it was considered as propounding the only, the chief, or but a subordinate cause; all that was needed to recommend the evidence of evolution to the judgment of science was the discovery of some cause which could be reasonably regarded as not incommensurate with some of the effects ascribed to it. And, unlike the desperate though most laudable groupings of Lamarck, the simple solution furnished by Darwin was precisely what was required to give a locus standi to the evidence of descent.

But we should form a very inadequate estimate of the services rendered to science by Mr. Darwin if we were to stop here. The few general facts out of which the theory of evolution by natural selection is formed-viz. struggle for existence, survival of the fittest, and heredity- were all previously wellknown facts; and we may not unreasonably feel astonished that so apparently obvious a combination of them as that which occurred to Mr. Darwin should have occurred to no one else, with the single exception of Mr. Wallace. The fact that it did not do so is most fortunate in two respects-first, because it gave Mr. Darwin the opportunity of pondering upon the subject ab initio, and next because it gave

the world an opportunity of witnessing the disinterested unselfishness which has been so signally and so consistently displayed by both these English naturalists. But the greatness of Mr. Darwin as the reformer of biology is not to be estimated by the fact that he conceived the idea of natural selection; his claim to everlasting memory rests upon the many years of devoted labour whereby he tested this idea. in all conceivable ways—amassing facts from every department of science, balancing evidence with the soundest judgment, shirking no difficulty, and at last astonishing the world as with a revelation by publishing the completed proof of evolution. Indeed, so colossal is Mr. Darwin's greatness in this respect, that we doubt whether there ever was a man so well fitted to undertake the work which he has so successfully accomplished. For this work required not merely vast and varied knowledge of many provinces of science, and the very exceptional powers of judgment which Mr. Darwin possessed, but also the patience to labour for many years at a great generalisation, the honest candour which rendered the author his own best critic, and last, though perhaps not least, the magnanimous simplicity of character which,

in rising above all petty and personal feelings, delivered a thought-reversing doctrine to mankind with as little disturbance as possible of the deeplyrooted sentiments of the age. In the chapter of accidents, therefore, it is a singularly fortunate coincidence that Mr. Darwin was the man to whom the idea of natural selection occurred; for although in a generation or two the truth of evolution might have become more and more forced upon the belief of science, and with it the acceptance of natural selection as an operating cause, in our own generation this could only have been accomplished in the way that it was accomplished; we required one such exceptional mind as that of Darwin to focus the facts, and to show the method.

It seems almost needless to turn from this aspect of our subject to enlarge upon the influence which a general acceptance of the theory of descent has had upon biology. We do not state the case too strongly when we say that this has been the influence which has created organisation out of confusion, brought the dry bones to life, and made all the previously dissociated facts of science stand up as an exceeding great army. Let any one turn to the eloquent

prophecy with which the pages of the Origin of Species terminate-a prophecy which sets forth in order the transforming effect that the doctrine of evolution would in the future exert upon every department of biology-and he may rejoice to think that Mr. Darwin himself lived to see every word of that prophecy fulfilled. For where is now the " systematist incessantly haunted by the

shadowy doubt whether this or that form be a true species"? And has it not proved that "the other and more general departments of natural history will rise greatly in interest-that the terms used by naturalists, of affinity, relationship, community of type, paternity, morphology, adaptive characters, rudimentary and aborted organs, &c., will cease to be metaphorical, and will have a plain signification"? Do we not indeed begin to feel that "we no longer look at an organic being as a savage looks at a ship, as something wholly beyond his comprehension ? and when we regard every production of nature as one which has had a long history, when we contemplate every complete structure and instinct as the summing up of many contrivances, each useful to the possessor, in the same way as any great

mechanical invention is the summing up of the labour, the experience, the reason, and even the blunders of numerous workmen, when we thus view each organic being," may we not now all say with Darwin, "How far more interesting-I speak from experience-does the study of natural history become"? And may we not now all see that a grand and almost untrodden field of inquiry on the laws of variation, on correlation, on the effects of use and disuse, on the direct action of external conditions has been opened up; that our classifications have become "as far as they can be made so, genealogies, and truly give what may be called a plan of creation;" that rules of classifying do "become simpler when we have a definite object in view;" and that "aberrant species, which may fancifully be called living fossils," actually are of service in supplying "a picture of ancient forms of life"? And again, must we not agree that "when we can feel assured that all the individuals of the same species and all the closely-allied species of most genera, have, within a not very remote period, descended from one parent, and have migrated from some one birthplace; and when we better know the many means of migration,