Thomas Henry Huxley; A Sketch Of His Life And Work Part 5

FOOTNOTES:

[Footnote D: See E. Clodd's _Pioneers of Evolution_, London, 1897, and Osborn's _From the Greeks to Darwin_, New York, 1896.]

CHAPTER VII

THE BATTLE FOR EVOLUTION

Huxley's Prevision of the Battle--The Causes of the Battle--The _Times_ Review--Sir Richard Owen attacks Darwinism in the _Edinburgh Review_--Bishop Wilberforce attacks in the _Quarterly Review_--Huxley's Scathing Replies--The British a.s.sociation Debates at Oxford--Huxley and Wilberforce--Resume of Huxley's Exact Position with Regard to Evolution and to Natural Selection.

When Huxley wrote thanking Darwin for the first copy of the _Origin_, he warned him of the annoyance and abuse he might expect from those whose opinions were too suddenly disturbed by the new exposition of evolution, and a.s.sured him of the strongest personal support:

"I trust you will not allow yourself to be in any way disgusted or annoyed by the considerable abuse and misrepresentation which, unless I greatly mistake, is in store for you. Depend upon it, you have earned the lasting grat.i.tude of all thoughtful men; and as to the curs which will bark and yelp, you must recollect that some of your friends, at any rate, are endowed with an amount of combativeness which (though you have often and justly rebuked it) may stand you in good stead.

"I am sharpening my claws and beak in readiness."

Huxley was absolutely right in his prediction as to the magnitude of the prejudices to be overcome before evolution became accepted, and for the next thirty years of his life he was the leader in the battle for Darwinism. It was natural that the new views, especially in their extension to man himself, should arouse the keenest opposition. To those of the present generation, who have grown up in an atmosphere impregnated by the doctrine of descent, the position of the world in 1860 seems "older than a tale written in any book." As we have tried to shew in the preceding chapter, biological science was partially prepared; the mutability of species and the orderly succession of organic life were in the air. But the application of the doctrine to man came as a greater shock to civilised sentiment than would have occurred a century earlier. It came as a disaster even to the clearest and calmest intellects, for it seemed to drag down to the dirt the n.o.bility of man. Out of the fierce flame of the French Revolution, there had come purged and clean the conception of man as an individual and soul. As this century advanced, the conception of the dignity and worth of each individual man, rich or poor, bond or free, had spread more and more widely, bearing as its fruit the emanc.i.p.ation of slaves, the spread of political freedom, the amelioration of the conditions of the dregs of humanity, the right of all to education, the possibility of universal peace based on the brotherhood of man; and all that was best in philosophy and in political practice seemed bound up with a lofty view of the unit of mankind. Carlyle himself, to whom many of the freest and n.o.blest spirits in Europe were beginning to look as to an inspired prophet, could see in it nothing but a "monkey d.a.m.nification of mankind." The dogmatic world saw in it nothing but a deliberate and malicious a.s.sault upon religion. The Church of England in particular was beginning to recover from a long period of almost incredible supineness, and there was arising a large body of clergy full of faith and zeal and good works, but quite unacquainted with science, who frankly regarded Darwin as Antichrist, and Huxley and Tyndall as emissaries of the devil. Against evolutionists there was left unused no weapon that ignorant prejudice could find, whether that prejudice was inspired by a lofty zeal for what it conceived to be the highest interests of humanity, or by a crafty policy which saw in the new doctrine a blow to the coming renewed supremacy of the Church. To us, now, it may seem that Huxley had "sharpened his beak and claws"

with the spirit of a gladiator rather than with that of the mere defender of a scientific doctrine; but a very short study of contemporary literature will convince anyone that for a time the defenders of evolution had to defend not only what they knew to be scientific truth, but their personal and private reputation. The new doctrine, like perhaps all the great doctrines that have come into the world, brought not peace but a sword, and had to be defended by the sword. Darwin had not the kind of disposition nor the particular faculties necessary for a deadly contest of this kind; he was interested indeed above all things in convincing a few leading naturalists of the truth of his opinions; but, that done, he would have been contented to continue his own work quietly, in absolute carelessness as to what the world in general thought of him. Huxley, on the other hand, was incapable of restraining himself from propagating what he knew to be the truth; his reforming missionary spirit was not content simply with self-defence; it drove him to be a bishop _in partibus infidelium_.

By a curious and interesting accident, Huxley had the opportunity of beginning his propagandism by writing the first great review of _The Origin of Species_ in the _Times_, at that period without question the leading journal in the world. Huxley's own account of this happy chance is given in _Darwin's Life and Letters_, vol. ii.

"The _Origin_ was sent to Mr. Lucas, one of the staff of the _Times_ writers at that day, in what I suppose was the ordinary course of business. Mr. Lucas, though an excellent journalist, and at a later period editor of _Once a Week_, was as innocent of any knowledge of science as a babe, and bewailed himself to an acquaintance on having to deal with such a book, whereupon he was recommended to ask me to get him out of his difficulty, and he applied to me accordingly, explaining, however, that it would be necessary for him formally to adopt anything I might be disposed to write, by prefacing it with two or three paragraphs of his own.

"I was too anxious to seize on the opportunity thus offered of giving the book a fair chance with the mult.i.tudinous readers of the _Times_ to make any difficulty about conditions; and being then very full of the subject, I wrote the article faster, I think, than I ever wrote anything in my life, and sent it to Mr.

Lucas, who duly prefixed his opening sentences. When the article appeared, there was much speculation as to its authorship. The secret leaked out in time, as all secrets will, but not by my aid; and then I used to derive a good deal of innocent amus.e.m.e.nt from the vehement a.s.sertions of some of my more acute friends, that they knew it was mine from the first paragraph." "As the _Times_ some years since referred to my connection with the review, I suppose there will be no breach of confidence in the publication of this little history."

This review was one of the few favourable notices, and naturally it delighted Darwin greatly. He wrote to Hooker about it: "Have you seen the splendid essay and notice of my book in the _Times_? I cannot avoid a strong suspicion that it is by Huxley; but I have never heard that he wrote in the _Times_. It will do grand service." On the same day, writing to Huxley himself, he said of the review:

"It included an eulogium of me which quite touched me, although I am not vain enough to think it all deserved. The author is a literary man and a German scholar. He has read my book attentively; but, what is very remarkable, it seems that he is a profound naturalist. He knows my barnacle book and appreciates it too highly. Lastly, he writes and thinks with quite uncommon force and clearness; and, what is even still rarer, his writing is seasoned with most pleasant wit. We all laughed heartily over some of the sentences.... Who can it be? Certainly I should have said that there was only one man in England who could have written this essay, and that you were the man; but I suppose that I am wrong, and that there is some hidden genius of great calibre; for how could you influence Jupiter Olympus and make him give you three and a half columns to pure science? The old fogies will think the world will come to an end. Well, whoever the man is, he has done great service to the cause."

The essay in the _Times_ was followed shortly afterwards by a "Friday Evening Discourse" in 1860 on "Species, Races, and their Origin," in which Huxley, addressing a cultivated audience, laid the whole weight of his brilliant scientific reputation on the side of evolution. Next, in April, 1860, he published a long article in the _Westminster Review_, then a leading organ of advanced opinion, on _The Origin of Species_, some quotations from which article were made in the last chapter. Apart from its strong support of the doctrine of evolution, its whole-hearted praise of Darwin's achievements, and the clear way in which, while it showed the value of natural selection as the only satisfactory hypothesis in the field, it gave reasons for regarding it strictly as an hypothesis, the review is specially interesting as a contrast to reviews which appeared about the same time in the _Edinburgh Review_ and in the _Quarterly_. Both these were not only exceedingly unfavourable, but were written in a spirit of personal abuse singularly unworthy of their authors and still more of their subject. The review in the _Edinburgh_ had come as a particularly great shock to Darwin, Huxley, and their friends. Sir Richard Owen, in many ways, was at that time the most distinguished anatomist in England. He had been an ardent follower of Cuvier, and in England had carried on the palaeontological work of the great Frenchman. He was a personal friend of the court, a well-known man in the best society, and in many ways a worthy upholder of the best traditions of science.

In the particular matter of species, he was known to be by no means a firm supporter of the orthodox views. When Darwin's paper was read at the Linnaean Society, and afterwards when the _Origin_ was published, the verdict of Owen was looked to with the greatest interest by the general public. For a time he wavered, and even expressed himself of the opinion that he had already in his published works included a considerable portion of Darwin's views. But two things seemed to have influenced him: First, Wilberforce, the Bishop of Oxford, and Sedgwick and Whewell, the two best-known men at Cambridge, urged him to stamp once for all, as he only could do, upon this "new and pernicious doctrine." Secondly, combined with his great abilities, he had the keenest personal interest in his own position as the leader of English science, and had no particular friendship for men or for views that seemed likely to threaten his own supreme position. In a very short time he changed from being neutral, with a tendency in favour of the new views, to being a bitter opponent of them. In scientific societies and in London generally, naturally enough he constantly came across the younger scientific men, such as Huxley and Hooker, who had declared for Darwin, and he made the irretrievable mistake of for a time attempting to disguise his opposition while he was writing the most bitter of all the articles against Darwinism. That appeared in the _Edinburgh Review_ in April, 1860, and the range of knowledge it displayed, and the form of arguments employed, naturally enough betrayed the secret of its authorship, although Owen for very long attempted to conceal his connection with it. Darwin, who had the most unusual generosity towards his opponents, found this review too much for him. Writing to Lyell soon after its publication, he said:

"I have just read the _Edinburgh_, which, without doubt is by ----. It is extremely malignant, clever, and, I fear, will be very damaging. He is atrociously severe on Huxley's lecture, and very bitter against Hooker. So we three _enjoyed_ it together.

Not that I really enjoyed it, for it made me uncomfortable for one night; but I have quite got over it to-day. It requires much study to appreciate all the bitter spite of many of the remarks against me; indeed I did not discover all myself. It scandalously misrepresents many parts. He misquotes some pa.s.sages, altering words within inverted commas.... It is painful to be hated in the intense degree with which ---- hates me."

As Owen was still alive when this letter was published in _Darwin's Life_, the authorship of the review was not actually mentioned; but it is necessary to mention it, as it justifies the sternness with which Huxley exposed Owen on an occasion shortly to be described. The review in the _Quarterly_ was written by Wilberforce, the Bishop of Oxford, in July, 1860, and almost at once the authorship of it became known to Darwin's friends. In connection with this, Huxley wrote in 1887, in _Darwin's Life and Letters_:

"I doubt if there was any man then living who had a better right (than Darwin) to expect that anything he might choose to say on such a question as the Origin of Species would be listened to with profound attention, and discussed with respect. And there was certainly no man whose personal character should have afforded a better safeguard against attacks, instinct with malignity and spiced with shameless impertinences. Yet such was the portion of one of the kindest and truest men that it was ever my good fortune to know; and years had to pa.s.s away before misrepresentation, ridicule, and denunciation ceased to be the most notable const.i.tuents of the majority of the mult.i.tudinous criticisms of his work which poured from the press. I am loth to rake up any of these ancient scandals from their well-deserved oblivion; but I must make good a statement which may seem overcharged to the present generation, and there is no _piece justificative_ more apt for the purpose or more worthy of such dishonour than the article in the _Quarterly Review_ for July, 1860. Since Lord Brougham a.s.sailed Dr. Young, the world has seen no such specimen of the insolence of a shallow pretender to a Master in Science as this remarkable production, in which one of the most exact of observers, most cautious of reasoners, and most candid of expositors, of this or any other age, is held up to scorn as a 'flighty' person who endeavours to 'prop up his utterly rotten fabric of guess and speculation,' and whose 'mode of dealing with nature' is reprobated as 'utterly dishonourable to natural science.' And all this high and mighty talk, which would have been indecent in one of Mr. Darwin's equals, proceeds from a writer whose want of intelligence, or of conscience, or of both, is so great, that, by way of an objection to Mr. Darwin's views, he can ask, 'Is it credible that all favourable varieties of turnips are tending to become men'; who is so ignorant of palaeontology that he can talk of the 'flowers and fruits' of the plants of the carboniferous epoch; of comparative anatomy, that he can gravely affirm the poison apparatus of venomous snakes to be 'entirely separate from the ordinary laws of animal life, and peculiar to themselves'; of the rudiments of physiology, that he can ask, 'what advantage of life could alter the shape of the corpuscles into which the blood can be evaporated?' Nor does the reviewer fail to flavour this outpouring of incapacity with a little stimulation of the _odium theologic.u.m_. Some inkling of the history of the conflicts between astronomy, geology, and theology leads him to keep a retreat open by the proviso that he cannot 'consent to test the truth of Natural Science by the Word of Revelation,' but for all that he devotes pages to the exposition of his conviction that Mr. Darwin's theory 'contradicts the revealed relation of the creation to its Creator,' and is 'inconsistent with the fulness of His glory.'"

In a footnote to this pa.s.sage, Huxley wrote that he was not aware when writing these lines that the authorship of the article had been avowed publicly. He adds, however:

"Confession unaccompanied by penitence, however, affords no ground for mitigation of judgment; and the kindliness with which Mr. Darwin speaks of his a.s.sailant, Bishop Wilberforce, is so striking an exemplification of his singular gentleness and modesty, that it rather increases one's indignation against the presumption of his critic."

As a matter of fact Wilberforce was a man of no particular information in letters or in philosophy, and his knowledge of science was of the vaguest: a little natural history picked up from Gosse, the naturalist of the seash.o.r.e, in the course of a few days' casual acquaintance at the seaside, and some pieces of anatomical facts with which he was provided, it is supposed, by Owen, for the purposes of the review. But he bore a great name, and misused a great position; he was a man of facile intelligence, smooth, crafty, and popular, and in this case he was convinced that he was doing the best possible for the great interests of religion by authoritatively denouncing a man whose character he was incapable of realising, and on whose work he was incompetent to p.r.o.nounce an opinion. Against an enemy of this kind, Huxley was implacable and relentless. He was const.i.tutionally incapable of tolerating pretentious ignorance, and he had realised from the first that there could be no question of giving and taking quarter from persons who were more concerned to suppress doctrines they conceived to be dangerous than to examine into their truth. On the other hand, much as Huxley disliked Owen's devious ways, and although in after life there occurred many and severe differences of opinion between Huxley and Owen, Huxley had a sincere respect for much of Owen's anatomical and palaeontological work, and when, in 1894, Owen's _Life_ was published, one of the most interesting parts of it was a long, fair, and appreciative review by Huxley of Owen's contributions to knowledge.

The middle of 1860, however, was not a time for Huxley, in his capacity as Darwin's chief defender, to make truce with the enemy. In England a certain number of well-known scientific men had given a general support to Darwinism. From France, Germany, and America there had come some support and a good deal of cold criticism, but most people were simmering with disturbed emotions. The newspapers and the reviews were full of the new subject; political speeches and sermons were filled with allusions to it. Wherever educated people talked the conversation came round to the question of evolution. Were animals and plants the results of special creations, or were they, including man, the result of the gradual transformations of a few simple primitive types evolving under the stress of some such force as Darwin's natural selection? To many people it seemed to be a choice between a world with G.o.d and a world without G.o.d; and the accredited defenders of religion gathered every force of argument, of misrepresentation, conscious and unconscious, of respectability, and of prejudice to crush once for all the obnoxious doctrine and its obnoxious supporters. In the autumn of that year it fell that the meeting of the British a.s.sociation, then coming into prominence as the annual parliament of the sciences, was to be held at Oxford. It was inevitable that evolution should be debated formally and informally in the sessions of the a.s.sociation, and it must have seemed to the orthodox that there, in that beautiful city, its air vibrant with tinkling calls to faith, its halls and libraries crowded with the devout and the learned, its history and traditions alike calling on all to defend the old fair piety, in such an uncongenial air, the supporters of evolution must be overwhelmed. Almost the whole weight of the attack had to be resisted by Huxley. In the various sectional meetings he had combat after combat with professors and clerics. Of these dialectic fights the most notable were one with Owen on the anatomical structure of the brain, and another with Wilberforce upon the general question of evolution. Owen contended that there were anatomical differences not merely of degree but of kind between the brain of man and the brain of the highest ape, and his remarks were accepted by the audience as a complete and authoritative blow to the theory of descent. Huxley at once met Owen with a direct and flat contradiction, and pledged his reputation to justify his contradiction with all due detail on a further occasion. As a matter of fact, he did justify the contradiction, and no anatomist would now dream of attempting the support of the proposition rashly made by Owen; but, at the time, the position of Owen and the sympathies of the audience took away much of their effect from Huxley's words. Two days later, Wilberforce, in a scene of considerable excitement, made a long, eloquent, and declamatory speech against evolution and against Huxley.

From the incomplete reports of the debate that were published, it is difficult to gain a very clear idea of the Bishop's speech; but it is certain that it was eloquent and facile, and that it appealed strongly to the religious prejudices of the majority of the audience. He ended by a gibe which, under ordinary circ.u.mstances, might have pa.s.sed simply as the rude humour of a popular orator, but which in that electric atmosphere stung Huxley into a retort that has become historical. He asked Huxley whether he was related by his grandfather's or grandmother's side to an ape. Huxley replied:

I a.s.serted, and I repeat, that a man has no reason to be ashamed of having an ape for his grandfather. If there were an ancestor whom I should feel shame in recalling, it would be a _man_, a man of restless and versatile intellect, who, not content with an equivocal success in his own sphere of activity, plunges into scientific questions with which he has no real acquaintance, only to obscure them by an aimless rhetoric, and distract the attention of his hearers from the real point at issue by eloquent digressions, and skilled appeals to religious prejudice.

An eye-witness has told the present writer that Huxley's speech produced little effect at the time. In the minds of those of the audience best qualified to weigh biological arguments, there was little doubt but that he had refuted Owen, and simply dispelled the vaporous effusions of the Bishop; but the majority of the audience retained the old convictions. The combat was removed to a wider tribunal. From that time forwards Huxley, by a series of essays, addresses, and investigations, continued almost to the end of his life, tried to convince, and succeeded in convincing, the intellectual world. At the risk of wearying by repet.i.tion we shall again insist upon the side of Darwinism that Huxley fought for and triumphed for.

Long before the time of Darwin and Huxley, almost at the beginning of recorded thought, philosophers busied themselves with the wonderful diversity of the living world and with speculations as to how it had a.s.sumed its present form. From the earliest times to this century, theories as to the living world fell into one or other of two main groups. The key-note of one group was the fixity of species: the belief that from their first appearance species were separate, independent ent.i.ties, one never springing from another, new species never arising by the modification in different directions of descendants of already existing species. The key-note of the other group of theories was the idea of progressive change: that animals and plants as they pa.s.sed along the stream of time were continually being moulded by the forces surrounding them, and that the farther back the mind could go in imagination the fewer and simpler species would be; until, in the first beginning, all the existing diverse kinds of living creatures would converge to a single point. It may be that, on the whole, the idea of fixity prevailed more among thinkers with a religious bias; but for the most part the theories were debated independently of the tenets of any faith, Christian or other. There were sceptical defenders of fixity and religious upholders of evolution. However, in Christian countries, from the time of the Reformation onwards, a change in this neutrality of religion to theories of the living world took place. As Pascal prophesied, Protestantism rejected the idea of an infallible Church in favour of the idea of an infallible book, and, because it happened that this book included an early legend of the origin of the world in a form apparently incompatible with evolution, Protestantism and, to a lesser and secondary extent, Catholicism, a.s.sumed the position that there was no place for evolution in a Christian philosophy. At the end of last century, and up to the middle of this century, the problem was not raised in any acute form. The chief anatomists and botanists were occupied with the investigation and discovery of facts, and, in an ordinary way, without taking any particular trouble about it, accepted more or less loosely the idea that species were fixed. Now and then an evolutionist propounded his views; but, as a rule, he supported them with a knowledge of facts very much inferior to that possessed by the more orthodox school. Then came Herbert Spencer, rea.s.serting evolution in the old broad spirit, not merely in its application to species, but as the guiding principle of the whole universe from the integrations of nebulae into systems of suns and planets to the transformations of chemical bodies. Before his marvellous generalisations had time to grip biologists, there came Darwin; and Darwin brought two things: first, a re-statement of the fact of evolution as applied to the living world, supported by an enormous body of evidence, new and old, presented with incomparably greater force, clearness, patience, and knowledge than had ever been seen before; and, second, the exposition of the principle of natural selection as a mechanism which might have caused, and probably did cause, evolution.

Huxley, as has been shewn, like many other anatomists, was ready for the general principle of evolution. In fact, so far as it concerned the great independent types which he believed to exist among animals, he was more than prepared for it. Let us take a single definite example of his position. In his work on the Medusae, he had shewn how a large number of creatures, at first sight diverse, were really modifications of a single great type, and he used language which, now that all zoologists accept evolution in the fullest way, requires no change to be understood:

"What has now been advanced will, perhaps, be deemed evidence sufficient to demonstrate,--first, that the organs of these various families are traceable back to the same point in the way of development; or, secondly, when this cannot be done, that they are connected by natural gradations with organs which are so traceable; in which case, according to the principles advanced in 57, the various organs are h.o.m.ologous, and the families have a real affinity to one another and should form one group.... It appears, then, that these five families are by no means so distinct as has. .h.i.therto been supposed, but that they are members of one great group, organised upon one simple and uniform plan, and, even in their most complex and aberrant forms, reducible to the same type. And I may add, finally, that on this theory it is by no means difficult to account for the remarkable forms presented by the Medusae in their young state. The Medusae are the most perfect, the most individualised animals of the series, and it is only in accordance with what very generally obtains in the animal kingdom, if, in their early condition, they approximate towards the simplest forms of the group to which they belong."

Such words, written before 1849, only differ from those that would have been written by a convinced evolutionist by a hair's breadth. But Huxley was not an evolutionist then: it was Darwin's work, containing a new exposition of evolution and the new principle of natural selection, that convinced him, not of natural selection but of evolution. At Oxford, in 1860, it was for evolution, and not for natural selection, that he spoke; and throughout his life afterwards, as he expressed it, it was this "ancient doctrine of evolution, rehabilitated and placed upon a sound scientific foundation, since, and in consequence of, the publication of _The Origin of Species_,"

that furnished him with the chief inspiration of his work. The clear accuracy of his original judgment upon Darwin's work has been abundantly justified by subsequent history. Since 1859 the case for evolution has become stronger and stronger until it can no longer be regarded as one of two possible hypotheses in the field, but as the only view credible to those who have even a moderate acquaintance with the facts. In 1894, thirty years after the famous meeting at Oxford, the British a.s.sociation again met in that historic town. The President, Lord Salisbury, a devout Churchman and with a notably critical intellect, declared of Darwin:

"He has, as a matter of fact, disposed of the doctrine of the immutability of species.... Few now are found to doubt that animals separated by differences far exceeding those that distinguish what we know as species have yet descended from common ancestors."

Huxley, in replying to the address, used the following words:

"As he noted in the Presidential Address to which they had just listened with such well deserved interest, he found it stated, on what was then and at this time the highest authority for them, that as a matter of fact the doctrine of the immutability of species was disposed of and gone. He found that few were now found to doubt that animals separated by differences far exceeding those which they knew as species were yet descended from a common ancestry. Those were their propositions; those were the fundamental principles of the doctrine of evolution."

On the other hand, Huxley all through his life, while holding that natural selection was by far the most probable hypothesis as to the mode in which evolution had come about, maintained that it was only a hypothesis, and, unlike evolution, not a proved fact. In 1863, in a course of lectures to workingmen, he declared:

"I really believe that the alternative is either Darwinism or nothing, for I do not know of any rational conception or theory of the organic universe which has any scientific position at all beside Mr. Darwin's.... But you must recollect that when I say I think it is either Mr. Darwin's hypothesis or nothing; that either we must take his view, or look upon the whole of organic nature as an enigma, the meaning of which is wholly hidden from us; you must understand that I mean that I accept it provisionally, in exactly the same way as I accept any other hypothesis."

In 1878 he wrote:

"How far natural selection suffices for the production of species remains to be seen. Few can doubt that, if not the whole cause, it is a very important factor in that operation; and that it must play a great part in the sorting out of varieties into those which are transitory and those which are permanent."

The difficulty in accepting natural selection as more than a hypothesis is simply that we have no experimental knowledge of its being able to produce the mutual infertility which is so striking a character of species. This difficulty is, in the first place, the difficulty of proving a negative. It might be possible to prove that its operation actually does produce species; it will always be impossible to prove that, in the past, natural selection, and no other known or unknown agency or combination of agencies, had a share in the process. All naturalists are now agreed that, as a matter of historical fact, it was the propounding of natural selection by Darwin that led to the acceptance of evolution, to the fact that evolution "takes its place alongside of those accepted truths which must be reckoned with by philosophers of all schools." The difficulty as to natural selection still exists, and there is no better way to express it than in Huxley's words, written in the early sixties:

"But, for all this, our acceptance of the Darwinian hypothesis must be provisional so long as one link in the chain of evidence is wanting; and, so long as all the animals and plants certainly produced by selective breeding from a common stock are fertile with one another, that link will be wanting; for, so long, selective breeding will not be proved to be competent to do all that is required of it to produce natural species.... I adopt Mr.

Darwin's hypothesis, therefore, subject to the production of proof that physiological species may be produced by selective breeding; just as a physical philosopher may accept the undulatory theory of light, subject to the proof of the existence of the hypothetical ether; or as the chemist adopts the atomic theory, subject to the proof of the existence of atoms; and for exactly the same reasons, namely, that it has an immense amount of _prima facie_ probability; that it is the only means at present within reach of reducing the chaos of observed facts to order; and, lastly, that it is the most powerful instrument of investigation which has been presented to the naturalists since the invention of the natural system of cla.s.sification, and the commencement of the systematic study of embryology."--_Man's Place in Nature_, p. 149.[E]

FOOTNOTES:

[Footnote E: Further details on the subject of this chapter may be obtained in Clodd's excellent volume, _Pioneers of Evolution_, where an account of the history of the idea of evolution from the earliest times is given; and in Poulton's _Charles Darwin and the Theory of Natural Selection_, where there is a particularly valuable chapter upon Huxley's relation to Darwinism.]

CHAPTER VIII

VERTEBRATE ANATOMY

The Theory of the Vertebrate Skull--Goethe, Oken, Cuvier, and Owen--Huxley Defends Goethe--His Own Contributions to the Theory--The Cla.s.sification of Birds--Huxley Treats them as "Extinct Animals"--Geographical Distribution--Sclater's Regions--Huxley's Suggestions.

We have seen that some of the most important of the contributions made by Huxley to zoological knowledge were in the field of the lower animals, especially of those marine forms for the study of which he had so great opportunities on the _Rattlesnake_. A great bulk of his zoological work, however, related to the group of back-boned animals.