[front cover]

DARWINISM: A LECTURE

BY F. W. HUTTON, F.G.S.,

(PROFESSOR OF GEOLOGY & BIOLOGY IN CANTERBURY COLLEGE, UNIVERSITY OF NEW ZEALAND),

AT THE

PHILOSOPHICAL INSTITUTE OF CANTERBURY.

SEPTEMBER 12, 1887.

Christchurch:

PRINTED AT THE "PRESS" JOB PRINTING OFFICE, CASHEL STREET.

MDCCCLXXXVII.

[title page]

DARWINISM: A LECTURE

BY F. W. HUTTON, F.G.S.,

(PROFESSOR OF GEOLOGY & BIOLOGY IN CANTERBURY COLLEGE, UNIVERSITY OF NEW ZEALAND),

AT THE

PHILOSOPHICAL INSTITUTE OF CANTERBURY.

SEPTEMBER 12, 1887.

Christchurch:

PRINTED AT THE "PRESS" JOB PRINTING OFFICE, CASHEL STREET.

MDCCCLXXXVII.

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DARWINISM

BY F. W. HUTTON, PROFESSOR OF BIOLOGY IN CANTERBURY COLLEGE.

THE subject on which I have undertaken to lecture has of late years been presented under so many forms in magazines and in books that it is difficult to find anything that will be fresh to you. Some of these books view it from the standpoint of philosophy, others from that of biology, others again from that of ethics. Certainly the artistic point of view is still vacant, we have no poem describing Darwinism, and I have seen no pictures of our hairy ancestors with pointed ears. I shall not, however, attempt to occupy that position to-night, but shall content myself with taking up much more humble ground. After some preliminary remarks on the ideas formerly associated by naturalists with the terms 'Species' and 'Genus'— a correct notion of which is absolutely necessary for understanding what follows—I shall compare the argument of Lamarck for the development of species with that of Darwin, and I shall then try to explain what Darwinism is and what it is not, what it has done and what it cannot do and this will give me an opportunity of expounding Darwin's views on inheritance and variation. As to the philosophical aspects of Darwinism I must pass them over with scarcely a word, I as am not competent to give an original opinion on that side of the question. I think I shall do more good by exposing the deep roots on which Darwinism stands. All of you I hope, know a good deal about Darwinism, for without that previous knowledge I very much doubt my ability to make so complicated a subject plain. All I expect to do is to help to clear up any haziness that may exist in your minds as to the limits of Darwinism; and to do even this I trust more to your intelligence than to my power of popular exposition.

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Passing over the views of the ancient philosophers which, although often ingenious, were not founded on careful observation, and consequently never prepared the way for further advance in knowledge, we find in the seventeenth century a general opinion prevailing that each kind of animal and plant had been separately created at the beginning of the world, and had since then increased and multiplied and covered the face of the earth. This popular belief is embodied by Milton in the seventh book of Paradise Lost, in which Raphael, "the affable archangel," tells Adam how and why the world was made. At this time the word species, although used by the ancients, had no particular meaning attached to it, but in the eighteenth century Linnæus gave precision to biological nomenclature, and defined a species as a group of animals or plants that had descended from common ancestors. "We reckon," he says, "just so many species as there were forms created in the beginning", and this definition was almost universally accepted by naturalists. It was, of course, allowed that no direct proof of the proposition could be obtained, but it was assumed that perfect fertility among the individuals, and such a close resemblance as might exist between parent and offspring, were sufficient to prove community of descent, while dissimilarity in appearance, and infertility, partial or complete, were supposed to prove that the individuals had descended from separate stocks, and, consequently, belonged to different species. It was known that in some cases very dissimilar individuals had to be included in the same species, because a series of links existed graduating one form into the other, and there were other cases in which dissimilar individuals were retained in the same species, because a series of links, although not known, was supposed to exist somewhere, or to have existed previously. The real test – fertility between the individuals —could rarely be applied, so that cases arose, and kept constantly augmenting in number, in which it was a mere matter of opinion whether two different individuals belonged to the same or to different species. It was, however, allowed that if the test of fertility could be applied it would be decisive, for it was not doubted that sterility between different species was a provision intended from the beginning to prevent confusion between

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all kinds of plants and animals. It is now known that the assumption of sterility between individuals of different species was based on a very limited number of facts and that it will not hold good in all cases.

The great difficulty of distinguishing between species and mere varieties of a species led a few naturalists — among them was Erasmus Darwin, grandfather of Charles Darwin—to doubt the doctrine of fixity of species, but it was not until Lamarck published his Philosophie Zoologique, at the commencement of the present century, that any definite idea was obtained of the rival theory of transmutation or development of species, since called Organic Evolution. Before going any farther it is necessary to explain how it was that the question became one about the origin of species and not of any of the larger groups. You are no doubt aware that, in the classification of plants and animals two or more species are united into a genus, and that genera are again grouped into families or orders. Now the group "species" was supposed to have a precise boundary, all the individuals contained in it being, as I have already said, fertile among themselves, but infertile with any individuals outside. Dr Fleming, in his Philosophy of Zoology, published in 1822, says: "The term 'species' is universally employed to characterize a group consisting of individuals possessing the greatest number of common properties, and producing without constraint a fertile progeny." But no such definite boundary could be traced for the larger groups, such as genera, &c. It was generally agreed that, while species were natural groups, i.e., real groups existing in nature, genera, families and orders were artificial inventions of naturalists, designed to facilitate classification, the number of species to be included in a genus being, to a large extent, a matter of convenience only. Mr. T. Vernon Wollaston, in a book on the "Variation of Species" published in 1855, has a chapter on "the generic theory," in which he says "the terms genus and species have been conjointly so long associated in our minds with the selfsame things, that they have become almost part and parcel of the objects themselves, so that the student who does not sufficiently reflect on their true signification is apt to regard them as of equal importance, or, more often perhaps

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than otherwise, to make the latter subservient to the former. This, however, is in reality the very reverse of what should be the case, as a moment's consideration will indeed at once convince us: for what are genera after all but dilatations, as it were, along a chain which is composed of separate, though differently shaped links? The links, or the actual independent bodies which constitute the chain, are the species, but the knobs or swellings are the groups into which those species naturally fall. It will consequently be seen from what has been said that the terms genus and species not only differ very considerably in importance, but in signification also. Whilst the former is merely suggestive of a particular position which a creature occupies in a systematic scale, the latter expresses the actual creature itself. So that while one applies to several animals of distinct natures and origins, though bound together by a certain bond of imitation, the other belongs to a single race alone, which it therefore exclusively indicates." Again, the well-known naturalist, Mr. S. P. Woodward, writing in 1856, says: "all the specimens or individuals which are so much alike that we may reasonably believe them to have descended from a common stock, constitute a species. It is a particular provision for preventing the blending of species that hybrids are always barren * * Genera are groups of species related by community of structure in all essential respects * * Families are groups of genera which agree in some more general characters than those which unite species into genera." I wish you to notice that while genera and families are defined as related by community of structure only, species are defined as related by community of descent. This opinion was generally held by naturalists before the publication of Darwin's "Origin of Species."

This long and rather dry digression has been necessary in order that you may clearly see that the group "species" was not merely an outpost in the theory of special creation, which the defenders might abandon without any serious consequences, and fall back on the larger groups, but was the very citadel itself — the keep of the castle- which, if taken, necessitated complete submission. This was well understood by naturalists, and it explains the rapidity of the campaign which I am about to describe. But

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many people, not being naturalists, have said—"We grant that different species of the same genus have descended from common ancestors, but it does not follow that this holds good for different genera." That is, they would allow that the lion, tiger, leopard, and all the cat genus, have had a common origin, but they deny that cats and dogs are in any way related. This error arose from not knowing what naturalists meant by "species," and not understanding that, if the reasons which had led naturalists to assume that each species had a distinct origin were abandoned, there was no other halting-place left, and that it was useless to take up other ground, because the same arguments which proved that the species of a genus were genetically related told with still greater force when applied to any of the larger groups, except perhaps the very largest of-all the kingdoms and sub-kingdoms. The meaning of the word genus in Greek — a race or nation with common descent – no doubt also contributed to this confusion of ideas, but the word genus never had among naturalists the same signification that it has in Greek.

To return now to our history. The Chevalier de Lamarck was a very celebrated naturalist, and Professor of Zoology in the Jardin du Roi at Paris. The first sketch of his theory is said to have been published in 1801, but the book in which it is developed bears the date of 1809, and of this I wish to give you a very short summary: taken, however, at second hand, as no copy is known to me in Christchurch. He commences by showing that species are not definitely separated by special characters, but run one into the other. Genera, orders, and even classes do the same, but these are avowedly artificial groups. Exceptions to this rule occasionally occur, but this is probably due to the connecting links not having been discovered. If we have a few individuals only before us, it is easy to establish differences, but as our knowledge increases, the difficulties of discriminating between species increase also. Varieties of a species show exactly the same thing. Now these varieties, he says, are acknowledged to be due to climate, habits, manner of living, &c. The descendants of the original species, having changed their situation, have, in consequence, become varieties.

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Why, he asks, should not these varieties go on changing until they become new species? He then refers to the great changes that have taken place in our cultivated plants and domesticated animals, and points out how impossible it is to say now from what species some of them have been derived. We cannot find in nature our cabbages and lettuces: the domestic duck has even lost its power of flight. Changes in nature, he points out, take place slowly, yet we know that in physical geography such changes have taken place, and these alterations in physical geography must have affected the climate and the local surroundings of the plants and animals. Their habits must, therefore, have changed, and this would require that organs which were formerly not much used should be more used, and consequently they would develop more. Other organs would be less used, and would be impoverished and ultimately would become rudimentary, or even be lost altogether. Consequently it is the habit that has shaped the organism. A duck was not made web-footed to enable it to swim, but it became web-footed because new wants attracted it to the water, by repeated stretching of the toes the skin acquired a habit of extension, and in time became a broad membrane. Among plants, changes in nutrition, light, moisture, &c., caused an analogous use or disuse of their parts. In addition to use and disuse of organs, Lamarck accounted for variations by an inherited tendency to vary, he talked of "the efforts of internal sentiment," of "the influence of subtle fluids," and of "acts of organisation," which caused a tendency to progressive advancement, and this, combined with the force of external circumstances, was, he thought, sufficient to explain the trans mutation of one species into another.

Lamarck's theory was altogether opposed to the teaching of the older naturalists, and, although supported by a few, was violently attacked by Cuvier and his school. Although founded on a true induction, it gave no rational explanation of the change of one species into another, and showed no efficient cause for gradual divergence of characters. The adaptive principle, although true, was made to do more work than it could bear, and the mixture of metaphysics discredited the whole. It so happened that just before

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his book was published the naturalists attached to Napoleon's army of Egypt had sent to Paris a number of mummies, including monkeys, dogs, cats, ibises, birds of prey, and crocodiles. These were certainly two or three thousand years old, and no difference could be detected between them and the same species now living in Egypt; while the present fauna and flora of the earth was supposed to date back not more than six thousand years. If, during the last two thousand years no change had been brought about, how, it was triumphantly asked, could such immense changes have taken place in six thousand years? Lamarck explained that the climate of Egypt had probably remained the same for more than two thousand years, and he protested against the supposed universal catastrophe by which all life had been destroyed six thousand years ago. But his explanation was in vain, for it was in advance of the age. The idea that the present surface of the earth, with its fauna and flora, was not very ancient, was founded partly on Biblical chronology, and partly on geological reasoning. It was said by geologists that if the earth had been old all lake basins would have been filled up, that sand-dunes would have covered much more country, that the deltas of the Nile, the Po and the Rhine would have been much larger, that the Red Sea would have been filled up by coral, while on the other hand Biblical chronologists had made different estimates of the age of the earth, varying from 3483 to 6984 years. This seemed to strengthen the opinion of James Usher, Archbishop of Armagh, who in the first half of the seventeenth century had arrived, on astronomical grounds, at the conclusion that the world had been created at six o'clock on the morning of the 11th of February, 4003 B.C., which date Dr. Lloyd, Bishop of Worcester, had added as a marginal note to a folio edition of the Bible published in 1701. The coincidence of these three lines of argument naturally seemed conclusive, but it may be as well to mention that Archbishop Usher's idea was founded upon calculations, made by astronomers, that at the time mentioned the line of equinoxes coincided with the major axis of the earth's orbit, and consequently at that time winter and summer were of equal duration all over the world. This, he thought,

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must necessarily have been the case at the creation of the earth.

The next vigorous onslaught on the doctrine of the fixity of species was made in 1844 by the "Vestiges of Creation," the author of which book was Mr. Robert Chambers. It was written in a pleasant style, and gave a popular account of the evidence in favour of the development of species, but, although disavowing Lamarck as having "scarcely a single adherent," did not advance a step beyond him. The book also contained many mistakes, especially as to the spontaneous generation of living organisms—even insects—by means of voltaic electricity, and the evident carelessness of the recorded experiments deprived the book of all scientific value. It was widely read, but had no influence on naturalists. That Lamarck had "scarcely a single adherent" was, however, not quite correct, for ever since he wrote there have always been some naturalists who believed in the theory of development of species, and as the facts of biology, and especially those of palæontology, increased, the disciples of this doctrine grew more and more numerous, but none could explain it.

While scientific men were thus groping in the dark after an indistinctly seen truth, the "Origin of Species" appeared, which not only gave a better account of the evidence for the development of species than had ever been given before, but showed the fallacy of the adverse argument from hybridism, and, above all gave a lucid explanation of how progress had been brought about by means of natural selection. It was met by a storm of abuse and opprobrium such as we now can hardly realise, and which it would be unwise to recall. Nevertheless, the effect of the book was magical. In ten years almost all naturalists were converted, in twenty years the doctrine had spread far beyond natural science into the dominions of ethics and psychology, and a little more than twenty-two years after the publication of his book Darwin was buried in Westminster Abbey, near the tomb of Sir Isaac Newton, literary men and theologians uniting with philosophers and naturalists to do honour to the memory of one of the greatest observers and thinkers that the world has ever seen.

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[The top half of this page is excised. The missing text is supplied from Hutton 1899:]

[So rapid has been the victory that I myself have seen the whole of the fight, and I trust, therefore, that a personal reminiscence will not be deemed egotistical. I was brought up in the old orthodox creed of special creation. I can well remember the time when naturalists discussed seriously such questions as: "Why the creative power had been more active in Madagascar and in Madeira than in Asia and Europe?" "Why ducks had been created with hind toes which they could not use?" "Why whales had five fingers inside their flippers? "and many other curious problems. The scales have long since fallen from our eyes, and for this we thank Charles Darwin. When the Origin of Species first came out, I read it with avidity. I could detect no flaw in the argument but thought that this must be owing to my ignorance. Soon afterwards I happened to make a geological excursion to the Isle of Wight with Sir Andrew Ramsay, then Director of the Geological Survey of Great Britain. Of course we talked in the evenings about the book, and I was surprised to find that he entirely agreed with its views. I had then, as I still have,] the greatest admiration for Professor Ramsay. I looked up to him as a model of all that a geologist should be and was astonished at his knowledge of detail in everything relating to his science. Judge therefore of the shock I felt when my cherished ideas were gently but completely taken to pieces and their hollowness exposed. Needless to say I returned from that expedition a Darwinian, and during the next six months I carefully studied the subject. About that time another geological friend, the late S. P. Mackie, editor of the Geologist, asked me to write something for his magazine, and I, brimful of youthful enthusiasm, offered an article on Darwin's book. This appeared in March and April, 1861 and, although poor enough stuff, as I now well know, it brought me an extremely kind and characteristic letter from the great Darwin himself, a letter which, I need hardly say, I have treasured ever since. You will not, I hope, accuse me of vanity if I read this letter to you. I wish to do so not on account of its reference to my article, but because any letter from Darwin

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[The top half of this page is excised. The missing text is supplied from Hutton 1899. It was subsequently republished in Autobiography (1892) and More letters (1903).]

[relating to his now famous theory must be of interest, and especially a letter written not much more than a year after his book had appeared. The letter ran as follows:

DOWN, BROMLEY, KENT,

April 20th (1861).

DEAR SIR, I hope that you will permit me to thank you for a copy of your paper in the Geologist, and at the same time to express my opinion that you have done the subject a real service by the highly original, striking and condensed manner with which you have put the case. I am actually weary of telling people that I do not pretend to adduce direct evidence of one species changing into another, but that I believe that this view in the main is correct, because so many phenomena can be thus grouped together and explained.

But it is generally of no use, I cannot make persons see this. I generally throw in their teeth the universally admitted theory of the undulation of Light—neither the undulation, nor the very existence of Ether being proved —yet admitted because the view explains so much. You are one of the very few who have seen this and have now put it most forcibly and clearly. I am much pleased to see how carefully you have read my book and what is far more important reflected on so many points with an independent spirit. As I am deeply interested in the subject (and I hope not exclusively under a personal point of view) I could not resist venturing to thank you for the right good service which you have done. —Pray believe me, dear sir, Yours faithfully and obliged, CHARLES DARWIN.]

This letter is interesting for three reasons. In the first place, it shews well the caution of Darwin, who never pretended to have proved anything beyond what the evidence warranted. In the second place, it shows his kindness and courtesy to young naturalists, who, like myself, were quite unknown to him. It is astonishing that he, in his mature judgment, should speak in terms of encouragement about a juvenile essay, which I should now regret having published, if it had not been the means of procuring me the letter I have just read to you, and, in the third place it shows how strong, at the time, the current of popular opinion must have been against him when he so much appreciated the sympathy of an unknown naturalist. How rapid has been the change! Let us try to find the reason for this by comparing the argument which failed with Lamarck with that which succeeded in the hand of Darwin.

Lamarck commenced by an induction from the facts of classification, and came to the conclusion that species do not differ essentially from varieties. So far he was right,

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but he then goes on to assume, without any reasons, that varieties are due to climate, which is not a legitimate induction from anything we know, as I shall show later on. He then argues that as changes in physical geography take place slowly, therefore climate, and with it the habits of the plants and animals, must also slowly change, and, consequently, they will pass through the stage of varieties into that of new species. The only rational explanation he gives for these changes is the use or disuse of organs, an explanation quite inadequate. The argument as to the cause of change was a failure. He gave no explanation of the extinction of intermediate forms, and his induction, that species were of a similar nature to varieties, was founded on far too limited a range of facts to carry, by itself, conviction of its truth.

Darwin sets to work very differently. He prepares the way by giving an account of the facts of variation in plants and animals under domestication and shows how these variations have been gradually accumulated, generation after generation, by the artificial selection of man, partly in a methodical way and partly unconsciously, until the most dissimilar varieties have been produced from the same stock.

These varieties of the same species he points out differ from each other in much the same manner as do the species of a genus in a state of nature. He then proceeds to give the facts of variation in a natural state, and arrives at the same conclusion that Lamarck had done before him, that species resemble varieties in many respects. But he does not stop here, he proceeds to put this conclusion to the proof by making a deduction which can be verified. He says, "If it be true that species resemble varieties, then the species of the larger genera ought to be more variable (that is, ought to contain more varieties) than the species belonging to smaller genera.["] To test this, he arranged the plants of twelve countries, and the beetles of two districts, in two nearly equal masses, the species of the larger genera on one side and those of the smaller genera on the other, and in every case it turned out that a larger proportion of the species on the side of the larger genera presented more varieties than those on the side of the smaller genera, thus verifying his conclusion.

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Having thus laid a firm foundation he next offers an explanation of how varieties change into species. He shows that plants and animals tend to increase very rapidly, while the amount of vegetation (and consequently the amount of animal life also ) which the earth can support is strictly limited, and so proves that more organisms come into existence than can possibly live, that, in fact, in each year as many must die as are born, and this gives rise to a struggle for existence.

Putting now together the fact of variation and the fact of the struggle for existence, he shows that in the long run those varieties that are best adapted to succeed in life will live the longest, and will leave most offspring, while the others will be killed off. The successful individuals will hand down their useful characters to their off spring, occasionally in a still more useful form, and thus useful variations will tend more and more to improve, and succeeding generations will diverge more and more from the original stock. This process he calls natural selection, and he shows how by its means the classification of all organic beings can be explained, and how it would necessarily tend towards a general advance of organisation, although lowly forms would still survive to occupy their appropriate places in the scheme of nature, while some might even retrograde. He then examines the laws of variation, of which he acknowledges our ignorance to be profound — discusses how much may be due to change in external conditions, and shows how use of one organ and disuse of another may bring about rudimentary structures by the unused parts be coming atrophied from want of sufficient nourishment.

This concludes the first part of his argument, and, before advancing, he proceeds to discuss the objections — including that of hybridism — that may be urged against the theory, and says that some of them are so serious that he cannot reflect on them without in some degree being staggered, but that, to the best of his judgment, the greater number are only apparent, while those that are real are not, he thinks, fatal to the theory. In this part of the book very nearly every objection that has since been made was considered in a thoroughly impartial manner, everything that could be urged against the theory being stated most

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forcibly, and its transparent honesty did a much perhaps as the previous chapters to convert naturalists to the new faith, for it showed that, after all, the argument for the immutability of species was a very weak one: and year by year the difficulties here discussed have grown fewer, while the argument in favour of the theory of development remains incontrovertible.

Having thus proved natural selection to be a true cause, and one that largely explains the origin of species from varieties by causing a gradual divergence of character, and having considered all the objections to that theory, he next proceeds to push the argument further, by passing in review all the facts of geology and biology that bear upon the subject. He treats on the geological succession of organic beings, on the geographical distribution of plants and animals, on the mutual affinities between organic beings, on morphology and homologies, on embryology, and on rudimentary organs. He shows how the theory of descent offers an easy explanation of nearly all the phenomena of organic nature, and so accumulates induction on induction as to leave no loophole for escape.

In a concluding chapter he sums up the results and points out that the chief cause of our unwillingness to admit that one species has given birth to other and distinct species, is that we are always slow in admitting great changes of which we do not see the steps. The mind cannot possibly grasp the full meaning of the term of even a million of years, it cannot add up and perceive the full effects of the many slight variations accumulated during an almost infinite number of generations, and he ends as follows: "It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing in the bushes, with various insects flitting about, and with worms crawling through the damp earth and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us. From the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is a grandeur in the view

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of life, with its several powers, having been originally breathed by the Creator into a few forms, or into one and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved."

What could resist such an encyclopædia of knowledge? What was there to oppose it? Nothing but empty rhetoric, and a réchauffé of the difficulties already considered by Darwin. It was seen that the only argument which could be urged in favour of the special-creation theory was the old one of the sterility of hybrids, and even that had broken down before the records of the numerous zoological and botanical gardens. Nothing could be done except to cover the retreat by raising a cloud of futile objections, and these soon ceased to have any weight. The victory was complete, and Darwinism has reigned ever since.

In 1871 the "Descent of Man" was published, but met with little opposition as it was an anticipated corollary from the theory of descent. As soon as it was shown that in his bodily structure and in his embryonic development, man resembled the lower animals, and especially when it was shown that man had rudimentary muscles which were useless to him, but which were well developed and useful in other mammals, it was seen that he could not be excluded from the theory. Difficulties were raised against natural selection having been the sole cause of the descent of man from the Apes, and these difficulties have not yet been overcome. At the present day no one can explain the origin of man, but all are agreed that he is descended from the lower animals.

It is generally thought that Darwin owed the idea of natural selection to Malthus. Indeed, he seems to have thought so himself for in a [1875] letter to Professor Hæckel he says, "With my mind thus prepared I fortunately happened to read Malthus's 'Essay on Population,' and the idea of natural selection through the struggle for existence at once occurred to me." But Darwin forgets for the moment that, long before this, he had stated the Malthusian doctrine more correctly than Malthus himself, for in his "Journal of a Naturalist" he says: "We do not

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steadily bear in mind how profoundly ignorant we are of the conditions of existence of every animal, nor do we always remember that some check is constantly preventing the too rapid increase of every organised being left in a state of nature. The supply of food on an average remains constant, yet the tendency in every animal to increase by propagation is geometrical, and its surprising effects have nowhere been more astonishingly shown than in the case of the European animals run wild during the last few centuries in America. Every animal in a state of nature regularly breeds, yet in a species long established any great increase in numbers is obviously impossible, and must be checked by some means." Here we have the germ of the theory of the struggle for existence stated correctly, and exactly as it was restated twenty years later. Malthus, on the contrary, says that, while man tends to increase in geometrical ratio, his means of subsistence increases in arithmetical ratio only, a statement difficult to prove, and different from that of Darwin. It is quite possible that the reading of Malthus's book may have blown into flame the spark already existing in Darwin's mind, and so may have been the means of evolving the theory of natural selection, but the whole credit really belongs to Darwin, and it was only his excessive modesty that made him push the name of Malthus to the front.

The essential feature of Darwinism is, undoubtedly, the principle of selection, but Darwin did so much to further the acceptance of the theory of descent that the whole doctrine of modern evolution is popularly associated with his name. This, however, is not correct, and Darwin himself would, I think, only claim that he had made the theory of development of species credible, and had thus indirectly influenced other subjects than biology. Darwin never used the word evolution until long after the "Origin of Species" was published. With him, as with all naturalists, it was called the development of species. The modern idea of evolution came about in this way. For some time previous to the publication of Darwin's book the idea had gradually been gaining ground that, owing to the

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radiation of heat into space, where it is lost, the energy of the solar system is gradually, but surely, being dissipated, and this dissipation of energy, added to the nebular hypothesis of Laplace, gave rise to a theory of the progress or evolution of the solar system. It was certain metaphysicians who connected this inorganic evolution with the development of species into one great doctrine of the evolution of the universe, including the hypothesis of abiogenesis, or the spontaneous generation of living matter. But they attempted no proof of this connection. Indeed, none can be given.

But, although Darwinism and the modern doctrine of evolution are two very different things, it is undoubtedly true that, but for Darwin, we should not have heard much about evolution, for it was he who taught us to believe in what is now called organic evolution, an essential part of the larger doctrine, and the one on which the greatest stress is laid by evolutionists. But, leaving on one side this supposed connection of organic with physical evolution, - a connection never agreed to by Darwin, - let us see what were the direct effects of the acceptance of the theory of the development of species.

In biology it at once revolutionised our ideas about classification. When I was young I was taught that there were two different methods of classification, called respectively artificial and natural, that there might be many different classifications under either of these heads, and that it was to a large extent a mere matter of individual opinion as to which was the best, each and all having for its aim "the double purpose of generalising acquired facts, and of facilitating the diffusion of biological knowledge, by rendering it possible to recognise plants and animals which have been already described" (Henfrey). The artificial methods had more especially as their object an easy means for finding out the name of each species, and, with this view, some one character was taken to separate the groups, another the sub-groups, and so on. A familiar example is the old Linnean classification of plants. He first divided all flowering plants with perfect flowers, into twenty classes, according to the number and coherence of the stamens, and each of these

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classes he again divided into orders, according to the number of carpels. This was very simple and easy to understand, but unfortunately it brought together plants which were evidently very unlike, and it often separated plants which were evidently closely related. Indeed, there are cases where, if the system were logically carried out, it would place in different classes different flowers on the same plant. The natural methods aimed more at bringing together plants or animals which their general structure showed to be mutually connected, and they took a combination of characters as a test of this relationship. These classifications were intended to point out the agreements among organisms, and they were only indirectly useful as a means of recognising the name of a species. The great difficulty here was to find out which characters were of more importance and which were subordinate, and this naturally gave rise to very different opinions, so that the natural systems became as numerous as the artificial ones. All was in confusion until the "Origin of Species" appeared, in which Darwin pointed out that there was only one natural system of classification, that which represented a genealogical tree. The terms affinity and relationship so long used in a metaphorical sense, had now a plain meaning, naturalists were no longer "incessantly haunted by the shadowy doubt whether this or that form be a true species," and all had the single object in view of tracing out this genealogical tree. But Darwinism did not stop here: it gave naturalists two entirely new clues wherewith to trace out genealogies. One was embryology, which, as Darwin says, will often reveal to us the structure of the prototype, the other was reversion, or atavism, by which long-lost characters are occasionally reproduced. Indeed, one of the most important discoveries of Darwin—one that will bear fruit in years to come—is the remarkable phenomenon of latent characters, a subject to which I shall refer presently.

Again, how much have biologists learnt from Darwin's experiments and observations on the effects of cross-fertilisation in plants. The discovery of a reason why there are two sexes in plants and in animals is of the highest value in physiology, while his observations on sexual

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selection among animals, and on the means of securing cross-fertilisation among plants have clearly proved that a large number of elaborately formed organs are of adaptive origin, that is, they have been gradually formed because they proved to be useful, and were not simply used because they were there. Once again, how plain is now the meaning of useless organs in plants and in animals, how often we can read their history, and see dimly the past stages in which these organs were once useful to their possessors. How true now becomes the pregnant sentence of the master, "The structure of each part of each species, for whatever purpose used, will be the sum of the many inherited changes through which that species has passed during its successive adaptations to changed habits and conditions of life." Truly, "we no longer look at an organic being as a savage looks at a ship, as something wholly beyond his comprehension", and this is the result of Darwinism.

Turning now to Geology, we find three great results from the teaching of Darwin. First, we have had our eyes opened to the imperfection of the geological record. Dimly seen at first, as the necessary effect of the destruction of rocks by the denudation of sea and rivers, its full significance has now been forced upon geologists with a hand of iron, and this has had the effect of stopping many wild speculation about universal catastrophes and the replenishment of the world. Secondly, by means of the theory of descent geologists are beginning, as Darwin said they would, to gauge with some security the relative duration of intervals of time by a comparison of the preceding with the succeeding forms of life, or in other words, we have learnt that the amount of the agreement or disagreement between two successive fossil faunas depends largely upon the length of time which separates them. And thirdly, by proving that the species of a genus, and the genera of a family, have all descended from common parents, a flood of light has been thrown on the former physical geography of the earth. By this means we can prove that Madagascar was once united to Africa, Borneo to Asia, Tasmania and New Guinea to Australia, that New Zealand has been separated

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from Australia ever since the cretaceous period, and that it has since then always remained as an island, and has never been entirely submerged below the sea. This, and much more, which I have no time even to mention, we could not have proved except for Darwinism. Indeed, by means of Darwinism, geologists can prove that there have always been land and fresh water on the face of the earth ever since the Silurian period. That since the Cambrian period there has never been a collision of the earth, or sun, or any member of the solar system, with a comet, or any other heavenly body, by which heat sufficient to destroy life on the earth has been generated. And if, knowing that the earth has supported life continuously for more than twenty millions of years, we can now, by the theory of chances, look forward trustfully to the future, and deride the prophets who foretell direful collisions with comets by which the earth shall melt away, we have to thank Darwinism for our new confidence.

There is another evil dream from which we have been relieved by Darwinism. I allude to the idea so well expressed in "In Memoriam" that Nature, red in tooth and claw with rapine, shrieked against the creed of the goodness of God as displayed in Nature.

Are God and Nature then at strife,

That Nature lends such evil dreams?

So careful of the type she seems,

So careless of the single life;

"So careful of the type?" but no.

From scarped cliff and quarried stone

She cries, "A thousand types are gone:

I care for nothing, all shall go."

Darwin has taught us that "I care for nothing all shall go" is a mistake. It is doubtless true that the individual must perish, but it perishes for the good of the race, or perhaps for the good of some other race, and, indirectly, it is by the death of the individual that progress is secured. It is only by narrowness of vision—by fixing our eyes on the individual instead of on the race—that we get the idea that God and Nature are at strife. So far as man is concerned we have every reason to believe that he will never become extinct, but that the form and proportions of his

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body, which at present distinguish him, will remain essentially the same to the end, because, by the development of his intellect his body has become liberated from the law of natural selection.

The effects of Darwinism on Psychology and Ethics have also been very great, but they are chiefly due to the development of the doctrine by others. Mr. Darwin, however, clearly saw the line his views would lead to, for in the "Origin of Species" he says: "In the future I see open fields for far more important researches. Psychology will be securely based on a new foundation, already well laid by Mr. Herbert Spencer, that of the necessary acquirement of each mental power and capacity by gradation," and though not a trained psychologist, his researches have gone far towards revolutionising that branch of inquiry. The chapter on Instinct in the Origin of Species was his first contribution in this direction, and it cleared up much ambiguity by showing that, although some instincts may be inherited habits, as taught by Lamarck, others have certainly been acquired unconsciously by means of natural selection. But of far more importance were the chapters in the "Descent of Man" on the comparison of the mental powers of man with those of the lower animals, and on the development of the intellectual and moral faculties during primeval and civilised times. Darwin himself modestly says, "This great question (the origin of the moral sense) has been discussed by many writers of consummate ability, and my only excuse for touching upon it is the impossibility of here passing it over, and because, so far as I know, no one has approached it exclusively from the side of natural history." Nevertheless, in the opinion of Mr. Romanes, no mean judge, the result of this investigation has been "to give, if not a new point of departure to the science of ethics, at least a completely new conception as to the origin of the faculties with which that science has to deal," and according to Professor Clifford, it is "the simplest and clearest and most profound philosophy that was ever written upon the subject."

Such is Darwinism, and such are some of the effects that have flowed from it. How far they will extend in the future no one can say. Nevertheless, Darwinism has its limitations, and I will now proceed to point them out.

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In the first place, natural selection does not appear to be capable of explaining all the changes that have taken place in plants and animals, but will only account for a certain number of them. This was always recognised by Darwin, and in the Introduction to the first edition of the "Origin of Species" he says distinctly, "I am convinced that natural selection has been the most important, but not exclusive means of modification", and this is repeated in all subsequent editions. Many biologists are of opinion that there is an "inherent tendency" towards higher organisation, they think that protoplasm tends to become more and more complex, and that evolution is the inevitable outcome of a fundamental property of living matter. This view is founded on the difficulty of explaining some phenomena in any other way and it may be taken merely as an expression of our ignorance, which may not be true, as a matter of fact natural selection is at present the only known efficient cause of progress or even of change.

Again, natural selection does not account for the origin of varieties. Darwin starts with the fact of variation, and shows how natural selection will affect it. On this account the name, "Origin of Species," has often been objected to, but without any reason. If the book had been called "The Origin of Species by the Natural Selection of Varieties," all ambiguity on this head would have been avoided. The origin of varieties and the laws of inheritance are not touched upon by the theory, and although Darwin deeply investigated these mysteries, and proposed a provisional hypothesis called Pangenesis to group together the facts, it forms no part of Darwinism, and it is understood that Darwin himself abandoned this hypothesis, or thought lightly of it. Still it will conduce to the understanding of the limits of Darwinism if I briefly describe Pangenesis, together with some of the known facts of inheritance and of variation, and as nearly all the facts have been collected by Darwin, the subject is strictly Darwinism, although not included in the popular sense of the word.

To take the subject of inheritance first: starting from the observed fact that a particle of living protoplasm grows by the assimilation of food, we can understand that this

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living particle, endowed as it is with the power of contraction, might, when it reached a certain size, divide into two, and thus form two individuals exactly alike, and so on ad infinitum, so long as the supply of food lasted. But what are we to think when we find that the two portions of protoplasm do not separate, but remain attached, and that each grows by numerous divisions into quite different organs? What further are we to think when we find that a portion of protoplasm, detached from this organism, will go through a development exactly similar to that of its parent? Take for example the particle of protoplasm called the oospore of a fern. This will divide into two parts, by the formation of a thin membrane of cellulose, and afterwards these two cells will develop quite differently, one forming the stem and fronds, the other the root. The root will perish altogether, but the fronds will produce spores, each one of which on germination will produce a little plant, which in its turn will produce oospores, and each of these oospores will go through exactly the same development as the first one did.

No one as yet has been able to frame any probable explanation of these facts, for Mr. Darwin never supposed that his hypothesis of Pangenesis was more than a speculation which grouped together a large number of them. This hypothesis assumes that each cell of an organism gives off minute detached particles, called gemmules, which are capable of multiplying by self-division. These gemmules circulate through the whole system and are collected together into those cells whose function it is to produce a new organism. In this way they are transmitted by the parent to the offspring, and each gemmule is then capable of development into a cell similar to that from which it was detached. But it can only develop when it finds itself in a position in the new organism similar to the position of its parent cell in the old organism. For instance, suppose that in a growing plant the cell A produced by division the cell B and that each gave off gemmules called a and ßrespectively. Then in the young plant ß can only develop on a in the same position that B held to A; and, until it finds that position, ß may be transmitted from generation to generation in an undeveloped state, but it will always be capable of development whenever it finds the necessary conditions.

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It is evident that this hypothesis does not account for the first origination of the ancestor of B; it only accounts for transmission from one generation to another. Still, so far as transmission is concerned, the hypothesis might go far towards explaining the facts of inheritance, if these facts were always constant. But such is not the case. In the first place, the force—if the expression may be allowed—the force of inheritance, although always strong, varies in different races, or even in different individuals of the same race. For instance most people know that although some lop-eared rabbits breed true, in others the tendency to produce young with drooping ears is very uncertain, and this is not due to any impurity of blood, for brothers and sisters differ much in this respect. It is not so well known that if the seeds of a "weeping" tree—that is a tree in which the branches hang down—be sown, some of the young plants will show a tendency to weep at once, others perhaps not for twenty years, others not at all. This proves incontestably that the power of transmission is individual, because it varies in different individuals, so that if these characters are due to the development of inherited gemmules, different individuals must contain different quantities of these gemmules, and consequently their number must be limited.

On the other hand, one of the most remarkable facts connected with inheritance is that transmitted characters may remain dormant, or latent, in one individual, who nevertheless may pass them on to another individual in which they may be developed. A good milking cow, for instance, can transmit her good qualities through her male offspring. Sometimes, indeed, these latent characters may be abnormally developed as when an old hen assumes the plumage and spurs of a cock and begins to crow, but usually they remain latent all through life. Indeed ancestral characters can remain latent for many generations. For example, all our various breeds of fancy pigeons are undoubtedly descended from the wild "Blue Rock," which is chiefly characterised by its blue colour, and by having two black bands on each wing and one on the tail. Everyone knows that some of the races of fancy pigeons have none of these characters. Some are pure white, some pure black, and several

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races are known to have bred true for more than a century. Yet Mr. Darwin has shown that, if any two breeds of pigeons are crossed, no matter what their colour may be, the young almost always, and in the second cross always, show a tendency to become blue and to have two black bars on the wings and one on the tail, in fact, to revert to their ancestral characters, which must, in many cases, have lain dormant for an unknown number of generations.

Now, if these characters result from the development of material bodies, or gemmules, given off by their remote ancestors, the gemmules must either be given off in numbers altogether incredible, or they must be capable of multiplying ad infinitum. But on the latter supposition, how could the power of transmission vary in different individuals? and, how could one individual inherit a character more strongly than another, as in the case just mentioned of weeping trees? If the gemmules are capable of multiplying, it is in credible that the transmission of a few more or less could make any difference. But if gemmules, either in finite or in infinite numbers, or in finite numbers but capable of infinite increase, are inadmissible, in what way can we conceive any material particles to exist? And yet without some special material body to work upon how can we conceive any force reproducing latent characters at all? Here then we have a mystery lying altogether beyond the boundary of Darwinism, and one which Darwin never pretended to have explained.

It is much the same with the facts of variation. Here also the great difficulty in framing an hypothesis that will account for the facts is the great irregularity among the facts themselves. But before giving you illustrations of this, it is necessary to remind you that offspring may differ from their parents in two ways, first by developing new characters, and secondly by reversion, or the development of latent ancestral characters. Now by variation naturalists mean the first only, but it is often not easy to decide whether a difference between parent or offspring is due to variation or to reversion.

The tendency to vary differs very much in different species of plants and animals, in some it is difficult to find

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two individuals alike, in others it is difficult to find any difference, even when a considerable number of individuals are compared. Groups of species sometimes follow the same rule, for example, the veronicas in New Zealand are among the most variable of plants, while the veronicas of Europe are remarkably stable. But more important still is the fact that the tendency to vary can be modified by man. The horticulturists when they want to prevent plants from varying sow the seed on poor soil, if, on the contrary they wish for variations, the plants are grown on good land, and separated from each other, so that they may grow vigorously. It often takes time to make a species vary. Wild flowers on first being cultivated do not vary for several years, and wild ducks when kept tame do not vary for the first five or six generations, but when in time the original colour or form shows an alteration, then variations will be abundant, and generally in many directions. Everyone knows with what rapidity new varieties of flowers are introduced by gardeners, when once the strict rule of inheritance has been broken through. Evidently the tendency to vary is increased by cultivation or domestication, and it seems connected with an excess of food. But here again we come across many anomalies, in some species domestication does not induce variation at all as in the goose or in the rye, both of which hardly vary, notwithstanding that they have been domesticated for ages. Again the variations induced by excess of food are not always accompanied by increase in size, for we have small varieties of dogs and of fowls produced by the same means as the large varieties.

Some parts are much more liable to vary than others. Colour is generally more variable than form, but the opposite may be the case in some species. Again, variation in one part is some times accompanied by variation in another part: for example, in pigeons the beak and feet vary together. Horses with a white star on the forehead generally have white feet, while in black and tan dogs tan feet go with tan spots over the eyes.

It would naturally be thought that changes in external conditions especially in climate would produce variation in the plants and animals and this was the view which Lamarck took. But a little investigation shows that this is

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not the case. No doubt any particular individual may be affected by climate as we see with trees grown in the wind or in the shade but we have every reason to think that these individual variations caused directly by the action of climate are but rarely if ever transmitted to the offspring, and do not therefore accumulate. A familiar example is found in the sheep the tails of which have been cut off for many generations and yet no farmer expects to find his lambs with short tails. The fact that many species of plants and of animals are found living almost all over the world, under the most different conditions of food and climate, without any sensible variation is alone sufficient to show that a change in external conditions does not necessarily produce variation, while the fact that variations may be produced under apparently exactly similar conditions (as when two varieties of flowers occur on the same plant), shows that change is not necessary for variation.

Again variations take place under all latitudes wherever plants and animals are found, and it is by no means necessary that the climate should be a congenial one to induce variation, for the orange, which can barely live in the north of Italy has varied there very much, and again nearly similar variations may occur under very dissimilar climates as is illustrated by the remarkable analogous varieties of pigeons in India and in Europe. If we turn to domesticated animals, we find that variability is by no means closely related to the amount of change in conditions. The most variable of domesticated birds in Europe are the pigeon, the fowl, and the duck and of these the pigeon and the duck are natives of Europe while the fowl is a native of India. On the other hand, the goose, guinea-fowl, turkey and peacock have hardly varied at all in Europe, and yet the guinea-fowl comes from Africa, the turkey from America and the peacock from India. Evidently change in external conditions will not account for variation and individual constitution is of more importance. At the same time domestication with an abundant supply of food, in time induces most plants and animals to vary and consequently change in conditions

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and in habits must in some way indirectly promote variation but whether there is in addition any innate tendency to vary we have as yet no sufficient proof.

So complicated and apparently contradictory are the facts of variation that some naturalists have assumed that no law reigns at all that in fact variation from the parent in every direction is the normal condition, and that inheritance is the law which checks variation. If we could accept this idea, it would get over many difficulties in the way of explaining evolution but Darwin, ever loyal to the truth has shown that it cannot be accepted and that the phenomena of inheritance are quite as irregular as those of variation.

On the hypothesis of Pangenesis we might look upon variation as the occasional abnormal development of gemmules in two ways, either by gemmules developing on other cells than their proper neighbour, or else that, although developing in the right place, they do not correctly reproduce the parent cell. In the first case we must suppose that the gemmule, which ought to have developed in that place, was absent and consequently that a variable species is one that produces few gemmules. This of course implies that different species give off different quantities of gemmules and consequently that their number is not infinite which once more brings upon us the difficulty of explaining latent characters. Increase of nourishment if it had any effect at all, would, we should think, tend to increase the number of gemmules, and thus to decrease the tendency to variation, but it has just the contrary effect. In the second case we must assume that the abnormal growth of the gemmules is due to the action of some external cause, and, therefore, that variation ought to show some sort of relation to changed circumstances, which can hardly be said to be the case. Still, this is conceivable, our chief difficulty in receiving the hypothesis lies in believing in the existence of gemmules at all.

And yet there are reasons for thinking that variation is due to some physical and material cause, for, if it were not so, what are we to think of monstrosities of animals born with two heads, or without any legs? and how else

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can we conceive of a necessary correlation between two different parts? But the strongest evidence that variation is due to some physical force lies in the fact that we are able to modify it, to some extent to increase or to decrease it by altering the amount of food. It is true that we can do this only to a very small extent, yet the fact of being able to influence it at all is a sufficient proof of its material nature. At present we can only accept in heritance and variation as observed facts the explanation of which is beyond the pale of Darwinism.

In 1859 the mystery of mysteries was the origin of species. It was Darwin who showed us how simple is the explanation of that mystery but he only pushed it one step back. The mystery of mysteries is still confronting us as inscrutable as ever and is now called transmission of characters. But what a change the gaining of this single step has made! When shall we take another? We have just seen that the transmission of characters and the origin of variations, in all probability depend upon physical causes and if this is the case, we may hope that they are not beyond the power of the human intellect to understand and therefore we may hope that they will be explained. The last step would be the explanation of the nature and origin of life itself, but this appears to be quite unfathomable by our senses. No one as yet has given us even a conceivable explanation, much less a possible one. It is a problem that will probably always remain shrouded in mystery although no doubt the human intellect will always be trying to solve it.

And now, ladies and gentlemen: I have explained to the best of my ability the scope and limits of Darwinism. All through the lecture I have felt the difficulty of expounding clearly so vast a subject in so short a time and I could have wished it had been placed in other hands. It was necessary for me to be concise, in order not to leave out any important point, and if at times I have been dry and obscure, I will ask you to remember this necessity for condensation, and to believe that I have tried to make my language as plain and as intelligible as possible.

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Christchurch:

THE PRESS JON PRINTING OFFICE, CASHEL STREET,

1887.