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CHARLES DARWIN.

TO-DAY, while all that was mortal of Charles Darwin is borne to resting-place in Westminster Abbey, by the side of Sir Isaac Newton, it seems a fitting occasion to utter a few words of tribute to the memory of the beautiful and glorious life that has just passed away from us. Though Mr. Darwin had more than completed his threescore and ten years, though his life had been rich in achievement and crowned with success such as is but seldom vouchsafed to man, yet the news of his death has none the less impressed us with a sense of sudden and premature bereavement. For on the one hand the time would never have come when those of us who had learned the inestimable worth of such a teacher and friend could have felt ready to part with him; and on the other hand Mr. Darwin was one whom the gods, for love of him, had endowed with perpetual youth, so that his death could never seem otherwise than premature. As Mr. Galton has well said, the period of physical youth — say from the fifteenth to the twenty-second year — is, with most men, the only available period for acquiring the intellectual habits and amassing the stores of knowledge that are to form their equipment for the work of a life-time; but in the case of men of the highest order this period is simply a period of seven years, neither more nor less valuable than any other seven years. There is, now and then, mind — perhaps one in four or five — which in early youth thinks the thoughts of mature manhood, and which in old age retains the flexibility, the receptiveness, the keen appetite for new impressions, that are characteristic of the fresh season of youth. Such a mind as this Mr. Darwin's. To the last he was eager for new facts and suggestions, to the last he held his judgments in readiness for revision; and to this unfailing freshness of spirit was joined a sagacity which, naturally great, had been refined and strengthened by half a century most fruitful in experiences, till it had come to be almost superhuman. When we remember how Alexander how Alexander von Humboldt began at the age of seventy-five to write his Kosmos, and how he lived to turn off in his ninetieth year the fifth bulky volume of that prodigiously learned book, — when we remember this, and consider the great scientific value of the monographs which Mr. Darwin has lately been publishing almost every year, we must feel that it is in a measure right to speak of his death as premature.

After all however, no one can fail to recognize in the career of Mr. Darwin the interest that belongs to a complete and well-rounded tale. When the extent of his work is properly estimated, it is not too much to say that among all the great leaders of human thought that have ever lived there are not half a dozen who have achieved so much as he. In an age that has been richer than any preceding age in great scientific names, his name is indisputably the foremost. He has already found his place in the history of science by the side of Aristotle, Descartes, and Newton. And among thinkers of the first order of originality, he has been peculiarly fortunate in having lived to see all the fresh and powerful minds of a new generation adopting his fundamental conceptions, and pursuing their inquiries along the path which he was the first to break.

When Mr. Darwin was born, in 1809, the name which he interited was already a famous name. Dr. Erasmus Darwin, the friend of Priest and Watt, and author of Botanic Garden, was de-

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servedly ranked among the most ingenious and original thinkers of the eighteenth century in England. His brother, Robert Waring Darwin, was the author of a work on botany which for many years enjoyed high repute. Of the sons of Erasmus one, Sir Francis Darwin, was noted as a keen observer of animals; another, Charles, who died at the age of twenty-one from a dissection wound, had already written a medical essay of such importance as to give his name a place in biographical dictionaries; a third, Robert Waring, who achieved great distinction as a physician, married a daughter of the celebrated Josiah Wedgwood, and became the father of the immortal discoverer who has just been taken away from us. While citing these remarkable instances of inherited ability, it may be of interest to mention also that among the cousins of Mr. Darwin who have become more or less distinguished in our own time are Mr. Hensleigh Wedgwood, the philologist, the late Sir Henry Holland, and Mr. Francis Galton, whose excellent treatise on Hereditary Genius is known to every one. Nor can it be irrelevant to add that one of Mr. Darwin's sons has already, through his study of the tides, achieved some remarkable results, which seem likely to give him a high place among the astronomers of the present day.

There is one thing which a man of original scientific or philosophical genius in a rightly ordered world should never be called upon to do. He should never be called upon to "earn a living;" for that is a wretched waste of energy, in which the highest intellectual power is sure to suffer serious detriment, and runs the risk of being frittered away into hopeless ruin. Like his great predecessor and ally, Sir Charles Lyell, Mr. Darwin was so favored by fortune as to be free from this odious necessity. He was able to devote his whole life with a single mind to the pursuit of scientific truth, and to ministering in the most exalted way to the welfare of his fellow-creatures. After taking his Master's degree at Cambridge in 1831, at the age of twenty-two, an opportunity was offered Mr. Darwin for studying natural history on a grand scale. The Beagle, a ten-gun brig under the command of Captain Fitz Roy, was about to start on a long voyage, "to complete the survey of Patagonia and Tierra del Fuego, . . . to survey the shores of Chili, Peru, and of some islands in the Pacific, and to carry a chain of chronometrical measurements round the world." As Captain Fitz Roy had expressed a wish to have a naturalist accompany the expedition, Mr. Darwin volunteered his services, which the Lords of the Admiralty readily accepted, — a fact which in itself is sufficient evidence of the reputation for scientific attainments which Mr. Darwin had already gained at that youthful age. This memorable voyage, which lasted five years, was very fruitful in results. The general history of the voyage, with an account of such observations in natural history as seemed likely to interest the ordinary reader, is to be found in the Journal of Researches published by Mr. Darwin some three years after his return to England. This book immediately acquired a great popularity, which it has retained to this day, having gone through at least thirteen editions; and it is certainly one of the most fascinating books of travel that was ever written. "The author," said the Quarterly Review, in December, 1839, "is a firstrate landscape painter with the pen, and the dreariest solitudes are made to teem with interest." An abridgment of this charming journal, lately published with illustrations, under the title What Mr. Darwin saw in his Voyage round the World, has become a favorite book for boys and girls.

The scientific results of Mr. Darwin's voyage in the Beagle were so volumi-

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nous that it required several years and the assistance of many able hands to record them all. Owen, Hooker, Waterhouse, Berkeley, Bell, and other eminent naturalists took part in the publication of these results, which formed a very important contribution to the zoölogy and botany, and to the palæontology, of the countries visited in the course of the voyage. To this great series of volumes, which appeared between 1840 and 1846, Mr. Darwin contributed three from his own hand, — the work on Volcanic Islands, the Geological Observations on South America, and the famous essay on Coral Reefs. In this latter work Mr. Darwin proved that through gradual submergence fringing-reefs are developed into barrier-reefs, and these again into atolls or lagoon-islands; and thus he not only for the first time rendered comprehensible the work of coral-building, but threw a new and wonderful light upon the movements of elevation and subsidence in all parts of the globe. By thus bringing the work of the corals into its direct relationship with volcanic phenomena, Mr. Darwin succeeded in presenting "a grand harmonious picture of the movements which the crust of the earth has undergone within a late period; and the result was undoubtedly one of the most brilliant contributions to geology that has been made since the first publication of the great work of Sir Charles Lyell. In 1851-53 Mr. Darwin published a Monograph of the Cirripedia, in two volumes octavo, and accompanied this about the same time, with monographs of the various fossil genera of cirripeds (or barnacle family) in Great Britain. In recognition of his solid and brilliant achievements, Mr. Darwin in 1853 received the royal medal from the Royal Society, and in 1859 the Wollaston medal from the Geological Society. By this time his name had com to be known in all parts of the civilized world, and he was already ranked among the foremost living naturalists, so that when, in the year 1859, the Origin Species was published, it at once attracted universal attention by reason of the eminence of its author. I well remember how, in the first few weeks after the book was published, every one at all instructed in the biological sciences was eager to ascertain the views of so distinguished a naturalist with regard to a question which for several years had agitated the scientific world.

Like the great works which had preceded it, the Origin of Species must be regarded as one of the results of the ever memorable voyage of the Beagle. In the course of this voyage Mr. Darwin visited the Galapagos Islands, and was struck by the peculiar relations which the floras and faunas of this archipelago sustained to one another, and to the flora and fauna of the nearest mainland of Ecuador, distant some five hundred miles. These islands are purely volcanic in formation, and have never at any time been joined to the South American continent. They possess no batrachians and no mammals, save a mouse, which was no doubt introduced by some ship. The only insects are coleopters, which possess peculiar facilities for transportation across salt water upon floating logs or branches; and along with these are two or three species of land shells. There are also two snakes, one land tortoise, and four kinds of lizard; and in striking contrast with all this general extreme paucity of animal forms, there are at least fifty-five species of birds. Now these insects, mollusks, reptiles, and birds are like the insects, mollusks, reptiles, and birds of the western coast of South America, and not like the corresponding animals in other parts of the world. But this is not all; for the Galapagos animals, while very like the animals of Ecuador, Peru, Chili, are not quite like them. While the families are identical, the

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differences are always at least specific, sometimes generic in value. Precisely the same sort of relationship is sustained by the Galapagos flora toward the flora of the mainland. And, to crown all, the differences between forms that are generic when the archipelago as a whole is compared with the continent sink into specific differences when the several islands of the archipelago are compared with one another. Such a group of facts as these leads irresistibly to the conclusion that the specific forms of plants and animals have been originated, not by "special creations," but by "descent with modifications." If species have been separately created, there is of course no reason why the population of such an archipelago should be strictly limited to such organisms as can fly or get floated across the water; nor is there any reason why these organisms should resemble those of the nearest mainland rather than those of any other tropical mainland, such as Africa or India. One might indeed object that organisms have been created in such wise as most completely to harmonize with the physical conditions by which they are surrounded, and that it is to be presumed that the physical conditions of the Galapagos islands are more like those of Ecuador and Peru than they are like those of any other countries; so that in this way the general similarity between the floras and faunas may be accounted for. But such an explanation is very weak, for it rests upon an assumption which has been proved to be untrue. It is not always true that the organisms in any given part of the world are such as harmonize best with the physical conditions by which they are surrounded. It is approximately true only where the competition among organisms is practically unlimited; in protected areas it is not at all true. In Australia and Now Zealand, for example, the plants and animals which have been introduced by Europeans are exterminating and supplanting the native plants animals quite as rapidly as the Englishman is supplanting the native human poopulation of these countries. And to state this fact is only to say, in other words, that the plants and animals of Europe are better adapted to the physical conditions which prevail in Australia and New Nealand than the plants and animals which are indigenous there. A comprehensive survey of the distribution of life all over the globe confirms this conclusion,. shows that by no assumption of a special act of creation can the peculiar features of the Galapagos flora and fauna be explained. The only way in which to account for these features is to suppose that the archipelago has been peopled by migrations from the nearest mainland. This explains why the creatures there are most like the creatures of Ecuador and Peru, and it also explains why the only indigenous animals to be found there are such as could have flown or been blown thither, or such as could have been ferried thither on floating vegetation.

But if all this be true — and to-day no competent naturalist doubts it — a conclusion of vast importance immediately follows. If the Galapagos plants and animals are descended from ancestors that migrated thither from the continent, they have been modified during ages of residence in the islands, until they have come to differ specifically, and in many cases generically, from their collateral relations on the mainland. And this amounts to saying that species are not fixed, but mutable, — that every distinct form of plant and animal was not originally created with its present attributes, but that some forms have arisen from the modification of ancestral forms.

In this way, from the study of the inhabitants of a single well-defined area, Mr. Darwin was led into a series of most grand and startling considerations relating to the past history of life upon

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our globe. The conclusions thus succinctly stated were amply confirmed by survey of the distribution of organisms all over the earth, and thus was inaugurated the study of zoölogical and botanical geography, — a study which in half a century has reached such magnificent proportions in the great work, of Hooker and Wallace, and which owes its wonderful progress mainly to the sagacious impulse communicated at the outset by Mr. Darwin. It has now become well established that in very few cases, if any, have animals and plants originated exactly in the places where we now find them, but that they are almost always theoffspring of immigrants; and the study of the ancient migrations of the progenitors of living plants and animals has begun to throw a flood of light upon the history of the changes that have taken place in the physical geography of the earth.

The conception of the origin of species through "descent with modifications" having been thus forcibly suggested to Mr. Darwin by the facts of geographical distribution, it was still further strengthened by a study of the geological succession of extinct organisms and their relations to living organisms in the same areas. Such broad facts as the successive appearance of various sloth-like and armadillo-like animals in South America, or of various marsupials and monotremes in Australia, forcibly suggest the descent of the later forms from the earlier ones that lived in the same countries. Of like import is the general fact that in the course of geological succession any given organism is sure to be intermediate in character between those that have preceded and those that have followed it. But still more powerfully suggestive even than this is the fact that, in proportion as we go back in geologic time, we find the characteristics of plants and animals to be less and less distinctly specialized: so that, for example, in the Eocene period, instead of horses and tapirs such as now exist we find an animal something like a tapir and something like a horse; and instead of leopards and wolves and bears we find carnivorous animals, not specialized as of feline or canine or ursine family, but with some points of resemblance to all three, and with some points like opossums and wombats into the bargain. In conformity with this general principle, the arrangement of organisms according to their succession in geologic time would be like the branches and branchlets of a tree, which is the typical form of arrangement where the link that connects the facts arranged is the link of parentage.

But just here the facts of geological succession are reinforced, with truly overwhelming conclusiveness, by the great facts of classification in the animal and vegetable kingdoms. This branching tree-like arrangement, which alone correctly represents the relationships of organisms in their geological succession, is at the same time the only possible arrangement by which the likenesses and affinities among existing organisms can be represented with anything like an approach to correctness. The facts of palæontology exactly dovetail in with those of taxonomy, and serve to elucidate and emphasize them. Many eminent naturalists before Cuvier attempted to classify all animals in a linear series, but Cuvier proved once for all that no such arrangement is possible. The only feasible arrangement is that of groups within groups, diverging like the branches and twigs of what we aptly term a "family-tree;" and this fact not only strongly suggests the theory of "descent with modifications," but is indeed utterly incompatible with any other theory.

Further powerful evidence in favor of the same view is furnished by countless familiar facts of morphology and embryology. On the theory of "de-

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scent with modifications," it is intelligible that all the classes and orders of the vertebrate sub-kingdom, for example, should be constructed on exactly the same fundamental plan, — that the arms of men, the fore-legs of quadrupeds, the paddles of cetacea, the wings of birds, and the pectoral fins of fishes should be structurally identical with one another. It is intelligible that a horse's hoof should be, as it is, made up of toes that have grown together. It is intelligible that every mammalian embryo should begin, as it does, to develop if it were going to become a fish, circulating its blood through gills and a two-chambered heart, and then, changing its course, should behave as if it were going to become a reptile or bird and only after long delay should assume the distinctive characteristics of mammality. It is intelligible that many snakes should possess beneath their skin the rudiments of limbs; that sundry insects, which never fly, should have wings firmly fastened down to their sides; and that the embryos of many birds, while developing in the egg, should grow temporary teeth within their little beaks. But it is only on one theory of "descent with modifications" that such facts, which are in no wise exceptional, but common throughout the entire animal kingdom, have any meaning whatever.

Many of these facts had been noticed by eminent naturalists before Mr. Darwin, and their incompatibility with any theory of special creations had also been observed; but it was Mr. Darwin who first marshaled them into one mighty argument, of which the cumulative result was that the phenomena of the organic world are unintelligible from beginning to end save on the theory of "descent with modifications." Had Mr. Darwin done nothing but this, it would have given him a peculiar right to associate his name with the development theory, it would have established that theory on a basis of "convincing probability," and it would have entitled him to a high place in the history of scientific thought in the nineteenth century. But Mr. Darwin did not stop here. Convinced by such considerations as those just presented that the specific characters of plants and animals are not constant, but variable, he sought for some grand all-pervading cause of variation in organisms, and his search was crowned with success. This was the achievement which in his hands raised the development theory from the rank of a brilliant philosophical speculation into the rank of an irrefragable scientific discovery. This was the achievement which gave to mankind a new implement of research and a new insight into the workings of Nature, and it was this which justifies us in placing Mr. Darwin's name beside those of Newton and Descartes.

The method by which Mr. Darwin succeeded in discovering the cause of variation in organisms was the thoroughly scientific method of advancing tentatively from the known to the unknown. Are there any instances in which the forms of plants and animals have actually been seen to vary, and, if there are, what seems to have been the principal cause of variation in these instances? The answer is not far to seek. The instances are very numerous indeed in which variations — and very marked ones, too — have been wrought in the characteristics of plants and animals through the agency of man. The phenomena of variation presented by animals and plants under domestication are so numerous and so complex that it would require many volumes to describe them. Dogs, horses, pigs, cattle, sheep, rabbits, pigeons, poultry, silk-moths, cereal and culinary plants, fruits and flowers innumerable, have been reared and bred by man for many long ages, — some of them from time immemorial. These domesticated organisms man has caused to vary, in one direc-

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tion or another, to suit his natural or artificial needs, or even the mere whim of his fancy. The variations, moreover, which have thus been produced have been neither slight nor unimportant, and have been by no means confined to superficial characteristics. Compare the thorough-bred race-horse with the gigantic London dray-horse on the one hand, and the Shetland pony on the other; or, among pigeons, contrast the pouter with the fan-tail, the barb, the short-faced tumbler, or the jacobin, all of which are historically known to have descended from one and the same ancestral form. The differences extend throughout the whole bony framework as well as throughout the muscular and nervous systems, and exceed in amount the differences by which naturalists often adjudge species to be distinct. Through what agency has man produced such results as these? He has produced them simply by taking advantage of a slight tendency to variation which exists perpetually in all plants and animals, and which exhibits itself in the simple fact that nowhere do we ever find any two individuals exactly alike. Taking advantage of these individual variations, the breeder simply selects the individuals which best suit his purpose, and breeds them apart by themselves. The qualities for which they are selected are propagated and enhanced through inheritance and renewed selection in each succeeding generation, until by the slow accumulation of small differences a new race la formed. And thus we have peaches and almonds from a common source, grapes to eat and grapes to make wine of, pointer-dogs and mastiffs, and so on throughout the list of cultivated plants and domesticated animals.

These facts about variation under domestication are for the most part well known, and the alleged cause of variation, in selection by man, is not an oscult cause, but is a phenomenon perfectly familiar to every one. Starting from this point, Mr. Darwin made a very elaborate study of all that farmers, horticulturists, and breeders could impart concerning. "artificial selection;" and more especially with regard to pigeons his own observations were so extensive and minute that, when the Origin of Species was published, I recollect reading one silly review, in which we were gravely informed that here was a new theory of development, — not by a naturalist, but by a mere pigeon-fancier, and probably worthy of very little consideration!

Such being the wonders which man has wrought within a comparatively short time though "artificial selection" in the breeding of animals and plants, the question next arises whether any selective process like this has been going on through countless ages without the intervention of man. Can it be that there is a "natural selection" of individual variations, whereby new species are produced in just the same way that breeders produce new races of pigeons? There is such a "natural selection" for ever going on as one of the inseparable concomitants of organic; and it was just in the detection of this great truth that the very kernel of Mr. Darwin's stupendous discovery consisted. It was here that the poetic or creative act of genius came into play, just as it dit Newton's discovery, when the fall of the moon was likened to the fall of the apple, and the tangential force of the moon to the tangential force of a stone whirled at the end of a string. The case is simple enough, when creative genius has once explained it. So great is the destruction of organic life that out of hundreds of seeds, or spawn, or ova but one or two ever live to, come to maturity and reproduce themselves in offspring. Such is the result of the universal and unrelenting competition between organisms for the means of subsistence. Any creature that lives to reproduce its kind is selected from out of a thousand that

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perish prematurely, and its selection is evidence of its better adaptation to the conditions amid which it is placed. And so stern and so ubiquitous is the competition that there is no individual variation, however slight or apparently trivial, that is not liable to be seized upon and enhanced if it tend in any way to promote the survival of the species. Thus it is natural selection that at every moment preserves the stability of a species, and keeps it in harmony with its environment, by cutting off all individual variations that oscillate too far on either side of a prescribed mean. The stability of a species depends, therefore, upon the stability of the environment; and the only condition under which a species could remain unchanged would be that it should remain forever exposed to the action of changeless groups of circum stances. But this has never been the case with any species, and never will be. The habitable surface of the earth has been perpetually changing for a hundred million years, and the relations between the coundless groups of organisms that have covered its surface have been perpetually changing in endless degrees of complexity; and in such a world, under the working of natural selection, there can be no such thing as "fixity of species."

Having arrived at these grand conclusions, it became comparatively easy for Mr. Darwin to go on and trace the workings of natural selection in many special instances. In these inquiries, upon which he brought to bear a knowl edge of the details of organic life more vast and multifarious than has ever been possessed by any other man, he occupied, pied nearly a quarter of a century before it seemed to him that the time had come for making his discovery known the world. In 1844, he wrote out a brief sketch of the conclusions which, as he modestly says, "then seemed to me probable;" and this sketch he showed to his friend Hooker, perhaps also to Lyell. But fifteen years more, rich in observation and reflection, passed away, and still the world had heard nothing about the origin of species by means of natural selection. How much longer this silence might have lasted, had not an unforeseen circumstance come in to break it, one cannot say. But no doubt it would have lasted some time longer, for Mr. Darwin did not wish to publish his conclusions until he had given due attention to every fact and every argument which might in any way bear upon them; and it is quite evident that when he wrote the Origin of Species he did not realize either the wonderful maturity which his argument had attained, or the overwhelming cogency with which he was then actually presenting it to the world. It was very characteristic of Mr. Darwin — into the fibre of whose mind there entered not the smallest shred of egotism or of the pride of knowledge — to make so many allowances for the inevitable incompleteness of his work, when judged by that standard of ideal perfection which he alone among men was able to apply to it, as to have rendered himself incapable for the time being of appreciating its real magnitude. In writing the Origin of Species, he regarded the book as merely a preliminary outline of his theory, which would serve to prevent his being forestalled by any one else in the announcement of it, and he made frequent allusions to the larger and more elaborate treatise in which he intended presently to follow up the exposition and to reinforce the argument. When I first met Mr. Darwin in London, in 1873, he told me that he was surprised at the great fame which his book instantly won, and at the quickness with which it carried conviction to the minds of all the men on whose opinions he set the most value. The success of his theory was, indeed, wonderfully rapid and complete. To understand him was to agree with him, and before ten years

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more had passed by, so many able men had become expounders and illustrators of the theory of natural selection that — as he told me — it seemed no longer so necessary as it had once seemed for him to write the larger and more elaborate treatise. The learned work on the Variation of Animals and Plants under Domestication, which appeared in 1868 in two octavo volumes, formed the first installment of this long-projected treatise. The second part was to have treated of the variation of animals and plants through natural selection; and a third part would have dealt at length with the phenomena of morphology', of classification, and of distribution in space and time. But these second and third parts were never published.

I alluded, just now, to the "unfore-seen circumstance" which led Mr. Darwin in 1859 to break his long silence, and to write and publish the Origin of Species. This circumstance served, no less than the extraordinary success of his book, to show how ripe the minds of men had become for entertaining such views as those which Mr. Darwin propounded. In 1858 Mr. Wallace, who was then engaged in studying the natural history of the Malay Archipelago, sent to Mr. Darwin (as to the man most likely to understand him) a paper, in which he sketched the outlines of a theory identical with that upon which Mr. Darwin had so long been at work. The same sequence of observed facts and inferences that had led Mr. Darwin to the discovery of natural selection and its consequences had led Mr. Wallace to the very threshold of the same discovery; but in Mr. Wallace's mind the theory had by no means been wrought out to the same degree of completeness to which it had been wrought in the mind of Mr. Darwin. In the preface to his charming book on Natural Selection, Mr. Wallace with rare modesty and candor, acknowledges that, whatever value his speculations may have had, they have been utterly surpassed in richness and cogency of proof by those of Mr. Darwin. This is no doubt true, and Mr. Wallace has done such good work in further illustration of the theory that he can well afford to rest content with the second place in the first announcement of it.

The coincidence, however, between Mr. Wallace's conclusions and those of Mr. Darwin was very remarkable. But, after all, coincidences of this sort have not been uncommon in the history of scientific inquiry. Nor is it at all surprising that they should occur now and then, when we remember that a great and pregnant discovery must always be concerned with some question which many of the foremost minds the world are busy in thinking about. It was so with the discovery of the differential calculus, and again with the discovery of the planet Neptune. It was so with the interpretation of the Egyptian hieroglyphics, and with the establishment of the undulatory theory of light. It was so, to a considerable extent, with the introduction of the new chemistry, with the discovery of the mechanical equivalent of heat, and the whole doctrine of the correlation of forces. It was so with the invention of the electric telegraph and with the discovery of spectrum analysis. And it is not at all strange that it should have been so with the doctrine of the origin of species through natural selection. The belief that all species have originated through derivation from other species, and not through special creation, had been held by part of the scientific world ever since the time of Mr. Darwin grandfather, who was one of its earlist and most eminent advocates, Even those naturalists who did not hold this belief can hardly be said to have held any antagonistic belief, inasmuch as the so-called "doctrine of special creations" is not a positive doctrine at

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all, but a mere confession of ignorance, and was so regarded by scientific naturalists, such as Owen, for example, before 1859. The truth is that before the publication of the Origin of Species there was no opinion whatever current respecting the subject that deserved to be called a scientific hypothesis. That the more complex forms of life must have come into existence through some process of development from simpler forms was no doubt the only sensible and rational view to take of the subject; but in a vague and general opinion of this sort there is nothing that is properly scientific. A scientific hypothesis must connect the phenomena with which it deals by alleging a "true cause," and before 1859 no one had suggested a "true cause" for the origination of new species, although the problem was one over which every philosophical naturalist had puzzled since the beginning of the century. This explains why Mr. Darwin's success was so rapid and complete, and it also explains why he came so near being anticipated. His long delay, however, in bringing forward his theory had one good result. The work was so thoroughly done that, although Darwinism has now for twenty-three years been one of the chief subjects of popular discussion in all the civilized countries of the world, no one as yet seems to have discovered any argument against the theory of natural selection which Mr. Darwin had not himself already fore-seen and considered in the first edition of the Origin of Species.

After an interval of twelve years Mr. Darwin followed up the first announcement of his general theory with his treatise on the Descent of Man, a book which deals with a subject in one respect even more difficult than the origin of species. In his earlier book Mr. Darwin, with masterly skill, brought together huge masses of facts, and showed their bearings upon a few general propositions relating to the whole organic world. In the Descent of Man the problem was different. Propositions of great generality, such as had been established in the Origin of Species, served here as fundamental principles; but they had to be supplemented by a consideration of the enormously complex and heterogeneous circumstances which attended the origination of a particular genus. It is enough to say that in the treatment of this arduous problem Mr. Darwin showed no less acuteness and grasp than had been displayed in his earlier work.

In connection with this problem of the origin of the human race,. Mr. Darwin announced the results of his extensive researches into the subject of sexual selection in the animal kingdom. Some time before this, in his treatise on the Fertilization of Orchids, published in 1862, he had called attention to the interdependence between the insect world and the world of flowers. Further research in this direction has made it clear that the beautiful colors and sweet odors of flowers are due selection on the part of insects. The bright colors and delicious perfumes attract insects, who come to sip the nectar, and carry away on their backs the pollen with which to fertilize the next plant they visit. Thus the fairest and sweetest flowers are continually selected to perpetuate their race, and thus have insects and flowering plants been developed in close correlation with one another.

It was Mr. Darwin, good fortune to live long enough to see his theory not only adopted by all competent naturalists, but demonstrated by crucial evidence in the case of one genus. The researches of Professor Marsh into the palæontology of the horse have established beyond question the descent of the genus equus from a five-toed mammal not larger than a pig, and somewhat resembling a tapir. All the "missing links" in this case have been found;

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and thus the primitive barbaric hypothesis of "special creations" may be said to have disappeared forever from the field of natural history. It has taken its place by the side of the Ptolemaic astronomy and the dreams of the alchemists.

Mr. Darwin's latest books belong to a period in which, having lived to witness the complete success of his great work, he has employed his time in recording the results of his researches on many subsidiary points, of no little interest and importance. The treatises on the Expression of the Emotions in Man and Animals, on the Movements and Habits of Climbing Plants, on Insectivorous Plants, on Cross and Self Fertilization, on the Different Forms of Flowers, and on the Formation of Vegetable Mould through the Action of Worms should be read as models of sound scientific method by every one who cares to learn what scientific method is. They may be counted, too, among the most entertaining books of science that have ever been written; and the points that have been established in them, taken in connection with Mr. Darwin's previous works, make up an aggregate of scientific achievement such as has rarely been equaled.

It is fitting that in the great Abbey, where rest the ashes of England's noblest heroes, the place of the discoverer of natural selection should be near that of Sir Isaac Newton. Since the publication of the immortal Principia, no scientific book has so widened the mental horizon of mankind as the Origin of Species. Mr. Darwin, like Newton, was a very young man when his great discovery suggested itself to him. Like Newton, he waited many years before publishing it to the world. Like Newton, he lived to see it become part and parcel of the mental equipment of all men of science. The theological objection urged against the Newtonian theory by Leibnitz, that it substituted the action of natural causes for the immediate action of the Deity, was also urged against the Darwinian theory by Agassiz; and the same objection will doubtless continue to be urged against scientific explanations of natural phenomena so long as there are men who fail to comprehend the profoundly theistic and religious truth that the action of natural causes is in itself the immediate action of the Deity. It is interesting, however, to see that, as theologians are no longer frightened by the doctrine of gravitation, so they are already outgrowing their dread of the doctrine of natural selection. On the Sunday following Mr. Darwin's death, Canon Liddon, at St. Paul's Cathedral, and Canons Barry and Prothero, at Westminster Abbey, agreed in referring to the Darwinian theory as "not necessarily hostile to the fundamental truths of religion." The effect of Mr. Darwin's work has been, however, to remodel the theological conceptions of the origin and destiny of man which were current in former times. In this respect it has wrought a revolution as great as that which Copernicus inaugurated and Newton completed, and of very much the same kind. Again has man been rudely unseated from his imaginary throne in the centre of the universe, but only that he may learn to see in the universe and in human life a richer and deeper meaning than he had before suspected. Truly, he who unfolds to us the way in which God works through the world of phenomena may well be called the best of religious teachers. In the study of the organic world, no less than in the study of the starry heavens, is it true that "day unto day uttereth speech, and night unto night showeth knowledge."

John Fiske.