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to be the case some day。 Anyhow； one may be excused in not having discovered the fact in a work on Naval Timber。〃 （〃Life and Letters〃 II。 page 301。）
De Quatrefages and De Varigny have maintained that the botanist Naudin stated the theory of evolution by natural selection in 1852。 He explains very clearly the process of artificial selection； and says that in the garden we are following Nature's method。 〃We do not think that Nature has made her species in a different fashion from that in which we proceed ourselves in order to make our variations。〃 But； as Darwin said； 〃he does not show how selection acts under nature。〃 Similarly it must be noted in regard to several pre…Darwinian pictures of the struggle for existence （such as Herder's； who wrote in 1790 〃All is in struggle。。。each one for himself〃 and so on）； that a recognition of this is only the first step in Darwinism。
Profs。 E。 Perrier and H。F。 Osborn have called attention to a remarkable anticipation of the selection…idea which is to be found in the speculations of Etienne Geoffroy St Hilaire （1825…1828） on the evolution of modern Crocodilians from the ancient Teleosaurs。 Changing environment induced changes in the respiratory system and far…reaching consequences followed。 The atmosphere； acting upon the pulmonary cells； brings about 〃modifications which are favourable or destructive （'funestes'）； these are inherited； and they influence all the rest of the organisation of the animal because if these modifications lead to injurious effects； the animals which exhibit them perish and are replaced by others of a somewhat different form； a form changed so as to be adapted to （a la convenance） the new environment。〃
Prof。 E。B。 Poulton （〃Science Progress〃； New Series； Vol。 I。 1897。 〃A Remarkable Anticipation of Modern Views on Evolution〃。 See also Chap。 VI。 in 〃Essays on Evolution〃； Oxford； 1908。） has shown that the anthropologist James Cowles Prichard （1786…1848） must be included； even in spite of himself； among the precursors of Darwin。 In some passages of the second edition of his 〃Researches into the Physical History of Mankind〃 （1826）； he certainly talks evolution and anticipates Prof。 Weismann in denying the transmission of acquired characters。 He is； however； sadly self… contradictory and his evolutionism weakens in subsequent editionsthe only ones that Darwin saw。 Prof。 Poulton finds in Prichard's work a recognition of the operation of Natural Selection。 〃After enquiring how it is that 'these varieties are developed and preserved in connection with particular climates and differences of local situation；' he gives the following very significant answer： 'One cause which tends to maintain this relation is obvious。 Individuals and families； and even whole colonies； perish and disappear in climates for which they are； by peculiarity of constitution； not adapted。 Of this fact proofs have been already mentioned。'〃 Mr Francis Darwin and Prof。 A。C。 Seward discuss Prichard's 〃anticipations〃 in 〃More Letters of Charles Darwin〃； Vol。 I。 page 43； and come to the conclusion that the evolutionary passages are entirely neutralised by others of an opposite trend。 There is the same difficulty with Buffon。
Hints of the idea of Natural Selection have been detected elsewhere。 James Watt （See Prof。 Patrick Geddes's article 〃Variation and Selection〃； 〃Encyclopaedia Britannica （9th edition） 1888。）； for instance； has been reported as one of the anticipators （1851）。 But we need not prolong the inquiry further； since Darwin did not know of any anticipations until after he had published the immortal work of 1859； and since none of those who got hold of the idea made any use of it。 What Darwin did was to follow the clue which Malthus gave him； to realise； first by genius and afterwards by patience； how the complex and subtle struggle for existence works out a natural selection of those organisms which vary in the direction of fitter adaptation to the conditions of their life。 So much success attended his application of the Selection…formula that for a time he regarded Natural Selection as almost the sole factor in evolution； variations being pre… supposed； gradually； however； he came to recognise that there was some validity in the factors which had been emphasized by Lamarck and by Buffon； and in his well…known summing up in the sixth edition of the 〃Origin〃 he says of the transformation of species： 〃This has been effected chiefly through the natural selection of numerous successive； slight； favourable variations； aided in an important manner by the inherited effects of the use and disuse of parts； and in an unimportant manner； that is； in relation to adaptive structures； whether past or present； by the direct action of external conditions； and by variations which seem to us in our ignorance to arise spontaneously。〃
To sum up： the idea of organic evolution； older than Aristotle； slowly developed from the stage of suggestion to the stage of verification； and the first convincing verification was Darwin's； from being an a priori anticipation it has become an interpretation of nature； and Darwin is still the chief interpreter； from being a modal interpretation it has advanced to the rank of a causal theory； the most convincing part of which men will never cease to call Darwinism。
III。 THE SELECTION THEORY
By August Weismann。 Professor of Zoology in the University of Freiburg （Baden）。
I。 THE IDEA OF SELECTION。
Many and diverse were the discoveries made by Charles Darwin in the course of a long and strenuous life； but none of them has had so far…reaching an influence on the science and thought of his time as the theory of selection。 I do not believe that the theory of evolution would have made its way so easily and so quickly after Darwin took up the cudgels in favour of it； if he had not been able to support it by a principle which was capable of solving； in a simple manner； the greatest riddle that living nature presents to us；I mean the purposiveness of every living form relative to the conditions of its life and its marvellously exact adaptation to these。
Everyone knows that Darwin was not alone in discovering the principle of selection； and that the same idea occurred simultaneously and independently to Alfred Russel Wallace。 At the memorable meeting of the Linnean Society on 1st July； 1858； two papers were read （communicated by Lyell and Hooker） both setting forth the same idea of selection。 One was written by Charles Darwin in Kent； the other by Alfred Wallace in Ternate； in the Malay Archipelago。 It was a splendid proof of the magnanimity of these two investigators； that they thus； in all friendliness and without envy； united in laying their ideas before a scientific tribunal： their names will always shine side by side as two of the brightest stars in the scientific sky。
But it is with Charles Darwin that I am here chiefly concerned； since this paper is intended to aid in the commemoration of the hundredth anniversary of his birth。
The idea of selection set forth by the two naturalists was at the time absolutely new； but it was also so simple that Huxley could say of it later； 〃How extremely stupid not to have thought of that。〃 As Darwin was led to the general doctrine of descent； not through the labours of his predecessors in the early years of the century； but by his own observations； so it was in regard to the principle of selection。 He was struck by the innumerable cases of adaptation； as； for instance； that of the woodpeckers and tree…frogs to climbing； or the hooks and feather…like appendages of seeds； which aid in the distribution of plants； and he said to himself that an explanation of adaptations was the first thing to be sought for in attempting to formulate a theory of evolution。
But since adaptations point to CHANGES which have been undergone by the ancestral forms of existing species； it is necessary； first of all； to inquire how far species in general are VARIABLE。 Thus Darwin's attention was directed in the first place to the phenomenon of variability； and the use man has made of this； from very early times； in the breeding of his domesticated animals and cultivated plants。 He inquired carefully how breeders set to work； when they wished to modify the structure and appearance of a species to their own ends； and it was soon clear to him that SELECTION FOR BREEDING PURPOSES played the chief part。
But how was it possible that such processes should occur in free nature？ Who is here the breeder； making the selection； choosing out one individual to bring forth offspring and rejecting others？ That was the problem that for a long time remained a riddle to him。
Darwin himself relates how illumination suddenly came to him。 He had been reading； for his own pleasure； Malthus' book on Population； and； as he had long known from numerous observations； that every species gives rise to many more descendants than ever attain to maturity； and that； therefore； the greater number of the descendants of a species perish without reproducing； the idea came to him that the decision as to which member of a species was to perish； and which was to attain to maturity and reproduction might not be a matter of chance； but might be determined