Editkd uv ANDllKW LANG CHAELES DAE WIN BY GKANT ALLEN LONDON LONGMANS, GREEN, AND CO. 1885 ■ ill ri'jhti /t'served 3662 79 I'llIXTF.l) BY .'IPOTTISWOODI; AND CO., NKW-STUKET SQUAIM- PEEFACE -*»*- In tliis little volum(5 I havt^ eiulenvourod to present the litb uiul work of Charles Darwin viewed as a moment in a threat revolution, in due relation both to those who went belong and to those who come after him. Recog- nisin<^-, as has been well said, that the wave makes the crest, not the crest the wave, I have tried to let my hero fall naturally into his propter plac(> in a vast onward movement of the human intellect, of which he was liimself at once a splendid product and a moving cause of the hrst importance. I have attempted to show him both as receiving the torch from Lamarck and Malthus, and as passing it on with renewed brilliancy to the wide school of evolutionary thinkers whom his work was instrumental in arousing to fresh and viu'orous activitv along a thousand separate and varied lines of thought and action. As ]Mr, Francis Darwin wjis already engaged upon a life of his father, I should have shrunk from putting ^ iv Ph'i-F.tr/': fortli my own little hook if I liiul wA succeetlod in soonriniT Ix'foreliund liis kind .sanction. Tliat sanction, however, was at once so frankly and cordially j^-iven, that all my hesit.ation upon snch a score was innnediately laid aside : and as I have necessarilv had to deal rather with Darwin's position as a thinker and worker than with the hioLrraphical details of his private life, T trust the lesser book may not clash witli the jjfreater, hnt to some ext(Mit may snppleinent and ev(Mi illnstrate it. Treating my snhject mainly as a study in tlu' inter- action of organism and environment, it has been neces- sary for me frequently to introduce the names of living men of science side by side with some of those who have more or less recently passed away from among us. For uniformity's sake, as well as for brevity's, 1 have been conipelliMl, in every instance alike, to omit the customary conventiomil handles. I trust those who thus find themselves docked of their usual titles of respect will kindly remember that the practice is in fact adopted honorU cavxil ; they are paying prematurely the usual penalty of intellectual greatness. INfy obligations to l^rofessor Huxley, to JVof(\ssor Fiske, to Mr. IferlxM-t Spencer, to Professor Sachs, to Hermann iMiiller, to Dr. Krause, to Charles Darwin him- self, find to many other historians and critics of evolu- tionism, will be sufficiently obvious to all instructed l^h'I-.l'ACE V roatlcrs, and are for the most part fully acknowledprcd already in tlio text. It would be absurd to overload so small and po])ularly written a book with reference's and authorities. I hope, ther"fore, that any other writers to wlio!)! I may inadvertently have neglected to confess my debts will kindlv rest satisfied with this ovneral acknow- Icdgment. There are, however, three persons in par- ticular from whom I have so larufelv l)orrowed facts or ideas that I owe them more special and definite thanks. From ^Fr. WoodalTs admirable paper on Charles Dar- win, contributed to the 'Transactions of the Shropshire Arcluuological Society,' I have taken much interesting information about my hero's innnediate ancestry and early days. From Mr. Samuel iiutler, the author of ' F]volution Old and New," I have derived many preg- nant suggestions with regard to the true position and meaning of BufFon, V]rasmus Darwin, and t3ie early essentially teleological evolutionists — suggestions which 1 am all the more anxious \o acknowledge since I differ fundamentally from ^\v. ] hitler in his estimate of the worth of Charles Darwin's distinctive discovery of natnral selection. Fin.ally, to ^Er. Bates, the ' Xatnralist on the Amazons,' I am indebted for several valuable items of information as to the general workings of the pre-Darwinian evolutionary spirit. In a book dealing so largely with a contemporary vi Prefaci-: movomeiif, tlic history of wliicli has never V(>t been con- seciitively written down in full, or subjected as a whole to searchiiifjf criticism, tliere must prol)ably be many errors of detail, whicli can hardly be avoided under such circumstances. 1 have endeavoured to minimise them as far as possible. For those which may have escaped my own scrutiny I nnist trust both for correction and for indul<^'ence to the kindness of mv readers. CONTENTS CHAPTEr: I. THE WORLD INTO WHICH DARWIN WAS BORN . II. CHARLES DAUWIK AND HIS ANTECEDENTS . III, EARLY DAYS IV. DARWIN'S WANDER-YEARS V. THE PERIOD OF INCUBATION .... VI. THE ORIGIN OF SPECIES VII. THE DARWINIAN REVOLUTION BEGINS VIII. THE DESCENT OF MAN IX. THE THEORY OF COURTSHIP .... X. VICTORY AND REST XI. DARWIN'S PLACE IN THE EVOLUTIONARY MOVEMKNT XH. THE NET RESULT INDEX PAGE 1 20 31 38 r.s 73 112 132 IM i5r. 177 102 203 CHARLES DAE WIN. CHAFPER I. THE WORLD INTO WIIICII DAliWIN WAS BORN. Charles Darwin was a great man, and lie accomplished a great work. The Newton of biology, he found the science of life a chaotic maze : he left it an orderly system, with a definite plan and a recognisable meaning. Great men are not accidents ; great works are not accomplished in a single day. Both are the product of adequate causes. The great man springs from an ancestry competent to produce him ; he is the final flower and ultimate outcome of converging hereditary forces, that culminate at last in the full production of his splendid and exceptional personality. The great work which it is his mission to perform in the world is never wholly of his own inception. It also is the last effect of antecedent conditions, the slow result of ten- dencies and 'ideas long working unseen or but little noticed beneath the surface of opinion, yet all gradually conspiring together towards the definitive revolution at whose head, in the fulness of time, the as yet unborn genius is destined to place himself. This is especially B 2 Charles Darwin the case with those extraordinary wa\es of mental upheaval, one of which gave us the Italian renaissance, and another of which is actually in progress around us at the present day. They have their sources deep down in the past of human thought and human feeling, and they are themselves but the final manifeotation of innumerable energies which have long been silently agi- tating the souls of nations in their profoundest depths. Thus, every great man may be regarded as possess- ing two distinct lines of ancestry, physical and spiritual, each of which separately demands elucidation. He owes much in one way to his father and his mother, his grandfathers and his grandmothers, and his remoter progenitors, from some or all of whom he derives, in varying degrees and combinations, the personal qualities whose special interaction constitutes his greatness and his idiosyncrasy ; he owes much in another way to his intellectual and moral ancestors, the thinkers and workers who have preceded him in his own department of thought or action, and have made possible in the course of ages the final development of his special revo- lution ©r his particular system. Viewed as an indivi- dual, he is what he is, with all his powers and faculties and potentialities, in virtue of the brain, the frame, the temperament, the energy he inherits directly from his actual ancestors, paternal and maternal ; viewed as a factor or element in a great movement, he is what he is because the movement had succeeded in reachinof such and such a point in its progress already without him, and waited only for such and such a grand and commanding personality in order to carry it yet a step fiulliej' on its course of development. The World into which Darwin was Born 3 No man who ever lived would more cordially have recognised these two alternative aspects of the great worker's predetermining causes than Charles Darwin. He knew well that the individual is the direct cumulative product of his physical predecessors, and that he works and is worked upon in innumerable ways by the particular environment into whose midst he is born. Let us see, then, in his own case what were these two main sets of conditioning circumstances which finally led up to the joint production of Charles Darwin, the man and the philosopher, the thinking brain and the moving energy. In other words, what was the state of the science of life at the time when he first began to observe and to speculate ; and what was the ancestry which made him be born a person capable of helping it forward at a single bound over its great restricting dogmatic barrier of the fixity of species ? Let us begin, in the first place, by clearing the path beforehand of a popular misconception, so extremely general and almost universal that, unless it be got ritl of at the verv outset of our sketch, much of the real scope and purport of Darwin's life and work nuist, of necessity, remain entirely misunderstood by the vast mass of English readers. In the public mind Darwin is, perhaps, most connnonly regarded as the discoverer and founder of the evolution hypothesis. Two ideas are usually associated with his name and memory, if is believed that he was the first propounder of the theory which supposes all plant and animal forms to be the result, not of special creation, but of slow modification ia pre-existent organisms. It is further and more particularly believed that he was the fiibt B 2 4 Charles Dariv/n propounder of the theory which supposes the descent of man to be traceable from a remote and more or less monkey-like ancestor. Now, as a matter of fact, Darwin was not the prime originator of either of these two great cardinal ideas. Though he held both as part of his organised theory of things, he was not by any means the first or the earliest thinker to hold them or to propound them publicly. Though he gained for them both a far wider and more general acceptance than they had ever before popularly received, he laid no sort of claim himself to originality or proprietorship in either theory. The grand idea which he did really originate was not the idea of ' descent with modifica- tion,' but the idea of ' natural selection,' by which agency, as he was the first to prove, definite kinds of plants and animals have been slowly evolved from simpler forms, with definite adaptations to the special circumstances by which they are surrounded. In a word, it was the peculiar glory of Charles Darwin, not to have suggested that all the variety of animal and vegetable life might have been produced by slow modi- fications in one or more original types, but to have shown the nature of the machinery by which such a result could be actually attained in the practical working out of natural causes. He did not invent the develop- ment theory, but he made it believable and comprehen- sible. He was not, as most people falsely inuigine, the Closes of evolutionism, the prime mover in the biological revolution ; he was the Joshua who led the world of thinkers and workers into full fruition of that promised land which earlier investigators had but dimly descried from the Pisgah-top of conjectural speculation. The World into which Darwfn ivas Born 5 How far Darwin's special idea of natural selection supplemented and rendered credible the earlier idea of descent with modification we shall see more fully when we come to treat of the inception and growth of his great epoch-making work, ' The, Origin of ri)ecies ; ' for the present, it must suffice to point out that in the world into which he was born, the theory of evolution already existed in a more or less shadowy and un- developed shape. And since it was his task in life to raise this theory from the rank of a mere plausible and happy guess to the rank of a highly elaborate and almost universally accepted biological system, we may pause awhile to consider on the threshold what was the actual state of natural science at the moment when tlie great directing and organising intelligence of Charles Darwin first appeared. From time immemorial, in modern Christendom at least, it had been the general opinion of learned and simple alike that every species of plant or animal owed its present form and its original existence to a distinct act of special creation. This nn'ff belief, unsupported as it was by any sort of internal evidence, was supposed to rest directly upon the express authority of a few obscure statements in the Book of Genesis. The Creator, it was held, had in the beginning formed each kind after a particular pattern, had endowed it with special organs devised with supreme wisdom for subserving special functions, and had bestowed upon it the mystical power of reproducing its like in its own image to all generations. No variation of importance ever occurred within the types thus constituted ; all plants and animals always retained their special forms unaltered in any 6 Charles Darwin way from era to era. This is the doctrine of the fixity and immutability of species, almost universal in the civilised world up to the end of the last century. Improbable as such a crude idea now seems to any person even moderately acquainted with the extra- ordinary variety and variability of living forms, it nevertheless contained nothing at all likely to con^ tradict the ordinary experience of the everyday observer in the last century. The handful of plants and animals with which he was personally acquainted consisted for the most part of a few large, highly advanced, and well-marked forms, not in the least liable to be mistaken for one another even by the most hasty and casual spectator. A horse can immediately be discriminated by the naked eye from fi donkey, and a cow from a sheep, without risk of error; nobody is likely to confuse wheat with barley, or to hesitate between classing any given fruit that is laid before him as a pear or an apple, a plum or a nectarine. Variability seldom comes under the notice of the ordinary passing spectator as it does under that of the prying and curious scientific observer ; and when it comes at all, as in the case of dogs and pigeons, roses and hyacinths, it is no doubt set down carelessly on a superficial view as a mere result of human selection or of deliberate mongrel interbreed- ing. To the eye of the average man, all the living objects ordinarily perceived in external nature fall at once under certain fixed and recognisable kinds, as dogs and horses, elms and ashes, whose limits he is never at all inclined to confound in any way one with the other. LinnaBus, the great father of modern scientific The World into which Darwin was Born 7 biology, had frankly and perhaps unthinkingly accepted this current and almost universal dogma of the fixity and immutability of species. Indeed, by defining a kind as a group of plants or animals so closely resembling one another as to give rise to the belief that they might all be descended from a single ancestor or pair of ancestors, he implicitly gave the new sanction of his weighty authority to the creation hypothesis, and to the pre- valent doctrine of the unchangeability of organic forms. To Linnasus, the species into which he mapped out all the plants and animals then known, appeared as the descendants each of a solitar^^ progenitor or of a primitive couple, called into existence at the beginning of all things by the direct fiat of a designing Creator. He saw the world of organic life as composed of so many well-demarcated types, each separate, distinct, and immutable, each capable of f)rodncing its like adi injinitum, and each unable to vary from its central standard in any of its individuals, except perhaps within very narrow and unimportant limits. But towards the close of the eighteenth century, side by side with the general awakening of the human intellect and the arrival of a new era of free social investigation, which culminated in a fresh order of things, there was developed a more critical and sceptical attitude in the world of science, which soon produced a notable change of front among thinking naturalists as to the origin and meaning of specific distinctions. Buffon was the first great biological innovator who ventured, in very doubtful and tentative language, to suggest the possibility of the rise of species from one 8. Charles Darwin another by slow modification of ancestral forms. Essen- tially a popular essayist, writing in the volcanic priest- suppressed France of the aucien rer/imc, during the inconsistent days of Louis XA\ and T.ouis XVI., when it was uncertain whether novel and heterodox opinions would bring down upon their author fame and reputa- tion or tlie Sorbonne and the Bastille, BufFon was careful to put his conjectural conclusions in a studiously guarded and often even ironical form. But time after time, in his great discursive work, the ' Histoire Natu- relle ' (published in successive volumes between 1 749 and 1788), he recurs anew to the pregnant suggestion that plants and animals may not be bound by fixed and immovable limits of species, but may freely vary in everv direction from a connnon centre, so that one kind may gradually and slowly be evolved by natural causes from the type of another. He points out that, under- lying all external diversities of character and shape, fundamental likenesses of type occur in many animals, which irresistibly suggest the novel notion of conmion descent from a single ancestor. Thus regarded, he says, not only the ass and the horse (to take a parti- cular passage) but even man himself, the monkeys, the quadrupeds, and all vertebrate animals, might be viewed as merely forming divergent branches of one and the same great family tree. Every such family, he believed, whether animal or vegetable, might have sprung ori ginally from a single stock, which after many gener- ations had here developed into a higher form, and there degenerated into a lower and less perfect type of organisation. Granting this — granting that nature could by slow variation produce one species in the The World into which Darwin was Born g course of direct descent from nnotlier niilike it (for example, tlie ass from the horse), then, Buffon observed, tliere was no further limit to be set to her powers in this respect, and we might reasonably conclude that from a single primordial being she has gradually been able in the course of time to develop the whole con- tinuous gamut of existing animal and vegetable life. To be sure, BufFon always saves himself from censure by an obvious afterthought — ' But no ; it is certain from revelation that every species was directly created by a separate fiat.' This half-hearted and somewhat subrisive denial, however, must be taken merely as a concession to the Sorbonne and to the fashionable exegesis of liis own day ; and, even so, the Sorbonne was too much in the end for the philosophic thinker. He had once in his life at least to make his submission and demand pardon from the offended orthodoxy of the Paris faculty. The wave of thought and feeling, thus apologetically and tentatively stirred on the unruffled pond of eighteenth century opinion by the startling plop of Buffon's little smooth-cut pebble, soon widened out on every side in concentric circles, and affected with its wash the entire world of biological science in every country. Before the close of the eighteenth century speculation as to the origin of species was rife in all quarters of Europe. In France itself, Geoffroy St. Hilaire, constitutionally cautious and undecided, but wide of view and free from prejudice, came slowly to the conclusion, in 1795, that all species are really derived by modification from one or more primitive types. In Germany, in the very same year, Goethe, 10 Charles Darwin with the keen vision of the poet and the calm eye of the philosopher uniquely combined, discerned indepen- dently as by a lightning flash the identical idea of the origin of kinds by modification of pre-existent organisms. ' We may assert without hesitation,' says that great nebulous thinker and observer, ' that all the more perfect organic natures, such as fishes, amphibians, birds and mammals, with man at their head, were formed at first on one original type, which still daily changes and modifies its form by propagation.' In England, twelve months earlier, Dr. Erasmus Darwin, Charles Darwin's grandfather (of whom more anon), published his '• Zoonomia,' a treatise on the laws of animal life, in which he not only adopted Button's theory of the origin of species by evolution, but also laid down as the chief cause of such development the actions and needs of the animals themselves. According to Dr. Erasmus Darwin, animals came to vary from one another chiefly because they were always altering their habits and voluntarily accommodating themselves to new actions and positions in life. His v/ork produced com- paratively little effect upon the world at large in his own time, but it had immense influence upon the next great prophet of evolution, Lamarck, and through Lamarck on Lyell, Charles Darwin, Herbert Spencer, jmd the modern school of evolutionists generally. We shall consider his views in greater detail when we pass from the spiritual to the j)liysical antecedents of Charles Darwin. It was in 1801 that Lamarck first gave to the world his epoch-making speculations and suggestions on the origin of species ; and from that date to the day of his The World into which Darwin w.is Born ii death, in 1831, the unwearied old philosopher continued to devote his whole time and energy, in blindness and poverty, to the elucidation of this interesting and im- portant subject. A bold, acute, and vigorous thinker, trained in the great school of Diderot and D'Alembert, with something of the vivid Celtic poetic imagination, iuid a fearless habit of forming his own conclusions irrespective of common or preconceived ideas, Lamarck went to the very root of the matter in the most deter- mined fashion, and openly proclaimed in the face of frowning officialism under the Napoleonic reaction his profound conviction that all species, including man, were descended by modification from one or more primordial forms. In Charles Darwin's own words, ' He first did the eminent service of arousing attention to the probability of all change, in the organic as well as in the inorganic world, being the result of law and not of miraculous interposition. Lamarck seems to have been chiefiy led to his conclusion on the gradual change of species by the difficulty of distinguishing species and varieties, by the almost perfect gradation of forms in certain groups, and by the analogy of domestic productions. With respect to the means of modifica- tion, he attributed something to the direct action of the physical conditions of life, something to the crossing of already existing forms, and much to use and disuse, that is, to the effects of habit. To this latter agency he seems to attribute all the beautiful adaptations in nature — such as the long neck of the giraffe for browsing on the branches of trees.' He believed, in short, that animals had largely developed themselves, by functional effort followed by increased powers and abilities. 12 Charles Darwin Lamarck's great work, the ' Philosophie Zoologique/ thonufh opposed by the austere and formal jj^eniua of the immortal Cuvier — a reactionary biolofjical conservative and obscurantist, equal to tlie enormous task of map- ping out piecemeal with infinite skill and power the separate provinces of his chosen science, but incapable of taking in all the bearings of ^he whole field at a single vivid and comprehensive sweep — Lamarck's great work produced a deep and lasting impression upon the entire subsequent course of evolutionary thought in scientific Europe. True, owing to the retrograde tendencies of the First Empire, it caused but little immediate stir at the precise moment of its first publica- tion ; but the seed it sowed sank deep, and, lying fallow long in men's minds, bore fruit at last in the next gener- ation with the marvellous fecundity of the germs of genius. Indeed, from the very beginning of the present century, a ferment of inquiry on the subject of creation and evolution was everywhere obvious among speculative thinkers. The profound interest which Goethe took in the dispute on this very subject in the French Academie des Sciences between Cuvier and Geoffrov St. Hilaire, amid the thundering guns of a threatened European convulsion, was but a solitary symptom of the general stir which preceded the gestation and birth of the Dar- winian hypothesis. It is impossible to take up any scientific memoirs or treatises of the first half of our own century without seeing at a glance how every mind of high original scientific importance was permeated and disturbed by the fundamental questions aroused, but not fully answered, by Buffon, Lamarck, and Erasmus Darwin. In Lyell's letters and in Agassiz's lectures, in The World into which Dan win was Born 13 tho ' Botanic Journal ' and the ' Philosophical Transac- tions,' in treatises on Madeira beetles and the Australian flora, we find everywhere the thoughts of men pro- foundly influenced in a thousand directions by this universal evolutionary solvent and leaven. And while the world of thought was thus seething and moving restlessly before the wave of ideas set in motion by these various independent philosophers, another group of cautjs in another field was rendering smooth the path beforehand for the future champion of the amended evolutionism. Geology on the one hand and astronomy on the other were making men's minds gradually familiar with the conception of slow natural development, as opposed to immediate and miraculous creation. The rise of geology had been rapid and brilliant. In the last century it had been almost universally believed that fossil organisms were the relics of sub- merged and destroyed worlds, strange remnants of successive terrible mundane catastrophes. Cuvier I'imself, who had rendered immense f vices to geo- logical science by his almost unerring reconstructions of extinct animals, remained a partisan of the old theory of constant cataclysms and fresh creations throughout his whole life ; but Lamarck, here as else- where the prophet of the modern uniforniitarian con- cept of nature, had already announced his grand idea that the ordinary process of natural laws sufficed to account for all the phenomena of the earth's crust. In England, William Smith, the ingenious land surveyor, riding up and down on his daily task over the face of the country, became convinced by his obser\utionb iu 14 Charles Darwin the first years of the present century that a fixed order of sequence could everywhere be traced anion «^ tlie various superincumbent ^man- kiud. In others it has accjuired chuvs or talons, as in tigers and eagles. In others, toes with an intervening web or niendjrane, as in seals find geese. In others it has aef[uired cloven hoofs, as in cows and swine ; and whole hoofs in others, as in the horse : while in the bird kind this original living filament has pnt forth wings instead of arms or legs, and feathers instead of Iniir.' This is a very crude form of evolutionism indeed, but it is leading up by gradual stages to the finished and all-sided philosophy of physical life, which at last definitely formulates itself through the mouth of Charles Darwin. We shall see hereafter wherein JOrasmus Darwin's conception of devel(jpment chielly failed — in attributing evolution for the most part to the exertions and endeav^ours of the anininl itself, rather than to inevitable survival of the fittest among innu- merable spontaneous variations — but we must at least conclude our glimpse of his pregnant and suggestive work by quoting its great fundamental ape^u : — ' As the earth and ocean were probably peopled with vege- table productions long before the existence of animals, and many families of these animals long before other families of them, shall we conjecture that one and the same kind of living filament is and has been the cause of all organic life ? ' A few lines from the ' Temple of Nature,' one of Erasmus Darwin's poetic rhapsodies, containing his fully matured views on the origin of living creatures, may be worth reproduction in further elucidation of his philosophical position : — C//ARf.F.s Darwin and ///s Axt/'X-I'Idexts 25 ' Organic life beneath the shoreless waves Was born, and nnrsed in ocean's pearly caves ; ( First forms minute, unseen by spheric in<^ and classifying the aninuils and plants he had brought home with him, the germs of those inquiring ideas about the origin of species which we have already observed in his account of the voyage were quickening into fresh life within him. As he ruminated at his leisure over 6o CiiARLRs Darwin the results of liis accumnlationsi, he was beginning to work upon tlie great problem with the definite and conscious resolution of solving it. ' On my return home, it occurred to me,' he says, ' in 1 8o7, that some- thing might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it. After five years' work, I allowed myself to speculate on the subject, and drew up some short notes ; these I en- larged in 18'tl' into a sketch of the conclusions that then seemed to me probable ; from that period to the present day [1 859] 1 have steadily pursued the same object. I hope that I may be excused for entering on these personal details, as I give them to show tluit I have not been hastv in coming to a decision.' So Darwin wrote at fifty. The words are weighty and well worthy of consideration. They give us in a nutshell the true secret of Darwin's success in compel- ling the attention and assent of his contemporaries to his completed theory. For speculations and hypotheses like those of Lamarck and Erasmus Darwin, however brilliant and luminous they may be, the hard, dry, scientific mind cares as a rule less than nothing. Men of genius and insight like Goethe and Oken may, indeed, seize greedily upon the pregnant suggestion ; their intellects are already attuned by nature to its due reception and assimilation ; but the mere butterfly- catchers and plant-hunters of the world, with whom after all rests ultimately the practical acceptance or rejection of such a theory, can only be convinced by long and patient accumulations of facts, by infinite instances and endless examples, by exhaustive surveys s The Period of Incubation 6i of the whole field of nature in a thousand petty details piecemeal. They have to be driven by repeated beating into the right path. Everywhere they fancy they see the loophole of an objection, which must be carefully closed beforehand against them with anticipatory argument, as we close hedges by the wayside against the obtrusive donkev with a cautious bunch of thorny brambles. Even if Charles Darwin had liit upon the fundamental idea of natural selection, and had published it, as Wallace did, in the form of a mere splendid apcr(iii, he would never have revolutionised the world of biology. When the great discovery was actually promulgated, it was easy enough to win the assent of philosophical thinkers like Herbert Spencer ; easy enough, even, to gain the ready adhesion of non- biological but kindred minds, like Leslie Stephen's and John Morley's ; those might all, perhaps, have been readily convinced by far less liea\y and crushing artillery than that so triumphantly marshalled together in the ' Origin of Species.' But in order to command the slow and grudging adhesion of the rank and file of scientific workers, the ' hodmen of science,' as Professor Huxley calls them, it was needful to bring together an imposing array of closely serried facts, to secure every post in the rear before taking a single step onward, and to bring to bear upon every antjigonist the exact form of arorument with which he was alreadv thorouo-hlv familiar. It was by carefully pursuing these safe and cautious phi- losophical tactics that Charles Darwin gained his great victory. Where others were pregnant, he was cogent. He met the Dryasdusts of science on their own ground, and he put them fairly to flight with their own weapons. 62 Charles Darwin More than that, he brought them all over in the long run as deserters into his own camp, and converted them from doubtful and suspicious foes into warm adherents of the evolutionary banner. Moreover, fortunately for the world, Darwin's own mind was essentially one of the inductive type. If a great deductive thinker and speculator like Herbert Spencer had hit upon the self-same idea of survival of the fittest, he might have communicated it to a small following of receptive disciples, who would have under- stood it and accepted it, on a imori grounds alone, and gradually passed it on to the grades beneath them ; but he would never have touched the slow and cautious elephantine intellect of the masses. The common run of mankind are not deductive ; they require to have everything made quite clear to them by example and instance. The English intelligence in particular shows itself as a rule congenitally incapable of appreciating the superior logical certitude of the deductive method. Englishmen will not even believe that the square on the hypotenuse is equal to the squares on the containing sides until they have measured and weighed as well as they are able by rude experimental devices a few selected pieces of rudely shaped rectangular paper. It was a great gain, therefore, that the task of reconstructing the course of organic evolution should fall to the lot of a highly trained and masterly intelligence of the in- ductive order. Darwin had first to convince himself, and then he could proceed to convince the world. He set about the task with characteristic patience and thoroughness. No man that ever lived possessed in a more remarkable degree than he did the innate capacity The Period oe Incubation 63 for taking trouble. For five years, as a mere pre- liminary, he accumulated facts in immense variety, and then for the first time and in the vaguest possibk> way he ' allowed himself to speculate.' That brings us down to the year 1842, when the first notes of the ' Origin of Species ' must have been tentatively committed to paper. It was in 1859 that the first edition of the complete work was given to tlie world. Compare this with the case of Newton, who similarly kept his grand idea of gravitation for many years in embrj^o, until more exact measurements of the moon's mass and dis- tance should enable him to verify it to his own satis- faction. One other item of immense importance in the genesis of the full Darwinian doctrine deserves mention here — I mean, the exact moment of time occupied by Charles Djirwin in the continuous history of scientific thought. A gener ion or two earlier, in Erasmus Darwin's days, biology had not yet arrived at the true classification of animals and plants upon an essentially hereditary basis. The LinnoDan arrangement, then universally accepted, was wholly artificial in its main features ; it distributed species without regard to their fundamental likenesses of structure and ory-auisation. But the natural svstem of Jussieu and De CandoUe, by arranging plants into truly related groups, made possible the proofs of an order of affiliation in the vegetable kingdom ; while Cuvier's similar reconstruction of the animal world gave a like foothold to the evolutionary philosopher in the other great department of organic nature. The recognition of kinship between the various members of the same family necessarily preceded the establish- 64 Charles Darwin ment of a regular genealogical theory of life in its entirety. Though we are here concerned mainly with Charles Darwin the thinker and writer — not with Charles Darwin the husband and father — a few words of explanation as to liis private life must necessarily be added at the present point, before we pass on to consider the long, slow, and cautious brewing of that wonderful work, the ' Origin of Species.' Darwin returned home from the voyage of the ' Beagle ' at the end of the year 183G. Soon after, he was elected a Fellow of the Royal Society, no doubt through the influence of his friend Lyell, who was quite enthusiastic over his splendid geological investigations on the rate of elevation in the Pampas and the Cordillera. Acting on Ly ell's advice, too, he determined to seek no official appointment, but to devote himself entirelv for the rest of his life to the pursuit of science. In 1838, at the age of twenty-nine, he read before the Geological Society his paper on the ' Connection of Volcanic Phenomena with the Elevation of Mountain Chains,' when, says Lyell admiringly in a private letter, ' he opened upon De la Beche, Phillips, and others ' — tlie veterans of the science — ' his whole battery of the earthquakes and volcanoes of the Andes.' Shortly after, the audacious young man was appointed secretary to the Geological Society, a post which he filled when the voyage of the ' Beagle ' was first pub- lished in 1839. In the earlj' part of that same year, the rising naturalist took to himself a wife from one of the houses to which he himself owed no small part of his conspicuous greatness. His choice fell upon his cousin, The Period of iKcrnATioN 65 j\liss Kininu Wedo^wood, dang'hter of Jusiali "Wedgwood, of Maer Hall; and, after tlnve yeai's of married life in London, lie settled at last at Down House, near Orpino-- ton, in Kent, where for the rest of his days he passed his time amon^- his conservatories and his pigeons, his (••arden and liis fowls, with liis children growing up quietly heside him, and the great thinking world of Loudon within easy reach of a few minutes' journey. J lis ]")rivfite means enabled him to live the pleasant life of an hhiglish country gentleman, and devote himself unremittingly to the pursuit of science. HI health, indeed, interfered sadly with his powers of work ; but system and patience did wonders during his working days, which were regularly ]iarcelled out between study and recreation, and utilised and economised in the very higliest possible degree. Early to bed and early to rise, wandering unseen among the lanes and paths, or riding slowly on his fa\'ourite black cob. the great naturalist passed forty years happily and usefully at Down, where all the village knew and loved him. A man of singular simplicity and largeness of heart, Charles Darwin never reallv learnt to know his own greatness. And that charming innocence and ignorance of his real value made the value itself all the greater. His moral qualities, indeed, were no less admirable and unique in their way than his intellectual faculties. To that charming candour and delightful unostentatious- ness which everybody must have noticed in his published writings, he united in private life a kindliness of dis- position, a width of sym]:)athy, and a ready generosity which made him as much beloved by his friends as he was admired and respected by all Europe. The very F 66 Charles DakwiS' sprvnnts wlio caine heneatli his roof stopped tliere for the most part (hirin<»' tlieir wliole lifetime. In Ids earlier years at Down, the quiet Kentisli home was constantly enlivened by the visits of men like liyell, Huxley, Hooker, Lubbock, and Wollaston. Durinpf his later days, it was the Mecca of a world-wide scientific and philosophic pilj^rimage, where all the greatest men our age has produced sought at times the rare honour of sitting before the face of the immortal master. J3nt to the very last Darwin himself never seemed to dis- cover that he was anything more than just an average man of science among his natural ]ieers. Shortlv after Darwin went to Down he beo-an one long and memorable experiment, which in itself casts a Hood of light upon his patient and painstaking method of inquiry. '^i\vo years before, he had read at the Geo- logical Society a paper on the ' Formation of ]\rould,' which more than thirty years later he expanded into his famous treatise on the ' Action of Earthworms.' His uncle and father-in-law, Josiah Wedgwood, sug- gested to him that the apparent sinking of stones on the surface might really be due to earthworm castings. So, as soon as he had some land of his own to experi- ment upon, he began, in 181-2, to spread broken chalk over a held at Down, in which, twenty-nine years later, in 1871, a trench was dug to test the results. "What other naturalist ever waited so long and so patiently to discover the upshot of a single experiment ? Is it wonder- ful that a man who worked like that should succeed, not by faith but by logical power, in removing mountains ? Unfortunately, we do not know the exact date when Darwin tirst read JMalthus. l^ut that the perusal of TiiR Period of Ixcuiiat/om 6y tliut reiiiark{i])le book fonneil a crisis and turning-point in his muntal development we know from his own distinct statement in a letter to llaeckel, prefixed to tlie brilliant German evolutionist's ' Historv of Creation.' t.' ' It seemed to me probable,' says Darwin, speaking of his own early development, ' that allied species were descended from a common ancestor. Rut during several years I could not conceive how each form could have been modified so as to become admirably adapted to its place in nature. I began therefore to study domesti- cated animals and cultivated plants, and after a time perceived that man's power of selecting and breeding from certain individuals was the moat powerful of all means in the production of new races. Having attended to the habits of animals and their relations to the sur- rounding conditions, I was able to realise the severe struggle for existence to which all organisms aiv sub- jected ; and my geological observations had allowed me to appreciate to a certain extent the duration of past geological periods. With my luind thus prepared 1 fortunately happened to read Maltlms's '' h]ssay on Popu- lation ; " and the idea of natural selection through the struggle for existence at once occurred to me. Of all the subordinate points in the theory, the last which 1 under- stood was the cause of the tendencv in the descerulants from a common progenitor to diverge in character." It is impossible, indeed, to overrate the importance of Malthus, viewed as a schoolmaster to bring men to Darwin, and to bring l^arwin himself to the truth. Without the " l']ssay on the Principle of Poi)ulation " it is quite conceivable that we should never have had the ' Origin of Species ' or the ' Descent of Man.' V 2 68 Char I. lis Darwin , At the same time, Darwin liad not been idle in other departments of scientific work. Side by side with liis collections for his final effort he had been busy on his valuable treatise upon Coral lleefs, in which he proved, mainly from his own observations on the Keelin*^ archipelago, that atolls owe their origin to a subsidence of the supporting ocean-floor, the rate of upward growth of the reefs keeping pace on the whole with the gradual depression of the sea-bottom. ' No more admirable example of scientific method,' says Professor Geikie forty years later, ' was ever given to the world ; and even if he had written nothing else, this treatise alone would have placed Darwin in the very front of investi- gators of nature.' But, from our present psychologicd and historical point of view, as a moment in the de- velopment of Darwin's influence, and therefore of the evolutionary impulse in general, it possesses a still greater and more profound importance, because the work in which the theory is unfolded forms a perfect masterpiece of thorough and comprehensive inductive method, and gained for its author a well-deserved repu- tation as a sound and sober scientific in([uirer. ^Hie ac- quisition of such a reputation, afterwards increased by the publication of the monograph on the Family Cirripediu (in 1851), proved of immense use to Charles Darwin in the fierce battle which was to rage around the uncon- scious body of the ' Origin of Species.' To be ' sound ' is everywhere of incalculable value ; to have approved one- self to the slow and cautious intelligence of the Phillstini' classes is a mighty spear and shield for a strong man ; but in England, and above all in scientific England, it is absolutely indispensable to the thinker who would TiiF Pi-Rinn m- Ixrun.-rrin.v 6() iiecomplish ?iiiy great ivvolutioii. Souii(lnt'ss is to tlie world of science what respectal)ility is to the world of business — the sine 'ji((i noii for successfully gaining even a liearing from esttiblished personages. To read the book on Coral Reefs is indeed to take a lesson of the deepest value in applied inductive canons. I'iVcrv fact is dulv nuirshalled : everv conclusion is drawn by the truest and most legitimate process from careful observation or crucial experiment, l^it by bit, Darwin shows most admirably that, through gradual submergence, fringing reefs are developed into barrier- reefs, and these again into atolls or hagoon ishmds ; and incideritallv he throws a vivid li<>-ht on the slow secular movements upward or downward for ever taking place ill the world's crust. But the value of the work as a geological record, great as it is, is as nothing compared with its value as a training exercise in inductive logic. Darwin was now learning by experience how to use his own immense powers. Meanwhile, the e>nvironment too had been gradually moviuo-. In 18o2,the vear after vouni? Darwin set out upon his cruise, Lyell published the tirst edition of his 'Principles of Geology," establishing once for all the uniformitarian concept of that branch of science, in I80G, the 3'ear when he returned, Ilatin(^s(jue, in his 'New Flora of North America,' had accepted within certain cramping limits the idea that ' all species might once have been vai'ieties, and that niiinv varieties are gradually becoming species by assuming constant and peculiar characters.' Haldeman in Boston, and Grant at University College, Ijondon, were teaching from their professorial chairs the self-same novel and revolutionary 70 CiiARi Hs Darwin (.locti'iiic. At last, ill I 8 It, Robi'rt CliaiiiLcrs ])iil)lislu'(l aiionyiiiously liis f'aiiioiis niid imicli-dt'batt'd " Vesti<^es of Civation,' wliicli l^rou^-lit down tlio (|nestifm of evolu- tion /v/•.s•/^s• creation from tlie senate ()f sardnfs to the arena of tlie mere general public, and set up at once a uin'versal fever of iiuinirv into the mysterious {piHstion of the origin of species. (Jluunbers himself was a man rather of general knowltnln-c and some native philo- sophical insight than of any marked scientific accuracy or depth. His work in its original form displayed comparatively little acfjuaintance with the vast ground- work of the qnestion at issue — zoological, botanical, geological, and so forth — and in Charles Diirwin's own opinion showed ' a great wiint of scientiiic caution.' But its graphic style, its vivid pictnres([ueness, and to the world at large the startling novelty of its brilliant and piquant suggestions, made it burst at once into an unwonted popularity for a work of so distinctly philo- sophical a character. In nine years it leaped rapidly through no less than ten successive editions, and re- mained until the publication of the ' Origin of Species ' the chief authoritative exponent in England of the still struggling evolutionary principle. The 'Vestiges of Creation' may be snccinctly de- scribed as Lamarck and wati^r, the waterv element being due in part to the unnecessary obtrusion (more Srofiiuj^ of a metaphysical and theological principle into the physical universe. Chambers himself, in his latest edition (before tlie book was finally killed by the advent of Darwinism), thus briefly describes his main concepts : ' The several series of animated beings, from the simplest and oldest up to the highest and most recent, are, nnder Till-: J^jiRjDi) OF iNcuiiAiioyj 71 tilt' jinwidt'iicc of (!otl, the rt'sults, ///w/, of an im])iilse wliirli has been iin])}U'tt'(l to tlic tonus of lite, atlvjineing tlii'iii, ill tlctiiiitr tiiiu's, by ^'t'licriitioii, through grmles of organisation, tcniiinating in flic highest ilicotyh'doiis and verte))rata, these grades being few in nninber, and generally marked by intervals of organic character, which we find to be 'a practical ditliculty in ascertaining atlinities; Kn-diiil, of another ini[)nlse connected witli the vital forces, tending, in the course of generations, to modifv oi'ganic structures in accordance with external circumstances, as food, the nature of the habitat, and the meteoric agencies.' Now it is clear at once that these two supposed ' impulses * are really (juite miracu- lous in their essence. They do not help us at all to a distinct physical and realisable conception of any natural agency whereby species became differentiated one from the other. 'I'hey lay the whole burden of s])ecies- iiiaking u])on a single primordial su])ernatural im])etus, imparted to the first living germ by the will of the Creator, and acting ever since continuously it is true, but none the less miraculously for all that. For many- creations Chambers substitutes one single long creative nisus : where Darwin saw natural selection, his Scotch predecessor saw a d(;its t\c itiacJtina, helping on the course of organic development by a constant but unseen interference from above, lie supposed evolution to be predetermined by some intrinsic and externally im- planted proclivity. In short, Chambers's theory is fjamarck's theologised, and spoilt in the process. The book had nevertheless a most prodigious and perfectly unprecedented success. I'he secret of its authorship was keenly debated and jealously kept, 'flie 72 Charles Darwin most ridiculous surmises .o,s to its anonvmous oriu-iii were everywhere atlout. Some attributed it to Thackeray, and some to Prince Albert, some to Lyell, some to Sir John Herschel, and some to Charles Darwin himself. Obscurantists thought it a wicki'd book; 'intellectual" people thought it an advanced book. As a matter of fact it was neither the one nor the other. It was just a pale and colourless transcript of the old familiar teleolojj'ical Lamarckism. Vet it did good in its generation. The pul)lic at large were induced by its ephemei'al vogue to interest themselves in a question to which they had never previously given even a passing thought, though more practised biologists of evolutionary tendencies were grieved at heart that evolution should first have IxnMi popularly presented to the English world under so unscientific, garbled, and nnitilated a form. From tlu^ ])hilosophic side, Herbert Spencei' found 'this ascri]ition of organic evolution to some aptitude naturally possessed by organisms or miracu- lously imposed upon them ' to be ' one of those explana- tions which explain nothing — a shaping of ignorance into the semblance of knowledge. 'The cause assigned,' he says, ' is not a true cause — not a cause assimilable to known causes — not a cause that can be anvwhere shown to produce analogous effects. It is a cause un- rejirest'iitable in thought : one of those illegitinuite symbolic conceptions which cannot by any mental pro- cess be elaborated into a real conception.' From the scientific side, on the other hand, Djirwin felt sadlv the inaccuracy and want of profound technical knowledge everywhere displayed by the anonymous author. These tilings might natunilly cause the enemy to blaspheme, Tin: Pr.Rinn of /.yrr//i,tr/(Ky / .•) Xo worse calaiuity, indeed, can Imppeii to ;i o-reat tnitli than for its defence to be intrusted to inetlicient luinds. Nevertheless, long after, in the *()riu-in of Species,' the great naturalist wrote with generous appreciation of the ' Wstiges of Creation,' ' Jn my own opinion it has (lone excellent service in this country in calling attention to the subject, in removing prejudice, and in thus pre- paring the ground for the reception of analogous views.' Still Darwin gave no sign. A iiaccid, cartihiginous, unphilosophic evolutionism had full possession of the held for the moment, and claimed, as it were, to be the genuine representative of the young and vigorous biological creed, while he himself was in truth the real heir to all tlie lionours of the situation. He was in ])()ssession ci' the master-key which alone could unlock the bars that opposed the progress of evolution, and still he waited. He could afford to wait. He was diligently collecting, amassing, investigating: eagerlv reading every new systenuitic work, every book of travels, every scientific journal, every record of sport, or exploration, or discovery, to extract from the dead nui'js of undigested fact whatever item of im])licit value might swell the (It'iinite co-ordiuiited series of notes in his own connnon- place books for the now distinctly contemplated 'Origin of Species.' His way was to nudce all sure behind him, to summon u]) all his facts in irresistible array, and iH'Vcr to set out u])ou a public progress until he was secure against all possible attacks of the ever- watch. ful and alert enemv in the rear. i'Vw nu'u would hav^e had strength of mind enough to resist the temptation ort'cred by the ])ublication » ■' the 'Vestiges of Creation, and the extraordinarv success attained bv so flabbv a 74 CHAh'fi'.r Darwin presentiil ion of the evohitioiinry case : Davwin resisted it, and he did wisely. We may, liowever, take it for granted, I doubt not, tliat it was the ajDpearance .'ind success of Chambers's invertebrate book which induced Darwin, iu 1811' (the year of its publication), to enlarge his short notes 'into a sketch of the conclusions which then seemed to him probable.' This sketch he showed to V\\\ (now Sir Joseph) Hooker, no doubt as a precaution to ensure his own claim of priority against any future ])ossible com- petitor. And having thus eased his mind for the moment, he continued to observe, to read, to devour ' Transactions,' to collate instances, with indefatigable persistence for fifteen years longer. If any man mentally measures out fifteen years of his own life, and bethinks Inm of how long a space it seems when thusdeliberateh' pictured, lie will be able to realise a little more definitely — but oidy a little — how profound was the patience, the self-denial, the single-mindedness of Darwin's intense search after the ultimate truths of natural science. What was the sketch that he thus committed to paper in 1811, and submitted to the judgment of his friend Hooker ? It was the germ of tlie theory of natural selection. According to that theory, organic development is due to the survival of the fittest among innumerable variations, good, bad, and indifferent, from one or more parent stocks. Darwin's reading of jMal- thus had suggested to him (apparently as early as the date of publication of the 'Naturalist's Journal") the idea that every species of plant and animal must idways be producing a far greater number of seeds, eggs, germs, or young offspring than could ])ossibly be needed for Tnr J^FRinn of IxmnATiox 75 tlie inainteiiance of lln' nvrra^'r miuibcr oi' tlu' species. Of tliese voniio- l,v liir the <>'reater number must always perish from n-eiieratiou to i>'eneration, for want of space, of food, of air, of raw material. Tlie survivors in each brood uuist l)e those naturally best adapted for survival. The uianv would be eaten, stiirved, overrun, or crowded out ; the few that survive would be those that jjossesscd auv special means of defence aij'ainst ai>'<''ressors, any special advantage for escaping starvation, any special protection against overrunning or overcrowding foes. Animals and plants, Darwin found on impiiry and iii- vestiu'iition, tended to varv under divi'rse circumstances from the parent or parents that originally produced them. These variations were usually intinitesinnd in amount, but sometimes more considerable or ev(Mi strikino-. If anv particular variation tended in anv way to preserve the life of the creatur(\s that exhibited it. beyond the avenige of their like competitors, that variation would in the long run survive, ami the indi- viduals that possessed it, being thus favoured in the struggle for existence, would replace the less adapted form from which they sprang. Darwinism is ^[althnsian- ism on the large scale : it is the application of the calculus of po])ulation t«) the wide facts of universal life. Tn one sense, indeed, it may be said that, given ^lalthus on the one hand and the Lamarckian evolu- tionism on the other, some great nnin somewhere must sooner or later, almost of necessity, have combined the two, and hit out the doctrine of natural selection as we actually know it. Quite so ; but then the point is just this : Darwin /'vrv the great man in question ; he d\i{ the work which in the very essence of things some yG ClIARIF.S DaRW/N suclioTeat" inim was iiiitiiriilly and inevitably predestinetl to do. You can ahvavs easilvmauau'e to o;et on witliout any particular great num, provided, of course, you have ready to hand another equally able great man by whom to replace him in tlie scheme of existence. But how many ordinary naturalists possess the width of mind and universality of interest whicli would prompt tliem to read, mark, learn, and inwardly digest a politico- economical treatise of the calibre of Malthus? How many, having done so, have the keenness of ^'ision to perceive the ensuing biological implications ? How many, having seen them, have the skill and the patience to work up the infinite chaos of botanical and zoological det.'dl into the far-reaching generalisations of the ' Oi'igin of Species * ? ]\[erely to have caught at the grand idea is in itself no small achievement ; others did so and deserve all honour for their insight ; but to flesh it out with all the minute care and conclusive force of Darwin's nuisterpiece is a thousand times a greater and nobler monument of human endeavour. During the fifteen years from 1811< to 1850, how- ever, Darwin's pen was by no means idle. h\ the first- nanied year he published his 'Oeological Observations on Volcanic Islands' — part of the ' Beagle" exploration series; in 1 S-IG he followed this up by his 'Geological Observations on South America ; ' in 1851 he gave to the world his monograph on ' Recent Barnacles ; ' and in 185o, his treatise on the fossil species of the same family. But all these works of restricted interest remrined always subsidiary to the one great central task of his entire lifetime, the preparation of his pro- jected volume on the Origin of S))ecies. T/iR Period of TxcrnATioN y) All throno-li tli(^ iniddlo decades of the centnrv Darwin continued to labour at his vast accumulation f)t" illustrative facts ; and side by side with liis continuous toil, outside o])inion kept paving the way for the final acceptance of his lucid ideas. The public was buying and reading all the time its ten editions of the 'Vestiges of Creation.' It was slowly digesting LyelTs ' Principles of (xeology,' in which the old cataclysmic theories were featly demolished, and the uniformitai'ian conception of a past gradually and insensibly merging into the present was conclusively established. It was getting accustomed to statements like those of the younger St. Hilaire, in 1850, that specific characters may be uiodified by changes in the environing conditions, and that the modifications thus produced may often be of generic value — may make a difference so great that we must regard the product not merely as beL)nging to a distinct species, but even to a distinct genus or higher kind. In 1 852 Herbert Spencer published in tlie 'Leader* his remarkable essay, contrasting the theories of creation and evolution, as applied to organic beings, with all the biting force of his profound intelligence; and in 1855. the same encyclop;edic philosopher put forth the first rough sketch of his 'Principles of Psychology,' in which he took the lead in treating the phenomena of mind from the ])oiut of view of gradual development. In that extraordinary work, the philo- sopher of evolution traced the origin of all mental ])owers and faculties by slow gradations from the very sim])lest subjective elements. The ' Principles of Psychology ' ]ireceded <"he ' Origin of Species ' ])y nearly five years; the first collected volume of Mr. Spencer's 78 Charles Darwin essavs iDrPCpdetl Ojirwiji's work bv some twelve iiiontlis. Jiutleii-l'oweU's essay on tlie ' P]iilos(jpliy of Creation' (nincli debated and condennied in ecclesiastical circles), and IVol'essor Owen's somewhat contradictory utterances on the nature of types and archetypal ideas, also helped to keep alive interest in tlie problem of origins np to the ver}' moment of the final appearance of Darwin's great and splendid solution. It is interesting' during tliese intermediate years to watch from time to time the occasional side-hints of J)arwin's activity and of the interest it aroused among his scientiiic contemporaries. In 1854', for examjile, Sir Charles Lyell notes, after an evening at Darwin's, how Sir Joseph Hooker astonished him with an account of that strange orchid, Catasetum, which bears three totally distinct kinds of flowers on the same plant; ' It will figure,' he says, ' in C. Darwin's book on species, with many other " ugly facts," fis Hooker, clinging like me to the orthodox faith, calls these and other abnormal vagaries.' On a shiiilar occasion, a little later, Lyell asks, after meeting ' Huxley, Hooker, and AVollaston at Darwin's,' 'After all, did we not come from an ourang ?' Last of all, in 1857, Darwin himself writes an aiiti- cijmtory h^tttn^ to his American friend, Asa Gray, in which he mentions ' six points' — the cardinal concep- tions of the ' Origin of Species.' His book is now fairly under weigh; he speaks of it himself to accpiaint- ance and correspondents as an acknowledged project. Events were growing ripe for the birth. A lucky accident precipitated its parturition in the course of the year 1858. 79 CHAPTER Vl. ' THE OKKJIN OF SPKCIES/ The uccideiit came in this wise. Alfred UuHsel Wallace, a young AVelsh biologist, went out at twenty -four, in 1818, to the Amazons lliver, in company with Bates (the author of ' 'I'lie Naturalist on the Amazons'), to collect birds and butterflies, and to study tropical life in the richest region of equatorial America. Like all other higher zoologists of their time, the two young explorers were deeply interested in the profound questions of origin and metamorphosis, and of geographical distribution, and in the letters that passed between them before tliev started thev avowed to o\w another that the object of their quest was a solution of the pressing biological enignui of creation or evolu- tion. Starting with fresh hopes and a few pounds in pocket, on an old, worn-out, and unseaworthy slave- trader, they often discussed these deep problems of life and nature together upon the Sargasso sea, or among the palms and lianas of the Ih-azilian woodlands. The air was thick with whiffs and foretastes of evolutionism, and the two budding naturalists of the Amazons expe- dition had inhaled them eagerh" witli every breath. They saw among the mimicking organisms of that 8o Charles Darwin eqnatnriiil zone striin^f*- pnzzlps to «'ii"iusp(l in the veins unci spots that diversified the filmv membranes of insects' winjjs tlie liieroo'lyphs of nature, writing as on a tablet for them to deci])liei- the story of the slow modification of species. In 1 852 — the year when Herbert Spencer in England pnblislied liis essay on the ' Develo]mient Hypothesis,' and when Nandin in France pnt forth his bold and able pajier on the ' Origin of Species' — A\'^allace once more returned to h]urope, and gave to the world liis interest- iu"- ' Travels on the Amazons and the llio Nem-o.' Two vears later the indefatigable traveller set out a second time on a voyage of tropical exploration, among the islands of the Malav archiiielago, and for eijjlit vears he wandered about in Malav huts and remote islets, gathering in solitude and isolation the enormous store of minute facts which he afterwards lavished with so prodigal a hand upon ' Tropical Nature,' and the ' (jeo- graphical Distribution of Animals.' While AVallace was still at Ambovna, he sent home in 1858 a striking memoir, addressed to Darwin, with a request that he would forward it to Sir Charles Lyell, for presentation to the liinnean Society. Darwin opened and read his brother naturalist's paper, and found to his surprise that it contained his own theory of natural selection, not worked out in detail, as he himself was working it out, but still complete in s])irit and essence, with no im])ortant ])ortion of the central idea lacking to its full rotundity of conception. A jealous man would have thrown obstacles in the way of publication ; but both Darwin and Wallace were born superior to the meannesses of jealousy. The elder naturalist commended ' Tun Origin of Spec/fs ' 8 1 liis yoiin»( rival's papor ft once to Sir Charles Lyell, wlio sent it on immediately to the Linnean Society. But Sir Charles Lyell and Sir Joseph Hooker, both of whom knew of Darwin's work, thought it advisable that he should publish, in tlie ' Journal ' of the Society, a few extracts from his own manuscripts, side by side with Wallace's paper. Darwin, therefore, selected some essential passages for the purpose from his own long- irathered and voluminous notes, and the two contributions were read together before tlie Society on Julv the 1st, 1858. That double communication marks the date of birth of modern evolutionism. It is to the eternal credit of both thinkers that each accepted his own true position with regard to the great discovery in perfect sincerity. The elder naturalist never strove for a moment to press his own claim to priority against the younger : the younger, with singular generosity and courtesy, waived his own claim to divide the honours of discovery in favour of the elder. Not one word save words of fraternal admiration and cordial appreciation ever passed the lips of tutlier with regard to the other. The distinctive notion of natural selection, indeed, like all true and fruitful ideas, had more than once flashed for a moment across the penetrating mind of more than one independent investigator. As early as 1813, Dr. Wells, the famous author of the theory of dew, applied that particular conception to the single case of the production of special races among mankind. ' Of the accidental varieties of man, which would occur among the first few and scattered inhjibitants of the middle regions of Africa,' he wrote, ' some one would be better fitted than the others to bear the diseases of G 82 Charles Dakwin tlie couutry. 'I'his nice would consequently luiiltiply, wlii^ the others would decrease ; not only from their inability to sustain the attacks of disease, but from their incapacity of contending with their more vigorous neighbours. . . . The same disposition to form varieties still existing, a darker and a darker race would in the course of time occur; and as tin; darkest would l)e the best fitted foi" the climate, this would at last become the most prevalent, if not the only racc^ in the country.' Here we have not merely the radical concept of natural selection, but jdso the subordinate idea of its exertion upon what Darwin calls ' spontaneous variations.' What is wanting in the paper is the application of the faintly descried law to the facts and circumstances of general biology : Wells saw only a particular instance, where Darwin and Wallace more vividly perceived a uni- versal princi])le. Again, in 1 8-"31 , ]\[r. Patrick Matthew in that singular appendix to his book on naval timber actually enunciates the same idea, applied this time to the whole of nature, in words sometimes almost iden- tical with Darwin's own. ' As nature in all her modifi- cations of life,' says this unconscious discoverer, ' has a power of increase far beyond what is needed to supply the place of what falls by Time's decay, those indivi- duals who possess not the requisite strength, swiftness, hardihood, or cunning, fall prematurely without repro- ducing — either a prey to their natural devourers, or sinking under disease, generally induced by want of nourishment, their place being occupied by the more perfect of their own kind, who are pressing on the means of existence. . . . The self-regulating adapti\'e disposition of organised life may, in part, be traced to ' Till Oa'Ihia of Sri:cU'S "^i the extreme fecundity of imtnre, wlio, as before statetl. has in all the varieties of her otlspriiiu^ a ])roli(ic ])ower nuicli beyond (in many cases a tlionsandfold) wliat is necessary to fill up tho vacancies cansed by senile decay. As the field of existence is limited and preoccupied, it is only the hardier, more robust, better-suited-to-cir- cumstance individuals, who are able to struggle forward to nnitnrity, these inhabitini,^ V)\\\\ the situations to which they liave snperior ada])tati()n and <(reater power of occupancy than any other kind ; the weaker and less circumstance-suited being prematurely destroyed. This principle is in constant action ; it reo'ulates the colour, the figure, the capacities, and instincts ; those individuals in each species whose colour and covering are best suited to concealment or protection from enemies, or defence from inclemencies and vicissitudes of climate, whose figure is best accommodated toliealth, strength, defence, and snp])ort ; whose capacities and instincts can best regulate the physical energies to self- advantage according to circumstances — in such im- mense waste of primary and youthful life those only come forward to maturity from the strict ordeal by which nature tests their adaptation to her standard of perfection and fitness to continue their kind by repro- duction.' Of the ideas expressed in these paragraphs, and others which preceded them, Djirwin himself rightly observes, ' He gives precisely the same view on the origin of species as that propounded by Mr. Wallace and mvself. He clearlv saw the full force of the prin- ciple of natural selection.' In 1852, once more, so eminent and confirmed an evolutionist as ]\Ir. Herbert Spencer himself had hit o 2 84 Chani.rs Darwin upon a glimpse of the same gre.iu truth, strange to say without perceiving the width and scope of its implica- tions. ' All mankind,' he wrote in that vear in an essav on population in the ' Westminster Ilevievv,' ' in turn subject themselves more or less to the discipline de- scribed ; they either may or may not advance under it ; but, in the nature of things, only those who do advance under it eventually survive. For, necessarily, families and races whom this increasing difficulty of getting a living which excess of fertility entails does not stimulate to improvements in production .... are on the high road to extinction ; and must ultimately be supplanted by those whom the pressure does so stimu- late. . . . And here, indeed, without further illustra- tion, it will be seen that premature death, under all its forms, and from all its causes, cannot fail to work in the same direction. For as those prematurely carried off must, in the average of cases, be those in whom the power of self-preservation is the least, it unavoidably follows that those left behind to continue the race must be those in whom the power of self-preservation is the greatest, must be the select of their generation.' In this striking pre-Darwinian passage we have a partial perception of what Mr. Spencer afterwards described as the survival of the fittest ; but, as our great philosopher liimself remarks, it ' shows how near one may be to a great generalisation without seeing it.' For not only does Mr. Spencer, like Wells before him, limit the application of the principle to the case of humanity ; but, unlike Wells, he overlooks the all-important factor of spontaneous variation, and the power of natural selection, acting upon such, to produce specific and ^The Origin of Species' 85 generic divergences of structure. In short, in his own words, the paragrapli ' contains merely a passing recog- nition of the selective process, and indicates no suspicion of the enormous range of its effects, or of the conditions under which a large part of its effects are produced.' On the other hand, it must be noted that both Spencer and Matthew, like Darwin himself, based their ideas largely upon the Malthusian principle, and thus held the two true keys of the situation fairly within their unconscious hands. Frankly to recognise these various foreshadowings of the distinctive Darwinian theory of natural selection is not in any way to undermine the foundations of Charles Darwin's own real and exceptional greatness. On the contrary, the mere fact that his views were so far anticipated by Wells, Matthew, Spencer, and others, and were simultaneously arrived at across half the globe by the independent intellect of Alfred Kussel Wallace, is in itself the very best proof and finest criterion of Charles D.irwin's genuine apostleship. No truly grand and fruitful idea was ever yet the sole property of a single originator. Great discoveries, says an acute critic, must alwavs be concerned with some problem of the time which many of the world's foremost minds are just then cudgelling their active brains about. It was so with the discoverv of the differential calculus, and of tlie planet Neptune ; with the interpretation of the Egyptian hieroglyphics, and of the cuneiform in- scriptions ; with the undulatory theory of light, with the mechanical equivalent of heat, with the doctrine of the correlation and conservation of energies, with the invention of the steam engine, the locomotive, the \ 86 ' Charles D ah win telep^rapli and the telephone ; with the nebnlar hypo- thesis, and with spectrum analysis. It was so, too, with the evolutionary movement. The fertile upturning of virgin sod in the biological field which produced Darwin's forerunners, as regards the idea of descent with modification, in the ])ersons of Buffon, Lamarck, and Erasmus Darwin, necessarily produced a little later, under the fresh impetus of the Malthusian conception, his forerunners or coadjutors, as regards the idea of natural selection, in the persons of Wells, Matthew, and Wallace. It was Darwin's task to recognise the uni- versal, where Wells and Spencer had seen only the particular ; to build up a vast and irresistible inductive system, where JMatthew and Wallace had but thrown out a pregnant hint of wonderful a jrriori interest and suggestiveness. It is one thing to draw out the idea of a campaign, another thing to carry it to a successful conclusion ; one thing rudely to sketch a ground-plan, another thing finally to pile aloft to the sky the front of an august and imposing fabric. As soon as the papers at the Linnean had been read and printed, Darwin set to work in real earnest to bring out the first instfilment of his great work. That instal- ment was the ' Origin of Species.' The first edition was ready for the public on November the 24tli, 1859. In his own mind Darwin regarded that immortal work merely in the light of an abstract of his projected volumes. So immense were his collections and so voluminous his notes that the ' Origin of Species ' itself seemed to him like a mere small portion of the contem- plated publication. And indeed he did ultimately work out several other portions of his original plan in his ' Tup. Origin of Species' %7 detailed treatises on the Variation of Animals and ]Mants under Domestication, on tlie P^ffects of Cross and Self- Fertilisation, and on the Descent of Man and Sexual Selection. But the immense and unexpected vogue of his first volume, the almost inunediate revolution which it caused in biological and general opinion, and the all but universal adhesion to his views of all tlie greatest and most rising naturalists, to a great extent saved him the trouble of carrying out in full the task he had originally contemplated as necessary. Younger and less occupied labourers took part of the work off their leader's hands ; the great chief was left to prosecute his special researches in some special lines, and was relieved from the necessity of further proving in minuter detail what he had already proved with sufficient cogency to convince all but the wilfully blind or the hopelessly stupid. The extraordinary and unprecedented success of the * Origin of Species ' is the truest test of the advance it made upon all previous evolutionary theorising. Those who had never been convinced before were now con- vinced by sheer force of reasoning ; those who believed and those who wavered had their faith confirmed into something like the reposeful calm of absolute certitude. Let us consider, therefore, what exactly were the additions which Charles Darwin offered in his epoch- making work to the pre-existing conceptions of evolu- tionists. In 1852, seven years before the publication of Darwin's masterpiece, Mr. Herbert Spencer wrote as follows in an essay in the ' Leader ' on creation and evolution. The expressions of so profound and philo- 88 Chaa'i.p.s Darwin sophical a hi )logist may be regarded as the higli-water mark of evolutionary thinking up to the date of the appearance of Walhice and Darwin's theory : — ' Even could the supporters of the development hypothesis merely show that the production of species by the process of modification is conceivable, they would be in a better position than their opponents. But they can do much more than this ; they can show that the process of modification has effected and is effecting great changes in all organisms, subject to modifying influences thc^y can show that any existing species — animal or vegetable — when placed under conditions different from its previous ones, imme- diately begins to undergo Certain changes of structure fitting it for the new conditions. They can show that in successive generations these changes continue until ultimately the new conditions become the natural ones. They can show that in cultivated plants and domesti- cated animals, and in the several races of men, these changes have uniforaily taken place. They can show that the degrees of difference, so produced, are often, as in dogs, greater than those on which distinctions of species are in other cases founded. They can show that it is a nuitter of dispute whether some of these modified forms f eacli oi' these produced a younu; fish which arrived at maturity, the whole sea would immediutely become a solid mass of closely packed codtish. Liuiuuus reckoned that it" an anuual plant had two seeds, each of which produced two seedlintjfs in the succeeding season, and so on continually, in twenty years their progeny would amount to a million plants. A struggle for existence necessarily results from this universal tendency of animals and plants to increase faster than the means of subsistence, whether those means be food, as in the first case, or carbonic acid, water, and sunshine as in the second. Animals are all perpetually battling with one another for the food-supply of the moment ; plants are perpetually bat- tling with one another for their share of the soil, the rainfall, and the sunshine. The case of the plant is a very important one to understand in this connection, because it is probable that most people greatly misunderstand the biological meaning of the phrase ' struggle for existence.' They imagine that the struggle is chiefly conducted between ditierent species, whereas in reality it is chiefly conducted between members of the same species. It is not so nmch the battle between the tiger and the antelope, between the wolf and the bison, between the snake and the bird, that ultimately results in natural selection or surviyal of the fittest, as the struggle between tiger and tiger, between bison and bison, between snake and snake, between antelope and antelope. A human 96 Charles Darwin analogy may help to make this difiicalt principle a little clearer. The baker does not fear the competition of the butcher in the struggle for life : it is the competi- tion of the other bakers that sometimes inexorably crushes him out of existence. The lawyer does not press hard upon the doctor, nor the architect upon the journeyman painter. A war in the Soudan or in South Africa is far less fatal to the workman in our great towns than the ceaseless competition of his fellow-workmen. It is not the soldier that kills the artisan, but the num- ber of other artisans who undersell him and crowd to fill up every vacant position. In this way the great enemies of the individual herbivore are not the carnivores, but the other herbivores. The lion eats the antelope, to be sure ; but the real struggle lies between lion and lion for a fair share of meat, or between antelope and antelope for a fair share of pasturage. Ilomu homini Iniim^ says the old proverb, and so, we may add, in a wider sense, luiniH liqw lupim, also. Of course, the cariuvore plays a great part in the selective process ; but he is the selector only ; the real competition is be- tween the selected. Now, let us take the case of the plant. A thousand seedlings occupy the space where few alone can ultimately grow ; and between these seedlings the struggle is fierce, the strongest and best adapted ultimately surviving. To take Darwin's own example, the mistletoe, which is a parasite, cannot truly be said to struggle with the apple tree on which it fastens ; for if too many parasites cover a tree, it perishes, and so they kill themselves as well as their host, all alike dying together. But several seedling mistletoes growing together on the same branch may ' Tju-: Origix of Species' 97 fairly be said to struggle with one another for light and air ; and since mistletoe seeds are disseminated by birds and dropped by them in the angles of brandies, the mistletoe may also be said to compete with other berry- bearing bashes, like cornel and hawthorn, for the minis- trations of the fruit-eatin": birds. The stru^fjifle is fierce between allied kirids, and fiercest of all between individual members of the same species. Owing to this constant struggle, variations, however slight, and from whatever cause arising, if in any degree profitable to the individual which presents them, will tend to the preservation of the particular organism, and, being on the average inherited by its offspring, will similarly tend to increase and multiply in the world at large. This is the principle of natural selection or sur- vival of the fittest — the great principle which Darwin and Wallace added to the evolutionism of Lamarck and his successors. Let us take a single concrete example. In the desert, with its monotonous sandy colouring, a black insect or a white insect, still more a red insect or a blue insect, would be immediately detected and promptly de- voured by its natural enemies, the birds and lizards. But any greyish or yellowish insects would be less likely to attract attention at first sight, and would be over- looked as long as there were any more conspicuous in- dividuals of their own kind about for the birds and hzards to feed on at their leisure. Hence, in a very short time, the desert would be depopulated of all but the greyest and yellowest insects ; and among these the birds would pick out those which differed most markedly iu hue or shade from the sand around them. Jhit those II 98 Charles Darwin which happened to vary most in the direction of a sandy or spotty colour would be most likely to survive, and to become the parents of future generations. Thus, in the course of long ages, all the insects which inhabit deserts have become sand-coloured ; because the least sandv were perpetually picked out for destruction by their ever-watchful foes, while the most sandy escaped and multiplied and replenished the earth with their own likes. Conversely, the birds and the lizards ag.ain would probably begin by being black, and white, and blue, and green, like most other birds and lizards in the world generally. But the insect would have ample warning of the near approach of such conspicuous self-advertising enemies, and would avoid them accordingly whenever they appeared within range of his limited vision, either by lying close, or by shamming death, or by retreating precipitately to holes and crannies. Therefore, whatever individual birds or lizards happened to vary most in the direction of grey or sand-colour, and so to creep unob- served upon the unguarded insects, would succeed best on the average in catching beetles or desert grasshoppers. Hence, by the slow dying out of the more highly coloured and distinctive insect-eaters, before the severe competition of the greyest and sandiest, all the birds and lizards of the desert have become at last as absolutely sand-coloured as the insects themselves. Only the gi'eyest insect could escape the bird ; only the greyest bird, en revanche, could surprise and devour the unwary insect. Sir Charles Lyell and the elder De Candolle had already seen the great importance of the struggle for existence in the organic world, but neither of them had observed the magnificent corollary of natural selection, ' The Or mix or Spf.c/f.s ' 99 which flows from it ahnost as a mathematical necessity when once suggested ; for, given indefinite variability, and a geometrical rate of increase, it must needs follow that some varieties will be better suited to the circumstances than others, and therefore that they will survive on the average in increased proportions. A passage from one of LyelFs early letters will show how near he too went to this i^reat luminous "'eneralisation, and yet how utterly he missed the true implications of liis own vague and chaotic idea. He writes thus to Sir John Herschel in 1836, while Darwin was still but homeward bound on the voyage of the ' Beagle ' : — ' In regard to the origination of new species, I am very glad to find that you think it probable that it may be carried on through the intervention of intermediate causes. . . . An insect may be made in one of its transformations to resemble a dead stick, or a leaf, or a lichen, or a stone, so as to be somewhat less easily found by its enemies ; or if this would make it too strong, an occasional variety of the species may have this advantage conferred on it ; or if this would be still too much, one sex of a certain variety. Probably there is scarcely a dash of colour on the wing or body of which the choice would be quite arbitrary, or which might not affect its duration for thousands of years.' Now, this comes in some ways perilously near to Darwin indeed ; but in the most important point of all it is wide apart from him as the pole is from the equator. For Lyell thought of all this as a matter of external teleological arrangement ; he imagined a de- liberate power from outside settling it all by design beforehand, and granting to varieties or species these H 2 lOO Charles Darwin special peculiarities in a manner that was at bottom essentially supernatural, or in other words miraculous ; whereas Darwin thinks of it as the necessary result of the circumstances themselves, an inevitable outcome of indefinite variability flm the geometrical rate of in- crease. Where Lyell sees a final cause, Darwin sees an eflficient cause ; and this distinction is fundamental. It marks Darwin's position as that of a great philosophi- cal thinker, who can dash aside at once all metaphysical cobwebs, and penetrate to the inmost recesses of things, unswerved by the vain but specious allurements of obvious and misleading teleological fallacies. Darwin also laid great stress on the immense com- plexity of the relations which animals and plants bear to one another, in the struggle for existence. For example, on the heathy uplands near Farnham in Surrey, large spaces were at one time enclosed, on which, within ten years, self-grown fir-trees from the wind-borne seeds of distant clumps sprang up so thickly as actually to choke one another with their tiny branches. All over the heaths outside, when Darwin looked for them, he could not find a single fir, except the old clumps on the hilltops, from which the seedlings themselves had originally sprung. But, on looking closer among the stems of the heath, he descried a number of very tiny firs, which had been perpetually browsed down by the cattle on the commons ; and one of them, with twenty-six rings of growth, had during many years endeavoured unsuccessfully to raise its head above the surrounding heather. Hence, as soon as the land was enclosed, and the cattle excluded, it became covered at once with a thick growth of vigorous 'The Origin of Specius' ioi younpf fir-trees. Yet who would ever liave supposed beforehand that the mere presence or absence of cattle would absolutt^lv have determined the very existence of the Scotch fir throughout a wide range of well-adapted sandy English upland ? To take another curious instance mentioned by Darwin. In Paraguay, unlike the greater part of neighbouring South America, neither horses nor cattle liave ever run wild. This is due to the presence of a parasitic fly, which lays its eggs in their bodies when first born, the maggots killing off the tender young in their first stages. But if any cause were to alter the number of the dangerous flies, then cattle and wild horses would abound; and this would alter the vegetation, as Darwin himself observed in other parts of America ; and the change in the vegetation would affect the insects ; and that again the insectivorous birds ; and so on in ever widening circles of incalculable complexity. Once more, to quote the most famous instance of all, the visits of humble-bees are absolutelv necessary in order to place the pollen in the right position for setting the seeds of purple clover. Heads from which Darwin excluded the bees produced no seeds at all. Hence, if humble-bees became extinct in England, the red clover, too, would die ofi": and indeed, in New Zealand, where there are no humble-bees, and where the efforts to introduce them for this very purpose have been uni- formly unsuccessful, the clover never sets its seed at all, and fresh stocks have to be imported at great ex- pense every year from Europe. But the number of humble-bees in any district largely depends upon the number of field-mice, which destroy the combs and 102 Char/.p.s Darwin nosfs ill iininonsp qnantities. The number of mice, again, is greatly affected by the pvopoi*tion of cats in the neiglibourhood ; so that Colonel Newman, who paid mnch attention to this subject, found humble-bees most numerous in the neighbourhood of villages and small towns, an effect which he attributed to the .ibundance of cats, and the consequent scarcity of the destructive field-mice. Yet here once more, who could suppose beforehand that the degree to which the purple clover set its seeds was in part determined by the number of cats kept in houses in the surrounding district ? One of Darwin's own favourite examples of the action of natural selection, which he afterwards ex- panded largely in his work on Orchids and in several other volumes, is that which relates to the origin of conspicuous flowers. Many plants have a sweet excre- tion, which is eliminated sometimes even by the leaves, as in the case of the common laurel. This juice, though small in quantity, is eagerly sought and eaten by insects. Now let us suppose that, in some variety of an incon- spicuous flower, similar nectar was produced in the neighbourhood of the petals and stamens. Insects, in seeking the nectar, would dust their bodies over with the pollen, and would carry it awaj' with them to the next flow^er visited. This would result in an act of crossing ; and that act, as Darwin afterwards abundantly proved in a separate and very laborious treatise, gives rise to exceptionally vigorous seedlings, which would therefore have the best chance of flourishing and sur- viving in the struggle for existence. The flowers which produced most hone}' would oftenest be visited, and oftenest crossed ; so that they would finally form a new * The Origin of Species^ 103 species. The more brightly coloured among them, again, would be more readily discriminated than the less brightly coloured ; and this would give them such an advantage that in the long run, as we actually see, almost all habituallv insect-fertilised flowers would come to liave brilliant petals. The germ of this luminous ideji, once more, is to be found in Sprengel's remarkable work on the fertilisation of flowers — a work far in advance of its time in many ways, and to which Darwin always expressed his deep obligations ; but, as in so many other instances, while Sprengel looked upon all the little modifications and adaptations of flower and insect to one another as the result of distinct creative design, Darwin looked upon them as the result of natural selection, working upon the basis of indeter- luinate spontaneous variations. How do these variations arise ? Not by chance, of course (for in the strict scientific sense nothing on earth can be considered as really fortuitous), but as the out- come for the most part of very minute organic causes, whose particular action it is impossible for us to predict with our present knowledge. Some physical cause in each case there must necessarily be ; and indeed it is often possible to show that certain changes of condition in the parent do result in variations in the off*spring, though what special direction the variation will take can never be foretold with any accuracy. In short, our ignorance of the laws of variation is profound, but our knowledge of the tact is clear and certain. The fact alone is essential to the principle of natural selection ; the cause, though in itself an interesting subject of inquiry, may be safely laid aside for the present as com- 104 Chart.es Darwin purativoly uniniportiiiit. What we liuve achiially <^-iven to us in the concrete universe is, organisms varying perpetually in minute points, and a rapid rate of in- crease causing every minute point of advantage to be exceptionally favoured in tlie struggle for existence. J^ut Darwin is remarkable amonff all broachers of new theories for the extraordinary candour and open- ness of liis method, tie acknowledged beforehand all the difficulties in the wav of his theory, and thoujifh he himself confessed tliat some of them were serious (a statement which subsequent research has often rendered unnecessaiy), he met many of them with cogent argu- ments by anticipation, and demolished objections before they could even be raised against him by hostile critics. Of these objections, only two need here be mentioned. The first is the question, why is not all nature even now a confused mass of transitional forms ? Why do generji and species exist as we see them at present in broad distinction one from the other? To this Darwin answers rightly that, where the process of species- making is still going on, we do actually find fine grada- tions and transitional forms existing between genera, varieties, and species.' But, furthermore, as natural selection acts solely bv the preservation of useful modi- fications, each better-adapted new form will always tend in a fully stocked country to oust and exterminate its own unimproved parent type, as well as all other competing but less perfect varieties. Thus natural selection and extinction of intermediates ^(:> for ever ' The researches of Seebohm and others hjive since proved that this Is really the case to a far greater extent than Darwin was awai'e of in 185y, or, indeed, till many years afterward. * Tub Origin of Species' 105 hand in hand. Tlio more pcrfec't tht' new varicfy, tlic more absolutely will it kill ott' the intermediate forms. The second great difficulty lies in the question of the origin of instinct, which, as Darwin shows, by careful inductive instances, may have arisen by the slow and gradual accumulation of numerous slight 3-et profitable variations. I have dwelt at some length upon those portions of the ' Origin of Species ' which deal in detail with the theor}' of natural selection, the chief contribution which Darwin made to the evolutionary movement, bt^cause it is impossible otherwise fully to understand the great gulf which separates his evolutionism from the earlier evolutionism of Lamarck and his followers. But it is impracticable here to give any idea of the immense wealth of example and illustration which Darwin brought to the elucidation of every part of his complex problem. In order to gain a full conception of this side of his nature, we must turn to the original treatise itself, and still more to the subsequent volumes in which the ground-work of observations and experiments on which he based his theory was more fully detailed for the specialist public. The rem.'iindi'r of Darwin's epoch-making work deals, strictly sjieaking, rather with the general theory of 'descent with modification' than with the special doc- trine of natural selection. It restates and reinforces, by the light of the new additional concept, and with fuller facts and later knowledge, the four great argu- ments alreadv known in favour of oryanic evolution as u whole, the argument from Geological Succession, the argument from Geographical Distribution, the argument io6 CitARi.F.s Darwin from l']inbry()l()giciil Duvelopnient, aiul the argument from Classificatory Affinities. Each of these we may briefly summarise. The geological record is confessedly imperfect. At the time when Darwin first published the ' Origin of Species,' it had disclosed to our view comparatively few intermediate or transitional forms between the chief great chisses of plants or animals ; since that time, in singular confirmation of the Darwinian hypothesis, it has disclosed an immense number of such connecting types, amongst which may be more particularly noticed the ' missing links ' between the birds and reptiles, the ancestors of the horses, the camels, and the pigs, jmd tlie common progenitor of the ruminants and the pachyderms, two great groups classed by Cuvier as distinct orders — all of which instances were incorporated by Darwin in later editions of his ' Origin of Species.' But, apart from these special and newly discovered cases, the whole general course of geological history ' agrees admirably with the theory of descent with modification through variation and natural selection.' The simpler aninuds of early times are followed by the more complex and more specialised animals of later geological periods. As each nuiin group of animals appears upon the stage of life, it appears in a very central and ' generalised ' form ; as time goes on, we find its various members differing more and more widely from one another, and assuming more and more specialised adaptive forms. And in each country it is found, as a rule, that the extinct animals of the later formations bear a close general resemblance and relationship to the animals which now inhabit the same regions. For example. ' The Origin of Species* 107 tlie fossil mammals from the Australian caves aiv nearly allied to the modern kantrarooa. ]ihalanfrers, and wom- bats; and the «^''i<>antic extinct sloths and armadillos of South America are reproduced in their smaller repre- sentatives at the present day. So, too, the moa of New Zealand was a huge apteryx ; and the birds dis- entombed from the bone-caves of lira/il show close affinities to the toucans and jaca^^ars that still scream and flit in countless flocks amonfy, tlu^ study of early (Ifvclojimont in the individual animal or plant, also throws much side light upon the nature and ancestry of each species or family. For example, gorse, which is a member of the Tv-n flower tribe, lias in its adult sta<2fe solid, spiny, thorn-nKo leaves, none of which in the least resemble the folia