterflies and flies +will soon see that these insects also can measure the distance of such +objects as are not far from them. The males and females of bees and ants +distinguish one another on the wing. It is rare for an individual to +lose sight of the swarm or to miss what it pursues flying. It has been +proved that the sense of smell has nothing to do with this matter. Thus +insects, though without any power of accommodation for light or +distance, are able to perceive objects at different distances. + +It is known that many insects will blindly fly and dash against a lamp +at night, until they burn themselves. It has often been wrongly thought +that they are fascinated. We ought first to remember that natural +lights, concentrated at one point like our artificial lights, are +extremely rare in Nature. The light of day, which is the light of wild +animals, is not concentrated at one point. Insects, when they are in +darkness--underground, beneath bark or leaves--are accustomed to reach +the open air, where the light is everywhere diffused, by directing +themselves towards the luminous point. At night, when they fly towards a +lamp, they are evidently deceived, and their small brains cannot +comprehend the novelty of this light concentrated at one spot. +Consequently, their fruitless efforts are again and again renewed +against the flame, and the poor innocents end by burning themselves. +Several domestic insects, which have become little by little adapted to +artificial light in the course of generations, no longer allow +themselves to be deceived thereby. This is the case with house-flies. + +Bees distinguish all colours, and seldom confound any but blue and +green; while wasps scarcely react to differences of colour, but note +better the shape of an object, and note, for instance, where the place +of honey is; so that a change of colour on the disc whereon the honey is +placed hardly upsets them. Further, wasps have a better sense of smell +than bees. + +The chief discovery regarding the vision of insects made in the last +thirty years is that of Lubbock, who proved that ants perceive the +ultra-violet rays of the spectrum, which we are unable, or almost +unable, to perceive. + +It has lately been proved also that many insects appreciate light by the +skin. + +They do not see as clearly as we do; but when they possess +well-developed compound eyes they appreciate size, and more or less +distinctly the contours of objects. + +Ants have a great faculty for recognition, which probably testifies to +their vision and visual memory. Lubbock observed ants which actually +recognised each other after more than a year of separation. + + +_III.--Smell, Taste, Hearing, Pain_ + +Smell is very important in insects. It is difficult for us to judge of, +since man is of all the vertebrates except the whales, perhaps, the one +in which this sense is most rudimentary. We can evidently, therefore, +form only a feeble idea of the world of knowledge imparted by a smell to +a dog, a mole, a hedgehog, or an insect. The instruments of smell are +the antennae. A poor ant without antennae is as lost as a blind man who is +also deaf and dumb. This appears from its complete social inactivity, +its isolation, its incapacity to guide itself and to find its food. It +can, therefore, be boldly supposed that the antennae and their power of +smell, as much on contact as at a distance, constitute the social sense +of ants, the sense which allows them to recognise one another, to tend +to their larvae, and mutually help one another, and also the sense which +awakens their greedy appetites, their violent hatred for every being +foreign to the colony, the sense which principally guides them--a little +helped by vision, especially in certain species--in the long and patient +travels which they have to undertake, which makes them find their way +back, find their plant-lice, and all their other means of subsistence. + +As the philosopher Herbert Spencer has well pointed out, the visceral +sensations of man, and those internal senses which, like smell, can only +make an impression of one kind as regards space--two simultaneous odours +can only be appreciated by us as a mixture--are precisely those by which +we can gain little or no information relative to space. Our vision, on +the contrary, which localises the rays from various distant points of +space on various distinct points of our retina at the same time, is our +most relational sense, that which gives us the most vast ideas of space. + +But the antennae of insects are an olfactory organ turned inside out, +prominent in space, and, further, very mobile. This allows us to suppose +that the sense of smell may be much more relational than ours, that the +sensations thence derived give them ideas of space and of direction +which may be qualitatively different from ours. + +Taste exists in insects, and has been very widely written on, but +somewhat inconclusively. The organs of taste probably are to be found in +the jaws and at the base of the tongue. This sense can be observed in +ants, bees, and wasps; and everyone has seen how caterpillars especially +recognise by taste the plants which suit them. + +Much has been written on the hearing of insects; but, in my judgment, +only crickets and several other insects of that class appear to perceive +sounds. Erroneous views have been due to confusing hearing with +mechanical vibrations. + +We must not forget that the specialisation of the organ of hearing has +reached in man a delicacy of detail which is evidently not found again +in lower vertebrates. + +Pain is much less developed in insects than in warm-blooded vertebrates. +Otherwise, one could not see either an ant, with its abdomen or antennae +cut off, gorge itself with honey; or a humble-bee, in which the antennae +and all the front of the head had been removed, go to find and pillage +flowers; or a spider, the foot of which had been broken, feed +immediately on this, its own foot, as I myself have seen; or, finally, a +caterpillar, wounded at the "tail" end, devour itself, beginning behind, +as I have observed more than once. + + +_IV.--Insect Reason and Passions_ + +Insects reason, and the most intelligent among them, the social +hymenoptera, especially the wasps and ants, even reason much more than +one is tempted to believe when one observes the regularly recurring +mechanism of their instincts. To observe and understand these +reasonings well, it is necessary to mislead their instinct. Further, one +may remark little bursts of plastic judgment, of combinations--extremely +limited, it is true--which, in forcing them an instant from the beaten +track of their automatism, help them to overcome difficulties, and to +decide between two dangers. From the point of view of instinct and +intelligence, or rather of reason, there are not, therefore, absolute +contrasts between the insect, the mammal, and the man. + +Finally, insects have passions which are more or less bound up with +their instincts. And these passions vary enormously, according to the +species. I have noted the following passions or traits of character +among ants: choler, hatred, devotion, activity, perseverance, and +gluttony. I have added thereto the discouragement which is sometimes +shown in a striking manner at the time of a defeat, and which can become +real despair; the fear which is shown among ants when they are alone, +while it disappears when they are numerous. I can add further the +momentary temerity whereby certain ants, knowing the enemy to be +weakened and discouraged, hurl themselves alone in the midst of the +black masses of enemies larger than themselves, hustling them without +taking the least further precaution. + +When we study the manners of an insect, it is necessary for us to take +account of its mental faculties as well as of its sense organs. +Intelligent insects make better use of their senses, especially by +combining them in various ways. It is possible to study such insects in +their homes in a more varied and more complete manner, allowing greater +accuracy of observations. + + + + +GALILEO + +Dialogues on the System of the World + + Galileo Galilei, famous as an astronomer and as an experimental + physicist, was born at Pisa, in Italy, Feb. 18, 1564. His talents + were most multifarious and remarkable; but his mathematical and + mechanical genius was dominant from the first. As a child he + constructed mechanical toys, and as a young man he made one of his + most important discoveries, which was that of the pendulum as an + agent in the measurement of time, and invented the hydrostatic + balance, by which the specific gravity of solid bodies might be + ascertained. At the age of 24 a learned treatise on the centre of + gravity of solids led to a lectureship at Pisa University. Driven + from Pisa by the enmity of Aristotelians, he went to Padua + University, where he invented a kind of thermometer, a proportional + compass, a microscope, and a telescope. The last invention bore + fruit in astronomical discoveries, and in 1610 he discovered four + of the moons of Jupiter. His promulgation of the Copernican + doctrine led to renewed attacks by the Aristotelians, and to + censure by the Inquisition. (See Religion, vol. xiii.) + Notwithstanding this censure, he published in 1632 his "Dialogues + on the System of the World." The interlocutors in the "Dialogues," + with the exception of Salviatus, who expounds the views of the + author himself, represent two of Galileo's early friends. For the + "Dialogues" he was sentenced by the Inquisition to incarceration at + its pleasure, and enjoined to recite penitential psalms once a week + for three years. His life thereafter was full of sorrow, and in + 1637 blindness added to his woes; but the fire of his genius still + burnt on till his death on January 8, 1642. + + +_Does the Earth Move_ + +SALVIATUS: Now, let Simplicius propound those doubts which dissuade him +from believing that the earth may move, as the other planets, round a +fixed centre. + +SIMPLICIUS: The first and greatest difficulty is that it is impossible +both to be in a centre and to be far from it. If the earth move in a +circle it cannot remain in the centre of the zodiac; but Aristotle, +Ptolemy and others have proved that it is in the centre of the zodiac. + +SALVIATUS: There is no question that the earth cannot be in the centre +of a circle round whose circumference it moves. But tell me what centre +do you mean? + +SIMPLICIUS: I mean the centre of the universe, of the whole world, of +the starry sphere. + +SALVIATUS: No one has ever proved that the universe is finite and +figurative; but granting that it is finite and spherical, and has +therefore a centre, we have still to give reasons why we should believe +that the earth is at its centre. + +SIMPLICIUS: Aristotle has proved in a hundred ways that the universe is +finite and spherical. + +SALVIATUS: Aristotle's proof that the universe was finite and spherical +was derived essentially from the consideration that it moved; and seeing +that centre and figure were inferred by Aristotle from its mobility, it +will be reasonable if we endeavour to find from the circular motions of +mundane bodies the centre's proper place. Aristotle himself came to the +conclusion that all the celestial spheres revolve round the earth, which +is placed at the centre of the universe. But tell me, Simplicius, +supposing Aristotle found that one of the two propositions must be +false, and that either the celestial spheres do not revolve or that the +earth is not the centre round which they revolve, which proposition +would he prefer to give up? + +SIMPLICIUS: I believe that the Peripatetics---- + +SALVIATUS: I do not ask the Peripatetics, I ask Aristotle. As for the +Peripatetics, they, as humble vassals of Aristotle, would deny all the +experiments and all the observations in the world; nay, would also +refuse to see them, and would say that the universe is as Aristotle +writeth, and not as Nature will have it; for, deprived of the shield of +his authority, with what do you think they would appear in the field? +Tell me, therefore, what Aristotle himself would do. + +SIMPLICIUS: To tell you the truth, I do not know how to decide which is +the lesser inconvenience. + +SALVIATUS: Seeing you do not know, let us examine which would be the +more rational choice, and let us assume that Aristotle would have chosen +so. Granting with Aristotle that the universe has a spherical figure and +moveth circularly round a centre, it is reasonable to believe that the +starry orbs move round the centre of the universe or round some separate +centre? + +SIMPLICIUS: I would say that it were much more reasonable to believe +that they move with the universe round the centre of the universe. + +SALVIATUS: But they move round the sun and not round the earth; +therefore the sun and not the earth is the centre of the universe. + +SIMPLICIUS: Whence, then, do you argue that it is the sun and not the +earth that is the centre of the planetary revolutions? + +SALVIATUS: I infer that the earth is not the centre of the planetary +revolutions because the planets are at different times at very different +distances from the earth. For instance, Venus, when it is farthest off, +is six times more remote from us than when it is nearest, and Mars rises +almost eight times as high at one time as at another. + +SIMPLICIUS: And what are the signs that the planets revolve round the +sun as centre? + +SALVIATUS: We find that the three superior planets--Mars, Jupiter, and +Saturn--are always nearest to the earth when they are in opposition to +the sun, and always farthest off when they are in conjunction; and so +great is this approximation and recession that Mars, when near, appears +very nearly sixty times greater than when remote. Venus and Mercury also +certainly revolve round the sun, since they never move far from it, and +appear now above and now below it. + +SAGREDUS: I expect that more wonderful things depend on the annual +revolution than upon the diurnal rotation of the earth. + +SALVIATUS: YOU do not err therein. The effect of the diurnal rotation of +the earth is to make the universe seem to rotate in the opposite +direction; but the annual motion complicates the particular motions of +all the planets. But to return to my proposition. I affirm that the +centre of the celestial convolutions of the five planets--Saturn, +Jupiter, Mars, Venus, and Mercury, and likewise of the earth--is the +sun. + +As for the moon, it goes round the earth, and yet does not cease to go +round the sun with the earth. It being true, then, that the five planets +do move about the sun as a centre, rest seems with so much more reason +to belong to the said sun than to the earth, inasmuch as in a movable +sphere it is more reasonable that the centre stand still than any place +remote from the centre. + +To the earth, therefore, may a yearly revolution be assigned, leaving +the sun at rest. And if that be so, it follows that the diurnal motion +likewise belongs to the earth; for if the sun stood still and the earth +did not rotate, the year would consist of six months of day and six +months of night. You may consider, likewise, how, in conformity with +this scheme, the precipitate motion of twenty-four hours is taken away +from the universe; and how the fixed stars, which are so many suns, are +made, like our sun, to enjoy perpetual rest. + +SAGREDUS: The scheme is simple and satisfactory; but, tell me, how is it +that Pythagoras and Copernicus, who first brought it forward, could make +so few converts? + +SALVIATUS: If you know what frivolous reasons serve to make the vulgar, +contumacious and indisposed to hearken, you would not wonder at the +paucity of converts. The number of thick skulls is infinite, and we need +neither record their follies nor endeavour to interest them in subtle +and sublime ideas. No demonstrations can enlighten stupid brains. + +My wonder, Sagredus, is different from yours. You wonder that so few are +believers in the Pythagorean hypothesis; I wonder that there are any to +embrace it. Nor can I sufficiently admire the super-eminence of those +men's wits that have received and held it to be true, and with the +sprightliness of their judgments have offered such violence to their +senses that they have been able to prefer that which their reason +asserted to that which sensible experience manifested. I cannot find any +bounds for my admiration how that reason was able, in Aristarchus and +Copernicus, to commit such a rape upon their senses, as in despite +thereof to make herself mistress of their credulity. + +SAGREDUS: Will there still be strong opposition to the Copernican +system? + +SALVIATUS: Undoubtedly; for there are evident and sensible facts to +oppose it, requiring a sense more sublime than the common and vulgar +senses to assist reason. + +SAGREDUS: Let us, then, join battle with those antagonistic facts. + +SALVIATUS: I am ready. In the first place, Mars himself charges hotly +against the truth of the Copernican system. According to the Copernican +system, that planet should appear sixty times as large when at its +nearest as when at its farthest; but this diversity of magnitude is not +to be seen. The same difficulty is seen in the case of Venus. Further, +if Venus be dark, and shine only with reflected light, like the moon, it +should show lunar phases; but these do not appear. + +Further, again, the moon prevents the whole order of the Copernican +system by revolving round the earth instead of round the sun. And there +are other serious and curious difficulties admitted by Copernicus +himself. But even the three great difficulties I have named are not +real. As a matter of fact, Mars and Venus do vary in magnitude as +required by theory, and Venus does change its shape exactly like the +moon. + +SAGREDUS: But how came this to be concealed from Copernicus and revealed +to you? + + + + +SIR FRANCIS GALTON + +Essays in Eugenics + + Sir Francis Galton, born at Birmingham, England, in 1822, was a + grandson of Dr. Erasmus Darwin. He graduated from Trinity College, + Cambridge, in 1844. Galton travelled in the north of Africa, on the + White Nile and in the western portion of South Africa between 1844 + and 1850. Like his immortal cousin, Charles Darwin, Sir Francis + Galton is a striking instance of a man of great and splendid + inheritance, who, also inheriting wealth, devotes it and his powers + to the cause of humanity. He published several books on heredity, + the first of which was "Hereditary Genius." The next "Inquiries + into Human Faculty," which was followed by "Natural Inheritance." + The "Essays in Eugenics" include all the most recent work of Sir + Francis Galton since his return to the subject of eugenics in 1901. + This volume has just been published by the Eugenics Education + Society, of which Sir Francis Galton is the honorary president. As + epitomised for this work, the "Essays" have been made to include a + still later study by the author, which will be included in future + editions of the book. The epitome has been prepared by special + permission of the Eugenics Education Society, and those responsible + hope that it will serve in some measure to neutralise the + outrageous, gross, and often wilful misrepresentations of eugenics + of which many popular writers are guilty. + + +_I.--The Aims and Methods of Eugenics_ + +The following essays help to show something of the progress of eugenics +during the last few years, and to explain my own views upon its aims and +methods, which often have been, and still sometimes are, absurdly +misrepresented. The practice of eugenics has already obtained a +considerable hold on popular estimation, and is steadily acquiring the +status of a practical question, and not that of a mere vision in Utopia. + +The power by which eugenic reform must chiefly be effected is that of +public opinion, which is amply strong enough for that purpose whenever +it shall be roused. Public opinion has done as much as this on many past +occasions and in various countries, of which much evidence is given in +the essay on restrictions in marriage. It is now ordering our acts more +intimately than we are apt to suspect, because the dictates of public +opinion become so thoroughly assimilated that they seem to be the +original and individual to those who are guided by them. By comparing +the current ideas at widely different epochs and under widely different +civilisations, we are able to ascertain what part of our convictions is +really innate and permanent, and what part has been acquired and is +transient. + +It is, above all things, needful for the successful progress of eugenics +that its advocates should move discreetly and claim no more efficacy on +its behalf than the future will justify; otherwise a reaction will be +justified. A great deal of investigation is still needed to show the +limit of practical eugenics, yet enough has been already determined to +justify large efforts being made to instruct the public in an +authoritative way, with the results hitherto obtained by sound +reasoning, applied to the undoubted facts of social experience. + +The word "eugenics" was coined and used by me in my book "Human +Faculty," published as long ago as 1883. In it I emphasised the +essential brotherhood of mankind, heredity being to my mind a very real +thing; also the belief that we are born to act, and not to wait for help +like able-bodied idlers, whining for doles. Individuals appear to me as +finite detachments from an infinite ocean of being, temporarily endowed +with executive powers. This is the only answer I can give to myself in +reply to the perpetually recurring questions of "why? whence? and +whither?" The immediate "whither?" does not seem wholly dark, as some +little information may be gleaned concerning the direction in which +Nature, so far as we know of it, is now moving--namely, towards the +evolution of mind, body, and character in increasing energy and +co-adaptation. + +The ideas have long held my fancy that we men may be the chief, and +perhaps the only executives on earth; that we are detached on active +service with, it may be only illusory, powers of free-will. Also that we +are in some way accountable for our success or failure to further +certain obscure ends, to be guessed as best we can; that though our +instructions are obscure they are sufficiently clear to justify our +interference with the pitiless course of Nature whenever it seems +possible to attain the goal towards which it moves by gentler and +kindlier ways. + +There are many questions which must be studied if we are to be guided +aright towards the possible improvement of mankind under the existing +conditions of law and sentiment. We must study human variety, and the +distribution of qualities in a nation. We must compare the +classification of a population according to social status with the +classification which we would make purely in terms of natural quality. +We must study with the utmost care the descent of qualities in a +population, and the consequences of that marked tendency to marriage +within the class which distinguishes all classes. Something is to be +learnt from the results of examinations in universities and colleges. + +It is desirable to study the degree of correspondence that may exist +between promise in youth, as shown in examinations, and subsequent +performance. Let me add that I think the neglect of this inquiry by the +vast army of highly educated persons who are connected with the present +huge system of competitive examination to be gross and unpardonable. +Until this problem is solved we cannot possibly estimate the value of +the present elaborate system of examinations. + + +_II.--Restrictions in Marriage_ + +It is necessary to meet an objection that has been repeatedly urged +against the possible adoption of any system of eugenics, namely, that +human nature would never brook interference with the freedom of +marriage. But the question is how far have marriage restrictions proved +effective when sanctified by the religion of the time, by custom, and by +law. I appeal from armchair criticism to historical facts. It will be +found that, with scant exceptions, marriage customs are based on social +expediency and not on natural instincts. This we learn when we study the +fact of monogamy, and the severe prohibition of polygamy, in many times +and places, due not to any natural instinct against the practice, but to +consideration of the social well-being. We find the same when we study +endogamy, exogamy, Australian marriages, and the control of marriage by +taboo. + +The institution of marriage, as now sanctified by religion and +safeguarded by law in the more highly civilised nations, may not be +ideally perfect, nor may it be universally accepted in future times, but +it is the best that has hitherto been devised for the parties primarily +concerned, for their children, for home life, and for society. The +degree of kinship within which marriage is prohibited is, with one +exception, quite in accordance with modern sentiment, the exception +being the disallowal of marriage with the sister of a deceased wife, the +propriety of which is greatly disputed and need not be discussed here. +The marriage of a brother and sister would excite a feeling of loathing +among us that seems implanted by nature, but which, further inquiry will +show, has mainly arisen from tradition and custom. + +The evidence proves that there is no instinctive repugnance felt +universally by man to marriage within the prohibited degrees, but that +its present strength is mainly due to what I may call immaterial +considerations. It is quite conceivable that a non-eugenic marriage +should hereafter excite no less loathing than that of a brother and +sister would do now. + +The dictates of religion in respect to the opposite duties of leading +celibate lives, and of continuing families, have been contradictory. In +many nations it is and has been considered a disgrace to bear no +children, and in other nations celibacy has been raised to the rank of a +virtue of the highest order. During the fifty or so generations that +have elapsed since the establishment of Christianity, the nunneries and +monasteries, and the celibate lives of Catholic priests, have had vast +social effects, how far for good and how far for evil need not be +discussed here. The point I wish to enforce is the potency, not only of +the religious sense in aiding or deterring marriage, but more especially +the influence and authority of ministers of religion in enforcing +celibacy. They have notoriously used it when aid has been invoked by +members of the family on grounds that are not religious at all, but +merely of family expediency. Thus at some times and in some Christian +nations, every girl who did not marry while still young was practically +compelled to enter a nunnery, from which escape was afterwards +impossible. + +It is easy to let the imagination run wild on the supposition of a +whole-hearted acceptance of eugenics as a national religion; that is, of +the thorough conviction by a nation that no worthier object exists for +man than the improvement of his own race, and when efforts as great as +those by which nunneries and monasteries were endowed and maintained +should be directed to fulfil an opposite purpose. I will not enter +further into this. Suffice it to say, that the history of conventual +life affords abundant evidence on a very large scale of the power of +religious authority in directing and withstanding the tendencies of +human nature towards freedom in marriage. + +Seven different forms of marriage restriction may be cited to show what +is possible. They are monogamy, endogamy, exogamy, Australian marriages, +taboo, prohibited degrees, and celibacy. It can be shown under each of +these heads how powerful are the various combinations of immaterial +motives upon marriage selection, how they may all become hallowed by +religion, accepted as custom, and enforced by law. Persons who are born +under their various rules live under them without any objection. They +are unconscious of their restrictions, as we are unaware of the tension +of the atmosphere. The subservience of civilised races to their several +religious superstitions, customs, authority, and the rest, is frequently +as abject as that of barbarians. + +The same classes of motives that direct other races direct ours; so a +knowledge of their customs helps us to realise the wide range of what we +may ourselves hereafter adopt, for reasons as satisfactory to us in +those future times, as theirs are or were to them at the time when they +prevailed. + + +_III.--Eugenic Qualities of Primary Importance_ + +The following is offered as a contribution to the art of justly +appraising the eugenic values of different qualities. It may fairly be +assumed that the presence of certain inborn traits is requisite before a +claim to eugenic rank can be justified, because these qualities are +needed to bring out the full values of such special faculties as broadly +distinguish philosophers, artists, financiers, soldiers, and other +representative classes. The method adopted for discovering the qualities +in question is to consider groups of individuals, and to compare the +qualities that distinguish such groups as flourish or prosper from +others of the same kind that decline or decay. This method has the +advantage of giving results more free from the possibility of bias than +those derived from examples of individual cases. + +In what follows I shall use the word "community" in its widest sense, +as including any group of persons who are connected by a common +interest--families, schools, clubs, sects, municipalities, nations, and +all intermediate social units. Whatever qualities increase the +prosperity of most or every one of these, will, as I hold, deserve a +place in the first rank of eugenic importance. + +Most of us have experience, either by direct observation or through +historical reading, of the working of several communities, and are +capable of forming a correct picture in our minds of the salient +characteristics of those that, on the one hand, are eminently +prosperous, and of those that, on the other hand, are as eminently +decadent. I have little doubt that the reader will agree with me that +the members of prospering communities are, as a rule, conspicuously +strenuous, and that those of decaying or decadent ones are conspicuously +slack. A prosperous community is distinguished by the alertness of its +members, by their busy occupations, by their taking pleasure in their +work, by their doing it thoroughly, and by an honest pride in their +community as a whole. The members of a decaying community are, for the +most part, languid and indolent; their very gestures are dawdling and +slouching, the opposite of smart. They shirk work when they can do so, +and scamp what they undertake. A prosperous community is remarkable for +the variety of the solid interests in which some or other of its members +are eagerly engaged, but the questions that agitate a decadent community +are for the most part of a frivolous order. + +Prosperous communities are also notable for enjoyment of life; for +though their members must work hard in order to procure the necessary +luxuries of an advanced civilisation, they are endowed with so large a +store of energy that, when their daily toil is over, enough of it +remains unexpended to allow them to pursue their special hobbies during +the remainder of the day. In a decadent community the men tire easily, +and soon sink into drudgery; there is consequently much languor among +them, and little enjoyment of life. + +I have studied the causes of civic prosperity in various directions and +from many points of view, and the conclusion at which I have arrived is +emphatic, namely, that chief among those causes is a large capacity for +labour--mental, bodily, or both--combined with eagerness for work. The +course of evolution in animals shows that this view is correct in +general. The huge lizards, incapable of rapid action, unless it be brief +in duration and associated with long terms of repose, have been +supplanted by birds and mammals possessed of powers of long endurance. +These latter are so constituted as to require work, becoming restless +and suffering in health when precluded from exertion. + +We must not, however, overlook the fact that the influence of +circumstance on a community is a powerful factor in raising its tone. A +cause that catches the popular feeling will often rouse a potentially +capable nation from apathy into action. A good officer, backed by +adequate supplies of food and with funds for the regular payment of his +troops, will change a regiment even of ill-developed louts and hooligans +into a fairly smart and well-disciplined corps. But with better material +as a foundation, the influence of a favourable environment is +correspondingly increased, and is less liable to impairment whenever the +environment changes and becomes less propitious. Hence, it follows that +a sound mind and body, enlightened, I should add, with an intelligence +above the average, and combined with a natural capacity and zeal for +work, are essential elements in eugenics. For however famous a man may +become in other respects, he cannot, I think, be justly termed eugenic +if deficient in the qualities I have just named. + +Eugenists justly claim to be true philanthropists, or lovers of mankind, +and should bestir themselves in their special province as eagerly as +the philanthropists, in the current and very restricted meaning of that +word, have done in theirs. They should interest themselves in such +families of civic worth as they come across, especially in those that +are large, making friends both with the parents and the children, and +showing themselves disposed to help to a reasonable degree, as +opportunity may offer, whenever help is really needful. They should +compare their own notes with those of others who are similarly engaged. +They should regard such families as an eager horticulturist regards beds +of seedlings of some rare variety of plant, but with an enthusiasm of a +far more patriotic kind. For, since it has been shown that about 10 per +cent. of the individuals born in one generation provide half the next +generation, large families that are also eugenic may prove of primary +importance to the nation and become its most valuable asset. + + +_IV.--Practical Eugenics_ + +The following are some views of my own relating to that large province +of eugenics which is concerned with favouring the families of those who +are exceptionally fit for citizenship. Consequently, little or nothing +will here be said relating to what has been well termed by Dr. Saleeby +"negative" eugenics, namely, the hindrance of the marriages and the +production of offspring by the exceptionally unfit. The latter is +unquestionably the more pressing subject, but it will soon be forced on +the attention of the legislature by the recent report of the Royal +Commission on the Feeble-minded. + +Whatever scheme of action is proposed for adoption must be neither +Utopian nor extravagant, but accordant throughout with British sentiment +and practice. + +By "worth" I mean the civic worthiness, or the value to the state, of a +person. Speaking only for myself, if I had to classify persons according +to worth, I should consider each of them under the three heads of +physique, ability and character, subject to the provision that +inferiority in any one of the three should outweigh superiority in the +other two. I rank physique first, because it is not only very valuable +in itself and allied to many other good qualities, but has the +additional merit of being easily rated. Ability I place second on +similar grounds, and character third, though in real importance it +stands first of all. + +The power of social opinion is apt to be underrated rather than +overrated. Like the atmosphere which we breathe and in which we move, +social opinion operates powerfully without our being conscious of its +weight. Everyone knows that governments, manners, and beliefs which were +thought to be right, decorous, and true at one period have been judged +wrong, indecorous, and false at another; and that views which we have +heard expressed by those in authority over us in early life tend to +become axiomatic and unchangeable in mature life. + +In circumscribed communities especially, social approval and disapproval +exert a potent force. Is it, then, I ask, too much to expect that when a +public opinion in favour of eugenics has once taken sure hold of such +communities, the result will be manifested in sundry and very effective +modes of action which are as yet untried? + +Speaking for myself only, I look forward to local eugenic action in +numerous directions, of which I will now specify one. It is the +accumulation of considerable funds to start young couples of "worthy" +qualities in their married life, and to assist them and their families +at critical times. The charitable gifts to those who are the reverse of +"worthy" are enormous in amount. I am not prepared to say how much of +this is judiciously spent, or in what ways, but merely quote the fact to +justify the inference that many persons who are willing to give freely +at the prompting of a sentiment based upon compassion might be +persuaded to give largely also in response to the more virile desire of +promoting the natural gifts and the national efficiency of future +generations. + + +_V.--Eugenics as a Factor in Religion_ + +Eugenics strengthen the sense of social duty in so many important +particulars that the conclusions derived from its study ought to find a +welcome home in every tolerant religion. It promotes a far-sighted +philanthropy, the acceptance of parentage as a serious responsibility, +and a higher conception of patriotism. The creed of eugenics is founded +upon the idea of evolution; not on a passive form of it, but on one that +can, to some extent, direct its own course. + +Purely passive, or what may be styled mechanical evolution displays the +awe-inspiring spectacle of a vast eddy of organic turmoil, originating +we know not how, and travelling we know not whither. It forms a +continuous whole, but it is moulded by blind and wasteful +processes--namely, by an extravagant production of raw material and the +ruthless rejection of all that is superfluous, through the blundering +steps of trial and error. + +The condition at each successive moment of this huge system, as it +issues from the already quiet past and is about to invade the still +undisturbed future, is one of violent internal commotion. Its elements +are in constant flux and change. + +Evolution is in any case a grand phantasmagoria, but it assumes an +infinitely more interesting aspect under the knowledge that the +intelligent action of the human will is, in some small measure, capable +of guiding its course. Man has the power of doing this largely so far as +the evolution of humanity is concerned; he has already affected the +quality and distribution of organic life so widely that the changes on +the surface of the earth, merely through his disforestings and +agriculture, would be recognisable from a distance as great as that of +the moon. + +As regards the practical side of eugenics, we need not linger to reopen +the unending argument whether man possesses any creative power of will +at all, or whether his will is not also predetermined by blind forces or +by intelligent agencies behind the veil, and whether the belief that man +can act independently is more than a mere illusion. + +Eugenic belief extends the function of philanthropy to future +generations; it renders its action more pervading than hitherto, by +dealing with families and societies in their entirety, and it enforces +the importance of the marriage covenant by directing serious attention +to the probable quality of the future offspring. It sternly forbids all +forms of sentimental charity that are harmful to the race, while it +eagerly seeks opportunity for acts of personal kindness. It strongly +encourages love and interest in family and race. In brief, eugenics is a +virile creed, full of hopefulness, and appealing to many of the noblest +feelings of our nature. + + + + +ERNST HAECKEL + +The Evolution of Man + + Ernst Haeckel, who was born in Potsdam, Germany, Feb. 16, 1834, + descends from a long line of lawyers and politicians. To his + father's annoyance, he turned to science, and graduated in + medicine. After a long tour in Italy in 1859, during which he + wavered between art and science, he decided for zoology, and made a + masterly study of a little-known group of sea-animalcules, the + Radiolaria. In 1861 he began to teach zoology at Jena University. + Darwin's "Origin of Species" had just been translated into German, + and he took up the defence of Darwinism against almost the whole of + his colleagues. His first large work on evolution, "General + Morphology," was published in 1866. He has since published + forty-two distinct works. He is not only a master of zoology, but + has a good command of botany and embryology. Haeckel's "Evolution + of Man" (Anthropogenie), is generally accepted as being his most + important production. Published in 1874, at a time when the theory + of natural evolution had few supporters in Germany, the work was + hailed with a storm of controversy, one celebrated critic declaring + that it was a blot on the escutcheon of Germany. From the hands of + English scientists, however, the treatise received a warm welcome. + Darwin said he would probably never have written his "Descent of + Man" had Haeckel published his work earlier. + + +_I.--The Science of Man_ + +The natural history of mankind, or anthropology, must always excite the +most lively interest, and no part of the science is more attractive than +that which deals with the question of man's origin. In order to study +this with full profit, we must combine the results of two sciences, +ontogeny (or embryology) and phylogeny (the science of evolution). We do +this because we have now discovered that the forms through which the +embryo passes in its development correspond roughly to the series of +forms in its ancestral development. The correspondence is by no means +complete or precise, since the embryonic life itself has been modified +in the course of time; but the general law is now very widely accepted. +I have called it "the biogenetic law," and will constantly appeal to it +in the course of this study. + +It is only in recent times that the two sciences have advanced +sufficiently to reveal the correspondence of the two series of forms. +Aristotle provided a good foundation for embryology, and made some +interesting discoveries, but no progress was made in the science for +2,000 years after him. Then the Reformation brought some liberty of +research, and in the seventeenth century several works were written on +embryology. + +For more than a hundred years the science was still hampered by the lack +of good microscopes. It was generally believed that all the organs of +the body existed, packed in a tiny point of space, in the germ. About +the middle of the eighteenth century, Caspar Friedrich Wolff discovered +the true development; but his work was ignored, and it was only fifty +years later that modern embryology began to work on the right line. K.E. +von Baer made it clear that the fertilised ovum divides into a group of +cells, and that the various organs of the body are developed from these +layers of cells, in the way I shall presently describe. + +The science of phylogeny, or, as it is popularly called, the evolution +of species, had an equally slow growth. On the ground of the Mosaic +narrative, no less than in view of the actual appearance of the living +world, the great naturalist Linne (1735) set up the dogma of the +unchangeability of species. Even when quite different remains of animals +were discovered by the advancing science of geology, they were forced +into the existing narrow framework of science by Cuvier. Sir Charles +Lyell completely undid the fallacious work of Cuvier, but in the +meantime the zoologists themselves were moving toward the doctrine of +evolution. + +Jean Lamarck made the first systematic attempt to expound the theory in +his "Zoological Philosophy" (1809). He suggested that animals modified +their organs by use or disuse, and that the effect of this was +inherited. In the course of time these inherited modifications reached +such a pitch that the organism fell into a new "species." Goethe also +made some remarkable contributions to the science of evolution. But it +was reserved for Charles Darwin to win an enduring place in science for +the theory. "The Origin of Species" (1859) not only sustained it with a +wealth of positive knowledge which Lamarck did not command, but it +provided a more luminous explanation in the doctrine of natural +selection. Huxley (1863) followed with an application of the law to man, +and in 1866 I gave a comprehensive sketch of its application throughout +the whole animal world. In 1874 I published the first edition of the +present work. + +The doctrine of evolution is now a vital part of biology, and we might +accept the evolution of man as a special deduction from the general law. +Three great groups of evidence impose that law on us. The first group +consists of the facts of palaeontology, or the fossil record of past +animal life. Imperfect as the record is, it shows us a broad divergence +of successively changing types from a simple common root, and in some +cases exhibits the complete transition from one type to another. The +next document is the evidence of comparative anatomy. This science +groups the forms of living animals in such a way that we seem to have +the same gradual divergence of types from simple common ancestors. In +particular, it discovers certain rudimentary organs in the higher +animals, which can only be understood as the shrunken relics of organs +that were once useful to a remote ancestor. Thus, man has still the +rudiment of the third eyelid of his shark-ancestor. The third document +is the evidence of embryology, which shows us the higher organism +substantially reproducing, in its embryonic development, the long +series of ancestral forms. + + +_II.--Man's Embryonic Development_ + +The first stage in the development of any animal is the tiny speck of +plasm, hardly visible to the naked eye, which we call the ovum, or +egg-cell. It is a single cell, recalling the earliest single-celled +ancestor of all animals. In its immature form it is not unlike certain +microscopic animalcules known as _amoeboe_. In its mature form it is +about 1/125th of an inch in diameter. + +When the male germ has blended with the female in the ovum, the new cell +slowly divides into two, with a very complicated division of the +material composing its nucleus. The two cells divide into four, the four +into eight, and so on until we have a round cluster of cells, something +like a blackberry in shape. + +This _morula_, as I have called it, reproduces the next stage in the +development of life. As all animals pass through it, our biogenetic law +forces us to see in it an ancestral stage; and in point of fact we have +animals of this type living in Nature to-day. The round cluster becomes +filled with fluid, and we have a hollow sphere of cells, which I call +the _blastula_. The corresponding early ancestor I name the _Blastaea_, +and again we find examples of it, like the _Volvox_ of the ponds, in +Nature to-day. + +The next step is very important. The hollow sphere closes in on itself, +as when an india rubber ball is pressed into the form of a cup. We have +then a vase-shaped body with two layers of cells, an inner and an outer, +and an opening. The inner layer we call the entoderm, the outer the +ectoderm; and the "primitive mouth" is known as the blastopore. In the +higher animals a good deal of food-yolk is stored up in the germ, and so +the vase-shaped structure has been flattened and altered. It has, +however, been shown that all embryos pass through this stage +(gastrulation), and we again infer the existence of a common ancestor of +that type--the _Gastraea_. The lowest group of many-celled animals--the +corals, jelly-fishes, and anemones--are essentially of that structure. + +The embryo now consists of two layers of cells, the "germ-layers," an +inner and outer. As the higher embryo develops, a third layer of cells +now pushes between the two. We may say, broadly, that from this middle +layer are developed most of the animal organs of the body; from the +internal germ-layer is developed the lining of the alimentary canal and +its dependent glands; from the outer layer are formed the skin and the +nervous system--which developed originally in the skin. + +The embryo of man and all the other higher animals now develops a +cavity, a pair of pouches, by the folding of the layer at the primitive +mouth. Sir E. Ray Lankester, and Professor Balfour, and other students, +traced this formation through the whole embryonic world, and we are +therefore again obliged to see in it a reminiscence of an ancestral +form--a primitive worm-like animal, of a type we shall see later. The +next step is the formation of the first trace of what will ultimately be +the backbone. It consists at first of a membraneous tube, formed by the +folding of the inner layer along the axis of the embryo-body. Later this +tube will become cartilage, and in the higher animals the cartilage will +give place to bone. + +The other organs of the body now gradually form from the germ-layers, +principally by the folding of the layers into tubes. A light area +appears on the surface of the germ. A streak or groove forms along its +axis, and becomes the nerve-cord running along the back. Cube-shaped +structures make their appearance on either side of it; these prove to be +the rudiments of the vertebrae--or separate bones of the backbone--and +gradually close round the cord. The heart is at first merely a +spindle-shaped enlargement of the main ventral blood-vessel. The nose is +at first only a pair of depressions in the skin above the mouth. + +When the human embryo is only a quarter of an inch in length, it has +gill-clefts and gill-arches in the throat like a fish, and no limbs. The +heart--as yet with only the simple two-chambered structure of a fish's +heart--is up in the throat--as in the fish--and the principal arteries +run to the gill-slits. These structures never have any utility in man or +the other land-animals, though the embryo always has them for a time. +They point clearly to a fish ancestor. + +Later, they break up, the limbs sprout out like blunt fins at the sides, +and the long tail begins to decrease. By the twelfth week the human +frame is perfectly formed, though less than two inches long. Last of +all, it retains its resemblance to the ape. In the embryonic apparatus, +too, man closely resembles the higher ape. + + +_III.--Our Ancestral Tree_ + +The series of forms which we thus trace in man's embryonic development +corresponds to the ancestral series which we would assign to man on the +evidence of palaeontology and comparative anatomy. At one time, the +tracing of this ancestral series encountered a very serious check. When +we examined the groups of living animals, we found none that illustrated +or explained the passage from the non-backboned--invertebrate--to the +backboned--vertebrate--animals. This gap was filled some years ago by +the discovery of the lancelet--_Amphioxus_--and the young of the +sea-squirt--_Ascidia_. The lancelet has a slender rod of cartilage along +its back, and corresponds very closely with the ideal I have sketched of +our primitive backboned ancestor. It may be an offshoot from the same +group. The sea-squirt further illustrates the origin of the backbone, +since it has a similar rod of cartilage in its youth, and loses it, by +degeneration, in its maturity. + +In this way the chief difficulty was overcome, and it was possible to +sketch the probable series of our ancestors. It must be well understood +that not only is the whole series conjectural, but no living animal must +be regarded as an ancestral form. The parental types have long been +extinct, and we may, at the most, use very conservative living types to +illustrate their nature, just as, in the matter of languages, German is +not the parent, but the cousin of Anglo-Saxon, or Greek of Latin. The +original parental languages are lost. But a language like Sanscrit +survives to give us a good idea of the type. + +The law of evolution is based on such a mass of evidence that we may +justly draw deductions from it, where the direct evidence is incomplete. +This is especially necessary in the early part of our ancestral tree, +because the fossil record quite fails us. For millions of years the +early soft-bodied animals left no trace in the primitive mud, which time +has hardened into rocks, and we are restricted to the evidence of +embryology and of comparative zoology. This suffices to give us a +general idea of the line of development. + +In nature to-day, one of the lowest animal forms is a tiny speck of +living plasm called the _amoeba_. We have still more elementary forms, +such as the minute particles which make up the bluish film on damp +rocks, but they are of a vegetal character, or below it. They give us +some idea of the very earliest forms of life; minute living particles, +with no organs, down to the ten-thousandth part of an inch in diameter. +The amoeba represents the lowest animal, and, as we saw, the ovum in +many cases resembles an amoeba. We therefore take some such one-celled +creature as our first animal ancestor. Taking food in at all parts of +its surface, having no permanent organs of locomotion, and reproducing +by merely splitting into two, it exhibits the lowest level of animal +life. + +The next step in development would be the clustering together of these +primitive microbes as they divided. This is actually the stage that +comes next in the development of the germ, and it is the next stage +upward in the existing animal world. We assume that these clusters of +microbes--or cells, as we will now call them--bent inward, as we saw the +embryo do, and became two-layered, cup-shaped organisms, with a hollow +interior (primitive stomach) and an aperture (primitive mouth). The +inner cells now do the work of digestion alone; the outer cells effect +locomotion, by means of lashes like oars, and are sensitive. This is, in +the main, the structure of the next great group of animals, the hydra, +coral, meduca, and anemone. They have remained at this level, though +they have developed, special organs for stinging their prey and bringing +the food into their mouths. + +Both zoology and the appearance of the embryo point to a worm-like +animal as the next stage. Constant swimming in the water would give the +animal a definite head, with special groups of nerve-cells, a definite +tail, and a two-sided or evenly-balanced body. + +We mean that those animals would be fittest to live, and multiply most, +which developed this organisation. Sense-organs would now appear in the +head, in the form of simple depressions, lined with sensitive cells, as +they do in the embryo; and a clump of nerve-cells within would represent +the primitive brain. In the vast and varied worm-group we find +illustrations of nearly every step in this process of evolution. + +The highest type of worm-like creature, the acorn-headed +worm--_Balanoglossus_--takes us an important step further. It has +gill-openings for breathing, and a cord of cartilage down its back. We +saw that the human embryo has a gill-apparatus, and that, comparing the +lancelet and the sea-squirt, the backbone must have begun as a string of +cartilage-cells. We are now on firmer ground, for there is no doubt that +all the higher land-animals come from a fish ancestor. The shark, one of +the most primitive of fishes in organisation, probably best suggests +this ancestor to us. In fact, in the embryonic development of the human +face there is a clear suggestion of the shark. + +Up to this period the story of evolution had run its course in the sea. +The area of dry land was now increasing, and certain of the primitive +fishes adapted themselves to living on land. They walked on their fins, +and used their floating-bladders--large air-bladders in the fish, for +rising in the water--to breathe air. We not only have fishes of this +type in Australia to-day, but we have the fossil remains of similar +fishes in the Old Red Sandstone rocks. From mud-fish the amphibian would +naturally develop, as it did in the coal-forest period. Walking on the +fins would strengthen the main stem, the broad paddle would become +useless, and we should get in time the bony five-toed limb. We have many +of these giant salamander forms in the rocks. + +The reptile now evolved from the amphibian, and a vast reptile +population spread over the earth. From one of these early reptiles the +birds were evolved. Geology furnishes the missing link between the bird +and the reptile in the _Archaeopteryx_, a bird with teeth, claws on its +wings, and a reptilian tail. From another primitive reptile the +important group of the mammals was evolved. We find what seem to be the +transitional types in the rocks of South Africa. The scales gave way to +tufts of hair, the heart evolved a fourth chamber, and thus supplied +purer blood (warm blood), the brain profited by the richer food, and the +mother began to suckle the young. We have still a primitive mammal of +this type in the duck-mole, or duck-billed platypus (_Ornithorhyncus_) +of Australia. There are grounds for thinking that the next stage was an +opossum-like animal, and this led on to the lowest ape-like being, the +lemur. Judging from the fossil remains, the black lemur of Madagascar +best suggests this ancestor. + +The apes of the Old and New Worlds now diverged from this level, and +some branch of the former gave rise to the man-like apes and man. In +bodily structure and embryonic development the large apes come very +close to man, and two recent discoveries have put their +blood-relationship beyond question. One is that experiments in the +transfusion of blood show that the blood of the man-like ape and man +have the same action on the blood of lower animals. The other is that we +have discovered, in Java, several bones of a being which stands just +midway between the highest living ape and lowest living race of men. +This ape-man (_Pithecanthropus_) represents the last of our animal and +first of our human ancestors. + + +_IV.--Evolution of Separate Organs_ + +So far, we have seen how the human body as a whole develops through a +long series of extinct ancestors. We may now take the various systems of +organs one by one, and, if we are careful to consult embryology as well +as zoology, we can trace the manner of their development. It is, in +accordance with our biogenetic law, the same in the embryo, as a rule, +as in the story of past evolution. + +We take first the nervous system. In the lowest animals, as in the early +stages of the embryo, there are no nerve-cells. In the embryo the +nerve-cells develop from the outer, or skin layer, of cells. This, +though strange as regards the human nervous system, is a correct +preservation of the primitive seat of the nerves. It was the surface of +the animal that needed to be sensitive in the primitive organism. Later, +when definite connecting nerves were formed, only special points in the +surface, protected by coverings which did not interfere with the +sensitiveness, needed to be exposed, and the nerves transmitted the +impressions to the central brain. + +This development is found in the animal world to-day. In such animals as +the hydra we find the first crude beginning of unorganised nerve-cells. +In the jelly-fish we find nerve-cells clustered into definite sensitive +organs. In the lower worms we have the beginning of organs of smell and +vision. They are at first merely blind, sensitive pits in the skin, as +in the embryo. The ear has a peculiar origin. Up to the fish level there +is no power of hearing. There is merely a little stone rolling in a +sensitive bed, to warn the animal of its movement from side to side. In +the higher animals this evolves into the ear. + +The glands of the skin (sweat, fat, tears, etc.) appear at first as +blunt, simple ingrowths. The hair first appears in tufts, representing +the scales, from underneath which they were probably evolved. The thin +coat of hair on the human body to-day is an ancestral inheritance. This +is well shown by the direction of the hairs on the arm. As on the ape's +arm, both on the upper and lower arm, they grow toward the elbow. The +ape finds this useful in rain, using his arms like a thatched roof, and +on our arm this can only be a reminiscence of the habits of an ape +ancestor. + +We have seen how the spinal cord first appears as a tube in the axis of +the back, and the cartilaginous column closes round it. All bone appears +first as membrane, then cartilage, and finally ossifies. This is the +order both in past evolution and in present embryonic development. The +brain is at first a bulbous expansion of the spinal nerve-cord. It is at +first simple, but gradually, both in the scale of nature and in the +embryo, divides into five parts. One of these parts, the cerebrum, is +mainly connected with mental life. We find it increasing in size, in +proportion to the animal's intelligence, until in man it comes to cover +the whole of the brain. When we remove it from the head of the mammal, +without killing the animal, we find all mental life suspended, and the +whole vitality used in vegetative functions. + +In the evolution of the bony system we find the same correspondence of +embryology and evolution. The main column is at first a rod of +cartilage. In time the separate cubes appear which are to form the +vertebrae of the flexible column. The skull develops in the same way. +Just as the brain is a specially modified part of the nerve-rod, the +skull is only a modified part of the vertebral column. The bones that +compose it are modified vertebrae, as Goethe long ago suspected. The +skull of the shark gives us a hint of the way in which the modification +took place, and the formation of the skull in the embryo confirms it. + +That adult man is devoid of that prolongation of the vertebral column +which we call a tail is not a distinctive peculiarity. The higher apes +are equally without it. We find, however, that the human embryo has a +long tail, much longer than the legs, when they are developing. At +times, moreover, children are born with tails--perfect tails, with +nerves and muscles, which they move briskly under emotion, and these +have to be amputated. The development of the limb from the fin offers no +serious difficulty to the osteologist. All the higher animals descend +from a five-toed ancestor. The whale has taken again to the water, and +reconverted its limb into a paddle. The bones of the front feet still +remain under the flesh. Animals of the horse type have had the central +toe strengthened, for running purposes, at the expense of the rest. The +serpent has lost its limbs from disuse, but in the python a rudimentary +limb-bone is still preserved. + +The alimentary system, blood-vessel system, and reproductive system +have been evolved gradually in the same way. The stomach is at first the +whole cavity in the animal. Later it becomes a straight, simple tube, +strengthened by a gullet in front. The liver is an outgrowth from this +tube; the stomach proper is a bulbous expansion of its central part, +later provided with a valve. The kidneys are at first simple channels in +the skin for drainage, then closed tubes, which branch out more and +more, and then gather into our compact kidneys. We thus see that the +building up of the human body from a single cell is a substantial +epitome of the long story of evolution, which occupied many millions of +years. We find man bearing in his body to-day traces of organs which +were useful to a remote ancestor, but of no advantage, and often a +source of mischief to himself. We learn that the origin of man, instead +of being placed a few thousand years ago, must be traced back to the +point where, hundreds of thousands of years ago, he diverged from his +ape-cousins, though he retains to-day the plainest traces of that +relationship. Body and mind--for the development of mind follows with +the utmost precision on the development of brain--he is the culmination +of a long process of development. His spirit is a form of energy +inseparably bound up with the substance of his body. His evolution has +been controlled by the same "eternal, iron laws" as the development of +any other body--the laws of heredity and adaptation. + + + + +WILLIAM HARVEY + +On the Motion of the Heart and Blood + + William Harvey, the discoverer of the circulation of the blood, was + born at Folkestone, England, on April 1, 1578. After graduating + from Caius College, Cambridge, he studied at Padua, where he had + the celebrated anatomist, Fabricius of Aquapendente, for his + master. In 1615 he was elected Lumleian lecturer at the College of + Physicians, and three years later was appointed physician + extraordinary to King James I. In 1628, twelve years after his + first statement of it in his lectures, he published at Frankfurt, + in Latin, "An Anatomical Disquisition on the Motion of the Heart + and Blood," in which he maintained that there is a circulation of + the blood. Moreover, he distinguished between the pulmonary + circulation, from the right side of the heart to the left through + the lungs, and the systemic circulation from the left side of the + heart to the right through the rest of the body. Further, he + maintained that it was the office of the heart to maintain this + circulation by its alternate _diastole_ (expansion) and _systole_ + (contraction) throughout life. This discovery was, says Sir John + Simon, the most important ever made in physiological science. It is + recorded that after his publication of it Harvey lost most of his + practice. Harvey died on June 3, 1657. + + +_I.--Motions of the Heart in Living Animals_ + +When first I gave my mind to vivisections as a means of discovering the +motions and uses of the heart, I found the task so truly arduous that I +was almost tempted to think, with Fracastorius, that the motion of the +heart was only to be comprehended by God. For I could neither rightly +perceive at first when the systole and when the diastole took place, nor +when and where dilation and contraction occurred, by reason of the +rapidity of the motion, which, in many animals, is accomplished in the +twinkling of an eye, coming and going like a flash of lightning. At +length it appeared that these things happen together or at the same +instant: the tension of the heart, the pulse of its apex, which is felt +externally by its striking against the chest, the thickening of its +walls, and the forcible expulsion of the blood it contains by the +constriction of its ventricles. + +Hence the very opposite of the opinions commonly received appears to be +true; inasmuch as it is generally believed that when the heart strikes +the breast and the pulse is felt without, the heart is dilated in its +ventricles and is filled with blood. But the contrary of this is the +fact; that is to say, the heart is in the act of contracting and being +emptied. Whence the motion, which is generally regarded as the diastole +of the heart, is in truth its systole. And in like manner the intrinsic +motion of the heart is not the diastole but the systole; neither is it +in the diastole that the heart grows firm and tense, but in the systole; +for then alone when tense is it moved and made vigorous. When it acts +and becomes tense the blood is expelled; when it relaxes and sinks +together it receives the blood in the manner and wise which will by and +by be explained. + +From divers facts it is also manifest, in opposition to commonly +received opinions, that the diastole of the arteries corresponds with +the time of the heart's systole; and that the arteries are filled and +distended by the blood forced into them by the contraction of the +ventricles. It is in virtue of one and the same cause, therefore, that +all the arteries of the body pulsate, _viz._, the contraction of the +left ventricle in the same way as the pulmonary artery pulsates by the +contraction of the right ventricle. + +I am persuaded it will be found that the motion of the heart is as +follows. First of all, the auricle contracts and throws the blood into +the ventricle, which, being filled, the heart raises itself straightway, +makes all its fibres tense, contracts the ventricles and performs a +beat, by which beat it immediately sends the blood supplied to it by the +auricle into the arteries; the right ventricle sending its charge into +the lungs by the vessel called _vena arteriosa_, but which, in structure +and function, and all things else, is an artery; the left ventricle +sending its charge into the aorta, and through this by the arteries to +the body at large. + +The grand cause of hesitation and error in this subject appears to me to +have been the intimate connection between the heart and the lungs. When +men saw both the pulmonary artery and the pulmonary veins losing +themselves in the lungs, of course it became a puzzle to them to know +how the right ventricle should distribute the blood to the body, or the +left draw it from the _venae cavae_. Or they have hesitated because they +did not perceive the route by which the blood is transferred from the +veins to the arteries, in consequence of the intimate connection between +the heart and lungs. And that this difficulty puzzled anatomists not a +little when in their dissections they found the pulmonary artery and +left ventricle full of black and clotted blood, plainly appears when +they felt themselves compelled to affirm that the blood made its way +from the right to the left ventricle by sweating through the septum of +the heart. + +Had anatomists only been as conversant with the dissection of the lower +animals as they are with that of the human body, the matters that have +hitherto kept them in perplexity of doubt would, in my opinion, have met +them freed from every kind of difficulty. And first in fishes, in which +the heart consists of but a single ventricle, they having no lungs, the +thing is sufficiently manifest. Here the sac, which is situated at the +base of the heart, and is the part analogous to the auricle in man, +plainly throws the blood into the heart, and the heart in its turn +conspicuously transmits it by a pipe or artery, or vessel analogous to +an artery; these are facts which are confirmed by simple ocular +experiment. I have seen, farther, that the same thing obtained most +obviously. + +And since we find that in the greater number of animals, in all indeed +at a certain period of their existence, the channels for the +transmission of the blood through the heart are so conspicuous, we have +still to inquire wherefore in some creatures--those, namely, that have +warm blood and that have attained to the adult age, man among the +number--we should not conclude that the same thing is accomplished +through the substance of the lungs, which, in the embryo, and at a time +when the functions of these organs is in abeyance, Nature effects by +direct passages, and which indeed she seems compelled to adopt through +want of a passage by the lungs; or wherefore it should be better (for +Nature always does that which is best) that she should close up the +various open routes which she had formerly made use of in the embryo, +and still uses in all other animals; not only opening up no new apparent +channels for the passage of the blood therefore, but even entirely +shutting up those which formerly existed in the embryos of those animals +that have lungs. For while the lungs are yet in a state of inaction, +Nature uses the two ventricles of the heart as if they formed but one +for the transmission of the blood. The condition of the embryos of those +animals which have lungs is the same as that of those animals which have +no lungs. + +Thus, by studying the structure of the animals who are nearer to and +further from ourselves in their modes of life and in the construction of +their bodies, we can prepare ourselves to understand the nature of the +pulmonary circulation in ourselves, and of the systemic circulation +also. + + +_II.--Systemic Circulation_ + +What remains to be said is of so novel and unheard of a character that I +not only fear injury to myself from the envy of a few, but I tremble +lest I have mankind at large for my enemies, so much do wont and custom +that become as another nature, and doctrine once sown that hath struck +deep root, and respect for antiquity, influence all men. + +And, sooth to say, when I surveyed my mass of evidence, whether derived +from vivisections and my previous reflections on them, or from the +ventricles of the heart and the vessels that enter into and issue from +them, the symmetry and size of these conduits--for Nature, doing nothing +in vain, would never have given them so large a relative size without a +purpose; or from the arrangement and intimate structure of the valves in +particular and of the many other parts of the heart in general, with +many things besides; and frequently and seriously bethought me and long +revolved in my mind what might be the quantity of blood which was +transmitted, in how short a time its passage might be effected and the +like; and not finding it possible that this could be supplied by the +juices of the ingested aliment without the veins on the one hand +becoming drained, and the arteries on the other getting ruptured through +the excessive charge of blood, unless the blood should somehow find its +way from the arteries into the veins, and so return to the right side of +the heart; when I say, I surveyed all this evidence, I began to think +whether there might not be _a motion as it were in a circle_. + +Now this I afterwards found to be true; and I finally saw that the +blood, forced by the action of the left ventricle into the arteries, was +distributed to the body at large, and its several parts, in the same +manner as it is sent through the lungs, impelled by the right ventricle +into the pulmonary artery; and that it then passed through the veins and +along the _vena cava_, and so round to the left ventricle in the manner +already indicated; which motion we may be allowed to call circular, in +the same way as Aristotle says that the air and the rain emulate the +circular motion of the superior bodies. For the moist earth, warmed by +the sun, evaporates; the vapours drawn upwards are condensed, and +descending in the form of rain moisten the earth again. And by this +arrangement are generations of living things produced; and in like +manner, too, are tempests and meteors engendered by the circular motion +of the sun. + +And so in all likelihood does it come to pass in the body through the +motion of the blood. The various parts are nourished, cherished, +quickened by the warmer, more perfect, vaporous, spirituous, and, as I +may say, alimentive blood; which, on the contrary, in contact with these +parts becomes cooled, coagulated, and, so to speak, effete; whence it +returns to its sovereign, the heart, as if to its source, or to the +inmost home of the body, there to recover its state of excellence or +perfection. Here it resumes its due fluidity, and receives an infusion +of natural heat--powerful, fervid, a kind of treasury of life--and is +impregnated with spirits and, it might be said, with balsam; and thence +it is again dispersed. And all this depends upon the motion and action +of the heart. + + +_Confirmations of the Theory_ + +Three points present themselves for confirmation, which, being +established, I conceive that the truth I contend for will follow +necessarily and appear as a thing obvious to all. + +The first point is this. The blood is incessantly transmitted by the +action of the heart from the _vena cava_ to the arteries in such +quantity that it cannot be supplied from the ingesta, and in such wise +that the whole mass must very quickly pass through the organ. + +Let us assume the quantity of blood which the left ventricle of the +heart will contain when distended to be, say, two ounces (in the dead +body I have found it to contain upwards of two ounces); and let us +suppose, as approaching the truth, that the fourth part of its charge +is thrown into the artery at each contraction. Now, in the course of +half an hour the heart will have made more than one thousand beats. +Multiplying the number of drachms propelled by the number of pulses, we +shall have one thousand half-ounces sent from this organ into the +artery; a larger quantity than is contained in the whole body. This +truth, indeed, presents itself obviously before us when we consider what +happens in the dissection of living animals. The great artery need not +be divided, but a very small branch only (as Galen even proves in regard +to man), to have the whole of the blood in the body, as well that of the +veins as of the arteries, drained away in the course of no long +time--some half hour or less. + +The second point is this. The blood, under the influence of the arterial +pulse, enters, and is impelled in a continuous, equable, and incessant +stream through every part and member of the body in much larger quantity +than were sufficient for nutrition, or than the whole mass of fluids +could supply. + +I have here to cite certain experiments. Ligatures are either very tight +or of middling tightness. A ligature I designate as tight, or perfect, +when it is drawn so close about an extremity that no vessel can be felt +pulsating beyond it. Such ligatures are employed in the removal of +tumours; and in these cases, all afflux of nutriment and heat being +prevented by the ligature, we see the tumours dwindle and die, and +finally drop off. Now let anyone make an experiment upon the arm of a +man, either using such a fillet as is employed in bloodletting, or +grasping the limb tightly with his hand; let a ligature be thrown about +the extremity and drawn as tightly as can be borne. It will first be +perceived that beyond the ligature the arteries do not pulsate, while +above it the artery begins to rise higher at each diastole and to swell +with a kind of tide as it strove to break through and overcome the +obstacle to its current. + +Then let the ligature be brought to that state of middling tightness +which is used in bleeding, and it will be seen that the hand and arm +will instantly become deeply suffused and extended, and the veins show +themselves tumid and knotted. Which is as much as to say that when the +arteries pulsate the blood is flowing through them, but where they do +not pulsate they cease from transmitting anything. The veins again being +compressed, nothing can flow through them; the certain indication of +which is that below the ligature they are much more tumid than above it. + +Whence is this blood? It must needs arrive by the arteries. For that it +cannot flow in by the veins appears from the fact that the blood cannot +be forced towards the heart unless the ligature be removed. Further, +when we see the veins below the ligature instantly swell up and become +gorged when from extreme tightness it is somewhat relaxed, the arteries +meanwhile continuing unaffected, this is an obvious indication that the +blood passes from the arteries into the veins, and not from the veins +into the arteries, and that there is either an anastomosis of the two +orders of vessels, or pores in the flesh and solid parts generally that +are permeable to the blood. + +And now we understand wherefore in phlebotomy we apply our fillet above +the part that is punctured, not below it. Did the flow come from above, +not from below, the bandage in this case would not only be of no +service, but would prove a positive hindrance. And further, if we +calculate how many ounces flow through one arm or how many pass in +twenty or thirty pulsations under the medium ligature, we shall perceive +that a circulation is absolutely necessary, seeing that the quantity +cannot be supplied immediately from the ingesta, and is vastly more than +can be requisite for the mere nutrition of the parts. + +And the third point to be confirmed is this. That the veins return this +blood to the heart incessantly from all parts and members of the body. + +This position will be made sufficiently clear from the valves which are +found in the cavities of the veins themselves, from the uses of these, +and from experiments cognisable by the senses. The celebrated Hieronymus +Fabricius, of Aquapendente, first gave representations of the valves in +the veins, which consist of raised or loose portions of the inner +membranes of these vessels of extreme delicacy and a sigmoid, or +semi-lunar shape. Their office is by no means explained when we are told +that it is to hinder the blood, by its weight, from flowing into +inferior parts; for the edges of the valves in the jugular veins hang +downwards, and are so contrived that they prevent the blood from rising +upwards. + +The valves, in a word, do not invariably look upwards, but always +towards the trunks of the veins--towards the seat of the heart. They are +solely made and instituted lest, instead of advancing from the extreme +to the central parts of the body, the blood should rather proceed along +the veins from the centre to the extremities; but the delicate valves, +while they readily open in the right direction, entirely prevent all +such contrary motion, being so situated and arranged that if anything +escapes, or is less perfectly obstructed by the flaps of the one above, +the fluid passing, as it were, by the chinks between the flaps, it is +immediately received on the convexity of the one beneath, which is +placed transversely with reference to the former, and so is effectually +hindered from getting any farther. And this I have frequently +experienced in my dissections of veins. If I attempted to pass a probe +from the trunk of the veins into one of the smaller branches, whatever +care I took I found it impossible to introduce it far any way by reason +of the valves; whilst, on the contrary, it was most easy to push it +along in the opposite direction, from without inwards, or from the +branches towards the trunks and roots. + +And now I may be allowed to give in brief my view of the circulation of +the blood, and to propose it for general adoption. + + +_The Conclusion_ + +Since all things, both argument and ocular demonstration, show that the +blood passes through the lungs and heart by the action of the +ventricles; and is sent for distribution to all parts of the body, where +it makes its way into the veins and pores of the flesh; and then flows +by the veins from the circumference on every side to the centre, from +the lesser to the greater veins; and is by them finally discharged into +the _vena cava_ and right auricle of the heart, and this in such a +quantity or in such a flux and reflux, thither by the arteries, hither +by the veins, as cannot possibly be supplied by the ingesta, and is much +greater than can be required for mere purposes of nutrition; therefore, +it is absolutely necessary to conclude that the blood in the animal body +is impelled in a circle and is in a state of ceaseless motion; and that +this is the act, or function, which the heart performs by means of its +pulse, and that it is the sole and only end of the motion and +contraction of the heart. For it would be very difficult to explain in +any other way to what purpose all is constructed and arranged as we have +seen it to be. + + + + +SIR JOHN HERSCHEL + +Outlines of Astronomy + + Sir John Frederick William Herschel, only child--and, as an + astronomer, almost the only rival--of Sir William Herschel, was + born at Slough, in Ireland, on March 7, 1792. At first privately + educated, in 1813 he graduated from St. John's College, Cambridge, + as senior wrangler and first Smith's prizeman. He chose the law as + his profession; but in 1816 reported that, under his father's + direction, he was going "to take up stargazing." He then began a + re-examination of his father's double stars. In 1825 he wrote that + he was going to take nebulae under his especial charge. He embarked + in 1833 with his family for the Cape; and his work at Feldhausen, + six miles from Cape Town, marked the beginning of southern sidereal + astronomy. The result of his four years' work there was published + in 1847. From 1855 he devoted himself at Collingwood to the + collection and revival of his father's and his own labours. His + "Outlines of Astronomy," published in 1849, and founded on an + earlier "Treatise on Astronomy" of 1833, was an outstanding + success. Herschel's long and happy life, every day of which added + its share to his scientific services, came to an end on May 11, + 1871. + + +_I.--The Wonders of the Milky Way_ + +There is no science which draws more largely than does astronomy on that +intellectual liberality which is ready to adopt whatever is demonstrated +or concede whatever is rendered highly probable, however new and +uncommon the points of view may be in which objects the most familiar +may thereby become placed. Almost all its conclusions stand in open and +striking contradiction with those of superficial and vulgar observation, +and with what appears to everyone the most positive evidence of his +senses. + +There is hardly anything which sets in a stronger light the inherent +power of truth over the mind of man, when opposed by no motives of +interest or passion, than the perfect readiness with which all its +conclusions are assented to as soon as their evidence is clearly +apprehended, and the tenacious hold they acquire over our belief when +once admitted. + +If the comparison of the apparent magnitude of the stars with their +number leads to no immediately obvious conclusion, it is otherwise when +we view them in connection with their local distribution over the +heavens. If indeed we confine ourselves to the three or four brightest +classes, we shall find them distributed with a considerable approach to +impartiality over the sphere; a marked preference, however, being +observable, especially in the southern hemisphere, to a zone or belt +passing through _epsilon_ Orionis and _alpha_ Crucis. But if we take in +the whole amount visible to the naked eye we shall perceive a great +increase of numbers as we approach the borders of the Milky Way. And +when we come to telescopic magnitudes we find them crowded beyond +imagination along the extent of that circle and of the branches which it +sends off from it; so that, in fact, its whole light is composed of +nothing but stars of every magnitude from such as are visible to the +naked eye down to the smallest points of light perceptible with the best +telescopes. + +These phenomena agree with the supposition that the stars of our +firmament, instead of being scattered indifferently in all directions +through space, form a stratum of which the thickness is small in +comparison with its length and breadth; and in which the earth occupies +a place somewhere about the middle of its thickness and near the point +where it subdivides into two principal laminae inclined at a small angle +to each other. For it is certain that to an eye so situated the apparent +density of the stars, supposing them pretty equally scattered through +the space they occupy, would be least in the direction of the visual ray +perpendicular to the lamina, and greatest in that of its breadth; +increasing rapidly in passing from one to the other direction, just as +we see a slight haze in the atmosphere thickening into a decided +fog-bank near the horizon by the rapid increase of the mere length of +the visual ray. + +Such is the view of the construction of the starry firmament taken by +Sir William Herschel, whose powerful telescopes first effected a +complete analysis of this wonderful zone, and demonstrated the fact of +its entirely consisting of stars. + +So crowded are they in some parts of it that by counting the stars in a +single field of his telescope he was led to conclude that 50,000 had +passed under his review in a zone two degrees in breadth during a single +hour's observation. The immense distances at which the remoter regions +must be situated will sufficiently account for the vast predominance of +small magnitudes which are observed in it. + +The process of gauging the heavens was devised by Sir William Herschel +for this purpose. It consisted simply in counting the stars of all +magnitudes which occur in single fields of view, of fifteen minutes in +diameter, visible through a reflecting telescope of 18 inches aperture, +and 20 feet focal length, with a magnifying power of 180 degrees, the +points of observation being very numerous and taken indiscriminately in +every part of the surface of the sphere visible in our latitudes. + +On a comparison of many hundred such "gauges," or local enumerations, it +appears that the density of starlight (or the number of stars existing +on an average of several such enumerations in any one immediate +neighbourhood) is least in the pole of the Galactic circle [_i.e._, the +great circle to which the course of the Milky Way most nearly conforms: +_gala_ = milk], and increases on all sides down to the Milky Way itself, +where it attains its maximum. The progressive rate of increase in +proceeding from the pole is at first slow, but becomes more and more +rapid as we approach the plane of that circle, according to a law from +which it appears that the mean density of the stars in the galactic +circle exceeds, in a ratio of very nearly 30 to 1, that in its pole, and +in a proportion of more than 4 to 1 that in a direction 15 degrees +inclined to its plane. + +As we ascend from the galactic plane we perceive that the density +decreases with great rapidity. So far we can perceive no flaw in this +reasoning if only it be granted (1) that the level planes are continuous +and of equal density throughout; and (2) that an absolute and definite +limit is set to telescopic vision, beyond which, if stars exist, they +elude our sight, and are to us as if they existed not. It would appear +that, with an almost exactly similar law of apparent density in the two +hemispheres, the southern were somewhat richer in stars than the +northern, which may arise from our situation not being precisely in the +middle of its thickness, but somewhat nearer to its northern surface. + + +_II.--Penetrating Infinite Space_ + +When examined with powerful telescopes, the constitution of this +wonderful zone is found to be no less various than its aspect to the +naked eye is irregular. In some regions the stars of which it is +composed are scattered with remarkable uniformity over immense tracts, +while in others the irregularity of their distribution is quite as +striking, exhibiting a rapid succession of closely clustering rich +patches separated by comparatively poor intervals, and indeed in some +instances absolutely dark and _completely_ void of any star even of the +smallest telescopic magnitude. In some places not more than 40 or 50 +stars on an average occur in a "gauge" field of 15 minutes, while in +others a similar average gives a result of 400 or 500. + +Nor is less variety observable in the character of its different +regions in respect of the magnitude of the stars they exhibit, and the +proportional numbers of the larger and smaller magnitudes associated +together, than in respect of their aggregate numbers. In some, for +instance, extremely minute stars, though never altogether wanting, occur +in numbers so moderate as to lead us irresistibly to the conclusion that +in these regions we are _fairly through_ the starry stratum, since it is +impossible otherwise (supposing their light not intercepted) that the +numbers of the smaller magnitudes should not go on increasing _ad +infinitum_. + +In such cases, moreover, the ground of the heavens, as seen between the +stars, is for the most part perfectly dark, which again would not be the +case if innumerable multitudes of stars, too minute to be individually +discernible, existed beyond. In other regions we are presented with the +phenomenon of an almost uniform degree of brightness of the individual +stars, accompanied with a very even distribution of them over the ground +of the heavens, both the larger and smaller magnitudes being strikingly +deficient. In such cases it is equally impossible not to perceive that +we are looking through a sheet of stars nearly of a size and of no great +thickness compared with the distance which separates them from us. Were +it otherwise we should be driven to suppose the more distant stars were +uniformly the larger, so as to compensate by their intrinsic brightness +for their greater distance, a supposition contrary to all probability. + +In others again, and that not infrequently, we are presented with a +double phenomenon of the same kind--_viz._, a tissue, as it were, of +large stars spread over another of very small ones, the intermediate +magnitudes being wanting, and the conclusion here seems equally evident +that in such cases we look through two sidereal sheets separated by a +starless interval. + +Throughout by far the larger portion of the extent of the Milky Way in +both hemispheres the general blackness of the ground of the heavens on +which its stars are projected, and the absence of that innumerable +multitude and excessive crowding of the smallest visible magnitudes, and +of glare produced by the aggregate light of multitudes too small to +affect the eye singly, which the contrary supposition would appear to +necessitate, must, we think, be considered unequivocal indications that +its dimensions, _in directions where those conditions obtain_, are not +only not infinite, but that the space-penetrating power of our +telescopes suffices fairly to pierce through and beyond it. + +It is but right, however, to warn our readers that this conclusion has +been controverted, and that by an authority not lightly to be put aside, +on the ground of certain views taken by Olbers as to a defect of perfect +transparency in the celestial spaces, in virtue of which the light of +the more distant stars is enfeebled more than in proportion to their +distance. The extinction of light thus originating proceeding in +geometrical ratio, while the distance increases in arithmetical, a +limit, it is argued, is placed to the space-penetrating power of +telescopes far within that which distance alone, apart from such +obscuration, would assign. + +It must suffice here to observe that the objection alluded to, if +applicable to any, is equally so to every part of the galaxy. We are not +at liberty to argue that at one part of its circumference our view is +limited by this sort of cosmical veil, which extinguishes the smaller +magnitudes, cuts off the nebulous light of distant masses, and closes +our view in impenetrable darkness; while at another we are compelled, by +the clearest evidence telescopes can afford, to believe that star-strewn +vistas _lie open_, exhausting their powers and stretching out beyond +their utmost reach, as is proved by that very phenomenon which the +existence of such a veil would render impossible--_viz._, infinite +increase of number and diminution of magnitude, terminating in complete +irresolvable nebulosity. + +Such is, in effect, the spectacle afforded by a very large portion of +the Milky Way in that interesting region near its point of bifurcation +in Scorpio, where, through the hollows and deep recesses of its +complicated structure, we behold what has all the appearance of a wide +and indefinitely prolonged area strewed over with discontinuous masses +and clouds of stars, which the telescope at last refuses to analyse. +Whatever other conclusions we may draw, this must anyhow be regarded as +the direction of the greatest linear extension of the ground-plan of the +galaxy. And it would appear to follow also that in those regions where +that zone is clearly resolved into stars well separated and _seen +projected on a black ground_, and where, by consequence, it is certain, +if the foregoing views be correct, that we look out beyond them into +space, the smallest visible stars appear as such not by reason of +excessive distance, but of inferiority of size or brightness. + + +_III.--Variable, Temporary and Binary Stars_ + +Wherever we can trace the law of periodicity we are strongly impressed +with the idea of rotatory or orbitual motion. Among the stars are +several which, though in no way distinguishable from others by any +apparent change of place, nor by any difference of appearance in +telescopes, yet undergo a more or less regular periodical increase and +diminution of lustre, involving in one or two cases a complete +extinction and revival. These are called periodic stars. The longest +known, and one of the most remarkable, is the star _Omicron_ in the +constellation Cetus (sometimes called Mira Ceti), which was first +noticed as variable by Fabricius in 1596. It appears about twelve times +in eleven years, remains at its greatest brightness about a fortnight, +being then on some occasions equal to a large star of the second +magnitude, decreases during about three months, till it becomes +completely invisible to the naked eye, in which state it remains about +five months, and continues increasing during the remainder of its +period. Such is the general course of its phases. But the mean period +above assigned would appear to be subject to a cyclical fluctuation +embracing eighty-eight such periods, and having the effect of gradually +lengthening and shortening alternately those intervals to the extent of +twenty-five days one way and the other. The irregularities in the degree +of brightness attained at the maximum are also periodical. + +Such irregularities prepare us for other phenomena of stellar variation +which have hitherto been reduced to no law of periodicity--the phenomena +of temporary stars which have appeared from time to time in different +parts of the heavens blazing forth with extraordinary lustre, and after +remaining awhile, apparently immovable, have died away and left no +trace. In the years 945, 1264, and 1572 brilliant stars appeared in the +region of the heavens between Cepheus and Cassiopeia; and we may suspect +them, with Goodricke, to be one and the same star with a period of 312, +or perhaps 156 years. The appearance of the star of 1572 was so sudden +that Tycho Brahe, a celebrated Dutch astronomer, returning one evening +from his laboratory to his dwellinghouse, was surprised to find a group +of country people gazing at a star which he was sure did not exist half +an hour before. This was the star in question. It was then as bright as +Sirius, and continued to increase till it surpassed Jupiter when +brightest, and was visible at midday. It began to diminish in December +of the same year, and in March 1574 had entirely disappeared. + +In 1803 it was announced by Sir William Herschel that there exist +sidereal systems composed of two stars revolving about each other in +regular orbits, and constituting which may be called, to distinguish +them from double stars, which are only optically double, binary stars. +That which since then has been most assiduously watched, and has offered +phenomena of the greatest interest, is _gamma Virginis_. It is a star of +the vulgar third magnitude, and its component individuals are very +nearly equal, and, as it would seem, in some slight degree variable. It +has been known to consist of two stars since the beginning of the +eighteenth century, the distance being then between six and seven +seconds, so that any tolerably good telescope would resolve it. When +observed by Herschel in 1780 it was 5.66 seconds, and continued to +decrease gradually and regularly, till at length, in 1836, the two stars +had approached so closely as to appear perfectly round and single under +the highest magnifying power which could be applied to most excellent +instruments--the great refractor of Pulkowa alone, with a magnifying +power of a thousand, continuing to indicate, by the wedge-shaped form of +the disc of the star, its composite nature. + +By estimating the ratio of its length to its breadth, and measuring the +former, M. Struve concludes that at this epoch the distance of the two +stars, centre from centre, might be stated at .22 seconds. From that +time the star again opened, and is now again a perfectly easily +separable star. This very remarkable diminution, and subsequent +increase, of distance has been accompanied by a corresponding and +equally remarkable increase and subsequent diminution of relative +angular motion. Thus in 1783 the apparent angular motion hardly amounted +to half a degree per annum; while in 1830 it had decreased to 5 degrees, +in 1834 to 20 degrees, in 1835 to 40 degrees, and about the middle of +1836 to upwards of 70 degrees per annum, or at the rate of a degree in +five days. + +This is in entire conformity with the principles of dynamics, which +establish a necessary connection between the angular velocity and the +distance, as well in the apparent as in the real orbit of one body +revolving about another under the influence of mutual attraction; the +former varying inversely as the square of the latter, in both orbits, +whatever be the curve described and whatever the law of the attractive +force. + +It is not with the revolutions of bodies of a planetary or cometary +nature round a solar centre that we are concerned; it is that of sun +round sun--each perhaps, at least in some binary systems, where the +individuals are very remote and their period of revolution very long, +accompanied by its train of planets and their satellites, closely +shrouded from our view by the splendour of their respective suns, and +crowded into a space bearing hardly a greater proportion to the enormous +interval which separates them than the distances of the satellites of +our planets from their primaries bear to their distances from the sun +itself. + +A less distinctly characterised subordination would be incompatible with +the stability of their systems and with the planetary nature of their +orbits. Unless close under the protecting wing of their immediate +superior, the sweep of their other sun, in its perihelion passage round +their own, might carry them off or whirl them into orbits utterly +incompatible with conditions necessary for the existence of their +inhabitants. + + +_IV.--The Nebulae_ + +It is to Sir William Herschel that we owe the most complete analysis of +the great variety of those objects which are generally classed as +nebulae. The great power of his telescopes disclosed the existence of an +immense number of these objects before unknown, and showed them to be +distributed over the heavens not by any means uniformly, but with a +marked preference to a certain district extending over the northern pole +of the galactic circle. In this region, occupying about one-eighth of +the surface of the sphere, one-third of the entire nebulous contents of +the heavens are situated. + +The resolvable nebulae can, of course, only be considered as clusters +either too remote, or consisting of stars intrinsically too faint, to +affect us by their individual light, unless where two or three happen to +be close enough to make a joint impression and give the idea of a point +brighter than the rest. They are almost universally round or oval, their +loose appendages and irregularities of form being, as it were, +extinguished by the distance, and only the general figure of the +condensed parts being discernible. It is under the appearance of objects +of this character that all the greater globular clusters exhibit +themselves in telescopes of insufficient optical power to show them +well. + +The first impression which Halley and other early discoverers of +nebulous objects received from their peculiar aspect was that of a +phosphorescent vapour (like the matter of a comet's tail), or a gaseous +and, so to speak, elementary form of luminous sidereal matter. Admitting +the existence of such a medium, Sir W. Herschel was led to speculate on +its gradual subsidence and condensation, by the effect of its own +gravity, into more or less regular spherical or spheroidal forms, denser +(as they must in that case be) towards the centre. + +Assuming that in the progress of this subsidence local centres of +condensation subordinate to the general tendency would not be wanting, +he conceived that in this way solid nuclei might arise whose local +gravitation still further condensing, and so absorbing the nebulous +matter each in its immediate neighbourhood, might ultimately become +stars, and the whole nebula finally take on the state of a cluster of +stars. + +Among the multitude of nebulae revealed by his telescope every stage of +this process might be considered as displayed to our eyes, and in every +modification of form to which the general principle might be conceived +to apply. The more or less advanced state of a nebula towards its +segregation into discrete stars, and of these stars themselves towards a +denser state of aggregation round a central nucleus, would thus be in +some sort an indication of age. + + + + +ALEXANDER VON HUMBOLDT + +Cosmos, a Sketch of the Universe + + Frederick Henry Alexander von Humboldt was born in Berlin on + September 14, 1769. In 1788 he made the acquaintance of George + Forster, one of Captain Cook's companions, and geological + excursions made with him were the occasion of his first + publications, a book on the nature of basalt. His work in the + administration of mines in the principalities of Bayreuth and + Anspach furnished materials for a treatise on fossil flora; and in + 1827, when he was residing in Paris, he gave to the world his + "Voyage to the Equinoctial Regions of the New Continent," which + embodies the results of his investigations in South America. Two + years later he organised an expedition to Asiatic Russia, charging + himself with all the scientific observations. But his principal + interest lay in the accomplishment of that physical description of + the universe for which all his previous studies had been a + preparation, and which during the years 1845 to 1848 appeared under + the comprehensive title of "Cosmos, or Sketch of a Physical + Description of the Universe." Humboldt died on May 6, 1859. + + +_I.--The Physical Study of the World_ + +The natural world may be opposed to the intellectual, or nature to art +taking the latter term in its higher sense as embracing the +manifestations of the intellectual power of man; but these +distinctions--which are indicated in most cultivated languages--must not +be suffered to lead to such a separation of the domain of physics from +that of the intellect as would reduce the physics of the universe to a +mere assemblage of empirical specialities. Science only begins for man +from the moment when his mind lays hold of matter--when he tries to +subject the mass accumulated by experience to rational combinations. + +Science is mind applied to nature. The external world only exists for us +so far as we conceive it within ourselves, and as it shapes itself +within us into the form of a contemplation of nature. As intelligence +and language, thought and the signs of thought, are united by secret and +indissoluble links, so, and almost without our being conscious of it, +the external world and our ideas and feelings melt into each other. +"External phenomena are translated," as Hegel expresses it in his +"Philosophy of History," "in our internal representation of them." The +objective world, thought by us, reflected in us, is subjected to the +unchanging, necessary, and all-conditioning forms of our intellectual +being. + +The activity of the mind exerts itself on the elements furnished to it +by the perceptions of the senses. Thus, in the youth of nations there +manifests itself in the simplest intuition of natural facts, in the +first efforts made to comprehend them, the germ of the philosophy of +nature. + +If the study of physical phenomena be regarded in its bearings not on +the material wants of man, but on his general intellectual progress, its +highest result is found in the knowledge of those mutual relations which +link together the general forces of nature. It is the intuitive and +intimate persuasion of the existence of these relations which at once +enlarges and elevates our views and enhances our enjoyment. Such +extended views are the growth of observation, of meditation, and of the +spirit of the age, which is ever reflected in the operations of the +human mind whatever may be their direction. + +From the time when man, in interrogating nature, began to experiment or +to produce phenomena under definite conditions, and to collect and +record the fruits of his experience--so that investigation might no +longer be restricted by the short limits of a single life--the +philosophy of nature laid aside the vague and poetic forms with which +she had at first been clothed, and has adopted a more severe character. + +The history of science teaches us how inexact and incomplete +observations have led, through false inductions, to that great number +of erroneous physical views which have been perpetuated as popular +prejudices among all classes of society. Thus, side by side with a solid +and scientific knowledge of phenomena, there has been preserved a system +of pretended results of observation, the more difficult to shake because +it takes no account of any of the facts by which it is overturned. + +This empiricism--melancholy inheritance of earlier times--invariably +maintains whatever axioms it has laid down; it is arrogant, as is +everything that is narrow-minded; while true physical philosophy, +founded on science, doubts because it seeks to investigate +thoroughly--distinguishes between that which is certain and that which +is simply probable--and labours incessantly to bring its theories nearer +to perfection by extending the circle of observation. This assemblage of +incomplete dogmas bequeathed from one century to another, this system of +physics made up of popular prejudices, is not only injurious because it +perpetuates error with all the obstinacy of ill-observed facts, but also +because it hinders the understanding from rising to the level of great +views of nature. + +Instead of seeking to discover the _mean_ state around which, in the +midst of apparent independence and irregularity, the phenomena really +and invariably oscillate, this false science delights in multiplying +apparent exceptions to the dominion of fixed laws, and seeks, in organic +forms and the phenomena of nature, other marvels than those presented by +internal progressive development, and by regular order and succession. +Ever disinclined to recognise in the present the analogy of the past, it +is always disposed to believe the order of nature suspended by +perturbations, of which it places the seat, as if by chance, sometimes +in the interior of the earth, sometimes in the remote regions of space. + + +_II.--The Inductive Method_ + +The generalisation of laws which were first applied to smaller groups of +phenomena advances by successive gradations, and their empire is +extended, and their evidence strengthened, so long as the reasoning +process is directed to really analogous phenomena. Empirical +investigation begins by single perceptions, which are afterwards classed +according to their analogy or dissimilarity. Observation is succeeded at +a much later epoch by experiment, in which phenomena are made to arise +under conditions previously determined on by the experimentalist, guided +by preliminary hypotheses, or a more or less just intuition of the +connection of natural objects and forces. + +The results obtained by observation and experiment lead by the path of +induction and analogy to the discovery of empirical laws, and these +successive phases in the application of human intellect have marked +different epochs in the life of nations. It has been by adhering closely +to this inductive path that the great mass of facts has been accumulated +which now forms the solid foundation of the natural sciences. + +Two forms of abstraction govern the whole of this class of +knowledge--_viz._, the determination of quantitative relations, +according to number and magnitude; and relations of quality, embracing +the specific properties of heterogeneous matter. + +The first of these forms, more accessible to the exercise of thought, +belongs to the domain of mathematics; the other, more difficult to +seize, and apparently more mysterious, to that of chemistry. In order to +submit phenomena to calculation, recourse is had to a hypothetical +construction of matter by a combination of molecules and atoms whose +number, form, position, and polarity determine, modify, and vary the +phenomena. + +We are yet very far from the time when a reasonable hope could be +entertained of reducing all that is perceived by our senses to the unity +of a single principle; but the partial solution of the problem--the +tendency towards a general comprehension of the phenomena of the +universe--does not the less continue to be the high and enduring aim of +all natural investigation. + + +_III.--Distribution of Matter in Space_ + +A physical cosmography, or picture of the universe, should begin, not +with the earth, but with the regions of space--the distribution of +matter in the universe. + +We see matter existing in space partly in the form of rotating and +revolving spheroids, differing greatly in density and magnitude, and +partly in the form of self-luminous vapour dispersed in shining nebulous +spots or patches. The nebulae present themselves to the eye in the form +of round, or nebulous discs, of small apparent magnitude, either single +or in pairs, which are sometimes connected by a thread of light; when +their diameters are greater their forms vary--some are elongated, others +have several branches, some are fan-shaped, some annular, the ring being +well defined and the interior dark. They are supposed to be undergoing +various and progressive changes of form, as condensation proceeds around +one or more nuclei in conformity with the laws of gravitation. Between +two and three thousand of such unresolvable nebulae have already been +counted, and their positions determined. + +If we leave the consideration of the attenuated vaporous matter of the +immeasurable regions of space, whether existing in a dispersed state as +a cosmical ether without form or limits, or in the shape of nebulae, and +pass to those portions of the universe which are condensed into solid +spheres or spheroids, we approach a class of phenomena exclusively +designated as stars or as the sidereal universe. Here, too, we find +different degrees of solidity or density in the agglomerated matter. + +If we compare the regions of space to one of the island-studded seas of +our planet, we may imagine we see matter distributed in groups, whether +of unresolvable nebulae of different ages condensed around one or more +nuclei, or in clusters of stars, or in stars scattered singly. Our +cluster of stars, or the island in space to which we belong, forms a +lens-shaped, flattened, and everywhere detached stratum, whose major +axis is estimated at seven or eight hundred, and its minor axis at a +hundred and fifty times, the distance of Sirius. If we assume that the +parallax of Sirius does not exceed that accurately determined for the +brightest stars in Centaur (0.9128 sec.), it will follow that light +traverses one distance of Sirius in three years, while nine years and a +quarter are required for the transmission of the light of the star 61 +Cygni, whose considerable proper motion might lead to the inference of +great proximity. + +Our cluster of stars is a disc of comparatively small thickness divided, +at about a third its length, into two branches; we are supposed to be +near this division, and nearer to the region of Sirius than to that of +the constellation of the Eagle; almost in the middle of the starry +stratum in the direction of its thickness. + +The place of our solar system and the form of the whole lens are +inferred from a kind of scale--_i.e._, from the different number of +stars seen in equal telescopic fields of view. The greater or less +number of stars measures the relative depth of the stratum in different +directions; giving in each case, like the marks on a sounding-line, the +comparative length of visual ray required to reach the bottom; or, more +properly, as above and below do not here apply, the outer limit of the +sidereal stratum. + +In the direction of the major axis, where the greater number of stars +are placed behind each other, the remoter ones appear closely crowded +together, and, as it were, united by a milky radiance, and present a +zone or belt projected on the visible celestial vault. This narrow belt +is divided into branches; and its beautiful, but not uniform brightness, +is interrupted by some dark places. As seen by us on the apparent +concave celestial sphere, it deviates only a few degrees from a great +circle, we being near the middle of the entire starry cluster, and +almost in the plane of the Milky Way. If out planetary system were far +outside the cluster, the Milky Way would appear to telescopic vision as +a ring, and at a still greater distance as a resolvable disc-shaped +nebula. + + +_IV.--On Earth History_ + +The succession and relative age of different geological formations are +traced partly by the order of superposition of sedimentary strata, of +metamorphic beds, and of conglomerates, but most securely by the +presence of organic remains and their diversities of structure. In the +fossiliferous strata are inhumed the remains of the floras and faunas of +past ages. As we descend from stratum to stratum to study the relations +of superposition, we ascend in the order of time, and new worlds of +animal and vegetable existence present themselves to the view. + +In our ignorance of the laws under which new organic forms appear from +time to time upon the surface of the globe, we employ the expression +"new creations" when we desire to refer to the historical phenomena of +the variations which have taken place at intervals in the animals and +plants that have inhabited the basins of the primitive seas and the +uplifted continents. + +It has sometimes happened that extinct species have been preserved +entire, even to the minutest details of their tissues and articulations. +In the lower beds of the Secondary Period, the lias of Lyme Regis, a +sepia has been found so wonderfully preserved that a part of the black +fluid with which the animal was provided myriads of years ago to conceal +itself from its enemies has actually served at the present time to draw +its picture. In other cases such traces alone remain as the impression +which the feet of animals have left on wet sand or mud over which they +passed when alive, or the remains of their undigested food (coprolites). + +The analytical study of the animal and vegetable kingdoms of the +primitive world has given rise to two distinct branches of science; one +purely morphological, which occupies itself in natural and physiological +descriptions, and in the endeavour to fill up from extinct forms the +chasms which present themselves in the series of existing species; the +other branch, more especially geological considers the relations of the +fossil remains to the superposition and relative age of the sedimentary +beds in which they are found. The first long predominated; and the +superficial manner which then prevailed of comparing fossil and existing +species led to errors of which traces still remain in the strange +denominations which were given to certain natural objects. Writers +attempted to identify all extinct forms with living species, as, in the +sixteenth century, the animals of the New World were confounded by false +analogies with those of the Old. + +In studying the relative age of fossils by the order of superposition of +the strata in which they are found, important relations have been +discovered between families and species (the latter always few in +numbers) which have disappeared and those which are still living. All +observations concur in showing that the fossil floras and faunas differ +from the present animal and vegetable forms the more widely in +proportion as the sedimentary beds to which they belong are lower, or +more ancient. + +Thus great variations have successively taken place in the general +types of organic life, and these grand phenomena, which were first +pointed out by Cuvier, offer numerical relations which Deshayes and +Lyell have made the object of researches by which they have been +conducted to important results, especially as regards the numerous and +well-preserved fossils of the Tertiary formation. Agassiz, who has +examined 1,700 species of fossil fishes, and who estimates at 8,000 the +number of living species which have been described, or which are +preserved in our collections, affirms that, with the exception of one +small fossil fish peculiar to the argillaceous geodes of Greenland, he +has never met in the Transition, Secondary, or Tertiary strata with any +example of this class specifically identical with any living fish; and +he adds the important remark that even in the lower Tertiary formations +a third of the fossil fishes of the _calcaire grossier_ and of the +London clay belong to extinct families. + +We have seen that fishes, which are the oldest vertebrates, first appear +in the Silurian strata, and are found in all the succeeding formations +up to the birds of the Tertiary Period. Reptiles begin in like manner in +the magnesian limestone, and if we now add that the first mammalia are +met with in Oolite, the Stonefield slate; and that the first remains of +birds have been found in the deposits of the cretaceous period, we shall +have indicated the inferior limits, according to our present knowledge, +of the four great divisions of the vertebrates. + +In regard to invertebrate animals, we find corals and some shells +associated in the oldest formations with very highly organised +cephalopodes and crustaceans, so that widely different orders of this +part of the animal kingdom appear intermingled; there are, nevertheless, +many isolated groups belonging to the same order in which determinate +laws are discoverable. Whole mountains are sometimes found to consist of +a single species of fossil goniatites, trilobites, or nummulites. + +Where different genera are intermingled, there often exists a +systematic relation between the series of organic forms and the +superposition of the formations; and it has been remarked that the +association of certain families and species follows a regular law in the +superimposed strata of which the whole constitutes one formation. It has +been found that the waters in the most distant parts of the globe were +inhabited at the same epochs by testaceous animals corresponding, at +least in generic character, with European fossils. + +Strata defined by their fossil contents, or by the fragments of other +rocks which they include, form a geological horizon by which the +geologist may recognise his position, and obtain safe conclusions in +regard to the identity or relative antiquity of formations, the +periodical repetition of certain strata--their parallelism--or their +entire suppression. If we would thus comprehend in its greatest +simplicity the general type of the sedentary formations, we find in +proceeding successively from below upwards: (1) The Transition group, +including the Silurian and Devonian (Old Red Sandstone) systems; (2) the +Lower Trias, comprising mountain limestone, the coal measures, the lower +new red sandstone, and the magnesian limestone; (3) the Upper Trias, +composing the bunter, or variegated sandstone, the muschelkalk, and the +Keuper sandstone; (4) the Oolitic, or Jurassic series, including Lias; +(5) the Cretaceous series; (6) the Tertiary group, as represented in its +three stages by the _calcaire grossier_ and other beds of the Paris +basin, the lignites, or brown coal of Germany, and the sub-Apennine +group of Italy. + +To these succeed transported soils (_alluvium_), containing the gigantic +bones of ancient mammalia, such as the mastodons, the dinotherium, and +the megatheroid animals, among which is the mylodon of Owen, an animal +upwards of eleven feet in length, allied to the sloth. Associated with +these extinct species are found the fossil remains of animals still +living: elephants, rhinoceroses, oxen, horses, and deer. Near Bogota, at +an elevation of 8,200 French feet above the level of the sea, there is a +field filled with the bones of mastodon (_Campo de Gigantes_), in which +I have had careful excavations made. The bones found on the table-lands +of Mexico belong to the true elephants of extinct species. The minor +range of the Himalaya, the Sewalik hills, contain, besides numerous +mastodons, the sivatherium and the gigantic land-tortoise +(_Colossochelys_), more than twelve feet in length and six in height, as +well as remains belonging to still existing species of elephants, +rhinoceroses, and giraffes. It is worthy of notice that these fossils +are found in a zone which enjoys the tropical climate supposed to have +prevailed at the period of the mastodons. + + +_V.--The Permanence of Science_ + +It has sometimes been regarded as a discouraging consideration that, +while works of literature being fast-rooted in the depths of human +feeling, imagination and reason suffer little from the lapse of time, it +is otherwise with works which treat of subjects dependent on the +progress of experimental knowledge. The improvement of instruments, and +the continued enlargement of the field of observation, render +investigations into natural phenomena and physical laws liable to become +antiquated, to lose their interest, and to cease to be read. + +Let none who are deeply penetrated with a true and genuine love of +nature, and with a lively appreciation of the true charm and dignity of +the study of her laws, ever view with discouragement or regret that +which is connected with the enlargement of the boundaries of our +knowledge. Many and important portions of this knowledge, both as +regards the phenomena of the celestial spaces and those belonging to our +own planet, are already based on foundations too firm to be lightly +shaken; although in other portions general laws will doubtless take the +place of those which are more limited in their application, new forces +will be discovered, and substances considered as simple will be +decomposed, while others will become known. + + + + +JAMES HUTTON + +The Theory of the Earth + + James Hutton, the notable Scotch geologist, was born at Edinburgh + on June 3, 1726. In 1743 he was apprenticed to a Writer to the + Signet; but his apprenticeship was of short duration and in the + following year he began to study medicine at Edinburgh University, + and in 1749 graduated as an M.D. Later he determined to study + agriculture, and went, in 1752, to live with a Norfolk farmer to + learn practical farming. He did not devote himself entirely to + agriculture, but gave a considerable amount of his time to chemical + and geological researches. His geological researches culminated in + his great work, "The Theory of the Earth," published at Edinburgh + in 1795. In this work he propounds the theory that the present + continents have been formed at the bottom of the sea by the + precipitation of the detritus of former continents, and that the + precipitate had been hardened by heat and elevated above the sea by + the expansive power of heat. He died on March 26, 1797. Other works + are his "Theory of Rain," "Elements of Agriculture," "Natural + Philosophy," and "Nature of Coal." + + +_I.--Origin and Consolidation of the Land_ + +The solid surface of the earth is mainly composed of gravel, of +calcareous, and argillaceous strata. Sand is separated by streams and +currents, gravel is formed by the attrition of stones agitated in water, +and argillaceous strata are deposited by water containing argillaceous +material. Accordingly, the solid earth would seem to have been mainly +produced by water, wind, and tides, and this theory is confirmed by the +discovery that all the masses of marble and limestone are composed of +the calcareous matter of marine bodies. All these materials were, in the +first place, deposited at the bottom of the sea, and we have to +consider, firstly, how they were consolidated; and secondly, how they +came to be dry land, elevated above the sea. + +It is plain that consolidation may have been effected either through +the concretion of substances dissolved in water or through fusion by +fire. Consolidation through the concretion of substances dissolved in +the sea is unlikely, for, in the first place, there are strata, such as +siliceous matter, which are insoluble, and which could not therefore +have been in solution; and, in the second place, the appearance of the +strata is contrary to this supposition. Consolidation was probably +effected by heat and fusion. All the substances in the earth may be +rendered fluid by heat, and all the appearances in the earth's crust are +consistent with the consolidation and crystallisation of fused +substances. Not only so, but we find rents and separations and veins in +the strata, such as would naturally occur in strata consolidated by the +cooling of fused masses, and other phenomena pointing to fusion by heat. +We may conclude, then, that all the solid strata of the globe have been +hardened from a state of fusion. + +But how were these strata raised up from the bottom of the sea and +transformed into dry land? Even as heat was the consolidating power, so +heat was also probably the elevating power. The power of heat for the +expansion of bodies is, as we know, unlimited, and the expansive power +of heat was certainly competent to raise the strata above the sea. Heat +was certainly competent, and if we examine the crust of the earth we +find evidence that heat was used. + +If the strata cemented by the heat of fusion were created by the +expansive power of heat acting from below, we should expect to find +every species of fracture, dislocation, and contortion in those bodies, +and every degree of departure from a horizontal towards a vertical +position. And this is just what we do find. From horizontal, the strata +are frequently found vertical; from continuous, broken, and separated in +every possible direction; and from a plane, bent and doubled. The theory +is confirmed by an examination of the veins and fissures of the earth +which contain matter foreign to the strata they traverse, and evidently +forced into them as a fluid under great pressure. Active volcanoes, and +extinct volcanoes, and the marks everywhere of volcanic action likewise +support the theory of expansion and elevation by heat. A volcano is not +made on purpose to frighten superstitious people into fits of piety and +devotion; it is to be considered as a spiracle of a subterranean +furnace. + +Such being the manner of the formation of the crust of the world, can we +form any judgment of its duration and durability? If we could measure +the rate of the attrition of the present continents, we might estimate +the duration of the older continents whose attrition supplied the +material for the present dry land. But as we cannot measure the +wearing-away of the land, we can merely state generally, first, that the +present dry land required an indefinitely long period for its formation; +second, that the previous dry land which supplied material for its +formation required equal time to make; third, that there is at present +land forming at the bottom of the sea which in time will appear above +the surface; fourth, that we find no vestige of a beginning, or of an +end. + +Granite has in its own nature no claim to originality, for it is found +to vary greatly in its composition. But, further, it is certain that +granite, or a species of the same kind of stone, is found stratified. It +is the _granit feuilletee_ of M. de Sauffure, and, if I mistake not, is +called _gneiss_ by the Germans. Granite being thus found stratified, the +masses of this stone cannot be allowed to any right of priority over the +schistus, its companion in Alpine countries. + +Lack of stratification, then, cannot be considered a proof of primitive +rock. Nor can lack of organized bodies, such as shells, in these rocks, +be considered a proof; for the traces of organized bodies may be +obliterated by the many subsequent operations of the mineral region. In +any case, signs of organized bodies are sometimes found in "primitive" +mountains. + +Nor can metallic veins, found plentifully in "primitive" mountains, +prove anything, for mineral veins are found in various strata. + +We maintain that _all_ the land was produced from fused substances +elevated from the bottom of the sea. But we do not hold that all parts +of the earth have undergone exactly similar and simultaneous +vicissitudes; and in respect to the changes which various parts of the +land have undergone we may distinguish between primary and secondary +strata. Nothing is more certain than that there have been several +repeated operations of the mineralising power exerted upon the strata in +particular places, and all those mineral operations tend to +consolidation. It is quite possible that "primitive" masses which differ +from the ordinary strata of the globe have been twice subjected to +mineral operations, having been first consolidated and raised as land, +and then submerged in order to be again fused and elevated. + + +_II.--The Nature of Mineral Coal_ + +Mineral, or fossil, coal is a species of stratum distinguished by its +inflammable and combustible nature. We find that it differs in respect +to its purity, and also in respect to its inflammability. As is well +known, some coals have almost no earthy ash, some a great deal; and, +again, some coals burn with much smoke and fire, while others burn like +coke. Where, then, did coal come from, and how can we account for its +different species? + +A substance proper for the formation of coaly matter is found in +vegetable bodies. But how did it become mixed with earthy matter? + +Vegetable bodies may be resolved into bituminous or coaly matter either +by means of fire or by means of water. Both may be used by nature in +the formation of coal. + +By the force of subterranean heat vegetable matter may have been charred +at the bottom of the sea, and the oleaginous, bituminous, and fuliginous +substances diffused through the sea as a result of the burning may have +been deposited at the bottom of the sea as coal. Further, the bituminous +matter from the smoke of vegetable substances burned on land would +ultimately be deposited from the atmosphere and settle at the bottom of +the sea. + +Many of the rivers contain in solution an immense quantity of +inflammable vegetable substance, and this is carried into the sea, and +precipitated there. + +From these two sources, then, the sea gets bituminous material, and this +material, condensed and consolidated by compression and by heat, at the +bottom of the sea, would form a black body of a most uniform structure, +breaking with a polished surface, and burning with more or less smoke or +flame in proportion as it be distilled less or more by subterranean +heat. And such a body exactly represents our purest fossil coal, which +gives the most heat and leaves the least ash. + +In some cases the bituminous material in suspension in the sea would be +mixed more or less with argillaceous, calcareous, and other earthy +substances; and these being precipitated along with the bituminous +matter would form layers of impure coal with a considerable amount of +ash. + +But there is still a third source of coal. Vegetable bodies macerated in +water, and consolidated by compression, form a body almost +indistinguishable from some species of coal, as is seen in peat +compressed under a great load of earth; and there can be no doubt that +coal sometimes originates in this way, for much fossil coal shows +abundance of vegetable bodies in its composition. + +There remains only to consider the change in the disposition of coal +strata. Coal strata, which had been originally in a horizontal position, +are now found sometimes standing erect, even perpendicular. This, also, +is consistent with our theory of the earth. Indeed, there is not a +substance in the mineral kingdom in which the action of subterranean +heat is better shown. These strata are evidently a deposit of +inflammable substances which all come originally from vegetable bodies. +In this stage of their formation they must all contain volatile +oleaginous constituents. But some coal strata contain no volatile +constituents, and the disappearance of the volatile oleaginous +substances must have been produced by distillation, proceeding perhaps +under the restraining force of immense compression. + +We cannot doubt that such distillation does take place in the mineral +regions, when we consider that in most places of the earth we find the +evident effects of such distillation in the naphtha and petroleum that +are constantly emitted along with water in certain springs. We have, +therefore, sufficient proof of this operation of distillation. + + +_III.--The Disintegration and Dissolution of Land_ + +Whether we examine the mountain or the plain, whether we consider the +disintegration of the rocks or the softer strata of the earth, whether +we regard the shores of seas or the central plains of continents, +whether we contemplate fertile lands or deserts, we find evidence of a +general dissolution and decay of the solid surface of the globe. Every +great river and deep valley gives evidence of the attrition of the land. +The purpose of the dry land is to sustain a system of plants and +animals; and for this purpose a soil is required, and to make a soil the +solid strata must be crumbled down. The earth is nothing more than an +indefinite number of soils and situations suitable for various animals +and plants, and it must consist of both solid rock and tender earth, of +both moist and dry districts; for all these are requisite for the world +we inhabit. + +But not only is the solid rock crumbling into soil by the action of air +and water, but the soil gradually progresses towards the sea, and sooner +or later the sea must swallow up the land. Vegetation and masses of +solid rock retard the seaward flow of the soil; but they merely retard, +they cannot wholly prevent. In proportion as the mountains are +diminished, the haugh, or plain, between them grows more wide, and also +on a lower level; but while there is a river running on a plain, and +floods produced in the seasons of rain, there is nothing stable in the +constitution of the surface of the land. + +The theory of the earth which I propound is founded upon the great +catastrophes that can happen to the earth. It supposes strata raised +from the bottom of the sea and elevated into mountainous continents. +But, between the catastrophes, it requires nothing further than the +ordinary everyday effects of air and water. Every shower of rain, every +stream, participates in the dissolution of the land, and helps to +transport to the sea the material for future continents. + +The prodigious waste of the land we see in places has seemed to some to +require some other explanation; but I maintain that the natural +operations of air and water would suffice in time to produce the effects +observed. It is true that the wastage would be slow; but slow +destruction of rock with gradual formation of soil is just what is +required in the economy of nature. A world sustaining plants and animals +requires continents which endure for more than a day. + +If this continent of land, first collected in the sea, is to remain a +habitable earth, and to resist the moving waters of the globe, certain +degrees of solidity or consolidation must be given to that collection of +loose materials; and certain degrees of hardness must be given to +bodies which are soft and incoherent, and consequently so extremely +perishable in the situation in which they are now placed. + +But, at the same time that this earth must have solidity and hardness to +resist the sudden changes which its moving fluids would occasion, it +must be made subject to decay and waste upon the surface exposed to the +atmosphere; for such an earth as were made incapable of change, or not +subject to decay, would not afford that fertile soil which is required +in the system of this world--a soil on which depends the growth of +plants and life of animals--the end of its intention. + +Now, we find this earth endued precisely with such degree of hardness +and consolidation as qualifies it at the same time to be a fruitful +earth, and to maintain its station with all the permanency compatible +with the nature of things, which are not formed to remain unchangeable. + +Thus we have a view of the most perfect wisdom in the contrivance of +that constitution by which the earth is made to answer, in the best +manner possible, the purpose of its intention, that is, to maintain and +perpetuate a system of vegetation, or the various races of useful +plants, or a system of living animals, which are in their turn +subservient to a system still infinitely more important--I mean a system +of intellect. Without fertility in the earth, many races of plants and +animals would soon perish, or be extinct; and with permanency in our +land it were impossible for the various tribes of plants and animals to +be dispersed over the surface of a changing earth. The fact is that +fertility, adequate to the various ends in view, is found in all the +quarters of the world, or in every country of the earth; and the +permanency of our land is such as to make it appear unalterable to +mankind in general and even to impose upon men of science, who have +endeavoured to persuade us that this earth is not to change. + +Nothing but supreme power and wisdom could have reconciled those two +opposite ends of intention, so as both to be equally pursued in the +system of nature, and so equally attained as to be imperceptible to +common observation, and at the same time a proper object of the human +understanding. + + + + +LAMARCK + +Zoological Philosophy + + Jean Baptiste de Monet, Chevalier de Lamarck, was born in Picardy, + France, Aug. I, 1744, the cadet of an ancient but impoverished + house. It was his father's desire that he should enter the Church, + but his inclination was for a military life; and having, at the age + of seventeen, joined the French army under De Broglie, he had + within twenty-four hours the good fortune so to distinguish himself + as to win his commission. When the Museum of Natural History was + brought into existence in 1794 he was sufficiently well-known as a + naturalist to be entrusted with the care of the collections of + invertebrates, comprising insects, molluscs, polyps, and worms. + Here he continued to lecture until his death in 1829. Haeckel, + classifying him in the front rank with Goethe and Darwin, + attributes to him "the imperishable glory of having been the first + to raise the theory of descent to the rank of an independent + scientific theory." The form of his theory was announced in 1801, + but was not given in detail to the world until 1809, by the + publication of his "Zoological Philosophy" ("Philosophie + Zoologique"). The Lamarckian theory of the hereditary transmission + of characters acquired by use, disuse, etc., has still a following, + though it is controverted by the schools of Darwin and Weissmann. + Lamarck died on December 18, 1829. + + +_I.--The Ladder of Life_ + +If we look backwards down the ladder of animal forms we find a +progressive degradation in the organisation of the creatures comprised; +the organisation of their bodies becomes simpler, the number of their +faculties less. This well-recognised fact throws a light upon the order +in which nature has produced the animals; but it leaves unexplained the +fact that this gradation, though sustained, is irregular. The reason +will become clear if we consider the effects produced by the infinite +diversity of conditions in different parts of the globe upon the +general form, the limbs, and the very organisation of the animals in +question. + +It will, in fact, be evident that the state in which we find all animals +is the product, on the one hand, of the growing composition of the +organisation which tends to form a regular gradation; and that, for the +rest, it results from a multitude of circumstances which tend +continually to destroy the regularity of the gradation in the +increasingly composite nature of the organism. + +Not that circumstances can effect any modification directly. But changed +circumstances produce changed wants, changed wants changed actions. If +the new wants become constant the animals acquire new habits, which are +no less constant than the wants which gave rise to them. And such new +habits will necessitate the use of one member rather than another, or +even the cessation of the use of a member which has lost its utility. + +We will look at some familiar examples of either case. Among vegetables, +which have no actions, and therefore no habits properly so called, great +differences in the development of the parts do none the less arise as a +consequence of changed circumstances; and these differences cause the +development of certain of them, while they attenuate others and cause +them to disappear. But all this is caused by changes in the nutrition of +the plant, in its absorptions and transpirations, in the quantity of +heat and light, of air and moisture, which it habitually receives; and, +lastly, by the superiority which certain of its vital movements may +assert over the others. There may arise between individuals of the same +species, of which some are placed in favourable, others amid +unfavourable, conditions, a difference which by degrees becomes very +notable. + +Suppose that circumstances keep certain individuals in an ill-nourished +or languid state. Their internal organisation will at length be +modified, and these individuals will engender offspring which will +perpetuate the modifications thus acquired, and thus will in the end +give place to a race quite distinct from that of which the individual +members come together always under circumstances favourable to their +development. + +For instance, if a seed of some meadow flower is carried to dry and +stony ground, where it is exposed to the winds and there germinates, the +consequence will be that the plant and its immediate offspring, being +always ill-nourished, will give rise to a race really different from +that which lives in the field; yet this, none the less, will be its +progenitor. The individuals of this race will be dwarfed; and their +organs, some being increased at the expense of the rest, will show +distinctive proportions. What nature does in a long time we do every day +ourselves. Every botanist knows that the vegetables transplanted to our +gardens out of their native soil undergo such changes as render them at +last unrecognisable. + +Consider, again, the varieties among our domestic fowls and pigeons, all +of them brought into existence by being raised in diverse circumstances +and different countries, and such as might be sought in vain in a state +of nature. It is matter of common knowledge that if we raise a bird in a +cage, and keep it there for five or six years, it will be unable to fly +if restored to liberty. There has, indeed, been no change as yet in the +form of its members; but if for a long series of generations individuals +of the same race had been kept caged for a considerable time, there is +no room for doubt that the very form of their limbs would little by +little have undergone notable alteration. Much more would this be the +case if their captivity had been accompanied by a marked change of +climate, and if these individuals had by degrees accustomed themselves +to other sorts of food and to other measures for acquiring it. Such +circumstances, taken constantly together, would have formed insensibly a +new and clearly denned race. + +The following example shows, in regard to plants, how the change of +some important circumstance may tend to change the various parts of +these living bodies. + +So long as the _ranunculus aquatilis_, the water buttercup, is under +water its leaves are all finely indented, and the divisions are +furnished with capillaries; but as soon as the stalk of the plant +reaches the surface the leaves, which develop in the air, are broadened +out, rounded, and simply lobed. If the plant manages to spring up in a +soil that is merely moist, and not covered with water, the stems will be +short, and none of the leaves will show these indentations and +capillaries. You have then the _ranunculus hederaceus_, which botanists +regard as a distinct species. + +Among animals changes take place more slowly, and it is therefore more +difficult to determine their cause. The strongest influence, no doubt, +is that of environment. Places far apart are different, and--which is +too commonly ignored--a given place changes its climate and quality with +time, though so slowly in respect of human life that we attribute to it +perfect stability. Hence it arises that we have not only extreme +changes, but also shadowy ones between the extremes. + +Everywhere the order of things changes so gradually that man cannot +observe the change directly, and the animal tribes in every place +preserve their habits for a long time; whence arises the apparent +constancy of what we call species--a constancy which has given birth in +us to the idea that these races are as old as nature. + +But the surface of the habitable globe varies in nature, situation, and +climate, in every variety of degrees. The naturalist will perceive that +just in proportion as the environment is notably changed will the +species change their characters. + +It must always be recognised: + +(1) That every considerable and constant change in the environment of a +race of animals works a real change in their wants. + +(2) That every change in their wants necessitates new actions to supply +them, and consequently new habits. + +(3) That every new want calling for new actions for its satisfaction +affects the animal in one of two ways. Either it has to make more +frequent use of some particular member, and this will develop the part +and cause it to increase in size; or it must employ new members which +will grow in the animal insensibly in response to the inward yearning to +satisfy these wants. And this I will presently prove from known facts. + +How the new wants have been able to attain satisfaction, and how the new +habits have been acquired, it will be easy to see if regard be had to +the two following laws, which observation has always confirmed. + + FIRST LAW.--In every animal which has not arrived at the term of + its developments, the more frequent and sustained use of any organ + strengthens, develops, and enlarges that organ, and gives it a + power commensurate with the duration of this employment of it. On + the other hand, constant disuse of such organ weakens it by + degrees, causes it to deteriorate, and progressively diminishes its + faculties, so that in the end it disappears. + + SECOND LAW.--All qualities naturally acquired by individuals as the + result of circumstances to which their race is exposed for a + considerable time, or as a consequence of a predominant employment + or the disuse of a certain organ, nature preserves to individual + offspring; provided that the acquired modifications are common to + the two sexes, or, at least, to both parents of the individual + offspring. + +Naturalists have observed that the members of animals are adapted to +their use, and thence have concluded hitherto that the formation of the +members has led to their appropriate employment. Now, this is an error. +For observation plainly shows that, on the contrary, the development of +the members has been caused by their need and use; that these have +caused them to come into existence where they were wanting. + +But let us examine the facts which bear upon the effects of employment +or disuse of organs resulting from the habits which a race has been +compelled to form. + + +_II.--The Penalties of Disuse_ + +Permanent disuse of an organ as a consequence of acquired habits +gradually impoverishes it, and in the end causes it to disappear, or +even annihilates it altogether. + +Thus vertebrates, which, in spite of innumerable particular +distinctions, are alike in the plan of their organisation, are generally +armed with teeth. Yet those of them which by circumstances have acquired +the habit of swallowing their prey without mastication have been liable +to leave their teeth undeveloped. Consequently, the teeth have either +remained hidden between the bony plates of the jaws, or have even been, +in the course of time, annihilated. + +The whale was supposed to have no teeth at all till M. Geoffrey found +them hidden in the jaws of the foetus. He has also found in birds the +groove in which teeth might be placed, but without any trace of the +teeth themselves. A similar case to that of the whale is the ant-eater +(_nyomecophaga_), which has long given up the practice of mastication. + +Eyes in the head are an essential part of the organisation of +vertebrates. Yet the mole, which habitually makes no use of the sense of +sight, has eyes so small that they can hardly be seen; and the aspalax, +whose habits-resemble a mole's, has totally lost its sight, and shows +but vestiges of eyes. So also the proteus, which inhabits dark caves +under water. + +In such cases, since the animals in question belong to a type of which +eyes are an essential part, it is clear that the impoverishment, and +even the total disappearance, of these organs are the results of long +continued disuse. + +With hearing, the case is otherwise. Sound traverses everything. +Therefore, wherever an animal dwells it may exercise this faculty. And +so no vertebrate lacks it, and we never find it re-appearing in any of +the lower ranges. Sight disappears, re-appears, and disappears again, +according as circumstances deny or permit its exercise. + +Four legs attached to its skeleton are part of the reptile type; and +serpents, particularly as between them and the fishes come the +batrachians--frogs, etc.--ought to have four legs. + +But serpents, having acquired the habit of gliding along the ground, and +concealing themselves amid the grass, their bodies, as a consequence of +constantly repeated efforts to lengthen themselves out in order to pass +through narrow passages, have acquired considerable length of body which +is out of all proportion to their breadth. + +Now, feet would have been useless to these animals, and consequently +would have remained unemployed; for long legs would have interfered with +their desire to go on their bellies; and short legs, being limited in +number to four, would have been incapable of moving their bodies. Thus +total disuse among these races of animals has caused the parts which +have fallen into disuse totally to disappear. + +Many insects, which by their order and genus should have wings, lack +them more or less completely for similar reasons. + + +_III.--The Advantages of Use_ + +The frequent use of an organ, if constant and habitual, increases its +powers, develops it, and makes it acquire dimensions and potency such +as are not found among animals which use it less. + +Of this principle, the web-feet of some birds, the long legs and neck of +the stork, are examples. Similarly, the elongated tongue of the +ant-eater, and those of lizards and serpents. + +Such wants, and the sustained efforts to satisfy them, have also +resulted in the displacement of organs. Fishes which swim habitually in +great masses of water, since they need to see right and left of them, +have the eyes one upon either side of the head. Their bodies, more or +less flat, according to species, have their edges perpendicular to the +plane of the water; and their eyes are so placed as to be one on either +side of the flattened body. But those whose habits bring them constantly +to the banks, especially sloping banks, have been obliged to lie over +upon the flattened surface in order to approach more nearly. In this +position, in which more light falls on the upper than on the under +surface, and their attention is more particularly fixed upon what is +going on above than on what is going on below them, this want has forced +one of the eyes to undergo a kind of displacement, and to keep the +strange position which it occupies in the head of a sole or a turbot. +The situation is not symmetrical because the mutation is not complete. +In the case of the skate, however, it is complete; for in these fish the +transverse flattening of the body is quite horizontal, no less than that +of the head. And so the eyes of a skate are not only placed both of them +on the upper surface, but have become symmetrical. + +Serpents need principally to see things above them, and, in response to +this need, the eyes are placed so high up at the sides of the head that +they can see easily what is above them on either side, while they can +see in front of them but a very little distance. To compensate for this, +the tongue, with which they test bodies in their line of march, has been +rendered by this habit thin, long, and very contractile, and even, in +most species, has been split so as to be able to test more than one +object at a time. The same custom has resulted similarly in the +formation of an opening at the end of the muzzle by which the tongue may +be protruded without any necessity for the opening of the jaws. + +The effect of use is curiously illustrated in the form and figure of the +giraffe. This animal, the largest of mammals, is found in the interior +of Africa, where the ground is scorched and destitute of grass, and has +to browse on the foliage of trees. From the continual stretching thus +necessitated over a great space of time in all the individuals of the +race, it has resulted that the fore legs have become longer than the +hind legs, and that the neck has become so elongated that the giraffe, +without standing on its hind legs, can raise its head to a height of +nearly twenty feet. Observation of all animals will furnish similar +examples. + +None, perhaps, is more striking than that of the kangaroo. This animal, +which carries its young in an abdominal pouch, has acquired the habit of +carrying itself upright upon its hind legs and tail, and of moving from +place to place in a series of leaps, during which, in order not to hurt +its little ones, it preserves its upright posture. Observe the result. + +(1) Its front limbs, which it uses very little, resting on them only in +the instant during which it quits its erect posture, have never acquired +a development in proportion to the other parts; they have remained thin, +little, and weak. + +(2) The hind legs, almost continually in action, whether to bear the +weight of the whole body or to execute its leaps, have, on the contrary, +obtained a considerable development; they are very big and very strong. + +(3) Finally, the tail, which we observe to be actively employed, both to +support the animal's weight and to execute its principal movements, has +acquired at its base a thickness and a strength that are extremely +remarkable. + +When the will determines an animal to a certain action, the organs +concerned are forthwith stimulated by a flow of subtle fluids, which are +the determining cause of organic changes and developments. And +multiplied repetitions of such acts strengthen, extend, and even call +into being the organs necessary to them. Now, every change in an organ +which has been acquired by habitual use sufficient to originate it is +reproduced in the offspring if it is common to both the individuals +which have come together for the reproduction of their species. In the +end, this change is propagated and passes to all the individuals which +come after and are submitted to the same conditions, without its being +necessary that they should acquire it in the original manner. + +For the rest, in the union of disparate couples, the disparity is +necessarily opposed to the constant propagation of such qualities and +outward forms. This is why man, who is exposed to such diversity of +conditions, does not preserve and propagate the qualities or the +accidental defects which he has been in the way of acquiring. Such +peculiarities will be produced only in case two individuals who share +them unite; these will produce offspring bearing similar +characteristics, and, if successive generations restrict themselves to +similar unions, a distinct race will then be formed. But perpetual +intermixture will cause all characters acquired through particular +circumstances to disappear. If it were not for the distances which +separate the races of men, such intermixture would quickly obliterate +all national distinctions. + + +_IV.--The Conclusion_ + +Here, then, is the conclusion to which we have come. It is a fact that +every genus and species of animal has its characteristic habits combined +with an organisation perfectly in harmony with them. From the +consideration of this fact one of two conclusions must follow, and that +though neither of them can be proved. + +(1) The conclusion admitted hitherto--that nature (or its Author) in +creating the animals has foreseen all the possible sets of circumstances +in which they would have to live, has given to each species a constant +organisation, and has shaped its parts in a determined and invariable +way so that every species is compelled to live in the districts and the +climates where it is actually formed, and to keep the habits by which it +is actually known. + +(2) My own conclusion--that nature has produced in succession all the +animal species, beginning with the more imperfect, or the simpler, and +ending with the more perfect; that in so doing it has gradually +complicated their organisation; and that of these animals, dispersed +over the habitable globe, every species has acquired, under the +influence of the circumstances amid which it is found, the habits and +modifications of form which we associate with it. + +To prove that the second of these hypotheses is unfounded, it will be +necessary, first, to prove that the surface of the globe never varies in +character, in exposure, situation, whether elevated or sheltered, +climate, etc.; and, secondly, to prove that no part of the animal world +undergoes, even in the course of long periods of time, any modification +through change of circumstances, or as a consequence of a changed manner +of life and action. + +Now, a single fact which establishes that an animal, after a long period +of domestication, differs from the wild stock from which it derives, and +that among the various domesticated members of a species may be found +differences no less marked between individuals which, have been +subjected to one use and those which have been subjected to another, +makes it certain that the former conclusion is not consistent with the +laws of nature, and that the second is. + +Everything, therefore, concurs to prove my assertion, to wit--that it is +not form, whether of the body or of the parts, which gives rise to the +habits of animals and their manner of life; but that, on the contrary, +in the habits, the manner of living, and all the other circumstances of +environment, we have those things which in the course of time have built +up animal bodies with all their members. With new forms new faculties +have been acquired, and little by little nature has come to shape +animals and all living things in their present forms. + + + + +JOHANN LAVATER + +Physiognomical Fragments + + Johann Caspar Lavater, the Swiss theologian, poet, and + physiognomist, was born at Zuerich on November 15, 1741. He began + his public life at the age of twenty-one as a political reformer. + Five years later he appeared as a poet, and published a volume of + poetry which was very favourably received. During the next five + years he produced a religious work, which was considered heretical, + although its mystic, religious enthusiasm appealed to a + considerable audience. His fame, however, rests neither on his + poetry nor on his theology, but on his physiognomical studies, + published in four volumes between 1775-78 under the title + "Physiognomical Fragments for the Advancement of Human Knowledge + and Human Life" ("Physiognomische Fragmente zur Befoerderung des + Menschenkenntniss und Menschenliebe"). The book is diffuse and + inconsequent, but it contains many shrewd observations with respect + to physiognomy and has had no little influence on popular opinion + in this matter. Lavater died on January 2, 1801. + + +_I.--The Truth of Physiognomy_ + +There can be no doubt of the truth of physiognomy. All countenances, all +forms, all created beings, are not only different from each other in +their classes, races, kinds, but are also individually distinct. It is +indisputable that all men estimate all things whatever by their external +temporary superficies--that is to say, by their physiognomy. Is not all +nature physiognomy, superficies and contents, body and spirit, external +effect and internal power? There is not a man who does not judge of all +things that pass through his hands by their physiognomy--there is not a +man who does not more or less, the first time he is in company with a +stranger, observe, estimate, compare, judge him according to +appearances. When each apple, each apricot, has a physiognomy peculiar +to itself, shall man, the lord of the earth, have none? + +Man is the most perfect of all earthly creatures. In no other creature +are so wonderfully united the animal, the intellectual, and the moral. +And man's organisation peculiarly distinguishes him from all other +beings, and shows him to be infinitely superior to all those other +visible organisms by which he is surrounded. His head, especially his +face, convinces the accurate observer, who is capable of investigating +truth, of the greatness and superiority of his intellectual qualities. +The eye, the expression, the cheeks, the mouth, the forehead, whether +considered in a state of entire rest, or during their innumerable +varieties of motion--in fine, whatever is understood by physiognomy--are +the most expressive, the most convincing picture of interior sensations, +desires, passions, will, and of all those properties which so much exalt +moral above animal life. + +Although the physiological, intellectual, and moral are united in man, +yet it is plain that each of these has its peculiar station where it +more especially unfolds itself and acts. + +It is, beyond contradiction, evident that, though physiological or +animal life displays itself through all the body, and especially through +all the animal parts, yet it acts more conspicuously in the arm, from +the shoulder to the ends of the fingers. + +It is not less evident that intellectual life, or the powers of the +understanding and the mind, make themselves most apparent in the +circumference and form of the solid parts of the head, especially the +forehead; though they will discover themselves to the attentive and +accurate eye in every part and point of the human body, by the +congeniality and harmony of the various parts. Is there any occasion to +prove that the power of thinking resides not in the foot, nor in the +hand, nor in the back, but in the head and its internal parts? + +The moral life of man particularly reveals itself in the lines, marks, +and transitions of the countenance. His moral powers and desires, his +irritability, sympathy, and antipathy, his facility of attracting or +repelling the objects that surround him--these are all summed up in, and +painted upon, his countenance when at rest. + +Not only do mental and moral traits evince themselves in the +physiognomy, but also health and sickness; and I believe that by +repeatedly examining the firm parts and outlines of the bodies and +countenances of the sick, disease might be diagnosed, and even that +liability to disease might be predicted in particular cases. + +The same vital powers that make the heart beat and the fingers move, +roof the skull and arch the finger-nails. From the head to the back, +from the shoulder to the arm, from the arm to the hand, from the hand to +the finger, each depends on the other, and all on a determinate effect +of a determinate power. Through all nature each determinate power is +productive of only such and such determinate effects. The finger of one +body is not adapted to the hand of another body. The blood in the +extremity of the finger has the character of the blood in the heart. The +same congeniality is found in the nerves and in the bones. One spirit +lives in all. Each member of the body, too, is in proportion to the +whole of which it is a part. As from the length of the smallest member, +the smallest joint of the finger, the proportion of the whole, the +length and breadth of the body may be found; so also may the form of the +whole be found from the form of each single part. When the head is long, +all is long; when the head is round, all is round; when the head is +square, all is square. + +One form, one mind, one root appertain to all. Each organised body is so +much a whole that, without discord, destruction, or deformity, nothing +can be added or subtracted. Those, therefore, who maintain that +conclusion cannot be drawn from a part to the whole labour under error, +failing to comprehend the harmony of nature. + + +_II.--Physiognomy and the Features_ + +The Forehead. The form, height, arching, proportion, obliquity, and +position of the skull, or bone of the forehead, show the propensity of +thought, power of thought, and sensibility of man. The position, colour, +wrinkles, tension of the skin of the forehead, show the passions and +present state of the mind. The bones indicate the power, the skin the +application of power. + +I consider the outline and position of the forehead to be the most +important feature in physiognomy. We may divide foreheads into three +principal classes--the retreating, the perpendicular, and the +projecting, and each of these classes has a multitude of variations. + +A few facts with respect to foreheads may now be given. + +The higher the forehead, the more comprehension and the less activity. + +The more compressed, short, and firm the forehead, the more compression +and firmness, and the less volatility in the man. + +The more curved and cornerless the outline, the more tender and flexible +the character; and the more rectilinear, the more pertinacious and +severe the character. + +Perfect perpendicularity implies lack of understanding, but gently +arched at top, capacity for cold, tranquil, profound thought. + +A projecting forehead indicates imbecility, immaturity, weakness, +stupidity. + +A retreating forehead, in general, denotes superior imagination, wit, +acuteness. + +A forehead round and prominent above, straight below, and, on the whole, +perpendicular, shows much understanding, life, sensibility, ardour. + +An oblique, rectilinear forehead is ardent and vigorous. + +Arched foreheads appear properly to be feminine. + +A forehead neither too perpendicular nor too retreating, but a happy +mean, indicates the post-perfect character of wisdom. + +I might also state it as an axiom that straight lines considered as +such, and curves considered as such, are related as power and weakness, +obstinacy and flexibility, understanding and sensation. + +I have seen no man with sharp, projecting eyebones who was not inclined +to vigorous thinking and wise planning. + +Yet, even lacking sharpness, a head may be excellent if the forehead +sink like a perpendicular wall upon horizontal eyebrows, and be greatly +rounded towards the temples. + +Perpendicular foreheads, projecting so as not to rest immediately upon +the nose, and small, wrinkled, short, and shining, indicate little +imagination, little understanding, little sensation. + +Foreheads with many angular, knotty protuberances denote perseverance +and much vigorous, firm, harsh, oppressive, ardent activity. + +It is a sure sign of a clear, sound understanding and a good temperament +when the profile of the forehead has two proportionate arches, the lower +of which projects. + +Eyebones with well-marked, firm arches I never saw but in noble and +great men. + +Square foreheads with extensive temples and firm eyebones show +circumspection and steadiness of character. + +Perpendicular wrinkles, if natural, denote application and power. +Horizontal wrinkles and those broken in the middle or at the extremities +generally denote negligence or want of power. + +Perpendicular, deep indentings in the forehead between the eyebrows, I +never met save in men of sound understanding and free and noble minds, +unless there were some positively contradictory feature. + +A blue frontal vein, in the form of a Y, when in an open, smooth, +well-arched forehead, I have only found in men of extraordinary talents +and of ardent and generous character. + +The following are the traits of a perfectly beautiful, intelligent, and +noble forehead. + +In length it must equal the nose, or the under part of the face. In +breadth it must be either oval at the top-like the foreheads of most of +the great men of England--or nearly square. It must be free from +unevenness and wrinkles, yet be able to wrinkle when deep in thought, +afflicted by pain, or moved by indignation. It must retreat above and +project beneath. The eyebones must be simple, horizontal, and, if seen +from above, must present a simple curve. There should be a small cavity +in the centre, from above to below, and traversing the forehead so as to +separate it into four divisions perceptible in a clear descending light. +The skin must be more clear on the forehead than in other parts of the +countenance. + +Foreheads short, wrinkled, and knotty, are incapable of durable +friendship. + +Be not discouraged though a friend, an enemy, a child, or a brother +transgress, for so long as he have a good, well-proportioned, open +forehead there is still hope of improvement. + +THE EYES AND EYEBROWS. Blue eyes are generally more indicative of +weakness and effeminacy than brown or black. Certainly there are many +powerful men with blue eyes, but I find more strength, manhood, thought +with brown. + +Choleric men have eyes of every colour, but rather brown or greenish +than blue. A propensity to green is an almost decisive token of ardour, +fire, and courage. + +Wide open eyes, with the white visible, I have often observed both in +the timid and phlegmatic, and in the courageous and rash. + +Meeting eyebrows were supposed to be the mark of craft, but I do not +believe them to have this significance. Angular, strong, interrupted +eyebrows denote fire and productive activity. The nearer the eyebrows to +the eyes, the more earnest, deep, and firm the character. Eyebrows +remote from each other denote warm, open, quick sensations. White +eyebrows signify weakness; and dark brown, firmness. The motion of the +eyebrows contains numerous expressions, especially of ignoble passions. + +THE NOSE. I have generally considered the nose the foundation or +abutment of the brain, for upon this the whole power of the arch of the +forehead rests. A beautiful nose will never be found accompanying an +ugly countenance. An ugly person may have fine eyes, but not a handsome +nose. + +I have never seen a nose with a broad back, whether arched or +rectilinear, that did not belong to an extraordinary man. Such a nose +was possessed by Swift, Caesar Borgia, Titian, etc. Small nostrils are +usually an indubitable sign of unenterprising timidity. The open, +breathing nostril is as certain a token of sensibility. + +THE MOUTH AND LIPS. The contents of the mind are communicated to the +mouth. How full of character is the mouth! As are the lips, so is the +character. Firm lips, firm character; weak lips, weak character. +Well-defined, large, and proportionate lips, the middle line of which is +equally serpentine on both sides, and easy to be drawn, are never seen +in a bad, mean, common, false, vicious countenance. A lipless mouth, +resembling a single line, denotes coldness, industry, a love of order, +precision, house-wifery, and, if it be drawn upwards at the two ends, +affectation, pretension, vanity, malice. Very fleshy lips have always to +contend with sensuality and indolence. Calm lips, well closed, without +constraint, and well delineated, certainly betoken consideration, +discretion, and firmness. Openness of mouth speaks complaint, and +closeness, endurance. + +THE CHIN. From numerous experiments, I am convinced that the projecting +chin ever denotes something positive, and the retreating something +negative. The presence or absence of strength in man is often signified +by the chin. + +I have never seen sharp indentings in the middle of the chin save in men +of cool understanding, unless when something evidently contradictory +appeared in the countenance. The soft, fat, double chin generally points +out the epicure; and the angular chin is seldom found save in discreet, +well-disposed, firm men. Flatness of chin speaks the cold and dry; +smallness, fear; and roundness, with a dimple, benevolence. + +SKULLS. HOW much may the anatomist see in the mere skull of man! How +much more the physiognomist! And how much more still the anatomist who +is a physiognomist! If shown the bald head of Caesar, as painted by +Rubens or Titian or Michael Angelo, what man would fail to notice the +rocky capacity which characterises it, and to realise that more ardour +and energy must be expected than from a smooth, round, flat head? How +characteristic is the skull of Charles XII.! How different from the +skull of his biographer Voltaire! Compare the skull of Judas with the +skull of Christ, after Holbein, and I doubt whether anyone would fail to +guess which is the skull of the wicked betrayer and which the skull of +the innocent betrayed. And who is unacquainted with the statement in +Herodotus that it was possible on the field of battle to distinguish the +skulls of the effeminate Medes from the skulls of the manly Persians? +Each nation, indeed, has its own characteristic skull. + + +_III.--Nation, Sex, and Family_ + +NATIONAL PHYSIOGNOMY. It is undeniable that there is a national +physiognomy as well as national character. Compare a negro and an +Englishman, a native of Lapland and an Italian, a Frenchman and an +inhabitant of Tierra del Fuego. Examine their forms, countenances, +characters, and minds. This difference will be easily seen, though it +will sometimes be very difficult to describe it scientifically. + +The following infinitely little is what I have hitherto observed in the +foreigners with whom I have conversed. + +I am least able to characterise the French, They have no traits so bold +as the English, nor so minute as the Germans. I know them chiefly by +their teeth and their laugh. The Italians I discover by the nose, small +eyes, and projecting chin. The English by their foreheads and eyebrows. +The Dutch by the rotundity of their heads and the weakness of the hair. +The Germans by the angles and wrinkles round the eyes and in the cheeks. +The Russians by the snub nose and their light-coloured or black hair. + +I shall now say a word concerning Englishmen in particular. Englishmen +have the shortest and best-arched foreheads--that is to say, they are +arched only upwards, and, towards the eyebrows, either gently recline or +are rectilinear. They seldom have pointed, usually round, full noses. +Their lips are usually large, well defined, beautifully curved. Their +chins are round and full. The outline of their faces is in general +large, and they never have those numerous angles and wrinkles by which +the Germans are so especially distinguished. Their complexion is fairer +than that of the Germans. + +All Englishwomen whom I have known personally, or by portrait, appear to +be composed of marrow and nerve. They are inclined to be tall, slender, +soft, and as distant from all that is harsh, rigorous, or stubborn as +heaven is from earth. + +The Swiss have generally no common physiognomy or national character, +the aspect of fidelity excepted. They are as different from each other +as nations the most remote. + +THE PHYSIOGNOMICAL RELATION OF THE SEXES. Generally speaking, how much +more pure, tender, delicate, irritable, affectionate, flexible, and +patient is woman than man. The primary matter of which woman is +constituted appears to account for this difference. All her organs are +tender, yielding, easily wounded, sensible, and receptive; they are made +for maternity and affection. Among a thousand women, there is hardly one +without these feminine characteristics. + +This tenderness and sensibility, the light texture of their fibres and +organs, render them easy to tempt and to subdue, and yet their charms +are more potent than the strength of man. Truly sensible of purity, +beauty and symmetry, woman does not always take time to reflect on +spiritual life, spiritual death, spiritual corruption. + +The woman does not think profoundly; profound thought is the prerogative +of the man; but women feel more. They rule with tender looks, tears, and +sighs, but not with passion and threats, unless they are monstrosities. +They are capable of the sweetest sensibility, the deepest emotion, the +utmost humility, and ardent enthusiasm. In their faces are signs of +sanctity which every man honours. + +Owing to their extreme sensibility and their incapacity for accurate +inquiry and firm decision, they may easily become fanatics. + +The love of women, strong as it is, is very changeable; but their hatred +is almost incurable, and is only to be overcome by persistent and artful +flattery. Men usually see things as a whole, whereas women take more +interest in details. + +Women have less physical courage than men. Man hears the bursting +thunders, views the destructive bolt with serene aspect, and stands +erect amid the fearful majesty of the torrent. But woman trembles at the +lightning and thunder, and seeks refuge in the arms of man. + +Woman is formed for pity and religion; and a woman without religion is +monstrous; and a woman who is a freethinker is more disgusting than a +woman with a beard. + +Woman is not a foundation on which to build. She is the gold, silver, +precious stones, wood, hay, stubble--the materials for building on the +male foundation. She is the leaven, or, more expressly, she is oil to +the vinegar of man. Man singly is but half a man, only half human--a +king without a kingdom. Woman must rest upon the man, and man can be +what he ought to be only in conjunction with the woman. + +Some of the principal physiognomical contrasts may be summarised here. + +Man is the most firm; woman the most flexible. + +Man is the straightest; woman the most bending. + +Man stands steadfast; woman gently retreats. + +Man surveys and observes; woman glances and feels. + +Man is serious; woman is gay. + +Man is the tallest and broadest; woman the smallest and weakest. + +Man is rough and hard; woman is smooth and soft. + +Man is brown; woman is fair. + +The hair of the man is strong and short; the hair of woman is pliant and +long. + +Man has most straight lines; woman most curved. + +The countenance of man, taken in profile, is not so often perpendicular +as that of woman. + +FAMILY PHYSIOGNOMY. The resemblance between parents and children is very +commonly remarkable. Family physiognomical resemblance is as undeniable +as national physiognomical resemblance. To doubt this is to doubt what +is self-evident. + +When children, as they increase in years, visibly increase in their +physical resemblance to their parents, we cannot doubt that resemblance +in character also increases. Howsoever much the character of children +may seem to differ from that of their parents, yet this difference will +be found to be due to great difference in external circumstances. + + + + +JUSTUS VON LIEBIG + +Animal Chemistry + + Baron Freiherr Justus von Liebig, one of the most illustrious + chemists of his age, was born on May 12, 1803, at Darmstadt, + Germany, the son of a drysalter. It was in his father's business + that his interest in chemistry first awoke, and at fifteen he + became an apothecary's assistant. Subsequently, he went to + Erlangen, where he took his doctorate in 1822; and afterwards, in + Paris, was admitted to the laboratory of Gay-Lussac as a private + pupil. In 1824 he was appointed a teacher of chemistry in the + University of Giessen in his native state. Here he lived for + twenty-eight years a quiet life of incessant industry, while his + fame spread throughout Europe. In 1845 he was raised to the + hereditary rank of baron, and seven years later was appointed by + the Bavarian government to the professorship of chemistry in the + University of Munich. Here he died on April 18, 1873. The treatise + on "Animal Chemistry, or Organic Chemistry in its Relations to + Physiology and Pathology," published in 1842, sums up the results + of Liebig's investigations into the immediate products of animal + life. He was the first to demonstrate that the only source of + animal heat is that produced by the oxidation of the tissues. + + +_I.--Chemical Needs of Life_ + +Animals, unlike plants, require highly organised atoms for nutriment; +they can subsist only upon parts of an organism. All parts of the animal +body are produced from the fluid circulating within its organism. A +destruction of the animal body is constantly proceeding, every motion is +the result of a transformation of its structure; every thought, every +sensation is accompanied by a change in the composition of the substance +of the brain. Food is applied either in the increase of the mass of a +structure (nutrition) or in the replacement of a structure wasted +(reproduction). + +Equally important is the continual absorption of oxygen from the +atmosphere. All vital activity results from the mutual action of the +oxygen of the atmosphere and the elements of food. According to +Lavoisier, an adult man takes into his system every year 827 lb. of +oxygen, and yet he does not increase in weight. What, then, becomes of +this oxygen?--for no part of it is again expired as oxygen. The carbon +and hydrogen of certain parts of the body have entered into combination +with the oxygen introduced through the lungs and through the skin, and +have been given out in the form of carbonic acid and the vapour of +water. + +Now, an adult inspires 32-1/2 oz. of oxygen daily; this will convert the +carbon of 24 lb. of blood (80 per cent. water) into carbonic acid. He +must, therefore, take as much nutriment as will supply the daily loss. +And, in fact, it is found that he does so; for the average amount of +carbon in the daily food of an adult man is 14 oz., which requires 37 +oz. of oxygen for its conversion into carbonic acid. The amount of food +necessary for the support of the animal body must be in direct ratio to +the quantity of oxygen taken into the system. A bird deprived of food +dies on the third day; while a serpent, which inspires a mere trace of +oxygen, can live without food for three months. The number of +respirations is less in a state of rest than in exercise, and the amount +of food necessary in both conditions must vary also. + +The capacity of the chest being a constant quantity, we inspire the same +volume of air whether at the pole or at the equator; but the weight of +air, and consequently of oxygen, varies with the temperature. Thus, an +adult man takes into the system daily 46,000 cubic inches of oxygen, +which, if the temperature be 77 deg. F., weighs 32-1/2 oz., but when the +temperature sinks to freezing-point will weigh 35 oz. It is obvious, +also, that in an equal number of respirations we consume more oxygen at +the level of the sea than on a mountain. The quantity of oxygen inspired +and carbonic acid expired must, therefore, vary with the height of the +barometer. In our climate the difference between summer and winter in +the carbon expired, and therefore necessary for food, is as much as +one-eighth. + + +_II.--The Cause of Animal Heat_ + +Now, the mutual action between the elements of food and the oxygen of +the air is the source of animal heat. + +This heat is wholly due to the combustion of the carbon and hydrogen in +the food consumed. Animal heat exists only in those parts of the body +through which arterial blood (and with it oxygen in solution) +circulates; hair, wool, or feathers, do not possess an elevated +temperature. + +As animal heat depends upon respired oxygen, it will vary according to +the respiratory apparatus of the animal. Thus the temperature of a child +is 102 deg. F., while that of an adult is 99-1/2 deg. F. That of birds is higher +than that of quadrupeds or that of fishes or amphibia, whose proper +temperature is 3 deg. F higher than the medium in which they live. All +animals, strictly speaking, are warm-blooded; but in those only which +possess lungs is their temperature quite independent of the surrounding +medium. The temperature of the human body is the same in the torrid as +in the frigid zone; but the colder the surrounding medium the greater +the quantity of fuel necessary to maintain its heat. + +The human body may be aptly compared to the furnace of a laboratory +destined to effect certain operations. It signifies nothing what +intermediate forms the food, or fuel, of the furnace may assume; it is +finally converted into carbonic acid and water. But in order to sustain +a fixed temperature in the furnace we must vary the quantity of fuel +according to the external temperature. + +In the animal body the food is the fuel; with a proper supply of oxygen +we obtain the heat given out during its oxidation or combustion. In +winter, when we take exercise in a cold atmosphere, and when +consequently the amount of inspired oxygen increases, the necessity for +food containing carbon and hydrogen increases in the same ratio; and by +gratifying the appetite thus excited, we obtain the most efficient +protection against the most piercing cold. A starving man is soon frozen +to death; and everyone knows that the animals of prey in the Arctic +regions far exceed in voracity those in the torrid zone. In cold and +temperate climates, the air, which incessantly strives to consume the +body, urges man to laborious efforts in order to furnish the means of +resistance to its action, while in hot climates the necessity of labour +to provide food is far less urgent. + +Our clothing is merely the equivalent for a certain amount of food. + +The more warmly we are clothed the less food we require. If in hunting +or fishing we were exposed to the same degree of cold as the Samoyedes +we could with ease consume ten pounds of flesh, and perhaps half a dozen +tallow candles into the bargain. The macaroni of the Italian, and the +train oil of the Greenlander and the Russian, are fitted to administer +to their comfort in the climate in which they have been born. + +The whole process of respiration appears most clearly developed in the +case of a man exposed to starvation. Currie mentions the case of an +individual who was unable to swallow, and whose body lost 100 lb. in one +month. The more fat an animal contains the longer will it be able to +exist without food, for the fat will be consumed before the oxygen of +the air acts upon the other parts of the body. + +There are various causes by which force or motion may be produced. But +in the animal body we recognise as the ultimate cause of all force only +one cause, the chemical action which the elements of the food and the +oxygen of the air mutually exercise on each other. The only known +ultimate cause of vital force, either in animals or in plants, is a +chemical process. If this be prevented, the phenomena of life do not +manifest themselves, or they cease to be recognisable by our senses. If +the chemical action be impeded, the vital phenomena must take new forms. + +The heat evolved by the combustion of carbon in the body is sufficient +to account for all the phenomena of animal heat. The 14 oz. of carbon +which in an adult are daily converted into carbonic acid disengage a +quantity of heat which would convert 24 lb. of water, at the temperature +of the body, into vapour. And if we assume that the quantity of water +vaporised through the skin and lungs amounts to 3 lb., then we have +still a large quantity of heat to sustain the temperature of the body. + + +_III.--The Chemistry of Blood-Making_ + +Physiologists conceive that the various organs in the body have +originally been formed from blood. If this be admitted, it is obvious +that those substances alone can be considered nutritious that are +capable of being transformed into blood. + +When blood is allowed to stand, it coagulates and separates into a +watery fluid called serum, and into the clot, which consists principally +of fibrine. These two bodies contain, in all, seven elements, among +which sulphur, phosphorus, and nitrogen are found; they contain also the +earth of bones. The serum holds in solution common salt and other salts +of potash and soda, of which the acids are carbonic, phosphoric, and +sulphuric acids. Serum, when heated, coagulates into a white mass called +albumen. This substance, along with the fibrine and a red colouring +matter in which iron is a constituent, constitute the globules of blood. + +Analysis has shown that fibrine and albumen are perfectly identical in +chemical composition. They may be mutually converted into each other. In +the process of nutrition both may be converted into muscular fibre, and +muscular fibre is capable of being reconverted into blood. + +All parts of the animal body which form parts of organs contain +nitrogen. The principal ingredients of blood contain 17 per cent. of +nitrogen, and there is no part of an active organ that contains less +than 17 per cent. of this element. + +The nutritive process is simplest in the case of the carnivora, for +their nutriment is chemically identical in composition with their own +tissues. The digestive apparatus of graminivorous animals is less +simple, and their food contains very little nitrogen. From what +constituents of vegetables is their blood produced? + +Chemical researches have shown that all such parts of vegetables as can +afford nutriment to animals contain certain constituents which are rich +in nitrogen; and experience proves that animals require for their +nutrition less of these parts of plants in proportion as they abound in +the nitrogenised constituents. These important products are specially +abundant in the seeds of the different kinds of grain, and of peas, +beans, and lentils. They exist, however, in all plants, without +exception, and in every part of plants in larger or smaller quantity. +The nitrogenised compounds of vegetables are called vegetable fibrine, +vegetable albumen, and vegetable casein. All other nitrogenised +compounds occurring in plants are either rejected by animals or else +they occur in the food in such very small proportion that they cannot +possibly contribute to the increase of mass in the animal body. + +The chemical analysis of these three substances has led to the +interesting result that they contain the same organic elements, united +in the same proportion by weight; and--which is more remarkable--that +they are identical in composition with the chief constituents of +blood--animal fibrine and animal albumen. By identity, be it remarked, +is not here meant merely similarity, but that even in regard to the +presence and relative amounts of sulphur, phosphorus, and phosphate of +lime no difference can be observed. + +How beautifully simple then, by the aid of these discoveries, appears +the process of nutrition in animals, the formation of their organs, in +which vitality chiefly resides. Those vegetable constituents which are +used by animals to form blood contain the essential ingredients of blood +ready formed. In point of fact, vegetables produce in their organism the +blood of all animals; for the carnivora, in consuming the blood and +flesh of the graminivora, consume, strictly speaking, the vegetable +principles which have served for the nourishment of the latter. In this +sense we may say the animal organism gives to blood only its form; and, +further, that it is incapable of forming blood out of other compounds +which do not contain the chief ingredients of that fluid. + +Animal and vegetable life are, therefore, closely related, for the first +substance capable of affording nutriment to animals is the last product +of the creative energy of vegetables. The seemingly miraculous in the +nutritive power of vegetables disappears in a great degree, for the +production of the constituents of blood cannot appear more surprising +than the occurrence of the principal ingredient of butter in palm-oil +and of horse-fat and train-oil in certain of the oily seeds. + + +_IV.--Food the Fuel of Life_ + +We have still to account for the use in food of substances which are +destitute of nitrogen but are known to be necessary to animal life. Such +substances are starch, sugar, gum, and pectine. In all of these we find +a great excess of carbon, with oxygen and hydrogen in the same +proportion as water. They therefore add an excess of carbon to the +nitrogenised constituents of food, and they cannot possibly be employed +in the production of blood, because the nitrogenised compounds contained +in the food already contain exactly the amount of carbon which is +required for the production of fibrine and albumen. Now, it can be shown +that very little of the excess of this carbon is ever expelled in the +form either of solid or liquid compounds; it must be expelled, +therefore, in the gaseous state. In short, these compounds are solely +expended in the production of animal heat, being converted by the oxygen +of the air into carbonic acid and water. The food of carnivorous animals +does not contain non-nitrogenised matters, so that the carbon and +hydrogen necessary for the production of animal heat are furnished in +them from the waste of their tissues. + +The transformed matters of the organs are obviously unfit for the +further nourishment of the body--that is, for the increase or +reproduction of the mass. They pass through the absorbent and lymphatic +vessels into the veins, and their accumulation in these would soon put a +stop to the nutritive process were it not that the blood has to pass +through a filtering apparatus, as it were, before reaching the heart. +The venous blood, before returning to the heart, is made to pass through +the liver and the kidneys, which separate from it all substances +incapable of contributing to nutrition. The new compounds containing the +nitrogen of the transformed organs, being utterly incapable of further +application in the system, are expelled from the body. Those which +contain the carbon of the transformed tissues are collected in the +gall-bladder as bile, a compound of soda which, being mixed with water, +passes through the duodenum and mixes with chyme. All the soda of the +bile, and ninety-nine-hundredths of the carbonaceous matter which it +contains, retain the capacity of re-absorption by the absorbents of the +small and large intestines--a capacity which has been proved by direct +experiment. + +The globules of the blood, which in themselves can be shown to take no +share in the nutritive process, serve to transport the oxygen which they +give up in their passage through the capillary vessels. Here the current +of oxygen meets with the carbonaceous substances of the transformed +tissues, and converts their carbon into carbonic acid, their hydrogen +into water. Every portion of these substances which escapes this process +of oxidation is sent back into the circulation in the form of bile, +which by degrees completely disappears. + +It is obvious that in the system of the graminivora, whose food contains +relatively so small a proportion of the constituents of blood, the +process of metamorphosis in existing tissues, and consequently their +restoration or reproduction, must go on far less rapidly than in the +carnivora. Otherwise, a vegetation a thousand times as luxuriant would +not suffice for their sustenance. Sugar, gum, and starch, which form so +large a proportion of their food, would then be no longer necessary to +support life in these animals, because in that case the products of +waste, or metamorphosis of organised tissues, would contain enough +carbon to support the respiratory process. + +When exercise is denied to graminivorous and omnivorous animals this is +tantamount to a deficient supply of oxygen. The carbon of the food, not +meeting with a sufficient supply of oxygen to consume it, passes into +other compounds containing a large excess of carbon--or, in other words, +fat is produced. Fat is thus an abnormal production, resulting from a +disproportion of carbon in the food to that of the oxygen respired by +the lungs or absorbed by the skin. Wild animals in a state of nature do +not contain fat. The production of fat is always a consequence of a +deficient supply of oxygen, for oxygen is absolutely indispensable for +the dissipation of excess of carbon in the food. + + +_V.--Animal Life-Chemistry_ + +The substances of which the food of man is composed may be divided into +two classes--into nitrogenised and non-nitrogenised. The former are +capable of conversion into blood, the latter incapable of this +transformation. Out of those substances which are adapted to the +formation of blood are formed all the organised tissues. The other class +of substances in the normal state of health serve to support the process +of respiration. The former may be called the plastic elements of +nutrition; the latter, elements of respiration. + +Among the former we may reckon--vegetable fibrine, vegetable albumen, +vegetable casein, animal flesh, animal blood. + +Among the elements of respiration in our food are--fat, starch, gum, +cane sugar, grape-sugar, sugar of milk, pectine, bassorine, wine, beer, +spirits. + +The nitrogenised constituents of vegetable food have a composition +identical with that of the constituents of the blood. + +No nitrogenised compound the composition of which differs from that of +fibrine, albumen, and casein, is capable of supporting the vital process +in animals. + +The animal organism undoubtedly possesses the power of forming from the +constituents of its blood the substance of its membranes and cellular +tissue, of the nerves and brain, of the organic part of cartilages and +bones. But the blood must be supplied to it ready in everything but its +form--that is, in its chemical composition. If this is not done, a +period is put to the formation of blood, and, consequently, to life. + +The whole life of animals consists of a conflict between chemical forces +and the vital power. In the normal state of the body of an adult these +stand in equilibrium: that is, there is equilibrium between the +manifestations of the causes of waste and the causes of supply. Every +mechanical or chemical agency which disturbs the restoration of this +equilibrium is a cause of disease. + +Death is that condition in which chemical or mechanical powers gain the +ascendancy, and all resistance on the part of the vital force ceases. +This resistance never entirely departs from living tissues during life. +Such deficiency in resistance is, in fact, a deficiency in resistance to +the action of the oxygen of the atmosphere. + +Disease occurs when the sum of vital force, which tends to neutralise +all causes of disturbance, is weaker than the acting cause of +disturbance. + +Should there be formed in the diseased parts, in consequence of the +change of matter, from the elements of the blood or of the tissue, new +products which the neighbouring parts cannot employ for their own vital +functions; should the surrounding parts, moreover, be unable to convey +these products to other parts where they may undergo transformation, +then these new products will suffer, at the place where they have been +formed, a process of decomposition analogous to putrefaction. + +In certain cases, medicine removes these diseased conditions by exciting +in the vicinity of the diseased part, or in any convenient situation, an +artificial diseased state (as by blisters), thus diminishing by means of +artificial disturbance the resistance offered to the external causes of +change in these parts by the vital force. The physician succeeds in +putting an end to the original diseased condition when the disturbance +artificially excited (or the diminution of resistance in another part) +exceeds in amount the diseased state to be overcome. + +The accelerated change of matter and the elevated temperature in the +diseased part show that the resistance offered by the vital force to the +action of oxygen is feebler than in the healthy state. But this +resistance only ceases entirely when death takes place. By the +artificial diminution of resistance in another part, the resistance in +the diseased organ is not, indeed, directly strengthened; but the +chemical action, the cause of the change of matter, is diminished in the +diseased part, being directed to another part, where the physician has +succeeded in producing a still more feeble resistance to the change of +matter, to the action of oxygen. + + + + +SIR CHARLES LYELL + +The Principles of Geology + + Sir Charles Lyell, the distinguished geologist, was born at + Kinnordy, Forfarshire, Scotland, Nov. 14, 1797. It was at Oxford + that his scientific interest was first aroused, and after taking an + M.A. degree in 1821 he continued his scientific studies, becoming + an active member of the Geological and Linnaean Societies of London. + In 1826 he was elected a fellow of the Royal Society, and two years + later went with Sir Roderick Murchison on a tour of Europe, and + gathered evidence for the theory of geological uniformity which he + afterwards promulgated. In 1830 he published his great work, + "Principles of Geology: Being an Attempt to Explain the Former + Changes of the Earth's Surface by References to Causes now in + Action," which converted almost the whole geological world to the + doctrine of uniformitarianism, and may be considered the foundation + of modern geology. Lyell died in London on February 22, 1875. + Besides his great work, he also published "The Elements of + Geology," "The Antiquity of Man," "Travels in North America," and + "The Student's Elements of Geology." + + +_I.--Uniformity in Geological Development_ + +According to the speculations of some writers, there have been in the +past history of the planet alternate periods of tranquillity and +convulsion, the former enduring for ages, and resembling the state of +things now experienced by man; the other brief, transient, and +paroxysmal, giving rise to new mountains, seas, and valleys, +annihilating one set of organic beings, and ushering in the creation of +another. These theories, however, are not borne out by a fair +interpretation of geological monuments; but, on the contrary, nature +indicates no such cataclysms, but rather progressive uniformity. + +Igneous rocks have been supposed to afford evidence of ancient paroxysms +of nature, but we cannot consider igneous rocks proof of any +exceptional paroxysms. Rather, we find ourselves compelled to regard +igneous rocks as an aggregate effect of innumerable eruptions, of +various degrees of violence, at various times, and to consider mountain +chains as the accumulative results of these eruptions. The incumbent +crust of the earth is never allowed to attain that strength and +coherence which would be necessary in order to allow the volcanic force +to accumulate and form an explosive charge capable of producing a grand +paroxysmal eruption. The subterranean power, on the contrary, displays, +even in its most energetic efforts, an intermittent and mitigated +intensity. There are no proofs that the igneous rocks were produced more +abundantly at remote periods. + +Nor can we find proof of catastrophic discontinuity when we examine +fossil plants and fossil animals. On the contrary, we find a progressive +development of organic life at successive geological periods. + +In Palaeozoic strata the entire want of plants of the most complex +organisation is very striking, for not a single dicotyledonous +angiosperm has yet been found, and only one undoubted monocotyledon. In +Secondary, or Mesozoic, times, palms and some other monocotyledons +appeared; but not till the Upper Cretaceous era do we meet with the +principal classes and orders of the vegetable kingdom as now known. +Through the Tertiary ages the forms were perpetually changing, but +always becoming more and more like, generically and specifically, to +those now in being. On the whole, therefore, we find progressive +development of plant life in the course of the ages. + +In the case of animal life, progression is equally evident. +Palaeontological research leads to the conclusion that the invertebrate +animals flourished before the vertebrate, and that in the latter class +fish, reptiles, birds, and mammalia made their appearance in a +chronological order analogous to that in which they would be arranged +zoologically according to an advancing scale of perfection in their +organisation. In regard to the mammalia themselves, they have been +divided by Professor Owen into four sub-classes by reference to +modifications of their brain. The two lowest are met with in the +Secondary strata. The next in grade is found in Tertiary strata. And the +highest of all, of which man is the sole representative, has not yet +been detected in deposits older than the Post-Tertiary. + +It is true that in passing from the older to the newer members of the +Tertiary system we meet with many chasms, but none which separate +entirely, by a broad line of demarcation, one state of the organic world +from another. There are no signs of an abrupt termination of one fauna +and flora, and the starting into life of new and wholly distinct forms. +Although we are far from being able to demonstrate geologically an +insensible transition from the Eocene to the Miocene, or even from the +latter to the recent fauna, yet the more we enlarge and perfect our +general survey the more nearly do we approximate to such a continuous +series, and the more gradually are we conducted from times when many of +the genera and nearly all the species were extinct to those in which +scarcely a single species flourished which we do not know to exist at +present. We must remember, too, that many gaps in animal and floral life +were due to ordinary climatic and geological factors. We could, under no +circumstances, expect to meet with a complete ascending series. + +The great vicissitudes in climate which the earth undoubtedly +experienced, as shown by geological records, have been held to be +themselves proof of sudden violent revolutions in the life-history of +the world. But all the great climatic vicissitudes can be accounted for +by the action of factors still, in operation--subsidences and elevations +of land, alterations in the relative proportions and position of land +and water, variations in the relative position of our planet to the sun +and other heavenly bodies. + +Altogether, the conclusion is inevitable that from the remotest period +there has been one uniform and continuous system of change in the +animate and inanimate world, and accordingly every fact collected +respecting the factors at present at work in forming and changing the +world, affords a key to the interpretation of its part. And thus, +although we are mere sojourners on the surface of the planet, chained to +a mere point in space, enduring but for a moment of time, the human mind +is enabled not only to number worlds beyond the unassisted ken of mortal +eye, but to trace the events of indefinite ages before the creation of +our race, and to penetrate into the dark secrets of the ocean and the +heart of the solid globe. + + +_II.--Changes in the Inorganic World now in Progress_ + +The great agents of change in the inorganic world may be divided into +two principal classes--the aqueous and the igneous. To the aqueous +belong rain, rivers, springs, currents, and tides, and the action of +frost and snow; to the igneous, volcanoes and earthquakes. Both these +classes are instruments of degradation as well as of reproduction. But +they may also be regarded as antagonist forces, since the aqueous agents +are incessantly labouring to reduce the inequalities of the earth's +surface to a level; while the igneous are equally active in restoring +the unevenness of the external crust, partly by heaping up new matter in +certain localities, and partly by depressing one portion of the earth's +envelope and forcing out another. + +We will treat in the first place of the aqueous agents. + +RAIN AND RIVERS. When one considers that in some parts of the world as +much as 500 or 600 inches of rain may fall annually, it is easy to +believe that rain _qua_ rain may be a denuding and plastic agent, and in +some parts of the world we find evidence of its action in earth pillars +or pyramids. The best example of earth pillars is seen near Botzen, in +the Tyrol, where there are hundreds of columns of indurated mud, varying +in height from 20 feet to 100 feet. These columns are usually capped by +a single stone, and have been separated by rain from the terrace of +which they once formed a part. + +As a rule, however, rain acts through rivers. The power of rivers to +denude and transport is exemplified daily. Even a comparatively small +stream when swollen by rain may move rocks tons in weight, and may +transport thousands of tons of gravel. The greatest damage is done when +rivers are dammed by landslips or by ice. In 1818 the River Dranse was +blocked by ice, and its upper part became a lake. In the hot season the +barrier of ice gave way, and the torrent swept before it rocks, forests, +houses, bridges, and cultivated land. For the greater part of its course +the flood resembled a moving mass of rock and mud rather than of water. +Some fragments of granite rock of enormous size, which might be compared +to houses, were torn out and borne down for a quarter of a mile. + +The rivers of unmelted ice called the glaciers act more slowly, but they +also have the power of transporting gravel, sand, and boulders to great +distances, and of polishing and scoring their rocky channels. Icebergs, +too, are potent geological agents. Many of them are loaded with 50,000 +to 100,000 tons of rock and earth, which they may carry great distances. +Also in their course they must break, and polish, and scratch the peaks +and points of submarine mountains. + +Coast ice, likewise, may transport rocks and earth. Springs also must be +considered as geological agents affecting the face of the globe. + +But running water not only denudes it, but also creates land, for +lakes, seas, rivers are seen to form deltas. That Egypt was the gift of +the Nile was the opinion of the Egyptian priests, and there can be no +doubt that the fertility of the alluvial plain above Cairo, and the very +existence of the delta below that city, are due to the action of that +great river, and to its power of transporting mud from the interior of +Africa and depositing it on its inundated plains as well as on that +space which has been reclaimed from the Mediterranean and converted into +land. The delta of the Ganges and Brahmapootra is more than double that +of the Nile. Even larger is the delta of the Mississippi, which has been +calculated to be 12,300 square miles in area. + +TIDES AND CURRENTS. The transporting and destroying and constructive +power of tides and currents is, in many respects, analogous to that of +rivers, but extends to wider areas, and is, therefore, of more +geological importance. The chief influence of the ocean is exerted at +moderate depths below the surface on all areas which are slowly rising, +or attempting, as it were, to rise above the sea; but its influence is +also seen round the coast of every continent and island. + + * * * * * + +We shall now consider the igneous agents that act on the earth's +surface. These agents are chiefly volcanoes and earthquakes, and we find +that both usually occur in particular parts of the world. At various +times and at various places within historical times volcanic eruptions +and earthquakes have both proved their potency to alter the face of the +earth. + +The principal geological facts and theories with regard to volcanoes and +earthquakes are as follows. + +The primary causes of the volcano and the earthquake are to a great +extent the same, and connected with the development of heat and chemical +action at various depths in the interior of the globe. + +Volcanic heat has been supposed to be the result of the original high +temperature of the molten planet, and the planet has been supposed to +lose heat by radiation. Recent inquiries, however, suggest that the +apparent loss of heat may arise from the excessive local development of +volcanic action. + +Whatever the original shape of our planet, it must in time have become +spheroidal by the gradual operation of centrifugal force acting on +yielding materials brought successively within its action by aqueous and +igneous causes. + +The heat in mines and artesian wells increases as we descend, but not in +uniform ratio in different regions. Increase at a uniform ratio would +imply such heat in the central nucleus as must instantly fuse the crust. + +Assuming that there are good astronomical grounds for inferring the +original fluidity of the planet, yet such pristine fluidity need not +affect the question of volcanic heat, for the volcanic action of +successive periods belongs to a much more modern state of the globe, and +implies the melting of different parts of the solid crust one after the +other. + +The supposed great energy of the volcanic forces in the remoter periods +is by no means borne out by geological observations on the quantity of +lava produced by single eruptions in those several periods. + +The old notion that the crystalline rocks, whether stratified or +unstratified, such as granite and gneiss, were produced in the lower +parts of the earth's crust at the expense of a central nucleus slowly +cooling from a state of fusion by heat has now had to be given up, now +that granite is found to be of all ages, and now that we know the +metamorphic rocks to be altered sedimentary strata, implying the +denudation of a previously solidified crust. + +The powerful agency of steam or aqueous vapour in volcanic eruptions +leads us to compare its power of propelling lava to the surface with +that which it exerts in driving water up the pipe of an Icelandic +geyser. Various gases also, rendered liquid by pressure at great depths, +may aid in causing volcanic outbursts, and in fissuring and convulsing +the rocks during earthquakes. + +The chemical character of the products of recent eruptions suggests that +large bodies of salt water gain access to the volcanic foci. Although +this may not be the primary cause of volcanic eruptions, which are +probably due to the aqueous vapour intimately mixed with molten rock, +yet once the crust is shattered through, the force and frequency of +eruptions may depend in some measure on the proximity of large bodies of +water. + +The permanent elevation and subsidence of land now observed, and which +may have been going on through past ages, may be connected with the +expansion and contraction of parts of the solid crust, some of which +have been cooling from time to time, while others have been gaining +heat. + +In the preservation of the average proportion of land and sea, the +igneous agents exert a conservative power, restoring the unevenness of +the surface which the levelling power of water in motion would tend to +destroy. If the diameter of the planet remains always the same, the +downward movements of the crust must be somewhat in excess, to +counterbalance the effects of volcanoes and mineral springs, which are +always ejecting material so as to raise the level of the surface of the +earth. Subterranean movements, therefore, however destructive they may +be during great earthquakes, are essential to the well-being of the +habitable surface, and even to the very existence of terrestrial and +aquatic species. + + +_III.--Changes of the Organic World now in Progress_ + +In 1809 Lamarck introduced the idea of transmutation of species, +suggesting that by changes in habitat, climate, and manner of living one +species may, in the course of generations, be transformed into a new +and distinct species. + +In England, however, the idea remained dormant till in 1844 a work +entitled the "Vestiges of Creation" reinforced it with many new facts. +In this work the unity of plan exhibited by the whole organic creation, +fossil and recent, and the mutual affinities of all the different +classes of the animal and vegetable kingdoms, were declared to be in +harmony with the idea of new forms having proceeded from older ones by +the gradually modifying influence of environment. In 1858 the theory was +put on a new and sound basis by Wallace and Darwin, who added the +conception of natural selection, suggesting that variations in species +are naturally produced, and that the variety fittest to survive in the +severe struggle for existence must survive, and transmit the +advantageous variation, implying the gradual evolution of new species. +Further, Darwin showed that other varieties may be perpetuated by sexual +selection. + +On investigating the geographical distribution of animals and plants we +find that the extent to which the species of mammalia, birds, insects, +landshells, and plants (whether flowering or cryptogamous) agree with +continental species; or the degree in which those of different islands +of the same group agree with each other has an unmistakable relation to +the known facilities enjoyed by each class of crossing the ocean. Such a +relationship accords well with the theory of variation and natural +selection, but with no other hypothesis yet suggested for explaining the +origin of species. + +From what has been said of the changes which are always going on in the +habitable surface of the world, and the manner in which some species are +constantly extending their range at the expense of others, it is evident +that the species existing at any particular period may, in the course of +ages, become extinct one after the other. + +If such, then, be the law of the organic world, if every species is +continually losing some of its varieties, and every genus some of its +species, it follows that the transitional links which once, according to +the doctrine of transmutation, must have existed, will, in the great +majority of cases, be missing. We learn from geological investigations +that throughout an indefinite lapse of ages the whole animate creation +has been decimated again and again. Sometimes a single representative +alone remains of a type once dominant, or of which the fossil species +may be reckoned by hundreds. We rarely find that whole orders have +disappeared, yet this is notably the case in the class of reptiles, +which has lost some orders characterised by a higher organisation than +any now surviving in that class. Certain genera of plants and animals +which seem to have been wholly wanting, and others which were feebly +represented in the Tertiary period, are now rich in species, and appear +to be in such perfect harmony with the present conditions of existence +that they present us with countless varieties, confounding the zoologist +or botanist who undertakes to describe or classify them. + +We have only to reflect on the causes of extinction, and we at once +foresee the time when even in these genera so many gaps will occur, so +many transitional forms will be lost, that there will no longer be any +difficulty in assigning definite limits to each surviving species. The +blending, therefore, of one generic or specific form into another must +be an exception to the general rule, whether in our own time or in any +period of the past, because the forms surviving at any given moment will +have been exposed for a long succession of antecedent periods to those +powerful causes of extinction which are slowly but incessantly at work +in the organic and inorganic worlds. + +They who imagine that, if the theory of transmutation be true, we ought +to discover in a fossil state all the intermediate links by which the +most dissimilar types have been formerly connected together, expect a +permanence and completeness of records such as is never found. We do not +find even that all recently extinct plants have left memorials of their +existence in the crust of the earth; and ancient archives are certainly +extremely defective. To one who is aware of the extreme imperfection of +the geological record, the discovery of one or two missing links is a +fact of small significance; but each new form rescued from oblivion is +an earnest of the former existence of hundreds of species, the greater +part of which are irrevocably lost. + +A somewhat serious cause of disquiet and alarm arises out of the +supposed bearing of this doctrine of the origin of species by +transmutation on the origin of man, and his place in nature. It is +clearly seen that there is such a close affinity, such an identity in +all essential points, in our corporeal structure, and in many of our +instincts and passions with those of the lower animals--that man is so +completely subjected to the same general laws of reproduction, increase, +growth, disease, and death--that if progressive development, spontaneous +variation, and natural selection have for millions of years directed the +changes of the rest of the organic world, we cannot expect to find that +the human race has been exempted from the same continuous process of +evolution. + +Such a near bond of connection between man and the rest of the animate +creation is regarded by many as derogatory to our dignity. But we have +already had to exchange the pleasing conceptions indulged in by poets +and theologians as to the high position in the scale of being held by +our early progenitors for humble and more lowly beginnings, the joint +labours of the geologist and archaeologist having left us in no doubt of +the ignorance and barbarism of Palaeolithic man. + +It is well, too, to remember that the high place we have reached in the +scale of being has been gained step by step, by a conscientious study +of natural phenomena, and by fearlessly teaching the doctrines to which +they point. It is by faithfully weighing evidence without regard to +preconceived notions, by earnestly and patiently searching for what is +true, not what we wish to be true, that we have attained to that +dignity, which we may in vain hope to claim through the rank of an ideal +parentage. + + + + +JAMES CLERK MAXWELL + +A Treatise on Electricity and Magnetism + + James Clerk Maxwell, the first professor of experimental physics at + Cambridge, was born at Edinburgh on November 13, 1831, and before + he was fifteen was already famous as a writer of scientific papers. + In 1854 he graduated at Cambridge as second wrangler. Two years + later he became professor of natural philosophy at Marischal + College, Aberdeen. Vacating his chair in 1860 for one at King's + College, London, Maxwell contributed largely to scientific + literature. His great lifework, however, is his famous "Treatise on + Electricity and Magnetism," which was published in 1873, and is, in + the words of a critic, "one of the most splendid monuments ever + raised by the genius of a single individual." It was in this work + that he constructed his famous theory if electricity in which + "action at a distance" should be replaced by "action through a + medium," and first enunciated the principles of an electro-magnetic + theory of light which has formed the basis of nearly all modern + physical science. He died on November 5, 1879. + + +_I.--The Nature of Electricity_ + +Let a piece of glass and a piece of resin be rubbed together. They will +be found to attract each other. If a second piece of glass be rubbed +with a second piece of resin, it will be found that the two pieces of +glass repel each other and that the two pieces of resin are also +repelled from one another, while each piece of glass attracts each piece +of resin. These phenomena of attraction and repulsion are called +electrical phenomena, and the bodies which exhibit them are said to be +"electrified," or to be "charged with electricity." + +Bodies may be electrified in many other ways, as well as by friction. +When bodies not previously electrified are observed to be acted on by an +electrified body, it is because they have become "electrified by +induction." If a metal vessel be electrified by induction, and a second +metallic body be suspended by silk threads near it, and a metal wire be +brought to touch simultaneously the electrified body and the second +body, this latter body will be found to be electrified. Electricity has +been transferred from one body to the other by means of the wire. + +There are many other manifestations of electricity, all of which have +been more or less studied, and they lead to the formation of theories of +its nature, theories which fit in, to a greater or less extent, with the +observed facts. The electrification of a body is a physical quantity +capable of measurement, and two or more electrifications can be combined +experimentally with a result of the same kind as when two quantities are +added algebraically. We, therefore, are entitled to use language fitted +to deal with electrification as a quantity as well as a quality, and to +speak of any electrified body as "charged with a certain quantity of +positive or negative electricity." + +While admitting electricity to the rank of a physical quantity, we must +not too hastily assume that it is, or is not, a substance, or that it +is, or is not, a form of energy, or that it belongs to any known +category of physical quantities. All that we have proved is that it +cannot be created or annihilated, so that if the total quantity of +electricity within a closed surface is increased or diminished, the +increase or diminution must have passed in or out through the closed +surface. + +This is true of matter, but it is not true of heat, for heat may be +increased or diminished within a closed surface, without passing in or +out through the surface, by the transformation of some form of energy +into heat, or of heat into some other form of energy. It is not true +even of energy in general if we admit the immediate action of bodies at +a distance. + +There is, however, another reason which warrants us in asserting that +electricity, as a physical quantity, synonymous with the total +electrification of a body, is not, like heat, a form of energy. An +electrified system has a certain amount of energy, and this energy can +be calculated. The physical qualities, "electricity" and "potential," +when multiplied together, produce the quantity, "energy." It is +impossible, therefore, that electricity and energy should be quantities +of the same category, for electricity is only one of the factors of +energy, the other factor being "potential." + +Electricity is treated as a substance in most theories of the subject, +but as there are two kinds of electrification, which, being combined, +annul each other, a distinction has to be drawn between free electricity +and combined electricity, for we cannot conceive of two substances +annulling each other. In the two-fluid theory, all bodies, in their +unelectrified state, are supposed to be charged with equal quantities of +positive and negative electricity. These quantities are supposed to be +so great than no process of electrification has ever yet deprived a body +of all the electricity of either kind. The two electricities are called +"fluids" because they are capable of being transferred from one body to +another, and are, within conducting bodies, extremely mobile. + +In the one-fluid theory everything is the same as in the theory of two +fluids, except that, instead of supposing the two substances equal and +opposite in all respects, one of them, generally the negative one, has +been endowed with the properties and name of ordinary matter, while the +other retains the name of the electric fluid. The particles of the fluid +are supposed to repel each other according to the law of the inverse +square of the distance, and to attract those of matter according to the +same law. Those of matter are supposed to repel each other and attract +those of electricity. This theory requires us, however, to suppose the +mass of the electric fluid so small that no attainable positive or +negative electrification has yet perceptibly increased or diminished the +mass or the weight of a body, and it has not yet been able to assign +sufficient reasons why the positive rather than the negative +electrification should be supposed due to an _excess_ quantity of +electricity. + +For my own part, I look for additional light on the nature of +electricity from a study of what takes place in the space intervening +between the electrified bodies. Some of the phenomena are explained +equally by all the theories, while others merely indicate the peculiar +difficulties of each theory. We may conceive the relation into which the +electrified bodies are thrown, either as the result of the state of the +intervening medium, or as the result of a direct action between the +electrified bodies at a distance. If we adopt the latter conception, we +may determine the law of the action, but we can go no further in +speculating on its cause. + +If, on the other hand, we adopt the conception of action through a +medium, we are led to inquire into the nature of that action in each +part of the medium. If we calculate on this hypothesis the total energy +residing in the medium, we shall find it equal to the energy due to the +electrification of the conductors on the hypothesis of direct action at +a distance. Hence, the two hypotheses are mathematically equivalent. + +On the hypothesis that the mechanical action observed between +electrified bodies is exerted through and by means of the medium, as the +action of one body on another by means of the tension of a rope or the +pressure of a rod, we find that the medium must be in a state of +mechanical stress. The nature of the stress is, as Faraday pointed out, +a tension along the lines of force combined with an equal pressure in +all directions at right angles to these lines. This distribution of +stress is the only one consistent with the observed mechanical action on +the electrified bodies, and also with the observed equilibrium of the +fluid dielectric which surrounds them. I have, therefore, assumed the +actual existence of this state of stress. + +Every case of electrification or discharge may be considered as a +motion in a closed circuit, such that at every section of the circuit +the same quantity of electricity crosses in the same time; and this is +the case, not only in the voltaic current, where it has always been +recognised, but in those cases in which electricity has been generally +supposed to be accumulated in certain places. We are thus led to a very +remarkable consequence of the theory which we are examining, namely, +that the motions of electricity are like those of an _incompressible_ +fluid, so that the total quantity within an imaginary fixed closed +surface remains always the same. + +The peculiar features of the theory as developed in this book are as +follows. + +That the energy of electrification resides in the dielectric medium, +whether that medium be solid or gaseous, dense or rare, or even deprived +of ordinary gross matter, provided that it be still capable of +transmitting electrical action. + +That the energy in any part of the medium is stored up in the form of a +constraint called polarisation, dependent on the resultant electromotive +force (the difference of potentials between two conductors) at the +place. + +That electromotive force acting on a dielectric produces what we call +electric displacement. + +That in fluid dielectrics the electric polarisation is accompanied by a +tension in the direction of the lines of force combined with an equal +pressure in all directions at right angles to the lines of force. + +That the surfaces of any elementary portion into which we may conceive +the volume of the dielectric divided must be conceived to be +electrified, so that the surface density at any point of the surface is +equal in magnitude to the displacement through that point of the surface +_reckoned inwards_. + +That, whatever electricity may be, the phenomena which we have called +electric displacement is a movement of electricity in the same sense as +the transference of a definite quantity of electricity through a wire. + + +_II.--Theories of Magnetism_ + +Certain bodies--as, for instance, the iron ore called loadstone, the +earth itself, and pieces of steel which have been subjected to certain +treatment--are found to possess the following properties, and are called +magnets. + +If a magnet be suspended so as to turn freely about a vertical axis, it +will in general tend to set itself in a certain azimuth, and, if +disturbed from this position, it will oscillate about it. + +It is found that the force which acts on the body tends to cause a +certain line in the body--called the axis of the magnet--to become +parallel to a certain line in space, called the "direction of the +magnetic force." + +The ends of a long thin magnet are commonly called its poles, and like +poles repel each other; while unlike poles attract each other. The +repulsion between the two magnetic poles is in the straight line joining +them, and is numerically equal to the products of the strength of the +poles divided by the square of the distance between them; that is, it +varies as the inverse square of the distance. Since the form of the law +of magnetic action is identical with that of electric action, the same +reasons which can be given for attributing electric phenomena to the +action of one "fluid," or two "fluids" can also be used in favour of the +existence of a magnetic matter, fluid or otherwise, provided new laws +are introduced to account for the actual facts. + +At all parts of the earth's surface, except some parts of the polar +regions, one end of a magnet points in a northerly direction and the +other in a southerly one. Now a bar of iron held parallel to the +direction of the earth's magnetic force is found to become magnetic. Any +piece of soft iron placed in a magnetic field is found to exhibit +magnetic properties. These are phenomena of _induced_ magnetism. Poisson +supposes the magnetism of iron to consist in a separation of the +magnetic fluids within each magnetic molecule. Weber's theory differs +from this in assuming that the molecules of the iron are always magnets, +even before the application of the magnetising force, but that in +ordinary iron the magnetic axes of the molecules are turned +indifferently in every direction, so that the iron as a whole exhibits +no magnetic properties; and this theory agrees very well with what is +observed. + +The theories establish the fact that magnetisation is a phenomenon, not +of large masses of iron, but of molecules; that is to say, of portions +of the substance so small that we cannot by any mechanical method cut +them in two, so as to obtain a north pole separate from the south pole. +We have arrived at no explanation, however, of the nature of a magnetic +molecule, and we have therefore to consider the hypothesis of +Ampere--that the magnetism of the molecule is due to an electric current +constantly circulating in some closed path within it. + +Ampere concluded that if magnetism is to be explained by means of +electric currents, these currents must circulate within the molecules of +the magnet, and cannot flow from one molecule to another. As we cannot +experimentally measure the magnetic action at a point within the +molecule, this hypothesis cannot be disproved in the same way that we +can disprove the hypothesis of sensible currents within the magnet. In +spite of its apparent complexity, Ampere's theory greatly extends our +mathematical vision into the interior of the molecules. + + +_III.--The Electro-Magnetic Theory of Light_ + +We explain electro-magnetic phenomena by means of mechanical action +transmitted from one body to another by means of a medium occupying the +space between them. The undulatory theory of light also assumes the +existence of a medium. We have to show that the properties of the +electro-magnetic medium are identical with those of the luminiferous +medium. + +To fill all space with a new medium whenever any new phenomena are to be +explained is by no means philosophical, but if the study of two +different branches of science has independently suggested the idea of a +medium; and if the properties which must be attributed to the medium in +order to account for electro-magnetic phenomena are of the same kind as +those which we attribute to the luminiferous medium in order to account +for the phenomena of light, the evidence for the physical existence of +the medium is considerably strengthened. + +According to the theory of emission, the transmission of light energy is +effected by the actual transference of light-corpuscles from the +luminous to the illuminated body. According to the theory of undulation +there is a material medium which fills the space between the two bodies, +and it is by the action of contiguous parts of this medium that the +energy is passed on, from one portion to the next, till it reaches the +illuminated body. The luminiferous medium is therefore, during the +passage of light through it, a receptacle of energy. This energy is +supposed to be partly potential and partly kinetic, and our theory +agrees with the undulatory theory in assuming the existence of a medium +capable of becoming a receptacle for two forms of energy. + +Now, the properties of bodies are capable of quantitative measurement. +We therefore obtain the numerical value of some property of the +medium--such as the velocity with which a disturbance is propagated in +it, which can be calculated from experiments, and also observed directly +in the case of light. If it be found that the velocity of propagation of +electro-magnetic disturbance is the same as the velocity of light, we +have strong reasons for believing that light is an electro-magnetic +phenomenon. + +It is, in fact, found that the velocity of light and the velocity of +propagation of electro-magnetic disturbance are quantities of the same +order of magnitude. Neither of them can be said to have been determined +accurately enough to say that one is greater than the other. In the +meantime, our theory asserts that the quantities are equal, and assigns +a physical reason for this equality, and it is not contradicted by the +comparison of the results, such as they are. + +Lorenz has deduced from Kirchoff's equations of electric currents a new +set of equations, indicating that the distribution of force in the +electro-magnetic field may be considered as arising from the mutual +action of contiguous elements, and that waves, consisting of transverse +electric currents, may be propagated, with a velocity comparable with +that of light, in non-conducting media. These conclusions are similar to +my own, though obtained by an entirely different method. + +The most important step in establishing a relation between electric and +magnetic phenomena and those of light must be the discovery of some +instance in which one set of phenomena is affected by the other. Faraday +succeeded in establishing such a relation, and the experiments by which +he did so are described in the nineteen series of his "Experimental +Researches." Suffice it to state here that he showed that in the case of +aray of plane-polarised light the effect of the magnetic force is to +turn the plane of polarisation round the direction of the ray as an +axis, through a certain angle. + +The action of magnetism on polarised light leads to the conclusion that +in a medium under the action of a magnetic force, something belonging to +the same mathematical class as an angular velocity, whose axis is in the +direction of the magnetic force, forms part of the phenomenon. This +angular velocity cannot be any portion of the medium of sensible +dimensions rotating as a whole. We must, therefore, conceive the +rotation to be that of very small portions of the medium, each rotating +on its own axis. + +This is the hypothesis of molecular vortices. The displacements of the +medium during the propagation of light will produce a disturbance of the +vortices, and the vortices, when so disturbed, may react on the medium +so as to affect the propagation of the ray. The theory proposed is of a +provisional kind, resting as it does on unproved hypotheses relating to +the nature of molecular vortices, and the mode in which they are +affected by the displacement of the medium. + + +_IV.--Action at a Distance_ + +There appears to be some prejudice, or _a priori_ objection, against the +hypothesis of a medium in which the phenomena of radiation of light and +heat, and the electric actions at a distance, take place. It is true +that at one time those who speculated as to the cause of physical +phenomena were in the habit of accounting for each kind of action at a +distance by means of a special aethereal fluid, whose function and +property it was to produce these actions. They filled all space three +and four times over with aethers of different kinds, the properties of +which consisted merely to "save appearances," so that more rational +inquirers were willing to accept not only Newton's definite law of +attraction at a distance, but even the dogma of Cotes that action at a +distance is one of the primary properties of matter, and that no +explanation can be more intelligible than this fact. Hence the +undulatory theory of light has met with much opposition, directed not +against its failure to explain the phenomena, but against its assumption +of the existence of a medium in which light is propagated. + +The mathematical expression for electro-dynamic action led, in the mind +of Gauss, to the conviction that a theory of the propagation of electric +action would in time be found to be the very keystone of +electro-dynamics. Now, we are unable to conceive of propagation in time, +except either as the flight of a material substance through space or as +the propagation of a condition of motion or stress in a medium already +existing in space. + +In the theory of Neumann, the mathematical conception called potential, +which we are unable to conceive as a material substance, is supposed to +be projected from one particle to another, in a manner which is quite +independent of a medium, and which, as Neumann has himself pointed out, +is extremely different from that of the propagation of light. In other +theories it would appear that the action is supposed to be propagated in +a manner somewhat more similar to that of light. + +But in all these theories the question naturally occurs: "If something +is transmitted from one particle to another at a distance, what is its +condition after it had left the one particle, and before it reached the +other?" If this something is the potential energy of the two particles, +as in Neumann's theory, how are we to conceive this energy as existing +in a point of space coinciding neither with the one particle nor with +the other? In fact, whenever energy is transmitted from one body to +another in time, there must be a medium or substance in which the energy +exists after it leaves one body, and before it reaches the other, for +energy, as Torricelli remarked, "is a quintessence of so subtile a +nature that it cannot be contained in any vessel except the inmost +substance of material things." + +Hence all these theories lead to the conception of a medium in which the +propagation takes place, and if we admit this medium as an hypothesis, I +think we ought to endeavour to construct a mental representation of all +the details of its action, and this has been my constant aim in this +treatise. + + + + +ELIE METCHNIKOFF + +The Nature of Man + + Elie Metchnikoff, Sub-Director of the Pasteur Institute in Paris, + was born May 15, 1845, in the province of Kharkov, Russia, and has + worked at the Pasteur Institute since 1888. The greater part of + Metchnikoff's work is concerned with the most intimate processes of + the body, and notably the means by which it defends itself from the + living agents of disease. He is, indeed, the author of a standard + treatise entitled "Immunity in Infective Diseases." His early work + in zoology led him to study the water-flea, and thence to discover + that the white cells of the human blood oppose, consume, and + destroy invading microbes. Latterly, Metchnikoff has devoted + himself in some measure to more general and especially + philosophical studies, the outcome of which is best represented by + the notable volume on "The Nature of Man," which was published at + Paris in 1903. + + +_I.--Disharmonies in Nature_ + +Notwithstanding the real advance made by science, it cannot be disputed +that a general uneasiness disturbs the whole world to-day, and the +frequency of suicide is increased greatly among civilised peoples. Yet +if science turns to study human nature, there may be grounds for hope. +The Greeks held human nature and the human body in high esteem, and +among the Romans such a philosopher as Seneca said, "Take nature as your +guide, for so reason bids you and advises you; to live happily is to +live naturally." In our own day Herbert Spencer has expressed again the +Greek ideal, seeking the foundation of morality in human nature itself. + +But it has often been taught that human nature is composed of two +hostile elements, a body and a soul. The soul alone was to be honoured, +while the body was regarded as the vile source of evils. This doctrine +has had many disastrous consequences, and it is not surprising that in +consequence of it celibacy should have been regarded as the ideal state. +Art fell from the Greek ideal until the Renaissance, with its return to +that ideal, brought new vigour. When the ancient spirit was born again +its influence reached science and even religion, and the Reformation was +a defence of human nature. The Lutheran doctrines resumed the principle +of a "development as complete as possible of all the natural powers" of +man, and compulsory celibacy was abolished. + +The historical diversity of opinion regarding human nature is what has +led me to the attempt to give an exposition of human nature in its +strength and in its weakness. But, before dealing with the man himself, +we must survey the lower forms of life. + +The facts of the organised world, before the appearnace of man, teach us +that though we find change and development, development does not always +take a progressive march. We are bound to believe, for instance, that +the latest products of evolution are not human beings, but certain +parasites which live only upon, or in, the human body. The law in nature +is not of constant progress, but of constant tendency towards +adaptation. Exquisite adaptations, or harmonies, in nature are +constantly met with in the world of living beings. But, on the other +hand, any close investigation of organisation and life reveals that +beside many most perfect harmonies, there are facts which prove the +existence of incomplete harmony, or even absolute disharmony. +Rudimentary and useless organs are widely distributed. Many insects are +exquisitely adapted for sucking the nectar of flowers; many others would +wish to do the same, but their want of adaptation baffles them. + +It is plain that an instinct, or any other form of disharmony, leading +to destruction, cannot increase or even endure very long. The perversion +of the maternal instinct, tending to abandonment of the young, is +destructive to the stock. In consequence, individuals affected by it do +not have the opportunity of transmitting the perversion. If all rabbits, +or a majority of them, left their young to die through neglect, it is +evident that the species would soon die out. On the contrary, mothers +guided by their instinct to nourish and foster their offspring will +produce a vigorous generation capable of transmitting the healthy +maternal instinct so essential for the preservation of the species. For +such a reason harmonious characters are more abundant in nature than +injurious peculiarities. The latter, because they are injurious to the +individual and to the species, cannot perpetuate themselves +indefinitely. + +In this way there comes about a constant selection of characters. The +useful qualities are handed down and preserved, while noxious characters +perish and so disappear. Although disharmonies tend to the destruction +of a species, they may themselves disappear without having destroyed the +race in which they occur. + +This continuous process of natural selection, which offers so good an +explanation of the transmutation and origin of species by means of +preservation of useful and destruction of harmful characters, was +discovered by Darwin and Wallace, and was established by the splendid +researches of the former of these. + +Long before the appearance of man on the face of the earth, there were +some happy beings well adapted to their environment, and some unhappy +creatures that followed disharmonious instincts so as to imperil or to +destroy their lives. Were such creatures capable of reflection and +communication, plainly the fortunate among them, such as orchids and +certain wasps, would be on the side of the optimists; they would declare +this the best of all possible worlds, and insist that to secure +happiness it is necessary only to follow natural instincts. On the other +hand, the disharmonious creatures, those ill adapted to the conditions +of life, would be pessimistic philosophers. Consider the case of the +ladybird, driven by hunger and with a preference for honey, which +searches for it on flowers and meets only with failure, or of insects +driven by their instincts into the flames, only to lose their wings and +their lives; such creatures, plainly, would express as their idea of the +world that it was fashioned abominably, and that existence was a +mistake. + + +_II.--Disharmonies in Man_ + +As for man, the creature most interesting to us, in what category does +he fall? Is he a being whose nature is in harmony with the conditions in +which he has to live, or is he out of harmony with his environment? A +critical examination is needed to answer these questions, and to such an +examination the pages to follow are devoted. + +Science has proved that man is closely akin to the higher monkeys or +anthropoid apes--a fact which we must reckon with if we are to +understand human nature. The details of anatomy which show the kinship +between man and the apes are numerous and astonishing. All the facts +brought to light during the last forty years have supported this truth, +and no single fact has been brought against it. Quite lately it has been +shown that there are remarkable characters in the blood, such that, +though by certain tests the fluid part of human blood can be readily +distinguished from that of any other creature, the anthropoid apes, and +they alone, furnish an exception to this rule. There is thus verily a +close blood-relationship between the human species and the anthropoid +apes. + +But how man arose we do not know. It is probable that he owes his origin +to a mutation--a sudden change comparable with that which De Vries +observed in the case of the evening primrose. The new creature possessed +a brain of abnormal size placed in a spacious cranium which allowed a +rapid development of intellectual faculties. This peculiarity would be +transmitted to the descendants, and as it was a very considerable +advantage in the struggle for existence, the new race would hold its +own, propagate, and prevail. + +Although he is a recent arrival on the earth, man has already made great +progress, as compared with his ancestors the anthropoid apes, and we +learn the same if we compare the higher and lower races of mankind. Yet +there remain many disharmonies in the organisation of man, as, for +instance, in his digestive system. A simple instance of this kind is +furnished by the wisdom teeth. The complete absence of all four wisdom +teeth has no influence on mastication, and their presence is very +frequently the source of illness and danger. In man they are indeed +rudimentary organs, providing another proof of our simian origin. The +vermiform appendix, so frequently the cause of illness and death, is +another rudimentary organ in the human body, together with the part of +the digestive canal to which it is attached. The organ is a very old +part of the constitution of mammals, and it is because it has been +preserved long after its function has disappeared that we find it +occurring in the body of man. + +I believe that not only the appendix, but a very large part of the +alimentary canal is superfluous, and worse than superfluous. It is, of +course, of great importance to the horse, the rabbit, and some other +mammals that live exclusively on grain and herbage. The latter part of +the alimentary canal, however, must be regarded as one of the organs +possessed by man and yet harmful to his health and life. It is the cause +of a series of misfortunes. The human stomach also is of little value, +and can easily be dispensed with, as surgery has proved. It is because +we inherit our alimentary canal from creatures of different dietetic +habits that it is impossible for us to take our nutriment in the most +perfect form. If we were only to eat substances that could be almost +completely absorbed, serious complications would be produced. A +satisfactory system of diet has to make allowance for this, and in +consequence of the structure of the alimentary canal has to include in +the food bulky and indigestible materials, such as vegetables. Lastly, +it may be noted that the instinct of appetite in man is largely +aberrant. The widespread results of alcoholism show plainly the +prevalent existence in man of a want of harmony between the instinct for +choosing food and the instinct of preservation. + +Far stronger than the social instinct, and far older, is the love of +life and the instinct of self-preservation. Devices for the protection +of life were developed long before the evolution of mankind, and it is +quite certain that animals, even those highest in the scale of life, are +unconscious of the inevitability of death and the ultimate fate of all +living things. This knowledge is a human acquisition. It has long been +recognised that the old attach a higher value to life than do the young. +The instinctive love of life and fear of death are of importance in the +study of human nature, impossible to over-estimate. + +The instinctive love of life is preserved in the aged in its strongest +form. I have carefully studied the aged to make certain on this point. +It is a terrible disharmony that the instinctive love of life should +manifest itself so strongly when death is felt to be so near at hand. +Hence the religions of all times have been concerned with the problem of +death. + + +_III.--Science the Only Remedy for Human Disharmonies_ + +In religion and in philosophy throughout their whole history we find +attempts to combat the ills arising from the disharmonies of the human +constitution. + +Ancient and modern philosophies, like ancient and modern religions, have +concerned themselves with the attempt to remedy the ills of human +existence, and instinctive fear of death has always ensured that great +attention has been paid to the doctrine of immortality. + +Science, the youngest daughter of knowledge, has begun to investigate +the great problems affecting humanity. Her first steps, taken along the +lines first clearly laid down by Bacon, were slow and halting. But +medical science has lately made great progress, and has gone very far to +control disease, especially in consequence of the work of Pasteur. It is +said that science has failed because, for instance, tuberculosis +persists, but tuberculosis is propagated not because of the failure of +science, but because of the ignorance and stupidity of the population. +To diminish the spread of tuberculosis, of typhoid fever, of dysentery, +and of many other diseases, it is necessary only to follow the rules of +scientific hygiene without waiting for specific remedies. + +Science offers us much hope also when it is directed to the study of old +age and the phenomena which lead to death. + +Man, who is the descendant of some anthropoid ape, has inherited a +constitution adapted to an environment very different from that which +now surrounds him. He is possessed of a brain very much more highly +developed than that of his ancestors, and has entered on a new path in +the evolution of the higher organisms. The sudden change in his natural +conditions has brought about a large series of organic disharmonies, +which become more and more acutely felt as he becomes more intelligent +and more sensitive; and thus there has arisen a number of sorrows which +poor humanity has tried to relieve by all the means in its power. +Humanity in its misery has put question after question to science, and +has lost patience at the slowness of the advance of knowledge. It has +declared that the answers already found by science are futile and of +little interest. But science, confident of its methods, has quietly +continued to work. Little by little the answers to some of the +questions that have been set have begun to appear. + +Man, because of the fundamental disharmonies in his constitution, does +not develop normally. The earlier phases of his development are passed +through with little trouble; but after maturity greater or lesser +abnormality begins, and ends in old age and death that are premature and +pathological. Is not the goal of existence the accomplishment of a +complete and physiological cycle in which occurs a normal old age, +ending in the loss of the instinct of life and the appearance of the +instinct of death? But before attaining the normal end, coming after the +appearance of the instinct of death, a normal life must be lived; a life +filled all through with the feeling that comes from the accomplishment +of function. Science has been able to tell us that man, the descendant +of animals, has good and evil qualities in his nature, and that his life +is made unhappy by the evil qualities. + +But the constitution of man is not immutable, and perhaps it may be +changed for the better. Morality should be based not on human nature in +its existing condition, but on ideal human nature, as it may be in the +future. Before all things, it is necessary to try to amend the evolution +of human life, that is to say, to transform its disharmonies into +harmonies. This task can be undertaken only by science, and to science +the opportunity of accomplishing it must be given. Before it is possible +to reach the goal mankind must be persuaded that science is all-powerful +and that the deeply-rooted existing superstitions are pernicious. It +will be necessary to reform many customs and many institutions that now +seem to rest on enduring foundations. The abandonment of much that is +habitual, and a revolution in the mode of education, will require long +and painful effort. But the conviction that science alone is able to +redress the disharmonies of the human constitution will lead directly to +the improvement of education and to the solidarity of mankind. + + + + +The Prolongation of Life + + Professor Metchnikoff's volume, on "The Prolongation of Life: + Studies in Optimistic Philosophy," was published in 1907, and is in + some respects the most original of his works. In it he carries much + further the arguments and the studies to which he made brief + allusion in "The Nature of Man," and he lays down certain + principles for the prolongation of life which have been put into + practice by a large number of people during the last two or three + years, and are steadily gaining more attention. Sour milk as an + article of diet appears to have a peculiar value in arresting the + supposed senile changes which are largely due to auto-intoxication + or self-poisoning. + + +_I.--Senile Debility_ + +When we study old age in man and the lower animals, we observe certain +features common to both. But often among vertebrates there are found +animals whose bodies withstand the ravages of time much better than that +of man. I think it a fair inference that senility, that precocious +senescence which is one of the greatest sorrows of humanity, is not so +profoundly seated in the constitution of the higher animals as has +generally been supposed. The first facts which we must accept are that +human beings who reach extreme old age may preserve their mental +qualities, notwithstanding serious physical decay, and that certain of +the higher animals can resist the influence of time much longer than is +the case with man under present conditions. + +Many theories have been advanced regarding the cause of senility. It is +certain that many parts of the body continue to thrive and grow even in +old age, as, for instance, the nails and hair. But I believe that I have +proved that in many parts of the body, especially the higher elements, +such as nervous and muscular cells, there is a destruction due to the +activity of the white cells of the blood. I have shown also that the +blanching of the hair in old age is due to the activity of these white +cells, which destroy the hair pigment. Progressive muscular debility is +an accompaniment of old age; physical work is seldom given to men over +sixty years of age, as it is notorious that they are less capable of it. +Their muscular movements are feebler, and soon bring on fatigue; their +actions are slow and painful. Even old men whose mental vigour is +unimpaired admit their muscular weakness. The physical correlate of this +condition is an actual atrophy of the muscles, and has for long been +known to observers. I have found that the cause of this atrophy is the +consumption of the muscle fibres by what I call phagocytes, or eating +cells, a certain kind of white blood cells. + +In the case of certain diseases we find symptoms, which look like +precocious senility, due to the poison of the disease. It is no mere +analogy to suppose that human senescence is the result of a slow but +chronic poisoning of the organism. Such poisons, if not completely +destroyed or got rid of, weaken the tissues, the functions of which +become altered or enfeebled in which the latter have the advantage. But +we must make further studies before we can answer the question whether +our senescence can be ameliorated. + +The duration of the life of animals varies within very wide limits. As a +general rule, small animals do not live so long as large ones, but there +is no absolute relation between size and longevity, since parrots, +ravens, and geese live much longer than many mammals, and than some much +larger birds. Buffon long ago argued that the total duration of life +bore some definite relation to the length of the period of growth, but +further inquiry shows that such a relation cannot be established. +Nevertheless, there is something intrinsic in each kind of animal which +sets a definite limit to the length of years it can attain. The purely +physiological conditions which determine this limit leave room for a +considerable amount of variation in longevity. Duration of life, +therefore, is a character which can be influenced by the environment. + +The duration of life in mammals is relatively shorter than in birds, and +in the so-called cold-blooded vertebrates. No indication as to the cause +of this difference can be found elsewhere than in the organs of +digestion. Mammals are the only group of vertebrate animals in which the +large intestine is much developed. This part of the alimentary canal is +not important, for it fulfils no notable digestive function. On the +other hand, it accommodates among the intestinal flora many microbes +which damage health by poisoning the body with their products. Among the +intestinal flora there are many microbes which are inoffensive, but +others are known to have pernicious properties, and auto-intoxication, +or self-poisoning, is the cause of the ill-health which may be traced to +their activity. It is indubitable that the intestinal microbes or their +poisons may reach the system generally, and bring harm to it. I infer +from the facts that the more the digestive tract is charged with +microbes, the more it is a source of harm capable of shortening life. As +the large intestine not only is that part of the digestive tube most +richly charged with microbes, but is relatively more capacious in +mammals than in any other vertebrates, it is a just inference that the +duration of life of mammals has been notably shortened as the result of +chronic poisoning from an abundant intestinal flora. + +When we come to study the duration of human life, it is impossible to +accept the view that the high mortality between the ages of seventy and +seventy-five indicates a natural limit to human life. The fact that many +men from seventy to seventy-five years old are well preserved, both +physically and intellectually, makes it impossible to regard that age as +the natural limit of human life. Philosophers such as Plato, poets such +as Goethe and Victor Hugo, artists such as Michael Angelo, Titian, and +Franz Hals, produced some of their most important works when they had +passed what some regard as the limit of life. Moreover, deaths of people +at that age are rarely due to senile debility. Centenarians are really +not rare. In France, for instance, nearly 150 centenarians die every +year, and extreme longevity is not limited to the white races. Women +more frequently become centenarians than men--a fact which supports the +general proposition that male mortality is always greater than that of +the other sex. + +It has been noticed that most centenarians have been people who were +poor or in humble circumstances, and whose life has been extremely +simple. It may well be said that great riches do not bring a very long +life. Poverty generally brings with it sobriety, especially in old age, +and sobriety is certainly favourable to long life. + + +_II.--The Study of Natural Death_ + +It is surprising to find how little science really knows about death. By +natural death I mean to denote death due to the nature of the organism, +and not to disease. We may ask whether natural death really occurs, +since death so frequently comes by accident or by disease; and certainly +the longevity of many plants is amazing. Such ages as three, four, and +five thousand years are attributed to the baobab at Cape Verd, certain +cypresses, and the sequoias of California. It is plain that among the +lower and higher plants there are cases where natural death does not +exist; and, further, so far as I can ascertain, it looks as if poisons +produced by their own bodies were the cause of natural death among the +higher plants where it does occur. + +In the human race cases of what may be called natural death are +extremely rare; the death of old people is usually due to infectious +disease, particularly pneumonia, or to apoplexy. The close analogy +between natural death and sleep supports my view that it is due to an +auto-intoxication of the organism, since it is very probable that sleep +is due to "poisoning" by the products of organic activity. + +Although the duration of the life of man is one of the longest amongst +mammals, men find it too short. Ought we to listen to the cry of +humanity that life is too short, and that it will be well to prolong it? +If the question were merely one of prolonging the life of old people, +without modifying old age itself, the answer would be doubtful. It must +be understood, however, that the prolongation of life will be associated +with the preservation of intelligence and of the power to work. When we +have reduced or abolished such causes of precocious senility as +intemperance and disease, it will no longer be necessary to give +pensions at the age of sixty or seventy years. The cost of supporting +the old, instead of increasing, will diminish progressively. We must use +all our endeavors to allow men to complete their normal course of life, +and to make it possible for old men to play their parts as advisers and +judges, endowed with their long experience of life. + +From time immemorial suggestions have been made for the prolongation of +life. Many elixirs have been sought and supposed to have been found, but +general hygienic measures have been the most successful in prolonging +life and in lessening the ills of old age. That is the teaching of Sir +Herman Weber, himself of very great age, who advises general hygienic +principles, and especially moderation in all respects. He advises us to +avoid alcohol and other stimulants, as well as narcotics and soothing +drugs. Certainly the prolongation of life which has come to pass in +recent centuries must be attributed to the advance of hygiene; and if +hygiene was able to prolong life when little developed, as was the case +until recently, we may well believe that with our greater knowledge a +much better result will be obtained. + + +_III.--The Use of Lactic Acid_ + +The general measures of hygiene directed against infectious diseases +play a part in prolonging the lives of old people; but, in addition to +the microbes which invade the body from outside, there is a rich source +of harm in microbes which inhabit the body. The most important of these +belong to the intestinal flora which is abundant and varied. Now the +attempt to destroy the intestinal microbes by the use of chemical agents +has little chance of success, and the intestine itself may be harmed +more than the microbes. If, however, we observe the new-born child we +find that, when suckled by its mother, its intestinal microbes are very +different and much fewer than if it be fed with cows' milk. I am +strongly convinced that it is advantageous to protect ourselves by +cooking all kinds of food which, like cows' milk, are exposed to the +air. It is well-known that other means--as, for instance, the use of +lactic acid--will prevent food outside the body from going bad. Now as +lactic fermentation serves so well to arrest putrefaction in general, +why should it not be used for the same purpose within the digestive +tube? It has been clearly proved that the microbes which produce lactic +acid can, and do, control the growth of other microbes within the body, +and that the lactic microbe is so much at home in the human body that it +is to be found there several weeks after it has been swallowed. + +From time immemorial human beings have absorbed quantities of lactic +microbes by consuming in the uncooked condition substances such as +soured milk, kephir, sauerkraut, or salted cucumbers, which have +undergone lactic fermentation. By these means they have unknowingly +lessened the evil consequences of intestinal putrefaction. The fact that +so many races make soured milk and use it copiously is an excellent +testimony to its usefulness, and critical inquiry shows that longevity, +with few traces of senility, is conspicuous amongst peoples who use sour +milk extensively. + +A reader who has little knowledge of such matters may be surprised by my +recommendation to absorb large quantities of microbes, as the general +belief is that microbes are all harmful. This belief, however, is +erroneous. There are many useful microbes, amongst which the lactic +bacilli have an honourable place. If it be true that our precocious and +unhappy old age is due to poisoning of the tissues, the greater part of +the poison coming from the large intestine, inhabited by numberless +microbes, it is clear that agents which arrest intestinal putrefaction +must at the same time postpone and ameliorate old age. This theoretical +view is confirmed by the collection of facts regarding races which live +chiefly on soured milk, and amongst which great ages are common. + + +_IV.--An Ideal Old Age_ + +As I have shown in the "Nature of Man," the human constitution as it +exists to-day, being the result of a long evolution and containing a +large animal element, cannot furnish the basis of rational morality. The +conception which has come down from antiquity to modern times, of a +harmonious activity of all the organs, is no longer appropriate to +mankind. Organs which are in course of atrophy must not be re-awakened, +and many natural characters which, perhaps, were useful in the case of +animals, must be made to disappear in men. + +Human nature which, like the constitutions of other organisms, is +subject to evolution, must be modified according to a definite ideal. +Just as a gardener or stock-raiser is not content with the existing +nature of the plants and animals with which he is occupied, but modifies +them to suit his purposes, so also the scientific philosopher must not +think of existing human nature as immutable, but must try to modify it +for the advantage of mankind. As bread is the chief article in the human +food, attempts to improve cereals have been made for a very long time, +but in order to obtain results much knowledge is necessary. To modify +the nature of plants, it is necessary to understand them well, and it is +necessary to have an ideal to be aimed at. In the case of mankind the +ideal of human nature, towards which we ought to press, may be formed. +In my opinion this ideal is "orthobiosis"--that is to say, the +development of human life, so that it passes through a long period of +old age in active and vigorous health, leading to a final period in +which there shall be present a sense of satiety of life, and a wish for +death. + +Just as we must study the nature of plants before trying to realise our +ideal, so also varied and profound knowledge is the first requisite for +the ideal of moral conduct. It is necessary not only to know the +structure and functions of the human organism, but to have exact ideas +on human life as it is in society. Scientific knowledge is so +indispensable for moral conduct that ignorance must be placed among the +most immoral acts. A mother who rears her child in defiance of good +hygiene, from want of knowledge, is acting immorally towards her +offspring, notwithstanding her feeling of sympathy. And this also is +true of a government which remains in ignorance of the laws which +regulate human life and human society. + +If the human race come to adopt the principles of orthobiosis, a +considerable change in the qualities of men of different ages will +follow. Old age will be postponed so much that men of from sixty to +seventy years of age will retain their vigour, and will not require to +ask assistance in the fashion now necessary. On the other hand, young +men of twenty-one years of age will no longer be thought mature or ready +to fulfil functions so difficult as taking a share in public affairs. +The view which I set forth in the "Nature of Man" regarding the danger +which comes from the present interference of young men in political +affairs has since then been confirmed in the most striking fashion. + +It is easily intelligible that in the new conditions such modern idols +as universal suffrage, public opinion, and the _referendum_, in which +the ignorant masses are called on to decide questions which demand +varied and profound knowledge, will last no longer than the old idols. +The progress of human knowledge will bring about the replacement of such +institutions by others, in which applied morality will be controlled by +the really competent persons. I permit myself to suppose that in these +times scientific training will be much more general than it is just now, +and that it will occupy the place which it deserves in education and in +life. + +Our intelligence informs us that man is capable of much, and, therefore, +we hope that he may be able to modify his own nature and transform his +disharmonies into harmonies. It is only human will that can attain this +ideal. + + + + +HUGH MILLER + +The Old Red Sandstone + + Hugh Miller was born in Cromarty, in the North of Scotland, October + 10, 1802. From the time he was seventeen until he was thirty-four, + he worked as a common stone-mason, although devoting his leisure + hours to independent researches in natural history, for which he + formed a taste early in life. He became interested in journalism, + and was editor of the Edinburgh "Witness," when, in 1840, he + published the contents of the volume issued a year later as "The + Old Red Sandstone." The book deals with its author's most + distinctive work, namely, finding fossils that tell much of the + history of the Lower Old Red Sandstone, and fixing in the + geological scale the place to which the larger beds of remains + found in the system belong. Besides being a practical and original + geologist, Miller had a fine imaginative power, which enabled him + to reconstruct the past from its ruinous relics. The fact that he + unfortunately set himself the task of combating the theory of + evolution, which was fast gaining ground in his day, should not + blind us to the high value of his geological experiences. The + results of his observations provide some of the most cogent proofs + of the theory he disputed. Late in life Miller's mind gave way, and + he put an end to his own life on December 24, 1856. + + +_I.--A Stone-mason's Researches_ + +My advice to young working men desirous of bettering their +circumstances, and adding to the amount of their enjoyment, is to seek +happiness in study. Learn to make a right use of your eyes; the +commonest things are worth looking at--even stones, weeds, and the most +familiar animals. There are none of the intellectual or moral faculties, +the exercise of which does not lead to enjoyment; hence it is that +happiness bears so little reference to station. + +Twenty years ago I made my first acquaintance with a life of labour and +restraint. I was but a slim, loose-jointed boy at the time, fond of the +pretty intangibilities of romance, and of dreaming when broad awake; +and, woful change! I was now going to work in a quarry. I was going to +exchange all my day-dreams for the kind of life in which men toil every +day that they may be enabled to eat, and eat every day that they may be +enabled to toil! + +That first day was no very formidable beginning of the course of life I +had so much dreaded. To be sure, my hands were a little sore, and I felt +nearly as much fatigued as if I had been climbing among the rocks; but I +had wrought and been useful, and had yet enjoyed the day fully as much +as usual. I was as light of heart next morning as any of my +brother-workmen. That night, arising out of my employment, I found I had +food enough for thought without once thinking of the unhappiness of a +life of labour. + +In the course of the day I picked up a nodular mass of blue limestone, +and laid it open by a stroke of the hammer. Wonderful to relate, it +contained inside a beautifully finished piece of sculpture, one of the +volutes, apparently, of an Ionic capital. Was there another such +curiosity in the whole world? I broke open a few other nodules of +similar appearance, and found that there might be. In one of these there +were what seemed to be scales of fishes and the impressions of a few +minute bivalves, prettily striated; in the centre of another there was +actually a piece of decayed wood. + +Of all nature's riddles these seemed to me to be at once the most +interesting and the most difficult to expound. I treasured them +carefully up, and was told by one of the workmen to whom I showed them +that there was a part of the shore, about two miles further to the west, +where curiously shaped stones, somewhat like the heads of +boarding-pikes, were occasionally picked up, and that in his father's +day the country people called them thunderbolts. Our first half-holiday +I employed in visiting the place where the thunderbolts had fallen so +thickly, and found it a richer scene of wonder than I could have +fancied even in my dreams. + +My first year of labour came to a close, and I found that the amount of +my happiness had not been less than in the last of my boyhood. My +knowledge had increased in more than the ratio of former seasons; and as +I had acquired the skill of at least the common mechanic, I had fitted +myself for independence. + +My curiosity, once fully awakened, remained awake, and my opportunities +of gratifying it have been tolerably ample. I have been an explorer of +caves and ravines, a loiterer along sea-shores, a climber among rocks, a +labourer in quarries. My profession was a wandering one. I remember +passing direct, on one occasion, from the wild western coast of +Ross-shire, where the Old Red Sandstone leans at a high angle against +the prevailing quartz of the district, to where, on the southern skirts +of Midlothian, the Mountain Limestone rises amid the coal. I have +resided one season on a raised beach of the Moray Firth. I have spent +the season immediately following amid the ancient granite and contorted +schists of the central Highlands. In the north I have laid open by +thousands the shells and lignites of the oolite; in the south I have +disinterred from their matrices of stone or of shale the huge reds and +tree ferns of the carboniferous period. + +I advise the stone-mason to acquaint himself with geology. Much of his +time must be spent amid the rocks and quarries of widely separated +localities, and so, in the course of a few years he may pass over the +whole geological scale, and this, too, with opportunities of observation +at every stage which can be shared with him by only the gentleman of +fortune who devotes his whole time to study. Nay, in some respects, his +advantages are superior to those of the amateur, for the man whose +employments have to be carried on in the same formation for months, +perhaps years, enjoys better opportunities of arriving at just +conclusions. There are formations which yield their organisms slowly to +the discoverer, and the proofs which establish their place in the +geological scale more tardily still. I was acquainted with the Old Red +Sandstone of Ross and Cromarty for nearly ten years ere I ascertained +that it is richly fossiliferous; I was acquainted with it for nearly ten +years more ere I could assign its fossils to their exact place in the +scale. Nature is vast and knowledge limited, and no individual need +despair of adding to the general fund. + + +_II.--Bridging Life's Gaps_ + +"The Old Red Sandstone," says a Scottish geologist in a digest of some +recent geological discoveries, "has hitherto been considered as +remarkably barren of fossils." Only a few years have gone by since men +of no low standing in the science disputed the very existence of this +formation--or system, rather, for it contains at least three distinct +formations. There are some of our British geologists who still regard it +as a sort of debatable tract, entitled to no independent status, a sort +of common which should be divided. + +It will be found, however, that this hitherto neglected system yields in +importance to none of the others, whether we take into account its +amazing depth, the great extent to which it is developed both at home +and abroad, the interesting links which it furnishes in the geological +scale, or the vast period of time which it represents. There are +localities in which the depth of the Old Red Sandstone fully equals the +elevation of Mount Etna over the level of the sea, and in which it +contains three distinct groups of organic remains, the one rising in +beautiful progression over the other. + +My first statement regarding the system must be much the reverse of the +one just quoted, for the fossils are remarkably numerous and in a state +of high preservation. I have a hundred solid proofs by which to +establish the truth of the assertion within less than a yard of me. Half +my closet walls are covered with the peculiar fossils of the Lower Old +Red Sandstone; and certainly a stranger assemblage of forms has rarely +been grouped together--creatures whose very type is lost, fantastic and +uncouth, which puzzle the naturalist to assign them even to their class; +boat-like animals, furnished with oars and a rudder; fish, plated over, +like the tortoise, above and below, with a strong armour of bone, and +furnished with but one solitary rudder-like fin; other fish with the +membranes of their fins thickly covered with scales; creatures bristling +over with thorns; others glistening in an enamelled coat, as if +beautifully japanned; the tail in every instance among the less +equivocal shapes formed not equally, as in existing fish, on each side +the central vertebral column, but chiefly on the lower side--the column +sending out its diminished vertebrae to the extreme termination of the +fin. All the forms testify of a remote antiquity. The figures on a +Chinese vase or an Egyptian obelisk are scarce more unlike what now +exists in nature than are the fossils of the Lower Old Red Sandstone. + +Lamarck, on the strength of a few striking facts which prove that to a +certain extent the instincts of species may be improved and heightened, +has concluded that there is a natural progress from the inferior orders +of being towards the superior, and that the offspring of creatures low +in the scale may belong to a different and nobler species a few thousand +years hence. Never was there a fancy so wild and extravagant. The +principle of adaptation still leaves the vegetable a vegetable, and the +dog a dog. It is true that it is a law of nature that the chain of being +is in some degree a continuous chain, and the various classes of +existence shade into each other. All the animal families have their +connecting links. Geology abounds with creatures of the intermediate +class. + +Fishes seem to have been the master existences of two great geological +systems, mayhap of three, ere the age of reptiles began. Now, fishes +differ very much among themselves, some ranking nearly as low as worms, +some nearly as high as reptiles; and we find in the Old Red Sandstone +series of links which are wanting in the present creation, and the +absence of which occasions a wide gap between the two grand divisions of +fishes, the bony and the cartilaginous. + +Of all the organisms of the system one of the most extraordinary is the +pterichthys, or winged fish, which the writer had the pleasure of +introducing to the acquaintance of geologists. Had Lamarck been the +discoverer he would unquestionably have held that he had caught a fish +almost in the act of wishing itself into a bird. There are wings which +want only feathers, a body which seems to have been as well adapted for +passing through the air as through water, and a tail with which to +steer. + +My first idea regarding it was that I had discovered a connecting +link-between the tortoise and the fish. I submitted some of my specimens +to Mr. Murchison, and they furnished him with additional data by which +to construct the calculations he was then making respecting fossils, and +they added a new and very singular link to the chain of existence in its +relation to human knowledge. Agassiz confirmed the conclusions of +Murchison in almost every particular, deciding at once that the creature +must have been a fish. + +Next to the pterichthys of the Lower Old Red Sandstone I shall place its +contemporary the coccosteus of Agassiz--a fish which in some respects +must have resembled it. Both were covered with an armour of thickly +tubercled bony plates, and both furnished with a vertebrated tail. The +coccosteus seems to have been most abundant. Another of the families of +the ichthyolites of the Old Red Sandstone--the cephalaspis--seems +almost to constitute a connecting link between fishes and crustaceans. +In the present creation fishes are either osseous or cartilaginous, that +is, with bony skeletons, or with a framework of elastic, +semi-transparent animal matter, like the shark; and the ichthyolites of +the Old Red Sandstone unite these characteristics, resembling in some +respects the osseous and in others the cartilaginous tribes. Agassiz at +once confirmed my suspicion that the ichthyolites of the Old Red +Sandstone were intermediate. Though it required skill to determine the +place of the pterichthys and coccosteus there could be no mistaking the +osteolepis--it must have been a fish, and a handsome one, too. But while +its head resembled the heads of the bony fishes, its tail differed in no +respects from the tails of the cartilaginous ones. And so through the +discovery of extinct species the gaps between existing species have been +bridged. + + +_III.--Place-Fixing in the Dim Past_ + +The next step was to fix the exact place of the ichthyolites in the +geological scale, and this I was enabled to do by finding a large and +complete bed _in situ_. Its true place is a little more than a hundred +feet above the top, and not much more than a hundred yards above the +base of the great conglomerate. + +The Old Red Sandstone in Scotland and in England has its lower, middle, +and upper groups--three distinct formations. As the pterichthys and +coccosteus are the characteristic ichthyolites of the Lower Old Red +formation, so the cephalaspis distinguishes the middle or coronstone +division of the system in England. When we pass to the upper formation, +we find the holoptychius the most characteristic fossil. + +These fossils are found in a degree of entireness which depends less on +their age than on the nature of the rock in which they occur. Limestone +is the preserving salt of the geological world, and the conservative +qualities of the shales and stratified clays of the Lower Old Red +Sandstone are not much inferior to limestone itself; while in the Upper +Old Red the beds of consolidated sand are much less conservative of +organic remains. The older fossils, therefore, can be described almost +as minutely as the existence of the present creation, whereas the newer +fossils exist, except in a few rare cases, as fragments, and demand the +powers of a Cuvier or an Agassiz to restore them to their original +combinations. On the other hand, while the organisms of the Lower Old +Red are numerous and well preserved, those of the Upper Old Red are much +greater in individual size. In short, the fish of the lower ocean must +have ranged in size between a stickleback and a cod; whereas some of the +fish of the ocean of the Upper Sandstone were covered with scales as +large as oyster shells, and were armed with teeth that rivalled in size +those of the crocodile. + + +_IV.--Fish as Nature's Last Word_ + +I will now attempt to present to the reader the Old Red Sandstone as it +existed in time--during the succeeding periods of its formation, and +when its existences lived and moved as the denizens of primeval oceans. +We pass from the cemetery with its heaps of bones to the ancient city +full of life and animation in all its streets and dwellings. + +Before we commence our picture, two great geological periods have come +to their close, and the floor of the widely spread ocean is occupied to +the depth of many thousand feet by the remains of bygone existences. The +rocks of these two earlier periods are those of the Cambrian and +Silurian groups. The lower--Cambrian, representative of the first +glimmering twilight of being--must be regarded as a period of +uncertainty. It remains for future discoverers to determine regarding +the shapes of life that burrowed in its ooze or careered through the +incumbent waters. + +There is less doubt respecting the existences of the Silurian rocks. +Four distinct platforms of being range in it, the one over the other, +like the stories of a building. Life abounded on all these platforms, +and in shapes the most wonderful. In the period of the Upper Silurian +fish, properly so called, and of a very perfect organisation, had taken +precedence of the crustacean. These most ancient beings of their class +were cartilaginous fishes, and they appear to have been introduced by +myriads. Such are the remains of what seem to have been the first +vertebrata. + +The history of the period represented by the Old Red Sandstone seems, in +what now forms the northern half of Scotland, to have opened amid +confusion and turmoil. The finely laminated Tilestones of England were +deposited evidently in a calm sea. During the contemporary period the +space which now includes Orkney, Lochness, Dingwall, Gamrie, and many a +thousand square miles besides, was the scene of a shallow ocean, +perplexed by powerful currents and agitated by waves. A vast stratum of +water-rolled pebbles, varying in depth from a hundred feet to a hundred +yards, remains, in a thousand different localities, to testify to the +disturbing agencies of this time of commotion, though it is difficult to +conceive how the bottom of any sea could have been so violently and +equally agitated for so greatly extended a space. + +The period of this shallow and stormy ocean passed, and the bottom, +composed of the identical conglomerate which now forms the summit of +some of our loftiest mountains, sank to a depth so profound as to be +little affected by tides and tempests. During this second period there +took place a vast deposit of coarse sandstone strata, and the subsidence +continued until fully ninety feet had overlaid the conglomerate in +waters perfectly undisturbed. And here we find the first proof that this +ancient ocean literally swarmed with life--that its bottom was covered +with miniature forests of algae, and its waters darkened by immense +shoals of fish. I have seen the ichthyolite bed where they were as +thickly covered with fossil remains as I have ever seen a fishing-bank +covered with herrings. + +At this period some terrible catastrophe involved in sudden destruction +the fish of an area at least a hundred miles from boundary to boundary, +perhaps much more. The same platform in Orkney as in Cromarty is strewn +thick with remains which exhibit unequivocally the marks of violent +death. In what could it have originated? By what quiet but potent agency +of destruction could the innumerable existences of an area perhaps ten +thousand miles in extent be annihilated at once, and yet the medium in +which they lived be left undisturbed by its operations? The thought has +often struck me that calcined lime, cast out as ashes from some distant +crater and carried by the winds, might have been the cause of the widely +spread destruction to which the fossil organisms testify. I have seen +the fish of a small trouting stream, over which a bridge was in the +course of building, destroyed in a single hour, for a full mile below +the erection, by a few troughfuls of lime that fell into the water when +the centring was removed. + +The period of death passed, and over the innumerable dead there settled +a soft muddy sediment. For an unknown space of time, represented in the +formation by a deposit about fifty feet in thickness, the waters of the +depopulated area seem to have remained devoid of life. A few scales and +plates then begin to appear. The fish that had existed outside the chasm +seem to have gradually gained upon it as their numbers increased. + +The work of deposition went on and sandstone was overlaid by stratified +clay. This upper bed had also its organisms, but the circumstances were +less favourable to the preservation of entire ichthyolites than those in +which the organisms were wrapped up in their stony coverings. Age +followed age, generations were entombed in ever-growing depositions. +Vast periods passed, and it seemed as if the power of the Creator had +reached its extreme limit when fishes had been called into existence, +and our planet was destined to be the dwelling-place of no nobler +inhabitants. + +The curtain rises, and the scene is new. The myriads of the lower +formation have disappeared, and we are surrounded on an upper platform +by the existences of a later creation. Shoals of cephalaspides, +feathered with fins, sweep past. We see the distant gleam of scales, +that some of the coats glitter with enamel, that others bristle over +with minute thorny points. A huge crustacean, of uncouth proportions, +stalks over the weedy bottoms, or burrows in the hollows of the banks. +Ages and centuries pass--who can sum up their number?--for the depth of +this middle formation greatly exceeds that of the other two. + +The curtain rises. A last day had at length come to the period of the +middle formation, and in an ocean roughened by waves and agitated by +currents we find new races of existences. We may mark the clumsy bulk of +the Holoptychius conspicuous in the group. The shark family have their +representative as before; a new variety of the pterichthys spreads out +its spear-like wings at every alarm, like its predecessor of the lower +formation. Fish still remained the lords of creation, and their bulk, at +least, had become immensely more great. We began with an age of dwarfs, +we end with an age of giants, which is carried on into the lower coal +measures. We pursue our history no further? + +Has the last scene in the series arisen? Cuvier asked the question, +hesitated, and then decided in the negative, for he was too intimately +acquainted with the works of the Creator to think of limiting His power, +and he could anticipate a coming period in which man would have to +resign his post of honour to some nobler and wiser creature, the monarch +of a better and happier world. + + + + +SIR ISAAC NEWTON + +Principia + + Sir Isaac Newton was born at Woolsthorpe, Lincolnshire, England, + Dec. 25, 1642, the son of a small landed proprietor. For the famous + episode of the falling apple, Voltaire, who admirably explained his + system for his countrymen, is responsible. It was in 1680 that + Newton discovered how to calculate the orbit of a body moving under + a central force, and showed that if the force varied as the inverse + square of the distance, the orbit would be an ellipse with the + centre of force in one focus. The great discovery, which made the + writing of his "Philosophiae Naturalis Principia Mathematica" + possible, was that the attraction between two spheres is the same + as it would be if we supposed each sphere condensed to a point at + its centre. The book was published as a whole in 1687. Of its + author it was said by Lagrange that not only was he the greatest + genius that ever existed, but also the most fortunate, "for we + cannot find more than once a system of the world to establish." + Newton died on March 20, 1727. + + +Our design (writes Newton in his preface) not respecting arts but +philosophy, and our subject not manual but natural powers, we consider +those things which relate to gravity, levity, elastic force, the +resistance of fluids and the like forces, whether attractive or +impulsive; and, therefore, we offer this work as the mathematical +principles of philosophy, for all the difficulty of philosophy seems to +consist in this--from the phenomena of motions to investigate the forces +of nature, and from these forces to demonstrate the other phenomena, and +to this end the general propositions in the first and second book are +directed. In the third book, we give an example of this in the +explication of the system of the world; for by the propositions +mathematically demonstrated in the former books, we in the third derive +from the celestial phenomena the forces of gravity with which bodies +tend to the sun and the several planets. Then from these forces, by +other propositions which are also mathematical, we deduce the motions of +the planets, the comets, the moon, and the sea. + +Upon this subject I had (he says) composed the third book in a popular +method, that it might be read by many, but afterward, considering that +such as had not sufficiently entered into the principles could not +easily discern the strength of the consequences, nor lay aside the +prejudices to which they had been many years accustomed, therefore, to +prevent the disputes which might be raised upon such accounts, I chose +to reduce the substance of this book into the form of Propositions (in +the mathematical way). So that this third book is composed both "in +popular method" and in the form of mathematical propositions. + + +_Books I and II_ + +The principle of universal gravitation, namely, "That every particle of +matter is attracted by or gravitates to every other particle of matter +with a force inversely proportional to the squares of their distances," +is the discovery which characterises the "Principia." This principle the +author deduced from the motion of the moon and the three laws of Kepler; +and these laws in turn Newton, by his greater law, demonstrated to be +true. + +From the first law of Kepler, namely, the proportionality of the areas +to the times of their description, Newton inferred that the force which +retained the planet in its orbit was always directed to the sun. From +the second, namely, that every planet moves in an ellipse with the sun +as one of foci, he drew the more general inference that the force by +which the planet moves round that focus varies inversely as the square +of its distance therefrom. He demonstrated that a planet acted upon by +such a force could not move in any other curve than a conic section; and +he showed when the moving body would describe a circular, an elliptical, +a parabolic, or hyperbolic orbit. He demonstrated, too, that this force +or attracting, gravitating power resided in even the least particle; but +that in spherical masses it operates as if confined to their centres, so +that one sphere or body will act upon another sphere or body with a +force directly proportional to the quantity of matter and inversely as +the square of the distance between their centres, and that their +velocities of mutual approach will be in the inverse ratio of their +quantities of matter. Thus he outlined the universal law. + + +_The System of the World_ + +It was the ancient opinion of not a few (writes Newton in Book III.) in +the earliest ages of philosophy that the fixed stars stood immovable in +the highest parts of the world; that under the fixed stars the planets +were carried about the sun; that the earth, as one of the planets, +described an annual course about the sun, while, by a diurnal motion, it +was in the meantime revolved about its own axis; and that the sun, as +the common fire which served to warm the whole, was fixed in the centre +of the universe. It was from the Egyptians that the Greeks derived their +first, as well as their soundest notions of philosophy. It is not to be +denied that Anaxagoras, Democritus and others would have it that the +earth possessed the centre of the world, but it was agreed on both sides +that the motions of the celestial bodies were performed in spaces +altogether free and void of resistance. The whim of solid orbs was[1] of +later date, introduced by Endoxus, Calippus and Aristotle, when the +ancient philosophy began to decline. + +As it was the unavoidable consequence of the hypothesis of solid orbs +while it prevailed that the comets must be thrust down below the moon, +so no sooner had the late observations of astronomers restored the +comets to their ancient places in the higher heavens than these +celestial spaces were at once cleared of the encumbrance of solid orbs, +which by these observations were broken to pieces and discarded for +ever. + +Whence it was that the planets came to be retained within any certain +bounds in these free spaces, and to be drawn off from the rectilinear +courses, which, left to themselves, they should have pursued, into +regular revolutions in curvilinear orbits, are questions which we do not +know how the ancients explained; and probably it was to give some sort +of satisfaction to this difficulty that solid orbs were introduced. + +The later philosophers pretend to account for it either by the action of +certain vortices, as Kepler and Descartes, or by some other principle of +impulse or attraction, for it is most certain that these effects must +proceed from the action of some force or other. This we will call by the +general name of a centripetal force, as it is a force which is directed +to some centre; and, as it regards more particularly a body in that +centre, we call it circum-solar, circum-terrestrial, circum-jovial. + + +_Centre-Seeking Forces_ + +That by means of centripetal forces the planets may be retained in +certain orbits we may easily understand if we consider the motions of +projectiles, for a stone projected is by the pressure of its own weight +forced out of the rectilinear path, which, by the projection alone, it +should have pursued, and made to describe a curve line in the air; and +through that crooked way is at last brought down to the ground, and the +greater the velocity is with which it is projected the further it goes +before it falls to earth. We can, therefore, suppose the velocity to be +so increased that it would describe an arc of 1, 2, 5, 10, 100, 1,000 +miles before it arrived at the earth, till, at last, exceeding the +limits of the earth, it should pass quite by it without touching it. + +And because the celestial motions are scarcely retarded by the little or +no resistance of the spaces in which they are performed, to keep up the +parity of cases, let us suppose either that there is no air about the +earth or, at least, that it is endowed with little or no power of +resisting. + +And since the areas which by this motion it describes by a radius drawn +to the centre of the earth have previously been shown to be proportional +to the times in which they are described, its velocity when it returns +to the point from which it started will be no less than at first; and, +retaining the same velocity, it will describe the same curve over and +over by the same law. + +But if we now imagine bodies to be projected in the directions of lines +parallel to the horizon from greater heights, as from 5, 10, 100, 1,000 +or more miles, or, rather, as many semi-diameters of the earth, those +bodies, according to their different velocity and the different force of +gravity in different heights, will describe arcs either concentric with +the earth or variously eccentric, and go on revolving through the +heavens in those trajectories just as the planets do in their orbs. + +As when a stone is projected obliquely, the perpetual deflection thereof +towards the earth is a proof of its gravitation to the earth no less +certain than its direct descent when suffered to fall freely from rest, +so the deviation of bodies moving in free spaces from rectilinear paths +and perpetual deflection therefrom towards any place, is a sure +indication of the existence of some force which from all quarters impels +those bodies towards that place. + +That there are centripetal forces actually directed to the bodies of +the sun, of the earth, and other planets, I thus infer. + +The moon revolves about our earth, and by radii drawn to its centre +describes areas nearly proportional to the times in which they are +described, as is evident from its velocity compared with its apparent +diameter; for its motion is slower when its diameter is less (and +therefore its distance greater), and its motion is swifter when its +diameter is greater. + +The revolutions of the satellites of Jupiter about the planet are more +regular; for they describe circles concentric with Jupiter by equable +motions, as exactly as our senses can distinguish. + +And so the satellites of Saturn are revolved about this planet with +motions nearly circular and equable, scarcely disturbed by any +eccentricity hitherto observed. + +That Venus and Mercury are revolved about the sun is demonstrable from +their moon-like appearances. And Venus, with a motion almost uniform, +describes an orb nearly circular and concentric with the sun. But +Mercury, with a more eccentric motion, makes remarkable approaches to +the sun and goes off again by turns; but it is always swifter as it is +near to the sun, and therefore by a radius drawn to the sun still +describes areas proportional to the times. + +Lastly, that the earth describes about the sun, or the sun about the +earth, by a radius from one to the other, areas exactly proportional to +the times is demonstrable from the apparent diameter of the sun compared +with its apparent motion. + +These are astronomical experiments; from which it follows that there are +centripetal forces actually directed to the centres of the earth, of +Jupiter, of Saturn, and of the sun.[2] + +That these forces decrease in the duplicate proportion of the distances +from the centre of every planet appears by Cor. vi., Prop. iv., Book +I.[3] for the periodic times of the satellites of Jupiter are one to +another in the sesquiplicate proportion of their distances from the +centre of this planet. Cassini assures us that the same proportion is +observed in the circum-Saturnal planets. In the circum-solar planets +Mercury and Venus, the same proportional holds with great accuracy. + +That Mars is revolved about the sun is demonstrated from the phases +which it shows and the proportion of its apparent diameters; for from +its appearing full near conjunction with the sun and gibbous in its +quadratures,[4] it is certain that it travels round the sun. And since +its diameter appears about five times greater when in opposition to the +sun than when in conjunction therewith, and its distance from the earth +is reciprocally as its apparent diameter, that distance will be about +five times less when in opposition to than when in conjunction with the +sun; but in both cases its distance from the sun will be nearly about +the same with the distance which is inferred from its gibbous appearance +in the quadratures. And as it encompasses the sun at almost equal +distances, but in respect of the earth is very unequally distant, so by +radii drawn to the sun it describes areas nearly uniform; but by radii +drawn to the earth it is sometimes swift, sometimes stationary, and +sometimes retrograde. + +That Jupiter in a higher orbit than Mars is likewise revolved about the +sun with a motion nearly equable as well in distance as in the areas +described, I infer from Mr. Flamsted's observations of the eclipses of +the innermost satellite; and the same thing may be concluded of Saturn +from his satellite by the observations of Mr. Huyghens and Mr. Halley. + +If Jupiter was viewed from the sun it would never appear retrograde or +stationary, as it is seen sometimes from the earth, but always to go +forward with a motion nearly uniform. And from the very great inequality +of its apparent geocentric motion we infer--as it has been previously +shown that we may infer--that the force by which Jupiter is turned out +of a rectilinear course and made to revolve in an orbit is not directed +to the centre of the earth. And the same argument holds good in Mars and +in Saturn. Another centre of these forces is, therefore, to be looked +for, about which the areas described by radii intervening may be +equable; and that this is the sun, we have proved already in Mars and +Saturn nearly, but accurately enough in Jupiter. + +The distances of the planets from the sun come out the same whether, +with Tycho, we place the earth in the centre of the system, or the sun +with Copernicus; and we have already proved that, these distances are +true in Jupiter. Kepler and Bullialdus have with great care determined +the distances of the planets from the sun, and hence it is that their +tables agree best with the heavens. And in all the planets, in Jupiter +and Mars, in Saturn and the earth, as well as in Venus and Mercury, the +cubes of their distances are as the squares of their periodic times; +and, therefore, the centripetal circum-solar force throughout all the +planetary regions decreases in the duplicate proportion of the distances +from the sun. Neglecting those little fractions which may have arisen +from insensible errors of observation, we shall always find the said +proportion to hold exactly; for the distances of Saturn, Jupiter, Mars, +the Earth, Venus, and Mercury from the sun, drawn from the observations +of astronomers, are (Kepler) as the numbers 951,000, 519,650, 152,350, +100,000, 70,000, 38,806; or (Bullialdus) as the numbers 954,198, +522,520, 152,350, 100,000, 72,398, 38,585; and from the periodic times +they come out 953,806, 520,116, 152,399, 100,000, 72,333, 38,710. Their +distances, according to Kepler and Bullialdus, scarcely differ by any +sensible quantity, and where they differ most the differences drawn from +the periodic times fall in between them. + + +_Earth as a Centre_ + +That the circum-terrestrial force likewise decreases in the duplicate +proportion of the distances, I infer thus: + +The mean distance of the moon from the centre of the earth is, we may +assume, sixty semi-diameters of the earth; and its periodic time in +respect of the fixed stars 27 days 7 hr. 43 min. Now, it has been shown +in a previous book that a body revolved in our air, near the surface of +the earth supposed at rest, by means of a centripetal force which should +be to the same force at the distance of the moon in the reciprocal +duplicate proportion of the distances from the centre of the earth, that +is, as 3,600 to 1, would (secluding the resistance of the air) complete +a revolution in 1 hr. 24 min. 27 sec. + +Suppose the circumference of the earth to be 123,249,600 Paris feet, +then the same body deprived of its circular motion and falling by the +impulse of the same centripetal force as before would in one second of +time describe 15-1/12 Paris feet. This we infer by a calculus formed +upon Prop. xxxvi. ("To determine the times of the descent of a body +falling from a given place"), and it agrees with the results of Mr. +Huyghens's experiments of pendulums, by which he demonstrated that +bodies falling by all the centripetal force with which (of whatever +nature it is) they are impelled near the surface of the earth do in one +second of time describe 15-1/12 Paris feet. + +But if the earth is supposed to move, the earth and moon together will +be revolved about their common centre of gravity. And the moon (by Prop, +lx.) will in the same periodic time, 27 days 7 hr. 43 min., with the +same circum-terrestrial force diminished in the duplicate proportion of +the distance, describe an orbit whose semi-diameter is to the +semi-diameter of the former orbit, that is, to the sixty semi-diameters +of the earth, as the sum of both the bodies of the earth and moon to the +first of two mean proportionals between this sum and the body of the +earth; that is, if we suppose the moon (on account of its mean apparent +diameter 31-1/2 min.) to be about 1/42 of the earth, as 43 to (42 + +42^2)^1/3 or as about 128 to 127. And, therefore, the semi-diameter of +the orbit--that is, the distance of the centres of the moon and +earth--will in this case be 60-1/2 semi-diameters of the earth, almost +the same with that assigned by Copernicus; and, therefore, the duplicate +proportion of the decrement of the force holds good in this distance. +(The action of the sun is here disregarded as inconsiderable.) + +This proportion of the decrement of the forces is confirmed from the +eccentricity of the planets, and the very slow motion of their apsides; +for in no other proportion, it has been established, could the +circum-solar planets once in every revolution descend to their least, +and once ascend to their greatest distance from the sun, and the places +of those distances remain immovable. A small error from the duplicate +proportion would produce a motion of the apsides considerable in every +revolution, but in many enormous. + + +_The Tides_ + +While the planets are thus revolved in orbits about remote centres, in +the meantime they make their several rotations about their proper axes: +the sun in 26 days, Jupiter in 9 hr. 56 min., Mars in 24-2/3 hr., Venus +in 23 hr., and in like manner is the moon revolved about its axis in 27 +days 7 hr. 43 min.; so that this diurnal motion is equal to the mean +motion of the moon in its orbit; upon which account the same face of the +moon always respects the centre about which this mean motion is +performed--that is, the exterior focus of the moon's orbit nearly. + +By reason of the diurnal revolutions of the planets the matter which +they contain endeavours to recede from the axis of this motion; and +hence the fluid parts, rising higher towards the equator than about the +poles, would lay the solid parts about the equator under water if those +parts did not rise also; upon which account the planets are something +thicker about the equator than about the poles. + +And from the diurnal motion and the attractions of the sun and moon our +sea ought twice to rise and twice to fall every day, as well lunar as +solar. But the two motions which the two luminaries raise will not +appear distinguished but will make a certain mixed motion. In the +conjunction or opposition of the luminaries their forces will be +conjoined and bring on the greatest flood and ebb. In the quadratures +the sun will raise the waters which the moon depresseth and depress the +waters which the moon raiseth; and from the difference of their forces +the smallest of all tides will follow. + +But the effects of the lumniaries depend upon their distances from the +earth, for when they are less distant their effects are greater and when +more distant their effects are less, and that in the triplicate +proportion of their apparent diameters. Therefore it is that the sun in +winter time, being then in its perigee, has a greater effect, whether +added to or subtracted from that of the moon, than in the summer season, +and every month the moon, while in the perigee raiseth higher tides than +at the distance of fifteen days before or after when it is in its +apogee. + +The fixed stars being at such vast distances from one another, can +neither attract each other sensibly nor be attracted by our sun. + + +_Comets_ + +There are three hypotheses about comets. For some will have it that they +are generated and perish as often as they appear and vanish; others that +they come from the regions of the fixed stars, and are near by us in +their passage through the sytem of our planets; and, lastly, others that +they are bodies perpetually revolving about the sun in very eccentric +orbits. + +In the first case, the comets, according to their different velocities, +will move in conic sections of all sorts; in the second they will +describe hyperbolas; and in either of the two will frequent +indifferently all quarters of the heavens, as well those about the poles +as those towards the ecliptic; in the third their motions will be +performed in eclipses very eccentric and very nearly approaching to +parabolas. But (if the law of the planets is observed) their orbits will +not much decline from the plane of the ecliptic; and, so far as I could +hitherto observe, the third case obtains; for the comets do indeed +chiefly frequent the zodiac, and scarcely ever attain to a heliocentric +latitude of 40 degrees. And that they move in orbits very nearly +parabolical, I infer from their velocity; for the velocity with which a +parabola is described is everywhere to the velocity with which a comet +or planet may be revolved about the sun in a circle at the same +distance in the subduplicate ratio of 2 to 1; and, by my computation, +the velocity of comets is found to be much about the same. I examined +the thing by inferring nearly the velocities from the distances, and the +distances both from the parallaxes and the phenomena of the tails, and +never found the errors of excess or defect in the velocities greater +than what might have arisen from the errors in the distances collected +after that manner. + + + + +SIR RICHARD OWEN + +Anatomy of Vertebrates + + Sir Richard Owen, the great naturalist, was born July 20, 1804, at + Lancaster, England, and received his early education at the grammar + school of that town. Thence he went to Edinburgh University. In + 1826 he was admitted a member of the English College of Surgeons, + and in 1829 was lecturing at St. Bartholomew's Hospital, London, + where he had completed his studies. His "Memoir on the Pearly + Nautillus," published in 1832, placed him, says Huxley, "at a bound + in the front rank of anatomical monographers," and for sixty-two + years the flow of his contributions to scientific literature never + ceased. In 1856 he was appointed to take charge of the natural + history departments of the British Museum, and before long set + forth views as to the inadequacy of the existing accommodation, + which led ultimately to the foundation of the buildings now devoted + to this purpose in South Kensington. Owen died on December 18, + 1892. His great book, "Comparative Anatomy and Physiology of the + Vertebrates," was completed in 1868, and since Cuvier's + "Comparative Anatomy," is the most monumental treatise on the + subject by any one man. Although much of the classification adopted + by Owen has not been accepted by other zoologists, yet the work + contains an immense amount of information, most of which was gained + from Owen's own personal observations and dissections. + + +_I.--Biological Questions of 1830_ + +At the close of my studies at the Jardin des Plantes, Paris, in 1831, I +returned strongly moved to lines of research bearing upon the then +prevailing phases of thought on some biological questions. + +The great master in whose dissecting rooms I was privileged to work held +that species were not permanent as a fact established inductively on a +wide basis of observation, by which comparative osteology had been +created. Camper and Hunter suspected the species might be transitory; +but Cuvier, in defining the characters of his anaplotherium and +palaeotherium, etc., proved the fact. Of the relation of past to present +species, Cuvier had not an adequate basis for a decided opinion. +Observation of changes in the relative position of land and sea +suggested to him one condition of the advent of new species on an island +or continent where old species had died out. This view he illustrates by +a hypothetical case of such succession, but expressly states: "I do not +assert that a new creation was necessary to produce the species now +existing, but only that they did not exist in the same regions, and must +have come from elsewhere." Geoffrey Saint Hilaire opposed to Cuvier's +inductive treatment of the question the following expression of belief: +"I have no doubt that existing animals are directly descended from the +animals of the antediluvian world," but added, "it is my belief that the +season has not yet arrived for a really satisfying knowledge of +geology." + +The main collateral questions argued in their debates appeared to me to +be the following: + +Unity of plan or final purpose, as a governing condition of organic +development? + +Series of species, uninterrupted or broken by intervals? + +Extinction, cataclysmal or regulated? + +Development, by epigenesis or evolution? + +Primary life, by miracle or secondary law? + +Cuvier held the work of organisation to be guided and governed by final +purpose or adaptation. Geoffrey denied the evidence of design and +contended for the principle which he called "unity of composition," as +the law of organisation. Most of his illustrations were open to the +demonstration of inaccuracy; and the language by which disciples of the +kindred school of Schelling illustrated in the animal structure the +transcendental idea of the whole in every part seemed little better than +mystical jargon. With Cuvier, answerable parts occurred in the +zoological scale because they had to perform similar functions. + +As, however, my observations and comparisons accumulated, they enforced +a reconsideration of Cuvier's conclusions. To demonstrate the evidence +of the community of organisation I found the artifice of an archetype +vertebrate animal essential; and from the demonstration of its +principle, which I then satisfied myself was associated with and +dominated by that of "adaptation to purpose," the step was inevitable to +the conception of the operation of a secondary cause of the entire +series of species, such cause being the servant of predetermining +intelligent will. + +But besides "derivation" or "filiation" another principle influencing +organisation became recognisable, to which I gave the name of +"irrelative repetition," or "vegetative repetition." The demonstrated +constitution of the vertebrate endoskeleton as a series of essentially +similar segments appeared to me to illustrate the law of irrelative +repetition. + +These results of inductive research swayed me in rejecting direct or +miraculous creation, and in recognising a "natural law or secondary +cause" as operative in the production of species "in orderly succession +and progression." + + +_II.--Succession of Species, Broken or Linked?_ + +To the hypothesis that existing are modifications of extinct species, +Cuvier replied that traces of modification were due from the fossil +world. "You ought," he said, "to be able to show the intermediate forms +between the palaeotherium and existing hoofed quadrupeds." + +The progress of palaeontology since 1830 has brought to light many +missing links unknown to the founder of the science. The discovery of +the remains of the hipparion supplied one of the links required by +Cuvier, and it is significant that the remains of such three-toed horses +are found only in deposits of that tertiary period which intervene +between the older palaeotherian one and the newer strata in which the +modern horse first appears to have lost its lateral hooflets. + +The molar series of the horse includes six large complex grinders +individually recognisable by developmental characters. The +representative of the first premolar is minute and soon shod. Its +homologue in palaeotherium is functionally developed and retained, that +type-dentition being adhered to. In hipparion this tooth is smaller than +in palaeotherium, but functional and permanent. The transitory and +singularly small and simple denticle in the horse exemplifies the +rudiment of an ancestral structure in the same degree as do the hoofless +splint-bones; just as the spurious hoofs dangling therefrom in hipparion +are retained rudiments of the functionally developed lateral hoofs in +the broader foot of palaeotherium. + +Other missing links of this series of species have also been supplied. + +How then is the origin of these intermediate gradations to be +interpreted? If the alternative--species by miracle or by law--be +applied to palaeotherium, paloplotherium, anchitherium, hipparion, equus, +I accept the latter without misgiving, and recognise such law as +continuously operative throughout tertiary time. + +In respect to its law of operation we may suppose Lamarck to say, "as +the surface of the earth consolidated, the larger and more produced +mid-hoof of the old three-toed pachyderius took a greater share in +sustaining the animal's weight; and more blood being required to meet +the greater demand of the more active mid-toe, it grew; whilst, the +side-toes, losing their share of nourishment and becoming more and more +withdrawn from use, shrank"--and so on. Mr. Darwin, I conceive, would +modify this by saying that some individuals of palaeotherium happening to +be born with a larger and longer middle toe, and with shorter and +smaller side-toes, such variety was better adapted to prevailing altered +conditions of the earth's surface than the parental form; and so on, +until finally the extreme equine modifications of foot came to be +"naturally selected." But the hypothesis of appetency and volition, as +of natural selection, are less applicable, less intelligible, in +connection with the changes in the teeth. + +I must further observe that to say the palaeotherium has graduated into +equus by "natural selection" is an explanation of the process of the +same kind and value as that by which the secretion of bile was +attributed to the "appetency" of the liver for the elements of bile. +One's surprise is that such explanatory devices should not have died out +with the "archeus faber," the "nisus formations," and other +self-deceiving, world-beguiling simulacra of science, with the last +century; and that a resuscitation should have had any success in the +present. + +What, then, are the facts on which any reasonable or intelligible +conception can be formed of the mode of operation of the derivative law +exemplified in the series linking on palaeotherium to equus? A very +significant one is the following. A modern horse occasionally comes into +the world with the supplementary ancestral hoofs. From Valerius Maximus, +who attributes the variety to Bucephalus downwards, such "polydactyle" +horses have been noted as monsters and marvels. In one of the latest +examples, the inner splint-bone, answering to the second metacarpal of +the pentadactyle foot, supported phalanges and a terminal hoof +resembling the corresponding one in hipparion. And the pairing of horses +with the meterpodials bearing, according to type, phalanges and hoofs +might restore the race of hipparions. + +Now, the fact suggesting such possibility teaches that the change would +be sudden and considerable; it opposes the idea that species are +transmuted by minute and slow degrees. It also shows that a species +might originate independently of the operation of any external +influence; that change of structure would precede that of use and +habit; that appetency, impulse, ambient medium, fortuitous fitness of +surrounding circumstances, or a personified "selecting nature" would +have had no share in the transmutative act. + +Thus I have been led to recognise species as exemplifying the continuous +operation of natural law, or secondary cause; and that not only +successively but progressively; "from the first embodiment of the +vertebrate idea under its old ichthyic vestment until it became arrayed +in the glorious garb of the human form." + + +_III.--Extinction--Cataclysmal or Regulated_ + +If the species of palaeothere, paloplothere, anchithere, hipparion, and +horse be severally deemed due to remotely and successively repeated acts +of creation; the successive going out of such species must have been as +miraculous as their coming in. Accordingly, in Cuvier's "Discourse on +Revolutions of the Earth's Surface" we have a section of "Proofs that +these revolutions have been numerous," and another of "Proofs that these +revolutions have been sudden." But as the discoveries of palaeontologists +have supplied the links between the species held to have perished by the +cataclysms, so each successive parcel of geological truth has tended to +dissipate the belief in the unusually sudden and violent nature of the +changes recognisable in the earth's surface. In specially directing my +attention to this moot point, whilst engaged in investigations of fossil +remains, I was led to recognise one cause of extinction as being due to +defeat in the contest which the individual of each species had to +maintain against the surrounding agencies which might militate against +its existence. This principle has received a large and most instructive +accession of illustrations from the labours of Charles Darwin; but he +aims to apply it not only to the extinction but to the origin of +species. + +Although I fail to recognise proof of the latter bearing of the battle +of life, the concurrence of so much evidence in favour of extinction by +law is, in like measure, corroborative of the truth of the ascription of +the origin of species to a secondary cause. + +What spectacle can be more beautiful than that of the inhabitants of the +calm expanse of water of an atoll encircled by its ring of coral rock! +Leaving locomotive frequenters of the calcarious basin out of the +question, we may ask, Was direct creation after the dying out of its +result as a "rugose coral" repeated to constitute the succeeding and +superseding "tabulate coral"? Must we also invoke the miraculous power +to initiate every distinct species of both rugosa and tabulata? These +grand old groups have had their day and are utterly gone. When we +endeavour to conceive or realise such mode of origin, not of them only +but of their manifold successors, the miracle, by the very +multiplication of its manifestations, becomes incredible--inconsistent +with any worthy conception of an all-seeing, all-provident Omnipotence. + +Being unable to accept the volitional hypothesis (of Lamarck) or the +selective force exerted by outward circumstances (Darwin), I deem an +innate tendency to deviate from parental type, operating through periods +of adequate duration, to be the most probable way of operation of the +secondary law whereby species have been derived one from another. + +According to my derivative hypothesis a change takes place first in the +structure of the animal, and this, when sufficiently advanced, may lead +to modifications of habits. But species owe as little to the accidental +concurrence of environing circumstances as kosmos depends upon a +fortuitous concourse of atoms. A purposive route of development and +change of correlation and inter-dependence, manifesting intelligent +will, is as determinable in the succession of races as in the +development and organisation of the individual. + +Derivation holds that every species changes in time, by virtue of +inherent tendencies thereto. Natural selection holds that no such change +can take place without the influence of altered external circumstances +educing or eliciting such change. + +Derivation sees among the effects of the innate tendency to change, +irrespective of altered surrounding circumstances, a manifestation of +creative power in the variety and beauty of the results; and, in the +ultimate forthcoming of a being susceptible of appreciating such beauty, +evidence of the preordaining of such relation of power to the +appreciation. Natural selection acknowledges that if power or beauty, in +itself, should be a purpose in creation, it would be absolutely fatal to +it as a hypothesis. + +Natural selection sees grandeur in the "view of life, with its several +powers, having been originally breathed by the Creator into a few forms +or into one." Derivation sees, therein, a narrow invocation of a special +miracle and an unworthy limitation of creative power, the grandeur of +which is manifested daily, hourly, in calling into life many forms, by +conversion of physical and chemical into vital modes of force, under as +many diversified conditions of the requisite elements to be so combined. + +Natural selection leaves the subsequent origin and succession of species +to the fortuitous concurrence of outward conditions; derivation +recognises a purpose in the defined and preordained course, due to +innate capacity or power of change, by which homogeneously-created +protozoa have risen to the higher forms of plants and animals. + +The hypothesis of derivation rests upon conclusions from four great +series of inductively established facts, together with a probable result +of facts of a fifth class; the hypothesis of natural selection totters +on the extension of a conjectural condition explanatory of extinction to +the origination of species, inapplicable in that extension to the +majority of organisms, and not known or observed to apply to the origin +of any species. + + +_IV.--Epigenesis or Evolution?_ + +The derivative origin of species, then, being at present the most +admissible one, and the retrospective survey of such species showing +convergence, as time recedes, to more simplified or generalised +organisations, the result to which the suggested train of thought +inevitably leads is very analogous in each instance. If to kosmos or the +mundane system have been allotted powers equivalent to the development +of the several grades of life, may not the demonstrated series of +conversions of force have also included that into the vital form? + +In the last century, physiologists were divided as to the principle +guiding the work of organic development. + +The "evolutionists" contended that the new being preexisted in a +complete state of formation, needing only to be vivified by impregnation +in order to commence the series of expansions or disencasings, +culminating in the independent individual. + +The "epigenesists" held that both the germ and its subsequent organs +were built up of juxtaposed molecules according to the operation of a +developmental force, or "nisus formations." + +At the present day the question may seem hardly worth the paper on which +it is referred to. Nevertheless, "pre-existence of germs" and evolution +are logically inseparable from the idea of species by primary +miraculously-created individuals. Cuvier, therefore, maintained both as +firmly as did Haller. In the debates of 1830 I remained the thrall of +that dogma in regard to the origin of single-celled organisms whether in +or out of body. Every result of formfaction, I believed, with most +physiologists, to be the genetic outcome of a pre-existing "cell." The +first was due to miraculous interposition and suspension of ordinary +laws; it contained potentially all future possible cells. +Cell-development exemplified evolution of pre-existing germs, the +progeny of the primary cell. They progagated themselves by +self-division, or by "proliferation" of minutes granules or atoms, +which, when properly nourished, again multiplied by self-division, and +grew to the likeness of the parent cells. + +It seems to me more consistent with the present phase of dynamical +science and the observed graduations of living things to suppose the +sarcode or the "protogenal" jelly-speck should be formable through the +concurrence of conditions favouring such combination of their elements, +and involving a change of force productive of their contractions and +extensions, molecular attractions, and repulsions--and the sarcode has +so become, from the period when its irrelative repetitions resulted in +the vast indefinite masses of the "eozoon," exemplifying the earliest +process of "formification" or organic crystallisation--than that all +existing sarcodes or "protogenes" are the result of genetic descent from +a germ or cell due to a primary act of miraculous interposition. + +I prefer, while indulging in such speculations, to consider the various +daily nomogeneously developed forms of protozoal or protistal jellies, +sarcodes, and single-celled organisms, to have been as many roots from +which the higher grades have ramified than that the origin of the whole +organic creation is to be referred, as the Egyptian priests did that of +the universe, to a single egg. + +Amber or steel, when magnetised, seem to exercise "selection"; they do +not attract all substances alike. A speck of protogenal jelly or +sarcode, if alive, shows analogous relations to certain substances; but +the soft yielding tissue allows the part next the attractive matter to +move thereto, and then, by retraction, to draw such matter into the +sarcodal mass, which overspreads, dissolves, and assimilates it. The +term "living" in the one case is correlative with the term "magnetic" in +the other. A man perceives ripe fruit; he stretches out his hand, +plucks, masticates, swallows, and digests it. + +The question then arises whether the difference between such series of +actions in the man and the attractive and assimilative movement of the +amaeba be greater or less than the difference between these acts of the +amaeba and the attracting and retaining acts of the magnet. + +The question, I think, may be put with some confidence as to the quality +of the ultimate reply whether the amaebal phenomena are so much more +different, or so essentially different, from the magnetic phenomena than +they are from the mammalian phenomena, as to necessitate the invocation +of a special miracle for their manifestation. It is analogically +conceivable that the same cause which has endowed His world with power +convertible into magnetic, electric, thermotic and other forms or modes +of force, has also added the conditions of conversion into the vital +force. + +From protozoa or protista to plants and animals the graduation is closer +than from magnetised iron to vitalised sarcode. From reflex acts of the +nervous system animals rise to sentient and volitional ones. And with +the ascent are associated brain-cells progressively increasing in size +and complexity. Thought relates to the "brain" of man as does +electricity to the nervous "battery" of the torpedo; both are forms of +force and the results of action of their respective organs. + +Each sensation affects a cerebral fibre, and, in so affecting it, gives +it the faculty of repeating the action, wherein memory consists and +sensation in a dream. + +If the hypothesis of an abstract entity produces psychological phenomena +by playing upon the brain as a musician upon his instrument be rejected, +and these phenomena be held to be the result of cerebral actions, an +objection is made that the latter view is "materialistic" and adverse to +the notion of an independent, indivisible, "immaterial," mental +principle or soul. + +But in the endeavour to comprehend clearly and explain the functions of +the combination of forces called "brain," the physiologist is hindered +and troubled by the views of the nature of those cerebral forces which +the needs of dogmatic theology have imposed on mankind. How long +physiologists would have entertained the notion of a "life," or "vital +principle," as a distinct entity if freed from this baneful influence +may be questioned; but it can be truly affirmed that physiology has now +established and does accept the truth of that statement of Locke--"the +life, whether of a material or immaterial substance, is not the +substance itself, but an affection of it." + + + + +RUDOLF VIRCHOW + +Cellular Pathology + + Rudolf Virchow, the son of a small farmer and shopkeeper, was born + at Schivelbein, in Pomerania, on October 13, 1821. He graduated in + medicine at Berlin, and was appointed lecturer at the University, + but his political enthusiasm brought him into disfavour. In 1849 he + was removed to Wurzburg, where he was made professor of pathology, + but in 1856 he returned to Berlin as Professor and Director of the + Pathological Institute, and there acquired world-wide fame. His + celebrated work, "Cellular Pathology as based on Histology," + published in 1856, marks a distinct epoch in the science. Virchow + established what Lord Lister describes as "the true and fertile + doctrine that every morbid structure consists of cells which have + been derived from pre-existing cells as a progeny." Virchow was not + only distinguished as a pathologist, he also gained considerable + fame as an archaeologist and anthropologist. During the wars of 1866 + and 1870-71, he equipped and drilled hospital corps and ambulance + squads, and superintended hospital trains and the Berlin military + hospital. War over, he directed his attention to sanitation and the + sewage problems of Berlin. Virchow was a voluminous author on a + variety of subjects, perhaps his most well-known works being + "Famine Fever" and "Freedom of Science." He died on September 5, + 1902. + + +_The Cell and the Tissues_ + +The chief point in the application of Histology to Pathology is to +obtain recognition of the fact that the cell is really the ultimate +morphological element in which there is any manifestation of life. + +In certain respects animal cells differ from vegetable cells; but in +essentials they are the same; both consist of matter of a nitrogenous +nature. + +When we examine a simple cell, we find we can distinguish morphological +parts. In the first place, we find in the cell a round or oval body +known as the nucleus. Occasionally the nucleus is stallate or angular; +but as a rule, so long as cells have vital power, the nucleus maintains +a nearly constant round or oval shape. The nucleus in its turn, in +completely developed cells, very constantly encloses another structure +within itself--the so-called nucleolus. With regard to the question of +vital form, it cannot be said of the nucleolus that it appears to be an +absolute essential, and in a considerable number of young cells it has +as yet escaped detection. On the other hand, we regularly meet with it +in fully-developed, older forms, and it therefore seems to mark a higher +degree of development in the cell. + +According to the view which was put forward in the first instance by +Schleiden, and accepted by Schwann, the connection between the three +co-existent cell-constituents was long thought to be of this nature: +that the nucleolus was the first to show itself in the development of +tissues, by separating out of a formative fluid (blastema, +cyto-blastema), that it quickly attained a certain size, that then fine +granules were precipitated out of the blastema and settled around it, +and that about these there condensed a membrane. In this way a nucleus +was formed about which new matter gradually gathered, and in due time +produced a little membrane. This theory of the formation of the cell is +designated the theory of free cell formation--a theory which has been +now almost entirely abandoned. + +It is highly probable that the nucleus plays an extremely important part +within the cell--a part less connected with the function and specific +office of the cell, than with its maintenance and multiplication as a +living part. The specific (animal) function is most distinctly +manifested in muscles, nerves, and gland cells, the peculiar actions of +which--contraction, sensation, and secretion--appear to be connected in +no direct manner with the nuclei. But the permanency of the cell as an +element seems to depend on nucleus, for all cells which lose their +nuclei quickly die, and break up, and disappear. + +Every organism, whether vegetable or animal, must be regarded as a +progressive total, made up of a larger or smaller number of similar or +dissimilar cells. Just as a tree constitutes a mass arranged in a +definite manner in which, in every single part, in the leaves as in the +root, in the trunk as in the blossom, cells are discovered to be the +ultimate elements, so it is with the forms of animal life. Every animal +presents itself as a sum of vital unities, every one of which manifests +all the characteristics of life. The characteristics and unity of life +cannot be limited to any one particular spot in an organism (for +instance, to the brain of a man) but are to be found only in the +definite, constantly recurring structure, which every individual element +displays. A so-called individual always represents an arrangement of a +social kind, in which a number of individual existences are mutually +dependent, but in such a way that every element has its own special +action, and even though it derive its stimulus to activity from other +parts, yet alone affects the actual performance of its duties. + +Between cells there is a greater or less amount of a homogeneous +substance--the _intercellular substance_. According to Schwann, the +intercellular substance was cyto-blastema destined for the development +of new cells; I believe this is not so, I believe that the intercellular +substance is dependent in a certain definite manner upon the cells, and +that certain parts of it belong to one cell and parts to another. + +At various times, fibres, globules, and elementary granules, have been +regarded as histological starting-points. Now, however, we have +established the general principle that no development of any kind begins +_de novo_ and that as spontaneous generation is impossible in the case +of entire organisms, so also it is impossible in the case of individual +parts. No cell can build itself up out of non-cellular material. Where a +cell arises, there a cell must have previously existed (omnis cellula e +cellula), just as an animal can spring only from an animal, and a plant +only from a plant. No developed tissues can be traced back to anything +but a cell. + +If we wish to classify tissues, a very simple division offers itself. We +have (a) tissues which consist exclusively of cells, where cell lies +close to cell. (b) Tissues in which the cells are separated by a certain +amount of intercellular substance. (c) Tissues of a high or peculiar +type, such as the nervous and muscular systems and vessels. An example +of the first class is seen in the _epithelial_ tissues. In these, cell +lies close to cell, with nothing between. + +The second class is exemplified in the _connective_ tissues--tissues +composed of intercellular substance in which at certain intervals cells +lie embedded. + +Muscles, nerves, and vessels form a somewhat heterogeneous group. The +idea suggests itself that we have in all three structures to deal with +real tubes filled with more or less movable contents. This view is, +however, inadequate, since we cannot regard the blood as analogous to +the medullary substance of the nerve, or contractile substance of a +muscular fasciculus. + +The elements of muscle have generally been regarded as the most simple. +If we examine an ordinary red muscle, we find it to be composed of a +number of cylindrical fibres, marked with transverse and longitudinal +striae. If, now, we add acetic acid, we discover also tolerably large +nuclei with nucleoli. Thus we obtain an appearance like an elongated +cell, and there is a tendency to regard the primitive fasciculus as +having sprung from a single cell. To this view I am much inclined. + +Pathological tissues arise from normal tissues; and there is no form of +morbid growth which cannot in its elements be traced back to some model +which had previously maintained an independent existence in the economy. +A classification, also, of pathological growths may be made on exactly +the same plan as that which we have suggested in the case of the normal +tissues. + + +_Nutrition, Blood, and Lymph. Pus_ + +Nutritive material is carried to the tissues by the blood; but the +material is accepted by the tissues only in accordance with their +requirements for the moment, and is conveyed to the individual districts +in suitable quantities. The muscular elements of the arteries have the +most important influence upon the quantity of the blood distributed, and +their elastic elements ensure an equable stream; but it is chiefly the +simple homogeneous membrane of the capillaries that influences the +permeation of the fluids. Not all the peculiarities, however, in the +interchange of nutritive material are to be attributed to the capillary +wall, for no doubt there are chemical affinities which enable certain +parts specially to attract certain substances from the blood. We know, +for example, that a number of substances are introduced into the body +which have special affinities for the nerve tissues, and that certain +materials are excreted by certain organs. We are therefore compelled to +consider the individual elements as active agents of the attraction. If +the living element be altered by disease, then it loses its power of +specific attraction. + +I do not regard the blood as the cause of chronic dyscrasiae; for I do +not regard the blood as a permanent tissue independently regenerating +and propagating itself, but as a fluid in a state of constant dependence +upon other parts. I consider that every dyscrasia _is dependent upon a +permanent supply of noxious ingredients from certain sources_. As a +continual ingestion of injurious food is capable of vitiating the blood, +in like manner persistent disease in a definite organ is able to furnish +the blood with a continual supply of morbid materials. + +The essential point, therefore, is to search for the _local sources_ of +the different dyscrasiae which cause disorders of the blood, for every +permanent change which takes place in the condition of the circulating +juices must be derived from definite organs or tissues. + +The blood contains certain morphological elements. It contains a +substance, _fibrine_, which appears as fibrillac when the blood clots, +and red and colourless blood corpuscles. + +The red blood corpuscles contain no nuclei except at certain periods of +the development of the embyro. They are lighter or darker red according +to the oxygen they contain. When treated with concentrated fluids they +shrivel; when treated with diluted fluids they swell. They are rather +coin-shaped, and when a drop of blood is quiet they are usually found +aggregated in rows, like rouleaux of money. + +The colourless corpuscles are much less numerous than the red +corpuscles--only one to 300--but they are larger, and contain nuclei. +When blood coagulates the white corpuscles sink more slowly and appear +as a lighter coloured layer on the top of the clot. + +Pus cells are very like colourless corpuscles, and the relation between +the two has been much debated. A pus cell can be distinguished from a +colourless blood cell only by its mode of origin. If it have an origin +external to the blood, it must be pus; if it originate in the blood, it +must be considered to be a blood cell. + +In the early stages of its development, a white blood corpuscle is seen +to modify by division; but in fully-developed blood such division is +never seen. It is probable that colourless white corpuscles are given to +the adult blood by the lymphatic glands. Every irritation of a part +which is freely connected with lymphatic glands increases the number of +colourless cells in the blood. Any excessive increase from this source I +have designated _leucocytosis_. + +In the first months of the embryo the red cell multiplies by division. +In adult life the mode of its multiplication is unknown. They, also, are +probably formed in the lymphatic glands and spleen. + +In a disease I have named _leukaemia_, the colourless blood cells +increase in number enormously. In such cases there is always disease of +the spleen, and very often of the lymphatic glands. + +These facts can hardly, I think, be interpreted in any other manner than +by supposing that the spleen and lymphatic glands are intimately +concerned in the production of the formed elements of the blood. + +By _pyaemia_ is meant pus corpuscles in the blood. But most cases of +so-called pyaemia are really cases in which there is an increase of white +blood corpuscles, and it is doubtful whether such a condition as pus in +the blood does ever occur. In the extremely rare cases, in which pus +breaks through into the veins, purulent ingredients may, without doubt, +be conveyed into the blood, but in such cases the introduction of pus +occurs for the most part but once, and there is no persistent pyaemia. +Even when clots in veins break down and form matter like pus, it will be +found that the matter is not really pus, and contains no pus cells. + +_Chlorosis_ is a condition in which there is a diminution of the +cellular elements of the blood, due probably to their deficient +formation in the spleen and lymphatic glands. + + +_The Vital Processes and Their Relation to Disease. Inflammation_ + +The study of the histology of the nervous system shows that in all parts +of the body a splitting up into a number of small centres takes place, +and that nowhere does a single central point susceptible of anatomical +demonstration exist from which the operations of the body are directed. +We find in the nervous systems definite little cells which serve as +centres of motion, but we do not find any single ganglion cell in which +alone all movement in the end originates. The most various individual +motor apparatuses are connected with the most various individual motor +ganglion cells. Sensations are certainly collected in definite ganglion +cells. Still, among them, too, we do not find any single ganglion cell +which can be in any way designated the centre of all sensation, but we +again meet with a great number of very minute centres. All the +operations which have their source in the nervous system, and there +certainly are a very great number of them, do not allow us to recognise +a unity anywhere else than in our own consciousness. An anatomical or +physiological unity has at least as yet been nowhere demonstrated. + +When we talk of life we mean vital activity. Now, every vital action +supposes an excitation or irritation. The irritability of the part is +the criterion by which we judge whether it be alive or not. Our notion +of the death of a part is based upon nothing more or less than +this--that we can no longer detect any irritability in it. If we now +proceed with our analysis of what is to be included in the notion of +excitability, we at once discover, that the different actions which can +be provoked by the influence of any external agency are essentially of +three kinds. The result of an excitation or irritation may, according to +circumstances, be either a merely functional process, or a more or less +increased nutrition of the part, _or_ a formative process giving rise to +a greater or less number of new elements. These differences manifest +themselves more or less distinctly according as the particular tissues +are more or less capable of responding to the one or other kinds of +excitation. It certainly cannot be denied that the processes may not be +distinctly defined, and that between the nutritive and formative +processes, and also between the functional and nutritive ones there are +transitional stages; still, when they are typically performed, there is +a very marked difference between them, and considerable differences in +the internal changes undergone by the excited parts. + +In inflammation all three irritative processes occur side by side. +Indeed, we may frequently see that when the organ itself is made up of +different parts, one part of the tissue undergoes functional or +nutritive, another formative, changes. If we consider what happens in a +muscle we see that a chemical or traumatic stimulus produces a +functional irritation of the primitive fasciculi, with contraction of +the muscle followed by nutritive changes. On the other hand, in the +interstitial connective tissue which binds the individual fasciculi of +the muscle together, real new formations are readily produced, commonly +pus. In this manner the three forms of irritation may be distinguished +in one part. + +The formative process is always preceded by nutritive enlargement due to +irritation of the part, and has no connection with irritation of the +nerves. Of course there may be also an irritation of the nerves, but +this, if we do not take function into account, has no causal connection +with the processes going on in the tissue proper, but is merely a +collateral effect of the original disturbance. + +Besides these active processes of function, nutrition, and new +formation, there occur passive processes. Passive processes are called +those changes in cells whereby they either lose a portion of their +substance, or are so completely destroyed, that a loss of substance, a +diminution of the sum total of the constituents of the body is produced. +To this class belong fatty degeneration of cells, affection of arteries, +calcification, and ossification of arteries, amyloid degeneration, and +so forth. + +It will now be necessary to consider inflammation at more length. The +theory of inflammation has passed through various stages. At first heat +was considered as its essential and dominant feature, then redness, +then exudative swelling; while the speculative neuropathologists +consider pain the _fons et origo_ of the condition. + +Personally, I believe that irritation must be taken as the +starting-point in the consideration of inflammation. We cannot conceive +of inflammation without an irritating stimulus, and the first question +is, what conception we are to form of such a stimulus. + +An inflammatory stimulus is a stimulus which acts either directly or +through the medium of the blood upon the composition and constitution of +a part in such a way as to enable it to attract to itself a larger +quantity of matter than usual and to transform it according to +circumstances. Every form of inflammation with which we are acquainted +may be explained in this way. It may be assumed that inflammation begins +from the moment that this increased absorption of matters into the +tissue takes place, and the further transformation of these matters +commences. + +It must be noticed that hyperaemia is not the essential feature of +inflammation, for inflammation occurs in non-vascular as well as in +vascular parts, and the inflammatory processes are practically the same +in both instances. + +Nor is inflammatory exudation the essential feature of inflammation. I +am of the opinion that there is no specific inflammatory exudation at +all, but that the exudation we meet with is composed essentially of the +material which has been generated in the inflamed part itself, through +the change in its condition, and of the transuded fluid derived from the +vessels. If, therefore, a part possess a great number of vessels, and +particularly if they are superficial, it will be able to furnish an +exudation, since the fluid which transudes from the blood conveys the +special product of the tissue along with it to the surface. If this is +not the case, there will be no exudation, but the whole process will be +limited to the occurrence in the real substance of the tissue of the +special changes which have been induced by the inflammatory stimulus. + +In this manner, two forms of inflammation can be distinguished, the +_purely parenchymatous inflammation_, where the process runs its course +in the interior of the tissue, without our being able to detect the +presence of any free fluid which has escaped from the blood; and the +secretory (exudative) inflammation, where an increased escape of fluid +takes place from the blood, and conveys the peculiar parenchymatous +matters along with it to the surface of the organs. That there are two +kinds of inflammation is shown by the fact that they occur for the most +part in different organs. Every parenchymatous inflammation tends to +alter the histological and functional character of an organ. Every +inflammation with free exudation generally affords a certain relief to +the parts by conveying away from it a great part of the noxious matters +with which it is clogged. + + +_New Formations_ + +I at present entirely reject the blastema doctrine in its original form, +and in its place I put the _doctrine of the continuous development of +tissues out of one another_. My first doubts of the blastema doctrine +date from my researches on tubercle. I found the tubercles never +exhibited a discernible exudation; but always organised elements +unpreceded by amorphous matter. I also found that the discharge from +scrofulous glands and from inflamed lymphatic glands is not an exudation +capable of organisation but merely debris, developed from the ordinary +cells of the glands. + +Until, however, the cellular nature of the body had been demonstrated, +it seemed necessary in some instances to postulate a blastema or +exudation to account for certain new formations. But the moment I could +show the universality of cells--the moment I could show that bone +corpuscles were real cells, and that connective tissues contained +cells--from that moment cellular material for the building of new +formations was apparent. In fact, the more observers increased the more +distinctly was it shown that by far the greater number of new formations +arise from the connective tissue. In almost all cases new formations may +be seen to be formed by a process of ordinary cell division from +previously existing cells. In some cases the cells continue to resemble +the parent cells; in other cases they become different. All new +formations built of cells which continue true to the parent type we may +call homologous new formations; while those which depart from the parent +type or undergo degenerative changes we may designate heterologous. In a +narrower sense of the word heterologous new formations are alone +destructive. The homologous ones may accidentally become very injurious, +but still they do not possess what can properly be called a destructive +or malignant character. On the other hand, every kind of heterologous +formation whenever it has not its seat in entirely superficial parts, +has a certain degree of malignity, and even superficial affections, +though entirely confined to the most external layers of epidermis, may +gradually exercise a very detrimental effect. Indeed, suppuration is of +this nature, for suppuration is simply a process of proliferation by +means of which cells are produced which do not acquire that degree of +consolidation or permanent connection with each other which is necessary +for the existence of the body. Pus is not the solvent of cells: but is +itself dissolved tissues. A part becomes soft and liquefies, while +suppurating, but it is not the pus which causes this softening; on the +contrary, it is the pus which is produced as the result of the +proliferation of tissues. + +A suppurative change of this nature takes place in all heterologous new +formations. The form of ulceration which is presented by cancer in its +latest stages bears so great a resemblance to suppurative ulceration +that the two things have long since been compared. The difference +between suppuration and suppuration lies in the differing duration of +the life of different cells. A cancer cell is capable of existing longer +than a pus corpuscle, and a cancerous tumour may last for months yet +still contain the whole of its elements intact. We are as yet able in +the case of very few elements to state with absolute certainty the +average length of their life. But among all pathological new formations +with fluid intercellular substance there is not a single one which is +able to preserve its existence for any length of time--not a single one +whose elements can become permanent constituents of the body, or exist +as long as the individual. The tumour as a whole may last; but its +individual elements perish. If we examine a tumour after it has existed +for perhaps a year, we usually find that the elements first formed no +longer exist in the centre; but that in the centre they are +disintegrating, dissolved by fatty changes. If a tumour be seated on a +surface, it often presents in the centre of its most prominent part a +navel-like depression, and the parts under this display a dense cicatrix +which no longer bears the original character of the new formation. +Heterologous new formations must be considered parasitical in their +nature, since every one of their elements will withdraw matters from the +body which might be used for better purposes, and since even its first +development implies the destruction of its parent structures. + +In view of origin of new formations it were well to create a +nomenclature showing their histological basis; but new names must not be +introduced too suddenly, and it must be noted that there are certain +tumours whose histological pedigree is still uncertain. + + +_Printed in the United States of America_ + +FOOTNOTES: + +[1] Azure transparent spheres conceived by the ancients to surround the +earth one within another, and to carry the heavenly bodies in their +revolutions. + +[2] Book I., Prop. i. The areas which revolving bodies describe by radii +drawn to an immovable centre of force do lie in the same immovable +planes and are proportional to the times in which they are described. + +Prop. ii. Every body that moves in any curve line described in a plane +and by a radius drawn to a point either immovable or moving forward with +a uniform rectilinear motion describes about that point areas +proportional to the times is urged by a centripetal force directed to +that point. + +Prop. iii. Every body that, by a radius drawn to another body, howsoever +moved, describes areas about that centre proportional to the times is +urged by a force compounded out of the centripetal force tending to that +other body and of all the accelerative force by which that other body is +impelled. + +[3] If the periodic times are in the sesquiplicate ratio of the radii, +and therefore the velocities reciprocally in the subduplicate ratio of +the radii, the centripetal forces will be in the duplicate ratio of the +radii inversely; and the converse. + +[4] _i.e._, showing convexity when in such a position as that, to an +observer on the earth, a line drawn between it and the sun would subtend +an angle of _90_ deg. or thereabouts. + + +TRANSCRIBER NOTE: + +Variant spelling and punctuation have been preserved. + + + + + +End of the Project Gutenberg EBook of The World's Greatest Books - Volume 15 +- Science, by Various + +*** END OF THIS PROJECT GUTENBERG EBOOK WORLD'S GREATEST BOOKS-VOLUME 15 *** + +***** This file should be named 25509.txt or 25509.zip ***** +This and all associated files of various formats will be found in: + https://www.gutenberg.org/2/5/5/0/25509/ + +Produced by Kevin Handy, John Hagerson, Greg Bergquist and +the Online Distributed Proofreading Team at +https://www.pgdp.net + + +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. 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