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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/6919-8.txt b/6919-8.txt new file mode 100644 index 0000000..49926f8 --- /dev/null +++ b/6919-8.txt @@ -0,0 +1,11082 @@ +The Project Gutenberg EBook of Darwiniana, by Thomas Henry Huxley + +Copyright laws are changing all over the world. Be sure to check the +copyright laws for your country before downloading or redistributing +this or any other Project Gutenberg eBook. + +This header should be the first thing seen when viewing this Project +Gutenberg file. Please do not remove it. Do not change or edit the +header without written permission. + +Please read the "legal small print," and other information about the +eBook and Project Gutenberg at the bottom of this file. Included is +important information about your specific rights and restrictions in +how the file may be used. You can also find out about how to make a +donation to Project Gutenberg, and how to get involved. + + +**Welcome To The World of Free Plain Vanilla Electronic Texts** + +**eBooks Readable By Both Humans and By Computers, Since 1971** + +*****These eBooks Were Prepared By Thousands of Volunteers!***** + + +Title: Darwiniana + +Author: Thomas Henry Huxley + +Release Date: November, 2004 [EBook #6919] +[This file was first posted on February 10, 2003] + +Edition: 10 + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THE PROJECT GUTENBERG EBOOK, DARWINIANA *** + + + + +Branko Collin, Carlo Traverso, Charles Franks and the Distributed +Proofreading Team. + +This file was produced from images generously made available by the +Bibliothèque nationale de France (BnF/Gallica) at http://gallica.bnf.fr. + + + + + +Thomas Henry Huxley + +Collected Essays + +(1893-1894) + +Vol. II + +Darwiniana + + +(Edition: published in 1893) + + + + +PREFACE + + +I have entitled this volume "Darwiniana" because the pieces republished in +it either treat of the ancient doctrine of Evolution, rehabilitated and +placed upon a sound scientific foundation, since and in consequence of, the +publication of the "Origin of Species;" or they attempt to meet the more +weighty of the unsparing criticisms with which that great work was visited +for several years after its appearance; or they record the impression left +by the personality of Mr. Darwin on one who had the privilege and the +happiness of enjoying his friendship for some thirty years; or they +endeavour to sum up his work and indicate its enduring influence on the +course of scientific thought. + +Those who take the trouble to read the first two essays, published in 1859 +and 1860, will, I think, do me the justice to admit that my zeal to secure +fair play for Mr. Darwin, did not drive me into the position of a mere +advocate; and that, while doing justice to the greatness of the argument I +did not fail to indicate its weak points. I have never seen any reason for +departing from the position which I took up in these two essays; and the +assertion which I sometimes meet with nowadays, that I have "recanted" or +changed my opinions about Mr. Darwin's views, is quite unintelligible to +me. + +As I have said in the seventh essay, the fact of evolution is to my mind +sufficiently evidenced by palaeontology; and I remain of the opinion +expressed in the second, that until selective breeding is definitely proved +to give rise to varieties infertile with one another, the logical +foundation of the theory of natural selection is incomplete. We still +remain very much in the dark about the causes of variation; the apparent +inheritance of acquired characters in some cases; and the struggle for +existence within the organism, which probably lies at the bottom of both of +these phenomena. + +Some apology is due to the reader for the reproduction of the "Lectures to +Working Men" in their original state. They were taken down in shorthand by +Mr. J. Aldous Mays, who requested me to allow him to print them. I was very +much pressed with work at the time; and, as I could not revise the reports, +which I imagined, moreover, would be of little or no interest to any but my +auditors, I stipulated that a notice should be prefixed to that effect. +This was done; but it did not prevent a considerable diffusion of the +little book in this country and in the United States, nor its translation +into more than one foreign language. Moreover Mr. Darwin often urged me to +revise and expand the lectures into a systematic popular exposition of the +topics of which they treat. I have more than once set about the task: but +the proverb about spoiling a horn and not making a spoon, is particularly +applicable to attempts to remodel a piece of work which may have served its +immediate purpose well enough. + +So I have reprinted the lectures as they stand, with all their +imperfections on their heads. It would seem that many people must have +found them useful thirty years ago; and, though the sixties appear now to +be reckoned by many of the rising generation as a part of the dark ages, I +am not without some grounds for suspecting that there yet remains a fair +sprinkling even of "philosophic thinkers" to whom it may be a profitable, +perhaps even a novel, task to descend from the heights of speculation and +go over the A B C of the great biological problem as it was set before a +body of shrewd artisans at that remote epoch. + +T. H. H. + +Hodeslea, Eastbourne, _April 7th_, 1893. + + + + +CONTENTS + + +I THE DARWINIAN HYPOTHESIS [1859] + +II THE ORIGIN OF SPECIES [1860] + +III CRITICISM ON "THE ORIGIN OF SPECIES" [1864] + +IV THE GENEALOGY OF ANIMALS [1869] + +V MR. DARWIN'S CRITICS [1871] + +VI EVOLUTION IN BIOLOGY [1878] + +VII THE COMING OF AGE OF "THE ORIGIN OF SPECIES" [1880] + +VIII CHARLES DARWIN [1882] + +IX THE DARWIN MEMORIAL [1885] + +X OBITUARY [1888] + +XI SIX LECTURES TO WORKING MEN "ON OUR KNOWLEDGE OF THE CAUSES OF THE + PHENOMENA OF ORGANIC NATURE" [1863] + + + + +I + +THE DARWINIAN HYPOTHESIS + +[1859] + + +The hypothesis of which the present work of Mr. Darwin is but the +preliminary outline, may be stated in his own language as follows:-- +"Species originated by means of natural selection, or through the +preservation of the favoured races in the struggle for life." To render +this thesis intelligible, it is necessary to interpret its terms. In the +first place, what is a species? The question is a simple one, but the right +answer to it is hard to find, even if we appeal to those who should know +most about it. It is all those animals or plants which have descended from +a single pair of parents; it is the smallest distinctly definable group of +living organisms; it is an eternal and immutable entity; it is a mere +abstraction of the human intellect having no existence in nature. Such are +a few of the significations attached to this simple word which may be +culled from authoritative sources; and if, leaving terms and theoretical +subtleties aside, we turn to facts and endeavour to gather a meaning for +ourselves, by studying the things to which, in practice, the name of +species is applied, it profits us little. For practice varies as much as +theory. Let two botanists or two zoologists examine and describe the +productions of a country, and one will pretty certainly disagree with the +other as to the number, limits, and definitions of the species into which +he groups the very same things. In these islands, we are in the habit of +regarding mankind as of one species, but a fortnight's steam will land us +in a country where divines and savants, for once in agreement, vie with one +another in loudness of assertion, if not in cogency of proof, that men are +of different species; and, more particularly, that the species negro is so +distinct from our own that the Ten Commandments have actually no reference +to him. Even in the calm region of entomology, where, if anywhere in this +sinful world, passion and prejudice should fail to stir the mind, one +learned coleopterist will fill ten attractive volumes with descriptions of +species of beetles, nine-tenths of which are immediately declared by his +brother beetle-mongers to be no species at all. + +The truth is that the number of distinguishable living creatures almost +surpasses imagination. At least 100,000 such kinds of insects alone have +been described and may be identified in collections, and the number of +separable kinds of living things is under-estimated at half a million. +Seeing that most of these obvious kinds have their accidental varieties, +and that they often shade into others by imperceptible degrees, it may well +be imagined that the task of distinguishing between what is permanent and +what fleeting, what is a species and what a mere variety, is sufficiently +formidable. + +But is it not possible to apply a test whereby a true species may be known +from a mere variety? Is there no criterion of species? Great authorities +affirm that there is--that the unions of members of the same species are +always fertile, while those of distinct species are either sterile, or +their offspring, called hybrids, are so. It is affirmed not only that this +is an experimental fact, but that it is a provision for the preservation of +the purity of species. Such a criterion as this would be invaluable; but, +unfortunately, not only is it not obvious how to apply it in the great +majority of cases in which its aid is needed, but its general validity is +stoutly denied. The Hon. and Rev. Mr. Herbert, a most trustworthy +authority, not only asserts as the result of his own observations and +experiments that many hybrids are quite as fertile as the parent species, +but he goes so far as to assert that the particular plant _Crinum +capense_ is much more fertile when crossed by a distinct species than +when fertilised by its proper pollen! On the other hand, the famous +Gaertner, though he took the greatest pains to cross the Primrose and the +Cowslip, succeeded only once or twice in several years; and yet it is a +well-established fact that the Primrose and the Cowslip are only varieties +of the same kind of plant. Again, such cases as the following are well +established. The female of species A, if crossed with the male of species +B, is fertile; but, if the female of B is crossed with the male of A, she +remains barren. Facts of this kind destroy the value of the supposed +criterion. + +If, weary of the endless difficulties involved in the determination of +species, the investigator, contenting himself with the rough practical +distinction of separable kinds, endeavours to study them as they occur in +nature--to ascertain their relations to the conditions which surround them, +their mutual harmonies and discordancies of structure, the bond of union of +their present and their past history, he finds himself, according to the +received notions, in a mighty maze, and with, at most, the dimmest +adumbration of a plan. If he starts with any one clear conviction, it is +that every part of a living creature is cunningly adapted to some special +use in its life. Has not his Paley told him that that seemingly useless +organ, the spleen, is beautifully adjusted as so much packing between the +other organs? And yet, at the outset of his studies, he finds that no +adaptive reason whatsoever can be given for one-half of the peculiarities +of vegetable structure. He also discovers rudimentary teeth, which are +never used, in the gums of the young calf and in those of the foetal whale; +insects which never bite have rudimental jaws, and others which never fly +have rudimental wings; naturally blind creatures have rudimental eyes; and +the halt have rudimentary limbs. So, again, no animal or plant puts on its +perfect form at once, but all have to start from the same point, however +various the course which each has to pursue. Not only men and horses, and +cats and dogs, lobsters and beetles, periwinkles and mussels, but even the +very sponges and animalcules commence their existence under forms which are +essentially undistinguishable; and this is true of all the infinite variety +of plants. Nay, more, all living beings march, side by side, along the high +road of development, and separate the later the more like they are; like +people leaving church, who all go down the aisle, but having reached the +door, some turn into the parsonage, others go down the village, and others +part only in the next parish. A man in his development runs for a little +while parallel with, though never passing through, the form of the meanest +worm, then travels for a space beside the fish, then journeys along with +the bird and the reptile for his fellow travellers: and only at last, after +a brief companionship with the highest of the four-footed and four-handed +world, rises into the dignity of pure manhood. No competent thinker of the +present day dreams of explaining these indubitable facts by the notion of +the existence of unknown and undiscoverable adaptations to purpose. And we +would remind those who, ignorant of the facts, must be moved by authority, +that no one has asserted the incompetence of the doctrine of final causes, +in its application to physiology and anatomy, more strongly than our own +eminent anatomist, Professor Owen, who, speaking of such cases, says ("On +the Nature of Limbs," pp. 39, 40)--"I think it will be obvious that the +principle of final adaptations fails to satisfy all the conditions of the +problem." + +But, if the doctrine of final causes will not help us to comprehend +the anomalies of living structure, the principle of adaptation must +surely lead us to understand why certain living beings are found in +certain regions of the world and not in others. The Palm, as we know, +will not grow in our climate, nor the Oak in Greenland. The white bear +cannot live where the tiger thrives, nor _vice versâ_, and the more +the natural habits of animal and vegetable species are examined, the +more do they seem, on the whole, limited to particular provinces. But +when we look into the facts established by the study of the +geographical distribution of animals and plants it seems utterly +hopeless to attempt to understand the strange and apparently +capricious relations which they exhibit. One would be inclined to +suppose _à priori_ that every country must be naturally peopled by +those animals that are fittest to live and thrive in it. And yet how, +on this hypothesis, are we to account for the absence of cattle in the +Pampas of South America, when those parts of the New World were +discovered? It is not that they were unfit for cattle, for millions of +cattle now run wild there; and the like holds good of Australia and +New Zealand. It is a curious circumstance, in fact, that the animals +and plants of the Northern Hemisphere are not only as well adapted to +live in the Southern Hemisphere as its own autochthones, but are, in +many cases, absolutely better adapted, and so overrun and extirpate +the aborigines. Clearly, therefore, the species which naturally +inhabit a country are not necessarily the best adapted to its climate +and other conditions. The inhabitants of islands are often distinct +from any other known species of animal or plants (witness our recent +examples from the work of Sir Emerson Tennent, on Ceylon), and yet +they have almost always a sort of general family resemblance to the +animals and plants of the nearest mainland. On the other hand, there +is hardly a species of fish, shell, or crab common to the opposite +sides of the narrow isthmus of Panama. [Footnote: See page 60 +_Note_.] Wherever we look, then, living nature offers us riddles of +difficult solution, if we suppose that what we see is all that can be +known of it. + +But our knowledge of life is not confined to the existing world. Whatever +their minor differences, geologists are agreed as to the vast thickness of +the accumulated strata which compose the visible part of our earth, and the +inconceivable immensity of the time the lapse of which they are the +imperfect but the only accessible witnesses. Now, throughout the greater +part of this long series of stratified rocks are scattered, sometimes very +abundantly, multitudes of organic remains, the fossilised exuviæ of animals +and plants which lived and died while the mud of which the rocks are formed +was yet soft ooze, and could receive and bury them. It would be a great +error to suppose that these organic remains were fragmentary relics. Our +museums exhibit fossil shells of immeasurable antiquity, as perfect as the +day they were formed; whole skeletons without a limb disturbed; nay, the +changed flesh, the developing embryos, and even the very footsteps of +primæval organisms. Thus the naturalist finds in the bowels of the earth +species as well defined as, and in some groups of animals more numerous +than, those which breathe the upper air. But, singularly enough, the +majority of these entombed species are wholly distinct from those that now +live. Nor is this unlikeness without its rule and order. As a broad fact, +the further we go back in time the less the buried species are like +existing forms; and, the further apart the sets of extinct creatures are, +the less they are like one another. In other words, there has been a +regular succession of living beings, each younger set, being in a very +broad and general sense, somewhat more like those which now live. + +It was once supposed that this succession had been the result of vast +successive catastrophes, destructions, and re-creations _en masse_; +but catastrophes are now almost eliminated from geological, or at least +palæontological speculation; and it is admitted, on all hands, that the +seeming breaks in the chain of being are not absolute, but only relative to +our imperfect knowledge; that species have replaced species, not in +assemblages, but one by one; and that, if it were possible to have all the +phenomena of the past presented to us, the convenient epochs and formations +of the geologist, though having a certain distinctness, would fade into one +another with limits as undefinable as those of the distinct and yet +separable colours of the solar spectrum. + +Such is a brief summary of the main truths which have been established +concerning species. Are these truths ultimate and irresolvable facts, or +are their complexities and perplexities the mere expressions of a higher +law? + +A large number of persons practically assume the former position to be +correct. They believe that the writer of the Pentateuch was empowered and +commissioned to teach us scientific as well as other truth, that the +account we find there of the creation of living things is simply and +literally correct, and that anything which seems to contradict it is, by +the nature of the case, false. All the phenomena which have been detailed +are, on this view, the immediate product of a creative fiat and, +consequently, are out of the domain of science altogether. + +Whether this view prove ultimately to be true or false, it is, at any rate, +not at present supported by what is commonly regarded as logical proof, +even if it be capable of discussion by reason; and hence we consider +ourselves at liberty to pass it by, and to turn to those views which +profess to rest on a scientific basis only, and therefore admit of being +argued to their consequences. And we do this with the less hesitation as it +so happens that those persons who are practically conversant with the facts +of the case (plainly a considerable advantage) have always thought fit to +range themselves under the latter category. + +The majority of these competent persons have up to the present time +maintained two positions--the first, that every species is, within certain +defined limits, fixed and incapable of modification; the second, that every +species was originally produced by a distinct creative act. The second +position is obviously incapable of proof or disproof, the direct operations +of the Creator not being subjects of science; and it must therefore be +regarded as a corollary from the first, the truth or falsehood of which is +a matter of evidence. Most persons imagine that the arguments in favour of +it are overwhelming; but to some few minds, and these, it must be +confessed, intellects of no small power and grasp of knowledge, they have +not brought conviction. Among these minds, that of the famous naturalist +Lamarck, who possessed a greater acquaintance with the lower forms of life +than any man of his day, Cuvier not excepted, and was a good botanist to +boot, occupies a prominent place. + +Two facts appear to have strongly affected the course of thought of this +remarkable man--the one, that finer or stronger links of affinity connect +all living beings with one another, and that thus the highest creature +grades by multitudinous steps into the lowest; the other, that an organ may +be developed in particular directions by exerting itself in particular +ways, and that modifications once induced may be transmitted and become +hereditary. Putting these facts together, Lamarck endeavoured to account +for the first by the operation of the second. Place an animal in new +circumstances, says he, and its needs will be altered; the new needs will +create new desires, and the attempt to gratify such desires will result in +an appropriate modification of the organs exerted. Make a man a blacksmith, +and his brachial muscles will develop in accordance with the demands made +upon them, and in like manner, says Lamarck, "the efforts of some +short-necked bird to catch fish without wetting himself have, with time and +perseverance, given rise to all our herons and long-necked waders." + +The Lamarckian hypothesis has long since been justly condemned, and it is +the established practice for every tyro to raise his heel against the +carcase of the dead lion. But it is rarely either wise or instructive to +treat even the errors of a really great man with mere ridicule, and in the +present case the logical form of the doctrine stands on a very different +footing from its substance. + +If species have really arisen by the operation of natural conditions, we +ought to be able to find those conditions now at work; we ought to be able +to discover in nature some power adequate to modify any given kind of +animal or plant in such a manner as to give rise to another kind, which +would be admitted by naturalists as a distinct species. Lamarck imagined +that he had discovered this _vera causa_ in the admitted facts that +some organs may be modified by exercise; and that modifications, once +produced, are capable of hereditary transmission. It does not seem to have +occurred to him to inquire whether there is any reason to believe that +there are any limits to the amount of modification producible, or to ask +how long an animal is likely to endeavour to gratify an impossible desire. +The bird, in our example, would surely have renounced fish dinners long +before it had produced the least effect on leg or neck. + +Since Lamarck's time, almost all competent naturalists have left +speculations on the origin of species to such dreamers as the author of the +"Vestiges," by whose well-intentioned efforts the Lamarckian theory +received its final condemnation in the minds of all sound thinkers. +Notwithstanding this silence, however, the transmutation theory, as it has +been called, has been a "skeleton in the closet" to many an honest +zoologist and botanist who had a soul above the mere naming of dried plants +and skins. Surely, has such an one thought, nature is a mighty and +consistent whole, and the providential order established in the world of +life must, if we could only see it rightly, be consistent with that +dominant over the multiform shapes of brute matter. But what is the history +of astronomy, of all the branches of physics, of chemistry, of medicine, +but a narration of the steps by which the human mind has been compelled, +often sorely against its will, to recognise the operation of secondary +causes in events where ignorance beheld an immediate intervention of a +higher power? And when we know that living things are formed of the same +elements as the inorganic world, that they act and react upon it, bound by +a thousand ties of natural piety, is it probable, nay is it possible, that +they, and they alone, should have no order in their seeming disorder, no +unity in their seeming multiplicity, should suffer no explanation by the +discovery of some central and sublime law of mutual connection? + +Questions of this kind have assuredly often arisen, but it might have been +long before they received such expression as would have commanded the +respect and attention of the scientific world, had it not been for the +publication of the work which prompted this article. Its author, Mr. +Darwin, inheritor of a once celebrated name, won his spurs in science when +most of those now distinguished were young men, and has for the last twenty +years held a place in the front ranks of British philosophers. After a +circumnavigatory voyage, undertaken solely for the love of his science, Mr. +Darwin published a series of researches which at once arrested the +attention of naturalists and geologists; his generalisations have since +received ample confirmation and now command universal assent, nor is it +questionable that they have had the most important influence on the +progress of science. More recently Mr. Darwin, with a versatility which is +among the rarest of gifts, turned his attention to a most difficult +question of zoology and minute anatomy; and no living naturalist and +anatomist has published a better monograph than that which resulted from +his labours. Such a man, at all events, has not entered the sanctuary with +unwashed hands, and when he lays before us the results of twenty years' +investigation and reflection we must listen even though we be disposed to +strike. But, in reading his work, it must be confessed that the attention +which might at first be dutifully, soon becomes willingly, given, so clear +is the author's thought, so outspoken his conviction, so honest and fair +the candid expression of his doubts. Those who would judge the book must +read it: we shall endeavour only to make its line of argument and its +philosophical position intelligible to the general reader in our own way. + +The Baker Street Bazaar has just been exhibiting its familiar annual +spectacle. Straight-backed, small-headed, big-barrelled oxen, as dissimilar +from any wild species as can well be imagined, contended for attention and +praise with sheep of half-a-dozen different breeds and styes of bloated +preposterous pigs, no more like a wild boar or sow than a city alderman is +like an ourang-outang. The cattle show has been, and perhaps may again be, +succeeded by a poultry show, of whose crowing and clucking prodigies it can +only be certainly predicated that they will be very unlike the aboriginal +_Phasianus gallus._ If the seeker after animal anomalies is not +satisfied, a turn or two in Seven Dials will convince him that the breeds +of pigeons are quite as extraordinary and unlike one another and their +parent stock, while the Horticultural Society will provide him with any +number of corresponding vegetable aberrations from nature's types. He will +learn with no little surprise, too, in the course of his travels, that the +proprietors and producers of these animal and vegetable anomalies regard +them as distinct species, with a firm belief, the strength of which is +exactly proportioned to their ignorance of scientific biology, and which is +the more remarkable as they are all proud of their skill in originating +such "species." + +On careful inquiry it is found that all these, and the many other +artificial breeds or races of animals and plants, have been produced by one +method. The breeder--and a skilful one must be a person of much sagacity +and natural or acquired perceptive faculty--notes some slight difference, +arising he knows not how, in some individuals of his stock. If he wish to +perpetuate the difference, to form a breed with the peculiarity in question +strongly marked, he selects such male and female individuals as exhibit the +desired character, and breeds from them. Their offspring are then carefully +examined, and those which exhibit the peculiarity the most distinctly are +selected for breeding; and this operation is repeated until the desired +amount of divergence from the primitive stock is reached. It is then found +that by continuing the process of selection--always breeding, that is, from +well-marked forms, and allowing no impure crosses to interfere--a race may +be formed, the tendency of which to reproduce itself is exceedingly strong; +nor is the limit to the amount of divergence which may be thus produced +known; but one thing is certain, that, if certain breeds of dogs, or of +pigeons, or of horses, were known only in a fossil state, no naturalist +would hesitate in regarding them as distinct species. + +But in all these cases we have human interference. Without the breeder +there would be no selection, and without the selection no race. Before +admitting the possibility of natural species having originated in any +similar way, it must be proved that there is in Nature some power which +takes the place of man, and performs a selection _suâ sponte._ It is +the claim of Mr. Darwin that he professes to have discovered the existence +and the _modus operandi_ of this "natural selection," as he terms it; +and, if he be right, the process is perfectly simple and comprehensible, +and irresistibly deducible from very familiar but well nigh forgotten +facts. + +Who, for instance, has duly reflected upon all the consequences of the +marvellous struggle for existence which is daily and hourly going on among +living beings? Not only does every animal live at the expense of some other +animal or plant, but the very plants are at war. The ground is full of +seeds that cannot rise into seedlings; the seedlings rob one another of +air, light and water, the strongest robber winning the day, and +extinguishing his competitors. Year after year, the wild animals with which +man never interferes are, on the average, neither more nor less numerous +than they were; and yet we know that the annual produce of every pair is +from one to perhaps a million young; so that it is mathematically certain +that, on the average, as many are killed by natural causes as are born +every year, and those only escape which happen to be a little better fitted +to resist destruction than those which die. The individuals of a species +are like the crew of a foundered ship, and none but good swimmers have a +chance of reaching the land. + +Such being unquestionably the necessary conditions under which living +creatures exist, Mr. Darwin discovers in them the instrument of natural +selection. Suppose that in the midst of this incessant competition some +individuals of a species (A) present accidental variations which happen to +fit them a little better than their fellows for the struggle in which they +are engaged, then the chances are in favour, not only of these individuals +being better nourished than the others, but of their predominating over +their fellows in other ways, and of having a better chance of leaving +offspring, which will of course tend to reproduce the peculiarities of +their parents. Their offspring will, by a parity of reasoning, tend to +predominate over their contemporaries, and there being (suppose) no room +for more than one species such as A, the weaker variety will eventually be +destroyed by the new destructive influence which is thrown into the scale, +and the stronger will take its place. Surrounding conditions remaining +unchanged, the new variety (which we may call B)--supposed, for argument's +sake, to be the best adapted for these conditions which can be got out of +the original stock--will remain unchanged, all accidental deviations from +the type becoming at once extinguished, as less fit for their post than B +itself. The tendency of B to persist will grow with its persistence through +successive generations, and it will acquire all the characters of a new +species. + +But, on the other hand, if the conditions of life change in any degree, +however slight, B may no longer be that form which is best adapted to +withstand their destructive, and profit by their sustaining, influence; in +which case if it should give rise to a more competent variety (C), this +will take its place and become a new species; and thus, by natural +selection, the species B and C will be successively derived from A. + +That this most ingenious hypothesis enables us to give a reason for many +apparent anomalies in the distribution of living beings in time and space, +and that it is not contradicted by the main phenomena of life and +organisation appear to us to be unquestionable; and, so far, it must be +admitted to have an immense advantage over any of its predecessors. But it +is quite another matter to affirm absolutely either the truth or falsehood +of Mr. Darwin's views at the present stage of the inquiry. Goethe has an +excellent aphorism defining that state of mind which he calls "Thätige +Skepsis"--active doubt. It is doubt which so loves truth that it neither +dares rest in doubting, nor extinguish itself by unjustified belief; and we +commend this state of mind to students of species, with respect to Mr. +Darwin's or any other hypothesis, as to their origin. The combined +investigations of another twenty years may, perhaps, enable naturalists to +say whether the modifying causes and the selective power, which Mr. Darwin +has satisfactorily shown to exist in Nature, are competent to produce all +the effects he ascribes to them; or whether, on the other hand, he has been +led to over-estimate the value of the principle of natural selection, as +greatly as Lamarck over-estimated his _vera causa_ of modification by +exercise. + +But there is, at all events, one advantage possessed by the more recent +writer over his predecessor. Mr. Darwin abhors mere speculation as nature +abhors a vacuum. He is as greedy of cases and precedents as any +constitutional lawyer, and all the principles he lays down are capable of +being brought to the test of observation and experiment. The path he bids +us follow professes to be, not a mere airy track, fabricated of ideal +cobwebs, but a solid and broad bridge of facts. If it be so, it will carry +us safely over many a chasm in our knowledge, and lead us to a region free +from the snares of those fascinating but barren virgins, the Final Causes, +against whom a high authority has so justly warned us. "My sons, dig in the +vineyard," were the last words of the old man in the fable: and, though the +sons found no treasure, they made their fortunes by the grapes. + + + + +II + +THE ORIGIN OF SPECIES + +[1860] + + +Mr. Darwin's long-standing and well-earned scientific eminence probably +renders him indifferent to that social notoriety which passes by the name +of success; but if the calm spirit of the philosopher have not yet wholly +superseded the ambition and the vanity of the carnal man within him, he +must be well satisfied with the results of his venture in publishing the +"Origin of Species." Overflowing the narrow bounds of purely scientific +circles, the "species question" divides with Italy and the Volunteers the +attention of general society. Everybody has read Mr. Darwin's book, or, at +least, has given an opinion upon its merits or demerits; pietists, whether +lay or ecclesiastic, decry it with the mild railing which sounds so +charitable; bigots denounce it with ignorant invective; old ladies of both +sexes consider it a decidedly dangerous book, and even savants, who have no +better mud to throw, quote antiquated writers to show that its author is no +better than an ape himself; while every philosophical thinker hails it as a +veritable Whitworth gun in the armoury of liberalism; and all competent +naturalists and physiologists, whatever their opinions as to the ultimate +fate of the doctrines put forth, acknowledge that the work in which they +are embodied is a solid contribution to knowledge and inaugurates a new +epoch in natural history. + +Nor has the discussion of the subject been restrained within the limits of +conversation. When the public is eager and interested, reviewers must +minister to its wants; and the genuine _littérateur_ is too much in +the habit of acquiring his knowledge from the book he judges--as the +Abyssinian is said to provide himself with steaks from the ox which carries +him--to be withheld from criticism of a profound scientific work by the +mere want of the requisite preliminary scientific acquirement; while, on +the other hand, the men of science who wish well to the new views, no less +than those who dispute their validity, have naturally sought opportunities +of expressing their opinions. Hence it is not surprising that almost all +the critical journals have noticed Mr. Darwin's work at greater or less +length; and so many disquisitions, of every degree of excellence, from the +poor product of ignorance, too often stimulated by prejudice, to the fair +and thoughtful essay of the candid student of Nature, have appeared, that +it seems an almost hopeless task to attempt to say anything new upon the +question. + +But it may be doubted if the knowledge and acumen of prejudged scientific +opponents, and the subtlety of orthodox special pleaders, have yet exerted +their full force in mystifying the real issues of the great controversy +which has been set afoot, and whose end is hardly likely to be seen by this +generation; so that, at this eleventh hour, and even failing anything new, +it may be useful to state afresh that which is true, and to put the +fundamental positions advocated by Mr. Darwin in such a form that they may +be grasped by those whose special studies lie in other directions. And the +adoption of this course may be the more advisable, because, notwithstanding +its great deserts, and indeed partly on account of them, the "Origin of +Species" is by no means an easy book to read--if by reading is implied the +full comprehension of an author's meaning. + +We do not speak jestingly in saying that it is Mr. Darwin's misfortune to +know more about the question he has taken up than any man living. +Personally and practically exercised in zoology, in minute anatomy, in +geology; a student of geographical distribution, not on maps and in museums +only, but by long voyages and laborious collection; having largely advanced +each of these branches of science, and having spent many years in gathering +and sifting materials for his present work, the store of accurately +registered facts upon which the author of the "Origin of Species" is able +to draw at will is prodigious. + +But this very superabundance of matter must have been embarrassing to a +writer who, for the present, can only put forward an abstract of his views; +and thence it arises, perhaps, that notwithstanding the clearness of the +style, those who attempt fairly to digest the book find much of it a sort +of intellectual pemmican--a mass of facts crushed and pounded into shape, +rather than held together by the ordinary medium of an obvious logical +bond; due attention will, without doubt, discover this bond, but it is +often hard to find. + +Again, from sheer want of room, much has to be taken for granted which +might readily enough be proved; and hence, while the adept, who can supply +the missing links in the evidence from his own knowledge, discovers fresh +proof of the singular thoroughness with which all difficulties have been +considered and all unjustifiable suppositions avoided, at every reperusal +of Mr. Darwin's pregnant paragraphs, the novice in biology is apt to +complain of the frequency of what he fancies is gratuitous assumption. + +Thus while it may be doubted if, for some years, any one is likely to be +competent to pronounce judgment on all the issues raised by Mr. Darwin, +there is assuredly abundant room for him, who, assuming the humbler, though +perhaps as useful, office of an interpreter between the "Origin of Species" +and the public, contents himself with endeavouring to point out the nature +of the problems which it discusses; to distinguish between the ascertained +facts and the theoretical views which it contains; and finally, to show the +extent to which the explanation it offers satisfies the requirements of +scientific logic. At any rate, it is this office which we purpose to +undertake in the following pages. + +It may be safely assumed that our readers have a general conception of the +nature of the objects to which the word "species" is applied; but it has, +perhaps, occurred to a few, even to those who are naturalists _ex +professo_, to reflect, that, as commonly employed, the term has a double +sense and denotes two very different orders of relations. When we call a +group of animals, or of plants, a species, we may imply thereby, either +that all these animals or plants have some common peculiarity of form or +structure; or, we may mean that they possess some common functional +character. That part of biological science which deals with form and +structure is called Morphology--that which concerns itself with function, +Physiology--so that we may conveniently speak of these two senses, or +aspects, of "species"--the one as morphological, the other as +physiological. Regarded from the former point of view, a species is nothing +more than a kind of animal or plant, which is distinctly definable from all +others, by certain constant, and not merely sexual, morphological +peculiarities. Thus horses form a species, because the group of animals to +which that name is applied is distinguished from all others in the world by +the following constantly associated characters. They have--1, A vertebral +column; 2, Mammae; 3, A placental embryo; 4, Four legs; 5, A single +well-developed toe in each foot provided with a hoof; 6, A bushy tail; and +7, Callosities on the inner sides of both the fore and the hind legs. The +asses, again, form a distinct species, because, with the same characters, +as far as the fifth in the above list, all asses have tufted tails, and +have callosities only on the inner side of the fore-legs. If animals were +discovered having the general characters of the horse, but sometimes with +callosities only on the fore-legs, and more or less tufted tails; or +animals having the general characters of the ass, but with more or less +bushy tails, and sometimes with callosities on both pairs of legs, besides +being intermediate in other respects--the two species would have to be +merged into one. They could no longer be regarded as morphologically +distinct species, for they would not be distinctly definable one from the +other. + +However bare and simple this definition of species may appear to be, we +confidently appeal to all practical naturalists, whether zoologists, +botanists, or palaeontologists, to say if, in the vast majority of cases, +they know, or mean to affirm, anything more of the group of animals or +plants they so denominate than what has just been stated. Even the most +decided advocates of the received doctrines respecting species admit this. + +"I apprehend," says Professor Owen, [Footnote: "On the Osteology of the +Chimpanzees and Orangs"; _Transactions of the Zoological Society_, +1858.] "that few naturalists nowadays, in describing and proposing a name +for what they call 'a new _species_,' use that term to signify what +was meant by it twenty or thirty years ago; that is, an originally distinct +creation, maintaining its primitive distinction by obstructive generative +peculiarities. The proposer of the new species now intends to state no more +than he actually knows; as, for example, that the differences on which he +founds the specific character are constant in individuals of both sexes, so +far as observation has reached; and that they are not due to domestication +or to artificially superinduced external circumstances, or to any outward +influence within his cognizance; that the species is wild, or is such as it +appears by Nature." + +If we consider, in fact, that by far the largest proportion of recorded +existing species are known only by the study of their skins, or bones, or +other lifeless exuviae; that we are acquainted with none, or next to none, +of their physiological peculiarities, beyond those which can be deduced +from their structure, or are open to cursory observation; and that we +cannot hope to learn more of any of those extinct forms of life which now +constitute no inconsiderable proportion of the known Flora and Fauna of the +world: it is obvious that the definitions of these species can be only of a +purely structural, or morphological, character. It is probable that +naturalists would have avoided much confusion of ideas if they had more +frequently borne the necessary limitations of our knowledge in mind. But +while it may safely be admitted that we are acquainted with only the +morphological characters of the vast majority of species--the functional or +physiological, peculiarities of a few have been carefully investigated, and +the result of that study forms a large and most interesting portion of the +physiology of reproduction. + +The student of Nature wonders the more and is astonished the less, the more +conversant he becomes with her operations; but of all the perennial +miracles she offers to his inspection, perhaps the most worthy of +admiration is the development of a plant or of an animal from its embryo. +Examine the recently laid egg of some common animal, such as a salamander +or newt. It is a minute spheroid in which the best microscope will reveal +nothing but a structureless sac, enclosing a glairy fluid, holding granules +in suspension. [Footnote: When this sentence was written, it was generally +believed that the original nucleus of the egg (the germinal vesicle) +disappeared. 1893.] But strange possibilities lie dormant in that +semi-fluid globule. Let a moderate supply of warmth reach its watery +cradle, and the plastic matter undergoes changes so rapid, yet so steady +and purposelike in their succession, that one can only compare them to +those operated by a skilled modeller upon a formless lump of clay. As with +an invisible trowel, the mass is divided and subdivided into smaller and +smaller portions, until it is reduced to an aggregation of granules not too +large to build withal the finest fabrics of the nascent organism. And, +then, it is as if a delicate finger traced out the line to be occupied by +the spinal column, and moulded the contour of the body; pinching up the +head at one end, the tail at the other, and fashioning flank and limb into +due salamandrine proportions, in so artistic a way, that, after watching +the process hour by hour, one is almost involuntarily possessed by the +notion, that some more subtle aid to vision than an achromatic, would show +the hidden artist, with his plan before him, striving with skilful +manipulation to perfect his work. + +As life advances, and the young amphibian ranges the waters, the terror of +his insect contemporaries, not only are the nutritious particles supplied +by its prey, by the addition of which to its frame, growth takes place, +laid down, each in its proper spot, and in such due proportion to the rest, +as to reproduce the form, the colour, and the size, characteristic of the +parental stock; but even the wonderful powers of reproducing lost parts +possessed by these animals are controlled by the same governing tendency. +Cut off the legs, the tail, the jaws, separately or all together, and, as +Spallanzani showed long ago, these parts not only grow again, but the +redintegrated limb is formed on the same type as those which were lost. The +new jaw, or leg, is a newt's, and never by any accident more like that of a +frog. What is true of the newt is true of every animal and of every plant; +the acorn tends to build itself up again into a woodland giant such as that +from whose twig it fell; the spore of the humblest lichen reproduces the +green or brown incrustation which gave it birth; and at the other end of +the scale of life, the child that resembled neither the paternal nor the +maternal side of the house would be regarded as a kind of monster. + +So that the one end to which, in all living beings, the formative impulse +is tending--the one scheme which the Archæus of the old speculators strives +to carry out, seems to be to mould the offspring into the likeness of the +parent. It is the first great law of reproduction, that the offspring tends +to resemble its parent or parents, more closely than anything else. + +Science will some day show us how this law is a necessary consequence of +the more general laws which govern matter; but, for the present, more can +hardly be said than that it appears to be in harmony with them. We know +that the phænomena of vitality are not something apart from other physical +phænomena, but one with them; and matter and force are the two names of the +one artist who fashions the living as well as the lifeless. Hence living +bodies should obey the same great laws as other matter--nor, throughout +Nature, is there a law of wider application than this, that a body impelled +by two forces takes the direction of their resultant. But living bodies may +be regarded as nothing but extremely complex bundles of forces held in a +mass of matter, as the complex forces of a magnet are held in the steel by +its coercive force; and, since the differences of sex are comparatively +slight, or, in other words, the sum of the forces in each has a very +similar tendency, their resultant, the offspring, may reasonably be +expected to deviate but little from a course parallel to either, or to +both. + +Represent the reason of the law to ourselves by what physical metaphor or +analogy we will, however, the great matter is to apprehend its existence +and the importance of the consequences deducible from it. For things which +are like to the same are like to one another; and if, in a great series of +generations, every offspring is like its parent, it follows that all the +offspring and all the parents must be like one another; and that, given an +original parental stock, with the opportunity of undisturbed +multiplication, the law in question necessitates the production, in course +of time, of an indefinitely large group, the whole of the members of which +are at once very similar and are blood relations, having descended from the +same parent, or pair of parents. The proof that all the members of any +given group of animals, or plants, had thus descended, would be ordinarily +considered sufficient to entitle them to the rank of physiological species, +for most physiologists consider species to be definable as "the offspring +of a single primitive stock." + +But though it is quite true that all those groups we call species +_may_, according to the known laws of reproduction, have descended +from a single stock, and though it is very likely they really have done so, +yet this conclusion rests on deduction and can hardly hope to establish +itself upon a basis of observation. And the primitiveness of the supposed +single stock, which, after all, is the essential part of the matter, is not +only a hypothesis, but one which has not a shadow of foundation, if by +"primitive" be meant "independent of any other living being." A scientific +definition, of which an unwarrantable hypothesis forms an essential part, +carries its condemnation within itself; but, even supposing such a +definition were, in form, tenable, the physiologist who should attempt to +apply it in Nature would soon find himself involved in great, if not +inextricable, difficulties. As we have said, it is indubitable that +offspring _tend_ to resemble the parental organism, but it is equally +true that the similarity attained never amounts to identity either in form +or in structure. There is always a certain amount of deviation, not only +from the precise characters of a single parent, but when, as in most +animals and many plants, the sexes are lodged in distinct individuals, from +an exact mean between the two parents. And indeed, on general principles, +this slight deviation seems as intelligible as the general similarity, if +we reflect how complex the co-operating "bundles of forces" are, and how +improbable it is that, in any case, their true resultant shall coincide +with any mean between the more obvious characters of the two parents. +Whatever be its cause, however, the co-existence of this tendency to minor +variation with the tendency to general similarity, is of vast importance in +its bearing on the question of the origin of species. + +As a general rule, the extent to which an offspring differs from its parent +is slight enough; but, occasionally, the amount of difference is much more +strongly marked, and then the divergent offspring receives the name of a +Variety. Multitudes, of what there is every reason to believe are such +varieties, are known, but the origin of very few has been accurately +recorded, and of these we will select two as more especially illustrative +of the main features of variation. The first of them is that of the "Ancon" +or "Otter" sheep, of which a careful account is given by Colonel David +Humphreys, F.R.S., in a letter to Sir Joseph Banks, published in the +"Philosophical Transactions" for 1813. It appears that one Seth Wright, the +proprietor of a farm on the banks of the Charles River, in Massachusetts, +possessed a flock of fifteen ewes and a ram of the ordinary kind. In the +year 1791, one of the ewes presented her owner with a male lamb, differing, +for no assignable reason, from its parents by a proportionally long body +and short bandy legs, whence it was unable to emulate its relatives in +those sportive leaps over the neighbours' fences, in which they were in the +habit of indulging, much to the good farmer's vexation. + +The second case is that detailed by a no less unexceptionable authority +than Réaumur, in his "Art de faire éclore les Poulets." A Maltese couple, +named Kelleia, whose hands and feet were constructed upon the ordinary +human model, had born to them a son, Gratio, who possessed six perfectly +movable fingers on each hand, and six toes, not quite so well formed, on +each foot. No cause could be assigned for the appearance of this unusual +variety of the human species. + +Two circumstances are well worthy of remark in both these cases. In each, +the variety appears to have arisen in full force, and, as it were, _per +saltum_; a wide and definite difference appearing, at once, between the +Ancon ram and the ordinary sheep; between the six-fingered and six-toed +Gratio Kelleia and ordinary men. In neither case is it possible to point +out any obvious reason for the appearance of the variety. Doubtless there +were determining causes for these as for all other phenomena; but they do +not appear, and we can be tolerably certain that what are ordinarily +understood as changes in physical conditions, as in climate, in food, or +the like, did not take place and had nothing to do with the matter. It was +no case of what is commonly called adaptation to circumstances; but, to use +a conveniently erroneous phrase, the variations arose spontaneously. The +fruitless search after final causes leads their pursuers a long way; but +even those hardy teleologists, who are ready to break through all the laws +of physics in chase of their favourite will-o'-the-wisp, may be puzzled to +discover what purpose could be attained by the stunted legs of Seth +Wright's ram or the hexadactyle members of Gratio Kelleia. + +Varieties then arise we know not why; and it is more than probable that the +majority of varieties have arisen in this "spontaneous" manner, though we +are, of course, far from denying that they may be traced, in some cases, to +distinct external influences; which are assuredly competent to alter the +character of the tegumentary covering, to change colour, to increase or +diminish the size of muscles, to modify constitution, and, among plants, to +give rise to the metamorphosis of stamens into petals, and so forth. But +however they may have arisen, what especially interests us at present is, +to remark that, once in existence, many varieties obey the fundamental law +of reproduction that like tends to produce like; and their offspring +exemplify it by tending to exhibit the same deviation from the parental +stock as themselves. Indeed, there seems to be, in many instances, a +prepotent influence about a newly-arisen variety which gives it what one +may call an unfair advantage over the normal descendants from the same +stock. This is strikingly exemplified by the case of Gratio Kelleia, who +married a woman with the ordinary pentadactyle extremities, and had by her +four children, Salvator, George, André, and Marie. Of these children +Salvator, the eldest boy, had six fingers and six toes, like his father; +the second and third, also boys, had five fingers and five toes, like their +mother, though the hands and feet of George were slightly deformed. The +last, a girl, had five fingers and five toes, but the thumbs were slightly +deformed. The variety thus reproduced itself purely in the eldest, while +the normal type reproduced itself purely in the third, and almost purely in +the second and last: so that it would seem, at first, as if the normal type +were more powerful than the variety. But all these children grew up and +intermarried with normal wives and husband, and then, note what took place: +Salvator had four children, three of whom exhibited the hexadactyle members +of their grandfather and father, while the youngest had the pentadactyle +limbs of the mother and grandmother; so that here, notwithstanding a double +pentadactyle dilution of the blood, the hexadactyle variety had the best of +it. The same pre-potency of the variety was still more markedly exemplified +in the progeny of two of the other children, Marie and George. Marie (whose +thumbs only were deformed) gave birth to a boy with six toes, and three +other normally formed children; but George, who was not quite so pure a +pentadactyle, begot, first, two girls, each of whom had six fingers and +toes; then a girl with six fingers on each hand and six toes on the right +foot, but only five toes on the left; and lastly, a boy with only five +fingers and toes. In these instances, therefore, the variety, as it were, +leaped over one generation to reproduce itself in full force in the next. +Finally, the purely pentadactyle André was the father of many children, not +one of whom departed from the normal parental type. + +If a variation which approaches the nature of a monstrosity can strive thus +forcibly to reproduce itself, it is not wonderful that less aberrant +modifications should tend to be preserved even more strongly; and the +history of the Ancon sheep is, in this respect, particularly instructive. +With the "'cuteness" characteristic of their nation, the neighbours of the +Massachusetts farmer imagined it would be an excellent thing if all his +sheep were imbued with the stay-at-home tendencies enforced by Nature upon +the newly-arrived ram; and they advised Wright to kill the old patriarch of +his fold, and install the Ancon ram in his place. The result justified +their sagacious anticipations, and coincided very nearly with what occurred +to the progeny of Gratio Kelleia. The young lambs were almost always either +pure Ancons, or pure ordinary sheep.[Footnote: Colonel Humphreys' +statements are exceedingly explicit on this point:--. "When an Ancon ewe is +impregnated by a common ram, the increase resembles wholly either the ewe +or the ram. The increase of the common ewe impregnated by an Ancon ram +follows entirely the one or the other, without blending any of the +distinguishing and essential peculiarities of both. Frequent instances have +happened where common ewes have had twins by Ancon rams, when one exhibited +the complete marks and features of the ewe, the other of the ram. The +contrast has been rendered singularly striking, when one short-legged and +one long-legged lamb, produced at a birth, have been seen sucking the dam +at the same time."--_Philosophical Transactions_, 1813, Ft. I. pp. 89, +90.] But when sufficient Ancon sheep were obtained to interbreed with one +another, it was found that the offspring was always pure Ancon. Colonel +Humphreys, in fact, states that he was acquainted with only "one +questionable case of a contrary nature." Here, then, is a remarkable and +well-established instance, not only of a very distinct race being +established _per saltum_, but of that race breeding "true" at once, +and showing no mixed forms, even when crossed with another breed. + +By taking care to select Ancons of both sexes, for breeding from, it thus +became easy to establish an extremely well-marked race; so peculiar that, +even when herded with other sheep, it was noted that the Ancons kept +together. And there is every reason to believe that the existence of this +breed might have been indefinitely protracted; but the introduction of the +Merino sheep, which were not only very superior to the Ancons in wool and +meat, but quite as quiet and orderly, led to the complete neglect of the +new breed, so that, in 1813, Colonel Humphreys found it difficult to obtain +the specimen, the skeleton of which was presented to Sir Joseph Banks. We +believe that, for many years, no remnant of it has existed in the United +States. + +Gratio Kelleia was not the progenitor of a race of six-fingered men, as +Seth Wright's ram became a nation of Ancon sheep, though the tendency of +the variety to perpetuate itself appears to have been fully as strong in +the one case as in the other. And the reason of the difference is not far +to seek. Seth Wright took care not to weaken the Ancon blood by matching +his Ancon ewes with any but males of the same variety, while Gratio +Kelleia's sons were too far removed from the patriarchal times to +intermarry with their sisters; and his grand-children seem not to have been +attracted by their six-fingered cousins. In other words, in the one example +a race was produced, because, for several generations, care was taken to +_select_ both parents of the breeding stock from animals exhibiting a +tendency to vary in the same direction; while, in the other, no race was +evolved, because no such selection was exercised. A race is a propagated +variety; and as, by the laws of reproduction, offspring tend to assume the +parental forms, they will be more likely to propagate a variation exhibited +by both parents than that possessed by only one. + +There is no organ of the body of an animal which may not, and does not, +occasionally, vary more or less from the normal type; and there is no +variation which may not be transmitted and which, if selectively +transmitted, may not become the foundation of a race. This great truth, +sometimes forgotten by philosophers, has long been familiar to practical +agriculturists and breeders; and upon it rest all the methods of improving +the breeds of domestic animals, which, for the last century, have been +followed with so much success in England. Colour, form, size, texture of +hair or wool, proportions of various parts, strength or weakness of +constitution, tendency to fatten or to remain lean, to give much or little +milk, speed, strength, temper, intelligence, special instincts; there is +not one of these characters the transmission of which is not an every-day +occurrence within the experience of cattle-breeders, stock-farmers, +horse-dealers, and dog and poultry fanciers. Nay, it is only the other day +that an eminent physiologist, Dr. Brown-Séquard, communicated to the Royal +Society his discovery that epilepsy, artificially produced in guinea-pigs, +by a means which he has discovered, is transmitted to their offspring. +[Footnote: Compare Weismann's _Essays Upon Heredity_, p. 310, _et +seq_. 1893.] + +But a race, once produced, is no more a fixed and immutable entity than the +stock whence it sprang; variations arise among its members, and as these +variations are transmitted like any others, new races may be developed out +of the pre-existing one _ad infinitum_, or, at least, within any limit +at present determined. Given sufficient time and sufficiently careful +selection, and the multitude of races which may arise from a common stock +is as astonishing as are the extreme structural differences which they may +present. A remarkable example of this is to be found in the rock-pigeon, +which Mr. Darwin has, in our opinion, satisfactorily demonstrated to be the +progenitor of all our domestic pigeons, of which there are certainly more +than a hundred well-marked races. The most noteworthy of these races are, +the four great stocks known to the "fancy" as tumblers, pouters, carriers, +and fantails; birds which not only differ most singularly in size, colour, +and habits, but in the form of the beak and of the skull; in the +proportions of the beak to the skull; in the number of tail-feathers; in +the absolute and relative size of the feet; in the presence or absence of +the uropygial gland; in the number of vertebræ in the back; in short, in +precisely those characters in which the genera and species of birds differ +from one another. + +And it is most remarkable and instructive to observe, that none of these +races can be shown to have been originated by the action of changes in what +are commonly called external circumstances, upon the wild rock-pigeon. On +the contrary, from time immemorial pigeon-fanciers have had essentially +similar methods of treating their pets, which have been housed, fed, +protected and cared for in much the same way in all pigeonries. In fact, +there is no case better adapted than that of the pigeons to refute the +doctrine which one sees put forth on high authority, that "no other +characters than those founded on the development of bone for the attachment +of muscles" are capable of variation. In precise contradiction of this +hasty assertion, Mr. Darwin's researches prove that the skeleton of the +wings in domestic pigeons has hardly varied at all from that of the wild +type; while, on the other hand, it is in exactly those respects, such as +the relative length of the beak and skull, the number of the vertebrae, and +the number of the tail-feathers, in which muscular exertion can have no +important influence, that the utmost amount of variation has taken place. + +We have said that the following out of the properties exhibited by +physiological species would lead us into difficulties, and at this point +they begin to be obvious; for if, as the result of spontaneous variation +and of selective breeding, the progeny of a common stock may become +separated into groups distinguished from one another by constant, not +sexual, morphological characters, it is clear that the physiological +definition of species is likely to clash with the morphological definition. +No one would hesitate to describe the pouter and the tumbler as distinct +species, if they were found fossil, or if their skins and skeletons were +imported, as those of exotic wild birds commonly are--and without doubt, if +considered alone, they are good and distinct morphological species. On the +other hand, they are not physiological species, for they are descended from +a common stock, the rock-pigeon. + +Under these circumstances, as it is admitted on all sides that races occur +in Nature, how are we to know whether any apparently distinct animals are +really of different physiological species, or not, seeing that the amount +of morphological difference is no safe guide? Is there any test of a +physiological species? The usual answer of physiologists is in the +affirmative. It is said that such a test is to be found in the phænomena of +hybridisation--in the results of crossing races, as compared with the +results of crossing species. + +So far as the evidence goes at present, individuals, of what are certainly +known to be mere races produced by selection, however distinct they may +appear to be, not only breed freely together, but the offspring of such +crossed races are perfectly fertile with one another. Thus, the spaniel and +the greyhound, the dray-horse and the Arab, the pouter and the tumbler, +breed together with perfect freedom, and their mongrels, if matched with +other mongrels of the same kind, are equally fertile. + +On the other hand, there can be no doubt that the individuals of many +natural species are either absolutely infertile if crossed with individuals +of other species, or, if they give rise to hybrid offspring, the hybrids so +produced are infertile when paired together. The horse and the ass, for +instance, if so crossed, give rise to the mule, and there is no certain +evidence of offspring ever having been produced by a male and female mule. +The unions of the rock-pigeon and the ring-pigeon appear to be equally +barren of result. Here, then, says the physiologist, we have a means of +distinguishing any two true species from any two varieties. If a male and a +female, selected from each group, produce offspring, and that offspring is +fertile with others produced in the same way, the groups are races and not +species. If, on the other hand, no result ensues, or if the offspring are +infertile with others produced in the same way, they are true physiological +species. The test would be an admirable one, if, in the first place, it +were always practicable to apply it, and if, in the second, it always +yielded results susceptible of a definite interpretation. Unfortunately, in +the great majority of cases, this touchstone for species is wholly +inapplicable. + +The constitution of many wild animals is so altered by confinement that +they will not breed even with their own females, so that the negative +results obtained from crosses are of no value; and the antipathy of wild +animals of different species for one another, or even of wild and tame +members of the same species, is ordinarily so great, that it is hopeless to +look for such unions in Nature. The hermaphrodism of most plants, the +difficulty in the way of insuring the absence of their own or the proper +working of other pollen, are obstacles of no less magnitude in applying the +test to them. And, in both animals and plants, is super-added the further +difficulty, that experiments must be continued over a long time for the +purpose of ascertaining the fertility of the mongrel or hybrid progeny, as +well as of the first crosses from which they spring. + +Not only do these great practical difficulties lie in the way of applying +the hybridisation test, but even when this oracle can be questioned, its +replies are sometimes as doubtful as those of Delphi. For example, cases +are cited by Mr. Darwin, of plants which are more fertile with the pollen +of another species than with their own; and there are others, such as +certain _Fuci,_ the male element of which will fertilise the ovule of +a plant of distinct species, while the males of the latter species are +ineffective with the females of the first. So that, in the last-named +instance, a physiologist, who should cross the two species in one way, +would decide that they were true species; while another, who should cross +them in the reverse way, would, with equal justice, according to the rule, +pronounce them to be mere races. Several plants, which there is great +reason to believe are mere varieties, are almost sterile when crossed; +while both animals and plants, which have always been regarded by +naturalists as of distinct species, turn out, when the test is applied, to +be perfectly fertile. Again, the sterility or fertility of crosses seems to +bear no relation to the structural resemblances or differences of the +members of any two groups. + +Mr. Darwin has discussed this question with singular ability and +circumspection, and his conclusions are summed up as follows, at page 276 +of his work:-- + +"First crosses between forms sufficiently distinct to be ranked as species, +and their hybrids, are very generally, but not universally, sterile. The +sterility is of all degrees, and is often so slight that the two most +careful experimentalists who have ever lived have come to diametrically +opposite conclusions in ranking forms by this test. The sterility is +innately variable in individuals of the same species, and is eminently +susceptible of favourable and unfavourable conditions. The degree of +sterility does not strictly follow systematic affinity, but is governed by +several curious and complex laws. It is generally different and sometimes +widely different, in reciprocal crosses between the same two species. It is +not always equal in degree in a first cross, and in the hybrid produced +from this cross. + +"In the same manner as in grafting trees, the capacity of one species or +variety to take on another is incidental on generally unknown differences +in their vegetative systems; so in crossing, the greater or less facility +of one species to unite with another is incidental on unknown differences +in their reproductive systems. There is no more reason to think that +species have been specially endowed with various degrees of sterility to +prevent them crossing and breeding in Nature, than to think that trees have +been specially endowed with various and somewhat analogous degrees of +difficulty in being grafted together, in order to prevent them becoming +inarched in our forests. + +"The sterility of first crosses between pure species, which have their +reproductive systems perfect, seems to depend on several circumstances; in +some cases largely on the early death of the embryo. The sterility of +hybrids which have their reproductive systems imperfect, and which have had +this system and their whole organisation disturbed by being compounded of +two distinct species, seems closely allied to that sterility which so +frequently affects pure species when their natural conditions of life have +been disturbed. This view is supported by a parallelism of another kind: +namely, that the crossing of forms, only slightly different, is favourable +to the vigour and fertility of the offspring; and that slight changes in +the conditions of life are apparently favourable to the vigour and +fertility of all organic beings. It is not surprising that the degree of +difficulty in uniting two species, and the degree of sterility of their +hybrid offspring, should generally correspond, though due to distinct +causes; for both depend on the amount of difference of some kind between +the species which are crossed. Nor is it surprising that the facility of +effecting a first cross, the fertility of hybrids produced from it, and the +capacity of being grafted together--though this latter capacity evidently +depends on widely different circumstances--should all run to a certain +extent parallel with the systematic affinity of the forms which are +subjected to experiment; for systematic affinity attempts to express all +kinds of resemblance between all species. + +"First crosses between forms known to be varieties, or sufficiently alike +to be considered as varieties, and their mongrel offspring, are very +generally, but not quite universally, fertile. Nor is this nearly general +and perfect fertility surprising, when we remember how liable we are to +argue in a circle with respect to varieties in a state of Nature; and when +we remember that the greater number of varieties have been produced under +domestication by the selection of mere external differences, and not of +differences in the reproductive system. In all other respects, excluding +fertility, there is a close general resemblance between hybrids and +mongrels."--Pp. 276-8. + +We fully agree with the general tenor of this weighty passage; but forcible +as are these arguments, and little as the value of fertility or infertility +as a test of species may be, it must not be forgotten that the really +important fact, so far as the inquiry into the origin of species goes, is, +that there are such things in Nature as groups of animals and of plants, +the members of which are incapable of fertile union with those of other +groups; and that there are such things as hybrids, which are absolutely +sterile when crossed with other hybrids. For, if such phænomena as these +were exhibited by only two of those assemblages of living objects, to which +the name of species (whether it be used in its physiological or in its +morphological sense) is given, it would have to be accounted for by any +theory of the origin of species, and every theory which could not account +for it would be, so far, imperfect. + +Up to this point, we have been dealing with matters of fact, and the +statements which we have laid before the reader would, to the best of our +knowledge, be admitted to contain a fair exposition of what is at present +known respecting the essential properties of species, by all who have +studied the question. And whatever may be his theoretical views, no +naturalist will probably be disposed to demur to the following summary of +that exposition:-- + +Living beings, whether animals or plants, are divisible into multitudes of +distinctly definable kinds, which are morphological species. They are also +divisible into groups of individuals, which breed freely together, tending +to reproduce their like, and are physiological species. Normally resembling +their parents, the offspring of members of these species are still liable +to vary; and the variation may be perpetuated by selection, as a race, +which race, in many cases, presents all the characteristics of a +morphological species. But it is not as yet proved that a race ever +exhibits, when crossed with another race of the same species, those +phænomena of hybridisation which are exhibited by many species when crossed +with other species. On the other hand, not only is it not proved that all +species give rise to hybrids infertile _inter se_, but there is much +reason to believe that, in crossing, species exhibit every gradation from +perfect sterility to perfect fertility. + +Such are the most essential characteristics of species. Even were man not +one of them--a member of the same system and subject to the same laws--the +question of their origin, their causal connexion, that is, with the other +phænomena of the universe, must have attracted his attention, as soon as +his intelligence had raised itself above the level of his daily wants. + +Indeed history relates that such was the case, and has embalmed for us the +speculations upon the origin of living beings, which were among the +earliest products of the dawning intellectual activity of man. In those +early days positive knowledge was not to be had, but the craving after it +needed, at all hazards, to be satisfied, and according to the country, or +the turn of thought, of the speculator, the suggestion that all living +things arose from the mud of the Nile, from a primeval egg, or from some +more anthropomorphic agency, afforded a sufficient resting-place for his +curiosity. The myths of Paganism are as dead as Osiris or Zeus, and the man +who should revive them, in opposition to the knowledge of our time, would +be justly laughed to scorn; but the coeval imaginations current among the +rude inhabitants of Palestine, recorded by writers whose very name and age +are admitted by every scholar to be unknown, have unfortunately not yet +shared their fate, but, even at this day, are regarded by nine-tenths of +the civilised world as the authoritative standard of fact and the criterion +of the justice of scientific conclusions, in all that relates to the origin +of things, and, among them, of species. In this nineteenth century, as at +the dawn of modern physical science, the cosmogony of the semi-barbarous +Hebrew is the incubus of the philosopher and the opprobrium of the +orthodox. Who shall number the patient and earnest seekers after truth, +from the days of Galileo until now, whose lives have been embittered and +their good name blasted by the mistaken zeal of Bibliolaters? Who shall +count the host of weaker men whose sense of truth has been destroyed in the +effort to harmonise impossibilities--whose life has been wasted in the +attempt to force the generous new wine of Science into the old bottles of +Judaism, compelled by the outcry of the same strong party? + +It is true that if philosophers have suffered, their cause has been amply +avenged. Extinguished theologians lie about the cradle of every science as +the strangled snakes beside that of Hercules; and history records that +whenever science and orthodoxy have been fairly opposed, the latter has +been forced to retire from the lists, bleeding and crushed if not +annihilated; scotched, if not slain. But orthodoxy is the Bourbon of the +world of thought. It learns not, neither can it forget; and though, at +present, bewildered and afraid to move, it is as willing as ever to insist +that the first chapter of Genesis contains the beginning and the end of +sound science; and to visit, with such petty thunderbolts as its +half-paralysed hands can hurl, those who refuse to degrade Nature to the +level of primitive Judaism. + +Philosophers, on the other hand, have no such aggressive tendencies. With +eyes fixed on the noble goal to which "per aspera et ardua" they tend, they +may, now and then, be stirred to momentary wrath by the unnecessary +obstacles with which the ignorant, or the malicious, encumber, if they +cannot bar, the difficult path; but why should their souls be deeply vexed? +The majesty of Fact is on their side, and the elemental forces of Nature +are working for them. Not a star comes to the meridian at its calculated +time but testifies to the justice of their methods--their beliefs are "one +with the falling rain and with the growing corn." By doubt they are +established, and open inquiry is their bosom friend. Such men have no fear +of traditions however venerable, and no respect for them when they become +mischievous and obstructive; but they have better than mere antiquarian +business in hand, and if dogmas, which ought to be fossil but are not, are +not forced upon their notice, they are too happy to treat them as +non-existent. + + * * * * * + +The hypotheses respecting the origin of species which profess to stand upon +a scientific basis, and, as such, alone demand serious attention, are of +two kinds. The one, the "special creation" hypothesis, presumes every +species to have originated from one or more stocks, these not being the +result of the modification of any other form of living matter--or arising +by natural agencies--but being produced, as such, by a supernatural +creative act. + +The other, the so-called "transmutation" hypothesis, considers that all +existing species are the result of the modification of pre-existing +species, and those of their predecessors, by agencies similar to those +which at the present day produce varieties and races, and therefore in an +altogether natural way; and it is a probable, though not a necessary +consequence of this hypothesis, that all living beings have arisen from a +single stock. With respect to the origin of this primitive stock, or +stocks, the doctrine of the origin of species is obviously not necessarily +concerned. The transmutation hypothesis, for example, is perfectly +consistent either with the conception of a special creation of the +primitive germ, or with the supposition of its having arisen, as a +modification of inorganic matter, by natural causes. + +The doctrine of special creation owes its existence very largely to the +supposed necessity of making science accord with the Hebrew cosmogony; but +it is curious to observe that, as the doctrine is at present maintained by +men of science, it is as hopelessly inconsistent with the Hebrew view as +any other hypothesis. + +If there be any result which has come more clearly out of geological +investigation than another, it is, that the vast series of extinct animals +and plants is not divisible, as it was once supposed to be, into distinct +groups, separated by sharply-marked boundaries. There are no great gulfs +between epochs and formations--no successive periods marked by the +appearance of plants, of water animals, and of land animals, _en +masse_. Every year adds to the list of links between what the older +geologists supposed to be widely separated epochs: witness the crags +linking the drift with older tertiaries; the Maestricht beds linking the +tertiaries with the chalk; the St. Cassian beds exhibiting an abundant +fauna of mixed mesozoic and palaeozoic types, in rocks of an epoch once +supposed to be eminently poor in life; witness, lastly, the incessant +disputes as to whether a given stratum shall be reckoned devonian or +carboniferous, silurian or devonian, cambrian or silurian. + +This truth is further illustrated in a most interesting manner by the +impartial and highly competent testimony of M. Pictet, from whose +calculations of what percentage of the genera of animals, existing in any +formation, lived during the preceding formation, it results that in no case +is the proportion less than _one-third_, or 33 per cent. It is the +triassic formation, or the commencement of the mesozoic epoch, which has +received the smallest inheritance from preceding ages. The other formations +not uncommonly exhibit 60, 80, or even 94 per cent, of genera in common +with those whose remains are imbedded in their predecessor. Not only is +this true, but the subdivisions of each formation exhibit new species +characteristic of, and found only in, them; and, in many cases, as in the +lias for example, the separate beds of these subdivisions are distinguished +by well-marked and peculiar forms of life. A section, a hundred feet thick, +will exhibit, at different heights, a dozen species of ammonite, none of +which passes beyond its particular zone of limestone, or clay, into the +zone below it or into that above it; so that those who adopt the doctrine +of special creation must be prepared to admit, that at intervals of time, +corresponding with the thickness of these beds, the Creator thought fit to +interfere with the natural course of events for the purpose of making a new +ammonite. It is not easy to transplant oneself into the frame of mind of +those who can accept such a conclusion as this, on any evidence short of +absolute demonstration; and it is difficult to see what is to be gained by +so doing, since, as we have said, it is obvious that such a view of the +origin of living beings is utterly opposed to the Hebrew cosmogony. +Deserving no aid from the powerful arm of Bibliolatry, then, does the +received form of the hypothesis of special creation derive any support from +science or sound logic? Assuredly not much. The arguments brought forward +in its favour all take one form: If species were not supernaturally +created, we cannot understand the facts _x_, or _y_, or _z_; +we cannot understand the structure of animals or plants, unless we suppose +they were contrived for special ends; we cannot understand the structure of +the eye, except by supposing it to have been made to see with; we cannot +understand instincts, unless we suppose animals to have been miraculously +endowed with them. + +As a question of dialectics, it must be admitted that this sort of +reasoning is not very formidable to those who are not to be frightened by +consequences. It is an _argumentum ad ignorantiam_--take this +explanation or be ignorant. But suppose we prefer to admit our ignorance +rather than adopt a hypothesis at variance with all the teachings of +Nature? Or, suppose for a moment we admit the explanation, and then +seriously ask ourselves how much the wiser are we; what does the +explanation explain? Is it any more than a grandiloquent way of announcing +the fact, that we really know nothing about the matter? A phenomenon is +explained when it is shown to be a case of some general law of Nature; but +the supernatural interposition of the Creator can, by the nature of the +case, exemplify no law, and if species have really arisen in this way, it +is absurd to attempt to discuss their origin. + +Or, lastly, let us ask ourselves whether any amount of evidence which the +nature of our faculties permits us to attain, can justify us in asserting +that any phenomenon is out of the reach of natural causation. To this end +it is obviously necessary that we should know all the consequences to which +all possible combinations, continued through unlimited time, can give rise. +If we knew these, and found none competent to originate species, we should +have good ground for denying their origin by natural causation. Till we +know them, any hypothesis is better than one which involves us in such +miserable presumption. + +But the hypothesis of special creation is not only a mere specious mask for +our ignorance; its existence in Biology marks the youth and imperfection of +the science. For what is the history of every science but the history of +the elimination of the notion of creative, or other interferences, with the +natural order of the phænomena which are the subject-matter of that +science? When Astronomy was young "the morning stars sang together for +joy," and the planets were guided in their courses by celestial hands. Now, +the harmony of the stars has resolved itself into gravitation according to +the inverse squares of the distances, and the orbits of the planets are +deducible from the laws of the forces which allow a schoolboy's stone to +break a window. The lightning was the angel of the Lord; but it has pleased +Providence, in these modern times, that science should make it the humble +messenger of man, and we know that every flash that shimmers about the +horizon on a summer's evening is determined by ascertainable conditions, +and that its direction and brightness might, if our knowledge of these were +great enough, have been calculated. + +The solvency of great mercantile companies rests on the validity of the +laws which have been ascertained to govern the seeming irregularity of that +human life which the moralist bewails as the most uncertain of things; +plague, pestilence, and famine are admitted, by all but fools, to be the +natural result of causes for the most part fully within human control, and +not the unavoidable tortures inflicted by wrathful Omnipotence upon His +helpless handiwork. + +Harmonious order governing eternally continuous progress--the web and woof +of matter and force interweaving by slow degrees, without a broken thread, +that veil which lies between us and the Infinite--that universe which alone +we know or can know; such is the picture which science draws of the world, +and in proportion as any part of that picture is in unison with the rest, +so may we feel sure that it is rightly painted. Shall Biology alone remain +out of harmony with her sister sciences? + +Such arguments against the hypothesis of the direct creation of species as +these are plainly enough deducible from general considerations; but there +are, in addition, phenomena exhibited by species themselves, and yet not so +much a part of their very essence as to have required earlier mention, +which are in the highest degree perplexing, if we adopt the popularly +accepted hypothesis. Such are the facts of distribution in space and in +time; the singular phenomena brought to light by the study of development; +the structural relations of species upon which our systems of +classification are founded; the great doctrines of philosophical anatomy, +such as that of homology, or of the community of structural plan exhibited +by large groups of species differing very widely in their habits and +functions. + +The species of animals which inhabit the sea on opposite sides of the +isthmus of Panama are wholly distinct;[Footnote: Recent investigations tend +to show that this statement is not strictly accurate.--1870.] the animals +and plants which inhabit islands are commonly distinct from those of the +neighbouring mainlands, and yet have a similarity of aspect. The mammals of +the latest tertiary epoch in the Old and New Worlds belong to the same +genera, or family groups, as those which now inhabit the same great +geographical area. The crocodilian reptiles which existed in the earliest +secondary epoch were similar in general structure to those now living, but +exhibit slight differences in their vertebræ, nasal passages, and one or +two other points. The guinea-pig has teeth which are shed before it is +born, and hence can never subserve the masticatory purpose for which they +seem contrived, and, in like manner, the female dugong has tusks which +never cut the gum. All the members of the same great group run through +similar conditions in their development, and all their parts, in the adult +state, are arranged according to the same plan. Man is more like a gorilla +than a gorilla is like a lemur. Such are a few, taken at random, among the +multitudes of similar facts which modern research has established; but when +the student seeks for an explanation of them from the supporters of the +received hypothesis of the origin of species, the reply he receives is, in +substance, of Oriental simplicity and brevity--"Mashallah! it so pleases +God!" There are different species on opposite sides of the isthmus of +Panama, because they were created different on the two sides. The pliocene +mammals are like the existing ones, because such was the plan of creation; +and we find rudimental organs and similarity of plan, because it has +pleased the Creator to set before Himself a "divine exemplar or archetype," +and to copy it in His works; and somewhat ill, those who hold this view +imply, in some of them. That such verbal hocus-pocus should be received as +science will one day be regarded as evidence of the low state of +intelligence in the nineteenth century, just as we amuse ourselves with the +phraseology about Nature's abhorrence of a vacuum, wherewith Torricellis +compatriots were satisfied to explain the rise of water in a pump. And be +it recollected that this sort of satisfaction works not only negative but +positive ill, by discouraging inquiry, and so depriving man of the usufruct +of one of the most fertile fields of his great patrimony, Nature. + +The objections to the doctrine of the origin of species by special creation +which have been detailed, must have occurred, with more or less force, to +the mind of every one who has seriously and independently considered the +subject. It is therefore no wonder that, from time to time, this hypothesis +should have been met by counter hypotheses, all as well, and some better +founded than itself; and it is curious to remark that the inventors of the +opposing views seem to have been led into them as much by their knowledge +of geology, as by their acquaintance with biology. In fact, when the mind +has once admitted the conception of the gradual production of the present +physical state of our globe, by natural causes operating through long ages +of time, it will be little disposed to allow that living beings have made +their appearance in another way, and the speculations of De Maillet and his +successors are the natural complement of Scilla's demonstration of the true +nature of fossils. + +A contemporary of Newton and of Leibnitz, sharing therefore in the +intellectual activity of the remarkable age which witnessed the birth of +modern physical science, Benoît de Maillet spent a long life as a consular +agent of the French Government in various Mediterranean ports. For sixteen +years, in fact, he held the office of Consul-General in Egypt, and the +wonderful phenomena offered by the valley of the Nile appear to have +strongly impressed his mind, to have directed his attention to all facts of +a similar order which came within his observation, and to have led him to +speculate on the origin of the present condition of our globe and of its +inhabitants. But, with all his ardour for science, De Maillet seems to have +hesitated to publish views which, notwithstanding the ingenious attempts to +reconcile them with the Hebrew hypothesis contained in the preface to +"Telliamed," were hardly likely to be received with favour by his +contemporaries. + +But a short time had elapsed since more than one of the great anatomists +and physicists of the Italian school had paid dearly for their endeavours +to dissipate some of the prevalent errors; and their illustrious pupil, +Harvey, the founder of modern physiology, had not fared so well, in a +country less oppressed by the benumbing influences of theology, as to tempt +any man to follow his example. Probably not uninfluenced by these +considerations, his Catholic majesty's Consul-General for Egypt kept his +theories to himself throughout a long life, for "Telliamed," the only +scientific work which is known to have proceeded from his pen, was not +printed till 1735, when its author had reached the ripe age of +seventy-nine; and though De Maillet lived three years longer, his book was +not given to the world before 1748. Even then it was anonymous to those who +were not in the secret of the anagrammatic character of its title; and the +preface and dedication are so worded as, in case of necessity, to give the +printer a fair chance of falling back on the excuse that the work was +intended for a mere _jeu d'esprit_. + +The speculations of the suppositious Indian sage, though quite as sound as +those of many a "Mosaic Geology," which sells exceedingly well, have no +great value if we consider them by the light of modern science. The waters +are supposed to have originally covered the whole globe; to have deposited +the rocky masses which compose its mountains by processes comparable to +those which are now forming mud, sand, and shingle; and then to have +gradually lowered their level, leaving the spoils of their animal and +vegetable inhabitants embedded in the strata. As the dry land appeared, +certain of the aquatic animals are supposed to have taken to it, and to +have become gradually adapted to terrestrial and aërial modes of existence. +But if we regard the general tenor and style of the reasoning in relation +to the state of knowledge of the day, two circumstances appear very well +worthy of remark. The first, that De Maillet had a notion of the +modifiability of living forms (though without any precise information on +the subject), and how such modifiability might account for the origin of +species; the second, that he very clearly apprehended the great modern +geological doctrine, so strongly insisted upon by Hutton, and so ably and +comprehensively expounded by Lyell, that we must look to existing causes +for the explanation of past geological events. Indeed, the following +passage of the preface, in which De Maillet is supposed to speak of the +Indian philosopher Telliamed, his _alter ego,_ might have been written +by the most philosophical uniformitarian of the present day:-- + +"Ce qu'il y a d'étonnant, est que pour arriver à ces connaissances il +semble avoir perverti l'ordre naturel, puisqu'au lieu de s'attacher d'abord +à rechercher l'origine de notre globe il a commence par travailler à +s'instruire de la nature. Mais à l'entendre, ce renversement de l'ordre a +été pour lui l'effet d'un génie favorable qui l'a conduit pas à pas et +comme par la main aux découvertes les plus sublimes. C'est en décomposant +la substance de ce globe par tine anatomie exacte de toutes ses parties +qu'il a premierement appris de quelles matières il était composé et quels +arrangemens ces mêmes matières observaient entre elles. Ces lumieres +jointes à l'esprit de comparaison toujours nécessaire à quiconque +entreprend de percer les voiles dont la nature aime à se cacher, ont servi +de guide à notre philosophe pour parvenir à des connoissances plus +intéressantes. Par la matière et l'arrangement de ces compositions il +prétend avoir reconnu quelle est la véritable origine de ce globe que nous +habitons, comment et par qui il a été formé."-Pp. xix. xx. + +But De Maillet was before his age, and as could hardly fail to happen to +one who speculated on a zoological and botanical question before Linnæus, +and on a physiological problem before Haller, he fell into great errors +here and there; and hence, perhaps, the general neglect of his work. +Robinet's speculations are rather behind, than in advance of, those of De +Maillet; and though Linnæus may have played with the hypothesis of +transmutation, it obtained no serious support until Lamarck adopted it, and +advocated it with great ability in his "Philosophie Zoologique." + +Impelled towards the hypothesis of the transmutation of species, partly by +his general cosmological and geological views; partly by the conception of +a graduated, though irregularly branching, scale of being, which had arisen +out of his profound study of plants and of the lower forms of animal life, +Lamarck, whose general line of thought often closely resembles that of De +Maillet, made a great advance upon the crude and merely speculative manner +in which that writer deals with the question of the origin of living +beings, by endeavouring to find physical causes competent to effect that +change of one species into another, which De Maillet had only supposed to +occur. And Lamarck conceived that he had found in Nature such causes, amply +sufficient for the purpose in view. It is a physiological fact, he says, +that organs are increased in size by action, atrophied by inaction; it is +another physiological fact that modifications produced are transmissible to +offspring. Change the actions of an animal, therefore, and you will change +its structure, by increasing the development of the parts newly brought +into use and by the diminution of those less used; but by altering the +circumstances which surround it you will alter its actions, and hence, in +the long run, change of circumstance must produce change of organisation. +All the species of animals, therefore, are, in Lamarck's view, the result +of the indirect action of changes of circumstance, upon those primitive +germs which he considered to have originally arisen, by spontaneous +generation, within the waters of the globe. It is curious, however, that +Lamarck should insist so strongly [Footnote: See _Phil. Zoologique_, +vol. i. p. 222. et seq.] as he has done, that circumstances never in any +degree directly modify the form or the organisation of animals, but only +operate by changing their wants and consequently their actions; for he +thereby brings upon himself the obvious question, How, then, do plants, +which cannot be said to have wants or actions, become modified? To this he +replies, that they are modified by the changes in their nutritive +processes, which are effected by changing circumstances; and it does not +seem to have occurred to him that such changes might be as well supposed to +take place among animals. + +When we have said that Lamarck felt that mere speculation was not the way +to arrive at the origin of species, but that it was necessary, in order to +the establishment of any sound theory on the subject, to discover by +observation or otherwise, some _vera causa_, competent to give rise to +them; that he affirmed the true order of classification to coincide with +the order of their development one from another; that he insisted on the +necessity of allowing sufficient time, very strongly; and that all the +varieties of instinct and reason were traced back by him to the same cause +as that which has given rise to species, we have enumerated his chief +contributions to the advance of the question. On the other hand, from his +ignorance of any power in Nature competent to modify the structure of +animals, except the development of parts, or atrophy of them, in +consequence of a change of needs, Lamarck was led to attach infinitely +greater weight than it deserves to this agency, and the absurdities into +which he was led have met with deserved condemnation. Of the struggle for +existence, on which, as we shall see, Mr. Darwin lays such great stress, he +had no conception; indeed, he doubts whether there really are such things +as extinct species, unless they be such large animals as may have met their +death at the hands of man; and so little does he dream of there being any +other destructive causes at work, that, in discussing the possible +existence of fossil shells, he asks, "Pourquoi d'ailleurs seroient-ils +perdues dès que l'homme n'a pu opérer leur destruction?" ("Phil. Zool.," +vol. i. p. 77.) Of the influence of selection Lamarck has as little notion, +and he makes no use of the wonderful phenomena which are exhibited by +domesticated animals, and illustrate its powers. The vast influence of +Cuvier was employed against the Lamarckian views, and, as the untenability +of some of his conclusions was easily shown, his doctrines sank under the +opprobrium of scientific, as well as of theological, heterodoxy. Nor have +the efforts made of late years to revive them tended to re-establish their +credit in the minds of sound thinkers acquainted with the facts of the +case; indeed it may be doubted whether Lamarck has not suffered more from +his friends than from his foes. + +Two years ago, in fact, though we venture to question if even the strongest +supporters of the special creation hypothesis had not, now and then, an +uneasy consciousness that all was not right, their position seemed more +impregnable than ever, if not by its own inherent strength, at any rate by +the obvious failure of all the attempts which had been made to carry it. On +the other hand, however much the few, who thought deeply on the question of +species, might be repelled by the generally received dogmas, they saw no +way of escaping from them save by the adoption of suppositions so little +justified by experiment or by observation as to be at least equally +distasteful. + +The choice lay between two absurdities and a middle condition of uneasy +scepticism; which last, however unpleasant and unsatisfactory, was +obviously the only justifiable state of mind under the circumstances. + +Such being the general ferment in the minds of naturalists, it is no wonder +that they mustered strong in the rooms of the Linnæan Society, on the 1st +of July of the year 1858, to hear two papers by authors living on opposite +sides of the globe, working out their results independently, and yet +professing to have discovered one and the same solution of all the problems +connected with species. The one of these authors was an able naturalist, +Mr. Wallace, who had been employed for some years in studying the +productions of the islands of the Indian Archipelago, and who had forwarded +a memoir embodying his views to Mr. Darwin, for communication to the +Linnæan Society. On perusing the essay, Mr. Darwin was not a little +surprised to find that it embodied some of the leading ideas of a great +work which he had been preparing for twenty years, and parts of which, +containing a development of the very same views, had been perused by his +private friends fifteen or sixteen years before. Perplexed in what manner +to do full justice both to his friend and to himself, Mr. Darwin placed the +matter in the hands of Dr. Hooker and Sir Charles Lyell, by whose advice he +communicated a brief abstract of his own views to the Linnæan Society, at +the same time that Mr. Wallace's paper was read. Of that abstract, the work +on the "Origin of Species" is an enlargement; but a complete statement of +Mr. Darwin's doctrine is looked for in the large and well-illustrated work +which he is said to be preparing for publication. + +The Darwinian hypothesis has the merit of being eminently simple and +comprehensible in principle, and its essential positions may be stated in a +very few words: all species have been produced by the development of +varieties from common stocks; by the conversion of these, first into +permanent races and then into new species, by the process of _natural +selection_, which process is essentially identical with that artificial +selection by which man has originated the races of domestic animals--the +_struggle for existence_ taking the place of man, and exerting, in the +case of natural selection, that selective action which he performs in +artificial selection. + +The evidence brought forward by Mr. Darwin in support of his hypothesis is +of three kinds. First, he endeavours to prove that species may be +originated by selection; secondly, he attempts to show that natural causes +are competent to exert selection; and thirdly, he tries to prove that the +most remarkable and apparently anomalous phænomena exhibited by the +distribution, development, and mutual relations of species, can be shown to +be deducible from the general doctrine of their origin, which he propounds, +combined with the known facts of geological change; and that, even if all +these phænomena are not at present explicable by it, none are necessarily +inconsistent with it. + +There cannot be a doubt that the method of inquiry which Mr. Darwin has +adopted is not only rigorously in accordance with the canons of scientific +logic, but that it is the only adequate method. Critics exclusively trained +in classics or in mathematics, who have never determined a scientific fact +in their lives by induction from experiment or observation, prate learnedly +about Mr. Darwin's method, which is not inductive enough, not Baconian +enough, forsooth, for them. But even if practical acquaintance with the +process of scientific investigation is denied them, they may learn, by the +perusal of Mr. Mill's admirable chapter "On the Deductive Method," that +there are multitudes of scientific inquiries in which the method of pure +induction helps the investigator but a very little way. + +"The mode of investigation," says Mr. Mill, "which, from the proved +inapplicability of direct methods of observation and experiment, remains to +us as the main source of the knowledge we possess, or can acquire, +respecting the conditions and laws of recurrence of the more complex +phænomena, is called, in its most general expression, the deductive method, +and consists of three operations: the first, one of direct induction; the +second, of ratiocination; and the third, of verification." + +Now, the conditions which have determined the existence of species are not +only exceedingly complex, but, so far as the great majority of them are +concerned, are necessarily beyond our cognisance. But what Mr. Darwin has +attempted to do is in exact accordance with the rule laid down by Mr. Mill; +he has endeavoured to determine certain great facts inductively, by +observation and experiment; he has then reasoned from the data thus +furnished; and lastly, he has tested the validity of his ratiocination by +comparing his deductions with the observed facts of Nature. Inductively, +Mr. Darwin endeavours to prove that species arise in a given way. +Deductively, he desires to show that, if they arise in that way, the facts +of distribution, development, classification, &c., may be accounted for, +_i.e._ may be deduced from their mode of origin, combined with +admitted changes in physical geography and climate, during an indefinite +period. And this explanation, or coincidence of observed with deduced +facts, is, so far as it extends, a verification of the Darwinian view. + +There is no fault to be found with Mr. Darwin's method, then; but it is +another question whether he has fulfilled all the conditions imposed by +that method. Is it satisfactorily proved, in fact, that species may be +originated by selection? that there is such a thing as natural selection? +that none of the phænomena exhibited by species are inconsistent with the +origin of species in this way? If these questions can be answered in the +affirmative, Mr. Darwin's view steps out of the rank of hypotheses into +those of proved theories; but, so long as the evidence at present adduced +falls short of enforcing that affirmation, so long, to our minds, must the +new doctrine be content to remain among the former--an extremely valuable, +and in the highest degree probable, doctrine, indeed the only extant +hypothesis which is worth anything in a scientific point of view; but still +a hypothesis, and not yet the theory of species. + +After much consideration, and with assuredly no bias against Mr. Darwin's +views, it is our clear conviction that, as the evidence stands, it is not +absolutely proven that a group of animals, having all the characters +exhibited by species in Nature, has ever been originated by selection, +whether artificial or natural. Groups having the morphological character of +species--distinct and permanent races in fact--have been so produced over +and over again; but there is no positive evidence, at present, that any +group of animals has, by variation and selective breeding, given rise to +another group which was, even in the least degree, infertile with the +first. Mr. Darwin is perfectly aware of this weak point, and brings forward +a multitude of ingenious and important arguments to diminish the force of +the objection. We admit the value of these arguments to their fullest +extent; nay, we will go so far as to express our belief that experiments, +conducted by a skilful physiologist, would very probably obtain the desired +production of mutually more or less infertile breeds from a common stock, +in a comparatively few years; but still, as the case stands at present, +this "little rift within the lute" is not to be disguised nor overlooked. + +In the remainder of Mr. Darwin's argument our own private ingenuity has not +hitherto enabled us to pick holes of any great importance; and judging by +what we hear and read, other adventurers in the same field do not seem to +have been much more fortunate. It has been urged, for instance, that in his +chapters on the struggle for existence and on natural selection, Mr. Darwin +does not so much prove that natural selection does occur, as that it must +occur; but, in fact, no other sort of demonstration is attainable. A race +does not attract our attention in Nature until it has, in all probability, +existed for a considerable time, and then it is too late to inquire into +the conditions of its origin. Again, it is said that there is no real +analogy between the selection which takes place under domestication, by +human influence, and any operation which can be effected by Nature, for man +interferes intelligently. Reduced to its elements, this argument implies +that an effect produced with trouble by an intelligent agent must, _à +fortiori,_ be more troublesome, if not impossible, to an unintelligent +agent. Even putting aside the question whether Nature, acting as she does +according to definite and invariable laws, can be rightly called an +unintelligent agent, such a position as this is wholly untenable. Mix salt +and sand, and it shall puzzle the wisest of men, with his mere natural +appliances, to separate all the grains of sand from all the grains of salt; +but a shower of rain will effect the same object in ten minutes. And so, +while man may find it tax all his intelligence to separate any variety +which arises, and to breed selectively from it, the destructive agencies +incessantly at work in Nature, if they find one variety to be more soluble +in circumstances than the other, will inevitably, in the long run, +eliminate it. + +A frequent and a just objection to the Lamarckian hypothesis of the +transmutation of species is based upon the absence of transitional forms +between many species. But against the Darwinian hypothesis this argument +has no force. Indeed, one of the most valuable and suggestive parts of Mr. +Darwin's work is that in which he proves, that the frequent absence of +transitions is a necessary consequence of his doctrine, and that the stock +whence two or more species have sprung, need in no respect be intermediate +between these species. If any two species have arisen from a common stock +in the same way as the carrier and the pouter, say, have arisen from the +rock-pigeon, then the common stock of these two species need be no more +intermediate between the two than the rock-pigeon is between the carrier +and pouter. Clearly appreciate the force of this analogy, and all the +arguments against the origin of species by selection, based on the absence +of transitional forms, fall to the ground. And Mr. Darwin's position might, +we think, have been even stronger than it is if he had not embarrassed +himself with the aphorism, "_Natura non facit saltum_," which turns up +so often in his pages. We believe, as we have said above, that Nature does +make jumps now and then, and a recognition of the fact is of no small +importance in disposing of many minor objections to the doctrine of +transmutation. + +But we must pause. The discussion of Mr. Darwin's arguments in detail would +lead us far beyond the limits within which we proposed, at starting, to +confine this article. Our object has been attained if we have given an +intelligible, however brief, account of the established facts connected +with species, and of the relation of the explanation of those facts offered +by Mr. Darwin to the theoretical views held by his predecessors and his +contemporaries, and, above all, to the requirements of scientific logic. We +have ventured to point out that it does not, as yet, satisfy all those +requirements; but we do not hesitate to assert that it is as superior to +any preceding or contemporary hypothesis, in the extent of observational +and experimental basis on which it rests, in its rigorously scientific +method, and in its power of explaining biological phenomena, as was the +hypothesis of Copernicus to the speculations of Ptolemy. But the planetary +orbits turned out to be not quite circular after all, and, grand as was the +service Copernicus rendered to science, Kepler and Newton had to come after +him. What if the orbit of Darwinism should be a little too circular? What +if species should offer residual phænomena, here and there, not explicable +by natural selection? Twenty years hence naturalists may be in a position +to say whether this is, or is not, the case; but in either event they will +owe the author of "The Origin of Species" an immense debt of gratitude. We +should leave a very wrong impression on the reader's mind if we permitted +him to suppose that the value of that work depends wholly on the ultimate +justification of the theoretical views which it contains. On the contrary, +if they were disproved to-morrow, the book would still be the best of its +kind--the most compendious statement of well-sifted facts bearing on the +doctrine of species that has ever appeared. The chapters on Variation, on +the Struggle for Existence, on Instinct, on Hybridism, on the Imperfection +of the Geological Record, on Geographical Distribution, have not only no +equals, but, so far as our knowledge goes, no competitors, within the range +of biological literature. And viewed as a whole, we do not believe that, +since the publication of Von Baer's "Researches on Development," thirty +years ago, any work has appeared calculated to exert so large an influence, +not only on the future of Biology, but in extending the domination of +Science over regions of thought into which she has, as yet, hardly +penetrated. + + + + +III + +CRITICISMS ON "THE ORIGIN OF SPECIES" + +[1864] + + +1. UEBER DIE DARWIN'SCHE SCHÖPFUNGSTHEORIE; EIN VORTRAG, Von A. KÖLLIKER. +Leipzig, 1864. + +2. EXAMINATION DU LIVRE DE M. DARWIN SUR L'ORIGINE DES ESPÈCES. Par P. +FLOURENS. Paris, 1864. + +In the course of the present year several foreign commentaries upon Mr. +Darwin's great work have made their appearance. Those who have perused that +remarkable chapter of the "Antiquity of Man," in which Sir Charles Lyell +draws a parallel between the development of species and that of languages, +will be glad to hear that one of the most eminent philologers of Germany, +Professor Schleicher, has, independently, published a most instructive and +philosophical pamphlet (an excellent notice of which is to be found in the +_Reader_, for February 27th of this year) supporting similar views +with all the weight of his special knowledge and established authority as a +linguist. Professor Haeckel, to whom Schleicher addresses himself, +previously took occasion, in his splendid monograph on the +_Radiolaria_,[Footnote: _Die Radiolarien: eine Monographie_, p. +231.] to express his high appreciation of, and general concordance with, +Mr. Darwin's views. + +But the most elaborate criticisms of the "Origin of Species" which have +appeared are two works of very widely different merit, the one by Professor +Kölliker, the well-known anatomist and histologist of Würzburg; the other +by M. Flourens, Perpetual Secretary of the French Academy of Sciences. + +Professor Kölliker's critical essay "Upon the Darwinian Theory" is, like +all that proceeds from the pen of that thoughtful and accomplished writer, +worthy of the most careful consideration. It comprises a brief but clear +sketch of Darwin's views, followed by an enumeration of the leading +difficulties in the way of their acceptance; difficulties which would +appear to be insurmountable to Professor Kölliker, inasmuch as he proposes +to replace Mr. Darwin's Theory by one which he terms the "Theory of +Heterogeneous Generation." We shall proceed to consider first the +destructive, and secondly, the constructive portion of the essay. + +We regret to find ourselves compelled to dissent very widely from many of +Professor Kölliker's remarks; and from none more thoroughly than from those +in which he seeks to define what we may term the philosophical position of +Darwinism. + +"Darwin," says Professor Kölliker, "is, in the fullest sense of the word, a +Teleologist. He says quite distinctly (First Edition, pp. 199, 200) that +every particular in the structure of an animal has been created for its +benefit, and he regards the whole series of animal forms only from this +point of view." + +And again: + +"7. The teleological general conception adopted by Darwin is a mistaken +one. + +"Varieties arise irrespectively of the notion of purpose, or of utility, +according to general laws of Nature, and may be either useful, or hurtful, +or indifferent. + +"The assumption that an organism exists only on account of some definite +end in view, and represents something more than the incorporation of a +general idea, or law, implies a one-sided conception of the universe. +Assuredly, every organ has, and every organism fulfils, its end, but its +purpose is not the condition of its existence. Every organism is also +sufficiently perfect for the purpose it serves, and in that, at least, it +is useless to seek for a cause of its improvement." + +It is singular how differently one and the same book will impress different +minds. That which struck the present writer most forcibly on his first +perusal of the "Origin of Species" was the conviction that Teleology, as +commonly understood, had received its deathblow at Mr. Darwin's hands. For +the teleological argument runs thus: an organ or organism (A) is precisely +fitted to perform a function or purpose (B); therefore it was specially +constructed to perform that function. In Paley's famous illustration, the +adaptation of all the parts of the watch to the function, or purpose, of +showing the time, is held to be evidence that the watch was specially +contrived to that end; on the ground, that the only cause we know of, +competent to produce such an effect as a watch which shall keep time, is a +contriving intelligence adapting the means directly to that end. + +Suppose, however, that any one had been able to show that the watch had not +been made directly by any person, but that it was the result of the +modification of another watch which kept time but poorly; and that this +again had proceeded from a structure which could hardly be called a watch +at all--seeing that it had no figures on the dial and the hands were +rudimentary; and that going back and back in time we came at last to a +revolving barrel as the earliest traceable rudiment of the whole fabric. +And imagine that it had been possible to show that all these changes had +resulted, first, from a tendency of the structure to vary indefinitely; and +secondly, from something in the surrounding world which helped all +variations in the direction of an accurate time-keeper, and checked all +those in other directions; then it is obvious that the force of Paley's +argument would be gone. For it would be demonstrated that an apparatus +thoroughly well adapted to a particular purpose might be the result of a +method of trial and error worked by unintelligent agents, as well as of the +direct application of the means appropriate to that end, by an intelligent +agent. + +Now it appears to us that what we have here, for illustration's sake, +supposed to be done with the watch, is exactly what the establishment of +Darwin's Theory will do for the organic world. For the notion that every +organism has been created as it is and launched straight at a purpose, Mr. +Darwin substitutes the conception of something which may fairly be termed a +method of trial and error. Organisms vary incessantly; of these variations +the few meet with surrounding conditions which suit them and thrive; the +many are unsuited and become extinguished. + +According to Teleology, each organism is like a rifle bullet fired straight +at a mark; according to Darwin, organisms are like grapeshot of which one +hits something and the rest fall wide. + +For the teleologist an organism exists because it was made for the +conditions in which it is found; for the Darwinian an organism exists +because, out of many of its kind, it is the only one which has been able to +persist in the conditions in which it is found. + +Teleology implies that the organs of every organism are perfect and cannot +be improved; the Darwinian theory simply affirms that they work well enough +to enable the organism to hold its own against such competitors as it has +met with, but admits the possibility of indefinite improvement. But an +example may bring into clearer light the profound opposition between the +ordinary teleological, and the Darwinian, conception. + +Cats catch mice, small birds and the like, very well. Teleology tells us +that they do so because they were expressly constructed for so doing--that +they are perfect mousing apparatuses, so perfect and so delicately adjusted +that no one of their organs could be altered, without the change involving +the alteration of all the rest. Darwinism affirms on the contrary, that +there was no express construction concerned in the matter; but that among +the multitudinous variations of the Feline stock, many of which died out +from want of power to resist opposing influences, some, the cats, were +better fitted to catch mice than others, whence they throve and persisted, +in proportion to the advantage over their fellows thus offered to them. + +Far from imagining that cats exist _in order_ to catch mice well, +Darwinism supposes that cats exist because they catch mice well--mousing +being not the end, but the condition, of their existence. And if the cat +type has long persisted as we know it, the interpretation of the fact upon +Darwinian principles would be, not that the cats have remained invariable, +but that such varieties as have incessantly occurred have been, on the +whole, less fitted to get on in the world than the existing stock. + +If we apprehend the spirit of the "Origin of Species" rightly, then, +nothing can be more entirely and absolutely opposed to Teleology, as it is +commonly understood, than the Darwinian Theory. So far from being a +"Teleologist in the fullest sense of the word," we should deny that he is a +Teleologist in the ordinary sense at all; and we should say that, apart +from his merits as a naturalist, he has rendered a most remarkable service +to philosophical thought by enabling the student of Nature to recognise, to +their fullest extent, those adaptations to purpose which are so striking in +the organic world, and which Teleology has done good service in keeping +before our minds, without being false to the fundamental principles of a +scientific conception of the universe. The apparently diverging teachings +of the Teleologist and of the Morphologist are reconciled by the Darwinian +hypothesis. + +But leaving our own impressions of the "Origin of Species," and turning to +those passages especially cited by Professor Kölliker, we cannot admit that +they bear the interpretation he puts upon them. Darwin, if we read him +rightly, does _not_ affirm that every detail in the structure of an +animal has been created for its benefit. His words are (p. 199):-- + +"The foregoing remarks lead me to say a few words on the protest lately +made by some naturalists against the utilitarian doctrine that every detail +of structure has been produced for the good of its possessor. They believe +that very many structures have been created for beauty in the eyes of man, +or for mere variety. This doctrine, if true, would be absolutely fatal to +my theory--yet I fully admit that many structures are of no direct use to +their possessor." + +And after sundry illustrations and qualifications, he concludes (p. 200):-- + +"Hence every detail of structure in every living creature (making some +little allowance for the direct action of physical conditions) may be +viewed either as having been of special use to some ancestral form, or as +being now of special use to the descendants of this form--either directly, +or indirectly, through the complex laws of growth." + +But it is one thing to say, Darwinically, that every detail observed in an +animal's structure is of use to it, or has been of use to its ancestors; +and quite another to affirm, teleologically, that every detail of an +animal's structure has been created for its benefit. On the former +hypothesis, for example, the teeth of the foetal _Baltæna_ have a +meaning; on the latter, none. So far as we are aware, there is not a phrase +in the "Origin of Species" inconsistent with Professor Kölliker's position, +that "varieties arise irrespectively of the notion of purpose, or of +utility, according to general laws of Nature, and may be either useful, or +hurtful, or indifferent." + +On the contrary, Mr. Darwin writes (Summary of Chap. V.):-- + +"Our ignorance of the laws of variation is profound. Not in one case out of +a hundred can we pretend to assign any reason why this or that part varies +more or less from the same part in the parents... The external conditions +of life, as climate and food, &c., seem to have induced some slight +modifications. Habit, in producing constitutional differences, and use, in +strengthening, and disuse, in weakening and diminishing organs, seem to +have been more potent in their effects." + +And finally, as if to prevent all possible misconception, Mr. Darwin +concludes his Chapter on Variation with these pregnant words:-- + +"Whatever the cause may be of each slight difference in the offspring from +their parents--and a cause for each must exist--it is the steady +accumulation, through natural selection of such differences, when +beneficial to the individual, that gives rise to all the more important +modifications of structure, by which the innumerable beings on the face of +the earth are enabled to struggle with each other, and the best adapted to +survive." + +We have dwelt at length upon, this subject, because of its great general +importance, and because we believe that Professor Kölliker's criticisms on +this head are based upon a misapprehension of Mr. Darwin's +views--substantially they appear to us to coincide with his own. The other +objections which Professor Kölliker enumerates and discusses are the +following: [Footnote: Space will not allow us to give Professor Kölliker's +arguments in detail; our readers will find a full and accurate version of +them in the _Reader_ for August 13th and 20th, 1864.]-- + +"1. No transitional forms between existing species are known; and known +varieties, whether selected or spontaneous, never go so far as to establish +new species." + +To this Professor Kölliker appears to attach some weight. He makes the +suggestion that the short-faced tumbler pigeon may be a pathological +product. + +"2. No transitional forms of animals are met with among the organic remains +of earlier epochs." + +Upon this, Professor Kölliker remarks that the absence of transitional +forms in the fossil world, though not necessarily fatal to Darwin's views, +weakens his case. + +"3. The struggle for existence does not take place." + +To this objection, urged by Pelzeln, Kölliker, very justly, attaches no +weight. + +"4. A tendency of organisms to give rise to useful varieties, and a natural +selection, do not exist. + +"The varieties which are found arise in consequence of manifold external +influences, and it is not obvious why they all, or partially, should be +particularly useful. Each animal suffices for its own ends, is perfect of +its kind, and needs no further development. Should, however, a variety be +useful and even maintain itself, there is no obvious reason why it should +change any further. The whole conception of the imperfection of organisms +and the necessity of their becoming perfected is plainly the weakest side +of Darwin's Theory, and a _pis aller_ (Nothbehelf) because Darwin +could think of no other principle by which to explain the metamorphoses +which, as I also believe, have occurred." + +Here again we must venture to dissent completely from Professor Kölliker's +conception of Mr. Darwin's hypothesis. It appears to us to be one of the +many peculiar merits of that hypothesis that it involves no belief in a +necessary and continual progress of organisms. + +Again, Mr. Darwin, if we read him aright, assumes no special tendency of +organisms to give rise to useful varieties, and knows nothing of needs of +development, or necessity of perfection. What he says is, in substance: All +organisms vary. It is in the highest degree improbable that any given +variety should have exactly the same relations to surrounding conditions as +the parent stock. In that case it is either better fitted (when the +variation may be called useful), or worse fitted, to cope with them. If +better, it will tend to supplant the parent stock; if worse, it will tend +to be extinguished by the parent stock. + +If (as is hardly conceivable) the new variety is so perfectly adapted to +the conditions that no improvement upon it is possible,--it will persist, +because, though it does not cease to vary, the varieties will be inferior +to itself. + +If, as is more probable, the new variety is by no means perfectly adapted +to its conditions, but only fairly well adapted to them, it will persist, +so long as none of the varieties which it throws off are better adapted +than itself. + +On the other hand, as soon as it varies in a useful way, _i.e._ when +the variation is such as to adapt it more perfectly to its conditions, the +fresh variety will tend to supplant the former. + +So far from a gradual progress towards perfection forming any necessary +part of the Darwinian creed, it appears to us that it is perfectly +consistent with indefinite persistence in one state, or with a gradual +retrogression. Suppose, for example, a return of the glacial epoch and a +spread of polar climatal conditions over the whole globe. The operation of +natural selection under these circumstances would tend, on the whole, to +the weeding out of the higher organisms and the cherishing of the lower +forms of life. Cryptogamic vegetation would have the advantage over +Phanerogamic; _Hydrozoa_ over Corals; _Crustacea_ over +_Insecta_, and _Amphipoda_ and _Isopoda_ over the higher +_Crustacea;_ Cetaceans and Seals over the _Primates_; the +civilisation of the Esquimaux over that of the European. + +"5. Pelzeln has also objected that if the later organisms have proceeded +from the earlier, the whole developmental series, from the simplest to the +highest, could not now exist; in such a case the simpler organisms must +have disappeared." + +To this Professor Kölliker replies, with perfect justice, that the +conclusion drawn by Pelzeln does not really follow from Darwin's premises, +and that, if we take the facts of Paleontology as they stand, they rather +support than oppose Darwin's theory. + +"6. Great weight must be attached to the objection brought forward by +Huxley, otherwise a warm supporter of Darwin's hypothesis, that we know of +no varieties which are sterile with one another, as is the rule among +sharply distinguished animal forms. + +"If Darwin is right, it must be demonstrated that forms may be produced by +selection, which, like the present sharply distinguished animal forms, are +infertile, when coupled with one another, and this has not been done." + +The weight of this objection is obvious; but our ignorance of the +conditions of fertility and sterility, the want of carefully conducted +experiments extending over long series of years, and the strange anomalies +presented by the results of the cross-fertilisation of many plants, should +all, as Mr. Darwin has urged, be taken into account in considering it. + +The seventh objection is that we have already discussed (_supra_ p. +82). + +The eighth and last stands as follows:-- + +"8. The developmental theory of Darwin is not needed to enable us to +understand the regular harmonious progress of the complete series of +organic forms from the simpler to the more perfect. + +"The existence of general laws of Nature explains this harmony, even if we +assume that all beings have arisen separately and independent of one +another. Darwin forgets that inorganic nature, in which there can be no +thought of genetic connexion of forms, exhibits the same regular plan, the +same harmony, as the organic world; and that, to cite only one example, +there is as much a natural system of minerals as of plants and animals." + +We do not feel quite sure that we seize Professor Kölliker's meaning here, +but he appears to suggest that the observation of the general order and +harmony which pervade inorganic nature, would lead us to anticipate a +similar order and harmony in the organic world. And this is no doubt true, +but it by no means follows that the particular order and harmony observed +among them should be that which we see. Surely the stripes of dun horses, +and the teeth of the _foetal_ _Balæna_, are not explained by the +"existence of General laws of Nature." Mr. Darwin endeavours to explain the +exact order of organic nature which exists; not the mere fact that there is +some order. + +And with regard to the existence of a natural system of minerals; the +obvious reply is that there may be a natural classification of any +objects--of stones on a sea-beach, or of works of art; a natural +classification being simply an assemblage of objects in groups, so as to +express their most important and fundamental resemblances and differences. +No doubt Mr. Darwin believes that those resemblances and differences upon +which our natural systems or classifications of animals and plants are +based, are resemblances and differences which have been produced +genetically, but we can discover no reason for supposing that he denies the +existence of natural classifications of other kinds. + +And, after all, is it quite so certain that a genetic relation may not +underlie the classification of minerals? The inorganic world has not always +been what we see it. It has certainly had its metamorphoses, and, very +probably, a long "Entwickelungsgeschichte" out of a nebular blastema. Who +knows how far that amount of likeness among sets of minerals, in virtue of +which they are now grouped into families and orders, may not be the +expression of the common conditions to which that particular patch of +nebulous fog, which may have been constituted by their atoms, and of which +they may be, in the strictest sense, the descendants, was subjected? + +It will be obvious from what has preceded, that we do not agree with +Professor Kölliker in thinking the objections which he brings forward so +weighty as to be fatal to Darwin's view. But even if the case were +otherwise, we should be unable to accept the "Theory of Heterogeneous +Generation" which is offered as a substitute. That theory is thus stated:-- + +"The fundamental conception of this hypothesis is, that, under the +influence of a general law of development, the germs of organisms produce +others different from themselves. This might happen (1) by the fecundated +ova passing, in the course of their development, under particular +circumstances, into higher forms; (2) by the primitive and later organisms +producing other organisms without fecundation, out of germs or eggs +(Parthenogenesis)." + +In favour of this hypothesis, Professor Kölliker adduces the well-known +facts of Agamogenesis, or "alternate generation"; the extreme dissimilarity +of the males and females of many animals; and of the males, females, and +neuters of those insects which live in colonies: and he defines its +relations to the Darwinian theory as follows:-- + +"It is obvious that my hypothesis is apparently very similar to Darwin's, +inasmuch as I also consider that the various forms of animals have +proceeded directly from one another. My hypothesis of the creation of +organisms by heterogeneous generation, however, is distinguished very +essentially from Darwin's by the entire absence of the principle of useful +variations and their natural selection: and my fundamental conception is +this, that a great plan of development lies at the foundation of the origin +of the whole organic world, impelling the simpler forms to more and more +complex developments. How this law operates, what influences determine the +development of the eggs and germs, and impel them to assume constantly new +forms, I naturally cannot pretend to say; but I can at least adduce the +great analogy of the alternation of generations. If a _Bipinnaria_, a +_Brachiolaria_, a _Pluteus_, is competent to produce the +Echinoderm, which is so widely different from it; if a hydroid polype can +produce the higher Medusa; if the vermiform Trematode 'nurse' can develop +within itself the very unlike _Cercaria_, it will not appear +impossible that the egg, or ciliated embryo, of a sponge, for once, under +special conditions, might become a hydroid polype, or the embryo of a +Medusa, an Echinoderm." + +It is obvious, from, these extracts, that Professor Kölliker's hypothesis +is based upon the supposed existence of a close analogy between the +phænomena of Agamogenesis and the production of new species from +pre-existing ones. But is the analogy a real one? We think that it is not, +and, by the hypothesis cannot be. + +For what are the phænomena of Agamogenesis, stated generally? An +impregnated egg develops into a sexless form, A; this gives rise, +non-sexually, to a second form or forms, B, more or less different from A. +B may multiply non-sexually again; in the simpler cases, however, it does +not, but, acquiring sexual characters, produces impregnated eggs from +whence A, once more, arises. + +No case of Agamogenesis is known in which _when A differs widely from +B_, it is itself capable of sexual propagation. No case whatever is +known in which the progeny of B, by sexual generation, is other than a +reproduction of A. + +But if this be a true statement of the nature of the process of +Agamogenesis, how can it enable us to comprehend the production of new +species from already existing ones? Let us suppose Hyænas to have preceded +Dogs, and to have produced the latter in this way. Then the Hyæna will +represent A, and the Dog, B. The first difficulty that presents itself is +that the Hyæna must be non-sexual, or the process will be wholly without +analogy in the world of Agamogenesis. But passing over this difficulty, and +supposing a male and female Dog to be produced at the same time from the +Hyæna stock, the progeny of the pair, if the analogy of the simpler kinds +of Agamogenesis [Footnote: If, on the contrary, we follow the analogy of +the more complex forms of Agamogenesis, such as that exhibited by some +_Trematoda_ and by the _Aphides_, the Hyæna must produce, +non-sexually, a brood of sexless Dogs, from which other sexless Dogs must +proceed. At the end of a certain number of terms of the series, the Dogs +would acquire sexes and generate young; but these young would be, not Dogs, +but Hyænas. In fact, we have demonstrated, in Agamogenetic phænomena, that +inevitable recurrence to the original type, which is asserted to be true of +variations in general, by Mr. Darwin's opponents; and which, if the +assertion could be changed into a demonstration, would, in fact, be fatal +to his hypothesis.] is to be followed, should be a litter, not of puppies, +but of young Hyænas. For the Agamogenetic series is always, as we have +seen, A:B:A:B, &c.; whereas, for the production of a new species, the +series must be A:B:B:B, &c. The production of new species, or genera, is +the extreme permanent divergence from the primitive stock. All known +Agamogenetic processes, on the other hand, end in a complete return to the +primitive stock. How then is the production of new species to be rendered +intelligible by the analogy of Agamogenesis? + +The other alternative put by Professor Kölliker--the passage of fecundated +ova in the course of their development into higher forms--would, if it +occurred, be merely an extreme case of variation in the Darwinian sense, +greater in degree than, but perfectly similar in kind to, that which +occurred when the well-known Ancon Ram was developed from an ordinary Ewe's +ovum. Indeed we have always thought that Mr. Darwin has unnecessarily +hampered himself by adhering so strictly to his favourite "Natura non facit +saltum." We greatly suspect that she does make considerable jumps in the +way of variation now and then, and that these saltations give rise to some +of the gaps which appear to exist in the series of known forms. + +Strongly and freely as we have ventured to disagree with Professor +Kölliker, we have always done so with regret, and we trust without +violating that respect which is due, not only to his scientific eminence +and to the careful study which he has devoted to the subject, but to the +perfect fairness of his argumentation, and the generous appreciation of the +worth of Mr. Darwin's labours which he always displays. It would be +satisfactory to be able to say as much for M. Flourens. + +But the Perpetual Secretary of the French Academy of Sciences deals with +Mr. Darwin as the first Napoleon would have treated an "idéologue;" and +while displaying a painful weakness of logic and shallowness of +information, assumes a tone of authority, which always touches upon the +ludicrous, and sometimes passes the limits of good breeding. + +For example (p. 56):-- + +"M. Darwin continue: 'Aucune distinction absolue n'a été et ne peut être +établie entre les espèces et les variétés.' Je vous ai déjà dit que vous +vous trompiez; une distinction absolue sépare les variétés d'avec les +espèces." + +"_Je vous ai déjà dit_; moi, M. le Secrétaire perpétuel de l'Académie +des Sciences: et vous + + "'Qui n'êtes rien, + Pas même Académicien;' + +what do you mean by asserting the contrary?" Being devoid of the blessings +of an Academy in England, we are unaccustomed to see our ablest men treated +in this fashion, even by a "Perpetual Secretary." + +Or again, considering that if there is any one quality of Mr. Darwin's work +to which friends and foes have alike borne witness, it is his candour and +fairness in admitting and discussing objections, what is to be thought of +M. Flourens' assertion, that + +"M. Darwin ne cite que les auteurs qui partagent ses opinions." (P. 40.) + +Once more (p. 65):-- + +"Enfin l'ouvrage de M. Darwin a paru. On ne peut qu'être frappé du talent +de l'auteur. Mais quo d'idées obscures, que d'idées fausses! Quel jargon +métaphysique jeté mal à propos dans l'histoire naturelle, qui tombe dans le +galimatias dès qu'elle sort des idées claires, des idées justes! Quel +langage prétentieux et vide! Quelles personnifications puériles et +surannées! O lucidité! 0 solidité de l'esprit Français, que devenez-vous?" + +"Obscure ideas," "metaphysical jargon," "pretentious and empty language," +"puerile and superannuated personifications." Mr. Darwin has many and hot +opponents on this side of the Channel and in Germany, but we do not +recollect to have found precisely these sins in the long catalogue of those +hitherto laid to his charge. It is worth while, therefore, to examine into +these discoveries effected solely by the aid of the "lucidity and solidity" +of the mind of M. Flourens. + +According to M. Flourens, Mr. Darwin's great error is that he has +personified Nature (p. 10), and further that he has + +"imagined a natural selection: he imagines afterwards that this power of +selecting (_pouvoir d'élire_) which he gives to Nature is similar to +the power of man. These two suppositions admitted, nothing stops him: he +plays with Nature as he likes, and makes her do all he pleases." (P. 6.) + +And this is the way M. Flourens extinguishes natural selection: + +"Voyons donc encore une fois, ce qu'il peut y avoir de fondé dans ce qu'on +nomme _élection naturelle_. + +"_L'élection naturelle_ n'est sous un autre nom que la nature. Pour un +être organisé, la nature n'est que l'organisation, ni plus ni moins. + +"Il faudra donc aussi personnifier _l'organisation,_ et dire que +_l'organisation_ choisit _l'organisation. L'élection naturelle_ +est cette _forme substantielle_ dont on jouait autrefois avec tant de +facilité. Aristote disait que 'Si l'art de bâtir était dans le bois, cet +art agirait comme la nature.' A la place de _l'art de bâtir_ M. Darwin +met _l'élection naturelle,_ et c'est tout un: l'un n'est pas plus +chimérique que l'autre." (P. 31.) + +And this is really all that M. Flourens can make of Natural Selection. We +have given the original, in fear lest a translation should be regarded as a +travesty; but with the original before the reader, we may try to analyse +the passage. "For an organised being, Nature is only organisation, neither +more nor less." + +Organised beings then have absolutely no relation to inorganic nature: a +plant does not depend on soil or sunshine, climate, depth in the ocean, +height above it; the quantity of saline matters in water have no influence +upon animal life; the substitution of carbonic acid for oxygen in our +atmosphere would hurt nobody! That these are absurdities no one should know +better than M. Flourens; but they are logical deductions from the assertion +just quoted, and from the further statement that natural selection means +only that "organisation chooses and selects organisation." + +For if it be once admitted (what no sane man denies) that the chances of +life of any given organism are increased by certain conditions (A) and +diminished by their opposites (B), then it is mathematically certain that +any change of conditions in the direction of (A) will exercise a selective +influence in favour of that organism, tending to its increase and +multiplication, while any change in the direction of (B) will exercise a +selective influence against that organism, tending to its decrease and +extinction. + +Or, on the other hand, conditions remaining the same, let a given organism +vary (and no one doubts that they do vary) in two directions: into one form +(_a_) better fitted to cope with these conditions than the original +stock, and a second (_b_) less well adapted to them. Then it is no +less certain that the conditions in question must exercise a selective +influence in favour of (_a_) and against (_b_), so that +(_a_) will tend to predominance, and (_b_) to extirpation. + +That M. Flourens should be unable to perceive the logical necessity of +these simple arguments, which lie at the foundation of all Mr. Darwin's +reasoning; that he should confound an irrefragable deduction from the +observed relations of organisms to the conditions which lie around them, +with a metaphysical "forme substantielle," or a chimerical personification +of the powers of Nature, would be incredible, were it not that other +passages of his work leave no room for doubt upon the subject. + +"On imagine une _élection naturelle_ que, pour plus de ménagement, on +me dit être _inconsciente_, sans s'apercevoir que le contresens +littéral est précisément là: _élection inconsciente_." (P. 52.) + +"J'ai déjà dit ce qu'il faut penser de _l'élection naturelle_. Ou +_l'élection naturelle_ n'est rien, ou c'est la nature: mais la nature +douée _d'élection_, mais la nature personnifiée: dernière erreur du +dernier siècle: Le XIXe ne fait plus de personnifications." (P. 53.) + +M. Flourens cannot imagine an unconscious selection--it is for him a +contradiction in terms. Did M. Flourens ever visit one of the prettiest +watering-places of "la belle France," the Baie d'Arcachon? If so, he will +probably have passed through the district of the Landes, and will have had +an opportunity of observing the formation of "dunes" on a grand scale. What +are these "dunes"? The winds and waves of the Bay of Biscay have not much +consciousness, and yet they have with great care "selected," from among an +infinity of masses of silex of all shapes and sizes, which have been +submitted to their action, all the grains of sand below a certain size, and +have heaped them by themselves over a great area. This sand has been +"unconsciously selected" from amidst the gravel in which it first lay with +as much precision as if man had "consciously selected" it by the aid of a +sieve. Physical Geology is full of such selections--of the picking out of +the soft from the hard, of the soluble from the insoluble, of the fusible +from the infusible, by natural agencies to which we are certainly not in +the habit of ascribing consciousness. + +But that which wind and sea are to a sandy beach, the sum of influences, +which we term the "conditions of existence," is to living organisms. The +weak are sifted out from the strong. A frosty night "selects" the hardy +plants in a plantation from among the tender ones as effectually as if it +were the wind, and they, the sand and pebbles, of our illustration; or, on +the other hand, as if the intelligence of a gardener had been operative in +cutting the weaker organisms down. The thistle, which has spread over the +Pampas, to the destruction of native plants, has been more effectually +"selected" by the unconscious operation of natural conditions than if a +thousand agriculturists had spent their time in sowing it. + +It is one of Mr. Darwin's many great services to Biological science that he +has demonstrated the significance of these facts. He has shown that given +variation and given change of conditions the inevitable result is the +exercise of such an influence upon organisms that one is helped and another +is impeded; one tends to predominate, another to disappear; and thus the +living world bears within itself, and is surrounded by, impulses towards +incessant change. + +But the truths just stated are as certain as any other physical laws, quite +independently of the truth, or falsehood, of the hypothesis which Mr. +Darwin has based upon them; and that Mr. Flourens, missing the substance +and grasping at a shadow, should be blind to the admirable exposition of +them, which Mr. Darwin has given, and see nothing there but a "dernière +erreur du dernier siècle"--a personification of Nature--leads us indeed to +cry with him: "O lucidité! O solidité de l'esprit Français, que +devenez-vous?" + +M. Flourens has, in fact, utterly failed to comprehend the first principles +of the doctrine which he assails so rudely. His objections to details are +of the old sort, so battered and hackneyed on this side of the Channel, +that not even a Quarterly Reviewer could be induced to pick them up for the +purpose of pelting Mr. Darwin over again. We have Cuvier and the mummies; +M. Roulin and the domesticated animals of America; the difficulties +presented by hybridism and by Palæontology; Darwinism a +_rifacciamento_ of De Maillet and Lamarck; Darwinism a system without +a commencement, and its author bound to believe in M. Pouchet, &c. &c. How +one knows it all by heart, and with what relief one reads at p. 65-- + +"Je laisse M. Darwin!" + +But we cannot leave M. Flourens without calling our readers' attention to +his wonderful tenth chapter, "De la Préexistence des Germes et de +l'Epigénèse," which opens thus:-- + +"Spontaneous generation is only a chimaera. This point established, two +hypotheses remain: that of _pre-existence_ and that of +_epigenesis_. The one of these hypotheses has as little foundation as +the other." (p. 163.) + +"The doctrine of _epigenesis_ is derived from Harvey: following by +ocular inspection the development of the new being in the Windsor does, he +saw each part appear successively, and taking the moment of +_appearance_ for the moment of _formation_ he imagined +_epigenesis_." (p. 165.) + +On the contrary, says M. Flourens (p. 167), + +"The new being is formed at a stroke (_tout d'un coup_), as a whole, +instantaneously; it is not formed part by part, and at different times. It +is formed at once at the single _individual_ moment at which the +conjunction of the male and female elements takes place." + +It will be observed that M. Flourens uses language which cannot be +mistaken. For him, the labours of Von Baer, of Rathke, of Coste, and their +contemporaries and successors in Germany, France, and England, are +non-existent: and, as Darwin "_imagina_" natural selection, so Harvey +"_imagina_" that doctrine which gives him an even greater claim to the +veneration of posterity than his better known discovery of the circulation +of the blood. + +Language such as that we have quoted is, in fact, so preposterous, so +utterly incompatible with anything but absolute ignorance of some of the +best established facts, that we should have passed it over in silence had +it not appeared to afford some clue to M. Flourens' unhesitating, _ à +priori_, repudiation of all forms of the doctrine of progressive +modification of living beings. He whose mind remains uninfluenced by an +acquaintance with the phænomena of development, must indeed lack one of the +chief motives towards the endeavour to trace a genetic relation between the +different existing forms of life. Those who are ignorant of Geology, find +no difficulty in believing that the world was made as it is; and the +shepherd, untutored in history, sees no reason to regard the green mounds +which indicate the site of a Roman camp as aught but part and parcel of the +primæval hillside. So M. Flourens, who believes that embryos are formed +"tout d'un coup," naturally finds no difficulty in conceiving that species +came into existence in the same way. + + + + +IV + +THE GENEALOGY OF ANIMALS [Footnote: _The Natural History of Creation_. +By Dr. Ernst Haeckel. [_Natürliche Schöpfungs-Geschichte_.--Von Dr. +Ernst Haeckel, Professor an der Universität Jena.] Berlin, 1868.] + +[1869] + + +Considering that Germany now takes the lead of the world in scientific +investigation, and particularly in biology, Mr. Darwin must be well pleased +at the rapid spread of his views among some of the ablest and most +laborious of German naturalists. + +Among these, Professor Haeckel, of Jena, is the Coryphæus. I know of no +more solid and important contributions to biology in the past seven years +than Haeckel's work on the "Radiolaria," and the researches of his +distinguished colleague Gegenbaur, in vertebrate anatomy; while in +Haeckel's "Generelle Morphologie" there is all the force, suggestiveness, +and, what I may term the systematising power, of Oken, without his +extravagance. The "Generelle Morphologie" is, in fact, an attempt to put +the Doctrine of Evolution, so far as it applies to the living world, into a +logical form; and to work out its practical applications to their final +results. The work before, us, again, may be said to be an exposition of the +"Generelle Morphologie" for an educated public, consisting, as it does, of +the substance of a series of lectures delivered before a mixed audience at +Jena, in the session 1867-8. + +"The Natural History of Creation,"--or, as Professor Haeckel admits it +would have been better to call his work, "The History of the Development or +Evolution of Nature,"--deals, in the first six lectures, with the general +and historical aspects of the question and contains a very interesting and +lucid account of the views of Linnæus, Cuvier, Agassiz, Goethe, Oken, Kant, +Lamarck, Lyell, and Darwin, and of the historical filiation of these +philosophers. + +The next six lectures are occupied by a well-digested statement of Mr. +Darwin's views. The thirteenth lecture discusses two topics which are not +touched by Mr. Darwin, namely, the origin of the present form of the solar +system, and that of living matter. Full justice is done to Kant, as the +originator of that "cosmic gas theory," as the Germans somewhat quaintly +call it, which is commonly ascribed to Laplace. With respect to spontaneous +generation, while admitting that there is no experimental evidence in its +favour, Professor Haeckel denies the possibility of disproving it, and +points out that the assumption that it has occurred is a necessary part of +the doctrine of Evolution. The fourteenth lecture, on "Schöpfungs-Perioden +und Schöpfungs-Urkunden," answers pretty much to the famous disquisition on +the "Imperfection of the Geological Record" in the "Origin of Species." + +The following five lectures contain the most original matter of any, being +devoted to "Phylogeny," or the working out of the details of the process of +Evolution in the animal and vegetable kingdoms, so as to prove the line of +descent of each group of living beings, and to furnish it with its proper +genealogical tree, or "phylum." + +The last lecture considers objections and sums up the evidence in favour of +biological Evolution. + +I shall best testify to my sense of the value of the work thus briefly +analysed if I now proceed to note down some of the more important +criticisms which have been suggested to me by its perusal. + +I. In more than one place, Professor Haeckel enlarges upon the service +which the "Origin of Species" has done, in favouring what he terms the +"causal or mechanical" view of living nature as opposed to the +"teleological or vitalistic" view. And no doubt it is quite true that the +doctrine of Evolution is the most formidable opponent of all the commoner +and coarser forms of Teleology. But perhaps the most remarkable service to +the philosophy of Biology rendered by Mr. Darwin is the reconciliation of +Teleology and Morphology, and the explanation of the facts of both which +his views offer. + +The Teleology which supposes that the eye, such as we see it in man or one +of the higher _Vertebrata_, was made with the precise structure which +it exhibits, for the purpose of enabling the animal which possesses it to +see, has undoubtedly received its death-blow. Nevertheless it is necessary +to remember that there is a wider Teleology, which is not touched by the +doctrine of Evolution, but is actually based upon the fundamental +proposition of Evolution. That proposition is, that the whole world, living +and not living, in the result of the mutual interaction, according to +definite laws, of the forces possessed by the molecules of which the +primitive nebulosity of the universe was composed. If this be true, it is +no less certain that the existing world lay, potentially, in the cosmic +vapour; and that a sufficient intelligence could, from a knowledge of the +properties of the molecules of that vapour, have predicted, say the state +of the Fauna of Britain in 1869, with as much certainty as one can say what +will happen to the vapour of the breath in a cold winter's day. + +Consider a kitchen clock, which ticks loudly, shows the hours, minutes, and +seconds, strikes, cries "cuckoo!" and perhaps shows the phases of the moon. +When the clock is wound up, all the phenomena which it exhibits are +potentially contained in its mechanism, and a clever clockmaker could +predict all it will do after an examination of its structure. + +If the evolution theory is correct, the molecular structure of the cosmic +gas stands in the same relation to the phenomena of the world as the +structure of the clock to its phenomena. + +Now let us suppose a death-watch, living in the clock-case, to be a learned +and intelligent student of its works. He might say, "I find here nothing +but matter and force and pure mechanism from beginning to end," and he +would be quite right. But if he drew the conclusion that the clock was not +contrived for a purpose, he would be quite wrong. On the other hand, +imagine another death-watch of a different turn of mind. He, listening to +the monotonous "tick! tick!" so exactly like his own, might arrive at the +conclusion that the clock was itself a monstrous sort of death-watch, and +that its final cause and purpose was to tick. How easy to point to the +clear relation of the whole mechanism to the pendulum, to the fact that the +one thing the clock did always and without intermission was to tick, and +that all the rest of its phenomena were intermittent and subordinate to +ticking! For all this, it is certain that kitchen clocks are not contrived +for the purpose of making a ticking noise. + +Thus the teleological theorist would be as wrong as the mechanical +theorist, among our death-watches; and, probably, the only death-watch who +would be right would be the one who should maintain that the sole thing +death-watches could be sure about was the nature of the clock-works and the +way they move; and that the purpose of the clock lay wholly beyond the +purview of beetle faculties. + +Substitute "cosmic vapour" for "clock," and "molecules" for "works," and +the application of the argument is obvious. The teleological and the +mechanical views of nature are not, necessarily, mutually exclusive. On the +contrary, the more purely a mechanist the speculator is, the more firmly +does he assume a primordial molecular arrangement, of which all the +phenomena of the universe are the consequences; and the more completely is +he thereby at the mercy of the teleologist, who can always defy him to +disprove that this primordial molecular arrangement was not intended to +evolve the phenomena of the universe. On the other hand, if the teleologist +assert that this, that, or the other result of the working of any part of +the mechanism of the universe is its purpose and final cause, the mechanist +can always inquire how he knows that it is more than an unessential +incident--the mere ticking of the clock, which he mistakes for its +function. And there seems to be no reply to this inquiry, any more than to +the further, not irrational, question, why trouble one's self about matters +which are out of reach, when the working of the mechanism itself, which is +of infinite practical importance, affords scope for all our energies? + +Professor Haeckel has invented a new and convenient name "Dysteleology," +for the study of the "purposelessnesses" which are observable in living +organisms--such as the multitudinous cases of rudimentary and apparently +useless structures. I confess, however, that it has often appeared to me +that the facts of Dysteleology cut two ways. If we are to assume, as +evolutionists in general do, that useless organs atrophy, such cases as the +existence of lateral rudiments of toes, in the foot of a horse, place us in +a dilemma. For, either these rudiments are of no use to the animal, in +which case, considering that the horse has existed in its present form +since the Pliocene epoch, they surely ought to have disappeared; or they +are of some use to the animal, in which case they are of no use as +arguments against Teleology. A similar, but still stronger, argument may be +based upon the existence of teats, and even functional mammary glands, in +male mammals. Numerous cases of "Gynæcomasty," or functionally active +breasts in men, are on record, though there is no mammalian species +whatever in which the male normally suckles the young. Thus, there can be +little doubt that the mammary gland was as apparently useless in the +remotest male mammalian ancestor of man as in living men, and yet it has +not disappeared. Is it then still profitable to the male organism to retain +it? Possibly; but in that case its dysteleological value is gone. +[Footnote: The recent discovery of the important part played by the Thyroid +gland should be a warning to all speculators about useless organs. 1893.] + +II. Professor Haeckel looks upon the causes which have led to the present +diversity of living nature as twofold. Living matter, he tells us, is urged +by two impulses: a centripetal, which tends to preserve and transmit the +specific form, and which he identifies with heredity; and a centrifugal, +which results from the tendency of external conditions to modify the +organism and effect its adaptation to themselves. The internal impulse is +conservative, and tends to the preservation of specific, or individual, +form; the external impulse is metamorphic, and tends to the modification of +specific, or individual, form. + +In developing his views upon this subject, Professor Haeckel introduces +qualifications which disarm some of the criticisms I should have been +disposed to offer; but I think that his method of stating the case has the +inconvenience of tending to leave out of sight the important fact--which is +a cardinal point in the Darwinian hypothesis--that the tendency to vary, in +a given organism, may have nothing to do with the external conditions to +which that individual organism is exposed, but may depend wholly upon +internal conditions. No one, I imagine, would dream of seeking for the +cause of the development of the sixth finger and toe in the famous Maltese, +in the direct influence of the external conditions of his life. + +I conceive that both hereditary transmission and adaptation need to be +analysed into their constituent conditions by the further application of +the doctrine of the Struggle for Existence. It is a probable hypothesis, +that what the world is to organisms in general, each organism is to the +molecules of which it is composed. Multitudes of these, having diverse +tendencies, are competing with one another for opportunity to exist and +multiply; and the organism, as a whole, is as much the product of the +molecules which are victorious as the Fauna, or Flora, of a country is the +product of the victorious organic beings in it. + +On this hypothesis, hereditary transmission is the result of the victory of +particular molecules contained in the impregnated germ. Adaptation to +conditions is the result of the favouring of the multiplication of those +molecules whose organising tendencies are most in harmony with such +conditions. In this view of the matter, conditions are not actively +productive, but are passively permissive; they do not cause variation in +any given direction, but they permit and favour a tendency in that +direction which already exists. + +It is true that, in the long run, the origin of the organic molecules +themselves, and of their tendencies, is to be sought in the external world; +but if we carry our inquiries as far back as this, the distinction between +internal and external impulses vanishes. On the other hand, if we confine +ourselves to the consideration of a single organism, I think it must be +admitted that the existence of an internal metamorphic tendency must be as +distinctly recognised as that of an internal conservative tendency; and +that the influence of conditions is mainly, if not wholly, the result of +the extent to which they favour the one, or the other, of these tendencies. + +III. There is only one point upon which I fundamentally and entirely +disagree with Professor Haeckel, but that is the very important one of his +conception of geological time, and of the meaning of the stratified rocks +as records and indications of that time. Conceiving that the stratified +rocks of an epoch indicate a period of depression, and that the intervals +between the epochs correspond with periods of elevation of which we have no +record, he intercalates between the different epochs, or periods, intervals +which he terms "Ante-periods." Thus, instead of considering the Triassic, +Jurassic, Cretaceous, and Eocene periods, as continuously successive, he +interposes a period before each, as an "Antetrias-zeit," "Antejura-zeit," +"Antecreta-zeit," "Anteo-cenzeit," &c. And he conceives that the abrupt +changes between the Faunæ of the different formations are due to the lapse +of time, of which we have no organic record, during their "Ante-periods." + +The frequent occurrence of strata containing assemblages of organic forms +which are intermediate between those of adjacent formations, is, to my +mind, fatal to this view. In the well-known St. Cassian beds, for example, +Palaeozoic and Mesozoic forms are commingled, and, between the Cretaceous +and the Eocene formations, there are similar transitional beds. On the +other hand, in the middle of the Silurian series, extensive unconformity of +the strata indicates the lapse of vast intervals of time between the +deposit of successive beds, without any corresponding change in the Fauna. + +Professor Haeckel will, I fear, think me unreasonable, if I say that he +seems to be still overshadowed by geological superstitions; and that he +will have to believe in the completeness of the geological record far less +than he does at present. He assumes, for example, that there was no dry +land, nor any terrestrial life, before the end of the Silurian epoch, +simply because, up to the present time, no indications of fresh water, or +terrestrial organisms, have been found in rocks of older date. And, in +speculating upon the origin of a given group, he rarely goes further back +than the "Ante-period," which precedes that in which the remains of animals +belonging to that group are found. Thus, as fossil remains of the majority +of the groups of _Reptilia_ are first found in the Trias, they are +assumed to have originated in the "Antetriassic" period, or between the +Permian and Triassic epochs. + +I confess this is wholly incredible to me. The Permian and the Triassic +deposits pass completely into one another; there is no sort of +discontinuity answering to an unrecorded "Antetrias"; and, what is more, we +have evidence of immensely extensive dry land during the formation of these +deposits. We know that the dry land of the Trias absolutely teemed with +reptiles of all groups except Pterodactyles, Snakes, and perhaps Tortoises; +there is every probability that true Birds existed, and _Mammalia_ +certainly did. Of the inhabitants of the Permian dry land, on the contrary, +all that have left a record are a few lizards. Is it conceivable that these +last should really represent the whole terrestrial population of that time, +and that the development of Mammals, of Birds, and of the highest forms of +Reptiles, should have been crowded into the time during which the Permian +conditions quietly passed away, and the Triassic conditions began? Does not +any such supposition become in the highest degree improbable, when, in the +terrestrial or fresh-water Labyrinthodonts, which lived on the land of the +Carboniferous epoch, as well as on that of the Trias, we have evidence that +one form of terrestrial life persisted, throughout all these ages, with no +important modification? For my part, having regard to the small amount of +modification (except in the way of extinction) which the Crocodilian, +Lacertilian, and Chelonian _Reptilia_ have undergone, from the older +Mesozoic times to the present day, I cannot but put the existence of the +common stock from which they sprang far back in the Palæozoic epoch; and I +should apply a similar argumentation to all other groups of animals. + +[The remainder of this essay contains a discussion of questions of taxonomy +and phylogeny, which is now antiquated. I have reprinted the considerations +about the reconciliation of Teleology with Morphology, about +"Dysteleology," and about the struggle for existence within the organism, +because it has happened to me to be charged with overlooking them. + +In discussing Teleology, I ought to have pointed out, as I have done +elsewhere (_Life and Letters of Charles Darwin_, vol. ii. p. 202), +that Paley "proleptically accepted the modern doctrine of Evolution," +(_Natural Theology_, chap. xxiii.). 1893.] + + + + +V + +MR. DARWIN'S CRITICS [Footnote: _Contributions to the Theory of Natural +Selection_. By A. R. Wallace. 1870.--2. _The Genesis of Species_. +By St. George Mivart, F.R.S. Second Edition. 1871.--3. _Darwin's Descent +of Man_. Quarterly Review, July 1871.] + +[1871] + + +The gradual lapse of time has now separated us by more than a decade from +the date of the publication of the "Origin of Species"--and whatever may be +thought or said about Mr. Darwin's doctrines, or the manner in which he has +propounded them, this much is certain, that, in a dozen years, the "Origin +of Species" has worked as complete a revolution in biological science as +the "Principia" did in astronomy--and it has done so, because, in the words +of Helmholtz, it contains "an essentially new creative thought." [Footnote: +Helmholtz: _Ueber das Ziel und die Fortschritte der +Naturwissenschaft_. Eröffnungsrede für die Naturforscherversammlung zu +Innsbruck. 1869.] And as time has slipped by, a happy change has come over +Mr. Darwin's critics. The mixture of ignorance and insolence which, at +first, characterised a large proportion of the attacks with which he was +assailed, is no longer the sad distinction of anti-Darwinian criticism. +Instead of abusive nonsense, which merely discredited its writers, we read +essays, which are, at worst, more or less intelligent and appreciative; +while, sometimes, like that which appeared in the "North British Review" +for 1867, they have a real and permanent value. + +The several publications of Mr. Wallace and Mr. Mivart contain discussions +of some of Mr. Darwin's views, which are worthy of particular attention, +not only on account of the acknowledged scientific competence of these +writers, but because they exhibit an attention to those philosophical +questions which underlie all physical science, which is as rare as it is +needful. And the same may be said of an article in the "Quarterly Review" +for July 1871, the comparison of which with an article in the same Review +for July 1860, is perhaps the best evidence which can be brought forward of +the change which has taken place in public opinion on "Darwinism." + +The Quarterly Reviewer admits "the certainty of the action of natural +selection" (p. 49); and further allows that there is an _à priori_ +probability in favour of the evolution of man from some lower animal form, +if these lower animal forms themselves have arisen by evolution. + +Mr. Wallace and Mr. Mivart go much further than this. They are as stout +believers in evolution as Mr. Darwin himself; but Mr. Wallace denies that +man can have been evolved from a lower animal by that process of natural +selection which he, with Mr. Darwin, holds to have been sufficient for the +evolution of all animals below man; while Mr. Mivart, admitting that +natural selection has been one of the conditions of the evolution of the +animals below man, maintains that natural selection must, even in their +case, have been supplemented by "some other cause"--of the nature of which, +unfortunately, he does not give us any idea. Thus Mr. Mivart is less of a +Darwinian than Mr. Wallace, for he has less faith in the power of natural +selection. But he is more of an evolutionist than Mr. Wallace, because Mr. +Wallace thinks it necessary to call in an intelligent agent--a sort of +supernatural Sir John Sebright--to produce even the animal frame of man; +while Mr. Mivart requires no Divine assistance till he comes to man's soul. + +Thus there is a considerable divergence between Mr. Wallace and Mr. Mivart. +On the other hand, there are some curious similarities between Mr. Mivart +and the Quarterly Reviewer, and these are sometimes so close, that, if Mr. +Mivart thought it worth while, I think he might make out a good case of +plagiarism against the Reviewer, who studiously abstains from quoting him. + +Both the Reviewer and Mr. Mivart reproach Mr. Darwin with being, "like so +many other physicists," entangled in a radically false metaphysical system, +and with setting at nought the first principles of both philosophy and +religion. Both enlarge upon the necessity of a sound philosophical basis, +and both, I venture to add, make a conspicuous exhibition of its absence. +The Quarterly Reviewer believes that man "differs more from an elephant or +a gorilla than do these from the dust of the earth on which they tread," +and Mr. Mivart has expressed the opinion that there is more difference +between man and an ape than there is between an ape and a piece of granite. +[Footnote: See the _Tablet_ for March 11, 1871.] + +And even when Mr. Mivart (p. 86) trips in a matter of anatomy, and creates +a difficulty for Mr. Darwin out of a supposed close similarity between the +eyes of fishes and cephalopods, which (as Gegenbaur and others have clearly +shown) does not exist, the Quarterly Reviewer adopts the argument without +hesitation (p. 66). + +There is another important point, however, in which it is hard to say +whether Mr. Mivart diverges from the Quarterly Reviewer or not. + +The Reviewer declares that Mr. Darwin has, "with needless opposition, set +at nought the first principles of both philosophy and religion" (p. 90). + +It looks, at first, as if this meant, that Mr. Darwin's views being false, +the opposition to "religion" which flows from them must be needless. But I +suspect this is not the right view of the meaning of the passage, as Mr. +Mivart, from whom the Quarterly Reviewer plainly draws so much inspiration, +tells us that "the consequences which have been drawn from evolution, +whether exclusively Darwinian or not, to the prejudice of religion, by no +means follow from it, and are in fact illegitimate" (p. 5). + +I may assume, then, that the Quarterly Reviewer and Mr. Mivart admit that +there is no necessary opposition between "evolution whether exclusively +Darwinian or not," and religion. But then, what do they mean by this last +much-abused term? On this point the Quarterly Reviewer is silent. Mr. +Mivart, on the contrary, is perfectly explicit, and the whole tenor of his +remarks leaves no doubt that by "religion" he means theology; and by +theology, that particular variety of the great Proteus, which is expounded +by the doctors of the Roman Catholic Church, and held by the members of +that religious community to be the sole form of absolute truth and of +saving faith. + +According to Mr. Mivart, the greatest and most orthodox authorities upon +matters of Catholic doctrine agree in distinctly asserting "derivative +creation" or evolution; "and thus their teachings harmonise with all that +modern science can possibly require" (p. 305). + +I confess that this bold assertion interested me more than anything else in +Mr. Mivart's book. What little knowledge I possessed of Catholic doctrine, +and of the influence exerted by Catholic authority in former times, had not +led me to expect that modern science was likely to find a warm welcome +within the pale of the greatest and most consistent of theological +organisations. + +And my astonishment reached its climax when I found Mr. Mivart citing +Father Suarez as his chief witness in favour of the scientific freedom +enjoyed by Catholics--the popular repute of that learned theologian and +subtle casuist not being such as to make his works a likely place of refuge +for liberality of thought. But in these days, when Judas Iscariot and +Robespierre, Henry VIII. and Catiline, have all been shown to be men of +admirable virtue, far in advance of their age, and consequently the victims +of vulgar prejudice, it was obviously possible that Jesuit Suarez might be +in like case. And, spurred by Mr. Mivart's unhesitating declaration, I +hastened to acquaint myself with such of the works of the great Catholic +divine as bore upon the question, hoping, not merely to acquaint myself +with the true teachings of the infallible Church, and free myself of an +unjust prejudice; but, haply, to enable myself, at a pinch, to put some +Protestant bibliolater to shame, by the bright example of Catholic freedom +from the trammels of verbal inspiration. + +I regret to say that my anticipations have been cruelly disappointed. But +the extent to which my hopes have been crushed can only be fully +appreciated by citing, in the first place, those passages of Mr. Mivart's +work by which they were excited. In his introductory chapter I find the +following passages:-- + +"The prevalence of this theory [of evolution] need alarm no one, for it is, +without any doubt, perfectly consistent with the strictest and most +orthodox Christian [Footnote: It should be observed that Mr. Mivart employs +the term 'Christian' as if it were the equivalent of 'Catholic.'] theology" +(p. 5). + +"Mr. Darwin and others may perhaps be excused if they have not devoted much +time to the study of Christian philosophy; but they have no right to assume +or accept without careful examination, as an unquestioned fact, that in +that philosophy there is a necessary antagonism between the two ideas +'creation' and 'evolution,' as applied to organic forms. + +"It is notorious and patent to all who choose to seek, that many +distinguished Christian thinkers have accepted, and do accept, both ideas, +_i.e._ both 'creation' and 'evolution.' + +"As much as ten years ago an eminently Christian writer observed: 'The +creationist theory does not necessitate the perpetual search after +manifestations of miraculous power and perpetual "catastrophes." Creation +is not a miraculous interference with the laws of Nature, but the very +institution of those laws. Law and regularity, not arbitrary intervention, +was the patristic ideal of creation. With this notion they admitted, +without difficulty, the most surprising origin of living creatures, +provided it took place by _law_. They held that when God said, "Let +the waters produce," "Let the earth produce," He conferred forces on the +elements of earth and water which enabled them naturally to produce the +various species of organic beings. This power, they thought, remains +attached to the elements throughout all time.' The same writer quotes St. +Augustin and St. Thomas Aquinas, to the effect that, 'in the institution of +Nature, we do not look for miracles, but for the laws of Nature.' And, +again, St. Basil speaks of the continued operation of natural laws in the +production of all organisms. + +"So much for the writers of early and mediæval times. As to the present +day, the author can confidently affirm that there are many as well versed +in theology as Mr. Darwin is in his own department of natural knowledge, +who would not be disturbed by the thorough demonstration of his theory. +Nay, they would not even be in the least painfully affected at witnessing +the generation of animals of complex organisation by the skilful artificial +arrangement of natural forces, and the production, in the future, of a fish +by means analogous to those by which we now produce urea. + +"And this because they know that the possibility of such phenomena, though +by no means actually foreseen, has yet been fully provided for in the old +philosophy centuries before Darwin, or even centuries before Bacon, and +that their place in the system can be at once assigned them without even +disturbing its order or marring its harmony. + +"Moreover, the old tradition in this respect has never been abandoned, +however much it may have been ignored or neglected by some modern writers. +In proof of this, it may be observed that perhaps no post-mediæval +theologian has a wider reception amongst Christians throughout the world +than Suarez, who has a separate section [Footnote: Suarez, +_Metaphysica_. Edition Vivés. Paris, 1868, vol. i Disput. xv. § 2.] in +opposition to those who maintain the distinct creation of the various +kinds--or substantial forms--of organic life" (pp. 19-21). + +Still more distinctly does Mr. Mivart express himself in the same sense, in +his last chapter, entitled "Theology and Evolution" (pp. 302-5). + +"It appears, then, that Christian thinkers are perfectly free to accept the +general evolution theory. But are there any theological authorities to +justify this view of the matter? + +"Now, considering how extremely recent are these biological speculations, +it might hardly be expected _à priori_ that writers of earlier ages +should have given expression to doctrines harmonising in any degree with +such very modern views; nevertheless, this is certainly the case, and it +would be easy to give numerous examples. It will be better, however, to +cite one or two authorities of weight. Perhaps no writer of the earlier +Christian ages could be quoted whose authority is more generally recognised +than that of St. Augustin. The same may be said of the mediæval period for +St. Thomas Aquinas: and since the movement of Luther, Suarez may be taken +as an authority, widely venerated, and one whose orthodoxy has never been +questioned. + +"It must be borne in mind that for a considerable time even after the last +of these writers no one had disputed the generally received belief as to +the small age of the world, or at least of the kinds of animals and plants +inhabiting it. It becomes, therefore, much more striking if views formed +under such a condition of opinion are found to harmonise with modern ideas +concerning 'Creation' and organic Life. + +"Now St. Augustin insists in a very remarkable manner on the merely +derivative sense in which God's creation of organic forms is to be +understood; that is, that God created them by conferring on the material +world the power to evolve them under suitable conditions." + +Mr. Mivart then cites certain passages from St. Augustin, St. Thomas +Aquinas, and Cornelius à Lapide, and finally adds:-- + +"As to Suarez, it will be enough to refer to Disp. xv. sec. 2, No. 9, p. +508, t. i. edition Vivés, Paris; also Nos. 13-15. Many other references to +the same effect could easily be given, but these may suffice. + +"It is then evident that ancient and most venerable theological authorities +distinctly assert derivative creation, and thus their teachings harmonise +with all that modern science can possibly require." + +It will be observed that Mr. Mivart refers solely to Suarez's fifteenth +Disputation, though he adds, "Many other references to the same effect +could easily be given." I shall look anxiously for these references in the +third edition of the "Genesis of Species." For the present, all I can say +is, that I have sought in vain, either in the fifteenth Disputation, or +elsewhere, for any passage in Suarez's writings which, in the slightest +degree, bears out Mr. Mivart's views as to his opinions. [Footnote: The +edition of Suarez's _Disputationes_ from which the following citations +are given, is Birckmann's, in two volumes folio, and is dated 1680.] + +The title of this fifteenth Disputation is "De causa formali substantiali," +and the second section of that Disputation (to which Mr. Mivart refers) is +headed, "Quomodo possit forma substantialis fieri in materia et ex +materia?" + +The problem which Suarez discusses in this place may be popularly stated +thus: According to the scholastic philosophy every natural body has two +components--the one its "matter" (_materia prima_), the other its +"substantial form" (_forma substantialis_). Of these the matter is +everywhere the same, the matter of one body being indistinguishable from +the matter of any other body. That which differentiates any one natural +body from all others is its substantial form, which inheres in the matter +of that body, as the human soul inheres in the matter of the frame of man, +and is the source of all the activities and other properties of the body. + +Thus, says Suarez, if water is heated, and the source of heat is then +removed, it cools again. The reason of this is that there is a certain +"_intimius principium_" in the water, which brings it back to the cool +condition when the external impediment to the existence of that condition +is removed. This _intimius principium_ is the "substantial form" of +the water. And the substantial form of the water is not only the cause +(_radix_) of the coolness of the water, but also of its moisture, of +its density, and of all its other properties. + +It will thus be seen that "substantial forms" play nearly the same part in +the scholastic philosophy as "forces" do in modern science; the general +tendency of modern thought being to conceive all bodies as resolvable into +material particles and forces, in virtue of which last these particles +assume those dispositions and exercise those powers which are +characteristic of each particular kind of matter. + +But the Schoolmen distinguished two kinds of substantial forms, the one +spiritual and the other material. The former division is represented by the +human soul, the _anima rationalis_; and they affirm as a matter, not +merely of reason, but of faith, that every human soul is created out of +nothing, and by this act of creation is endowed with the power of existing +for all eternity, apart from the _materia prima_ of which the +corporeal frame of man is composed. And the _anima rationalis_, once +united with the _materia prima_ of the body, becomes its substantial +form, and is the source of all the powers and faculties of man--of all the +vital and sensitive phenomena which he exhibits--just as the substantial +form of water is the source of all its qualities. + +The "material substantial forms" are those which inform all other natural +bodies except that of man; and the object of Suarez in the present +Disputation, is to show that the axiom "_ex nihilo nihil fit_," though +not true of the substantial form of man, is true of the substantial forms +of all other bodies, the endless mutations of which constitute the ordinary +course of nature. The origin of the difficulty which he discusses is easily +comprehensible. Suppose a piece of bright iron to be exposed to the air. +The existence of the iron depends on the presence within it of a +substantial form, which is the cause of its properties, _e.g._ +brightness, hardness, weight. But, by degrees, the iron becomes converted +into a mass of rust, which is dull, and soft, and light, and, in all other +respects, is quite different from the iron. As, in the scholastic view, +this difference is due to the rust being informed by a new substantial +form, the grave problem arises, how did this new substantial form come into +being? Has it been created? or has it arisen by the power of natural +causation? If the former hypothesis is correct, then the axiom, "_ex +nihilo nihil fit_," is false, even in relation to the ordinary course of +nature, seeing that such mutations of matter as imply the continual origin +of new substantial forms are occurring every moment. But the harmonisation +of Aristotle with theology was as dear to the Schoolmen, as the smoothing +down the differences between Moses and science is to our Broad Churchmen, +and they were proportionably unwilling to contradict one of Aristotle's +fundamental propositions. Nor was their objection to flying in the face of +the Stagirite likely to be lessened by the fact that such flight landed +them in flat Pantheism. + +So Father Suarez fights stoutly for the second hypothesis; and I quote the +principal part of his argumentation as an exquisite specimen of that speech +which is a "darkening of counsel." + +"13. Secundo de omnibus aliis formis substantialibus [sc. materialibus] +dicendum est non fieri proprie ex nihilo, sed ex potentia præjacentis +materiæ educi: ideoque in effectione harum formarum nil fieri contra illud +axioma, _Ex nihilo nihil fit_, si recte intelligatur. Hæc assertio +sumitur ex Aristotele 1. Physicorum per totum et libro 7. Metaphyss. et ex +aliis auctoribus, quos statim referam. Et declaratur breviter, nam fieri ex +nihilo duo dicit, unum est fieri absolute et simpliciter, aliud est quod +talis effectio fit ex nihilo. Primum propriè dicitur de re subsistente, +quia ejus est fieri, cujus est esse: id autem proprie quod subsistit et +habet esse; nam quod alteri adjacet, potius est quo aliud est. Ex hac ergo +parte, formæ substantiales materiales non fiunt ex nihilo, quia proprie non +fiunt. Atque hanc rationem reddit Divus Thomas 1 parte, quæstione 45, +articulo 8, et quæstione 90, articulo 2, et ex dicendis magis explicabitur. +Sumendo ergo ipsum _fieri_ in hac proprietate et rigore, sic fieri ex +nihilo est fieri secundum se totum, id est nulla sui parte præsupposita, ex +quo fiat. Et hac ratione res naturales dum de novo fiunt, non fiunt ex +nihilo, quia fiunt ex præsupposita materia, ex qua componuntur, et ita non +fiunt, secundum se totæ, sed secundum aliquid sui. Formæ autem harum rerum, +quamvis revera totam suam entitatem de novo accipiant, quam antea non +habebant, quia vero ipsæ non fiunt, ut dictum est, ideo neque ex nihilo +fiunt. Attamen, quia latiori modo sumendo verbum illud _fieri_ negari +non potest: quin forma facta sit, eo modo quo nunc est, et antea non erat, +ut etiam probat ratio dubitandi posita in principio sectionis, ideo +addendum est, sumpto _fieri_ in hac amplitudine, fieri ex nihilo non +tamen negare habitudinem materialis causæ intrinsecè componentis id quod +fit, sed etiam habitudinem causæ materialis per se causantis et +sustentantis formam quæ fit, seu confit. Diximus enim in superioribus +materiam et esse causam compositi et formæ dependentis ab illa: ut res ergo +dicatur ex nihilo fieri uterque modus causalitatis negari debet; et eodem +sensu accipiendum est illud axioma, ut sit verum: _Ex nihilo nihil +fit_, scilicet virtute agentis naturalis et finiti nihil fieri, nisi ex +præsupposito subjecto per se concurrente, et ad compositum et ad formam, si +utrumque suo modo ab eodem agente fiat. Ex his ergo rectè concluditur, +formas substantiales materiales non fieri ex nihilo, quia fiunt ex materia, +quæ in suo genere per se concurrit, et influit ad esse, et fieri talium +formarum; quia, sicut esse non possunt nisi affixae materiæ, a qua +sustententur in esse: ita nec fieri possunt, nisi earum effectio et +penetratio in eadem materia sustentetur. Et hæc est propria et per se +differentia inter effectionem ex nihilo, et ex aliquo, propter quam, ut +infra ostendemus, prior modus efficiendi superat vim finitam naturaliam +agentium, non vero posterior. + +"14. Ex his etiam constat, proprie de his formis dici non creari, sed educi +de potentia materiæ." [Footnote: Suarez, _loc. cit._ Disput. xv. § +ii.] + +If I may venture to interpret these hard sayings, Suarez conceives that the +evolution of substantial forms in the ordinary course of nature, is +conditioned not only by the existence of the _materia prima_, but also +by a certain "concurrence and influence" which that _materia_ exerts; +and every new substantial form being thus conditioned, and in part, at any +rate, caused, by a pre-existing something, cannot be said to be created out +of nothing. + +But as the whole tenor of the context shows, Suarez applies this +argumentation merely to the evolution of material substantial forms in the +ordinary course of nature. How the substantial forms of animals and plants +primarily originated, is a question to which, so far as I am able to +discover, he does not so much as allude in his "Metaphysical Disputations." +Nor was there any necessity that he should do so, inasmuch as he has +devoted a separate treatise of considerable bulk to the discussion of all +the problems which arise out of the account of the Creation which is given +in the Book of Genesis. And it is a matter of wonderment to me that Mr. +Mivart, who somewhat sharply reproves "Mr. Darwin and others" for not +acquainting themselves with the true teachings of his Church, should allow +himself to be indebted to a heretic like myself for a knowledge of the +existence of that "Tractatus de opere sex Dierum," [Footnote: _Tractatus +de opere sex Dierum, seu de Universi Creatione, quatenus sex diebus +perfecta esse, in libro Genesis cap. i. refertur, et praesertim de +productione hominis in statu innocentiae._ Ed. Birckmann, 1622.] in +which the learned Father, of whom he justly speaks, as "an authority widely +venerated, and whose orthodoxy has never been questioned," directly opposes +all those opinions for which Mr. Mivart claims the shelter of his +authority. + +In the tenth and eleventh chapters of the first book of this treatise, +Suarez inquires in what sense the word "day," as employed in the first +chapter of Genesis, is to be taken. He discusses the views of Philo and of +Augustin on this question, and rejects them. He suggests that the approval +of their allegorising interpretations by St. Thomas Aquinas, merely arose +out of St. Thomas's modesty, and his desire not to seem openly to +controvert St. Augustin--"voluisse Divus Thomas pro sua modestia +subterfugere vim argumenti potius quam aperte Augustinum inconstantiæ +arguere." + +Finally, Suarez decides that the writer of Genesis meant that the term +"day" should be taken in its natural sense; and he winds up the discussion +with the very just and natural remark that "it is not probable that God, in +inspiring Moses to write a history of the Creation which was to be believed +by ordinary people, would have made him use language, the true meaning of +which it is hard to discover, and still harder to believe." [Footnote: +"Propter hæc ergo sententia illa Augustini et propter nimiam obscuritatem +et subtilitatem ejus difficilis creditu est: quia verisimile non est Deum +inspirasse Moysi, ut historiam de creatione mundi ad fidem totius populi +adeo necessariam per nomina dierum explicaret, quorum significatio vix +inveniri et difficillime ab aliquo credi posset." (_Loc. cit._ Lib. I. +cap. xi. 42.)] + +And in chapter xii. 3, Suarez further observes:-- + +"Ratio enim retinendi veram significationem diei naturalis est illa +communis, quod verba Scripturæ non sunt ad metaphoras transferenda, nisi +vel necessitas cogit, vel ex ipsa scriptura constet, et maximè in historica +narratione et ad instructionem fidei pertinente: sed hæc ratio non minus +cogit ad intelligendum propriè dierum numerum, quam diei qualitatem, QUIA +NON MINUS UNO MODO QUAM ALIO DESTRUITUR SINCERITAS, IMO ET VERITAS +HISTORIÆ. Secundo hoc valde confirmant alia Scripturæ loca, in quibus hi +sex dies tanquam veri, et inter se distincti commemorantur, ut Exod. 20 +dicitur, _Sex diebus operabis et facies omnia opera tua, septimo autem +die Sabbatum Domini Dei tui est_. Et infra: _Sex enim diebus fecit +Dominus cælum et terram et mare et omnia quæ in eis sunt_, et idem +repetitur in cap. 31. In quibus locis sermonis proprietas colligi potest +tum ex æquiparatione, nam cum dicitur: _sex diebus operabis_, +propriissimè intelligitur: tum quia non est verisimile, potuisse populum +intelligere verba illa in alio sensu, et è contrario incredibile est, Deum +in suis præceptis tradendis illis verbis ad populum fuisse loquutum, quibus +deciperetur, falsum sensum concipiendo, si Deus non per sex veros dies +opera sua fecisset." + +These passages leave no doubt that this great doctor of the Catholic +Church, of unchallenged authority and unspotted orthodoxy, not only +declares it to be Catholic doctrine that the work of creation took place in +the space of six natural days; but that he warmly repudiates, as +inconsistent with our knowledge of the Divine attributes, the supposition +that the language which Catholic faith requires the believer to hold that +God inspired, was used in any other sense than that which He knew it would +convey to the minds of those to whom it was addressed. + +And I think that in this repudiation Father Suarez will have the sympathy +of every man of common uprightness, to whom it is certainly "incredible" +that the Almighty should have acted in a manner which He would esteem +dishonest and base in a man. + +But the belief that the universe was created in six natural days is +hopelessly inconsistent with the doctrine of evolution, in so far as it +applies to the stars and planetary bodies; and it can be made to agree with +a belief in the evolution of living beings only by the supposition that the +plants and animals, which are said to have been created on the third, +fifth, and sixth days, were merely the primordial forms, or rudiments, out +of which existing plants and animals have been evolved; so that, on these +days, plants and animals were not created actually, but only potentially. + +The latter view is that held by Mr. Mivart, who follows St. Augustin, and +implies that he has the sanction of Suarez. But, in point of fact, the +latter great light of orthodoxy takes no small pains to give the most +explicit and direct contradiction to all such imaginations, as the +following passages prove. In the first place, as regards plants, Suarez +discusses the problem:-- + +"_Quomodo herba virens et cætera vegetabilia hoc_ +[_tertio_] _die fuerint producta_. +[Footnote: _Loc. cit._ Lib. II. cap. vii. et viii. 1, 32, 35.] + +"Præcipua enim difficultas hîc est, quam attingit Div. Thomas 1, par. qu. +69, art. 2, an hæc productio plantarum hoc die facta intelligenda sit de +productione ipsarum in proprio esse actuali et formali (ut sic rem +explicerem) vel de productione tantum in semine et in potentia. Nam Divus +Augustinus libro quinto Genes, ad liter. cap. 4 et 5 et libro 8, cap. 3, +posteriorem partem tradit, dicens, terram in hoc die accepisse virtutem +germinandi omnia vegetabilia quasi concepto omnium illorum semine, non +tamen statim vegetabilia omnia produxisse. Quod primo suadet verbis illis +capitis secundi. _In die quo fecit Deus cælum et terram et omne virgultum +agri priusquam germinaret_. Quomodo enim potuerunt virgulta fieri +antequam terra germinaret nisi quia causaliter prius et quasi in radice, +seu in semine facta sunt, et postea in actu producta? Secundo confirmari +potest, quia verbum illud _germinet terra_ optimè exponitur +potestativè ut sic dicam, id est accipiat terra vim germinandi. Sicut in +eodem capite dicitur _crescite et multiplicamini_. Tertio potest +confirmari, quia actualis productio vegetabilium non tam ad opus +creationis, quam ad opus propagationis pertinet, quod postea factum est. Et +hanc sententiam sequitur Eucherius lib. 1, in Gen. cap. 11, et illi faveat +Glossa, interli. Hugo. et Lyran. dum verbum _germinet_ dicto modo +exponunt. NIHILOMINUS CONTRARIA SENTENTIA TENENDA EST: SCILICET, PRODUXISSE +DEUM HOC DIE HERBAM, ARBORES, ET ALIA VEGETABILIA ACTU IN PROPRIA SPECIE ET +NATURA. Hæc est communis sententia Patrum.--Basil. homil. 5; Exæmer. +Ambros. lib. 3; Exæmer. cap. 8, 11, et 16; Chrysost. homil. 5 in Gen. +Damascene. lib. 2 de Fid. cap. 10; Theodor. Cyrilli. Bedæ, Glossæ ordinariæ +et aliorum in Gen. Et idem sentit Divus Thomas, _supra_, solvens +argumenta Augustini, quamvis propter reverentiam ejus quasi problematicè +semper procedat. Denique idem sentiunt omnes qui in his operibus veram +successionem et temporalem distinctionem agnoscant." + +Secondly, with respect to animals, Suarez is no less decided:-- + +"_De animalium ratione carentium productione quinto et sexto die +facta_. [Footnote: _Loc. cit_. Lib. II. cap. vii. et viii. 1, 32, +35.] + +"32. Primo ergo nobis certum sit hæc animantia non in virtute tantum aut in +semine, sed actu, et in seipsis, facta fuisse his diebus in quibus facta +narrantur. Quanquam Augustinus lib. 3, Gen. ad liter, cap. 5 in sua +persistens sententia contrarium sentire videatur." + +But Suarez proceeds to refute Augustin's opinions at great length, and his +final judgment may be gathered from the following passage:-- + +"35. Tertio dicendum est, hæc animalia omnia his diebus producta esse, IN +PERFECTO STATU, IN SINGULIS INDIVIDUIS, SEU SPECIEBUS SUIS, JUXTA +UNIUSCUJUSQUE NATURAM.... ITAQUE FUERUNT OMNIA CREATA INTEGRA ET OMNIBUS +SUIS MEMBRIS PERFECTA." + +As regards the creation of animals and plants, therefore, it is clear that +Suarez, so far from "distinctly asserting derivative creating," denies it +as distinctly and positively as he can; that he is at much pains to refute +St. Augustin's opinions; that he does not hesitate to regard the faint +acquiescence of St. Thomas Aquinas in the views of his brother saint as a +kindly subterfuge on the part of Divus Thomas; and that he affirms his own +view to be that which is supported by the authority of the Fathers of the +Church. So that, when Mr. Mivart tells us that Catholic theology is in +harmony with all that modern science can possibly require; that "to the +general theory of evolution, and to the special Darwinian form of it, no +exception ... need be taken on the ground of orthodoxy;" and that "law and +regularity, not arbitrary intervention, was the Patristic ideal of +creation," we have to choose between his dictum, as a theologian, and that +of a great light of his Church, whom he himself declares to be "widely +venerated as an authority, and whose orthodoxy has never been questioned." + +But Mr. Mivart does not hesitate to push his attempt to harmonise science +with Catholic orthodoxy to its utmost limit; and, while assuming that the +soul of man "arises from immediate and direct creation," he supposes that +his body was "formed at first (as now in each separate individual) by +derivative, or secondary creation, through natural laws" (p. 331). + +This means, I presume, that an animal, having the corporeal form and bodily +powers of man, may have been developed out of some lower form of life by a +process of evolution; and that, after this anthropoid animal had existed +for a longer or shorter time, God made a soul by direct creation, and put +it into the manlike body, which, heretofore, had been devoid of that +_anima rationalis_, which is supposed to be man's distinctive +character. + +This hypothesis is incapable of either proof or disproof, and therefore may +be true; but if Suarez is any authority, it is not Catholic doctrine. +"Nulla est in homine forma educta de potentia materiæ," [Footnote: Disput. +xv. § x. No. 27.] is a dictum which is absolutely inconsistent with the +doctrine of the natural evolution of any vital manifestation of the human +body. + +Moreover, if man existed as an animal before he was provided with a +rational soul, he must, in accordance with the elementary requirements of +the philosophy in which Mr. Mivart delights, have possessed a distinct +sensitive and vegetative soul, or souls. Hence, when the "breath of life" +was breathed into the manlike animal's nostrils, he must have already been +a living and feeling creature. But Suarez particularly discusses this +point, and not only rejects Mr. Mivart's view, but adopts language of very +theological strength regarding it. + +"Possent præterea his adjungi argumenta theologica, ut est illud quod +sumitur ex illis verbis Genes. 2. _Formavit Deus hominem ex limo terræ et +inspiravit in faciem ejus spiraculum vitæ et factus est homo in animam +viventem_: ille enim spiritus, quam Deus spiravit, anima rationalis +fuit, et PER EADEM FACTUS EST HOMO VIVENS, ET CONSQUENTER, ETIAM SENTIENS. + +"Aliud est ex VIII. Synodo Generali quæ est Constantinopolitana IV. can. +11, qui sic habet. _Apparet quosdam in tantum impietatis venisse ut +homines duas animas habere dogmatizent: talis igitur impietatis inventores +et similes sapientes, cum Vetus et Novum Testamentum omnesque Ecclesiæ +patres unam animam rationalem hominem habere asseverent, Sancta et +universalis Synodus anathematizat_." [FOOTNOTE: Disput. xv. "De causa +formali substantiali," § x. No. 24.] + +Moreover, if the animal nature of man was the result of evolution, so must +that of woman have been. But the Catholic doctrine, according to Suarez, is +that woman was, in the strictest and most literal sense of the words, made +out of the rib of man. + +"Nihilominus sententia Catholica est, verba illa Scripturæ esse ad literam +intelligenda. AC PROINDE VERE, AC REALITER, TULISSE DEUM COSTAM ADAMÆ, ET, +EX ILLA, CORPUS EVÆ FORMASSE." [Footnote: _Tractatus de Opere_, Lib. +III. "De hominis creatione," cap. ii. No. 3.] + +Nor is there any escape in the supposition that some woman existed before +Eve, after the fashion of the Lilith of the rabbis; since Suarez qualifies +that notion, along with some other Judaic imaginations, as simply +"damnabilis." [Footnote: _Ibid_. Lib. III. cap. iv. Nos. 8 and 9] + +After the perusal of the "Tractatus de Opere" it is, in fact, impossible to +admit that Suarez held any opinion respecting the origin of species, except +such as is consistent with the strictest and most literal interpretation of +the words of Genesis. For Suarez, it is Catholic doctrine, that the world +was made in six natural days. On the first of these days the _materia +prima_ was made out of nothing, to receive afterwards those "substantial +forms" which moulded it into the universe of things; on the third day, the +ancestors of all living plants suddenly came into being, full-grown, +perfect, and possessed of all the properties which now distinguish them; +while, on the fifth and sixth days, the ancestors of all existing animals +were similarly caused to exist in their complete and perfect state, by the +infusion of their appropriate material substantial forms into the matter +which had already been created. Finally, on the sixth day, the _anima +rationalis_--that rational and immortal substantial form which is +peculiar to man--was created out of nothing, and "breathed into" a mass of +matter which, till then, was mere dust of the earth, and so man arose. But +the species man was represented by a solitary male individual, until the +Creator took out one of his ribs and fashioned it into a female. + +This is the view of the "Genesis of Species" held by Suarez to be the only +one consistent with Catholic faith: it is because he holds this view to be +Catholic that he does not hesitate to declare St. Augustin unsound, and St. +Thomas Aquinas guilty of weakness, when the one swerved from this view and +the other tolerated the deviation. And, until responsible Catholic +authority--say, for example, the Archbishop of Westminster--formally +declares that Suarez was wrong, and that Catholic priests are free to teach +their flocks that the world was _not_ made in six natural days, and +that plants and animals were _not_ created in their perfect and +complete state, but have been evolved by natural processes through long +ages from certain germs in which they were potentially contained, I, for +one, shall feel bound to believe that the doctrines of Suarez are the only +ones which are sanctioned by Infallible Authority, as represented by the +Holy Father and the Catholic Church. + +I need hardly add that they are as absolutely denied and repudiated by +Scientific Authority, as represented by Reason and Fact. The question +whether the earth and the immediate progenitors of its present living +population were made in six natural days or not is no longer one upon which +two opinions can be held. + +The fact that it did not so come into being stands upon as sound a basis as +any fact of history whatever. It is not true that existing plants and +animals came into being within three days of the creation of the earth out +of nothing, for it is certain that innumerable generations of other plants +and animals lived upon the earth before its present population. And when, +Sunday after Sunday, men who profess to be our instructors in righteousness +read out the statement, "In six days the Lord made heaven and earth, the +sea, and all that in them is," in innumerable churches, they are either +propagating what they may easily know, and, therefore, are bound to know, +to be falsities; or, if they use the words in some non-natural sense, they +fall below the moral standard of the much-abused Jesuit. + +Thus far the contradiction between Catholic verity and Scientific verity is +complete and absolute, quite independently of the truth or falsehood of the +doctrine of evolution. But, for those who hold the doctrine of evolution, +all the Catholic verities about the creation of living beings must be no +less false. For them, the assertion that the progenitors of all existing +plants were made on the third day, of animals on the fifth and sixth days, +in the forms they now present, is simply false. Nor can they admit that man +was made suddenly out of the dust of the earth; while it would be an insult +to ask an evolutionist whether he credits the preposterous fable respecting +the fabrication of woman to which Suarez pins his faith. If Suarez has +rightly stated Catholic doctrine, then is evolution utter heresy. And such +I believe it to be. In addition to the truth of the doctrine of evolution, +indeed, one of its greatest merits in my eyes, is the fact that it occupies +a position of complete and irreconcilable antagonism to that vigorous and +consistent enemy of the highest intellectual, moral, and social life of +mankind--the Catholic Church. No doubt, Mr. Mivart, like other putters of +new wine into old bottles, is actuated by motives which are worthy of +respect, and even of sympathy; but his attempt has met with the fate which +the Scripture prophesies for all such. + +Catholic theology, like all theologies which are based upon the assumption +of the truth of the account of the origin of things given in the Book of +Genesis, being utterly irreconcilable with the doctrine of evolution, the +student of science, who is satisfied that the evidence upon which the +doctrine of evolution rests, is incomparably stronger and better than that +upon which the supposed authority of the Book of Genesis rests, will not +trouble himself further with these theologies, but will confine his +attention to such arguments against the view he holds as are based upon +purely scientific data--and by scientific data I do not merely mean the +truths of physical, mathematical, or logical science, but those of moral +and metaphysical science. For by science I understand all knowledge which +rests upon evidence and reasoning of a like character to that which claims +our assent to ordinary scientific propositions. And if any one is able to +make good the assertion that his theology rests upon valid evidence and +sound reasoning, then it appears to me that such theology will take its +place as a part of science. + +The present antagonism between theology and science does not arise from any +assumption by the men of science that all theology must necessarily be +excluded from science, but simply because they are unable to allow that +reason and morality have two weights and two measures; and that the belief +in a proposition, because authority tells you it is true, or because you +wish to believe it, which is a high crime and misdemeanour when the subject +matter of reasoning is of one kind, becomes under the _alias_ of +"faith" the greatest of all virtues when the subject matter of reasoning is +of another kind. + +The Bishop of Brechin said well the other day:--"Liberality in religion--I +do not mean tender and generous allowances for the mistakes of others--is +only unfaithfulness to truth." [Footnote: Charge at the Diocesan Synod of +Brechin. _Scotsman_, Sept. 14, 1871.] And, with the same +qualification, I venture to paraphrase the Bishop's dictum: +"Ecclesiasticism in science is only unfaithfulness to truth." + +Elijah's great question, "Will you serve God or Baal? Choose ye," is +uttered audibly enough in the ears of every one of us as we come to +manhood. Let every man who tries to answer it seriously ask himself whether +he can be satisfied with the Baal of authority, and with all the good +things his worshippers are promised in this world and the next. If he can, +let him, if he be so inclined, amuse himself with such scientific +implements as authority tells him are safe and will not cut his fingers; +but let him not imagine he is, or can be, both a true son of the Church and +a loyal soldier of science. + +And, on the other hand, if the blind acceptance of authority appears to him +in its true colours, as mere private judgment _in excelsis_, and if he +have the courage to stand alone, face to face with the abyss of the eternal +and unknowable, let him be content, once for all, not only to renounce the +good things promised by "Infallibility," but even to bear the bad things +which it prophesies; content to follow reason and fact in singleness and +honesty of purpose, wherever they may lead, in the sure faith that a hell +of honest men will, to him, be more endurable than a paradise full of +angelic shams. + +Mr. Mivart asserts that "without a belief in a personal God there is no +religion worthy of the name." This is a matter of opinion. But it may be +asserted, with less reason to fear contradiction, that the worship of a +personal God, who, on Mr. Mivart's hypothesis, must have used language +studiously calculated to deceive His creatures and worshippers, is "no +religion worthy of the name." "Incredible est, Deum illis verbis ad populum +fuisse locutum quibus deciperetur," is a verdict in which, for once, Jesuit +casuistry concurs with the healthy moral sense of all mankind. + +Having happily got quit of the theological aspect of evolution, the +supporter of that great truth who turns to the scientific objections which +are brought against it by recent criticism, finds, to his relief, that the +work before him is greatly lightened by the spontaneous retreat of the +enemy from nine-tenths of the territory which he occupied ten years ago. +Even the Quarterly Reviewer not only abstains from venturing to deny that +evolution has taken place, but he openly admits that Mr. Darwin has forced +on men's minds "a recognition of the probability, if not more, of +evolution, and of the certainty of the action of natural selection" (p. +49). + +I do not quite see, myself, how, if the action of natural selection is +_certain_, the occurrence of evolution is only _probable_; +inasmuch as the development of a new species by natural selection is, so +far as it goes, evolution. However, it is not worth while to quarrel with +the precise terms of a sentence which shows that the high water mark of +intelligence among those most respectable of Britons, the readers of the +_Quarterly Review_, has now reached such a level that the next tide +may lift them easily and pleasantly on the once-dreaded shore of evolution. +Nor, having got there, do they seem likely to stop, until they have reached +the inmost heart of that great region, and accepted the ape ancestry of, at +any rate, the body of man. For the Reviewer admits that Mr. Darwin can be +said to have established: + +"That if the various kinds of lower animals have been evolved one from the +other by a process of natural generation or evolution, then it becomes +highly probable, _a priori_, that man's body has been similarly +evolved; but this, in such a case, becomes equally probable from the +admitted fact that he is an animal at all" (p. 65). + +From the principles laid down in the last sentence it would follow that if +man were constructed upon a plan as different from that of any other animal +as that of a sea-urchin is from that of a whale, it would be "equally +probable" that he had been developed from some other animal as it is now, +when we know that for every bone, muscle, tooth, and even pattern of tooth, +in man, there is a corresponding bone, muscle, tooth, and pattern of tooth, +in an ape. And this shows one of two things--either that the Quarterly +Reviewer's notions of probability are peculiar to himself, or that he has +such an overpowering faith in the truth of evolution that no extent of +structural break between one animal and another is sufficient to destroy +his conviction that evolution has taken place. + +But this by the way. The importance of the admission that there is nothing +in man's physical structure to interfere with his having been evolved from +an ape is not lessened because it is grudgingly made and inconsistently +qualified. And instead of jubilating over the extent of the enemy's +retreat, it will be more worth while to lay siege to his last +stronghold--the position that there is a distinction in kind between the +mental faculties of man and those of brutes, and that in consequence of +this distinction in kind no gradual progress from the mental faculties of +the one to those of the other can have taken place. + +The Quarterly Reviewer entrenches himself within formidable-looking +psychological outworks, and there is no getting at him without attacking +them one by one. + +He begins by laying down the following proposition. "'Sensation' is not +'thought,' and no amount of the former would constitute the most +rudimentary condition of the latter, though sensations supply the +conditions for the existence of 'thought' or 'knowledge'" (p. 67). + +This proposition is true, or not, according to the sense in which the word +"thought" is employed. Thought is not uncommonly used in a sense +co-extensive with consciousness, and, especially, with those states of +consciousness we call memory. If I recall the impression made by a colour +or an odour, and distinctly remember blueness or muskiness, I may say with +perfect propriety that I "think of" blue or musk; and, so long as the +thought lasts, it is simply a faint reproduction of the state of +consciousness to which I gave the name in question, when it first became +known to me as a sensation. + +Now, if that faint reproduction of a sensation, which we call the memory of +it, is properly termed a thought, it seems to me to be a somewhat forced +proceeding to draw a hard and fast line of demarcation between thoughts and +sensations. If sensations are not rudimentary thoughts, it may be said that +some thoughts are rudimentary sensations. No amount of sound constitutes an +echo, but for all that no one would pretend that an echo is something of +totally different nature from a sound. Again, nothing can be looser, or +more inaccurate, than the assertion that "sensations supply the conditions +for the existence of thought or knowledge." If this implies that sensations +supply the conditions for the existence of our memory of sensations or of +our thoughts about sensations, it is a truism which it is hardly worth +while to state so solemnly. If it implies that sensations supply anything +else, it is obviously erroneous. And if it means, as the context would seem +to show it does, that sensations are the subject-matter of all thought or +knowledge, then it is no less contrary to fact, inasmuch as our emotions, +which constitute a large part of the subject-matter of thought or of +knowledge, are not sensations. + +More eccentric still is the Quarterly Reviewer's next piece of psychology. + +"Altogether, we may clearly distinguish at least six kinds of action to +which the nervous system ministers:-- + +"I. That in which impressions received result in appropriate movements +without the intervention of sensation or thought, as in the cases of injury +above given.--This is the reflex action of the nervous system. + +"II. That in which stimuli from without result in sensations through the +agency of which their due effects are wrought out.--Sensation. + +"III. That in which impressions received result in sensations which give +rise to the observation of sensible objects.--Sensible perception. + +"IV. That in which sensations and perceptions continue to coalesce, +agglutinate, and combine in more or less complex aggregations, according to +the laws of the association of sensible perceptions.--Association. + +"The above four groups contain only indeliberate operations, consisting, as +they do at the best, but of mere _presentative_ sensible ideas in no +way implying any reflective or _representative_ faculty. Such actions +minister to and form _Instinct_. Besides these, we may distinguish two +other kinds of mental action, namely:-- + +"V. That in which sensations and sensible perceptions are reflected on by +thought, and recognised as our own, and we ourselves recognised by +ourselves as affected and perceiving.--Self-consciousness. + +"VI. That in which we reflect upon our sensations or perceptions, and ask +what they are, and why they are.--Reason. + +"These two latter kinds of action are deliberate operations, performed, as +they are, by means of representative ideas implying the use of a +_reflective representative_ faculty. Such actions distinguish the +_intellect_ or rational faculty. Now, we assert that possession in +perfection of all the first four (_presentative_) kinds of action by +no means implies the possession of the last two (_representative_) +kinds. All persons, we think, must admit the truth of the following +proposition:-- + +"Two faculties are distinct, not in degree but _in kind_, if we may +possess the one in perfection without that fact implying that we possess +the other also. Still more will this be the case if the two faculties tend +to increase in an inverse ratio. Yet this is the distinction between the +_instinctive_ and the _intellectual_ parts of man's nature. + +"As to animals, we fully admit that they may possess all the first four +groups of actions--that they may have, so to speak, mental images of +sensible objects combined in all degrees of complexity, as governed by the +laws of association. We deny to them, on the other hand, the possession of +the last two kinds of mental action. We deny them, that is, the power of +reflecting on their own existences, or of inquiring into the nature of +objects and their causes. We deny that they know that they know or know +themselves in knowing. In other words, we deny them _reason_. The +possession of the presentative faculty, as above explained, in no way +implies that of the reflective faculty; nor does any amount of direct +operation imply the power of asking the reflective question before +mentioned, as to 'what' and 'why.'" (_Loc. cit_. pp. 67, 68.) + +Sundry points are worthy of notice in this remarkable account of the +intellectual powers. In the first place the Reviewer ignores emotion and +volition, though they are no inconsiderable "kinds of action to which the +nervous system ministers," and memory has a place in his classification +only by implication. Secondly, we are told that the second "kind of action +to which the nervous system ministers" is "that in which stimuli from +without result in sensations through the agency of which their due effects +are wrought out.--Sensation." Does this really mean that, in the writer's +opinion, "sensation" is the "agent" by which the "due effect" of the +stimulus, which gives rise to sensation, is "wrought out"? Suppose somebody +runs a pin into me. The "due effect" of that particular stimulus will +probably be threefold; namely, a sensation of pain, a start, and an +interjectional expletive. Does the Quarterly Reviewer really think that the +"sensation" is the "agent" by which the other two phenomena are wrought +out? + +But these matters are of little moment to anyone but the Reviewer and those +persons who may incautiously take their physiology, or psychology, from +him. The really interesting point is this, that when he fully admits that +animals "may possess all the first four groups of actions," he grants all +that is necessary for the purposes of the evolutionist. For he hereby +admits that in animals "impressions received result in sensations which +give rise to the observation of sensible objects," and that they have what +he calls "sensible perception." Nor was it possible to help the admission; +for we have as much reason to ascribe to animals, as we have to attribute +to our fellow-men, the power, not only of perceiving external objects as +external, and thus practically recognizing the difference between the self +and the not-self; but that of distinguishing between like and unlike, and +between simultaneous and successive things. When a gamekeeper goes out +coursing with a greyhound in leash, and a hare crosses the field of vision, +he becomes the subject of those states of consciousness we call visual +sensation, and that is all he receives from without. Sensation, as such, +tells him nothing whatever about the cause of these states of +consciousness; but the thinking faculty instantly goes to work upon the raw +material of sensation furnished to it through the eye, and gives rise to a +train of thoughts. First comes the thought that there is an object at a +certain distance; then arises another thought--the perception of the +likeness between the states of consciousness awakened by this object to +those presented by memory, as, on some former occasion, called up by a +hare; this is succeeded by another thought of the nature of an +emotion--namely, the desire to possess the hare; then follows a longer or +shorter train of other thoughts, which end in a volition and an act--the +loosing of the greyhound from the leash. These several thoughts are the +concomitants of a process which goes on in the nervous system of the man. +Unless the nerve-elements of the retina, of the optic nerve, of the brain, +of the spinal cord, and of the nerves of the arms, went through certain +physical changes in due order and correlation, the various states of +consciousness which have been enumerated would not make their appearance. +So that in this, as in all other intellectual operations, we have to +distinguish two sets of successive changes--one in the physical basis of +consciousness, and the other in consciousness itself; one set which may, +and doubtless will, in course of time, be followed through all their +complexities by the anatomist and the physicist, and one of which only the +man himself can have immediate knowledge. + +As it is very necessary to keep up a clear distinction between these two +processes, let the one be called _neurosis_, and the other +_psychosis_. When the gamekeeper was first trained to his work every +step in the process of neurosis was accompanied by a corresponding step in +that of psychosis, or nearly so. He was conscious of seeing something, +conscious of making sure it was a hare, conscious of desiring to catch it, +and therefore to loose the greyhound at the right time, conscious of the +acts by which he let the dog out of the leash. But with practice, though +the various steps of the neurosis remain--for otherwise the impression on +the retina would not result in the loosing of the dog--the great majority +of the steps of the psychosis vanish, and the loosing of the dog follows +unconsciously, or as we say, without thinking about it, upon the sight of +the hare. No one will deny that the series of acts which originally +intervened between the sensation and the letting go of the dog were, in the +strictest sense, intellectual and rational operations. Do they cease to be +so when the man ceases to be conscious of them? That depends upon what is +the essence and what the accident of those operations, which, taken +together, constitute ratiocination. + +Now ratiocination is resolvable into predication, and predication consists +in marking, in some way, the existence, the co-existence, the succession, +the likeness and unlikeness, of things or their ideas. Whatever does this, +reasons; and if a machine produces the effects of reason, I see no more +ground for denying to it the reasoning power, because it is unconscious, +than I see for refusing to Mr. Babbage's engine the title of a calculating +machine on the same grounds. + +Thus it seems to me that a gamekeeper reasons, whether he is conscious or +unconscious, whether his reasoning is carried on by neurosis alone, or +whether it involves more or less psychosis. And if this is true of the +gamekeeper, it is also true of the greyhound. The essential resemblances in +all points of structure and function, so far as they can be studied, +between the nervous system of the man and that of the dog, leave no +reasonable doubt that the processes which go on in the one are just like +those which take place in the other. In the dog, there can be no doubt that +the nervous matter which lies between the retina and the muscles undergoes +a series of changes, precisely analogous to those which, in the man, give +rise to sensation, a train of thought, and volition. + +Whether this neurosis is accompanied by such psychosis as ours it is +impossible to say; but those who deny that the nervous changes, which, in +the dog, correspond with those which underlie thought in a man, are +accompanied by consciousness, are equally bound to maintain that those +nervous changes in the dog, which correspond with those which underlie +sensation in a man, are also unaccompanied by consciousness. In other +words, if there is no ground for believing that a dog thinks, neither is +there any for believing that he feels. + +As is well known, Descartes boldly faced this dilemma, and maintained that +all animals were mere machines and entirely devoid of consciousness. But he +did not deny, nor can anyone deny, that in this case they are reasoning +machines, capable of performing all those operations which are performed by +the nervous system of man when he reasons. For even supposing that in man, +and in man only, psychosis is superadded to neurosis--the neurosis which is +common to both man and animal gives their reasoning processes a fundamental +unity. But Descartes' position is open to very serious objections if the +evidence that animals feel is insufficient to prove that they really do so. +What is the value of the evidence which leads one to believe that one's +fellow-man feels? The only evidence in this argument of analogy is the +similarity of his structure and of his actions to one's own. And if that is +good enough to prove that one's fellow-man feels, surely it is good enough +to prove that an ape feels. For the differences of structure and function +between men and apes are utterly insufficient to warrant the assumption +that while men have those states of consciousness we call sensations apes +have nothing of the kind. Moreover, we have as good evidence that apes are +capable of emotion and volition as we have that men other than ourselves +are. But if apes possess three out of the four kinds of states of +consciousness which we discover in ourselves, what possible reason is there +for denying them the fourth? If they are capable of sensation, emotion, and +volition, why are they to be denied thought (in the sense of predication)? + +No answer has ever been given to these questions. And as the law of +continuity is as much opposed, as is the common sense of mankind, to the +notion that all animals are unconscious machines, it may safely be assumed +that no sufficient answer ever will be given to them. + +There is every reason to believe that consciousness is a function of +nervous matter, when that nervous matter has attained a certain degree of +organisation, just as we know the other "actions to which the nervous +system ministers," such as reflex action and the like, to be. As I have +ventured to state my view of the matter elsewhere, "our thoughts are the +expression of molecular changes in that matter of life which is the source +of our other vital phenomena." + +Mr. Wallace objects to this statement in the following terms:-- + +"Not having been able to find any clue in Professor Huxley's writings to +the steps by which he passes from those vital phenomena, which consist +only, in their last analysis, of movements by particles of matter, to those +other phenomena which we term thought, sensation, or consciousness; but, +knowing that so positive an expression of opinion from him will have great +weight with many persons, I shall endeavour to show, with as much brevity +as is compatible with clearness, that this theory is not only incapable of +proof, but is also, as it appears to me, inconsistent with accurate +conceptions of molecular physics." + +With all respect for Mr. Wallace, it appears to me that his remarks are +entirely beside the question. I really know nothing whatever, and never +hope to know anything, of the steps by which the passage from molecular +movement to states of consciousness is effected; and I entirely agree with +the sense of the passage which he quotes from Professor Tyndall, apparently +imagining that it is in opposition to the view I hold. + +All that I have to say is, that, in my belief, consciousness and molecular +action are capable of being expressed by one another, just as heat and +mechanical action are capable of being expressed in terms of one another. +Whether we shall ever be able to express consciousness in foot-pounds, or +not, is more than I will venture to say; but that there is evidence of the +existence of some correlation between mechanical motion and consciousness, +is as plain as anything can be. Suppose the poles of an electric battery to +be connected by a platinum wire. A certain intensity of the current gives +rise in the mind of a bystander to that state of consciousness we call a +"dull red light"--a little greater intensity to another which we call a +"bright red light;" increase the intensity, and the light becomes white; +and, finally, it dazzles, and a new state of consciousness arises, which we +term pain. Given the same wire and the same nervous apparatus, and the +amount of electric force required to give rise to these several states of +consciousness will be the same, however often the experiment is repeated. +And as the electric force, the light waves, and the nerve-vibrations caused +by the impact of the light-waves on the retina, are all expressions of the +molecular changes which are taking place in the elements of the battery; so +consciousness is, in the same sense, an expression of the molecular changes +which take place in that nervous matter, which is the organ of +consciousness. + +And, since this, and any number of similar examples that may be required, +prove that one form of consciousness, at any rate, is, in the strictest +sense, the expression of molecular change, it really is not worth while to +pursue the inquiry, whether a fact so easily established is consistent with +any particular system of molecular physics or not. + +Mr. Wallace, in fact, appears to me to have mixed up two very distinct +propositions: the one, the indisputable truth that consciousness is +correlated with molecular changes in the organ of consciousness; the other, +that the nature of that correlation is known, or can be conceived, which is +quite another matter. Mr. Wallace, presumably, believes in that correlation +of phenomena which we call cause and effect as firmly as I do. But if he +has ever been able to form the faintest notion how a cause gives rise to +its effect, all I can say is that I envy him. Take the simplest case +imaginable--suppose a ball in motion to impinge upon another ball at rest. +I know very well, as a matter of fact, that the ball in motion will +communicate some of its motion to the ball at rest, and that the motion of +the two balls, after collision, is precisely correlated with the masses of +both balls and the amount of motion of the first. But how does this come +about? In what manner can we conceive that the _vis viva_ of the first +ball passes into the second? I confess I can no more form any conception of +what happens in this case, than I can of what takes place when the motion +of particles of my nervous matter, caused by the impact of a similar ball +gives rise to the state of consciousness I call pain. In ultimate analysis +everything is incomprehensible, and the whole object of science is simply +to reduce the fundamental incomprehensibilities to the smallest possible +number. + +But to return to the Quarterly Reviewer. He admits that animals have +"mental images of sensible objects, combined in all degrees of complexity, +as governed by the laws of association." Presumably, by this confused and +imperfect statement the Reviewer means to admit more than the words imply. +For mental images of sensible objects, even though "combined in all degrees +of complexity," are, and can be, nothing more than mental images of +sensible objects. But judgments, emotions, and volitions cannot by any +possibility be included under the head of "mental images of sensible +objects." If the greyhound had no better mental endowment than the Reviewer +allows him, he might have the "mental image" of the "sensible object"--the +hare--and that might be combined with the mental images of other sensible +objects, to any degree of complexity, but he would have no power of judging +it to be at a certain distance from him; no power of perceiving its +similarity to his memory of a hare; and no desire to get at it. +Consequently he would stand stock still, and the noble art of coursing +would have no existence. On the other hand, as that art is largely +practised, it follows that greyhounds alone possess a number of mental +powers, the existence of which, in any animal, is absolutely denied by the +Quarterly Reviewer. + +Finally, what are the mental powers which he reserves as the especial +prerogative of man? They are two. First, the recognition of "ourselves by +ourselves as affected and perceiving.--Self-consciousness." + +Secondly. "The reflection upon our sensations and perceptions, and asking +what they are and why they are.--Reason." + +To the faculty defined in the last sentence, the Reviewer, without +assigning the least ground for thus departing from both common usage and +technical propriety, applies the name of reason. But if man is not to be +considered a reasoning being, unless he asks what his sensations and +perceptions are, and why they are, what is a Hottentot, or an Australian +"black-fellow"; or what the "swinked hedger" of an ordinary agricultural +district? Nay, what becomes of an average country squire or parson? How +many of these worthy persons who, as their wont is, read the _Quarterly +Review_, would do other than stand agape, if you asked them whether they +had ever reflected what their sensations and perceptions are and why they +are? + +So that if the Reviewer's new definition of reason be correct, the majority +of men, even among the most civilised nations, are devoid of that supreme +characteristic of manhood. And if it be as absurd as I believe it to be, +then, as reason is certainly not self-consciousness, and since it, as +certainly, is one of the "actions to which the nervous system ministers," +we must, if the Reviewer's classification is to be adopted, seek it among +those four faculties which he allows animals to possess. And thus, for the +second time, he really surrenders, while seeming to defend, his position. + +The Quarterly Reviewer, as we have seen, lectures the evolutionists upon +their want of knowledge of philosophy altogether. Mr. Mivart is not less +pained at Mr. Darwin's ignorance of moral science. It is grievous to him +that Mr. Darwin (and _nous autres_) should not have grasped the +elementary distinction between material and formal morality; and he lays +down as an axiom, of which no tyro ought to be ignorant, the position that +"acts, unaccompanied by mental acts of conscious will directed towards the +fulfilment of duty," are "absolutely destitute of the most incipient degree +of real or formal goodness." + +Now this may be Mr. Mivart's opinion, but it is a proposition which really +does not stand on the footing of an undisputed axiom. Mr. Mill denies it in +his work on Utilitarianism. The most influential writer of a totally +opposed school, Mr. Carlyle, is never weary of denying it, and upholding +the merit of that virtue which is unconscious; nay, it is, to my +understanding, extremely hard to reconcile Mr. Mivart's dictum with that +noble summary of the whole duty of man--"Thou shalt love the Lord thy God +with all thy heart, and with all thy soul, and with all thy strength; and +thou shalt love thy neighbour as thyself." According to Mr. Mivart's +definition, the man who loves God and his neighbour, and, out of sheer love +and affection for both, does all he can to please them, is, nevertheless, +destitute of a particle of real goodness. + +And it further happens that Mr. Darwin, who is charged by Mr. Mivart with +being ignorant of the distinction between material and formal goodness, +discusses the very question at issue in a passage which is well worth +reading (vol. i. p. 87), and also comes to a conclusion opposed to Mr. +Mivart's axiom. A proposition which has been so much disputed and +repudiated, should, under no circumstances, have been thus confidently +assumed to be true. For myself, I utterly reject it, inasmuch as the +logical consequence of the adoption of any such principle is the denial of +all moral value to sympathy and affection. According to Mr. Mivart's axiom, +the man who, seeing another struggling in the water, leaps in at the risk +of his own life to save him, does that which is "destitute of the most +incipient degree of real goodness," unless, as he strips off his coat, he +says to himself, "Now, mind, I am going to do this because it is my duty +and for no other reason;" and the most beautiful character to which +humanity can attain, that of the man who does good without thinking about +it, because he loves justice and mercy and is repelled by evil, has no +claim on our moral approbation. The denial that a man acts morally because +he does not think whether he does so or not, may be put upon the same +footing as the denial of the title of an arithmetician to the calculating +boy, because he did not know how he worked his sums. If mankind ever +generally accept and act upon Mr. Mivart's axiom, they will simply become a +set of most unendurable prigs; but they never have accepted it, and I +venture to hope that evolution has nothing so terrible in store for the +human race. + +But if an action, the motive of which is nothing but affection or sympathy, +may be deserving of moral approbation and really good, who that has ever +had a dog of his own will deny that animals are capable of such actions? +Mr. Mivart indeed says:--"It may be safely affirmed, however, that there is +no trace in brutes of any actions simulating morality which are not +explicable by the fear of punishment, by the hope of pleasure, or by +personal affection" (p. 221). But it may be affirmed, with equal truth, +that there is no trace in men of any actions which are not traceable to the +same motives. If a man does anything, he does it either because he fears to +be punished if he does not do it, or because he hopes to obtain pleasure by +doing it, or because he gratifies his affections [Footnote: In separating +pleasure and the gratification of affection, I simply follow Mr. Mivart +without admitting the justice of the separation.] by doing it. + +Assuming the position of the absolute moralists, let it be granted that +there is a perception of right and wrong innate in every man. This means, +simply, that when certain ideas are presented to his mind, the feeling of +approbation arises; and when certain others, the feeling of disapprobation. +To do your duty is to earn the approbation of your conscience, or moral +sense; to fail in your duty is to feel its disapprobation, as we all say. +Now, is approbation a pleasure or a pain? Surely a pleasure. And is +disapprobation a pleasure or a pain? Surely a pain. Consequently, all that +is really meant by the absolute moralists is that there is, in the very +nature of man, something which enables him to be conscious of these +particular pleasures and pains. And when they talk of immutable and eternal +principles of morality, the only intelligible sense which I can put upon +the words, is that the nature of man being what it is, he always has been, +and always will be, capable of feeling these particular pleasures and +pains. _À priori,_ I have nothing to say against this proposition. +Admitting its truth, I do not see how the moral faculty is on a different +footing from any of the other faculties of man. If I choose to say that it +is an immutable and eternal law of human nature that "ginger is hot in the +mouth," the assertion has as much foundation of truth as the other, though +I think it would be expressed in needlessly pompous language. I must +confess that I have never been able to understand why there should be such +a bitter quarrel between the intuitionists and the utilitarians. The +intuitionist is, after all, only a utilitarian who believes that a +particular class of pleasures and pains has an especial importance, by +reason of its foundation in the nature of man, and its inseparable +connection with his very existence as a thinking being. And as regards the +motive of personal affection: Love, as Spinoza profoundly says, is the +association of pleasure with that which is loved. [Footnote: "Nempe, Amor +nihil aliud est, quam Lætitia, concomitante idea causæ +externæ."--_Ethices_, III. xiii.] Or, to put it to the common sense of +mankind, is the gratification of affection a pleasure or a pain? Surely a +pleasure. So that whether the motive which leads us to perform an action is +the love of our neighbour, or the love of God, it is undeniable that +pleasure enters into that motive. + +Thus much in reply to Mr. Mivart's arguments. I cannot but think that it is +to be regretted that he ekes them out by ascribing to the doctrines of the +philosophers with whom he does not agree, logical consequences which have +been over and over again proved not to flow from them: and when reason +fails him, tries the effect of an injurious nickname. According to the +views of Mr. Spencer, Mr. Mill, and Mr. Darwin, Mr. Mivart tells us, +"_virtue is a mere kind of retrieving:_" and, that we may not miss the +point of the joke, he puts it in italics. But what if it is? Does that make +it less virtue? Suppose I say that sculpture is a "mere way" of +stone-cutting, and painting a "mere way" of daubing canvas, and music a +"mere way" of making a noise, the statements are quite true; but they only +show that I see no other method of depreciating some of the noblest aspects +of humanity than that of using language in an inadequate and misleading +sense about them. And the peculiar inappropriateness of this particular +nickname to the views in question, arises from the circumstance which Mr. +Mivart would doubtless have recollected, if his wish to ridicule had not +for the moment obscured his judgment--that whether the law of evolution +applies to man or not, that of hereditary transmission certainly does. Mr. +Mivart will hardly deny that a man owes a large share of the moral +tendencies which he exhibits to his ancestors; and the man who inherits a +desire to steal from a kleptomaniac, or a tendency to benevolence from a +Howard, is, so far as he illustrates hereditary transmission, comparable to +the dog who inherits the desire to fetch a duck out of the water from his +retrieving sire. So that, evolution, or no evolution, moral qualities are +comparable to a "kind of retrieving;" though the comparison, if meant for +the purposes of casting obloquy on evolution, does not say much for the +fairness of those who make it. + +The Quarterly Reviewer and Mr. Mivart base their objections to the +evolution of the mental faculties of man from those of some lower animal +form upon what they maintain to be a difference in kind between the mental +and moral faculties of men and brutes; and I have endeavoured to show, by +exposing the utter unsoundness of their philosophical basis, that these +objections are devoid of importance. + +The objections which Mr. Wallace brings forward to the doctrine of the +evolution of the mental faculties of man from those of brutes by natural +causes, are of a different order, and require separate consideration. + +If I understand him rightly, he by no means doubts that both the bodily and +the mental faculties of man have been evolved from those of some lower +animal; but he is of opinion that some agency beyond that which has been +concerned in the evolution of ordinary animals has been operative in the +case of man. "A superior intelligence has guided the development of man in +a definite direction and for a special purpose, just as man guides the +development of many animal and vegetable forms." [Footnote: "The Limits of +Natural Selection as applied to Man" (_loc. cit._ p. 359).] I +understand this to mean that, just as the rock-pigeon has been produced by +natural causes, while the evolution of the tumbler from the blue rock has +required the special intervention of the intelligence of man, so some +anthropoid form may have been evolved by variation and natural selection; +but it could never have given rise to man, unless some superior +intelligence had played the part of the pigeon-fancier. + +According to Mr. Wallace, "whether we compare the savage with the higher +developments of man, or with the brutes around him, we are alike driven to +the conclusion, that, in his large and well-developed brain, he possesses +an organ quite disproportioned to his requirements" (p. 343); and he asks, +"What is there in the life of the savage but the satisfying of the cravings +of appetite in the simplest and easiest way? What thoughts, idea, or +actions are there that raise him many grades above the elephant or the +ape?" (p. 342.) I answer Mr. Wallace by citing a remarkable passage which +occurs in his instructive paper on "Instinct in Man and Animals." + +"Savages make long journeys in many directions, and, their whole faculties +being directed to the subject, they gain a wide and accurate knowledge of +the topography, not only of their own district, but of all the regions +round about. Every one who has travelled in a new direction communicates +his knowledge to those who have travelled less, and descriptions of routes +and localities, and minute incidents of travel, form one of the main +staples of conversation around the evening fire. Every wanderer or captive +from another tribe adds to the store of information, and, as the very +existence of individuals and of whole families and tribes depends upon the +completeness of this knowledge, all the acute perceptive faculties of the +adult savage are directed to acquiring and perfecting it. The good hunter +or warrior thus comes to know the bearing of every hill and mountain range, +the directions and junctions of all the streams, the situation of each +tract characterised by peculiar vegetation, not only within the area he has +himself traversed, but perhaps for a hundred miles around it. His acute +observation enables him to detect the slightest undulations of the surface, +the various changes of subsoil and alterations in the character of the +vegetation that would be quite imperceptible to a stranger. His eye is +always open to the direction in which he is going; the mossy side of trees, +the presence of certain plants under the shade of rocks, the morning and +evening flight of birds, are to him indications of direction almost as sure +as the sun in the heavens" (pp. 207, 208). + +I have seen enough of savages to be able to declare that nothing can be +more admirable than this description of what a savage has to learn. But it +is incomplete. Add to all this the knowledge which a savage is obliged to +gain of the properties of plants, of the characters and habits of animals, +and of the minute indications by which their course is discoverable: +consider that even an Australian can make excellent baskets and nets, and +neatly fitted and beautifully balanced spears; that he learns to use these +so as to be able to transfix a quartern loaf at sixty yards; and that very +often, as in the case of the American Indians, the language of a savage +exhibits complexities which a well-trained European finds it difficult to +master: consider that every time a savage tracks his game he employs a +minuteness of observation, and an accuracy of inductive and deductive +reasoning which, applied to other matters, would assure some reputation to +a man of science, and I think we need ask no further why he possesses such +a fair supply of brains. In complexity and difficulty, I should say that +the intellectual labour of a "good hunter or warrior" considerably exceeds +that of an ordinary Englishman. The Civil Service Examiners are held in +great terror by young Englishmen; but even their ferocity never tempted +them to require a candidate to possess such a knowledge of a parish as Mr. +Wallace justly points out savages may possess of an area a hundred miles or +more in diameter. + +But suppose, for the sake of argument, that a savage has more brains than +seems proportioned to his wants, all that can be said is that the objection +to natural selection, if it be one, applies quite as strongly to the lower +animals. The brain of a porpoise is quite wonderful for its mass, and for +the development of the cerebral convolutions. And yet since we have ceased +to credit the story of Arion, it is hard to believe that porpoises are much +troubled with intellect: and still more difficult is it to imagine that +their big brains are only a preparation for the advent of some accomplished +cetacean of the future. Surely, again, a wolf must have too much brains, or +else how is it that a dog with only the same quantity and form of brain is +able to develop such singular intelligence? The wolf stands to the dog in +the same relation as the savage to the man; and, therefore, if Mr. +Wallace's doctrine holds good, a higher power must have superintended the +breeding up of wolves from some inferior stock, in order to prepare them to +become dogs. + +Mr. Wallace further maintains that the origin of some of man's mental +faculties by the preservation of useful variations is not possible. Such, +for example, are "the capacity to form ideal conceptions of space and time, +of eternity and infinity; the capacity for intense artistic feelings of +pleasure in form, colour, and composition; and for those abstract notions +of form and number which render geometry and arithmetic possible." "How," +he asks, "were all or any of these faculties first developed, when they +could have been of no possible use to man in his early stages of +barbarism?" + +Surely the answer is not far to seek. The lowest savages are as devoid of +any such conceptions as the brutes themselves. What sort of conceptions of +space and time, of form and number, can be possessed by a savage who has +not got so far as to be able to count beyond five or six, who does not know +how to draw a triangle or a circle, and has not the remotest notion of +separating the particular quality we call form, from the other qualities of +bodies? None of these capacities are exhibited by men, unless they form +part of a tolerably advanced society. And, in such a society, there are +abundant conditions by which a selective influence is exerted in favour of +those persons who exhibit an approximation towards the possession of these +capacities. + +The savage who can amuse his fellows by telling a good story over the +nightly fire, is held by them in esteem and rewarded, in one way or +another, for so doing--in other words, it is an advantage to him to possess +this power. He who can carve a paddle, or the figure-head of a canoe +better, similarly profits beyond his duller neighbour. He who counts a +little better than others, gets most yams when barter is going on, and +forms the shrewdest estimate of the numbers of an opposing tribe. The +experience of daily life shows that the conditions of our present social +existence exercise the most extraordinarily powerful selective influence in +favour of novelists, artists, and strong intellects of all kinds; and it +seems unquestionable that all forms of social existence must have had the +same tendency, if we consider the indisputable facts that even animals +possess the power of distinguishing form and number, and that they are +capable of deriving pleasure from particular forms and sounds. If we admit, +as Mr. Wallace does, that the lowest savages are not raised "many grades +above the elephant and the ape;" and if we further admit, as I contend must +be admitted, that the conditions of social life tend, powerfully, to give +an advantage to those individuals who vary in the direction of intellectual +or æsthetic excellence, what is there to interfere with the belief that +these higher faculties, like the rest, owe their development to natural +selection? + +Finally, with respect to the development of the moral sense out of the +simple feelings of pleasure and pain, liking and disliking, with which the +lower animals are provided, I can find nothing in Mr. Wallace's reasonings +which has not already been met by Mr. Mill, Mr. Spencer, or Mr. Darwin. + +I do not propose to follow the Quarterly Reviewer and Mr. Mivart through +the long string of objections in matters of detail which they bring against +Mr. Darwin's views. Every one who has considered the matter carefully will +be able to ferret out as many more "difficulties"; but he will also, I +believe, fail as completely as they appear to me to have done, in bringing +forward any fact which is really contradictory of Mr. Darwin's views. +Occasionally, too, their objections and criticisms are based upon errors of +their own. As, for example, when Mr. Mivart and the Quarterly Reviewer +insist upon the resemblances between the eyes of _Cephalopoda_ and +_Vertebrata_, quite forgetting that there are striking and altogether +fundamental differences between them; or when the Quarterly Reviewer +corrects Mr. Darwin for saying that the gibbons, "without having been +taught, can walk or run upright with tolerable quickness, though they move +awkwardly, and much less securely than man." The Quarterly Reviewer says, +"This is a little misleading, inasmuch as it is not stated that this +upright progression is effected by placing the enormously long arms behind +the head, or holding them out backwards as a balance in progression." + +Now, before carping at a small statement like this, the Quarterly Reviewer +should have made sure that he was quite right. But he happens to be quite +wrong. I suspect he got his notion of the manner in which a gibbon walks +from a citation in "Man's Place in Nature." But at that time I had not seen +a gibbon walk. Since then I have, and I can testify that nothing can be +more precise than Mr. Darwin's statement. The gibbon I saw walked without +either putting his arms behind his head or holding them out backwards. All +he did was to touch the ground with the outstretched fingers of his long +arms now and then, just as one sees a man who carries a stick, but does not +need one, touch the ground with it as he walks along. + +Again, a large number of the objections brought forward by Mr. Mivart and +the Quarterly Reviewer apply to evolution in general, quite as much as to +the particular form of that doctrine advocated by Mr. Darwin; or, to their +notions of Mr. Darwin's views and not to what they really are. An excellent +example of this class of difficulties is to be found in Mr. Mivart's +chapter on "Independent Similarities of Structure." Mr. Mivart says that +these cannot be explained by an "absolute and pure Darwinian," but "that an +innate power and evolutionary law, aided by the corrective action of +natural selection, should have furnished like needs with like aids, is not +at all improbable" (p. 82). + +I do not exactly know what Mr. Mivart means by an "absolute and pure +Darwinian;" indeed Mr. Mivart makes that creature hold so many singular +opinions that I doubt if I can ever have seen one alive. But I find nothing +in his statement of the view which he imagines to be originated by himself, +which is really inconsistent with what I understand to be Mr. Darwin's +views. + +I apprehend that the foundation of the theory of natural selection is the +fact that living bodies tend incessantly to vary. This variation is neither +indefinite, nor fortuitous, nor does it take place in all directions, in +the strict sense of these words. + +Accurately speaking, it is not indefinite, nor does it take place in all +directions, because it is limited by the general characters of the type to +which the organism exhibiting the variation belongs. A whale does not tend +to vary in the direction of producing feathers, nor a bird in the direction +of developing whalebone. In popular language there is no harm in saying +that the waves which break upon the sea-shore are indefinite, fortuitous, +and break in all directions. In scientific language, on the contrary, such +a statement would be a gross error, inasmuch as every particle of foam is +the result of perfectly definite forces, operating according to no less +definite laws. In like manner, every variation of a living form, however +minute, however apparently accidental, is inconceivable except as the +expression of the operation of molecular forces or "powers" resident within +the organism. And, as these forces certainly operate according to definite +laws, their general result is, doubtless, in accordance with some general +law which subsumes them all. And there appears to be no objection to call +this an "evolutionary law." But nobody is the wiser for doing so, or has +thereby contributed, in the least degree, to the advance of the doctrine of +evolution, the great need of which is a theory of variation. + +When Mr. Mivart tells us that his "aim has been to support the doctrine +that these species have been evolved by ordinary _natural laws_ (for +the most part unknown), aided by the _subordinate_ action of 'natural +selection'" (pp. 332-3), he seems to be of opinion that his enterprise has +the merit of novelty. All I can say is that I have never had the slightest +notion that Mr. Darwin's aim is in any way different from this. If I affirm +that "species have been evolved by variation [Footnote: Including under +this head hereditary transmission.] (a natural process, the laws of which +are for the most part unknown), aided by the subordinate action of natural +selection," it seems to me that I enunciate a proposition which constitutes +the very pith and marrow of the first edition of the "Origin of Species." +And what the evolutionist stands in need of just now, is not an iteration +of the fundamental principle of Darwinism, but some light upon the +questions, What are the limits of variation? and, If a variety has arisen, +can that variety be perpetuated, or even intensified, when selective +conditions are indifferent, or perhaps unfavourable to its existence? I +cannot find that Mr. Darwin has ever been very dogmatic in answering these +questions. Formerly, he seems to have inclined to reply to them in the +negative, while now his inclination is the other way. Leaving aside those +broad questions of theology, philosophy, and ethics, by the discussion of +which neither the Quarterly Reviewer nor Mr. Mivart can be said to have +damaged Darwinism--whatever else they have injured--this is what their +criticisms come to. They confound a struggle for some rifle-pits with an +assault on the fortress. + +In some respects, finally, I can only characterise the Quarterly Reviewer's +treatment of Mr. Darwin as alike unjust and unbecoming. Language of this +strength requires justification, and on that ground I add the remarks which +follow. + +The Quarterly Reviewer opens his essay by a careful enumeration of all +those points upon which, during the course of thirteen years of incessant +labour, Mr. Darwin has modified his opinions. It has often and justly been +remarked, that what strikes a candid student of Mr. Darwin's works is not +so much his industry, his knowledge, or even the surprising fertility of +his inventive genius; but that unswerving truthfulness and honesty which +never permit him to hide a weak place, or gloss over a difficulty, but lead +him, on all occasions, to point out the weak places in his own armour, and +even sometimes, it appears to me, to make admissions against himself which +are quite unnecessary. A critic who desires to attack Mr. Darwin has only +to read his works with a desire to observe, not their merits, but their +defects, and he will find, ready to hand, more adverse suggestions than are +likely ever to have suggested themselves to his own sharpness, without Mr. +Darwin's self-denying aid. + +Now this quality of scientific candour is not so common that it needs to be +discouraged; and it appears to me to deserve other treatment than that +adopted by the Quarterly Reviewer, who deals with Mr. Darwin as an Old +Bailey barrister deals with a man against whom he wishes to obtain a +conviction, _per fas aut nefas_, and opens his case by endeavouring to +create a prejudice against the prisoner in the minds of the jury. In his +eagerness to carry out this laudable design, the Quarterly Reviewer cannot +even state the history of the doctrine of natural selection without an +oblique and entirely unjustifiable attempt to depreciate Mr. Darwin. "To +Mr. Darwin," says he, "and (through Mr. Wallace's reticence) to Mr. Darwin +alone, is due the credit of having first brought it prominently forward and +demonstrated its truth." No one can less desire than I do, to throw a doubt +upon Mr. Wallace's originality, or to question his claim to the honour of +being one of the originators of the doctrine of natural selection; but the +statement that Mr. Darwin has the sole credit of originating the doctrine +because of Mr. Wallace's reticence is simply ridiculous. The proof of this +is, in the first place, afforded by Mr. Wallace himself, whose noble +freedom from petty jealousy in this matter smaller folk would do well to +imitate, and who writes thus:--"I have felt all my life, and I still feel, +the most sincere satisfaction that Mr. Darwin had been at work long before +me and that it was not left for me to attempt to write the 'Origin of +Species.' I have long since measured my own strength, and know well that it +would be quite unequal to that task." So that if there was any reticence at +all in the matter, it was Mr. Darwin's reticence during the long twenty +years of study which intervened between the conception and the publication +of his theory, which gave Mr. Wallace the chance of being an independent +discoverer of the importance of natural selection. And, finally, if it be +recollected that Mr. Darwin's and Mr. Wallace's essays were published +simultaneously in the "Journal of the Linnæan Society" for 1858, it follows +that the Reviewer, while obliquely depreciating Mr. Darwin's deserts, has +in reality awarded to him a priority which, in legal strictness, does not +exist. + +Mr. Mivart, whose opinions so often concur with those of the Quarterly +Reviewer, puts the case in a way, which I much regret to be obliged to say, +is, in my judgment, quite as incorrect; though the injustice may be less +glaring. He says that the theory of natural selection is, in general, +exclusively associated with the name of Mr. Darwin, "on account of the +noble self-abnegation of Mr. Wallace." As I have said, no one can honour +Mr. Wallace more than I do, both for what he has done and for what he has +not done, in his relation to Mr. Darwin. And perhaps nothing is more +creditable to him than his frank declaration that he could not have written +such a work as the "Origin of Species." But, by this declaration, the +person most directly interested in the matter repudiates, by anticipation, +Mr. Mivart's suggestion that Mr. Darwin's eminence is more or less due to +Mr. Wallace's modesty. + + + + +VI + +EVOLUTION IN BIOLOGY + +[1878] + + +In the former half of the eighteenth century, the term "evolution" was +introduced into biological writings, in order to denote the mode in which +some of the most eminent physiologists of that time conceived that the +generations of living things took place; in opposition to the hypothesis +advocated, in the preceding century, by Harvey in that remarkable work +[Footnote: The _Exercitationes de Generatione Animalium_, which Dr. +George Ent extracted from him and published in 1651.] which would give him +a claim to rank among the founders of biological science, even had he not +been the discoverer of the circulation of the blood. + +One of Harvey's prime objects is to defend and establish, on the basis of +direct observation, the opinion already held by Aristotle; that, in the +higher animals at any rate, the formation of the new organism by the +process of generation takes place, not suddenly, by simultaneous accretion +of rudiments of all, or of the most important, of the organs of the adult; +nor by sudden metamorphosis of a formative substance into a miniature of +the whole, which subsequently grows; but by _epigenesis_, or +successive differentiation of a relatively homogeneous rudiment into the +parts and structures which are characteristic of the adult. + +"Et primò, quidem, quoniam per _epigenesin_ sive partium +superexorientium additamentum pullum fabricari certum est: quænam pars ante +alias omnes exstruatur, et quid de illa ejusque generandi modo observandum +veniat, dispiciemus. Ratum sane est et in ovo manifestè apparet quod +_Aristoteles_ de perfectorum animalium generatione enuntiat: nimirum, +non omnes partes simul fieri, sed ordine aliam post aliam; primùmque +existere particulam genitalem, cujus virtute postea (tanquam ex principio +quodam) reliquæ omnes partes prosiliant. Qualem in plantarum seminibus +(fabis, putà, aut glandibus) gemmam sive apicem protuberantem cernimus, +totius futuræ arboris principium. _Estque hæc particula, velut filius +emancipatus seorsumquc collocatus, et principium per se vivens; unde +postea, membrorum ordo describitur; et quæcunque ad absolvendum animal +pertinent, disponuntur._ [Footnote: _De Generatione Animalium_, +lib. ii. cap. x.] Quoniam enim _nulla pars se ipsam generat; sed postquam +generata est, se ipsam jam auget; ideo eam primùm oriri necesse est, quæ +principium augendi contineat (sive enim planta, sive animal est, æque +omnibus inest quod vim habeat vegetandi, sive nutriendi_), [Footnote: +_De Generatione_, lib. ii. cap. iv.] simulque reliquas omnes partes +suo quamque ordine distinguat et formet; proindeque in eadem primogenita +particula anima primario inest, sensus, motusque, et totius vitæ auctor et +principium." (Exercitatio 51.) + +Harvey proceeds to contrast this view with that of the "Medici," or +followers of Hippocrates and Galen, who, "badly philosophising," imagined +that the brain, the heart, and the liver were simultaneously first +generated in the form of vesicles; and, at the same time, while expressing +his agreement with Aristotle in the principle of epigenesis, he maintains +that it is the blood which is the primal generative part, and not, as +Aristotle thought, the heart. + +In the latter part of the seventeenth century, the doctrine of epigenesis, +thus advocated by Harvey, was controverted, on the ground of direct +observation, by Malpighi, who affirmed that the body of the chick is to be +seen in the egg, before the _punctum sanguineum_ makes it appearance. +But, from this perfectly correct observation a conclusion which is by no +means warranted was drawn; namely, that the chick, as a whole, really +exists in the egg antecedently to incubation; and that what happens in the +course of the latter process is no addition of new parts, "alias post alias +natas," as Harvey puts it, but a simple expansion, or unfolding, of the +organs which already exist, though they are too small and inconspicuous to +be discovered. The weight of Malpighi's observations therefore fell into +the scale of that doctrine which Harvey terms _metamorphosis_, in +contradistinction to epigenesis. + +The views of Malpighi were warmly welcomed, on philosophical grounds, by +Leibnitz, [Footnote: "Cependant, pour revenir aux formes ordinaires ou aux +âmes matérielles, cette durée qu'il leur faut attribuer à la place de celle +qu'on avoit attribuée aux atomes pourroit faire douter si elles ne vont pas +de corps en corps; ce qui seroit la métempsychose, à peu près comme +quelques philosophes ont cru la transmission du mouvement et celle des +espèces. Mais cette imagination est bien éloignée de la nature des choses. +Il n'y a point de tel passage; et c'est ici où les transformations de +Messieurs Swammerdam, Malpighi, et Leewenhoek, qui sont des plus excellens +observateurs de notre tems, sont venues à mon secours, et m'ont fait +admettre plus aisément, que l'animal, et toute autre substance organisée ne +commence point lorsque nous le croyons, et que sa generation apparente +n'est qu'une développement et une espèce d'augmentation. Aussi ai je +remarqué que l'auteur de la _Recherche de la Verité_, M. Regis, M. +Hartsoeker, et d'autres habiles hommes n'ont pas été fort éloignés de ce +sentiment." Leibnitz, _Système Nouveau de la Nature_, 1695. The +doctrine of "Embôitement" is contained in the _Considérations sur le +Principe de Vie_, 1705; the preface to the _Theodicée_, 1710; and +the _Principes de la Nature et de la Grace_ (§ 6), 1718.] who found in +them a support to his hypothesis of monads, and by Malebranche; [Footnote: +"Il est vrai que la pensée la plus raisonnable et la plus conforme à +l'experience sur cette question très difficile de la formation du foetus; +c'est que les enfans sont déja presque tout formés avant même l'action par +laquelle ils sont conçus; et que leurs mères ne font que leur donner +l'accroissement ordinaire dans le temps de la grossesse." _De la +Recherche de la Verité_, livre ii. chap. vii. p. 334, 7th ed., 1721.] +while, in the middle of the eighteenth century, not only speculative +considerations, but a great number of new and interesting observations on +the phenomena of generation, led the ingenious Bonnet, and Haller, +[Footnote: The writer is indebted to Dr. Allen Thomson for reference to the +evidence contained in a note to Haller's edition of Boerhaave's +_Prælectiones Academicæ_, vol. v. pt. ii. p. 497, published in 1744, +that Haller originally advocated epigenesis.] the first physiologist of the +age, to adopt, advocate, and extend them. + +Bonnet affirms that, before fecundation, the hen's egg contains an +excessively minute but complete chick; and that fecundation and incubation +simply cause this germ to absorb nutritious matters, which are deposited in +the interstices of the elementary structures of which the miniature chick, +or germ, is made up. The consequence of this intussusceptive growth is the +"development" or "evolution" of the germ into the visible bird. Thus an +organised individual (_tout organisé_) "is a composite body consisting +of the original, or _elementary_, parts and of the matters which have +been associated with them by the aid of nutrition;" so that, if these +matters could be extracted from the individual (_tout_), it would, so +to speak, become concentrated in a point, and would thus be restored to its +primitive condition of a _germ_; "just as by extracting from a bone +the calcareous substance which is the source of its hardness, it is reduced +to its primitive state of gristle or membrane." [Footnote: +_Considérations sur les Corps organisés, chap. x.] "Evolution" and +"development" are, for Bonnet, synonymous terms; and since by "evolution" +he means simply the expansion of that which was invisible into visibility, +he was naturally led to the conclusion, at which Leibnitz had arrived by a +different line of reasoning, that no such thing as generation, in the +proper sense of the word, exists in Nature. The growth of an organic being +is simply a process of enlargement as a particle of dry gelatine may be +swelled up by the intussusception of water; its death is a shrinkage, such +as the swelled jelly might undergo on desiccation. Nothing really new is +produced in the living world, but the germs which develop have existed +since the beginning of things; and nothing really dies, but, when what we +call death takes place, the living thing shrinks back into its germ state. +[Footnote: Bonnet had the courage of his opinions, and in the +_Palingénésie Philosophique_, part vi. chap, iv., he develops a +hypothesis which he terms "évolution naturelle;" and which, making +allowance for his peculiar views of the nature of generation, bears no +small resemblance to what is understood by "evolution" at the present +day:-- + +"Si la volonté divine a créé par un seul Acte l'Universalité des êtres, +d'où venoient ces plantes et ces animaux dont Moyse nous decrit la +Production au troisieme et au cinquieme jour du renouvellement de notre +monde? + +"Abuserois-je de la liberté de conjectures si je disois, que les Plantes et +les Animaux qui existent aujourd'hui sont parvenus par une sorte +d'evolution naturelle des Etres organises qui peuplaient ce premier Monde, +sorti immédiatement des MAINS du CREATEUR?... + +"Ne supposons que trois révolutions. La Terre vient de sortir des MAINS du +CREATEUR. Des causes preparées par sa SAGESSE font développer de toutes +parts les Germes. Les Etres organisés commencent à jouir de l'existence. +Ils étoient probablement alors bien différens de ce qu'ils sont +aujourd'hui. Ils l'etoient autant que ce premier Monde différoit de celui +que nous habitons. Nous manquons de moyens pour juger de ces dissemblances, +et peut-être que le plus habile Naturaliste qui auroit été placé dans ce +premier Monde y auroit entièrement méconnu nos Plantes et nos Animaux."] + +The two parts of Bonnet's hypothesis, namely, the doctrine that all living +things proceed from pre-existing germs, and that these contain, one +inclosed within the other, the germs of all future living things, which is +the hypothesis of "_emboîtement_;" and the doctrine that every germ +contains in miniature all the organs of the adult, which is the hypothesis +of evolution or development, in the primary senses of these words, must be +carefully distinguished. In fact, while holding firmly by the former, +Bonnet more or less modified the latter in his later writings, and, at +length, he admits that a "germ" need not be an actual miniature of the +organism; but that it may be merely an "original preformation" capable of +producing the latter. [Footnote: "Ce mot (germe) ne désignera pas seulement +un corps organisé _réduit en petit_; il désignera encore toute espèce +de _préformation originelle dont un Tout organique peut résulter comme de +son principe immédiat."--Palingénésie Philosophique_, part X. chap. II.] + +But, thus defined, the germ is neither more nor less than the "particula +genitalis" of Aristotle, or the "primordium vegetale" or "ovum" of Harvey; +and the "evolution" of such a germ would not be distinguishable from +"epigenesis." + +Supported by the great authority of Haller, the doctrine of evolution, or +development, prevailed throughout the whole of the eighteenth century, and +Cuvier appears to have substantially adopted Bonnet's later views, though +probably he would not have gone all lengths in the direction of +"emboîtement." In a well-known note to Laurillard's "Éloge," prefixed to +the last edition of the "Ossemens fossiles," the "radical de l'être" is +much the same thing as Aristotle's "particula genitalis" and Harvey's +"ovum." [Footnote: "M. Cuvier considérant que tous les êtres organisés sont +dérivés de parens, et ne voyant dans la nature aucune force capable de +produire l'organisation, croyait à la pré-existence des germes; non pas à +la pré-existence d'un être tout formé, puisqu'il est bien évident que ce +n'est que par des développemens successifs que l'être acquiert sa forme; +mais, si l'on peut s'exprimer ainsi, à la pré-existence du _radical de +l'être_, radical qui existe avant que la série des évolutions ne +commence, et qui remonte certainement, suivant la belle observation de +Bonnet, à plusieurs generations."--Laurillard, _Éloge de Cuvier_, note +12.] + +Bonnet's eminent contemporary, Buffon, held nearly the same views with +respect to the nature of the germ, and expresses them even more +confidently. + +"Ceux qui ont cru que le coeur étoit le premier formé, se sont trompés; +ceux qui disent que c'est le sang se trompent aussi: tout est formé en même +temps. Si l'on ne consulte que l'observation, le poulet se voit dans l'oeuf +avant qu'il ait été couvé." [Footnote: _Histoire Naturelle_, tom. ii. +ed. ii. 1750, p. 350.] + +"J'ai ouvert une grande quantité d'oeufs à differens temps avant et après +l'incubation, et je me suis convaincu par mes yeux que le poulet existe en +entier dans le milieu de la cicatricule au moment qu'il sort du corps de la +poule." [Footnote: _Ibid_., p. 351.] + +The "moule intérieur" of Buffon is the aggregate of elementary parts which +constitute the individual, and is thus the equivalent of Bonnet's germ, +[Footnote: See particularly Buffon, _l. c._ p. 41.] as defined in the +passage cited above. But Buffon further imagined that innumerable +"molecules organiques" are dispersed throughout the world, and that +alimentation consists in the appropriation by the parts of an organism of +those molecules which are analogous to them. Growth, therefore, was, on +this hypothesis, a process partly of simple evolution, and partly of what +has been termed "syngenesis." Buffon's opinion is, in fact, a sort of +combination of views, essentially similar to those of Bonnet, with others, +somewhat similar to those of the "Medici" whom Harvey condemns. The +"molecules organiques" are physical equivalents of Leibnitz's "monads." + +It is a striking example of the difficulty of getting people to use their +own powers of investigation accurately, that this form of the doctrine of +evolution should have held its ground so long; for it was thoroughly and +completely exploded, not long after its enunciation, by Casper Friederich +Wolff, who in his "Theoria Generationis," published in 1759, placed the +opposite theory of epigenesis upon the secure foundation of fact, from +which it has never been displaced. But Wolff had no immediate successors. +The school of Cuvier was lamentably deficient in embryologists; and it was +only in the course of the first thirty years of the present century, that +Prévost and Dumas in France, and, later on, Döllinger, Pander, Von Bär, +Rathke, and Remak in Germany, founded modern embryology; while, at the same +time, they proved the utter incompatibility of the hypothesis of evolution, +as formulated by Bonnet and Haller, with easily demonstrable facts. + +Nevertheless, though the conceptions originally denoted by "evolution" and +"development" were shown to be untenable, the words retained their +application to the process by which the embryos of living beings gradually +make their appearance; and the terms "Development," "Entwickelung," and +"Evolutio," are now indiscriminately used for the series of genetic changes +exhibited by living beings, by writers who would emphatically deny that +"Development" or "Entwickelung" or "Evolutio," in the sense in which these +words were usually employed by Bonnet or by Haller, ever occurs. + +Evolution, or development, is, in fact, at present employed in biology as a +general name for the history of the steps by which any living being has +acquired the morphological and the physiological characters which +distinguish it. As civil history may be divided into biography, which is +the history of individuals, and universal history, which is the history of +the human race, so evolution falls naturally into two categories--the +evolution of the individual, and the evolution of the sum of living beings. +It will be convenient to deal with the modern doctrine of evolution under +these two heads. + +I. _The Evolution of the Individual_. + +No exception is at this time, known to the general law, established upon an +immense multitude of direct observations, that every living thing is +evolved from a particle of matter in which no trace of the distinctive +characters of the adult form of that living thing is discernible. This +particle is termed a _germ_. Harvey [Footnote: _Execitationes de +Generatione_. Ex. 62, "Ovum esse primordium commune omnibus +animalibus."] says-- + +"Omnibus viventibus primordium insit, ex quo et a quo proveniant. Liceat +hoc nobis _primordium vegetale_ nominare; nempe substantiam quandam +corpoream vitam habentem potentiâ; vel quoddam per se existens, quod aptum +sit, in vegetativam formam, ab interno principio operante, mutari. Quale +nempe primordium, ovum est et plantarum semen; tale etiam viviparorum +conceptus, et insectorum _vermis_ ab Aristotele dictus: diversa +scilicet diversorum viventium primordia." + +The definition of a germ as "matter potentially alive, and having within +itself the tendency to assume a definite living form," appears to meet all +the requirements of modern science. For, notwithstanding it might be justly +questioned whether a germ is not merely potentially, but rather actually, +alive, though its vital manifestations are reduced to a minimum, the term +"potential" may fairly be used in a sense broad enough to escape the +objection. And the qualification of "potential" has the advantage of +reminding us that the great characteristic of the germ is not so much what +it is, but what it may, under suitable conditions, become. Harvey shared +the belief of Aristotle--whose writings he so often quotes and of whom he +speaks as his precursor and model, with the generous respect with which one +genuine worker should regard another--that such germs may arise by a +process of "equivocal generation" out of not-living matter; and the +aphorism so commonly ascribed to him, "_omne vivum ex ovo_" and which +is indeed a fair summary of his reiterated assertions, though incessantly +employed against the modern advocates of spontaneous generation, can be +honestly so used only by those who have never read a score of pages of the +"Exercitationes." Harvey, in fact, believed as implicitly as Aristotle did +in the equivocal generation of the lower animals. But, while the course of +modern investigation has only brought out into greater prominence the +accuracy of Harvey's conception of the nature and mode of development of +germs, it has as distinctly tended to disprove the occurrence of equivocal +generation, or abiogenesis, in the present course of nature. In the immense +majority of both plants and animals, it is certain that the germ is not +merely a body in which life is dormant or potential, but that it is itself +simply a detached portion of the substance of a pre-existing living body; +and the evidence has yet to be adduced which will satisfy any cautious +reasoner that "omne vivum ex vivo" is not as well-established a law of the +existing course of nature as "omne vivum ex ovo." + +In all instances which have yet been investigated, the substance of this +germ has a peculiar chemical composition, consisting of at fewest four +elementary bodies, viz., carbon, hydrogen, oxygen, and nitrogen, united +into the ill-defined compound known as protein, and associated with much +water, and very generally, if not always, with sulphur and phosphorus in +minute proportions. Moreover, up to the present time, protein is known only +as a product and constituent of living matter. Again, a true germ is either +devoid of any structure discernible by optical means, or, at most, it is a +simple nucleated cell. [Footnote: In some cases of sexless multiplication +the germ is a cell-aggregate--if we call germ only that which is already +detached from the parent organism.] + +In all cases the process of evolution consists in a succession of changes +of the form, structure, and functions of the germ, by which it passes, step +by step, from an extreme simplicity, or relative homogeneity, of visible +structure, to a greater or less degree of complexity or heterogeneity; and +the course of progressive differentiation is usually accompanied by growth, +which is effected by intussusception. This intussusception, however, is a +very different process from that imagined either by Buffon or by Bonnet. +The substance by the addition of which the germ is enlarged is in no case +simply absorbed, ready-made, from the not-living world and packed between +the elementary constituents of the germ, as Bonnet imagined; still less +does it consist of the "molecules organiques" of Buffon. The new material +is, in great measure, not only absorbed but assimilated, so that it becomes +part and parcel of the molecular structure of the living body into which it +enters. And, so far from the fully developed organism being simply the germ +_plus_ the nutriment which it has absorbed, it is probable that the +adult contains neither in form, nor in substance, more than an +inappreciable fraction of the constituents of the germ, and that it is +almost, if not wholly, made up of assimilated and metamorphosed nutriment. +In the great majority of cases, at any rate, the full-grown organism +becomes what it is by the absorption of not-living matter, and its +conversion into living matter of a specific type. As Harvey says (Ex. 45), +all parts of the body are nourished "ab eodem succo alibili, aliter +aliterque cambiato," "ut plantæ omnes ex eodem communi nutrimento (sive +rore seu terræ humore)." + +In all animals and plants above the lowest the germ is a nucleated cell, +using that term in its broadest sense; and the first step in the process of +the evolution of the individual is the division of this cell into two or +more portions. The process of division is repeated, until the organism, +from being unicellular, becomes multicellular. The single cell becomes a +cell-aggregate; and it is to the growth and metamorphosis of the cells of +the cell-aggregate thus produced, that all the organs and tissues of the +adult owe their origin. + +In certain animals belonging to every one of the chief groups into which +the _Metazoa_ are divisible, the cells of the cell-aggregate which +results from the process of yelk-division, and which is termed a +_morula_, diverge from one another in such a manner as to give rise to +a central space, around which they dispose themselves as a coat or +envelope; and thus the morula becomes a vesicle filled with fluid, the +_planula_. The wall of the planula is next pushed in on one side, or +invaginated, whereby it is converted into a double-walled sac with an +opening, the _blastopore_, which leads into the cavity lined by the +inner wall. This cavity is the primitive alimentary cavity or +_archenteron_; the inner or invaginated layer is the _hypoblast_; +the outer the _epiblast_; and the embryo, in this stage, is termed a +_gastrula_. In all the higher animals a layer of cells makes its +appearance between the hypoblast and the epiblast, and is termed the +_mesoblast_. In the further course of development the epiblast becomes +the ectoderm or epidermic layer of the body; the hypoblast becomes the +epithelium of the middle portion of the alimentary canal; and the mesoblast +gives rise to all the other tissues, except the central nervous system, +which originates from an ingrowth of the epiblast. + +With more or less modification in detail, the embryo has been observed to +pass through these successive evolutional stages in sundry Sponges, +Coelenterates, Worms, Echinoderms, Tunicates, Arthropods, Mollusks, and +Vertebrates; and there are valid reasons for the belief that all animals of +higher organisation than the _Protozoa_, agree in the general +character of the early stages of their individual evolution. Each, starting +from the condition of a simple nucleated cell, becomes a cell-aggregate; +and this passes through a condition which represents the gastrula stage, +before taking on the features distinctive of the group to which it belongs. +Stated in this form, the "gastræa theory" of Haeckel appears to the present +writer to be one of most important and best founded of recent +generalisations. So far as individual plants and animals are concerned, +therefore, evolution is not a speculation but a fact; and it takes place by +epigenesis. + +"Animal...per _epigenesin_ procreatur, materiam simul attrahit, parat, +concoquit, et eâdem utitur; formatur simul et augetur ... primum futuri +corporis concrementum ... prout augetur, dividitur sensim et distinguitur +in partes, non simul omnes, sed alias post alias natas, et ordine quasque +suo emergentes." [Footnote: Harvey, _Exercitationes de Generatione_. +Ex. 45, "Quænam sit pulli materia et quomodo fiat in Ovo."] In these words, +by the divination of genius, Harvey, in the seventeenth century, summed up +the outcome of the work of all those who, with appliances he could not +dream of, are continuing his labours in the nineteenth century. + +Nevertheless, though the doctrine of epigenesis, as understood by Harvey, +has definitively triumphed over the doctrine of evolution, as understood by +his opponents of the eighteenth century, it is not impossible that, when +the analysis of the process of development is carried still further, and +the origin of the molecular components of the physically gross, though +sensibly minute, bodies which we term germs is traced, the theory of +development will approach more nearly to metamorphosis than to epigenesis. +Harvey thought that impregnation influenced the female organism as a +contagion; and that the blood, which he conceived to be the first rudiment +of the germ, arose in the clear fluid of the "colliquamentum" of the ovum +by a process of concrescence, as a sort of living precipitate. We now know, +on the contrary, that the female germ or ovum, in all the higher animals +and plants, is a body which possesses the structure of a nucleated cell; +that impregnation consists in the fusion of the substance [Footnote: [At +any rate of the nuclei of the two germ-cells. 1893]] of another more or +less modified nucleated cell, the male germ, with the ovum; and that the +structural components of the body of the embryo are all derived, by a +process of division, from the coalesced male and female germs. Hence it is +conceivable, and indeed probable, that every part of the adult contains +molecules, derived both from the male and from the female parent; and that, +regarded as a mass of molecules, the entire organism may he compared to a +web of which the warp is derived from the female and the woof from the +male. And each of these may constitute one individuality, in the same sense +as the whole organism is one individual, although the matter of the +organism has been constantly changing. The primitive male and female +molecules may play the part of Buffon's "moules organiques," and mould the +assimilated nutriment, each according to its own type, into innumerable new +molecules. From this point of view the process, which, in its superficial +aspect, is epigenesis, appears in essence, to be evolution, in the modified +sense adopted in Bonnet's later writings; and development is merely the +expansion of a potential organism or "original preformation" according to +fixed laws. + +II. _The Evolution of the Sum of Living Beings_. + +The notion that all the kinds of animals and plants may have come into +existence by the growth and modification of primordial germs is as old as +speculative thought; but the modern scientific form of the doctrine can be +traced historically to the influence of several converging lines of +philosophical speculation and of physical observation, none of which go +farther back than the seventeenth century. These are:-- + +1. The enunciation by Descartes of the conception that the physical +universe, whether living or not living, is a mechanism, and that, as such, +it is explicable on physical principles. + +2. The observation of the gradations of structure, from extreme simplicity +to very great complexity, presented by living things, and of the relation +of these graduated forms to one another. + +3. The observation of the existence of an analogy between the series of +gradations presented by the species which compose any great group of +animals or plants, and the series of embryonic conditions of the highest +members of that group. + +4. The observation that large groups of species of widely different habits +present the same fundamental plan of structure; and that parts of the same +animal or plant, the functions of which are very different, likewise +exhibit modifications of a common plan. + +5. The observation of the existence of structures, in a rudimentary and +apparently useless condition, in one species of a group, which are fully +developed and have definite functions in other species of the same group. + +6. The observation of the effects of varying conditions in modifying living +organisms. + +7. The observation of the facts of geographical distribution. + +8. The observation of the facts of the geological succession of the forms +of life. + +1. Notwithstanding the elaborate disguise which fear of the powers that +were led Descartes to throw over his real opinions, it is impossible to +read the "Principes de la Philosophie" without acquiring the conviction +that this great philosopher held that the physical world and all things in +it, whether living or not living, have originated by a process of +evolution, due to the continuous operation of purely physical causes, out +of a primitive relatively formless matter. [Footnote: As Buffon has well +said:--"L'idée de ramener l'explication de tous les phénomènes à des +principes mecaniques est assurement grande et belle, ce pas est le plus +hardi qu'on peut faire en philosophie, et c'est Descartes qui l'a +fait."--_l. c._ p. 50.] + +The following passage is especially instructive:-- + +"Et tant s'en faut que je veuille que l'on croie toutes les choses que +j'écrirai, que même je pretends en proposer ici quelques unes que je crois +absolument être fausses; à savoir, je ne doute point quo le monde n'ait été +créé au commencement avec autant de perfection qu'il eu a; en sorte que le +soleil, la terre, la lune, et les étoiles ont été dès lors; et que la terre +n'a pas eu seulement en soi les semences des plantes, mais que les plantes +même en ont couvert une partie; et qu' Adam et Eve n'ont pas été créés +enfans mais en âge d'hommes parfaits. La religion chrétienne veut que nous +le croyons ainsi, et la raison naturelle nous persuade entièrement cette +vérité; car si nous considérons la toute puissance de Dieu, nous devons +juger que tout ce qu'il a fait a eu dès le commencement toute la perfection +qu'il devoit avoir. Mais néanmoins, comme on connôitroit beaucoup mieux +quelle a été la nature d'Adam et celle des arbres de Paradis si on avoit +examiné comment les enfants se forment peu à peu dans le ventre de leurs +mères et comment les plantes sortent de leurs semences, que si on avoit +seulement considéré quels ils ont été quand Dieu les a créés: tout de même, +nous ferons mieux entendre quelle est généralement la nature de toutes les +choses qui sont au monde si nous pouvons imaginer quelques principes qui +soient fort intelligibles et fort simples, desquels nous puissions voir +clairement que les astres et la terre et enfin tout ce monde visible auroit +pu être produit ainsi que de quelques semences (bien que, nous sachions +qu'il n'a pas été produit en cette façon) que si nous la decrivions +seulement comme il est, ou bien comme nous croyons qu'il a été créé. Et +parceque je pense avoir trouvé des principes qui sont tels, je tacherai ici +de les expliquer." [Footnote: _Principes de la Philosophie_, Troisième +partie, § 45.] + +If we read between the lines of this singular exhibition of force of one +kind and weakness of another, it is clear that Descartes believed that he +had divined the mode in which the physical universe had been evolved; and +the "Traité de l'Homme," and the essay "Sur les Passions" afford abundant +additional evidence that he sought for, and thought he had found, an +explanation of the phenomena of physical life by deduction from purely +physical laws. + +Spinoza abounds in the same sense, and is as usual perfectly candid-- + +"Naturæ leges et regulæ, secundum quas omnia fiunt et ex unis formis in +alias mutantur, sunt ubique et semper eadem." [Footnote: _Ethices_, +Pars tertia, Præfatio.] Leibnitz's doctrine of continuity necessarily led +him in the same direction; and, of the infinite multitude of monads with +which he peopled the world, each is supposed to be the focus of an endless +process of evolution and involution. In the "Protogæa," xxvi., Leibnitz +distinctly suggests the mutability of species-- + +"Alii mirantur in saxis passim species videri quas vel in orbe cognito, vel +saltem in vicinis locis frustra quæras. 'Ita Cornua Ammonis,' quæ ex +nautilorum numero habeantur, passim et forma et magnitudine (nam et pedali +diametro aliquando reperiuntur) ab omnibus illis naturis discrepare dicunt, +quas præbet mare. Sed quis absconditos ejus recessus aut subterraneas +abyssos pervestigavit? quam multa nobis animalia antea ignota offert novus +orbis? Et credibile est per magnas illas conversiones etiam animalium +species plurimum immutatas." + +Thus, in the end of the seventeenth century, the seed was sown which has, +at intervals, brought forth recurrent crops of evolutional hypotheses, +based, more or less completely, on general reasonings. + +Among the earliest of these speculations is that put forward by Benoit de +Maillet in his "Telliamed," which, though printed in 1735, was not +published until twenty-three years later. Considering that this book was +written before the time of Haller, or Bonnet, or Linnæus, or Hutton, it +surely deserves more respectful consideration than it usually receives. For +De Maillet not only has a definite conception of the plasticity of living +things, and of the production of existing species by the modification of +their predecessors; but he clearly apprehends the cardinal maxim of modern +geological science, that the explanation of the structure of the globe is +to be sought in the deductive application to geological phenomena of the +principles established inductively by the study of the present course of +nature. Somewhat later, Maupertuis [Footnote: _Système de la Nature_. +"Essai sur la Formation des Corps Organisés," 1751, xiv.] suggested a +curious hypothesis as to the causes of variation, which he thinks may be +sufficient to account for the origin of all animals from a single pair. +Robinet [Footnote: _Considérations Philosophiques sur la gradation +naturelle des formes de l'être; ou les essais de la nature qui apprend a +faire l'homme,_ 1768.] followed out much the same line of thought as De +Maillet, but less soberly; and Bonnet's speculations in the "Palingénésie," +which appeared in 1769, have already been mentioned. Buffon (1753-1778), at +first a partisan of the absolute immutability of species, subsequently +appears to have believed that larger or smaller groups of species have been +produced by the modification of a primitive stock; but he contributed +nothing to the general doctrine of evolution. + +Erasmus Darwin ("Zoonomia," 1794), though a zealous evolutionist, can +hardly be said to have made any real advance on his predecessors; and, +notwithstanding that Goethe (1791-4) had the advantage of a wide knowledge +of morphological facts, and a true insight into their signification, while +he threw all the power of a great poet into the expression of his +conceptions, it may be questioned whether he supplied the doctrine of +evolution with a firmer scientific basis than it already possessed. +Moreover, whatever the value of Goethe's labours in that field, they were +not published before 1820, long after evolutionism had taken a new +departure from the works of Treviranus and Lamarck--the first of its +advocates who were equipped for their task with the needful large and +accurate knowledge of the phenomena of life, as a whole. It is remarkable +that each of these writers seems to have been led, independently and +contemporaneously, to invent the same name of "Biology" for the science of +the phenomena of life; and thus, following Buffon, to have recognised the +essential unity of these phenomena, and their contradistinction from those +of inanimate nature. And it is hard to say whether Lamarck or Treviranus +has the priority in propounding the main thesis of the doctrine of +evolution; for though the first volume of Treviranus's "Biologie" appeared +only in 1802, he says, in the preface to his later work, the "Erscheinungen +und Gesetze des organischen Lebens," dated 1831, that he wrote the first +volume of the "Biologie" "nearly five-and-thirty years ago," or about 1796. + +Now, in 1794, there is evidence that Lamarck held doctrines which present a +striking contrast to those which are to be found in the "Philosophie +Zoologique," as the following passages show:-- + +"685. Quoique mon unique objet dans cet article n'ait été que de traiter de +la cause physique de l'entretien de la vie des êtres organiques, malgré +cela j'ai osé avancer en débutant, que l'existence de ces êtres étonnants +n'appartiennent nullement à la nature; que tout ce qu'on peut entendre par +le mot _nature_, ne pouvoit donner la vie, c'est-à-dire, que toutes +les qualités de la matière, jointes à toutes les circonstances possibles, +et même à l'activité répandue dans l'univers, ne pouvaient point produire +un être muni du mouvement organique, capable de reproduire son semblable, +et sujet à la mort. + +"686. Tous les individus de cette nature, qui existent, proviennent +d'individus semblables qui tous ensemble constituent l'espèce entière. Or, +je crois qu'il est aussi impossible à l'homme de connôitre la cause +physique du premier individu de chaque espèce, que d'assigner aussi +physiquement la cause de l'existence de la matière ou de l'univers entier. +C'est au moins ce que le résultat de mes connaissances et de mes réflexions +me portent à penser. S'il existe beaucoup de variétés produites par l'effet +des circonstances, ces variétés ne denaturent point les espèces; mais on se +trompe, sans doute souvent, en indiquant comme espèce, ce qui n'est que +variété; et alors je sens que cette erreur peut tirer à conséquence dans +les raisonnements que l'on fait sur cette matière." [Footnote: +_Recherches sur les causes des principaux faits physiques_, par J.B. +Lamarck. Paris. Seconde année de la République. In the preface, Lamarck +says that the work was written in 1776, and presented to the Academy in +1780; but it was not published before 17994, and, at that time, it +presumably expressed Lamarck's mature views. It would be interesting to +know what brought about the change of opinion manifested in the +_Recherches sur l'organisation des corps vivants_, published only +seven years later.] + +The first three volumes of Treviranus's "Biologie," which contain his +general views of evolution, appeared between 1802 and 1805. The "Recherches +sur l'organisation des corps vivants," in which the outlines of Lamarck's +doctrines are given, was published in 1802, but the full development of his +views, in the "Philosophie Zoologique," did not take place until 1809. + +The "Biologie" and the "Philosophie Zoologique" are both very remarkable +productions, and are still worthy of attentive study, but they fell upon +evil times. The vast authority of Cuvier was employed in support of the +traditionally respectable hypotheses of special creation and of +catastrophism; and the wild speculations of the "Discours sur les +Révolutions de la Surface du Globe" were held to be models of sound +scientific thinking, while the really much more sober and philosophical +hypotheses of the "Hydrogeologie" were scouted. For many years it was the +fashion to speak of Lamarck with ridicule, while Treviranus was altogether +ignored. + +Nevertheless, the work had been done. The conception of evolution was +henceforward irrepressible, and it incessantly reappears, in one shape or +another, [Footnote: See the "Historical Sketch" prefixed to the last +edition of the _Origin of Species_.] up to the year 1858, when Mr. +Darwin and Mr. Wallace published their "Theory of Natural Selection." The +"Origin of Species" appeared in 1859; and it is within the knowledge of all +whose memories go back to that time, that, henceforward, the doctrine of +evolution has assumed a position and acquired an importance which it never +before possessed. In the "Origin of Species," and in his other numerous and +important contributions to the solution of the problem of biological +evolution, Mr. Darwin confines himself to the discussion of the causes +which have brought about the present condition of living matter, assuming +such matter to have once come into existence. On the other hand, Mr. +Spencer [Footnote: _First Principles_. and _Principles of +Biology_, 1860-1864.] and Professor Haeckel [Footnote: _Generelle +Marphologie_, 1866.] have dealt with the whole problem of evolution. The +profound and vigorous writings of Mr. Spencer embody the spirit of +Descartes in the knowledge of our own day, and may be regarded as the +"Principes de la Philosophie" of the nineteenth century; while, whatever +hesitation may not unfrequently be felt by less daring minds, in following +Haeckel in many of his speculations, his attempt to systematise the +doctrine of evolution and to exhibit its influence as the central thought +of modern biology, cannot fail to have a far-reaching influence on the +progress of science. + +If we seek for the reason of the difference between the scientific position +of the doctrine of evolution a century ago, and that which it occupies now, +we shall find it in the great accumulation of facts, the several classes of +which have been enumerated above, under the second to the eighth heads. For +those which are grouped under the second to the seventh of these classes, +respectively, have a clear significance on the hypothesis of evolution, +while they are unintelligible if that hypothesis be denied. And those of +the eighth group are not only unintelligible without the assumption of +evolution, but can be proved never to be discordant with that hypothesis, +while, in some cases, they are exactly such as the hypothesis requires. The +demonstration of these assertions would require a volume, but the general +nature of the evidence on which they rest may be briefly indicated. + +2. The accurate investigation of the lowest forms of animal life, commenced +by Leeuwenhoek and Swammerdam, and continued by the remarkable labours of +Reaumur, Trembley, Bonnet, and a host of other observers, in the latter +part of the seventeenth and the first half of the eighteenth centuries, +drew the attention of biologists to the gradation in the complexity of +organisation which is presented by living beings, and culminated in the +doctrine of the "échelle des êtres," so powerfully and clearly stated by +Bonnet; and, before him, adumbrated by Locke and by Leibnitz. In the then +state of knowledge, it appeared that all the species of animals and plants +could be arranged in one series; in such a manner that, by insensible +gradations, the mineral passed into the plant, the plant into the polype, +the polype into the worm, and so, through gradually higher forms of life, +to man, at the summit of the animated world. + +But, as knowledge advanced, this conception ceased to be tenable in the +crude form in which it was first put forward. Taking into account existing +animals and plants alone, it became obvious that they fell into groups +which were more or less sharply separated from one another; and, moreover, +that even the species of a genus can hardly ever be arranged in linear +series. Their natural resemblances and differences are only to be expressed +by disposing them as if they were branches springing from a common +hypothetical centre. + +Lamarck, while affirming the verbal proposition that animals form a single +series, was forced by his vast acquaintance with the details of zoology to +limit the assertion to such a series as may be formed out of the +abstractions constituted by the common characters of each group. [Footnote: +"Il s'agit donc de prouver que la série qui constitue l'échelle animale +réside essentiellement dans la distribution des masses principales qui la +composent et non dans celle des espèces ni même toujours dans celle des +genres."--_Philosophie Zoologique_. chap. v.] + +Cuvier on anatomical, and Von Baer on embryological grounds, made the +further step of proving that, even in this limited sense, animals cannot be +arranged in a single series, but that there are several distinct plans of +organisation to be observed among them, no one of which, in its highest and +most complicated modification, leads to any of the others. + +The conclusions enunciated by Cuvier and Von Baer have been confirmed, in +principle, by all subsequent research into the structure of animals and +plants. But the effect of the adoption of these conclusions has been rather +to substitute a new metaphor for that of Bonnet than to abolish the +conception expressed by it. Instead of regarding living things as capable +of arrangement in one series like the steps of a ladder, the results of +modern investigation compel us to dispose them as if they were the twigs +and branches of a tree. The ends of the twigs represent individuals, the +smallest groups of twigs species, larger groups genera, and so on, until we +arrive at the source of all these ramifications of the main branch, which +is represented by a common plan of structure. At the present moment, it is +impossible to draw up any definition, based on broad anatomical or +developmental characters, by which any one of Cuvier's great groups shall +be separated from all the rest. On the contrary, the lower members of each +tend to converge towards the lower members of all the others. The same may +be said of the vegetable world. The apparently clear distinction between +flowering and flowerless plants has been broken down by the series of +gradations between the two exhibited by the _Lycopodiaceæ, +Rhizocarpeæ_, and _Gymnospermeæ_. The groups of _Fungi_, +_Lichenes_, and _Algæ_ have completely run into one another, and, +when the lowest forms of each are alone considered, even the animal and +vegetable kingdoms cease to have a definite frontier. + +If it is permissible to speak of the relations of living forms to one +another metaphorically, the similitude chosen must undoubtedly be that of a +common root, whence two main trunks, one representing the vegetable and one +the animal world, spring; and, each dividing into a few main branches, +these subdivide into multitudes of branchlets and these into smaller groups +of twigs. + +As Lamarck has well said--[Footnote: _Philosophie Zoologique_, +première partie, chap. iii.] "Il n'y a que ceux qui se sont longtemps et +fortement occupés de la détermination des espèces, et qui ont consulté de +riches collections, qui peuvent savoir jusqu'à quel point les +_espèces_, parmi les corps vivants se fondent les unes dans les +autres, et qui ont pu se convaincre que, dans les parties où nous voyons +des _espèces_ isolès, cela n'est ainsi que parcequ'il nous en manque +d'autres qui en sont plus voisines et que nous n'avons pas encore +recueillies. + +"Je ne veux pas dire pour cela que les animaux qui existent forment une +série très-simple et partout également nuancée; mais je dis qu'ils forment +une série ramense, irréguliérement graduée et qui n'a point de +discontinuité dans ses parties, ou qui, du moins, n'en a toujours pas eu, +s'il est vrai que, par suite de quelques espèces perdues, il s'en trouve +quelque part. Il en resulte que les _espèces_ qui terminent chaque +rameau de la série générale tiennent, au moins d'un côté, à d'autres +espèces voisines qui se nuancent avec elles. Voilà ce que l'état bien connu +des choses me met maintenant à portée de demontrer. Je n'ai besoin d'aucune +hypothèse ni d'aucune supposition pour cela: j'en atteste tous les +naturalistes observateurs." + +3. In a remarkable essay [Footnote: "Entwurf einer Darstellung der zwischen +dem Embryozustände der höheren Thiere und dem permanenten der niederen +stattfindenden Parallele," _Beyträge zur Vergleichenden Anatomie_, Bd. +ii. 1811.] Meckel remarks-- + +"There is no good physiologist who has not been struck by the observation +that the original form of all organisms is one and the same, and that out +of this one form, all, the lowest as well as the highest, are developed in +such a manner that the latter pass through the permanent forms of the +former as transitory stages. Aristotle, Haller, Harvey, Kielmeyer, +Autenrieth, and many others, have either made this observation +incidentally, or, especially the latter, have drawn particular attention to +it, and deduced therefrom results of permanent importance for physiology." + +Meckel proceeds to exemplify the thesis, that the lower forms of animals +represent stages in the course of the development of the higher, with a +large series of illustrations. + +After comparing the Salamanders and the perennibranchiate _Urodela_ +with the Tadpoles and the Frogs, and enunciating the law that the more +highly any animal is organised the more quickly does it pass through the +lower stages, Meckel goes on to say-- + +"From these lowest Vertebrata to the highest, and to the highest forms +among these, the comparison between the embryonic conditions of the higher +animals and the adult states of the lower can be more completely and +thoroughly instituted than if the survey is extended to the Invertebrata, +inasmuch as the latter are in many respects constructed upon an altogether +too dissimilar type; indeed they often differ from one another far more +than the lowest vertebrate does from the highest mammal; yet the following +pages will show that the comparison may also be extended to them with +interest. In fact, there is a period when, as Aristotle long ago said, the +embryo of the highest animal has the form of a mere worm; and, devoid of +internal and external organisation, is merely an almost structureless lump +of polype substance. Notwithstanding the origin of organs, it still for a +certain time, by reason of its want of an internal bony skeleton, remains +worm and mollusk, and only later enters into the series of the Vertebrata, +although traces of the vertebral column even in the earliest periods +testify its claim to a place in that series."--_Op, cit_ pp. 4, 5. + +If Meckel's proposition is so far qualified, that the comparison of adult +with embryonic forms is restricted within the limits of one type of +organisation; and, if it is further recollected that the resemblance +between the permanent lower form and the embryonic stage of a higher form +is not special but general, it is in entire accordance with modern +embryology; although there is no branch of biology which has grown so +largely, and improved its methods so much, since Meckel's time, as this. In +its original form, the doctrine of "arrest of development," as advocated by +Geoffroy Saint-Hilaire and Serres, was no doubt an overstatement of the +case. It is not true, for example, that a fish is a reptile arrested in its +development, or that a reptile was ever a fish: but it is true that the +reptile embryo, at one stage of its development, is an organism which, if +it had an independent existence, must be classified among fishes; and all +the organs of the reptile pass, in the course of their development, through +conditions which are closely analogous to those which are permanent in some +fishes. + +4. That branch of biology which is termed Morphology is a commentary upon, +and expansion of, the proposition that widely different animals or plants, +and widely different parts of animals or plants, are constructed upon the +same plan. From the rough comparison of the skeleton of a bird with that of +a man by Belon, in the sixteenth century (to go no farther back), down to +the theory of the limbs and the theory of the skull at the present day; or, +from the first demonstration of the homologies of the parts of a flower by +C. F. Wolff, to the present elaborate analysis of the floral organs, +morphology exhibits a continual advance towards the demonstration of a +fundamental unity among the seeming diversities of living structures. And +this demonstration has been completed by the final establishment of the +cell theory, which involves the admission of a primitive conformity, not +only of all the elementary structures in animals and plants respectively, +but of those in the one of these great divisions of living things with +those in the other. No _à priori_ difficulty can be said to stand in +the way of evolution, when it can be shown that all animals and all plants +proceed by modes of development, which are similar in principle, from a +fundamental protoplasmic material. + +5. The innumerable cases of structures, which are rudimentary and +apparently useless, in species, the close allies of which possess +well-developed and functionally important homologous structures, are +readily intelligible on the theory of evolution, while it is hard to +conceive their _raison d'être_ on any other hypothesis. However, a +cautious reasoner will probably rather explain such cases deductively from +the doctrine of evolution than endeavour to support the doctrine of +evolution by them. For it is almost impossible to prove that any structure, +however rudimentary, is useless--that is to say, that it plays no part +whatever in the economy; and, if it is in the slightest degree useful, +there is no reason why, on the hypothesis of direct creation, it should not +have been created. Nevertheless, double-edged as is the argument from +rudimentary organs, there is probably none which has produced a greater +effect in promoting the general acceptance of the theory of evolution. + +6. The older advocates of evolution sought for the causes of the process +exclusively in the influence of varying conditions, such as climate and +station, or hybridisation, upon living forms. Even Treviranus has got no +farther than this point. Lamarck introduced the conception of the action of +an animal on itself as a factor in producing modification. Starting from +the well-known fact that the habitual use of a limb tends to develop the +muscles of the limb, and to produce a greater and greater facility in using +it, he made the general assumption that the effort of an animal to exert an +organ in a given direction tends to develop the organ in that direction. +But a little consideration showed that, though Lamarck had seized what, as +far it goes, is a true cause of modification, it is a cause the actual +effects of which are wholly inadequate to account for any considerable +modification in animals, and which can have no influence at all in the +vegetable world; and probably nothing contributed so much to discredit +evolution, in the early part of this century, as the floods of easy +ridicule which were poured upon this part of Lamarck's speculation. The +theory of natural selection, or survival of the fittest, was suggested by +Wells in 1813, and further elaborated by Matthew in 1831. But the pregnant +suggestions of these writers remained practically unnoticed and forgotten, +until the theory was independently devised and promulgated by Darwin and +Wallace in 1858, and the effect of its publication was immediate and +profound. + +Those who were unwilling to accept evolution, without better grounds than +such as are offered by Lamarck, or the author of that particularly +unsatisfactory book, the "Vestiges of the Natural History of the Creation," +and who therefore preferred to suspend their judgment on the question, +found in the principle of selective breeding, pursued in all its +applications with marvellous knowledge and skill by Mr. Darwin, a valid +explanation of the occurrence of varieties and races; and they saw clearly +that, if the explanation would apply to species, it would not only solve +the problem of their evolution, but that it would account for the facts of +teleology, as well as for those of morphology; and for the persistence of +some forms of life unchanged through long epochs of time, while others +undergo comparatively rapid metamorphosis. + +How far "natural selection" suffices for the production of species remains +to be seen. Few can doubt that, if not the whole cause, it is a very +important factor in that operation; and that it must play a great part in +the sorting out of varieties into those which are transitory and those +which are permanent. + +But the causes and conditions of variation have yet to be thoroughly +explored; and the importance of natural selection will not be impaired, +even if further inquiries should prove that variability is definite, and is +determined in certain directions rather than in others, by conditions +inherent in that which varies. It is quite conceivable that every species +tends to produce varieties of a limited number and kind, and that the +effect of natural selection is to favour the development of some of these, +while it opposes the development of others along their predetermined lines +of modification. + +7. No truths brought to light by biological investigation were better +calculated to inspire distrust of the dogmas intruded upon science in the +name of theology, than those which relate to the distribution of animals +and plants on the surface of the earth. Very skilful accommodation was +needful, if the limitation of sloths to South America, and of the +ornithorhynchus to Australia, was to be reconciled with the literal +interpretation of the history of the deluge; and with the establishment of +the existence of distinct provinces of distribution, any serious belief in +the peopling of the world by migration from Mount Ararat came to an end. + +Under these circumstances, only one alternative was left for those who +denied the occurrence of evolution--namely, the supposition that the +characteristic animals and plants of each great province were created as +such, within the limits in which we find them. And as the hypothesis of +"specific centres," thus formulated, was heterodox from the theological +point of view, and unintelligible under its scientific aspect, it may be +passed over without further notice, as a phase of transition from the +creational to the evolutional hypothesis. + +8. In fact, the strongest and most conclusive arguments in favour of +evolution are those which are based upon the facts of geographical, taken +in conjunction with those of geological, distribution. + +Both Mr. Darwin and Mr. Wallace lay great stress on the close relation +which obtains between the existing fauna of any region and that of the +immediately antecedent geological epoch in the same region; and rightly, +for it is in truth inconceivable that there should be no genetic connection +between the two. It is possible to put into words the proposition that all +the animals and plants of each geological epoch were annihilated and that a +new set of very similar forms was created for the next epoch; but it may be +doubted if any one who ever tried to form a distinct mental image of this +process of spontaneous generation on the grandest scale, ever really +succeeded in realising it. + +Within the last twenty years, the attention of the best palæontologists has +been withdrawn from the hodman's work of making "new species" of fossils, +to the scientific task of completing our knowledge of individual species, +and tracing out the succession of the forms presented by any given type in +time. + +Those who desire to inform themselves of the nature and extent of the +evidence bearing on these questions may consult the works of Rütimeyer, +Gaudry, Kowalewsky, Marsh, and the writer of the present article. It must +suffice, in this place, to say that the successive forms of the Equine type +have been fully worked out; while those of nearly all the other existing +types of Ungulate mammals and of the _Carnivora_ have been almost as +closely followed through the Tertiary deposits; the gradations between +birds and reptiles have been traced; and the modifications undergone by the +_Crocodilia_, from the Triassic epoch to the present day, have been +demonstrated. On the evidence of palæontology, the evolution of many +existing forms of animal life from their predecessors is no longer an +hypothesis, but an historical fact; it is only the nature of the +physiological factors to which that evolution is due which is still open to +discussion. + +[At page 209, the reference to Erasmus Darwin does not do justice to that +ingenious writer, who, in the 39th section of the _Zoonomia_, clearly +and repeatedly enunciates the theory of the inheritance of acquired +modifications. For example "From their first rudiment, or primordium, to +the termination of their lives, all animals undergo perpetual +transformations; which are in part produced by their own exertions in +consequence of their desires and aversions, of their pleasures and their +pains, or of irritation, or of associations; and many of these acquired +forms or propensities are transmitted to their posterity." _Zoonomia_ +I., p. 506. 1893.] + + + +VII + +THE COMING OF AGE OF "THE ORIGIN OF SPECIES" + +[1880] + + +Many of you will be familiar with the aspect of this small green-covered +book. It is a copy of the first edition of the "Origin of Species," and +bears the date of its production--the 1st of October 1859. Only a few +months, therefore, are needed to complete the full tale of twenty-one years +since its birthday. + +Those whose memories carry them back to this time will remember that the +infant was remarkably lively, and that a great number of excellent persons +mistook its manifestations of a vigorous individuality for mere +naughtiness; in fact there was a very pretty turmoil about its cradle. My +recollections of the period are particularly vivid, for, having conceived a +tender affection for a child of what appeared to me to be such remarkable +promise, I acted for some time in the capacity of a sort of under-nurse, +and thus came in for my share of the storms which threatened the very life +of the young creature. For some years it was undoubtedly warm work; but +considering how exceedingly unpleasant the apparition of the newcomer must +have been to those who did not fall in love with him at first sight, I +think it is to the credit of our age that the war was not fiercer, and that +the more bitter and unscrupulous forms of opposition died away as soon as +they did. + +I speak of this period as of something past and gone, possessing merely an +historical, I had almost said an antiquarian interest. For, during the +second decade of the existence of the "Origin of Species," opposition, +though by no means dead, assumed a different aspect. On the part of all +those who had any reason to respect themselves, it assumed a thoroughly +respectful character. By this time, the dullest began to perceive that the +child was not likely to perish of any congenital weakness or infantile +disorder, but was growing into a stalwart personage, upon whom mere goody +scoldings and threatenings with the birch-rod were quite thrown away. + +In fact, those who have watched the progress of science within the last ten +years will bear me out to the full, when I assert that there is no field of +biological inquiry in which the influence of the "Origin of Species" is not +traceable; the foremost men of science in every country are either avowed +champions of its leading doctrines, or at any rate abstain from opposing +them; a host of young and ardent investigators seek for and find +inspiration and guidance in Mr. Darwin's great work; and the general +doctrine of evolution, to one side of which it gives expression, obtains, +in the phenomena of biology, a firm base of operations whence it may +conduct its conquest of the whole realm of Nature. + +History warns us, however, that it is the customary fate of new truths to +begin as heresies and to end as superstitions; and, as matters now stand, +it is hardly rash to anticipate that, in another twenty years, the new +generation, educated under the influences of the present day, will be in +danger of accepting the main doctrines of the "Origin of Species," with as +little reflection, and it may be with as little justification, as so many +of our contemporaries, twenty years ago, rejected them. + +Against any such a consummation let us all devoutly pray; for the +scientific spirit is of more value than its products, and irrationally held +truths may be more harmful than reasoned errors. Now the essence of the +scientific spirit is criticism. It tells us that whenever a doctrine claims +our assent we should reply, Take it if you can compel it. The struggle for +existence holds as much in the intellectual as in the physical world. A +theory is a species of thinking, and its right to exist is coextensive with +its power of resisting extinction by its rivals. + +From this point of view, it appears to me that it would be but a poor way +of celebrating the Coming of Age of the "Origin of Species," were I merely +to dwell upon the facts, undoubted and remarkable as they are, of its +far-reaching influence and of the great following of ardent disciples who +are occupied in spreading and developing its doctrines. Mere insanities and +inanities have before now swollen to portentous size in the course of +twenty years. Let us rather ask this prodigious change in opinion to +justify itself: let us inquire whether anything has happened since 1859, +which will explain, on rational grounds, why so many are worshipping that +which they burned, and burning that which they worshipped. It is only in +this way that we shall acquire the means of judging whether the movement we +have witnessed is a mere eddy of fashion, or truly one with the +irreversible current of intellectual progress, and, like it, safe from +retrogressive reaction. + +Every belief is the product of two factors: the first is the state of the +mind to which the evidence in favour of that belief is presented; and the +second is the logical cogency of the evidence itself. In both these +respects, the history of biological science during the last twenty years +appears to me to afford an ample explanation of the change which has taken +place; and a brief consideration of the salient events of that history will +enable us to understand why, if the "Origin of Species" appeared now, it +would meet with a very different reception from that which greeted it in +1859. + +One-and-twenty years ago, in spite of the work commenced by Hutton and +continued with rare skill and patience by Lyell, the dominant view of the +past history of the earth was catastrophic. Great and sudden physical +revolutions, wholesale creations and extinctions of living beings, were the +ordinary machinery of the geological epic brought into fashion by the +misapplied genius of Cuvier. It was gravely maintained and taught that the +end of every geological epoch was signalised by a cataclysm, by which every +living being on the globe was swept away, to be replaced by a brand-new +creation when the world returned to quiescence. A scheme of nature which +appeared to be modelled on the likeness of a succession of rubbers of +whist, at the end of each of which the players upset the table and called +for a new pack, did not seem to shock anybody. + +I may be wrong, but I doubt if, at the present time, there is a single +responsible representative of these opinions left. The progress of +scientific geology has elevated the fundamental principle of +uniformitarianism, that the explanation of the past is to be sought in the +study of the present, into the position of an axiom; and the wild +speculations of the catastrophists, to which we all listened with respect a +quarter of a century ago, would hardly find a single patient hearer at the +present day. No physical geologist now dreams of seeking, outside the range +of known natural causes, for the explanation of anything that happened +millions of years ago, any more than he would be guilty of the like +absurdity in regard to current events. + +The effect of this change of opinion upon biological speculation is +obvious. For, if there have been no periodical general physical +catastrophes, what brought about the assumed general extinctions and +re-creations of life which are the corresponding biological catastrophes? +And, if no such interruptions of the ordinary course of nature have taken +place in the organic, any more than in the inorganic, world, what +alternative is there to the admission of evolution? + +The doctrine of evolution in biology is the necessary result of the logical +application of the principles of uniformitarianism to the phenomena of +life. Darwin is the natural successor of Hutton and Lyell, and the "Origin +of Species" the logical sequence of the "Principles of Geology." + +The fundamental doctrine of the "Origin of Species," as of all forms of the +theory of evolution applied to biology, is "that the innumerable species, +genera, and families of organic beings with which the world is peopled have +all descended, each within its own class or group, from common parents, and +have all been modified in the course of descent." [Footnote: _Origin of +Species_, ed. I, p. 457.] + +And, in view of the facts of geology, it follows that all living animals +and plants "are the lineal descendants of those which lived long before the +Silurian epoch." [Footnote: _Origin of Species_, p. 458.] + +It is an obvious consequence of this theory of descent with modification, +as it is sometimes called, that all plants and animals, however different +they may now be, must, at one time or other, have been connected by direct +or indirect intermediate gradations, and that the appearance of isolation +presented by various groups of organic beings must be unreal. + +No part of Mr. Darwin's work ran more directly counter to the +prepossessions of naturalists twenty years ago than this. And such +prepossessions were very excusable, for there was undoubtedly a great deal +to be said, at that time, in favour of the fixity of species and of the +existence of great breaks, which there was no obvious or probable means of +filling up, between various groups of organic beings. + +For various reasons, scientific and unscientific, much had been made of the +hiatus between man and the rest of the higher mammalia, and it is no wonder +that issue was first joined on this part of the controversy. I have no wish +to revive past and happily forgotten controversies; but I must state the +simple fact that the distinctions in the cerebral and other characters, +which were so hotly affirmed to separate man from all other animals in +1860, have all been demonstrated to be non-existent, and that the contrary +doctrine is now universally accepted and taught. + +But there were other cases in which the wide structural gaps asserted to +exist between one group of animals and another were by no means fictitious; +and, when such structural breaks were real, Mr. Darwin could account for +them only by supposing that the intermediate forms which once existed had +become extinct. In a remarkable passage he says-- + +"We may thus account even for the distinctness of whole classes from each +other--for instance, of birds from all other vertebrate animals--by the +belief that many animal forms of life have been utterly lost, through which +the early progenitors of birds were formerly connected with the early +progenitors of the other vertebrate classes." [Footnote: _Origin of +Species_, p. 431.] Adverse criticism made merry over such suggestions as +these. Of course it was easy to get out of the difficulty by supposing +extinction; but where was the slightest evidence that such intermediate +forms between birds and reptiles as the hypothesis required ever existed? +And then probably followed a tirade upon this terrible forsaking of the +paths of "Baconian induction." + +But the progress of knowledge has justified Mr. Darwin to an extent which +could hardly have been anticipated. In 1862, the specimen of +_Archæopteryx_, which, until the last two or three years, has remained +unique, was discovered; and it is an animal which, in its feathers and the +greater part of its organisation, is a veritable bird, while, in other +parts, it is as distinctly reptilian. + +In 1868, I had the honour of bringing under your notice, in this theatre, +the results of investigations made, up to that time, into the anatomical +characters of certain ancient reptiles, which showed the nature of the +modifications in virtue of which the type of the quadrupedal reptile passed +into that of a bipedal bird; and abundant confirmatory evidence of the +justice of the conclusions which I then laid before you has since come to +light. + +In 1875, the discovery of the toothed birds of the cretaceous formation in +North America by Professor Marsh completed the series of transitional forms +between birds and reptiles, and removed Mr. Darwin's proposition that "many +animal forms of life have been utterly lost, through which the early +progenitors of birds were formerly connected with the early progenitors of +the other vertebrate classes," from the region of hypothesis to that of +demonstrable fact. + +In 1859, there appeared to be a very sharp and clear hiatus between +vertebrated and invertebrated animals, not only in their structure, but, +what was more important, in their development. I do not think that we even +yet know the precise links of connection between the two; but the +investigations of Kowalewsky and others upon the development of +_Amphioxus_ and of the _Tunicata_ prove, beyond a doubt, that the +differences which were supposed to constitute a barrier between the two are +non-existent. There is no longer any difficulty in understanding how the +vertebrate type may have arisen from the invertebrate, though the full +proof of the manner in which the transition was actually effected may still +be lacking. + +Again, in 1859, there appeared to be a no less sharp separation between the +two great groups of flowering and flowerless plants. It is only +subsequently that the series of remarkable investigations inaugurated by +Hofmeister has brought to light the extraordinary and altogether unexpected +modifications of the reproductive apparatus in the _Lycopodiaceæ_, the +_Rhizocarpeæ_, and the _Gymnospermeæ_, by which the ferns and the +mosses are gradually connected with the Phanerogamic division of the +vegetable world. + +So, again, it is only since 1859 that we have acquired that wealth of +knowledge of the lowest forms of life which demonstrates the futility of +any attempt to separate the lowest plants from the lowest animals, and +shows that the two kingdoms of living nature have a common borderland which +belongs to both, or to neither. + +Thus it will be observed that the whole tendency of biological +investigation, since 1859, has been in the direction of removing the +difficulties which the apparent breaks in the series created at that time; +and the recognition of gradation is the first step towards the acceptance +of evolution. + +As another great factor in bringing about the change of opinion which has +taken place among naturalists, I count the astonishing progress which has +been made in the study of embryology. Twenty years ago, not only were we +devoid of any accurate knowledge of the mode of development of many groups +of animals and plants, but the methods of investigation were rude and +imperfect. At the present time, there is no important group of organic +beings the development of which has not been carefully studied; and the +modern methods of hardening and section-making enable the embryologist to +determine the nature of the process, in each case, with a degree of +minuteness and accuracy which is truly astonishing to those whose memories +carry them back to the beginnings of modern histology. And the results of +these embryological investigations are in complete harmony with the +requirements of the doctrine of evolution. The first beginnings of all the +higher forms of animal life are similar, and however diverse their adult +conditions, they start from a common foundation. Moreover, the process of +development of the animal or the plant from its primary egg, or germ, is a +true process of evolution--a progress from almost formless to more or less +highly organised matter, in virtue of the properties inherent in that +matter. + +To those who are familiar with the process of development, all _a +priori_ objections to the doctrine of biological evolution appear +childish. Any one who has watched the gradual formation of a complicated +animal from the protoplasmic mass, which constitutes the essential element +of a frog's or a hen's egg, has had under his eyes sufficient evidence that +a similar evolution of the whole animal world from the like foundation is, +at any rate, possible. + +Yet another product of investigation has largely contributed to the removal +of the objections to the doctrine of evolution current in 1859. It is the +proof afforded by successive discoveries that Mr. Darwin did not +over-estimate the imperfection of the geological record. No more striking +illustration of this is needed than a comparison of our knowledge of the +mammalian fauna of the Tertiary epoch in 1859 with its present condition. +M. Gaudry's researches on the fossils of Pikermi were published in 1868, +those of Messrs. Leidy, Marsh, and Cope, on the fossils of the Western +Territories of America, have appeared almost wholly since 1870, those of M. +Filhol on the phosphorites of Quercy in 1878. The general effect of these +investigations has been to introduce to us a multitude of extinct animals, +the existence of which was previously hardly suspected; just as if +zoologists were to become acquainted with a country, hitherto unknown, as +rich in novel forms of life as Brazil or South Africa once were to +Europeans. Indeed, the fossil fauna of the Western Territories of America +bid fair to exceed in interest and importance all other known Tertiary +deposits put together; and yet, with the exception of the case of the +American tertiaries, these investigations have extended over very limited +areas; and, at Pikermi, were confined to an extremely small space. + +Such appear to me to be the chief events in the history of the progress of +knowledge during the last twenty years, which account for the changed +feeling with which the doctrine of evolution is at present regarded by +those who have followed the advance of biological science, in respect of +those problems which bear indirectly upon that doctrine. + +But all this remains mere secondary evidence. It may remove dissent, but it +does not compel assent. Primary and direct evidence in favour of evolution +can be furnished only by palæontology. The geological record, so soon as it +approaches completeness, must, when properly questioned, yield either an +affirmative or a negative answer: if evolution has taken place, there will +its mark be left; if it has not taken place, there will lie its refutation. + +What was the state of matters in 1859? Let us hear Mr. Darwin, who may be +trusted always to state the case against himself as strongly as possible. + +"On this doctrine of the extermination of an infinitude of connecting links +between the living and extinct inhabitants of the world, and at each +successive period between the extinct and still older species, why is not +every geological formation charged with such links? Why does not every +collection of fossil remains afford plain evidence of the gradation and +mutation of the forms of life? We meet with no such evidence, and this is +the most obvious and plausible of the many objections which may be urged +against my theory." [Footnote: _Origin of Species_, ed. 1, p. 463.] + +Nothing could have been more useful to the opposition than this +characteristically candid avowal, twisted as it immediately was into an +admission that the writer's views were contradicted by the facts of +palæontology. But, in fact, Mr. Darwin made no such admission. What he says +in effect is, not that palæontological evidence is against him, but that it +is not distinctly in his favour; and, without attempting to attenuate the +fact, he accounts for it by the scantiness and the imperfection of that +evidence. + +What is the state of the case now, when, as we have seen, the amount of our +knowledge respecting the mammalia of the Tertiary epoch is increased +fifty-fold, and in some directions even approaches completeness? + +Simply this, that, if the doctrine of evolution had not existed, +palaeontologists must have invented it, so irresistibly is it forced upon +the mind by the study of the remains of the Tertiary mammalia which have +been brought to light since 1859. + +Among the fossils of Pikermi, Gaudry found the successive stages by which +the ancient civets passed into the more modern hyænas; through the Tertiary +deposits of Western America, Marsh tracked the successive forms by which +the ancient stock of the horse has passed into its present form; and +innumerable less complete indications of the mode of evolution of other +groups of the higher mammalia have been obtained. In the remarkable memoir +on the phosphorites of Quercy, to which I have referred, M. Filhol +describes no fewer than seventeen varieties of the genus _Cynodictis_, +which fill up all the interval between the viverine animals and the +bear-like dog _Amphicyon_; nor do I know any solid ground of objection +to the supposition that, in this _Cynodictis-Amphicyon_ group, we have +the stock whence all the Viveridæ, Felidæ, Hyænidæ, Canidæ, and perhaps the +Procyonidæ and Ursidæ, of the present fauna have been evolved. On the +contrary, there is a great deal to be said in favour. + +In the course of summing up his results, M. Filhol observes:-- + +"During the epoch of the phosphorites, great changes took place in animal +forms, and almost the same types as those which now exist became defined +from one another. + +"Under the influence of natural conditions of which we have no exact +knowledge, though traces of them are discoverable, species have been +modified in a thousand ways: races have arisen which, becoming fixed, have +thus produced a corresponding number of secondary species." + +In 1859, language of which this is an unintentional paraphrase, occurring +in the "Origin of Species," was scouted as wild speculation; at present, it +is a sober statement of the conclusions to which an acute and +critically-minded investigator is led by large and patient study of the +facts of palæontology. I venture to repeat what I have said before, that so +far as the animal world is concerned, evolution is no longer a speculation, +but a statement of historical fact. It takes its place alongside of those +accepted truths which must be reckoned with by philosophers of all schools. + +Thus when, on the first day of October next, "The Origin of Species" comes +of age, the promise of its youth will be amply fulfilled; and we shall be +prepared to congratulate the venerated author of the book, not only that +the greatness of his achievement and its enduring influence upon the +progress of knowledge have won him a place beside our Harvey; but, still +more, that, like Harvey, he has lived long enough to outlast detraction and +opposition, and to see the stone that the builders rejected become the +head-stone of the corner. + + + + +VIII + +CHARLES DARWIN + +[_Nature_, April 27th, 1882] + + +Very few, even among those who have taken the keenest interest in the +progress of the revolution in natural knowledge set afoot by the +publication of "The Origin of Species," and who have watched, not without +astonishment, the rapid and complete change which has been effected both +inside and outside the boundaries of the scientific world in the attitude +of men's minds towards the doctrines which are expounded in that great +work, can have been prepared for the extraordinary manifestation of +affectionate regard for the man, and of profound reverence for the +philosopher, which followed the announcement, on Thursday last, of the +death of Mr. Darwin. + +Not only in these islands, where so many have felt the fascination of +personal contact with an intellect which had no superior, and with a +character which was even nobler than the intellect; but, in all parts of +the civilised world, it would seem that those whose business it is to feel +the pulse of nations and to know what interests the masses of mankind, were +well aware that thousands of their readers would think the world the poorer +for Darwin's death, and would dwell with eager interest upon every incident +of his history. In France, in Germany, in Austro-Hungary, in Italy, in the +United States, writers of all shades of opinion, for once unanimous, have +paid a willing tribute to the worth of our great countryman, ignored in +life by the official representatives of the kingdom, but laid in death +among his peers in Westminster Abbey by the will of the intelligence of the +nation. + +It is not for us to allude to the sacred sorrows of the bereaved home at +Down; but it is no secret that, outside that domestic group, there are many +to whom Mr. Darwin's death is a wholly irreparable loss. And this not +merely because of his wonderfully genial, simple, and generous nature; his +cheerful and animated conversation, and the infinite variety and accuracy +of his information; but because the more one knew of him, the more he +seemed the incorporated ideal of a man of science. Acute as were his +reasoning powers, vast as was his knowledge, marvellous as was his +tenacious industry, under physical difficulties which would have converted +nine men out of ten into aimless invalids; it was not these qualities, +great as they were, which impressed those who were admitted to his intimacy +with involuntary veneration, but a certain intense and almost passionate +honesty by which all his thoughts and actions were irradiated, as by a +central fire. + +It was this rarest and greatest of endowments which kept his vivid +imagination and great speculative powers within due bounds; which compelled +him to undertake the prodigious labours of original investigation and of +reading, upon which his published works are based; which made him accept +criticisms and suggestions from anybody and everybody, not only without +impatience, but with expressions of gratitude sometimes almost comically in +excess of their value; which led him to allow neither himself nor others to +be deceived by phrases, and to spare neither time nor pains in order to +obtain clear and distinct ideas upon every topic with which he occupied +himself. + +One could not converse with Darwin without being reminded of Socrates. +There was the same desire to find some one wiser than himself; the same +belief in the sovereignty of reason; the same ready humour; the same +sympathetic interest in all the ways and works of men. But instead of +turning away from the problems of Nature as hopelessly insoluble, our +modern philosopher devoted his whole life to attacking them in the spirit +of Heraclitus and of Democritus, with results which are the substance of +which their speculations were anticipatory shadows. + +The due appreciation, or even enumeration, of these results is neither +practicable nor desirable at this moment. There is a time for all things--a +time for glorying in our ever-extending conquests over the realm of Nature, +and a time for mourning over the heroes who have led us to victory. + +None have fought better, and none have been more fortunate, than Charles +Darwin. He found a great truth trodden underfoot, reviled by bigots, and +ridiculed by all the world; he lived long enough to see it, chiefly by his +own efforts, irrefragably established in science, inseparably incorporated +with the common thoughts of men, and only hated and feared by those who +would revile, but dare not. What shall a man desire more than this? Once +more the image of Socrates rises unbidden, and the noble peroration of the +"Apology" rings in our ears as if it were Charles Darwin's farewell:-- + +"The hour of departure has arrived, and we go our ways--I to die and you to +live. Which is the better, God only knows." + + + + +IX + +THE DARWIN MEMORIAL + +[June 9th, 1885] + + +_Address by the President of the Royal Society, in the name of the +Memorial Committee, on handing over the statue of Darwin to H.R.H. the +Prince of Wales, as representative of the Trustees of the British +Museum_. + +YOUR ROYAL HIGHNESS,--It is now three years since the announcement of the +death of our famous countryman, Charles Darwin, gave rise to a +manifestation of public feeling, not only in these realms, but throughout +the civilised world, which, if I mistake not, is without precedent in the +modest annals of scientific biography. + +The causes of this deep and wide outburst of emotion are not far to seek. +We had lost one of these rare ministers and interpreters of Nature whose +names mark epochs in the advance of natural knowledge. For, whatever be the +ultimate verdict of posterity upon this or that opinion which Mr. Darwin +has propounded; whatever adumbrations or anticipations of his doctrines may +be found in the writings of his predecessors; the broad fact remains that, +since the publication and by reason of the publication, of "The Origin of +Species" the fundamental conceptions and the aims of the students of living +Nature have been completely changed. From that work has sprung a great +renewal, a true "instauratio magna" of the zoological and botanical +sciences. + +But the impulse thus given to scientific thought rapidly spread beyond the +ordinarily recognised limits of biology. Psychology, Ethics, Cosmology were +stirred to their foundations, and the "Origin of Species" proved itself to +be the fixed point which the general doctrine of evolution needed in order +to move the world. "Darwinism," in one form or another, sometimes strangely +distorted and mutilated, became an everyday topic of men's speech, the +object of an abundance both of vituperation and of praise, more often than +of serious study. + +It is curious now to remember how largely, at first, the objectors +predominated; but considering the usual fate of new views, it is still more +curious to consider for how short a time the phase of vehement opposition +lasted. Before twenty years had passed, not only had the importance of Mr. +Darwin's work been fully recognised, but the world had discerned the +simple, earnest, generous character of the man, that shone through every +page of his writings. + +I imagine that reflections such as these swept through the minds alike of +loving friends and of honourable antagonists when Mr. Darwin died; and that +they were at one in the desire to honour the memory of the man who, without +fear and without reproach, had successfully fought the hardest intellectual +battle of these days. + +It was in satisfaction of these just and generous impulses that our great +naturalist's remains were deposited in Westminster Abbey; and that, +immediately afterwards, a public meeting, presided over by my lamented +predecessor, Mr. Spottiswoode, was held in the rooms of the Royal Society, +for the purpose of considering what further step should be taken towards +the same end. + +It was resolved to invite subscriptions, with the view of erecting a statue +of Mr. Darwin in some suitable locality; and to devote any surplus to the +advancement of the biological sciences. + +Contributions at once flowed in from Austria, Belgium, Brazil, Denmark, +France, Germany, Holland, Italy, Norway, Portugal, Russia, Spain, Sweden, +Switzerland, the United States, and the British Colonies, no less than from +all parts of the three kingdoms; and they came from all classes of the +community. To mention one interesting case, Sweden sent in 2296 +subscriptions "from all sorts of people," as the distinguished man of +science who transmitted them wrote, "from the bishop to the seamstress, and +in sums from five pounds to two pence." + +The Executive Committee has thus been enabled to carry out the objects +proposed. A "Darwin Fund" has been created, which is to be held in trust by +the Royal Society, and is to be employed in the promotion of biological +research. + +The execution of the statue was entrusted to Mr. Boehm; and I think that +those who had the good fortune to know Mr. Darwin personally will admire +the power of artistic divination which has enabled the sculptor to place +before us so very characteristic a likeness of one whom he had not seen. + +It appeared to the Committee that, whether they regarded Mr. Darwin's +career or the requirements of a work of art, no site could be so +appropriate as this great hall, and they applied to the Trustees of the +British Museum for permission to erect it in its present position. + +That permission was most cordially granted, and I am desired to tender the +best thanks of the Committee to the Trustees for their willingness to +accede to our wishes. + +I also beg leave to offer the expression of our gratitude to your Royal +Highness for kindly consenting to represent the Trustees to-day. It only +remains for me, your Royal Highness, my Lords and Gentlemen, Trustees of +the British Museum, in the name of the Darwin Memorial Committee, to +request you to accept this statue of Charles Darwin. + +We do not make this request for the mere sake of perpetuating a memory; for +so long as men occupy themselves with the pursuit of truth, the name of +Darwin runs no more risk of oblivion than does that of Copernicus, or that +of Harvey. + +Nor, most assuredly, do we ask you to preserve the statue in its cynosural +position in this entrance-hall of our National Museum of Natural History as +evidence that Mr. Darwin's views have received your official sanction; for +science does not recognise such sanctions, and commits suicide when it +adopts a creed. + +No; we beg you to cherish this Memorial as a symbol by which, as generation +after generation of students of Nature enter yonder door, they shall be +reminded of the ideal according to which they must shape their lives, if +they would turn to the best account the opportunities offered by the great +institution under your charge. + + + + +X + +OBITUARY [Footnote: From the Obituary Notices of the _Proceedings of the +Royal Society_, vol. 44.] + +[1888] + + +Charles Robert Darwin was the fifth child and second son of Robert Waring +Darwin and Susannah Wedgwood, and was born on the 12th February, 1809, at +Shrewsbury, where his father was a physician in large practice. + +Mrs. Robert Darwin died when her son Charles was only eight years old, and +he hardly remembered her. A daughter of the famous Josiah Wedgwood, who +created a new branch of the potter's art, and established the great works +of Etruria, could hardly fail to transmit important mental and moral +qualities to her children; and there is a solitary record of her direct +influence in the story told by a schoolfellow, who remembers Charles Darwin +"bringing a flower to school, and saying that his mother had taught him +how, by looking at the inside of the blossom, the name of the plant could +be discovered." (I., p. 28. [Footnote: The references throughout this +notice are to the _Life and Letters_, unless the contrary is expressly +stated.]) + +The theory that men of genius derive their qualities from their mothers, +however, can hardly derive support from Charles Darwin's case, in the face +of the patent influence of his paternal forefathers. Dr. Darwin, indeed, +though a man of marked individuality of character, a quick and acute +observer, with much practical sagacity, is said not to have had a +scientific mind. But when his son adds that his father "formed a theory for +almost everything that occurred" (I., p. 20), he indicates a highly +probable source for that inability to refrain from forming an hypothesis on +every subject which he confesses to be one of the leading characteristics +of his own mind, some pages further on (I., p. 103). Dr. R. W. Darwin, +again, was the third son of Erasmus Darwin, also a physician of great +repute, who shared the intimacy of Watt and Priestley, and was widely known +as the author of "Zoonomia," and other voluminous poetical and prose works +which had a great vogue in the latter half of the eighteenth century. The +celebrity which they enjoyed was in part due to the attractive style (at +least according to the taste of that day) in which the author's extensive, +though not very profound, acquaintance with natural phenomena was set +forth; but in a still greater degree, probably, to the boldness of the +speculative views, always ingenious and sometimes fantastic, in which he +indulged. The conception of evolution set afoot by De Maillet and others, +in the early part of the century, not only found a vigorous champion in +Erasmus Darwin, but he propounded an hypothesis as to the manner in which +the species of animals and plants have acquired their characters, which is +identical in principle with that subsequently rendered famous by Lamarck. + +That Charles Darwin's chief intellectual inheritance came to him from the +paternal side, then, is hardly doubtful. But there is nothing to show that +he was, to any sensible extent, directly influenced by his grandfather's +biological work. He tells us that a perusal of the "Zoonomia" in early life +produced no effect upon him, although he greatly admired it; and that, on +reading it again, ten or fifteen years afterwards, he was much +disappointed, "the proportion of speculation being so large to the facts +given." But with his usual anxious candour he adds, "Nevertheless, it is +probable that the hearing, rather early in life, such views maintained and +praised, may have favoured my upholding them, in a different form, in my +'Origin of Species.'" (I., p. 38.) Erasmus Darwin was in fact an +anticipator of Lamarck, and not of Charles Darwin; there is no trace in his +works of the conceptions by the addition of which his grandson +metamorphosed the theory of evolution as applied to living things and gave +it a new foundation. + +Charles Darwin's childhood and youth afforded no intimation that he would +he, or do, anything out of the common run. In fact, the prognostications of +the educational authorities into whose hands he first fell were most +distinctly unfavourable; and they counted the only boy of original genius +who is known to have come under their hands as no better than a dunce. The +history of the educational experiments to which Darwin was subjected is +curious, and not without a moral for the present generation. There were +four of them, and three were failures. Yet it cannot be said that the +materials on which the pedagogic powers operated were other than good. In +his boyhood Darwin was strong, well-grown, and active, taking the keen +delight in field sports and in every description of hard physical exercise +which is natural to an English country-bred lad; and, in respect of things +of the mind, he was neither apathetic, nor idle, nor one-sided. The +"Autobiography" tells us that he "had much zeal for whatever interested" +him, and he was interested in many and very diverse topics. He could work +hard, and liked a complex subject better than an easy one. The "clear +geometrical proofs" of Euclid delighted him. His interest in practical +chemistry, carried out in an extemporised laboratory, in which he was +permitted to assist by his elder brother, kept him late at work, and earned +him the nickname of "gas" among his schoolfellows. And there could have +been no insensibility to literature in one who, as a boy, could sit for +hours reading Shakespeare, Milton, Scott, and Byron; who greatly admired +some of the Odes of Horace; and who, in later years, on board the "Beagle," +when only one book could be carried on an expedition, chose a volume of +Milton for his companion. + +Industry, intellectual interests, the capacity for taking pleasure in +deductive reasoning, in observation, in experiment, no less than in the +highest works of imagination: where these qualities are present any +rational system of education should surely be able to make something of +them. Unfortunately for Darwin, the Shrewsbury Grammar School, though good +of its kind, was an institution of a type universally prevalent in this +country half a century ago, and by no means extinct at the present day. The +education given was "strictly classical," "especial attention" being "paid +to verse-making," while all other subjects, except a little ancient +geography and history, were ignored. Whether, as in some famous English +schools at that date and much later, elementary arithmetic was also left +out of sight does not appear; but the instruction in Euclid which gave +Charles Darwin so much satisfaction was certainly supplied by a private +tutor. That a boy, even in his leisure hours, should permit himself to be +interested in any but book-learning seems to have been regarded as little +better than an outrage by the head master, who thought it his duty to +administer a public rebuke to young Darwin for wasting his time on such a +contemptible subject as chemistry. English composition and literature, +modern languages, modern history, modern geography, appear to have been +considered to be as despicable as chemistry. + +For seven long years Darwin got through his appointed tasks; construed +without cribs, learned by rote whatever was demanded, and concocted his +verses in approved schoolboy fashion. And the result, as it appeared to his +mature judgment, was simply negative. "The school as a means of education +to me was simply a blank." (I. p. 32.) On the other hand, the extraneous +chemical exercises, which the head master treated so contumeliously, are +gratefully spoken of as the "best part" of his education while at school. +Such is the judgment of the scholar on the school; as might be expected, it +has its counterpart in the judgment of the school on the scholar. The +collective intelligence of the staff of Shrewsbury School could find +nothing but dull mediocrity in Charles Darwin. The mind that found +satisfaction in knowledge, but very little in mere learning; that could +appreciate literature, but had no particular aptitude for grammatical +exercises; appeared to the "strictly classical" pedagogue to be no mind at +all. As a matter of fact, Darwin's school education left him ignorant of +almost all the things which it would have been well for him to know, and +untrained in all the things it would have been useful for him to be able to +do, in after life. Drawing, practice in English composition, and +instruction in the elements of the physical sciences, would not only have +been infinitely valuable to him in reference to his future career, but +would have furnished the discipline suited to his faculties, whatever that +career might be. And a knowledge of French and German, especially the +latter, would have removed from his path obstacles which he never fully +overcame. + +Thus, starved and stunted on the intellectual side, it is not surprising +that Charles Darwin's energies were directed towards athletic amusements +and sport, to such an extent, that even his kind and sagacious father could +be exasperated into telling him that "he cared for nothing but shooting, +dogs, and rat-catching." (I. p. 32.) It would be unfair to expect even the +wisest of fathers to have foreseen that the shooting and the rat-catching, +as training in the ways of quick observation and in physical endurance, +would prove more valuable than the construing and verse-making to his son, +whose attempt, at a later period of his Life, to persuade himself "that +shooting was almost an intellectual employment: it required so much skill +to judge where to find most game, and to hunt the dogs well" (I. p. 43), +was by no means so sophistical as he seems to have been ready to admit. + +In 1825, Dr. Darwin came to the very just conclusion that his son Charles +would do no good by remaining at Shrewsbury School, and sent him to join +his elder brother Erasmus, who was studying medicine at Edinburgh, with the +intention that the younger son should also become a medical practitioner. +Both sons, however, were well aware that their inheritance would relieve +them from the urgency of the struggle for existence which most professional +men have to face; and they seemed to have allowed their tastes, rather than +the medical curriculum, to have guided their studies. Erasmus Darwin was +debarred by constant ill-health from seeking the public distinction which +his high intelligence and extensive knowledge would, under ordinary +circumstances, have insured. He took no great interest in biological +subjects, but his companionship must have had its influence on his brother. +Still more was exerted by friends like Coldstream and Grant, both +subsequently well-known zoologists (and the latter an enthusiastic +Lamarckian), by whom Darwin was induced to interest himself in marine +zoology. A notice of the ciliated germs of _Flustra_, communicated to +the Plinian Society in 1826, was the first fruits of Darwin's half century +of scientific work. Occasional attendance at the Wernerian Society brought +him into relation with that excellent ornithologist the elder Macgillivray, +and enabled him to see and hear Audubon. Moreover, he got lessons in +bird-stuffing from a negro, who had accompanied the eccentric traveller +Waterton in his wanderings, before settling in Edinburgh. + +No doubt Darwin picked up a great deal of valuable knowledge during his two +years' residence in Scotland; but it is equally clear that next to none of +it came through the regular channels of academic education. Indeed, the +influence of the Edinburgh professoriate appears to have been mainly +negative, and in some cases deterrent; creating in his mind, not only a +very low estimate of the value of lectures, but an antipathy to the +subjects which had been the occasion of the boredom inflicted upon him by +their instrumentality. With the exception of Hope, the Professor of +Chemistry, Darwin found them all "intolerably dull." Forty years afterwards +he writes of the lectures of the Professor of Materia Medica that they were +"fearful to remember." The Professor of Anatomy made his lectures "as dull +as he was himself," and he must have been very dull to have wrung from his +victim the sharpest personal remark recorded as his. But the climax seems +to have been attained by the Professor of Geology and Zoology, whose +prælections were so "incredibly dull" that they produced in their hearer +the somewhat rash determination never "to read a book on geology or in any +way to study the science" so long as he lived. (I. p. 41.) + +There is much reason to believe that the lectures in question were +eminently qualified to produce the impression which they made; and there +can be little doubt, that Darwin's conclusion that his time was better +employed in reading than in listening to such lectures was a sound one. But +it was particularly unfortunate that the personal and professorial dulness +of the Professor of Anatomy, combined with Darwin's sensitiveness to the +disagreeable concomitants of anatomical work, drove him away from the +dissecting room. In after life, he justly recognised that this was an +"irremediable evil" in reference to the pursuits he eventually adopted; +indeed, it is marvellous that he succeeded in making up for his lack of +anatomical discipline, so far as his work on the Cirripedes shows he did. +And the neglect of anatomy had the further unfortunate result that it +excluded him from the best opportunity of bringing himself into direct +contact with the facts of nature which the University had to offer. In +those days, almost the only practical scientific work accessible to +students was anatomical, and the only laboratory at their disposal the +dissecting room. + +We may now console ourselves with the reflection that the partial evil was +the general good. Darwin had already shown an aptitude for practical +medicine (I. p. 37); and his subsequent career proved that he had the +making of an excellent anatomist. Thus, though his horror of operations +would probably have shut him off from surgery, there was nothing to prevent +him (any more than the same peculiarity prevented his father) from passing +successfully through the medical curriculum and becoming, like his father +and grandfather, a successful physician, in which case "The Origin of +Species" would not have been written. Darwin has jestingly alluded to the +fact that the shape of his nose (to which Captain Fitzroy objected), nearly +prevented his embarkation in the "Beagle"; it may be that the sensitiveness +of that organ secured him for science. + +At the end of two years' residence in Edinburgh it hardly needed Dr. +Darwin's sagacity to conclude that a young man, who found nothing but +dulness in professorial lucubrations, could not bring himself to endure a +dissecting room, fled from operations, and did not need a profession as a +means of livelihood, was hardly likely to distinguish himself as a student +of medicine. He therefore made a new suggestion, proposing that his son +should enter an English University and qualify for the ministry of the +Church. Charles Darwin found the proposal agreeable, none the less, +probably, that a good deal of natural history and a little shooting were by +no means held, at that time, to be incompatible with the conscientious +performance of the duties of a country clergyman. But it is characteristic +of the man, that he asked time for consideration, in order that he might +satisfy himself that he could sign the Thirty-nine Articles with a clear +conscience. However, the study of "Pearson on the Creeds" and a few other +books of divinity soon assured him that his religious opinions left nothing +to be desired on the score of orthodoxy, and he acceded to his father's +proposition. + +The English University selected was Cambridge; but an unexpected obstacle +arose from the fact that, within the two years which had elapsed, since the +young man who had enjoyed seven years of the benefit of a strictly +classical education had left school, he had forgotten almost everything he +had learned there, "even to some few of the Greek letters." (I. p. 46.) +Three months with a tutor, however, brought him back to the point of +translating Homer and the Greek Testament "with moderate facility," and +Charles Darwin commenced the third educational experiment of which he was +the subject, and was entered on the books of Christ's College in October +1827. So far as the direct results of the academic training thus received +are concerned, the English University was not more successful than the +Scottish. "During the three years which I spent at Cambridge my time was +wasted, as far as the academical studies were concerned, as completely as +at Edinburgh and as at school." (I. p. 46.) And yet, as before, there is +ample evidence that this negative result cannot be put down to any native +defect on the part of the scholar. Idle and dull young men, or even young +men who being neither idle nor dull, are incapable of caring for anything +but some hobby, do not devote themselves to the thorough study of Paley's +"Moral Philosophy," and "Evidences of Christianity"; nor are their +reminiscences of this particular portion of their studies expressed in +terms such as the following: "The logic of this book [the 'Evidences'] and, +as I may add, of his 'Natural Theology' gave me as much delight as did +Euclid." (I. p. 47.) + +The collector's instinct, strong in Darwin from his childhood, as is +usually the case in great naturalists, turned itself in the direction of +Insects during his residence at Cambridge. In childhood it had been damped +by the moral scruples of a sister, as to the propriety of catching and +killing insects for the mere sake of possessing them, but now it broke out +afresh, and Darwin became an enthusiastic beetle collector. Oddly enough he +took no scientific interest in beetles, not even troubling himself to make +out their names; his delight lay in the capture of a species which turned +out to be rare or new, and still more in finding his name, as captor, +recorded in print. Evidently, this beetle-hunting hobby had little to do +with science, but was mainly a new phase of the old and undiminished love +of sport. In the intervals of beetle-catching, when shooting and hunting +were not to be had, riding across country answered the purpose. These +tastes naturally threw the young undergraduate among a set of men who +preferred hard riding: to hard reading, and wasted the midnight oil upon +other pursuits than that of academic distinction. A superficial observer +might have had some grounds to fear that Dr. Darwin's wrathful prognosis +might yet be verified. But if the eminently social tendencies of a vigorous +and genial nature sought an outlet among a set of jovial sporting friends, +there were other and no less strong proclivities which brought him into +relation with associates of a very different stamp. + +Though almost without ear and with a very defective memory for music, +Darwin was so strongly and pleasurably affected by it that he became a +member of a musical society; and an equal lack of natural capacity for +drawing did not prevent him from studying good works of art with much care. + +An acquaintance with even the rudiments of physical science was no part of +the requirements for the ordinary Cambridge degree. But there were +professors both of Geology and of Botany whose lectures were accessible to +those who chose to attend them. The occupants of these chairs, in Darwin's +time, were eminent men and also admirable lecturers in their widely +different styles. The horror of geological lectures which Darwin had +acquired at Edinburgh, unfortunately prevented him from going within reach +of the fervid eloquence of Sedgwick; but he attended the botanical course, +and though he paid no serious attention to the subject, he took great +delight in the country excursions, which Henslow so well knew how to make +both pleasant and instructive. The Botanical Professor was, in fact, a man +of rare character and singularly extensive acquirements in all branches of +natural history. It was his greatest pleasure to place his stores of +knowledge at the disposal of the young men who gathered about him, and who +found in him, not merely an encyclopedic teacher but a wise counsellor, +and, in case of worthiness, a warm friend. Darwin's acquaintance with him +soon ripened into a friendship which was terminated only by Henslow's death +in 1861, when his quondam pupil gave touching expression to his sense of +what he owed to one whom he calls (in one of his letters) his "dear old +master in Natural History." (II. p. 217.) It was by Henslow's advice that +Darwin was led to break the vow he had registered against making an +acquaintance with geology; and it was through Henslow's good offices with +Sedgwick that he obtained the opportunity of accompanying the Geological +Professor on one of his excursions in Wales. He then received a certain +amount of practical instruction in Geology, the value of which he +subsequently warmly acknowledged. (I. p. 237.) In another direction, +Henslow did him an immense, though not altogether intentional service, by +recommending him to buy and study the recently published first volume of +Lyell's "Principles." As an orthodox geologist of the then dominant +catastrophic school, Henslow accompanied his recommendation with the +admonition on no account to adopt Lyell's general views. But the warning +fell on deaf ears, and it is hardly too much to say that Darwin's greatest +work is the outcome of the unflinching application to Biology of the +leading idea and the method applied in the "Principles" to geology. +[Footnote: "After my return to England it appeared to me that by following +the example of Lyell in Geology, and by collecting all facts which bore in +any way on the variation of animals and plants under domestication and +nature, some light might perhaps be thrown on the whole subject [of the +origin of species]." (I. p. 83.) See also the dedication of the second +edition of the _Journal of a Naturalist_]. Finally, it was through +Henslow, and at his suggestion, that Darwin was offered the appointment to +the "Beagle" as naturalist. + +During the latter part of Darwin's residence at Cambridge the prospect of +entering the Church, though the plan was never formally renounced, seems to +have grown very shadowy. Humboldt's "Personal Narrative," and Herschel's +"Introduction to the Study of Natural Philosophy," fell in his way and +revealed to him his real vocation. The impression made by the former work +was very strong. "My whole course of life," says Darwin in sending a +message to Humboldt, "is due to having read and re-read, as a youth, his +personal narrative." (I. p. 336.) The description of Teneriffe inspired +Darwin with such a strong desire to visit the island, that he took some +steps towards going there--inquiring about ships, and so on. + +But, while this project was fermenting, Henslow, who had been asked to +recommend a naturalist for Captain Fitzroy's projected expedition, at once +thought of his pupil. In his letter of the 24th August, 1831, he says: "I +have stated that I consider you to be the best qualified person I know of +who is likely to undertake such a situation. I state this--not on the +supposition of your being a _finished_ naturalist, but as amply +qualified for collecting, observing, and noting anything worthy to be noted +in Natural History.... The voyage is to last two years, and if you take +plenty of books with you, anything you please may be done." (I. p. 193.) +The state of the case could not have been better put. Assuredly the young +naturalist's theoretical and practical scientific training had gone no +further than might suffice for the outfit of an intelligent collector and +note-taker. He was fully conscious of the fact, and his ambition hardly +rose above the hope that he should bring back materials for the scientific +"lions" at home of sufficient excellence to prevent them from turning and +rending him. (I. p. 248.) + +But a fourth educational experiment was to be tried. This time Nature took +him in hand herself and showed him the way by which, to borrow Henslow's +prophetic phrase, "anything he pleased might be done." + +The conditions of life presented by a ship-of-war of only 242 tons burthen, +would not, _primâ facie_, appear to be so favourable to intellectual +development as those offered by the cloistered retirement of Christ's +College. Darwin had not even a cabin to himself; while, in addition to the +hindrances and interruptions incidental to sea-life, which can be +appreciated only by those who have had experience of them, sea-sickness +came on whenever the little ship was "lively"; and, considering the +circumstances of the cruise, that must have been her normal state. +Nevertheless, Darwin found on board the "Beagle" that which neither the +pedagogues of Shrewsbury, nor the professoriate of Edinburgh, nor the +tutors of Cambridge had managed to give him. "I have always felt that I owe +to the voyage the first real training or education of my mind (I. p. 61);" +and in a letter written as he was leaving England, he calls the voyage on +which he was starting, with just insight, his "second life." (I. p. 214.) +Happily for Darwin's education, the school time of the "Beagle" lasted five +years instead of two; and the countries which the ship visited were +singularly well fitted to provide him with object-lessons, on the nature of +things, of the greatest value. + +While at sea, he diligently collected, studied, and made copious notes upon +the surface Fauna. But with no previous training in dissection, hardly any +power of drawing, and next to no knowledge of comparative anatomy, his +occupation with work of this kind--notwithstanding all his zeal and +industry--resulted, for the most part, in a vast accumulation of useless +manuscript. Some acquaintance with the marine _Crustacea_, +observations on _Planariæ_ and on the ubiquitous _Sagitta_, seem +to have been the chief results of a great amount of labour in this +direction. + +It was otherwise with the terrestrial phenomena which came under the +voyager's notice: and Geology very soon took her revenge for the scorn +which the much-bored Edinburgh student had poured upon her. Three weeks +after leaving England the ship touched land for the first time at St. Jago, +in the Cape de Verd Islands, and Darwin found his attention vividly engaged +by the volcanic phenomena and the signs of upheaval which the island +presented. His geological studies had already indicated the direction in +which a great deal might be done, beyond collecting; and it was while +sitting beneath a low lava cliff on the shore of this island, that a sense +of his real capability first dawned upon Darwin, and prompted the ambition +to write a book on the geology of the various countries visited. (I. p. +66.) Even at this early date, Darwin must have thought much on geological +topics, for he was already convinced of the superiority of Lyell's views to +those entertained by the catastrophists [Footnote: "I had brought with me +the first volume of Lyell's _Principles of Geology_, which I studied +attentively; and the book was of the highest service to me in many ways. +The very first place which I examined, namely, St. Jago, in the Cape de +Verd Islands, showed me clearly the wonderful superiority of Lyell's manner +of treating Geology, compared with that of any other author whose works I +had with me or ever afterwards read "-(I. p. 62.)]; and his subsequent +study of the tertiary deposits and of the terraced gravel beds of South +America was eminently fitted to strengthen that conviction. The letters +from South America contain little reference to any scientific topic except +geology; and even the theory of the formation of coral reefs was prompted +by the evidence of extensive and gradual changes of level afforded by the +geology of South America; "No other work of mine," he says, "was begun in +so deductive a spirit as this; for the whole theory was thought out on the +West Coast of South America, before I had seen a true coral reef. I had, +therefore, only to verify and extend my views by a careful examination of +living reefs." (I. p. 70.) In 1835, when starting from Lima for the +Galapagos, he recommends his friend, W. D. Fox, to take up geology:--"There +is so much larger a field for thought than in the other branches of Natural +History. I am become a zealous disciple of Mr. Lyell's views, as made known +in his admirable book. Geologising in South America, I am tempted to carry +parts to a greater extent even than he does. Geology is a capital science +to begin with, as it requires nothing but a little reading, thinking, and +hammering." (I. p. 263.) The truth of the last statement, when it was +written, is a curious mark of the subsequent progress of geology. Even so +late as 1836, Darwin speaks of being "much more inclined for geology than +the other branches of Natural History." (I. p. 275.) + +At the end of the letter to Mr. Fox, however, a little doubt is expressed +whether zoological studies might not, after all, have been more profitable; +and an interesting passage in the "Autobiography" enables us to understand +the origin of this hesitation. + +"During the voyage of the 'Beagle' I had been deeply impressed by +discovering in the Pampean formation great fossil animals covered with +armour like that on the existing armadillos; secondly, by the manner in +which closely-allied animals replace one another in proceeding southwards +over the continent; and, thirdly, by the South American character of most +of the productions of the Galapagos Archipelago, and, more especially, by +the manner in which they differ slightly on each island of the group; some +of the islands appearing to be very ancient in a geological sense. + +"It was evident that such facts as these, as well as many others, could +only be explained on the supposition that species gradually become +modified; and the subject haunted me. But it was equally evident that +neither the action of the surrounding conditions, nor the will of the +organisms (especially in the case of plants) could account for the +innumerable cases in which organisms of every kind are beautifully adapted +to their habits of life; for instance, a woodpecker or a tree-frog to climb +trees, or a seed for dispersal by hooks or plumes. I had always been much +struck by such adaptations, and until these could be explained it seemed to +me almost useless to endeavour to prove by indirect evidence that species +have been modified." (I. p. 82.) + +The facts to which reference is here made were, without doubt, eminently +fitted to attract the attention of a philosophical thinker; but, until the +relations of the existing with the extinct species and of the species of +the different geographical areas with one another, were determined with +some exactness, they afforded but an unsafe foundation for speculation. It +was not possible that this determination should have been effected before +the return of the "Beagle" to England; and thus the date which Darwin +(writing in 1837) assigns to the dawn of the new light which was rising in +his mind becomes intelligible. [Footnote: I am indebted to Mr. F. Darwin +for the knowledge of a letter addressed by his father to Dr. Otto Zacharias +in 1877 which contains the following paragraph, confirmatory of the view +expressed above: "When I was on board the _Beagle_, I believed in the +permanence of species, but, as far as I can remember, vague doubts +occasionally flitted across my mind. On my return home in the autumn of +1836, I immediately began to prepare my journal for publication, and then +saw how many facts indicated the common descent of species, so that in +July, 1837, I opened a note-book to record any facts which might bear on +the question. But I did not become convinced that species were mutable +until, I think, two or three years had elapsed."] + +"In July opened first note-book on Transmutation of Species. Had been +greatly struck from about the month of previous March on character of South +American fossils and species on Galapagos Archipelago. These facts +(especially latter) origin of all my views." (I. p. 276.) + +From March, 1837, then, Darwin, not without many misgivings and +fluctuations of opinion, inclined towards transmutation as a provisional +hypothesis. Three months afterwards he is hard at work collecting facts for +the purpose of testing the hypothesis; and an almost apologetic passage in +a letter to Lyell shows that, already, the attractions of biology are +beginning to predominate over those of geology. + +"I have lately been sadly tempted to be idle--[Footnote: Darwin generally +uses the word "idle" in a peculiar sense. He means by it working hard at +something he likes when he ought to be occupied with a less attractive +subject. Though it sounds paradoxical, there is a good deal to be said in +favour of this view of pleasant work.]that is, as far as pure Geology is +concerned--by the delightful number of new views which have been coming in +thickly and steadily--on the classification and affinities and instincts of +animals--bearing on the question of species. Note-book after note-book has +been filled with facts which begin to group themselves _clearly_ under +sub-laws." (I. p. 298.) + +The problem which was to be Darwin's chief subject of occupation for the +rest of his life thus presented itself, at first, mainly under its +distributional aspect. Why do species present certain relations in space +and in time? Why are the animals and plants of the Galapagos Archipelago so +like those of South America and yet different from them? Why are those of +the several islets more or less different from one another? Why are the +animals of the latest geological epoch in South America similar in +_facies_ to those which exist in the same region at the present day, +and yet specifically or generically different? + +The reply to these questions, which was almost universally received fifty +years ago, was that animals and plants were created such as they are; and +that their present distribution, at any rate so far as terrestrial +organisms are concerned, has been effected by the migration of their +ancestors from the region in which the ark stranded after the subsidence of +the deluge. It is true that the geologists had drawn attention to a good +many tolerably serious difficulties in the way of the diluvial part of this +hypothesis, no less than to the supposition that the work of creation had +occupied only a brief space of time. But even those, such as Lyell, who +most strenuously argued in favour of the sufficiency of natural causes for +the production of the phenomena of the inorganic world, held stoutly by the +hypothesis of creation in the case of those of the world of life. + +For persons who were unable to feel satisfied with the fashionable +doctrine, there remained only two alternatives--the hypothesis of +spontaneous generation, and that of descent with modification. The former +was simply the creative hypothesis with the creator left out; the latter +had already been propounded by De Maillet and Erasmus Darwin, among others; +and, later, systematically expounded by Lamarck. But in the eyes of the +naturalist of the "Beagle" (and, probably, in those of most sober +thinkers), the advocates of transmutation had done the doctrine they +expounded more harm than good. + +Darwin's opinion of the scientific value of the "Zoonomia" has already been +mentioned. His verdict on Lamarck is given in the following passage of a +letter to Lyell (March, 1863):-- + +"Lastly, you refer repeatedly to my view as a modification of Lamarck's +doctrine of development and progression. If this is your deliberate opinion +there is nothing to be said, but it does not seem so to me. Plato, Buffon, +my grandfather, before Lamarck and others, propounded the _obvious_ +view that if species were not created separately they must have descended +from other species, and I can see nothing else in common between the +"Origin" and Lamarck. I believe this way of putting the case is very +injurious to its acceptance, as it implies necessary progression, and +closely connects Wallace's and my views with what I consider, after two +deliberate readings, as a wretched book, and one from which (I well +remember to my surprise) I gained nothing." + +"But," adds Darwin with a little touch of banter, "I know you rank it +higher, which is curious, as it did not in the least shake your belief." +(III. p. 14; see also p. 16, "to me it was an absolutely useless book.") + +Unable to find any satisfactory theory of the process of descent with +modification in the works of his predecessors, Darwin proceeded to lay the +foundations of his own views independently; and he naturally turned, in the +first place, to the only certainly known examples of descent with +modification, namely, those which are presented by domestic animals and +cultivated plants. He devoted himself to the study of these cases with a +thoroughness to which none of his predecessors even remotely approximated; +and he very soon had his reward in the discovery "that selection was the +keystone of man's success in making useful races of animals and plants." +(I. p. 83.) + +This was the first step in Darwin's progress, though its immediate result +was to bring him face to face with a great difficulty. "But how selection +could be applied to organisms living in a state of nature remained for some +time a mystery to me." (I. p. 83.) + +The key to this mystery was furnished by the accidental perusal of the +famous essay of Malthus "On Population" in the autumn of 1838. The +necessary result of unrestricted multiplication is competition for the +means of existence. The success of one competitor involves the failure of +the rest, that is, their extinction; and this "selection" is dependent on +the better adaptation of the successful competitor to the conditions of the +competition. Variation occurs under natural, no less than under artificial, +conditions. Unrestricted multiplication implies the competition of +varieties and the selection of those which are relatively best adapted to +the conditions. + +Neither Erasmus Darwin, nor Lamarck, had any inkling of the possibility of +this process of "natural selection"; and though it had been foreshadowed by +Wells in 1813, and more fully stated by Matthew in 1831, the speculations +of the latter writer remained unknown to naturalists until after the +publication of the "Origin of Species." + +Darwin found in the doctrine of the selection of favourable variations by +natural causes, which thus presented itself to his mind, not merely a +probable theory of the origin of the diverse species of living forms, but +that explanation of the phenomena of adaptation, which previous +speculations had utterly failed to give. The process of natural selection +is, in fact, dependent on adaptation--it is all one, whether one says that +the competitor which survives is the "fittest" or the "best adapted." And +it was a perfectly fair deduction that even the most complicated +adaptations might result from the summation of a long series of simple +favourable variations. + +Darwin notes as a serious defect in the first sketch of his theory that he +had omitted to consider one very important problem, the solution of which +did not occur to him till some time afterwards. "This problem is the +tendency in organic beings descended from the same stock to diverge in +character as they become modified.... The solution, as I believe, is that +the modified offspring of all dominant and increasing forms tend to become +adapted to many and highly diversified places in the economy of nature." +(I. p. 84.) + +It is curious that so much importance should be attached to this +supplementary idea. It seems obvious that the theory of the origin of +species by natural selection necessarily involves the divergence of the +forms selected. An individual which varies, _ipso facto_ diverges from +the type of its species; and its progeny, in which the variation becomes +intensified by selection, must diverge still more, not only from the parent +stock, but from any other race of that stock starting from, a variation of +a different character. The selective process could not take place unless +the selected variety was either better adapted to the conditions than the +original stock, or adapted to other conditions than the original stock. In +the first case, the original stock would be sooner or later extirpated; in +the second, the type, as represented by the original stock and the variety, +would occupy more diversified stations than it did before. + +The theory, essentially such as it was published fourteen years later, was +written out in 1844, and Darwin was so fully convinced of the importance of +his work, as it then stood, that he made special arrangements for its +publication in case of his death. But it is a singular example of reticent +fortitude, that, although for the next fourteen years the subject never +left his mind, and during the latter half of that period he was constantly +engaged in amassing facts bearing upon it from wide reading, a colossal +correspondence, and a long series of experiments, only two or three friends +were cognisant of his views. To the outside world he seemed to have his +hands quite sufficiently full of other matters. In 1844, he published his +observations on the volcanic islands visited during the voyage of the +"Beagle." In 1845, a largely remodelled edition of his "Journal" made its +appearance, and immediately won, as it has ever since held, the favour of +both the scientific and the unscientific public. In 1846, the "Geological +Observations in South America" came out, and this book was no sooner +finished than Darwin set to work upon the Cirripedes. He was led to +undertake this long and heavy task, partly by his desire to make out the +relations of a very anomalous form which he had discovered on the coast of +Chili; and partly by a sense of "presumption in accumulating facts and +speculating on the subject of variation without having worked out my due +share of species." (II. p. 31.) The eight or nine years of labour, which +resulted in a monograph of first-rate importance in systematic zoology (to +say nothing of such novel points as the discovery of complemental males), +left Darwin no room to reproach himself on this score, and few will share +his "doubt whether the work was worth the consumption of so much time." (I. +p. 82.) + +In science no man can safely speculate about the nature and relation of +things with which he is unacquainted at first hand, and the acquirement of +an intimate and practical knowledge of the process of species-making and of +all the uncertainties which underlie the boundaries between species and +varieties, drawn by even the most careful and conscientious systematists +[Footnote: "After describing a set of forms as distinct species, tearing up +my MS., and making them one species, tearing that up and making them +separate, and then making them one again (which has happened to me), I have +gnashed my teeth, cursed species, and asked what sin I had committed to be +so punished." (II. p. 40.) Is there any naturalist provided with a logical +sense and a large suite of specimens, who has not undergone pangs of the +sort described in this vigorous paragraph, which might, with advantage, be +printed on the title-page of every systematic monograph as a warning to the +uninitiated?] were of no less importance to the author of the "Origin of +Species" than was the bearing of the Cirripede work upon "the principles of +a natural classification." (I. p. 81.) No one, as Darwin justly observes, +has a "right to examine the question of species who has not minutely +described many." (II. p. 39.) + +In September, 1854, the Cirripede work was finished, "ten thousand +barnacles" had been sent "out of the house, all over the world," and Darwin +had the satisfaction of being free to turn again to his "old notes on +species." In 1855, he began to breed pigeons, and to make observations on +the effects of use and disuse, experiments on seeds, and so on, while +resuming his industrious collection of facts, with a view "to see how far +they favour or are opposed to the notion that wild species are mutable or +immutable. I mean with my utmost power to give all arguments and facts on +both sides. I have a _number_ of people helping me every way, and +giving me most valuable assistance; but I often doubt whether the subject +will not quite overpower me." (II. p. 49.) + +Early in 1856, on Lyell's advice, Darwin began to write out his views on +the origin of species on a scale three or four times as extensive as that +of the work published in 1859. In July of the same year he gave a brief +sketch of his theory in a letter to Asa Gray; and, in the year 1857, his +letters to his correspondents show him to be busily engaged on what he +calls his "big book." (II. pp. 85, 94.) In May, 1857, Darwin writes to +Wallace: "I am now preparing my work [on the question how and in what way +do species and varieties differ from each other] for publication, but I +find the subject so very large, that, though I have written many chapters, +I do not suppose I shall go to press for two years." (II. p. 95.) In +December, 1857, he writes, in the course of a long letter to the same +correspondent, "I am extremely glad to hear that you are attending to +distribution in accordance with theoretical ideas. I am a firm believer +that without speculation there is no good and original observation." (II. +p. 108.) [Footnote: The last remark contains a pregnant truth, but it must +be confessed it hardly squares with the declaration in the +_Autobiography_, (I. p. 83), that he worked on "true Baconian +principles."] In June, 1858, he received from Mr. Wallace, then in the +Malay Archipelago, an "Essay on the tendency of varieties to depart +indefinitely from the original type," of which Darwin says, "If Wallace had +my MS. sketch written out in 1842 he could not have made a better short +abstract! Even his terms stand now as heads of my chapters. Please return +me the MS., which he does not say he wishes me to publish, but I shall, of +course, at once write and offer to send it to any journal. So all my +originality, whatever it may amount to, will be smashed, though my book, if +ever it will have any value, will not be deteriorated; as all the labour +consists in the application of the theory." (II. p. 116.) + +Thus, Darwin's first impulse was to publish Wallace's essay without note or +comment of his own. But, on consultation with Lyell and Hooker, the latter +of whom had read the sketch of 1844, they suggested, as an undoubtedly more +equitable course, that extracts from the MS. of 1844 and from the letter to +Dr. Asa Gray should be communicated to the Linnean Society along with +Wallace's essay. The joint communication was read on July 1, 1858, and +published under the title "On the Tendency of Species to form Varieties; +and on the Perpetuation of Varieties and Species by Natural Means of +Selection." This was followed, on Darwin's part, by the composition of a +summary account of the conclusions to which his twenty years' work on the +species question had led him. It occupied him for thirteen months, and +appeared in November, 1859, under the title "On the Origin of Species by +means of Natural Selection or the Preservation of Favoured Races in the +Struggle of Life." + +It is doubtful if any single book, except the "Principia," ever worked so +great and so rapid a revolution in science, or made so deep an impression +on the general mind. It aroused a tempest of opposition and met with +equally vehement support, and it must be added that no book has been more +widely and persistently misunderstood by both friends and foes. In 1861, +Darwin remarks to a correspondent, "You understand my book perfectly, and +that I find a very rare event with my critics." (I. p. 313.) The immense +popularity which the "Origin" at once acquired was no doubt largely due to +its many points of contact with philosophical and theological questions in +which every intelligent man feels a profound interest; but a good deal must +be assigned to a somewhat delusive simplicity of style, which tends to +disguise the complexity and difficulty of the subject, and much to the +wealth of information on all sorts of curious problems of natural history, +which is made accessible to the most unlearned reader. But long occupation +with the work has led the present writer to believe that the "Origin of +Species" is one of the hardest of books to master; [Footnote: He is +comforted to find that probably the best qualified judge among all the +readers of the _Origin_ in 1859 was of the same opinion. Sir J. Hooker +writes, "It is the very hardest book to read, to full profit, that I ever +tried." (II. p. 242.)] and he is justified in this conviction by observing +that although the "Origin" has been close on thirty years before the world, +the strangest misconceptions of the essential nature of the theory therein +advocated are still put forth by serious writers. + +Although, then, the present occasion is not suitable for any detailed +criticism of the theory, or of the objections which have been brought +against it, it may not be out of place to endeavour to separate the +substance of the theory from its accidents; and to show that a variety not +only of hostile comments, but of friendly would-be improvements lose their +_raison d'être_ to the careful student. Observation proves the +existence among all living beings of phenomena of three kinds, denoted by +the terms heredity, variation, and multiplication. Progeny tend to resemble +their parents; nevertheless all their organs and functions are susceptible +of departing more or less from the average parental character; and their +number is in excess of that of their parents. Severe competition for the +means of living, or the struggle for existence, is a necessary consequence +of unlimited multiplication; while selection, or the preservation of +favourable variations and the extinction of others, is a necessary +consequence of severe competition. "Favourable variations" are those which +are better adapted to surrounding conditions. It follows, therefore, that +every variety which is selected into a species is so favoured and preserved +in consequence of being, in some one or more respects, better adapted to +its surroundings than its rivals. In other words, every species which +exists, exists in virtue of adaptation, and whatever accounts for that +adaptation accounts for the existence of the species. + +To say that Darwin has put forward a theory of the adaptation of species, +but not of their origin, is therefore to misunderstand the first principles +of the theory. For, as has been pointed out, it is a necessary consequence +of the theory of selection that every species must have some one or more +structural or functional peculiarities, in virtue of the advantage +conferred by which, it has fought through the crowd of its competitors and +achieved a certain duration. In this sense, it is true that every species +has been "originated" by selection. + +There is another sense, however, in which it is equally true that selection +originates nothing. "Unless profitable variations ... occur natural +selection can do nothing" ("Origin," Ed. I. p. 82). "Nothing can be +effected unless favourable variations occur" (_ibid_., p. 108). "What +applies to one animal will apply throughout time to all animals--that is, +if they vary--for otherwise natural selection can do nothing. So it will be +with plants" (_ibid_., p. 113). Strictly speaking, therefore, the +origin of species in general lies in variation; while the origin of any +particular species lies, firstly, in the occurrence, and secondly, in the +selection and preservation of a particular variation. Clearness on this +head will relieve one from the necessity of attending to the fallacious +assertion that natural selection is a _deus ex machinâ_, or occult +agency. + +Those, again, who confuse the operation of the natural causes which bring +about variation and selection with what they are pleased to call "chance" +can hardly have read the opening paragraph of the fifth chapter of the +"Origin" (Ed. I, p. 131): "I have sometimes spoken as if the variations ... +had been due to chance. This is of course a wholly incorrect expression, +but it seems to acknowledge plainly our ignorance of the cause of each +particular variation." + +Another point of great importance to the right comprehension of the theory, +is, that while every species must needs have some adaptive advantageous +characters to which it owes its preservation by selection, it may possess +any number of others which are neither advantageous nor disadvantageous, +but indifferent, or even slightly disadvantageous. (_Ibid_., p. 81.) +For variations take place, not merely in one organ or function at a time, +but in many; and thus an advantageous variation, which gives rise to the +selection of a new race or species, may be accompanied by others which are +indifferent, but which are just as strongly hereditary as the advantageous +variations. The advantageous structure is but one product of a modified +general constitution which may manifest itself by several other products; +and the selective process carries the general constitution along with the +advantageous special peculiarity. A given species of plant may owe its +existence to the selective adaptation of its flowers to insect fertilisers; +but the character of its leaves may be the result of variations of an +indifferent character. It is the origin of variations of this kind to which +Darwin refers in his frequent reference to what he calls "laws of +correlation of growth" or "correlated variation." + +These considerations lead us further to see the inappropriateness of the +objections raised to Darwin's theory on the ground that natural selection +does not account for the first commencements of useful organs. But it does +not pretend to do so. The source of such commencements is necessarily to be +sought in different variations, which remain unaffected by selection until +they have taken such a form as to become utilisable in the struggle for +existence. + +It is not essential to Darwin's theory that anything more should be assumed +than the facts of heredity, variation, and unlimited multiplication; and +the validity of the deductive reasoning as to the effect of the last (that +is, of the struggle for existence which it involves) upon the varieties +resulting from the operation of the former. Nor is it essential that one +should take up any particular position in regard to the mode of variation, +whether, for example, it takes place _per saltum_ or gradually; +whether it is definite in character or indefinite. Still less are those who +accept the theory bound to any particular views as to the causes of +heredity or of variation. + +That Darwin held strong opinions on some or all of these points may be +quite true; but, so far as the theory is concerned, they must be regarded +as _obiter dicta_. With respect to the causes of variation, Darwin's +opinions are, from first to last, put forward altogether tentatively. In +the first edition of the "Origin," he attributes the strongest influence to +changes in the conditions of life of parental organisms, which he appears +to think act on the germ through the intermediation of the sexual organs. +He points out, over and over again, that habit, use, disuse, and the direct +influence of conditions have some effect, but he does not think it great, +and he draws attention to the difficulty of distinguishing between effects +of these agencies and those of selection. There is, however, one class of +variations which he withdraws from the direct influence of selection, +namely, the variations in the fertility of the sexual union of more or less +closely allied forms. He regards less fertility, or more or less complete +sterility, as "incidental to other acquired differences." (_Ibid_., p. +245.) + +Considering the difficulties which surround the question of the causes of +variation, it is not to be wondered at, that Darwin should have inclined, +sometimes, rather more to one and, sometimes, rather more to another of the +possible alternatives. There is little difference between the last edition +of the "Origin" (1872) and the first on this head. In 1876, however, he +writes to Moritz Wagner, "In my opinion, the greatest error which I have +committed has been not allowing sufficient weight to the direct action of +the environments, i.e., food, climate, &c., independently of natural +selection. ...When I wrote the 'Origin,' and for some years afterwards, I +could find little good evidence of the direct action of the environment; +now there is a large body of evidence, and your case of the Saturnia is one +of the most remarkable of which I have heard." (III, p. 159.) But there is +really nothing to prevent the most tenacious adherent to the theory of +natural selection from taking any view he pleases as to the importance of +the direct influence of conditions and the hereditary transmissibility of +the modifications which they produce. In fact, there is a good deal to be +said for the view that the so-called direct influence of conditions is +itself a case of selection. Whether the hypothesis of Pangenesis be +accepted or rejected, it can hardly be doubted that the struggle for +existence goes on not merely between distinct organisms, but between the +physiological units of which each organism is composed, and that changes in +external conditions favour some and hinder others. + +After a short stay in Cambridge, Darwin resided in London for the first +five years which followed his return to England; and for three years, he +held the post of Secretary to the Geological Society, though he shared to +the full his friend Lyell's objection to entanglement in such engagements. +In fact, he used to say in later life, more than half in earnest, that he +gave up hoping for work from men who accepted official duties and, +especially, Government appointments. Happily for him, he was exempted from +the necessity of making any sacrifice of this kind, but an even heavier +burden was laid upon him. During the earlier half of his voyage Darwin +retained the vigorous health of his boyhood, and indeed proved himself to +be exceptionally capable of enduring fatigue and privation. An anomalous +but severe disorder, which laid him up for several weeks at Valparaiso in +1834, however, seems to have left its mark on his constitution; and, in the +later years of his London life, attacks of illness, usually accompanied by +severe vomiting and great prostration of strength, became frequent. As he +grew older, a considerable part of every day, even at his best times, was +spent in misery; while, not unfrequently, months of suffering rendered work +of any kind impossible. Even Darwin's remarkable tenacity of purpose and +methodical utilisation of every particle of available energy could not have +enabled him to achieve a fraction of the vast amount of labour he got +through, in the course of the following forty years, had not the wisest and +the most loving care unceasingly surrounded him from the time of his +marriage in 1839. As early as 1842, the failure of health was so marked +that removal from London became imperatively necessary; and Darwin +purchased a house and grounds at Down, a solitary hamlet in Kent, which was +his home for the rest of his life. Under the strictly regulated conditions +of a valetudinarian existence, the intellectual activity of the invalid +might have put to shame most healthy men; and, so long as he could hold his +head up, there was no limit to the genial kindness of thought and action +for all about him. Those friends who were privileged to share the intimate +life of the household at Down have an abiding memory of the cheerful +restfulness which pervaded and characterised it. + +After mentioning his settlement at Down, Darwin writes in his +Autobiography:-- + +"My chief enjoyment and sole employment throughout life has been scientific +work; and the excitement from such work makes me, for the time, forget, or +drives quite away, my daily discomfort. I have, therefore, nothing to +record during the rest of my life, except the publication of my several +books." (I, p. 79.) + +Of such works published subsequently to 1859, several are monographic +discussions of topics briefly dealt with in the "Origin," which, it must +always be recollected, was considered by the author to be merely an +abstract of an _opus majus_. + +The earliest of the books which may be placed in this category, "On the +Various Contrivances by which Orchids are Fertilised by Insects," was +published in 1862, and whether we regard its theoretical significance, the +excellence of the observations and the ingenuity of the reasonings which it +records, or the prodigious mass of subsequent investigation of which it has +been the parent, it has no superior in point of importance. The conviction +that no theory of the origin of species could be satisfactory which failed +to offer an explanation of the way in which mechanisms involving +adaptations of structure and function to the performance of certain +operations are brought about, was, from the first, dominant in Darwin's +mind. As has been seen, he rejected Lamarck's views because of their +obvious incapacity to furnish such an explanation in the case of the great +majority of animal mechanisms, and in that of all those presented by the +vegetable world. + +So far back as 1793, the wonderful work of Sprengel had established, beyond +any reasonable doubt, the fact that, in a large number of cases, a flower +is a piece of mechanism the object of which is to convert insect visitors +into agents of fertilisation. Sprengel's observations had been most +undeservedly neglected and well-nigh forgotten; but Robert Brown having +directed Darwin's attention to them in 1841, he was attracted towards the +subject, and verified many of Sprengel's statements. (III, p. 258.) It may +be doubted whether there was a living botanical specialist, except perhaps +Brown, who had done as much. If, however, adaptations of this kind were to +be explained by natural selection, it was necessary to show that the plants +which were provided with mechanisms for ensuring the aid of insects as +fertilisers, were by so much the better fitted to compete with their +rivals. This Sprengel had not done. Darwin had been attending to cross +fertilisation in plants so far back as 1839, from having arrived, in the +course of his speculations on the origin of species, at the conviction +"that crossing played an important part in keeping specific forms constant" +(I, p. 90). The further development of his views on the importance of cross +fertilisation appears to have taken place between this time and 1857, when +he published his first papers on the fertilisation of flowers in the +"Gardener's Chronicle." If the conclusion at which he ultimately arrived, +that cross fertilisation is favourable to the fertility of the parent and +to the vigour of the offspring, is correct, then it follows that all those +mechanisms which hinder self-fertilisation and favour crossing must be +advantageous in the struggle for existence; and, the more perfect the +action of the mechanism, the greater the advantage. Thus the way lay open +for the operation of natural selection in gradually perfecting the flower +as a fertilisation-trap. Analogous reasoning applies to the fertilising +insect. The better its structure is adapted to that of the trap, the more +will it be able to profit by the bait, whether of honey or of pollen, to +the exclusion of its competitors. Thus, by a sort of action and reaction, a +two-fold series of adaptive modifications will be brought about. + +In 1865, the important bearing of this subject on his theory led Darwin to +commence a great series of laborious and difficult experiments on the +fertilisation of plants, which occupied him for eleven years, and furnished +him with the unexpectedly strong evidence in favour of the influence of +crossing which he published in 1876, under the title of "The Effects of +Cross and Self Fertilisation in the Vegetable Kingdom." Incidentally, as it +were, to this heavy piece of work, he made the remarkable series of +observations on the different arrangements by which crossing is favoured +and, in many cases, necessitated, which appeared in the work on "The +Different Forms of Flowers in Plants of the same Species" in 1877. + +In the course of the twenty years during which Darwin was thus occupied in +opening up new regions of investigation to the botanist and showing the +profound physiological significance of the apparently meaningless +diversities of floral structure, his attention was keenly alive to any +other interesting phenomena of plant life which came in his way. In his +correspondence, he not unfrequently laughs at himself for his ignorance of +systematic botany; and his acquaintance with vegetable anatomy and +physiology was of the slenderest. Nevertheless, if any of the less common +features of plant life came under his notice, that imperious necessity of +seeking for causes which nature had laid upon him, impelled, and indeed +compelled, him to inquire the how and the why of the fact, and its bearing +on his general views. And as, happily, the atavic tendency to frame +hypotheses was accompanied by an equally strong need to test them by +well-devised experiments, and to acquire all possible information before +publishing his results, the effect was that he touched no topic without +elucidating it. + +Thus the investigation of the operations of insectivorous plants, embodied +in the work on that topic published in 1875, was started fifteen years +before, by a passing observation made during one of Darwin's rare holidays. + +"In the summer of 1860, I was idling and resting near Hartfield, where two +species of Drosera abound; and I noticed that numerous insects had been +entrapped by the leaves. I carried home some plants, and on giving them +some insects saw the movements of the tentacles, and this made me think it +possible that the insects were caught for some special purpose. +Fortunately, a crucial test occurred to me, that of placing a large number +of leaves in various nitrogenous and non-nitrogenous fluids of equal +density; and as soon as I found that the former alone excited energetic +movements, it was obvious that here was a fine new field for +investigation." (I, p. 95.) + +The researches thus initiated led to the proof that plants are capable of +secreting a digestive fluid like that of animals, and of profiting by the +result of digestion; whereby the peculiar apparatuses of the insectivorous +plants were brought within the scope of natural selection. Moreover, these +inquiries widely enlarged our knowledge of the manner in which stimuli are +transmitted in plants, and opened up a prospect of drawing closer the +analogies between the motor processes of plants and those of animals. + +So with respect to the books on "Climbing Plants" (1875), and on the "Power +of Movement in Plants" (1880), Darwin says;-- + +"I was led to take up this subject by reading a short paper by Asa Gray, +published in 1858. He sent me some seeds, and on raising some plants I was +so much fascinated and perplexed by the revolving movements of the tendrils +and stems, which movements are really very simple, though appearing at +first sight very complex, that I procured various other kinds of climbing +plants and studied the whole subject.... Some of the adaptations displayed +by climbing plants are as beautiful as those of orchids for ensuring +cross-fertilisation." (I, p. 93.) + +In the midst of all this amount of work, remarkable alike for its variety +and its importance, among plants, the animal kingdom was by no means +neglected. A large moiety of "The Variation of Animals and Plants under +Domestication" (1868), which contains the _pièces justificatives_ of +the first chapter of the "Origin," is devoted to domestic animals, and the +hypothesis of "pangenesis" propounded in the second volume applies to the +whole living world. In the "Origin" Darwin throws out some suggestions as +to the causes of variation, but he takes heredity, as it is manifested by +individual organisms, for granted, as an ultimate fact; pangenesis is an +attempt to account for the phenomena of heredity in the organism, on the +assumption that the physiological units of which the organism is composed +give off gemmules, which, in virtue of heredity, tend to reproduce the unit +from which they are derived. + +That Darwin had the application of his theory to the origin of the human +species clearly in his mind in 1859, is obvious from a passage in the first +edition of "The Origin of Species." (Ed. I, p. 488.) "In the distant future +I see open fields for far more important researches. Psychology will be +based on a new foundation, that of the necessary acquirement of each mental +power and capacity by gradation. Light will be thrown on the origin of man +and his history." It is one of the curiosities of scientific literature, +that, in the face of this plain declaration, its author should have been +charged with concealing his opinions on the subject of the origin of man. +But he reserved the full statement of his views until 1871, when the +"Descent of Man" was published. The "Expression of the Emotions" +(originally intended to form only a chapter in the "Descent of Man") grew +into a separate volume, which appeared in 1872. Although always taking a +keen interest in geology, Darwin naturally found no time disposable for +geological work, even had his health permitted it, after he became +seriously engaged with the great problem of species. But the last of his +labours is, in some sense, a return to his earliest, inasmuch as it is an +expansion of a short paper read before the Geological Society more than +forty years before, and, as he says, "revived old geological thoughts" (I, +p. 98). In fact, "The Formation of Vegetable Mould through the Action of +Worms," affords as striking an example of the great results produced by the +long-continued operation of small causes as even the author of the +"Principles of Geology" could have desired. + +In the early months of 1882 Darwin's health underwent a change for the +worse; attacks of giddiness and fainting supervened, and on the 19th of +April he died. On the 24th, his remains were interred in Westminster Abbey, +in accordance with the general feeling that such a man as he should not go +to the grave without some public recognition of the greatness of his work. + +Mr. Darwin became a Fellow of the Royal Society in 1839; one of the Royal +Medals was awarded to him in 1853, and he received the Copley Medal in +1864. The "Life and Letters," edited with admirable skill and judgment by +Mr. Francis Darwin, gives a full and singularly vivid presentment of his +father's personal character, of his mode of work, and of the events of his +life. In the present brief obituary notice, the writer has attempted +nothing more than to select and put together those facts which enable us to +trace the intellectual evolution of one of the greatest of the many great +men of science whose names adorn the long roll of the Fellows of the Royal +Society. + + + + +XI + +ON OUR KNOWLEDGE OF THE CAUSES OF THE PHENOMENA OF ORGANIC NATURE + +[_Six Lectures to Working Men_.--1863.] + + + +I. THE PRESENT CONDITION OF ORGANIC NATURE + + +When it was my duty to consider what subject I would select for the six +lectures which I shall now have the pleasure of delivering to you, it +occurred to me that I could not do better than endeavour to put before you +in a true light, or in what I might perhaps with more modesty call, that +which I conceive myself to be the true light, the position of a book which +has been more praised and more abused, perhaps, than any book which has +appeared for some years;--I mean Mr. Darwin's work on the "Origin of +Species." That work, I doubt not, many of you have read; for I know the +inquiring spirit which is rife among you. At any rate, all of you will have +heard of it,--some by one kind of report and some by another kind of +report; the attention of all and the curiosity of all have been probably +more or less excited on the subject of that work. All I can do, and all I +shall attempt to do, is to put before you that kind of judgment which has +been formed by a man, who, of course, is liable to judge erroneously; but, +at any rate, of one whose business and profession it is to form judgments +upon questions of this nature. + +And here, as it will always happen when dealing with an extensive subject, +the greater part of my course--if, indeed, so small a number of lectures +can be properly called a course--must be devoted to preliminary matters, or +rather to a statement of those facts and of those principles which the work +itself dwells upon, and brings more or less directly before us. I have no +right to suppose that all or any of you are naturalists; and, even if you +were, the misconceptions and misunderstandings prevalent even among +naturalists, on these matters, would make it desirable that I should take +the course I now propose to take,--that I should start from the +beginning,--that I should endeavour to point out what is the existing state +of the organic world--that I should point out its past condition,--that I +should state what is the precise nature of the undertaking which Mr. Darwin +has taken in hand; that I should endeavour to show you what are the only +methods by which that undertaking can be brought to an issue, and to point +out to you how far the author of the work in question has satisfied those +conditions, how far he has not satisfied them, how far they are satisfiable +by man, and how far they are not satisfiable by man. + +To-night, in taking up the first part of the question, I shall endeavour to +put before you a sort of broad notion of our knowledge of the condition of +the living world. There are many ways of doing this. I might deal with it +pictorially and graphically. Following the example of Humboldt in his +"Aspects of Nature," I might endeavour to point out the infinite variety of +organic life in every mode of its existence, with reference to the +variations of climate and the like; and such an attempt would be fraught +with interest to us all; but considering the subject before us, such a +course would not be that best calculated to assist us. In an argument of +this kind we must go further and dig deeper into the matter; we must +endeavour to look into the foundations of living Nature, if I may so say, +and discover the principles involved in some of her most secret operations. +I propose, therefore, in the first place, to take some ordinary animal with +which you are all familiar, and by easily comprehensible and obvious +examples drawn from it, to show what are the kind of problems which living +beings in general lay before us; and I shall then show you that the same +problems are laid open to us by all kinds of living beings. But, first, let +me say in what sense I have used the words "organic nature." In speaking of +the causes which lead to our present knowledge of organic nature, I have +used it almost as an equivalent of the word "living," and for this +reason,--that in almost all living beings you can distinguish several +distinct portions set apart to do particular things and work in a +particular way. These are termed "organs," and the whole together is called +"organic." And as it is universally characteristic of them, the term +"organic" has been very conveniently employed to denote the whole of living +nature,--the whole of the plant world, and the whole of the animal world. + +Few animals can be more familiar to you than that whose skeleton is shown +on our diagram. You need not bother yourselves with this "_Equus +caballus_" written under it; that is only the Latin name of it, and does +not make it any better. It simply means the common horse. Suppose we wish +to understand all about the horse. Our first object must be to study the +structure of the animal. The whole of his body is inclosed within a hide, a +skin covered with hair; and if that hide or skin be taken off, we find a +great mass of flesh, or what is technically called muscle, being the +substance which by its power of contraction enables the animal to move. +These muscles move the hard parts one upon the other, and so give that +strength and power of motion which renders the horse so useful to us in the +performance of those services in which we employ him. + +And then, on separating and removing the whole of this skin and flesh, you +have a great series of bones, hard structures, bound together with +ligaments, and forming the skeleton which is represented here. + +In that skeleton there are a number of parts to be recognised. The long +series of bones, beginning from the skull and ending in the tail, is called +the spine, and those in front are the ribs; and then there are two pairs of +limbs, one before and one behind; and there are what we all know as the +fore-legs and the hind-legs. If we pursue our researches into the interior +of this animal, we find within the framework of the skeleton a great +cavity, or rather, I should say, two great cavities,--one cavity beginning +in the skull and running through the neck-bones, along the spine, and +ending in the tail, containing the brain and the spinal marrow, which are +extremely important organs. The second great cavity, commencing with the +mouth, contains the gullet, the stomach, the long intestine, and all the +rest of those internal apparatus which are essential for digestion; and +then in the same great cavity, there are lodged the heart and all the great +vessels going from it; and, besides that, the organs of respiration--the +lungs: and then the kidneys, and the organs of reproduction, and so on. Let +us now endeavour to reduce this notion of a horse that we now have, to some +such kind of simple expressions as can be at once, and without difficulty, +retained in the mind, apart from all minor details. If I make a transverse +section, that is, if I were to saw a dead horse across, I should find that, +if I left out the details, and supposing I took my section through the +anterior region, and through the fore-limbs, I should have here this kind +of section of the body (Fig. 1). + +[Illustration: Fig. 1] + +Here would be the upper part of the animal--that great mass of bones that +we spoke of as the spine (_a_, Fig. 1). Here I should have the +alimentary canal (_b_, Fig. 1). Here I should have the heart +(_c_, Fig. 1); and then you see, there would be a kind of double tube, +the whole being inclosed within the hide; the spinal marrow would be placed +in the upper tube (_a_, Fig. 1), and in the lower tube (_d d_, +Fig. 1), there would be the alimentary canal (_b_), and the heart +(_e_); and here I shall have the legs proceeding from each side. For +simplicity's sake, I represent them merely as stumps (_e e_, Fig. 1). +Now that is a horse--as mathematicians would say--reduced to its most +simple expression. Carry that in your minds, if you please, as a simplified +idea of the structure of the horse. The considerations which I have now put +before you belong to what we technically call the "Anatomy" of the horse. +Now, suppose we go to work upon these several parts,--flesh and hair, and +skin and bone, and lay open these various organs with our scalpels, and +examine them by means of our magnifying-glasses, and see what we can make +of them. We shall find that the flesh is made up of bundles of strong +fibres The brain and nerves, too, we shall find are made up of fibres, and +these queer-looking things that are called ganglionic corpuscles. If we +take a slice of the bone and examine it, we shall find that it is very like +this diagram of a section of the bone of on ostrich, though differing, of +course, in some details; and if we take any part whatsoever of the tissue, +and examine it, we shall find it all has a minute structure, visible only +under the microscope. All these parts constitute microscopic anatomy or +"Histology." These parts are constantly being changed; every part is +constantly growing, decaying, and being replaced during the life of the +animal. The tissue is constantly replaced by new material; and if you go +back to the young state of the tissue in the case of muscle, or in the case +of skin, or any of the organs I have mentioned, you will find that they all +come under the same condition. Every one of these microscopic filaments and +fibres (I now speak merely of the general character of the whole +process)--every one of these parts--could be traced down to some +modification of a tissue which can be readily divided into little particles +of fleshy matter, of that substance which is composed of the chemical +elements, carbon, hydrogen, oxygen, and nitrogen, having such a shape as +this (Fig. 2). These particles, into which all primitive tissues break up, +are called cells. If I were to make a section of a piece of the skin of my +hand, I should find that it was made up of these cells. If I examine the +fibres which form the various organs of all living animals, I should find +that all of them, at one time or other, had been formed out of a substance +consisting of similar elements; so that you see, just as we reduced the +whole body in the gross to that sort of simple expression given in Fig. 1, +so we may reduce the whole of the microscopic structural elements to a form +of even greater simplicity; just as the plan of the whole body may be so +represented in a sense (Fig. 1), so the primary structure of every tissue +may be represented by a mass of cells (Fig. 2). + +[Illustration: Fig. 2.] + +Having thus, in this sort of general way, sketched to you what I may call, +perhaps, the architecture of the body of the horse (what we term +technically its Morphology), I must now turn to another aspect. A horse is +not a mere dead structure: it is an active, living, working machine. +Hitherto we have, as it were, been looking at a steam-engine with the fires +out, and nothing in the boiler; but the body of the living animal is a +beautifully-formed active machine, and every part has its different work to +do in the working of that machine, which is what we call its life. The +horse, if you see him after his day's work is done, is cropping the grass +in the fields, as it may be, or munching the oats in his stable. What is he +doing? His jaws are working as a mill--and a very complex mill +too--grinding the corn, or crushing the grass to a pulp. As soon as that +operation has taken place, the food is passed down to the stomach, and +there it is mixed with the chemical fluid called the gastric juice, a +substance which has the peculiar property of making soluble and dissolving +out the nutritious matter in the grass, and leaving behind those parts +which are not nutritious; so that you have, first, the mill, then a sort of +chemical digester; and then the food, thus partially dissolved, is carried +back by the muscular contractions of the intestines into the hinder parts +of the body, while the soluble portions are taken up into the blood. The +blood is contained in a vast system of pipes, spreading through the whole +body, connected with a force-pump,--the heart,--which, by its position and +by the contractions of its valves, keeps the blood constantly circulating +in one direction, never allowing it to rest; and then, by means of this +circulation of the blood, laden as it is with the products of digestion, +the skin, the flesh, the hair, and every other part of the body, draws from +it that which it wants, and every one of these organs derives those +materials which are necessary to enable it to do its work. + +The action of each of these organs, the performance of each of these +various duties, involve in their operation a continual absorption of the +matters necessary for their support, from the blood and a constant +formation of waste products, which are returned to the blood, and conveyed +by it to the lungs and the kidneys, which are organs that have allotted to +them the office of extracting, separating, and getting rid of these waste +products; and thus the general nourishment, labour, and repair of the whole +machine are kept up with order and regularity. But not only is it a machine +which feeds and appropriates to its own support the nourishment necessary +to its existence--it is an engine for locomotive purposes. The horse +desires to go from one place to another; and to enable it to do this, it +has those strong contractile bundles of muscles attached to the bones of +its limbs, which are put in motion by means of a sort of telegraphic +apparatus formed by the brain and the great spinal cord running through the +spine or backbone; and to this spinal cord are attached a number of fibres +termed nerves, which proceed to all parts of the structure. By means of +these the eyes, nose, tongue, and skin--all the organs of +perception--transmit impressions or sensations to the brain, which acts as +a sort of great central telegraph-office, receiving impressions and sending +messages to all parts of the body, and putting in motion the muscles +necessary to accomplish any movement that maybe desired. So that you have +here an extremely complex and beautifully-proportioned machine, with all +its parts working harmoniously together towards one common object--the +preservation of the life of the animal. + +Now, note this: the horse makes up its waste by feeding, and its food is +grass or oats, or perhaps other vegetable products; therefore, in the long +run, the source of all this complex machinery lies in the vegetable +kingdom. But where does the grass, or the oat, or any other plant obtain +this nourishing food-producing material? At first it is a little seed, +which soon begins to draw into itself from the earth and the surrounding +air matters which in themselves contain no vital properties whatever; it +absorbs into its own substance water, an inorganic body; it draws into its +substance carbonic acid, an inorganic matter; and ammonia, another +inorganic matter, found in the air; and then, by some wonderful chemical +process, the details of which chemists do not yet understand, though they +are near foreshadowing them, it combines them into one substance, which is +known to us as "Protein," a complex compound of carbon, hydrogen, oxygen, +and nitrogen, which alone possesses the property of manifesting vitality +and of permanently supporting animal life. So that, you see, the waste +products of the animal economy, the effete materials which are continually +being thrown off by all living beings, in the form of organic matters, are +constantly replaced by supplies of the necessary repairing and rebuilding +materials drawn from the plants, which in their turn manufacture them, so +to speak, by a mysterious combination of those same inorganic materials. + +Let us trace out the history of the horse in another direction. After a +certain time, as the result of sickness or disease, the effect of accident, +or the consequence of old age, sooner or later, the animal dies. The +multitudinous operations of this beautiful mechanism flag in their +performance, the horse loses its vigour, and after passing through the +curious series of changes comprised in its formation and preservation, it +finally decays, and ends its life by going back into that inorganic world +from which all but an inappreciable fraction of its substance was derived. +Its bones become mere carbonate and phosphate of lime; the matter of its +flesh, and of its other parts, becomes, in the long run, converted into +carbonic acid, into water, and into ammonia. You will now, perhaps, +understand the curious relation of the animal with the plant, of the +organic with the inorganic world, which is shown in this diagram. + +[Illustration: Inorganic World Fig. 3.] + +The plant gathers these inorganic materials together and makes them up into +its own substance. The animal eats the plant and appropriates the +nutritious portions to its own sustenance, rejects and gets rid of the +useless matters; and, finally, the animal itself dies, and its whole body +is decomposed and returned into the inorganic world. There is thus a +constant circulation from one to the other, a continual formation of +organic life from inorganic matters, and as constant a return of the matter +of living bodies to the inorganic world; so that the materials of which our +bodies are composed are largely, in all probability, the substances which +constituted the matter of long extinct creations, but which have in the +interval constituted a part of the inorganic world. + +Thus we come to the conclusion, strange at first sight, that the MATTER +constituting the living world is identical with that which forms the +inorganic world. And not less true is it that, remarkable as are the powers +or, in other words, as are the FORCES which are exerted by living beings, +yet all these forces are either identical with those which exist in the +inorganic world, or they are convertible into them; I mean in just the same +sense as the researches of physical philosophers have shown that heat is +convertible into electricity, that electricity is convertible into +magnetism, magnetism into mechanical force or chemical force, and any one +of them with the other, each being measurable in terms of the other,--even +so, I say, that great law is applicable to the living world. Consider why +is the skeleton of this horse capable of supporting the masses of flesh and +the various organs forming the living body, unless it is because of the +action of the same forces of cohesion which combines together the particles +of matter composing this piece of chalk? What is there in the muscular +contractile power of the animal but the force which is expressible, and +which is in a certain sense convertible, into the force of gravity which it +overcomes? Or, if you go to more hidden processes, in what does the process +of digestion differ from those processes which are carried on in the +laboratory of the chemist? Even if we take the most recondite and most +complex operations of animal life--those of the nervous system, these of +late years have been shown to be--I do not say identical in any sense with +the electrical processes--but this has been shown, that they are in some +way or other associated with them; that is to say, that every amount of +nervous action is accompanied by a certain amount of electrical disturbance +in the particles of the nerves in which that nervous action is carried on. +In this way the nervous action is related to electricity in the same way +that heat is related to electricity; and the same sort of argument which +demonstrates the two latter to be related to one another shows that the +nervous forces are correlated to electricity; for the experiments of M. +Dubois Reymond and others have shown that whenever a nerve is in a state of +excitement, sending a message to the muscles or conveying an impression to +the brain, there is a disturbance of the electrical condition of that nerve +which does not exist at other times; and there are a number of other facts +and phenomena of that sort; so that we come to the broad conclusion that +not only as to living matter itself, but as to the forces that matter +exerts, there is a close relationship between the organic and the inorganic +world--the difference between them arising from the diverse combination and +disposition of identical forces, and not from any primary diversity, so far +as we can see. + +I said just now that the horse eventually died and became converted into +the same inorganic substances from whence all but an inappreciable fraction +of its substance demonstrably originated, so that the actual wanderings of +matter are as remarkable as the transmigrations of the soul fabled by +Indian tradition. But before death has occurred, in the one sex or the +other, and in fact in both, certain products or parts of the organism have +been set free, certain parts of the organisms of the two sexes have come +into contact with one another, and from that conjunction, from that union +which then takes place, there results the formation of a new being. At +stated times the mare, from a particular part of the interior of her body, +called the ovary, gets rid of a minute particle of matter comparable in all +essential respects with that which we called a cell a little while since, +which cell contains a kind of nucleus in its centre, surrounded by a clear +space and by a viscid mass of protein substance (Fig. 2); and though it is +different in appearance from the eggs which we are mostly acquainted with, +it is really an egg. After a time this minute particle of matter, which may +only be a small fraction of a grain in weight, undergoes a series of +changes,--wonderful, complex changes. Finally, upon its surface there is +fashioned a little elevation, which afterwards becomes divided and marked +by a groove. The lateral boundaries of the groove extend upwards and +downwards, and at length give rise to a double tube. In the upper and +smaller tube the spinal marrow and brain are fashioned; in the lower, the +alimentary canal and heart; and at length two pairs of buds shoot out at +the sides of the body, and they are the rudiments of the limbs. In fact a +true drawing of a section of the embryo in this state would in all +essential respects resemble that diagram of a horse reduced to its simplest +expression, which I first placed before you (Fig. 1). + +Slowly and gradually these changes take place. The whole of the body, at +first, can be broken up into "cells," which become in one place +metamorphosed into muscle,--in another place into gristle and bone,--in +another place into fibrous tissue,--and in another into hair; every part +becoming gradually and slowly fashioned, as if there were an artificer at +work in each of these complex structures that I have mentioned. This +embryo, as it is called, then passes into other conditions. I should tell +you that there is a time when the embryos of neither dog, nor horse, nor +porpoise, nor monkey, nor man, can be distinguished by any essential +feature one from the other; there is a time when they each and all of them +resemble this one of the dog. But as development advances, all the parts +acquire their speciality, till at length you have the embryo converted into +the form of the parent from which it started. So that you see, this living +animal, this horse, begins its existence as a minute particle of +nitrogenous matter, which, being supplied with nutriment (derived, as I +have shown, from the inorganic world), grows up according to the special +type and construction of its parents, works and undergoes a constant waste, +and that waste is made good by nutriment derived from the inorganic world; +the waste given off in this way being directly added to the inorganic +world. Eventually the animal itself dies, and, by the process of +decomposition, its whole body is returned to those conditions of inorganic +matter in which its substance originated. + +This, then, is that which is true of every living form, from the lowest +plant to the highest animal--to man himself. You might define the life of +every one in exactly the same terms as those which I have now used; the +difference between the highest and the lowest being simply in the +complexity of the developmental changes, the variety of the structural +forms, and the diversity of the physiological functions which are exerted +by each. + +If I were to take an oak tree, as a specimen of the plant world, I should +find that it originated in an acorn, which, too, commenced in a cell; the +acorn is placed in the ground, and it very speedily begins to absorb the +inorganic matters I have named, adds enormously to its bulk, and we can see +it, year after year, extending itself upward and downward, attracting and +appropriating to itself inorganic materials, which it vivifies, and +eventually, as it ripens, gives off its own proper acorns, which again run +the same course. But I need not multiply examples,--from the highest to the +lowest the essential features of life are the same as I have described in +each of these cases. + +So much, then, for these particular features of the organic world, which +you can understand and comprehend, so long as you confine yourself to one +sort of living being, and study that only. + +But, as you know, horses are not the only living creatures in the world; +and again, horses, like all other animals, have certain limits--are +confined to a certain area on the surface of the earth on which we +live,--and, as that is the simpler matter, I may take that first. In its +wild state, and before the discovery of America, when the natural state of +things was interfered with by the Spaniards, the horse was only to be found +in parts of the earth which are known to geographers as the Old World; that +is to say, you might meet with horses in Europe, Asia, or Africa; but there +were none in Australia, and there were none whatsoever in the whole +continent of America, from Labrador down to Cape Horn. This is an empirical +fact, and it is what is called, stated in the way I have given it you, the +"Geographical Distribution" of the horse. + +Why horses should be found in Europe, Asia, and Africa, and not in America, +is not obvious; the explanation that the conditions of life in America are +unfavourable to their existence, and that, therefore, they had not been +created there, evidently does not apply; for when the invading Spaniards, +or our own yeomen farmers, conveyed horses to these countries for their own +use, they were found to thrive well and multiply very rapidly; and many are +even now running wild in those countries, and in a perfectly natural +condition. Now, suppose we were to do for every animal what we have here +done for the horse,--that is, to mark off and distinguish the particular +district or region to which each belonged; and supposing we tabulated all +these results, that would be called the Geographical Distribution of +animals, while a corresponding study of plants would yield as a result the +Geographical Distribution of plants. + +I pass on from that now, as I merely wished to explain to you what I meant +by the use of the term "Geographical Distribution." As I said, there is +another aspect, and a much more important one, and that is, the relations +of the various animals to one another. The horse is a very well-defined +matter-of-fact sort of animal, and we are all pretty familiar with its +structure. I dare say it may have struck you, that it resembles very much +no other member of the animal kingdom, except perhaps the zebra or the ass. +But let me ask you to look along these diagrams. Here is the skeleton of +the horse, and here the skeleton of the dog. You will notice that we have +in the horse a skull, a backbone and ribs, shoulder-blades and +haunch-bones. In the fore-limb, one upper arm-bone, two fore arm-bones, +wrist-bones (wrongly called knee), and middle hand-bones, ending in the +three bones of a finger, the last of which is sheathed in the horny hoof of +the fore-foot: in the hind-limb, one thigh-bone, two leg-bones, +ankle-bones, and middle foot-bones, ending in the three bones of a toe, the +last of which is encased in the hoof of the hind-foot. Now turn to the +dog's skeleton. We find identically the same bones, but more of them, there +being more toes in each foot, and hence more toe-bones. + +Well, that is a very curious thing! The fact is that the dog and the +horse--when one gets a look at them without the outward impediments of the +skin--are found to be made in very much the same sort of fashion. And if I +were to make a transverse section of the dog, I should find the same organs +that I have already shown you as forming parts of the horse. Well, here is +another skeleton--that of a kind of lemur--you see he has just the same +bones; and if I were to make a transverse section of it, it would be just +the same again. In your mind's eye turn him round, so as to put his +backbone in a position inclined obliquely upwards and forwards, just as in +the next three diagrams, which represent the skeletons of an orang, a +chimpanzee, and a gorilla, and you find you have no trouble in identifying +the bones throughout; and lastly turn to the end of the series, the diagram +representing a man's skeleton, and still you find no great structural +feature essentially altered. There are the same bones in the same +relations. From the horse we pass on and on, with gradual steps until we +arrive at last at the highest known forms. On the other hand, take the +other line of diagrams, and pass from the horse downwards in the scale to +this fish; and still, though the modifications are vastly greater, the +essential framework of the organisation remains unchanged. Here, for +instance, is a porpoise: here is its strong backbone, with the cavity +running through it, which contains the spinal cord; here are the ribs, here +the shoulder-blade; here is the little short upper-arm bone, here are the +two forearm bones, the wrist-bone, and the finger-bones. + +Strange, is it not, that the porpoise should have in this queer-looking +affair--its flapper (as it is called), the same fundamental elements as the +fore-leg of the horse or the dog, or the ape or man; and here you will +notice a very curious thing,--the hinder limbs are absent. Now, let us make +another jump. Let us go to the codfish: here you see is the forearm, in +this large pectoral fin--carrying your mind's eye onward from the flapper +of the porpoise. And here you have the hinder limbs restored in the shape +of these ventral fins. If I were to make a transverse section of this, I +should find just the same organs that we have before noticed. So that, you +see, there comes out this strange conclusion as the result of our +investigations, that the horse, when examined and compared with other +animals, is found by no means to stand alone in Nature; but that there are +an enormous number of other creatures which have backbones, ribs, and legs, +and other parts arranged in the same general manner, and in all their +formation exhibiting the same broad peculiarities. + +I am sure that you cannot have followed me even in this extremely +elementary exposition of the structural relations of animals, without +seeing what I have been driving at all through, which is, to show you that, +step by step, naturalists have come to the idea of a unity of plan, or +conformity of construction, among animals which appeared at first sight to +be extremely dissimilar. + +And here you have evidence of such a unity of plan among all the animals +which have backbones, and which we technically call _Vertebrata_. But +there are multitudes of other animals, such as crabs, lobsters, spiders, +and so on, which we term _Annulosa_. In these I could not point out to +you the parts that correspond with those of the horse,--the backbone, for +instance,--as they are constructed upon a very different principle, which +is also common to all of them; that is to say, the lobster, the spider, and +the centipede, have a common plan running through their whole arrangement, +in just the same way that the horse, the dog, and the porpoise assimilate +to each other. + +Yet other creatures--whelks, cuttlefishes, oysters, snails, and all their +tribe (_Mollusca_)--resemble one another in the same way, but differ +from both _Vertebrata_ and _Annulosa_; and the like is true of +the animals called _Coelenterata_ (Polypes) and _Protozoa_ +(animalcules and sponges). + +Now, by pursuing this sort of comparison, naturalists have arrived at the +conviction that there are,--some think five, and some seven,--but certainly +not more than the latter number--and perhaps it is simpler to assume +five--distinct plans or constructions in the whole of the animal world; and +that the hundreds of thousands of species of creatures on the surface of +the earth, are all reducible to those five, or, at most, seven, plans of +organisation. + +But can we go no further than that? When one has got so far, one is tempted +to go on a step and inquire whether we cannot go back yet further and bring +down the whole to modifications of one primordial unit. The anatomist +cannot do this; but if he call to his aid the study of development, he can +do it. For we shall find that, distinct as those plans are, whether it be a +porpoise or man, or lobster, or any of those other kinds I have mentioned, +every one begins its existence with one and the same primitive form,--that +of the egg, consisting, as we have seen, of a nitrogenous substance, having +a small particle or nucleus in the centre of it. Furthermore, the earlier +changes of each are substantially the same. And it is in this that lies +that true "unity of organisation" of the animal kingdom which has been +guessed at and fancied for many years; but which it has been left to the +present time to be demonstrated by the careful study of development. But is +it possible to go another step further still, and to show that in the same +way the whole of the organic world is reducible to one primitive condition +of form? Is there among the plants the same primitive form of organisation, +and is that identical with that of the animal kingdom? The reply to that +question, too, is not uncertain or doubtful. It is now proved that every +plant begins its existence under the same form; that is to say, in that of +a cell--a particle of nitrogenous matter having substantially the same +conditions. So that if you trace back the oak to its first germ, or a man, +or a horse, or lobster, or oyster, or any other animal you choose to name, +you shall find each and all of these commencing their existence in forms +essentially similar to each other; and, furthermore, that the first +processes of growth, and many of the subsequent modifications, are +essentially the same in principle in almost all. + +In conclusion, let me, in a few words, recapitulate the positions which I +have laid down. And you must understand that I have not been talking mere +theory; I have been speaking of matters which are as plainly demonstrable +as the commonest propositions of Euclid--of facts that must form the basis +of all speculations and beliefs in Biological science. We have gradually +traced down all organic forms, or, in other words, we have analysed the +present condition of animated nature, until we found that each species took +its origin in a form similar to that under which all the others commenced +their existence. We have found the whole of the vast array of living forms +with which we are surrounded, constantly growing, increasing, decaying and +disappearing; the animal constantly attracting, modifying, and applying to +its sustenance the matter of the vegetable kingdom, which derived its +support from the absorption and conversion of inorganic matter. And so +constant and universal is this absorption, waste, and reproduction, that it +may be said with perfect certainty that there is left in no one of our +bodies at the present moment a millionth part of the matter of which they +were originally formed! We have seen, again, that not only is the living +matter derived from the inorganic world, but that the forces of that matter +are all of them correlative with and convertible into those of inorganic +nature. + +This, for our present purposes, is the best view of the present condition +of organic nature which I can lay before you: it gives you the great +outlines of a vast picture, which you must fill up by your own study. + +In the next lecture I shall endeavour in the same way to go back into the +past, and to sketch in the same broad manner the history of life in epochs +preceding our own. + + + +II. THE PAST CONDITION OF ORGANIC NATURE + + +In the lecture which I delivered last Monday evening, I endeavoured to +sketch in a very brief manner, but as well as the time at my disposal would +permit, the present condition of organic nature, meaning by that large +title simply an indication of the great, broad, and general principles +which are to be discovered by those who look attentively at the phenomena +of organic nature as at present displayed. The general result of our +investigations might be summed up thus: we found that the multiplicity of +the forms of animal life, great as that may be, may be reduced to a +comparatively few primitive plans or types of construction; that a further +study of the development of those different forms revealed to us that they +were again reducible, until we at last brought the infinite diversity of +animal, and even vegetable life, down to the primordial form of a single +cell. + +We found that our analysis of the organic world, whether animals or plants, +showed, in the long run, that they might both be reduced into, and were, in +fact, composed of, the same constituents. And we saw that the plant +obtained the materials constituting its substance by a peculiar combination +of matters belonging entirely to the inorganic world; that, then, the +animal was constantly appropriating the nitrogenous matters of the plant to +its own nourishment, and returning them back to the inorganic world, in +what we spoke of as its waste; and that finally, when the animal ceased to +exist, the constituents of its body were dissolved and transmitted to that +inorganic world whence they had been at first abstracted. Thus we saw in +both the blade of grass and the horse but the same elements differently +combined and arranged. We discovered a continual circulation going on,--the +plant drawing in the elements of inorganic nature and combining them into +food for the animal creation; the animal borrowing from the plant the +matter for its own support, giving off during its life products which +returned immediately to the inorganic world; and that, eventually, the +constituent materials of the whole structure of both animals and plants +were thus returned to their original source: there was a constant passage +from one state of existence to another, and a returning back again. + +Lastly, when we endeavoured to form some notion of the nature of the forces +exercised by living beings, we discovered that they--if not capable of +being subjected to the same minute analysis as the constituents of those +beings themselves--that they were correlative with--that they were the +equivalents of the forces of inorganic nature--that they were, in the sense +in which the term is now used, convertible with them. That was our general +result. + +And now, leaving the Present, I must endeavour in the same manner to put +before you the facts that are to be discovered in the Past history of the +living world, in the past conditions of organic nature. We have, to-night, +to deal with the facts of that history--a history involving periods of time +before which our mere human records sink into utter insignificance--a +history the variety and physical magnitude of whose events cannot even be +foreshadowed by the history of human life and human phenomena--a history of +the most varied and complex character. + +We must deal with the history, then, in the first place, as we should deal +with all other histories. The historical student knows that his first +business should be to inquire into the validity of his evidence, and the +nature of the record in which the evidence is contained, that he may be +able to form a proper estimate of the correctness of the conclusions which +have been drawn from that evidence. So, here we must pass, in the first +place, to the consideration of a matter which may seem foreign to the +question under discussion. We must dwell upon the nature of the records, +and the credibility of the evidence they contain; we must look to the +completeness or incompleteness of those records themselves, before we turn +to that which they contain and reveal. The question of the credibility of +the history, happily for us, will not require much consideration, for, in +this history, unlike those of human origin, there can be no cavilling, no +differences as to the reality and truth of the facts of which it is made +up; the facts state themselves, and are laid out clearly before us. + +But, although one of the greatest difficulties of the historical student is +cleared out of our path, there are other difficulties--difficulties in +rightly interpreting the facts as they are presented to us--which may be +compared with the greatest difficulties of any other kinds of historical +study. + +What is this record of the past history of the globe, and what are the +questions which are involved in an inquiry into its completeness or +incompleteness? That record is composed of mud; and the question which we +have to investigate this evening resolves itself into a question of the +formation of mud. You may think, perhaps, that this is a vast step--of +almost from the sublime to the ridiculous--from the contemplation of the +history of the past ages of the world's existence to the consideration of +the history of the formation of mud! But, in Nature, there is nothing mean +and unworthy of attention; there is nothing ridiculous or contemptible in +any of her works; and this inquiry, you will soon see, I hope, takes us to +the very root and foundations of our subject. + +How, then, is mud formed? Always, with some trifling exceptions, which I +need not consider now--always, as the result of the action of water, +wearing down and disintegrating the surface of the earth and rocks with +which it comes in contact--pounding and grinding it down, and carrying the +particles away to places where they cease to be disturbed by this +mechanical action, and where they can subside and rest. For the ocean, +urged by winds, washes, as we know, a long extent of coast, and every wave, +loaded as it is with particles of sand and gravel as it breaks upon the +shore, does something towards the disintegrating process. And thus, slowly +but surely, the hardest rocks are gradually ground down to a powdery +substance; and the mud thus formed, coarser or finer, as the case may be, +is carried by the rush of the tides, or currents, till it reaches the +comparatively deeper parts of the ocean, in which it can sink to the +bottom, that is, to parts where there is a depth of about fourteen or +fifteen fathoms, a depth at which the water is, usually, nearly motionless, +and in which, of course, the finer particles of this detritus, or mud as we +call it, sinks to the bottom. + +Or, again, if you take a river, rushing down from its mountain sources, +brawling over the stones and rocks that intersect its path, loosening, +removing, and carrying with it in its downward course the pebbles and +lighter matters from its banks, it crushes and pounds down the rocks and +earths in precisely the same way as the wearing action of the sea waves. +The matters forming the deposit are torn from the mountain-side and whirled +impetuously into the valley, more slowly over the plain, thence into the +estuary, and from the estuary they are swept into the sea. The coarser and +heavier fragments are obviously deposited first, that is, as soon as the +current begins to lose its force by becoming amalgamated with the stiller +depths of the ocean, but the finer and lighter particles are carried +further on, and eventually deposited in a deeper and stiller portion of the +ocean. + +It clearly follows from this that mud gives us a chronology; for it is +evident that supposing this, which I now sketch, to be the sea bottom, and +supposing this to be a coast-line; from the washing action of the sea upon +the rock, wearing and grinding it down into a sediment of mud, the mud will +be carried down, and, at length, deposited in the deeper parts of this sea +bottom, where it will form a layer; and then, while that first layer is +hardening, other mud which is coming from the same source will, of course, +be carried to the same place; and, as it is quite impossible for it to get +beneath the layer already there, it deposits itself above it, and forms +another layer, and in that way you gradually have layers of mud constantly +forming and hardening one above the other, and conveying a record of time. + +It is a necessary result of the operation of the law of gravitation that +the uppermost layer shall be the youngest and the lowest the oldest, and +that the different beds shall be older at any particular point or spot in +exactly the ratio of their depth from the surface. So that if they were +upheaved afterwards, and you had a series of these different layers of mud, +converted into sandstone, or limestone, as the case might be, you might be +sure that the bottom layer was deposited first, and that the upper layers +were formed afterwards. Here, you see, is the first step in the +history--these layers of mud give us an idea of time. + +The whole surface of the earth,--I speak broadly, and leave out minor +qualifications,--is made up of such layers of mud, so hard, the majority of +them, that we call them rock whether limestone or sandstone, or other +varieties of rock. And, seeing that every part of the crust of the earth is +made up in this way, you might think that the determination of the +chronology, the fixing of the time which it has taken to form this crust is +a comparatively simple matter. Take a broad average, ascertain how fast the +mud is deposited upon the bottom of the sea, or in the estuary of rivers; +take it to be an inch, or two, or three inches a year, or whatever you may +roughly estimate it at; then take the total thickness of the whole series +of stratified rocks, which geologists estimate at twelve or thirteen miles, +or about seventy thousand feet, make a sum in short division, divide the +total thickness by that of the quantity deposited in one year, and the +result will, of course, give you the number of years which the crust has +taken to form. + +Truly, that looks a very simple process! It would be so except for certain +difficulties, the very first of which is that of finding how rapidly +sediments are deposited; but the main difficulty--a difficulty which +renders any certain calculations of such a matter out of the question--is +this, the sea-bottom on which the deposit takes place is continually +shifting. + +Instead of the surface of the earth being that stable, fixed thing that it +is popularly believed to be, being, in common parlance, the very emblem of +fixity itself, it is incessantly moving, and is, in fact, as unstable as +the surface of the sea, except that its undulations are infinitely slower +and enormously higher and deeper. + +Now, what is the effect of this oscillation? Take the case to which I have +previously referred. The finer or coarser sediments that are carried down +by the current of the river, will only be carried out a certain distance, +and eventually, as we have already seen, on reaching the stiller part of +the ocean, will be deposited at the bottom. + +[Illustration: Fig. 4.] + +Let C _y_ (Fig. 4) be the sea-bottom, _y_ D the shore, _x y_ +the sea-level, then the coarser deposit will subside over the region B, the +finer over A, while beyond A there will be no deposit at all; and, +consequently, no record will be kept, simply because no deposit is going +on. Now, suppose that the whole land, C, D, which we have regarded as +stationary, goes down, as it does so, both A and B go further out from the +shore, which will be at _y1_; _x1_, _y1_, being the new +sea-level. The consequence will be that the layer of mud (A), being now, +for the most part, further than the force of the current is strong enough +to convey even the finest _débris_, will, of course, receive no more +deposits, and having attained a certain thickness will now grow no thicker. + +We should be misled in taking the thickness of that layer, whenever it may +be exposed to our view, as a record of time in the manner in which we are +now regarding this subject, as it would give us only an imperfect and +partial record: it would seem to represent too short a period of time. + +Suppose, on the other hand, that the land (C D) had gone on rising slowly +and gradually--say an inch or two inches in the course of a century,--what +would be the practical effect of that movement? Why, that the sediment A +and B which has been already deposited, would eventually be brought nearer +to the shore-level and again subjected to the wear and tear of the sea; and +directly the sea begins to act upon it, it would of course soon cut up and +carry it way, to a greater or less extent, to be re-deposited further out. + +Well, as there is, in all probability, not one single spot on the whole +surface of the earth, which has not been up and down in this way a great +many times, it follows that the thickness of the deposits formed at any +particular spot cannot be taken (even supposing we had at first obtained +correct data as to the rate at which they took place), as affording +reliable information as to the period of time occupied in its deposit. So +that you see it is absolutely necessary from these facts, seeing that our +record entirely consists of accumulations of mud, superimposed one on the +other; seeing in the next place that any particular spots on which +accumulations have occurred, have been constantly moving up and down, and +sometimes out of the reach of a deposit, and at other times its own deposit +broken up and carried away, it follows that our record must be in the +highest degree imperfect, and we have hardly a trace left of thick +deposits, or any definite knowledge of the area that they occupied, in a +great many cases. And mark this! That supposing even that the whole surface +of the earth had been accessible to the geologist,--that man had had access +to every part of the earth, and had made sections of the whole, and put +them all together,--even then his record must of necessity be imperfect. + +But to how much has man really access? If you will look at this map you +will see that it represents the proportion of the sea to the earth: this +coloured part indicates all the dry land, and this other portion is the +water. You will notice at once that the water covers three-fifths of the +whole surface of the globe, and has covered it in the same manner ever +since man has kept any record of his own observations, to say nothing of +the minute period during which he has cultivated geological inquiry. So +that three-fifths of the surface of the earth is shut out from us because +it is under the sea. Let us look at the other two-fifths, and see what are +the countries in which anything that may be termed searching geological +inquiry has been carried out: a good deal of France, Germany, and Great +Britain and Ireland, bits of Spain, of Italy, and of Russia, have been +examined, but of the whole great mass of Africa, except parts of the +southern extremity, we know next to nothing; little bits of India, but of +the greater part of the Asiatic continent nothing; bits of the Northern +American States and of Canada, but of the greater part of the continent of +North America, and in still larger proportion, of South America, nothing! + +Under these circumstances, it follows that even with reference to that kind +of imperfect information which we can possess, it is only of about the +ten-thousandth part of the accessible parts of the earth that has been +examined properly. Therefore, it is with justice that the most thoughtful +of those who are concerned in these inquiries insist continually upon the +imperfection of the geological record; for, I repeat, it is absolutely +necessary, from the nature of things, that that record should be of the +most fragmentary and imperfect character. Unfortunately this circumstance +has been constantly forgotten. Men of science, like young colts in a fresh +pasture, are apt to be exhilarated on being turned into a new field of +inquiry, to go off at a hand-gallop, in total disregard of hedges and +ditches, to lose sight of the real limitation of their inquiries, and to +forget the extreme imperfection of what is really known. Geologists have +imagined that they could tell us what was going on at all parts of the +earth's surface during a given epoch; they have talked of this deposit +being contemporaneous with that deposit, until, from our little local +histories of the changes at limited spots of the earth's surface, they have +constructed a universal history of the globe as full of wonders and +portents as any other story of antiquity. + +But what does this attempt to construct a universal history of the globe +imply? It implies that we shall not only have a precise knowledge of the +events which have occurred at any particular point, but that we shall be +able to say what events, at any one spot, took place at the same time with +those at other spots. + +Let us see how far that is in the nature of things practicable. Suppose +that here I make a section of the Lake of Killarney, and here the section +of another lake--that of Loch Lomond in Scotland for instance. The rivers +that flow into them are constantly carrying down deposits of mud, and beds, +or strata, are being as constantly formed, one above the other, at the +bottom of those lakes. Now, there is not a shadow of doubt that in these +two lakes the lower beds are all older than the upper--there is no doubt +about that; but what does _this_ tell us about the age of any given +bed in Loch Lomond, as compared with that of any given bed in the Lake of +Killarney? It is, indeed, obvious that if any two sets of deposits are +separated and discontinuous, there is absolutely no means whatever given +you by the nature of the deposit of saying whether one is much younger or +older than the other; but you may say, as many have said and think, that +the case is very much altered if the beds which we are comparing are +continuous. Suppose two beds of mud hardened into rock,--A and B--are seen +in section. (Fig. 5.) + +[Illustration: Fig. 5.] + +Well, you say, it is admitted that the lowermost bed is always the older. +Very well; B, therefore, is older than A. No doubt, _as a whole_, it +is so; or if any parts of the two beds which are in the same vertical line +are compared, it is so. But suppose you take what seems a very natural step +further, and say that the part _a_ of the bed A is younger than the +part _b_ of the bed B. Is this sound reasoning? If you find any record +of changes taking place at _b_, did they occur before any events which +took place while _a_ was being deposited? It looks all very plain +sailing, indeed, to say that they did; and yet there is no proof of +anything of the kind. As the former Director of this Institution, Sir H. De +la Beche, long ago showed, this reasoning may involve an entire fallacy. It +is extremely possible that _a_ may have been deposited ages before +_b_. It is very easy to understand how that can be. To return to Fig. +4; when A and B were deposited, they were _substantially_ +contemporaneous; A being simply the finer deposit, and B the coarser of the +same detritus or waste of land. Now suppose that that sea-bottom goes down +(as shown in Fig. 4), so that the first deposit is carried no farther than +_a_, forming the bed A1, and the coarse no farther than _b_, +forming the bed B1, the result will be the formation of two continuous +beds, one of fine sediment (A A1) over-lapping another of coarse sediment +(B B1). Now suppose the whole sea-bottom is raised up, and a section +exposed about the point A1; no doubt, _at this spot_, the upper bed is +younger than the lower. But we should obviously greatly err if we concluded +that the mass of the upper bed at A was younger than the lower bed at B; +for we have just seen that they are contemporaneous deposits. Still more +should we be in error if we supposed the upper bed at A to be younger than +the continuation of the lower bed at B1; for A was deposited long before +B1. In fine, if, instead of comparing immediately adjacent parts of two +beds, one of which lies upon another, we compare distant parts, it is quite +possible that the upper may be any number of years older than the under, +and the under any number of years younger than the upper. + +Now you must not suppose that I put this before you for the purpose of +raising a paradoxical difficulty; the fact is, that the great mass of +deposits have taken place in sea-bottoms which are gradually sinking, and +have been formed under the very conditions I am here supposing. + +Do not run away with the notion that this subverts the principle I laid +down at first. The error lies in extending a principle which is perfectly +applicable to deposits in the same vertical line to deposits which are not +in that relation to one another. + +It is in consequence of circumstances of this kind, and of others that I +might mention to you, that our conclusions on and interpretations of the +record are really and strictly only valid so long as we confine ourselves +to one vertical section. I do not mean to tell you that there are no +qualifying circumstances, so that, even in very considerable areas, we may +safely speak of conformably superimposed beds being older or younger than +others at many different points. But we can never be quite sure in coming +to that conclusion, and especially we cannot be sure if there is any break +in their continuity, or any very great distance between the points to be +compared. + +Well now, so much for the record itself,--so much for its +imperfections,--so much for the conditions to be observed in interpreting +it, and its chronological indications, the moment we pass beyond the limits +of a vertical linear section. + +Now let us pass from the record to that which it contains,--from the book +itself to the writing and the figures on its pages. This writing and these +figures consist of remains of animals and plants which, in the great +majority of cases, have lived and died in the very spot in which we now +find them, or at least in the immediate vicinity. You must all of you be +aware--and I referred to the fact in my last lecture--that there are vast +numbers of creatures living at the bottom of the sea. These creatures, like +all others, sooner or later die, and their shells and hard parts lie at the +bottom; and then the fine mud which is being constantly brought down by +rivers and the action of the wear and tear of the sea, covers them over and +protects them from any further change or alteration; and, of course, as in +process of time the mud becomes hardened and solidified, the shells of +these animals are preserved and firmly imbedded in the limestone or +sandstone which is being thus formed. You may see in the galleries of the +Museum up stairs specimens of limestones in which such fossil remains of +existing animals are imbedded. There are some specimens in which turtles' +eggs have been imbedded in calcareous sand, and before the sun had hatched +the young turtles, they became covered over with calcareous mud, and thus +have been preserved and fossilised. + +Not only does this process of imbedding and fossilisation occur with marine +and other aquatic animals and plants, but it affects those land animals and +plants which are drifted away to sea, or become buried in bogs or morasses; +and the animals which have been trodden down by their fellows and crushed +in the mud at the river's bank, as the herd have come to drink. In any of +these cases, the organisms may be crushed or be mutilated, before or after +putrefaction, in such a manner that perhaps only a part will be left in the +form in which it reaches us. It is, indeed, a most remarkable fact, that it +is quite an exceptional case to find a skeleton of any one of all the +thousands of wild land animals that we know are constantly being killed, or +dying in the course of nature: they are preyed on and devoured by other +animals, or die in places where their bodies are not afterwards protected +by mud. There are other animals existing on the sea, the shells of which +form exceedingly large deposits. You are probably aware that before the +attempt was made to lay the Atlantic telegraphic cable, the Government +employed vessels in making a series of very careful observations and +soundings of the bottom of the Atlantic; and although, as we must all +regret, that up to the present time that project has not succeeded, we have +the satisfaction of knowing that it yielded some most remarkable results to +science. The Atlantic Ocean had to be sounded right across, to depths of +several miles in some places, and the nature of its bottom was carefully +ascertained. Well, now, a space of about 1,000 miles wide from east to +west, and I do not exactly know how many from north to south, but at any +rate 600 or 700 miles, was carefully examined, and it was found that over +the whole of that immense area an excessively fine chalky mud is being +deposited; and this deposit is entirely made up of animals whose hard parts +are deposited in this part of the ocean, and are doubtless gradually +acquiring solidity and becoming metamorphosed into a chalky limestone. +Thus, you see, it is quite possible in this way to preserve unmistakable +records of animal and vegetable life. Whenever the sea-bottom, by some of +those undulations of the earth's crust that I have referred to, becomes +up-heaved, and sections or borings are made, or pits are dug, then we +become able to examine the contents and constituents of these ancient +sea-bottoms, and find out what manner of animals lived at that period. + +Now it is a very important consideration in its bearing on the completeness +of the record, to inquire how far the remains contained in these +fossiliferous limestones are able to convey anything like an accurate or +complete account of the animals which were in existence at the time of its +formation. Upon that point we can form a very clear judgment, and one in +which there is no possible room for any mistake. There are of course a +great number of animals--such as jellyfishes, and other animals--without +any hard parts, of which we cannot reasonably expect to find any traces +whatever: there is nothing of them to preserve. Within a very short time, +you will have noticed, after they are removed from the water, they dry up +to a mere nothing; certainly they are not of a nature to leave any very +visible traces of their existence on such bodies as chalk or mud. Then +again, look at land animals; it is, as I have said, a very uncommon thing +to find a land animal entire after death. Insects and other carnivorous +animals very speedily pull them to pieces, putrefaction takes place, and +so, out of the hundreds of thousands that are known to die every year, it +is the rarest thing in the world to see one imbedded in such a way that its +remains would be preserved for a lengthened period. Not only is this the +case, but even when animal remains have been safely imbedded, certain +natural agents may wholly destroy and remove them. + +Almost all the hard parts of animals--the bones and so on--are composed +chiefly of phosphate of lime and carbonate of lime. Some years ago, I had +to make an inquiry into the nature of some very curious fossils sent to me +from the North of Scotland. Fossils are usually hard bony structures that +have become imbedded in the way I have described, and have gradually +acquired the nature and solidity of the body with which they are +associated; but in this case I had a series of _holes_ in some pieces +of rock, and nothing else. Those holes, however, had a certain definite +shape about them, and when I got a skilful workman to make castings of the +interior of these holes, I found that they were the impressions of the +joints of a backbone and of the armour of a great reptile, twelve or more +feet long. This great beast had died and got buried in the sand; the sand +had gradually hardened over the bones, but remained porous. Water had +trickled through it, and that water being probably charged with a +superfluity of carbonic acid, had dissolved all the phosphate and carbonate +of lime, and the bones themselves had thus decayed and entirely +disappeared; but as the sandstone happened to have consolidated by that +time, the precise shape of the bones was retained. If that sandstone had +remained soft a little longer, we should have known nothing whatsoever of +the existence of the reptile whose bones it had encased. + +How certain it is that a vast number of animals which have existed at one +period on this earth have entirely perished, and left no trace whatever of +their forms, may be proved to you by other considerations. There are large +tracts of sandstone in various parts of the world, in which nobody has yet +found anything but footsteps. Not a bone of any description, but an +enormous number of traces of footsteps. There is no question about them. +There is a whole valley in Connecticut covered with these footsteps, and +not a single fragment of the animals which made them have yet been found. +Let me mention another case while upon that matter, which is even more +surprising than those to which I have yet referred. There is a limestone +formation near Oxford, at a place called Stonesfield, which has yielded the +remains of certain very interesting mammalian animals, and up to this time, +if I recollect rightly, there have been found seven specimens of its lower +jaws, and not a bit of anything else, neither limb-bones nor skull, nor any +part whatever; not a fragment of the whole system! Of course, it would be +preposterous to imagine that the beasts had nothing else but a lower jaw! +The probability is, as Dr. Buckland showed, as the result of his +observations on dead dogs in the river Thames, that the lower jaw, not +being secured by very firm ligaments to the bones of the head, and being a +weighty affair, would easily be knocked off, or might drop away from the +body as it floated in water in a state of decomposition. The jaw would thus +be deposited immediately, while the rest of the body would float and drift +away altogether, ultimately reaching the sea, and perhaps becoming +destroyed. The jaw becomes covered up and preserved in the river silt, and +thus it comes that we have such a curious circumstance as that of the lower +jaws in the Stonesfield slates. So that, you see, faulty as these layers of +stone in the earth's crust are, defective as they necessarily are as a +record, the account of contemporaneous vital phenomena presented by them +is, by the necessity of the case, infinitely more defective and +fragmentary. + +It was necessary that I should put all this very strongly before you, +because, otherwise, you might have been led to think differently of the +completeness of our knowledge by the next facts I shall state to you. + +The researches of the last three-quarters of a century have, in truth, +revealed a wonderful richness of organic life in those rocks. Certainly not +fewer than thirty or forty thousand different species of fossils have been +discovered. You have no more ground for doubting that these creatures +really lived and died at or near the places in which we find them than you +have for like scepticism about a shell on the sea-shore. The evidence is as +good in the one case as in the other. + +Our next business is to look at the general character of these fossil +remains, and it is a subject which will be requisite to consider carefully; +and the first point for us is to examine how much the extinct _Flora_ +and _Fauna_ as a _whole_--disregarding altogether the +_succession_ of their constituents, of which I shall speak +afterwards--differ from the _Flora_ and _Fauna_ of the present +day;--how far they differ in what we _do_ know about them, leaving +altogether out of consideration speculations based upon what we _do +not_ know. + +I strongly imagine that if it were not for the peculiar appearance that +fossilised animals have, any of you might readily walk through a museum +which contains fossil remains mixed up with those of the present forms of +life, and I doubt very much whether your uninstructed eyes would lead you +to see any vast or wonderful difference between the two. If you looked +closely, you would notice, in the first place, a great many things very +like animals with which you are acquainted now: you would see differences +of shape and proportion, but on the whole a close similarity. + +I explained what I meant by ORDERS the other day, when I described the +animal kingdom as being divided into sub-kingdoms, classes and orders. If +you divide the animal kingdom into orders you will find that there are +above one hundred and twenty. The number may vary on one side or the other, +but this is a fair estimate. That is the sum total of the orders of all the +animals which we know now, and which have been known in past times, and +left remains behind. + +Now, how many of those are absolutely extinct? That is to say, how many of +these orders of animals have lived at a former period of the world's +history but have at present no representatives? That is the sense in which +I meant to use the word "extinct." I mean that those animals did live on +this earth at one time, but have left no one of their kind with us at the +present moment. So that estimating the number of extinct animals is a sort +of way of comparing the past creation as a whole with the present as a +whole. Among the mammalia and birds there are none extinct; but when we +come to the reptiles there is a most wonderful thing: out of the eight +orders, or thereabouts, which you can make among reptiles, one-half are +extinct. These diagrams of the plesiosaurus, the ichthyosaurus, the +pterodactyle, give you a notion of some of these extinct reptiles. And here +is a cast of the pterodactyle and bones of the ichthyosaurus and the +plesiosaurus, just as fresh-looking as if it had been recently dug up in a +churchyard. Thus, in the reptile class, there are no less than half of the +orders which are absolutely extinct. If we turn to the _Amphibia_, +there was one extinct order, the Labyrinthodonts, typified by the large +salamander-like beast shown in this diagram. + +No order of fishes is known to be extinct. Every fish that we find in the +strata--to which I have been referring--can be identified and placed in one +of the orders which exist at the present day. There is not known to be a +single ordinal form of insect extinct. There are only two orders extinct +among the _Crustacea_. There is not known to be an extinct order of +these creatures, the parasitic and other worms; but there are two, not to +say three, absolutely extinct orders of this class, the +_Echinodermata_; out of all the orders of the _Coelenterata_ and +_Protozoa_ only one, the Rugose Corals. + +So that, you see, out of somewhere about 120 orders of animals, taking them +altogether, you will not, at the outside estimate, find above ten or a +dozen extinct. Summing up all the order of animals which have left remains +behind them, you will not find above ten or a dozen which cannot be +arranged with those of the present day; that is to say, that the difference +does not amount to much more than ten per cent.: and the proportion of +extinct orders of plants is still smaller. I think that that is a very +astounding a most astonishing fact: seeing the enormous epochs of time +which have elapsed during the constitution of the surface of the earth as +it at present exists, it is, indeed, a most astounding thing that the +proportion of extinct ordinal types should be so exceedingly small. + +But now, there is another point of view in which we must look at this past +creation. Suppose that we were to sink a vertical pit through the floor +beneath us, and that I could succeed in making a section right through in +the direction of New Zealand, I should find in each of the different beds +through which I passed the remains of animals which I should find in that +stratum and not in the others. First, I should come upon beds of gravel or +drift containing the bones of large animals, such as the elephant, +rhinoceros, and cave tiger. Rather curious things to fall across in +Piccadilly! If I should dig lower still, I should come upon a bed of what +we call the London clay, and in this, as you will see in our galleries up +stairs, are found remains of strange cattle, remains of turtles, palms, and +large tropical fruits; with shell-fish such as you see the like of now only +in tropical regions. If I went below that, I should come upon the chalk, +and there I should find something altogether different, the remains of +ichthyosauria and pterodactyles, and ammonites, and so forth. + +I do not know what Mr. Godwin Austin would say comes next, but probably +rocks containing more ammonites, and more ichthyosauria and plesiosauria, +with a vast number of other things; and under that I should meet with yet +older rocks containing numbers of strange shells and fishes; and in thus +passing from the surface to the lowest depths of the earth's crust, the +forms of animal life and vegetable life which I should meet with in the +successive beds would, looking at them broadly, be the more different the +further that I went down. Or, in other words, inasmuch as we started with +the clear principle, that in a series of naturally-disposed mud beds the +lowest are the oldest, we should come to this result, that the further we +go back in time the more difference exists between the animal and vegetable +life of an epoch and that which now exists. That was the conclusion to +which I wished to bring you at the end of this lecture. + + + +III. THE METHOD BY WHICH THE CAUSES OF THE PRESENT AND PAST CONDITIONS OF +ORGANIC NATURE ARE TO BE DISCOVERED;--THE ORIGINATION OF LIVING BEINGS + + +In the two preceding lectures I have endeavoured to indicate to you the +extent of the subject-matter of the inquiry upon which we are engaged; and +having thus acquired some conception of the past and present phenomena of +organic nature, I must now turn to that which constitutes the great problem +which we have set before ourselves;--I mean, the question of what knowledge +we have of the causes of these phenomena of organic nature, and how such +knowledge is obtainable. + +Here, on the threshold of the inquiry, an objection meets us. There are in +the world a number of extremely worthy, well-meaning persons, whose +judgments and opinions are entitled to the utmost respect on account of +their sincerity, who are of opinion that vital phenomena, and especially +all questions relating to the origin of vital phenomena, are questions +quite apart from the ordinary run of inquiry, and are, by their very +nature, placed out of our reach. They say that all these phenomena +originated miraculously, or in some way totally different from the ordinary +course of nature, and that therefore they conceive it to be futile, not to +say presumptuous, to attempt to inquire into them. + +To such sincere and earnest persons, I would only say, that a question of +this kind is not to be shelved upon theoretical or speculative grounds. You +may remember the story of the Sophist who demonstrated to Diogenes in the +most complete and satisfactory manner that he could not walk; that, in +fact, all motion was an impossibility; and that Diogenes refuted him by +simply getting up and walking round his tub. So, in the same way, the man +of science replies to objections of this kind, by simply getting up and +walking onward, and showing what science has done and is doing---by +pointing to that immense mass of facts which have been ascertained as +systematised under the forms of the great doctrines of morphology, of +development, of distribution, and the like. He sees an enormous mass of +facts and laws relating to organic beings, which stand on the same good +sound foundation as every other natural law. With this mass of facts and +laws before us, therefore, seeing that, as far as organic matters have +hitherto been accessible and studied, they have shown themselves capable of +yielding to scientific investigation, we may accept this as proof that +order and law reign there as well as in the rest of Nature. The man of +science says nothing to objectors of this sort, but supposes that we can +and shall walk to a knowledge of the origin of organic nature, in the same +way that we have walked to a knowledge of the laws and principles of the +inorganic world. + +But there are objectors who say the same from ignorance and ill-will. To +such I would reply that the objection comes ill from them, and that the +real presumption, I may almost say the real blasphemy, in this matter, is +in the attempt to limit that inquiry into the causes of phenomena, which is +the source of all human blessings, and from which has sprung all human +prosperity and progress; for, after all, we can accomplish comparatively +little; the limited range of our own faculties bounds us on every +side,--the field of our powers of observation is small enough, and he who +endeavours to narrow the sphere of our inquiries is only pursuing a course +that is likely to produce the greatest harm to his fellow-men. + +But now, assuming, as we all do, I hope, that these phenomena are properly +accessible to inquiry, and setting out upon our search into the causes of +the phenomena of organic nature, or at any rate, setting out to discover +how much we at present know upon these abstruse matters, the question +arises as to what is to be our course of proceeding, and what method we +must lay down for our guidance. I reply to that question, that our method +must be exactly the same as that which is pursued in any other scientific +inquiry, the method of scientific investigation being the same for all +orders of facts and phenomena whatsoever. + +I must dwell a little on this point, for I wish you to leave this room with +a very clear conviction that scientific investigation is not, as many +people seem to suppose, some kind of modern black art. I say that you might +easily gather this impression from the manner in which many persons speak +of scientific inquiry, or talk about inductive and deductive philosophy, or +the principles of the "Baconian philosophy." I do protest that, of the vast +number of cants in this world, there are none, to my mind, so contemptible +as the pseudo-scientific cant which is talked about the "Baconian +philosophy." + +To hear people talk about the great Chancellor--and a very great man he +certainly was,--you would think that it was he who had invented science, +and that there was no such thing as sound reasoning before the time of +Queen Elizabeth! Of course you say, that cannot possibly be true; you +perceive, on a moment's reflection, that such an idea is absurdly wrong, +and yet, so firmly rooted is this sort of impression,--I cannot call it an +idea, or conception,--the thing is too absurd to be entertained,--but so +completely does it exist at the bottom of most men's minds, that this has +been a matter of observation with me for many years past. There are many +men who, though knowing absolutely nothing of the subject with which they +may be dealing, wish, nevertheless, to damage the author of some view with +which they think fit to disagree. What they do, then, is not to go and +learn something about the subject, which one would naturally think the best +way of fairly dealing with it; but they abuse the originator of the view +they question, in a general manner, and wind up by saying that, "After all, +you know, the principles and method of this author are totally opposed to +the canons of the Baconian philosophy." Then everybody applauds, as a +matter of course, and agrees that it must be so. But if you were to stop +them all in the middle of their applause, you would probably find that +neither the speaker nor his applauders could tell you how or in what way it +was so; neither the one nor the other having the slightest idea of what +they mean when they speak of the "Baconian philosophy." + +You will understand, I hope, that I have not the slightest desire to join +in the outcry against either the morals, the intellect, or the great genius +of Lord Chancellor Bacon. He was undoubtedly a very great man, let people +say what they will of him; but notwithstanding all that he did for +philosophy, it would be entirely wrong to suppose that the methods of +modern scientific inquiry originated with him, or with his age; they +originated with the first man, whoever he was; and indeed existed long +before him, for many of the essential processes of reasoning are exerted by +the higher order of brutes as completely and effectively as by ourselves. +We see in many of the brute creation the exercise of one, at least, of the +same powers of reasoning as that which we ourselves employ. + +The method of scientific investigation is nothing but the expression of the +necessary mode of working of the human mind. It is simply the mode at which +all phenomena are reasoned about, rendered precise and exact. There is no +more difference, but there is just the same kind of difference, between the +mental operations of a man of science and those of an ordinary person, as +there is between the operations and methods of a baker or of a butcher +weighing out his goods in common scales, and the operations of a chemist in +performing a difficult and complex analysis by means of his balance and +finely-graduated weights. It is not that the action of the scales in the +one case, and the balance in the other, differ in the principles of their +construction or manner of working; but the beam of one is set on an +infinitely finer axis than the other, and of course turns by the addition +of a much smaller weight. + +You will understand this better, perhaps, if I give you some familiar +example. You have all heard it repeated, I dare say, that men of science +work by means of induction and deduction, and that by the help of these +operations, they, in a sort of sense, wring from Nature certain other +things, which are called natural laws, and causes, and that out of these, +by some cunning skill of their own, they build up hypotheses and theories. +And it is imagined by many, that the operations of the common mind can be +by no means compared with these processes, and that they have to be +acquired by a sort of special apprenticeship to the craft. To hear all +these large words, you would think that the mind of a man of science must +be constituted differently from that of his fellow men; but if you will not +be frightened by terms, you will discover that you are quite wrong, and +that all these terrible apparatus are being used by yourselves every day +and every hour of your lives. + +There is a well-known incident in one of Molière's plays, where the author +makes the hero express unbounded delight on being told that he had been +talking prose during the whole of his life. In the same way, I trust, that +you will take comfort, and be delighted with yourselves, on the discovery +that you have been acting on the principles of inductive and deductive +philosophy during the same period. Probably there is not one here who has +not in the course of the day had occasion to set in motion a complex train +of reasoning, of the very same kind, though differing of course in degree, +as that which a scientific man goes through in tracing the causes of +natural phenomena. + +A very trivial circumstance will serve to exemplify this. Suppose you go +into a fruiterer's shop, wanting an apple,--you take up one, and, on biting +it, you find it is sour; you look at it, and see that it is hard and green. +You take up another one, and that too is hard, green, and sour. The shopman +offers you a third; but, before biting it, you examine it, and find that it +is hard and green, and you immediately say that you will not have it, as it +must be sour, like those that you have already tried. + +Nothing can be more simple than that, you think; but if you will take the +trouble to analyse and trace out into its logical elements what has been +done by the mind, you will be greatly surprised. In the first place, you +have performed the operation of induction. You found that, in two +experiences, hardness and greenness in apples went together with sourness. +It was so in the first case, and it was confirmed by the second. True, it +is a very small basis, but still it is enough to make an induction from; +you generalise the facts, and you expect to find sourness in apples where +you get hardness and greenness. You found upon that a general law, that all +hard and green apples are sour; and that, so far as it goes, is a perfect +induction. Well, having got your natural law in this way, when you are +offered another apple which you find is hard and green, you say, "All hard +and green apples are sour; this apple is hard and green, therefore this +apple is sour." That train of reasoning is what logicians call a syllogism, +and has all its various parts and terms,--its major premiss, its minor +premiss, and its conclusion. And, by the help of further reasoning, which, +if drawn out, would have to be exhibited in two or three other syllogisms, +you arrive at your final determination, "I will not have that apple." So +that, you see, you have, in the first place, established a law by +induction, and upon that you have founded a deduction, and reasoned out the +special conclusion of the particular case. Well now, suppose, having got +your law, that at some time afterwards, you are discussing the qualities of +apples with a friend: you will say to him, "It is a very curious +thing,--but I find that all hard and green apples are sour!" Your friend +says to you, "But how do you know that?" You at once reply, "Oh, because I +have tried them over and over again, and have always found them to be so." +Well, if we were talking science instead of common sense, we should call +that an experimental verification. And, if still opposed, you go further, +and say, "I have heard from the people in Somersetshire and Devonshire, +where a large number of apples are grown, that they have observed the same +thing. It is also found to be the case in Normandy, and in North America. +In short, I find it to be the universal experience of mankind wherever +attention has been directed to the subject." Whereupon, your friend, unless +he is a very unreasonable man, agrees with you, and is convinced that you +are quite right in the conclusion you have drawn. He believes, although +perhaps he does not know he believes it, that the more extensive +verifications are,--that the more frequently experiments have been made, +and results of the same kind arrived at,--that the more varied the +conditions under which the same results are attained, the more certain is +the ultimate conclusion, and he disputes the question no further. He sees +that the experiment has been tried under all sorts of conditions, as to +time, place, and people, with the same result; and he says with you, +therefore, that the law you have laid down must be a good one, and he must +believe it. + +In science we do the same thing;--the philosopher exercises precisely the +same faculties, though in a much more delicate manner. In scientific +inquiry it becomes a matter of duty to expose a supposed law to every +possible kind of verification, and to take care, moreover, that this is +done intentionally, and not left to a mere accident, as in the case of the +apples. And in science, as in common life, our confidence in a law is in +exact proportion to the absence, of variation in the result of our +experimental verifications. For instance, if you let go your grasp of an +article you may have in your hand, it will immediately fall to the ground. +That is a very common verification of one of the best established laws of +nature--that of gravitation. The method by which men of science establish +the existence of that law is exactly the same as that by which we have +established the trivial proposition about the sourness of hard and green +apples. But we believe it in such an extensive, thorough, and unhesitating +manner because the universal experience of mankind verifies it, and we can +verify it ourselves at any time; and that is the strongest possible +foundation on which any natural law can rest. + +So much, then, by way of proof that the method of establishing laws in +science is exactly the same as that pursued in common life. Let us now turn +to another matter (though really it is but another phase of the same +question), and that is, the method by which, from the relations of certain +phenomena, we prove that some stand in the position of causes towards the +others. + +I want to put the case clearly before you, and I will therefore show you +what I mean by another familiar example. I will suppose that one of you, on +coming down in the morning to the parlour of your house, finds that a +tea-pot and some spoons which had been left in the room on the previous +evening are gone,--the window is open, and you observe the mark of a dirty +hand on the window-frame, and perhaps, in addition to that, you notice the +impress of a hob-nailed shoe on the gravel outside. All these phenomena +have struck your attention instantly, and before two seconds have passed +you say, "Oh, somebody has broken open the window, entered the room, and +run off with the spoons and the tea-pot!" That speech is out of your mouth +in a moment. And you will probably add, "I know there has; I am quite sure +of it!" You mean to say exactly what you know; but in reality you are +giving expression to what is, in all essential particulars, an hypothesis. +You do not _know_ it at all; it is nothing but an hypothesis rapidly +framed in your own mind. And it is an hypothesis founded on a long train of +inductions and deductions. + +What are those inductions and deductions, and how have you got at this +hypothesis? You have observed, in the first place, that the window is open; +but by a train of reasoning involving many inductions and deductions, you +have probably arrived long before at the general law--and a very good one +it is--that windows do not open of themselves; and you therefore conclude +that something has opened the window. A second general law that you have +arrived at in the same way is, that tea-pots and spoons do not go out of a +window spontaneously, and you are satisfied that, as they are not now where +you left them, they have been removed. In the third place, you look at the +marks on the window-sill, and the shoe-marks outside, and you say that in +all previous experience the former kind of mark has never been produced by +anything else but the hand of a human being; and the same experience shows +that no other animal but man at present wears shoes with hob-nails in them +such as would produce the marks in the gravel. I do not know, even if we +could discover any of those "missing links" that are talked about, that +they would help us to any other conclusion! At any rate the law which +states our present experience is strong enough for my present purpose. You +next reach the conclusion, that as these kinds of marks have not been left +by any other animals than men, or are liable to be formed in any other way +than by a man's hand and shoe, the marks in question have been formed by a +man in that way. You have, further, a general law, founded on observation +and experience, and that, too, is, I am sorry to say, a very universal and +unimpeachable one,--that some men are thieves; and you assume at once from +all these premisses--and that is what constitutes your hypothesis--that the +man who made the marks outside and on the window-sill, opened the window, +got into the room, and stole your tea-pot and spoons. You have now arrived +at a _vera causa_;--you have assumed a cause which, it is plain, is +competent to produce all the phenomena you have observed. You can explain +all these phenomena only by the hypothesis of a thief. But that is a +hypothetical conclusion, of the justice of which you have no absolute proof +at all; it is only rendered highly probable by a series of inductive and +deductive reasonings. + +I suppose your first action, assuming that you are a man of ordinary common +sense, and that you have established this hypothesis to your own +satisfaction, will very likely be to go off for the police, and set them on +the track of the burglar, with the view to the recovery of your property. +But just as you are starting with this object, some person comes in, and on +learning what you are about, says, "My good friend, you are going on a +great deal too fast. How do you know that the man who really made the marks +took the spoons? It might have been a monkey that took them, and the man +may have merely looked in afterwards." You would probably reply, "Well, +that is all very well, but you see it is contrary to all experience of the +way tea-pots and spoons are abstracted; so that, at any rate, your +hypothesis is less probable than mine." While you are talking the thing +over in this way, another friend arrives, one of that good kind of people +that I was talking of a little while ago. And he might say, "Oh, my dear +sir, you are certainly going on a great deal too fast. You are most +presumptuous. You admit that all these occurrences took place when you were +fast asleep, at a time when you could not possibly have known anything +about what was taking place. How do you know that the laws of Nature are +not suspended during the night? It may be that there has been some kind of +supernatural interference in this case." In point of fact, he declares that +your hypothesis is one of which you cannot at all demonstrate the truth, +and that you are by no means sure that the laws of Nature are the same when +you are asleep as when you are awake. + +Well, now, you cannot at the moment answer that kind of reasoning. You feel +that your worthy friend has you somewhat at a disadvantage. You will feel +perfectly convinced in your own mind, however, that you are quite right, +and you say to him, "My good friend, I can only be guided by the natural +probabilities of the case, and if you will be kind enough to stand aside +and permit me to pass, I will go and fetch the police." Well, we will +suppose that your journey is successful, and that by good luck you meet +with a policeman; that eventually the burglar is found with your property +on his person, and the marks correspond to his hand and to his boots. +Probably any jury would consider those facts a very good experimental +verification of your hypothesis, touching the cause of the abnormal +phenomena observed in your parlour, and would act accordingly. + +Now, in this suppositious case, I have taken phenomena of a very common +kind, in order that you might see what are the different steps in an +ordinary process of reasoning, if you will only take the trouble to analyse +it carefully. All the operations I have described, you will see, are +involved in the mind of any man of sense in leading him to a conclusion as +to the course he should take in order to make good a robbery and punish the +offender. I say that you are led, in that case, to your conclusion by +exactly the same train of reasoning as that which a man of science pursues +when he is endeavouring to discover the origin and laws of the most occult +phenomena. The process is, and always must be, the same; and precisely the +same mode of reasoning was employed by Newton and Laplace in their +endeavours to discover and define the causes of the movements of the +heavenly bodies, as you, with your own common sense, would employ to detect +a burglar. The only difference is, that the nature of the inquiry being +more abstruse, every step has to be most carefully watched, so that there +may not be a single crack or flaw in your hypothesis. A flaw or crack in +many of the hypotheses of daily life may be of little or no moment as +affecting the general correctness of the conclusions at which we may +arrive; but, in a scientific inquiry, a fallacy, great or small, is always +of importance, and is sure to be in the long run constantly productive of +mischievous, if not fatal results. + +Do not allow yourselves to be misled by the common notion that an +hypothesis is untrustworthy simply because it is an hypothesis. It is often +urged, in respect to some scientific conclusion, that, after all, it is +only an hypothesis. But what more have we to guide us in nine-tenths of the +most important affairs of daily life than hypotheses, and often very +ill-based ones? So that in science, where the evidence of an hypothesis is +subjected to the most rigid examination, we may rightly pursue the same +course. You may have hypotheses and hypotheses. A man may say, if he likes, +that the moon is made of green cheese: that is an hypothesis. But another +man, who has devoted a great deal of time and attention to the subject, and +availed himself of the most powerful telescopes and the results of the +observations of others, declares that in his opinion it is probably +composed of materials very similar to those of which our own earth is made +up: and that is also only an hypothesis. But I need not tell you that there +is an enormous difference in the value of the two hypotheses. That one +which is based on sound scientific knowledge is sure to have a +corresponding value; and that which is a mere hasty random guess is likely +to have but little value. Every great step in our progress in discovering +causes has been made in exactly the same way as that which I have detailed +to you. A person observing the occurrence of certain facts and phenomena +asks, naturally enough, what process, what kind of operation known to occur +in Nature applied to the particular case, will unravel and explain the +mystery? Hence you have the scientific hypothesis; and its value will be +proportionate to the care and completeness with which its basis had been +tested and verified. It is in these matters as in the commonest affairs of +practical life: the guess of the fool will be folly, while the guess of the +wise man will contain wisdom. In all cases, you see that the value of the +result depends on the patience and faithfulness with which the investigator +applies to his hypothesis every possible kind of verification. + +I dare say I may have to return to this point by and by; but having dealt +thus far with our logical methods, I must now turn to something which, +perhaps, you may consider more interesting, or, at any rate, more tangible. +But in reality there are but few things that can be more important for you +to understand than the mental processes and the means by which we obtain +scientific conclusions and theories. [Footnote: Those who wish to study +fully the doctrines of which I have endeavoured to give some +rough-and-ready illustrations, must read Mr. John Stuart Mill's _System +of Logic_.] Having granted that the inquiry is a proper one, and having +determined on the nature of the methods we are to pursue and which only can +lead to success, I must now turn to the consideration of our knowledge of +the nature of the processes which have resulted in the present condition of +organic nature. + +Here, let me say at once, lest some of you misunderstand me, that I have +extremely little to report. The question of how the present condition of +organic nature came about, resolves itself into two questions. The first +is: How has organic or living matter commenced its existence? And the +second is: How has it been perpetuated? On the second question I shall have +more to say hereafter. But on the first one, what I now have to say will be +for the most part of a negative character. + +If you consider what kind of evidence we can have upon this matter, it will +resolve itself into two kinds. We may have historical evidence and we may +have experimental evidence. It is, for example, conceivable, that inasmuch +as the hardened mud which forms a considerable portion of the thickness of +the earth's crust contains faithful records of the past forms of life, and +inasmuch as these differ more and more as we go further down,--it is +possible and conceivable that we might come to some particular bed or +stratum which should contain the remains of those creatures with which +organic life began upon the earth. And if we did so, and if such forms of +organic life were preservable, we should have what I would call historical +evidence of the mode in which organic life began upon this planet. Many +persons will tell you, and indeed you will find it stated in many works on +geology, that this has been done, and that we really possess such a record; +there are some who imagine that the earliest forms of life of which we have +as yet discovered any record, are in truth the forms in which animal life +began upon the globe. The grounds on which they base that supposition are +these:--That if you go through the enormous thickness of the earth's crust +and get down to the older rocks, the higher vertebrate animals--the +quadrupeds, birds, and fishes--cease to be found; beneath them you find +only the invertebrate animals; and in the deepest and lowest rocks those +remains become scantier and scantier, not in any very gradual progression, +however, until, at length, in what are supposed to be the oldest rocks, the +animal remains which are found are almost always confined to four +forms--_Oldhamia_, whose precise nature is not known, whether plant or +animal; _Lingula_, a kind of mollusc; _Trilobites_, a crustacean +animal, having the same essential plan of construction, though differing in +many details from a lobster or crab; and _Hymenocaris_, which is also +a crustacean. So that you have all the _Fauna_ reduced, at this +period, to four forms: one a kind of animal or plant that we know nothing +about, and three undoubted animals--two crustaceans and one mollusc. + +I think, considering the organisation of these mollusca and crustacea, and +looking at their very complex nature, that it does indeed require a very +strong imagination to conceive that these were the first created of all +living things. And you must take into consideration the fact that we have +not the slightest proof that these which we call the oldest beds are really +so: I repeat, we have not the slightest proof of it. When you find in some +places that in an enormous thickness of rocks there are but very scanty +traces of life, or absolutely none at all; and that in other parts of the +world rocks of the very same formation are crowded with the records of +living forms, I think it is impossible to place any reliance on the +supposition, or to feel one's self justified in supposing that these are +the forms in which life first commenced. I have not time here to enter upon +the technical grounds upon which I am led to this conclusion,--that could +hardly be done properly in half a dozen lectures on that part alone:--I +must content myself with saying that I do not at all believe that these are +the oldest forms of life. + +I turn to the experimental side to see what evidence we have there. To +enable us to say that we know anything about the experimental origination +of organisation and life, the investigator ought to be able to take +inorganic matters, such as carbonic acid, ammonia, water, and salines, in +any sort of inorganic combination, and be able to build them up into +protein matter, and then that protein matter ought to begin to live in an +organic form. That, nobody has done as yet, and I suspect it will be a long +while before anybody does do it. But the thing is by no means so impossible +as it looks; for the researches of modern chemistry have shown us--I won't +say the road towards it, but, if I may so say, they have shown the +finger-post pointing to the road that may lead to it. + +It is not many years ago--and you must recollect that Organic Chemistry is +a young science, not above a couple of generations old, you must not expect +too much of it,--it is not many years ago since it was said to be perfectly +impossible to fabricate any organic compound; that is to say, any +non-mineral compound which is to be found in an organised being. It +remained so for a very long period; but it is now a considerable number of +years since a distinguished foreign chemist contrived to fabricate urea, a +substance of a very complex character, which forms one of the waste +products of animal structures. And of late years a number of other +compounds, such as butyric acid, and others, have been added to the list. I +need not tell you that chemistry is an enormous distance from the goal I +indicate; all I wish to point out to you is, that it is by no means safe to +say that that goal may not be reached one day. It may be that it is +impossible for us to produce the conditions requisite to the origination of +life; but we must speak modestly about the matter, and recollect that +Science has put her foot upon the bottom round of the ladder. Truly he +would be a bold man who would venture to predict where she will be fifty +years hence. + +There is another inquiry which bears indirectly upon this question, and +upon which I must say a few words. You are all of you aware of the +phenomena of what is called spontaneous generation. Our forefathers, down +to the seventeenth century, or thereabouts, all imagined, in perfectly good +faith, that certain vegetable and animal forms gave birth, in the process +of their decomposition, to insect life. Thus, if you put a piece of meat in +the sun, and allowed it to putrefy, they conceived that the grubs which +soon began to appear were the result of the action of a power of +spontaneous generation which the meat contained. And they could give you +receipts for making various animal and vegetable preparations which would +produce particular kinds of animals. A very distinguished Italian +naturalist, named Redi, took up the question, at a time when everybody +believed in it; among others our own great Harvey, the discoverer of the +circulation of the blood. You will constantly find his name quoted, +however, as an opponent of the doctrine of spontaneous generation; but the +fact is, and you will see it if you will take the trouble to look into his +works, Harvey believed it as profoundly as any man of his time; but he +happened to enunciate a very curious proposition--that every living thing +came from an _egg_; he did not mean to use the word in the sense in +which we now employ it, he only meant to say that every living thing +originated in a little rounded particle of organised substance; and it is +from this circumstance, probably, that the notion of Harvey having opposed +the doctrine originated. Then came Redi, and he proceeded to upset the +doctrine in a very simple manner. He merely covered the piece of meat with +some very fine gauze, and then he exposed it to the same conditions. The +result of this was that no grubs or insects were produced; he proved that +the grubs originated from the insects who came and deposited their eggs in +the meat, and that they were hatched by the heat of the sun. By this kind +of inquiry he thoroughly upset the doctrine of spontaneous generation, for +his time at least. + +Then came the discovery and application of the microscope to scientific +inquiries, which showed to naturalists that besides the organisms which +they already knew as living beings and plants, there were an immense number +of minute things which could be obtained apparently almost at will from +decaying vegetable and animal forms. Thus, if you took some ordinary black +pepper or some hay, and steeped it in water, you would find in the course +of a few days that the water had become impregnated with an immense number +of animalcules swimming about in all directions. From facts of this kind +naturalists were led to revive the theory of spontaneous generation. They +were headed here by an English naturalist,--Needham,--and afterwards in +France by the learned Buffon. They said that these things were absolutely +begotten in the water of the decaying substances out of which the infusion +was made. It did not matter whether you took animal or vegetable matter, +you had only to steep it in water and expose it, and you would soon have +plenty of animalcules. They made an hypothesis about this which was a very +fair one. They said, this matter of the animal world, or of the higher +plants, appears to be dead, but in reality it has a sort of dim life about +it, which, if it is placed under fair conditions, will cause it to break up +into the forms of these little animalcules, and they will go through their +lives in the same way as the animal or plant of which they once formed a +part. + +The question now became very hotly debated. Spallanzani, an Italian +naturalist, took up opposite views to those of Needham and Buffon, and by +means of certain experiments he showed that it was quite possible to stop +the process by boiling the water, and closing the vessel in which it was +contained. "Oh!" said his opponents; "but what do you know you may be doing +when you heat the air over the water in this way? You may be destroying +some property of the air requisite for the spontaneous generation of the +animalcules." + +However, Spallanzani's views were supposed to be upon the right side, and +those of the others fell into discredit; although the fact was that +Spallanzani had not made good his views. Well, then, the subject continued +to be revived from time to time, and experiments were made by several +persons; but these experiments were not altogether satisfactory. It was +found that if you put an infusion in which animalcules would appear if it +were exposed to the air into a vessel and boiled it, and then sealed up the +mouth of the vessel, so that no air, save such as had been heated to 212°, +could reach its contents, that then no animalcules would be found; but if +you took the same vessel and exposed the infusion to the air, then you +would get animalcules. Furthermore, it was found that if you connected the +mouth of the vessel with a red-hot tube in such a way that the air would +have to pass through the tube before reaching the infusion, that then you +would get no animalcules. Yet another thing was noticed: if you took two +flasks containing the same kind of infusion, and left one entirely exposed +to the air, and in the mouth of the other placed a ball of cotton wool, so +that the air would have to filter itself through it before reaching the +infusion, that then, although you might have plenty of animalcules in the +first flask, you would certainly obtain none from the second. + +These experiments, you see, all tended towards one conclusion--that the +infusoria were developed from little minute spores or eggs which were +constantly floating in the atmosphere, and which lose their power of +germination if subjected to heat. But one observer now made another +experiment, which seemed to go entirely the other way, and puzzled him +altogether. He took some of this boiled infusion that I have been speaking +of, and by the use of a mercurial bath--a kind of trough used in +laboratories--he deftly inverted a vessel containing the infusion into the +mercury, so that the latter reached a little beyond the level of the mouth +of the _inverted_ vessel. You see that he thus had a quantity of the +infusion shut off from any possible communication with the outer air by +being inverted upon a bed of mercury. + +He then prepared some pure oxygen and nitrogen gases, and passed them by +means of a tube going from the outside of the vessel, up through the +mercury into the infusion; so that he thus had it exposed to a perfectly +pure atmosphere of the same constituents as the external air. Of course, he +expected he would get no infusorial animalcules at all in that infusion; +but, to his great dismay and discomfiture, he found he almost always did +get them. + +Furthermore, it has been found that experiments made in the manner +described above answer well with most infusions; but that if you fill the +vessel with boiled milk, and then stop the neck with cotton-wool, you +_will_ have infusoria. So that you see there were two experiments that +brought you to one kind of conclusion, and three to another; which was a +most unsatisfactory state of things to arrive at in a scientific inquiry. + +Some few years after this, the question began to be very hotly discussed in +France. There was M. Pouchet, a professor at Rouen, a very learned man, but +certainly not a very rigid experimentalist. He published a number of +experiments of his own, some of which were very ingenious, to show that if +you went to work in a proper way, there was a truth in the doctrine of +spontaneous generation. Well, it was one of the most fortunate things in +the world that M. Pouchet took up this question, because it induced a +distinguished French chemist, M. Pasteur, to take up the question on the +other side; and he has certainly worked it out in the most perfect manner. +I am glad to say, too, that he has published his researches in time to +enable me to give you an account of them. He verified all the experiments +which I have just mentioned to you--and then finding those extraordinary +anomalies, as in the case of the mercury bath and the milk, he set himself +to work to discover their nature. In the case of milk he found it to be a +question of temperature. Milk in a fresh state is slightly alkaline; and it +is a very curious circumstance, but this very slight degree of alkalinity +seems to have the effect of preserving the organisms which fall into it +from the air from being destroyed at a temperature of 212°, which is the +boiling point. But if you raise the temperature 10° when you boil it, the +milk behaves like everything else; and if the air with which it comes in +contact, after being boiled at this temperature, is passed through a +red-hot tube, you will not get a trace of organisms. + +He then turned his attention to the mercury bath, and found on examination +that the surface of the mercury was almost always covered with a very fine +dust. He found that even the mercury itself was positively full of organic +matters; that from being constantly exposed to the air, it had collected an +immense number of these infusorial organisms from the air. Well, under +these circumstances he felt that the case was quite clear, and that the +mercury was not what it had appeared to M. Schwann to be,--a bar to the +admission of these organisms; but that, in reality, it acted as a reservoir +from which the infusion was immediately supplied with the large quantity +that had so puzzled him. + +But not content with explaining the experiments of others, M. Pasteur went +to work to satisfy himself completely. He said to himself: "If my view is +right, and if, in point of fact, all these appearances of spontaneous +generation are altogether due to the falling of minute germs suspended in +the atmosphere,--why, I ought not only to be able to show the germs, but I +ought to be able to catch and sow them, and produce the resulting +organisms." He, accordingly, constructed a very ingenious apparatus to +enable him to accomplish the trapping of the "_germ dust_" in the air. +He fixed in the window of his room a glass tube, in the centre of which he +had placed a ball of gun-cotton, which, as you all know, is ordinary +cotton-wool, which, from having been steeped in strong acid, is converted +into a substance of great explosive power. It is also soluble in alcohol +and ether. One end of the glass tube was, of course, open to the external +air; and at the other end of it he placed an aspirator, a contrivance for +causing a current of the external air to pass through the tube. He kept +this apparatus going for four-and-twenty hours, and then removed the +_dusted_ gun-cotton, and dissolved it in alcohol and ether. He then +allowed this to stand for a few hours, and the result was, that a very fine +dust was gradually deposited at the bottom of it. That dust, on being +transferred to the stage of a microscope, was found to contain an enormous +number of starch grains. You know that the materials of our food and the +greater portion of plants are composed of starch, and we are constantly +making use of it in a variety of ways, so that there is always a quantity +of it suspended in the air. It is these starch grains which form many of +those bright specks that we see dancing in a ray of light sometimes. But +besides these, M. Pasteur found also an immense number of other organic +substances such as spores of fungi, which had been floating about in the +air and had got caged in this way. + +He went farther, and said to himself, "If these really are the things that +give rise to the appearance of spontaneous generation, I ought to be able +to take a ball of this dusted gun-cotton and put it into one of my vessels, +containing that boiled infusion which has been kept away from the air, and +in which no infusoria are at present developed, and then, if I am right, +the introduction of this gun-cotton will give rise to organisms." + +Accordingly, he took one of these vessels of infusion, which had been kept +eighteen months, without the least appearance of life in it, and by a most +ingenious contrivance, he managed to break it open and introduce such a +ball of gun-cotton, without allowing the infusion or the cotton ball to +come into contact with any air but that which had been subjected to a red +heat, and in twenty-four hours he had the satisfaction of finding all the +indications of what had been hitherto called spontaneous generation. He had +succeeded in catching the germs and developing organisms in the way ho had +anticipated. + +It now struck him that the truth of his conclusions might be demonstrated +without all the apparatus he had employed. To do this, he took some +decaying animal or vegetable substance, such as urine, which is an +extremely decomposable substance, or the juice of yeast, or perhaps some +other artificial preparation, and filled a vessel having a long tubular +neck with it. He then boiled the liquid and bent that long neck into an S +shape or zig-zag, leaving it open at the end. The infusion then gave no +trace of any appearance of spontaneous generation, however long it might be +left, as all the germs in the air were deposited in the beginning of the +bent neck. He then cut the tube close to the vessel, and allowed the +ordinary air to have free and direct access; and the result of that was the +appearance of organisms in it, as soon as the infusion had been allowed to +stand long enough to allow of the growth of those it received from the air, +which was about forty-eight hours. The result of M. Pasteur's experiments +proved, therefore, in the most conclusive manner, that all the appearances +of spontaneous generation arose from nothing more than the deposition of +the germs of organisms which were constantly floating in the air. + +To this conclusion, however, the objection was made, that if that were the +cause, then the air would contain such an enormous number of these germs, +that it would be a continual fog. But M. Pasteur replied that they are not +there in anything like the number we might suppose, and that an exaggerated +view has been held on that subject; he showed that the chances of animal or +vegetable life appearing in infusions, depend entirely on the conditions +under which they are exposed. If they are exposed to the ordinary +atmosphere around us, why, of course, you may have organisms appearing +early. But, on the other hand, if they are exposed to air at a great +height, or in some very quiet cellar, you will often not find a single +trace of life. + +So that M. Pasteur arrived at last at the clear and definite result, that +all these appearances are like the case of the worms in the piece of meat, +which was refuted by Redi, simply germs carried by the air and deposited in +the liquids in which they afterwards appear. For my own part, I conceive +that, with the particulars of M. Pasteur's experiments before us, we cannot +fail to arrive at his conclusions; and that the doctrine of spontaneous +generation has received a final _coup de grâce_. + +You, of course, understand that all this in no way interferes with the +_possibility_ of the fabrication of organic matters by the direct +method to which I have referred, remote as that possibility may be. + + + +IV. THE PERPETUATION OF LIVING BEINGS, HEREDITARY TRANSMISSION AND +VARIATION + + +The inquiry which we undertook, at our last meeting, into the state of our +knowledge of the causes of the phenomena of organic nature,--of the past +and of the present,--resolved itself into two subsidiary inquiries: the +first was, whether we know anything, either historically or experimentally, +of the mode of origin of living beings; the second subsidiary inquiry was, +whether, granting the origin, we know anything about the perpetuation and +modifications of the forms of organic beings. The reply which I had to give +to the first question was altogether negative, and the chief result of my +last lecture was, that, neither historically nor experimentally, do we at +present know anything whatsoever about the origin of living forms. We saw +that, historically, we are not likely to know anything about it, although +we may perhaps learn something experimentally; but that at present we are +an enormous distance from the goal I indicated. + +I now, then, take up the next question, What do we know of the +reproduction, the perpetuation, and the modifications of the forms of +living beings, supposing that we have put the question as to their +origination on one side, and have assumed that at present the causes of +their origination are beyond us, and that we know nothing about them? Upon +this question the state of our knowledge is extremely different; it is +exceedingly large: and, if not complete, our experience is certainly most +extensive. It would be impossible to lay it all before you, and the most I +can do, or need do to-night, is to take up the principal points and put +them before you with such prominence as may subserve the purposes of our +present argument. + +The method of the perpetuation of organic beings is of two kinds,--the +non-sexual and the sexual. In the first the perpetuation takes place from +and by a particular act of an individual organism, which sometimes may not +be classed as belonging to any sex at all. In the second case, it is in +consequence of the mutual action and interaction of certain portions of the +organisms of usually two distinct individuals,--the male and the female. +The cases of non-sexual perpetuation are by no means so common as the cases +of sexual perpetuation; and they are by no means so common in the animal as +in the vegetable world. You are all probably familiar with the fact, as a +matter of experience, that you can propagate plants by means of what are +called "cuttings"; for example, that by taking a cutting from a geranium +plant, and rearing it properly, by supplying it with light and warmth and +nourishment from the earth, it grows up and takes the form of its parent, +having all the properties and peculiarities of the original plant. + +Sometimes this process, which the gardener performs artificially, takes +place naturally; that is to say, a little bulb, or portion of the plant, +detaches itself, drops off, and becomes capable of growing as a separate +thing. That is the case with many bulbous plants, which throw off in this +way secondary bulbs, which are lodged in the ground and become developed +into plants. This is a non-sexual process, and from it results the +repetition or reproduction of the form of the original being from which the +bulb proceeds. + +Among animals the same thing takes place. Among the lower forms of animal +life, the infusorial animalculæ we have already spoken of throw off certain +portions, or break themselves up in various directions, sometimes +transversely or sometimes longitudinally; or they may give off buds, which +detach themselves and develop into their proper forms. There is the common +fresh-water polype, for instance, which multiplies itself in this way. Just +in the same way as the gardener is able to multiply and reproduce the +peculiarities and characters of particular plants by means of cuttings, so +can the physiological experimentalist--as was shown by the Abbé Trembley +many years ago--so can he do the same thing with many of the lower forms of +animal life. M. de Trembley showed that you could take a polype and cut it +into two, or four, or many pieces, mutilating it in all directions, and the +pieces would still grow up and reproduce completely the original form of +the animal. These are all cases of non-sexual multiplication, and there are +other instances, and still more extraordinary ones, in which this process +takes place naturally, in a more hidden, a more recondite kind of way. You +are all of you familiar with that little green insect, the _Aphis_ or +blight, as it is called. These little animals, during a very considerable +part of their existence, multiply themselves by means of a kind of internal +budding, the buds being developed into essentially non-sexual animals, +which are neither male nor female; they become converted into young +_Aphides_, which repeat the process, and their offspring after them, +and so on again; you may go on for nine or ten, or even twenty or more +successions; and there is no very good reason to say how soon it might +terminate, or how long it might not go on if the proper conditions of +warmth and nourishment were kept up. + +Sexual reproduction is quite a distinct matter. Here, in all these cases, +what is required is the detachment of two portions of the parental +organisms, which portions we know as the egg or the spermatozoon. In plants +it is the ovule and the pollen-grain, as in the flowering plants, or the +ovule and the antherozooid, as in the flowerless. Among all forms of animal +life, the spermatozoa proceed from the male sex, and the egg is the product +of the female. Now, what is remarkable about this mode of reproduction is +this, that the egg by itself, or the spermatozoa by themselves, are unable +to assume the parental form; but if they be brought into contact with one +another, the effect of the mixture of organic substances proceeding from +two sources appears to confer an altogether new vigour to the mixed +product. This process is brought about, as we all know, by the sexual +intercourse of the two sexes, and is called the act of impregnation. The +result of this act on the part of the male and female is, that the +formation of a new being is set up in the ovule or egg; this ovule or egg +soon begins to be divided and subdivided, and to be fashioned into various +complex organs, and eventually to develop into the form of one of its +parents, as I explained in the first lecture. These are the processes by +which the perpetuation of organic beings is secured. Why there should be +the two modes--why this re-invigoration should be required on the part of +the female element we do not know; but it is most assuredly the fact, and +it is presumable, that, however long the process of non-sexual +multiplication could be continued--I say there is good reason to believe +that it would come to an end if a new commencement were not obtained by a +conjunction of the two sexual elements. + +That character which is common to these two distinct processes is this, +that, whether we consider the reproduction, or perpetuation, or +modification of organic beings as they take place non-sexually, or as they +may take place sexually--in either case, I say, the offspring has a +constant tendency to assume, speaking generally, the character of the +parent. As I said just now, if you take a slip of a plant, and tend it with +care, it will eventually grow up and develop into a plant like that from +which it had sprung; and this tendency is so strong that, as gardeners +know, this mode of multiplying by means of cuttings is the only secure mode +of propagating very many varieties of plants; the peculiarity of the +primitive stock seems to be better preserved if you propagate it by means +of a slip than if you resort to the sexual mode. + +Again, in experiments upon the lower animals, such as the polype, to which +I have referred, it is most extraordinary that, although cut up into +various pieces, each particular piece will grow up into the form of the +primitive stock; the head, if separated, will reproduce the body and the +tail; and if you cut off the tail, you will find that that will reproduce +the body and all the rest of the members, without in any way deviating from +the plan of the organism from which these portions have been detached. And +so far does this go, that some experimentalists have carefully examined the +lower orders of animals,--among them the Abbé Spallanzani, who made a +number of experiments upon snails and salamanders,--and have found that +they might mutilate them to an incredible extent; that you might cut off +the jaw or the greater part of the head, or the leg or the tail, and repeat +the experiment several times, perhaps cutting off the same member again and +again; and yet each of those types would be reproduced according to the +primitive type: Nature making no mistake, never putting on a fresh kind of +leg, or head, or tail, but always tending to repeat and to return to the +primitive type. + +It is the same in sexual reproduction: it is a matter of perfectly common +experience, that the tendency on the part of the offspring always is, +speaking broadly, to reproduce the form of the parents. The proverb has it +that the thistle does not bring forth grapes; so, among ourselves, there is +always a likeness, more or less marked and distinct, between children and +their parents. That is a matter of familiar and ordinary observation. We +notice the same thing occurring in the cases of the domestic animals--dogs, +for instance, and their offspring. In all these cases of propagation and +perpetuation, there seems to be a tendency in the offspring to take the +characters of the parental organisms. To that tendency a special name is +given--and as I may very often use it, I will write it up here on this +black-board that you may remember it--it is called _Atavism_; it +expresses this tendency to revert to the ancestral type, and comes from the +Latin word _atavus_, ancestor. + +Well, this _Atavism_ which I shall speak of, is, as I said before, one +of the most marked and striking tendencies of organic beings; but, side by +side with this hereditary tendency there is an equally distinct and +remarkable tendency to variation. The tendency to reproduce the original +stock has, as it were, its limits, and side by side with it there is a +tendency to vary in certain directions, as if there were two opposing +powers working upon the organic being, one tending to take it in a straight +line, and the other tending to make it diverge from that straight line, +first to one side and then to the other. + +So that you see these two tendencies need not precisely contradict one +another, as the ultimate result may not always be very remote from what +would have been the case if the line had been quite straight. + +This tendency to variation is less marked in that mode of propagation which +takes place non-sexually; it is in that mode that the minor characters of +animal and vegetable structures are most completely preserved. Still, it +will happen sometimes, that the gardener, when he has planted a cutting of +some favourite plant, will find, contrary to his expectation, that the slip +grows up a little different from the primitive stock--that it produces +flowers of a different colour or make, or some deviation in one way or +another. This is what is called the "sporting" of plants. + +In animals the phenomena of non-sexual propagation are so obscure, that at +present we cannot be said to know much about them; but if we turn to that +mode of perpetuation which results from the sexual process, then we find +variation a perfectly constant occurrence, to a certain extent; and, +indeed, I think that a certain amount of variation from the primitive stock +is the necessary result of the method of sexual propagation itself; for, +inasmuch as the thing propagated proceeds from two organisms of different +sexes and different makes and temperaments, and as the offspring is to be +either of one sex or the other, it is quite clear that it cannot be an +exact diagonal of the two, or it would be of no sex at all; it cannot be an +exact intermediate form between that of each of its parents--it must +deviate to one side or the other. You do not find that the male follows the +precise type of the male parent, nor does the female always inherit the +precise characteristics of the mother,--there is always a proportion of the +female character in the male offspring, and of the male character in the +female offspring. That must be quite plain to all of you who have looked at +all attentively on your own children or those of your neighbours; you will +have noticed how very often it may happen that the son shall exhibit the +maternal type of character, or the daughter possess the characteristics of +the father's family. There are all sorts of intermixtures and intermediate +conditions between the two, where complexion, or beauty, or fifty other +different peculiarities belonging to either side of the house, are +reproduced in other members of the same family. Indeed, it is sometimes to +be remarked in this kind of variation, that the variety belongs, strictly +speaking, to neither of the immediate parents; you will see a child in a +family who is not like either its father or its mother; but some old person +who knew its grandfather or grandmother, or, it may be, an uncle, or, +perhaps, even a more distant relative will see a great similarity between +the child and one of these. In this way it constantly happens that the +characteristic of some previous member of the family comes out and is +reproduced and recognised in the most unexpected manner. + +But apart from that matter of general experience, there are some cases +which put that curious mixture in a very clear light. You are aware that +the offspring of the ass and the horse, or rather of the he-ass and the +mare, is what is called a mule; and, on the other hand, the offspring of +the stallion and the she-ass is what is called a hinny. It is a very rare +thing in this country to see a hinny. I never saw one myself; but they have +been very carefully studied. Now, the curious thing is this, that although +you have the same elements in the experiment in each case, the offspring is +entirely different in character, according as the male influence comes from +the ass or the horse. Where the ass is the male, as in the case of the +mule, you find that the head is like that of the ass, that the ears are +long, the tail is tufted at the end, the feet are small, and the voice is +an unmistakable bray; these are all points of similarity to the ass; but, +on the other hand, the barrel of the body and the cut of the neck are much +more like those of the mare. Then, if you look at the hinny,--the result of +the union of the stallion and the she-ass, then you find it is the horse +that has the predominance; that the head is more like that of the horse, +the ears are shorter, the legs coarser, and the type is altogether altered; +while the voice, instead of being a bray, is the ordinary neigh of the +horse. Here, you see, is a most curious thing: you take exactly the same +elements, ass and horse, but you combine the sexes in a different manner, +and the result is modified accordingly. You have in this case, however, a +result which is not general and universal--there is usually an important +preponderance, but not always on the same side. + +Here, then, is one intelligible, and, perhaps, necessary cause of +variation: the fact, that there are two sexes sharing in the production of +the offspring, and that the share taken by each is different and variable, +not only for each combination, but also for different members of the same +family. + +Secondly, there is a variation, to a certain extent--though, in all +probability, the influence of this cause has been very much +exaggerated--but there is no doubt that variation is produced, to a certain +extent, by what are commonly known as external conditions,--such as +temperature, food, warmth, and moisture. In the long run, every variation +depends, in some sense, upon external conditions, seeing that everything +has a cause of its own. I use the term "external conditions" now in the +sense in which it is ordinarily employed: certain it is, that external +conditions have a definite effect. You may take a plant which has single +flowers, and by dealing with the soil, and nourishment, and so on, you may +by and by convert single flowers into double flowers, and make thorns shoot +out into branches. You may thicken or make various modifications in the +shape of the fruit. In animals, too, you may produce analogous changes in +this way, as in the case of that deep bronze colour which persons rarely +lose after having passed any length of time in tropical countries. You may +also alter the development of the muscles very much, by dint of training; +all the world knows that exercise has a great effect in this way; we always +expect to find the arm of a blacksmith hard and wiry, and possessing a +large development of the brachial muscles. No doubt training, which is one +of the forms of external conditions, converts what are originally only +instructions, teachings, into habits, or, in other words, into +organisations, to a great extent; but this second cause of variation cannot +be considered to be by any means a large one. The third cause that I have +to mention, however, is a very extensive one. It is one that, for want of a +better name, has been called "spontaneous variation"; which means that when +we do not know anything about the cause of phenomena, we call it +spontaneous. In the orderly chain of causes and effects in this world, +there are very few things of which it can be said with truth that they are +spontaneous. Certainly not in these physical matters--in these there is +nothing of the kind--everything depends on previous conditions. But when we +cannot trace the cause of phenomena, we call them spontaneous. + +Of these variations, multitudinous as they are, but little is known with +perfect accuracy. I will mention to you some two or three cases, because +they are very remarkable in themselves, and also because I shall want to +use them afterwards. Réaumur, a famous French naturalist, a great many +years ago, in an essay which he wrote upon the art of hatching +chickens--which was indeed a very curious essay--had occasion to speak of +variations and monstrosities. One very remarkable case had come under his +notice of a variation in the form of a human member, in the person of a +Maltese, of the name of Gratio Kelleia, who was born with six fingers upon +each hand, and the like number of toes to each of his feet. That was a case +of spontaneous variation. Nobody knows why he was born with that number of +fingers and toes, and as we don't know, we call it a case of "spontaneous" +variation. There is another remarkable case also. I select these, because +they happen to have been observed and noted very carefully at the time. It +frequently happens that a variation occurs, but the persons who notice it +do not take any care in noting down the particulars, until at length, when +inquiries come to be made, the exact circumstances are forgotten; and +hence, multitudinous as may be such "spontaneous" variations, it is +exceedingly difficult to get at the origin of them. + +The second case is one of which you may find the whole details in the +"Philosophical Transactions" for the year 1813, in a paper communicated by +Colonel Humphrey to the President of the Royal Society--"On a new Variety +in the Breed of Sheep," giving an account of a very remarkable breed of +sheep, which at one time was well known in the northern states of America, +and which went by the name of the Ancon or the Otter breed of sheep. In the +year 1791, there was a farmer of the name of Seth Wright in Massachusetts, +who had a flock of sheep, consisting of a ram and, I think, of some twelve +or thirteen ewes. Of this flock of ewes, one at the breeding-time bore a +lamb which was very singularly formed; it had a very long body, very short +legs, and those legs were bowed. I will tell you by and by how this +singular variation in the breed of sheep came to be noted, and to have the +prominence that it now has. For the present, I mention only these two +cases; but the extent of variation in the breed of animals is perfectly +obvious to any one who has studied natural history with ordinary attention, +or to any person who compares animals with others of the same kind. It is +strictly true that there are never any two specimens which are exactly +alike; however similar, they will always differ in some certain particular. + +Now let us go back to Atavism--to the hereditary tendency I spoke of. What +will come of a variation when you breed from it, when Atavism comes, if I +may say so, to intersect variation? The two cases of which I have mentioned +the history give a most excellent illustration of what occurs. Gratio +Kelleia, the Maltese, married when he was twenty-two years of age, and, as +I suppose there were no six-fingered ladies in Malta, he married an +ordinary five-fingered person. The result of that marriage was four +children; the first, who was christened Salvator, had six fingers and six +toes, like his father; the second was George, who had five fingers and +toes, but one of them was deformed, showing a tendency to variation; the +third was Andrè; he had five fingers and five toes, quite perfect; the +fourth was a girl, Marie; she had five fingers and five toes, but her +thumbs were deformed, showing a tendency toward the sixth. + +These children grew up, and when they came to adult years, they all +married, and of course it happened that they all married five-fingered and +five-toed persons. Now let us see what were the results. Salvator had four +children; they were two boys, a girl, and another boy; the first two boys +and the girl were six-fingered and six-toed like their grandfather; the +fourth boy had only five fingers and five toes. George had only four +children; there were two girls with six fingers and six toes; there was one +girl with six fingers and five toes on the right side, and five fingers and +five toes on the left side, so that she was half and half. The last, a boy, +had five fingers and five toes. The third, Andrè, you will recollect, was +perfectly well-formed, and he had many children whose hands and feet were +all regularly developed. Marie, the last, who, of course, married a man who +had only five fingers, had four children; the first, a boy, was born with +six toes, but the other three were normal. + +Now observe what very extraordinary phenomena are presented here. You have +an accidental variation giving rise to what you may call a monstrosity; you +have that monstrosity or variation diluted in the first instance by an +admixture with a female of normal construction, and you would naturally +expect that, in the results of such an union, the monstrosity, if repeated, +would be in equal proportion with the normal type; that is to say, that the +children would be half and half, some taking the peculiarity of the father, +and the others being of the purely normal type of the mother; but you see +we have a great preponderance of the abnormal type. Well, this comes to be +mixed once more with the pure, the normal type, and the abnormal is again +produced in large proportion, notwithstanding the second dilution. Now what +would have happened if these abnormal types had intermarried with each +other; that is to say, suppose the two boys of Salvator had taken it into +their heads to marry their first cousins, the two first girls of George, +their uncle? You will remember that these are all of the abnormal type of +their grandfather. The result would probably have been, that their +offspring would have been in every case a further development of that +abnormal type. You see it is only in the fourth, in the person of Marie, +that the tendency, when it appears but slightly in the second generation, +is washed out in the third, while the progeny of Andrè, who escaped in the +first instance, escape altogether. + +We have in this case a good example of nature's tendency to the +perpetuation of a variation. Here it is certainly a variation which earned +with it no use or benefit; and yet you see the tendency to perpetuation may +be so strong, that, notwithstanding a great admixture of pure blood, the +variety continues itself up to the third generation, which is largely +marked with it. In this case, as I have said, there was no means of the +second generation intermarrying with any but five-fingered persons, and the +question naturally suggests itself, What would have been the result of such +marriage? Réaumur narrates this case only as far as the third generation. +Certainly it would have been an exceedingly curious thing if we could have +traced this matter any further; had the cousins intermarried, a +six-fingered variety of the human race might have been set up. + +To show you that this supposition is by no means an unreasonable one, let +me now point out what took place in the case of Seth Wright's sheep, where +it happened to be a matter of moment to him to obtain a breed or raise a +flock of sheep like that accidental variety that I have described--and I +will tell you why. In that part of Massachusetts where Seth Wright was +living, the fields were separated by fences, and the sheep, which were very +active and robust, would roam abroad, and without much difficulty jump over +these fences into other people's farms. As a matter of course, this +exuberant activity on the part of the sheep constantly gave rise to all +sorts of quarrels, bickerings, and contentions among the farmers of the +neighbourhood; so it occurred to Seth Wright, who was, like his successors, +more or less 'cute, that if he could get a stock of sheep like those with +the bandy legs, they would not be able to jump over the fences so readily; +and he acted upon that idea. He killed his old ram, and as soon as the +young one arrived at maturity, he bred altogether from it. The result was +even more striking than in the human experiment which I mentioned just now. +Colonel Humphreys testifies that it always happened that the offspring were +either pure Ancons or pure ordinary sheep; that in no case was there any +mixing of the Ancons with the others. In consequence of this, in the course +of a very few years, the farmer was able to get a very considerable flock +of this variety, and a large number of them were spread throughout +Massachusetts. Most unfortunately, however--I suppose it was because they +were so common--nobody took enough notice of them to preserve their +skeletons; and although Colonel Humphreys states that he sent a skeleton to +the President of the Royal Society at the same time that he forwarded his +paper, I am afraid that the variety has entirely disappeared; for a short +time after these sheep had become prevalent in that district, the Merino +sheep were introduced; and as their wool was much more valuable, and as +they were a quiet race of sheep, and showed no tendency to trespasser jump +over fences, the Otter breed of sheep, the wool of which was inferior to +that of the Merino, was gradually allowed to die out. + +You see that these facts illustrate perfectly well what may be done if you +take care to breed from stocks that are similar to each other. After having +got a variation, if, by crossing a variation with the original stock, you +multiply that variation, and then take care to keep that variation distinct +from the original stock, and make them breed together,--then you may almost +certainly produce a race whose tendency to continue the variation is +exceedingly strong. + +This is what is called "selection"; and it is by exactly the same process +as that by which Seth Wright bred his Ancon sheep, that our breeds of +cattle, dogs, and fowls are obtained. There are some possibilities of +exception, but still, speaking broadly, I may say that this is the way in +which all our varied races of domestic animals have arisen; and you must +understand that it is not one peculiarity or one characteristic alone in +which animals may vary. There is not a single peculiarity or characteristic +of any kind, bodily or mental, in which offspring may not vary to a certain +extent from the parent and other animals. + +Among ourselves this is well known. The simplest physical peculiarity is +mostly reproduced. I know a case of a woman who has the lobe of one of her +ears a little flattened. An ordinary observer might scarcely notice it, and +yet every one of her children has an approximation to the same peculiarity +to some extent. If you look at the other extreme, too, the gravest +diseases, such as gout, scrofula, and consumption, may be handed down with +just the same certainty and persistence as we noticed in the perpetuation +of the bandy legs of the Ancon sheep. + +However, these facts are best illustrated in animals, and the extent of the +variation, as is well known, is very remarkable in dogs. For example, there +are some dogs very much smaller than others; indeed, the variation is so +enormous that probably the smallest dog would be about the size of the head +of the largest; there are very great variations in the structural forms not +only of the skeleton but also in the shape of the skull, and in the +proportions of the face and the disposition of the teeth. + +The Pointer, the Retriever, Bulldog, and the Terrier differ very greatly, +and yet there is every reason to believe that every one of these races has +arisen from the same source,--that all the most important races have arisen +by this selective breeding from accidental variation. + +A still more striking case of what may be done by selective breeding, and +it is a better case, because there is no chance of that partial infusion of +error to which I alluded, has been studied very carefully by Mr. +Darwin,--the case of the domestic pigeons. I dare say there may be some +among you who may be pigeon _fanciers_, and I wish you to understand +that in approaching the subject, I would speak with all humility and +hesitation, as I regret to say that I am not a pigeon fancier. I know it is +a great art and mystery, and a thing upon which a man must not speak +lightly; but I shall endeavour, as far as my understanding goes, to give +you a summary of the published and unpublished information which I have +gained from Mr. Darwin. + +Among the enormous variety,--I believe there are somewhere about a hundred +and fifty kinds of pigeons,--there are four kinds which may be selected as +representing the extremest divergences of one kind from another. Their +names are the Carrier, the Pouter, the Fantail, and the Tumbler. In these +large diagrams that I have here they are each represented in their relative +sizes to each other. This first one is the Carrier; you will notice this +large excrescence on its beak; it has a comparatively small head; there is +a bare space round the eyes; it has a long neck, a very long beak, very +strong legs, large feet, long wings, and so on. The second one is the +Pouter, a very large bird, with very long legs and beak. It is called the +Pouter because it is in the habit of causing its gullet to swell up by +inflating it with air. I should tell you that all pigeons have a tendency +to do this at times, but in the Pouter it is carried to an enormous extent. +The birds appear to be quite proud of their power of swelling and puffing +themselves out in this way; and I think it is about as droll a sight as you +can well see to look at a cage full of these pigeons puffing and blowing +themselves out in this ridiculous manner. + +This diagram is a representation of the third kind I mentioned--the +Fantail. It is, you see, a small bird, with exceedingly small legs and a +very small beak. It is most curiously distinguished by the size and extent +of its tail, which, instead of containing twelve feathers, may have many +more,--say thirty, or even more--I believe there are some with as many as +forty-two. This bird has a curious habit of spreading out the feathers of +its tail in such a way that they reach forward and touch its head; and if +this can be accomplished, I believe it is looked upon as a point of great +beauty. + +But here is the last great variety,--the Tumbler; and of that great +variety, one of the principal kinds, and one most prized, is the specimen +represented here--the short-faced Tumbler. Its beak, you see, is reduced to +a mere nothing. Just compare the beak of this one and that of the first +one, the Carrier--I believe the orthodox comparison of the head and beak of +a thoroughly well-bred Tumbler is to stick an oat into a cherry, and that +will give you the proper relative proportions of the beak and head. The +feet and legs are exceedingly small, and the bird appears to be quite a +dwarf when placed side by side with this great Carrier. + +These are differences enough in regard to their external appearance; but +these differences are by no means the whole or even the most important of +the differences which obtain between these birds. There is hardly a single +point of their structure which has not become more or less altered; and to +give you an idea of how extensive these alterations are, I have here some +very good skeletons, for which I am indebted to my friend, Mr. Tegetmeier, +a great authority in these matters; by means of which, if you examine them +by and by, you will be able to see the enormous difference in their bony +structures. + +I had the privilege, some time ago, of access to some important MSS. of Mr. +Darwin, who, I may tell you, has taken very great pains and spent much +valuable time and attention on the investigation of these variations, and +getting together all the facts that bear upon them. I obtained from these +MSS. the following summary of the differences between the domestic breeds +of pigeons; that is to say, a notification of the various points in which +their organisation differs. In the first place, the back of the skull may +differ a good deal, and the development of the bones of the face may vary a +great deal; the back varies a good deal; the shape of the lower jaw varies; +the tongue varies very greatly, not only in correlation to the length and +size of the beak, but it seems also to have a kind of independent variation +of its own. Then the amount of naked skin round the eyes, and at the base +of the beak, may vary enormously; so may the length of the eyelids, the +shape of the nostrils, and the length of the neck. I have already noticed +the habit of blowing out the gullet, so remarkable in the Pouter, and +comparatively so in the others. There are great differences, too, in the +size of the female and the male, the shape of the body, the number and +width of the processes of the ribs, the development of the ribs, and the +size, shape, and development of the breastbone. We may notice, too--and I +mention the fact because it has been disputed by what is assumed to be high +authority,--the variation in the number of the sacral vertebrae. The number +of these varies from eleven to fourteen, and that without any diminution in +the number of the vertebrae of the back or of the tail. Then the number and +position of the tail-feathers may vary enormously, and so may the number of +the primary and secondary feathers of the wings. Again, the length of the +feet and of the beak,--although they have no relation to each other, yet +appear to go together,--that is, you have a long beak wherever you have +long feet. There are differences also in the periods of the acquirement of +the perfect plumage--the size and shape of the eggs--the nature of flight, +and the powers of flight--so-called _"homing"_ birds having enormous +flying powers; [Footnote: The _"Carrier,"_ I learn from Mr. +Tegetmeier, does not _carry_; a high-bred bird of this breed being but +a poor flier. The birds which fly long distances, and come home--"homing" +birds-and are consequently used as carriers, are not "carriers" in the +fancy sense.] while, on the other hand, the little Tumbler is so called +because of its extraordinary faculty of turning head over heels in the air, +instead of pursuing a direct course. And, lastly, the dispositions and +voices of the birds may vary. Thus the case of the pigeons shows you that +there is hardly a single particular--whether of instinct, or habit, or bony +structure, or of plumage--of either the internal economy or the external +shape, in which some variation or change may not take place, which, by +selective breeding, may become perpetuated, and form the foundation of, and +give rise to, a new race. + +If you carry in your mind's eye these four varieties of pigeons, you will +bear with you as good a notion as you can have, perhaps, of the enormous +extent to which a deviation from a primitive type may be carried by means +of this process of selective breeding. + + + +V. THE CONDITIONS OF EXISTENCE AS AFFECTING THE PERPETUATION OF LIVING +BEINGS + + +In the last Lecture I endeavoured to prove to you that, while, as a general +rule, organic beings tend to reproduce their kind, there is in them, also, +a constantly recurring tendency to vary--to vary to a greater or to a less +extent. Such a variety, I pointed out to you, might arise from causes which +we do not understand; we therefore called it spontaneous; and it might come +into existence as a definite and marked thing, without any gradations +between itself and the form which preceded it. I further pointed out, that +such a variety having once arisen, might be perpetuated to some extent, and +indeed to a very marked extent, without any direct interference, or without +any exercise of that process which we called selection. And then I stated +further, that by such selection, when exercised artificially--if you took +care to breed only from those forms which presented the same peculiarities +of any variety which had arisen in this manner--the variation might be +perpetuated, as far as we can see, indefinitely. + +The next question, and it is an important one for us, is this: Is there any +limit to the amount of variation from the primitive stock which can be +produced by this process of selective breeding? In considering this +question, it will be useful to class the characteristics, in respect of +which organic beings vary, under two heads: we may consider structural +characteristics, and we may consider physiological characteristics. + +In the first place, as regards structural characteristics, I endeavoured to +show you, by the skeletons which I had upon the table, and by reference to +a great many well-ascertained facts, that the different breeds of Pigeons, +the Carriers, Pouters, and Tumblers, might vary in any of their internal +and important structural characters to a very great degree; not only might +there be changes in the proportions of the skull, and the characters of the +feet and beaks, and so on; but that there might be an absolute difference +in the number of the vertebrae of the back, as in the sacral vertebras of +the Pouter; and so great is the extent of the variation in these and +similar characters that I pointed out to you, by reference to the skeletons +and the diagrams, that these extreme varieties may absolutely differ more +from one another in their structural characters than do what naturalists +call distinct SPECIES of pigeons; that is to say, that they differ so much +in structure that there is a greater difference between the Pouter and the +Tumbler than there is between such wild and distinct forms as the Rock +Pigeon or the Ring Pigeon, or the Ring Pigeon and the Stock Dove; and +indeed the differences are of greater value than this, for the structural +differences between these domesticated pigeons are such as would be +admitted by a naturalist, supposing he knew nothing at all about their +origin, to entitle them to constitute even distinct genera. + +As I have used this term SPECIES, and shall probably use it a good deal, I +had better perhaps devote a word or two to explaining what I mean by it. + +Animals and plants are divided into groups, which become gradually smaller, +beginning with a KINGDOM, which is divided into SUB-KINGDOMS; then come the +smaller divisions called PROVINCES; and so on from a PROVINCE to a CLASS, +from a CLASS to an ORDER, from ORDERS to FAMILIES, and from these to +GENERA, until we come at length to the smallest groups of animals which can +be defined one from the other by constant characters, which are not sexual; +and these are what naturalists call SPECIES in practice, whatever they may +do in theory. + +If, in a state of nature, you find any two groups of living beings, which +are separated one from the other by some constantly-recurring +characteristic, I don't care how slight and trivial, so long as it is +defined and constant, and does not depend on sexual peculiarities, then all +naturalists agree in calling them two species; that is what is meant by the +use of the word species--that is to say, it is, for the practical +naturalist, a mere question of structural differences. [Footnote: I lay +stress here on the _practical_ signification of "Species." Whether a +physiological test between species exist or not, it is hardly ever +applicable by the practical naturalist.] We have seen now--to repeat this +point once more, and it is very essential that we should rightly understand +it--we have seen that breeds, known to have been derived from a common +stock by selection, may be as different in their structure from the +original stock as species may be distinct from each other. + +But is the like true of the physiological characteristics of animals? Do +the physiological differences of varieties amount in degree to those +observed between forms which naturalists call distinct species? This is a +most important point for us to consider. + +As regards the great majority of physiological characteristics, there is no +doubt that they are capable of being developed, increased, and modified by +selection. + +There is no doubt that breeds may be made as different as species in many +physiological characters. I have already pointed out to you very briefly +the different habits of the breeds of Pigeons, all of which depend upon +their physiological peculiarities--as the peculiar habit of tumbling, in +the Tumbler--the peculiarities of flight, in the "homing" birds--the +strange habit of spreading out the tail, and walking in a peculiar fashion, +in the Fantail--and, lastly, the habit of blowing out the gullet, so +characteristic of the Pouter. These are all due to physiological +modifications, and in all these respects these birds differ as much from +each other as any two ordinary species do. + +So with Dogs in their habits and instincts. It is a physiological +peculiarity which leads the Greyhound to chase its prey by sight--that +enables the Beagle to track it by the scent--that impels the Terrier to its +rat-hunting propensity--and that leads the Retriever to its habit of +retrieving. These habits and instincts are all the results of physiological +differences and peculiarities, which have been developed from a common +stock, at least there is every reason to believe so. But it is a most +singular circumstance, that while you may run through almost the whole +series of physiological processes, without finding a check to your +argument, you come at last to a point where you do find a check, and that +is in the reproductive processes. For there is a most singular circumstance +in respect to natural species--at least about some of them--and it would be +sufficient for the purposes of this argument if it were true of only one of +them, but there is, in fact, a great number of such cases--and that is, +that, similar as they may appear to be to mere races or breeds, they +present a marked peculiarity in the reproductive process. If you breed from +the male and female of the same race, you of course have offspring of the +like kind, and if you make the offspring breed together, you obtain the +same result, and if you breed from these again, you will still have the +same kind of offspring; there is no check. But if you take members of two +distinct species, however similar they may be to each other, and make them +breed together, you will find a check, with some modifications and +exceptions, however, which I shall speak of presently. If you cross two +such species with each other, then--although you may get offspring in the +case of the first cross, yet, if you attempt to breed from the products of +that crossing, which are what are called HYBRIDS--that is, if you couple a +male and a female hybrid--then the result is that in ninety-nine cases out +of a hundred you will get no offspring at all; there will be no result +whatsoever. + +The reason of this is quite obvious in some cases; the male hybrids, +although possessing all the external appearances and characteristics of +perfect animals, are physiologically imperfect and deficient in the +structural parts of the reproductive elements necessary to generation. It +is said to be invariably the case with the male mule, the cross between the +Ass and the Mare; and hence it is, that, although crossing the Horse with +the Ass is easy enough, and is constantly done, as far as I am aware, if +you take two mules, a male and a female, and endeavour to breed from them, +you get no offspring whatever; no generation will take place. This is what +is called the sterility of the hybrids between two distinct species. + +You see that this is a very extraordinary circumstance; one does not see +why it should be. The common teleological explanation is, that it is to +prevent the impurity of the blood resulting from the crossing of one +species with another, but you see it does not in reality do anything of the +kind. There is nothing in this fact that hybrids cannot breed with each +other, to establish such a theory; there is nothing to prevent the Horse +breeding with the Ass, or the Ass with the Horse. So that this explanation +breaks down, as a great many explanations of this kind do, that are only +founded on mere assumptions. + +Thus you see that there is a great difference between "mongrels," which are +crosses between distinct races, and "hybrids," which are crosses between +distinct species. The mongrels are, so far as we know, fertile with one +another. But between species, in many cases, you cannot succeed in +obtaining even the first cross; at any rate it is quite certain that the +hybrids are often absolutely infertile one with another. + +Here is a feature, then, great or small as it may be, which distinguishes +natural species of animals. Can we find any approximation to this in the +different races known to be produced by selective breeding from a common +stock? Up to the present time the answer to that question is absolutely a +negative one. As far as we know at present, there is nothing approximating +to this check. In crossing the breeds between the Fantail and the Pouter, +the Carrier and the Tumbler, or any other variety or race you may name--so +far as we know at present--there is no difficulty in breeding together the +mongrels. Take the Carrier and the Fantail, for instance, and let them +represent the Horse and the Ass in the case of distinct species; then you +have, as the result of their breeding, the Carrier-Fantail mongrel,--we +will say the male and female mongrel,--and, as far as we know, these two +when crossed would not be less fertile than the original cross, or than +Carrier with Carrier. Here, you see, is a physiological contrast between +the races produced by selective modification and natural species. I shall +inquire into the value of this fact, and of some modifying circumstances by +and by; for the present I merely put it broadly before you. + +But while considering this question of the limitations of species, a word +must be said about what is called RECURRENCE--the tendency of races which +have been developed by selective breeding from varieties to return to their +primitive type. This is supposed by many to put an absolute limit to the +extent of selective and all other variations. People say, "It is all very +well to talk about producing these different races, but you know very well +that if you turned all these birds wild, these Pouters, and Carriers, and +so on, they would all return to their primitive stock." This is very +commonly assumed to be a fact, and it is an argument that is commonly +brought forward as conclusive; but if you will take the trouble to inquire +into it rather closely, I think you will find that it is not worth very +much. The first question of course is, Do they thus return to the primitive +stock? And commonly as the thing is assumed and accepted, it is extremely +difficult to get anything like good evidence of it. It is constantly said, +for example, that if domesticated Horses are turned wild, as they have been +in some parts of Asia Minor and South America, that they return at once to +the primitive stock from which they were bred. But the first answer that +you make to this assumption is, to ask who knows what the primitive stock +was; and the second answer is, that in that case the wild Horses of Asia +Minor ought to be exactly like the wild Horses of South America. If they +are both like the same thing, they ought manifestly to be like each other! +The best authorities, however, tell you that it is quite different. The +wild Horse of Asia is said to be of a dun colour, with a largish head, and +a great many other peculiarities; while the best authorities on the wild +Horses of South America tell you that there is no similarity between their +wild Horses and those of Asia Minor; the cut of their heads is very +different, and they are commonly chestnut or bay-coloured. It is quite +clear, therefore, that as by these facts there ought to have been two +primitive stocks, they go for nothing in support of the assumption that +races recur to one primitive stock, and so far as this evidence is +concerned, it falls to the ground. + +Suppose for a moment that it were so, and that domesticated races, when +turned wild, did return to some common condition, I cannot see that this +would prove much more than that similar conditions are likely to produce +similar results; and that when you take back domesticated animals into what +we call natural conditions, you do exactly the same thing as if you +carefully undid all the work you had gone through, for the purpose of +bringing the animal from its wild to its domesticated state. I do not see +anything very wonderful in the fact, if it took all that trouble to get it +from a wild state, that it should go back into its original state as soon +as you removed the conditions which produced the variation to the +domesticated form. There is an important fact, however, forcibly brought +forward by Mr. Darwin, which has been noticed in connection with the +breeding of domesticated pigeons; and it is, that however different these +breeds of pigeons may be from each other, and we have already noticed the +great differences in these breeds, that if, among any of those variations, +you chance to have a blue pigeon turn up, it will be sure to have the black +bars across the wings, which are characteristic of the original wild stock, +the Rock Pigeon. + +Now, this is certainly a very remarkable circumstance; but I do not see +myself how it tells very strongly either one way or the other. I think, in +fact, that this argument in favour of recurrence to the primitive type +might prove a great deal too much for those who so constantly bring it +forward. For example, Mr. Darwin has very forcibly urged, that nothing is +commoner than if you examine a dun horse--and I had an opportunity of +verifying this illustration lately while in the islands of the West +Highlands, where there are a great many dun horses--to find that horse +exhibit a long black stripe down his back, very often stripes on his +shoulder, and very often stripes on his legs. I, myself, saw a pony of this +description a short time ago, in a baker's cart, near Rothesay, in Bute: it +had the long stripe down the back, and stripes on the shoulders and legs, +just like those of the Ass, the Quagga, and the Zebra. Now, if we interpret +the theory of recurrence as applied to this case, might it not be said that +here was a case of a variation exhibiting the characters and conditions of +an animal occupying something like an intermediate position between the +Horse, the Ass, the Quagga, and the Zebra, and from which these had been +developed? In the same way with regard even to Man. Every anatomist will +tell you that there is nothing commoner, in dissecting the human body, than +to meet with what are called muscular variations--that is, if you dissect +two bodies very carefully, you will probably find that the modes of +attachment and insertion of the muscles are not exactly the same in both, +there being great peculiarities in the mode in which the muscles are +arranged; and it is very singular, that in some dissections of the human +body you will come upon arrangements of the muscles very similar indeed to +the same parts in the Apes. Is the conclusion in that case to be, that this +is like the black bars in the case of the Pigeon, and that it indicates a +recurrence to the primitive type from which the animals have been probably +developed? Truly, I think that the opponents of modification and variation +had better leave the argument of recurrence alone, or it may prove +altogether too strong for them. + +To sum up,--the evidence as far as we have gone is against the argument as +to any limit to divergences, so far as structure is concerned; and in +favour of a physiological limitation. By selective breeding we can produce +structural divergences as great as those of species, but we cannot produce +equal physiological divergences. For the present I leave the question +there. + +Now, the next problem that lies before us--and it is an extremely important +one--is this: Does this selective breeding occur in nature? Because, if +there is no proof of it, all that I have been telling you goes for nothing +in accounting for the origin of species. Are natural causes competent to +play the part of selection in perpetuating varieties? Here we labour under +very great difficulties. In the last lecture I had occasion to point out to +you the extreme difficulty of obtaining evidence even of the first origin +of those varieties which we know to have occurred in domesticated animals. +I told you, that almost always the origin of these varieties is overlooked, +so that I could only produce two or three cases, as that of Gratio Kelleia +and of the Ancon sheep. People forget, or do not take notice of them until +they come to have a prominence; and if that is true of artificial cases, +under our own eyes, and in animals in our own care, how much more difficult +it must be to have at first hand good evidence of the origin of varieties +in nature! Indeed, I do not know that it is possible by direct evidence to +prove the origin of a variety in nature, or to prove selective breeding; +but I will tell you what we can prove--and this comes to the same +thing--that varieties exist in nature within the limits of species, and, +what is more, that when a variety has come into existence in nature, there +are natural causes and conditions, which are amply competent to play the +part of a selective breeder; and although that is not quite the evidence +that one would like to have--though it is not direct testimony--yet it is +exceeding good and exceedingly powerful evidence in its way. + +As to the first point, of varieties existing among natural species, I might +appeal to the universal experience of every naturalist, and of any person +who has ever turned any attention at all to the characteristics of plants +and animals in a state of nature; but I may as well take a few definite +cases, and I will begin with Man himself. + +I am one of those who believe that, at present, there is no evidence +whatever for saying, that mankind sprang originally from any more than a +single pair; I must say, that I cannot see any good ground whatever, or +even any tenable sort of evidence, for believing that there is more than +one species of Man. Nevertheless, as you know, just as there are numbers of +varieties in animals, so there are remarkable varieties of men. I speak not +merely of those broad and distinct variations which you see at a glance. +Everybody, of course, knows the difference between a Negro and a white man, +and can tell a Chinaman from an Englishman. They each have peculiar +characteristics of colour and physiognomy; but you must recollect that the +characters of these races go very far deeper--they extend to the bony +structure, and to the characters of that most important of all organs to +us--the brain; so that, among men belonging to different races, or even +within the same race, one man shall have a brain a third, or half, or even +seventy per cent, bigger than another; and if you take the whole range of +human brains, you will find a variation in some cases of a hundred per +cent. Apart from these variations in the size of the brain, the characters +of the skull vary. Thus if I draw the figures of a Mongol and of a Negro +head on the blackboard, in the case of the last the breadth would be about +seven-tenths, and in the other it would be nine-tenths of the total length. +So that you see there is abundant evidence of variation among men in their +natural condition. And if you turn to other animals there is just the same +thing. The fox, for example, which has a very large geographical +distribution all over Europe, and parts of Asia, and on the American +Continent, varies greatly. There are mostly large foxes in the North, and +smaller ones in the South. In Germany alone the foresters reckon some eight +different sorts. + +Of the tiger, no one supposes that there is more than one species; they +extend from the hottest parts of Bengal, into the dry, cold, bitter steppes +of Siberia, into a latitude of 50°,--so that they may even prey upon the +reindeer. These tigers have exceedingly different characteristics, but +still they all keep their general features, so that there is no doubt as to +their being tigers. The Siberian tiger has a thick fur, a small mane, and a +longitudinal stripe down the back, while the tigers of Java and Sumatra +differ in many important respects from the tigers of Northern Asia. So +lions vary; so birds vary; and so, if you go further back and lower down in +creation, you find that fishes vary. In different streams, in the same +country even, you will find the trout to be quite different to each other +and easily recognisable by those who fish in the particular streams. There +is the same differences in leeches; leech collectors can easily point out +to you the differences and the peculiarities which you yourself would +probably pass by; so with fresh-water mussels; so, in fact, with every +animal you can mention. + +In plants there is the same kind of variation. Take such a case even as the +common bramble. The botanists are all at war about it; some of them wanting +to make out that there are many species of it, and others maintaining that +they are but many varieties of one species; and they cannot settle to this +day which is a species and which is a variety! + +So that there can be no doubt whatsoever that any plant and any animal may +vary in nature; that varieties may arise in the way I have described--as +spontaneous varieties--and that those varieties may be perpetuated in the +same way that I have shown you spontaneous varieties are perpetuated; I +say, therefore, that there can be no doubt as to the origin and +perpetuation of varieties in nature. + +But the question now is:--Does selection take place in nature? Is there +anything like the operation of man in exercising selective breeding, taking +place in nature? You will observe that, at present, I say nothing about +species; I wish to confine myself to the consideration of the production of +those natural races which everybody admits to exist. The question is, +whether in nature there are causes competent to produce races, just in the +same way as man is able to produce by selection, such races of animals as +we have already noticed. + +When a variety has arisen, the CONDITIONS OF EXISTENCE are such as to +exercise an influence which is exactly comparable to that of artificial +selection. By Conditions of Existence I mean two things--there are +conditions which are furnished by the physical, the inorganic world, and +there are conditions of existence which are furnished by the organic world. +There is, in the first place, CLIMATE; under that head I include only +temperature and the varied amount of moisture of particular places. In the +next place there is what is technically called STATION, which means--given +the climate, the particular kind of place in which an animal or a plant +lives or grows; for example, the station of a fish is in the water, of a +fresh-water fish in fresh water; the station of a marine fish is in the +sea, and a marine animal may have a station higher or deeper. So again with +land animals: the differences in their stations are those of different +soils and neighbourhoods; some being best adapted to a calcareous, and +others to an arenaceous soil. The third condition of existence is FOOD, by +which I mean food in the broadest sense, the supply of the materials +necessary to the existence of an organic being; in the case of a plant the +inorganic matters, such as carbonic acid, water, ammonia, and the earthy +salts or salines; in the case of the animal the inorganic and organic +matters, which we have seen they require; then these are all, at least the +first two, what we may call the inorganic or physical conditions of +existence. Food takes a mid-place, and then come the organic conditions; by +which I mean the conditions which depend upon the state of the rest of the +organic creation, upon the number and kind of living beings, with which an +animal is surrounded. You may class these under two heads: there are +organic beings, which operate as _opponents_, and there are organic +beings which operate as _helpers_ to any given organic creature. The +opponents may be of two kinds: there are the _indirect opponents_, +which are what we may call _rivals_; and there are the _direct +opponents_, those which strive to destroy the creature; and these we +call _enemies_. By rivals I mean, of course, in the case of plants, +those which require for their support the same kind of soil and station, +and, among animals, those which require the same kind of station, or food, +or climate; those are the indirect opponents; the direct opponents are, of +course, those which prey upon an animal or vegetable. The _helpers_ +may also be regarded as direct and indirect: in the case of a carnivorous +animal, for example, a particular herbaceous plant may, in multiplying, be +an indirect helper, by enabling the herbivora on which the carnivore preys +to get more food, and thus to nourish the carnivore more abundantly; the +direct helper may be best illustrated by reference to some parasitic +creature, such as the tape-worm. The tape-worm exists in the human +intestines, so that the fewer there are of men the fewer there will be of +tape-worms, other things being alike. It is a humiliating reflection, +perhaps, that we may be classed as direct helpers to the tape-worm, but the +fact is so: we can all see that if there were no men there would be no +tape-worms. + +It is extremely difficult to estimate, in a proper way, the importance and +the working of the Conditions of Existence. I do not think there were any +of us who had the remotest notion of properly estimating them until the +publication of Mr. Darwin's work, which has placed them before us with +remarkable clearness; and I must endeavour, as far as I can in my own +fashion, to give you some notion of how they work. We shall find it easiest +to take a simple case, and one as free as possible from every kind of +complication. + +I will suppose, therefore, that all the habitable part of this globe--the +dry land, amounting to about 51,000,000 square miles--I will suppose that +the whole of that dry land has the same climate, and that it is composed of +the same kind of rock or soil, so that there will be the same station +everywhere; we thus get rid of the peculiar influence of different climates +and stations. I will then imagine that there shall be but one organic being +in the world, and that shall be a plant. In this we start fair. Its food is +to be carbonic acid, water and ammonia, and the saline matters in the soil, +which are, by the supposition, everywhere alike. We take one single plant, +with no opponents, no helpers, and no rivals; it is to be a "fair field, +and no favour." Now, I will ask you to imagine further that it shall be a +plant which shall produce every year fifty seeds, which is a very moderate +number for a plant to produce; and that, by the action of the winds and +currents, these seeds shall be equally and gradually distributed over the +whole surface of the land. I want you now to trace out what will occur, and +you will observe that I am not talking fallaciously any more than a +mathematician does when he expounds his problem. If you show that the +conditions of your problem are such as may actually occur in Nature and do +not transgress any of the known laws of Nature in working out your +proposition, then you are as safe in the conclusion you arrive at as is the +mathematician in arriving at the solution of his problem. In science, the +only way of getting rid of the complications with which a subject of this +kind is environed, is to work in this deductive method. What will be the +result, then? I will suppose that every plant requires one square foot of +ground to live upon; and the result will be that, in the course of nine +years, the plant will have occupied every single available spot in the +whole globe! I have chalked upon the blackboard the figures by which I +arrive at the result:-- + + Plants. Plants. + + + 1 x 50 in 1st year = 50 + 50 x 50 " 2nd " = 2,500 + 2,500 x 50 " 3rd " = 125,000 + 125,000 x 50 " 4th " = 6,250,000 + 6,250,000 x 50 " 5th " = 312,500,000 + 312,500,000 x 50 " 6th " = 15,625,000,000 + 15,625,000,000 x 50 " 7th " = 781,250,000,000 + 781,250,000,000 x 50 " 8th " = 39,062,500,000,000 + 39,062,500,000,000 x 50 " 9th " = 1,953,125,000,000,000 + + 51,000,000 square miles--the ) + dry surface of the earth x ) + 27,878,400--the number of ) = sq. ft. 1,421,798,400,000,000 + sq. ft. in 1 sq. mile ) --------------------- + being 531,326,600,000,000 + square feet less than would be required at the end of the ninth + year. + +You will see from this that, at the end of the first year the single plant +will have produced fifty more of its kind; by the end of the second year +these will have increased to 2,500; and so on, in succeeding years, you get +beyond even trillions; and I am not at all sure that I could tell you what +the proper arithmetical denomination of the total number really is; but, at +any rate, you will understand the meaning of all those noughts. Then you +see that, at the bottom, I have taken the 51,000,000 of square miles, +constituting the surface of the dry land; and as the number of square feet +are placed under and subtracted from the number of seeds that would be +produced in the ninth year, you can see at once that there would be an +immense number more of plants than there would be square feet of ground for +their accommodation. This is certainly quite enough to prove my point; that +between the eighth and ninth year after being planted the single plant +would have stocked the whole available surface of the earth. + +This is a thing which is hardly conceivable--it seems hardly +imaginable--yet it is so. It is indeed simply the law of Malthus +exemplified. Mr. Malthus was a clergyman, who worked out this subject most +minutely and truthfully some years ago; he showed quite clearly--and +although he was much abused for his conclusions at the time, they have +never yet been disproved and never will be--he showed that in consequence +of the increase in the number of organic beings in a geometrical ratio, +while the means of existence cannot be made to increase in the same ratio, +that there must come a time when the number of organic beings will be in +excess of the power of production of nutriment, and that thus some check +must arise to the further increase of those organic beings. At the end of +the ninth year we have seen that each plant would not be able to get its +full square foot of ground, and at the end of another year it would have to +share that space with fifty others the produce of the seeds which it would +give off. + +What, then, takes place? Every plant grows up, flourishes, occupies its +square foot of ground, and gives off its fifty seeds; but notice this, that +out of this number only one can come to anything; there is thus, as it +were, forty-nine chances to one against its growing up; it depends upon the +most fortuitous circumstances whether any one of these fifty seeds shall +grow up and flourish, or whether it shall die and perish. This is what Mr. +Darwin has drawn attention to, and called the "STRUGGLE FOR EXISTENCE"; and +I have taken this simple case of a plant because some people imagine that +the phrase seems to imply a sort of fight. + +I have taken this plant and shown you that this is the result of the ratio +of the increase, the necessary result of the arrival of a time coming for +every species when exactly as many members must be destroyed as are born; +that is the inevitable ultimate result of the rate of production. Now, what +is the result of all this? I have said that there are forty-nine struggling +against every one; and it amounts to this, that the smallest possible start +given to any one seed may give it an advantage which will enable it to get +ahead of all the others; anything that will enable any one of these seeds +to germinate six hours before any of the others will, other things being +alike, enable it to choke them out altogether. I have shown you that there +is no particular in which plants will not vary from each other; it is quite +possible that one of our imaginary plants may vary in such a character as +the thickness of the integument of its seeds; it might happen that one of +the plants might produce seeds having a thinner integument, and that would +enable the seeds of that plant to germinate a little quicker than those of +any of the others, and those seeds would most inevitably extinguish the +forty-nine times as many that were struggling with them. + +I have put it in this way, but you see the practical result of the process +is the same as if some person had nurtured the one and destroyed the other +seeds. It does not matter how the variation is produced, so long as it is +once allowed to occur. The variation in the plant once fairly started tends +to become hereditary and reproduce itself; the seeds would spread +themselves in the same way and take part in the struggle with the +forty-nine hundred, or forty-nine thousand, with which they might be +exposed. Thus, by degrees, this variety with some slight organic change or +modification, must spread itself over the whole surface of the habitable +globe, and extirpate or replace the other kinds. That is what is meant by +NATURAL SELECTION; that is the kind of argument by which it is perfectly +demonstrable that the conditions of existence may play exactly the same +part for natural varieties as man does for domesticated varieties. No one +doubts at all that particular circumstances may be more favourable for one +plant and less so for another, and the moment you admit that, you admit the +selective power of nature. Now, although I have been putting a hypothetical +case, you must not suppose that I have been reasoning hypothetically. There +are plenty of direct experiments which bear out what we may call the theory +of natural selection; there is extremely good authority for the statement +that if you take the seed of mixed varieties of wheat and sow it, +collecting the seed next year and sowing it again, at length you will find +that out of all your varieties only two or three have lived, or perhaps +even only one. There were one or two varieties which were best fitted to +get on, and they have killed out the other kinds in just the same way and +with just the same certainty as if you had taken the trouble to remove +them. As I have already said, the operation of nature is exactly the same +as the artificial operation of man. + +But if this be true of that simple case, which I put before you, where +there is nothing but the rivalry of one member of a species with others, +what must be the operation of selective conditions, when you recollect as a +matter of fact, that for every species of animal or plant there are fifty +or a hundred species which might all, more or less, be comprehended in the +same climate, food, and station;--that every plant has multitudinous +animals which prey upon it, and which are its direct opponents; and that +these have other animals preying upon them,--that every plant has its +indirect helpers in the birds that scatter abroad its seed, and the animals +that manure it with their dung;--I say, when these things are considered, +it seems impossible that any variation which may arise in a species in +nature should not tend in some way or other either to be a little better or +worse than the previous stock; if it is a little better it will have an +advantage over and tend to extirpate the latter in this crush and struggle; +and if it is a little worse it will itself be extirpated. + +I know nothing that more appropriately expresses this, than the phrase, +"the struggle for existence "; because it brings before your minds, in a +vivid sort of way, some of the simplest possible circumstances connected +with it. When a struggle is intense there must be some who are sure to be +trodden down, crushed, and overpowered by others; and there will be some +who just manage to get through only by the help of the slightest accident. +I recollect reading an account of the famous retreat of the French troops, +under Napoleon, from Moscow. Worn out, tired, and dejected, they at length +came to a great river over which there was but one bridge for the passage +of the vast army. Disorganised and demoralised as that army was, the +struggle must certainly have been a terrible one--every one heeding only +himself, and crushing through the ranks and treading down his fellows. The +writer of the narrative, who was himself one of those who were fortunate +enough to succeed in getting over, and not among the thousands who were +left behind or forced into the river, ascribed his escape to the fact that +he saw striding onward through the mass a great strong fellow,--one of the +French Cuirassiers, who had on a large blue cloak-and he had enough +presence of mind to catch and retain a hold of this strong man's cloak. He +says, "I caught hold of his cloak, and although he swore at me and cut at +and struck me by turns, and at last, when he found he could not shake me +off, fell to entreating me to leave go or I should prevent him from +escaping, besides not assisting myself, I still kept tight hold of him, and +would not quit my grasp until he had at last dragged me through." Here you +see was a case of selective saving--if we may so term it--depending for its +success on the strength of the cloth of the Cuirassier's cloak. It is the +same in nature; every species has its bridge of Beresina; it has to fight +its way through and struggle with other species; and when well-nigh +overpowered, it may be that the smallest chance, something in its colour, +perhaps--the minutest circumstance--will turn the scale one way or the +other. + +Suppose that by a variation of the black race it had produced the white man +at any time--you know that the Negroes are said to believe this to have +been the case, and to imagine that Cain was the first white man, and that +we are his descendants--suppose that this had ever happened, and that the +first residence of this human being was on the West Coast of Africa. There +is no great structural difference between the white man and the Negro, and +yet there is something so singularly different in the constitution of the +two, that the malarias of that country, which do not hurt the black at all, +cut off and destroy the white. Then you see there would have been a +selective operation performed; if the white man had risen in that way, he +would have been selected out and removed by means of the malaria. Now there +really is a very curious case of selection of this sort among pigs, and it +is a case of selection of colour too. In the woods of Florida there are a +great many pigs, and it is a very curious thing that they are all black, +every one of them. Professor Wyman was there some years ago, and on +noticing no pigs but these black ones, he asked some of the people how it +was that they had no white pigs, and the reply was that in the woods of +Florida there was a root which they called the Paint Root, and that if the +white pigs were to eat any of it, it had the effect of making their hoofs +crack, and they died, but if the black pigs ate any of it, it did not hurt +them at all. Here was a very simple case of natural selection. A skilful +breeder could not more carefully develop the black breed of pigs, and weed +out all the white pigs, than the Paint Root does. + +To show you how remarkably indirect may be such natural selective agencies +as I have referred to, I will conclude by noticing a case mentioned by Mr. +Darwin, and which is certainly one of the most curious of its kind. It is +that of the Humble Bee. It has been noticed that there are a great many +more humble bees in the neighbourhood of towns, than out in the open +country; and the explanation of the matter is this: the humble bees build +nests, in which they store their honey and deposit the larvæ and eggs. The +field mice are amazingly fond of the honey and larvæ; therefore, wherever +there are plenty of field mice, as in the country, the humble bees are kept +down; but in the neighbourhood of towns, the number of cats which prowl +about the fields eat up the field mice, and of course the more mice they +eat up the less there are to prey upon the larvæ of the bees--the cats are +therefore the INDIRECT HELPERS of the bees. [Footnote: The humble bees, on +the other hand, are direct helpers of some plants, such as the heartsease +and red clover, which are fertilised by the visits of the bees; and they +are indirect helpers of the numerous insects which are more or less +completely supported by the heartsease and red clover.] Coming back a step +farther we may say that the old maids are also indirect friends of the +humble bees, and indirect enemies of the field mice, as they keep the cats +which eat up the latter! This is an illustration somewhat beneath the +dignity of the subject, perhaps, but it occurs to me in passing, and with +it I will conclude this lecture. + + + +VI. A CRITICAL EXAMINATION OF THE POSITION OF MR. DARWIN'S WORK, "ON THE +ORIGIN OF SPECIES," IN RELATION TO THE COMPLETE THEORY OF THE CAUSES OF THE +PHENOMENA OF ORGANIC NATURE + + +In the preceding five lectures I have endeavoured to give you an account of +those facts, and of those reasonings from facts, which form the data upon +which all theories regarding the causes of the phenomena of organic nature +must be based. And, although I have had frequent occasion to quote Mr. +Darwin--as all persons hereafter, in speaking upon these subjects, will +have occasion to quote his famous book on the "Origin of Species,"--you +must yet remember that, wherever I have quoted him, it has not been upon +theoretical points, or for statements in any way connected with his +particular speculations, but on matters of fact, brought forward by +himself, or collected by himself, and which appear incidentally in his +book. If a man _will_ make a book, professing to discuss a single +question, an encyclopædia, I cannot help it. + +Now, having had an opportunity of considering in this sort of way the +different statements bearing upon all theories whatsoever, I have to lay +before you, as fairly as I can, what is Mr. Darwin's view of the matter and +what position his theories hold, when judged by the principles which I have +previously laid down, as deciding our judgments upon all theories and +hypotheses. + +I have already stated to you that the inquiry respecting the causes of the +phenomena of organic nature resolves itself into two problems--the first +being the question of the origination of living or organic beings; and the +second being the totally distinct problem of the modification and +perpetuation of organic beings when they have already come into existence. +The first question Mr. Darwin does not touch; he does not deal with it at +all; but he says:--"Given the origin of organic matter--supposing its +creation to have already taken place, my object is to show in consequence +of what laws and what demonstrable properties of organic matter, and of its +environments, such states of organic nature as those with which we are +acquainted must have come about." This, you will observe, is a perfectly +legitimate proposition; every person has a right to define the limits of +the inquiry which he sets before himself; and yet it is a most singular +thing that in all the multifarious, and, not unfrequently, ignorant attacks +which have been made upon the "Origin of Species," there is nothing which +has been more speciously criticised than this particular limitation. If +people have nothing else to urge against the book, they say--"Well, after +all, you see Mr. Darwin's explanation of the 'Origin of Species' is not +good for much, because, in the long run, he admits that he does not know +how organic matter began to exist. But if you admit any special creation +for the first particle of organic matter you may just as well admit it for +all the rest; five hundred or five thousand distinct creations are just as +intelligible, and just as little difficult to understand, as one." The +answer to these cavils is two-fold. In the first place, all human inquiry +must stop somewhere; all our knowledge and all our investigation cannot +take us beyond the limits set by the finite and restricted character of our +faculties, or destroy the endless unknown, which accompanies, like its +shadow, the endless procession of phenomena. So far as I can venture to +offer an opinion on such a matter, the purpose of our being in existence, +the highest object that human beings can set before themselves, is not the +pursuit of any such chimera as the annihilation of the unknown; but it is +simply the unwearied endeavour to remove its boundaries a little further +from our little sphere of action. + +I wonder if any historian would for a moment admit the objection, that it +is preposterous to trouble ourselves about the history of the Roman Empire, +because we do not know anything positive about the origin and first +building of the city of Rome! Would it be a fair objection to urge, +respecting the sublime discoveries of a Newton, or a Kepler, those great +philosophers, whose discoveries have been of the profoundest benefit and +service to all men--to say to them--"After all that you have told us as to +how the planets revolve, and how they are maintained in their orbits, you +cannot tell us what is the cause of the origin of the sun, moon, and stars. +So what is the use of what you have done?" Yet these objections would not +be one whit more preposterous than the objections which have been made to +the "Origin of Species." Mr. Darwin, then, had a perfect right to limit his +inquiry as he pleased, and the only question for us--the inquiry being so +limited--is to ascertain whether the method of his inquiry is sound or +unsound; whether he has obeyed the canons which must guide and govern all +investigation, or whether he has broken them; and it was because our +inquiry this evening is essentially limited to that question, that I spent +a good deal of time in a former lecture (which, perhaps some of you thought +might have been better employed), in endeavouring to illustrate the method +and nature of scientific inquiry in general. We shall now have to put in +practice the principles that I then laid down. + +I stated to you in substance, if not in words, that wherever there are +complex masses of phenomena to be inquired into, whether they be phenomena +of the affairs of daily life, or whether they belong to the more abstruse +and difficult problems laid before the philosopher, our course of +proceeding in unravelling that complex chain of phenomena with a view to +get at its cause, is always the same; in all cases we must invent an +hypothesis; we must place before ourselves some more or less likely +supposition respecting that cause; and then, having assumed an hypothesis, +having supposed a cause for the phenomena in question, we must endeavour, +on the one hand, to demonstrate our hypothesis, or, on the other, to upset +and reject it altogether, by testing it in three ways. We must, in the +first place, be prepared to prove that the supposed causes of the phenomena +exist in nature; that they are what the logicians call _vera +causæ_--true causes;--in the next place, we should be prepared to show +that the assumed causes of the phenomena are competent to produce such +phenomena as those which we wish to explain by them; and in the last place, +we ought to be able to show that no other known causes are competent to +produce these phenomena. If we can succeed in satisfying these three +conditions we shall have demonstrated our hypothesis; or rather I ought to +say we shall have proved it as far as certainty is possible for us; for, +after all, there is no one of our surest convictions which may not be +upset, or at any rate modified by a further accession of knowledge. It was +because it satisfied these conditions that we accepted the hypothesis as to +the disappearance of the tea-pot and spoons in the case I supposed in a +previous lecture; we found that our hypothesis on that subject was tenable +and valid, because the supposed cause existed in nature, because it was +competent to account for the phenomena, and because no other known cause +was competent to account for them; and it is upon similar grounds that any +hypothesis you choose to name is accepted in science as tenable and valid. + +What is Mr. Darwin's hypothesis? As I apprehend it--for I have put it into +a shape more convenient for common purposes than I could find +_verbatim_ in his book--as I apprehend it, I say, it is, that all the +phenomena of organic nature, past and present, result from, or are caused +by, the inter-action of those properties of organic matter, which we have +called ATAVISM and VARIABILITY, with the CONDITIONS OF EXISTENCE, or, in +other words,--given the existence of organic matter, its tendency to +transmit its properties, and its tendency occasionally to vary; and, +lastly, given the conditions of existence by which organic matter is +surrounded--that these put together are the causes of the Present and of +the Past conditions of ORGANIC NATURE. + +Such is the hypothesis as I understand it. Now let us see how it will stand +the various tests which I laid down just now. In the first place, do these +supposed causes of the phenomena exist in nature? Is it the fact that, in +nature, these properties of organic matter--atavism and variability--and +those phenomena which we have called the conditions of existence,--is it +true that they exist? Well, of course, if they do not exist, all that I +have told you in the last three or four lectures must be incorrect, because +I have been attempting to prove that they do exist, and I take it that +there is abundant evidence that they do exist; so far, therefore, the +hypothesis does not break down. + +But in the next place comes a much more difficult inquiry:--Are the causes +indicated competent to give rise to the phenomena of organic nature? I +suspect that this is indubitable to a certain extent. It is demonstrable, I +think, as I have endeavoured to show you, that they are perfectly competent +to give rise to all the phenomena which are exhibited by RACES in nature. +Furthermore, I believe that they are quite competent to account for all +that we may call purely structural phenomena which are exhibited by SPECIES +in nature. On that point also I have already enlarged somewhat. Again, I +think that the causes assumed are competent to account for most of the +physiological characteristics of species, and I not only think that they +are competent to account for them, but I think that they account for many +things which otherwise remain wholly unaccountable and inexplicable, and I +may say incomprehensible. For a full exposition of the grounds on which +this conviction is based, I must refer you to Mr. Darwin's work; all that I +can do now is to illustrate what I have said by two or three cases taken +almost at random. + +I drew your attention, on a previous evening, to the facts which are +embodied in our systems of Classification, which are the results of the +examination and comparison of the different members of the animal kingdom +one with another. I mentioned that the whole of the animal kingdom is +divisible into five sub-kingdoms; that each of these sub-kingdoms is again +divisible into provinces; that each province may be divided into classes, +and the classes into the successively smaller groups, orders, families, +genera, and species. + +Now, in each of these groups the resemblance in structure among the members +of the group is closer in proportion as the group is smaller. Thus, a man +and a worm are members of the animal kingdom in virtue of certain +apparently slight though really fundamental resemblances which they +present. But a man and a fish are members of the same sub-kingdom +_Vertebrata_, because they are much more like one another than either +of them is to a worm, or a snail, or any member of the other sub-kingdoms. +For similar reasons men and horses are arranged as members of the same +Class, _Mammalia_; men and apes as members of the same Order, +_Primates_; and if there were any animals more like men than they were +like any of the apes, and yet different from men in important and constant +particulars of their organisation, we should rank them as members of the +same Family, or of the same Genus, but as of distinct Species. + +That it is possible to arrange all the varied forms of animals into groups, +having this sort of singular subordination one to the other, is a very +remarkable circumstance; but, as Mr. Darwin remarks, this is a result which +is quite to be expected, if the principles which he lays down be correct. +Take the case of the races which are known to be produced by the operation +of atavism and variability, and the conditions of existence which check and +modify these tendencies. Take the case of the pigeons that I brought before +you: there it was shown that they might be all classed as belonging to some +one of five principal divisions, and that within these divisions other +subordinate groups might be formed. The members of these groups are related +to one another in just the same way as the genera of a family, and the +groups themselves as the families of an order, or the orders of a class; +while all have the same sort of structural relations with the wild +rock-pigeon, as the members of any great natural group have with a real or +imaginary typical form. Now, we know that all varieties of pigeons of every +kind have arisen by a process of selective breeding from a common stock, +the rock-pigeon; hence, you see, that if all species of animals have +proceeded from some common stock, the general character of their structural +relations, and of our systems of classification, which express those +relations, would be just what we find them to be. In other words, the +hypothetical cause is, so far, competent to produce effects similar to +those of the real cause. + +Take, again, another set of very remarkable facts,--the existence of what +are called rudimentary organs, organs for which we can find no obvious use, +in the particular animal economy in which they are found, and yet which are +there. + +Such are the splint-like bones in the leg of the horse, which I here show +you, and which correspond with bones which belong to certain toes and +fingers in the human hand and foot. In the horse you see they are quite +rudimentary, and bear neither toes nor fingers; so that the horse has only +one "finger" in his fore-foot and one "toe" in his hind-foot. But it is a +very curious thing that the animals closely allied to the horse show more +toes than he; as the rhinoceros, for instance: he has these extra toes well +formed, and anatomical facts show very clearly that he is very closely +related to the horse indeed. So we may say that animals, in an anatomical +sense nearly related to the horse, have those parts which are rudimentary +in him fully developed. + +Again, the sheep and the cow have no cutting-teeth, but only a hard pad in +the upper jaw. That is the common characteristic of ruminants in general. +But the calf has in its upper jaw some rudiments of teeth which never are +developed, and never play the part of teeth at all. Well, if you go back in +time, you find some of the older, now extinct, allies of the ruminants have +well-developed teeth in their upper jaws; and at the present day the pig +(which is in structure closely connected with ruminants) has well-developed +teeth in its upper jaw; so that here is another instance of organs +well-developed and very useful, in one animal, represented by rudimentary +organs, for which we can discover no purpose whatsoever in another closely +allied animal. The whalebone whale, again, has horny "whalebone" plates in +its mouth, and no teeth; but the young foetal whale before it is born has +teeth in its jaws; they, however, are never used, and they never come to +anything. But other members of the group to which the whale belongs have +well-developed teeth in both jaws. + +Upon any hypothesis of special creation, facts of this kind appear to me to +be entirely unaccountable and inexplicable, but they cease to be so if you +accept Mr. Darwin's hypothesis, and see reason for believing that the +whalebone whale and the whale with teeth in its mouth both sprang from a +whale that had teeth, and that the teeth of the foetal whale are merely +remnants--recollections, if we may so say--of the extinct whale. So in the +case of the horse and the rhinoceros: suppose that both have descended by +modification from some earlier form which had the normal number of toes, +and the persistence of the rudimentary bones which no longer support toes +in the horse becomes comprehensible. + +In the language that we speak in England, and in the language of the +Greeks, there are identical verbal roots, or elements entering into the +composition of words. That fact remains unintelligible so long as we +suppose English and Greek to be independently created tongues; but when it +is shown that both languages are descended from one original, we give an +explanation of that resemblance. In the same way the existence of identical +structural roots, if I may so term them, entering into the composition of +widely different animals, is striking evidence in favour of the descent of +those animals from a common original. + +To turn to another kind of illustration:--If you regard the whole series of +stratified rocks--that enormous thickness of sixty or seventy thousand feet +that I have mentioned before, constituting the only record we have of a +most prodigious lapse of time, that time being, in all probability, but a +fraction of that of which we have no record;--if you observe in these +successive strata of rocks successive groups of animals arising and dying +out, a constant succession, giving you the same kind of impression, as you +travel from one group of strata to another, as you would have in travelling +from one country to another;--when you find this constant succession of +forms, their traces obliterated except to the man of science--when you look +at this wonderful history, and ask what it means, it is only a paltering +with words if you are offered the reply--"They were so created." + +But if, on the other hand, you look on all forms of organised beings as the +results of the gradual modification of a primitive type, the facts receive +a meaning, and you see that these older conditions are the necessary +predecessors of the present. Viewed in this light the facts of +palaeontology receive a meaning--upon any other hypothesis I am unable to +see, in the slightest degree, what knowledge or signification we are to +draw out of them. Again, note as bearing upon the same point, the singular +likeness which obtains between the successive Faunæ and Floræ, whose +remains are preserved on the rocks: you never find any great and enormous +difference between the immediately successive Faunæ and Floræ, unless you +have reason to believe there has also been a great lapse of time or a great +change of conditions. The animals, for instance, of the newest tertiary +rocks, in any part of the world, are always, and without exception, found +to be closely allied with those which now live in that part of the world. +For example, in Europe, Asia, and Africa, the large mammals are at present +rhinoceroses, hippopotamuses, elephants, lions, tigers, oxen, horses, &c.; +and if you examine the newest tertiary deposits, which contain the animals +and plants which immediately preceded those which now exist in the same +country, you do not find gigantic specimens of ant-eaters and kangaroos, +but you find rhinoceroses, elephants, lions, tigers, &c.,--of different +species to those now living--but still their close allies. If you turn to +South America, where, at the present day, we have great sloths and +armadilloes and creatures of that kind, what do you find in the newest +tertiaries? You find the great sloth-like creature, the _Megatherium_, +and the great armadillo, the _Glyptodon_, and so on. And if you go to +Australia you find the same law holds good, namely, that that condition of +organic nature which has preceded the one which now exists, presents +differences perhaps of species, and of genera, but that the great types of +organic structure are the same as those which now flourish. + +What meaning has this fact upon any other hypothesis or supposition than +one of successive modification? But if the population of the world, in any +age, is the result of the gradual modification of the forms which peopled +it in the preceding age--if that has been the case, it is intelligible +enough; because we may expect that the creature that results from the +modification of an elephantine mammal shall be something like an elephant, +and the creature which is produced by the modification of an armadillo-like +mammal shall be like an armadillo. Upon that supposition, I say, the facts +are intelligible; upon any other, that I am aware of, they are not. + +So far, the facts of palæontology are consistent with almost any form of +the doctrine of progressive modification; they would not be absolutely +inconsistent with the wild speculations of De Maillet, or with the less +objectionable hypothesis of Lamarck. But Mr. Darwin's views have one +peculiar merit; and that is, that they are perfectly consistent with an +array of facts which are utterly inconsistent with, and fatal to, any other +hypothesis of progressive modification which has yet been advanced. It is +one remarkable peculiarity of Mr. Darwin's hypothesis that it involves no +necessary progression or incessant modification, and that it is perfectly +consistent with the persistence for any length of time of a given primitive +stock, contemporaneously with its modifications. To return to the case of +the domestic breeds of pigeons, for example; you have the dove-cot pigeon, +which closely resembles the rock pigeon, from which they all started, +existing at the same time with the others. And if species are developed in +the same way in nature, a primitive stock and its modifications may, +occasionally, all find the conditions fitted for their existence; and +though they come into competition, to a certain extent, with one another, +the derivative species may not necessarily extirpate the primitive one, or +_vice versa_. + +Now palæontology shows us many facts which are perfectly harmonious with +these observed effects of the process by which Mr. Darwin supposes species +to have originated, but which appear to me to be totally inconsistent with +any other hypothesis which has been proposed. There are some groups of +animals and plants, in the fossil world, which have been said to belong to +"persistent types," because they have persisted, with very little change +indeed, through a very great range of time, while everything about them has +changed largely. There are families of fishes whose type of construction +has persisted all the way from the carboniferous strata right up to the +cretaceous; and others which have lasted through almost the whole range of +the secondary rocks, and from the lias to the older tertiaries. It is +something stupendous this--to consider a genus lasting without essential +modifications through all this enormous lapse of time while almost +everything else was changed and modified. + +Thus I have no doubt that Mr. Darwin's hypothesis will be found competent +to explain the majority of the phenomena exhibited by species in nature; +but in an earlier lecture I spoke cautiously with respect to its power of +explaining all the physiological peculiarities of species. + +There is, in fact, one set of these peculiarities which the theory of +selective modification, as it stands at present, is not wholly competent to +explain, and that is the group of phenomena which I mentioned to you under +the name of Hybridism, and which I explained to consist in the sterility of +the offspring of certain species when crossed one with another. It matters +not one whit whether this sterility is universal, or whether it exists only +in a single case. Every hypothesis is bound to explain, or, at any rate, +not be inconsistent with, the whole of the facts which it professes to +account for; and if there is a single one of these facts which can be shown +to be inconsistent with (I do not merely mean inexplicable by, but contrary +to) the hypothesis, the hypothesis falls to the ground,--it is worth +nothing. One fact with which it is positively inconsistent is worth as +much, and as powerful in negativing the hypothesis, as five hundred. If I +am right in thus defining the obligations of an hypothesis, Mr. Darwin, in +order to place his views beyond the reach of all possible assault, ought to +be able to demonstrate the possibility of developing from a particular +stock by selective breeding, two forms, which should either be unable to +cross one with another, or whose cross-bred offspring should be infertile +with one another. + +For, you see, if you have not done that you have not strictly fulfilled all +the conditions of the problem; you have not shown that you can produce, by +the cause assumed, all the phenomena which you have in nature. Here are the +phenomena of Hybridism staring you in the face, and you cannot say, "I can, +by selective modification, produce these same results." Now, it is admitted +on all hands that, at present, so far as experiments have gone, it has not +been found possible to produce this complete physiological divergence by +selective breeding. I stated this very clearly before, and I now refer to +the point, because, if it could be proved, not only that this _has_ +not been done, but that it _cannot_ be done; if it could be +demonstrated that it is impossible to breed selectively, from any stock, a +form which shall not breed with another, produced from the same stock; and +if we were shown that this must be the necessary and inevitable results of +all experiments, I hold that Mr. Darwin's hypothesis would be utterly +shattered. + +But has this been done? or what is really the state of the case? It is +simply that, so far as we have gone yet with our breeding, we have not +produced from a common stock two breeds which are not more or less fertile +with one another. + +I do not know that there is a single fact which would justify any one in +saying that any degree of sterility has been observed between breeds +absolutely known to have been produced by selective breeding from a common +stock. On the other hand, I do not know that there is a single fact which +can justify any one in asserting that such sterility cannot be produced by +proper experimentation. For my own part, I see every reason to believe that +it may, and will be so produced. For, as Mr. Darwin has very properly +urged, when we consider the phenomena of sterility, we find they are most +capricious; we do not know what it is that the sterility depends on. There +are some animals which will not breed in captivity; whether it arises from +the simple fact of their being shut up and deprived of their liberty, or +not, we do not know, but they certainly will not breed. What an astounding +thing this is, to find one of the most important of all functions +annihilated by mere imprisonment! + +So, again, there are cases known of animals which have been thought by +naturalists to be undoubted species, which have yielded perfectly fertile +hybrids; while there are other species which present what everybody +believes to be varieties [Footnote: And as I conceive with very good +reason; but if any objector urges that we cannot prove that they have been +produced by artificial or natural selection, the objection must be +admitted--ultra-sceptical as it is. But in science, scepticism is a duty.] +which are more or less infertile with one another. There are other cases +which are truly extraordinary; there is one, for example, which has been +carefully examined,--of two kinds of sea-weed, of which the male element of +the one, which we may call A, fertilises the female element of the other, +B; while the male element of B will not fertilise the female element of A; +so that, while the former experiment seems to show us that they are +_varieties_, the latter leads to the conviction that they are +_species_. + +When we see how capricious and uncertain this sterility is, how unknown the +conditions on which it depends, I say that we have no right to affirm that +those conditions will not be better understood by and by, and we have no +ground for supposing that we may not be able to experiment so as to obtain +that crucial result which I mentioned just now. So that though Mr. Darwin's +hypothesis does not completely extricate us from this difficulty at +present, we have not the least right to say it will not do so. + +There is a wide gulf between the thing you cannot explain and the thing +that upsets you altogether. There is hardly any hypothesis in this world +which has not some fact in connection with it which has not been explained, +but that is a very different affair to a fact that entirely opposes your +hypothesis; in this case all you can say is, that your hypothesis is in the +same position as a good many others. + +Now, as to the third test, that there are no other causes competent to +explain the phenomena, I explained to you that one should be able to say of +an hypothesis, that no other known causes than those supposed by it are +competent to give rise to the phenomena. Here, I think, Mr. Darwin's view +is pretty strong. I really believe that the alternative is either Darwinism +or nothing, for I do not know of any rational conception or theory of the +organic universe which has any scientific position at all beside Mr. +Darwin's. I do not know of any proposition that has been put before us with +the intention of explaining the phenomena of organic nature, which has in +its favour a thousandth part of the evidence which may be adduced in favour +of Mr. Darwin's views. Whatever may be the objections to his views, +certainly all other theories are absolutely out of court. + +Take the Lamarckian hypothesis, for example. Lamarck was a great +naturalist, and to a certain extent went the right way to work; he argued +from what was undoubtedly a true cause of some of the phenomena of organic +nature. He said it is a matter of experience that an animal may be modified +more or less in consequence of its desires and consequent actions. Thus, if +a man exercise himself as a blacksmith, his arms will become strong and +muscular; such organic modification is a result of this particular action +and exercise. Lamarck thought that by a very simple supposition based on +this truth he could explain the origin of the various animal species: he +said, for example, that the short-legged birds which live on fish had been +converted into the long-legged waders by desiring to get the fish without +wetting their feathers, and so stretching their legs more and more through +successive generations. If Lamarck could have shown experimentally that +even races of animals could be produced in this way, there might have been +some ground for his speculations. But he could show nothing of the kind, +and his hypothesis has pretty well dropped into oblivion, as it deserved to +do. I said in an earlier lecture that there are hypotheses and hypotheses, +and when people tell you that Mr. Darwin's strongly-based hypothesis is +nothing but a mere modification of Lamarck's, you will know what to think +of their capacity for forming a judgment on this subject. + +But you must recollect that when I say I think it is either Mr. Darwin's +hypothesis or nothing; that either we must take his view, or look upon the +whole of organic nature as an enigma, the meaning of which is wholly hidden +from us; you must understand that I mean that I accept it provisionally, in +exactly the same way as I accept any other hypothesis. Men of science do +not pledge themselves to creeds; they are bound by articles of no sort; +there is not a single belief that it is not a bounden duty with them to +hold with a light hand and to part with cheerfully, the moment it is really +proved to be contrary to any fact, great or small. And if, in course of +time I see good reasons for such a proceeding, I shall have no hesitation +in coming before you, and pointing out any change in my opinion without +finding the slightest occasion to blush for so doing. So I say that we +accept this view as we accept any other, so long as it will help us, and we +feel bound to retain it only so long as it will serve our great +purpose--the improvement of Man's estate and the widening of his knowledge. +The moment this, or any other conception, ceases to be useful for these +purposes, away with it to the four winds; we care not what becomes of it! + +But to say truth, although it has been my business to attend closely to the +controversies roused by the publication of Mr. Darwin's book, I think that +not one of the enormous mass of objections and obstacles which have been +raised is of any very great value, except that sterility case which I +brought before you just now. All the rest are misunderstandings of some +sort, arising either from prejudice, or want of knowledge, or still more +from want of patience and care in reading the work. + +For you must recollect that it is not a book to be read with as much ease +as its pleasant style may lead you to imagine. You spin through it as if it +were a novel the first time you read it, and think you know all about it; +the second time you read it you think you know rather less about it; and +the third time, you are amazed to find how little you have really +apprehended its vast scope and objects. I can positively say that I never +take it up without finding in it some new view, or light, or suggestion +that I have not noticed before. That is the best characteristic of a +thorough and profound book; and I believe this feature of the "Origin of +Species" explains why so many persons have ventured to pass judgment and +criticisms upon it which are by no means worth the paper they are written +on. + +Before concluding these lectures there is one point to which I must +advert--though, as Mr. Darwin has said nothing about man in his book, it +concerns myself rather than him;--for I have strongly maintained on sundry +occasions that if Mr. Darwin's views are sound, they apply as much to man +as to the lower mammals, seeing that it is perfectly demonstrable that the +structural differences which separate man from the apes are not greater +than those which separate some apes from others. There cannot be the +slightest doubt in the world that the argument which applies to the +improvement of the horse from an earlier stock, or of ape from ape, applies +to the improvement of man from some simpler and lower stock than man. There +is not a single faculty--functional or structural, moral, intellectual, or +instinctive, there--is no faculty whatever that is not capable of +improvement; there is no faculty whatsoever which does not depend upon +structure, and as structure tends to vary, it is capable of being improved. + +Well, I have taken a good deal of pains at various times to prove this, and +I have endeavoured to meet the objections of those who maintain, that the +structural differences between man and the lower animals are of so vast a +character and enormous extent, that even if Mr. Darwin's views are correct, +you cannot imagine this particular modification to take place. It is, in +fact, an easy matter to prove that, so far as structure is concerned, man +differs to no greater extent from the animals which are immediately below +him than these do from other members of the same order. Upon the other +hand, there is no one who estimates more highly than I do the dignity of +human nature, and the width of the gulf in intellectual and moral matters +which lies between man and the whole of the lower creation. + +But I find this very argument brought forward vehemently by some. "You say +that man has proceeded from a modification of some lower animal, and you +take pains to prove that the structural differences which are said to exist +in his brain do not exist at all, and you teach that all functions, +intellectual, moral, and others, are the expression or the result, in the +long run, of structures, and of the molecular forces which they exert." It +is quite true that I do so. + +"Well, but," I am told at once, somewhat triumphantly, "you say in the same +breath that there is a great moral and intellectual chasm between man and +the lower animals. How is this possible when you declare that moral and +intellectual characteristics depend on structure, and yet tell us that +there is no such gulf between the structure of man and that of the lower +animals?" + +I think that objection is based upon a misconception of the real relations +which exist between structure and function, between mechanism and work. +Function is the expression of molecular forces and arrangements no doubt; +but, does it follow from this, that variation in function so depends upon +variation in structure that the former is always exactly proportioned to +the latter? If there is no such relation, if the variation in function +which follows on a variation in structure may be enormously greater than +the variation of the structure, then, you see, the objection falls to the +ground. + +Take a couple of watches--made by the same maker, and as completely alike +as possible; set them upon the table, and the function of each--which is +its rate of going--will be performed in the same manner, and you shall be +able to distinguish no difference between them; but let me take a pair of +pincers, and if my hand is steady enough to do it, let me just lightly +crush together the bearings of the balance-wheel, or force to a slightly +different angle the teeth of the escapement of one of them, and of course +you know the immediate result will be that the watch, so treated, from that +moment will cease to go. But what proportion is there between the +structural alteration and the functional result? Is it not perfectly +obvious that the alteration is of the minutest kind, yet that, slight as it +is, it has produced an infinite difference in the performance of the +functions of these two instruments? + +Well, now, apply that to the present question. What is it that constitutes +and makes man what he is? What is it but his power of language--that +language giving him the means of recording his experience--making every +generation somewhat wiser than its predecessor--more in accordance with the +established order of the universe? + +What is it but this power of speech, of recording experience, which enables +men to be men--looking before and after and, in some dim sense, +understanding the working of this wondrous universe--and which +distinguishes man from the whole of the brute world? I say that this +functional difference is vast, unfathomable, and truly infinite in its +consequences; and I say at the same time, that it may depend upon +structural differences which shall be absolutely inappreciable to us with +our present means of investigation. What is this very speech that we are +talking about? I am speaking to you at this moment, but if you were to +alter, in the minutest degree, the proportion of the nervous forces now +active in the two nerves which supply the muscles of my glottis, I should +become suddenly dumb. The voice is produced only so long as the vocal +chords are parallel; and these are parallel only so long as certain muscles +contract with exact equality; and that again depends on the equality of +action of those two nerves I spoke of. So that a change of the minutest +kind in the structure of one of these nerves, or in the structure of the +part in which it originates, or of the supply of blood to that part, or of +one of the muscles to which it is distributed, might render all of us dumb. +But a race of dumb men, deprived of all communication with those who could +speak, would be little indeed removed from the brutes. And the moral and +intellectual difference between them and ourselves would be practically +infinite, though the naturalist should not be able to find a single shadow +of even specific structural difference. + +But let me dismiss this question now, and, in conclusion, let me say that +you may go away with it as my mature conviction, that Mr. Darwin's work is +the greatest contribution which has been made to biological science since +the publication of the "Regne Animal" of Cuvier, and since that of the +"History of Development," of Von Baer. I believe that if you strip it of +its theoretical part it still remains one of the greatest encyclopaedias of +biological doctrine that any one man ever brought forth; and I believe +that, if you take it as the embodiment of an hypothesis, it is destined to +be the guide of biological and psychological speculation for the next three +or four generations. + +END OF VOL. II + + + + +*** END OF THE PROJECT GUTENBERG EBOOK, DARWINIANA *** + +This file should be named 6919-8.txt or 6919-8.zip + +Project Gutenberg eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the US +unless a copyright notice is included. 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FOR PUBLIC DOMAIN EBOOKS*Ver.02/11/02*END* + diff --git a/6919-8.zip b/6919-8.zip Binary files differnew file mode 100644 index 0000000..1b98715 --- /dev/null +++ b/6919-8.zip diff --git a/6919-h.zip b/6919-h.zip Binary files differnew file mode 100644 index 0000000..b6f019d --- /dev/null +++ b/6919-h.zip diff --git a/6919-h/6919-h.htm b/6919-h/6919-h.htm new file mode 100644 index 0000000..cd6e120 --- /dev/null +++ b/6919-h/6919-h.htm @@ -0,0 +1,12505 @@ +<?xml version="1.0" encoding="iso-8859-1"?> + +<!DOCTYPE html + PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd" > + +<html xmlns="http://www.w3.org/1999/xhtml" lang="en"> + <head> + <title> + Huxley, Thomas Henry (1809-1849): Darwiniana II: collected essays + </title> + <style type="text/css" xml:space="preserve"> + +BODY + { + margin: 0; + border: none; + padding: 1em; + } + +BODY, P, DIV, TD, TH, LI, H1, H2, H3 + { + background: #fff; + color: #000; + } + +.footnotes, .footnotes LI, .footnotes P + { + background: #eee; + color: #000; + } + +</style> + </head> + <body> +<pre xml:space="preserve">The Project Gutenberg EBook of Darwiniana, by Thomas Henry Huxley + +Copyright laws are changing all over the world. 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You can also find out about how to make a +donation to Project Gutenberg, and how to get involved. + + +**Welcome To The World of Free Plain Vanilla Electronic Texts** + +**eBooks Readable By Both Humans and By Computers, Since 1971** + +*****These eBooks Were Prepared By Thousands of Volunteers!***** + + +Title: Darwiniana + +Author: Thomas Henry Huxley + +Release Date: November, 2004 [EBook #6919] +[This file was first posted on February 10, 2003] + +Edition: 10 + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THE PROJECT GUTENBERG EBOOK, DARWINIANA *** + + + + +Branko Collin, Carlo Traverso, Charles Franks and the Distributed +Proofreading Team. + +This file was produced from images generously made available by the +Bibliothèque nationale de France (BnF/Gallica) at +http://gallica.bnf.fr.</pre> + <p> + Thomas Henry Huxley + </p> + <h1> + Collected Essays + </h1> + <p> + (1893-1894) + </p> + <p> + Vol. II + </p> + <p> + Darwiniana + </p> + <p> + (Edition: published in 1893) + </p> + <h2> + Preface + </h2> + <p> + I have entitled this volume "Darwiniana" because the pieces republished in + it either treat of the ancient doctrine of Evolution, rehabilitated and + placed upon a sound scientific foundation, since and in consequence of, + the publication of the "Origin of Species;" or they attempt to meet the + more weighty of the unsparing criticisms with which that great work was + visited for several years after its appearance; or they record the + impression left by the personality of Mr. Darwin on one who had the + privilege and the happiness of enjoying his friendship for some thirty + years; or they endeavour to sum up his work and indicate its enduring + influence on the course of scientific thought. + </p> + <p> + Those who take the trouble to read the first two essays, published in 1859 + and 1860, will, I think, do me the justice to admit that my zeal to secure + fair play for Mr. Darwin, did not drive me into the position of a mere + advocate; and that, while doing justice to the greatness of the argument I + did not fail to indicate its weak points. I have never seen any reason for + departing from the position which I took up in these two essays; and the + assertion which I sometimes meet with nowadays, that I have "recanted" or + changed my opinions about Mr. Darwin's views, is quite unintelligible to + me. + </p> + <p> + As I have said in the seventh essay, the fact of evolution is to my mind + sufficiently evidenced by palaeontology; and I remain of the opinion + expressed in the second, that until selective breeding is definitely + proved to give rise to varieties infertile with one another, the logical + foundation of the theory of natural selection is incomplete. We still + remain very much in the dark about the causes of variation; the apparent + inheritance of acquired characters in some cases; and the struggle for + existence within the organism, which probably lies at the bottom of both + of these phenomena. + </p> + <p> + Some apology is due to the reader for the reproduction of the "Lectures to + Working Men" in their original state. They were taken down in shorthand by + Mr. J. Aldous Mays, who requested me to allow him to print them. I was + very much pressed with work at the time; and, as I could not revise the + reports, which I imagined, moreover, would be of little or no interest to + any but my auditors, I stipulated that a notice should be prefixed to that + effect. This was done; but it did not prevent a considerable diffusion of + the little book in this country and in the United States, nor its + translation into more than one foreign language. Moreover Mr. Darwin often + urged me to revise and expand the lectures into a systematic popular + exposition of the topics of which they treat. I have more than once set + about the task: but the proverb about spoiling a horn and not making a + spoon, is particularly applicable to attempts to remodel a piece of work + which may have served its immediate purpose well enough. + </p> + <p> + So I have reprinted the lectures as they stand, with all their + imperfections on their heads. It would seem that many people must have + found them useful thirty years ago; and, though the sixties appear now to + be reckoned by many of the rising generation as a part of the dark ages, I + am not without some grounds for suspecting that there yet remains a fair + sprinkling even of "philosophic thinkers" to whom it may be a profitable, + perhaps even a novel, task to descend from the heights of speculation and + go over the A B C of the great biological problem as it was set before a + body of shrewd artisans at that remote epoch. + </p> + <p> + T. H. H. + </p> + <p> + Hodeslea, Eastbourne, <i>April 7th, 1893</i>. + </p> + <h2> + Contents + </h2> + <ul> + <li> + I <a href="#c1">The Darwinian Hypothesis</a> [1859] + </li> + <li> + II <a href="#c2">The Origin of Species</a> [1860] + </li> + <li> + III <a href="#c3">Criticism on "The Origin of Species"</a> [1864] + </li> + <li> + IV <a href="#c4">The Genealogy of Animals</a> [1869] + </li> + <li> + V <a href="#c5">Mr. Darwin's Critics</a> [1871] + </li> + <li> + VI <a href="#c6">Evolution in Biology</a> [1878] + </li> + <li> + VII <a href="#c7">The Coming of Age of "The Origin of Species"</a> [1880] + </li> + <li> + VIII <a href="#c8">Charles Darwin</a> [1882] + </li> + <li> + IX <a href="#c9">The Darwin Memorial</a> [1885] + </li> + <li> + X <a href="#c10">Obituary</a> [1888] + </li> + <li> + XI <a href="#c11">Six Lectures to Working Men "On Our Knowledge of the + Causes of the Phenomena of Organic Nature"</a> [1863] + </li> + </ul> + <h2 id="c1"> + I The Darwinian Hypothesis + </h2> + <p> + [1859] + </p> + <p> + The hypothesis of which the present work of Mr. Darwin is but the + preliminary outline, may be stated in his own language as follows:-- + "Species originated by means of natural selection, or through the + preservation of the favoured races in the struggle for life." To render + this thesis intelligible, it is necessary to interpret its terms. In the + first place, what is a species? The question is a simple one, but the + right answer to it is hard to find, even if we appeal to those who should + know most about it. It is all those animals or plants which have descended + from a single pair of parents; it is the smallest distinctly definable + group of living organisms; it is an eternal and immutable entity; it is a + mere abstraction of the human intellect having no existence in nature. + Such are a few of the significations attached to this simple word which + may be culled from authoritative sources; and if, leaving terms and + theoretical subtleties aside, we turn to facts and endeavour to gather a + meaning for ourselves, by studying the things to which, in practice, the + name of species is applied, it profits us little. For practice varies as + much as theory. Let two botanists or two zoologists examine and describe + the productions of a country, and one will pretty certainly disagree with + the other as to the number, limits, and definitions of the species into + which he groups the very same things. In these islands, we are in the + habit of regarding mankind as of one species, but a fortnight's steam will + land us in a country where divines and savants, for once in agreement, vie + with one another in loudness of assertion, if not in cogency of proof, + that men are of different species; and, more particularly, that the + species negro is so distinct from our own that the Ten Commandments have + actually no reference to him. Even in the calm region of entomology, + where, if anywhere in this sinful world, passion and prejudice should fail + to stir the mind, one learned coleopterist will fill ten attractive + volumes with descriptions of species of beetles, nine-tenths of which are + immediately declared by his brother beetle-mongers to be no species at + all. + </p> + <p> + The truth is that the number of distinguishable living creatures almost + surpasses imagination. At least 100,000 such kinds of insects alone have + been described and may be identified in collections, and the number of + separable kinds of living things is under-estimated at half a million. + Seeing that most of these obvious kinds have their accidental varieties, + and that they often shade into others by imperceptible degrees, it may + well be imagined that the task of distinguishing between what is permanent + and what fleeting, what is a species and what a mere variety, is + sufficiently formidable. + </p> + <p> + But is it not possible to apply a test whereby a true species may be known + from a mere variety? Is there no criterion of species? Great authorities + affirm that there is--that the unions of members of the same species are + always fertile, while those of distinct species are either sterile, or + their offspring, called hybrids, are so. It is affirmed not only that this + is an experimental fact, but that it is a provision for the preservation + of the purity of species. Such a criterion as this would be invaluable; + but, unfortunately, not only is it not obvious how to apply it in the + great majority of cases in which its aid is needed, but its general + validity is stoutly denied. The Hon. and Rev. Mr. Herbert, a most + trustworthy authority, not only asserts as the result of his own + observations and experiments that many hybrids are quite as fertile as the + parent species, but he goes so far as to assert that the particular plant + <i>Crinum capense</i> is much more fertile when crossed by a distinct + species than when fertilised by its proper pollen! On the other hand, the + famous Gaertner, though he took the greatest pains to cross the Primrose + and the Cowslip, succeeded only once or twice in several years; and yet it + is a well-established fact that the Primrose and the Cowslip are only + varieties of the same kind of plant. Again, such cases as the following + are well established. The female of species A, if crossed with the male of + species B, is fertile; but, if the female of B is crossed with the male of + A, she remains barren. Facts of this kind destroy the value of the + supposed criterion. + </p> + <p> + If, weary of the endless difficulties involved in the determination of + species, the investigator, contenting himself with the rough practical + distinction of separable kinds, endeavours to study them as they occur in + nature--to ascertain their relations to the conditions which surround + them, their mutual harmonies and discordancies of structure, the bond of + union of their present and their past history, he finds himself, according + to the received notions, in a mighty maze, and with, at most, the dimmest + adumbration of a plan. If he starts with any one clear conviction, it is + that every part of a living creature is cunningly adapted to some special + use in its life. Has not his Paley told him that that seemingly useless + organ, the spleen, is beautifully adjusted as so much packing between the + other organs? And yet, at the outset of his studies, he finds that no + adaptive reason whatsoever can be given for one-half of the peculiarities + of vegetable structure. He also discovers rudimentary teeth, which are + never used, in the gums of the young calf and in those of the foetal + whale; insects which never bite have rudimental jaws, and others which + never fly have rudimental wings; naturally blind creatures have rudimental + eyes; and the halt have rudimentary limbs. So, again, no animal or plant + puts on its perfect form at once, but all have to start from the same + point, however various the course which each has to pursue. Not only men + and horses, and cats and dogs, lobsters and beetles, periwinkles and + mussels, but even the very sponges and animalcules commence their + existence under forms which are essentially undistinguishable; and this is + true of all the infinite variety of plants. Nay, more, all living beings + march, side by side, along the high road of development, and separate the + later the more like they are; like people leaving church, who all go down + the aisle, but having reached the door, some turn into the parsonage, + others go down the village, and others part only in the next parish. A man + in his development runs for a little while parallel with, though never + passing through, the form of the meanest worm, then travels for a space + beside the fish, then journeys along with the bird and the reptile for his + fellow travellers: and only at last, after a brief companionship with the + highest of the four-footed and four-handed world, rises into the dignity + of pure manhood. No competent thinker of the present day dreams of + explaining these indubitable facts by the notion of the existence of + unknown and undiscoverable adaptations to purpose. And we would remind + those who, ignorant of the facts, must be moved by authority, that no one + has asserted the incompetence of the doctrine of final causes, in its + application to physiology and anatomy, more strongly than our own eminent + anatomist, Professor Owen, who, speaking of such cases, says ("On the + Nature of Limbs," pp. 39, 40)--"I think it will be obvious that the + principle of final adaptations fails to satisfy all the conditions of the + problem." + </p> + <p> + But, if the doctrine of final causes will not help us to comprehend the + anomalies of living structure, the principle of adaptation must surely + lead us to understand why certain living beings are found in certain + regions of the world and not in others. The Palm, as we know, will not + grow in our climate, nor the Oak in Greenland. The white bear cannot live + where the tiger thrives, nor vice versâ, and the more the natural + habits of animal and vegetable species are examined, the more do they + seem, on the whole, limited to particular provinces. But when we look into + the facts established by the study of the geographical distribution of + animals and plants it seems utterly hopeless to attempt to understand the + strange and apparently capricious relations which they exhibit. One would + be inclined to suppose à priori that every country must be + naturally peopled by those animals that are fittest to live and thrive in + it. And yet how, on this hypothesis, are we to account for the absence of + cattle in the Pampas of South America, when those parts of the New World + were discovered? It is not that they were unfit for cattle, for millions + of cattle now run wild there; and the like holds good of Australia and New + Zealand. It is a curious circumstance, in fact, that the animals and + plants of the Northern Hemisphere are not only as well adapted to live in + the Southern Hemisphere as its own autochthones, but are, in many cases, + absolutely better adapted, and so overrun and extirpate the aborigines. + Clearly, therefore, the species which naturally inhabit a country are not + necessarily the best adapted to its climate and other conditions. The + inhabitants of islands are often distinct from any other known species of + animal or plants (witness our recent examples from the work of Sir Emerson + Tennent, on Ceylon), and yet they have almost always a sort of general + family resemblance to the animals and plants of the nearest mainland. On + the other hand, there is hardly a species of fish, shell, or crab common + to the opposite sides of the narrow isthmus of Panama. [*] Wherever we + look, then, living nature offers us riddles of difficult solution, if we + suppose that what we see is all that can be known of it. + </p> + <ol class="footnotes"> + <li> + See page 60 <i>Note</i>. + </li> + </ol> + <p> + But our knowledge of life is not confined to the existing world. Whatever + their minor differences, geologists are agreed as to the vast thickness of + the accumulated strata which compose the visible part of our earth, and + the inconceivable immensity of the time the lapse of which they are the + imperfect but the only accessible witnesses. Now, throughout the greater + part of this long series of stratified rocks are scattered, sometimes very + abundantly, multitudes of organic remains, the fossilised exuviæ of + animals and plants which lived and died while the mud of which the rocks + are formed was yet soft ooze, and could receive and bury them. It would be + a great error to suppose that these organic remains were fragmentary + relics. Our museums exhibit fossil shells of immeasurable antiquity, as + perfect as the day they were formed; whole skeletons without a limb + disturbed; nay, the changed flesh, the developing embryos, and even the + very footsteps of primæval organisms. Thus the naturalist finds in + the bowels of the earth species as well defined as, and in some groups of + animals more numerous than, those which breathe the upper air. But, + singularly enough, the majority of these entombed species are wholly + distinct from those that now live. Nor is this unlikeness without its rule + and order. As a broad fact, the further we go back in time the less the + buried species are like existing forms; and, the further apart the sets of + extinct creatures are, the less they are like one another. In other words, + there has been a regular succession of living beings, each younger set, + being in a very broad and general sense, somewhat more like those which + now live. + </p> + <p> + It was once supposed that this succession had been the result of vast + successive catastrophes, destructions, and re-creations en masse; but + catastrophes are now almost eliminated from geological, or at least palæontological + speculation; and it is admitted, on all hands, that the seeming breaks in + the chain of being are not absolute, but only relative to our imperfect + knowledge; that species have replaced species, not in assemblages, but one + by one; and that, if it were possible to have all the phenomena of the + past presented to us, the convenient epochs and formations of the + geologist, though having a certain distinctness, would fade into one + another with limits as undefinable as those of the distinct and yet + separable colours of the solar spectrum. + </p> + <p> + Such is a brief summary of the main truths which have been established + concerning species. Are these truths ultimate and irresolvable facts, or + are their complexities and perplexities the mere expressions of a higher + law? + </p> + <p> + A large number of persons practically assume the former position to be + correct. They believe that the writer of the Pentateuch was empowered and + commissioned to teach us scientific as well as other truth, that the + account we find there of the creation of living things is simply and + literally correct, and that anything which seems to contradict it is, by + the nature of the case, false. All the phenomena which have been detailed + are, on this view, the immediate product of a creative fiat and, + consequently, are out of the domain of science altogether. + </p> + <p> + Whether this view prove ultimately to be true or false, it is, at any + rate, not at present supported by what is commonly regarded as logical + proof, even if it be capable of discussion by reason; and hence we + consider ourselves at liberty to pass it by, and to turn to those views + which profess to rest on a scientific basis only, and therefore admit of + being argued to their consequences. And we do this with the less + hesitation as it so happens that those persons who are practically + conversant with the facts of the case (plainly a considerable advantage) + have always thought fit to range themselves under the latter category. + </p> + <p> + The majority of these competent persons have up to the present time + maintained two positions--the first, that every species is, within certain + defined limits, fixed and incapable of modification; the second, that + every species was originally produced by a distinct creative act. The + second position is obviously incapable of proof or disproof, the direct + operations of the Creator not being subjects of science; and it must + therefore be regarded as a corollary from the first, the truth or + falsehood of which is a matter of evidence. Most persons imagine that the + arguments in favour of it are overwhelming; but to some few minds, and + these, it must be confessed, intellects of no small power and grasp of + knowledge, they have not brought conviction. Among these minds, that of + the famous naturalist Lamarck, who possessed a greater acquaintance with + the lower forms of life than any man of his day, Cuvier not excepted, and + was a good botanist to boot, occupies a prominent place. + </p> + <p> + Two facts appear to have strongly affected the course of thought of this + remarkable man--the one, that finer or stronger links of affinity connect + all living beings with one another, and that thus the highest creature + grades by multitudinous steps into the lowest; the other, that an organ + may be developed in particular directions by exerting itself in particular + ways, and that modifications once induced may be transmitted and become + hereditary. Putting these facts together, Lamarck endeavoured to account + for the first by the operation of the second. Place an animal in new + circumstances, says he, and its needs will be altered; the new needs will + create new desires, and the attempt to gratify such desires will result in + an appropriate modification of the organs exerted. Make a man a + blacksmith, and his brachial muscles will develop in accordance with the + demands made upon them, and in like manner, says Lamarck, "the efforts of + some short-necked bird to catch fish without wetting himself have, with + time and perseverance, given rise to all our herons and long-necked + waders." + </p> + <p> + The Lamarckian hypothesis has long since been justly condemned, and it is + the established practice for every tyro to raise his heel against the + carcase of the dead lion. But it is rarely either wise or instructive to + treat even the errors of a really great man with mere ridicule, and in the + present case the logical form of the doctrine stands on a very different + footing from its substance. + </p> + <p> + If species have really arisen by the operation of natural conditions, we + ought to be able to find those conditions now at work; we ought to be able + to discover in nature some power adequate to modify any given kind of + animal or plant in such a manner as to give rise to another kind, which + would be admitted by naturalists as a distinct species. Lamarck imagined + that he had discovered this vera causa in the admitted facts that some + organs may be modified by exercise; and that modifications, once produced, + are capable of hereditary transmission. It does not seem to have occurred + to him to inquire whether there is any reason to believe that there are + any limits to the amount of modification producible, or to ask how long an + animal is likely to endeavour to gratify an impossible desire. The bird, + in our example, would surely have renounced fish dinners long before it + had produced the least effect on leg or neck. + </p> + <p> + Since Lamarck's time, almost all competent naturalists have left + speculations on the origin of species to such dreamers as the author of + the "Vestiges," by whose well-intentioned efforts the Lamarckian theory + received its final condemnation in the minds of all sound thinkers. + Notwithstanding this silence, however, the transmutation theory, as it has + been called, has been a "skeleton in the closet" to many an honest + zoologist and botanist who had a soul above the mere naming of dried + plants and skins. Surely, has such an one thought, nature is a mighty and + consistent whole, and the providential order established in the world of + life must, if we could only see it rightly, be consistent with that + dominant over the multiform shapes of brute matter. But what is the + history of astronomy, of all the branches of physics, of chemistry, of + medicine, but a narration of the steps by which the human mind has been + compelled, often sorely against its will, to recognise the operation of + secondary causes in events where ignorance beheld an immediate + intervention of a higher power? And when we know that living things are + formed of the same elements as the inorganic world, that they act and + react upon it, bound by a thousand ties of natural piety, is it probable, + nay is it possible, that they, and they alone, should have no order in + their seeming disorder, no unity in their seeming multiplicity, should + suffer no explanation by the discovery of some central and sublime law of + mutual connection? + </p> + <p> + Questions of this kind have assuredly often arisen, but it might have been + long before they received such expression as would have commanded the + respect and attention of the scientific world, had it not been for the + publication of the work which prompted this article. Its author, Mr. + Darwin, inheritor of a once celebrated name, won his spurs in science when + most of those now distinguished were young men, and has for the last + twenty years held a place in the front ranks of British philosophers. + After a circumnavigatory voyage, undertaken solely for the love of his + science, Mr. Darwin published a series of researches which at once + arrested the attention of naturalists and geologists; his generalisations + have since received ample confirmation and now command universal assent, + nor is it questionable that they have had the most important influence on + the progress of science. More recently Mr. Darwin, with a versatility + which is among the rarest of gifts, turned his attention to a most + difficult question of zoology and minute anatomy; and no living naturalist + and anatomist has published a better monograph than that which resulted + from his labours. Such a man, at all events, has not entered the sanctuary + with unwashed hands, and when he lays before us the results of twenty + years' investigation and reflection we must listen even though we be + disposed to strike. But, in reading his work, it must be confessed that + the attention which might at first be dutifully, soon becomes willingly, + given, so clear is the author's thought, so outspoken his conviction, so + honest and fair the candid expression of his doubts. Those who would judge + the book must read it: we shall endeavour only to make its line of + argument and its philosophical position intelligible to the general reader + in our own way. + </p> + <p> + The Baker Street Bazaar has just been exhibiting its familiar annual + spectacle. Straight-backed, small-headed, big-barrelled oxen, as + dissimilar from any wild species as can well be imagined, contended for + attention and praise with sheep of half-a-dozen different breeds and styes + of bloated preposterous pigs, no more like a wild boar or sow than a city + alderman is like an ourang-outang. The cattle show has been, and perhaps + may again be, succeeded by a poultry show, of whose crowing and clucking + prodigies it can only be certainly predicated that they will be very + unlike the aboriginal Phasianus gallus. If the seeker after animal + anomalies is not satisfied, a turn or two in Seven Dials will convince him + that the breeds of pigeons are quite as extraordinary and unlike one + another and their parent stock, while the Horticultural Society will + provide him with any number of corresponding vegetable aberrations from + nature's types. He will learn with no little surprise, too, in the course + of his travels, that the proprietors and producers of these animal and + vegetable anomalies regard them as distinct species, with a firm belief, + the strength of which is exactly proportioned to their ignorance of + scientific biology, and which is the more remarkable as they are all proud + of their skill in originating such "species." + </p> + <p> + On careful inquiry it is found that all these, and the many other + artificial breeds or races of animals and plants, have been produced by + one method. The breeder--and a skilful one must be a person of much + sagacity and natural or acquired perceptive faculty--notes some slight + difference, arising he knows not how, in some individuals of his stock. If + he wish to perpetuate the difference, to form a breed with the peculiarity + in question strongly marked, he selects such male and female individuals + as exhibit the desired character, and breeds from them. Their offspring + are then carefully examined, and those which exhibit the peculiarity the + most distinctly are selected for breeding; and this operation is repeated + until the desired amount of divergence from the primitive stock is + reached. It is then found that by continuing the process of + selection--always breeding, that is, from well-marked forms, and allowing + no impure crosses to interfere--a race may be formed, the tendency of + which to reproduce itself is exceedingly strong; nor is the limit to the + amount of divergence which may be thus produced known; but one thing is + certain, that, if certain breeds of dogs, or of pigeons, or of horses, + were known only in a fossil state, no naturalist would hesitate in + regarding them as distinct species. + </p> + <p> + But in all these cases we have human interference. Without the breeder + there would be no selection, and without the selection no race. Before + admitting the possibility of natural species having originated in any + similar way, it must be proved that there is in Nature some power which + takes the place of man, and performs a selection <i>suâ sponte.</i> + It is the claim of Mr. Darwin that he professes to have discovered the + existence and the <i>modus operandi</i> of this "natural selection," as he + terms it; and, if he be right, the process is perfectly simple and + comprehensible, and irresistibly deducible from very familiar but well + nigh forgotten facts. + </p> + <p> + Who, for instance, has duly reflected upon all the consequences of the + marvellous struggle for existence which is daily and hourly going on among + living beings? Not only does every animal live at the expense of some + other animal or plant, but the very plants are at war. The ground is full + of seeds that cannot rise into seedlings; the seedlings rob one another of + air, light and water, the strongest robber winning the day, and + extinguishing his competitors. Year after year, the wild animals with + which man never interferes are, on the average, neither more nor less + numerous than they were; and yet we know that the annual produce of every + pair is from one to perhaps a million young; so that it is mathematically + certain that, on the average, as many are killed by natural causes as are + born every year, and those only escape which happen to be a little better + fitted to resist destruction than those which die. The individuals of a + species are like the crew of a foundered ship, and none but good swimmers + have a chance of reaching the land. + </p> + <p> + Such being unquestionably the necessary conditions under which living + creatures exist, Mr. Darwin discovers in them the instrument of natural + selection. Suppose that in the midst of this incessant competition some + individuals of a species (A) present accidental variations which happen to + fit them a little better than their fellows for the struggle in which they + are engaged, then the chances are in favour, not only of these individuals + being better nourished than the others, but of their predominating over + their fellows in other ways, and of having a better chance of leaving + offspring, which will of course tend to reproduce the peculiarities of + their parents. Their offspring will, by a parity of reasoning, tend to + predominate over their contemporaries, and there being (suppose) no room + for more than one species such as A, the weaker variety will eventually be + destroyed by the new destructive influence which is thrown into the scale, + and the stronger will take its place. Surrounding conditions remaining + unchanged, the new variety (which we may call B)--supposed, for argument's + sake, to be the best adapted for these conditions which can be got out of + the original stock--will remain unchanged, all accidental deviations from + the type becoming at once extinguished, as less fit for their post than B + itself. The tendency of B to persist will grow with its persistence + through successive generations, and it will acquire all the characters of + a new species. + </p> + <p> + But, on the other hand, if the conditions of life change in any degree, + however slight, B may no longer be that form which is best adapted to + withstand their destructive, and profit by their sustaining, influence; in + which case if it should give rise to a more competent variety (C), this + will take its place and become a new species; and thus, by natural + selection, the species B and C will be successively derived from A. + </p> + <p> + That this most ingenious hypothesis enables us to give a reason for many + apparent anomalies in the distribution of living beings in time and space, + and that it is not contradicted by the main phenomena of life and + organisation appear to us to be unquestionable; and, so far, it must be + admitted to have an immense advantage over any of its predecessors. But it + is quite another matter to affirm absolutely either the truth or falsehood + of Mr. Darwin's views at the present stage of the inquiry. Goethe has an + excellent aphorism defining that state of mind which he calls "Thätige + Skepsis"--active doubt. It is doubt which so loves truth that it neither + dares rest in doubting, nor extinguish itself by unjustified belief; and + we commend this state of mind to students of species, with respect to Mr. + Darwin's or any other hypothesis, as to their origin. The combined + investigations of another twenty years may, perhaps, enable naturalists to + say whether the modifying causes and the selective power, which Mr. Darwin + has satisfactorily shown to exist in Nature, are competent to produce all + the effects he ascribes to them; or whether, on the other hand, he has + been led to over-estimate the value of the principle of natural selection, + as greatly as Lamarck over-estimated his <i>vera causa</i> of modification + by exercise. + </p> + <p> + But there is, at all events, one advantage possessed by the more recent + writer over his predecessor. Mr. Darwin abhors mere speculation as nature + abhors a vacuum. He is as greedy of cases and precedents as any + constitutional lawyer, and all the principles he lays down are capable of + being brought to the test of observation and experiment. The path he bids + us follow professes to be, not a mere airy track, fabricated of ideal + cobwebs, but a solid and broad bridge of facts. If it be so, it will carry + us safely over many a chasm in our knowledge, and lead us to a region free + from the snares of those fascinating but barren virgins, the Final Causes, + against whom a high authority has so justly warned us. "My sons, dig in + the vineyard," were the last words of the old man in the fable: and, + though the sons found no treasure, they made their fortunes by the grapes. + </p> + <h2 id="c2"> + II The Origin Of Species + </h2> + <p> + [1860] + </p> + <p> + Mr. Darwin's long-standing and well-earned scientific eminence probably + renders him indifferent to that social notoriety which passes by the name + of success; but if the calm spirit of the philosopher have not yet wholly + superseded the ambition and the vanity of the carnal man within him, he + must be well satisfied with the results of his venture in publishing the + "Origin of Species." Overflowing the narrow bounds of purely scientific + circles, the "species question" divides with Italy and the Volunteers the + attention of general society. Everybody has read Mr. Darwin's book, or, at + least, has given an opinion upon its merits or demerits; pietists, whether + lay or ecclesiastic, decry it with the mild railing which sounds so + charitable; bigots denounce it with ignorant invective; old ladies of both + sexes consider it a decidedly dangerous book, and even savants, who have + no better mud to throw, quote antiquated writers to show that its author + is no better than an ape himself; while every philosophical thinker hails + it as a veritable Whitworth gun in the armoury of liberalism; and all + competent naturalists and physiologists, whatever their opinions as to the + ultimate fate of the doctrines put forth, acknowledge that the work in + which they are embodied is a solid contribution to knowledge and + inaugurates a new epoch in natural history. + </p> + <p> + Nor has the discussion of the subject been restrained within the limits of + conversation. When the public is eager and interested, reviewers must + minister to its wants; and the genuine <i>littérateur</i> is too + much in the habit of acquiring his knowledge from the book he judges--as + the Abyssinian is said to provide himself with steaks from the ox which + carries him--to be withheld from criticism of a profound scientific work + by the mere want of the requisite preliminary scientific acquirement; + while, on the other hand, the men of science who wish well to the new + views, no less than those who dispute their validity, have naturally + sought opportunities of expressing their opinions. Hence it is not + surprising that almost all the critical journals have noticed Mr. Darwin's + work at greater or less length; and so many disquisitions, of every degree + of excellence, from the poor product of ignorance, too often stimulated by + prejudice, to the fair and thoughtful essay of the candid student of + Nature, have appeared, that it seems an almost hopeless task to attempt to + say anything new upon the question. + </p> + <p> + But it may be doubted if the knowledge and acumen of prejudged scientific + opponents, and the subtlety of orthodox special pleaders, have yet exerted + their full force in mystifying the real issues of the great controversy + which has been set afoot, and whose end is hardly likely to be seen by + this generation; so that, at this eleventh hour, and even failing anything + new, it may be useful to state afresh that which is true, and to put the + fundamental positions advocated by Mr. Darwin in such a form that they may + be grasped by those whose special studies lie in other directions. And the + adoption of this course may be the more advisable, because, + notwithstanding its great deserts, and indeed partly on account of them, + the "Origin of Species" is by no means an easy book to read--if by reading + is implied the full comprehension of an author's meaning. + </p> + <p> + We do not speak jestingly in saying that it is Mr. Darwin's misfortune to + know more about the question he has taken up than any man living. + Personally and practically exercised in zoology, in minute anatomy, in + geology; a student of geographical distribution, not on maps and in + museums only, but by long voyages and laborious collection; having largely + advanced each of these branches of science, and having spent many years in + gathering and sifting materials for his present work, the store of + accurately registered facts upon which the author of the "Origin of + Species" is able to draw at will is prodigious. + </p> + <p> + But this very superabundance of matter must have been embarrassing to a + writer who, for the present, can only put forward an abstract of his + views; and thence it arises, perhaps, that notwithstanding the clearness + of the style, those who attempt fairly to digest the book find much of it + a sort of intellectual pemmican--a mass of facts crushed and pounded into + shape, rather than held together by the ordinary medium of an obvious + logical bond; due attention will, without doubt, discover this bond, but + it is often hard to find. + </p> + <p> + Again, from sheer want of room, much has to be taken for granted which + might readily enough be proved; and hence, while the adept, who can supply + the missing links in the evidence from his own knowledge, discovers fresh + proof of the singular thoroughness with which all difficulties have been + considered and all unjustifiable suppositions avoided, at every reperusal + of Mr. Darwin's pregnant paragraphs, the novice in biology is apt to + complain of the frequency of what he fancies is gratuitous assumption. + </p> + <p> + Thus while it may be doubted if, for some years, any one is likely to be + competent to pronounce judgment on all the issues raised by Mr. Darwin, + there is assuredly abundant room for him, who, assuming the humbler, + though perhaps as useful, office of an interpreter between the "Origin of + Species" and the public, contents himself with endeavouring to point out + the nature of the problems which it discusses; to distinguish between the + ascertained facts and the theoretical views which it contains; and + finally, to show the extent to which the explanation it offers satisfies + the requirements of scientific logic. At any rate, it is this office which + we purpose to undertake in the following pages. + </p> + <p> + It may be safely assumed that our readers have a general conception of the + nature of the objects to which the word "species" is applied; but it has, + perhaps, occurred to a few, even to those who are naturalists <i>ex + professo</i>, to reflect, that, as commonly employed, the term has a + double sense and denotes two very different orders of relations. When we + call a group of animals, or of plants, a species, we may imply thereby, + either that all these animals or plants have some common peculiarity of + form or structure; or, we may mean that they possess some common + functional character. That part of biological science which deals with + form and structure is called Morphology--that which concerns itself with + function, Physiology--so that we may conveniently speak of these two + senses, or aspects, of "species"--the one as morphological, the other as + physiological. Regarded from the former point of view, a species is + nothing more than a kind of animal or plant, which is distinctly definable + from all others, by certain constant, and not merely sexual, morphological + peculiarities. Thus horses form a species, because the group of animals to + which that name is applied is distinguished from all others in the world + by the following constantly associated characters. They have--1, A + vertebral column; 2, Mammae; 3, A placental embryo; 4, Four legs; 5, A + single well-developed toe in each foot provided with a hoof; 6, A bushy + tail; and 7, Callosities on the inner sides of both the fore and the hind + legs. The asses, again, form a distinct species, because, with the same + characters, as far as the fifth in the above list, all asses have tufted + tails, and have callosities only on the inner side of the fore-legs. If + animals were discovered having the general characters of the horse, but + sometimes with callosities only on the fore-legs, and more or less tufted + tails; or animals having the general characters of the ass, but with more + or less bushy tails, and sometimes with callosities on both pairs of legs, + besides being intermediate in other respects--the two species would have + to be merged into one. They could no longer be regarded as morphologically + distinct species, for they would not be distinctly definable one from the + other. + </p> + <p> + However bare and simple this definition of species may appear to be, we + confidently appeal to all practical naturalists, whether zoologists, + botanists, or palaeontologists, to say if, in the vast majority of cases, + they know, or mean to affirm, anything more of the group of animals or + plants they so denominate than what has just been stated. Even the most + decided advocates of the received doctrines respecting species admit this. + </p> + <p> + "I apprehend," says Professor Owen, [*] "that few naturalists nowadays, in + describing and proposing a name for what they call 'a new <i>species</i>,' + use that term to signify what was meant by it twenty or thirty years ago; + that is, an originally distinct creation, maintaining its primitive + distinction by obstructive generative peculiarities. The proposer of the + new species now intends to state no more than he actually knows; as, for + example, that the differences on which he founds the specific character + are constant in individuals of both sexes, so far as observation has + reached; and that they are not due to domestication or to artificially + superinduced external circumstances, or to any outward influence within + his cognizance; that the species is wild, or is such as it appears by + Nature." + </p> + <ol class="footnotes"> + <li> + "On the Osteology of the Chimpanzees and Orangs"; <i>Transactions of the + Zoological Society</i>, 1858. + </li> + </ol> + <p> + If we consider, in fact, that by far the largest proportion of recorded + existing species are known only by the study of their skins, or bones, or + other lifeless exuviae; that we are acquainted with none, or next to none, + of their physiological peculiarities, beyond those which can be deduced + from their structure, or are open to cursory observation; and that we + cannot hope to learn more of any of those extinct forms of life which now + constitute no inconsiderable proportion of the known Flora and Fauna of + the world: it is obvious that the definitions of these species can be only + of a purely structural, or morphological, character. It is probable that + naturalists would have avoided much confusion of ideas if they had more + frequently borne the necessary limitations of our knowledge in mind. But + while it may safely be admitted that we are acquainted with only the + morphological characters of the vast majority of species--the functional + or physiological, peculiarities of a few have been carefully investigated, + and the result of that study forms a large and most interesting portion of + the physiology of reproduction. + </p> + <p> + The student of Nature wonders the more and is astonished the less, the + more conversant he becomes with her operations; but of all the perennial + miracles she offers to his inspection, perhaps the most worthy of + admiration is the development of a plant or of an animal from its embryo. + Examine the recently laid egg of some common animal, such as a salamander + or newt. It is a minute spheroid in which the best microscope will reveal + nothing but a structureless sac, enclosing a glairy fluid, holding + granules in suspension. [*] But strange possibilities lie dormant in that + semi-fluid globule. Let a moderate supply of warmth reach its watery + cradle, and the plastic matter undergoes changes so rapid, yet so steady + and purposelike in their succession, that one can only compare them to + those operated by a skilled modeller upon a formless lump of clay. As with + an invisible trowel, the mass is divided and subdivided into smaller and + smaller portions, until it is reduced to an aggregation of granules not + too large to build withal the finest fabrics of the nascent organism. And, + then, it is as if a delicate finger traced out the line to be occupied by + the spinal column, and moulded the contour of the body; pinching up the + head at one end, the tail at the other, and fashioning flank and limb into + due salamandrine proportions, in so artistic a way, that, after watching + the process hour by hour, one is almost involuntarily possessed by the + notion, that some more subtle aid to vision than an achromatic, would show + the hidden artist, with his plan before him, striving with skilful + manipulation to perfect his work. + </p> + <ol class="footnotes"> + <li> + When this sentence was written, it was generally believed that the + original nucleus of the egg (the germinal vesicle) disappeared. 1893. + </li> + </ol> + <p> + As life advances, and the young amphibian ranges the waters, the terror of + his insect contemporaries, not only are the nutritious particles supplied + by its prey, by the addition of which to its frame, growth takes place, + laid down, each in its proper spot, and in such due proportion to the + rest, as to reproduce the form, the colour, and the size, characteristic + of the parental stock; but even the wonderful powers of reproducing lost + parts possessed by these animals are controlled by the same governing + tendency. Cut off the legs, the tail, the jaws, separately or all + together, and, as Spallanzani showed long ago, these parts not only grow + again, but the redintegrated limb is formed on the same type as those + which were lost. The new jaw, or leg, is a newt's, and never by any + accident more like that of a frog. What is true of the newt is true of + every animal and of every plant; the acorn tends to build itself up again + into a woodland giant such as that from whose twig it fell; the spore of + the humblest lichen reproduces the green or brown incrustation which gave + it birth; and at the other end of the scale of life, the child that + resembled neither the paternal nor the maternal side of the house would be + regarded as a kind of monster. + </p> + <p> + So that the one end to which, in all living beings, the formative impulse + is tending--the one scheme which the Archæus of the old speculators + strives to carry out, seems to be to mould the offspring into the likeness + of the parent. It is the first great law of reproduction, that the + offspring tends to resemble its parent or parents, more closely than + anything else. + </p> + <p> + Science will some day show us how this law is a necessary consequence of + the more general laws which govern matter; but, for the present, more can + hardly be said than that it appears to be in harmony with them. We know + that the phænomena of vitality are not something apart from other + physical phænomena, but one with them; and matter and force are the + two names of the one artist who fashions the living as well as the + lifeless. Hence living bodies should obey the same great laws as other + matter--nor, throughout Nature, is there a law of wider application than + this, that a body impelled by two forces takes the direction of their + resultant. But living bodies may be regarded as nothing but extremely + complex bundles of forces held in a mass of matter, as the complex forces + of a magnet are held in the steel by its coercive force; and, since the + differences of sex are comparatively slight, or, in other words, the sum + of the forces in each has a very similar tendency, their resultant, the + offspring, may reasonably be expected to deviate but little from a course + parallel to either, or to both. + </p> + <p> + Represent the reason of the law to ourselves by what physical metaphor or + analogy we will, however, the great matter is to apprehend its existence + and the importance of the consequences deducible from it. For things which + are like to the same are like to one another; and if, in a great series of + generations, every offspring is like its parent, it follows that all the + offspring and all the parents must be like one another; and that, given an + original parental stock, with the opportunity of undisturbed + multiplication, the law in question necessitates the production, in course + of time, of an indefinitely large group, the whole of the members of which + are at once very similar and are blood relations, having descended from + the same parent, or pair of parents. The proof that all the members of any + given group of animals, or plants, had thus descended, would be ordinarily + considered sufficient to entitle them to the rank of physiological + species, for most physiologists consider species to be definable as "the + offspring of a single primitive stock." + </p> + <p> + But though it is quite true that all those groups we call species <i>may</i>, + according to the known laws of reproduction, have descended from a single + stock, and though it is very likely they really have done so, yet this + conclusion rests on deduction and can hardly hope to establish itself upon + a basis of observation. And the primitiveness of the supposed single + stock, which, after all, is the essential part of the matter, is not only + a hypothesis, but one which has not a shadow of foundation, if by + "primitive" be meant "independent of any other living being." A scientific + definition, of which an unwarrantable hypothesis forms an essential part, + carries its condemnation within itself; but, even supposing such a + definition were, in form, tenable, the physiologist who should attempt to + apply it in Nature would soon find himself involved in great, if not + inextricable, difficulties. As we have said, it is indubitable that + offspring <i>tend</i> to resemble the parental organism, but it is equally + true that the similarity attained never amounts to identity either in form + or in structure. There is always a certain amount of deviation, not only + from the precise characters of a single parent, but when, as in most + animals and many plants, the sexes are lodged in distinct individuals, + from an exact mean between the two parents. And indeed, on general + principles, this slight deviation seems as intelligible as the general + similarity, if we reflect how complex the co-operating "bundles of forces" + are, and how improbable it is that, in any case, their true resultant + shall coincide with any mean between the more obvious characters of the + two parents. Whatever be its cause, however, the co-existence of this + tendency to minor variation with the tendency to general similarity, is of + vast importance in its bearing on the question of the origin of species. + </p> + <p> + As a general rule, the extent to which an offspring differs from its + parent is slight enough; but, occasionally, the amount of difference is + much more strongly marked, and then the divergent offspring receives the + name of a Variety. Multitudes, of what there is every reason to believe + are such varieties, are known, but the origin of very few has been + accurately recorded, and of these we will select two as more especially + illustrative of the main features of variation. The first of them is that + of the "Ancon" or "Otter" sheep, of which a careful account is given by + Colonel David Humphreys, F.R.S., in a letter to Sir Joseph Banks, + published in the "Philosophical Transactions" for 1813. It appears that + one Seth Wright, the proprietor of a farm on the banks of the Charles + River, in Massachusetts, possessed a flock of fifteen ewes and a ram of + the ordinary kind. In the year 1791, one of the ewes presented her owner + with a male lamb, differing, for no assignable reason, from its parents by + a proportionally long body and short bandy legs, whence it was unable to + emulate its relatives in those sportive leaps over the neighbours' fences, + in which they were in the habit of indulging, much to the good farmer's + vexation. + </p> + <p> + The second case is that detailed by a no less unexceptionable authority + than Réaumur, in his "Art de faire éclore les Poulets." A + Maltese couple, named Kelleia, whose hands and feet were constructed upon + the ordinary human model, had born to them a son, Gratio, who possessed + six perfectly movable fingers on each hand, and six toes, not quite so + well formed, on each foot. No cause could be assigned for the appearance + of this unusual variety of the human species. + </p> + <p> + Two circumstances are well worthy of remark in both these cases. In each, + the variety appears to have arisen in full force, and, as it were, <i>per + saltum</i>; a wide and definite difference appearing, at once, between the + Ancon ram and the ordinary sheep; between the six-fingered and six-toed + Gratio Kelleia and ordinary men. In neither case is it possible to point + out any obvious reason for the appearance of the variety. Doubtless there + were determining causes for these as for all other phenomena; but they do + not appear, and we can be tolerably certain that what are ordinarily + understood as changes in physical conditions, as in climate, in food, or + the like, did not take place and had nothing to do with the matter. It was + no case of what is commonly called adaptation to circumstances; but, to + use a conveniently erroneous phrase, the variations arose spontaneously. + The fruitless search after final causes leads their pursuers a long way; + but even those hardy teleologists, who are ready to break through all the + laws of physics in chase of their favourite will-o'-the-wisp, may be + puzzled to discover what purpose could be attained by the stunted legs of + Seth Wright's ram or the hexadactyle members of Gratio Kelleia. + </p> + <p> + Varieties then arise we know not why; and it is more than probable that + the majority of varieties have arisen in this "spontaneous" manner, though + we are, of course, far from denying that they may be traced, in some + cases, to distinct external influences; which are assuredly competent to + alter the character of the tegumentary covering, to change colour, to + increase or diminish the size of muscles, to modify constitution, and, + among plants, to give rise to the metamorphosis of stamens into petals, + and so forth. But however they may have arisen, what especially interests + us at present is, to remark that, once in existence, many varieties obey + the fundamental law of reproduction that like tends to produce like; and + their offspring exemplify it by tending to exhibit the same deviation from + the parental stock as themselves. Indeed, there seems to be, in many + instances, a prepotent influence about a newly-arisen variety which gives + it what one may call an unfair advantage over the normal descendants from + the same stock. This is strikingly exemplified by the case of Gratio + Kelleia, who married a woman with the ordinary pentadactyle extremities, + and had by her four children, Salvator, George, André, and Marie. + Of these children Salvator, the eldest boy, had six fingers and six toes, + like his father; the second and third, also boys, had five fingers and + five toes, like their mother, though the hands and feet of George were + slightly deformed. The last, a girl, had five fingers and five toes, but + the thumbs were slightly deformed. The variety thus reproduced itself + purely in the eldest, while the normal type reproduced itself purely in + the third, and almost purely in the second and last: so that it would + seem, at first, as if the normal type were more powerful than the variety. + But all these children grew up and intermarried with normal wives and + husband, and then, note what took place: Salvator had four children, three + of whom exhibited the hexadactyle members of their grandfather and father, + while the youngest had the pentadactyle limbs of the mother and + grandmother; so that here, notwithstanding a double pentadactyle dilution + of the blood, the hexadactyle variety had the best of it. The same + pre-potency of the variety was still more markedly exemplified in the + progeny of two of the other children, Marie and George. Marie (whose + thumbs only were deformed) gave birth to a boy with six toes, and three + other normally formed children; but George, who was not quite so pure a + pentadactyle, begot, first, two girls, each of whom had six fingers and + toes; then a girl with six fingers on each hand and six toes on the right + foot, but only five toes on the left; and lastly, a boy with only five + fingers and toes. In these instances, therefore, the variety, as it were, + leaped over one generation to reproduce itself in full force in the next. + Finally, the purely pentadactyle André was the father of many + children, not one of whom departed from the normal parental type. + </p> + <p> + If a variation which approaches the nature of a monstrosity can strive + thus forcibly to reproduce itself, it is not wonderful that less aberrant + modifications should tend to be preserved even more strongly; and the + history of the Ancon sheep is, in this respect, particularly instructive. + With the "'cuteness" characteristic of their nation, the neighbours of the + Massachusetts farmer imagined it would be an excellent thing if all his + sheep were imbued with the stay-at-home tendencies enforced by Nature upon + the newly-arrived ram; and they advised Wright to kill the old patriarch + of his fold, and install the Ancon ram in his place. The result justified + their sagacious anticipations, and coincided very nearly with what + occurred to the progeny of Gratio Kelleia. The young lambs were almost + always either pure Ancons, or pure ordinary sheep. [*] But when sufficient + Ancon sheep were obtained to interbreed with one another, it was found + that the offspring was always pure Ancon. Colonel Humphreys, in fact, + states that he was acquainted with only "one questionable case of a + contrary nature." Here, then, is a remarkable and well-established + instance, not only of a very distinct race being established <i>per saltum</i>, + but of that race breeding "true" at once, and showing no mixed forms, even + when crossed with another breed. + </p> + <ol class="footnotes"> + <li> + Colonel Humphreys' statements are exceedingly explicit on this point:--. + "When an Ancon ewe is impregnated by a common ram, the increase + resembles wholly either the ewe or the ram. The increase of the common + ewe impregnated by an Ancon ram follows entirely the one or the other, + without blending any of the distinguishing and essential peculiarities + of both. Frequent instances have happened where common ewes have had + twins by Ancon rams, when one exhibited the complete marks and features + of the ewe, the other of the ram. The contrast has been rendered + singularly striking, when one short-legged and one long-legged lamb, + produced at a birth, have been seen sucking the dam at the same time."--<i>Philosophical + Transactions</i>, 1813, Ft. I. pp. 89, 90. + </li> + </ol> + <p> + By taking care to select Ancons of both sexes, for breeding from, it thus + became easy to establish an extremely well-marked race; so peculiar that, + even when herded with other sheep, it was noted that the Ancons kept + together. And there is every reason to believe that the existence of this + breed might have been indefinitely protracted; but the introduction of the + Merino sheep, which were not only very superior to the Ancons in wool and + meat, but quite as quiet and orderly, led to the complete neglect of the + new breed, so that, in 1813, Colonel Humphreys found it difficult to + obtain the specimen, the skeleton of which was presented to Sir Joseph + Banks. We believe that, for many years, no remnant of it has existed in + the United States. + </p> + <p> + Gratio Kelleia was not the progenitor of a race of six-fingered men, as + Seth Wright's ram became a nation of Ancon sheep, though the tendency of + the variety to perpetuate itself appears to have been fully as strong in + the one case as in the other. And the reason of the difference is not far + to seek. Seth Wright took care not to weaken the Ancon blood by matching + his Ancon ewes with any but males of the same variety, while Gratio + Kelleia's sons were too far removed from the patriarchal times to + intermarry with their sisters; and his grand-children seem not to have + been attracted by their six-fingered cousins. In other words, in the one + example a race was produced, because, for several generations, care was + taken to <i>select</i> both parents of the breeding stock from animals + exhibiting a tendency to vary in the same direction; while, in the other, + no race was evolved, because no such selection was exercised. A race is a + propagated variety; and as, by the laws of reproduction, offspring tend to + assume the parental forms, they will be more likely to propagate a + variation exhibited by both parents than that possessed by only one. + </p> + <p> + There is no organ of the body of an animal which may not, and does not, + occasionally, vary more or less from the normal type; and there is no + variation which may not be transmitted and which, if selectively + transmitted, may not become the foundation of a race. This great truth, + sometimes forgotten by philosophers, has long been familiar to practical + agriculturists and breeders; and upon it rest all the methods of improving + the breeds of domestic animals, which, for the last century, have been + followed with so much success in England. Colour, form, size, texture of + hair or wool, proportions of various parts, strength or weakness of + constitution, tendency to fatten or to remain lean, to give much or little + milk, speed, strength, temper, intelligence, special instincts; there is + not one of these characters the transmission of which is not an every-day + occurrence within the experience of cattle-breeders, stock-farmers, + horse-dealers, and dog and poultry fanciers. Nay, it is only the other day + that an eminent physiologist, Dr. Brown-Séquard, communicated to + the Royal Society his discovery that epilepsy, artificially produced in + guinea-pigs, by a means which he has discovered, is transmitted to their + offspring. [*] + </p> + <ol class="footnotes"> + <li> + Compare Weismann's <i>Essays Upon Heredity</i>, p. 310, <i>et seq</i>. + 1893. + </li> + </ol> + <p> + But a race, once produced, is no more a fixed and immutable entity than + the stock whence it sprang; variations arise among its members, and as + these variations are transmitted like any others, new races may be + developed out of the pre-existing one <i>ad infinitum</i>, or, at least, + within any limit at present determined. Given sufficient time and + sufficiently careful selection, and the multitude of races which may arise + from a common stock is as astonishing as are the extreme structural + differences which they may present. A remarkable example of this is to be + found in the rock-pigeon, which Mr. Darwin has, in our opinion, + satisfactorily demonstrated to be the progenitor of all our domestic + pigeons, of which there are certainly more than a hundred well-marked + races. The most noteworthy of these races are, the four great stocks known + to the "fancy" as tumblers, pouters, carriers, and fantails; birds which + not only differ most singularly in size, colour, and habits, but in the + form of the beak and of the skull; in the proportions of the beak to the + skull; in the number of tail-feathers; in the absolute and relative size + of the feet; in the presence or absence of the uropygial gland; in the + number of vertebræ in the back; in short, in precisely those + characters in which the genera and species of birds differ from one + another. + </p> + <p> + And it is most remarkable and instructive to observe, that none of these + races can be shown to have been originated by the action of changes in + what are commonly called external circumstances, upon the wild + rock-pigeon. On the contrary, from time immemorial pigeon-fanciers have + had essentially similar methods of treating their pets, which have been + housed, fed, protected and cared for in much the same way in all + pigeonries. In fact, there is no case better adapted than that of the + pigeons to refute the doctrine which one sees put forth on high authority, + that "no other characters than those founded on the development of bone + for the attachment of muscles" are capable of variation. In precise + contradiction of this hasty assertion, Mr. Darwin's researches prove that + the skeleton of the wings in domestic pigeons has hardly varied at all + from that of the wild type; while, on the other hand, it is in exactly + those respects, such as the relative length of the beak and skull, the + number of the vertebrae, and the number of the tail-feathers, in which + muscular exertion can have no important influence, that the utmost amount + of variation has taken place. + </p> + <p> + We have said that the following out of the properties exhibited by + physiological species would lead us into difficulties, and at this point + they begin to be obvious; for if, as the result of spontaneous variation + and of selective breeding, the progeny of a common stock may become + separated into groups distinguished from one another by constant, not + sexual, morphological characters, it is clear that the physiological + definition of species is likely to clash with the morphological + definition. No one would hesitate to describe the pouter and the tumbler + as distinct species, if they were found fossil, or if their skins and + skeletons were imported, as those of exotic wild birds commonly are--and + without doubt, if considered alone, they are good and distinct + morphological species. On the other hand, they are not physiological + species, for they are descended from a common stock, the rock-pigeon. + </p> + <p> + Under these circumstances, as it is admitted on all sides that races occur + in Nature, how are we to know whether any apparently distinct animals are + really of different physiological species, or not, seeing that the amount + of morphological difference is no safe guide? Is there any test of a + physiological species? The usual answer of physiologists is in the + affirmative. It is said that such a test is to be found in the phænomena + of hybridisation--in the results of crossing races, as compared with the + results of crossing species. + </p> + <p> + So far as the evidence goes at present, individuals, of what are certainly + known to be mere races produced by selection, however distinct they may + appear to be, not only breed freely together, but the offspring of such + crossed races are perfectly fertile with one another. Thus, the spaniel + and the greyhound, the dray-horse and the Arab, the pouter and the + tumbler, breed together with perfect freedom, and their mongrels, if + matched with other mongrels of the same kind, are equally fertile. + </p> + <p> + On the other hand, there can be no doubt that the individuals of many + natural species are either absolutely infertile if crossed with + individuals of other species, or, if they give rise to hybrid offspring, + the hybrids so produced are infertile when paired together. The horse and + the ass, for instance, if so crossed, give rise to the mule, and there is + no certain evidence of offspring ever having been produced by a male and + female mule. The unions of the rock-pigeon and the ring-pigeon appear to + be equally barren of result. Here, then, says the physiologist, we have a + means of distinguishing any two true species from any two varieties. If a + male and a female, selected from each group, produce offspring, and that + offspring is fertile with others produced in the same way, the groups are + races and not species. If, on the other hand, no result ensues, or if the + offspring are infertile with others produced in the same way, they are + true physiological species. The test would be an admirable one, if, in the + first place, it were always practicable to apply it, and if, in the + second, it always yielded results susceptible of a definite + interpretation. Unfortunately, in the great majority of cases, this + touchstone for species is wholly inapplicable. + </p> + <p> + The constitution of many wild animals is so altered by confinement that + they will not breed even with their own females, so that the negative + results obtained from crosses are of no value; and the antipathy of wild + animals of different species for one another, or even of wild and tame + members of the same species, is ordinarily so great, that it is hopeless + to look for such unions in Nature. The hermaphrodism of most plants, the + difficulty in the way of insuring the absence of their own or the proper + working of other pollen, are obstacles of no less magnitude in applying + the test to them. And, in both animals and plants, is super-added the + further difficulty, that experiments must be continued over a long time + for the purpose of ascertaining the fertility of the mongrel or hybrid + progeny, as well as of the first crosses from which they spring. + </p> + <p> + Not only do these great practical difficulties lie in the way of applying + the hybridisation test, but even when this oracle can be questioned, its + replies are sometimes as doubtful as those of Delphi. For example, cases + are cited by Mr. Darwin, of plants which are more fertile with the pollen + of another species than with their own; and there are others, such as + certain <i>Fuci,</i> the male element of which will fertilise the ovule of + a plant of distinct species, while the males of the latter species are + ineffective with the females of the first. So that, in the last-named + instance, a physiologist, who should cross the two species in one way, + would decide that they were true species; while another, who should cross + them in the reverse way, would, with equal justice, according to the rule, + pronounce them to be mere races. Several plants, which there is great + reason to believe are mere varieties, are almost sterile when crossed; + while both animals and plants, which have always been regarded by + naturalists as of distinct species, turn out, when the test is applied, to + be perfectly fertile. Again, the sterility or fertility of crosses seems + to bear no relation to the structural resemblances or differences of the + members of any two groups. + </p> + <p> + Mr. Darwin has discussed this question with singular ability and + circumspection, and his conclusions are summed up as follows, at page 276 + of his work:-- + </p> + <p> + "First crosses between forms sufficiently distinct to be ranked as + species, and their hybrids, are very generally, but not universally, + sterile. The sterility is of all degrees, and is often so slight that the + two most careful experimentalists who have ever lived have come to + diametrically opposite conclusions in ranking forms by this test. The + sterility is innately variable in individuals of the same species, and is + eminently susceptible of favourable and unfavourable conditions. The + degree of sterility does not strictly follow systematic affinity, but is + governed by several curious and complex laws. It is generally different + and sometimes widely different, in reciprocal crosses between the same two + species. It is not always equal in degree in a first cross, and in the + hybrid produced from this cross. + </p> + <p> + "In the same manner as in grafting trees, the capacity of one species or + variety to take on another is incidental on generally unknown differences + in their vegetative systems; so in crossing, the greater or less facility + of one species to unite with another is incidental on unknown differences + in their reproductive systems. There is no more reason to think that + species have been specially endowed with various degrees of sterility to + prevent them crossing and breeding in Nature, than to think that trees + have been specially endowed with various and somewhat analogous degrees of + difficulty in being grafted together, in order to prevent them becoming + inarched in our forests. + </p> + <p> + "The sterility of first crosses between pure species, which have their + reproductive systems perfect, seems to depend on several circumstances; in + some cases largely on the early death of the embryo. The sterility of + hybrids which have their reproductive systems imperfect, and which have + had this system and their whole organisation disturbed by being compounded + of two distinct species, seems closely allied to that sterility which so + frequently affects pure species when their natural conditions of life have + been disturbed. This view is supported by a parallelism of another kind: + namely, that the crossing of forms, only slightly different, is favourable + to the vigour and fertility of the offspring; and that slight changes in + the conditions of life are apparently favourable to the vigour and + fertility of all organic beings. It is not surprising that the degree of + difficulty in uniting two species, and the degree of sterility of their + hybrid offspring, should generally correspond, though due to distinct + causes; for both depend on the amount of difference of some kind between + the species which are crossed. Nor is it surprising that the facility of + effecting a first cross, the fertility of hybrids produced from it, and + the capacity of being grafted together--though this latter capacity + evidently depends on widely different circumstances--should all run to a + certain extent parallel with the systematic affinity of the forms which + are subjected to experiment; for systematic affinity attempts to express + all kinds of resemblance between all species. + </p> + <p> + "First crosses between forms known to be varieties, or sufficiently alike + to be considered as varieties, and their mongrel offspring, are very + generally, but not quite universally, fertile. Nor is this nearly general + and perfect fertility surprising, when we remember how liable we are to + argue in a circle with respect to varieties in a state of Nature; and when + we remember that the greater number of varieties have been produced under + domestication by the selection of mere external differences, and not of + differences in the reproductive system. In all other respects, excluding + fertility, there is a close general resemblance between hybrids and + mongrels."--Pp. 276-8. + </p> + <p> + We fully agree with the general tenor of this weighty passage; but + forcible as are these arguments, and little as the value of fertility or + infertility as a test of species may be, it must not be forgotten that the + really important fact, so far as the inquiry into the origin of species + goes, is, that there are such things in Nature as groups of animals and of + plants, the members of which are incapable of fertile union with those of + other groups; and that there are such things as hybrids, which are + absolutely sterile when crossed with other hybrids. For, if such phænomena + as these were exhibited by only two of those assemblages of living + objects, to which the name of species (whether it be used in its + physiological or in its morphological sense) is given, it would have to be + accounted for by any theory of the origin of species, and every theory + which could not account for it would be, so far, imperfect. + </p> + <p> + Up to this point, we have been dealing with matters of fact, and the + statements which we have laid before the reader would, to the best of our + knowledge, be admitted to contain a fair exposition of what is at present + known respecting the essential properties of species, by all who have + studied the question. And whatever may be his theoretical views, no + naturalist will probably be disposed to demur to the following summary of + that exposition:-- + </p> + <p> + Living beings, whether animals or plants, are divisible into multitudes of + distinctly definable kinds, which are morphological species. They are also + divisible into groups of individuals, which breed freely together, tending + to reproduce their like, and are physiological species. Normally + resembling their parents, the offspring of members of these species are + still liable to vary; and the variation may be perpetuated by selection, + as a race, which race, in many cases, presents all the characteristics of + a morphological species. But it is not as yet proved that a race ever + exhibits, when crossed with another race of the same species, those phænomena + of hybridisation which are exhibited by many species when crossed with + other species. On the other hand, not only is it not proved that all + species give rise to hybrids infertile <i>inter se</i>, but there is much + reason to believe that, in crossing, species exhibit every gradation from + perfect sterility to perfect fertility. + </p> + <p> + Such are the most essential characteristics of species. Even were man not + one of them--a member of the same system and subject to the same laws--the + question of their origin, their causal connexion, that is, with the other + phænomena of the universe, must have attracted his attention, as + soon as his intelligence had raised itself above the level of his daily + wants. + </p> + <p> + Indeed history relates that such was the case, and has embalmed for us the + speculations upon the origin of living beings, which were among the + earliest products of the dawning intellectual activity of man. In those + early days positive knowledge was not to be had, but the craving after it + needed, at all hazards, to be satisfied, and according to the country, or + the turn of thought, of the speculator, the suggestion that all living + things arose from the mud of the Nile, from a primeval egg, or from some + more anthropomorphic agency, afforded a sufficient resting-place for his + curiosity. The myths of Paganism are as dead as Osiris or Zeus, and the + man who should revive them, in opposition to the knowledge of our time, + would be justly laughed to scorn; but the coeval imaginations current + among the rude inhabitants of Palestine, recorded by writers whose very + name and age are admitted by every scholar to be unknown, have + unfortunately not yet shared their fate, but, even at this day, are + regarded by nine-tenths of the civilised world as the authoritative + standard of fact and the criterion of the justice of scientific + conclusions, in all that relates to the origin of things, and, among them, + of species. In this nineteenth century, as at the dawn of modern physical + science, the cosmogony of the semi-barbarous Hebrew is the incubus of the + philosopher and the opprobrium of the orthodox. Who shall number the + patient and earnest seekers after truth, from the days of Galileo until + now, whose lives have been embittered and their good name blasted by the + mistaken zeal of Bibliolaters? Who shall count the host of weaker men + whose sense of truth has been destroyed in the effort to harmonise + impossibilities--whose life has been wasted in the attempt to force the + generous new wine of Science into the old bottles of Judaism, compelled by + the outcry of the same strong party? + </p> + <p> + It is true that if philosophers have suffered, their cause has been amply + avenged. Extinguished theologians lie about the cradle of every science as + the strangled snakes beside that of Hercules; and history records that + whenever science and orthodoxy have been fairly opposed, the latter has + been forced to retire from the lists, bleeding and crushed if not + annihilated; scotched, if not slain. But orthodoxy is the Bourbon of the + world of thought. It learns not, neither can it forget; and though, at + present, bewildered and afraid to move, it is as willing as ever to insist + that the first chapter of Genesis contains the beginning and the end of + sound science; and to visit, with such petty thunderbolts as its + half-paralysed hands can hurl, those who refuse to degrade Nature to the + level of primitive Judaism. + </p> + <p> + Philosophers, on the other hand, have no such aggressive tendencies. With + eyes fixed on the noble goal to which "per aspera et ardua" they tend, + they may, now and then, be stirred to momentary wrath by the unnecessary + obstacles with which the ignorant, or the malicious, encumber, if they + cannot bar, the difficult path; but why should their souls be deeply + vexed? The majesty of Fact is on their side, and the elemental forces of + Nature are working for them. Not a star comes to the meridian at its + calculated time but testifies to the justice of their methods--their + beliefs are "one with the falling rain and with the growing corn." By + doubt they are established, and open inquiry is their bosom friend. Such + men have no fear of traditions however venerable, and no respect for them + when they become mischievous and obstructive; but they have better than + mere antiquarian business in hand, and if dogmas, which ought to be fossil + but are not, are not forced upon their notice, they are too happy to treat + them as non-existent. + </p> + <p> + * * * * * + </p> + <p> + The hypotheses respecting the origin of species which profess to stand + upon a scientific basis, and, as such, alone demand serious attention, are + of two kinds. The one, the "special creation" hypothesis, presumes every + species to have originated from one or more stocks, these not being the + result of the modification of any other form of living matter--or arising + by natural agencies--but being produced, as such, by a supernatural + creative act. + </p> + <p> + The other, the so-called "transmutation" hypothesis, considers that all + existing species are the result of the modification of pre-existing + species, and those of their predecessors, by agencies similar to those + which at the present day produce varieties and races, and therefore in an + altogether natural way; and it is a probable, though not a necessary + consequence of this hypothesis, that all living beings have arisen from a + single stock. With respect to the origin of this primitive stock, or + stocks, the doctrine of the origin of species is obviously not necessarily + concerned. The transmutation hypothesis, for example, is perfectly + consistent either with the conception of a special creation of the + primitive germ, or with the supposition of its having arisen, as a + modification of inorganic matter, by natural causes. + </p> + <p> + The doctrine of special creation owes its existence very largely to the + supposed necessity of making science accord with the Hebrew cosmogony; but + it is curious to observe that, as the doctrine is at present maintained by + men of science, it is as hopelessly inconsistent with the Hebrew view as + any other hypothesis. + </p> + <p> + If there be any result which has come more clearly out of geological + investigation than another, it is, that the vast series of extinct animals + and plants is not divisible, as it was once supposed to be, into distinct + groups, separated by sharply-marked boundaries. There are no great gulfs + between epochs and formations--no successive periods marked by the + appearance of plants, of water animals, and of land animals, <i>en masse</i>. + Every year adds to the list of links between what the older geologists + supposed to be widely separated epochs: witness the crags linking the + drift with older tertiaries; the Maestricht beds linking the tertiaries + with the chalk; the St. Cassian beds exhibiting an abundant fauna of mixed + mesozoic and palaeozoic types, in rocks of an epoch once supposed to be + eminently poor in life; witness, lastly, the incessant disputes as to + whether a given stratum shall be reckoned devonian or carboniferous, + silurian or devonian, cambrian or silurian. + </p> + <p> + This truth is further illustrated in a most interesting manner by the + impartial and highly competent testimony of M. Pictet, from whose + calculations of what percentage of the genera of animals, existing in any + formation, lived during the preceding formation, it results that in no + case is the proportion less than <i>one-third</i>, or 33 per cent. It is + the triassic formation, or the commencement of the mesozoic epoch, which + has received the smallest inheritance from preceding ages. The other + formations not uncommonly exhibit 60, 80, or even 94 per cent, of genera + in common with those whose remains are imbedded in their predecessor. Not + only is this true, but the subdivisions of each formation exhibit new + species characteristic of, and found only in, them; and, in many cases, as + in the lias for example, the separate beds of these subdivisions are + distinguished by well-marked and peculiar forms of life. A section, a + hundred feet thick, will exhibit, at different heights, a dozen species of + ammonite, none of which passes beyond its particular zone of limestone, or + clay, into the zone below it or into that above it; so that those who + adopt the doctrine of special creation must be prepared to admit, that at + intervals of time, corresponding with the thickness of these beds, the + Creator thought fit to interfere with the natural course of events for the + purpose of making a new ammonite. It is not easy to transplant oneself + into the frame of mind of those who can accept such a conclusion as this, + on any evidence short of absolute demonstration; and it is difficult to + see what is to be gained by so doing, since, as we have said, it is + obvious that such a view of the origin of living beings is utterly opposed + to the Hebrew cosmogony. Deserving no aid from the powerful arm of + Bibliolatry, then, does the received form of the hypothesis of special + creation derive any support from science or sound logic? Assuredly not + much. The arguments brought forward in its favour all take one form: If + species were not supernaturally created, we cannot understand the facts <i>x</i>, + or <i>y</i>, or <i>z</i>; we cannot understand the structure of animals or + plants, unless we suppose they were contrived for special ends; we cannot + understand the structure of the eye, except by supposing it to have been + made to see with; we cannot understand instincts, unless we suppose + animals to have been miraculously endowed with them. + </p> + <p> + As a question of dialectics, it must be admitted that this sort of + reasoning is not very formidable to those who are not to be frightened by + consequences. It is an <i>argumentum ad ignorantiam</i>--take this + explanation or be ignorant. But suppose we prefer to admit our ignorance + rather than adopt a hypothesis at variance with all the teachings of + Nature? Or, suppose for a moment we admit the explanation, and then + seriously ask ourselves how much the wiser are we; what does the + explanation explain? Is it any more than a grandiloquent way of announcing + the fact, that we really know nothing about the matter? A phenomenon is + explained when it is shown to be a case of some general law of Nature; but + the supernatural interposition of the Creator can, by the nature of the + case, exemplify no law, and if species have really arisen in this way, it + is absurd to attempt to discuss their origin. + </p> + <p> + Or, lastly, let us ask ourselves whether any amount of evidence which the + nature of our faculties permits us to attain, can justify us in asserting + that any phenomenon is out of the reach of natural causation. To this end + it is obviously necessary that we should know all the consequences to + which all possible combinations, continued through unlimited time, can + give rise. If we knew these, and found none competent to originate + species, we should have good ground for denying their origin by natural + causation. Till we know them, any hypothesis is better than one which + involves us in such miserable presumption. + </p> + <p> + But the hypothesis of special creation is not only a mere specious mask + for our ignorance; its existence in Biology marks the youth and + imperfection of the science. For what is the history of every science but + the history of the elimination of the notion of creative, or other + interferences, with the natural order of the phænomena which are the + subject-matter of that science? When Astronomy was young "the morning + stars sang together for joy," and the planets were guided in their courses + by celestial hands. Now, the harmony of the stars has resolved itself into + gravitation according to the inverse squares of the distances, and the + orbits of the planets are deducible from the laws of the forces which + allow a schoolboy's stone to break a window. The lightning was the angel + of the Lord; but it has pleased Providence, in these modern times, that + science should make it the humble messenger of man, and we know that every + flash that shimmers about the horizon on a summer's evening is determined + by ascertainable conditions, and that its direction and brightness might, + if our knowledge of these were great enough, have been calculated. + </p> + <p> + The solvency of great mercantile companies rests on the validity of the + laws which have been ascertained to govern the seeming irregularity of + that human life which the moralist bewails as the most uncertain of + things; plague, pestilence, and famine are admitted, by all but fools, to + be the natural result of causes for the most part fully within human + control, and not the unavoidable tortures inflicted by wrathful + Omnipotence upon His helpless handiwork. + </p> + <p> + Harmonious order governing eternally continuous progress--the web and woof + of matter and force interweaving by slow degrees, without a broken thread, + that veil which lies between us and the Infinite--that universe which + alone we know or can know; such is the picture which science draws of the + world, and in proportion as any part of that picture is in unison with the + rest, so may we feel sure that it is rightly painted. Shall Biology alone + remain out of harmony with her sister sciences? + </p> + <p> + Such arguments against the hypothesis of the direct creation of species as + these are plainly enough deducible from general considerations; but there + are, in addition, phenomena exhibited by species themselves, and yet not + so much a part of their very essence as to have required earlier mention, + which are in the highest degree perplexing, if we adopt the popularly + accepted hypothesis. Such are the facts of distribution in space and in + time; the singular phenomena brought to light by the study of development; + the structural relations of species upon which our systems of + classification are founded; the great doctrines of philosophical anatomy, + such as that of homology, or of the community of structural plan exhibited + by large groups of species differing very widely in their habits and + functions. + </p> + <p> + The species of animals which inhabit the sea on opposite sides of the + isthmus of Panama are wholly distinct; [*] the animals and plants which + inhabit islands are commonly distinct from those of the neighbouring + mainlands, and yet have a similarity of aspect. The mammals of the latest + tertiary epoch in the Old and New Worlds belong to the same genera, or + family groups, as those which now inhabit the same great geographical + area. The crocodilian reptiles which existed in the earliest secondary + epoch were similar in general structure to those now living, but exhibit + slight differences in their vertebræ, nasal passages, and one or two + other points. The guinea-pig has teeth which are shed before it is born, + and hence can never subserve the masticatory purpose for which they seem + contrived, and, in like manner, the female dugong has tusks which never + cut the gum. All the members of the same great group run through similar + conditions in their development, and all their parts, in the adult state, + are arranged according to the same plan. Man is more like a gorilla than a + gorilla is like a lemur. Such are a few, taken at random, among the + multitudes of similar facts which modern research has established; but + when the student seeks for an explanation of them from the supporters of + the received hypothesis of the origin of species, the reply he receives + is, in substance, of Oriental simplicity and brevity--"Mashallah! it so + pleases God!" There are different species on opposite sides of the isthmus + of Panama, because they were created different on the two sides. The + pliocene mammals are like the existing ones, because such was the plan of + creation; and we find rudimental organs and similarity of plan, because it + has pleased the Creator to set before Himself a "divine exemplar or + archetype," and to copy it in His works; and somewhat ill, those who hold + this view imply, in some of them. That such verbal hocus-pocus should be + received as science will one day be regarded as evidence of the low state + of intelligence in the nineteenth century, just as we amuse ourselves with + the phraseology about Nature's abhorrence of a vacuum, wherewith + Torricellis compatriots were satisfied to explain the rise of water in a + pump. And be it recollected that this sort of satisfaction works not only + negative but positive ill, by discouraging inquiry, and so depriving man + of the usufruct of one of the most fertile fields of his great patrimony, + Nature. + </p> + <ol class="footnotes"> + <li> + Recent investigations tend to show that this statement is not strictly + accurate.--1870. + </li> + </ol> + <p> + The objections to the doctrine of the origin of species by special + creation which have been detailed, must have occurred, with more or less + force, to the mind of every one who has seriously and independently + considered the subject. It is therefore no wonder that, from time to time, + this hypothesis should have been met by counter hypotheses, all as well, + and some better founded than itself; and it is curious to remark that the + inventors of the opposing views seem to have been led into them as much by + their knowledge of geology, as by their acquaintance with biology. In + fact, when the mind has once admitted the conception of the gradual + production of the present physical state of our globe, by natural causes + operating through long ages of time, it will be little disposed to allow + that living beings have made their appearance in another way, and the + speculations of De Maillet and his successors are the natural complement + of Scilla's demonstration of the true nature of fossils. + </p> + <p> + A contemporary of Newton and of Leibnitz, sharing therefore in the + intellectual activity of the remarkable age which witnessed the birth of + modern physical science, Benoît de Maillet spent a long life as a + consular agent of the French Government in various Mediterranean ports. + For sixteen years, in fact, he held the office of Consul-General in Egypt, + and the wonderful phenomena offered by the valley of the Nile appear to + have strongly impressed his mind, to have directed his attention to all + facts of a similar order which came within his observation, and to have + led him to speculate on the origin of the present condition of our globe + and of its inhabitants. But, with all his ardour for science, De Maillet + seems to have hesitated to publish views which, notwithstanding the + ingenious attempts to reconcile them with the Hebrew hypothesis contained + in the preface to "Telliamed," were hardly likely to be received with + favour by his contemporaries. + </p> + <p> + But a short time had elapsed since more than one of the great anatomists + and physicists of the Italian school had paid dearly for their endeavours + to dissipate some of the prevalent errors; and their illustrious pupil, + Harvey, the founder of modern physiology, had not fared so well, in a + country less oppressed by the benumbing influences of theology, as to + tempt any man to follow his example. Probably not uninfluenced by these + considerations, his Catholic majesty's Consul-General for Egypt kept his + theories to himself throughout a long life, for "Telliamed," the only + scientific work which is known to have proceeded from his pen, was not + printed till 1735, when its author had reached the ripe age of + seventy-nine; and though De Maillet lived three years longer, his book was + not given to the world before 1748. Even then it was anonymous to those + who were not in the secret of the anagrammatic character of its title; and + the preface and dedication are so worded as, in case of necessity, to give + the printer a fair chance of falling back on the excuse that the work was + intended for a mere <i>jeu d'esprit</i>. + </p> + <p> + The speculations of the suppositious Indian sage, though quite as sound as + those of many a "Mosaic Geology," which sells exceedingly well, have no + great value if we consider them by the light of modern science. The waters + are supposed to have originally covered the whole globe; to have deposited + the rocky masses which compose its mountains by processes comparable to + those which are now forming mud, sand, and shingle; and then to have + gradually lowered their level, leaving the spoils of their animal and + vegetable inhabitants embedded in the strata. As the dry land appeared, + certain of the aquatic animals are supposed to have taken to it, and to + have become gradually adapted to terrestrial and aërial modes of + existence. But if we regard the general tenor and style of the reasoning + in relation to the state of knowledge of the day, two circumstances appear + very well worthy of remark. The first, that De Maillet had a notion of the + modifiability of living forms (though without any precise information on + the subject), and how such modifiability might account for the origin of + species; the second, that he very clearly apprehended the great modern + geological doctrine, so strongly insisted upon by Hutton, and so ably and + comprehensively expounded by Lyell, that we must look to existing causes + for the explanation of past geological events. Indeed, the following + passage of the preface, in which De Maillet is supposed to speak of the + Indian philosopher Telliamed, his <i>alter ego,</i> might have been + written by the most philosophical uniformitarian of the present day:-- + </p> + <p> + "Ce qu'il y a d'étonnant, est que pour arriver à ces + connaissances il semble avoir perverti l'ordre naturel, puisqu'au lieu de + s'attacher d'abord à rechercher l'origine de notre globe il a + commence par travailler à s'instruire de la nature. Mais à + l'entendre, ce renversement de l'ordre a été pour lui + l'effet d'un génie favorable qui l'a conduit pas à pas et + comme par la main aux découvertes les plus sublimes. C'est en décomposant + la substance de ce globe par tine anatomie exacte de toutes ses parties + qu'il a premierement appris de quelles matières il était + composé et quels arrangemens ces mêmes matières + observaient entre elles. Ces lumieres jointes à l'esprit de + comparaison toujours nécessaire à quiconque entreprend de + percer les voiles dont la nature aime à se cacher, ont servi de + guide à notre philosophe pour parvenir à des connoissances + plus intéressantes. Par la matière et l'arrangement de ces + compositions il prétend avoir reconnu quelle est la véritable + origine de ce globe que nous habitons, comment et par qui il a été + formé."-Pp. xix. xx. + </p> + <p> + But De Maillet was before his age, and as could hardly fail to happen to + one who speculated on a zoological and botanical question before Linnæus, + and on a physiological problem before Haller, he fell into great errors + here and there; and hence, perhaps, the general neglect of his work. + Robinet's speculations are rather behind, than in advance of, those of De + Maillet; and though Linnæus may have played with the hypothesis of + transmutation, it obtained no serious support until Lamarck adopted it, + and advocated it with great ability in his "Philosophie Zoologique." + </p> + <p> + Impelled towards the hypothesis of the transmutation of species, partly by + his general cosmological and geological views; partly by the conception of + a graduated, though irregularly branching, scale of being, which had + arisen out of his profound study of plants and of the lower forms of + animal life, Lamarck, whose general line of thought often closely + resembles that of De Maillet, made a great advance upon the crude and + merely speculative manner in which that writer deals with the question of + the origin of living beings, by endeavouring to find physical causes + competent to effect that change of one species into another, which De + Maillet had only supposed to occur. And Lamarck conceived that he had + found in Nature such causes, amply sufficient for the purpose in view. It + is a physiological fact, he says, that organs are increased in size by + action, atrophied by inaction; it is another physiological fact that + modifications produced are transmissible to offspring. Change the actions + of an animal, therefore, and you will change its structure, by increasing + the development of the parts newly brought into use and by the diminution + of those less used; but by altering the circumstances which surround it + you will alter its actions, and hence, in the long run, change of + circumstance must produce change of organisation. All the species of + animals, therefore, are, in Lamarck's view, the result of the indirect + action of changes of circumstance, upon those primitive germs which he + considered to have originally arisen, by spontaneous generation, within + the waters of the globe. It is curious, however, that Lamarck should + insist so strongly [*] as he has done, that circumstances never in any + degree directly modify the form or the organisation of animals, but only + operate by changing their wants and consequently their actions; for he + thereby brings upon himself the obvious question, How, then, do plants, + which cannot be said to have wants or actions, become modified? To this he + replies, that they are modified by the changes in their nutritive + processes, which are effected by changing circumstances; and it does not + seem to have occurred to him that such changes might be as well supposed + to take place among animals. + </p> + <ol class="footnotes"> + <li> + See <i>Phil. Zoologique</i>, vol. i. p. 222. et seq. + </li> + </ol> + <p> + When we have said that Lamarck felt that mere speculation was not the way + to arrive at the origin of species, but that it was necessary, in order to + the establishment of any sound theory on the subject, to discover by + observation or otherwise, some <i>vera causa</i>, competent to give rise + to them; that he affirmed the true order of classification to coincide + with the order of their development one from another; that he insisted on + the necessity of allowing sufficient time, very strongly; and that all the + varieties of instinct and reason were traced back by him to the same cause + as that which has given rise to species, we have enumerated his chief + contributions to the advance of the question. On the other hand, from his + ignorance of any power in Nature competent to modify the structure of + animals, except the development of parts, or atrophy of them, in + consequence of a change of needs, Lamarck was led to attach infinitely + greater weight than it deserves to this agency, and the absurdities into + which he was led have met with deserved condemnation. Of the struggle for + existence, on which, as we shall see, Mr. Darwin lays such great stress, + he had no conception; indeed, he doubts whether there really are such + things as extinct species, unless they be such large animals as may have + met their death at the hands of man; and so little does he dream of there + being any other destructive causes at work, that, in discussing the + possible existence of fossil shells, he asks, "Pourquoi d'ailleurs + seroient-ils perdues dès que l'homme n'a pu opérer leur + destruction?" ("Phil. Zool.," vol. i. p. 77.) Of the influence of + selection Lamarck has as little notion, and he makes no use of the + wonderful phenomena which are exhibited by domesticated animals, and + illustrate its powers. The vast influence of Cuvier was employed against + the Lamarckian views, and, as the untenability of some of his conclusions + was easily shown, his doctrines sank under the opprobrium of scientific, + as well as of theological, heterodoxy. Nor have the efforts made of late + years to revive them tended to re-establish their credit in the minds of + sound thinkers acquainted with the facts of the case; indeed it may be + doubted whether Lamarck has not suffered more from his friends than from + his foes. + </p> + <p> + Two years ago, in fact, though we venture to question if even the + strongest supporters of the special creation hypothesis had not, now and + then, an uneasy consciousness that all was not right, their position + seemed more impregnable than ever, if not by its own inherent strength, at + any rate by the obvious failure of all the attempts which had been made to + carry it. On the other hand, however much the few, who thought deeply on + the question of species, might be repelled by the generally received + dogmas, they saw no way of escaping from them save by the adoption of + suppositions so little justified by experiment or by observation as to be + at least equally distasteful. + </p> + <p> + The choice lay between two absurdities and a middle condition of uneasy + scepticism; which last, however unpleasant and unsatisfactory, was + obviously the only justifiable state of mind under the circumstances. + </p> + <p> + Such being the general ferment in the minds of naturalists, it is no + wonder that they mustered strong in the rooms of the Linnæan + Society, on the 1st of July of the year 1858, to hear two papers by + authors living on opposite sides of the globe, working out their results + independently, and yet professing to have discovered one and the same + solution of all the problems connected with species. The one of these + authors was an able naturalist, Mr. Wallace, who had been employed for + some years in studying the productions of the islands of the Indian + Archipelago, and who had forwarded a memoir embodying his views to Mr. + Darwin, for communication to the Linnæan Society. On perusing the + essay, Mr. Darwin was not a little surprised to find that it embodied some + of the leading ideas of a great work which he had been preparing for + twenty years, and parts of which, containing a development of the very + same views, had been perused by his private friends fifteen or sixteen + years before. Perplexed in what manner to do full justice both to his + friend and to himself, Mr. Darwin placed the matter in the hands of Dr. + Hooker and Sir Charles Lyell, by whose advice he communicated a brief + abstract of his own views to the Linnæan Society, at the same time + that Mr. Wallace's paper was read. Of that abstract, the work on the + "Origin of Species" is an enlargement; but a complete statement of Mr. + Darwin's doctrine is looked for in the large and well-illustrated work + which he is said to be preparing for publication. + </p> + <p> + The Darwinian hypothesis has the merit of being eminently simple and + comprehensible in principle, and its essential positions may be stated in + a very few words: all species have been produced by the development of + varieties from common stocks; by the conversion of these, first into + permanent races and then into new species, by the process of <i>natural + selection</i>, which process is essentially identical with that artificial + selection by which man has originated the races of domestic animals--the + <i>struggle for existence</i> taking the place of man, and exerting, in + the case of natural selection, that selective action which he performs in + artificial selection. + </p> + <p> + The evidence brought forward by Mr. Darwin in support of his hypothesis is + of three kinds. First, he endeavours to prove that species may be + originated by selection; secondly, he attempts to show that natural causes + are competent to exert selection; and thirdly, he tries to prove that the + most remarkable and apparently anomalous phænomena exhibited by the + distribution, development, and mutual relations of species, can be shown + to be deducible from the general doctrine of their origin, which he + propounds, combined with the known facts of geological change; and that, + even if all these phænomena are not at present explicable by it, + none are necessarily inconsistent with it. + </p> + <p> + There cannot be a doubt that the method of inquiry which Mr. Darwin has + adopted is not only rigorously in accordance with the canons of scientific + logic, but that it is the only adequate method. Critics exclusively + trained in classics or in mathematics, who have never determined a + scientific fact in their lives by induction from experiment or + observation, prate learnedly about Mr. Darwin's method, which is not + inductive enough, not Baconian enough, forsooth, for them. But even if + practical acquaintance with the process of scientific investigation is + denied them, they may learn, by the perusal of Mr. Mill's admirable + chapter "On the Deductive Method," that there are multitudes of scientific + inquiries in which the method of pure induction helps the investigator but + a very little way. + </p> + <p> + "The mode of investigation," says Mr. Mill, "which, from the proved + inapplicability of direct methods of observation and experiment, remains + to us as the main source of the knowledge we possess, or can acquire, + respecting the conditions and laws of recurrence of the more complex phænomena, + is called, in its most general expression, the deductive method, and + consists of three operations: the first, one of direct induction; the + second, of ratiocination; and the third, of verification." + </p> + <p> + Now, the conditions which have determined the existence of species are not + only exceedingly complex, but, so far as the great majority of them are + concerned, are necessarily beyond our cognisance. But what Mr. Darwin has + attempted to do is in exact accordance with the rule laid down by Mr. + Mill; he has endeavoured to determine certain great facts inductively, by + observation and experiment; he has then reasoned from the data thus + furnished; and lastly, he has tested the validity of his ratiocination by + comparing his deductions with the observed facts of Nature. Inductively, + Mr. Darwin endeavours to prove that species arise in a given way. + Deductively, he desires to show that, if they arise in that way, the facts + of distribution, development, classification, &c., may be accounted + for, <i>i.e.</i> may be deduced from their mode of origin, combined with + admitted changes in physical geography and climate, during an indefinite + period. And this explanation, or coincidence of observed with deduced + facts, is, so far as it extends, a verification of the Darwinian view. + </p> + <p> + There is no fault to be found with Mr. Darwin's method, then; but it is + another question whether he has fulfilled all the conditions imposed by + that method. Is it satisfactorily proved, in fact, that species may be + originated by selection? that there is such a thing as natural selection? + that none of the phænomena exhibited by species are inconsistent + with the origin of species in this way? If these questions can be answered + in the affirmative, Mr. Darwin's view steps out of the rank of hypotheses + into those of proved theories; but, so long as the evidence at present + adduced falls short of enforcing that affirmation, so long, to our minds, + must the new doctrine be content to remain among the former--an extremely + valuable, and in the highest degree probable, doctrine, indeed the only + extant hypothesis which is worth anything in a scientific point of view; + but still a hypothesis, and not yet the theory of species. + </p> + <p> + After much consideration, and with assuredly no bias against Mr. Darwin's + views, it is our clear conviction that, as the evidence stands, it is not + absolutely proven that a group of animals, having all the characters + exhibited by species in Nature, has ever been originated by selection, + whether artificial or natural. Groups having the morphological character + of species--distinct and permanent races in fact--have been so produced + over and over again; but there is no positive evidence, at present, that + any group of animals has, by variation and selective breeding, given rise + to another group which was, even in the least degree, infertile with the + first. Mr. Darwin is perfectly aware of this weak point, and brings + forward a multitude of ingenious and important arguments to diminish the + force of the objection. We admit the value of these arguments to their + fullest extent; nay, we will go so far as to express our belief that + experiments, conducted by a skilful physiologist, would very probably + obtain the desired production of mutually more or less infertile breeds + from a common stock, in a comparatively few years; but still, as the case + stands at present, this "little rift within the lute" is not to be + disguised nor overlooked. + </p> + <p> + In the remainder of Mr. Darwin's argument our own private ingenuity has + not hitherto enabled us to pick holes of any great importance; and judging + by what we hear and read, other adventurers in the same field do not seem + to have been much more fortunate. It has been urged, for instance, that in + his chapters on the struggle for existence and on natural selection, Mr. + Darwin does not so much prove that natural selection does occur, as that + it must occur; but, in fact, no other sort of demonstration is attainable. + A race does not attract our attention in Nature until it has, in all + probability, existed for a considerable time, and then it is too late to + inquire into the conditions of its origin. Again, it is said that there is + no real analogy between the selection which takes place under + domestication, by human influence, and any operation which can be effected + by Nature, for man interferes intelligently. Reduced to its elements, this + argument implies that an effect produced with trouble by an intelligent + agent must, <i>à fortiori,</i> be more troublesome, if not + impossible, to an unintelligent agent. Even putting aside the question + whether Nature, acting as she does according to definite and invariable + laws, can be rightly called an unintelligent agent, such a position as + this is wholly untenable. Mix salt and sand, and it shall puzzle the + wisest of men, with his mere natural appliances, to separate all the + grains of sand from all the grains of salt; but a shower of rain will + effect the same object in ten minutes. And so, while man may find it tax + all his intelligence to separate any variety which arises, and to breed + selectively from it, the destructive agencies incessantly at work in + Nature, if they find one variety to be more soluble in circumstances than + the other, will inevitably, in the long run, eliminate it. + </p> + <p> + A frequent and a just objection to the Lamarckian hypothesis of the + transmutation of species is based upon the absence of transitional forms + between many species. But against the Darwinian hypothesis this argument + has no force. Indeed, one of the most valuable and suggestive parts of Mr. + Darwin's work is that in which he proves, that the frequent absence of + transitions is a necessary consequence of his doctrine, and that the stock + whence two or more species have sprung, need in no respect be intermediate + between these species. If any two species have arisen from a common stock + in the same way as the carrier and the pouter, say, have arisen from the + rock-pigeon, then the common stock of these two species need be no more + intermediate between the two than the rock-pigeon is between the carrier + and pouter. Clearly appreciate the force of this analogy, and all the + arguments against the origin of species by selection, based on the absence + of transitional forms, fall to the ground. And Mr. Darwin's position + might, we think, have been even stronger than it is if he had not + embarrassed himself with the aphorism, "<i>Natura non facit saltum</i>," + which turns up so often in his pages. We believe, as we have said above, + that Nature does make jumps now and then, and a recognition of the fact is + of no small importance in disposing of many minor objections to the + doctrine of transmutation. + </p> + <p> + But we must pause. The discussion of Mr. Darwin's arguments in detail + would lead us far beyond the limits within which we proposed, at starting, + to confine this article. Our object has been attained if we have given an + intelligible, however brief, account of the established facts connected + with species, and of the relation of the explanation of those facts + offered by Mr. Darwin to the theoretical views held by his predecessors + and his contemporaries, and, above all, to the requirements of scientific + logic. We have ventured to point out that it does not, as yet, satisfy all + those requirements; but we do not hesitate to assert that it is as + superior to any preceding or contemporary hypothesis, in the extent of + observational and experimental basis on which it rests, in its rigorously + scientific method, and in its power of explaining biological phenomena, as + was the hypothesis of Copernicus to the speculations of Ptolemy. But the + planetary orbits turned out to be not quite circular after all, and, grand + as was the service Copernicus rendered to science, Kepler and Newton had + to come after him. What if the orbit of Darwinism should be a little too + circular? What if species should offer residual phænomena, here and + there, not explicable by natural selection? Twenty years hence naturalists + may be in a position to say whether this is, or is not, the case; but in + either event they will owe the author of "The Origin of Species" an + immense debt of gratitude. We should leave a very wrong impression on the + reader's mind if we permitted him to suppose that the value of that work + depends wholly on the ultimate justification of the theoretical views + which it contains. On the contrary, if they were disproved to-morrow, the + book would still be the best of its kind--the most compendious statement + of well-sifted facts bearing on the doctrine of species that has ever + appeared. The chapters on Variation, on the Struggle for Existence, on + Instinct, on Hybridism, on the Imperfection of the Geological Record, on + Geographical Distribution, have not only no equals, but, so far as our + knowledge goes, no competitors, within the range of biological literature. + And viewed as a whole, we do not believe that, since the publication of + Von Baer's "Researches on Development," thirty years ago, any work has + appeared calculated to exert so large an influence, not only on the future + of Biology, but in extending the domination of Science over regions of + thought into which she has, as yet, hardly penetrated. + </p> + <h2 id="c3"> + III Criticisms On "The Origin Of Species" + </h2> + <p> + [1864] + </p> + <p> + 1. UEBER DIE DARWIN'SCHE SCHÖPFUNGSTHEORIE; EIN VORTRAG, Von A. KÖLLIKER. + Leipzig, 1864. + </p> + <p> + 2. EXAMINATION DU LIVRE DE M. DARWIN SUR L'ORIGINE DES ESPÈCES. Par + P. FLOURENS. Paris, 1864. + </p> + <p> + In the course of the present year several foreign commentaries upon Mr. + Darwin's great work have made their appearance. Those who have perused + that remarkable chapter of the "Antiquity of Man," in which Sir Charles + Lyell draws a parallel between the development of species and that of + languages, will be glad to hear that one of the most eminent philologers + of Germany, Professor Schleicher, has, independently, published a most + instructive and philosophical pamphlet (an excellent notice of which is to + be found in the <i>Reader</i>, for February 27th of this year) supporting + similar views with all the weight of his special knowledge and established + authority as a linguist. Professor Haeckel, to whom Schleicher addresses + himself, previously took occasion, in his splendid monograph on the <i>Radiolaria</i>, + [*] to express his high appreciation of, and general concordance with, Mr. + Darwin's views. + </p> + <ol class="footnotes"> + <li> + <i>Die Radiolarien: eine Monographie</i>, p. 231. + </li> + </ol> + <p> + But the most elaborate criticisms of the "Origin of Species" which have + appeared are two works of very widely different merit, the one by + Professor Kölliker, the well-known anatomist and histologist of Würzburg; + the other by M. Flourens, Perpetual Secretary of the French Academy of + Sciences. + </p> + <p> + Professor Kölliker's critical essay "Upon the Darwinian Theory" is, + like all that proceeds from the pen of that thoughtful and accomplished + writer, worthy of the most careful consideration. It comprises a brief but + clear sketch of Darwin's views, followed by an enumeration of the leading + difficulties in the way of their acceptance; difficulties which would + appear to be insurmountable to Professor Kölliker, inasmuch as he + proposes to replace Mr. Darwin's Theory by one which he terms the "Theory + of Heterogeneous Generation." We shall proceed to consider first the + destructive, and secondly, the constructive portion of the essay. + </p> + <p> + We regret to find ourselves compelled to dissent very widely from many of + Professor Kölliker's remarks; and from none more thoroughly than from + those in which he seeks to define what we may term the philosophical + position of Darwinism. + </p> + <p> + "Darwin," says Professor Kölliker, "is, in the fullest sense of the + word, a Teleologist. He says quite distinctly (First Edition, pp. 199, + 200) that every particular in the structure of an animal has been created + for its benefit, and he regards the whole series of animal forms only from + this point of view." + </p> + <p> + And again: + </p> + <p> + "7. The teleological general conception adopted by Darwin is a mistaken + one. + </p> + <p> + "Varieties arise irrespectively of the notion of purpose, or of utility, + according to general laws of Nature, and may be either useful, or hurtful, + or indifferent. + </p> + <p> + "The assumption that an organism exists only on account of some definite + end in view, and represents something more than the incorporation of a + general idea, or law, implies a one-sided conception of the universe. + Assuredly, every organ has, and every organism fulfils, its end, but its + purpose is not the condition of its existence. Every organism is also + sufficiently perfect for the purpose it serves, and in that, at least, it + is useless to seek for a cause of its improvement." + </p> + <p> + It is singular how differently one and the same book will impress + different minds. That which struck the present writer most forcibly on his + first perusal of the "Origin of Species" was the conviction that + Teleology, as commonly understood, had received its deathblow at Mr. + Darwin's hands. For the teleological argument runs thus: an organ or + organism (A) is precisely fitted to perform a function or purpose (B); + therefore it was specially constructed to perform that function. In + Paley's famous illustration, the adaptation of all the parts of the watch + to the function, or purpose, of showing the time, is held to be evidence + that the watch was specially contrived to that end; on the ground, that + the only cause we know of, competent to produce such an effect as a watch + which shall keep time, is a contriving intelligence adapting the means + directly to that end. + </p> + <p> + Suppose, however, that any one had been able to show that the watch had + not been made directly by any person, but that it was the result of the + modification of another watch which kept time but poorly; and that this + again had proceeded from a structure which could hardly be called a watch + at all--seeing that it had no figures on the dial and the hands were + rudimentary; and that going back and back in time we came at last to a + revolving barrel as the earliest traceable rudiment of the whole fabric. + And imagine that it had been possible to show that all these changes had + resulted, first, from a tendency of the structure to vary indefinitely; + and secondly, from something in the surrounding world which helped all + variations in the direction of an accurate time-keeper, and checked all + those in other directions; then it is obvious that the force of Paley's + argument would be gone. For it would be demonstrated that an apparatus + thoroughly well adapted to a particular purpose might be the result of a + method of trial and error worked by unintelligent agents, as well as of + the direct application of the means appropriate to that end, by an + intelligent agent. + </p> + <p> + Now it appears to us that what we have here, for illustration's sake, + supposed to be done with the watch, is exactly what the establishment of + Darwin's Theory will do for the organic world. For the notion that every + organism has been created as it is and launched straight at a purpose, Mr. + Darwin substitutes the conception of something which may fairly be termed + a method of trial and error. Organisms vary incessantly; of these + variations the few meet with surrounding conditions which suit them and + thrive; the many are unsuited and become extinguished. + </p> + <p> + According to Teleology, each organism is like a rifle bullet fired + straight at a mark; according to Darwin, organisms are like grapeshot of + which one hits something and the rest fall wide. + </p> + <p> + For the teleologist an organism exists because it was made for the + conditions in which it is found; for the Darwinian an organism exists + because, out of many of its kind, it is the only one which has been able + to persist in the conditions in which it is found. + </p> + <p> + Teleology implies that the organs of every organism are perfect and cannot + be improved; the Darwinian theory simply affirms that they work well + enough to enable the organism to hold its own against such competitors as + it has met with, but admits the possibility of indefinite improvement. But + an example may bring into clearer light the profound opposition between + the ordinary teleological, and the Darwinian, conception. + </p> + <p> + Cats catch mice, small birds and the like, very well. Teleology tells us + that they do so because they were expressly constructed for so doing--that + they are perfect mousing apparatuses, so perfect and so delicately + adjusted that no one of their organs could be altered, without the change + involving the alteration of all the rest. Darwinism affirms on the + contrary, that there was no express construction concerned in the matter; + but that among the multitudinous variations of the Feline stock, many of + which died out from want of power to resist opposing influences, some, the + cats, were better fitted to catch mice than others, whence they throve and + persisted, in proportion to the advantage over their fellows thus offered + to them. + </p> + <p> + Far from imagining that cats exist <i>in order</i> to catch mice well, + Darwinism supposes that cats exist because they catch mice well--mousing + being not the end, but the condition, of their existence. And if the cat + type has long persisted as we know it, the interpretation of the fact upon + Darwinian principles would be, not that the cats have remained invariable, + but that such varieties as have incessantly occurred have been, on the + whole, less fitted to get on in the world than the existing stock. + </p> + <p> + If we apprehend the spirit of the "Origin of Species" rightly, then, + nothing can be more entirely and absolutely opposed to Teleology, as it is + commonly understood, than the Darwinian Theory. So far from being a + "Teleologist in the fullest sense of the word," we should deny that he is + a Teleologist in the ordinary sense at all; and we should say that, apart + from his merits as a naturalist, he has rendered a most remarkable service + to philosophical thought by enabling the student of Nature to recognise, + to their fullest extent, those adaptations to purpose which are so + striking in the organic world, and which Teleology has done good service + in keeping before our minds, without being false to the fundamental + principles of a scientific conception of the universe. The apparently + diverging teachings of the Teleologist and of the Morphologist are + reconciled by the Darwinian hypothesis. + </p> + <p> + But leaving our own impressions of the "Origin of Species," and turning to + those passages especially cited by Professor Kölliker, we cannot + admit that they bear the interpretation he puts upon them. Darwin, if we + read him rightly, does <i>not</i> affirm that every detail in the + structure of an animal has been created for its benefit. His words are (p. + 199):-- + </p> + <p> + "The foregoing remarks lead me to say a few words on the protest lately + made by some naturalists against the utilitarian doctrine that every + detail of structure has been produced for the good of its possessor. They + believe that very many structures have been created for beauty in the eyes + of man, or for mere variety. This doctrine, if true, would be absolutely + fatal to my theory--yet I fully admit that many structures are of no + direct use to their possessor." + </p> + <p> + And after sundry illustrations and qualifications, he concludes (p. + 200):-- + </p> + <p> + "Hence every detail of structure in every living creature (making some + little allowance for the direct action of physical conditions) may be + viewed either as having been of special use to some ancestral form, or as + being now of special use to the descendants of this form--either directly, + or indirectly, through the complex laws of growth." + </p> + <p> + But it is one thing to say, Darwinically, that every detail observed in an + animal's structure is of use to it, or has been of use to its ancestors; + and quite another to affirm, teleologically, that every detail of an + animal's structure has been created for its benefit. On the former + hypothesis, for example, the teeth of the foetal <i>Baltæna</i> have + a meaning; on the latter, none. So far as we are aware, there is not a + phrase in the "Origin of Species" inconsistent with Professor Kölliker's + position, that "varieties arise irrespectively of the notion of purpose, + or of utility, according to general laws of Nature, and may be either + useful, or hurtful, or indifferent." + </p> + <p> + On the contrary, Mr. Darwin writes (Summary of Chap. V.):-- + </p> + <p> + "Our ignorance of the laws of variation is profound. Not in one case out + of a hundred can we pretend to assign any reason why this or that part + varies more or less from the same part in the parents... The external + conditions of life, as climate and food, &c., seem to have induced + some slight modifications. Habit, in producing constitutional differences, + and use, in strengthening, and disuse, in weakening and diminishing + organs, seem to have been more potent in their effects." + </p> + <p> + And finally, as if to prevent all possible misconception, Mr. Darwin + concludes his Chapter on Variation with these pregnant words:-- + </p> + <p> + "Whatever the cause may be of each slight difference in the offspring from + their parents--and a cause for each must exist--it is the steady + accumulation, through natural selection of such differences, when + beneficial to the individual, that gives rise to all the more important + modifications of structure, by which the innumerable beings on the face of + the earth are enabled to struggle with each other, and the best adapted to + survive." + </p> + <p> + We have dwelt at length upon, this subject, because of its great general + importance, and because we believe that Professor Kölliker's + criticisms on this head are based upon a misapprehension of Mr. Darwin's + views--substantially they appear to us to coincide with his own. The other + objections which Professor Kölliker enumerates and discusses are the + following: [*]-- + </p> + <ol class="footnotes"> + <li> + Space will not allow us to give Professor Kölliker's arguments in + detail; our readers will find a full and accurate version of them in the + <i>Reader</i> for August 13th and 20th, 1864. + </li> + </ol> + <p> + "1. No transitional forms between existing species are known; and known + varieties, whether selected or spontaneous, never go so far as to + establish new species." + </p> + <p> + To this Professor Kölliker appears to attach some weight. He makes + the suggestion that the short-faced tumbler pigeon may be a pathological + product. + </p> + <p> + "2. No transitional forms of animals are met with among the organic + remains of earlier epochs." + </p> + <p> + Upon this, Professor Kölliker remarks that the absence of + transitional forms in the fossil world, though not necessarily fatal to + Darwin's views, weakens his case. + </p> + <p> + "3. The struggle for existence does not take place." + </p> + <p> + To this objection, urged by Pelzeln, Kölliker, very justly, attaches + no weight. + </p> + <p> + "4. A tendency of organisms to give rise to useful varieties, and a + natural selection, do not exist. + </p> + <p> + "The varieties which are found arise in consequence of manifold external + influences, and it is not obvious why they all, or partially, should be + particularly useful. Each animal suffices for its own ends, is perfect of + its kind, and needs no further development. Should, however, a variety be + useful and even maintain itself, there is no obvious reason why it should + change any further. The whole conception of the imperfection of organisms + and the necessity of their becoming perfected is plainly the weakest side + of Darwin's Theory, and a <i>pis aller</i> (Nothbehelf) because Darwin + could think of no other principle by which to explain the metamorphoses + which, as I also believe, have occurred." + </p> + <p> + Here again we must venture to dissent completely from Professor Kölliker's + conception of Mr. Darwin's hypothesis. It appears to us to be one of the + many peculiar merits of that hypothesis that it involves no belief in a + necessary and continual progress of organisms. + </p> + <p> + Again, Mr. Darwin, if we read him aright, assumes no special tendency of + organisms to give rise to useful varieties, and knows nothing of needs of + development, or necessity of perfection. What he says is, in substance: + All organisms vary. It is in the highest degree improbable that any given + variety should have exactly the same relations to surrounding conditions + as the parent stock. In that case it is either better fitted (when the + variation may be called useful), or worse fitted, to cope with them. If + better, it will tend to supplant the parent stock; if worse, it will tend + to be extinguished by the parent stock. + </p> + <p> + If (as is hardly conceivable) the new variety is so perfectly adapted to + the conditions that no improvement upon it is possible,--it will persist, + because, though it does not cease to vary, the varieties will be inferior + to itself. + </p> + <p> + If, as is more probable, the new variety is by no means perfectly adapted + to its conditions, but only fairly well adapted to them, it will persist, + so long as none of the varieties which it throws off are better adapted + than itself. + </p> + <p> + On the other hand, as soon as it varies in a useful way, <i>i.e.</i> when + the variation is such as to adapt it more perfectly to its conditions, the + fresh variety will tend to supplant the former. + </p> + <p> + So far from a gradual progress towards perfection forming any necessary + part of the Darwinian creed, it appears to us that it is perfectly + consistent with indefinite persistence in one state, or with a gradual + retrogression. Suppose, for example, a return of the glacial epoch and a + spread of polar climatal conditions over the whole globe. The operation of + natural selection under these circumstances would tend, on the whole, to + the weeding out of the higher organisms and the cherishing of the lower + forms of life. Cryptogamic vegetation would have the advantage over + Phanerogamic; <i>Hydrozoa</i> over Corals; <i>Crustacea</i> over <i>Insecta</i>, + and <i>Amphipoda</i> and <i>Isopoda</i> over the higher <i>Crustacea;</i> + Cetaceans and Seals over the <i>Primates</i>; the civilisation of the + Esquimaux over that of the European. + </p> + <p> + "5. Pelzeln has also objected that if the later organisms have proceeded + from the earlier, the whole developmental series, from the simplest to the + highest, could not now exist; in such a case the simpler organisms must + have disappeared." + </p> + <p> + To this Professor Kölliker replies, with perfect justice, that the + conclusion drawn by Pelzeln does not really follow from Darwin's premises, + and that, if we take the facts of Paleontology as they stand, they rather + support than oppose Darwin's theory. + </p> + <p> + "6. Great weight must be attached to the objection brought forward by + Huxley, otherwise a warm supporter of Darwin's hypothesis, that we know of + no varieties which are sterile with one another, as is the rule among + sharply distinguished animal forms. + </p> + <p> + "If Darwin is right, it must be demonstrated that forms may be produced by + selection, which, like the present sharply distinguished animal forms, are + infertile, when coupled with one another, and this has not been done." + </p> + <p> + The weight of this objection is obvious; but our ignorance of the + conditions of fertility and sterility, the want of carefully conducted + experiments extending over long series of years, and the strange anomalies + presented by the results of the cross-fertilisation of many plants, should + all, as Mr. Darwin has urged, be taken into account in considering it. + </p> + <p> + The seventh objection is that we have already discussed (<i>supra</i> p. + 82). + </p> + <p> + The eighth and last stands as follows:-- + </p> + <p> + "8. The developmental theory of Darwin is not needed to enable us to + understand the regular harmonious progress of the complete series of + organic forms from the simpler to the more perfect. + </p> + <p> + "The existence of general laws of Nature explains this harmony, even if we + assume that all beings have arisen separately and independent of one + another. Darwin forgets that inorganic nature, in which there can be no + thought of genetic connexion of forms, exhibits the same regular plan, the + same harmony, as the organic world; and that, to cite only one example, + there is as much a natural system of minerals as of plants and animals." + </p> + <p> + We do not feel quite sure that we seize Professor Kölliker's meaning + here, but he appears to suggest that the observation of the general order + and harmony which pervade inorganic nature, would lead us to anticipate a + similar order and harmony in the organic world. And this is no doubt true, + but it by no means follows that the particular order and harmony observed + among them should be that which we see. Surely the stripes of dun horses, + and the teeth of the <i>foetal</i> <i>Balæna</i>, are not explained + by the "existence of General laws of Nature." Mr. Darwin endeavours to + explain the exact order of organic nature which exists; not the mere fact + that there is some order. + </p> + <p> + And with regard to the existence of a natural system of minerals; the + obvious reply is that there may be a natural classification of any + objects--of stones on a sea-beach, or of works of art; a natural + classification being simply an assemblage of objects in groups, so as to + express their most important and fundamental resemblances and differences. + No doubt Mr. Darwin believes that those resemblances and differences upon + which our natural systems or classifications of animals and plants are + based, are resemblances and differences which have been produced + genetically, but we can discover no reason for supposing that he denies + the existence of natural classifications of other kinds. + </p> + <p> + And, after all, is it quite so certain that a genetic relation may not + underlie the classification of minerals? The inorganic world has not + always been what we see it. It has certainly had its metamorphoses, and, + very probably, a long "Entwickelungsgeschichte" out of a nebular blastema. + Who knows how far that amount of likeness among sets of minerals, in + virtue of which they are now grouped into families and orders, may not be + the expression of the common conditions to which that particular patch of + nebulous fog, which may have been constituted by their atoms, and of which + they may be, in the strictest sense, the descendants, was subjected? + </p> + <p> + It will be obvious from what has preceded, that we do not agree with + Professor Kölliker in thinking the objections which he brings forward + so weighty as to be fatal to Darwin's view. But even if the case were + otherwise, we should be unable to accept the "Theory of Heterogeneous + Generation" which is offered as a substitute. That theory is thus + stated:-- + </p> + <p> + "The fundamental conception of this hypothesis is, that, under the + influence of a general law of development, the germs of organisms produce + others different from themselves. This might happen (1) by the fecundated + ova passing, in the course of their development, under particular + circumstances, into higher forms; (2) by the primitive and later organisms + producing other organisms without fecundation, out of germs or eggs + (Parthenogenesis)." + </p> + <p> + In favour of this hypothesis, Professor Kölliker adduces the + well-known facts of Agamogenesis, or "alternate generation"; the extreme + dissimilarity of the males and females of many animals; and of the males, + females, and neuters of those insects which live in colonies: and he + defines its relations to the Darwinian theory as follows:-- + </p> + <p> + "It is obvious that my hypothesis is apparently very similar to Darwin's, + inasmuch as I also consider that the various forms of animals have + proceeded directly from one another. My hypothesis of the creation of + organisms by heterogeneous generation, however, is distinguished very + essentially from Darwin's by the entire absence of the principle of useful + variations and their natural selection: and my fundamental conception is + this, that a great plan of development lies at the foundation of the + origin of the whole organic world, impelling the simpler forms to more and + more complex developments. How this law operates, what influences + determine the development of the eggs and germs, and impel them to assume + constantly new forms, I naturally cannot pretend to say; but I can at + least adduce the great analogy of the alternation of generations. If a <i>Bipinnaria</i>, + a <i>Brachiolaria</i>, a <i>Pluteus</i>, is competent to produce the + Echinoderm, which is so widely different from it; if a hydroid polype can + produce the higher Medusa; if the vermiform Trematode 'nurse' can develop + within itself the very unlike <i>Cercaria</i>, it will not appear + impossible that the egg, or ciliated embryo, of a sponge, for once, under + special conditions, might become a hydroid polype, or the embryo of a + Medusa, an Echinoderm." + </p> + <p> + It is obvious, from, these extracts, that Professor Kölliker's + hypothesis is based upon the supposed existence of a close analogy between + the phænomena of Agamogenesis and the production of new species from + pre-existing ones. But is the analogy a real one? We think that it is not, + and, by the hypothesis cannot be. + </p> + <p> + For what are the phænomena of Agamogenesis, stated generally? An + impregnated egg develops into a sexless form, A; this gives rise, + non-sexually, to a second form or forms, B, more or less different from A. + B may multiply non-sexually again; in the simpler cases, however, it does + not, but, acquiring sexual characters, produces impregnated eggs from + whence A, once more, arises. + </p> + <p> + No case of Agamogenesis is known in which <i>when A differs widely from B</i>, + it is itself capable of sexual propagation. No case whatever is known in + which the progeny of B, by sexual generation, is other than a reproduction + of A. + </p> + <p> + But if this be a true statement of the nature of the process of + Agamogenesis, how can it enable us to comprehend the production of new + species from already existing ones? Let us suppose Hyænas to have + preceded Dogs, and to have produced the latter in this way. Then the Hyæna + will represent A, and the Dog, B. The first difficulty that presents + itself is that the Hyæna must be non-sexual, or the process will be + wholly without analogy in the world of Agamogenesis. But passing over this + difficulty, and supposing a male and female Dog to be produced at the same + time from the Hyæna stock, the progeny of the pair, if the analogy + of the simpler kinds of Agamogenesis [*] is to be followed, should be a + litter, not of puppies, but of young Hyænas. For the Agamogenetic + series is always, as we have seen, A:B:A:B, &c.; whereas, for the + production of a new species, the series must be A:B:B:B, &c. The + production of new species, or genera, is the extreme permanent divergence + from the primitive stock. All known Agamogenetic processes, on the other + hand, end in a complete return to the primitive stock. How then is the + production of new species to be rendered intelligible by the analogy of + Agamogenesis? + </p> + <ol class="footnotes"> + <li> + If, on the contrary, we follow the analogy of the more complex forms of + Agamogenesis, such as that exhibited by some <i>Trematoda</i> and by the + <i>Aphides</i>, the Hyæna must produce, non-sexually, a brood of + sexless Dogs, from which other sexless Dogs must proceed. At the end of + a certain number of terms of the series, the Dogs would acquire sexes + and generate young; but these young would be, not Dogs, but Hyænas. + In fact, we have demonstrated, in Agamogenetic phænomena, that + inevitable recurrence to the original type, which is asserted to be true + of variations in general, by Mr. Darwin's opponents; and which, if the + assertion could be changed into a demonstration, would, in fact, be + fatal to his hypothesis. + </li> + </ol> + <p> + The other alternative put by Professor Kölliker--the passage of + fecundated ova in the course of their development into higher + forms--would, if it occurred, be merely an extreme case of variation in + the Darwinian sense, greater in degree than, but perfectly similar in kind + to, that which occurred when the well-known Ancon Ram was developed from + an ordinary Ewe's ovum. Indeed we have always thought that Mr. Darwin has + unnecessarily hampered himself by adhering so strictly to his favourite + "Natura non facit saltum." We greatly suspect that she does make + considerable jumps in the way of variation now and then, and that these + saltations give rise to some of the gaps which appear to exist in the + series of known forms. + </p> + <p> + Strongly and freely as we have ventured to disagree with Professor Kölliker, + we have always done so with regret, and we trust without violating that + respect which is due, not only to his scientific eminence and to the + careful study which he has devoted to the subject, but to the perfect + fairness of his argumentation, and the generous appreciation of the worth + of Mr. Darwin's labours which he always displays. It would be satisfactory + to be able to say as much for M. Flourens. + </p> + <p> + But the Perpetual Secretary of the French Academy of Sciences deals with + Mr. Darwin as the first Napoleon would have treated an "idéologue;" + and while displaying a painful weakness of logic and shallowness of + information, assumes a tone of authority, which always touches upon the + ludicrous, and sometimes passes the limits of good breeding. + </p> + <p> + For example (p. 56):-- + </p> + <p> + "M. Darwin continue: 'Aucune distinction absolue n'a été et + ne peut être établie entre les espèces et les variétés.' + Je vous ai déjà dit que vous vous trompiez; une distinction + absolue sépare les variétés d'avec les espèces." + </p> + <p> + "<i>Je vous ai déjà dit</i>; moi, M. le Secrétaire + perpétuel de l'Académie des Sciences: et vous + </p> + <p> + "'Qui n'êtes rien, Pas même Académicien;' + </p> + <p> + what do you mean by asserting the contrary?" Being devoid of the blessings + of an Academy in England, we are unaccustomed to see our ablest men + treated in this fashion, even by a "Perpetual Secretary." + </p> + <p> + Or again, considering that if there is any one quality of Mr. Darwin's + work to which friends and foes have alike borne witness, it is his candour + and fairness in admitting and discussing objections, what is to be thought + of M. Flourens' assertion, that + </p> + <p> + "M. Darwin ne cite que les auteurs qui partagent ses opinions." (P. 40.) + </p> + <p> + Once more (p. 65):-- + </p> + <p> + "Enfin l'ouvrage de M. Darwin a paru. On ne peut qu'être frappé + du talent de l'auteur. Mais quo d'idées obscures, que d'idées + fausses! Quel jargon métaphysique jeté mal à propos + dans l'histoire naturelle, qui tombe dans le galimatias dès qu'elle + sort des idées claires, des idées justes! Quel langage prétentieux + et vide! Quelles personnifications puériles et surannées! O + lucidité! 0 solidité de l'esprit Français, que + devenez-vous?" + </p> + <p> + "Obscure ideas," "metaphysical jargon," "pretentious and empty language," + "puerile and superannuated personifications." Mr. Darwin has many and hot + opponents on this side of the Channel and in Germany, but we do not + recollect to have found precisely these sins in the long catalogue of + those hitherto laid to his charge. It is worth while, therefore, to + examine into these discoveries effected solely by the aid of the "lucidity + and solidity" of the mind of M. Flourens. + </p> + <p> + According to M. Flourens, Mr. Darwin's great error is that he has + personified Nature (p. 10), and further that he has + </p> + <p> + "imagined a natural selection: he imagines afterwards that this power of + selecting (<i>pouvoir d'élire</i>) which he gives to Nature is + similar to the power of man. These two suppositions admitted, nothing + stops him: he plays with Nature as he likes, and makes her do all he + pleases." (P. 6.) + </p> + <p> + And this is the way M. Flourens extinguishes natural selection: + </p> + <p> + "Voyons donc encore une fois, ce qu'il peut y avoir de fondé dans + ce qu'on nomme <i>élection naturelle</i>. + </p> + <p> + "<i>L'élection naturelle</i> n'est sous un autre nom que la nature. + Pour un être organisé, la nature n'est que l'organisation, ni + plus ni moins. + </p> + <p> + "Il faudra donc aussi personnifier <i>l'organisation,</i> et dire que <i>l'organisation</i> + choisit <i>l'organisation. L'élection naturelle</i> est cette <i>forme + substantielle</i> dont on jouait autrefois avec tant de facilité. + Aristote disait que 'Si l'art de bâtir était dans le bois, + cet art agirait comme la nature.' A la place de <i>l'art de bâtir</i> + M. Darwin met <i>l'élection naturelle,</i> et c'est tout un: l'un + n'est pas plus chimérique que l'autre." (P. 31.) + </p> + <p> + And this is really all that M. Flourens can make of Natural Selection. We + have given the original, in fear lest a translation should be regarded as + a travesty; but with the original before the reader, we may try to analyse + the passage. "For an organised being, Nature is only organisation, neither + more nor less." + </p> + <p> + Organised beings then have absolutely no relation to inorganic nature: a + plant does not depend on soil or sunshine, climate, depth in the ocean, + height above it; the quantity of saline matters in water have no influence + upon animal life; the substitution of carbonic acid for oxygen in our + atmosphere would hurt nobody! That these are absurdities no one should + know better than M. Flourens; but they are logical deductions from the + assertion just quoted, and from the further statement that natural + selection means only that "organisation chooses and selects organisation." + </p> + <p> + For if it be once admitted (what no sane man denies) that the chances of + life of any given organism are increased by certain conditions (A) and + diminished by their opposites (B), then it is mathematically certain that + any change of conditions in the direction of (A) will exercise a selective + influence in favour of that organism, tending to its increase and + multiplication, while any change in the direction of (B) will exercise a + selective influence against that organism, tending to its decrease and + extinction. + </p> + <p> + Or, on the other hand, conditions remaining the same, let a given organism + vary (and no one doubts that they do vary) in two directions: into one + form (<i>a</i>) better fitted to cope with these conditions than the + original stock, and a second (<i>b</i>) less well adapted to them. Then it + is no less certain that the conditions in question must exercise a + selective influence in favour of (<i>a</i>) and against (<i>b</i>), so + that (<i>a</i>) will tend to predominance, and (<i>b</i>) to extirpation. + </p> + <p> + That M. Flourens should be unable to perceive the logical necessity of + these simple arguments, which lie at the foundation of all Mr. Darwin's + reasoning; that he should confound an irrefragable deduction from the + observed relations of organisms to the conditions which lie around them, + with a metaphysical "forme substantielle," or a chimerical personification + of the powers of Nature, would be incredible, were it not that other + passages of his work leave no room for doubt upon the subject. + </p> + <p> + "On imagine une <i>élection naturelle</i> que, pour plus de ménagement, + on me dit être <i>inconsciente</i>, sans s'apercevoir que le + contresens littéral est précisément là: <i>élection + inconsciente</i>." (P. 52.) + </p> + <p> + "J'ai déjà dit ce qu'il faut penser de <i>l'élection + naturelle</i>. Ou <i>l'élection naturelle</i> n'est rien, ou c'est + la nature: mais la nature douée <i>d'élection</i>, mais la + nature personnifiée: dernière erreur du dernier siècle: + Le XIXe ne fait plus de personnifications." (P. 53.) + </p> + <p> + M. Flourens cannot imagine an unconscious selection--it is for him a + contradiction in terms. Did M. Flourens ever visit one of the prettiest + watering-places of "la belle France," the Baie d'Arcachon? If so, he will + probably have passed through the district of the Landes, and will have had + an opportunity of observing the formation of "dunes" on a grand scale. + What are these "dunes"? The winds and waves of the Bay of Biscay have not + much consciousness, and yet they have with great care "selected," from + among an infinity of masses of silex of all shapes and sizes, which have + been submitted to their action, all the grains of sand below a certain + size, and have heaped them by themselves over a great area. This sand has + been "unconsciously selected" from amidst the gravel in which it first lay + with as much precision as if man had "consciously selected" it by the aid + of a sieve. Physical Geology is full of such selections--of the picking + out of the soft from the hard, of the soluble from the insoluble, of the + fusible from the infusible, by natural agencies to which we are certainly + not in the habit of ascribing consciousness. + </p> + <p> + But that which wind and sea are to a sandy beach, the sum of influences, + which we term the "conditions of existence," is to living organisms. The + weak are sifted out from the strong. A frosty night "selects" the hardy + plants in a plantation from among the tender ones as effectually as if it + were the wind, and they, the sand and pebbles, of our illustration; or, on + the other hand, as if the intelligence of a gardener had been operative in + cutting the weaker organisms down. The thistle, which has spread over the + Pampas, to the destruction of native plants, has been more effectually + "selected" by the unconscious operation of natural conditions than if a + thousand agriculturists had spent their time in sowing it. + </p> + <p> + It is one of Mr. Darwin's many great services to Biological science that + he has demonstrated the significance of these facts. He has shown that + given variation and given change of conditions the inevitable result is + the exercise of such an influence upon organisms that one is helped and + another is impeded; one tends to predominate, another to disappear; and + thus the living world bears within itself, and is surrounded by, impulses + towards incessant change. + </p> + <p> + But the truths just stated are as certain as any other physical laws, + quite independently of the truth, or falsehood, of the hypothesis which + Mr. Darwin has based upon them; and that Mr. Flourens, missing the + substance and grasping at a shadow, should be blind to the admirable + exposition of them, which Mr. Darwin has given, and see nothing there but + a "dernière erreur du dernier siècle"--a personification of + Nature--leads us indeed to cry with him: "O lucidité! O solidité + de l'esprit Français, que devenez-vous?" + </p> + <p> + M. Flourens has, in fact, utterly failed to comprehend the first + principles of the doctrine which he assails so rudely. His objections to + details are of the old sort, so battered and hackneyed on this side of the + Channel, that not even a Quarterly Reviewer could be induced to pick them + up for the purpose of pelting Mr. Darwin over again. We have Cuvier and + the mummies; M. Roulin and the domesticated animals of America; the + difficulties presented by hybridism and by Palæontology; Darwinism a + <i>rifacciamento</i> of De Maillet and Lamarck; Darwinism a system without + a commencement, and its author bound to believe in M. Pouchet, &c. + &c. How one knows it all by heart, and with what relief one reads at + p. 65-- + </p> + <p> + "Je laisse M. Darwin!" + </p> + <p> + But we cannot leave M. Flourens without calling our readers' attention to + his wonderful tenth chapter, "De la Préexistence des Germes et de + l'Epigénèse," which opens thus:-- + </p> + <p> + "Spontaneous generation is only a chimaera. This point established, two + hypotheses remain: that of <i>pre-existence</i> and that of <i>epigenesis</i>. + The one of these hypotheses has as little foundation as the other." (p. + 163.) + </p> + <p> + "The doctrine of <i>epigenesis</i> is derived from Harvey: following by + ocular inspection the development of the new being in the Windsor does, he + saw each part appear successively, and taking the moment of <i>appearance</i> + for the moment of <i>formation</i> he imagined <i>epigenesis</i>." (p. + 165.) + </p> + <p> + On the contrary, says M. Flourens (p. 167), + </p> + <p> + "The new being is formed at a stroke (<i>tout d'un coup</i>), as a whole, + instantaneously; it is not formed part by part, and at different times. It + is formed at once at the single <i>individual</i> moment at which the + conjunction of the male and female elements takes place." + </p> + <p> + It will be observed that M. Flourens uses language which cannot be + mistaken. For him, the labours of Von Baer, of Rathke, of Coste, and their + contemporaries and successors in Germany, France, and England, are + non-existent: and, as Darwin "<i>imagina</i>" natural selection, so Harvey + "<i>imagina</i>" that doctrine which gives him an even greater claim to + the veneration of posterity than his better known discovery of the + circulation of the blood. + </p> + <p> + Language such as that we have quoted is, in fact, so preposterous, so + utterly incompatible with anything but absolute ignorance of some of the + best established facts, that we should have passed it over in silence had + it not appeared to afford some clue to M. Flourens' unhesitating, <i> + à priori</i>, repudiation of all forms of the doctrine of + progressive modification of living beings. He whose mind remains + uninfluenced by an acquaintance with the phænomena of development, + must indeed lack one of the chief motives towards the endeavour to trace a + genetic relation between the different existing forms of life. Those who + are ignorant of Geology, find no difficulty in believing that the world + was made as it is; and the shepherd, untutored in history, sees no reason + to regard the green mounds which indicate the site of a Roman camp as + aught but part and parcel of the primæval hillside. So M. Flourens, + who believes that embryos are formed "tout d'un coup," naturally finds no + difficulty in conceiving that species came into existence in the same way. + </p> + <h2 id="c4"> + IV The Genealogy Of Animals <i>The Natural History of Creation</i>. By Dr. + Ernst Haeckel. [<i>Natürliche Schöpfungs-Geschichte</i>.--Von + Dr. Ernst Haeckel, Professor an der Universität Jena. Berlin, 1868.] + </h2> + <p> + [1869] + </p> + <p> + Considering that Germany now takes the lead of the world in scientific + investigation, and particularly in biology, Mr. Darwin must be well + pleased at the rapid spread of his views among some of the ablest and most + laborious of German naturalists. + </p> + <p> + Among these, Professor Haeckel, of Jena, is the Coryphæus. I know of + no more solid and important contributions to biology in the past seven + years than Haeckel's work on the "Radiolaria," and the researches of his + distinguished colleague Gegenbaur, in vertebrate anatomy; while in + Haeckel's "Generelle Morphologie" there is all the force, suggestiveness, + and, what I may term the systematising power, of Oken, without his + extravagance. The "Generelle Morphologie" is, in fact, an attempt to put + the Doctrine of Evolution, so far as it applies to the living world, into + a logical form; and to work out its practical applications to their final + results. The work before, us, again, may be said to be an exposition of + the "Generelle Morphologie" for an educated public, consisting, as it + does, of the substance of a series of lectures delivered before a mixed + audience at Jena, in the session 1867-8. + </p> + <p> + "The Natural History of Creation,"--or, as Professor Haeckel admits it + would have been better to call his work, "The History of the Development + or Evolution of Nature,"--deals, in the first six lectures, with the + general and historical aspects of the question and contains a very + interesting and lucid account of the views of Linnæus, Cuvier, + Agassiz, Goethe, Oken, Kant, Lamarck, Lyell, and Darwin, and of the + historical filiation of these philosophers. + </p> + <p> + The next six lectures are occupied by a well-digested statement of Mr. + Darwin's views. The thirteenth lecture discusses two topics which are not + touched by Mr. Darwin, namely, the origin of the present form of the solar + system, and that of living matter. Full justice is done to Kant, as the + originator of that "cosmic gas theory," as the Germans somewhat quaintly + call it, which is commonly ascribed to Laplace. With respect to + spontaneous generation, while admitting that there is no experimental + evidence in its favour, Professor Haeckel denies the possibility of + disproving it, and points out that the assumption that it has occurred is + a necessary part of the doctrine of Evolution. The fourteenth lecture, on + "Schöpfungs-Perioden und Schöpfungs-Urkunden," answers pretty + much to the famous disquisition on the "Imperfection of the Geological + Record" in the "Origin of Species." + </p> + <p> + The following five lectures contain the most original matter of any, being + devoted to "Phylogeny," or the working out of the details of the process + of Evolution in the animal and vegetable kingdoms, so as to prove the line + of descent of each group of living beings, and to furnish it with its + proper genealogical tree, or "phylum." + </p> + <p> + The last lecture considers objections and sums up the evidence in favour + of biological Evolution. + </p> + <p> + I shall best testify to my sense of the value of the work thus briefly + analysed if I now proceed to note down some of the more important + criticisms which have been suggested to me by its perusal. + </p> + <p> + I. In more than one place, Professor Haeckel enlarges upon the service + which the "Origin of Species" has done, in favouring what he terms the + "causal or mechanical" view of living nature as opposed to the + "teleological or vitalistic" view. And no doubt it is quite true that the + doctrine of Evolution is the most formidable opponent of all the commoner + and coarser forms of Teleology. But perhaps the most remarkable service to + the philosophy of Biology rendered by Mr. Darwin is the reconciliation of + Teleology and Morphology, and the explanation of the facts of both which + his views offer. + </p> + <p> + The Teleology which supposes that the eye, such as we see it in man or one + of the higher <i>Vertebrata</i>, was made with the precise structure which + it exhibits, for the purpose of enabling the animal which possesses it to + see, has undoubtedly received its death-blow. Nevertheless it is necessary + to remember that there is a wider Teleology, which is not touched by the + doctrine of Evolution, but is actually based upon the fundamental + proposition of Evolution. That proposition is, that the whole world, + living and not living, in the result of the mutual interaction, according + to definite laws, of the forces possessed by the molecules of which the + primitive nebulosity of the universe was composed. If this be true, it is + no less certain that the existing world lay, potentially, in the cosmic + vapour; and that a sufficient intelligence could, from a knowledge of the + properties of the molecules of that vapour, have predicted, say the state + of the Fauna of Britain in 1869, with as much certainty as one can say + what will happen to the vapour of the breath in a cold winter's day. + </p> + <p> + Consider a kitchen clock, which ticks loudly, shows the hours, minutes, + and seconds, strikes, cries "cuckoo!" and perhaps shows the phases of the + moon. When the clock is wound up, all the phenomena which it exhibits are + potentially contained in its mechanism, and a clever clockmaker could + predict all it will do after an examination of its structure. + </p> + <p> + If the evolution theory is correct, the molecular structure of the cosmic + gas stands in the same relation to the phenomena of the world as the + structure of the clock to its phenomena. + </p> + <p> + Now let us suppose a death-watch, living in the clock-case, to be a + learned and intelligent student of its works. He might say, "I find here + nothing but matter and force and pure mechanism from beginning to end," + and he would be quite right. But if he drew the conclusion that the clock + was not contrived for a purpose, he would be quite wrong. On the other + hand, imagine another death-watch of a different turn of mind. He, + listening to the monotonous "tick! tick!" so exactly like his own, might + arrive at the conclusion that the clock was itself a monstrous sort of + death-watch, and that its final cause and purpose was to tick. How easy to + point to the clear relation of the whole mechanism to the pendulum, to the + fact that the one thing the clock did always and without intermission was + to tick, and that all the rest of its phenomena were intermittent and + subordinate to ticking! For all this, it is certain that kitchen clocks + are not contrived for the purpose of making a ticking noise. + </p> + <p> + Thus the teleological theorist would be as wrong as the mechanical + theorist, among our death-watches; and, probably, the only death-watch who + would be right would be the one who should maintain that the sole thing + death-watches could be sure about was the nature of the clock-works and + the way they move; and that the purpose of the clock lay wholly beyond the + purview of beetle faculties. + </p> + <p> + Substitute "cosmic vapour" for "clock," and "molecules" for "works," and + the application of the argument is obvious. The teleological and the + mechanical views of nature are not, necessarily, mutually exclusive. On + the contrary, the more purely a mechanist the speculator is, the more + firmly does he assume a primordial molecular arrangement, of which all the + phenomena of the universe are the consequences; and the more completely is + he thereby at the mercy of the teleologist, who can always defy him to + disprove that this primordial molecular arrangement was not intended to + evolve the phenomena of the universe. On the other hand, if the + teleologist assert that this, that, or the other result of the working of + any part of the mechanism of the universe is its purpose and final cause, + the mechanist can always inquire how he knows that it is more than an + unessential incident--the mere ticking of the clock, which he mistakes for + its function. And there seems to be no reply to this inquiry, any more + than to the further, not irrational, question, why trouble one's self + about matters which are out of reach, when the working of the mechanism + itself, which is of infinite practical importance, affords scope for all + our energies? + </p> + <p> + Professor Haeckel has invented a new and convenient name "Dysteleology," + for the study of the "purposelessnesses" which are observable in living + organisms--such as the multitudinous cases of rudimentary and apparently + useless structures. I confess, however, that it has often appeared to me + that the facts of Dysteleology cut two ways. If we are to assume, as + evolutionists in general do, that useless organs atrophy, such cases as + the existence of lateral rudiments of toes, in the foot of a horse, place + us in a dilemma. For, either these rudiments are of no use to the animal, + in which case, considering that the horse has existed in its present form + since the Pliocene epoch, they surely ought to have disappeared; or they + are of some use to the animal, in which case they are of no use as + arguments against Teleology. A similar, but still stronger, argument may + be based upon the existence of teats, and even functional mammary glands, + in male mammals. Numerous cases of "Gynæcomasty," or functionally + active breasts in men, are on record, though there is no mammalian species + whatever in which the male normally suckles the young. Thus, there can be + little doubt that the mammary gland was as apparently useless in the + remotest male mammalian ancestor of man as in living men, and yet it has + not disappeared. Is it then still profitable to the male organism to + retain it? Possibly; but in that case its dysteleological value is gone. + [*] + </p> + <ol class="footnotes"> + <li> + The recent discovery of the important part played by the Thyroid gland + should be a warning to all speculators about useless organs. 1893. + </li> + </ol> + <p> + II. Professor Haeckel looks upon the causes which have led to the present + diversity of living nature as twofold. Living matter, he tells us, is + urged by two impulses: a centripetal, which tends to preserve and transmit + the specific form, and which he identifies with heredity; and a + centrifugal, which results from the tendency of external conditions to + modify the organism and effect its adaptation to themselves. The internal + impulse is conservative, and tends to the preservation of specific, or + individual, form; the external impulse is metamorphic, and tends to the + modification of specific, or individual, form. + </p> + <p> + In developing his views upon this subject, Professor Haeckel introduces + qualifications which disarm some of the criticisms I should have been + disposed to offer; but I think that his method of stating the case has the + inconvenience of tending to leave out of sight the important fact--which + is a cardinal point in the Darwinian hypothesis--that the tendency to + vary, in a given organism, may have nothing to do with the external + conditions to which that individual organism is exposed, but may depend + wholly upon internal conditions. No one, I imagine, would dream of seeking + for the cause of the development of the sixth finger and toe in the famous + Maltese, in the direct influence of the external conditions of his life. + </p> + <p> + I conceive that both hereditary transmission and adaptation need to be + analysed into their constituent conditions by the further application of + the doctrine of the Struggle for Existence. It is a probable hypothesis, + that what the world is to organisms in general, each organism is to the + molecules of which it is composed. Multitudes of these, having diverse + tendencies, are competing with one another for opportunity to exist and + multiply; and the organism, as a whole, is as much the product of the + molecules which are victorious as the Fauna, or Flora, of a country is the + product of the victorious organic beings in it. + </p> + <p> + On this hypothesis, hereditary transmission is the result of the victory + of particular molecules contained in the impregnated germ. Adaptation to + conditions is the result of the favouring of the multiplication of those + molecules whose organising tendencies are most in harmony with such + conditions. In this view of the matter, conditions are not actively + productive, but are passively permissive; they do not cause variation in + any given direction, but they permit and favour a tendency in that + direction which already exists. + </p> + <p> + It is true that, in the long run, the origin of the organic molecules + themselves, and of their tendencies, is to be sought in the external + world; but if we carry our inquiries as far back as this, the distinction + between internal and external impulses vanishes. On the other hand, if we + confine ourselves to the consideration of a single organism, I think it + must be admitted that the existence of an internal metamorphic tendency + must be as distinctly recognised as that of an internal conservative + tendency; and that the influence of conditions is mainly, if not wholly, + the result of the extent to which they favour the one, or the other, of + these tendencies. + </p> + <p> + III. There is only one point upon which I fundamentally and entirely + disagree with Professor Haeckel, but that is the very important one of his + conception of geological time, and of the meaning of the stratified rocks + as records and indications of that time. Conceiving that the stratified + rocks of an epoch indicate a period of depression, and that the intervals + between the epochs correspond with periods of elevation of which we have + no record, he intercalates between the different epochs, or periods, + intervals which he terms "Ante-periods." Thus, instead of considering the + Triassic, Jurassic, Cretaceous, and Eocene periods, as continuously + successive, he interposes a period before each, as an "Antetrias-zeit," + "Antejura-zeit," "Antecreta-zeit," "Anteo-cenzeit," &c. And he + conceives that the abrupt changes between the Faunæ of the different + formations are due to the lapse of time, of which we have no organic + record, during their "Ante-periods." + </p> + <p> + The frequent occurrence of strata containing assemblages of organic forms + which are intermediate between those of adjacent formations, is, to my + mind, fatal to this view. In the well-known St. Cassian beds, for example, + Palaeozoic and Mesozoic forms are commingled, and, between the Cretaceous + and the Eocene formations, there are similar transitional beds. On the + other hand, in the middle of the Silurian series, extensive unconformity + of the strata indicates the lapse of vast intervals of time between the + deposit of successive beds, without any corresponding change in the Fauna. + </p> + <p> + Professor Haeckel will, I fear, think me unreasonable, if I say that he + seems to be still overshadowed by geological superstitions; and that he + will have to believe in the completeness of the geological record far less + than he does at present. He assumes, for example, that there was no dry + land, nor any terrestrial life, before the end of the Silurian epoch, + simply because, up to the present time, no indications of fresh water, or + terrestrial organisms, have been found in rocks of older date. And, in + speculating upon the origin of a given group, he rarely goes further back + than the "Ante-period," which precedes that in which the remains of + animals belonging to that group are found. Thus, as fossil remains of the + majority of the groups of <i>Reptilia</i> are first found in the Trias, + they are assumed to have originated in the "Antetriassic" period, or + between the Permian and Triassic epochs. + </p> + <p> + I confess this is wholly incredible to me. The Permian and the Triassic + deposits pass completely into one another; there is no sort of + discontinuity answering to an unrecorded "Antetrias"; and, what is more, + we have evidence of immensely extensive dry land during the formation of + these deposits. We know that the dry land of the Trias absolutely teemed + with reptiles of all groups except Pterodactyles, Snakes, and perhaps + Tortoises; there is every probability that true Birds existed, and <i>Mammalia</i> + certainly did. Of the inhabitants of the Permian dry land, on the + contrary, all that have left a record are a few lizards. Is it conceivable + that these last should really represent the whole terrestrial population + of that time, and that the development of Mammals, of Birds, and of the + highest forms of Reptiles, should have been crowded into the time during + which the Permian conditions quietly passed away, and the Triassic + conditions began? Does not any such supposition become in the highest + degree improbable, when, in the terrestrial or fresh-water + Labyrinthodonts, which lived on the land of the Carboniferous epoch, as + well as on that of the Trias, we have evidence that one form of + terrestrial life persisted, throughout all these ages, with no important + modification? For my part, having regard to the small amount of + modification (except in the way of extinction) which the Crocodilian, + Lacertilian, and Chelonian <i>Reptilia</i> have undergone, from the older + Mesozoic times to the present day, I cannot but put the existence of the + common stock from which they sprang far back in the Palæozoic epoch; + and I should apply a similar argumentation to all other groups of animals. + </p> + <p> + [The remainder of this essay contains a discussion of questions of + taxonomy and phylogeny, which is now antiquated. I have reprinted the + considerations about the reconciliation of Teleology with Morphology, + about "Dysteleology," and about the struggle for existence within the + organism, because it has happened to me to be charged with overlooking + them. + </p> + <p> + In discussing Teleology, I ought to have pointed out, as I have done + elsewhere (<i>Life and Letters of Charles Darwin</i>, vol. ii. p. 202), + that Paley "proleptically accepted the modern doctrine of Evolution," (<i>Natural + Theology</i>, chap. xxiii.). 1893.] + </p> + <h2 id="c5"> + V Mr. Darwin's Critics [*] + </h2> + <ol class="footnotes"> + <li> + <i>Contributions to the Theory of Natural Selection</i>. By A. R. + Wallace. 1870.--2. <i>The Genesis of Species</i>. By St. George Mivart, + F.R.S. Second Edition. 1871.--3. <i>Darwin's Descent of Man</i>. + Quarterly Review, July 1871. + </li> + </ol> + <p> + [1871] + </p> + <p> + The gradual lapse of time has now separated us by more than a decade from + the date of the publication of the "Origin of Species"--and whatever may + be thought or said about Mr. Darwin's doctrines, or the manner in which he + has propounded them, this much is certain, that, in a dozen years, the + "Origin of Species" has worked as complete a revolution in biological + science as the "Principia" did in astronomy--and it has done so, because, + in the words of Helmholtz, it contains "an essentially new creative + thought." [*] And as time has slipped by, a happy change has come over Mr. + Darwin's critics. The mixture of ignorance and insolence which, at first, + characterised a large proportion of the attacks with which he was + assailed, is no longer the sad distinction of anti-Darwinian criticism. + Instead of abusive nonsense, which merely discredited its writers, we read + essays, which are, at worst, more or less intelligent and appreciative; + while, sometimes, like that which appeared in the "North British Review" + for 1867, they have a real and permanent value. + </p> + <ol class="footnotes"> + <li> + Helmholtz: <i>Ueber das Ziel und die Fortschritte der Naturwissenschaft</i>. + Eröffnungsrede für die Naturforscherversammlung zu Innsbruck. + 1869. + </li> + </ol> + <p> + The several publications of Mr. Wallace and Mr. Mivart contain discussions + of some of Mr. Darwin's views, which are worthy of particular attention, + not only on account of the acknowledged scientific competence of these + writers, but because they exhibit an attention to those philosophical + questions which underlie all physical science, which is as rare as it is + needful. And the same may be said of an article in the "Quarterly Review" + for July 1871, the comparison of which with an article in the same Review + for July 1860, is perhaps the best evidence which can be brought forward + of the change which has taken place in public opinion on "Darwinism." + </p> + <p> + The Quarterly Reviewer admits "the certainty of the action of natural + selection" (p. 49); and further allows that there is an <i>à priori</i> + probability in favour of the evolution of man from some lower animal form, + if these lower animal forms themselves have arisen by evolution. + </p> + <p> + Mr. Wallace and Mr. Mivart go much further than this. They are as stout + believers in evolution as Mr. Darwin himself; but Mr. Wallace denies that + man can have been evolved from a lower animal by that process of natural + selection which he, with Mr. Darwin, holds to have been sufficient for the + evolution of all animals below man; while Mr. Mivart, admitting that + natural selection has been one of the conditions of the evolution of the + animals below man, maintains that natural selection must, even in their + case, have been supplemented by "some other cause"--of the nature of + which, unfortunately, he does not give us any idea. Thus Mr. Mivart is + less of a Darwinian than Mr. Wallace, for he has less faith in the power + of natural selection. But he is more of an evolutionist than Mr. Wallace, + because Mr. Wallace thinks it necessary to call in an intelligent agent--a + sort of supernatural Sir John Sebright--to produce even the animal frame + of man; while Mr. Mivart requires no Divine assistance till he comes to + man's soul. + </p> + <p> + Thus there is a considerable divergence between Mr. Wallace and Mr. + Mivart. On the other hand, there are some curious similarities between Mr. + Mivart and the Quarterly Reviewer, and these are sometimes so close, that, + if Mr. Mivart thought it worth while, I think he might make out a good + case of plagiarism against the Reviewer, who studiously abstains from + quoting him. + </p> + <p> + Both the Reviewer and Mr. Mivart reproach Mr. Darwin with being, "like so + many other physicists," entangled in a radically false metaphysical + system, and with setting at nought the first principles of both philosophy + and religion. Both enlarge upon the necessity of a sound philosophical + basis, and both, I venture to add, make a conspicuous exhibition of its + absence. The Quarterly Reviewer believes that man "differs more from an + elephant or a gorilla than do these from the dust of the earth on which + they tread," and Mr. Mivart has expressed the opinion that there is more + difference between man and an ape than there is between an ape and a piece + of granite. [*] + </p> + <ol class="footnotes"> + <li> + See the <i>Tablet</i> for March 11, 1871. + </li> + </ol> + <p> + And even when Mr. Mivart (p. 86) trips in a matter of anatomy, and creates + a difficulty for Mr. Darwin out of a supposed close similarity between the + eyes of fishes and cephalopods, which (as Gegenbaur and others have + clearly shown) does not exist, the Quarterly Reviewer adopts the argument + without hesitation (p. 66). + </p> + <p> + There is another important point, however, in which it is hard to say + whether Mr. Mivart diverges from the Quarterly Reviewer or not. + </p> + <p> + The Reviewer declares that Mr. Darwin has, "with needless opposition, set + at nought the first principles of both philosophy and religion" (p. 90). + </p> + <p> + It looks, at first, as if this meant, that Mr. Darwin's views being false, + the opposition to "religion" which flows from them must be needless. But I + suspect this is not the right view of the meaning of the passage, as Mr. + Mivart, from whom the Quarterly Reviewer plainly draws so much + inspiration, tells us that "the consequences which have been drawn from + evolution, whether exclusively Darwinian or not, to the prejudice of + religion, by no means follow from it, and are in fact illegitimate" (p. + 5). + </p> + <p> + I may assume, then, that the Quarterly Reviewer and Mr. Mivart admit that + there is no necessary opposition between "evolution whether exclusively + Darwinian or not," and religion. But then, what do they mean by this last + much-abused term? On this point the Quarterly Reviewer is silent. Mr. + Mivart, on the contrary, is perfectly explicit, and the whole tenor of his + remarks leaves no doubt that by "religion" he means theology; and by + theology, that particular variety of the great Proteus, which is expounded + by the doctors of the Roman Catholic Church, and held by the members of + that religious community to be the sole form of absolute truth and of + saving faith. + </p> + <p> + According to Mr. Mivart, the greatest and most orthodox authorities upon + matters of Catholic doctrine agree in distinctly asserting "derivative + creation" or evolution; "and thus their teachings harmonise with all that + modern science can possibly require" (p. 305). + </p> + <p> + I confess that this bold assertion interested me more thananything else in + Mr. Mivart's book. What little knowledge I possessed of Catholic doctrine, + and of the influence exerted by Catholic authority in former times, had + not led me to expect that modern science was likely to find a warm welcome + within the pale of the greatest and most consistent of theological + organisations. + </p> + <p> + And my astonishment reached its climax when I found Mr. Mivart citing + Father Suarez as his chief witness in favour of the scientific freedom + enjoyed by Catholics--the popular repute of that learned theologian and + subtle casuist not being such as to make his works a likely place of + refuge for liberality of thought. But in these days, when Judas Iscariot + and Robespierre, Henry VIII. and Catiline, have all been shown to be men + of admirable virtue, far in advance of their age, and consequently the + victims of vulgar prejudice, it was obviously possible that Jesuit Suarez + might be in like case. And, spurred by Mr. Mivart's unhesitating + declaration, I hastened to acquaint myself with such of the works of the + great Catholic divine as bore upon the question, hoping, not merely to + acquaint myself with the true teachings of the infallible Church, and free + myself of an unjust prejudice; but, haply, to enable myself, at a pinch, + to put some Protestant bibliolater to shame, by the bright example of + Catholic freedom from the trammels of verbal inspiration. + </p> + <p> + I regret to say that my anticipations have been cruelly disappointed. But + the extent to which my hopes have been crushed can only be fully + appreciated by citing, in the first place, those passages of Mr. Mivart's + work by which they were excited. In his introductory chapter I find the + following passages:-- + </p> + <p> + "The prevalence of this theory [of evolution] need alarm no one, for it + is, without any doubt, perfectly consistent with the strictest and most + orthodox Christian [*] theology" (p. 5). + </p> + <ol class="footnotes"> + <li> + It should be observed that Mr. Mivart employs the term 'Christian' as if + it were the equivalent of 'Catholic.' + </li> + </ol> + <p> + "Mr. Darwin and others may perhaps be excused if they have not devoted + much time to the study of Christian philosophy; but they have no right to + assume or accept without careful examination, as an unquestioned fact, + that in that philosophy there is a necessary antagonism between the two + ideas 'creation' and 'evolution,' as applied to organic forms. + </p> + <p> + "It is notorious and patent to all who choose to seek, that many + distinguished Christian thinkers have accepted, and do accept, both ideas, + <i>i.e.</i> both 'creation' and 'evolution.' + </p> + <p> + "As much as ten years ago an eminently Christian writer observed: 'The + creationist theory does not necessitate the perpetual search after + manifestations of miraculous power and perpetual "catastrophes." Creation + is not a miraculous interference with the laws of Nature, but the very + institution of those laws. Law and regularity, not arbitrary intervention, + was the patristic ideal of creation. With this notion they admitted, + without difficulty, the most surprising origin of living creatures, + provided it took place by <i>law</i>. They held that when God said, "Let + the waters produce," "Let the earth produce," He conferred forces on the + elements of earth and water which enabled them naturally to produce the + various species of organic beings. This power, they thought, remains + attached to the elements throughout all time.' The same writer quotes St. + Augustin and St. Thomas Aquinas, to the effect that, 'in the institution + of Nature, we do not look for miracles, but for the laws of Nature.' And, + again, St. Basil speaks of the continued operation of natural laws in the + production of all organisms. + </p> + <p> + "So much for the writers of early and mediæval times. As to the + present day, the author can confidently affirm that there are many as well + versed in theology as Mr. Darwin is in his own department of natural + knowledge, who would not be disturbed by the thorough demonstration of his + theory. Nay, they would not even be in the least painfully affected at + witnessing the generation of animals of complex organisation by the + skilful artificial arrangement of natural forces, and the production, in + the future, of a fish by means analogous to those by which we now produce + urea. + </p> + <p> + "And this because they know that the possibility of such phenomena, though + by no means actually foreseen, has yet been fully provided for in the old + philosophy centuries before Darwin, or even centuries before Bacon, and + that their place in the system can be at once assigned them without even + disturbing its order or marring its harmony. + </p> + <p> + "Moreover, the old tradition in this respect has never been abandoned, + however much it may have been ignored or neglected by some modern writers. + In proof of this, it may be observed that perhaps no post-mediæval + theologian has a wider reception amongst Christians throughout the world + than Suarez, who has a separate section [*] in opposition to those who + maintain the distinct creation of the various kinds--or substantial + forms--of organic life" (pp. 19-21). + </p> + <ol class="footnotes"> + <li> + Suarez, <i>Metaphysica</i>. Edition Vivés. Paris, 1868, vol. i + Disput. xv. § 2. + </li> + </ol> + <p> + Still more distinctly does Mr. Mivart express himself in the same sense, + in his last chapter, entitled "Theology and Evolution" (pp. 302-5). + </p> + <p> + "It appears, then, that Christian thinkers are perfectly free to accept + the general evolution theory. But are there any theological authorities to + justify this view of the matter? + </p> + <p> + "Now, considering how extremely recent are these biological speculations, + it might hardly be expected <i>à priori</i> that writers of earlier + ages should have given expression to doctrines harmonising in any degree + with such very modern views; nevertheless, this is certainly the case, and + it would be easy to give numerous examples. It will be better, however, to + cite one or two authorities of weight. Perhaps no writer of the earlier + Christian ages could be quoted whose authority is more generally + recognised than that of St. Augustin. The same may be said of the mediæval + period for St. Thomas Aquinas: and since the movement of Luther, Suarez + may be taken as an authority, widely venerated, and one whose orthodoxy + has never been questioned. + </p> + <p> + "It must be borne in mind that for a considerable time even after the last + of these writers no one had disputed the generally received belief as to + the small age of the world, or at least of the kinds of animals and plants + inhabiting it. It becomes, therefore, much more striking if views formed + under such a condition of opinion are found to harmonise with modern ideas + concerning 'Creation' and organic Life. + </p> + <p> + "Now St. Augustin insists in a very remarkable manner on the merely + derivative sense in which God's creation of organic forms is to be + understood; that is, that God created them by conferring on the material + world the power to evolve them under suitable conditions." + </p> + <p> + Mr. Mivart then cites certain passages from St. Augustin, St. Thomas + Aquinas, and Cornelius à Lapide, and finally adds:-- + </p> + <p> + "As to Suarez, it will be enough to refer to Disp. xv. sec. 2, No. 9, p. + 508, t. i. edition Vivés, Paris; also Nos. 13-15. Many other + references to the same effect could easily be given, but these may + suffice. + </p> + <p> + "It is then evident that ancient and most venerable theological + authorities distinctly assert derivative creation, and thus their + teachings harmonise with all that modern science can possibly require." + </p> + <p> + It will be observed that Mr. Mivart refers solely to Suarez's fifteenth + Disputation, though he adds, "Many other references to the same effect + could easily be given." I shall look anxiously for these references in the + third edition of the "Genesis of Species." For the present, all I can say + is, that I have sought in vain, either in the fifteenth Disputation, or + elsewhere, for any passage in Suarez's writings which, in the slightest + degree, bears out Mr. Mivart's views as to his opinions. [*] + </p> + <ol class="footnotes"> + <li> + The edition of Suarez's <i>Disputationes</i> from which the following + citations are given, is Birckmann's, in two volumes folio, and is dated + 1680. + </li> + </ol> + <p> + The title of this fifteenth Disputation is "De causa formali + substantiali," and the second section of that Disputation (to which Mr. + Mivart refers) is headed, "Quomodo possit forma substantialis fieri in + materia et ex materia?" + </p> + <p> + The problem which Suarez discusses in this place may be popularly stated + thus: According to the scholastic philosophy every natural body has two + components--the one its "matter" (<i>materia prima</i>), the other its + "substantial form" (<i>forma substantialis</i>). Of these the matter is + everywhere the same, the matter of one body being indistinguishable from + the matter of any other body. That which differentiates any one natural + body from all others is its substantial form, which inheres in the matter + of that body, as the human soul inheres in the matter of the frame of man, + and is the source of all the activities and other properties of the body. + </p> + <p> + Thus, says Suarez, if water is heated, and the source of heat is then + removed, it cools again. The reason of this is that there is a certain "<i>intimius + principium</i>" in the water, which brings it back to the cool condition + when the external impediment to the existence of that condition is + removed. This <i>intimius principium</i> is the "substantial form" of the + water. And the substantial form of the water is not only the cause (<i>radix</i>) + of the coolness of the water, but also of its moisture, of its density, + and of all its other properties. + </p> + <p> + It will thus be seen that "substantial forms" play nearly the same part in + the scholastic philosophy as "forces" do in modern science; the general + tendency of modern thought being to conceive all bodies as resolvable into + material particles and forces, in virtue of which last these particles + assume those dispositions and exercise those powers which are + characteristic of each particular kind of matter. + </p> + <p> + But the Schoolmen distinguished two kinds of substantial forms, the one + spiritual and the other material. The former division is represented by + the human soul, the <i>anima rationalis</i>; and they affirm as a matter, + not merely of reason, but of faith, that every human soul is created out + of nothing, and by this act of creation is endowed with the power of + existing for all eternity, apart from the <i>materia prima</i> of which + the corporeal frame of man is composed. And the <i>anima rationalis</i>, + once united with the <i>materia prima</i> of the body, becomes its + substantial form, and is the source of all the powers and faculties of + man--of all the vital and sensitive phenomena which he exhibits--just as + the substantial form of water is the source of all its qualities. + </p> + <p> + The "material substantial forms" are those which inform all other natural + bodies except that of man; and the object of Suarez in the present + Disputation, is to show that the axiom "<i>ex nihilo nihil fit</i>," + though not true of the substantial form of man, is true of the substantial + forms of all other bodies, the endless mutations of which constitute the + ordinary course of nature. The origin of the difficulty which he discusses + is easily comprehensible. Suppose a piece of bright iron to be exposed to + the air. The existence of the iron depends on the presence within it of a + substantial form, which is the cause of its properties, <i>e.g.</i> + brightness, hardness, weight. But, by degrees, the iron becomes converted + into a mass of rust, which is dull, and soft, and light, and, in all other + respects, is quite different from the iron. As, in the scholastic view, + this difference is due to the rust being informed by a new substantial + form, the grave problem arises, how did this new substantial form come + into being? Has it been created? or has it arisen by the power of natural + causation? If the former hypothesis is correct, then the axiom, "<i>ex + nihilo nihil fit</i>," is false, even in relation to the ordinary course + of nature, seeing that such mutations of matter as imply the continual + origin of new substantial forms are occurring every moment. But the + harmonisation of Aristotle with theology was as dear to the Schoolmen, as + the smoothing down the differences between Moses and science is to our + Broad Churchmen, and they were proportionably unwilling to contradict one + of Aristotle's fundamental propositions. Nor was their objection to flying + in the face of the Stagirite likely to be lessened by the fact that such + flight landed them in flat Pantheism. + </p> + <p> + So Father Suarez fights stoutly for the second hypothesis; and I quote the + principal part of his argumentation as an exquisite specimen of that + speech which is a "darkening of counsel." + </p> + <p> + "13. Secundo de omnibus aliis formis substantialibus [sc. materialibus] + dicendum est non fieri proprie ex nihilo, sed ex potentia præjacentis + materiæ educi: ideoque in effectione harum formarum nil fieri contra + illud axioma, <i>Ex nihilo nihil fit</i>, si recte intelligatur. Hæc + assertio sumitur ex Aristotele 1. Physicorum per totum et libro 7. + Metaphyss. et ex aliis auctoribus, quos statim referam. Et declaratur + breviter, nam fieri ex nihilo duo dicit, unum est fieri absolute et + simpliciter, aliud est quod talis effectio fit ex nihilo. Primum propriè + dicitur de re subsistente, quia ejus est fieri, cujus est esse: id autem + proprie quod subsistit et habet esse; nam quod alteri adjacet, potius est + quo aliud est. Ex hac ergo parte, formæ substantiales materiales non + fiunt ex nihilo, quia proprie non fiunt. Atque hanc rationem reddit Divus + Thomas 1 parte, quæstione 45, articulo 8, et quæstione 90, + articulo 2, et ex dicendis magis explicabitur. Sumendo ergo ipsum <i>fieri</i> + in hac proprietate et rigore, sic fieri ex nihilo est fieri secundum se + totum, id est nulla sui parte præsupposita, ex quo fiat. Et hac + ratione res naturales dum de novo fiunt, non fiunt ex nihilo, quia fiunt + ex præsupposita materia, ex qua componuntur, et ita non fiunt, + secundum se totæ, sed secundum aliquid sui. Formæ autem harum + rerum, quamvis revera totam suam entitatem de novo accipiant, quam antea + non habebant, quia vero ipsæ non fiunt, ut dictum est, ideo neque ex + nihilo fiunt. Attamen, quia latiori modo sumendo verbum illud <i>fieri</i> + negari non potest: quin forma facta sit, eo modo quo nunc est, et antea + non erat, ut etiam probat ratio dubitandi posita in principio sectionis, + ideo addendum est, sumpto <i>fieri</i> in hac amplitudine, fieri ex nihilo + non tamen negare habitudinem materialis causæ intrinsecè + componentis id quod fit, sed etiam habitudinem causæ materialis per + se causantis et sustentantis formam quæ fit, seu confit. Diximus + enim in superioribus materiam et esse causam compositi et formæ + dependentis ab illa: ut res ergo dicatur ex nihilo fieri uterque modus + causalitatis negari debet; et eodem sensu accipiendum est illud axioma, ut + sit verum: <i>Ex nihilo nihil fit</i>, scilicet virtute agentis naturalis + et finiti nihil fieri, nisi ex præsupposito subjecto per se + concurrente, et ad compositum et ad formam, si utrumque suo modo ab eodem + agente fiat. Ex his ergo rectè concluditur, formas substantiales + materiales non fieri ex nihilo, quia fiunt ex materia, quæ in suo + genere per se concurrit, et influit ad esse, et fieri talium formarum; + quia, sicut esse non possunt nisi affixae materiæ, a qua + sustententur in esse: ita nec fieri possunt, nisi earum effectio et + penetratio in eadem materia sustentetur. Et hæc est propria et per + se differentia inter effectionem ex nihilo, et ex aliquo, propter quam, ut + infra ostendemus, prior modus efficiendi superat vim finitam naturaliam + agentium, non vero posterior. + </p> + <p> + "14. Ex his etiam constat, proprie de his formis dici non creari, sed + educi de potentia materiæ." [*] + </p> + <ol class="footnotes"> + <li> + Suarez, <i>loc. cit.</i> Disput. xv. § ii. + </li> + </ol> + <p> + If I may venture to interpret these hard sayings, Suarez conceives that + the evolution of substantial forms in the ordinary course of nature, is + conditioned not only by the existence of the <i>materia prima</i>, but + also by a certain "concurrence and influence" which that <i>materia</i> + exerts; and every new substantial form being thus conditioned, and in + part, at any rate, caused, by a pre-existing something, cannot be said to + be created out of nothing. + </p> + <p> + But as the whole tenor of the context shows, Suarez applies this + argumentation merely to the evolution of material substantial forms in the + ordinary course of nature. How the substantial forms of animals and plants + primarily originated, is a question to which, so far as I am able to + discover, he does not so much as allude in his "Metaphysical + Disputations." Nor was there any necessity that he should do so, inasmuch + as he has devoted a separate treatise of considerable bulk to the + discussion of all the problems which arise out of the account of the + Creation which is given in the Book of Genesis. And it is a matter of + wonderment to me that Mr. Mivart, who somewhat sharply reproves "Mr. + Darwin and others" for not acquainting themselves with the true teachings + of his Church, should allow himself to be indebted to a heretic like + myself for a knowledge of the existence of that "Tractatus de opere sex + Dierum," [*] in which the learned Father, of whom he justly speaks, as "an + authority widely venerated, and whose orthodoxy has never been + questioned," directly opposes all those opinions for which Mr. Mivart + claims the shelter of his authority. + </p> + <ol class="footnotes"> + <li> + <i>Tractatus de opere sex Dierum, seu de Universi Creatione, quatenus + sex diebus perfecta esse, in libro Genesis cap. i. refertur, et + praesertim de productione hominis in statu innocentiae.</i> Ed. + Birckmann, 1622. + </li> + </ol> + <p> + In the tenth and eleventh chapters of the first book of this treatise, + Suarez inquires in what sense the word "day," as employed in the first + chapter of Genesis, is to be taken. He discusses the views of Philo and of + Augustin on this question, and rejects them. He suggests that the approval + of their allegorising interpretations by St. Thomas Aquinas, merely arose + out of St. Thomas's modesty, and his desire not to seem openly to + controvert St. Augustin--"voluisse Divus Thomas pro sua modestia + subterfugere vim argumenti potius quam aperte Augustinum inconstantiæ + arguere." + </p> + <p> + Finally, Suarez decides that the writer of Genesis meant that the term + "day" should be taken in its natural sense; and he winds up the discussion + with the very just and natural remark that "it is not probable that God, + in inspiring Moses to write a history of the Creation which was to be + believed by ordinary people, would have made him use language, the true + meaning of which it is hard to discover, and still harder to believe." [*] + </p> + <ol class="footnotes"> + <li> + "Propter hæc ergo sententia illa Augustini et propter nimiam + obscuritatem et subtilitatem ejus difficilis creditu est: quia + verisimile non est Deum inspirasse Moysi, ut historiam de creatione + mundi ad fidem totius populi adeo necessariam per nomina dierum + explicaret, quorum significatio vix inveniri et difficillime ab aliquo + credi posset." (<i>Loc. cit.</i> Lib. I. cap. xi. 42.) + </li> + </ol> + <p> + And in chapter xii. 3, Suarez further observes:-- + </p> + <p> + "Ratio enim retinendi veram significationem diei naturalis est illa + communis, quod verba Scripturæ non sunt ad metaphoras transferenda, + nisi vel necessitas cogit, vel ex ipsa scriptura constet, et maximè + in historica narratione et ad instructionem fidei pertinente: sed hæc + ratio non minus cogit ad intelligendum propriè dierum numerum, quam + diei qualitatem, QUIA NON MINUS UNO MODO QUAM ALIO DESTRUITUR SINCERITAS, + IMO ET VERITAS HISTORIÆ. Secundo hoc valde confirmant alia Scripturæ + loca, in quibus hi sex dies tanquam veri, et inter se distincti + commemorantur, ut Exod. 20 dicitur, <i>Sex diebus operabis et facies omnia + opera tua, septimo autem die Sabbatum Domini Dei tui est</i>. Et infra: <i>Sex + enim diebus fecit Dominus cælum et terram et mare et omnia quæ + in eis sunt</i>, et idem repetitur in cap. 31. In quibus locis sermonis + proprietas colligi potest tum ex æquiparatione, nam cum dicitur: <i>sex + diebus operabis</i>, propriissimè intelligitur: tum quia non est + verisimile, potuisse populum intelligere verba illa in alio sensu, et + è contrario incredibile est, Deum in suis præceptis tradendis + illis verbis ad populum fuisse loquutum, quibus deciperetur, falsum sensum + concipiendo, si Deus non per sex veros dies opera sua fecisset." + </p> + <p> + These passages leave no doubt that this great doctor of the Catholic + Church, of unchallenged authority and unspotted orthodoxy, not only + declares it to be Catholic doctrine that the work of creation took place + in the space of six natural days; but that he warmly repudiates, as + inconsistent with our knowledge of the Divine attributes, the supposition + that the language which Catholic faith requires the believer to hold that + God inspired, was used in any other sense than that which He knew it would + convey to the minds of those to whom it was addressed. + </p> + <p> + And I think that in this repudiation Father Suarez will have the sympathy + of every man of common uprightness, to whom it is certainly "incredible" + that the Almighty should have acted in a manner which He would esteem + dishonest and base in a man. + </p> + <p> + But the belief that the universe was created in six natural days is + hopelessly inconsistent with the doctrine of evolution, in so far as it + applies to the stars and planetary bodies; and it can be made to agree + with a belief in the evolution of living beings only by the supposition + that the plants and animals, which are said to have been created on the + third, fifth, and sixth days, were merely the primordial forms, or + rudiments, out of which existing plants and animals have been evolved; so + that, on these days, plants and animals were not created actually, but + only potentially. + </p> + <p> + The latter view is that held by Mr. Mivart, who follows St. Augustin, and + implies that he has the sanction of Suarez. But, in point of fact, the + latter great light of orthodoxy takes no small pains to give the most + explicit and direct contradiction to all such imaginations, as the + following passages prove. In the first place, as regards plants, Suarez + discusses the problem:-- + </p> + <p> + "<i>Quomodo herba virens et cætera vegetabilia hoc</i> [<i>tertio</i>] + <i>die fuerint producta</i>. [*] + </p> + <ol class="footnotes"> + <li> + <i>Loc. cit.</i> Lib. II. cap. vii. et viii. 1, 32, 35. + </li> + </ol> + <p> + "Præcipua enim difficultas hîc est, quam attingit Div. Thomas + 1, par. qu. 69, art. 2, an hæc productio plantarum hoc die facta + intelligenda sit de productione ipsarum in proprio esse actuali et formali + (ut sic rem explicerem) vel de productione tantum in semine et in + potentia. Nam Divus Augustinus libro quinto Genes, ad liter. cap. 4 et 5 + et libro 8, cap. 3, posteriorem partem tradit, dicens, terram in hoc die + accepisse virtutem germinandi omnia vegetabilia quasi concepto omnium + illorum semine, non tamen statim vegetabilia omnia produxisse. Quod primo + suadet verbis illis capitis secundi. <i>In die quo fecit Deus cælum + et terram et omne virgultum agri priusquam germinaret</i>. Quomodo enim + potuerunt virgulta fieri antequam terra germinaret nisi quia causaliter + prius et quasi in radice, seu in semine facta sunt, et postea in actu + producta? Secundo confirmari potest, quia verbum illud <i>germinet terra</i> + optimè exponitur potestativè ut sic dicam, id est accipiat + terra vim germinandi. Sicut in eodem capite dicitur <i>crescite et + multiplicamini</i>. Tertio potest confirmari, quia actualis productio + vegetabilium non tam ad opus creationis, quam ad opus propagationis + pertinet, quod postea factum est. Et hanc sententiam sequitur Eucherius + lib. 1, in Gen. cap. 11, et illi faveat Glossa, interli. Hugo. et Lyran. + dum verbum <i>germinet</i> dicto modo exponunt. NIHILOMINUS CONTRARIA + SENTENTIA TENENDA EST: SCILICET, PRODUXISSE DEUM HOC DIE HERBAM, ARBORES, + ET ALIA VEGETABILIA ACTU IN PROPRIA SPECIE ET NATURA. Hæc est + communis sententia Patrum.--Basil. homil. 5; Exæmer. Ambros. lib. 3; + Exæmer. cap. 8, 11, et 16; Chrysost. homil. 5 in Gen. Damascene. + lib. 2 de Fid. cap. 10; Theodor. Cyrilli. Bedæ, Glossæ + ordinariæ et aliorum in Gen. Et idem sentit Divus Thomas, <i>supra</i>, + solvens argumenta Augustini, quamvis propter reverentiam ejus quasi + problematicè semper procedat. Denique idem sentiunt omnes qui in + his operibus veram successionem et temporalem distinctionem agnoscant." + </p> + <p> + Secondly, with respect to animals, Suarez is no less decided:-- + </p> + <p> + "<i>De animalium ratione carentium productione quinto et sexto die facta</i>. + [*] + </p> + <ol class="footnotes"> + <li> + <i>Loc. cit</i>. Lib. II. cap. vii. et viii. 1, 32, 35. + </li> + </ol> + <p> + "32. Primo ergo nobis certum sit hæc animantia non in virtute tantum + aut in semine, sed actu, et in seipsis, facta fuisse his diebus in quibus + facta narrantur. Quanquam Augustinus lib. 3, Gen. ad liter, cap. 5 in sua + persistens sententia contrarium sentire videatur." + </p> + <p> + But Suarez proceeds to refute Augustin's opinions at great length, and his + final judgment may be gathered from the following passage:-- + </p> + <p> + "35. Tertio dicendum est, hæc animalia omnia his diebus producta + esse, IN PERFECTO STATU, IN SINGULIS INDIVIDUIS, SEU SPECIEBUS SUIS, JUXTA + UNIUSCUJUSQUE NATURAM.... ITAQUE FUERUNT OMNIA CREATA INTEGRA ET OMNIBUS + SUIS MEMBRIS PERFECTA." + </p> + <p> + As regards the creation of animals and plants, therefore, it is clear that + Suarez, so far from "distinctly asserting derivative creating," denies it + as distinctly and positively as he can; that he is at much pains to refute + St. Augustin's opinions; that he does not hesitate to regard the faint + acquiescence of St. Thomas Aquinas in the views of his brother saint as a + kindly subterfuge on the part of Divus Thomas; and that he affirms his own + view to be that which is supported by the authority of the Fathers of the + Church. So that, when Mr. Mivart tells us that Catholic theology is in + harmony with all that modern science can possibly require; that "to the + general theory of evolution, and to the special Darwinian form of it, no + exception ... need be taken on the ground of orthodoxy;" and that "law and + regularity, not arbitrary intervention, was the Patristic ideal of + creation," we have to choose between his dictum, as a theologian, and that + of a great light of his Church, whom he himself declares to be "widely + venerated as an authority, and whose orthodoxy has never been questioned." + </p> + <p> + But Mr. Mivart does not hesitate to push his attempt to harmonise science + with Catholic orthodoxy to its utmost limit; and, while assuming that the + soul of man "arises from immediate and direct creation," he supposes that + his body was "formed at first (as now in each separate individual) by + derivative, or secondary creation, through natural laws" (p. 331). + </p> + <p> + This means, I presume, that an animal, having the corporeal form and + bodily powers of man, may have been developed out of some lower form of + life by a process of evolution; and that, after this anthropoid animal had + existed for a longer or shorter time, God made a soul by direct creation, + and put it into the manlike body, which, heretofore, had been devoid of + that <i>anima rationalis</i>, which is supposed to be man's distinctive + character. + </p> + <p> + This hypothesis is incapable of either proof or disproof, and therefore + may be true; but if Suarez is any authority, it is not Catholic doctrine. + "Nulla est in homine forma educta de potentia materiæ," [*] is a + dictum which is absolutely inconsistent with the doctrine of the natural + evolution of any vital manifestation of the human body. + </p> + <ol class="footnotes"> + <li> + Disput. xv. § x. No. 27. + </li> + </ol> + <p> + Moreover, if man existed as an animal before he was provided with a + rational soul, he must, in accordance with the elementary requirements of + the philosophy in which Mr. Mivart delights, have possessed a distinct + sensitive and vegetative soul, or souls. Hence, when the "breath of life" + was breathed into the manlike animal's nostrils, he must have already been + a living and feeling creature. But Suarez particularly discusses this + point, and not only rejects Mr. Mivart's view, but adopts language of very + theological strength regarding it. + </p> + <p> + "Possent præterea his adjungi argumenta theologica, ut est illud + quod sumitur ex illis verbis Genes. 2. <i>Formavit Deus hominem ex limo + terræ et inspiravit in faciem ejus spiraculum vitæ et factus + est homo in animam viventem</i>: ille enim spiritus, quam Deus spiravit, + anima rationalis fuit, et PER EADEM FACTUS EST HOMO VIVENS, ET + CONSQUENTER, ETIAM SENTIENS. + </p> + <p> + "Aliud est ex VIII. Synodo Generali quæ est Constantinopolitana IV. + can. 11, qui sic habet. <i>Apparet quosdam in tantum impietatis venisse ut + homines duas animas habere dogmatizent: talis igitur impietatis inventores + et similes sapientes, cum Vetus et Novum Testamentum omnesque Ecclesiæ + patres unam animam rationalem hominem habere asseverent, Sancta et + universalis Synodus anathematizat</i>." [*] + </p> + <ol class="footnotes"> + <li> + Disput. xv. "De causa formali substantiali," § x. No. 24. + </li> + </ol> + <p> + Moreover, if the animal nature of man was the result of evolution, so must + that of woman have been. But the Catholic doctrine, according to Suarez, + is that woman was, in the strictest and most literal sense of the words, + made out of the rib of man. + </p> + <p> + "Nihilominus sententia Catholica est, verba illa Scripturæ esse ad + literam intelligenda. AC PROINDE VERE, AC REALITER, TULISSE DEUM COSTAM + ADAMÆ, ET, EX ILLA, CORPUS EVÆ FORMASSE." [*] + </p> + <ol class="footnotes"> + <li> + <i>Tractatus de Opere</i>, Lib. III. "De hominis creatione," cap. ii. + No. 3. + </li> + </ol> + <p> + Nor is there any escape in the supposition that some woman existed before + Eve, after the fashion of the Lilith of the rabbis; since Suarez qualifies + that notion, along with some other Judaic imaginations, as simply + "damnabilis." [*] + </p> + <ol class="footnotes"> + <li> + <i>Ibid</i>. Lib. III. cap. iv. Nos. 8 and 9 + </li> + </ol> + <p> + After the perusal of the "Tractatus de Opere" it is, in fact, impossible + to admit that Suarez held any opinion respecting the origin of species, + except such as is consistent with the strictest and most literal + interpretation of the words of Genesis. For Suarez, it is Catholic + doctrine, that the world was made in six natural days. On the first of + these days the <i>materia prima</i> was made out of nothing, to receive + afterwards those "substantial forms" which moulded it into the universe of + things; on the third day, the ancestors of all living plants suddenly came + into being, full-grown, perfect, and possessed of all the properties which + now distinguish them; while, on the fifth and sixth days, the ancestors of + all existing animals were similarly caused to exist in their complete and + perfect state, by the infusion of their appropriate material substantial + forms into the matter which had already been created. Finally, on the + sixth day, the <i>anima rationalis</i>--that rational and immortal + substantial form which is peculiar to man--was created out of nothing, and + "breathed into" a mass of matter which, till then, was mere dust of the + earth, and so man arose. But the species man was represented by a solitary + male individual, until the Creator took out one of his ribs and fashioned + it into a female. + </p> + <p> + This is the view of the "Genesis of Species" held by Suarez to be the only + one consistent with Catholic faith: it is because he holds this view to be + Catholic that he does not hesitate to declare St. Augustin unsound, and + St. Thomas Aquinas guilty of weakness, when the one swerved from this view + and the other tolerated the deviation. And, until responsible Catholic + authority--say, for example, the Archbishop of Westminster--formally + declares that Suarez was wrong, and that Catholic priests are free to + teach their flocks that the world was <i>not</i> made in six natural days, + and that plants and animals were <i>not</i> created in their perfect and + complete state, but have been evolved by natural processes through long + ages from certain germs in which they were potentially contained, I, for + one, shall feel bound to believe that the doctrines of Suarez are the only + ones which are sanctioned by Infallible Authority, as represented by the + Holy Father and the Catholic Church. + </p> + <p> + I need hardly add that they are as absolutely denied and repudiated by + Scientific Authority, as represented by Reason and Fact. The question + whether the earth and the immediate progenitors of its present living + population were made in six natural days or not is no longer one upon + which two opinions can be held. + </p> + <p> + The fact that it did not so come into being stands upon as sound a basis + as any fact of history whatever. It is not true that existing plants and + animals came into being within three days of the creation of the earth out + of nothing, for it is certain that innumerable generations of other plants + and animals lived upon the earth before its present population. And when, + Sunday after Sunday, men who profess to be our instructors in + righteousness read out the statement, "In six days the Lord made heaven + and earth, the sea, and all that in them is," in innumerable churches, + they are either propagating what they may easily know, and, therefore, are + bound to know, to be falsities; or, if they use the words in some + non-natural sense, they fall below the moral standard of the much-abused + Jesuit. + </p> + <p> + Thus far the contradiction between Catholic verity and Scientific verity + is complete and absolute, quite independently of the truth or falsehood of + the doctrine of evolution. But, for those who hold the doctrine of + evolution, all the Catholic verities about the creation of living beings + must be no less false. For them, the assertion that the progenitors of all + existing plants were made on the third day, of animals on the fifth and + sixth days, in the forms they now present, is simply false. Nor can they + admit that man was made suddenly out of the dust of the earth; while it + would be an insult to ask an evolutionist whether he credits the + preposterous fable respecting the fabrication of woman to which Suarez + pins his faith. If Suarez has rightly stated Catholic doctrine, then is + evolution utter heresy. And such I believe it to be. In addition to the + truth of the doctrine of evolution, indeed, one of its greatest merits in + my eyes, is the fact that it occupies a position of complete and + irreconcilable antagonism to that vigorous and consistent enemy of the + highest intellectual, moral, and social life of mankind--the Catholic + Church. No doubt, Mr. Mivart, like other putters of new wine into old + bottles, is actuated by motives which are worthy of respect, and even of + sympathy; but his attempt has met with the fate which the Scripture + prophesies for all such. + </p> + <p> + Catholic theology, like all theologies which are based upon the assumption + of the truth of the account of the origin of things given in the Book of + Genesis, being utterly irreconcilable with the doctrine of evolution, the + student of science, who is satisfied that the evidence upon which the + doctrine of evolution rests, is incomparably stronger and better than that + upon which the supposed authority of the Book of Genesis rests, will not + trouble himself further with these theologies, but will confine his + attention to such arguments against the view he holds as are based upon + purely scientific data--and by scientific data I do not merely mean the + truths of physical, mathematical, or logical science, but those of moral + and metaphysical science. For by science I understand all knowledge which + rests upon evidence and reasoning of a like character to that which claims + our assent to ordinary scientific propositions. And if any one is able to + make good the assertion that his theology rests upon valid evidence and + sound reasoning, then it appears to me that such theology will take its + place as a part of science. + </p> + <p> + The present antagonism between theology and science does not arise from + any assumption by the men of science that all theology must necessarily be + excluded from science, but simply because they are unable to allow that + reason and morality have two weights and two measures; and that the belief + in a proposition, because authority tells you it is true, or because you + wish to believe it, which is a high crime and misdemeanour when the + subject matter of reasoning is of one kind, becomes under the <i>alias</i> + of "faith" the greatest of all virtues when the subject matter of + reasoning is of another kind. + </p> + <p> + The Bishop of Brechin said well the other day:--"Liberality in religion--I + do not mean tender and generous allowances for the mistakes of others--is + only unfaithfulness to truth." [*] And, with the same qualification, I + venture to paraphrase the Bishop's dictum: "Ecclesiasticism in science is + only unfaithfulness to truth." + </p> + <ol class="footnotes"> + <li> + Charge at the Diocesan Synod of Brechin. <i>Scotsman</i>, Sept. 14, + 1871. + </li> + </ol> + <p> + Elijah's great question, "Will you serve God or Baal? Choose ye," is + uttered audibly enough in the ears of every one of us as we come to + manhood. Let every man who tries to answer it seriously ask himself + whether he can be satisfied with the Baal of authority, and with all the + good things his worshippers are promised in this world and the next. If he + can, let him, if he be so inclined, amuse himself with such scientific + implements as authority tells him are safe and will not cut his fingers; + but let him not imagine he is, or can be, both a true son of the Church + and a loyal soldier of science. + </p> + <p> + And, on the other hand, if the blind acceptance of authority appears to + him in its true colours, as mere private judgment <i>in excelsis</i>, and + if he have the courage to stand alone, face to face with the abyss of the + eternal and unknowable, let him be content, once for all, not only to + renounce the good things promised by "Infallibility," but even to bear the + bad things which it prophesies; content to follow reason and fact in + singleness and honesty of purpose, wherever they may lead, in the sure + faith that a hell of honest men will, to him, be more endurable than a + paradise full of angelic shams. + </p> + <p> + Mr. Mivart asserts that "without a belief in a personal God there is no + religion worthy of the name." This is a matter of opinion. But it may be + asserted, with less reason to fear contradiction, that the worship of a + personal God, who, on Mr. Mivart's hypothesis, must have used language + studiously calculated to deceive His creatures and worshippers, is "no + religion worthy of the name." "Incredible est, Deum illis verbis ad + populum fuisse locutum quibus deciperetur," is a verdict in which, for + once, Jesuit casuistry concurs with the healthy moral sense of all + mankind. + </p> + <p> + Having happily got quit of the theological aspect of evolution, the + supporter of that great truth who turns to the scientific objections which + are brought against it by recent criticism, finds, to his relief, that the + work before him is greatly lightened by the spontaneous retreat of the + enemy from nine-tenths of the territory which he occupied ten years ago. + Even the Quarterly Reviewer not only abstains from venturing to deny that + evolution has taken place, but he openly admits that Mr. Darwin has forced + on men's minds "a recognition of the probability, if not more, of + evolution, and of the certainty of the action of natural selection" (p. + 49). + </p> + <p> + I do not quite see, myself, how, if the action of natural selection is <i>certain</i>, + the occurrence of evolution is only <i>probable</i>; inasmuch as the + development of a new species by natural selection is, so far as it goes, + evolution. However, it is not worth while to quarrel with the precise + terms of a sentence which shows that the high water mark of intelligence + among those most respectable of Britons, the readers of the <i>Quarterly + Review</i>, has now reached such a level that the next tide may lift them + easily and pleasantly on the once-dreaded shore of evolution. Nor, having + got there, do they seem likely to stop, until they have reached the inmost + heart of that great region, and accepted the ape ancestry of, at any rate, + the body of man. For the Reviewer admits that Mr. Darwin can be said to + have established: + </p> + <p> + "That if the various kinds of lower animals have been evolved one from the + other by a process of natural generation or evolution, then it becomes + highly probable, <i>a priori</i>, that man's body has been similarly + evolved; but this, in such a case, becomes equally probable from the + admitted fact that he is an animal at all" (p. 65). + </p> + <p> + From the principles laid down in the last sentence it would follow that if + man were constructed upon a plan as different from that of any other + animal as that of a sea-urchin is from that of a whale, it would be + "equally probable" that he had been developed from some other animal as it + is now, when we know that for every bone, muscle, tooth, and even pattern + of tooth, in man, there is a corresponding bone, muscle, tooth, and + pattern of tooth, in an ape. And this shows one of two things--either that + the Quarterly Reviewer's notions of probability are peculiar to himself, + or that he has such an overpowering faith in the truth of evolution that + no extent of structural break between one animal and another is sufficient + to destroy his conviction that evolution has taken place. + </p> + <p> + But this by the way. The importance of the admission that there is nothing + in man's physical structure to interfere with his having been evolved from + an ape is not lessened because it is grudgingly made and inconsistently + qualified. And instead of jubilating over the extent of the enemy's + retreat, it will be more worth while to lay siege to his last + stronghold--the position that there is a distinction in kind between the + mental faculties of man and those of brutes, and that in consequence of + this distinction in kind no gradual progress from the mental faculties of + the one to those of the other can have taken place. + </p> + <p> + The Quarterly Reviewer entrenches himself within formidable-looking + psychological outworks, and there is no getting at him without attacking + them one by one. + </p> + <p> + He begins by laying down the following proposition. "'Sensation' is not + 'thought,' and no amount of the former would constitute the most + rudimentary condition of the latter, though sensations supply the + conditions for the existence of 'thought' or 'knowledge'" (p. 67). + </p> + <p> + This proposition is true, or not, according to the sense in which the word + "thought" is employed. Thought is not uncommonly used in a sense + co-extensive with consciousness, and, especially, with those states of + consciousness we call memory. If I recall the impression made by a colour + or an odour, and distinctly remember blueness or muskiness, I may say with + perfect propriety that I "think of" blue or musk; and, so long as the + thought lasts, it is simply a faint reproduction of the state of + consciousness to which I gave the name in question, when it first became + known to me as a sensation. + </p> + <p> + Now, if that faint reproduction of a sensation, which we call the memory + of it, is properly termed a thought, it seems to me to be a somewhat + forced proceeding to draw a hard and fast line of demarcation between + thoughts and sensations. If sensations are not rudimentary thoughts, it + may be said that some thoughts are rudimentary sensations. No amount of + sound constitutes an echo, but for all that no one would pretend that an + echo is something of totally different nature from a sound. Again, nothing + can be looser, or more inaccurate, than the assertion that "sensations + supply the conditions for the existence of thought or knowledge." If this + implies that sensations supply the conditions for the existence of our + memory of sensations or of our thoughts about sensations, it is a truism + which it is hardly worth while to state so solemnly. If it implies that + sensations supply anything else, it is obviously erroneous. And if it + means, as the context would seem to show it does, that sensations are the + subject-matter of all thought or knowledge, then it is no less contrary to + fact, inasmuch as our emotions, which constitute a large part of the + subject-matter of thought or of knowledge, are not sensations. + </p> + <p> + More eccentric still is the Quarterly Reviewer's next piece of psychology. + </p> + <p> + "Altogether, we may clearly distinguish at least six kinds of action to + which the nervous system ministers:-- + </p> + <p> + "I. That in which impressions received result in appropriate movements + without the intervention of sensation or thought, as in the cases of + injury above given.--This is the reflex action of the nervous system. + </p> + <p> + "II. That in which stimuli from without result in sensations through the + agency of which their due effects are wrought out.--Sensation. + </p> + <p> + "III. That in which impressions received result in sensations which give + rise to the observation of sensible objects.--Sensible perception. + </p> + <p> + "IV. That in which sensations and perceptions continue to coalesce, + agglutinate, and combine in more or less complex aggregations, according + to the laws of the association of sensible perceptions.--Association. + </p> + <p> + "The above four groups contain only indeliberate operations, consisting, + as they do at the best, but of mere <i>presentative</i> sensible ideas in + no way implying any reflective or <i>representative</i> faculty. Such + actions minister to and form <i>Instinct</i>. Besides these, we may + distinguish two other kinds of mental action, namely:-- + </p> + <p> + "V. That in which sensations and sensible perceptions are reflected on by + thought, and recognised as our own, and we ourselves recognised by + ourselves as affected and perceiving.--Self-consciousness. + </p> + <p> + "VI. That in which we reflect upon our sensations or perceptions, and ask + what they are, and why they are.--Reason. + </p> + <p> + "These two latter kinds of action are deliberate operations, performed, as + they are, by means of representative ideas implying the use of a <i>reflective + representative</i> faculty. Such actions distinguish the <i>intellect</i> + or rational faculty. Now, we assert that possession in perfection of all + the first four (<i>presentative</i>) kinds of action by no means implies + the possession of the last two (<i>representative</i>) kinds. All persons, + we think, must admit the truth of the following proposition:-- + </p> + <p> + "Two faculties are distinct, not in degree but <i>in kind</i>, if we may + possess the one in perfection without that fact implying that we possess + the other also. Still more will this be the case if the two faculties tend + to increase in an inverse ratio. Yet this is the distinction between the + <i>instinctive</i> and the <i>intellectual</i> parts of man's nature. + </p> + <p> + "As to animals, we fully admit that they may possess all the first four + groups of actions--that they may have, so to speak, mental images of + sensible objects combined in all degrees of complexity, as governed by the + laws of association. We deny to them, on the other hand, the possession of + the last two kinds of mental action. We deny them, that is, the power of + reflecting on their own existences, or of inquiring into the nature of + objects and their causes. We deny that they know that they know or know + themselves in knowing. In other words, we deny them <i>reason</i>. The + possession of the presentative faculty, as above explained, in no way + implies that of the reflective faculty; nor does any amount of direct + operation imply the power of asking the reflective question before + mentioned, as to 'what' and 'why.'" (<i>Loc. cit</i>. pp. 67, 68.) + </p> + <p> + Sundry points are worthy of notice in this remarkable account of the + intellectual powers. In the first place the Reviewer ignores emotion and + volition, though they are no inconsiderable "kinds of action to which the + nervous system ministers," and memory has a place in his classification + only by implication. Secondly, we are told that the second "kind of action + to which the nervous system ministers" is "that in which stimuli from + without result in sensations through the agency of which their due effects + are wrought out.--Sensation." Does this really mean that, in the writer's + opinion, "sensation" is the "agent" by which the "due effect" of the + stimulus, which gives rise to sensation, is "wrought out"? Suppose + somebody runs a pin into me. The "due effect" of that particular stimulus + will probably be threefold; namely, a sensation of pain, a start, and an + interjectional expletive. Does the Quarterly Reviewer really think that + the "sensation" is the "agent" by which the other two phenomena are + wrought out? + </p> + <p> + But these matters are of little moment to anyone but the Reviewer and + those persons who may incautiously take their physiology, or psychology, + from him. The really interesting point is this, that when he fully admits + that animals "may possess all the first four groups of actions," he grants + all that is necessary for the purposes of the evolutionist. For he hereby + admits that in animals "impressions received result in sensations which + give rise to the observation of sensible objects," and that they have what + he calls "sensible perception." Nor was it possible to help the admission; + for we have as much reason to ascribe to animals, as we have to attribute + to our fellow-men, the power, not only of perceiving external objects as + external, and thus practically recognizing the difference between the self + and the not-self; but that of distinguishing between like and unlike, and + between simultaneous and successive things. When a gamekeeper goes out + coursing with a greyhound in leash, and a hare crosses the field of + vision, he becomes the subject of those states of consciousness we call + visual sensation, and that is all he receives from without. Sensation, as + such, tells him nothing whatever about the cause of these states of + consciousness; but the thinking faculty instantly goes to work upon the + raw material of sensation furnished to it through the eye, and gives rise + to a train of thoughts. First comes the thought that there is an object at + a certain distance; then arises another thought--the perception of the + likeness between the states of consciousness awakened by this object to + those presented by memory, as, on some former occasion, called up by a + hare; this is succeeded by another thought of the nature of an + emotion--namely, the desire to possess the hare; then follows a longer or + shorter train of other thoughts, which end in a volition and an act--the + loosing of the greyhound from the leash. These several thoughts are the + concomitants of a process which goes on in the nervous system of the man. + Unless the nerve-elements of the retina, of the optic nerve, of the brain, + of the spinal cord, and of the nerves of the arms, went through certain + physical changes in due order and correlation, the various states of + consciousness which have been enumerated would not make their appearance. + So that in this, as in all other intellectual operations, we have to + distinguish two sets of successive changes--one in the physical basis of + consciousness, and the other in consciousness itself; one set which may, + and doubtless will, in course of time, be followed through all their + complexities by the anatomist and the physicist, and one of which only the + man himself can have immediate knowledge. + </p> + <p> + As it is very necessary to keep up a clear distinction between these two + processes, let the one be called <i>neurosis</i>, and the other <i>psychosis</i>. + When the gamekeeper was first trained to his work every step in the + process of neurosis was accompanied by a corresponding step in that of + psychosis, or nearly so. He was conscious of seeing something, conscious + of making sure it was a hare, conscious of desiring to catch it, and + therefore to loose the greyhound at the right time, conscious of the acts + by which he let the dog out of the leash. But with practice, though the + various steps of the neurosis remain--for otherwise the impression on the + retina would not result in the loosing of the dog--the great majority of + the steps of the psychosis vanish, and the loosing of the dog follows + unconsciously, or as we say, without thinking about it, upon the sight of + the hare. No one will deny that the series of acts which originally + intervened between the sensation and the letting go of the dog were, in + the strictest sense, intellectual and rational operations. Do they cease + to be so when the man ceases to be conscious of them? That depends upon + what is the essence and what the accident of those operations, which, + taken together, constitute ratiocination. + </p> + <p> + Now ratiocination is resolvable into predication, and predication consists + in marking, in some way, the existence, the co-existence, the succession, + the likeness and unlikeness, of things or their ideas. Whatever does this, + reasons; and if a machine produces the effects of reason, I see no more + ground for denying to it the reasoning power, because it is unconscious, + than I see for refusing to Mr. Babbage's engine the title of a calculating + machine on the same grounds. + </p> + <p> + Thus it seems to me that a gamekeeper reasons, whether he is conscious or + unconscious, whether his reasoning is carried on by neurosis alone, or + whether it involves more or less psychosis. And if this is true of the + gamekeeper, it is also true of the greyhound. The essential resemblances + in all points of structure and function, so far as they can be studied, + between the nervous system of the man and that of the dog, leave no + reasonable doubt that the processes which go on in the one are just like + those which take place in the other. In the dog, there can be no doubt + that the nervous matter which lies between the retina and the muscles + undergoes a series of changes, precisely analogous to those which, in the + man, give rise to sensation, a train of thought, and volition. + </p> + <p> + Whether this neurosis is accompanied by such psychosis as ours it is + impossible to say; but those who deny that the nervous changes, which, in + the dog, correspond with those which underlie thought in a man, are + accompanied by consciousness, are equally bound to maintain that those + nervous changes in the dog, which correspond with those which underlie + sensation in a man, are also unaccompanied by consciousness. In other + words, if there is no ground for believing that a dog thinks, neither is + there any for believing that he feels. + </p> + <p> + As is well known, Descartes boldly faced this dilemma, and maintained that + all animals were mere machines and entirely devoid of consciousness. But + he did not deny, nor can anyone deny, that in this case they are reasoning + machines, capable of performing all those operations which are performed + by the nervous system of man when he reasons. For even supposing that in + man, and in man only, psychosis is superadded to neurosis--the neurosis + which is common to both man and animal gives their reasoning processes a + fundamental unity. But Descartes' position is open to very serious + objections if the evidence that animals feel is insufficient to prove that + they really do so. What is the value of the evidence which leads one to + believe that one's fellow-man feels? The only evidence in this argument of + analogy is the similarity of his structure and of his actions to one's + own. And if that is good enough to prove that one's fellow-man feels, + surely it is good enough to prove that an ape feels. For the differences + of structure and function between men and apes are utterly insufficient to + warrant the assumption that while men have those states of consciousness + we call sensations apes have nothing of the kind. Moreover, we have as + good evidence that apes are capable of emotion and volition as we have + that men other than ourselves are. But if apes possess three out of the + four kinds of states of consciousness which we discover in ourselves, what + possible reason is there for denying them the fourth? If they are capable + of sensation, emotion, and volition, why are they to be denied thought (in + the sense of predication)? + </p> + <p> + No answer has ever been given to these questions. And as the law of + continuity is as much opposed, as is the common sense of mankind, to the + notion that all animals are unconscious machines, it may safely be assumed + that no sufficient answer ever will be given to them. + </p> + <p> + There is every reason to believe that consciousness is a function of + nervous matter, when that nervous matter has attained a certain degree of + organisation, just as we know the other "actions to which the nervous + system ministers," such as reflex action and the like, to be. As I have + ventured to state my view of the matter elsewhere, "our thoughts are the + expression of molecular changes in that matter of life which is the source + of our other vital phenomena." + </p> + <p> + Mr. Wallace objects to this statement in the following terms:-- + </p> + <p> + "Not having been able to find any clue in Professor Huxley's writings to + the steps by which he passes from those vital phenomena, which consist + only, in their last analysis, of movements by particles of matter, to + those other phenomena which we term thought, sensation, or consciousness; + but, knowing that so positive an expression of opinion from him will have + great weight with many persons, I shall endeavour to show, with as much + brevity as is compatible with clearness, that this theory is not only + incapable of proof, but is also, as it appears to me, inconsistent with + accurate conceptions of molecular physics." + </p> + <p> + With all respect for Mr. Wallace, it appears to me that his remarks are + entirely beside the question. I really know nothing whatever, and never + hope to know anything, of the steps by which the passage from molecular + movement to states of consciousness is effected; and I entirely agree with + the sense of the passage which he quotes from Professor Tyndall, + apparently imagining that it is in opposition to the view I hold. + </p> + <p> + All that I have to say is, that, in my belief, consciousness and molecular + action are capable of being expressed by one another, just as heat and + mechanical action are capable of being expressed in terms of one another. + Whether we shall ever be able to express consciousness in foot-pounds, or + not, is more than I will venture to say; but that there is evidence of the + existence of some correlation between mechanical motion and consciousness, + is as plain as anything can be. Suppose the poles of an electric battery + to be connected by a platinum wire. A certain intensity of the current + gives rise in the mind of a bystander to that state of consciousness we + call a "dull red light"--a little greater intensity to another which we + call a "bright red light;" increase the intensity, and the light becomes + white; and, finally, it dazzles, and a new state of consciousness arises, + which we term pain. Given the same wire and the same nervous apparatus, + and the amount of electric force required to give rise to these several + states of consciousness will be the same, however often the experiment is + repeated. And as the electric force, the light waves, and the + nerve-vibrations caused by the impact of the light-waves on the retina, + are all expressions of the molecular changes which are taking place in the + elements of the battery; so consciousness is, in the same sense, an + expression of the molecular changes which take place in that nervous + matter, which is the organ of consciousness. + </p> + <p> + And, since this, and any number of similar examples that may be required, + prove that one form of consciousness, at any rate, is, in the strictest + sense, the expression of molecular change, it really is not worth while to + pursue the inquiry, whether a fact so easily established is consistent + with any particular system of molecular physics or not. + </p> + <p> + Mr. Wallace, in fact, appears to me to have mixed up two very distinct + propositions: the one, the indisputable truth that consciousness is + correlated with molecular changes in the organ of consciousness; the + other, that the nature of that correlation is known, or can be conceived, + which is quite another matter. Mr. Wallace, presumably, believes in that + correlation of phenomena which we call cause and effect as firmly as I do. + But if he has ever been able to form the faintest notion how a cause gives + rise to its effect, all I can say is that I envy him. Take the simplest + case imaginable--suppose a ball in motion to impinge upon another ball at + rest. I know very well, as a matter of fact, that the ball in motion will + communicate some of its motion to the ball at rest, and that the motion of + the two balls, after collision, is precisely correlated with the masses of + both balls and the amount of motion of the first. But how does this come + about? In what manner can we conceive that the <i>vis viva</i> of the + first ball passes into the second? I confess I can no more form any + conception of what happens in this case, than I can of what takes place + when the motion of particles of my nervous matter, caused by the impact of + a similar ball gives rise to the state of consciousness I call pain. In + ultimate analysis everything is incomprehensible, and the whole object of + science is simply to reduce the fundamental incomprehensibilities to the + smallest possible number. + </p> + <p> + But to return to the Quarterly Reviewer. He admits that animals have + "mental images of sensible objects, combined in all degrees of complexity, + as governed by the laws of association." Presumably, by this confused and + imperfect statement the Reviewer means to admit more than the words imply. + For mental images of sensible objects, even though "combined in all + degrees of complexity," are, and can be, nothing more than mental images + of sensible objects. But judgments, emotions, and volitions cannot by any + possibility be included under the head of "mental images of sensible + objects." If the greyhound had no better mental endowment than the + Reviewer allows him, he might have the "mental image" of the "sensible + object"--the hare--and that might be combined with the mental images of + other sensible objects, to any degree of complexity, but he would have no + power of judging it to be at a certain distance from him; no power of + perceiving its similarity to his memory of a hare; and no desire to get at + it. Consequently he would stand stock still, and the noble art of coursing + would have no existence. On the other hand, as that art is largely + practised, it follows that greyhounds alone possess a number of mental + powers, the existence of which, in any animal, is absolutely denied by the + Quarterly Reviewer. + </p> + <p> + Finally, what are the mental powers which he reserves as the especial + prerogative of man? They are two. First, the recognition of "ourselves by + ourselves as affected and perceiving.--Self-consciousness." + </p> + <p> + Secondly. "The reflection upon our sensations and perceptions, and asking + what they are and why they are.--Reason." + </p> + <p> + To the faculty defined in the last sentence, the Reviewer, without + assigning the least ground for thus departing from both common usage and + technical propriety, applies the name of reason. But if man is not to be + considered a reasoning being, unless he asks what his sensations and + perceptions are, and why they are, what is a Hottentot, or an Australian + "black-fellow"; or what the "swinked hedger" of an ordinary agricultural + district? Nay, what becomes of an average country squire or parson? How + many of these worthy persons who, as their wont is, read the <i>Quarterly + Review</i>, would do other than stand agape, if you asked them whether + they had ever reflected what their sensations and perceptions are and why + they are? + </p> + <p> + So that if the Reviewer's new definition of reason be correct, the + majority of men, even among the most civilised nations, are devoid of that + supreme characteristic of manhood. And if it be as absurd as I believe it + to be, then, as reason is certainly not self-consciousness, and since it, + as certainly, is one of the "actions to which the nervous system + ministers," we must, if the Reviewer's classification is to be adopted, + seek it among those four faculties which he allows animals to possess. And + thus, for the second time, he really surrenders, while seeming to defend, + his position. + </p> + <p> + The Quarterly Reviewer, as we have seen, lectures the evolutionists upon + their want of knowledge of philosophy altogether. Mr. Mivart is not less + pained at Mr. Darwin's ignorance of moral science. It is grievous to him + that Mr. Darwin (and <i>nous autres</i>) should not have grasped the + elementary distinction between material and formal morality; and he lays + down as an axiom, of which no tyro ought to be ignorant, the position that + "acts, unaccompanied by mental acts of conscious will directed towards the + fulfilment of duty," are "absolutely destitute of the most incipient + degree of real or formal goodness." + </p> + <p> + Now this may be Mr. Mivart's opinion, but it is a proposition which really + does not stand on the footing of an undisputed axiom. Mr. Mill denies it + in his work on Utilitarianism. The most influential writer of a totally + opposed school, Mr. Carlyle, is never weary of denying it, and upholding + the merit of that virtue which is unconscious; nay, it is, to my + understanding, extremely hard to reconcile Mr. Mivart's dictum with that + noble summary of the whole duty of man--"Thou shalt love the Lord thy God + with all thy heart, and with all thy soul, and with all thy strength; and + thou shalt love thy neighbour as thyself." According to Mr. Mivart's + definition, the man who loves God and his neighbour, and, out of sheer + love and affection for both, does all he can to please them, is, + nevertheless, destitute of a particle of real goodness. + </p> + <p> + And it further happens that Mr. Darwin, who is charged by Mr. Mivart with + being ignorant of the distinction between material and formal goodness, + discusses the very question at issue in a passage which is well worth + reading (vol. i. p. 87), and also comes to a conclusion opposed to Mr. + Mivart's axiom. A proposition which has been so much disputed and + repudiated, should, under no circumstances, have been thus confidently + assumed to be true. For myself, I utterly reject it, inasmuch as the + logical consequence of the adoption of any such principle is the denial of + all moral value to sympathy and affection. According to Mr. Mivart's + axiom, the man who, seeing another struggling in the water, leaps in at + the risk of his own life to save him, does that which is "destitute of the + most incipient degree of real goodness," unless, as he strips off his + coat, he says to himself, "Now, mind, I am going to do this because it is + my duty and for no other reason;" and the most beautiful character to + which humanity can attain, that of the man who does good without thinking + about it, because he loves justice and mercy and is repelled by evil, has + no claim on our moral approbation. The denial that a man acts morally + because he does not think whether he does so or not, may be put upon the + same footing as the denial of the title of an arithmetician to the + calculating boy, because he did not know how he worked his sums. If + mankind ever generally accept and act upon Mr. Mivart's axiom, they will + simply become a set of most unendurable prigs; but they never have + accepted it, and I venture to hope that evolution has nothing so terrible + in store for the human race. + </p> + <p> + But if an action, the motive of which is nothing but affection or + sympathy, may be deserving of moral approbation and really good, who that + has ever had a dog of his own will deny that animals are capable of such + actions? Mr. Mivart indeed says:--"It may be safely affirmed, however, + that there is no trace in brutes of any actions simulating morality which + are not explicable by the fear of punishment, by the hope of pleasure, or + by personal affection" (p. 221). But it may be affirmed, with equal truth, + that there is no trace in men of any actions which are not traceable to + the same motives. If a man does anything, he does it either because he + fears to be punished if he does not do it, or because he hopes to obtain + pleasure by doing it, or because he gratifies his affections [*] by doing + it. + </p> + <ol class="footnotes"> + <li> + In separating pleasure and the gratification of affection, I simply + follow Mr. Mivart without admitting the justice of the separation. + </li> + </ol> + <p> + Assuming the position of the absolute moralists, let it be granted that + there is a perception of right and wrong innate in every man. This means, + simply, that when certain ideas are presented to his mind, the feeling of + approbation arises; and when certain others, the feeling of + disapprobation. To do your duty is to earn the approbation of your + conscience, or moral sense; to fail in your duty is to feel its + disapprobation, as we all say. Now, is approbation a pleasure or a pain? + Surely a pleasure. And is disapprobation a pleasure or a pain? Surely a + pain. Consequently, all that is really meant by the absolute moralists is + that there is, in the very nature of man, something which enables him to + be conscious of these particular pleasures and pains. And when they talk + of immutable and eternal principles of morality, the only intelligible + sense which I can put upon the words, is that the nature of man being what + it is, he always has been, and always will be, capable of feeling these + particular pleasures and pains. <i>À priori,</i> I have nothing to + say against this proposition. Admitting its truth, I do not see how the + moral faculty is on a different footing from any of the other faculties of + man. If I choose to say that it is an immutable and eternal law of human + nature that "ginger is hot in the mouth," the assertion has as much + foundation of truth as the other, though I think it would be expressed in + needlessly pompous language. I must confess that I have never been able to + understand why there should be such a bitter quarrel between the + intuitionists and the utilitarians. The intuitionist is, after all, only a + utilitarian who believes that a particular class of pleasures and pains + has an especial importance, by reason of its foundation in the nature of + man, and its inseparable connection with his very existence as a thinking + being. And as regards the motive of personal affection: Love, as Spinoza + profoundly says, is the association of pleasure with that which is loved. + [*] Or, to put it to the common sense of mankind, is the gratification of + affection a pleasure or a pain? Surely a pleasure. So that whether the + motive which leads us to perform an action is the love of our neighbour, + or the love of God, it is undeniable that pleasure enters into that + motive. + </p> + <ol class="footnotes"> + <li> + "Nempe, Amor nihil aliud est, quam Lætitia, concomitante idea causæ + externæ."--<i>Ethices</i>, III. xiii. + </li> + </ol> + <p> + Thus much in reply to Mr. Mivart's arguments. I cannot but think that it + is to be regretted that he ekes them out by ascribing to the doctrines of + the philosophers with whom he does not agree, logical consequences which + have been over and over again proved not to flow from them: and when + reason fails him, tries the effect of an injurious nickname. According to + the views of Mr. Spencer, Mr. Mill, and Mr. Darwin, Mr. Mivart tells us, "<i>virtue + is a mere kind of retrieving:</i>" and, that we may not miss the point of + the joke, he puts it in italics. But what if it is? Does that make it less + virtue? Suppose I say that sculpture is a "mere way" of stone-cutting, and + painting a "mere way" of daubing canvas, and music a "mere way" of making + a noise, the statements are quite true; but they only show that I see no + other method of depreciating some of the noblest aspects of humanity than + that of using language in an inadequate and misleading sense about them. + And the peculiar inappropriateness of this particular nickname to the + views in question, arises from the circumstance which Mr. Mivart would + doubtless have recollected, if his wish to ridicule had not for the moment + obscured his judgment--that whether the law of evolution applies to man or + not, that of hereditary transmission certainly does. Mr. Mivart will + hardly deny that a man owes a large share of the moral tendencies which he + exhibits to his ancestors; and the man who inherits a desire to steal from + a kleptomaniac, or a tendency to benevolence from a Howard, is, so far as + he illustrates hereditary transmission, comparable to the dog who inherits + the desire to fetch a duck out of the water from his retrieving sire. So + that, evolution, or no evolution, moral qualities are comparable to a + "kind of retrieving;" though the comparison, if meant for the purposes of + casting obloquy on evolution, does not say much for the fairness of those + who make it. + </p> + <p> + The Quarterly Reviewer and Mr. Mivart base their objections to the + evolution of the mental faculties of man from those of some lower animal + form upon what they maintain to be a difference in kind between the mental + and moral faculties of men and brutes; and I have endeavoured to show, by + exposing the utter unsoundness of their philosophical basis, that these + objections are devoid of importance. + </p> + <p> + The objections which Mr. Wallace brings forward to the doctrine of the + evolution of the mental faculties of man from those of brutes by natural + causes, are of a different order, and require separate consideration. + </p> + <p> + If I understand him rightly, he by no means doubts that both the bodily + and the mental faculties of man have been evolved from those of some lower + animal; but he is of opinion that some agency beyond that which has been + concerned in the evolution of ordinary animals has been operative in the + case of man. "A superior intelligence has guided the development of man in + a definite direction and for a special purpose, just as man guides the + development of many animal and vegetable forms." [*] I understand this to + mean that, just as the rock-pigeon has been produced by natural causes, + while the evolution of the tumbler from the blue rock has required the + special intervention of the intelligence of man, so some anthropoid form + may have been evolved by variation and natural selection; but it could + never have given rise to man, unless some superior intelligence had played + the part of the pigeon-fancier. + </p> + <ol class="footnotes"> + <li> + "The Limits of Natural Selection as applied to Man" (<i>loc. cit.</i> p. + 359). + </li> + </ol> + <p> + According to Mr. Wallace, "whether we compare the savage with the higher + developments of man, or with the brutes around him, we are alike driven to + the conclusion, that, in his large and well-developed brain, he possesses + an organ quite disproportioned to his requirements" (p. 343); and he asks, + "What is there in the life of the savage but the satisfying of the + cravings of appetite in the simplest and easiest way? What thoughts, idea, + or actions are there that raise him many grades above the elephant or the + ape?" (p. 342.) I answer Mr. Wallace by citing a remarkable passage which + occurs in his instructive paper on "Instinct in Man and Animals." + </p> + <p> + "Savages make long journeys in many directions, and, their whole faculties + being directed to the subject, they gain a wide and accurate knowledge of + the topography, not only of their own district, but of all the regions + round about. Every one who has travelled in a new direction communicates + his knowledge to those who have travelled less, and descriptions of routes + and localities, and minute incidents of travel, form one of the main + staples of conversation around the evening fire. Every wanderer or captive + from another tribe adds to the store of information, and, as the very + existence of individuals and of whole families and tribes depends upon the + completeness of this knowledge, all the acute perceptive faculties of the + adult savage are directed to acquiring and perfecting it. The good hunter + or warrior thus comes to know the bearing of every hill and mountain + range, the directions and junctions of all the streams, the situation of + each tract characterised by peculiar vegetation, not only within the area + he has himself traversed, but perhaps for a hundred miles around it. His + acute observation enables him to detect the slightest undulations of the + surface, the various changes of subsoil and alterations in the character + of the vegetation that would be quite imperceptible to a stranger. His eye + is always open to the direction in which he is going; the mossy side of + trees, the presence of certain plants under the shade of rocks, the + morning and evening flight of birds, are to him indications of direction + almost as sure as the sun in the heavens" (pp. 207, 208). + </p> + <p> + I have seen enough of savages to be able to declare that nothing can be + more admirable than this description of what a savage has to learn. But it + is incomplete. Add to all this the knowledge which a savage is obliged to + gain of the properties of plants, of the characters and habits of animals, + and of the minute indications by which their course is discoverable: + consider that even an Australian can make excellent baskets and nets, and + neatly fitted and beautifully balanced spears; that he learns to use these + so as to be able to transfix a quartern loaf at sixty yards; and that very + often, as in the case of the American Indians, the language of a savage + exhibits complexities which a well-trained European finds it difficult to + master: consider that every time a savage tracks his game he employs a + minuteness of observation, and an accuracy of inductive and deductive + reasoning which, applied to other matters, would assure some reputation to + a man of science, and I think we need ask no further why he possesses such + a fair supply of brains. In complexity and difficulty, I should say that + the intellectual labour of a "good hunter or warrior" considerably exceeds + that of an ordinary Englishman. The Civil Service Examiners are held in + great terror by young Englishmen; but even their ferocity never tempted + them to require a candidate to possess such a knowledge of a parish as Mr. + Wallace justly points out savages may possess of an area a hundred miles + or more in diameter. + </p> + <p> + But suppose, for the sake of argument, that a savage has more brains than + seems proportioned to his wants, all that can be said is that the + objection to natural selection, if it be one, applies quite as strongly to + the lower animals. The brain of a porpoise is quite wonderful for its + mass, and for the development of the cerebral convolutions. And yet since + we have ceased to credit the story of Arion, it is hard to believe that + porpoises are much troubled with intellect: and still more difficult is it + to imagine that their big brains are only a preparation for the advent of + some accomplished cetacean of the future. Surely, again, a wolf must have + too much brains, or else how is it that a dog with only the same quantity + and form of brain is able to develop such singular intelligence? The wolf + stands to the dog in the same relation as the savage to the man; and, + therefore, if Mr. Wallace's doctrine holds good, a higher power must have + superintended the breeding up of wolves from some inferior stock, in order + to prepare them to become dogs. + </p> + <p> + Mr. Wallace further maintains that the origin of some of man's mental + faculties by the preservation of useful variations is not possible. Such, + for example, are "the capacity to form ideal conceptions of space and + time, of eternity and infinity; the capacity for intense artistic feelings + of pleasure in form, colour, and composition; and for those abstract + notions of form and number which render geometry and arithmetic possible." + "How," he asks, "were all or any of these faculties first developed, when + they could have been of no possible use to man in his early stages of + barbarism?" + </p> + <p> + Surely the answer is not far to seek. The lowest savages are as devoid of + any such conceptions as the brutes themselves. What sort of conceptions of + space and time, of form and number, can be possessed by a savage who has + not got so far as to be able to count beyond five or six, who does not + know how to draw a triangle or a circle, and has not the remotest notion + of separating the particular quality we call form, from the other + qualities of bodies? None of these capacities are exhibited by men, unless + they form part of a tolerably advanced society. And, in such a society, + there are abundant conditions by which a selective influence is exerted in + favour of those persons who exhibit an approximation towards the + possession of these capacities. + </p> + <p> + The savage who can amuse his fellows by telling a good story over the + nightly fire, is held by them in esteem and rewarded, in one way or + another, for so doing--in other words, it is an advantage to him to + possess this power. He who can carve a paddle, or the figure-head of a + canoe better, similarly profits beyond his duller neighbour. He who counts + a little better than others, gets most yams when barter is going on, and + forms the shrewdest estimate of the numbers of an opposing tribe. The + experience of daily life shows that the conditions of our present social + existence exercise the most extraordinarily powerful selective influence + in favour of novelists, artists, and strong intellects of all kinds; and + it seems unquestionable that all forms of social existence must have had + the same tendency, if we consider the indisputable facts that even animals + possess the power of distinguishing form and number, and that they are + capable of deriving pleasure from particular forms and sounds. If we + admit, as Mr. Wallace does, that the lowest savages are not raised "many + grades above the elephant and the ape;" and if we further admit, as I + contend must be admitted, that the conditions of social life tend, + powerfully, to give an advantage to those individuals who vary in the + direction of intellectual or æsthetic excellence, what is there to + interfere with the belief that these higher faculties, like the rest, owe + their development to natural selection? + </p> + <p> + Finally, with respect to the development of the moral sense out of the + simple feelings of pleasure and pain, liking and disliking, with which the + lower animals are provided, I can find nothing in Mr. Wallace's reasonings + which has not already been met by Mr. Mill, Mr. Spencer, or Mr. Darwin. + </p> + <p> + I do not propose to follow the Quarterly Reviewer and Mr. Mivart through + the long string of objections in matters of detail which they bring + against Mr. Darwin's views. Every one who has considered the matter + carefully will be able to ferret out as many more "difficulties"; but he + will also, I believe, fail as completely as they appear to me to have + done, in bringing forward any fact which is really contradictory of Mr. + Darwin's views. Occasionally, too, their objections and criticisms are + based upon errors of their own. As, for example, when Mr. Mivart and the + Quarterly Reviewer insist upon the resemblances between the eyes of <i>Cephalopoda</i> + and <i>Vertebrata</i>, quite forgetting that there are striking and + altogether fundamental differences between them; or when the Quarterly + Reviewer corrects Mr. Darwin for saying that the gibbons, "without having + been taught, can walk or run upright with tolerable quickness, though they + move awkwardly, and much less securely than man." The Quarterly Reviewer + says, "This is a little misleading, inasmuch as it is not stated that this + upright progression is effected by placing the enormously long arms behind + the head, or holding them out backwards as a balance in progression." + </p> + <p> + Now, before carping at a small statement like this, the Quarterly Reviewer + should have made sure that he was quite right. But he happens to be quite + wrong. I suspect he got his notion of the manner in which a gibbon walks + from a citation in "Man's Place in Nature." But at that time I had not + seen a gibbon walk. Since then I have, and I can testify that nothing can + be more precise than Mr. Darwin's statement. The gibbon I saw walked + without either putting his arms behind his head or holding them out + backwards. All he did was to touch the ground with the outstretched + fingers of his long arms now and then, just as one sees a man who carries + a stick, but does not need one, touch the ground with it as he walks + along. + </p> + <p> + Again, a large number of the objections brought forward by Mr. Mivart and + the Quarterly Reviewer apply to evolution in general, quite as much as to + the particular form of that doctrine advocated by Mr. Darwin; or, to their + notions of Mr. Darwin's views and not to what they really are. An + excellent example of this class of difficulties is to be found in Mr. + Mivart's chapter on "Independent Similarities of Structure." Mr. Mivart + says that these cannot be explained by an "absolute and pure Darwinian," + but "that an innate power and evolutionary law, aided by the corrective + action of natural selection, should have furnished like needs with like + aids, is not at all improbable" (p. 82). + </p> + <p> + I do not exactly know what Mr. Mivart means by an "absolute and pure + Darwinian;" indeed Mr. Mivart makes that creature hold so many singular + opinions that I doubt if I can ever have seen one alive. But I find + nothing in his statement of the view which he imagines to be originated by + himself, which is really inconsistent with what I understand to be Mr. + Darwin's views. + </p> + <p> + I apprehend that the foundation of the theory of natural selection is the + fact that living bodies tend incessantly to vary. This variation is + neither indefinite, nor fortuitous, nor does it take place in all + directions, in the strict sense of these words. + </p> + <p> + Accurately speaking, it is not indefinite, nor does it take place in all + directions, because it is limited by the general characters of the type to + which the organism exhibiting the variation belongs. A whale does not tend + to vary in the direction of producing feathers, nor a bird in the + direction of developing whalebone. In popular language there is no harm in + saying that the waves which break upon the sea-shore are indefinite, + fortuitous, and break in all directions. In scientific language, on the + contrary, such a statement would be a gross error, inasmuch as every + particle of foam is the result of perfectly definite forces, operating + according to no less definite laws. In like manner, every variation of a + living form, however minute, however apparently accidental, is + inconceivable except as the expression of the operation of molecular + forces or "powers" resident within the organism. And, as these forces + certainly operate according to definite laws, their general result is, + doubtless, in accordance with some general law which subsumes them all. + And there appears to be no objection to call this an "evolutionary law." + But nobody is the wiser for doing so, or has thereby contributed, in the + least degree, to the advance of the doctrine of evolution, the great need + of which is a theory of variation. + </p> + <p> + When Mr. Mivart tells us that his "aim has been to support the doctrine + that these species have been evolved by ordinary <i>natural laws</i> (for + the most part unknown), aided by the <i>subordinate</i> action of 'natural + selection'" (pp. 332-3), he seems to be of opinion that his enterprise has + the merit of novelty. All I can say is that I have never had the slightest + notion that Mr. Darwin's aim is in any way different from this. If I + affirm that "species have been evolved by variation [*] (a natural + process, the laws of which are for the most part unknown), aided by the + subordinate action of natural selection," it seems to me that I enunciate + a proposition which constitutes the very pith and marrow of the first + edition of the "Origin of Species." And what the evolutionist stands in + need of just now, is not an iteration of the fundamental principle of + Darwinism, but some light upon the questions, What are the limits of + variation? and, If a variety has arisen, can that variety be perpetuated, + or even intensified, when selective conditions are indifferent, or perhaps + unfavourable to its existence? I cannot find that Mr. Darwin has ever been + very dogmatic in answering these questions. Formerly, he seems to have + inclined to reply to them in the negative, while now his inclination is + the other way. Leaving aside those broad questions of theology, + philosophy, and ethics, by the discussion of which neither the Quarterly + Reviewer nor Mr. Mivart can be said to have damaged Darwinism--whatever + else they have injured--this is what their criticisms come to. They + confound a struggle for some rifle-pits with an assault on the fortress. + </p> + <ol class="footnotes"> + <li> + Including under this head hereditary transmission. + </li> + </ol> + <p> + In some respects, finally, I can only characterise the Quarterly + Reviewer's treatment of Mr. Darwin as alike unjust and unbecoming. + Language of this strength requires justification, and on that ground I add + the remarks which follow. + </p> + <p> + The Quarterly Reviewer opens his essay by a careful enumeration of all + those points upon which, during the course of thirteen years of incessant + labour, Mr. Darwin has modified his opinions. It has often and justly been + remarked, that what strikes a candid student of Mr. Darwin's works is not + so much his industry, his knowledge, or even the surprising fertility of + his inventive genius; but that unswerving truthfulness and honesty which + never permit him to hide a weak place, or gloss over a difficulty, but + lead him, on all occasions, to point out the weak places in his own + armour, and even sometimes, it appears to me, to make admissions against + himself which are quite unnecessary. A critic who desires to attack Mr. + Darwin has only to read his works with a desire to observe, not their + merits, but their defects, and he will find, ready to hand, more adverse + suggestions than are likely ever to have suggested themselves to his own + sharpness, without Mr. Darwin's self-denying aid. + </p> + <p> + Now this quality of scientific candour is not so common that it needs to + be discouraged; and it appears to me to deserve other treatment than that + adopted by the Quarterly Reviewer, who deals with Mr. Darwin as an Old + Bailey barrister deals with a man against whom he wishes to obtain a + conviction, <i>per fas aut nefas</i>, and opens his case by endeavouring + to create a prejudice against the prisoner in the minds of the jury. In + his eagerness to carry out this laudable design, the Quarterly Reviewer + cannot even state the history of the doctrine of natural selection without + an oblique and entirely unjustifiable attempt to depreciate Mr. Darwin. + "To Mr. Darwin," says he, "and (through Mr. Wallace's reticence) to Mr. + Darwin alone, is due the credit of having first brought it prominently + forward and demonstrated its truth." No one can less desire than I do, to + throw a doubt upon Mr. Wallace's originality, or to question his claim to + the honour of being one of the originators of the doctrine of natural + selection; but the statement that Mr. Darwin has the sole credit of + originating the doctrine because of Mr. Wallace's reticence is simply + ridiculous. The proof of this is, in the first place, afforded by Mr. + Wallace himself, whose noble freedom from petty jealousy in this matter + smaller folk would do well to imitate, and who writes thus:--"I have felt + all my life, and I still feel, the most sincere satisfaction that Mr. + Darwin had been at work long before me and that it was not left for me to + attempt to write the 'Origin of Species.' I have long since measured my + own strength, and know well that it would be quite unequal to that task." + So that if there was any reticence at all in the matter, it was Mr. + Darwin's reticence during the long twenty years of study which intervened + between the conception and the publication of his theory, which gave Mr. + Wallace the chance of being an independent discoverer of the importance of + natural selection. And, finally, if it be recollected that Mr. Darwin's + and Mr. Wallace's essays were published simultaneously in the "Journal of + the Linnæan Society" for 1858, it follows that the Reviewer, while + obliquely depreciating Mr. Darwin's deserts, has in reality awarded to him + a priority which, in legal strictness, does not exist. + </p> + <p> + Mr. Mivart, whose opinions so often concur with those of the Quarterly + Reviewer, puts the case in a way, which I much regret to be obliged to + say, is, in my judgment, quite as incorrect; though the injustice may be + less glaring. He says that the theory of natural selection is, in general, + exclusively associated with the name of Mr. Darwin, "on account of the + noble self-abnegation of Mr. Wallace." As I have said, no one can honour + Mr. Wallace more than I do, both for what he has done and for what he has + not done, in his relation to Mr. Darwin. And perhaps nothing is more + creditable to him than his frank declaration that he could not have + written such a work as the "Origin of Species." But, by this declaration, + the person most directly interested in the matter repudiates, by + anticipation, Mr. Mivart's suggestion that Mr. Darwin's eminence is more + or less due to Mr. Wallace's modesty. + </p> + <h2 id="c6"> + VI Evolution In Biology + </h2> + <p> + [1878] + </p> + <p> + In the former half of the eighteenth century, the term "evolution" was + introduced into biological writings, in order to denote the mode in which + some of the most eminent physiologists of that time conceived that the + generations of living things took place; in opposition to the hypothesis + advocated, in the preceding century, by Harvey in that remarkable work [*] + which would give him a claim to rank among the founders of biological + science, even had he not been the discoverer of the circulation of the + blood. + </p> + <ol class="footnotes"> + <li> + The <i>Exercitationes de Generatione Animalium</i>, which Dr. George Ent + extracted from him and published in 1651. + </li> + </ol> + <p> + One of Harvey's prime objects is to defend and establish, on the basis of + direct observation, the opinion already held by Aristotle; that, in the + higher animals at any rate, the formation of the new organism by the + process of generation takes place, not suddenly, by simultaneous accretion + of rudiments of all, or of the most important, of the organs of the adult; + nor by sudden metamorphosis of a formative substance into a miniature of + the whole, which subsequently grows; but by <i>epigenesis</i>, or + successive differentiation of a relatively homogeneous rudiment into the + parts and structures which are characteristic of the adult. + </p> + <p> + "Et primò, quidem, quoniam per <i>epigenesin</i> sive partium + superexorientium additamentum pullum fabricari certum est: quænam + pars ante alias omnes exstruatur, et quid de illa ejusque generandi modo + observandum veniat, dispiciemus. Ratum sane est et in ovo manifestè + apparet quod <i>Aristoteles</i> de perfectorum animalium generatione + enuntiat: nimirum, non omnes partes simul fieri, sed ordine aliam post + aliam; primùmque existere particulam genitalem, cujus virtute + postea (tanquam ex principio quodam) reliquæ omnes partes + prosiliant. Qualem in plantarum seminibus (fabis, putà, aut + glandibus) gemmam sive apicem protuberantem cernimus, totius futuræ + arboris principium. <i>Estque hæc particula, velut filius + emancipatus seorsumquc collocatus, et principium per se vivens; unde + postea, membrorum ordo describitur; et quæcunque ad absolvendum + animal pertinent, disponuntur.</i> [*] Quoniam enim <i>nulla pars se ipsam + generat; sed postquam generata est, se ipsam jam auget; ideo eam primùm + oriri necesse est, quæ principium augendi contineat (sive enim + planta, sive animal est, æque omnibus inest quod vim habeat + vegetandi, sive nutriendi</i>), [*] simulque reliquas omnes partes suo + quamque ordine distinguat et formet; proindeque in eadem primogenita + particula anima primario inest, sensus, motusque, et totius vitæ + auctor et principium." (Exercitatio 51.) + </p> + <ol class="footnotes"> + <li> + <i>De Generatione Animalium</i>, lib. ii. cap. x. + </li> + <li> + <i>De Generatione</i>, lib. ii. cap. iv. + </li> + </ol> + <p> + Harvey proceeds to contrast this view with that of the "Medici," or + followers of Hippocrates and Galen, who, "badly philosophising," imagined + that the brain, the heart, and the liver were simultaneously first + generated in the form of vesicles; and, at the same time, while expressing + his agreement with Aristotle in the principle of epigenesis, he maintains + that it is the blood which is the primal generative part, and not, as + Aristotle thought, the heart. + </p> + <p> + In the latter part of the seventeenth century, the doctrine of epigenesis, + thus advocated by Harvey, was controverted, on the ground of direct + observation, by Malpighi, who affirmed that the body of the chick is to be + seen in the egg, before the <i>punctum sanguineum</i> makes it appearance. + But, from this perfectly correct observation a conclusion which is by no + means warranted was drawn; namely, that the chick, as a whole, really + exists in the egg antecedently to incubation; and that what happens in the + course of the latter process is no addition of new parts, "alias post + alias natas," as Harvey puts it, but a simple expansion, or unfolding, of + the organs which already exist, though they are too small and + inconspicuous to be discovered. The weight of Malpighi's observations + therefore fell into the scale of that doctrine which Harvey terms <i>metamorphosis</i>, + in contradistinction to epigenesis. + </p> + <p> + The views of Malpighi were warmly welcomed, on philosophical grounds, by + Leibnitz, [*] who found in them a support to his hypothesis of monads, and + by Malebranche; [*] while, in the middle of the eighteenth century, not + only speculative considerations, but a great number of new and interesting + observations on the phenomena of generation, led the ingenious Bonnet, and + Haller, [*] the first physiologist of the age, to adopt, advocate, and + extend them. + </p> + <ol class="footnotes"> + <li> + "Cependant, pour revenir aux formes ordinaires ou aux âmes matérielles, + cette durée qu'il leur faut attribuer à la place de celle + qu'on avoit attribuée aux atomes pourroit faire douter si elles + ne vont pas de corps en corps; ce qui seroit la métempsychose, + à peu près comme quelques philosophes ont cru la + transmission du mouvement et celle des espèces. Mais cette + imagination est bien éloignée de la nature des choses. Il + n'y a point de tel passage; et c'est ici où les transformations + de Messieurs Swammerdam, Malpighi, et Leewenhoek, qui sont des plus + excellens observateurs de notre tems, sont venues à mon secours, + et m'ont fait admettre plus aisément, que l'animal, et toute + autre substance organisée ne commence point lorsque nous le + croyons, et que sa generation apparente n'est qu'une développement + et une espèce d'augmentation. Aussi ai je remarqué que + l'auteur de la <i>Recherche de la Verité</i>, M. Regis, M. + Hartsoeker, et d'autres habiles hommes n'ont pas été fort + éloignés de ce sentiment." Leibnitz, <i>Système + Nouveau de la Nature</i>, 1695. The doctrine of "Embôitement" is + contained in the <i>Considérations sur le Principe de Vie</i>, + 1705; the preface to the <i>Theodicée</i>, 1710; and the <i>Principes + de la Nature et de la Grace</i> (§ 6), 1718. + </li> + <li> + "Il est vrai que la pensée la plus raisonnable et la plus + conforme à l'experience sur cette question très difficile + de la formation du foetus; c'est que les enfans sont déja presque + tout formés avant même l'action par laquelle ils sont conçus; + et que leurs mères ne font que leur donner l'accroissement + ordinaire dans le temps de la grossesse." <i>De la Recherche de la Verité</i>, + livre ii. chap. vii. p. 334, 7th ed., 1721. + </li> + <li> + The writer is indebted to Dr. Allen Thomson for reference to the + evidence contained in a note to Haller's edition of Boerhaave's <i>Prælectiones + Academicæ</i>, vol. v. pt. ii. p. 497, published in 1744, that + Haller originally advocated epigenesis. + </li> + </ol> + <p> + Bonnet affirms that, before fecundation, the hen's egg contains an + excessively minute but complete chick; and that fecundation and incubation + simply cause this germ to absorb nutritious matters, which are deposited + in the interstices of the elementary structures of which the miniature + chick, or germ, is made up. The consequence of this intussusceptive growth + is the "development" or "evolution" of the germ into the visible bird. + Thus an organised individual (<i>tout organisé</i>) "is a composite + body consisting of the original, or <i>elementary</i>, parts and of the + matters which have been associated with them by the aid of nutrition;" so + that, if these matters could be extracted from the individual (<i>tout</i>), + it would, so to speak, become concentrated in a point, and would thus be + restored to its primitive condition of a <i>germ</i>; "just as by + extracting from a bone the calcareous substance which is the source of its + hardness, it is reduced to its primitive state of gristle or membrane." + [*] "Evolution" and "development" are, for Bonnet, synonymous terms; and + since by "evolution" he means simply the expansion of that which was + invisible into visibility, he was naturally led to the conclusion, at + which Leibnitz had arrived by a different line of reasoning, that no such + thing as generation, in the proper sense of the word, exists in Nature. + The growth of an organic being is simply a process of enlargement as a + particle of dry gelatine may be swelled up by the intussusception of + water; its death is a shrinkage, such as the swelled jelly might undergo + on desiccation. Nothing really new is produced in the living world, but + the germs which develop have existed since the beginning of things; and + nothing really dies, but, when what we call death takes place, the living + thing shrinks back into its germ state. [*] + </p> + <ol class="footnotes"> + <li> + <i>Considérations sur les Corps organisés</i>, chap. x. + </li> + <li> + <p> + Bonnet had the courage of his opinions, and in the <i>Palingénésie + Philosophique</i>, part vi. chap, iv., he develops a hypothesis which + he terms "évolution naturelle;" and which, making allowance for + his peculiar views of the nature of generation, bears no small + resemblance to what is understood by "evolution" at the present day:-- + </p> + <p> + "Si la volonté divine a créé par un seul Acte + l'Universalité des êtres, d'où venoient ces + plantes et ces animaux dont Moyse nous decrit la Production au + troisieme et au cinquieme jour du renouvellement de notre monde? + </p> + <p> + "Abuserois-je de la liberté de conjectures si je disois, que + les Plantes et les Animaux qui existent aujourd'hui sont parvenus par + une sorte d'evolution naturelle des Etres organises qui peuplaient ce + premier Monde, sorti immédiatement des MAINS du CREATEUR?... + </p> + <p> + "Ne supposons que trois révolutions. La Terre vient de sortir + des MAINS du CREATEUR. Des causes preparées par sa SAGESSE font + développer de toutes parts les Germes. Les Etres organisés + commencent à jouir de l'existence. Ils étoient + probablement alors bien différens de ce qu'ils sont + aujourd'hui. Ils l'etoient autant que ce premier Monde différoit + de celui que nous habitons. Nous manquons de moyens pour juger de ces + dissemblances, et peut-être que le plus habile Naturaliste qui + auroit été placé dans ce premier Monde y auroit + entièrement méconnu nos Plantes et nos Animaux." + </p> + </li> + </ol> + <p> + The two parts of Bonnet's hypothesis, namely, the doctrine that all living + things proceed from pre-existing germs, and that these contain, one + inclosed within the other, the germs of all future living things, which is + the hypothesis of "<i>emboîtement</i>;" and the doctrine that every + germ contains in miniature all the organs of the adult, which is the + hypothesis of evolution or development, in the primary senses of these + words, must be carefully distinguished. In fact, while holding firmly by + the former, Bonnet more or less modified the latter in his later writings, + and, at length, he admits that a "germ" need not be an actual miniature of + the organism; but that it may be merely an "original preformation" capable + of producing the latter. [*] + </p> + <ol class="footnotes"> + <li> + "Ce mot (germe) ne désignera pas seulement un corps organisé + <i>réduit en petit</i>; il désignera encore toute espèce + de <i>préformation originelle dont un Tout organique peut résulter + comme de son principe immédiat."--Palingénésie + Philosophique</i>, part X. chap. II. + </li> + </ol> + <p> + But, thus defined, the germ is neither more nor less than the "particula + genitalis" of Aristotle, or the "primordium vegetale" or "ovum" of Harvey; + and the "evolution" of such a germ would not be distinguishable from + "epigenesis." + </p> + <p> + Supported by the great authority of Haller, the doctrine of evolution, or + development, prevailed throughout the whole of the eighteenth century, and + Cuvier appears to have substantially adopted Bonnet's later views, though + probably he would not have gone all lengths in the direction of "emboîtement." + In a well-known note to Laurillard's "Éloge," prefixed to the last + edition of the "Ossemens fossiles," the "radical de l'être" is much + the same thing as Aristotle's "particula genitalis" and Harvey's "ovum." + [*] + </p> + <ol class="footnotes"> + <li> + "M. Cuvier considérant que tous les êtres organisés + sont dérivés de parens, et ne voyant dans la nature aucune + force capable de produire l'organisation, croyait à la pré-existence + des germes; non pas à la pré-existence d'un être + tout formé, puisqu'il est bien évident que ce n'est que + par des développemens successifs que l'être acquiert sa + forme; mais, si l'on peut s'exprimer ainsi, à la pré-existence + du <i>radical de l'être</i>, radical qui existe avant que la série + des évolutions ne commence, et qui remonte certainement, suivant + la belle observation de Bonnet, à plusieurs + generations."--Laurillard, <i>Éloge de Cuvier</i>, note 12. + </li> + </ol> + <p> + Bonnet's eminent contemporary, Buffon, held nearly the same views with + respect to the nature of the germ, and expresses them even more + confidently. + </p> + <p> + "Ceux qui ont cru que le coeur étoit le premier formé, se + sont trompés; ceux qui disent que c'est le sang se trompent aussi: + tout est formé en même temps. Si l'on ne consulte que + l'observation, le poulet se voit dans l'oeuf avant qu'il ait été + couvé." [*] + </p> + <ol class="footnotes"> + <li> + <i>Histoire Naturelle</i>, tom. ii. ed. ii. 1750, p. 350. + </li> + </ol> + <p> + "J'ai ouvert une grande quantité d'oeufs à differens temps + avant et après l'incubation, et je me suis convaincu par mes yeux + que le poulet existe en entier dans le milieu de la cicatricule au moment + qu'il sort du corps de la poule." [*] + </p> + <ol class="footnotes"> + <li> + <i>Ibid</i>., p. 351. + </li> + </ol> + <p> + The "moule intérieur" of Buffon is the aggregate of elementary + parts which constitute the individual, and is thus the equivalent of + Bonnet's germ, [*] as defined in the passage cited above. But Buffon + further imagined that innumerable "molecules organiques" are dispersed + throughout the world, and that alimentation consists in the appropriation + by the parts of an organism of those molecules which are analogous to + them. Growth, therefore, was, on this hypothesis, a process partly of + simple evolution, and partly of what has been termed "syngenesis." + Buffon's opinion is, in fact, a sort of combination of views, essentially + similar to those of Bonnet, with others, somewhat similar to those of the + "Medici" whom Harvey condemns. The "molecules organiques" are physical + equivalents of Leibnitz's "monads." + </p> + <ol class="footnotes"> + <li> + See particularly Buffon, <i>l. c.</i> p. 41. + </li> + </ol> + <p> + It is a striking example of the difficulty of getting people to use their + own powers of investigation accurately, that this form of the doctrine of + evolution should have held its ground so long; for it was thoroughly and + completely exploded, not long after its enunciation, by Casper Friederich + Wolff, who in his "Theoria Generationis," published in 1759, placed the + opposite theory of epigenesis upon the secure foundation of fact, from + which it has never been displaced. But Wolff had no immediate successors. + The school of Cuvier was lamentably deficient in embryologists; and it was + only in the course of the first thirty years of the present century, that + Prévost and Dumas in France, and, later on, Döllinger, Pander, + Von Bär, Rathke, and Remak in Germany, founded modern embryology; + while, at the same time, they proved the utter incompatibility of the + hypothesis of evolution, as formulated by Bonnet and Haller, with easily + demonstrable facts. + </p> + <p> + Nevertheless, though the conceptions originally denoted by "evolution" and + "development" were shown to be untenable, the words retained their + application to the process by which the embryos of living beings gradually + make their appearance; and the terms "Development," "Entwickelung," and + "Evolutio," are now indiscriminately used for the series of genetic + changes exhibited by living beings, by writers who would emphatically deny + that "Development" or "Entwickelung" or "Evolutio," in the sense in which + these words were usually employed by Bonnet or by Haller, ever occurs. + </p> + <p> + Evolution, or development, is, in fact, at present employed in biology as + a general name for the history of the steps by which any living being has + acquired the morphological and the physiological characters which + distinguish it. As civil history may be divided into biography, which is + the history of individuals, and universal history, which is the history of + the human race, so evolution falls naturally into two categories--the + evolution of the individual, and the evolution of the sum of living + beings. It will be convenient to deal with the modern doctrine of + evolution under these two heads. + </p> + <p> + I. <i>The Evolution of the Individual</i>. + </p> + <p> + No exception is at this time, known to the general law, established upon + an immense multitude of direct observations, that every living thing is + evolved from a particle of matter in which no trace of the distinctive + characters of the adult form of that living thing is discernible. This + particle is termed a <i>germ</i>. Harvey [*] says-- + </p> + <ol class="footnotes"> + <li> + <i>Execitationes de Generatione</i>. Ex. 62, "Ovum esse primordium + commune omnibus animalibus." + </li> + </ol> + <p> + "Omnibus viventibus primordium insit, ex quo et a quo proveniant. Liceat + hoc nobis <i>primordium vegetale</i> nominare; nempe substantiam quandam + corpoream vitam habentem potentiâ; vel quoddam per se existens, quod + aptum sit, in vegetativam formam, ab interno principio operante, mutari. + Quale nempe primordium, ovum est et plantarum semen; tale etiam + viviparorum conceptus, et insectorum <i>vermis</i> ab Aristotele dictus: + diversa scilicet diversorum viventium primordia." + </p> + <p> + The definition of a germ as "matter potentially alive, and having within + itself the tendency to assume a definite living form," appears to meet all + the requirements of modern science. For, notwithstanding it might be + justly questioned whether a germ is not merely potentially, but rather + actually, alive, though its vital manifestations are reduced to a minimum, + the term "potential" may fairly be used in a sense broad enough to escape + the objection. And the qualification of "potential" has the advantage of + reminding us that the great characteristic of the germ is not so much what + it is, but what it may, under suitable conditions, become. Harvey shared + the belief of Aristotle--whose writings he so often quotes and of whom he + speaks as his precursor and model, with the generous respect with which + one genuine worker should regard another--that such germs may arise by a + process of "equivocal generation" out of not-living matter; and the + aphorism so commonly ascribed to him, "<i>omne vivum ex ovo</i>" and which + is indeed a fair summary of his reiterated assertions, though incessantly + employed against the modern advocates of spontaneous generation, can be + honestly so used only by those who have never read a score of pages of the + "Exercitationes." Harvey, in fact, believed as implicitly as Aristotle did + in the equivocal generation of the lower animals. But, while the course of + modern investigation has only brought out into greater prominence the + accuracy of Harvey's conception of the nature and mode of development of + germs, it has as distinctly tended to disprove the occurrence of equivocal + generation, or abiogenesis, in the present course of nature. In the + immense majority of both plants and animals, it is certain that the germ + is not merely a body in which life is dormant or potential, but that it is + itself simply a detached portion of the substance of a pre-existing living + body; and the evidence has yet to be adduced which will satisfy any + cautious reasoner that "omne vivum ex vivo" is not as well-established a + law of the existing course of nature as "omne vivum ex ovo." + </p> + <p> + In all instances which have yet been investigated, the substance of this + germ has a peculiar chemical composition, consisting of at fewest four + elementary bodies, viz., carbon, hydrogen, oxygen, and nitrogen, united + into the ill-defined compound known as protein, and associated with much + water, and very generally, if not always, with sulphur and phosphorus in + minute proportions. Moreover, up to the present time, protein is known + only as a product and constituent of living matter. Again, a true germ is + either devoid of any structure discernible by optical means, or, at most, + it is a simple nucleated cell. [*] + </p> + <ol class="footnotes"> + <li> + In some cases of sexless multiplication the germ is a cell-aggregate--if + we call germ only that which is already detached from the parent + organism. + </li> + </ol> + <p> + In all cases the process of evolution consists in a succession of changes + of the form, structure, and functions of the germ, by which it passes, + step by step, from an extreme simplicity, or relative homogeneity, of + visible structure, to a greater or less degree of complexity or + heterogeneity; and the course of progressive differentiation is usually + accompanied by growth, which is effected by intussusception. This + intussusception, however, is a very different process from that imagined + either by Buffon or by Bonnet. The substance by the addition of which the + germ is enlarged is in no case simply absorbed, ready-made, from the + not-living world and packed between the elementary constituents of the + germ, as Bonnet imagined; still less does it consist of the "molecules + organiques" of Buffon. The new material is, in great measure, not only + absorbed but assimilated, so that it becomes part and parcel of the + molecular structure of the living body into which it enters. And, so far + from the fully developed organism being simply the germ <i>plus</i> the + nutriment which it has absorbed, it is probable that the adult contains + neither in form, nor in substance, more than an inappreciable fraction of + the constituents of the germ, and that it is almost, if not wholly, made + up of assimilated and metamorphosed nutriment. In the great majority of + cases, at any rate, the full-grown organism becomes what it is by the + absorption of not-living matter, and its conversion into living matter of + a specific type. As Harvey says (Ex. 45), all parts of the body are + nourished "ab eodem succo alibili, aliter aliterque cambiato," "ut plantæ + omnes ex eodem communi nutrimento (sive rore seu terræ humore)." + </p> + <p> + In all animals and plants above the lowest the germ is a nucleated cell, + using that term in its broadest sense; and the first step in the process + of the evolution of the individual is the division of this cell into two + or more portions. The process of division is repeated, until the organism, + from being unicellular, becomes multicellular. The single cell becomes a + cell-aggregate; and it is to the growth and metamorphosis of the cells of + the cell-aggregate thus produced, that all the organs and tissues of the + adult owe their origin. + </p> + <p> + In certain animals belonging to every one of the chief groups into which + the <i>Metazoa</i> are divisible, the cells of the cell-aggregate which + results from the process of yelk-division, and which is termed a <i>morula</i>, + diverge from one another in such a manner as to give rise to a central + space, around which they dispose themselves as a coat or envelope; and + thus the morula becomes a vesicle filled with fluid, the <i>planula</i>. + The wall of the planula is next pushed in on one side, or invaginated, + whereby it is converted into a double-walled sac with an opening, the <i>blastopore</i>, + which leads into the cavity lined by the inner wall. This cavity is the + primitive alimentary cavity or <i>archenteron</i>; the inner or + invaginated layer is the <i>hypoblast</i>; the outer the <i>epiblast</i>; + and the embryo, in this stage, is termed a <i>gastrula</i>. In all the + higher animals a layer of cells makes its appearance between the hypoblast + and the epiblast, and is termed the <i>mesoblast</i>. In the further + course of development the epiblast becomes the ectoderm or epidermic layer + of the body; the hypoblast becomes the epithelium of the middle portion of + the alimentary canal; and the mesoblast gives rise to all the other + tissues, except the central nervous system, which originates from an + ingrowth of the epiblast. + </p> + <p> + With more or less modification in detail, the embryo has been observed to + pass through these successive evolutional stages in sundry Sponges, + Coelenterates, Worms, Echinoderms, Tunicates, Arthropods, Mollusks, and + Vertebrates; and there are valid reasons for the belief that all animals + of higher organisation than the <i>Protozoa</i>, agree in the general + character of the early stages of their individual evolution. Each, + starting from the condition of a simple nucleated cell, becomes a + cell-aggregate; and this passes through a condition which represents the + gastrula stage, before taking on the features distinctive of the group to + which it belongs. Stated in this form, the "gastræa theory" of + Haeckel appears to the present writer to be one of most important and best + founded of recent generalisations. So far as individual plants and animals + are concerned, therefore, evolution is not a speculation but a fact; and + it takes place by epigenesis. + </p> + <p> + "Animal...per <i>epigenesin</i> procreatur, materiam simul attrahit, + parat, concoquit, et eâdem utitur; formatur simul et augetur ... + primum futuri corporis concrementum ... prout augetur, dividitur sensim et + distinguitur in partes, non simul omnes, sed alias post alias natas, et + ordine quasque suo emergentes." [*] In these words, by the divination of + genius, Harvey, in the seventeenth century, summed up the outcome of the + work of all those who, with appliances he could not dream of, are + continuing his labours in the nineteenth century. + </p> + <ol class="footnotes"> + <li> + Harvey, <i>Exercitationes de Generatione</i>. Ex. 45, "Quænam sit + pulli materia et quomodo fiat in Ovo." + </li> + </ol> + <p> + Nevertheless, though the doctrine of epigenesis, as understood by Harvey, + has definitively triumphed over the doctrine of evolution, as understood + by his opponents of the eighteenth century, it is not impossible that, + when the analysis of the process of development is carried still further, + and the origin of the molecular components of the physically gross, though + sensibly minute, bodies which we term germs is traced, the theory of + development will approach more nearly to metamorphosis than to epigenesis. + Harvey thought that impregnation influenced the female organism as a + contagion; and that the blood, which he conceived to be the first rudiment + of the germ, arose in the clear fluid of the "colliquamentum" of the ovum + by a process of concrescence, as a sort of living precipitate. We now + know, on the contrary, that the female germ or ovum, in all the higher + animals and plants, is a body which possesses the structure of a nucleated + cell; that impregnation consists in the fusion of the substance [*] of + another more or less modified nucleated cell, the male germ, with the + ovum; and that the structural components of the body of the embryo are all + derived, by a process of division, from the coalesced male and female + germs. Hence it is conceivable, and indeed probable, that every part of + the adult contains molecules, derived both from the male and from the + female parent; and that, regarded as a mass of molecules, the entire + organism may he compared to a web of which the warp is derived from the + female and the woof from the male. And each of these may constitute one + individuality, in the same sense as the whole organism is one individual, + although the matter of the organism has been constantly changing. The + primitive male and female molecules may play the part of Buffon's "moules + organiques," and mould the assimilated nutriment, each according to its + own type, into innumerable new molecules. From this point of view the + process, which, in its superficial aspect, is epigenesis, appears in + essence, to be evolution, in the modified sense adopted in Bonnet's later + writings; and development is merely the expansion of a potential organism + or "original preformation" according to fixed laws. + </p> + <ol class="footnotes"> + <li> + [At any rate of the nuclei of the two germ-cells. 1893] + </li> + </ol> + <p> + II. <i>The Evolution of the Sum of Living Beings</i>. + </p> + <p> + The notion that all the kinds of animals and plants may have come into + existence by the growth and modification of primordial germs is as old as + speculative thought; but the modern scientific form of the doctrine can be + traced historically to the influence of several converging lines of + philosophical speculation and of physical observation, none of which go + farther back than the seventeenth century. These are:-- + </p> + <p> + 1. The enunciation by Descartes of the conception that the physical + universe, whether living or not living, is a mechanism, and that, as such, + it is explicable on physical principles. + </p> + <p> + 2. The observation of the gradations of structure, from extreme simplicity + to very great complexity, presented by living things, and of the relation + of these graduated forms to one another. + </p> + <p> + 3. The observation of the existence of an analogy between the series of + gradations presented by the species which compose any great group of + animals or plants, and the series of embryonic conditions of the highest + members of that group. + </p> + <p> + 4. The observation that large groups of species of widely different habits + present the same fundamental plan of structure; and that parts of the same + animal or plant, the functions of which are very different, likewise + exhibit modifications of a common plan. + </p> + <p> + 5. The observation of the existence of structures, in a rudimentary and + apparently useless condition, in one species of a group, which are fully + developed and have definite functions in other species of the same group. + </p> + <p> + 6. The observation of the effects of varying conditions in modifying + living organisms. + </p> + <p> + 7. The observation of the facts of geographical distribution. + </p> + <p> + 8. The observation of the facts of the geological succession of the forms + of life. + </p> + <p> + 1. Notwithstanding the elaborate disguise which fear of the powers that + were led Descartes to throw over his real opinions, it is impossible to + read the "Principes de la Philosophie" without acquiring the conviction + that this great philosopher held that the physical world and all things in + it, whether living or not living, have originated by a process of + evolution, due to the continuous operation of purely physical causes, out + of a primitive relatively formless matter. [*] + </p> + <ol class="footnotes"> + <li> + As Buffon has well said:--"L'idée de ramener l'explication de + tous les phénomènes à des principes mecaniques est + assurement grande et belle, ce pas est le plus hardi qu'on peut faire en + philosophie, et c'est Descartes qui l'a fait."--<i>l. c.</i> p.50. + </li> + </ol> + <p> + The following passage is especially instructive:-- + </p> + <p> + "Et tant s'en faut que je veuille que l'on croie toutes les choses que j'écrirai, + que même je pretends en proposer ici quelques unes que je crois + absolument être fausses; à savoir, je ne doute point quo le + monde n'ait été créé au commencement avec + autant de perfection qu'il eu a; en sorte que le soleil, la terre, la + lune, et les étoiles ont été dès lors; et que + la terre n'a pas eu seulement en soi les semences des plantes, mais que + les plantes même en ont couvert une partie; et qu' Adam et Eve n'ont + pas été créés enfans mais en âge + d'hommes parfaits. La religion chrétienne veut que nous le croyons + ainsi, et la raison naturelle nous persuade entièrement cette vérité; + car si nous considérons la toute puissance de Dieu, nous devons + juger que tout ce qu'il a fait a eu dès le commencement toute la + perfection qu'il devoit avoir. Mais néanmoins, comme on connôitroit + beaucoup mieux quelle a été la nature d'Adam et celle des + arbres de Paradis si on avoit examiné comment les enfants se + forment peu à peu dans le ventre de leurs mères et comment + les plantes sortent de leurs semences, que si on avoit seulement considéré + quels ils ont été quand Dieu les a créés: tout + de même, nous ferons mieux entendre quelle est généralement + la nature de toutes les choses qui sont au monde si nous pouvons imaginer + quelques principes qui soient fort intelligibles et fort simples, desquels + nous puissions voir clairement que les astres et la terre et enfin tout ce + monde visible auroit pu être produit ainsi que de quelques semences + (bien que, nous sachions qu'il n'a pas été produit en cette + façon) que si nous la decrivions seulement comme il est, ou bien + comme nous croyons qu'il a été créé. Et + parceque je pense avoir trouvé des principes qui sont tels, je + tacherai ici de les expliquer." [*] + </p> + <ol class="footnotes"> + <li> + <i>Principes de la Philosophie</i>, Troisième partie, § 45. + </li> + </ol> + <p> + If we read between the lines of this singular exhibition of force of one + kind and weakness of another, it is clear that Descartes believed that he + had divined the mode in which the physical universe had been evolved; and + the "Traité de l'Homme," and the essay "Sur les Passions" afford + abundant additional evidence that he sought for, and thought he had found, + an explanation of the phenomena of physical life by deduction from purely + physical laws. + </p> + <p> + Spinoza abounds in the same sense, and is as usual perfectly candid-- + </p> + <p> + "Naturæ leges et regulæ, secundum quas omnia fiunt et ex unis + formis in alias mutantur, sunt ubique et semper eadem." [*] Leibnitz's + doctrine of continuity necessarily led him in the same direction; and, of + the infinite multitude of monads with which he peopled the world, each is + supposed to be the focus of an endless process of evolution and + involution. In the "Protogæa," xxvi., Leibnitz distinctly suggests + the mutability of species-- + </p> + <ol class="footnotes"> + <li> + <i>Ethices</i>, Pars tertia, Præfatio. + </li> + </ol> + <p> + "Alii mirantur in saxis passim species videri quas vel in orbe cognito, + vel saltem in vicinis locis frustra quæras. 'Ita Cornua Ammonis,' quæ + ex nautilorum numero habeantur, passim et forma et magnitudine (nam et + pedali diametro aliquando reperiuntur) ab omnibus illis naturis discrepare + dicunt, quas præbet mare. Sed quis absconditos ejus recessus aut + subterraneas abyssos pervestigavit? quam multa nobis animalia antea ignota + offert novus orbis? Et credibile est per magnas illas conversiones etiam + animalium species plurimum immutatas." + </p> + <p> + Thus, in the end of the seventeenth century, the seed was sown which has, + at intervals, brought forth recurrent crops of evolutional hypotheses, + based, more or less completely, on general reasonings. + </p> + <p> + Among the earliest of these speculations is that put forward by Benoit de + Maillet in his "Telliamed," which, though printed in 1735, was not + published until twenty-three years later. Considering that this book was + written before the time of Haller, or Bonnet, or Linnæus, or Hutton, + it surely deserves more respectful consideration than it usually receives. + For De Maillet not only has a definite conception of the plasticity of + living things, and of the production of existing species by the + modification of their predecessors; but he clearly apprehends the cardinal + maxim of modern geological science, that the explanation of the structure + of the globe is to be sought in the deductive application to geological + phenomena of the principles established inductively by the study of the + present course of nature. Somewhat later, Maupertuis [*] suggested a + curious hypothesis as to the causes of variation, which he thinks may be + sufficient to account for the origin of all animals from a single pair. + Robinet [*] followed out much the same line of thought as De Maillet, but + less soberly; and Bonnet's speculations in the "Palingénésie," + which appeared in 1769, have already been mentioned. Buffon (1753-1778), + at first a partisan of the absolute immutability of species, subsequently + appears to have believed that larger or smaller groups of species have + been produced by the modification of a primitive stock; but he contributed + nothing to the general doctrine of evolution. + </p> + <ol class="footnotes"> + <li> + <i>Système de la Nature</i>. "Essai sur la Formation des Corps + Organisés," 1751, xiv. + </li> + <li> + <i>Considérations Philosophiques sur la gradation naturelle des + formes de l'être; ou les essais de la nature qui apprend a faire + l'homme,</i> 1768. + </li> + </ol> + <p> + Erasmus Darwin ("Zoonomia," 1794), though a zealous evolutionist, can + hardly be said to have made any real advance on his predecessors; and, + notwithstanding that Goethe (1791-4) had the advantage of a wide knowledge + of morphological facts, and a true insight into their signification, while + he threw all the power of a great poet into the expression of his + conceptions, it may be questioned whether he supplied the doctrine of + evolution with a firmer scientific basis than it already possessed. + Moreover, whatever the value of Goethe's labours in that field, they were + not published before 1820, long after evolutionism had taken a new + departure from the works of Treviranus and Lamarck--the first of its + advocates who were equipped for their task with the needful large and + accurate knowledge of the phenomena of life, as a whole. It is remarkable + that each of these writers seems to have been led, independently and + contemporaneously, to invent the same name of "Biology" for the science of + the phenomena of life; and thus, following Buffon, to have recognised the + essential unity of these phenomena, and their contradistinction from those + of inanimate nature. And it is hard to say whether Lamarck or Treviranus + has the priority in propounding the main thesis of the doctrine of + evolution; for though the first volume of Treviranus's "Biologie" appeared + only in 1802, he says, in the preface to his later work, the + "Erscheinungen und Gesetze des organischen Lebens," dated 1831, that he + wrote the first volume of the "Biologie" "nearly five-and-thirty years + ago," or about 1796. + </p> + <p> + Now, in 1794, there is evidence that Lamarck held doctrines which present + a striking contrast to those which are to be found in the "Philosophie + Zoologique," as the following passages show:-- + </p> + <p> + "685. Quoique mon unique objet dans cet article n'ait été + que de traiter de la cause physique de l'entretien de la vie des êtres + organiques, malgré cela j'ai osé avancer en débutant, + que l'existence de ces êtres étonnants n'appartiennent + nullement à la nature; que tout ce qu'on peut entendre par le mot + <i>nature</i>, ne pouvoit donner la vie, c'est-à-dire, que toutes + les qualités de la matière, jointes à toutes les + circonstances possibles, et même à l'activité répandue + dans l'univers, ne pouvaient point produire un être muni du + mouvement organique, capable de reproduire son semblable, et sujet + à la mort. + </p> + <p> + "686. Tous les individus de cette nature, qui existent, proviennent + d'individus semblables qui tous ensemble constituent l'espèce entière. + Or, je crois qu'il est aussi impossible à l'homme de connôitre + la cause physique du premier individu de chaque espèce, que + d'assigner aussi physiquement la cause de l'existence de la matière + ou de l'univers entier. C'est au moins ce que le résultat de mes + connaissances et de mes réflexions me portent à penser. S'il + existe beaucoup de variétés produites par l'effet des + circonstances, ces variétés ne denaturent point les espèces; + mais on se trompe, sans doute souvent, en indiquant comme espèce, + ce qui n'est que variété; et alors je sens que cette erreur + peut tirer à conséquence dans les raisonnements que l'on + fait sur cette matière." [*] + </p> + <ol class="footnotes"> + <li> + <i>Recherches sur les causes des principaux faits physiques</i>, par + J.B. Lamarck. Paris. Seconde année de la République. In + the preface, Lamarck says that the work was written in 1776, and + presented to the Academy in 1780; but it was not published before 17994, + and, at that time, it presumably expressed Lamarck's mature views. It + would be interesting to know what brought about the change of opinion + manifested in the <i>Recherches sur l'organisation des corps vivants</i>, + published only seven years later. + </li> + </ol> + <p> + The first three volumes of Treviranus's "Biologie," which contain his + general views of evolution, appeared between 1802 and 1805. The + "Recherches sur l'organisation des corps vivants," in which the outlines + of Lamarck's doctrines are given, was published in 1802, but the full + development of his views, in the "Philosophie Zoologique," did not take + place until 1809. + </p> + <p> + The "Biologie" and the "Philosophie Zoologique" are both very remarkable + productions, and are still worthy of attentive study, but they fell upon + evil times. The vast authority of Cuvier was employed in support of the + traditionally respectable hypotheses of special creation and of + catastrophism; and the wild speculations of the "Discours sur les Révolutions + de la Surface du Globe" were held to be models of sound scientific + thinking, while the really much more sober and philosophical hypotheses of + the "Hydrogeologie" were scouted. For many years it was the fashion to + speak of Lamarck with ridicule, while Treviranus was altogether ignored. + </p> + <p> + Nevertheless, the work had been done. The conception of evolution was + henceforward irrepressible, and it incessantly reappears, in one shape or + another, [*] up to the year 1858, when Mr. Darwin and Mr. Wallace + published their "Theory of Natural Selection." The "Origin of Species" + appeared in 1859; and it is within the knowledge of all whose memories go + back to that time, that, henceforward, the doctrine of evolution has + assumed a position and acquired an importance which it never before + possessed. In the "Origin of Species," and in his other numerous and + important contributions to the solution of the problem of biological + evolution, Mr. Darwin confines himself to the discussion of the causes + which have brought about the present condition of living matter, assuming + such matter to have once come into existence. On the other hand, Mr. + Spencer [*] and Professor Haeckel [*] have dealt with the whole problem of + evolution. The profound and vigorous writings of Mr. Spencer embody the + spirit of Descartes in the knowledge of our own day, and may be regarded + as the "Principes de la Philosophie" of the nineteenth century; while, + whatever hesitation may not unfrequently be felt by less daring minds, in + following Haeckel in many of his speculations, his attempt to systematise + the doctrine of evolution and to exhibit its influence as the central + thought of modern biology, cannot fail to have a far-reaching influence on + the progress of science. + </p> + <ol class="footnotes"> + <li> + See the "Historical Sketch" prefixed to the last edition of the <i>Origin + of Species</i>. + </li> + <li> + <i>First Principles</i>. and <i>Principles of Biology</i>, 1860-1864. + </li> + <li> + <i>Generelle Marphologie</i>, 1866. + </li> + </ol> + <p> + If we seek for the reason of the difference between the scientific + position of the doctrine of evolution a century ago, and that which it + occupies now, we shall find it in the great accumulation of facts, the + several classes of which have been enumerated above, under the second to + the eighth heads. For those which are grouped under the second to the + seventh of these classes, respectively, have a clear significance on the + hypothesis of evolution, while they are unintelligible if that hypothesis + be denied. And those of the eighth group are not only unintelligible + without the assumption of evolution, but can be proved never to be + discordant with that hypothesis, while, in some cases, they are exactly + such as the hypothesis requires. The demonstration of these assertions + would require a volume, but the general nature of the evidence on which + they rest may be briefly indicated. + </p> + <p> + 2. The accurate investigation of the lowest forms of animal life, + commenced by Leeuwenhoek and Swammerdam, and continued by the remarkable + labours of Reaumur, Trembley, Bonnet, and a host of other observers, in + the latter part of the seventeenth and the first half of the eighteenth + centuries, drew the attention of biologists to the gradation in the + complexity of organisation which is presented by living beings, and + culminated in the doctrine of the "échelle des êtres," so + powerfully and clearly stated by Bonnet; and, before him, adumbrated by + Locke and by Leibnitz. In the then state of knowledge, it appeared that + all the species of animals and plants could be arranged in one series; in + such a manner that, by insensible gradations, the mineral passed into the + plant, the plant into the polype, the polype into the worm, and so, + through gradually higher forms of life, to man, at the summit of the + animated world. + </p> + <p> + But, as knowledge advanced, this conception ceased to be tenable in the + crude form in which it was first put forward. Taking into account existing + animals and plants alone, it became obvious that they fell into groups + which were more or less sharply separated from one another; and, moreover, + that even the species of a genus can hardly ever be arranged in linear + series. Their natural resemblances and differences are only to be + expressed by disposing them as if they were branches springing from a + common hypothetical centre. + </p> + <p> + Lamarck, while affirming the verbal proposition that animals form a single + series, was forced by his vast acquaintance with the details of zoology to + limit the assertion to such a series as may be formed out of the + abstractions constituted by the common characters of each group. [*] + </p> + <ol class="footnotes"> + <li> + "Il s'agit donc de prouver que la série qui constitue l'échelle + animale réside essentiellement dans la distribution des masses + principales qui la composent et non dans celle des espèces ni même + toujours dans celle des genres."--<i>Philosophie Zoologique</i>. chap. + v. + </li> + </ol> + <p> + Cuvier on anatomical, and Von Baer on embryological grounds, made the + further step of proving that, even in this limited sense, animals cannot + be arranged in a single series, but that there are several distinct plans + of organisation to be observed among them, no one of which, in its highest + and most complicated modification, leads to any of the others. + </p> + <p> + The conclusions enunciated by Cuvier and Von Baer have been confirmed, in + principle, by all subsequent research into the structure of animals and + plants. But the effect of the adoption of these conclusions has been + rather to substitute a new metaphor for that of Bonnet than to abolish the + conception expressed by it. Instead of regarding living things as capable + of arrangement in one series like the steps of a ladder, the results of + modern investigation compel us to dispose them as if they were the twigs + and branches of a tree. The ends of the twigs represent individuals, the + smallest groups of twigs species, larger groups genera, and so on, until + we arrive at the source of all these ramifications of the main branch, + which is represented by a common plan of structure. At the present moment, + it is impossible to draw up any definition, based on broad anatomical or + developmental characters, by which any one of Cuvier's great groups shall + be separated from all the rest. On the contrary, the lower members of each + tend to converge towards the lower members of all the others. The same may + be said of the vegetable world. The apparently clear distinction between + flowering and flowerless plants has been broken down by the series of + gradations between the two exhibited by the <i>Lycopodiaceæ, + Rhizocarpeæ</i>, and <i>Gymnospermeæ</i>. The groups of <i>Fungi</i>, + <i>Lichenes</i>, and <i>Algæ</i> have completely run into one + another, and, when the lowest forms of each are alone considered, even the + animal and vegetable kingdoms cease to have a definite frontier. + </p> + <p> + If it is permissible to speak of the relations of living forms to one + another metaphorically, the similitude chosen must undoubtedly be that of + a common root, whence two main trunks, one representing the vegetable and + one the animal world, spring; and, each dividing into a few main branches, + these subdivide into multitudes of branchlets and these into smaller + groups of twigs. + </p> + <p> + As Lamarck has well said--[*] "Il n'y a que ceux qui se sont longtemps et + fortement occupés de la détermination des espèces, et + qui ont consulté de riches collections, qui peuvent savoir jusqu'à + quel point les <i>espèces</i>, parmi les corps vivants se fondent + les unes dans les autres, et qui ont pu se convaincre que, dans les + parties où nous voyons des <i>espèces</i> isolès, + cela n'est ainsi que parcequ'il nous en manque d'autres qui en sont plus + voisines et que nous n'avons pas encore recueillies. + </p> + <ol class="footnotes"> + <li> + <i>Philosophie Zoologique</i>, première partie, chap. iii. + </li> + </ol> + <p> + "Je ne veux pas dire pour cela que les animaux qui existent forment une série + très-simple et partout également nuancée; mais je dis + qu'ils forment une série ramense, irréguliérement + graduée et qui n'a point de discontinuité dans ses parties, + ou qui, du moins, n'en a toujours pas eu, s'il est vrai que, par suite de + quelques espèces perdues, il s'en trouve quelque part. Il en + resulte que les <i>espèces</i> qui terminent chaque rameau de la série + générale tiennent, au moins d'un côté, à + d'autres espèces voisines qui se nuancent avec elles. Voilà + ce que l'état bien connu des choses me met maintenant à portée + de demontrer. Je n'ai besoin d'aucune hypothèse ni d'aucune + supposition pour cela: j'en atteste tous les naturalistes observateurs." + </p> + <p> + 3. In a remarkable essay [*] Meckel remarks-- + </p> + <ol class="footnotes"> + <li> + "Entwurf einer Darstellung der zwischen dem Embryozustände der höheren + Thiere und dem permanenten der niederen stattfindenden Parallele," <i>Beyträge + zur Vergleichenden Anatomie</i>, Bd. ii. 1811. + </li> + </ol> + <p> + "There is no good physiologist who has not been struck by the observation + that the original form of all organisms is one and the same, and that out + of this one form, all, the lowest as well as the highest, are developed in + such a manner that the latter pass through the permanent forms of the + former as transitory stages. Aristotle, Haller, Harvey, Kielmeyer, + Autenrieth, and many others, have either made this observation + incidentally, or, especially the latter, have drawn particular attention + to it, and deduced therefrom results of permanent importance for + physiology." + </p> + <p> + Meckel proceeds to exemplify the thesis, that the lower forms of animals + represent stages in the course of the development of the higher, with a + large series of illustrations. + </p> + <p> + After comparing the Salamanders and the perennibranchiate <i>Urodela</i> + with the Tadpoles and the Frogs, and enunciating the law that the more + highly any animal is organised the more quickly does it pass through the + lower stages, Meckel goes on to say-- + </p> + <p> + "From these lowest Vertebrata to the highest, and to the highest forms + among these, the comparison between the embryonic conditions of the higher + animals and the adult states of the lower can be more completely and + thoroughly instituted than if the survey is extended to the Invertebrata, + inasmuch as the latter are in many respects constructed upon an altogether + too dissimilar type; indeed they often differ from one another far more + than the lowest vertebrate does from the highest mammal; yet the following + pages will show that the comparison may also be extended to them with + interest. In fact, there is a period when, as Aristotle long ago said, the + embryo of the highest animal has the form of a mere worm; and, devoid of + internal and external organisation, is merely an almost structureless lump + of polype substance. Notwithstanding the origin of organs, it still for a + certain time, by reason of its want of an internal bony skeleton, remains + worm and mollusk, and only later enters into the series of the Vertebrata, + although traces of the vertebral column even in the earliest periods + testify its claim to a place in that series."--<i>Op, cit</i> pp. 4, 5. + </p> + <p> + If Meckel's proposition is so far qualified, that the comparison of adult + with embryonic forms is restricted within the limits of one type of + organisation; and, if it is further recollected that the resemblance + between the permanent lower form and the embryonic stage of a higher form + is not special but general, it is in entire accordance with modern + embryology; although there is no branch of biology which has grown so + largely, and improved its methods so much, since Meckel's time, as this. + In its original form, the doctrine of "arrest of development," as + advocated by Geoffroy Saint-Hilaire and Serres, was no doubt an + overstatement of the case. It is not true, for example, that a fish is a + reptile arrested in its development, or that a reptile was ever a fish: + but it is true that the reptile embryo, at one stage of its development, + is an organism which, if it had an independent existence, must be + classified among fishes; and all the organs of the reptile pass, in the + course of their development, through conditions which are closely + analogous to those which are permanent in some fishes. + </p> + <p> + 4. That branch of biology which is termed Morphology is a commentary upon, + and expansion of, the proposition that widely different animals or plants, + and widely different parts of animals or plants, are constructed upon the + same plan. From the rough comparison of the skeleton of a bird with that + of a man by Belon, in the sixteenth century (to go no farther back), down + to the theory of the limbs and the theory of the skull at the present day; + or, from the first demonstration of the homologies of the parts of a + flower by C. F. Wolff, to the present elaborate analysis of the floral + organs, morphology exhibits a continual advance towards the demonstration + of a fundamental unity among the seeming diversities of living structures. + And this demonstration has been completed by the final establishment of + the cell theory, which involves the admission of a primitive conformity, + not only of all the elementary structures in animals and plants + respectively, but of those in the one of these great divisions of living + things with those in the other. No <i>à priori</i> difficulty can + be said to stand in the way of evolution, when it can be shown that all + animals and all plants proceed by modes of development, which are similar + in principle, from a fundamental protoplasmic material. + </p> + <p> + 5. The innumerable cases of structures, which are rudimentary and + apparently useless, in species, the close allies of which possess + well-developed and functionally important homologous structures, are + readily intelligible on the theory of evolution, while it is hard to + conceive their <i>raison d'être</i> on any other hypothesis. + However, a cautious reasoner will probably rather explain such cases + deductively from the doctrine of evolution than endeavour to support the + doctrine of evolution by them. For it is almost impossible to prove that + any structure, however rudimentary, is useless--that is to say, that it + plays no part whatever in the economy; and, if it is in the slightest + degree useful, there is no reason why, on the hypothesis of direct + creation, it should not have been created. Nevertheless, double-edged as + is the argument from rudimentary organs, there is probably none which has + produced a greater effect in promoting the general acceptance of the + theory of evolution. + </p> + <p> + 6. The older advocates of evolution sought for the causes of the process + exclusively in the influence of varying conditions, such as climate and + station, or hybridisation, upon living forms. Even Treviranus has got no + farther than this point. Lamarck introduced the conception of the action + of an animal on itself as a factor in producing modification. Starting + from the well-known fact that the habitual use of a limb tends to develop + the muscles of the limb, and to produce a greater and greater facility in + using it, he made the general assumption that the effort of an animal to + exert an organ in a given direction tends to develop the organ in that + direction. But a little consideration showed that, though Lamarck had + seized what, as far it goes, is a true cause of modification, it is a + cause the actual effects of which are wholly inadequate to account for any + considerable modification in animals, and which can have no influence at + all in the vegetable world; and probably nothing contributed so much to + discredit evolution, in the early part of this century, as the floods of + easy ridicule which were poured upon this part of Lamarck's speculation. + The theory of natural selection, or survival of the fittest, was suggested + by Wells in 1813, and further elaborated by Matthew in 1831. But the + pregnant suggestions of these writers remained practically unnoticed and + forgotten, until the theory was independently devised and promulgated by + Darwin and Wallace in 1858, and the effect of its publication was + immediate and profound. + </p> + <p> + Those who were unwilling to accept evolution, without better grounds than + such as are offered by Lamarck, or the author of that particularly + unsatisfactory book, the "Vestiges of the Natural History of the + Creation," and who therefore preferred to suspend their judgment on the + question, found in the principle of selective breeding, pursued in all its + applications with marvellous knowledge and skill by Mr. Darwin, a valid + explanation of the occurrence of varieties and races; and they saw clearly + that, if the explanation would apply to species, it would not only solve + the problem of their evolution, but that it would account for the facts of + teleology, as well as for those of morphology; and for the persistence of + some forms of life unchanged through long epochs of time, while others + undergo comparatively rapid metamorphosis. + </p> + <p> + How far "natural selection" suffices for the production of species remains + to be seen. Few can doubt that, if not the whole cause, it is a very + important factor in that operation; and that it must play a great part in + the sorting out of varieties into those which are transitory and those + which are permanent. + </p> + <p> + But the causes and conditions of variation have yet to be thoroughly + explored; and the importance of natural selection will not be impaired, + even if further inquiries should prove that variability is definite, and + is determined in certain directions rather than in others, by conditions + inherent in that which varies. It is quite conceivable that every species + tends to produce varieties of a limited number and kind, and that the + effect of natural selection is to favour the development of some of these, + while it opposes the development of others along their predetermined lines + of modification. + </p> + <p> + 7. No truths brought to light by biological investigation were better + calculated to inspire distrust of the dogmas intruded upon science in the + name of theology, than those which relate to the distribution of animals + and plants on the surface of the earth. Very skilful accommodation was + needful, if the limitation of sloths to South America, and of the + ornithorhynchus to Australia, was to be reconciled with the literal + interpretation of the history of the deluge; and with the establishment of + the existence of distinct provinces of distribution, any serious belief in + the peopling of the world by migration from Mount Ararat came to an end. + </p> + <p> + Under these circumstances, only one alternative was left for those who + denied the occurrence of evolution--namely, the supposition that the + characteristic animals and plants of each great province were created as + such, within the limits in which we find them. And as the hypothesis of + "specific centres," thus formulated, was heterodox from the theological + point of view, and unintelligible under its scientific aspect, it may be + passed over without further notice, as a phase of transition from the + creational to the evolutional hypothesis. + </p> + <p> + 8. In fact, the strongest and most conclusive arguments in favour of + evolution are those which are based upon the facts of geographical, taken + in conjunction with those of geological, distribution. + </p> + <p> + Both Mr. Darwin and Mr. Wallace lay great stress on the close relation + which obtains between the existing fauna of any region and that of the + immediately antecedent geological epoch in the same region; and rightly, + for it is in truth inconceivable that there should be no genetic + connection between the two. It is possible to put into words the + proposition that all the animals and plants of each geological epoch were + annihilated and that a new set of very similar forms was created for the + next epoch; but it may be doubted if any one who ever tried to form a + distinct mental image of this process of spontaneous generation on the + grandest scale, ever really succeeded in realising it. + </p> + <p> + Within the last twenty years, the attention of the best palæontologists + has been withdrawn from the hodman's work of making "new species" of + fossils, to the scientific task of completing our knowledge of individual + species, and tracing out the succession of the forms presented by any + given type in time. + </p> + <p> + Those who desire to inform themselves of the nature and extent of the + evidence bearing on these questions may consult the works of Rütimeyer, + Gaudry, Kowalewsky, Marsh, and the writer of the present article. It must + suffice, in this place, to say that the successive forms of the Equine + type have been fully worked out; while those of nearly all the other + existing types of Ungulate mammals and of the <i>Carnivora</i> have been + almost as closely followed through the Tertiary deposits; the gradations + between birds and reptiles have been traced; and the modifications + undergone by the <i>Crocodilia</i>, from the Triassic epoch to the present + day, have been demonstrated. On the evidence of palæontology, the + evolution of many existing forms of animal life from their predecessors is + no longer an hypothesis, but an historical fact; it is only the nature of + the physiological factors to which that evolution is due which is still + open to discussion. + </p> + <p> + [At page 209, the reference to Erasmus Darwin does not do justice to that + ingenious writer, who, in the 39th section of the <i>Zoonomia</i>, clearly + and repeatedly enunciates the theory of the inheritance of acquired + modifications. For example "From their first rudiment, or primordium, to + the termination of their lives, all animals undergo perpetual + transformations; which are in part produced by their own exertions in + consequence of their desires and aversions, of their pleasures and their + pains, or of irritation, or of associations; and many of these acquired + forms or propensities are transmitted to their posterity." <i>Zoonomia</i> + I., p. 506. 1893.] + </p> + <h2 id="c7"> + VII The Coming Of Age Of "The Origin Of Species" + </h2> + <p> + [1880] + </p> + <p> + Many of you will be familiar with the aspect of this small green-covered + book. It is a copy of the first edition of the "Origin of Species," and + bears the date of its production--the 1st of October 1859. Only a few + months, therefore, are needed to complete the full tale of twenty-one + years since its birthday. + </p> + <p> + Those whose memories carry them back to this time will remember that the + infant was remarkably lively, and that a great number of excellent persons + mistook its manifestations of a vigorous individuality for mere + naughtiness; in fact there was a very pretty turmoil about its cradle. My + recollections of the period are particularly vivid, for, having conceived + a tender affection for a child of what appeared to me to be such + remarkable promise, I acted for some time in the capacity of a sort of + under-nurse, and thus came in for my share of the storms which threatened + the very life of the young creature. For some years it was undoubtedly + warm work; but considering how exceedingly unpleasant the apparition of + the newcomer must have been to those who did not fall in love with him at + first sight, I think it is to the credit of our age that the war was not + fiercer, and that the more bitter and unscrupulous forms of opposition + died away as soon as they did. + </p> + <p> + I speak of this period as of something past and gone, possessing merely an + historical, I had almost said an antiquarian interest. For, during the + second decade of the existence of the "Origin of Species," opposition, + though by no means dead, assumed a different aspect. On the part of all + those who had any reason to respect themselves, it assumed a thoroughly + respectful character. By this time, the dullest began to perceive that the + child was not likely to perish of any congenital weakness or infantile + disorder, but was growing into a stalwart personage, upon whom mere goody + scoldings and threatenings with the birch-rod were quite thrown away. + </p> + <p> + In fact, those who have watched the progress of science within the last + ten years will bear me out to the full, when I assert that there is no + field of biological inquiry in which the influence of the "Origin of + Species" is not traceable; the foremost men of science in every country + are either avowed champions of its leading doctrines, or at any rate + abstain from opposing them; a host of young and ardent investigators seek + for and find inspiration and guidance in Mr. Darwin's great work; and the + general doctrine of evolution, to one side of which it gives expression, + obtains, in the phenomena of biology, a firm base of operations whence it + may conduct its conquest of the whole realm of Nature. + </p> + <p> + History warns us, however, that it is the customary fate of new truths to + begin as heresies and to end as superstitions; and, as matters now stand, + it is hardly rash to anticipate that, in another twenty years, the new + generation, educated under the influences of the present day, will be in + danger of accepting the main doctrines of the "Origin of Species," with as + little reflection, and it may be with as little justification, as so many + of our contemporaries, twenty years ago, rejected them. + </p> + <p> + Against any such a consummation let us all devoutly pray; for the + scientific spirit is of more value than its products, and irrationally + held truths may be more harmful than reasoned errors. Now the essence of + the scientific spirit is criticism. It tells us that whenever a doctrine + claims our assent we should reply, Take it if you can compel it. The + struggle for existence holds as much in the intellectual as in the + physical world. A theory is a species of thinking, and its right to exist + is coextensive with its power of resisting extinction by its rivals. + </p> + <p> + From this point of view, it appears to me that it would be but a poor way + of celebrating the Coming of Age of the "Origin of Species," were I merely + to dwell upon the facts, undoubted and remarkable as they are, of its + far-reaching influence and of the great following of ardent disciples who + are occupied in spreading and developing its doctrines. Mere insanities + and inanities have before now swollen to portentous size in the course of + twenty years. Let us rather ask this prodigious change in opinion to + justify itself: let us inquire whether anything has happened since 1859, + which will explain, on rational grounds, why so many are worshipping that + which they burned, and burning that which they worshipped. It is only in + this way that we shall acquire the means of judging whether the movement + we have witnessed is a mere eddy of fashion, or truly one with the + irreversible current of intellectual progress, and, like it, safe from + retrogressive reaction. + </p> + <p> + Every belief is the product of two factors: the first is the state of the + mind to which the evidence in favour of that belief is presented; and the + second is the logical cogency of the evidence itself. In both these + respects, the history of biological science during the last twenty years + appears to me to afford an ample explanation of the change which has taken + place; and a brief consideration of the salient events of that history + will enable us to understand why, if the "Origin of Species" appeared now, + it would meet with a very different reception from that which greeted it + in 1859. + </p> + <p> + One-and-twenty years ago, in spite of the work commenced by Hutton and + continued with rare skill and patience by Lyell, the dominant view of the + past history of the earth was catastrophic. Great and sudden physical + revolutions, wholesale creations and extinctions of living beings, were + the ordinary machinery of the geological epic brought into fashion by the + misapplied genius of Cuvier. It was gravely maintained and taught that the + end of every geological epoch was signalised by a cataclysm, by which + every living being on the globe was swept away, to be replaced by a + brand-new creation when the world returned to quiescence. A scheme of + nature which appeared to be modelled on the likeness of a succession of + rubbers of whist, at the end of each of which the players upset the table + and called for a new pack, did not seem to shock anybody. + </p> + <p> + I may be wrong, but I doubt if, at the present time, there is a single + responsible representative of these opinions left. The progress of + scientific geology has elevated the fundamental principle of + uniformitarianism, that the explanation of the past is to be sought in the + study of the present, into the position of an axiom; and the wild + speculations of the catastrophists, to which we all listened with respect + a quarter of a century ago, would hardly find a single patient hearer at + the present day. No physical geologist now dreams of seeking, outside the + range of known natural causes, for the explanation of anything that + happened millions of years ago, any more than he would be guilty of the + like absurdity in regard to current events. + </p> + <p> + The effect of this change of opinion upon biological speculation is + obvious. For, if there have been no periodical general physical + catastrophes, what brought about the assumed general extinctions and + re-creations of life which are the corresponding biological catastrophes? + And, if no such interruptions of the ordinary course of nature have taken + place in the organic, any more than in the inorganic, world, what + alternative is there to the admission of evolution? + </p> + <p> + The doctrine of evolution in biology is the necessary result of the + logical application of the principles of uniformitarianism to the + phenomena of life. Darwin is the natural successor of Hutton and Lyell, + and the "Origin of Species" the logical sequence of the "Principles of + Geology." + </p> + <p> + The fundamental doctrine of the "Origin of Species," as of all forms of + the theory of evolution applied to biology, is "that the innumerable + species, genera, and families of organic beings with which the world is + peopled have all descended, each within its own class or group, from + common parents, and have all been modified in the course of descent." [*] + </p> + <ol class="footnotes"> + <li> + <i>Origin of Species</i>, ed. I, p. 457. + </li> + </ol> + <p> + And, in view of the facts of geology, it follows that all living animals + and plants "are the lineal descendants of those which lived long before + the Silurian epoch." [*] + </p> + <ol class="footnotes"> + <li> + <i>Origin of Species</i>, p. 458. + </li> + </ol> + <p> + It is an obvious consequence of this theory of descent with modification, + as it is sometimes called, that all plants and animals, however different + they may now be, must, at one time or other, have been connected by direct + or indirect intermediate gradations, and that the appearance of isolation + presented by various groups of organic beings must be unreal. + </p> + <p> + No part of Mr. Darwin's work ran more directly counter to the + prepossessions of naturalists twenty years ago than this. And such + prepossessions were very excusable, for there was undoubtedly a great deal + to be said, at that time, in favour of the fixity of species and of the + existence of great breaks, which there was no obvious or probable means of + filling up, between various groups of organic beings. + </p> + <p> + For various reasons, scientific and unscientific, much had been made of + the hiatus between man and the rest of the higher mammalia, and it is no + wonder that issue was first joined on this part of the controversy. I have + no wish to revive past and happily forgotten controversies; but I must + state the simple fact that the distinctions in the cerebral and other + characters, which were so hotly affirmed to separate man from all other + animals in 1860, have all been demonstrated to be non-existent, and that + the contrary doctrine is now universally accepted and taught. + </p> + <p> + But there were other cases in which the wide structural gaps asserted to + exist between one group of animals and another were by no means + fictitious; and, when such structural breaks were real, Mr. Darwin could + account for them only by supposing that the intermediate forms which once + existed had become extinct. In a remarkable passage he says-- + </p> + <p> + "We may thus account even for the distinctness of whole classes from each + other--for instance, of birds from all other vertebrate animals--by the + belief that many animal forms of life have been utterly lost, through + which the early progenitors of birds were formerly connected with the + early progenitors of the other vertebrate classes." [*] Adverse criticism + made merry over such suggestions as these. Of course it was easy to get + out of the difficulty by supposing extinction; but where was the slightest + evidence that such intermediate forms between birds and reptiles as the + hypothesis required ever existed? And then probably followed a tirade upon + this terrible forsaking of the paths of "Baconian induction." + </p> + <ol class="footnotes"> + <li> + <i>Origin of Species</i>, p. 431. + </li> + </ol> + <p> + But the progress of knowledge has justified Mr. Darwin to an extent which + could hardly have been anticipated. In 1862, the specimen of <i>Archæopteryx</i>, + which, until the last two or three years, has remained unique, was + discovered; and it is an animal which, in its feathers and the greater + part of its organisation, is a veritable bird, while, in other parts, it + is as distinctly reptilian. + </p> + <p> + In 1868, I had the honour of bringing under your notice, in this theatre, + the results of investigations made, up to that time, into the anatomical + characters of certain ancient reptiles, which showed the nature of the + modifications in virtue of which the type of the quadrupedal reptile + passed into that of a bipedal bird; and abundant confirmatory evidence of + the justice of the conclusions which I then laid before you has since come + to light. + </p> + <p> + In 1875, the discovery of the toothed birds of the cretaceous formation in + North America by Professor Marsh completed the series of transitional + forms between birds and reptiles, and removed Mr. Darwin's proposition + that "many animal forms of life have been utterly lost, through which the + early progenitors of birds were formerly connected with the early + progenitors of the other vertebrate classes," from the region of + hypothesis to that of demonstrable fact. + </p> + <p> + In 1859, there appeared to be a very sharp and clear hiatus between + vertebrated and invertebrated animals, not only in their structure, but, + what was more important, in their development. I do not think that we even + yet know the precise links of connection between the two; but the + investigations of Kowalewsky and others upon the development of <i>Amphioxus</i> + and of the <i>Tunicata</i> prove, beyond a doubt, that the differences + which were supposed to constitute a barrier between the two are + non-existent. There is no longer any difficulty in understanding how the + vertebrate type may have arisen from the invertebrate, though the full + proof of the manner in which the transition was actually effected may + still be lacking. + </p> + <p> + Again, in 1859, there appeared to be a no less sharp separation between + the two great groups of flowering and flowerless plants. It is only + subsequently that the series of remarkable investigations inaugurated by + Hofmeister has brought to light the extraordinary and altogether + unexpected modifications of the reproductive apparatus in the <i>Lycopodiaceæ</i>, + the <i>Rhizocarpeæ</i>, and the <i>Gymnospermeæ</i>, by which + the ferns and the mosses are gradually connected with the Phanerogamic + division of the vegetable world. + </p> + <p> + So, again, it is only since 1859 that we have acquired that wealth of + knowledge of the lowest forms of life which demonstrates the futility of + any attempt to separate the lowest plants from the lowest animals, and + shows that the two kingdoms of living nature have a common borderland + which belongs to both, or to neither. + </p> + <p> + Thus it will be observed that the whole tendency of biological + investigation, since 1859, has been in the direction of removing the + difficulties which the apparent breaks in the series created at that time; + and the recognition of gradation is the first step towards the acceptance + of evolution. + </p> + <p> + As another great factor in bringing about the change of opinion which has + taken place among naturalists, I count the astonishing progress which has + been made in the study of embryology. Twenty years ago, not only were we + devoid of any accurate knowledge of the mode of development of many groups + of animals and plants, but the methods of investigation were rude and + imperfect. At the present time, there is no important group of organic + beings the development of which has not been carefully studied; and the + modern methods of hardening and section-making enable the embryologist to + determine the nature of the process, in each case, with a degree of + minuteness and accuracy which is truly astonishing to those whose memories + carry them back to the beginnings of modern histology. And the results of + these embryological investigations are in complete harmony with the + requirements of the doctrine of evolution. The first beginnings of all the + higher forms of animal life are similar, and however diverse their adult + conditions, they start from a common foundation. Moreover, the process of + development of the animal or the plant from its primary egg, or germ, is a + true process of evolution--a progress from almost formless to more or less + highly organised matter, in virtue of the properties inherent in that + matter. + </p> + <p> + To those who are familiar with the process of development, all <i>a priori</i> + objections to the doctrine of biological evolution appear childish. Any + one who has watched the gradual formation of a complicated animal from the + protoplasmic mass, which constitutes the essential element of a frog's or + a hen's egg, has had under his eyes sufficient evidence that a similar + evolution of the whole animal world from the like foundation is, at any + rate, possible. + </p> + <p> + Yet another product of investigation has largely contributed to the + removal of the objections to the doctrine of evolution current in 1859. It + is the proof afforded by successive discoveries that Mr. Darwin did not + over-estimate the imperfection of the geological record. No more striking + illustration of this is needed than a comparison of our knowledge of the + mammalian fauna of the Tertiary epoch in 1859 with its present condition. + M. Gaudry's researches on the fossils of Pikermi were published in 1868, + those of Messrs. Leidy, Marsh, and Cope, on the fossils of the Western + Territories of America, have appeared almost wholly since 1870, those of + M. Filhol on the phosphorites of Quercy in 1878. The general effect of + these investigations has been to introduce to us a multitude of extinct + animals, the existence of which was previously hardly suspected; just as + if zoologists were to become acquainted with a country, hitherto unknown, + as rich in novel forms of life as Brazil or South Africa once were to + Europeans. Indeed, the fossil fauna of the Western Territories of America + bid fair to exceed in interest and importance all other known Tertiary + deposits put together; and yet, with the exception of the case of the + American tertiaries, these investigations have extended over very limited + areas; and, at Pikermi, were confined to an extremely small space. + </p> + <p> + Such appear to me to be the chief events in the history of the progress of + knowledge during the last twenty years, which account for the changed + feeling with which the doctrine of evolution is at present regarded by + those who have followed the advance of biological science, in respect of + those problems which bear indirectly upon that doctrine. + </p> + <p> + But all this remains mere secondary evidence. It may remove dissent, but + it does not compel assent. Primary and direct evidence in favour of + evolution can be furnished only by palæontology. The geological + record, so soon as it approaches completeness, must, when properly + questioned, yield either an affirmative or a negative answer: if evolution + has taken place, there will its mark be left; if it has not taken place, + there will lie its refutation. + </p> + <p> + What was the state of matters in 1859? Let us hear Mr. Darwin, who may be + trusted always to state the case against himself as strongly as possible. + </p> + <p> + "On this doctrine of the extermination of an infinitude of connecting + links between the living and extinct inhabitants of the world, and at each + successive period between the extinct and still older species, why is not + every geological formation charged with such links? Why does not every + collection of fossil remains afford plain evidence of the gradation and + mutation of the forms of life? We meet with no such evidence, and this is + the most obvious and plausible of the many objections which may be urged + against my theory." [*] + </p> + <ol class="footnotes"> + <li> + <i>Origin of Species</i>, ed. 1, p. 463. + </li> + </ol> + <p> + Nothing could have been more useful to the opposition than this + characteristically candid avowal, twisted as it immediately was into an + admission that the writer's views were contradicted by the facts of palæontology. + But, in fact, Mr. Darwin made no such admission. What he says in effect + is, not that palæontological evidence is against him, but that it is + not distinctly in his favour; and, without attempting to attenuate the + fact, he accounts for it by the scantiness and the imperfection of that + evidence. + </p> + <p> + What is the state of the case now, when, as we have seen, the amount of + our knowledge respecting the mammalia of the Tertiary epoch is increased + fifty-fold, and in some directions even approaches completeness? + </p> + <p> + Simply this, that, if the doctrine of evolution had not existed, + palaeontologists must have invented it, so irresistibly is it forced upon + the mind by the study of the remains of the Tertiary mammalia which have + been brought to light since 1859. + </p> + <p> + Among the fossils of Pikermi, Gaudry found the successive stages by which + the ancient civets passed into the more modern hyænas; through the + Tertiary deposits of Western America, Marsh tracked the successive forms + by which the ancient stock of the horse has passed into its present form; + and innumerable less complete indications of the mode of evolution of + other groups of the higher mammalia have been obtained. In the remarkable + memoir on the phosphorites of Quercy, to which I have referred, M. Filhol + describes no fewer than seventeen varieties of the genus <i>Cynodictis</i>, + which fill up all the interval between the viverine animals and the + bear-like dog <i>Amphicyon</i>; nor do I know any solid ground of + objection to the supposition that, in this <i>Cynodictis-Amphicyon</i> + group, we have the stock whence all the Viveridæ, Felidæ, Hyænidæ, + Canidæ, and perhaps the Procyonidæ and Ursidæ, of the + present fauna have been evolved. On the contrary, there is a great deal to + be said in favour. + </p> + <p> + In the course of summing up his results, M. Filhol observes:-- + </p> + <p> + "During the epoch of the phosphorites, great changes took place in animal + forms, and almost the same types as those which now exist became defined + from one another. + </p> + <p> + "Under the influence of natural conditions of which we have no exact + knowledge, though traces of them are discoverable, species have been + modified in a thousand ways: races have arisen which, becoming fixed, have + thus produced a corresponding number of secondary species." + </p> + <p> + In 1859, language of which this is an unintentional paraphrase, occurring + in the "Origin of Species," was scouted as wild speculation; at present, + it is a sober statement of the conclusions to which an acute and + critically-minded investigator is led by large and patient study of the + facts of palæontology. I venture to repeat what I have said before, + that so far as the animal world is concerned, evolution is no longer a + speculation, but a statement of historical fact. It takes its place + alongside of those accepted truths which must be reckoned with by + philosophers of all schools. + </p> + <p> + Thus when, on the first day of October next, "The Origin of Species" comes + of age, the promise of its youth will be amply fulfilled; and we shall be + prepared to congratulate the venerated author of the book, not only that + the greatness of his achievement and its enduring influence upon the + progress of knowledge have won him a place beside our Harvey; but, still + more, that, like Harvey, he has lived long enough to outlast detraction + and opposition, and to see the stone that the builders rejected become the + head-stone of the corner. + </p> + <h2 id="c8"> + VIII Charles Darwin + </h2> + <p> + [<i>Nature</i>, April 27th, 1882] + </p> + <p> + Very few, even among those who have taken the keenest interest in the + progress of the revolution in natural knowledge set afoot by the + publication of "The Origin of Species," and who have watched, not without + astonishment, the rapid and complete change which has been effected both + inside and outside the boundaries of the scientific world in the attitude + of men's minds towards the doctrines which are expounded in that great + work, can have been prepared for the extraordinary manifestation of + affectionate regard for the man, and of profound reverence for the + philosopher, which followed the announcement, on Thursday last, of the + death of Mr. Darwin. + </p> + <p> + Not only in these islands, where so many have felt the fascination of + personal contact with an intellect which had no superior, and with a + character which was even nobler than the intellect; but, in all parts of + the civilised world, it would seem that those whose business it is to feel + the pulse of nations and to know what interests the masses of mankind, + were well aware that thousands of their readers would think the world the + poorer for Darwin's death, and would dwell with eager interest upon every + incident of his history. In France, in Germany, in Austro-Hungary, in + Italy, in the United States, writers of all shades of opinion, for once + unanimous, have paid a willing tribute to the worth of our great + countryman, ignored in life by the official representatives of the + kingdom, but laid in death among his peers in Westminster Abbey by the + will of the intelligence of the nation. + </p> + <p> + It is not for us to allude to the sacred sorrows of the bereaved home at + Down; but it is no secret that, outside that domestic group, there are + many to whom Mr. Darwin's death is a wholly irreparable loss. And this not + merely because of his wonderfully genial, simple, and generous nature; his + cheerful and animated conversation, and the infinite variety and accuracy + of his information; but because the more one knew of him, the more he + seemed the incorporated ideal of a man of science. Acute as were his + reasoning powers, vast as was his knowledge, marvellous as was his + tenacious industry, under physical difficulties which would have converted + nine men out of ten into aimless invalids; it was not these qualities, + great as they were, which impressed those who were admitted to his + intimacy with involuntary veneration, but a certain intense and almost + passionate honesty by which all his thoughts and actions were irradiated, + as by a central fire. + </p> + <p> + It was this rarest and greatest of endowments which kept his vivid + imagination and great speculative powers within due bounds; which + compelled him to undertake the prodigious labours of original + investigation and of reading, upon which his published works are based; + which made him accept criticisms and suggestions from anybody and + everybody, not only without impatience, but with expressions of gratitude + sometimes almost comically in excess of their value; which led him to + allow neither himself nor others to be deceived by phrases, and to spare + neither time nor pains in order to obtain clear and distinct ideas upon + every topic with which he occupied himself. + </p> + <p> + One could not converse with Darwin without being reminded of Socrates. + There was the same desire to find some one wiser than himself; the same + belief in the sovereignty of reason; the same ready humour; the same + sympathetic interest in all the ways and works of men. But instead of + turning away from the problems of Nature as hopelessly insoluble, our + modern philosopher devoted his whole life to attacking them in the spirit + of Heraclitus and of Democritus, with results which are the substance of + which their speculations were anticipatory shadows. + </p> + <p> + The due appreciation, or even enumeration, of these results is neither + practicable nor desirable at this moment. There is a time for all + things--a time for glorying in our ever-extending conquests over the realm + of Nature, and a time for mourning over the heroes who have led us to + victory. + </p> + <p> + None have fought better, and none have been more fortunate, than Charles + Darwin. He found a great truth trodden underfoot, reviled by bigots, and + ridiculed by all the world; he lived long enough to see it, chiefly by his + own efforts, irrefragably established in science, inseparably incorporated + with the common thoughts of men, and only hated and feared by those who + would revile, but dare not. What shall a man desire more than this? Once + more the image of Socrates rises unbidden, and the noble peroration of the + "Apology" rings in our ears as if it were Charles Darwin's farewell:-- + </p> + <p> + "The hour of departure has arrived, and we go our ways--I to die and you + to live. Which is the better, God only knows." + </p> + <h2 id="c9"> + IX The Darwin Memorial + </h2> + <p> + [June 9th, 1885] + </p> + <p> + <i>Address by the President of the Royal Society, in the name of the + Memorial Committee, on handing over the statue of Darwin to H.R.H. the + Prince of Wales, as representative of the Trustees of the British Museum</i>. + </p> + <p> + YOUR ROYAL HIGHNESS,--It is now three years since the announcement of the + death of our famous countryman, Charles Darwin, gave rise to a + manifestation of public feeling, not only in these realms, but throughout + the civilised world, which, if I mistake not, is without precedent in the + modest annals of scientific biography. + </p> + <p> + The causes of this deep and wide outburst of emotion are not far to seek. + We had lost one of these rare ministers and interpreters of Nature whose + names mark epochs in the advance of natural knowledge. For, whatever be + the ultimate verdict of posterity upon this or that opinion which Mr. + Darwin has propounded; whatever adumbrations or anticipations of his + doctrines may be found in the writings of his predecessors; the broad fact + remains that, since the publication and by reason of the publication, of + "The Origin of Species" the fundamental conceptions and the aims of the + students of living Nature have been completely changed. From that work has + sprung a great renewal, a true "instauratio magna" of the zoological and + botanical sciences. + </p> + <p> + But the impulse thus given to scientific thought rapidly spread beyond the + ordinarily recognised limits of biology. Psychology, Ethics, Cosmology + were stirred to their foundations, and the "Origin of Species" proved + itself to be the fixed point which the general doctrine of evolution + needed in order to move the world. "Darwinism," in one form or another, + sometimes strangely distorted and mutilated, became an everyday topic of + men's speech, the object of an abundance both of vituperation and of + praise, more often than of serious study. + </p> + <p> + It is curious now to remember how largely, at first, the objectors + predominated; but considering the usual fate of new views, it is still + more curious to consider for how short a time the phase of vehement + opposition lasted. Before twenty years had passed, not only had the + importance of Mr. Darwin's work been fully recognised, but the world had + discerned the simple, earnest, generous character of the man, that shone + through every page of his writings. + </p> + <p> + I imagine that reflections such as these swept through the minds alike of + loving friends and of honourable antagonists when Mr. Darwin died; and + that they were at one in the desire to honour the memory of the man who, + without fear and without reproach, had successfully fought the hardest + intellectual battle of these days. + </p> + <p> + It was in satisfaction of these just and generous impulses that our great + naturalist's remains were deposited in Westminster Abbey; and that, + immediately afterwards, a public meeting, presided over by my lamented + predecessor, Mr. Spottiswoode, was held in the rooms of the Royal Society, + for the purpose of considering what further step should be taken towards + the same end. + </p> + <p> + It was resolved to invite subscriptions, with the view of erecting a + statue of Mr. Darwin in some suitable locality; and to devote any surplus + to the advancement of the biological sciences. + </p> + <p> + Contributions at once flowed in from Austria, Belgium, Brazil, Denmark, + France, Germany, Holland, Italy, Norway, Portugal, Russia, Spain, Sweden, + Switzerland, the United States, and the British Colonies, no less than + from all parts of the three kingdoms; and they came from all classes of + the community. To mention one interesting case, Sweden sent in 2296 + subscriptions "from all sorts of people," as the distinguished man of + science who transmitted them wrote, "from the bishop to the seamstress, + and in sums from five pounds to two pence." + </p> + <p> + The Executive Committee has thus been enabled to carry out the objects + proposed. A "Darwin Fund" has been created, which is to be held in trust + by the Royal Society, and is to be employed in the promotion of biological + research. + </p> + <p> + The execution of the statue was entrusted to Mr. Boehm; and I think that + those who had the good fortune to know Mr. Darwin personally will admire + the power of artistic divination which has enabled the sculptor to place + before us so very characteristic a likeness of one whom he had not seen. + </p> + <p> + It appeared to the Committee that, whether they regarded Mr. Darwin's + career or the requirements of a work of art, no site could be so + appropriate as this great hall, and they applied to the Trustees of the + British Museum for permission to erect it in its present position. + </p> + <p> + That permission was most cordially granted, and I am desired to tender the + best thanks of the Committee to the Trustees for their willingness to + accede to our wishes. + </p> + <p> + I also beg leave to offer the expression of our gratitude to your Royal + Highness for kindly consenting to represent the Trustees to-day. It only + remains for me, your Royal Highness, my Lords and Gentlemen, Trustees of + the British Museum, in the name of the Darwin Memorial Committee, to + request you to accept this statue of Charles Darwin. + </p> + <p> + We do not make this request for the mere sake of perpetuating a memory; + for so long as men occupy themselves with the pursuit of truth, the name + of Darwin runs no more risk of oblivion than does that of Copernicus, or + that of Harvey. + </p> + <p> + Nor, most assuredly, do we ask you to preserve the statue in its cynosural + position in this entrance-hall of our National Museum of Natural History + as evidence that Mr. Darwin's views have received your official sanction; + for science does not recognise such sanctions, and commits suicide when it + adopts a creed. + </p> + <p> + No; we beg you to cherish this Memorial as a symbol by which, as + generation after generation of students of Nature enter yonder door, they + shall be reminded of the ideal according to which they must shape their + lives, if they would turn to the best account the opportunities offered by + the great institution under your charge. + </p> + <h2 id="c10"> + X Obituary From the Obituary Notices of the <i>Proceedings of the Royal + Society</i>, vol. 44. + </h2> + <p> + [1888] + </p> + <p> + Charles Robert Darwin was the fifth child and second son of Robert Waring + Darwin and Susannah Wedgwood, and was born on the 12th February, 1809, at + Shrewsbury, where his father was a physician in large practice. + </p> + <p> + Mrs. Robert Darwin died when her son Charles was only eight years old, and + he hardly remembered her. A daughter of the famous Josiah Wedgwood, who + created a new branch of the potter's art, and established the great works + of Etruria, could hardly fail to transmit important mental and moral + qualities to her children; and there is a solitary record of her direct + influence in the story told by a schoolfellow, who remembers Charles + Darwin "bringing a flower to school, and saying that his mother had taught + him how, by looking at the inside of the blossom, the name of the plant + could be discovered." (I., p. 28.) [*] + </p> + <ol class="footnotes"> + <li> + The references throughout this notice are to the <i>Life and Letters</i>, + unless the contrary is expressly stated. + </li> + </ol> + <p> + The theory that men of genius derive their qualities from their mothers, + however, can hardly derive support from Charles Darwin's case, in the face + of the patent influence of his paternal forefathers. Dr. Darwin, indeed, + though a man of marked individuality of character, a quick and acute + observer, with much practical sagacity, is said not to have had a + scientific mind. But when his son adds that his father "formed a theory + for almost everything that occurred" (I., p. 20), he indicates a highly + probable source for that inability to refrain from forming an hypothesis + on every subject which he confesses to be one of the leading + characteristics of his own mind, some pages further on (I., p. 103). Dr. + R. W. Darwin, again, was the third son of Erasmus Darwin, also a physician + of great repute, who shared the intimacy of Watt and Priestley, and was + widely known as the author of "Zoonomia," and other voluminous poetical + and prose works which had a great vogue in the latter half of the + eighteenth century. The celebrity which they enjoyed was in part due to + the attractive style (at least according to the taste of that day) in + which the author's extensive, though not very profound, acquaintance with + natural phenomena was set forth; but in a still greater degree, probably, + to the boldness of the speculative views, always ingenious and sometimes + fantastic, in which he indulged. The conception of evolution set afoot by + De Maillet and others, in the early part of the century, not only found a + vigorous champion in Erasmus Darwin, but he propounded an hypothesis as to + the manner in which the species of animals and plants have acquired their + characters, which is identical in principle with that subsequently + rendered famous by Lamarck. + </p> + <p> + That Charles Darwin's chief intellectual inheritance came to him from the + paternal side, then, is hardly doubtful. But there is nothing to show that + he was, to any sensible extent, directly influenced by his grandfather's + biological work. He tells us that a perusal of the "Zoonomia" in early + life produced no effect upon him, although he greatly admired it; and + that, on reading it again, ten or fifteen years afterwards, he was much + disappointed, "the proportion of speculation being so large to the facts + given." But with his usual anxious candour he adds, "Nevertheless, it is + probable that the hearing, rather early in life, such views maintained and + praised, may have favoured my upholding them, in a different form, in my + 'Origin of Species.'" (I., p. 38.) Erasmus Darwin was in fact an + anticipator of Lamarck, and not of Charles Darwin; there is no trace in + his works of the conceptions by the addition of which his grandson + metamorphosed the theory of evolution as applied to living things and gave + it a new foundation. + </p> + <p> + Charles Darwin's childhood and youth afforded no intimation that he would + he, or do, anything out of the common run. In fact, the prognostications + of the educational authorities into whose hands he first fell were most + distinctly unfavourable; and they counted the only boy of original genius + who is known to have come under their hands as no better than a dunce. The + history of the educational experiments to which Darwin was subjected is + curious, and not without a moral for the present generation. There were + four of them, and three were failures. Yet it cannot be said that the + materials on which the pedagogic powers operated were other than good. In + his boyhood Darwin was strong, well-grown, and active, taking the keen + delight in field sports and in every description of hard physical exercise + which is natural to an English country-bred lad; and, in respect of things + of the mind, he was neither apathetic, nor idle, nor one-sided. The + "Autobiography" tells us that he "had much zeal for whatever interested" + him, and he was interested in many and very diverse topics. He could work + hard, and liked a complex subject better than an easy one. The "clear + geometrical proofs" of Euclid delighted him. His interest in practical + chemistry, carried out in an extemporised laboratory, in which he was + permitted to assist by his elder brother, kept him late at work, and + earned him the nickname of "gas" among his schoolfellows. And there could + have been no insensibility to literature in one who, as a boy, could sit + for hours reading Shakespeare, Milton, Scott, and Byron; who greatly + admired some of the Odes of Horace; and who, in later years, on board the + "Beagle," when only one book could be carried on an expedition, chose a + volume of Milton for his companion. + </p> + <p> + Industry, intellectual interests, the capacity for taking pleasure in + deductive reasoning, in observation, in experiment, no less than in the + highest works of imagination: where these qualities are present any + rational system of education should surely be able to make something of + them. Unfortunately for Darwin, the Shrewsbury Grammar School, though good + of its kind, was an institution of a type universally prevalent in this + country half a century ago, and by no means extinct at the present day. + The education given was "strictly classical," "especial attention" being + "paid to verse-making," while all other subjects, except a little ancient + geography and history, were ignored. Whether, as in some famous English + schools at that date and much later, elementary arithmetic was also left + out of sight does not appear; but the instruction in Euclid which gave + Charles Darwin so much satisfaction was certainly supplied by a private + tutor. That a boy, even in his leisure hours, should permit himself to be + interested in any but book-learning seems to have been regarded as little + better than an outrage by the head master, who thought it his duty to + administer a public rebuke to young Darwin for wasting his time on such a + contemptible subject as chemistry. English composition and literature, + modern languages, modern history, modern geography, appear to have been + considered to be as despicable as chemistry. + </p> + <p> + For seven long years Darwin got through his appointed tasks; construed + without cribs, learned by rote whatever was demanded, and concocted his + verses in approved schoolboy fashion. And the result, as it appeared to + his mature judgment, was simply negative. "The school as a means of + education to me was simply a blank." (I. p. 32.) On the other hand, the + extraneous chemical exercises, which the head master treated so + contumeliously, are gratefully spoken of as the "best part" of his + education while at school. Such is the judgment of the scholar on the + school; as might be expected, it has its counterpart in the judgment of + the school on the scholar. The collective intelligence of the staff of + Shrewsbury School could find nothing but dull mediocrity in Charles + Darwin. The mind that found satisfaction in knowledge, but very little in + mere learning; that could appreciate literature, but had no particular + aptitude for grammatical exercises; appeared to the "strictly classical" + pedagogue to be no mind at all. As a matter of fact, Darwin's school + education left him ignorant of almost all the things which it would have + been well for him to know, and untrained in all the things it would have + been useful for him to be able to do, in after life. Drawing, practice in + English composition, and instruction in the elements of the physical + sciences, would not only have been infinitely valuable to him in reference + to his future career, but would have furnished the discipline suited to + his faculties, whatever that career might be. And a knowledge of French + and German, especially the latter, would have removed from his path + obstacles which he never fully overcame. + </p> + <p> + Thus, starved and stunted on the intellectual side, it is not surprising + that Charles Darwin's energies were directed towards athletic amusements + and sport, to such an extent, that even his kind and sagacious father + could be exasperated into telling him that "he cared for nothing but + shooting, dogs, and rat-catching." (I. p. 32.) It would be unfair to + expect even the wisest of fathers to have foreseen that the shooting and + the rat-catching, as training in the ways of quick observation and in + physical endurance, would prove more valuable than the construing and + verse-making to his son, whose attempt, at a later period of his Life, to + persuade himself "that shooting was almost an intellectual employment: it + required so much skill to judge where to find most game, and to hunt the + dogs well" (I. p. 43), was by no means so sophistical as he seems to have + been ready to admit. + </p> + <p> + In 1825, Dr. Darwin came to the very just conclusion that his son Charles + would do no good by remaining at Shrewsbury School, and sent him to join + his elder brother Erasmus, who was studying medicine at Edinburgh, with + the intention that the younger son should also become a medical + practitioner. Both sons, however, were well aware that their inheritance + would relieve them from the urgency of the struggle for existence which + most professional men have to face; and they seemed to have allowed their + tastes, rather than the medical curriculum, to have guided their studies. + Erasmus Darwin was debarred by constant ill-health from seeking the public + distinction which his high intelligence and extensive knowledge would, + under ordinary circumstances, have insured. He took no great interest in + biological subjects, but his companionship must have had its influence on + his brother. Still more was exerted by friends like Coldstream and Grant, + both subsequently well-known zoologists (and the latter an enthusiastic + Lamarckian), by whom Darwin was induced to interest himself in marine + zoology. A notice of the ciliated germs of <i>Flustra</i>, communicated to + the Plinian Society in 1826, was the first fruits of Darwin's half century + of scientific work. Occasional attendance at the Wernerian Society brought + him into relation with that excellent ornithologist the elder + Macgillivray, and enabled him to see and hear Audubon. Moreover, he got + lessons in bird-stuffing from a negro, who had accompanied the eccentric + traveller Waterton in his wanderings, before settling in Edinburgh. + </p> + <p> + No doubt Darwin picked up a great deal of valuable knowledge during his + two years' residence in Scotland; but it is equally clear that next to + none of it came through the regular channels of academic education. + Indeed, the influence of the Edinburgh professoriate appears to have been + mainly negative, and in some cases deterrent; creating in his mind, not + only a very low estimate of the value of lectures, but an antipathy to the + subjects which had been the occasion of the boredom inflicted upon him by + their instrumentality. With the exception of Hope, the Professor of + Chemistry, Darwin found them all "intolerably dull." Forty years + afterwards he writes of the lectures of the Professor of Materia Medica + that they were "fearful to remember." The Professor of Anatomy made his + lectures "as dull as he was himself," and he must have been very dull to + have wrung from his victim the sharpest personal remark recorded as his. + But the climax seems to have been attained by the Professor of Geology and + Zoology, whose prælections were so "incredibly dull" that they + produced in their hearer the somewhat rash determination never "to read a + book on geology or in any way to study the science" so long as he lived. + (I. p. 41.) + </p> + <p> + There is much reason to believe that the lectures in question were + eminently qualified to produce the impression which they made; and there + can be little doubt, that Darwin's conclusion that his time was better + employed in reading than in listening to such lectures was a sound one. + But it was particularly unfortunate that the personal and professorial + dulness of the Professor of Anatomy, combined with Darwin's sensitiveness + to the disagreeable concomitants of anatomical work, drove him away from + the dissecting room. In after life, he justly recognised that this was an + "irremediable evil" in reference to the pursuits he eventually adopted; + indeed, it is marvellous that he succeeded in making up for his lack of + anatomical discipline, so far as his work on the Cirripedes shows he did. + And the neglect of anatomy had the further unfortunate result that it + excluded him from the best opportunity of bringing himself into direct + contact with the facts of nature which the University had to offer. In + those days, almost the only practical scientific work accessible to + students was anatomical, and the only laboratory at their disposal the + dissecting room. + </p> + <p> + We may now console ourselves with the reflection that the partial evil was + the general good. Darwin had already shown an aptitude for practical + medicine (I. p. 37); and his subsequent career proved that he had the + making of an excellent anatomist. Thus, though his horror of operations + would probably have shut him off from surgery, there was nothing to + prevent him (any more than the same peculiarity prevented his father) from + passing successfully through the medical curriculum and becoming, like his + father and grandfather, a successful physician, in which case "The Origin + of Species" would not have been written. Darwin has jestingly alluded to + the fact that the shape of his nose (to which Captain Fitzroy objected), + nearly prevented his embarkation in the "Beagle"; it may be that the + sensitiveness of that organ secured him for science. + </p> + <p> + At the end of two years' residence in Edinburgh it hardly needed Dr. + Darwin's sagacity to conclude that a young man, who found nothing but + dulness in professorial lucubrations, could not bring himself to endure a + dissecting room, fled from operations, and did not need a profession as a + means of livelihood, was hardly likely to distinguish himself as a student + of medicine. He therefore made a new suggestion, proposing that his son + should enter an English University and qualify for the ministry of the + Church. Charles Darwin found the proposal agreeable, none the less, + probably, that a good deal of natural history and a little shooting were + by no means held, at that time, to be incompatible with the conscientious + performance of the duties of a country clergyman. But it is characteristic + of the man, that he asked time for consideration, in order that he might + satisfy himself that he could sign the Thirty-nine Articles with a clear + conscience. However, the study of "Pearson on the Creeds" and a few other + books of divinity soon assured him that his religious opinions left + nothing to be desired on the score of orthodoxy, and he acceded to his + father's proposition. + </p> + <p> + The English University selected was Cambridge; but an unexpected obstacle + arose from the fact that, within the two years which had elapsed, since + the young man who had enjoyed seven years of the benefit of a strictly + classical education had left school, he had forgotten almost everything he + had learned there, "even to some few of the Greek letters." (I. p. 46.) + Three months with a tutor, however, brought him back to the point of + translating Homer and the Greek Testament "with moderate facility," and + Charles Darwin commenced the third educational experiment of which he was + the subject, and was entered on the books of Christ's College in October + 1827. So far as the direct results of the academic training thus received + are concerned, the English University was not more successful than the + Scottish. "During the three years which I spent at Cambridge my time was + wasted, as far as the academical studies were concerned, as completely as + at Edinburgh and as at school." (I. p. 46.) And yet, as before, there is + ample evidence that this negative result cannot be put down to any native + defect on the part of the scholar. Idle and dull young men, or even young + men who being neither idle nor dull, are incapable of caring for anything + but some hobby, do not devote themselves to the thorough study of Paley's + "Moral Philosophy," and "Evidences of Christianity"; nor are their + reminiscences of this particular portion of their studies expressed in + terms such as the following: "The logic of this book [the 'Evidences'] + and, as I may add, of his 'Natural Theology' gave me as much delight as + did Euclid." (I. p. 47.) + </p> + <p> + The collector's instinct, strong in Darwin from his childhood, as is + usually the case in great naturalists, turned itself in the direction of + Insects during his residence at Cambridge. In childhood it had been damped + by the moral scruples of a sister, as to the propriety of catching and + killing insects for the mere sake of possessing them, but now it broke out + afresh, and Darwin became an enthusiastic beetle collector. Oddly enough + he took no scientific interest in beetles, not even troubling himself to + make out their names; his delight lay in the capture of a species which + turned out to be rare or new, and still more in finding his name, as + captor, recorded in print. Evidently, this beetle-hunting hobby had little + to do with science, but was mainly a new phase of the old and undiminished + love of sport. In the intervals of beetle-catching, when shooting and + hunting were not to be had, riding across country answered the purpose. + These tastes naturally threw the young undergraduate among a set of men + who preferred hard riding: to hard reading, and wasted the midnight oil + upon other pursuits than that of academic distinction. A superficial + observer might have had some grounds to fear that Dr. Darwin's wrathful + prognosis might yet be verified. But if the eminently social tendencies of + a vigorous and genial nature sought an outlet among a set of jovial + sporting friends, there were other and no less strong proclivities which + brought him into relation with associates of a very different stamp. + </p> + <p> + Though almost without ear and with a very defective memory for music, + Darwin was so strongly and pleasurably affected by it that he became a + member of a musical society; and an equal lack of natural capacity for + drawing did not prevent him from studying good works of art with much + care. + </p> + <p> + An acquaintance with even the rudiments of physical science was no part of + the requirements for the ordinary Cambridge degree. But there were + professors both of Geology and of Botany whose lectures were accessible to + those who chose to attend them. The occupants of these chairs, in Darwin's + time, were eminent men and also admirable lecturers in their widely + different styles. The horror of geological lectures which Darwin had + acquired at Edinburgh, unfortunately prevented him from going within reach + of the fervid eloquence of Sedgwick; but he attended the botanical course, + and though he paid no serious attention to the subject, he took great + delight in the country excursions, which Henslow so well knew how to make + both pleasant and instructive. The Botanical Professor was, in fact, a man + of rare character and singularly extensive acquirements in all branches of + natural history. It was his greatest pleasure to place his stores of + knowledge at the disposal of the young men who gathered about him, and who + found in him, not merely an encyclopedic teacher but a wise counsellor, + and, in case of worthiness, a warm friend. Darwin's acquaintance with him + soon ripened into a friendship which was terminated only by Henslow's + death in 1861, when his quondam pupil gave touching expression to his + sense of what he owed to one whom he calls (in one of his letters) his + "dear old master in Natural History." (II. p. 217.) It was by Henslow's + advice that Darwin was led to break the vow he had registered against + making an acquaintance with geology; and it was through Henslow's good + offices with Sedgwick that he obtained the opportunity of accompanying the + Geological Professor on one of his excursions in Wales. He then received a + certain amount of practical instruction in Geology, the value of which he + subsequently warmly acknowledged. (I. p. 237.) In another direction, + Henslow did him an immense, though not altogether intentional service, by + recommending him to buy and study the recently published first volume of + Lyell's "Principles." As an orthodox geologist of the then dominant + catastrophic school, Henslow accompanied his recommendation with the + admonition on no account to adopt Lyell's general views. But the warning + fell on deaf ears, and it is hardly too much to say that Darwin's greatest + work is the outcome of the unflinching application to Biology of the + leading idea and the method applied in the "Principles" to geology. [*] + Finally, it was through Henslow, and at his suggestion, that Darwin was + offered the appointment to the "Beagle" as naturalist. + </p> + <ol class="footnotes"> + <li> + "After my return to England it appeared to me that by following the + example of Lyell in Geology, and by collecting all facts which bore in + any way on the variation of animals and plants under domestication and + nature, some light might perhaps be thrown on the whole subject [of the + origin of species]." (I. p. 83.) See also the dedication of the second + edition of the <i>Journal of a Naturalist</i>, + </li> + </ol> + <p> + During the latter part of Darwin's residence at Cambridge the prospect of + entering the Church, though the plan was never formally renounced, seems + to have grown very shadowy. Humboldt's "Personal Narrative," and + Herschel's "Introduction to the Study of Natural Philosophy," fell in his + way and revealed to him his real vocation. The impression made by the + former work was very strong. "My whole course of life," says Darwin in + sending a message to Humboldt, "is due to having read and re-read, as a + youth, his personal narrative." (I. p. 336.) The description of Teneriffe + inspired Darwin with such a strong desire to visit the island, that he + took some steps towards going there--inquiring about ships, and so on. + </p> + <p> + But, while this project was fermenting, Henslow, who had been asked to + recommend a naturalist for Captain Fitzroy's projected expedition, at once + thought of his pupil. In his letter of the 24th August, 1831, he says: "I + have stated that I consider you to be the best qualified person I know of + who is likely to undertake such a situation. I state this--not on the + supposition of your being a <i>finished</i> naturalist, but as amply + qualified for collecting, observing, and noting anything worthy to be + noted in Natural History.... The voyage is to last two years, and if you + take plenty of books with you, anything you please may be done." (I. p. + 193.) The state of the case could not have been better put. Assuredly the + young naturalist's theoretical and practical scientific training had gone + no further than might suffice for the outfit of an intelligent collector + and note-taker. He was fully conscious of the fact, and his ambition + hardly rose above the hope that he should bring back materials for the + scientific "lions" at home of sufficient excellence to prevent them from + turning and rending him. (I. p. 248.) + </p> + <p> + But a fourth educational experiment was to be tried. This time Nature took + him in hand herself and showed him the way by which, to borrow Henslow's + prophetic phrase, "anything he pleased might be done." + </p> + <p> + The conditions of life presented by a ship-of-war of only 242 tons + burthen, would not, <i>primâ facie</i>, appear to be so favourable + to intellectual development as those offered by the cloistered retirement + of Christ's College. Darwin had not even a cabin to himself; while, in + addition to the hindrances and interruptions incidental to sea-life, which + can be appreciated only by those who have had experience of them, + sea-sickness came on whenever the little ship was "lively"; and, + considering the circumstances of the cruise, that must have been her + normal state. Nevertheless, Darwin found on board the "Beagle" that which + neither the pedagogues of Shrewsbury, nor the professoriate of Edinburgh, + nor the tutors of Cambridge had managed to give him. "I have always felt + that I owe to the voyage the first real training or education of my mind + (I. p. 61);" and in a letter written as he was leaving England, he calls + the voyage on which he was starting, with just insight, his "second life." + (I. p. 214.) Happily for Darwin's education, the school time of the + "Beagle" lasted five years instead of two; and the countries which the + ship visited were singularly well fitted to provide him with + object-lessons, on the nature of things, of the greatest value. + </p> + <p> + While at sea, he diligently collected, studied, and made copious notes + upon the surface Fauna. But with no previous training in dissection, + hardly any power of drawing, and next to no knowledge of comparative + anatomy, his occupation with work of this kind--notwithstanding all his + zeal and industry--resulted, for the most part, in a vast accumulation of + useless manuscript. Some acquaintance with the marine <i>Crustacea</i>, + observations on <i>Planariæ</i> and on the ubiquitous <i>Sagitta</i>, + seem to have been the chief results of a great amount of labour in this + direction. + </p> + <p> + It was otherwise with the terrestrial phenomena which came under the + voyager's notice: and Geology very soon took her revenge for the scorn + which the much-bored Edinburgh student had poured upon her. Three weeks + after leaving England the ship touched land for the first time at St. + Jago, in the Cape de Verd Islands, and Darwin found his attention vividly + engaged by the volcanic phenomena and the signs of upheaval which the + island presented. His geological studies had already indicated the + direction in which a great deal might be done, beyond collecting; and it + was while sitting beneath a low lava cliff on the shore of this island, + that a sense of his real capability first dawned upon Darwin, and prompted + the ambition to write a book on the geology of the various countries + visited. (I. p. 66.) Even at this early date, Darwin must have thought + much on geological topics, for he was already convinced of the superiority + of Lyell's views to those entertained by the catastrophists [*]; and his + subsequent study of the tertiary deposits and of the terraced gravel beds + of South America was eminently fitted to strengthen that conviction. The + letters from South America contain little reference to any scientific + topic except geology; and even the theory of the formation of coral reefs + was prompted by the evidence of extensive and gradual changes of level + afforded by the geology of South America; "No other work of mine," he + says, "was begun in so deductive a spirit as this; for the whole theory + was thought out on the West Coast of South America, before I had seen a + true coral reef. I had, therefore, only to verify and extend my views by a + careful examination of living reefs." (I. p. 70.) In 1835, when starting + from Lima for the Galapagos, he recommends his friend, W. D. Fox, to take + up geology:--"There is so much larger a field for thought than in the + other branches of Natural History. I am become a zealous disciple of Mr. + Lyell's views, as made known in his admirable book. Geologising in South + America, I am tempted to carry parts to a greater extent even than he + does. Geology is a capital science to begin with, as it requires nothing + but a little reading, thinking, and hammering." (I. p. 263.) The truth of + the last statement, when it was written, is a curious mark of the + subsequent progress of geology. Even so late as 1836, Darwin speaks of + being "much more inclined for geology than the other branches of Natural + History." (I. p. 275.) + </p> + <ol class="footnotes"> + <li> + "I had brought with me the first volume of Lyell's <i>Principles of + Geology</i>, which I studied attentively; and the book was of the + highest service to me in many ways. The very first place which I + examined, namely, St. Jago, in the Cape de Verd Islands, showed me + clearly the wonderful superiority of Lyell's manner of treating Geology, + compared with that of any other author whose works I had with me or ever + afterwards read "-(I. p. 62.) + </li> + </ol> + <p> + At the end of the letter to Mr. Fox, however, a little doubt is expressed + whether zoological studies might not, after all, have been more + profitable; and an interesting passage in the "Autobiography" enables us + to understand the origin of this hesitation. + </p> + <p> + "During the voyage of the 'Beagle' I had been deeply impressed by + discovering in the Pampean formation great fossil animals covered with + armour like that on the existing armadillos; secondly, by the manner in + which closely-allied animals replace one another in proceeding southwards + over the continent; and, thirdly, by the South American character of most + of the productions of the Galapagos Archipelago, and, more especially, by + the manner in which they differ slightly on each island of the group; some + of the islands appearing to be very ancient in a geological sense. + </p> + <p> + "It was evident that such facts as these, as well as many others, could + only be explained on the supposition that species gradually become + modified; and the subject haunted me. But it was equally evident that + neither the action of the surrounding conditions, nor the will of the + organisms (especially in the case of plants) could account for the + innumerable cases in which organisms of every kind are beautifully adapted + to their habits of life; for instance, a woodpecker or a tree-frog to + climb trees, or a seed for dispersal by hooks or plumes. I had always been + much struck by such adaptations, and until these could be explained it + seemed to me almost useless to endeavour to prove by indirect evidence + that species have been modified." (I. p. 82.) + </p> + <p> + The facts to which reference is here made were, without doubt, eminently + fitted to attract the attention of a philosophical thinker; but, until the + relations of the existing with the extinct species and of the species of + the different geographical areas with one another, were determined with + some exactness, they afforded but an unsafe foundation for speculation. It + was not possible that this determination should have been effected before + the return of the "Beagle" to England; and thus the date which Darwin + (writing in 1837) assigns to the dawn of the new light which was rising in + his mind becomes intelligible. [*] + </p> + <ol class="footnotes"> + <li> + I am indebted to Mr. F. Darwin for the knowledge of a letter addressed + by his father to Dr. Otto Zacharias in 1877 which contains the following + paragraph, confirmatory of the view expressed above: "When I was on + board the <i>Beagle</i>, I believed in the permanence of species, but, + as far as I can remember, vague doubts occasionally flitted across my + mind. On my return home in the autumn of 1836, I immediately began to + prepare my journal for publication, and then saw how many facts + indicated the common descent of species, so that in July, 1837, I opened + a note-book to record any facts which might bear on the question. But I + did not become convinced that species were mutable until, I think, two + or three years had elapsed." + </li> + </ol> + <p> + "In July opened first note-book on Transmutation of Species. Had been + greatly struck from about the month of previous March on character of + South American fossils and species on Galapagos Archipelago. These facts + (especially latter) origin of all my views." (I. p. 276.) + </p> + <p> + From March, 1837, then, Darwin, not without many misgivings and + fluctuations of opinion, inclined towards transmutation as a provisional + hypothesis. Three months afterwards he is hard at work collecting facts + for the purpose of testing the hypothesis; and an almost apologetic + passage in a letter to Lyell shows that, already, the attractions of + biology are beginning to predominate over those of geology. + </p> + <p> + "I have lately been sadly tempted to be idle--[*] that is, as far as pure + Geology is concerned--by the delightful number of new views which have + been coming in thickly and steadily--on the classification and affinities + and instincts of animals--bearing on the question of species. Note-book + after note-book has been filled with facts which begin to group themselves + <i>clearly</i> under sub-laws." (I. p. 298.) + </p> + <ol class="footnotes"> + <li> + Darwin generally uses the word "idle" in a peculiar sense. He means by + it working hard at something he likes when he ought to be occupied with + a less attractive subject. Though it sounds paradoxical, there is a good + deal to be said in favour of this view of pleasant work. + </li> + </ol> + <p> + The problem which was to be Darwin's chief subject of occupation for the + rest of his life thus presented itself, at first, mainly under its + distributional aspect. Why do species present certain relations in space + and in time? Why are the animals and plants of the Galapagos Archipelago + so like those of South America and yet different from them? Why are those + of the several islets more or less different from one another? Why are the + animals of the latest geological epoch in South America similar in <i>facies</i> + to those which exist in the same region at the present day, and yet + specifically or generically different? + </p> + <p> + The reply to these questions, which was almost universally received fifty + years ago, was that animals and plants were created such as they are; and + that their present distribution, at any rate so far as terrestrial + organisms are concerned, has been effected by the migration of their + ancestors from the region in which the ark stranded after the subsidence + of the deluge. It is true that the geologists had drawn attention to a + good many tolerably serious difficulties in the way of the diluvial part + of this hypothesis, no less than to the supposition that the work of + creation had occupied only a brief space of time. But even those, such as + Lyell, who most strenuously argued in favour of the sufficiency of natural + causes for the production of the phenomena of the inorganic world, held + stoutly by the hypothesis of creation in the case of those of the world of + life. + </p> + <p> + For persons who were unable to feel satisfied with the fashionable + doctrine, there remained only two alternatives--the hypothesis of + spontaneous generation, and that of descent with modification. The former + was simply the creative hypothesis with the creator left out; the latter + had already been propounded by De Maillet and Erasmus Darwin, among + others; and, later, systematically expounded by Lamarck. But in the eyes + of the naturalist of the "Beagle" (and, probably, in those of most sober + thinkers), the advocates of transmutation had done the doctrine they + expounded more harm than good. + </p> + <p> + Darwin's opinion of the scientific value of the "Zoonomia" has already + been mentioned. His verdict on Lamarck is given in the following passage + of a letter to Lyell (March, 1863):-- + </p> + <p> + "Lastly, you refer repeatedly to my view as a modification of Lamarck's + doctrine of development and progression. If this is your deliberate + opinion there is nothing to be said, but it does not seem so to me. Plato, + Buffon, my grandfather, before Lamarck and others, propounded the <i>obvious</i> + view that if species were not created separately they must have descended + from other species, and I can see nothing else in common between the + "Origin" and Lamarck. I believe this way of putting the case is very + injurious to its acceptance, as it implies necessary progression, and + closely connects Wallace's and my views with what I consider, after two + deliberate readings, as a wretched book, and one from which (I well + remember to my surprise) I gained nothing." + </p> + <p> + "But," adds Darwin with a little touch of banter, "I know you rank it + higher, which is curious, as it did not in the least shake your belief." + (III. p. 14; see also p. 16, "to me it was an absolutely useless book.") + </p> + <p> + Unable to find any satisfactory theory of the process of descent with + modification in the works of his predecessors, Darwin proceeded to lay the + foundations of his own views independently; and he naturally turned, in + the first place, to the only certainly known examples of descent with + modification, namely, those which are presented by domestic animals and + cultivated plants. He devoted himself to the study of these cases with a + thoroughness to which none of his predecessors even remotely approximated; + and he very soon had his reward in the discovery "that selection was the + keystone of man's success in making useful races of animals and plants." + (I. p. 83.) + </p> + <p> + This was the first step in Darwin's progress, though its immediate result + was to bring him face to face with a great difficulty. "But how selection + could be applied to organisms living in a state of nature remained for + some time a mystery to me." (I. p. 83.) + </p> + <p> + The key to this mystery was furnished by the accidental perusal of the + famous essay of Malthus "On Population" in the autumn of 1838. The + necessary result of unrestricted multiplication is competition for the + means of existence. The success of one competitor involves the failure of + the rest, that is, their extinction; and this "selection" is dependent on + the better adaptation of the successful competitor to the conditions of + the competition. Variation occurs under natural, no less than under + artificial, conditions. Unrestricted multiplication implies the + competition of varieties and the selection of those which are relatively + best adapted to the conditions. + </p> + <p> + Neither Erasmus Darwin, nor Lamarck, had any inkling of the possibility of + this process of "natural selection"; and though it had been foreshadowed + by Wells in 1813, and more fully stated by Matthew in 1831, the + speculations of the latter writer remained unknown to naturalists until + after the publication of the "Origin of Species." + </p> + <p> + Darwin found in the doctrine of the selection of favourable variations by + natural causes, which thus presented itself to his mind, not merely a + probable theory of the origin of the diverse species of living forms, but + that explanation of the phenomena of adaptation, which previous + speculations had utterly failed to give. The process of natural selection + is, in fact, dependent on adaptation--it is all one, whether one says that + the competitor which survives is the "fittest" or the "best adapted." And + it was a perfectly fair deduction that even the most complicated + adaptations might result from the summation of a long series of simple + favourable variations. + </p> + <p> + Darwin notes as a serious defect in the first sketch of his theory that he + had omitted to consider one very important problem, the solution of which + did not occur to him till some time afterwards. "This problem is the + tendency in organic beings descended from the same stock to diverge in + character as they become modified.... The solution, as I believe, is that + the modified offspring of all dominant and increasing forms tend to become + adapted to many and highly diversified places in the economy of nature." + (I. p. 84.) + </p> + <p> + It is curious that so much importance should be attached to this + supplementary idea. It seems obvious that the theory of the origin of + species by natural selection necessarily involves the divergence of the + forms selected. An individual which varies, <i>ipso facto</i> diverges + from the type of its species; and its progeny, in which the variation + becomes intensified by selection, must diverge still more, not only from + the parent stock, but from any other race of that stock starting from, a + variation of a different character. The selective process could not take + place unless the selected variety was either better adapted to the + conditions than the original stock, or adapted to other conditions than + the original stock. In the first case, the original stock would be sooner + or later extirpated; in the second, the type, as represented by the + original stock and the variety, would occupy more diversified stations + than it did before. + </p> + <p> + The theory, essentially such as it was published fourteen years later, was + written out in 1844, and Darwin was so fully convinced of the importance + of his work, as it then stood, that he made special arrangements for its + publication in case of his death. But it is a singular example of reticent + fortitude, that, although for the next fourteen years the subject never + left his mind, and during the latter half of that period he was constantly + engaged in amassing facts bearing upon it from wide reading, a colossal + correspondence, and a long series of experiments, only two or three + friends were cognisant of his views. To the outside world he seemed to + have his hands quite sufficiently full of other matters. In 1844, he + published his observations on the volcanic islands visited during the + voyage of the "Beagle." In 1845, a largely remodelled edition of his + "Journal" made its appearance, and immediately won, as it has ever since + held, the favour of both the scientific and the unscientific public. In + 1846, the "Geological Observations in South America" came out, and this + book was no sooner finished than Darwin set to work upon the Cirripedes. + He was led to undertake this long and heavy task, partly by his desire to + make out the relations of a very anomalous form which he had discovered on + the coast of Chili; and partly by a sense of "presumption in accumulating + facts and speculating on the subject of variation without having worked + out my due share of species." (II. p. 31.) The eight or nine years of + labour, which resulted in a monograph of first-rate importance in + systematic zoology (to say nothing of such novel points as the discovery + of complemental males), left Darwin no room to reproach himself on this + score, and few will share his "doubt whether the work was worth the + consumption of so much time." (I. p. 82.) + </p> + <p> + In science no man can safely speculate about the nature and relation of + things with which he is unacquainted at first hand, and the acquirement of + an intimate and practical knowledge of the process of species-making and + of all the uncertainties which underlie the boundaries between species and + varieties, drawn by even the most careful and conscientious systematists + [*] were of no less importance to the author of the "Origin of Species" + than was the bearing of the Cirripede work upon "the principles of a + natural classification." (I. p. 81.) No one, as Darwin justly observes, + has a "right to examine the question of species who has not minutely + described many." (II. p. 39.) + </p> + <ol class="footnotes"> + <li> + "After describing a set of forms as distinct species, tearing up my MS., + and making them one species, tearing that up and making them separate, + and then making them one again (which has happened to me), I have + gnashed my teeth, cursed species, and asked what sin I had committed to + be so punished." (II. p. 40.) Is there any naturalist provided with a + logical sense and a large suite of specimens, who has not undergone + pangs of the sort described in this vigorous paragraph, which might, + with advantage, be printed on the title-page of every systematic + monograph as a warning to the uninitiated? + </li> + </ol> + <p> + In September, 1854, the Cirripede work was finished, "ten thousand + barnacles" had been sent "out of the house, all over the world," and + Darwin had the satisfaction of being free to turn again to his "old notes + on species." In 1855, he began to breed pigeons, and to make observations + on the effects of use and disuse, experiments on seeds, and so on, while + resuming his industrious collection of facts, with a view "to see how far + they favour or are opposed to the notion that wild species are mutable or + immutable. I mean with my utmost power to give all arguments and facts on + both sides. I have a <i>number</i> of people helping me every way, and + giving me most valuable assistance; but I often doubt whether the subject + will not quite overpower me." (II. p. 49.) + </p> + <p> + Early in 1856, on Lyell's advice, Darwin began to write out his views on + the origin of species on a scale three or four times as extensive as that + of the work published in 1859. In July of the same year he gave a brief + sketch of his theory in a letter to Asa Gray; and, in the year 1857, his + letters to his correspondents show him to be busily engaged on what he + calls his "big book." (II. pp. 85, 94.) In May, 1857, Darwin writes to + Wallace: "I am now preparing my work [on the question how and in what way + do species and varieties differ from each other] for publication, but I + find the subject so very large, that, though I have written many chapters, + I do not suppose I shall go to press for two years." (II. p. 95.) In + December, 1857, he writes, in the course of a long letter to the same + correspondent, "I am extremely glad to hear that you are attending to + distribution in accordance with theoretical ideas. I am a firm believer + that without speculation there is no good and original observation." (II. + p. 108.) [*] In June, 1858, he received from Mr. Wallace, then in the + Malay Archipelago, an "Essay on the tendency of varieties to depart + indefinitely from the original type," of which Darwin says, "If Wallace + had my MS. sketch written out in 1842 he could not have made a better + short abstract! Even his terms stand now as heads of my chapters. Please + return me the MS., which he does not say he wishes me to publish, but I + shall, of course, at once write and offer to send it to any journal. So + all my originality, whatever it may amount to, will be smashed, though my + book, if ever it will have any value, will not be deteriorated; as all the + labour consists in the application of the theory." (II. p. 116.) + </p> + <ol class="footnotes"> + <li> + The last remark contains a pregnant truth, but it must be confessed it + hardly squares with the declaration in the <i>Autobiography</i>, (I. p. + 83), that he worked on "true Baconian principles." + </li> + </ol> + <p> + Thus, Darwin's first impulse was to publish Wallace's essay without note + or comment of his own. But, on consultation with Lyell and Hooker, the + latter of whom had read the sketch of 1844, they suggested, as an + undoubtedly more equitable course, that extracts from the MS. of 1844 and + from the letter to Dr. Asa Gray should be communicated to the Linnean + Society along with Wallace's essay. The joint communication was read on + July 1, 1858, and published under the title "On the Tendency of Species to + form Varieties; and on the Perpetuation of Varieties and Species by + Natural Means of Selection." This was followed, on Darwin's part, by the + composition of a summary account of the conclusions to which his twenty + years' work on the species question had led him. It occupied him for + thirteen months, and appeared in November, 1859, under the title "On the + Origin of Species by means of Natural Selection or the Preservation of + Favoured Races in the Struggle of Life." + </p> + <p> + It is doubtful if any single book, except the "Principia," ever worked so + great and so rapid a revolution in science, or made so deep an impression + on the general mind. It aroused a tempest of opposition and met with + equally vehement support, and it must be added that no book has been more + widely and persistently misunderstood by both friends and foes. In 1861, + Darwin remarks to a correspondent, "You understand my book perfectly, and + that I find a very rare event with my critics." (I. p. 313.) The immense + popularity which the "Origin" at once acquired was no doubt largely due to + its many points of contact with philosophical and theological questions in + which every intelligent man feels a profound interest; but a good deal + must be assigned to a somewhat delusive simplicity of style, which tends + to disguise the complexity and difficulty of the subject, and much to the + wealth of information on all sorts of curious problems of natural history, + which is made accessible to the most unlearned reader. But long occupation + with the work has led the present writer to believe that the "Origin of + Species" is one of the hardest of books to master; [*] and he is justified + in this conviction by observing that although the "Origin" has been close + on thirty years before the world, the strangest misconceptions of the + essential nature of the theory therein advocated are still put forth by + serious writers. + </p> + <ol class="footnotes"> + <li> + He is comforted to find that probably the best qualified judge among all + the readers of the <i>Origin</i> in 1859 was of the same opinion. Sir J. + Hooker writes, "It is the very hardest book to read, to full profit, + that I ever tried." (II. p. 242.) + </li> + </ol> + <p> + Although, then, the present occasion is not suitable for any detailed + criticism of the theory, or of the objections which have been brought + against it, it may not be out of place to endeavour to separate the + substance of the theory from its accidents; and to show that a variety not + only of hostile comments, but of friendly would-be improvements lose their + <i>raison d'être</i> to the careful student. Observation proves the + existence among all living beings of phenomena of three kinds, denoted by + the terms heredity, variation, and multiplication. Progeny tend to + resemble their parents; nevertheless all their organs and functions are + susceptible of departing more or less from the average parental character; + and their number is in excess of that of their parents. Severe competition + for the means of living, or the struggle for existence, is a necessary + consequence of unlimited multiplication; while selection, or the + preservation of favourable variations and the extinction of others, is a + necessary consequence of severe competition. "Favourable variations" are + those which are better adapted to surrounding conditions. It follows, + therefore, that every variety which is selected into a species is so + favoured and preserved in consequence of being, in some one or more + respects, better adapted to its surroundings than its rivals. In other + words, every species which exists, exists in virtue of adaptation, and + whatever accounts for that adaptation accounts for the existence of the + species. + </p> + <p> + To say that Darwin has put forward a theory of the adaptation of species, + but not of their origin, is therefore to misunderstand the first + principles of the theory. For, as has been pointed out, it is a necessary + consequence of the theory of selection that every species must have some + one or more structural or functional peculiarities, in virtue of the + advantage conferred by which, it has fought through the crowd of its + competitors and achieved a certain duration. In this sense, it is true + that every species has been "originated" by selection. + </p> + <p> + There is another sense, however, in which it is equally true that + selection originates nothing. "Unless profitable variations ... occur + natural selection can do nothing" ("Origin," Ed. I. p. 82). "Nothing can + be effected unless favourable variations occur" (<i>ibid</i>., p. 108). + "What applies to one animal will apply throughout time to all + animals--that is, if they vary--for otherwise natural selection can do + nothing. So it will be with plants" (<i>ibid</i>., p. 113). Strictly + speaking, therefore, the origin of species in general lies in variation; + while the origin of any particular species lies, firstly, in the + occurrence, and secondly, in the selection and preservation of a + particular variation. Clearness on this head will relieve one from the + necessity of attending to the fallacious assertion that natural selection + is a <i>deus ex machinâ</i>, or occult agency. + </p> + <p> + Those, again, who confuse the operation of the natural causes which bring + about variation and selection with what they are pleased to call "chance" + can hardly have read the opening paragraph of the fifth chapter of the + "Origin" (Ed. I, p. 131): "I have sometimes spoken as if the variations + ... had been due to chance. This is of course a wholly incorrect + expression, but it seems to acknowledge plainly our ignorance of the cause + of each particular variation." + </p> + <p> + Another point of great importance to the right comprehension of the + theory, is, that while every species must needs have some adaptive + advantageous characters to which it owes its preservation by selection, it + may possess any number of others which are neither advantageous nor + disadvantageous, but indifferent, or even slightly disadvantageous. (<i>Ibid</i>., + p. 81.) For variations take place, not merely in one organ or function at + a time, but in many; and thus an advantageous variation, which gives rise + to the selection of a new race or species, may be accompanied by others + which are indifferent, but which are just as strongly hereditary as the + advantageous variations. The advantageous structure is but one product of + a modified general constitution which may manifest itself by several other + products; and the selective process carries the general constitution along + with the advantageous special peculiarity. A given species of plant may + owe its existence to the selective adaptation of its flowers to insect + fertilisers; but the character of its leaves may be the result of + variations of an indifferent character. It is the origin of variations of + this kind to which Darwin refers in his frequent reference to what he + calls "laws of correlation of growth" or "correlated variation." + </p> + <p> + These considerations lead us further to see the inappropriateness of the + objections raised to Darwin's theory on the ground that natural selection + does not account for the first commencements of useful organs. But it does + not pretend to do so. The source of such commencements is necessarily to + be sought in different variations, which remain unaffected by selection + until they have taken such a form as to become utilisable in the struggle + for existence. + </p> + <p> + It is not essential to Darwin's theory that anything more should be + assumed than the facts of heredity, variation, and unlimited + multiplication; and the validity of the deductive reasoning as to the + effect of the last (that is, of the struggle for existence which it + involves) upon the varieties resulting from the operation of the former. + Nor is it essential that one should take up any particular position in + regard to the mode of variation, whether, for example, it takes place <i>per + saltum</i> or gradually; whether it is definite in character or + indefinite. Still less are those who accept the theory bound to any + particular views as to the causes of heredity or of variation. + </p> + <p> + That Darwin held strong opinions on some or all of these points may be + quite true; but, so far as the theory is concerned, they must be regarded + as <i>obiter dicta</i>. With respect to the causes of variation, Darwin's + opinions are, from first to last, put forward altogether tentatively. In + the first edition of the "Origin," he attributes the strongest influence + to changes in the conditions of life of parental organisms, which he + appears to think act on the germ through the intermediation of the sexual + organs. He points out, over and over again, that habit, use, disuse, and + the direct influence of conditions have some effect, but he does not think + it great, and he draws attention to the difficulty of distinguishing + between effects of these agencies and those of selection. There is, + however, one class of variations which he withdraws from the direct + influence of selection, namely, the variations in the fertility of the + sexual union of more or less closely allied forms. He regards less + fertility, or more or less complete sterility, as "incidental to other + acquired differences." (<i>Ibid</i>., p. 245.) + </p> + <p> + Considering the difficulties which surround the question of the causes of + variation, it is not to be wondered at, that Darwin should have inclined, + sometimes, rather more to one and, sometimes, rather more to another of + the possible alternatives. There is little difference between the last + edition of the "Origin" (1872) and the first on this head. In 1876, + however, he writes to Moritz Wagner, "In my opinion, the greatest error + which I have committed has been not allowing sufficient weight to the + direct action of the environments, i.e., food, climate, &c., + independently of natural selection. ...When I wrote the 'Origin,' and for + some years afterwards, I could find little good evidence of the direct + action of the environment; now there is a large body of evidence, and your + case of the Saturnia is one of the most remarkable of which I have heard." + (III, p. 159.) But there is really nothing to prevent the most tenacious + adherent to the theory of natural selection from taking any view he + pleases as to the importance of the direct influence of conditions and the + hereditary transmissibility of the modifications which they produce. In + fact, there is a good deal to be said for the view that the so-called + direct influence of conditions is itself a case of selection. Whether the + hypothesis of Pangenesis be accepted or rejected, it can hardly be doubted + that the struggle for existence goes on not merely between distinct + organisms, but between the physiological units of which each organism is + composed, and that changes in external conditions favour some and hinder + others. + </p> + <p> + After a short stay in Cambridge, Darwin resided in London for the first + five years which followed his return to England; and for three years, he + held the post of Secretary to the Geological Society, though he shared to + the full his friend Lyell's objection to entanglement in such engagements. + In fact, he used to say in later life, more than half in earnest, that he + gave up hoping for work from men who accepted official duties and, + especially, Government appointments. Happily for him, he was exempted from + the necessity of making any sacrifice of this kind, but an even heavier + burden was laid upon him. During the earlier half of his voyage Darwin + retained the vigorous health of his boyhood, and indeed proved himself to + be exceptionally capable of enduring fatigue and privation. An anomalous + but severe disorder, which laid him up for several weeks at Valparaiso in + 1834, however, seems to have left its mark on his constitution; and, in + the later years of his London life,attacks of illness, usually accompanied + by severe vomiting and great prostration of strength, became frequent. As + he grew older, a considerable part of every day, even at his best times, + was spent in misery; while, not unfrequently, months of suffering rendered + work of any kind impossible. Even Darwin's remarkable tenacity of purpose + and methodical utilisation of every particle of available energy could not + have enabled him to achieve a fraction of the vast amount of labour he got + through, in the course of the following forty years, had not the wisest + and the most loving care unceasingly surrounded him from the time of his + marriage in 1839. As early as 1842, the failure of health was so marked + that removal from London became imperatively necessary; and Darwin + purchased a house and grounds at Down, a solitary hamlet in Kent, which + was his home for the rest of his life. Under the strictly regulated + conditions of a valetudinarian existence, the intellectual activity of the + invalid might have put to shame most healthy men; and, so long as he could + hold his head up, there was no limit to the genial kindness of thought and + action for all about him. Those friends who were privileged to share the + intimate life of the household at Down have an abiding memory of the + cheerful restfulness which pervaded and characterised it. + </p> + <p> + After mentioning his settlement at Down, Darwin writes in his + Autobiography:-- + </p> + <p> + "My chief enjoyment and sole employment throughout life has been + scientific work; and the excitement from such work makes me, for the time, + forget, or drives quite away, my daily discomfort. I have, therefore, + nothing to record during the rest of my life, except the publication of my + several books." (I, p. 79.) + </p> + <p> + Of such works published subsequently to 1859, several are monographic + discussions of topics briefly dealt with in the "Origin," which, it must + always be recollected, was considered by the author to be merely an + abstract of an <i>opus majus</i>. + </p> + <p> + The earliest of the books which may be placed in this category, "On the + Various Contrivances by which Orchids are Fertilised by Insects," was + published in 1862, and whether we regard its theoretical significance, the + excellence of the observations and the ingenuity of the reasonings which + it records, or the prodigious mass of subsequent investigation of which it + has been the parent, it has no superior in point of importance. The + conviction that no theory of the origin of species could be satisfactory + which failed to offer an explanation of the way in which mechanisms + involving adaptations of structure and function to the performance of + certain operations are brought about, was, from the first, dominant in + Darwin's mind. As has been seen, he rejected Lamarck's views because of + their obvious incapacity to furnish such an explanation in the case of the + great majority of animal mechanisms, and in that of all those presented by + the vegetable world. + </p> + <p> + So far back as 1793, the wonderful work of Sprengel had established, + beyond any reasonable doubt, the fact that, in a large number of cases, a + flower is a piece of mechanism the object of which is to convert insect + visitors into agents of fertilisation. Sprengel's observations had been + most undeservedly neglected and well-nigh forgotten; but Robert Brown + having directed Darwin's attention to them in 1841, he was attracted + towards the subject, and verified many of Sprengel's statements. (III, p. + 258.) It may be doubted whether there was a living botanical specialist, + except perhaps Brown, who had done as much. If, however, adaptations of + this kind were to be explained by natural selection, it was necessary to + show that the plants which were provided with mechanisms for ensuring the + aid of insects as fertilisers, were by so much the better fitted to + compete with their rivals. This Sprengel had not done. Darwin had been + attending to cross fertilisation in plants so far back as 1839, from + having arrived, in the course of his speculations on the origin of + species, at the conviction "that crossing played an important part in + keeping specific forms constant" (I, p. 90). The further development of + his views on the importance of cross fertilisation appears to have taken + place between this time and 1857, when he published his first papers on + the fertilisation of flowers in the "Gardener's Chronicle." If the + conclusion at which he ultimately arrived, that cross fertilisation is + favourable to the fertility of the parent and to the vigour of the + offspring, is correct, then it follows that all those mechanisms which + hinder self-fertilisation and favour crossing must be advantageous in the + struggle for existence; and, the more perfect the action of the mechanism, + the greater the advantage. Thus the way lay open for the operation of + natural selection in gradually perfecting the flower as a + fertilisation-trap. Analogous reasoning applies to the fertilising insect. + The better its structure is adapted to that of the trap, the more will it + be able to profit by the bait, whether of honey or of pollen, to the + exclusion of its competitors. Thus, by a sort of action and reaction, a + two-fold series of adaptive modifications will be brought about. + </p> + <p> + In 1865, the important bearing of this subject on his theory led Darwin to + commence a great series of laborious and difficult experiments on the + fertilisation of plants, which occupied him for eleven years, and + furnished him with the unexpectedly strong evidence in favour of the + influence of crossing which he published in 1876, under the title of "The + Effects of Cross and Self Fertilisation in the Vegetable Kingdom." + Incidentally, as it were, to this heavy piece of work, he made the + remarkable series of observations on the different arrangements by which + crossing is favoured and, in many cases, necessitated, which appeared in + the work on "The Different Forms of Flowers in Plants of the same Species" + in 1877. + </p> + <p> + In the course of the twenty years during which Darwin was thus occupied in + opening up new regions of investigation to the botanist and showing the + profound physiological significance of the apparently meaningless + diversities of floral structure, his attention was keenly alive to any + other interesting phenomena of plant life which came in his way. In his + correspondence, he not unfrequently laughs at himself for his ignorance of + systematic botany; and his acquaintance with vegetable anatomy and + physiology was of the slenderest. Nevertheless, if any of the less common + features of plant life came under his notice, that imperious necessity of + seeking for causes which nature had laid upon him, impelled, and indeed + compelled, him to inquire the how and the why of the fact, and its bearing + on his general views. And as, happily, the atavic tendency to frame + hypotheses was accompanied by an equally strong need to test them by + well-devised experiments, and to acquire all possible information before + publishing his results, the effect was that he touched no topic without + elucidating it. + </p> + <p> + Thus the investigation of the operations of insectivorous plants, embodied + in the work on that topic published in 1875, was started fifteen years + before, by a passing observation made during one of Darwin's rare + holidays. + </p> + <p> + "In the summer of 1860, I was idling and resting near Hartfield, where two + species of Drosera abound; and I noticed that numerous insects had been + entrapped by the leaves. I carried home some plants, and on giving them + some insects saw the movements of the tentacles, and this made me think it + possible that the insects were caught for some special purpose. + Fortunately, a crucial test occurred to me, that of placing a large number + of leaves in various nitrogenous and non-nitrogenous fluids of equal + density; and as soon as I found that the former alone excited energetic + movements, it was obvious that here was a fine new field for + investigation." (I, p. 95.) + </p> + <p> + The researches thus initiated led to the proof that plants are capable of + secreting a digestive fluid like that of animals, and of profiting by the + result of digestion; whereby the peculiar apparatuses of the insectivorous + plants were brought within the scope of natural selection. Moreover, these + inquiries widely enlarged our knowledge of the manner in which stimuli are + transmitted in plants, and opened up a prospect of drawing closer the + analogies between the motor processes of plants and those of animals. + </p> + <p> + So with respect to the books on "Climbing Plants" (1875), and on the + "Power of Movement in Plants" (1880), Darwin says;-- + </p> + <p> + "I was led to take up this subject by reading a short paper by Asa Gray, + published in 1858. He sent me some seeds, and on raising some plants I was + so much fascinated and perplexed by the revolving movements of the + tendrils and stems, which movements are really very simple, though + appearing at first sight very complex, that I procured various other kinds + of climbing plants and studied the whole subject.... Some of the + adaptations displayed by climbing plants are as beautiful as those of + orchids for ensuring cross-fertilisation." (I, p. 93.) + </p> + <p> + In the midst of all this amount of work, remarkable alike for its variety + and its importance, among plants, the animal kingdom was by no means + neglected. A large moiety of "The Variation of Animals and Plants under + Domestication" (1868), which contains the <i>pièces justificatives</i> + of the first chapter of the "Origin," is devoted to domestic animals, and + the hypothesis of "pangenesis" propounded in the second volume applies to + the whole living world. In the "Origin" Darwin throws out some suggestions + as to the causes of variation, but he takes heredity, as it is manifested + by individual organisms, for granted, as an ultimate fact; pangenesis is + an attempt to account for the phenomena of heredity in the organism, on + the assumption that the physiological units of which the organism is + composed give off gemmules, which, in virtue of heredity, tend to + reproduce the unit from which they are derived. + </p> + <p> + That Darwin had the application of his theory to the origin of the human + species clearly in his mind in 1859, is obvious from a passage in the + first edition of "The Origin of Species." (Ed. I, p. 488.) "In the distant + future I see open fields for far more important researches. Psychology + will be based on a new foundation, that of the necessary acquirement of + each mental power and capacity by gradation. Light will be thrown on the + origin of man and his history." It is one of the curiosities of scientific + literature, that, in the face of this plain declaration, its author should + have been charged with concealing his opinions on the subject of the + origin of man. But he reserved the full statement of his views until 1871, + when the "Descent of Man" was published. The "Expression of the Emotions" + (originally intended to form only a chapter in the "Descent of Man") grew + into a separate volume, which appeared in 1872. Although always taking a + keen interest in geology, Darwin naturally found no time disposable for + geological work, even had his health permitted it, after he became + seriously engaged with the great problem of species. But the last of his + labours is, in some sense, a return to his earliest, inasmuch as it is an + expansion of a short paper read before the Geological Society more than + forty years before, and, as he says, "revived old geological thoughts" (I, + p. 98). In fact, "The Formation of Vegetable Mould through the Action of + Worms," affords as striking an example of the great results produced by + the long-continued operation of small causes as even the author of the + "Principles of Geology" could have desired. + </p> + <p> + In the early months of 1882 Darwin's health underwent a change for the + worse; attacks of giddiness and fainting supervened, and on the 19th of + April he died. On the 24th, his remains were interred in Westminster + Abbey, in accordance with the general feeling that such a man as he should + not go to the grave without some public recognition of the greatness of + his work. + </p> + <p> + Mr. Darwin became a Fellow of the Royal Society in 1839; one of the Royal + Medals was awarded to him in 1853, and he received the Copley Medal in + 1864. The "Life and Letters," edited with admirable skill and judgment by + Mr. Francis Darwin, gives a full and singularly vivid presentment of his + father's personal character, of his mode of work, and of the events of his + life. In the present brief obituary notice, the writer has attempted + nothing more than to select and put together those facts which enable us + to trace the intellectual evolution of one of the greatest of the many + great men of science whose names adorn the long roll of the Fellows of the + Royal Society. + </p> + <h2 id="c11"> + XI On Our Knowledge Of The Causes Of The Phenomena Of Organic Nature + </h2> + <p> + [<i>Six Lectures to Working Men</i>.--1863.] + </p> + <h3> + I. The Present Condition Of Organic Nature + </h3> + <p> + When it was my duty to consider what subject I would select for the six + lectures which I shall now have the pleasure of delivering to you, it + occurred to me that I could not do better than endeavour to put before you + in a true light, or in what I might perhaps with more modesty call, that + which I conceive myself to be the true light, the position of a book which + has been more praised and more abused, perhaps, than any book which has + appeared for some years;--I mean Mr. Darwin's work on the "Origin of + Species." That work, I doubt not, many of you have read; for I know the + inquiring spirit which is rife among you. At any rate, all of you will + have heard of it,--some by one kind of report and some by another kind of + report; the attention of all and the curiosity of all have been probably + more or less excited on the subject of that work. All I can do, and all I + shall attempt to do, is to put before you that kind of judgment which has + been formed by a man, who, of course, is liable to judge erroneously; but, + at any rate, of one whose business and profession it is to form judgments + upon questions of this nature. + </p> + <p> + And here, as it will always happen when dealing with an extensive subject, + the greater part of my course--if, indeed, so small a number of lectures + can be properly called a course--must be devoted to preliminary matters, + or rather to a statement of those facts and of those principles which the + work itself dwells upon, and brings more or less directly before us. I + have no right to suppose that all or any of you are naturalists; and, even + if you were, the misconceptions and misunderstandings prevalent even among + naturalists, on these matters, would make it desirable that I should take + the course I now propose to take,--that I should start from the + beginning,--that I should endeavour to point out what is the existing + state of the organic world--that I should point out its past + condition,--that I should state what is the precise nature of the + undertaking which Mr. Darwin has taken in hand; that I should endeavour to + show you what are the only methods by which that undertaking can be + brought to an issue, and to point out to you how far the author of the + work in question has satisfied those conditions, how far he has not + satisfied them, how far they are satisfiable by man, and how far they are + not satisfiable by man. + </p> + <p> + To-night, in taking up the first part of the question, I shall endeavour + to put before you a sort of broad notion of our knowledge of the condition + of the living world. There are many ways of doing this. I might deal with + it pictorially and graphically. Following the example of Humboldt in his + "Aspects of Nature," I might endeavour to point out the infinite variety + of organic life in every mode of its existence, with reference to the + variations of climate and the like; and such an attempt would be fraught + with interest to us all; but considering the subject before us, such a + course would not be that best calculated to assist us. In an argument of + this kind we must go further and dig deeper into the matter; we must + endeavour to look into the foundations of living Nature, if I may so say, + and discover the principles involved in some of her most secret + operations. I propose, therefore, in the first place, to take some + ordinary animal with which you are all familiar, and by easily + comprehensible and obvious examples drawn from it, to show what are the + kind of problems which living beings in general lay before us; and I shall + then show you that the same problems are laid open to us by all kinds of + living beings. But, first, let me say in what sense I have used the words + "organic nature." In speaking of the causes which lead to our present + knowledge of organic nature, I have used it almost as an equivalent of the + word "living," and for this reason,--that in almost all living beings you + can distinguish several distinct portions set apart to do particular + things and work in a particular way. These are termed "organs," and the + whole together is called "organic." And as it is universally + characteristic of them, the term "organic" has been very conveniently + employed to denote the whole of living nature,--the whole of the plant + world, and the whole of the animal world. + </p> + <p> + Few animals can be more familiar to you than that whose skeleton is shown + on our diagram. You need not bother yourselves with this "<i>Equus + caballus</i>" written under it; that is only the Latin name of it, and + does not make it any better. It simply means the common horse. Suppose we + wish to understand all about the horse. Our first object must be to study + the structure of the animal. The whole of his body is inclosed within a + hide, a skin covered with hair; and if that hide or skin be taken off, we + find a great mass of flesh, or what is technically called muscle, being + the substance which by its power of contraction enables the animal to + move. These muscles move the hard parts one upon the other, and so give + that strength and power of motion which renders the horse so useful to us + in the performance of those services in which we employ him. + </p> + <p> + And then, on separating and removing the whole of this skin and flesh, you + have a great series of bones, hard structures, bound together with + ligaments, and forming the skeleton which is represented here. + </p> + <p> + In that skeleton there are a number of parts to be recognised. The long + series of bones, beginning from the skull and ending in the tail, is + called the spine, and those in front are the ribs; and then there are two + pairs of limbs, one before and one behind; and there are what we all know + as the fore-legs and the hind-legs. If we pursue our researches into the + interior of this animal, we find within the framework of the skeleton a + great cavity, or rather, I should say, two great cavities,--one cavity + beginning in the skull and running through the neck-bones, along the + spine, and ending in the tail, containing the brain and the spinal marrow, + which are extremely important organs. The second great cavity, commencing + with the mouth, contains the gullet, the stomach, the long intestine, and + all the rest of those internal apparatus which are essential for + digestion; and then in the same great cavity, there are lodged the heart + and all the great vessels going from it; and, besides that, the organs of + respiration--the lungs: and then the kidneys, and the organs of + reproduction, and so on. Let us now endeavour to reduce this notion of a + horse that we now have, to some such kind of simple expressions as can be + at once, and without difficulty, retained in the mind, apart from all + minor details. If I make a transverse section, that is, if I were to saw a + dead horse across, I should find that, if I left out the details, and + supposing I took my section through the anterior region, and through the + fore-limbs, I should have here this kind of section of the body (Fig. 1). + </p> + <div class="fig" style="width:65%"> + <img src="images/8thdr_01.png" alt="Fig. 1: section of a horse" + width="100%" /><br /> + </div> + <p> + Here would be the upper part of the animal--that great mass of bones that + we spoke of as the spine (<i>a</i>, Fig. 1). Here I should have the + alimentary canal (<i>b</i>, Fig. 1). Here I should have the heart (<i>c</i>, + Fig. 1); and then you see, there would be a kind of double tube, the whole + being inclosed within the hide; the spinal marrow would be placed in the + upper tube (<i>a</i>, Fig. 1), and in the lower tube (<i>d d</i>, Fig. 1), + there would be the alimentary canal (<i>b</i>), and the heart (<i>e</i>); + and here I shall have the legs proceeding from each side. For simplicity's + sake, I represent them merely as stumps (<i>e e</i>, Fig. 1). Now that is + a horse--as mathematicians would say--reduced to its most simple + expression. Carry that in your minds, if you please, as a simplified idea + of the structure of the horse. The considerations which I have now put + before you belong to what we technically call the "Anatomy" of the horse. + Now, suppose we go to work upon these several parts,--flesh and hair, and + skin and bone, and lay open these various organs with our scalpels, and + examine them by means of our magnifying-glasses, and see what we can make + of them. We shall find that the flesh is made up of bundles of strong + fibres The brain and nerves, too, we shall find are made up of fibres, and + these queer-looking things that are called ganglionic corpuscles. If we + take a slice of the bone and examine it, we shall find that it is very + like this diagram of a section of the bone of on ostrich, though + differing, of course, in some details; and if we take any part whatsoever + of the tissue, and examine it, we shall find it all has a minute + structure, visible only under the microscope. All these parts constitute + microscopic anatomy or "Histology." These parts are constantly being + changed; every part is constantly growing, decaying, and being replaced + during the life of the animal. The tissue is constantly replaced by new + material; and if you go back to the young state of the tissue in the case + of muscle, or in the case of skin, or any of the organs I have mentioned, + you will find that they all come under the same condition. Every one of + these microscopic filaments and fibres (I now speak merely of the general + character of the whole process)--every one of these parts--could be traced + down to some modification of a tissue which can be readily divided into + little particles of fleshy matter, of that substance which is composed of + the chemical elements, carbon, hydrogen, oxygen, and nitrogen, having such + a shape as this (Fig. 2). These particles, into which all primitive + tissues break up, are called cells. If I were to make a section of a piece + of the skin of my hand, I should find that it was made up of these cells. + If I examine the fibres which form the various organs of all living + animals, I should find that all of them, at one time or other, had been + formed out of a substance consisting of similar elements; so that you see, + just as we reduced the whole body in the gross to that sort of simple + expression given in Fig. 1, so we may reduce the whole of the microscopic + structural elements to a form of even greater simplicity; just as the plan + of the whole body may be so represented in a sense (Fig. 1), so the + primary structure of every tissue may be represented by a mass of cells + (Fig. 2). + </p> + <div class="fig" style="width:65%"> + <img src="images/8thdr_02.png" alt="Fig. 2: section of a cell" width="100%" /><br /> + </div> + <p> + Having thus, in this sort of general way, sketched to you what I may call, + perhaps, the architecture of the body of the horse (what we term + technically its Morphology), I must now turn to another aspect. A horse is + not a mere dead structure: it is an active, living, working machine. + Hitherto we have, as it were, been looking at a steam-engine with the + fires out, and nothing in the boiler; but the body of the living animal is + a beautifully-formed active machine, and every part has its different work + to do in the working of that machine, which is what we call its life. The + horse, if you see him after his day's work is done, is cropping the grass + in the fields, as it may be, or munching the oats in his stable. What is + he doing? His jaws are working as a mill--and a very complex mill + too--grinding the corn, or crushing the grass to a pulp. As soon as that + operation has taken place, the food is passed down to the stomach, and + there it is mixed with the chemical fluid called the gastric juice, a + substance which has the peculiar property of making soluble and dissolving + out the nutritious matter in the grass, and leaving behind those parts + which are not nutritious; so that you have, first, the mill, then a sort + of chemical digester; and then the food, thus partially dissolved, is + carried back by the muscular contractions of the intestines into the + hinder parts of the body, while the soluble portions are taken up into the + blood. The blood is contained in a vast system of pipes, spreading through + the whole body, connected with a force-pump,--the heart,--which, by its + position and by the contractions of its valves, keeps the blood constantly + circulating in one direction, never allowing it to rest; and then, by + means of this circulation of the blood, laden as it is with the products + of digestion, the skin, the flesh, the hair, and every other part of the + body, draws from it that which it wants, and every one of these organs + derives those materials which are necessary to enable it to do its work. + </p> + <p> + The action of each of these organs, the performance of each of these + various duties, involve in their operation a continual absorption of the + matters necessary for their support, from the blood and a constant + formation of waste products, which are returned to the blood, and conveyed + by it to the lungs and the kidneys, which are organs that have allotted to + them the office of extracting, separating, and getting rid of these waste + products; and thus the general nourishment, labour, and repair of the + whole machine are kept up with order and regularity. But not only is it a + machine which feeds and appropriates to its own support the nourishment + necessary to its existence--it is an engine for locomotive purposes. The + horse desires to go from one place to another; and to enable it to do + this, it has those strong contractile bundles of muscles attached to the + bones of its limbs, which are put in motion by means of a sort of + telegraphic apparatus formed by the brain and the great spinal cord + running through the spine or backbone; and to this spinal cord are + attached a number of fibres termed nerves, which proceed to all parts of + the structure. By means of these the eyes, nose, tongue, and skin--all the + organs of perception--transmit impressions or sensations to the brain, + which acts as a sort of great central telegraph-office, receiving + impressions and sending messages to all parts of the body, and putting in + motion the muscles necessary to accomplish any movement that maybe + desired. So that you have here an extremely complex and + beautifully-proportioned machine, with all its parts working harmoniously + together towards one common object--the preservation of the life of the + animal. + </p> + <p> + Now, note this: the horse makes up its waste by feeding, and its food is + grass or oats, or perhaps other vegetable products; therefore, in the long + run, the source of all this complex machinery lies in the vegetable + kingdom. But where does the grass, or the oat, or any other plant obtain + this nourishing food-producing material? At first it is a little seed, + which soon begins to draw into itself from the earth and the surrounding + air matters which in themselves contain no vital properties whatever; it + absorbs into its own substance water, an inorganic body; it draws into its + substance carbonic acid, an inorganic matter; and ammonia, another + inorganic matter, found in the air; and then, by some wonderful chemical + process, the details of which chemists do not yet understand, though they + are near foreshadowing them, it combines them into one substance, which is + known to us as "Protein," a complex compound of carbon, hydrogen, oxygen, + and nitrogen, which alone possesses the property of manifesting vitality + and of permanently supporting animal life. So that, you see, the waste + products of the animal economy, the effete materials which are continually + being thrown off by all living beings, in the form of organic matters, are + constantly replaced by supplies of the necessary repairing and rebuilding + materials drawn from the plants, which in their turn manufacture them, so + to speak, by a mysterious combination of those same inorganic materials. + </p> + <p> + Let us trace out the history of the horse in another direction. After a + certain time, as the result of sickness or disease, the effect of + accident, or the consequence of old age, sooner or later, the animal dies. + The multitudinous operations of this beautiful mechanism flag in their + performance, the horse loses its vigour, and after passing through the + curious series of changes comprised in its formation and preservation, it + finally decays, and ends its life by going back into that inorganic world + from which all but an inappreciable fraction of its substance was derived. + Its bones become mere carbonate and phosphate of lime; the matter of its + flesh, and of its other parts, becomes, in the long run, converted into + carbonic acid, into water, and into ammonia. You will now, perhaps, + understand the curious relation of the animal with the plant, of the + organic with the inorganic world, which is shown in this diagram. + </p> + <div class="fig" style="width:65%"> + <img src="images/8thdr_03.png" + alt="Fig. 3: the curious relation of the animal with the plant" + width="100%" /><br /> + </div> + <p> + The plant gathers these inorganic materials together and makes them up + into its own substance. The animal eats the plant and appropriates the + nutritious portions to its own sustenance, rejects and gets rid of the + useless matters; and, finally, the animal itself dies, and its whole body + is decomposed and returned into the inorganic world. There is thus a + constant circulation from one to the other, a continual formation of + organic life from inorganic matters, and as constant a return of the + matter of living bodies to the inorganic world; so that the materials of + which our bodies are composed are largely, in all probability, the + substances which constituted the matter of long extinct creations, but + which have in the interval constituted a part of the inorganic world. + </p> + <p> + Thus we come to the conclusion, strange at first sight, that the MATTER + constituting the living world is identical with that which forms the + inorganic world. And not less true is it that, remarkable as are the + powers or, in other words, as are the FORCES which are exerted by living + beings, yet all these forces are either identical with those which exist + in the inorganic world, or they are convertible into them; I mean in just + the same sense as the researches of physical philosophers have shown that + heat is convertible into electricity, that electricity is convertible into + magnetism, magnetism into mechanical force or chemical force, and any one + of them with the other, each being measurable in terms of the other,--even + so, I say, that great law is applicable to the living world. Consider why + is the skeleton of this horse capable of supporting the masses of flesh + and the various organs forming the living body, unless it is because of + the action of the same forces of cohesion which combines together the + particles of matter composing this piece of chalk? What is there in the + muscular contractile power of the animal but the force which is + expressible, and which is in a certain sense convertible, into the force + of gravity which it overcomes? Or, if you go to more hidden processes, in + what does the process of digestion differ from those processes which are + carried on in the laboratory of the chemist? Even if we take the most + recondite and most complex operations of animal life--those of the nervous + system, these of late years have been shown to be--I do not say identical + in any sense with the electrical processes--but this has been shown, that + they are in some way or other associated with them; that is to say, that + every amount of nervous action is accompanied by a certain amount of + electrical disturbance in the particles of the nerves in which that + nervous action is carried on. In this way the nervous action is related to + electricity in the same way that heat is related to electricity; and the + same sort of argument which demonstrates the two latter to be related to + one another shows that the nervous forces are correlated to electricity; + for the experiments of M. Dubois Reymond and others have shown that + whenever a nerve is in a state of excitement, sending a message to the + muscles or conveying an impression to the brain, there is a disturbance of + the electrical condition of that nerve which does not exist at other + times; and there are a number of other facts and phenomena of that sort; + so that we come to the broad conclusion that not only as to living matter + itself, but as to the forces that matter exerts, there is a close + relationship between the organic and the inorganic world--the difference + between them arising from the diverse combination and disposition of + identical forces, and not from any primary diversity, so far as we can + see. + </p> + <p> + I said just now that the horse eventually died and became converted into + the same inorganic substances from whence all but an inappreciable + fraction of its substance demonstrably originated, so that the actual + wanderings of matter are as remarkable as the transmigrations of the soul + fabled by Indian tradition. But before death has occurred, in the one sex + or the other, and in fact in both, certain products or parts of the + organism have been set free, certain parts of the organisms of the two + sexes have come into contact with one another, and from that conjunction, + from that union which then takes place, there results the formation of a + new being. At stated times the mare, from a particular part of the + interior of her body, called the ovary, gets rid of a minute particle of + matter comparable in all essential respects with that which we called a + cell a little while since, which cell contains a kind of nucleus in its + centre, surrounded by a clear space and by a viscid mass of protein + substance (Fig. 2); and though it is different in appearance from the eggs + which we are mostly acquainted with, it is really an egg. After a time + this minute particle of matter, which may only be a small fraction of a + grain in weight, undergoes a series of changes,--wonderful, complex + changes. Finally, upon its surface there is fashioned a little elevation, + which afterwards becomes divided and marked by a groove. The lateral + boundaries of the groove extend upwards and downwards, and at length give + rise to a double tube. In the upper and smaller tube the spinal marrow and + brain are fashioned; in the lower, the alimentary canal and heart; and at + length two pairs of buds shoot out at the sides of the body, and they are + the rudiments of the limbs. In fact a true drawing of a section of the + embryo in this state would in all essential respects resemble that diagram + of a horse reduced to its simplest expression, which I first placed before + you (Fig. 1). + </p> + <p> + Slowly and gradually these changes take place. The whole of the body, at + first, can be broken up into "cells," which become in one place + metamorphosed into muscle,--in another place into gristle and bone,--in + another place into fibrous tissue,--and in another into hair; every part + becoming gradually and slowly fashioned, as if there were an artificer at + work in each of these complex structures that I have mentioned. This + embryo, as it is called, then passes into other conditions. I should tell + you that there is a time when the embryos of neither dog, nor horse, nor + porpoise, nor monkey, nor man, can be distinguished by any essential + feature one from the other; there is a time when they each and all of them + resemble this one of the dog. But as development advances, all the parts + acquire their speciality, till at length you have the embryo converted + into the form of the parent from which it started. So that you see, this + living animal, this horse, begins its existence as a minute particle of + nitrogenous matter, which, being supplied with nutriment (derived, as I + have shown, from the inorganic world), grows up according to the special + type and construction of its parents, works and undergoes a constant + waste, and that waste is made good by nutriment derived from the inorganic + world; the waste given off in this way being directly added to the + inorganic world. Eventually the animal itself dies, and, by the process of + decomposition, its whole body is returned to those conditions of inorganic + matter in which its substance originated. + </p> + <p> + This, then, is that which is true of every living form, from the lowest + plant to the highest animal--to man himself. You might define the life of + every one in exactly the same terms as those which I have now used; the + difference between the highest and the lowest being simply in the + complexity of the developmental changes, the variety of the structural + forms, and the diversity of the physiological functions which are exerted + by each. + </p> + <p> + If I were to take an oak tree, as a specimen of the plant world, I should + find that it originated in an acorn, which, too, commenced in a cell; the + acorn is placed in the ground, and it very speedily begins to absorb the + inorganic matters I have named, adds enormously to its bulk, and we can + see it, year after year, extending itself upward and downward, attracting + and appropriating to itself inorganic materials, which it vivifies, and + eventually, as it ripens, gives off its own proper acorns, which again run + the same course. But I need not multiply examples,--from the highest to + the lowest the essential features of life are the same as I have described + in each of these cases. + </p> + <p> + So much, then, for these particular features of the organic world, which + you can understand and comprehend, so long as you confine yourself to one + sort of living being, and study that only. + </p> + <p> + But, as you know, horses are not the only living creatures in the world; + and again, horses, like all other animals, have certain limits--are + confined to a certain area on the surface of the earth on which we + live,--and, as that is the simpler matter, I may take that first. In its + wild state, and before the discovery of America, when the natural state of + things was interfered with by the Spaniards, the horse was only to be + found in parts of the earth which are known to geographers as the Old + World; that is to say, you might meet with horses in Europe, Asia, or + Africa; but there were none in Australia, and there were none whatsoever + in the whole continent of America, from Labrador down to Cape Horn. This + is an empirical fact, and it is what is called, stated in the way I have + given it you, the "Geographical Distribution" of the horse. + </p> + <p> + Why horses should be found in Europe, Asia, and Africa, and not in + America, is not obvious; the explanation that the conditions of life in + America are unfavourable to their existence, and that, therefore, they had + not been created there, evidently does not apply; for when the invading + Spaniards, or our own yeomen farmers, conveyed horses to these countries + for their own use, they were found to thrive well and multiply very + rapidly; and many are even now running wild in those countries, and in a + perfectly natural condition. Now, suppose we were to do for every animal + what we have here done for the horse,--that is, to mark off and + distinguish the particular district or region to which each belonged; and + supposing we tabulated all these results, that would be called the + Geographical Distribution of animals, while a corresponding study of + plants would yield as a result the Geographical Distribution of plants. + </p> + <p> + I pass on from that now, as I merely wished to explain to you what I meant + by the use of the term "Geographical Distribution." As I said, there is + another aspect, and a much more important one, and that is, the relations + of the various animals to one another. The horse is a very well-defined + matter-of-fact sort of animal, and we are all pretty familiar with its + structure. I dare say it may have struck you, that it resembles very much + no other member of the animal kingdom, except perhaps the zebra or the + ass. But let me ask you to look along these diagrams. Here is the skeleton + of the horse, and here the skeleton of the dog. You will notice that we + have in the horse a skull, a backbone and ribs, shoulder-blades and + haunch-bones. In the fore-limb, one upper arm-bone, two fore arm-bones, + wrist-bones (wrongly called knee), and middle hand-bones, ending in the + three bones of a finger, the last of which is sheathed in the horny hoof + of the fore-foot: in the hind-limb, one thigh-bone, two leg-bones, + ankle-bones, and middle foot-bones, ending in the three bones of a toe, + the last of which is encased in the hoof of the hind-foot. Now turn to the + dog's skeleton. We find identically the same bones, but more of them, + there being more toes in each foot, and hence more toe-bones. + </p> + <p> + Well, that is a very curious thing! The fact is that the dog and the + horse--when one gets a look at them without the outward impediments of the + skin--are found to be made in very much the same sort of fashion. And if I + were to make a transverse section of the dog, I should find the same + organs that I have already shown you as forming parts of the horse. Well, + here is another skeleton--that of a kind of lemur--you see he has just the + same bones; and if I were to make a transverse section of it, it would be + just the same again. In your mind's eye turn him round, so as to put his + backbone in a position inclined obliquely upwards and forwards, just as in + the next three diagrams, which represent the skeletons of an orang, a + chimpanzee, and a gorilla, and you find you have no trouble in identifying + the bones throughout; and lastly turn to the end of the series, the + diagram representing a man's skeleton, and still you find no great + structural feature essentially altered. There are the same bones in the + same relations. From the horse we pass on and on, with gradual steps until + we arrive at last at the highest known forms. On the other hand, take the + other line of diagrams, and pass from the horse downwards in the scale to + this fish; and still, though the modifications are vastly greater, the + essential framework of the organisation remains unchanged. Here, for + instance, is a porpoise: here is its strong backbone, with the cavity + running through it, which contains the spinal cord; here are the ribs, + here the shoulder-blade; here is the little short upper-arm bone, here are + the two forearm bones, the wrist-bone, and the finger-bones. + </p> + <p> + Strange, is it not, that the porpoise should have in this queer-looking + affair--its flapper (as it is called), the same fundamental elements as + the fore-leg of the horse or the dog, or the ape or man; and here you will + notice a very curious thing,--the hinder limbs are absent. Now, let us + make another jump. Let us go to the codfish: here you see is the forearm, + in this large pectoral fin--carrying your mind's eye onward from the + flapper of the porpoise. And here you have the hinder limbs restored in + the shape of these ventral fins. If I were to make a transverse section of + this, I should find just the same organs that we have before noticed. So + that, you see, there comes out this strange conclusion as the result of + our investigations, that the horse, when examined and compared with other + animals, is found by no means to stand alone in Nature; but that there are + an enormous number of other creatures which have backbones, ribs, and + legs, and other parts arranged in the same general manner, and in all + their formation exhibiting the same broad peculiarities. + </p> + <p> + I am sure that you cannot have followed me even in this extremely + elementary exposition of the structural relations of animals, without + seeing what I have been driving at all through, which is, to show you + that, step by step, naturalists have come to the idea of a unity of plan, + or conformity of construction, among animals which appeared at first sight + to be extremely dissimilar. + </p> + <p> + And here you have evidence of such a unity of plan among all the animals + which have backbones, and which we technically call <i>Vertebrata</i>. But + there are multitudes of other animals, such as crabs, lobsters, spiders, + and so on, which we term <i>Annulosa</i>. In these I could not point out + to you the parts that correspond with those of the horse,--the backbone, + for instance,--as they are constructed upon a very different principle, + which is also common to all of them; that is to say, the lobster, the + spider, and the centipede, have a common plan running through their whole + arrangement, in just the same way that the horse, the dog, and the + porpoise assimilate to each other. + </p> + <p> + Yet other creatures--whelks, cuttlefishes, oysters, snails, and all their + tribe (<i>Mollusca</i>)--resemble one another in the same way, but differ + from both <i>Vertebrata</i> and <i>Annulosa</i>; and the like is true of + the animals called <i>Coelenterata</i> (Polypes) and <i>Protozoa</i> + (animalcules and sponges). + </p> + <p> + Now, by pursuing this sort of comparison, naturalists have arrived at the + conviction that there are,--some think five, and some seven,--but + certainly not more than the latter number--and perhaps it is simpler to + assume five--distinct plans or constructions in the whole of the animal + world; and that the hundreds of thousands of species of creatures on the + surface of the earth, are all reducible to those five, or, at most, seven, + plans of organisation. + </p> + <p> + But can we go no further than that? When one has got so far, one is + tempted to go on a step and inquire whether we cannot go back yet further + and bring down the whole to modifications of one primordial unit. The + anatomist cannot do this; but if he call to his aid the study of + development, he can do it. For we shall find that, distinct as those plans + are, whether it be a porpoise or man, or lobster, or any of those other + kinds I have mentioned, every one begins its existence with one and the + same primitive form,--that of the egg, consisting, as we have seen, of a + nitrogenous substance, having a small particle or nucleus in the centre of + it. Furthermore, the earlier changes of each are substantially the same. + And it is in this that lies that true "unity of organisation" of the + animal kingdom which has been guessed at and fancied for many years; but + which it has been left to the present time to be demonstrated by the + careful study of development. But is it possible to go another step + further still, and to show that in the same way the whole of the organic + world is reducible to one primitive condition of form? Is there among the + plants the same primitive form of organisation, and is that identical with + that of the animal kingdom? The reply to that question, too, is not + uncertain or doubtful. It is now proved that every plant begins its + existence under the same form; that is to say, in that of a cell--a + particle of nitrogenous matter having substantially the same conditions. + So that if you trace back the oak to its first germ, or a man, or a horse, + or lobster, or oyster, or any other animal you choose to name, you shall + find each and all of these commencing their existence in forms essentially + similar to each other; and, furthermore, that the first processes of + growth, and many of the subsequent modifications, are essentially the same + in principle in almost all. + </p> + <p> + In conclusion, let me, in a few words, recapitulate the positions which I + have laid down. And you must understand that I have not been talking mere + theory; I have been speaking of matters which are as plainly demonstrable + as the commonest propositions of Euclid--of facts that must form the basis + of all speculations and beliefs in Biological science. We have gradually + traced down all organic forms, or, in other words, we have analysed the + present condition of animated nature, until we found that each species + took its origin in a form similar to that under which all the others + commenced their existence. We have found the whole of the vast array of + living forms with which we are surrounded, constantly growing, increasing, + decaying and disappearing; the animal constantly attracting, modifying, + and applying to its sustenance the matter of the vegetable kingdom, which + derived its support from the absorption and conversion of inorganic + matter. And so constant and universal is this absorption, waste, and + reproduction, that it may be said with perfect certainty that there is + left in no one of our bodies at the present moment a millionth part of the + matter of which they were originally formed! We have seen, again, that not + only is the living matter derived from the inorganic world, but that the + forces of that matter are all of them correlative with and convertible + into those of inorganic nature. + </p> + <p> + This, for our present purposes, is the best view of the present condition + of organic nature which I can lay before you: it gives you the great + outlines of a vast picture, which you must fill up by your own study. + </p> + <p> + In the next lecture I shall endeavour in the same way to go back into the + past, and to sketch in the same broad manner the history of life in epochs + preceding our own. + </p> + <h3> + II. The Past Condition Of Organic Nature + </h3> + <p> + In the lecture which I delivered last Monday evening, I endeavoured to + sketch in a very brief manner, but as well as the time at my disposal + would permit, the present condition of organic nature, meaning by that + large title simply an indication of the great, broad, and general + principles which are to be discovered by those who look attentively at the + phenomena of organic nature as at present displayed. The general result of + our investigations might be summed up thus: we found that the multiplicity + of the forms of animal life, great as that may be, may be reduced to a + comparatively few primitive plans or types of construction; that a further + study of the development of those different forms revealed to us that they + were again reducible, until we at last brought the infinite diversity of + animal, and even vegetable life, down to the primordial form of a single + cell. + </p> + <p> + We found that our analysis of the organic world, whether animals or + plants, showed, in the long run, that they might both be reduced into, and + were, in fact, composed of, the same constituents. And we saw that the + plant obtained the materials constituting its substance by a peculiar + combination of matters belonging entirely to the inorganic world; that, + then, the animal was constantly appropriating the nitrogenous matters of + the plant to its own nourishment, and returning them back to the inorganic + world, in what we spoke of as its waste; and that finally, when the animal + ceased to exist, the constituents of its body were dissolved and + transmitted to that inorganic world whence they had been at first + abstracted. Thus we saw in both the blade of grass and the horse but the + same elements differently combined and arranged. We discovered a continual + circulation going on,--the plant drawing in the elements of inorganic + nature and combining them into food for the animal creation; the animal + borrowing from the plant the matter for its own support, giving off during + its life products which returned immediately to the inorganic world; and + that, eventually, the constituent materials of the whole structure of both + animals and plants were thus returned to their original source: there was + a constant passage from one state of existence to another, and a returning + back again. + </p> + <p> + Lastly, when we endeavoured to form some notion of the nature of the + forces exercised by living beings, we discovered that they--if not capable + of being subjected to the same minute analysis as the constituents of + those beings themselves--that they were correlative with--that they were + the equivalents of the forces of inorganic nature--that they were, in the + sense in which the term is now used, convertible with them. That was our + general result. + </p> + <p> + And now, leaving the Present, I must endeavour in the same manner to put + before you the facts that are to be discovered in the Past history of the + living world, in the past conditions of organic nature. We have, to-night, + to deal with the facts of that history--a history involving periods of + time before which our mere human records sink into utter insignificance--a + history the variety and physical magnitude of whose events cannot even be + foreshadowed by the history of human life and human phenomena--a history + of the most varied and complex character. + </p> + <p> + We must deal with the history, then, in the first place, as we should deal + with all other histories. The historical student knows that his first + business should be to inquire into the validity of his evidence, and the + nature of the record in which the evidence is contained, that he may be + able to form a proper estimate of the correctness of the conclusions which + have been drawn from that evidence. So, here we must pass, in the first + place, to the consideration of a matter which may seem foreign to the + question under discussion. We must dwell upon the nature of the records, + and the credibility of the evidence they contain; we must look to the + completeness or incompleteness of those records themselves, before we turn + to that which they contain and reveal. The question of the credibility of + the history, happily for us, will not require much consideration, for, in + this history, unlike those of human origin, there can be no cavilling, no + differences as to the reality and truth of the facts of which it is made + up; the facts state themselves, and are laid out clearly before us. + </p> + <p> + But, although one of the greatest difficulties of the historical student + is cleared out of our path, there are other difficulties--difficulties in + rightly interpreting the facts as they are presented to us--which may be + compared with the greatest difficulties of any other kinds of historical + study. + </p> + <p> + What is this record of the past history of the globe, and what are the + questions which are involved in an inquiry into its completeness or + incompleteness? That record is composed of mud; and the question which we + have to investigate this evening resolves itself into a question of the + formation of mud. You may think, perhaps, that this is a vast step--of + almost from the sublime to the ridiculous--from the contemplation of the + history of the past ages of the world's existence to the consideration of + the history of the formation of mud! But, in Nature, there is nothing mean + and unworthy of attention; there is nothing ridiculous or contemptible in + any of her works; and this inquiry, you will soon see, I hope, takes us to + the very root and foundations of our subject. + </p> + <p> + How, then, is mud formed? Always, with some trifling exceptions, which I + need not consider now--always, as the result of the action of water, + wearing down and disintegrating the surface of the earth and rocks with + which it comes in contact--pounding and grinding it down, and carrying the + particles away to places where they cease to be disturbed by this + mechanical action, and where they can subside and rest. For the ocean, + urged by winds, washes, as we know, a long extent of coast, and every + wave, loaded as it is with particles of sand and gravel as it breaks upon + the shore, does something towards the disintegrating process. And thus, + slowly but surely, the hardest rocks are gradually ground down to a + powdery substance; and the mud thus formed, coarser or finer, as the case + may be, is carried by the rush of the tides, or currents, till it reaches + the comparatively deeper parts of the ocean, in which it can sink to the + bottom, that is, to parts where there is a depth of about fourteen or + fifteen fathoms, a depth at which the water is, usually, nearly + motionless, and in which, of course, the finer particles of this detritus, + or mud as we call it, sinks to the bottom. + </p> + <p> + Or, again, if you take a river, rushing down from its mountain sources, + brawling over the stones and rocks that intersect its path, loosening, + removing, and carrying with it in its downward course the pebbles and + lighter matters from its banks, it crushes and pounds down the rocks and + earths in precisely the same way as the wearing action of the sea waves. + The matters forming the deposit are torn from the mountain-side and + whirled impetuously into the valley, more slowly over the plain, thence + into the estuary, and from the estuary they are swept into the sea. The + coarser and heavier fragments are obviously deposited first, that is, as + soon as the current begins to lose its force by becoming amalgamated with + the stiller depths of the ocean, but the finer and lighter particles are + carried further on, and eventually deposited in a deeper and stiller + portion of the ocean. + </p> + <p> + It clearly follows from this that mud gives us a chronology; for it is + evident that supposing this, which I now sketch, to be the sea bottom, and + supposing this to be a coast-line; from the washing action of the sea upon + the rock, wearing and grinding it down into a sediment of mud, the mud + will be carried down, and, at length, deposited in the deeper parts of + this sea bottom, where it will form a layer; and then, while that first + layer is hardening, other mud which is coming from the same source will, + of course, be carried to the same place; and, as it is quite impossible + for it to get beneath the layer already there, it deposits itself above + it, and forms another layer, and in that way you gradually have layers of + mud constantly forming and hardening one above the other, and conveying a + record of time. + </p> + <p> + It is a necessary result of the operation of the law of gravitation that + the uppermost layer shall be the youngest and the lowest the oldest, and + that the different beds shall be older at any particular point or spot in + exactly the ratio of their depth from the surface. So that if they were + upheaved afterwards, and you had a series of these different layers of + mud, converted into sandstone, or limestone, as the case might be, you + might be sure that the bottom layer was deposited first, and that the + upper layers were formed afterwards. Here, you see, is the first step in + the history--these layers of mud give us an idea of time. + </p> + <p> + The whole surface of the earth,--I speak broadly, and leave out minor + qualifications,--is made up of such layers of mud, so hard, the majority + of them, that we call them rock whether limestone or sandstone, or other + varieties of rock. And, seeing that every part of the crust of the earth + is made up in this way, you might think that the determination of the + chronology, the fixing of the time which it has taken to form this crust + is a comparatively simple matter. Take a broad average, ascertain how fast + the mud is deposited upon the bottom of the sea, or in the estuary of + rivers; take it to be an inch, or two, or three inches a year, or whatever + you may roughly estimate it at; then take the total thickness of the whole + series of stratified rocks, which geologists estimate at twelve or + thirteen miles, or about seventy thousand feet, make a sum in short + division, divide the total thickness by that of the quantity deposited in + one year, and the result will, of course, give you the number of years + which the crust has taken to form. + </p> + <p> + Truly, that looks a very simple process! It would be so except for certain + difficulties, the very first of which is that of finding how rapidly + sediments are deposited; but the main difficulty--a difficulty which + renders any certain calculations of such a matter out of the question--is + this, the sea-bottom on which the deposit takes place is continually + shifting. + </p> + <p> + Instead of the surface of the earth being that stable, fixed thing that it + is popularly believed to be, being, in common parlance, the very emblem of + fixity itself, it is incessantly moving, and is, in fact, as unstable as + the surface of the sea, except that its undulations are infinitely slower + and enormously higher and deeper. + </p> + <p> + Now, what is the effect of this oscillation? Take the case to which I have + previously referred. The finer or coarser sediments that are carried down + by the current of the river, will only be carried out a certain distance, + and eventually, as we have already seen, on reaching the stiller part of + the ocean, will be deposited at the bottom. + </p> + <div class="fig" style="width:65%"> + <img src="images/8thdr_04.png" alt="Fig. 4." width="100%" /><br /> + </div> + <p> + Let C <i>y</i> (Fig. 4) be the sea-bottom, <i>y</i> D the shore, <i>x y</i> + the sea-level, then the coarser deposit will subside over the region B, + the finer over A, while beyond A there will be no deposit at all; and, + consequently, no record will be kept, simply because no deposit is going + on. Now, suppose that the whole land, C, D, which we have regarded as + stationary, goes down, as it does so, both A and B go further out from the + shore, which will be at <i>y1</i>; <i>x1</i>, <i>y1</i>, being the new + sea-level. The consequence will be that the layer of mud (A), being now, + for the most part, further than the force of the current is strong enough + to convey even the finest <i>débris</i>, will, of course, receive + no more deposits, and having attained a certain thickness will now grow no + thicker. + </p> + <p> + We should be misled in taking the thickness of that layer, whenever it may + be exposed to our view, as a record of time in the manner in which we are + now regarding this subject, as it would give us only an imperfect and + partial record: it would seem to represent too short a period of time. + </p> + <p> + Suppose, on the other hand, that the land (C D) had gone on rising slowly + and gradually--say an inch or two inches in the course of a century,--what + would be the practical effect of that movement? Why, that the sediment A + and B which has been already deposited, would eventually be brought nearer + to the shore-level and again subjected to the wear and tear of the sea; + and directly the sea begins to act upon it, it would of course soon cut up + and carry it way, to a greater or less extent, to be re-deposited further + out. + </p> + <p> + Well, as there is, in all probability, not one single spot on the whole + surface of the earth, which has not been up and down in this way a great + many times, it follows that the thickness of the deposits formed at any + particular spot cannot be taken (even supposing we had at first obtained + correct data as to the rate at which they took place), as affording + reliable information as to the period of time occupied in its deposit. So + that you see it is absolutely necessary from these facts, seeing that our + record entirely consists of accumulations of mud, superimposed one on the + other; seeing in the next place that any particular spots on which + accumulations have occurred, have been constantly moving up and down, and + sometimes out of the reach of a deposit, and at other times its own + deposit broken up and carried away, it follows that our record must be in + the highest degree imperfect, and we have hardly a trace left of thick + deposits, or any definite knowledge of the area that they occupied, in a + great many cases. And mark this! That supposing even that the whole + surface of the earth had been accessible to the geologist,--that man had + had access to every part of the earth, and had made sections of the whole, + and put them all together,--even then his record must of necessity be + imperfect. + </p> + <p> + But to how much has man really access? If you will look at this map you + will see that it represents the proportion of the sea to the earth: this + coloured part indicates all the dry land, and this other portion is the + water. You will notice at once that the water covers three-fifths of the + whole surface of the globe, and has covered it in the same manner ever + since man has kept any record of his own observations, to say nothing of + the minute period during which he has cultivated geological inquiry. So + that three-fifths of the surface of the earth is shut out from us because + it is under the sea. Let us look at the other two-fifths, and see what are + the countries in which anything that may be termed searching geological + inquiry has been carried out: a good deal of France, Germany, and Great + Britain and Ireland, bits of Spain, of Italy, and of Russia, have been + examined, but of the whole great mass of Africa, except parts of the + southern extremity, we know next to nothing; little bits of India, but of + the greater part of the Asiatic continent nothing; bits of the Northern + American States and of Canada, but of the greater part of the continent of + North America, and in still larger proportion, of South America, nothing! + </p> + <p> + Under these circumstances, it follows that even with reference to that + kind of imperfect information which we can possess, it is only of about + the ten-thousandth part of the accessible parts of the earth that has been + examined properly. Therefore, it is with justice that the most thoughtful + of those who are concerned in these inquiries insist continually upon the + imperfection of the geological record; for, I repeat, it is absolutely + necessary, from the nature of things, that that record should be of the + most fragmentary and imperfect character. Unfortunately this circumstance + has been constantly forgotten. Men of science, like young colts in a fresh + pasture, are apt to be exhilarated on being turned into a new field of + inquiry, to go off at a hand-gallop, in total disregard of hedges and + ditches, to lose sight of the real limitation of their inquiries, and to + forget the extreme imperfection of what is really known. Geologists have + imagined that they could tell us what was going on at all parts of the + earth's surface during a given epoch; they have talked of this deposit + being contemporaneous with that deposit, until, from our little local + histories of the changes at limited spots of the earth's surface, they + have constructed a universal history of the globe as full of wonders and + portents as any other story of antiquity. + </p> + <p> + But what does this attempt to construct a universal history of the globe + imply? It implies that we shall not only have a precise knowledge of the + events which have occurred at any particular point, but that we shall be + able to say what events, at any one spot, took place at the same time with + those at other spots. + </p> + <p> + Let us see how far that is in the nature of things practicable. Suppose + that here I make a section of the Lake of Killarney, and here the section + of another lake--that of Loch Lomond in Scotland for instance. The rivers + that flow into them are constantly carrying down deposits of mud, and + beds, or strata, are being as constantly formed, one above the other, at + the bottom of those lakes. Now, there is not a shadow of doubt that in + these two lakes the lower beds are all older than the upper--there is no + doubt about that; but what does <i>this</i> tell us about the age of any + given bed in Loch Lomond, as compared with that of any given bed in the + Lake of Killarney? It is, indeed, obvious that if any two sets of deposits + are separated and discontinuous, there is absolutely no means whatever + given you by the nature of the deposit of saying whether one is much + younger or older than the other; but you may say, as many have said and + think, that the case is very much altered if the beds which we are + comparing are continuous. Suppose two beds of mud hardened into rock,--A + and B--are seen in section. (Fig. 5.) + </p> + <div class="fig" style="width:65%"> + <img src="images/8thdr_05.png" alt="Fig. 5." width="100%" /><br /> + </div> + <p> + Well, you say, it is admitted that the lowermost bed is always the older. + Very well; B, therefore, is older than A. No doubt, <i>as a whole</i>, it + is so; or if any parts of the two beds which are in the same vertical line + are compared, it is so. But suppose you take what seems a very natural + step further, and say that the part <i>a</i> of the bed A is younger than + the part <i>b</i> of the bed B. Is this sound reasoning? If you find any + record of changes taking place at <i>b</i>, did they occur before any + events which took place while <i>a</i> was being deposited? It looks all + very plain sailing, indeed, to say that they did; and yet there is no + proof of anything of the kind. As the former Director of this Institution, + Sir H. De la Beche, long ago showed, this reasoning may involve an entire + fallacy. It is extremely possible that <i>a</i> may have been deposited + ages before <i>b</i>. It is very easy to understand how that can be. To + return to Fig. 4; when A and B were deposited, they were <i>substantially</i> + contemporaneous; A being simply the finer deposit, and B the coarser of + the same detritus or waste of land. Now suppose that that sea-bottom goes + down (as shown in Fig. 4), so that the first deposit is carried no farther + than <i>a</i>, forming the bed A1, and the coarse no farther than <i>b</i>, + forming the bed B1, the result will be the formation of two continuous + beds, one of fine sediment (A A1) over-lapping another of coarse sediment + (B B1). Now suppose the whole sea-bottom is raised up, and a section + exposed about the point A1; no doubt, <i>at this spot</i>, the upper bed + is younger than the lower. But we should obviously greatly err if we + concluded that the mass of the upper bed at A was younger than the lower + bed at B; for we have just seen that they are contemporaneous deposits. + Still more should we be in error if we supposed the upper bed at A to be + younger than the continuation of the lower bed at B1; for A was deposited + long before B1. In fine, if, instead of comparing immediately adjacent + parts of two beds, one of which lies upon another, we compare distant + parts, it is quite possible that the upper may be any number of years + older than the under, and the under any number of years younger than the + upper. + </p> + <p> + Now you must not suppose that I put this before you for the purpose of + raising a paradoxical difficulty; the fact is, that the great mass of + deposits have taken place in sea-bottoms which are gradually sinking, and + have been formed under the very conditions I am here supposing. + </p> + <p> + Do not run away with the notion that this subverts the principle I laid + down at first. The error lies in extending a principle which is perfectly + applicable to deposits in the same vertical line to deposits which are not + in that relation to one another. + </p> + <p> + It is in consequence of circumstances of this kind, and of others that I + might mention to you, that our conclusions on and interpretations of the + record are really and strictly only valid so long as we confine ourselves + to one vertical section. I do not mean to tell you that there are no + qualifying circumstances, so that, even in very considerable areas, we may + safely speak of conformably superimposed beds being older or younger than + others at many different points. But we can never be quite sure in coming + to that conclusion, and especially we cannot be sure if there is any break + in their continuity, or any very great distance between the points to be + compared. + </p> + <p> + Well now, so much for the record itself,--so much for its + imperfections,--so much for the conditions to be observed in interpreting + it, and its chronological indications, the moment we pass beyond the + limits of a vertical linear section. + </p> + <p> + Now let us pass from the record to that which it contains,--from the book + itself to the writing and the figures on its pages. This writing and these + figures consist of remains of animals and plants which, in the great + majority of cases, have lived and died in the very spot in which we now + find them, or at least in the immediate vicinity. You must all of you be + aware--and I referred to the fact in my last lecture--that there are vast + numbers of creatures living at the bottom of the sea. These creatures, + like all others, sooner or later die, and their shells and hard parts lie + at the bottom; and then the fine mud which is being constantly brought + down by rivers and the action of the wear and tear of the sea, covers them + over and protects them from any further change or alteration; and, of + course, as in process of time the mud becomes hardened and solidified, the + shells of these animals are preserved and firmly imbedded in the limestone + or sandstone which is being thus formed. You may see in the galleries of + the Museum up stairs specimens of limestones in which such fossil remains + of existing animals are imbedded. There are some specimens in which + turtles' eggs have been imbedded in calcareous sand, and before the sun + had hatched the young turtles, they became covered over with calcareous + mud, and thus have been preserved and fossilised. + </p> + <p> + Not only does this process of imbedding and fossilisation occur with + marine and other aquatic animals and plants, but it affects those land + animals and plants which are drifted away to sea, or become buried in bogs + or morasses; and the animals which have been trodden down by their fellows + and crushed in the mud at the river's bank, as the herd have come to + drink. In any of these cases, the organisms may be crushed or be + mutilated, before or after putrefaction, in such a manner that perhaps + only a part will be left in the form in which it reaches us. It is, + indeed, a most remarkable fact, that it is quite an exceptional case to + find a skeleton of any one of all the thousands of wild land animals that + we know are constantly being killed, or dying in the course of nature: + they are preyed on and devoured by other animals, or die in places where + their bodies are not afterwards protected by mud. There are other animals + existing on the sea, the shells of which form exceedingly large deposits. + You are probably aware that before the attempt was made to lay the + Atlantic telegraphic cable, the Government employed vessels in making a + series of very careful observations and soundings of the bottom of the + Atlantic; and although, as we must all regret, that up to the present time + that project has not succeeded, we have the satisfaction of knowing that + it yielded some most remarkable results to science. The Atlantic Ocean had + to be sounded right across, to depths of several miles in some places, and + the nature of its bottom was carefully ascertained. Well, now, a space of + about 1,000 miles wide from east to west, and I do not exactly know how + many from north to south, but at any rate 600 or 700 miles, was carefully + examined, and it was found that over the whole of that immense area an + excessively fine chalky mud is being deposited; and this deposit is + entirely made up of animals whose hard parts are deposited in this part of + the ocean, and are doubtless gradually acquiring solidity and becoming + metamorphosed into a chalky limestone. Thus, you see, it is quite possible + in this way to preserve unmistakable records of animal and vegetable life. + Whenever the sea-bottom, by some of those undulations of the earth's crust + that I have referred to, becomes up-heaved, and sections or borings are + made, or pits are dug, then we become able to examine the contents and + constituents of these ancient sea-bottoms, and find out what manner of + animals lived at that period. + </p> + <p> + Now it is a very important consideration in its bearing on the + completeness of the record, to inquire how far the remains contained in + these fossiliferous limestones are able to convey anything like an + accurate or complete account of the animals which were in existence at the + time of its formation. Upon that point we can form a very clear judgment, + and one in which there is no possible room for any mistake. There are of + course a great number of animals--such as jellyfishes, and other + animals--without any hard parts, of which we cannot reasonably expect to + find any traces whatever: there is nothing of them to preserve. Within a + very short time, you will have noticed, after they are removed from the + water, they dry up to a mere nothing; certainly they are not of a nature + to leave any very visible traces of their existence on such bodies as + chalk or mud. Then again, look at land animals; it is, as I have said, a + very uncommon thing to find a land animal entire after death. Insects and + other carnivorous animals very speedily pull them to pieces, putrefaction + takes place, and so, out of the hundreds of thousands that are known to + die every year, it is the rarest thing in the world to see one imbedded in + such a way that its remains would be preserved for a lengthened period. + Not only is this the case, but even when animal remains have been safely + imbedded, certain natural agents may wholly destroy and remove them. + </p> + <p> + Almost all the hard parts of animals--the bones and so on--are composed + chiefly of phosphate of lime and carbonate of lime. Some years ago, I had + to make an inquiry into the nature of some very curious fossils sent to me + from the North of Scotland. Fossils are usually hard bony structures that + have become imbedded in the way I have described, and have gradually + acquired the nature and solidity of the body with which they are + associated; but in this case I had a series of <i>holes</i> in some pieces + of rock, and nothing else. Those holes, however, had a certain definite + shape about them, and when I got a skilful workman to make castings of the + interior of these holes, I found that they were the impressions of the + joints of a backbone and of the armour of a great reptile, twelve or more + feet long. This great beast had died and got buried in the sand; the sand + had gradually hardened over the bones, but remained porous. Water had + trickled through it, and that water being probably charged with a + superfluity of carbonic acid, had dissolved all the phosphate and + carbonate of lime, and the bones themselves had thus decayed and entirely + disappeared; but as the sandstone happened to have consolidated by that + time, the precise shape of the bones was retained. If that sandstone had + remained soft a little longer, we should have known nothing whatsoever of + the existence of the reptile whose bones it had encased. + </p> + <p> + How certain it is that a vast number of animals which have existed at one + period on this earth have entirely perished, and left no trace whatever of + their forms, may be proved to you by other considerations. There are large + tracts of sandstone in various parts of the world, in which nobody has yet + found anything but footsteps. Not a bone of any description, but an + enormous number of traces of footsteps. There is no question about them. + There is a whole valley in Connecticut covered with these footsteps, and + not a single fragment of the animals which made them have yet been found. + Let me mention another case while upon that matter, which is even more + surprising than those to which I have yet referred. There is a limestone + formation near Oxford, at a place called Stonesfield, which has yielded + the remains of certain very interesting mammalian animals, and up to this + time, if I recollect rightly, there have been found seven specimens of its + lower jaws, and not a bit of anything else, neither limb-bones nor skull, + nor any part whatever; not a fragment of the whole system! Of course, it + would be preposterous to imagine that the beasts had nothing else but a + lower jaw! The probability is, as Dr. Buckland showed, as the result of + his observations on dead dogs in the river Thames, that the lower jaw, not + being secured by very firm ligaments to the bones of the head, and being a + weighty affair, would easily be knocked off, or might drop away from the + body as it floated in water in a state of decomposition. The jaw would + thus be deposited immediately, while the rest of the body would float and + drift away altogether, ultimately reaching the sea, and perhaps becoming + destroyed. The jaw becomes covered up and preserved in the river silt, and + thus it comes that we have such a curious circumstance as that of the + lower jaws in the Stonesfield slates. So that, you see, faulty as these + layers of stone in the earth's crust are, defective as they necessarily + are as a record, the account of contemporaneous vital phenomena presented + by them is, by the necessity of the case, infinitely more defective and + fragmentary. + </p> + <p> + It was necessary that I should put all this very strongly before you, + because, otherwise, you might have been led to think differently of the + completeness of our knowledge by the next facts I shall state to you. + </p> + <p> + The researches of the last three-quarters of a century have, in truth, + revealed a wonderful richness of organic life in those rocks. Certainly + not fewer than thirty or forty thousand different species of fossils have + been discovered. You have no more ground for doubting that these creatures + really lived and died at or near the places in which we find them than you + have for like scepticism about a shell on the sea-shore. The evidence is + as good in the one case as in the other. + </p> + <p> + Our next business is to look at the general character of these fossil + remains, and it is a subject which will be requisite to consider + carefully; and the first point for us is to examine how much the extinct + <i>Flora</i> and <i>Fauna</i> as a <i>whole</i>--disregarding altogether + the <i>succession</i> of their constituents, of which I shall speak + afterwards--differ from the <i>Flora</i> and <i>Fauna</i> of the present + day;--how far they differ in what we <i>do</i> know about them, leaving + altogether out of consideration speculations based upon what we <i>do not</i> + know. + </p> + <p> + I strongly imagine that if it were not for the peculiar appearance that + fossilised animals have, any of you might readily walk through a museum + which contains fossil remains mixed up with those of the present forms of + life, and I doubt very much whether your uninstructed eyes would lead you + to see any vast or wonderful difference between the two. If you looked + closely, you would notice, in the first place, a great many things very + like animals with which you are acquainted now: you would see differences + of shape and proportion, but on the whole a close similarity. + </p> + <p> + I explained what I meant by ORDERS the other day, when I described the + animal kingdom as being divided into sub-kingdoms, classes and orders. If + you divide the animal kingdom into orders you will find that there are + above one hundred and twenty. The number may vary on one side or the + other, but this is a fair estimate. That is the sum total of the orders of + all the animals which we know now, and which have been known in past + times, and left remains behind. + </p> + <p> + Now, how many of those are absolutely extinct? That is to say, how many of + these orders of animals have lived at a former period of the world's + history but have at present no representatives? That is the sense in which + I meant to use the word "extinct." I mean that those animals did live on + this earth at one time, but have left no one of their kind with us at the + present moment. So that estimating the number of extinct animals is a sort + of way of comparing the past creation as a whole with the present as a + whole. Among the mammalia and birds there are none extinct; but when we + come to the reptiles there is a most wonderful thing: out of the eight + orders, or thereabouts, which you can make among reptiles, one-half are + extinct. These diagrams of the plesiosaurus, the ichthyosaurus, the + pterodactyle, give you a notion of some of these extinct reptiles. And + here is a cast of the pterodactyle and bones of the ichthyosaurus and the + plesiosaurus, just as fresh-looking as if it had been recently dug up in a + churchyard. Thus, in the reptile class, there are no less than half of the + orders which are absolutely extinct. If we turn to the <i>Amphibia</i>, + there was one extinct order, the Labyrinthodonts, typified by the large + salamander-like beast shown in this diagram. + </p> + <p> + No order of fishes is known to be extinct. Every fish that we find in the + strata--to which I have been referring--can be identified and placed in + one of the orders which exist at the present day. There is not known to be + a single ordinal form of insect extinct. There are only two orders extinct + among the <i>Crustacea</i>. There is not known to be an extinct order of + these creatures, the parasitic and other worms; but there are two, not to + say three, absolutely extinct orders of this class, the <i>Echinodermata</i>; + out of all the orders of the <i>Coelenterata</i> and <i>Protozoa</i> only + one, the Rugose Corals. + </p> + <p> + So that, you see, out of somewhere about 120 orders of animals, taking + them altogether, you will not, at the outside estimate, find above ten or + a dozen extinct. Summing up all the order of animals which have left + remains behind them, you will not find above ten or a dozen which cannot + be arranged with those of the present day; that is to say, that the + difference does not amount to much more than ten per cent.: and the + proportion of extinct orders of plants is still smaller. I think that that + is a very astounding a most astonishing fact: seeing the enormous epochs + of time which have elapsed during the constitution of the surface of the + earth as it at present exists, it is, indeed, a most astounding thing that + the proportion of extinct ordinal types should be so exceedingly small. + </p> + <p> + But now, there is another point of view in which we must look at this past + creation. Suppose that we were to sink a vertical pit through the floor + beneath us, and that I could succeed in making a section right through in + the direction of New Zealand, I should find in each of the different beds + through which I passed the remains of animals which I should find in that + stratum and not in the others. First, I should come upon beds of gravel or + drift containing the bones of large animals, such as the elephant, + rhinoceros, and cave tiger. Rather curious things to fall across in + Piccadilly! If I should dig lower still, I should come upon a bed of what + we call the London clay, and in this, as you will see in our galleries up + stairs, are found remains of strange cattle, remains of turtles, palms, + and large tropical fruits; with shell-fish such as you see the like of now + only in tropical regions. If I went below that, I should come upon the + chalk, and there I should find something altogether different, the remains + of ichthyosauria and pterodactyles, and ammonites, and so forth. + </p> + <p> + I do not know what Mr. Godwin Austin would say comes next, but probably + rocks containing more ammonites, and more ichthyosauria and plesiosauria, + with a vast number of other things; and under that I should meet with yet + older rocks containing numbers of strange shells and fishes; and in thus + passing from the surface to the lowest depths of the earth's crust, the + forms of animal life and vegetable life which I should meet with in the + successive beds would, looking at them broadly, be the more different the + further that I went down. Or, in other words, inasmuch as we started with + the clear principle, that in a series of naturally-disposed mud beds the + lowest are the oldest, we should come to this result, that the further we + go back in time the more difference exists between the animal and + vegetable life of an epoch and that which now exists. That was the + conclusion to which I wished to bring you at the end of this lecture. + </p> + <h3> + III. The Method By Which The Causes Of The Present And Past Conditions Of + Organic Nature Are To Be Discovered;--The Origination Of Living Beings + </h3> + <p> + In the two preceding lectures I have endeavoured to indicate to you the + extent of the subject-matter of the inquiry upon which we are engaged; and + having thus acquired some conception of the past and present phenomena of + organic nature, I must now turn to that which constitutes the great + problem which we have set before ourselves;--I mean, the question of what + knowledge we have of the causes of these phenomena of organic nature, and + how such knowledge is obtainable. + </p> + <p> + Here, on the threshold of the inquiry, an objection meets us. There are in + the world a number of extremely worthy, well-meaning persons, whose + judgments and opinions are entitled to the utmost respect on account of + their sincerity, who are of opinion that vital phenomena, and especially + all questions relating to the origin of vital phenomena, are questions + quite apart from the ordinary run of inquiry, and are, by their very + nature, placed out of our reach. They say that all these phenomena + originated miraculously, or in some way totally different from the + ordinary course of nature, and that therefore they conceive it to be + futile, not to say presumptuous, to attempt to inquire into them. + </p> + <p> + To such sincere and earnest persons, I would only say, that a question of + this kind is not to be shelved upon theoretical or speculative grounds. + You may remember the story of the Sophist who demonstrated to Diogenes in + the most complete and satisfactory manner that he could not walk; that, in + fact, all motion was an impossibility; and that Diogenes refuted him by + simply getting up and walking round his tub. So, in the same way, the man + of science replies to objections of this kind, by simply getting up and + walking onward, and showing what science has done and is doing---by + pointing to that immense mass of facts which have been ascertained as + systematised under the forms of the great doctrines of morphology, of + development, of distribution, and the like. He sees an enormous mass of + facts and laws relating to organic beings, which stand on the same good + sound foundation as every other natural law. With this mass of facts and + laws before us, therefore, seeing that, as far as organic matters have + hitherto been accessible and studied, they have shown themselves capable + of yielding to scientific investigation, we may accept this as proof that + order and law reign there as well as in the rest of Nature. The man of + science says nothing to objectors of this sort, but supposes that we can + and shall walk to a knowledge of the origin of organic nature, in the same + way that we have walked to a knowledge of the laws and principles of the + inorganic world. + </p> + <p> + But there are objectors who say the same from ignorance and ill-will. To + such I would reply that the objection comes ill from them, and that the + real presumption, I may almost say the real blasphemy, in this matter, is + in the attempt to limit that inquiry into the causes of phenomena, which + is the source of all human blessings, and from which has sprung all human + prosperity and progress; for, after all, we can accomplish comparatively + little; the limited range of our own faculties bounds us on every + side,--the field of our powers of observation is small enough, and he who + endeavours to narrow the sphere of our inquiries is only pursuing a course + that is likely to produce the greatest harm to his fellow-men. + </p> + <p> + But now, assuming, as we all do, I hope, that these phenomena are properly + accessible to inquiry, and setting out upon our search into the causes of + the phenomena of organic nature, or at any rate, setting out to discover + how much we at present know upon these abstruse matters, the question + arises as to what is to be our course of proceeding, and what method we + must lay down for our guidance. I reply to that question, that our method + must be exactly the same as that which is pursued in any other scientific + inquiry, the method of scientific investigation being the same for all + orders of facts and phenomena whatsoever. + </p> + <p> + I must dwell a little on this point, for I wish you to leave this room + with a very clear conviction that scientific investigation is not, as many + people seem to suppose, some kind of modern black art. I say that you + might easily gather this impression from the manner in which many persons + speak of scientific inquiry, or talk about inductive and deductive + philosophy, or the principles of the "Baconian philosophy." I do protest + that, of the vast number of cants in this world, there are none, to my + mind, so contemptible as the pseudo-scientific cant which is talked about + the "Baconian philosophy." + </p> + <p> + To hear people talk about the great Chancellor--and a very great man he + certainly was,--you would think that it was he who had invented science, + and that there was no such thing as sound reasoning before the time of + Queen Elizabeth! Of course you say, that cannot possibly be true; you + perceive, on a moment's reflection, that such an idea is absurdly wrong, + and yet, so firmly rooted is this sort of impression,--I cannot call it an + idea, or conception,--the thing is too absurd to be entertained,--but so + completely does it exist at the bottom of most men's minds, that this has + been a matter of observation with me for many years past. There are many + men who, though knowing absolutely nothing of the subject with which they + may be dealing, wish, nevertheless, to damage the author of some view with + which they think fit to disagree. What they do, then, is not to go and + learn something about the subject, which one would naturally think the + best way of fairly dealing with it; but they abuse the originator of the + view they question, in a general manner, and wind up by saying that, + "After all, you know, the principles and method of this author are totally + opposed to the canons of the Baconian philosophy." Then everybody + applauds, as a matter of course, and agrees that it must be so. But if you + were to stop them all in the middle of their applause, you would probably + find that neither the speaker nor his applauders could tell you how or in + what way it was so; neither the one nor the other having the slightest + idea of what they mean when they speak of the "Baconian philosophy." + </p> + <p> + You will understand, I hope, that I have not the slightest desire to join + in the outcry against either the morals, the intellect, or the great + genius of Lord Chancellor Bacon. He was undoubtedly a very great man, let + people say what they will of him; but notwithstanding all that he did for + philosophy, it would be entirely wrong to suppose that the methods of + modern scientific inquiry originated with him, or with his age; they + originated with the first man, whoever he was; and indeed existed long + before him, for many of the essential processes of reasoning are exerted + by the higher order of brutes as completely and effectively as by + ourselves. We see in many of the brute creation the exercise of one, at + least, of the same powers of reasoning as that which we ourselves employ. + </p> + <p> + The method of scientific investigation is nothing but the expression of + the necessary mode of working of the human mind. It is simply the mode at + which all phenomena are reasoned about, rendered precise and exact. There + is no more difference, but there is just the same kind of difference, + between the mental operations of a man of science and those of an ordinary + person, as there is between the operations and methods of a baker or of a + butcher weighing out his goods in common scales, and the operations of a + chemist in performing a difficult and complex analysis by means of his + balance and finely-graduated weights. It is not that the action of the + scales in the one case, and the balance in the other, differ in the + principles of their construction or manner of working; but the beam of one + is set on an infinitely finer axis than the other, and of course turns by + the addition of a much smaller weight. + </p> + <p> + You will understand this better, perhaps, if I give you some familiar + example. You have all heard it repeated, I dare say, that men of science + work by means of induction and deduction, and that by the help of these + operations, they, in a sort of sense, wring from Nature certain other + things, which are called natural laws, and causes, and that out of these, + by some cunning skill of their own, they build up hypotheses and theories. + And it is imagined by many, that the operations of the common mind can be + by no means compared with these processes, and that they have to be + acquired by a sort of special apprenticeship to the craft. To hear all + these large words, you would think that the mind of a man of science must + be constituted differently from that of his fellow men; but if you will + not be frightened by terms, you will discover that you are quite wrong, + and that all these terrible apparatus are being used by yourselves every + day and every hour of your lives. + </p> + <p> + There is a well-known incident in one of Molière's plays, where the + author makes the hero express unbounded delight on being told that he had + been talking prose during the whole of his life. In the same way, I trust, + that you will take comfort, and be delighted with yourselves, on the + discovery that you have been acting on the principles of inductive and + deductive philosophy during the same period. Probably there is not one + here who has not in the course of the day had occasion to set in motion a + complex train of reasoning, of the very same kind, though differing of + course in degree, as that which a scientific man goes through in tracing + the causes of natural phenomena. + </p> + <p> + A very trivial circumstance will serve to exemplify this. Suppose you go + into a fruiterer's shop, wanting an apple,--you take up one, and, on + biting it, you find it is sour; you look at it, and see that it is hard + and green. You take up another one, and that too is hard, green, and sour. + The shopman offers you a third; but, before biting it, you examine it, and + find that it is hard and green, and you immediately say that you will not + have it, as it must be sour, like those that you have already tried. + </p> + <p> + Nothing can be more simple than that, you think; but if you will take the + trouble to analyse and trace out into its logical elements what has been + done by the mind, you will be greatly surprised. In the first place, you + have performed the operation of induction. You found that, in two + experiences, hardness and greenness in apples went together with sourness. + It was so in the first case, and it was confirmed by the second. True, it + is a very small basis, but still it is enough to make an induction from; + you generalise the facts, and you expect to find sourness in apples where + you get hardness and greenness. You found upon that a general law, that + all hard and green apples are sour; and that, so far as it goes, is a + perfect induction. Well, having got your natural law in this way, when you + are offered another apple which you find is hard and green, you say, "All + hard and green apples are sour; this apple is hard and green, therefore + this apple is sour." That train of reasoning is what logicians call a + syllogism, and has all its various parts and terms,--its major premiss, + its minor premiss, and its conclusion. And, by the help of further + reasoning, which, if drawn out, would have to be exhibited in two or three + other syllogisms, you arrive at your final determination, "I will not have + that apple." So that, you see, you have, in the first place, established a + law by induction, and upon that you have founded a deduction, and reasoned + out the special conclusion of the particular case. Well now, suppose, + having got your law, that at some time afterwards, you are discussing the + qualities of apples with a friend: you will say to him, "It is a very + curious thing,--but I find that all hard and green apples are sour!" Your + friend says to you, "But how do you know that?" You at once reply, "Oh, + because I have tried them over and over again, and have always found them + to be so." Well, if we were talking science instead of common sense, we + should call that an experimental verification. And, if still opposed, you + go further, and say, "I have heard from the people in Somersetshire and + Devonshire, where a large number of apples are grown, that they have + observed the same thing. It is also found to be the case in Normandy, and + in North America. In short, I find it to be the universal experience of + mankind wherever attention has been directed to the subject." Whereupon, + your friend, unless he is a very unreasonable man, agrees with you, and is + convinced that you are quite right in the conclusion you have drawn. He + believes, although perhaps he does not know he believes it, that the more + extensive verifications are,--that the more frequently experiments have + been made, and results of the same kind arrived at,--that the more varied + the conditions under which the same results are attained, the more certain + is the ultimate conclusion, and he disputes the question no further. He + sees that the experiment has been tried under all sorts of conditions, as + to time, place, and people, with the same result; and he says with you, + therefore, that the law you have laid down must be a good one, and he must + believe it. + </p> + <p> + In science we do the same thing;--the philosopher exercises precisely the + same faculties, though in a much more delicate manner. In scientific + inquiry it becomes a matter of duty to expose a supposed law to every + possible kind of verification, and to take care, moreover, that this is + done intentionally, and not left to a mere accident, as in the case of the + apples. And in science, as in common life, our confidence in a law is in + exact proportion to the absence, of variation in the result of our + experimental verifications. For instance, if you let go your grasp of an + article you may have in your hand, it will immediately fall to the ground. + That is a very common verification of one of the best established laws of + nature--that of gravitation. The method by which men of science establish + the existence of that law is exactly the same as that by which we have + established the trivial proposition about the sourness of hard and green + apples. But we believe it in such an extensive, thorough, and unhesitating + manner because the universal experience of mankind verifies it, and we can + verify it ourselves at any time; and that is the strongest possible + foundation on which any natural law can rest. + </p> + <p> + So much, then, by way of proof that the method of establishing laws in + science is exactly the same as that pursued in common life. Let us now + turn to another matter (though really it is but another phase of the same + question), and that is, the method by which, from the relations of certain + phenomena, we prove that some stand in the position of causes towards the + others. + </p> + <p> + I want to put the case clearly before you, and I will therefore show you + what I mean by another familiar example. I will suppose that one of you, + on coming down in the morning to the parlour of your house, finds that a + tea-pot and some spoons which had been left in the room on the previous + evening are gone,--the window is open, and you observe the mark of a dirty + hand on the window-frame, and perhaps, in addition to that, you notice the + impress of a hob-nailed shoe on the gravel outside. All these phenomena + have struck your attention instantly, and before two seconds have passed + you say, "Oh, somebody has broken open the window, entered the room, and + run off with the spoons and the tea-pot!" That speech is out of your mouth + in a moment. And you will probably add, "I know there has; I am quite sure + of it!" You mean to say exactly what you know; but in reality you are + giving expression to what is, in all essential particulars, an hypothesis. + You do not <i>know</i> it at all; it is nothing but an hypothesis rapidly + framed in your own mind. And it is an hypothesis founded on a long train + of inductions and deductions. + </p> + <p> + What are those inductions and deductions, and how have you got at this + hypothesis? You have observed, in the first place, that the window is + open; but by a train of reasoning involving many inductions and + deductions, you have probably arrived long before at the general law--and + a very good one it is--that windows do not open of themselves; and you + therefore conclude that something has opened the window. A second general + law that you have arrived at in the same way is, that tea-pots and spoons + do not go out of a window spontaneously, and you are satisfied that, as + they are not now where you left them, they have been removed. In the third + place, you look at the marks on the window-sill, and the shoe-marks + outside, and you say that in all previous experience the former kind of + mark has never been produced by anything else but the hand of a human + being; and the same experience shows that no other animal but man at + present wears shoes with hob-nails in them such as would produce the marks + in the gravel. I do not know, even if we could discover any of those + "missing links" that are talked about, that they would help us to any + other conclusion! At any rate the law which states our present experience + is strong enough for my present purpose. You next reach the conclusion, + that as these kinds of marks have not been left by any other animals than + men, or are liable to be formed in any other way than by a man's hand and + shoe, the marks in question have been formed by a man in that way. You + have, further, a general law, founded on observation and experience, and + that, too, is, I am sorry to say, a very universal and unimpeachable + one,--that some men are thieves; and you assume at once from all these + premisses--and that is what constitutes your hypothesis--that the man who + made the marks outside and on the window-sill, opened the window, got into + the room, and stole your tea-pot and spoons. You have now arrived at a <i>vera + causa</i>;--you have assumed a cause which, it is plain, is competent to + produce all the phenomena you have observed. You can explain all these + phenomena only by the hypothesis of a thief. But that is a hypothetical + conclusion, of the justice of which you have no absolute proof at all; it + is only rendered highly probable by a series of inductive and deductive + reasonings. + </p> + <p> + I suppose your first action, assuming that you are a man of ordinary + common sense, and that you have established this hypothesis to your own + satisfaction, will very likely be to go off for the police, and set them + on the track of the burglar, with the view to the recovery of your + property. But just as you are starting with this object, some person comes + in, and on learning what you are about, says, "My good friend, you are + going on a great deal too fast. How do you know that the man who really + made the marks took the spoons? It might have been a monkey that took + them, and the man may have merely looked in afterwards." You would + probably reply, "Well, that is all very well, but you see it is contrary + to all experience of the way tea-pots and spoons are abstracted; so that, + at any rate, your hypothesis is less probable than mine." While you are + talking the thing over in this way, another friend arrives, one of that + good kind of people that I was talking of a little while ago. And he might + say, "Oh, my dear sir, you are certainly going on a great deal too fast. + You are most presumptuous. You admit that all these occurrences took place + when you were fast asleep, at a time when you could not possibly have + known anything about what was taking place. How do you know that the laws + of Nature are not suspended during the night? It may be that there has + been some kind of supernatural interference in this case." In point of + fact, he declares that your hypothesis is one of which you cannot at all + demonstrate the truth, and that you are by no means sure that the laws of + Nature are the same when you are asleep as when you are awake. + </p> + <p> + Well, now, you cannot at the moment answer that kind of reasoning. You + feel that your worthy friend has you somewhat at a disadvantage. You will + feel perfectly convinced in your own mind, however, that you are quite + right, and you say to him, "My good friend, I can only be guided by the + natural probabilities of the case, and if you will be kind enough to stand + aside and permit me to pass, I will go and fetch the police." Well, we + will suppose that your journey is successful, and that by good luck you + meet with a policeman; that eventually the burglar is found with your + property on his person, and the marks correspond to his hand and to his + boots. Probably any jury would consider those facts a very good + experimental verification of your hypothesis, touching the cause of the + abnormal phenomena observed in your parlour, and would act accordingly. + </p> + <p> + Now, in this suppositious case, I have taken phenomena of a very common + kind, in order that you might see what are the different steps in an + ordinary process of reasoning, if you will only take the trouble to + analyse it carefully. All the operations I have described, you will see, + are involved in the mind of any man of sense in leading him to a + conclusion as to the course he should take in order to make good a robbery + and punish the offender. I say that you are led, in that case, to your + conclusion by exactly the same train of reasoning as that which a man of + science pursues when he is endeavouring to discover the origin and laws of + the most occult phenomena. The process is, and always must be, the same; + and precisely the same mode of reasoning was employed by Newton and + Laplace in their endeavours to discover and define the causes of the + movements of the heavenly bodies, as you, with your own common sense, + would employ to detect a burglar. The only difference is, that the nature + of the inquiry being more abstruse, every step has to be most carefully + watched, so that there may not be a single crack or flaw in your + hypothesis. A flaw or crack in many of the hypotheses of daily life may be + of little or no moment as affecting the general correctness of the + conclusions at which we may arrive; but, in a scientific inquiry, a + fallacy, great or small, is always of importance, and is sure to be in the + long run constantly productive of mischievous, if not fatal results. + </p> + <p> + Do not allow yourselves to be misled by the common notion that an + hypothesis is untrustworthy simply because it is an hypothesis. It is + often urged, in respect to some scientific conclusion, that, after all, it + is only an hypothesis. But what more have we to guide us in nine-tenths of + the most important affairs of daily life than hypotheses, and often very + ill-based ones? So that in science, where the evidence of an hypothesis is + subjected to the most rigid examination, we may rightly pursue the same + course. You may have hypotheses and hypotheses. A man may say, if he + likes, that the moon is made of green cheese: that is an hypothesis. But + another man, who has devoted a great deal of time and attention to the + subject, and availed himself of the most powerful telescopes and the + results of the observations of others, declares that in his opinion it is + probably composed of materials very similar to those of which our own + earth is made up: and that is also only an hypothesis. But I need not tell + you that there is an enormous difference in the value of the two + hypotheses. That one which is based on sound scientific knowledge is sure + to have a corresponding value; and that which is a mere hasty random guess + is likely to have but little value. Every great step in our progress in + discovering causes has been made in exactly the same way as that which I + have detailed to you. A person observing the occurrence of certain facts + and phenomena asks, naturally enough, what process, what kind of operation + known to occur in Nature applied to the particular case, will unravel and + explain the mystery? Hence you have the scientific hypothesis; and its + value will be proportionate to the care and completeness with which its + basis had been tested and verified. It is in these matters as in the + commonest affairs of practical life: the guess of the fool will be folly, + while the guess of the wise man will contain wisdom. In all cases, you see + that the value of the result depends on the patience and faithfulness with + which the investigator applies to his hypothesis every possible kind of + verification. + </p> + <p> + I dare say I may have to return to this point by and by; but having dealt + thus far with our logical methods, I must now turn to something which, + perhaps, you may consider more interesting, or, at any rate, more + tangible. But in reality there are but few things that can be more + important for you to understand than the mental processes and the means by + which we obtain scientific conclusions and theories. [*] Having granted + that the inquiry is a proper one, and having determined on the nature of + the methods we are to pursue and which only can lead to success, I must + now turn to the consideration of our knowledge of the nature of the + processes which have resulted in the present condition of organic nature. + </p> + <ol class="footnotes"> + <li> + Those who wish to study fully the doctrines of which I have endeavoured + to give some rough-and-ready illustrations, must read Mr. John Stuart + Mill's <i>System of Logic</i>. + </li> + </ol> + <p> + Here, let me say at once, lest some of you misunderstand me, that I have + extremely little to report. The question of how the present condition of + organic nature came about, resolves itself into two questions. The first + is: How has organic or living matter commenced its existence? And the + second is: How has it been perpetuated? On the second question I shall + have more to say hereafter. But on the first one, what I now have to say + will be for the most part of a negative character. + </p> + <p> + If you consider what kind of evidence we can have upon this matter, it + will resolve itself into two kinds. We may have historical evidence and we + may have experimental evidence. It is, for example, conceivable, that + inasmuch as the hardened mud which forms a considerable portion of the + thickness of the earth's crust contains faithful records of the past forms + of life, and inasmuch as these differ more and more as we go further + down,--it is possible and conceivable that we might come to some + particular bed or stratum which should contain the remains of those + creatures with which organic life began upon the earth. And if we did so, + and if such forms of organic life were preservable, we should have what I + would call historical evidence of the mode in which organic life began + upon this planet. Many persons will tell you, and indeed you will find it + stated in many works on geology, that this has been done, and that we + really possess such a record; there are some who imagine that the earliest + forms of life of which we have as yet discovered any record, are in truth + the forms in which animal life began upon the globe. The grounds on which + they base that supposition are these:--That if you go through the enormous + thickness of the earth's crust and get down to the older rocks, the higher + vertebrate animals--the quadrupeds, birds, and fishes--cease to be found; + beneath them you find only the invertebrate animals; and in the deepest + and lowest rocks those remains become scantier and scantier, not in any + very gradual progression, however, until, at length, in what are supposed + to be the oldest rocks, the animal remains which are found are almost + always confined to four forms--<i>Oldhamia</i>, whose precise nature is + not known, whether plant or animal; <i>Lingula</i>, a kind of mollusc; <i>Trilobites</i>, + a crustacean animal, having the same essential plan of construction, + though differing in many details from a lobster or crab; and <i>Hymenocaris</i>, + which is also a crustacean. So that you have all the <i>Fauna</i> reduced, + at this period, to four forms: one a kind of animal or plant that we know + nothing about, and three undoubted animals--two crustaceans and one + mollusc. + </p> + <p> + I think, considering the organisation of these mollusca and crustacea, and + looking at their very complex nature, that it does indeed require a very + strong imagination to conceive that these were the first created of all + living things. And you must take into consideration the fact that we have + not the slightest proof that these which we call the oldest beds are + really so: I repeat, we have not the slightest proof of it. When you find + in some places that in an enormous thickness of rocks there are but very + scanty traces of life, or absolutely none at all; and that in other parts + of the world rocks of the very same formation are crowded with the records + of living forms, I think it is impossible to place any reliance on the + supposition, or to feel one's self justified in supposing that these are + the forms in which life first commenced. I have not time here to enter + upon the technical grounds upon which I am led to this conclusion,--that + could hardly be done properly in half a dozen lectures on that part + alone:--I must content myself with saying that I do not at all believe + that these are the oldest forms of life. + </p> + <p> + I turn to the experimental side to see what evidence we have there. To + enable us to say that we know anything about the experimental origination + of organisation and life, the investigator ought to be able to take + inorganic matters, such as carbonic acid, ammonia, water, and salines, in + any sort of inorganic combination, and be able to build them up into + protein matter, and then that protein matter ought to begin to live in an + organic form. That, nobody has done as yet, and I suspect it will be a + long while before anybody does do it. But the thing is by no means so + impossible as it looks; for the researches of modern chemistry have shown + us--I won't say the road towards it, but, if I may so say, they have shown + the finger-post pointing to the road that may lead to it. + </p> + <p> + It is not many years ago--and you must recollect that Organic Chemistry is + a young science, not above a couple of generations old, you must not + expect too much of it,--it is not many years ago since it was said to be + perfectly impossible to fabricate any organic compound; that is to say, + any non-mineral compound which is to be found in an organised being. It + remained so for a very long period; but it is now a considerable number of + years since a distinguished foreign chemist contrived to fabricate urea, a + substance of a very complex character, which forms one of the waste + products of animal structures. And of late years a number of other + compounds, such as butyric acid, and others, have been added to the list. + I need not tell you that chemistry is an enormous distance from the goal I + indicate; all I wish to point out to you is, that it is by no means safe + to say that that goal may not be reached one day. It may be that it is + impossible for us to produce the conditions requisite to the origination + of life; but we must speak modestly about the matter, and recollect that + Science has put her foot upon the bottom round of the ladder. Truly he + would be a bold man who would venture to predict where she will be fifty + years hence. + </p> + <p> + There is another inquiry which bears indirectly upon this question, and + upon which I must say a few words. You are all of you aware of the + phenomena of what is called spontaneous generation. Our forefathers, down + to the seventeenth century, or thereabouts, all imagined, in perfectly + good faith, that certain vegetable and animal forms gave birth, in the + process of their decomposition, to insect life. Thus, if you put a piece + of meat in the sun, and allowed it to putrefy, they conceived that the + grubs which soon began to appear were the result of the action of a power + of spontaneous generation which the meat contained. And they could give + you receipts for making various animal and vegetable preparations which + would produce particular kinds of animals. A very distinguished Italian + naturalist, named Redi, took up the question, at a time when everybody + believed in it; among others our own great Harvey, the discoverer of the + circulation of the blood. You will constantly find his name quoted, + however, as an opponent of the doctrine of spontaneous generation; but the + fact is, and you will see it if you will take the trouble to look into his + works, Harvey believed it as profoundly as any man of his time; but he + happened to enunciate a very curious proposition--that every living thing + came from an <i>egg</i>; he did not mean to use the word in the sense in + which we now employ it, he only meant to say that every living thing + originated in a little rounded particle of organised substance; and it is + from this circumstance, probably, that the notion of Harvey having opposed + the doctrine originated. Then came Redi, and he proceeded to upset the + doctrine in a very simple manner. He merely covered the piece of meat with + some very fine gauze, and then he exposed it to the same conditions. The + result of this was that no grubs or insects were produced; he proved that + the grubs originated from the insects who came and deposited their eggs in + the meat, and that they were hatched by the heat of the sun. By this kind + of inquiry he thoroughly upset the doctrine of spontaneous generation, for + his time at least. + </p> + <p> + Then came the discovery and application of the microscope to scientific + inquiries, which showed to naturalists that besides the organisms which + they already knew as living beings and plants, there were an immense + number of minute things which could be obtained apparently almost at will + from decaying vegetable and animal forms. Thus, if you took some ordinary + black pepper or some hay, and steeped it in water, you would find in the + course of a few days that the water had become impregnated with an immense + number of animalcules swimming about in all directions. From facts of this + kind naturalists were led to revive the theory of spontaneous generation. + They were headed here by an English naturalist,--Needham,--and afterwards + in France by the learned Buffon. They said that these things were + absolutely begotten in the water of the decaying substances out of which + the infusion was made. It did not matter whether you took animal or + vegetable matter, you had only to steep it in water and expose it, and you + would soon have plenty of animalcules. They made an hypothesis about this + which was a very fair one. They said, this matter of the animal world, or + of the higher plants, appears to be dead, but in reality it has a sort of + dim life about it, which, if it is placed under fair conditions, will + cause it to break up into the forms of these little animalcules, and they + will go through their lives in the same way as the animal or plant of + which they once formed a part. + </p> + <p> + The question now became very hotly debated. Spallanzani, an Italian + naturalist, took up opposite views to those of Needham and Buffon, and by + means of certain experiments he showed that it was quite possible to stop + the process by boiling the water, and closing the vessel in which it was + contained. "Oh!" said his opponents; "but what do you know you may be + doing when you heat the air over the water in this way? You may be + destroying some property of the air requisite for the spontaneous + generation of the animalcules." + </p> + <p> + However, Spallanzani's views were supposed to be upon the right side, and + those of the others fell into discredit; although the fact was that + Spallanzani had not made good his views. Well, then, the subject continued + to be revived from time to time, and experiments were made by several + persons; but these experiments were not altogether satisfactory. It was + found that if you put an infusion in which animalcules would appear if it + were exposed to the air into a vessel and boiled it, and then sealed up + the mouth of the vessel, so that no air, save such as had been heated to + 212°, could reach its contents, that then no animalcules would be + found; but if you took the same vessel and exposed the infusion to the + air, then you would get animalcules. Furthermore, it was found that if you + connected the mouth of the vessel with a red-hot tube in such a way that + the air would have to pass through the tube before reaching the infusion, + that then you would get no animalcules. Yet another thing was noticed: if + you took two flasks containing the same kind of infusion, and left one + entirely exposed to the air, and in the mouth of the other placed a ball + of cotton wool, so that the air would have to filter itself through it + before reaching the infusion, that then, although you might have plenty of + animalcules in the first flask, you would certainly obtain none from the + second. + </p> + <p> + These experiments, you see, all tended towards one conclusion--that the + infusoria were developed from little minute spores or eggs which were + constantly floating in the atmosphere, and which lose their power of + germination if subjected to heat. But one observer now made another + experiment, which seemed to go entirely the other way, and puzzled him + altogether. He took some of this boiled infusion that I have been speaking + of, and by the use of a mercurial bath--a kind of trough used in + laboratories--he deftly inverted a vessel containing the infusion into the + mercury, so that the latter reached a little beyond the level of the mouth + of the <i>inverted</i> vessel. You see that he thus had a quantity of the + infusion shut off from any possible communication with the outer air by + being inverted upon a bed of mercury. + </p> + <p> + He then prepared some pure oxygen and nitrogen gases, and passed them by + means of a tube going from the outside of the vessel, up through the + mercury into the infusion; so that he thus had it exposed to a perfectly + pure atmosphere of the same constituents as the external air. Of course, + he expected he would get no infusorial animalcules at all in that + infusion; but, to his great dismay and discomfiture, he found he almost + always did get them. + </p> + <p> + Furthermore, it has been found that experiments made in the manner + described above answer well with most infusions; but that if you fill the + vessel with boiled milk, and then stop the neck with cotton-wool, you <i>will</i> + have infusoria. So that yousee there were two experiments that brought you + to one kind of conclusion, and three to another; which was a most + unsatisfactory state of things to arrive at in a scientific inquiry. + </p> + <p> + Some few years after this, the question began to be very hotly discussed + in France. There was M. Pouchet, a professor at Rouen, a very learned man, + but certainly not a very rigid experimentalist. He published a number of + experiments of his own, some of which were very ingenious, to show that if + you went to work in a proper way, there was a truth in the doctrine of + spontaneous generation. Well, it was one of the most fortunate things in + the world that M. Pouchet took up this question, because it induced a + distinguished French chemist, M. Pasteur, to take up the question on the + other side; and he has certainly worked it out in the most perfect manner. + I am glad to say, too, that he has published his researches in time to + enable me to give you an account of them. He verified all the experiments + which I have just mentioned to you--and then finding those extraordinary + anomalies, as in the case of the mercury bath and the milk, he set himself + to work to discover their nature. In the case of milk he found it to be a + question of temperature. Milk in a fresh state is slightly alkaline; and + it is a very curious circumstance, but this very slight degree of + alkalinity seems to have the effect of preserving the organisms which fall + into it from the air from being destroyed at a temperature of 212°, + which is the boiling point. But if you raise the temperature 10° when + you boil it, the milk behaves like everything else; and if the air with + which it comes in contact, after being boiled at this temperature, is + passed through a red-hot tube, you will not get a trace of organisms. + </p> + <p> + He then turned his attention to the mercury bath, and found on examination + that the surface of the mercury was almost always covered with a very fine + dust. He found that even the mercury itself was positively full of organic + matters; that from being constantly exposed to the air, it had collected + an immense number of these infusorial organisms from the air. Well, under + these circumstances he felt that the case was quite clear, and that the + mercury was not what it had appeared to M. Schwann to be,--a bar to the + admission of these organisms; but that, in reality, it acted as a + reservoir from which the infusion was immediately supplied with the large + quantity that had so puzzled him. + </p> + <p> + But not content with explaining the experiments of others, M. Pasteur went + to work to satisfy himself completely. He said to himself: "If my view is + right, and if, in point of fact, all these appearances of spontaneous + generation are altogether due to the falling of minute germs suspended in + the atmosphere,--why, I ought not only to be able to show the germs, but I + ought to be able to catch and sow them, and produce the resulting + organisms." He, accordingly, constructed a very ingenious apparatus to + enable him to accomplish the trapping of the "<i>germ dust</i>" in the + air. He fixed in the window of his room a glass tube, in the centre of + which he had placed a ball of gun-cotton, which, as you all know, is + ordinary cotton-wool, which, from having been steeped in strong acid, is + converted into a substance of great explosive power. It is also soluble in + alcohol and ether. One end of the glass tube was, of course, open to the + external air; and at the other end of it he placed an aspirator, a + contrivance for causing a current of the external air to pass through the + tube. He kept this apparatus going for four-and-twenty hours, and then + removed the <i>dusted</i> gun-cotton, and dissolved it in alcohol and + ether. He then allowed this to stand for a few hours, and the result was, + that a very fine dust was gradually deposited at the bottom of it. That + dust, on being transferred to the stage of a microscope, was found to + contain an enormous number of starch grains. You know that the materials + of our food and the greater portion of plants are composed of starch, and + we are constantly making use of it in a variety of ways, so that there is + always a quantity of it suspended in the air. It is these starch grains + which form many of those bright specks that we see dancing in a ray of + light sometimes. But besides these, M. Pasteur found also an immense + number of other organic substances such as spores of fungi, which had been + floating about in the air and had got caged in this way. + </p> + <p> + He went farther, and said to himself, "If these really are the things that + give rise to the appearance of spontaneous generation, I ought to be able + to take a ball of this dusted gun-cotton and put it into one of my + vessels, containing that boiled infusion which has been kept away from the + air, and in which no infusoria are at present developed, and then, if I am + right, the introduction of this gun-cotton will give rise to organisms." + </p> + <p> + Accordingly, he took one of these vessels of infusion, which had been kept + eighteen months, without the least appearance of life in it, and by a most + ingenious contrivance, he managed to break it open and introduce such a + ball of gun-cotton, without allowing the infusion or the cotton ball to + come into contact with any air but that which had been subjected to a red + heat, and in twenty-four hours he had the satisfaction of finding all the + indications of what had been hitherto called spontaneous generation. He + had succeeded in catching the germs and developing organisms in the way ho + had anticipated. + </p> + <p> + It now struck him that the truth of his conclusions might be demonstrated + without all the apparatus he had employed. To do this, he took some + decaying animal or vegetable substance, such as urine, which is an + extremely decomposable substance, or the juice of yeast, or perhaps some + other artificial preparation, and filled a vessel having a long tubular + neck with it. He then boiled the liquid and bent that long neck into an S + shape or zig-zag, leaving it open at the end. The infusion then gave no + trace of any appearance of spontaneous generation, however long it might + be left, as all the germs in the air were deposited in the beginning of + the bent neck. He then cut the tube close to the vessel, and allowed the + ordinary air to have free and direct access; and the result of that was + the appearance of organisms in it, as soon as the infusion had been + allowed to stand long enough to allow of the growth of those it received + from the air, which was about forty-eight hours. The result of M. + Pasteur's experiments proved, therefore, in the most conclusive manner, + that all the appearances of spontaneous generation arose from nothing more + than the deposition of the germs of organisms which were constantly + floating in the air. + </p> + <p> + To this conclusion, however, the objection was made, that if that were the + cause, then the air would contain such an enormous number of these germs, + that it would be a continual fog. But M. Pasteur replied that they are not + there in anything like the number we might suppose, and that an + exaggerated view has been held on that subject; he showed that the chances + of animal or vegetable life appearing in infusions, depend entirely on the + conditions under which they are exposed. If they are exposed to the + ordinary atmosphere around us, why, of course, you may have organisms + appearing early. But, on the other hand, if they are exposed to air at a + great height, or in some very quiet cellar, you will often not find a + single trace of life. + </p> + <p> + So that M. Pasteur arrived at last at the clear and definite result, that + all these appearances are like the case of the worms in the piece of meat, + which was refuted by Redi, simply germs carried by the air and deposited + in the liquids in which they afterwards appear. For my own part, I + conceive that, with the particulars of M. Pasteur's experiments before us, + we cannot fail to arrive at his conclusions; and that the doctrine of + spontaneous generation has received a final <i>coup de grâce</i>. + </p> + <p> + You, of course, understand that all this in no way interferes with the <i>possibility</i> + of the fabrication of organic matters by the direct method to which I have + referred, remote as that possibility may be. + </p> + <h3> + IV. The Perpetuation Of Living Beings, Hereditary Transmission And + Variation + </h3> + <p> + The inquiry which we undertook, at our last meeting, into the state of our + knowledge of the causes of the phenomena of organic nature,--of the past + and of the present,--resolved itself into two subsidiary inquiries: the + first was, whether we know anything, either historically or + experimentally, of the mode of origin of living beings; the second + subsidiary inquiry was, whether, granting the origin, we know anything + about the perpetuation and modifications of the forms of organic beings. + The reply which I had to give to the first question was altogether + negative, and the chief result of my last lecture was, that, neither + historically nor experimentally, do we at present know anything whatsoever + about the origin of living forms. We saw that, historically, we are not + likely to know anything about it, although we may perhaps learn something + experimentally; but that at present we are an enormous distance from the + goal I indicated. + </p> + <p> + I now, then, take up the next question, What do we know of the + reproduction, the perpetuation, and the modifications of the forms of + living beings, supposing that we have put the question as to their + origination on one side, and have assumed that at present the causes of + their origination are beyond us, and that we know nothing about them? Upon + this question the state of our knowledge is extremely different; it is + exceedingly large: and, if not complete, our experience is certainly most + extensive. It would be impossible to lay it all before you, and the most I + can do, or need do to-night, is to take up the principal points and put + them before you with such prominence as may subserve the purposes of our + present argument. + </p> + <p> + The method of the perpetuation of organic beings is of two kinds,--the + non-sexual and the sexual. In the first the perpetuation takes place from + and by a particular act of an individual organism, which sometimes may not + be classed as belonging to any sex at all. In the second case, it is in + consequence of the mutual action and interaction of certain portions of + the organisms of usually two distinct individuals,--the male and the + female. The cases of non-sexual perpetuation are by no means so common as + the cases of sexual perpetuation; and they are by no means so common in + the animal as in the vegetable world. You are all probably familiar with + the fact, as a matter of experience, that you can propagate plants by + means of what are called "cuttings"; for example, that by taking a cutting + from a geranium plant, and rearing it properly, by supplying it with light + and warmth and nourishment from the earth, it grows up and takes the form + of its parent, having all the properties and peculiarities of the original + plant. + </p> + <p> + Sometimes this process, which the gardener performs artificially, takes + place naturally; that is to say, a little bulb, or portion of the plant, + detaches itself, drops off, and becomes capable of growing as a separate + thing. That is the case with many bulbous plants, which throw off in this + way secondary bulbs, which are lodged in the ground and become developed + into plants. This is a non-sexual process, and from it results the + repetition or reproduction of the form of the original being from which + the bulb proceeds. + </p> + <p> + Among animals the same thing takes place. Among the lower forms of animal + life, the infusorial animalculæ we have already spoken of throw off + certain portions, or break themselves up in various directions, sometimes + transversely or sometimes longitudinally; or they may give off buds, which + detach themselves and develop into their proper forms. There is the common + fresh-water polype, for instance, which multiplies itself in this way. + Just in the same way as the gardener is able to multiply and reproduce the + peculiarities and characters of particular plants by means of cuttings, so + can the physiological experimentalist--as was shown by the Abbé + Trembley many years ago--so can he do the same thing with many of the + lower forms of animal life. M. de Trembley showed that you could take a + polype and cut it into two, or four, or many pieces, mutilating it in all + directions, and the pieces would still grow up and reproduce completely + the original form of the animal. These are all cases of non-sexual + multiplication, and there are other instances, and still more + extraordinary ones, in which this process takes place naturally, in a more + hidden, a more recondite kind of way. You are all of you familiar with + that little green insect, the <i>Aphis</i> or blight, as it is called. + These little animals, during a very considerable part of their existence, + multiply themselves by means of a kind of internal budding, the buds being + developed into essentially non-sexual animals, which are neither male nor + female; they become converted into young <i>Aphides</i>, which repeat the + process, and their offspring after them, and so on again; you may go on + for nine or ten, or even twenty or more successions; and there is no very + good reason to say how soon it might terminate, or how long it might not + go on if the proper conditions of warmth and nourishment were kept up. + </p> + <p> + Sexual reproduction is quite a distinct matter. Here, in all these cases, + what is required is the detachment of two portions of the parental + organisms, which portions we know as the egg or the spermatozoon. In + plants it is the ovule and the pollen-grain, as in the flowering plants, + or the ovule and the antherozooid, as in the flowerless. Among all forms + of animal life, the spermatozoa proceed from the male sex, and the egg is + the product of the female. Now, what is remarkable about this mode of + reproduction is this, that the egg by itself, or the spermatozoa by + themselves, are unable to assume the parental form; but if they be brought + into contact with one another, the effect of the mixture of organic + substances proceeding from two sources appears to confer an altogether new + vigour to the mixed product. This process is brought about, as we all + know, by the sexual intercourse of the two sexes, and is called the act of + impregnation. The result of this act on the part of the male and female + is, that the formation of a new being is set up in the ovule or egg; this + ovule or egg soon begins to be divided and subdivided, and to be fashioned + into various complex organs, and eventually to develop into the form of + one of its parents, as I explained in the first lecture. These are the + processes by which the perpetuation of organic beings is secured. Why + there should be the two modes--why this re-invigoration should be required + on the part of the female element we do not know; but it is most assuredly + the fact, and it is presumable, that, however long the process of + non-sexual multiplication could be continued--I say there is good reason + to believe that it would come to an end if a new commencement were not + obtained by a conjunction of the two sexual elements. + </p> + <p> + That character which is common to these two distinct processes is this, + that, whether we consider the reproduction, or perpetuation, or + modification of organic beings as they take place non-sexually, or as they + may take place sexually--in either case, I say, the offspring has a + constant tendency to assume, speaking generally, the character of the + parent. As I said just now, if you take a slip of a plant, and tend it + with care, it will eventually grow up and develop into a plant like that + from which it had sprung; and this tendency is so strong that, as + gardeners know, this mode of multiplying by means of cuttings is the only + secure mode of propagating very many varieties of plants; the peculiarity + of the primitive stock seems to be better preserved if you propagate it by + means of a slip than if you resort to the sexual mode. + </p> + <p> + Again, in experiments upon the lower animals, such as the polype, to which + I have referred, it is most extraordinary that, although cut up into + various pieces, each particular piece will grow up into the form of the + primitive stock; the head, if separated, will reproduce the body and the + tail; and if you cut off the tail, you will find that that will reproduce + the body and all the rest of the members, without in any way deviating + from the plan of the organism from which these portions have been + detached. And so far does this go, that some experimentalists have + carefully examined the lower orders of animals,--among them the Abbé + Spallanzani, who made a number of experiments upon snails and + salamanders,--and have found that they might mutilate them to an + incredible extent; that you might cut off the jaw or the greater part of + the head, or the leg or the tail, and repeat the experiment several times, + perhaps cutting off the same member again and again; and yet each of those + types would be reproduced according to the primitive type: Nature making + no mistake, never putting on a fresh kind of leg, or head, or tail, but + always tending to repeat and to return to the primitive type. + </p> + <p> + It is the same in sexual reproduction: it is a matter of perfectly common + experience, that the tendency on the part of the offspring always is, + speaking broadly, to reproduce the form of the parents. The proverb has it + that the thistle does not bring forth grapes; so, among ourselves, there + is always a likeness, more or less marked and distinct, between children + and their parents. That is a matter of familiar and ordinary observation. + We notice the same thing occurring in the cases of the domestic + animals--dogs, for instance, and their offspring. In all these cases of + propagation and perpetuation, there seems to be a tendency in the + offspring to take the characters of the parental organisms. To that + tendency a special name is given--and as I may very often use it, I will + write it up here on this black-board that you may remember it--it is + called <i>Atavism</i>; it expresses this tendency to revert to the + ancestral type, and comes from the Latin word <i>atavus</i>, ancestor. + </p> + <p> + Well, this <i>Atavism</i> which I shall speak of, is, as I said before, + one of the most marked and striking tendencies of organic beings; but, + side by side with this hereditary tendency there is an equally distinct + and remarkable tendency to variation. The tendency to reproduce the + original stock has, as it were, its limits, and side by side with it there + is a tendency to vary in certain directions, as if there were two opposing + powers working upon the organic being, one tending to take it in a + straight line, and the other tending to make it diverge from that straight + line, first to one side and then to the other. + </p> + <p> + So that you see these two tendencies need not precisely contradict one + another, as the ultimate result may not always be very remote from what + would have been the case if the line had been quite straight. + </p> + <p> + This tendency to variation is less marked in that mode of propagation + which takes place non-sexually; it is in that mode that the minor + characters of animal and vegetable structures are most completely + preserved. Still, it will happen sometimes, that the gardener, when he has + planted a cutting of some favourite plant, will find, contrary to his + expectation, that the slip grows up a little different from the primitive + stock--that it produces flowers of a different colour or make, or some + deviation in one way or another. This is what is called the "sporting" of + plants. + </p> + <p> + In animals the phenomena of non-sexual propagation are so obscure, that at + present we cannot be said to know much about them; but if we turn to that + mode of perpetuation which results from the sexual process, then we find + variation a perfectly constant occurrence, to a certain extent; and, + indeed, I think that a certain amount of variation from the primitive + stock is the necessary result of the method of sexual propagation itself; + for, inasmuch as the thing propagated proceeds from two organisms of + different sexes and different makes and temperaments, and as the offspring + is to be either of one sex or the other, it is quite clear that it cannot + be an exact diagonal of the two, or it would be of no sex at all; it + cannot be an exact intermediate form between that of each of its + parents--it must deviate to one side or the other. You do not find that + the male follows the precise type of the male parent, nor does the female + always inherit the precise characteristics of the mother,--there is always + a proportion of the female character in the male offspring, and of the + male character in the female offspring. That must be quite plain to all of + you who have looked at all attentively on your own children or those of + your neighbours; you will have noticed how very often it may happen that + the son shall exhibit the maternal type of character, or the daughter + possess the characteristics of the father's family. There are all sorts of + intermixtures and intermediate conditions between the two, where + complexion, or beauty, or fifty other different peculiarities belonging to + either side of the house, are reproduced in other members of the same + family. Indeed, it is sometimes to be remarked in this kind of variation, + that the variety belongs, strictly speaking, to neither of the immediate + parents; you will see a child in a family who is not like either its + father or its mother; but some old person who knew its grandfather or + grandmother, or, it may be, an uncle, or, perhaps, even a more distant + relative will see a great similarity between the child and one of these. + In this way it constantly happens that the characteristic of some previous + member of the family comes out and is reproduced and recognised in the + most unexpected manner. + </p> + <p> + But apart from that matter of general experience, there are some cases + which put that curious mixture in a very clear light. You are aware that + the offspring of the ass and the horse, or rather of the he-ass and the + mare, is what is called a mule; and, on the other hand, the offspring of + the stallion and the she-ass is what is called a hinny. It is a very rare + thing in this country to see a hinny. I never saw one myself; but they + have been very carefully studied. Now, the curious thing is this, that + although you have the same elements in the experiment in each case, the + offspring is entirely different in character, according as the male + influence comes from the ass or the horse. Where the ass is the male, as + in the case of the mule, you find that the head is like that of the ass, + that the ears are long, the tail is tufted at the end, the feet are small, + and the voice is an unmistakable bray; these are all points of similarity + to the ass; but, on the other hand, the barrel of the body and the cut of + the neck are much more like those of the mare. Then, if you look at the + hinny,--the result of the union of the stallion and the she-ass, then you + find it is the horse that has the predominance; that the head is more like + that of the horse, the ears are shorter, the legs coarser, and the type is + altogether altered; while the voice, instead of being a bray, is the + ordinary neigh of the horse. Here, you see, is a most curious thing: you + take exactly the same elements, ass and horse, but you combine the sexes + in a different manner, and the result is modified accordingly. You have in + this case, however, a result which is not general and universal--there is + usually an important preponderance, but not always on the same side. + </p> + <p> + Here, then, is one intelligible, and, perhaps, necessary cause of + variation: the fact, that there are two sexes sharing in the production of + the offspring, and that the share taken by each is different and variable, + not only for each combination, but also for different members of the same + family. + </p> + <p> + Secondly, there is a variation, to a certain extent--though, in all + probability, the influence of this cause has been very much + exaggerated--but there is no doubt that variation is produced, to a + certain extent, by what are commonly known as external conditions,--such + as temperature, food, warmth, and moisture. In the long run, every + variation depends, in some sense, upon external conditions, seeing that + everything has a cause of its own. I use the term "external conditions" + now in the sense in which it is ordinarily employed: certain it is, that + external conditions have a definite effect. You may take a plant which has + single flowers, and by dealing with the soil, and nourishment, and so on, + you may by and by convert single flowers into double flowers, and make + thorns shoot out into branches. You may thicken or make various + modifications in the shape of the fruit. In animals, too, you may produce + analogous changes in this way, as in the case of that deep bronze colour + which persons rarely lose after having passed any length of time in + tropical countries. You may also alter the development of the muscles very + much, by dint of training; all the world knows that exercise has a great + effect in this way; we always expect to find the arm of a blacksmith hard + and wiry, and possessing a large development of the brachial muscles. No + doubt training, which is one of the forms of external conditions, converts + what are originally only instructions, teachings, into habits, or, in + other words, into organisations, to a great extent; but this second cause + of variation cannot be considered to be by any means a large one. The + third cause that I have to mention, however, is a very extensive one. It + is one that, for want of a better name, has been called "spontaneous + variation"; which means that when we do not know anything about the cause + of phenomena, we call it spontaneous. In the orderly chain of causes and + effects in this world, there are very few things of which it can be said + with truth that they are spontaneous. Certainly not in these physical + matters--in these there is nothing of the kind--everything depends on + previous conditions. But when we cannot trace the cause of phenomena, we + call them spontaneous. + </p> + <p> + Of these variations, multitudinous as they are, but little is known with + perfect accuracy. I will mention to you some two or three cases, because + they are very remarkable in themselves, and also because I shall want to + use them afterwards. Réaumur, a famous French naturalist, a great + many years ago, in an essay which he wrote upon the art of hatching + chickens--which was indeed a very curious essay--had occasion to speak of + variations and monstrosities. One very remarkable case had come under his + notice of a variation in the form of a human member, in the person of a + Maltese, of the name of Gratio Kelleia, who was born with six fingers upon + each hand, and the like number of toes to each of his feet. That was a + case of spontaneous variation. Nobody knows why he was born with that + number of fingers and toes, and as we don't know, we call it a case of + "spontaneous" variation. There is another remarkable case also. I select + these, because they happen to have been observed and noted very carefully + at the time. It frequently happens that a variation occurs, but the + persons who notice it do not take any care in noting down the particulars, + until at length, when inquiries come to be made, the exact circumstances + are forgotten; and hence, multitudinous as may be such "spontaneous" + variations, it is exceedingly difficult to get at the origin of them. + </p> + <p> + The second case is one of which you may find the whole details in the + "Philosophical Transactions" for the year 1813, in a paper communicated by + Colonel Humphrey to the President of the Royal Society--"On a new Variety + in the Breed of Sheep," giving an account of a very remarkable breed of + sheep, which at one time was well known in the northern states of America, + and which went by the name of the Ancon or the Otter breed of sheep. In + the year 1791, there was a farmer of the name of Seth Wright in + Massachusetts, who had a flock of sheep, consisting of a ram and, I think, + of some twelve or thirteen ewes. Of this flock of ewes, one at the + breeding-time bore a lamb which was very singularly formed; it had a very + long body, very short legs, and those legs were bowed. I will tell you by + and by how this singular variation in the breed of sheep came to be noted, + and to have the prominence that it now has. For the present, I mention + only these two cases; but the extent of variation in the breed of animals + is perfectly obvious to any one who has studied natural history with + ordinary attention, or to any person who compares animals with others of + the same kind. It is strictly true that there are never any two specimens + which are exactly alike; however similar, they will always differ in some + certain particular. + </p> + <p> + Now let us go back to Atavism--to the hereditary tendency I spoke of. What + will come of a variation when you breed from it, when Atavism comes, if I + may say so, to intersect variation? The two cases of which I have + mentioned the history give a most excellent illustration of what occurs. + Gratio Kelleia, the Maltese, married when he was twenty-two years of age, + and, as I suppose there were no six-fingered ladies in Malta, he married + an ordinary five-fingered person. The result of that marriage was four + children; the first, who was christened Salvator, had six fingers and six + toes, like his father; the second was George, who had five fingers and + toes, but one of them was deformed, showing a tendency to variation; the + third was Andrè; he had five fingers and five toes, quite perfect; + the fourth was a girl, Marie; she had five fingers and five toes, but her + thumbs were deformed, showing a tendency toward the sixth. + </p> + <p> + These children grew up, and when they came to adult years, they all + married, and of course it happened that they all married five-fingered and + five-toed persons. Now let us see what were the results. Salvator had four + children; they were two boys, a girl, and another boy; the first two boys + and the girl were six-fingered and six-toed like their grandfather; the + fourth boy had only five fingers and five toes. George had only four + children; there were two girls with six fingers and six toes; there was + one girl with six fingers and five toes on the right side, and five + fingers and five toes on the left side, so that she was half and half. The + last, a boy, had five fingers and five toes. The third, Andrè, you + will recollect, was perfectly well-formed, and he had many children whose + hands and feet were all regularly developed. Marie, the last, who, of + course, married a man who had only five fingers, had four children; the + first, a boy, was born with six toes, but the other three were normal. + </p> + <p> + Now observe what very extraordinary phenomena are presented here. You have + an accidental variation giving rise to what you may call a monstrosity; + you have that monstrosity or variation diluted in the first instance by an + admixture with a female of normal construction, and you would naturally + expect that, in the results of such an union, the monstrosity, if + repeated, would be in equal proportion with the normal type; that is to + say, that the children would be half and half, some taking the peculiarity + of the father, and the others being of the purely normal type of the + mother; but you see we have a great preponderance of the abnormal type. + Well, this comes to be mixed once more with the pure, the normal type, and + the abnormal is again produced in large proportion, notwithstanding the + second dilution. Now what would have happened if these abnormal types had + intermarried with each other; that is to say, suppose the two boys of + Salvator had taken it into their heads to marry their first cousins, the + two first girls of George, their uncle? You will remember that these are + all of the abnormal type of their grandfather. The result would probably + have been, that their offspring would have been in every case a further + development of that abnormal type. You see it is only in the fourth, in + the person of Marie, that the tendency, when it appears but slightly in + the second generation, is washed out in the third, while the progeny of + Andrè, who escaped in the first instance, escape altogether. + </p> + <p> + We have in this case a good example of nature's tendency to the + perpetuation of a variation. Here it is certainly a variation which earned + with it no use or benefit; and yet you see the tendency to perpetuation + may be so strong, that, notwithstanding a great admixture of pure blood, + the variety continues itself up to the third generation, which is largely + marked with it. In this case, as I have said, there was no means of the + second generation intermarrying with any but five-fingered persons, and + the question naturally suggests itself, What would have been the result of + such marriage? Réaumur narrates this case only as far as the third + generation. Certainly it would have been an exceedingly curious thing if + we could have traced this matter any further; had the cousins + intermarried, a six-fingered variety of the human race might have been set + up. + </p> + <p> + To show you that this supposition is by no means an unreasonable one, let + me now point out what took place in the case of Seth Wright's sheep, where + it happened to be a matter of moment to him to obtain a breed or raise a + flock of sheep like that accidental variety that I have described--and I + will tell you why. In that part of Massachusetts where Seth Wright was + living, the fields were separated by fences, and the sheep, which were + very active and robust, would roam abroad, and without much difficulty + jump over these fences into other people's farms. As a matter of course, + this exuberant activity on the part of the sheep constantly gave rise to + all sorts of quarrels, bickerings, and contentions among the farmers of + the neighbourhood; so it occurred to Seth Wright, who was, like his + successors, more or less 'cute, that if he could get a stock of sheep like + those with the bandy legs, they would not be able to jump over the fences + so readily; and he acted upon that idea. He killed his old ram, and as + soon as the young one arrived at maturity, he bred altogether from it. The + result was even more striking than in the human experiment which I + mentioned just now. Colonel Humphreys testifies that it always happened + that the offspring were either pure Ancons or pure ordinary sheep; that in + no case was there any mixing of the Ancons with the others. In consequence + of this, in the course of a very few years, the farmer was able to get a + very considerable flock of this variety, and a large number of them were + spread throughout Massachusetts. Most unfortunately, however--I suppose it + was because they were so common--nobody took enough notice of them to + preserve their skeletons; and although Colonel Humphreys states that he + sent a skeleton to the President of the Royal Society at the same time + that he forwarded his paper, I am afraid that the variety has entirely + disappeared; for a short time after these sheep had become prevalent in + that district, the Merino sheep were introduced; and as their wool was + much more valuable, and as they were a quiet race of sheep, and showed no + tendency to trespasser jump over fences, the Otter breed of sheep, the + wool of which was inferior to that of the Merino, was gradually allowed to + die out. + </p> + <p> + You see that these facts illustrate perfectly well what may be done if you + take care to breed from stocks that are similar to each other. After + having got a variation, if, by crossing a variation with the original + stock, you multiply that variation, and then take care to keep that + variation distinct from the original stock, and make them breed + together,--then you may almost certainly produce a race whose tendency to + continue the variation is exceedingly strong. + </p> + <p> + This is what is called "selection"; and it is by exactly the same process + as that by which Seth Wright bred his Ancon sheep, that our breeds of + cattle, dogs, and fowls are obtained. There are some possibilities of + exception, but still, speaking broadly, I may say that this is the way in + which all our varied races of domestic animals have arisen; and you must + understand that it is not one peculiarity or one characteristic alone in + which animals may vary. There is not a single peculiarity or + characteristic of any kind, bodily or mental, in which offspring may not + vary to a certain extent from the parent and other animals. + </p> + <p> + Among ourselves this is well known. The simplest physical peculiarity is + mostly reproduced. I know a case of a woman who has the lobe of one of her + ears a little flattened. An ordinary observer might scarcely notice it, + and yet every one of her children has an approximation to the same + peculiarity to some extent. If you look at the other extreme, too, the + gravest diseases, such as gout, scrofula, and consumption, may be handed + down with just the same certainty and persistence as we noticed in the + perpetuation of the bandy legs of the Ancon sheep. + </p> + <p> + However, these facts are best illustrated in animals, and the extent of + the variation, as is well known, is very remarkable in dogs. For example, + there are some dogs very much smaller than others; indeed, the variation + is so enormous that probably the smallest dog would be about the size of + the head of the largest; there are very great variations in the structural + forms not only of the skeleton but also in the shape of the skull, and in + the proportions of the face and the disposition of the teeth. + </p> + <p> + The Pointer, the Retriever, Bulldog, and the Terrier differ very greatly, + and yet there is every reason to believe that every one of these races has + arisen from the same source,--that all the most important races have + arisen by this selective breeding from accidental variation. + </p> + <p> + A still more striking case of what may be done by selective breeding, and + it is a better case, because there is no chance of that partial infusion + of error to which I alluded, has been studied very carefully by Mr. + Darwin,--the case of the domestic pigeons. I dare say there may be some + among you who may be pigeon <i>fanciers</i>, and I wish you to understand + that in approaching the subject, I would speak with all humility and + hesitation, as I regret to say that I am not a pigeon fancier. I know it + is a great art and mystery, and a thing upon which a man must not speak + lightly; but I shall endeavour, as far as my understanding goes, to give + you a summary of the published and unpublished information which I have + gained from Mr. Darwin. + </p> + <p> + Among the enormous variety,--I believe there are somewhere about a hundred + and fifty kinds of pigeons,--there are four kinds which may be selected as + representing the extremest divergences of one kind from another. Their + names are the Carrier, the Pouter, the Fantail, and the Tumbler. In these + large diagrams that I have here they are each represented in their + relative sizes to each other. This first one is the Carrier; you will + notice this large excrescence on its beak; it has a comparatively small + head; there is a bare space round the eyes; it has a long neck, a very + long beak, very strong legs, large feet, long wings, and so on. The second + one is the Pouter, a very large bird, with very long legs and beak. It is + called the Pouter because it is in the habit of causing its gullet to + swell up by inflating it with air. I should tell you that all pigeons have + a tendency to do this at times, but in the Pouter it is carried to an + enormous extent. The birds appear to be quite proud of their power of + swelling and puffing themselves out in this way; and I think it is about + as droll a sight as you can well see to look at a cage full of these + pigeons puffing and blowing themselves out in this ridiculous manner. + </p> + <p> + This diagram is a representation of the third kind I mentioned--the + Fantail. It is, you see, a small bird, with exceedingly small legs and a + very small beak. It is most curiously distinguished by the size and extent + of its tail, which, instead of containing twelve feathers, may have many + more,--say thirty, or even more--I believe there are some with as many as + forty-two. This bird has a curious habit of spreading out the feathers of + its tail in such a way that they reach forward and touch its head; and if + this can be accomplished, I believe it is looked upon as a point of great + beauty. + </p> + <p> + But here is the last great variety,--the Tumbler; and of that great + variety, one of the principal kinds, and one most prized, is the specimen + represented here--the short-faced Tumbler. Its beak, you see, is reduced + to a mere nothing. Just compare the beak of this one and that of the first + one, the Carrier--I believe the orthodox comparison of the head and beak + of a thoroughly well-bred Tumbler is to stick an oat into a cherry, and + that will give you the proper relative proportions of the beak and head. + The feet and legs are exceedingly small, and the bird appears to be quite + a dwarf when placed side by side with this great Carrier. + </p> + <p> + These are differences enough in regard to their external appearance; but + these differences are by no means the whole or even the most important of + the differences which obtain between these birds. There is hardly a single + point of their structure which has not become more or less altered; and to + give you an idea of how extensive these alterations are, I have here some + very good skeletons, for which I am indebted to my friend, Mr. Tegetmeier, + a great authority in these matters; by means of which, if you examine them + by and by, you will be able to see the enormous difference in their bony + structures. + </p> + <p> + I had the privilege, some time ago, of access to some important MSS. of + Mr. Darwin, who, I may tell you, has taken very great pains and spent much + valuable time and attention on the investigation of these variations, and + getting together all the facts that bear upon them. I obtained from these + MSS. the following summary of the differences between the domestic breeds + of pigeons; that is to say, a notification of the various points in which + their organisation differs. In the first place, the back of the skull may + differ a good deal, and the development of the bones of the face may vary + a great deal; the back varies a good deal; the shape of the lower jaw + varies; the tongue varies very greatly, not only in correlation to the + length and size of the beak, but it seems also to have a kind of + independent variation of its own. Then the amount of naked skin round the + eyes, and at the base of the beak, may vary enormously; so may the length + of the eyelids, the shape of the nostrils, and the length of the neck. I + have already noticed the habit of blowing out the gullet, so remarkable in + the Pouter, and comparatively so in the others. There are great + differences, too, in the size of the female and the male, the shape of the + body, the number and width of the processes of the ribs, the development + of the ribs, and the size, shape, and development of the breastbone. We + may notice, too--and I mention the fact because it has been disputed by + what is assumed to be high authority,--the variation in the number of the + sacral vertebrae. The number of these varies from eleven to fourteen, and + that without any diminution in the number of the vertebrae of the back or + of the tail. Then the number and position of the tail-feathers may vary + enormously, and so may the number of the primary and secondary feathers of + the wings. Again, the length of the feet and of the beak,--although they + have no relation to each other, yet appear to go together,--that is, you + have a long beak wherever you have long feet. There are differences also + in the periods of the acquirement of the perfect plumage--the size and + shape of the eggs--the nature of flight, and the powers of + flight--so-called "<i>homing</i>" birds having enormous flying powers; [*] + while, on the other hand, the little Tumbler is so called because of its + extraordinary faculty of turning head over heels in the air, instead of + pursuing a direct course. And, lastly, the dispositions and voices of the + birds may vary. Thus the case of the pigeons shows you that there is + hardly a single particular--whether of instinct, or habit, or bony + structure, or of plumage--of either the internal economy or the external + shape, in which some variation or change may not take place, which, by + selective breeding, may become perpetuated, and form the foundation of, + and give rise to, a new race. + </p> + <ol class="footnotes"> + <li> + The "<i>Carrier</i>", I learn from Mr. Tegetmeier, does not <i>carry</i>; + a high-bred bird of this breed being but a poor flier. The birds which + fly long distances, and come home--"homing" birds-and are consequently + used as carriers, are not "carriers" in the fancy sense. + </li> + </ol> + <p> + If you carry in your mind's eye these four varieties of pigeons, you will + bear with you as good a notion as you can have, perhaps, of the enormous + extent to which a deviation from a primitive type may be carried by means + of this process of selective breeding. + </p> + <h3> + V. The Conditions Of Existence As Affecting The Perpetuation Of Living + Beings + </h3> + <p> + In the last Lecture I endeavoured to prove to you that, while, as a + general rule, organic beings tend to reproduce their kind, there is in + them, also, a constantly recurring tendency to vary--to vary to a greater + or to a less extent. Such a variety, I pointed out to you, might arise + from causes which we do not understand; we therefore called it + spontaneous; and it might come into existence as a definite and marked + thing, without any gradations between itself and the form which preceded + it. I further pointed out, that such a variety having once arisen, might + be perpetuated to some extent, and indeed to a very marked extent, without + any direct interference, or without any exercise of that process which we + called selection. And then I stated further, that by such selection, when + exercised artificially--if you took care to breed only from those forms + which presented the same peculiarities of any variety which had arisen in + this manner--the variation might be perpetuated, as far as we can see, + indefinitely. + </p> + <p> + The next question, and it is an important one for us, is this: Is there + any limit to the amount of variation from the primitive stock which can be + produced by this process of selective breeding? In considering this + question, it will be useful to class the characteristics, in respect of + which organic beings vary, under two heads: we may consider structural + characteristics, and we may consider physiological characteristics. + </p> + <p> + In the first place, as regards structural characteristics, I endeavoured + to show you, by the skeletons which I had upon the table, and by reference + to a great many well-ascertained facts, that the different breeds of + Pigeons, the Carriers, Pouters, and Tumblers, might vary in any of their + internal and important structural characters to a very great degree; not + only might there be changes in the proportions of the skull, and the + characters of the feet and beaks, and so on; but that there might be an + absolute difference in the number of the vertebrae of the back, as in the + sacral vertebras of the Pouter; and so great is the extent of the + variation in these and similar characters that I pointed out to you, by + reference to the skeletons and the diagrams, that these extreme varieties + may absolutely differ more from one another in their structural characters + than do what naturalists call distinct SPECIES of pigeons; that is to say, + that they differ so much in structure that there is a greater difference + between the Pouter and the Tumbler than there is between such wild and + distinct forms as the Rock Pigeon or the Ring Pigeon, or the Ring Pigeon + and the Stock Dove; and indeed the differences are of greater value than + this, for the structural differences between these domesticated pigeons + are such as would be admitted by a naturalist, supposing he knew nothing + at all about their origin, to entitle them to constitute even distinct + genera. + </p> + <p> + As I have used this term SPECIES, and shall probably use it a good deal, I + had better perhaps devote a word or two to explaining what I mean by it. + </p> + <p> + Animals and plants are divided into groups, which become gradually + smaller, beginning with a KINGDOM, which is divided into SUB-KINGDOMS; + then come the smaller divisions called PROVINCES; and so on from a + PROVINCE to a CLASS, from a CLASS to an ORDER, from ORDERS to FAMILIES, + and from these to GENERA, until we come at length to the smallest groups + of animals which can be defined one from the other by constant characters, + which are not sexual; and these are what naturalists call SPECIES in + practice, whatever they may do in theory. + </p> + <p> + If, in a state of nature, you find any two groups of living beings, which + are separated one from the other by some constantly-recurring + characteristic, I don't care how slight and trivial, so long as it is + defined and constant, and does not depend on sexual peculiarities, then + all naturalists agree in calling them two species; that is what is meant + by the use of the word species--that is to say, it is, for the practical + naturalist, a mere question of structural differences. [*] We have seen + now--to repeat this point once more, and it is very essential that we + should rightly understand it--we have seen that breeds, known to have been + derived from a common stock by selection, may be as different in their + structure from the original stock as species may be distinct from each + other. + </p> + <ol class="footnotes"> + <li> + I lay stress here on the <i>practical</i> signification of "Species." + Whether a physiological test between species exist or not, it is hardly + ever applicable by the practical naturalist. + </li> + </ol> + <p> + But is the like true of the physiological characteristics of animals? Do + the physiological differences of varieties amount in degree to those + observed between forms which naturalists call distinct species? This is a + most important point for us to consider. + </p> + <p> + As regards the great majority of physiological characteristics, there is + no doubt that they are capable of being developed, increased, and modified + by selection. + </p> + <p> + There is no doubt that breeds may be made as different as species in many + physiological characters. I have already pointed out to you very briefly + the different habits of the breeds of Pigeons, all of which depend upon + their physiological peculiarities--as the peculiar habit of tumbling, in + the Tumbler--the peculiarities of flight, in the "homing" birds--the + strange habit of spreading out the tail, and walking in a peculiar + fashion, in the Fantail--and, lastly, the habit of blowing out the gullet, + so characteristic of the Pouter. These are all due to physiological + modifications, and in all these respects these birds differ as much from + each other as any two ordinary species do. + </p> + <p> + So with Dogs in their habits and instincts. It is a physiological + peculiarity which leads the Greyhound to chase its prey by sight--that + enables the Beagle to track it by the scent--that impels the Terrier to + its rat-hunting propensity--and that leads the Retriever to its habit of + retrieving. These habits and instincts are all the results of + physiological differences and peculiarities, which have been developed + from a common stock, at least there is every reason to believe so. But it + is a most singular circumstance, that while you may run through almost the + whole series of physiological processes, without finding a check to your + argument, you come at last to a point where you do find a check, and that + is in the reproductive processes. For there is a most singular + circumstance in respect to natural species--at least about some of + them--and it would be sufficient for the purposes of this argument if it + were true of only one of them, but there is, in fact, a great number of + such cases--and that is, that, similar as they may appear to be to mere + races or breeds, they present a marked peculiarity in the reproductive + process. If you breed from the male and female of the same race, you of + course have offspring of the like kind, and if you make the offspring + breed together, you obtain the same result, and if you breed from these + again, you will still have the same kind of offspring; there is no check. + But if you take members of two distinct species, however similar they may + be to each other, and make them breed together, you will find a check, + with some modifications and exceptions, however, which I shall speak of + presently. If you cross two such species with each other, then--although + you may get offspring in the case of the first cross, yet, if you attempt + to breed from the products of that crossing, which are what are called + HYBRIDS--that is, if you couple a male and a female hybrid--then the + result is that in ninety-nine cases out of a hundred you will get no + offspring at all; there will be no result whatsoever. + </p> + <p> + The reason of this is quite obvious in some cases; the male hybrids, + although possessing all the external appearances and characteristics of + perfect animals, are physiologically imperfect and deficient in the + structural parts of the reproductive elements necessary to generation. It + is said to be invariably the case with the male mule, the cross between + the Ass and the Mare; and hence it is, that, although crossing the Horse + with the Ass is easy enough, and is constantly done, as far as I am aware, + if you take two mules, a male and a female, and endeavour to breed from + them, you get no offspring whatever; no generation will take place. This + is what is called the sterility of the hybrids between two distinct + species. + </p> + <p> + You see that this is a very extraordinary circumstance; one does not see + why it should be. The common teleological explanation is, that it is to + prevent the impurity of the blood resulting from the crossing of one + species with another, but you see it does not in reality do anything of + the kind. There is nothing in this fact that hybrids cannot breed with + each other, to establish such a theory; there is nothing to prevent the + Horse breeding with the Ass, or the Ass with the Horse. So that this + explanation breaks down, as a great many explanations of this kind do, + that are only founded on mere assumptions. + </p> + <p> + Thus you see that there is a great difference between "mongrels," which + are crosses between distinct races, and "hybrids," which are crosses + between distinct species. The mongrels are, so far as we know, fertile + with one another. But between species, in many cases, you cannot succeed + in obtaining even the first cross; at any rate it is quite certain that + the hybrids are often absolutely infertile one with another. + </p> + <p> + Here is a feature, then, great or small as it may be, which distinguishes + natural species of animals. Can we find any approximation to this in the + different races known to be produced by selective breeding from a common + stock? Up to the present time the answer to that question is absolutely a + negative one. As far as we know at present, there is nothing approximating + to this check. In crossing the breeds between the Fantail and the Pouter, + the Carrier and the Tumbler, or any other variety or race you may name--so + far as we know at present--there is no difficulty in breeding together the + mongrels. Take the Carrier and the Fantail, for instance, and let them + represent the Horse and the Ass in the case of distinct species; then you + have, as the result of their breeding, the Carrier-Fantail mongrel,--we + will say the male and female mongrel,--and, as far as we know, these two + when crossed would not be less fertile than the original cross, or than + Carrier with Carrier. Here, you see, is a physiological contrast between + the races produced by selective modification and natural species. I shall + inquire into the value of this fact, and of some modifying circumstances + by and by; for the present I merely put it broadly before you. + </p> + <p> + But while considering this question of the limitations of species, a word + must be said about what is called RECURRENCE--the tendency of races which + have been developed by selective breeding from varieties to return to + their primitive type. This is supposed by many to put an absolute limit to + the extent of selective and all other variations. People say, "It is all + very well to talk about producing these different races, but you know very + well that if you turned all these birds wild, these Pouters, and Carriers, + and so on, they would all return to their primitive stock." This is very + commonly assumed to be a fact, and it is an argument that is commonly + brought forward as conclusive; but if you will take the trouble to inquire + into it rather closely, I think you will find that it is not worth very + much. The first question of course is, Do they thus return to the + primitive stock? And commonly as the thing is assumed and accepted, it is + extremely difficult to get anything like good evidence of it. It is + constantly said, for example, that if domesticated Horses are turned wild, + as they have been in some parts of Asia Minor and South America, that they + return at once to the primitive stock from which they were bred. But the + first answer that you make to this assumption is, to ask who knows what + the primitive stock was; and the second answer is, that in that case the + wild Horses of Asia Minor ought to be exactly like the wild Horses of + South America. If they are both like the same thing, they ought manifestly + to be like each other! The best authorities, however, tell you that it is + quite different. The wild Horse of Asia is said to be of a dun colour, + with a largish head, and a great many other peculiarities; while the best + authorities on the wild Horses of South America tell you that there is no + similarity between their wild Horses and those of Asia Minor; the cut of + their heads is very different, and they are commonly chestnut or + bay-coloured. It is quite clear, therefore, that as by these facts there + ought to have been two primitive stocks, they go for nothing in support of + the assumption that races recur to one primitive stock, and so far as this + evidence is concerned, it falls to the ground. + </p> + <p> + Suppose for a moment that it were so, and that domesticated races, when + turned wild, did return to some common condition, I cannot see that this + would prove much more than that similar conditions are likely to produce + similar results; and that when you take back domesticated animals into + what we call natural conditions, you do exactly the same thing as if you + carefully undid all the work you had gone through, for the purpose of + bringing the animal from its wild to its domesticated state. I do not see + anything very wonderful in the fact, if it took all that trouble to get it + from a wild state, that it should go back into its original state as soon + as you removed the conditions which produced the variation to the + domesticated form. There is an important fact, however, forcibly brought + forward by Mr. Darwin, which has been noticed in connection with the + breeding of domesticated pigeons; and it is, that however different these + breeds of pigeons may be from each other, and we have already noticed the + great differences in these breeds, that if, among any of those variations, + you chance to have a blue pigeon turn up, it will be sure to have the + black bars across the wings, which are characteristic of the original wild + stock, the Rock Pigeon. + </p> + <p> + Now, this is certainly a very remarkable circumstance; but I do not see + myself how it tells very strongly either one way or the other. I think, in + fact, that this argument in favour of recurrence to the primitive type + might prove a great deal too much for those who so constantly bring it + forward. For example, Mr. Darwin has very forcibly urged, that nothing is + commoner than if you examine a dun horse--and I had an opportunity of + verifying this illustration lately while in the islands of the West + Highlands, where there are a great many dun horses--to find that horse + exhibit a long black stripe down his back, very often stripes on his + shoulder, and very often stripes on his legs. I, myself, saw a pony of + this description a short time ago, in a baker's cart, near Rothesay, in + Bute: it had the long stripe down the back, and stripes on the shoulders + and legs, just like those of the Ass, the Quagga, and the Zebra. Now, if + we interpret the theory of recurrence as applied to this case, might it + not be said that here was a case of a variation exhibiting the characters + and conditions of an animal occupying something like an intermediate + position between the Horse, the Ass, the Quagga, and the Zebra, and from + which these had been developed? In the same way with regard even to Man. + Every anatomist will tell you that there is nothing commoner, in + dissecting the human body, than to meet with what are called muscular + variations--that is, if you dissect two bodies very carefully, you will + probably find that the modes of attachment and insertion of the muscles + are not exactly the same in both, there being great peculiarities in the + mode in which the muscles are arranged; and it is very singular, that in + some dissections of the human body you will come upon arrangements of the + muscles very similar indeed to the same parts in the Apes. Is the + conclusion in that case to be, that this is like the black bars in the + case of the Pigeon, and that it indicates a recurrence to the primitive + type from which the animals have been probably developed? Truly, I think + that the opponents of modification and variation had better leave the + argument of recurrence alone, or it may prove altogether too strong for + them. + </p> + <p> + To sum up,--the evidence as far as we have gone is against the argument as + to any limit to divergences, so far as structure is concerned; and in + favour of a physiological limitation. By selective breeding we can produce + structural divergences as great as those of species, but we cannot produce + equal physiological divergences. For the present I leave the question + there. + </p> + <p> + Now, the next problem that lies before us--and it is an extremely + important one--is this: Does this selective breeding occur in nature? + Because, if there is no proof of it, all that I have been telling you goes + for nothing in accounting for the origin of species. Are natural causes + competent to play the part of selection in perpetuating varieties? Here we + labour under very great difficulties. In the last lecture I had occasion + to point out to you the extreme difficulty of obtaining evidence even of + the first origin of those varieties which we know to have occurred in + domesticated animals. I told you, that almost always the origin of these + varieties is overlooked, so that I could only produce two or three cases, + as that of Gratio Kelleia and of the Anconsheep. People forget, or do not + take notice of them until they come to have a prominence; and if that is + true of artificial cases, under our own eyes, and in animals in our own + care, how much more difficult it must be to have at first hand good + evidence of the origin of varieties in nature! Indeed, I do not know that + it is possible by direct evidence to prove the origin of a variety in + nature, or to prove selective breeding; but I will tell you what we can + prove--and this comes to the same thing--that varieties exist in nature + within the limits of species, and, what is more, that when a variety has + come into existence in nature, there are natural causes and conditions, + which are amply competent to play the part of a selective breeder; and + although that is not quite the evidence that one would like to + have--though it is not direct testimony--yet it is exceeding good and + exceedingly powerful evidence in its way. + </p> + <p> + As to the first point, of varieties existing among natural species, I + might appeal to the universal experience of every naturalist, and of any + person who has ever turned any attention at all to the characteristics of + plants and animals in a state of nature; but I may as well take a few + definite cases, and I will begin with Man himself. + </p> + <p> + I am one of those who believe that, at present, there is no evidence + whatever for saying, that mankind sprang originally from any more than a + single pair; I must say, that I cannot see any good ground whatever, or + even any tenable sort of evidence, for believing that there is more than + one species of Man. Nevertheless, as you know, just as there are numbers + of varieties in animals, so there are remarkable varieties of men. I speak + not merely of those broad and distinct variations which you see at a + glance. Everybody, of course, knows the difference between a Negro and a + white man, and can tell a Chinaman from an Englishman. They each have + peculiar characteristics of colour and physiognomy; but you must recollect + that the characters of these races go very far deeper--they extend to the + bony structure, and to the characters of that most important of all organs + to us--the brain; so that, among men belonging to different races, or even + within the same race, one man shall have a brain a third, or half, or even + seventy per cent, bigger than another; and if you take the whole range of + human brains, you will find a variation in some cases of a hundred per + cent. Apart from these variations in the size of the brain, the characters + of the skull vary. Thus if I draw the figures of a Mongol and of a Negro + head on the blackboard, in the case of the last the breadth would be about + seven-tenths, and in the other it would be nine-tenths of the total + length. So that you see there is abundant evidence of variation among men + in their natural condition. And if you turn to other animals there is just + the same thing. The fox, for example, which has a very large geographical + distribution all over Europe, and parts of Asia, and on the American + Continent, varies greatly. There are mostly large foxes in the North, and + smaller ones in the South. In Germany alone the foresters reckon some + eight different sorts. + </p> + <p> + Of the tiger, no one supposes that there is more than one species; they + extend from the hottest parts of Bengal, into the dry, cold, bitter + steppes of Siberia, into a latitude of 50°,--so that they may even + prey upon the reindeer. These tigers have exceedingly different + characteristics, but still they all keep their general features, so that + there is no doubt as to their being tigers. The Siberian tiger has a thick + fur, a small mane, and a longitudinal stripe down the back, while the + tigers of Java and Sumatra differ in many important respects from the + tigers of Northern Asia. So lions vary; so birds vary; and so, if you go + further back and lower down in creation, you find that fishes vary. In + different streams, in the same country even, you will find the trout to be + quite different to each other and easily recognisable by those who fish in + the particular streams. There is the same differences in leeches; leech + collectors can easily point out to you the differences and the + peculiarities which you yourself would probably pass by; so with + fresh-water mussels; so, in fact, with every animal you can mention. + </p> + <p> + In plants there is the same kind of variation. Take such a case even as + the common bramble. The botanists are all at war about it; some of them + wanting to make out that there are many species of it, and others + maintaining that they are but many varieties of one species; and they + cannot settle to this day which is a species and which is a variety! + </p> + <p> + So that there can be no doubt whatsoever that any plant and any animal may + vary in nature; that varieties may arise in the way I have described--as + spontaneous varieties--and that those varieties may be perpetuated in the + same way that I have shown you spontaneous varieties are perpetuated; I + say, therefore, that there can be no doubt as to the origin and + perpetuation of varieties in nature. + </p> + <p> + But the question now is:--Does selection take place in nature? Is there + anything like the operation of man in exercising selective breeding, + taking place in nature? You will observe that, at present, I say nothing + about species; I wish to confine myself to the consideration of the + production of those natural races which everybody admits to exist. The + question is, whether in nature there are causes competent to produce + races, just in the same way as man is able to produce by selection, such + races of animals as we have already noticed. + </p> + <p> + When a variety has arisen, the CONDITIONS OF EXISTENCE are such as to + exercise an influence which is exactly comparable to that of artificial + selection. By Conditions of Existence I mean two things--there are + conditions which are furnished by the physical, the inorganic world, and + there are conditions of existence which are furnished by the organic + world. There is, in the first place, CLIMATE; under that head I include + only temperature and the varied amount of moisture of particular places. + In the next place there is what is technically called STATION, which + means--given the climate, the particular kind of place in which an animal + or a plant lives or grows; for example, the station of a fish is in the + water, of a fresh-water fish in fresh water; the station of a marine fish + is in the sea, and a marine animal may have a station higher or deeper. So + again with land animals: the differences in their stations are those of + different soils and neighbourhoods; some being best adapted to a + calcareous, and others to an arenaceous soil. The third condition of + existence is FOOD, by which I mean food in the broadest sense, the supply + of the materials necessary to the existence of an organic being; in the + case of a plant the inorganic matters, such as carbonic acid, water, + ammonia, and the earthy salts or salines; in the case of the animal the + inorganic and organic matters, which we have seen they require; then these + are all, at least the first two, what we may call the inorganic or + physical conditions of existence. Food takes a mid-place, and then come + the organic conditions; by which I mean the conditions which depend upon + the state of the rest of the organic creation, upon the number and kind of + living beings, with which an animal is surrounded. You may class these + under two heads: there are organic beings, which operate as <i>opponents</i>, + and there are organic beings which operate as <i>helpers</i> to any given + organic creature. The opponents may be of two kinds: there are the <i>indirect + opponents</i>, which are what we may call <i>rivals</i>; and there are the + <i>direct opponents</i>, those which strive to destroy the creature; and + these we call <i>enemies</i>. By rivals I mean, of course, in the case of + plants, those which require for their support the same kind of soil and + station, and, among animals, those which require the same kind of station, + or food, or climate; those are the indirect opponents; the direct + opponents are, of course, those which prey upon an animal or vegetable. + The <i>helpers</i> may also be regarded as direct and indirect: in the + case of a carnivorous animal, for example, a particular herbaceous plant + may, in multiplying, be an indirect helper, by enabling the herbivora on + which the carnivore preys to get more food, and thus to nourish the + carnivore more abundantly; the direct helper may be best illustrated by + reference to some parasitic creature, such as the tape-worm. The tape-worm + exists in the human intestines, so that the fewer there are of men the + fewer there will be of tape-worms, other things being alike. It is a + humiliating reflection, perhaps, that we may be classed as direct helpers + to the tape-worm, but the fact is so: we can all see that if there were no + men there would be no tape-worms. + </p> + <p> + It is extremely difficult to estimate, in a proper way, the importance and + the working of the Conditions of Existence. I do not think there were any + of us who had the remotest notion of properly estimating them until the + publication of Mr. Darwin's work, which has placed them before us with + remarkable clearness; and I must endeavour, as far as I can in my own + fashion, to give you some notion of how they work. We shall find it + easiest to take a simple case, and one as free as possible from every kind + of complication. + </p> + <p> + I will suppose, therefore, that all the habitable part of this globe--the + dry land, amounting to about 51,000,000 square miles--I will suppose that + the whole of that dry land has the same climate, and that it is composed + of the same kind of rock or soil, so that there will be the same station + everywhere; we thus get rid of the peculiar influence of different + climates and stations. I will then imagine that there shall be but one + organic being in the world, and that shall be a plant. In this we start + fair. Its food is to be carbonic acid, water and ammonia, and the saline + matters in the soil, which are, by the supposition, everywhere alike. We + take one single plant, with no opponents, no helpers, and no rivals; it is + to be a "fair field, and no favour." Now, I will ask you to imagine + further that it shall be a plant which shall produce every year fifty + seeds, which is a very moderate number for a plant to produce; and that, + by the action of the winds and currents, these seeds shall be equally and + gradually distributed over the whole surface of the land. I want you now + to trace out what will occur, and you will observe that I am not talking + fallaciously any more than a mathematician does when he expounds his + problem. If you show that the conditions of your problem are such as may + actually occur in Nature and do not transgress any of the known laws of + Nature in working out your proposition, then you are as safe in the + conclusion you arrive at as is the mathematician in arriving at the + solution of his problem. In science, the only way of getting rid of the + complications with which a subject of this kind is environed, is to work + in this deductive method. What will be the result, then? I will suppose + that every plant requires one square foot of ground to live upon; and the + result will be that, in the course of nine years, the plant will have + occupied every single available spot in the whole globe! I have chalked + upon the blackboard the figures by which I arrive at the result:-- + </p> + <table border="1" cellspacing="0" cellpadding="2" summary=""> + <tr> + <th align="center"> + Plants. + </th> + <th align="center"></th> + <th align="right"> + Plants. + </th> + </tr> + <tr> + <td align="right"> + 1 x 50 in 1st year + </td> + <td align="center"> + = + </td> + <td align="right"> + 50 + </td> + </tr> + <tr> + <td align="right"> + 50 x 50 " 2nd " + </td> + <td align="center"> + = + </td> + <td align="right"> + 2,500 + </td> + </tr> + <tr> + <td align="right"> + 2,500 x 50 " 3rd " + </td> + <td align="center"> + = + </td> + <td align="right"> + 125,000 + </td> + </tr> + <tr> + <td align="right"> + 125,000 x 50 " 4th " + </td> + <td align="center"> + = + </td> + <td align="right"> + 6,250,000 + </td> + </tr> + <tr> + <td align="right"> + 6,250,000 x 50 " 5th " + </td> + <td align="center"> + = + </td> + <td align="right"> + 312,500,000 + </td> + </tr> + <tr> + <td align="right"> + 312,500,000 x 50 " 6th " + </td> + <td align="center"> + = + </td> + <td align="right"> + 15,625,000,000 + </td> + </tr> + <tr> + <td align="right"> + 15,625,000,000 x 50 " 7th " + </td> + <td align="center"> + = + </td> + <td align="right"> + 781,250,000,000 + </td> + </tr> + <tr> + <td align="right"> + 781,250,000,000 x 50 " 8th " + </td> + <td align="center"> + = + </td> + <td align="right"> + 39,062,500,000,000 + </td> + </tr> + <tr> + <td align="right"> + 39,062,500,000,000 x 50 " 9th " + </td> + <td align="center"> + = + </td> + <td align="right"> + 1,953,125,000,000,000 + </td> + </tr> + </table> +<pre xml:space="preserve"> + 51,000,000 square miles--the \ + dry surface of the earth x | = sq. ft. 1,421,798,400,000,000 + 27,878,400--the number of | + sq. ft. in 1 sq. mile / --------------------- + being 531,326,600,000,000 + square feet less than would be required at the end of the ninth + year. +</pre> + <p> + You will see from this that, at the end of the first year the single plant + will have produced fifty more of its kind; by the end of the second year + these will have increased to 2,500; and so on, in succeeding years, you + get beyond even trillions; and I am not at all sure that I could tell you + what the proper arithmetical denomination of the total number really is; + but, at any rate, you will understand the meaning of all those noughts. + Then you see that, at the bottom, I have taken the 51,000,000 of square + miles, constituting the surface of the dry land; and as the number of + square feet are placed under and subtracted from the number of seeds that + would be produced in the ninth year, you can see at once that there would + be an immense number more of plants than there would be square feet of + ground for their accommodation. This is certainly quite enough to prove my + point; that between the eighth and ninth year after being planted the + single plant would have stocked the whole available surface of the earth. + </p> + <p> + This is a thing which is hardly conceivable--it seems hardly + imaginable--yet it is so. It is indeed simply the law of Malthus + exemplified. Mr. Malthus was a clergyman, who worked out this subject most + minutely and truthfully some years ago; he showed quite clearly--and + although he was much abused for his conclusions at the time, they have + never yet been disproved and never will be--he showed that in consequence + of the increase in the number of organic beings in a geometrical ratio, + while the means of existence cannot be made to increase in the same ratio, + that there must come a time when the number of organic beings will be in + excess of the power of production of nutriment, and that thus some check + must arise to the further increase of those organic beings. At the end of + the ninth year we have seen that each plant would not be able to get its + full square foot of ground, and at the end of another year it would have + to share that space with fifty others the produce of the seeds which it + would give off. + </p> + <p> + What, then, takes place? Every plant grows up, flourishes, occupies its + square foot of ground, and gives off its fifty seeds; but notice this, + that out of this number only one can come to anything; there is thus, as + it were, forty-nine chances to one against its growing up; it depends upon + the most fortuitous circumstances whether any one of these fifty seeds + shall grow up and flourish, or whether it shall die and perish. This is + what Mr. Darwin has drawn attention to, and called the "STRUGGLE FOR + EXISTENCE"; and I have taken this simple case of a plant because some + people imagine that the phrase seems to imply a sort of fight. + </p> + <p> + I have taken this plant and shown you that this is the result of the ratio + of the increase, the necessary result of the arrival of a time coming for + every species when exactly as many members must be destroyed as are born; + that is the inevitable ultimate result of the rate of production. Now, + what is the result of all this? I have said that there are forty-nine + struggling against every one; and it amounts to this, that the smallest + possible start given to any one seed may give it an advantage which will + enable it to get ahead of all the others; anything that will enable any + one of these seeds to germinate six hours before any of the others will, + other things being alike, enable it to choke them out altogether. I have + shown you that there is no particular in which plants will not vary from + each other; it is quite possible that one of our imaginary plants may vary + in such a character as the thickness of the integument of its seeds; it + might happen that one of the plants might produce seeds having a thinner + integument, and that would enable the seeds of that plant to germinate a + little quicker than those of any of the others, and those seeds would most + inevitably extinguish the forty-nine times as many that were struggling + with them. + </p> + <p> + I have put it in this way, but you see the practical result of the process + is the same as if some person had nurtured the one and destroyed the other + seeds. It does not matter how the variation is produced, so long as it is + once allowed to occur. The variation in the plant once fairly started + tends to become hereditary and reproduce itself; the seeds would spread + themselves in the same way and take part in the struggle with the + forty-nine hundred, or forty-nine thousand, with which they might be + exposed. Thus, by degrees, this variety with some slight organic change or + modification, must spread itself over the whole surface of the habitable + globe, and extirpate or replace the other kinds. That is what is meant by + NATURAL SELECTION; that is the kind of argument by which it is perfectly + demonstrable that the conditions of existence may play exactly the same + part for natural varieties as man does for domesticated varieties. No one + doubts at all that particular circumstances may be more favourable for one + plant and less so for another, and the moment you admit that, you admit + the selective power of nature. Now, although I have been putting a + hypothetical case, you must not suppose that I have been reasoning + hypothetically. There are plenty of direct experiments which bear out what + we may call the theory of natural selection; there is extremely good + authority for the statement that if you take the seed of mixed varieties + of wheat and sow it, collecting the seed next year and sowing it again, at + length you will find that out of all your varieties only two or three have + lived, or perhaps even only one. There were one or two varieties which + were best fitted to get on, and they have killed out the other kinds in + just the same way and with just the same certainty as if you had taken the + trouble to remove them. As I have already said, the operation of nature is + exactly the same as the artificial operation of man. + </p> + <p> + But if this be true of that simple case, which I put before you, where + there is nothing but the rivalry of one member of a species with others, + what must be the operation of selective conditions, when you recollect as + a matter of fact, that for every species of animal or plant there are + fifty or a hundred species which might all, more or less, be comprehended + in the same climate, food, and station;--that every plant has + multitudinous animals which prey upon it, and which are its direct + opponents; and that these have other animals preying upon them,--that + every plant has its indirect helpers in the birds that scatter abroad its + seed, and the animals that manure it with their dung;--I say, when these + things are considered, it seems impossible that any variation which may + arise in a species in nature should not tend in some way or other either + to be a little better or worse than the previous stock; if it is a little + better it will have an advantage over and tend to extirpate the latter in + this crush and struggle; and if it is a little worse it will itself be + extirpated. + </p> + <p> + I know nothing that more appropriately expresses this, than the phrase, + "the struggle for existence "; because it brings before your minds, in a + vivid sort of way, some of the simplest possible circumstances connected + with it. When a struggle is intense there must be some who are sure to be + trodden down, crushed, and overpowered by others; and there will be some + who just manage to get through only by the help of the slightest accident. + I recollect reading an account of the famous retreat of the French troops, + under Napoleon, from Moscow. Worn out, tired, and dejected, they at length + came to a great river over which there was but one bridge for the passage + of the vast army. Disorganised and demoralised as that army was, the + struggle must certainly have been a terrible one--every one heeding only + himself, and crushing through the ranks and treading down his fellows. The + writer of the narrative, who was himself one of those who were fortunate + enough to succeed in getting over, and not among the thousands who were + left behind or forced into the river, ascribed his escape to the fact that + he saw striding onward through the mass a great strong fellow,--one of the + French Cuirassiers, who had on a large blue cloak-and he had enough + presence of mind to catch and retain a hold of this strong man's cloak. He + says, "I caught hold of his cloak, and although he swore at me and cut at + and struck me by turns, and at last, when he found he could not shake me + off, fell to entreating me to leave go or I should prevent him from + escaping, besides not assisting myself, I still kept tight hold of him, + and would not quit my grasp until he had at last dragged me through." Here + you see was a case of selective saving--if we may so term it--depending + for its success on the strength of the cloth of the Cuirassier's cloak. It + is the same in nature; every species has its bridge of Beresina; it has to + fight its way through and struggle with other species; and when well-nigh + overpowered, it may be that the smallest chance, something in its colour, + perhaps--the minutest circumstance--will turn the scale one way or the + other. + </p> + <p> + Suppose that by a variation of the black race it had produced the white + man at any time--you know that the Negroes are said to believe this to + have been the case, and to imagine that Cain was the first white man, and + that we are his descendants--suppose that this had ever happened, and that + the first residence of this human being was on the West Coast of Africa. + There is no great structural difference between the white man and the + Negro, and yet there is something so singularly different in the + constitution of the two, that the malarias of that country, which do not + hurt the black at all, cut off and destroy the white. Then you see there + would have been a selective operation performed; if the white man had + risen in that way, he would have been selected out and removed by means of + the malaria. Now there really is a very curious case of selection of this + sort among pigs, and it is a case of selection of colour too. In the woods + of Florida there are a great many pigs, and it is a very curious thing + that they are all black, every one of them. Professor Wyman was there some + years ago, and on noticing no pigs but these black ones, he asked some of + the people how it was that they had no white pigs, and the reply was that + in the woods of Florida there was a root which they called the Paint Root, + and that if the white pigs were to eat any of it, it had the effect of + making their hoofs crack, and they died, but if the black pigs ate any of + it, it did not hurt them at all. Here was a very simple case of natural + selection. A skilful breeder could not more carefully develop the black + breed of pigs, and weed out all the white pigs, than the Paint Root does. + </p> + <p> + To show you how remarkably indirect may be such natural selective agencies + as I have referred to, I will conclude by noticing a case mentioned by Mr. + Darwin, and which is certainly one of the most curious of its kind. It is + that of the Humble Bee. It has been noticed that there are a great many + more humble bees in the neighbourhood of towns, than out in the open + country; and the explanation of the matter is this: the humble bees build + nests, in which they store their honey and deposit the larvæ and + eggs. The field mice are amazingly fond of the honey and larvæ; + therefore, wherever there are plenty of field mice, as in the country, the + humble bees are kept down; but in the neighbourhood of towns, the number + of cats which prowl about the fields eat up the field mice, and of course + the more mice they eat up the less there are to prey upon the larvæ + of the bees--the cats are therefore the INDIRECT HELPERS of the bees. [*] + Coming back a step farther we may say that the old maids are also indirect + friends of the humble bees, and indirect enemies of the field mice, as + they keep the cats which eat up the latter! This is an illustration + somewhat beneath the dignity of the subject, perhaps, but it occurs to me + in passing, and with it I will conclude this lecture. + </p> + <ol class="footnotes"> + <li> + The humble bees, on the other hand, are direct helpers of some plants, + such as the heartsease and red clover, which are fertilised by the + visits of the bees; and they are indirect helpers of the numerous + insects which are more or less completely supported by the heartsease + and red clover. + </li> + </ol> + <h3> + VI. A Critical Examination Of The Position Of Mr. Darwin's Work, "On The + Origin Of Species," In Relation To The Complete Theory Of The Causes Of + The Phenomena Of Organic Nature + </h3> + <p> + In the preceding five lectures I have endeavoured to give you an account + of those facts, and of those reasonings from facts, which form the data + upon which all theories regarding the causes of the phenomena of organic + nature must be based. And, although I have had frequent occasion to quote + Mr. Darwin--as all persons hereafter, in speaking upon these subjects, + will have occasion to quote his famous book on the "Origin of + Species,"--you must yet remember that, wherever I have quoted him, it has + not been upon theoretical points, or for statements in any way connected + with his particular speculations, but on matters of fact, brought forward + by himself, or collected by himself, and which appear incidentally in his + book. If a man <i>will</i> make a book, professing to discuss a single + question, an encyclopædia, I cannot help it. + </p> + <p> + Now, having had an opportunity of considering in this sort of way the + different statements bearing upon all theories whatsoever, I have to lay + before you, as fairly as I can, what is Mr. Darwin's view of the matter + and what position his theories hold, when judged by the principles which I + have previously laid down, as deciding our judgments upon all theories and + hypotheses. + </p> + <p> + I have already stated to you that the inquiry respecting the causes of the + phenomena of organic nature resolves itself into two problems--the first + being the question of the origination of living or organic beings; and the + second being the totally distinct problem of the modification and + perpetuation of organic beings when they have already come into existence. + The first question Mr. Darwin does not touch; he does not deal with it at + all; but he says:--"Given the origin of organic matter--supposing its + creation to have already taken place, my object is to show in consequence + of what laws and what demonstrable properties of organic matter, and of + its environments, such states of organic nature as those with which we are + acquainted must have come about." This, you will observe, is a perfectly + legitimate proposition; every person has a right to define the limits of + the inquiry which he sets before himself; and yet it is a most singular + thing that in all the multifarious, and, not unfrequently, ignorant + attacks which have been made upon the "Origin of Species," there is + nothing which has been more speciously criticised than this particular + limitation. If people have nothing else to urge against the book, they + say--"Well, after all, you see Mr. Darwin's explanation of the 'Origin of + Species' is not good for much, because, in the long run, he admits that he + does not know how organic matter began to exist. But if you admit any + special creation for the first particle of organic matter you may just as + well admit it for all the rest; five hundred or five thousand distinct + creations are just as intelligible, and just as little difficult to + understand, as one." The answer to these cavils is two-fold. In the first + place, all human inquiry must stop somewhere; all our knowledge and all + our investigation cannot take us beyond the limits set by the finite and + restricted character of our faculties, or destroy the endless unknown, + which accompanies, like its shadow, the endless procession of phenomena. + So far as I can venture to offer an opinion on such a matter, the purpose + of our being in existence, the highest object that human beings can set + before themselves, is not the pursuit of any such chimera as the + annihilation of the unknown; but it is simply the unwearied endeavour to + remove its boundaries a little further from our little sphere of action. + </p> + <p> + I wonder if any historian would for a moment admit the objection, that it + is preposterous to trouble ourselves about the history of the Roman + Empire, because we do not know anything positive about the origin and + first building of the city of Rome! Would it be a fair objection to urge, + respecting the sublime discoveries of a Newton, or a Kepler, those great + philosophers, whose discoveries have been of the profoundest benefit and + service to all men--to say to them--"After all that you have told us as to + how the planets revolve, and how they are maintained in their orbits, you + cannot tell us what is the cause of the origin of the sun, moon, and + stars. So what is the use of what you have done?" Yet these objections + would not be one whit more preposterous than the objections which have + been made to the "Origin of Species." Mr. Darwin, then, had a perfect + right to limit his inquiry as he pleased, and the only question for + us--the inquiry being so limited--is to ascertain whether the method of + his inquiry is sound or unsound; whether he has obeyed the canons which + must guide and govern all investigation, or whether he has broken them; + and it was because our inquiry this evening is essentially limited to that + question, that I spent a good deal of time in a former lecture (which, + perhaps some of you thought might have been better employed), in + endeavouring to illustrate the method and nature of scientific inquiry in + general. We shall now have to put in practice the principles that I then + laid down. + </p> + <p> + I stated to you in substance, if not in words, that wherever there are + complex masses of phenomena to be inquired into, whether they be phenomena + of the affairs of daily life, or whether they belong to the more abstruse + and difficult problems laid before the philosopher, our course of + proceeding in unravelling that complex chain of phenomena with a view to + get at its cause, is always the same; in all cases we must invent an + hypothesis; we must place before ourselves some more or less likely + supposition respecting that cause; and then, having assumed an hypothesis, + having supposed a cause for the phenomena in question, we must endeavour, + on the one hand, to demonstrate our hypothesis, or, on the other, to upset + and reject it altogether, by testing it in three ways. We must, in the + first place, be prepared to prove that the supposed causes of the + phenomena exist in nature; that they are what the logicians call <i>vera + causæ</i>--true causes;--in the next place, we should be prepared to + show that the assumed causes of the phenomena are competent to produce + such phenomena as those which we wish to explain by them; and in the last + place, we ought to be able to show that no other known causes are + competent to produce these phenomena. If we can succeed in satisfying + these three conditions we shall have demonstrated our hypothesis; or + rather I ought to say we shall have proved it as far as certainty is + possible for us; for, after all, there is no one of our surest convictions + which may not be upset, or at any rate modified by a further accession of + knowledge. It was because it satisfied these conditions that we accepted + the hypothesis as to the disappearance of the tea-pot and spoons in the + case I supposed in a previous lecture; we found that our hypothesis on + that subject was tenable and valid, because the supposed cause existed in + nature, because it was competent to account for the phenomena, and because + no other known cause was competent to account for them; and it is upon + similar grounds that any hypothesis you choose to name is accepted in + science as tenable and valid. + </p> + <p> + What is Mr. Darwin's hypothesis? As I apprehend it--for I have put it into + a shape more convenient for common purposes than I could find <i>verbatim</i> + in his book--as I apprehend it, I say, it is, that all the phenomena of + organic nature, past and present, result from, or are caused by, the + inter-action of those properties of organic matter, which we have called + ATAVISM and VARIABILITY, with the CONDITIONS OF EXISTENCE, or, in other + words,--given the existence of organic matter, its tendency to transmit + its properties, and its tendency occasionally to vary; and, lastly, given + the conditions of existence by which organic matter is surrounded--that + these put together are the causes of the Present and of the Past + conditions of ORGANIC NATURE. + </p> + <p> + Such is the hypothesis as I understand it. Now let us see how it will + stand the various tests which I laid down just now. In the first place, do + these supposed causes of the phenomena exist in nature? Is it the fact + that, in nature, these properties of organic matter--atavism and + variability--and those phenomena which we have called the conditions of + existence,--is it true that they exist? Well, of course, if they do not + exist, all that I have told you in the last three or four lectures must be + incorrect, because I have been attempting to prove that they do exist, and + I take it that there is abundant evidence that they do exist; so far, + therefore, the hypothesis does not break down. + </p> + <p> + But in the next place comes a much more difficult inquiry:--Are the causes + indicated competent to give rise to the phenomena of organic nature? I + suspect that this is indubitable to a certain extent. It is demonstrable, + I think, as I have endeavoured to show you, that they are perfectly + competent to give rise to all the phenomena which are exhibited by RACES + in nature. Furthermore, I believe that they are quite competent to account + for all that we may call purely structural phenomena which are exhibited + by SPECIES in nature. On that point also I have already enlarged somewhat. + Again, I think that the causes assumed are competent to account for most + of the physiological characteristics of species, and I not only think that + they are competent to account for them, but I think that they account for + many things which otherwise remain wholly unaccountable and inexplicable, + and I may say incomprehensible. For a full exposition of the grounds on + which this conviction is based, I must refer you to Mr. Darwin's work; all + that I can do now is to illustrate what I have said by two or three cases + taken almost at random. + </p> + <p> + I drew your attention, on a previous evening, to the facts which are + embodied in our systems of Classification, which are the results of the + examination and comparison of the different members of the animal kingdom + one with another. I mentioned that the whole of the animal kingdom is + divisible into five sub-kingdoms; that each of these sub-kingdoms is again + divisible into provinces; that each province may be divided into classes, + and the classes into the successively smaller groups, orders, families, + genera, and species. + </p> + <p> + Now, in each of these groups the resemblance in structure among the + members of the group is closer in proportion as the group is smaller. + Thus, a man and a worm are members of the animal kingdom in virtue of + certain apparently slight though really fundamental resemblances which + they present. But a man and a fish are members of the same sub-kingdom <i>Vertebrata</i>, + because they are much more like one another than either of them is to a + worm, or a snail, or any member of the other sub-kingdoms. For similar + reasons men and horses are arranged as members of the same Class, <i>Mammalia</i>; + men and apes as members of the same Order, <i>Primates</i>; and if there + were any animals more like men than they were like any of the apes, and + yet different from men in important and constant particulars of their + organisation, we should rank them as members of the same Family, or of the + same Genus, but as of distinct Species. + </p> + <p> + That it is possible to arrange all the varied forms of animals into + groups, having this sort of singular subordination one to the other, is a + very remarkable circumstance; but, as Mr. Darwin remarks, this is a result + which is quite to be expected, if the principles which he lays down be + correct. Take the case of the races which are known to be produced by the + operation of atavism and variability, and the conditions of existence + which check and modify these tendencies. Take the case of the pigeons that + I brought before you: there it was shown that they might be all classed as + belonging to some one of five principal divisions, and that within these + divisions other subordinate groups might be formed. The members of these + groups are related to one another in just the same way as the genera of a + family, and the groups themselves as the families of an order, or the + orders of a class; while all have the same sort of structural relations + with the wild rock-pigeon, as the members of any great natural group have + with a real or imaginary typical form. Now, we know that all varieties of + pigeons of every kind have arisen by a process of selective breeding from + a common stock, the rock-pigeon; hence, you see, that if all species of + animals have proceeded from some common stock, the general character of + their structural relations, and of our systems of classification, which + express those relations, would be just what we find them to be. In other + words, the hypothetical cause is, so far, competent to produce effects + similar to those of the real cause. + </p> + <p> + Take, again, another set of very remarkable facts,--the existence of what + are called rudimentary organs, organs for which we can find no obvious + use, in the particular animal economy in which they are found, and yet + which are there. + </p> + <p> + Such are the splint-like bones in the leg of the horse, which I here show + you, and which correspond with bones which belong to certain toes and + fingers in the human hand and foot. In the horse you see they are quite + rudimentary, and bear neither toes nor fingers; so that the horse has only + one "finger" in his fore-foot and one "toe" in his hind-foot. But it is a + very curious thing that the animals closely allied to the horse show more + toes than he; as the rhinoceros, for instance: he has these extra toes + well formed, and anatomical facts show very clearly that he is very + closely related to the horse indeed. So we may say that animals, in an + anatomical sense nearly related to the horse, have those parts which are + rudimentary in him fully developed. + </p> + <p> + Again, the sheep and the cow have no cutting-teeth, but only a hard pad in + the upper jaw. That is the common characteristic of ruminants in general. + But the calf has in its upper jaw some rudiments of teeth which never are + developed, and never play the part of teeth at all. Well, if you go back + in time, you find some of the older, now extinct, allies of the ruminants + have well-developed teeth in their upper jaws; and at the present day the + pig (which is in structure closely connected with ruminants) has + well-developed teeth in its upper jaw; so that here is another instance of + organs well-developed and very useful, in one animal, represented by + rudimentary organs, for which we can discover no purpose whatsoever in + another closely allied animal. The whalebone whale, again, has horny + "whalebone" plates in its mouth, and no teeth; but the young foetal whale + before it is born has teeth in its jaws; they, however, are never used, + and they never come to anything. But other members of the group to which + the whale belongs have well-developed teeth in both jaws. + </p> + <p> + Upon any hypothesis of special creation, facts of this kind appear to me + to be entirely unaccountable and inexplicable, but they cease to be so if + you accept Mr. Darwin's hypothesis, and see reason for believing that the + whalebone whale and the whale with teeth in its mouth both sprang from a + whale that had teeth, and that the teeth of the foetal whale are merely + remnants--recollections, if we may so say--of the extinct whale. So in the + case of the horse and the rhinoceros: suppose that both have descended by + modification from some earlier form which had the normal number of toes, + and the persistence of the rudimentary bones which no longer support toes + in the horse becomes comprehensible. + </p> + <p> + In the language that we speak in England, and in the language of the + Greeks, there are identical verbal roots, or elements entering into the + composition of words. That fact remains unintelligible so long as we + suppose English and Greek to be independently created tongues; but when it + is shown that both languages are descended from one original, we give an + explanation of that resemblance. In the same way the existence of + identical structural roots, if I may so term them, entering into the + composition of widely different animals, is striking evidence in favour of + the descent of those animals from a common original. + </p> + <p> + To turn to another kind of illustration:--If you regard the whole series + of stratified rocks--that enormous thickness of sixty or seventy thousand + feet that I have mentioned before, constituting the only record we have of + a most prodigious lapse of time, that time being, in all probability, but + a fraction of that of which we have no record;--if you observe in these + successive strata of rocks successive groups of animals arising and dying + out, a constant succession, giving you the same kind of impression, as you + travel from one group of strata to another, as you would have in + travelling from one country to another;--when you find this constant + succession of forms, their traces obliterated except to the man of + science--when you look at this wonderful history, and ask what it means, + it is only a paltering with words if you are offered the reply--"They were + so created." + </p> + <p> + But if, on the other hand, you look on all forms of organised beings as + the results of the gradual modification of a primitive type, the facts + receive a meaning, and you see that these older conditions are the + necessary predecessors of the present. Viewed in this light the facts of + palaeontology receive a meaning--upon any other hypothesis I am unable to + see, in the slightest degree, what knowledge or signification we are to + draw out of them. Again, note as bearing upon the same point, the singular + likeness which obtains between the successive Faunæ and Floræ, + whose remains are preserved on the rocks: you never find any great and + enormous difference between the immediately successive Faunæ and + Floræ, unless you have reason to believe there has also been a great + lapse of time or a great change of conditions. The animals, for instance, + of the newest tertiary rocks, in any part of the world, are always, and + without exception, found to be closely allied with those which now live in + that part of the world. For example, in Europe, Asia, and Africa, the + large mammals are at present rhinoceroses, hippopotamuses, elephants, + lions, tigers, oxen, horses, &c.; and if you examine the newest + tertiary deposits, which contain the animals and plants which immediately + preceded those which now exist in the same country, you do not find + gigantic specimens of ant-eaters and kangaroos, but you find rhinoceroses, + elephants, lions, tigers, &c.,--of different species to those now + living--but still their close allies. If you turn to South America, where, + at the present day, we have great sloths and armadilloes and creatures of + that kind, what do you find in the newest tertiaries? You find the great + sloth-like creature, the <i>Megatherium</i>, and the great armadillo, the + <i>Glyptodon</i>, and so on. And if you go to Australia you find the same + law holds good, namely, that that condition of organic nature which has + preceded the one which now exists, presents differences perhaps of + species, and of genera, but that the great types of organic structure are + the same as those which now flourish. + </p> + <p> + What meaning has this fact upon any other hypothesis or supposition than + one of successive modification? But if the population of the world, in any + age, is the result of the gradual modification of the forms which peopled + it in the preceding age--if that has been the case, it is intelligible + enough; because we may expect that the creature that results from the + modification of an elephantine mammal shall be something like an elephant, + and the creature which is produced by the modification of an + armadillo-like mammal shall be like an armadillo. Upon that supposition, I + say, the facts are intelligible; upon any other, that I am aware of, they + are not. + </p> + <p> + So far, the facts of palæontology are consistent with almost any + form of the doctrine of progressive modification; they would not be + absolutely inconsistent with the wild speculations of De Maillet, or with + the less objectionable hypothesis of Lamarck. But Mr. Darwin's views have + one peculiar merit; and that is, that they are perfectly consistent with + an array of facts which are utterly inconsistent with, and fatal to, any + other hypothesis of progressive modification which has yet been advanced. + It is one remarkable peculiarity of Mr. Darwin's hypothesis that it + involves no necessary progression or incessant modification, and that it + is perfectly consistent with the persistence for any length of time of a + given primitive stock, contemporaneously with its modifications. To return + to the case of the domestic breeds of pigeons, for example; you have the + dove-cot pigeon, which closely resembles the rock pigeon, from which they + all started, existing at the same time with the others. And if species are + developed in the same way in nature, a primitive stock and its + modifications may, occasionally, all find the conditions fitted for their + existence; and though they come into competition, to a certain extent, + with one another, the derivative species may not necessarily extirpate the + primitive one, or <i>vice versa</i>. + </p> + <p> + Now palæontology shows us many facts which are perfectly harmonious + with these observed effects of the process by which Mr. Darwin supposes + species to have originated, but which appear to me to be totally + inconsistent with any other hypothesis which has been proposed. There are + some groups of animals and plants, in the fossil world, which have been + said to belong to "persistent types," because they have persisted, with + very little change indeed, through a very great range of time, while + everything about them has changed largely. There are families of fishes + whose type of construction has persisted all the way from the + carboniferous strata right up to the cretaceous; and others which have + lasted through almost the whole range of the secondary rocks, and from the + lias to the older tertiaries. It is something stupendous this--to consider + a genus lasting without essential modifications through all this enormous + lapse of time while almost everything else was changed and modified. + </p> + <p> + Thus I have no doubt that Mr. Darwin's hypothesis will be found competent + to explain the majority of the phenomena exhibited by species in nature; + but in an earlier lecture I spoke cautiously with respect to its power of + explaining all the physiological peculiarities of species. + </p> + <p> + There is, in fact, one set of these peculiarities which the theory of + selective modification, as it stands at present, is not wholly competent + to explain, and that is the group of phenomena which I mentioned to you + under the name of Hybridism, and which I explained to consist in the + sterility of the offspring of certain species when crossed one with + another. It matters not one whit whether this sterility is universal, or + whether it exists only in a single case. Every hypothesis is bound to + explain, or, at any rate, not be inconsistent with, the whole of the facts + which it professes to account for; and if there is a single one of these + facts which can be shown to be inconsistent with (I do not merely mean + inexplicable by, but contrary to) the hypothesis, the hypothesis falls to + the ground,--it is worth nothing. One fact with which it is positively + inconsistent is worth as much, and as powerful in negativing the + hypothesis, as five hundred. If I am right in thus defining the + obligations of an hypothesis, Mr. Darwin, in order to place his views + beyond the reach of all possible assault, ought to be able to demonstrate + the possibility of developing from a particular stock by selective + breeding, two forms, which should either be unable to cross one with + another, or whose cross-bred offspring should be infertile with one + another. + </p> + <p> + For, you see, if you have not done that you have not strictly fulfilled + all the conditions of the problem; you have not shown that you can + produce, by the cause assumed, all the phenomena which you have in nature. + Here are the phenomena of Hybridism staring you in the face, and you + cannot say, "I can, by selective modification, produce these same + results." Now, it is admitted on all hands that, at present, so far as + experiments have gone, it has not been found possible to produce this + complete physiological divergence by selective breeding. I stated this + very clearly before, and I now refer to the point, because, if it could be + proved, not only that this <i>has</i> not been done, but that it <i>cannot</i> + be done; if it could be demonstrated that it is impossible to breed + selectively, from any stock, a form which shall not breed with another, + produced from the same stock; and if we were shown that this must be the + necessary and inevitable results of all experiments, I hold that Mr. + Darwin's hypothesis would be utterly shattered. + </p> + <p> + But has this been done? or what is really the state of the case? It is + simply that, so far as we have gone yet with our breeding, we have not + produced from a common stock two breeds which are not more or less fertile + with one another. + </p> + <p> + I do not know that there is a single fact which would justify any one in + saying that any degree of sterility has been observed between breeds + absolutely known to have been produced by selective breeding from a common + stock. On the other hand, I do not know that there is a single fact which + can justify any one in asserting that such sterility cannot be produced by + proper experimentation. For my own part, I see every reason to believe + that it may, and will be so produced. For, as Mr. Darwin has very properly + urged, when we consider the phenomena of sterility, we find they are most + capricious; we do not know what it is that the sterility depends on. There + are some animals which will not breed in captivity; whether it arises from + the simple fact of their being shut up and deprived of their liberty, or + not, we do not know, but they certainly will not breed. What an astounding + thing this is, to find one of the most important of all functions + annihilated by mere imprisonment! + </p> + <p> + So, again, there are cases known of animals which have been thought by + naturalists to be undoubted species, which have yielded perfectly fertile + hybrids; while there are other species which present what everybody + believes to be varieties [*] which are more or less infertile with one + another. There are other cases which are truly extraordinary; there is + one, for example, which has been carefully examined,--of two kinds of + sea-weed, of which the male element of the one, which we may call A, + fertilises the female element of the other, B; while the male element of B + will not fertilise the female element of A; so that, while the former + experiment seems to show us that they are <i>varieties</i>, the latter + leads to the conviction that they are <i>species</i>. + </p> + <ol class="footnotes"> + <li> + And as I conceive with very good reason; but if any objector urges that + we cannot prove that they have been produced by artificial or natural + selection, the objection must be admitted--ultra-sceptical as it is. But + in science, scepticism is a duty. + </li> + </ol> + <p> + When we see how capricious and uncertain this sterility is, how unknown + the conditions on which it depends, I say that we have no right to affirm + that those conditions will not be better understood by and by, and we have + no ground for supposing that we may not be able to experiment so as to + obtain that crucial result which I mentioned just now. So that though Mr. + Darwin's hypothesis does not completely extricate us from this difficulty + at present, we have not the least right to say it will not do so. + </p> + <p> + There is a wide gulf between the thing you cannot explain and the thing + that upsets you altogether. There is hardly any hypothesis in this world + which has not some fact in connection with it which has not been + explained, but that is a very different affair to a fact that entirely + opposes your hypothesis; in this case all you can say is, that your + hypothesis is in the same position as a good many others. + </p> + <p> + Now, as to the third test, that there are no other causes competent to + explain the phenomena, I explained to you that one should be able to say + of an hypothesis, that no other known causes than those supposed by it are + competent to give rise to the phenomena. Here, I think, Mr. Darwin's view + is pretty strong. I really believe that the alternative is either + Darwinism or nothing, for I do not know of any rational conception or + theory of the organic universe which has any scientific position at all + beside Mr. Darwin's. I do not know of any proposition that has been put + before us with the intention of explaining the phenomena of organic + nature, which has in its favour a thousandth part of the evidence which + may be adduced in favour of Mr. Darwin's views. Whatever may be the + objections to his views, certainly all other theories are absolutely out + of court. + </p> + <p> + Take the Lamarckian hypothesis, for example. Lamarck was a great + naturalist, and to a certain extent went the right way to work; he argued + from what was undoubtedly a true cause of some of the phenomena of organic + nature. He said it is a matter of experience that an animal may be + modified more or less in consequence of its desires and consequent + actions. Thus, if a man exercise himself as a blacksmith, his arms will + become strong and muscular; such organic modification is a result of this + particular action and exercise. Lamarck thought that by a very simple + supposition based on this truth he could explain the origin of the various + animal species: he said, for example, that the short-legged birds which + live on fish had been converted into the long-legged waders by desiring to + get the fish without wetting their feathers, and so stretching their legs + more and more through successive generations. If Lamarck could have shown + experimentally that even races of animals could be produced in this way, + there might have been some ground for his speculations. But he could show + nothing of the kind, and his hypothesis has pretty well dropped into + oblivion, as it deserved to do. I said in an earlier lecture that there + are hypotheses and hypotheses, and when people tell you that Mr. Darwin's + strongly-based hypothesis is nothing but a mere modification of Lamarck's, + you will know what to think of their capacity for forming a judgment on + this subject. + </p> + <p> + But you must recollect that when I say I think it is either Mr. Darwin's + hypothesis or nothing; that either we must take his view, or look upon the + whole of organic nature as an enigma, the meaning of which is wholly + hidden from us; you must understand that I mean that I accept it + provisionally, in exactly the same way as I accept any other hypothesis. + Men of science do not pledge themselves to creeds; they are bound by + articles of no sort; there is not a single belief that it is not a bounden + duty with them to hold with a light hand and to part with cheerfully, the + moment it is really proved to be contrary to any fact, great or small. And + if, in course of time I see good reasons for such a proceeding, I shall + have no hesitation in coming before you, and pointing out any change in my + opinion without finding the slightest occasion to blush for so doing. So I + say that we accept this view as we accept any other, so long as it will + help us, and we feel bound to retain it only so long as it will serve our + great purpose--the improvement of Man's estate and the widening of his + knowledge. The moment this, or any other conception, ceases to be useful + for these purposes, away with it to the four winds; we care not what + becomes of it! + </p> + <p> + But to say truth, although it has been my business to attend closely to + the controversies roused by the publication of Mr. Darwin's book, I think + that not one of the enormous mass of objections and obstacles which have + been raised is of any very great value, except that sterility case which I + brought before you just now. All the rest are misunderstandings of some + sort, arising either from prejudice, or want of knowledge, or still more + from want of patience and care in reading the work. + </p> + <p> + For you must recollect that it is not a book to be read with as much ease + as its pleasant style may lead you to imagine. You spin through it as if + it were a novel the first time you read it, and think you know all about + it; the second time you read it you think you know rather less about it; + and the third time, you are amazed to find how little you have really + apprehended its vast scope and objects. I can positively say that I never + take it up without finding in it some new view, or light, or suggestion + that I have not noticed before. That is the best characteristic of a + thorough and profound book; and I believe this feature of the "Origin of + Species" explains why so many persons have ventured to pass judgment and + criticisms upon it which are by no means worth the paper they are written + on. + </p> + <p> + Before concluding these lectures there is one point to which I must + advert--though, as Mr. Darwin has said nothing about man in his book, it + concerns myself rather than him;--for I have strongly maintained on sundry + occasions that if Mr. Darwin's views are sound, they apply as much to man + as to the lower mammals, seeing that it is perfectly demonstrable that the + structural differences which separate man from the apes are not greater + than those which separate some apes from others. There cannot be the + slightest doubt in the world that the argument which applies to the + improvement of the horse from an earlier stock, or of ape from ape, + applies to the improvement of man from some simpler and lower stock than + man. There is not a single faculty--functional or structural, moral, + intellectual, or instinctive, there--is no faculty whatever that is not + capable of improvement; there is no faculty whatsoever which does not + depend upon structure, and as structure tends to vary, it is capable of + being improved. + </p> + <p> + Well, I have taken a good deal of pains at various times to prove this, + and I have endeavoured to meet the objections of those who maintain, that + the structural differences between man and the lower animals are of so + vast a character and enormous extent, that even if Mr. Darwin's views are + correct, you cannot imagine this particular modification to take place. It + is, in fact, an easy matter to prove that, so far as structure is + concerned, man differs to no greater extent from the animals which are + immediately below him than these do from other members of the same order. + Upon the other hand, there is no one who estimates more highly than I do + the dignity of human nature, and the width of the gulf in intellectual and + moral matters which lies between man and the whole of the lower creation. + </p> + <p> + But I find this very argument brought forward vehemently by some. "You say + that man has proceeded from a modification of some lower animal, and you + take pains to prove that the structural differences which are said to + exist in his brain do not exist at all, and you teach that all functions, + intellectual, moral, and others, are the expression or the result, in the + long run, of structures, and of the molecular forces which they exert." It + is quite true that I do so. + </p> + <p> + "Well, but," I am told at once, somewhat triumphantly, "you say in the + same breath that there is a great moral and intellectual chasm between man + and the lower animals. How is this possible when you declare that moral + and intellectual characteristics depend on structure, and yet tell us that + there is no such gulf between the structure of man and that of the lower + animals?" + </p> + <p> + I think that objection is based upon a misconception of the real relations + which exist between structure and function, between mechanism and work. + Function is the expression of molecular forces and arrangements no doubt; + but, does it follow from this, that variation in function so depends upon + variation in structure that the former is always exactly proportioned to + the latter? If there is no such relation, if the variation in function + which follows on a variation in structure may be enormously greater than + the variation of the structure, then, you see, the objection falls to the + ground. + </p> + <p> + Take a couple of watches--made by the same maker, and as completely alike + as possible; set them upon the table, and the function of each--which is + its rate of going--will be performed in the same manner, and you shall be + able to distinguish no difference between them; but let me take a pair of + pincers, and if my hand is steady enough to do it, let me just lightly + crush together the bearings of the balance-wheel, or force to a slightly + different angle the teeth of the escapement of one of them, and of course + you know the immediate result will be that the watch, so treated, from + that moment will cease to go. But what proportion is there between the + structural alteration and the functional result? Is it not perfectly + obvious that the alteration is of the minutest kind, yet that, slight as + it is, it has produced an infinite difference in the performance of the + functions of these two instruments? + </p> + <p> + Well, now, apply that to the present question. What is it that constitutes + and makes man what he is? What is it but his power of language--that + language giving him the means of recording his experience--making every + generation somewhat wiser than its predecessor--more in accordance with + the established order of the universe? + </p> + <p> + What is it but this power of speech, of recording experience, which + enables men to be men--looking before and after and, in some dim sense, + understanding the working of this wondrous universe--and which + distinguishes man from the whole of the brute world? I say that this + functional difference is vast, unfathomable, and truly infinite in its + consequences; and I say at the same time, that it may depend upon + structural differences which shall be absolutely inappreciable to us with + our present means of investigation. What is this very speech that we are + talking about? I am speaking to you at this moment, but if you were to + alter, in the minutest degree, the proportion of the nervous forces now + active in the two nerves which supply the muscles of my glottis, I should + become suddenly dumb. The voice is produced only so long as the vocal + chords are parallel; and these are parallel only so long as certain + muscles contract with exact equality; and that again depends on the + equality of action of those two nerves I spoke of. So that a change of the + minutest kind in the structure of one of these nerves, or in the structure + of the part in which it originates, or of the supply of blood to that + part, or of one of the muscles to which it is distributed, might render + all of us dumb. But a race of dumb men, deprived of all communication with + those who could speak, would be little indeed removed from the brutes. And + the moral and intellectual difference between them and ourselves would be + practically infinite, though the naturalist should not be able to find a + single shadow of even specific structural difference. + </p> + <p> + But let me dismiss this question now, and, in conclusion, let me say that + you may go away with it as my mature conviction, that Mr. Darwin's work is + the greatest contribution which has been made to biological science since + the publication of the "Regne Animal" of Cuvier, and since that of the + "History of Development," of Von Baer. I believe that if you strip it of + its theoretical part it still remains one of the greatest encyclopaedias + of biological doctrine that any one man ever brought forth; and I believe + that, if you take it as the embodiment of an hypothesis, it is destined to + be the guide of biological and psychological speculation for the next + three or four generations. + </p> + <p> + END OF VOL. II + </p> +<pre xml:space="preserve">*** END OF THE PROJECT GUTENBERG EBOOK, DARWINIANA *** + +This file should be named 6919-h.txt or 6919-h.zip + +Project Gutenberg eBooks are often created from several printed +editions, all of which are confirmed as Public Domain in the US +unless a copyright notice is included. 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