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undoubtedly dismayed by the complexity of the role of these factors 

 and did not attempt to disentangle the mechanisms which give rise 

 to the numberless variations of living beings. 



These variations exist. He indicates them, and, without refer- 

 ring them to their immediate causes, attempts first of all to show 

 that they may be so determined as to constitute races, then new 

 species. 



Darwin had read Malthus; he recognized the law of a division 

 of labor borrowed by H. Milne-Edwards from political economy; 

 he found that the method of the sociologists was good, and that in 

 a science which was complicated and still young, as was biology, 

 one might employ the methods in use equally in meteorology, in 

 statistics, etc., in resting upon the law of great numbers without 

 seeking to discover distant causes and to penetrate to the essence 

 of the phenomena. 



Thus he showed the importance of selection for the fixing of 

 acquired characters when they offered some utility in the life- 

 struggle and thus assured the survival of their possessor through 

 a better adaptation. 



But he did not seek to establish in each particular case the 

 exact determination of the appearance of indifferent or advan- 

 tageous varieties. Perhaps he was deterred from this path by the 

 failure of his eminent predecessor, Lamarck, in the energetic effort 

 which he had made to explain in terms of surrounding conditions 

 (acting directly or indirectly by the creation of new needs) the 

 gradual modifications of living beings and the transformation of 

 species. 



We must not forget, also, that at the outset of the nineteenth 

 century, and even at the moment when the Origin of Species ap- 

 peared, the state of the physical and chemical sciences did not 

 permit of successful approach to most of the problems of external 

 physiology, the search for the solution of which had been important : 

 chemical investigations determining variations of color, the influence 

 of different kinds of radiations, the morphogenic action of saline 

 solutions, of osmosis, etc. 



However satisfactory they may have been for the mind, and 

 despite the enormous progress that they had wrought in morpho- 

 logy, the ideas of Darwin began to appear insufficient; we may 

 even believe for a moment that the exaggerations of some of the 

 disciples of the master merely compromised the triumph of the 

 doctrine and led thought back toward the finalistic explanation of 

 the ancients, now learnedly resuscitated under the name of neo- 

 vitalism. The words natural selection, mimicry, convergence, 

 heredity, and others like them, which in the thought of Darwin had 

 only a provisional value, became for the philosophers and even for 



