We cannot follow in detail the profoundly suggestive chapters on Hybridism, on the Imperfection of the Geological Record, on the Geological Succession of Organic Beings, on the Geographical Distribution, and on the Mutual Affinity of Plants and Animals. The first of these is one of the most difficult portions of the subject, and yet remains as a stumbling-block of science by its apparently inexplicable phenomena. The author throws on the past history of life on the earth the glamour of a fairy record, as he contemplates the infinite number of generations, which the mind cannot grasp, which must have succeeded one another in the long roll of years, the limited extent to which at any time fossil remains have been preserved, the immense amount of destruction of such records which has taken place; and hence argues most powerfully how improbable it is that the transitional stages from species to species should have been handed down and also (another rare chance) have been laid open to us. The great array of facts about extinct animals and plants is shown to be consistent with, and to be largely explained by, descent with modification, and to be incomprehensible on any other view. The eccentric contrasts and parallelisms displayed in the geographical distribution of plants and animals, the striking effects of barriers such as mountains, deserts, and seas, the phenomena of dispersion of living creatures, the indications of old glacial periods in the present distribution of Alpine plants, the strange distribution of fresh-water animals and plants, the specialities of oceanic islands, and many other subjects of a like kind, are dealt with, all being turned to advantage, and shown to give strong support to Darwin’s view.

Classification and classifiers are all made to bear testimony in the same direction. Morphology, which, in the hands of Huxley, Haeckel, Gegenbaur, Ray Lankester, and Balfour has, since the first issue of the “Origin of Species,” grown into a coherent science, based on embryology, was even then seen by Darwin to yield evidence for his views. Examining very young animals, he found that in very distinct races of dogs and horses the young had by no means acquired their adult differences. He compared pigeons of extremely various breeds twelve hours after being hatched, and found their differences incomparably less than in the full-grown birds. How immensely morphological science has progressed since Darwin directed investigation into this profitable line would need a separate treatise to show; but it is not too much to say that embryology alone, without other evidence, would now suffice to prove the doctrine of descent with adaptive modification.

Rudimentary organs, again, strange appearances, like the presence of teeth in unborn whales and in the front of the upper jaws of unborn calves, the rudimentary wings of many insects, the rudimentary stamens or pistils of many flowers, are all swept into the Darwinian net. “Nothing can be plainer than that wings are formed for flight; yet in how many insects do we see wings so reduced in size as to be utterly incapable of flight, and not rarely lying under wing-cases, firmly soldered together?” These phenomena are all explicable if descent with modification is true.

Approaching the close of his work, the author expressed his doubts of being able to convert naturalists of long standing to his views; but based his main hopes on young and rising men approaching these questions without prejudices. He put some puzzling questions, however, to those who might oppose him. Did they really believe that at innumerable periods in the earth’s history certain atoms had been commanded suddenly to flash into living tissues? Were animals and plants created as eggs or seed or as full grown? At each act of creation was one individual or were many produced? For himself, he came to the conclusion that all organic beings had descended from some one primordial form into which life was first breathed.

On this view Darwin predicted that a great increase of interest in many departments of natural history would arise. “When we no longer look at an organic being as a savage looks at a ship, as at something wholly beyond his comprehension; when we regard every production of nature as one which has had a history; when we contemplate every complex structure and instinct as the summing up of many contrivances, each useful to the possessor, nearly in the same way as when we look at any great mechanical invention as the summing up of the labour, the experience, the reason, and even the blunders of numerous workmen; when we thus view each organic being, how far more interesting—I speak from experience—will the study of natural history become.... The whole history of the world, as at present known, although of a length quite incomprehensible to us, will hereafter be recognized as a mere fragment of time compared with the ages which have elapsed since the first creature, the progenitor of innumerable extinct and living descendants, was created.... We may look forward with some confidence to a secure future of equally inappreciable length. And as natural selection works solely by and for the good of each being, all corporeal and mental endowments will tend to progress towards perfection.” The concluding sentence of the “Origin of Species” has become one of our classical quotations. “There is grandeur in this view of life, with its several powers, having been originally breathed 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.”

This is not the place to give a history of the criticisms and discussions which arose in regard to “The Origin of Species,” especially as Darwin himself took no public part in them, except by the alterations made in successive editions. As indicating the tone of prominent critical organs, we may note that The Athenæum (November 19, 1859) acknowledges there is something poetical in the theory. “If a monkey has become a man, what may not a man become?” Neither book, author, nor subject being ordinary, “the work deserves attention.” The Edinburgh Review considered that the author left the question very nearly where he found it. Failing to find original observations adequate even to give a colour to the hypothesis, the reviewer sought to find flaws in the author’s mode of reasoning, and concluded that “we are called upon to accept a hypothesis on the plea of want of knowledge.” Defective information, vagueness, and incompleteness are charged upon the man whom we now delight to honour; “intellectual husks,” we are told; are all that he offers. Professor Huxley, who lectured at the Royal Institution, on February 10, 1860, on “Species and Races and their Origin,” and brought forward Darwin’s investigations as exemplifying that application of science to which England owes her greatness, was told that it more truly paralleled “the abuse of science to which a neighbouring nation—some seventy years since—owed its temporary degradation.” And the professor was accused of audaciously seeking to blind his audience. Samuel Wilberforce, then Bishop of Oxford, was equally denunciatory in The Quarterly. He hopes that “this flimsy speculation” will be completely put down. “It is a dishonouring view of nature.... Under such influences,” says the courtly bishop, “a man soon goes back to the marvelling stare of childhood at the centaurs and hippogriffs of fancy; or, if he is of a philosophic turn, he comes, like Oken, to write a scheme of creation under a ‘sort of inspiration,’ but it is the frenzied inspiration of the inhaler of mephitic gas. The whole world of nature is laid for such a man under a fantastic law of glamour, and he becomes capable of believing anything; and he is able, with a continually growing neglect of all the facts around him, with equal confidence and equal delusion, to look back to any past and to look on to any future.”[11]

The Saturday Review was much more moderate, by no means sharing the anxiety of those who regarded evolutionary theories as hostile to Christianity. The author is said to have encountered the difficulties of his theory “with admirable skill and ability,” and though The Saturday remained unconvinced of his general argument, yet it acknowledged itself “persuaded that natural selection must henceforward be admitted as the chief mode by which the structure of organised beings is modified in a state of nature;” and thought it very possible that, through its agency, considerable groups of nearly allied species might have been derived from a single progenitor: but there The Saturday stopped, believing in limits to this power.

The second edition of “The Origin of Species,” which appeared in January, 1860, only six weeks after the first, contained but few alterations; the third, in March, 1861, had received extensive additions and corrections. The most important of these discussed the so-called tendency of organisation to advance, and explained the present coexistence of high and lowly organised forms. A valuable historical sketch of the modern progress of opinion on the subject, from Lamarck’s time, was prefixed to the book. It was further enlarged in subsequent editions, as evidences accumulated that various thinkers had independently adopted the evolution theory, or the more special one of natural selection. Notable instances of anticipation were those of Dr. Wells, who, in a paper read before the Royal Society in 1813, but not published till 1818, had expressed the opinion that all animals tend to vary; that agriculturists improve breeds by selection; and that what they do by art “seems to be done with equal efficacy, though more slowly, by nature, in the formation of varieties of mankind.” He then goes on to exemplify the survival of the fittest, though in other words. Mr. Patrick Matthew, in 1831, published a work on “Naval Timber and Arboriculture,” in which he expressed, in scattered passages, a view nearly resembling Darwin’s.

The fourth edition of “The Origin,” in 1866, was longer, by fifty pages, than its predecessor. Among the additions may be mentioned a fuller treatment of the argument from embryology, which was made stronger by later investigations. The fifth edition (1869) was comparatively little increased in bulk, though altered in many details. In particular it contained a somewhat important change relating to the extent of the influence of natural selection. This is also referred to in “The Descent of Man” (first edition, vol. i. pp. 152-3), where the author says he had not formerly considered sufficiently the existence of many structures which appeared to be neither beneficial nor injurious, and had attributed too much to natural selection. “I was not able,” he says, “to annul the influence of my former belief, then widely prevalent, that each species had been purposely created; and this led to my tacitly assuming that every detail of structure, excepting rudiments, was of some special, though unrecognised, service.... If I have erred in giving to natural selection great power, which I am far from admitting, or in having exaggerated its power, which is in itself probable, I have, at least, as I hope, done good service in aiding to overthrow the dogma of separate creations.”

The sixth edition (1872), in smaller type, was considerably revised and altered, and remains permanent. A glossary of scientific terms was added by Mr. W. S. Dallas. A new chapter was inserted after the sixth, and entitled “Miscellaneous Objections to the Theory of Natural Selection.” It was partly derived from modified portions of chapter iv. of former editions, but the latter and larger part was new, and relates chiefly to the supposed incompetency of natural selection to account for the very early stages of useful structures. Numerous cases, such as the development of the giraffe’s neck, the baleen of the whale, the mammary glands, &c., are admirably discussed. Causes preventing the acquisition, through natural selection, of useful structures in many cases are dealt with, and reasons given for disbelieving in great and sudden modifications. In the concluding chapter Darwin further admits that he had formerly underrated the frequency and importance of use and disuse of parts, of the direct action of external conditions, and of variations which seem to us, in our ignorance, to arise spontaneously. He alludes to misrepresentations of his views, and calls attention to the fact that, in the first edition, at the close of the introduction, he stated his conviction that natural selection had been the main, but not the exclusive means of modification. “This has been of no avail. Great is the power of steady misrepresentation; but the history of science shows that, fortunately, this power does not long endure.” This is Darwin’s almost sole allusion in his works to the persistence with which views not his had been attributed to him, or he had been calumniated for views he did hold. But in his own lifetime—nay, within fifteen years—he witnessed a sufficiently satisfying revolution. “I formerly spoke to very many naturalists on the subject of evolution, and never once met with any sympathetic agreement. It is probable that some did then believe in evolution, but they were either silent or expressed themselves so ambiguously, that it was not easy to understand their meaning. Now things are wholly changed, and almost every naturalist admits the great principle of evolution” (“Origin,” sixth edition, p. 424). At present the sale of the book in this country approaches forty thousand copies. Its sale in America has been very large; and numerous translations into German, French, Italian, Russian, Dutch, and Swedish, and even into Japanese and Hindustani, have been largely sold. It must always be one of the most valued of all English classics.