50 HUXLEY MEMORIAL LECTURES 



pound changed when one element in it was re- 

 placed by another. 



The evidence at our disposal led to the belief 

 that such was the state of Huxley's mind when, in 

 November, 1859, he read the " Origin." He there 

 met with far more convincing proofs of evolution 

 than he had ever encountered before, and he 

 accepted them at once, unreservedly, permanently. 

 He furthermore encountered what was to him the 

 entirely new idea of natural selection, and he 

 recognised that it disposed of his earlier objection 

 that no motive cause in any way adequate had 

 been suggested. But to the end of his life he 

 never went beyond that. He never committed 

 himself to a full belief in natural selection, and 

 even contemplated the possibility of its ultimate 

 disappearance. The difficulty which he felt 

 early and late, and about which he had a pro- 

 longed discussion with Darwin, was the fact that 

 the breeds created by the artificial selection of 

 man were mutually fertile, while the species 

 created ex hypotkesi by natural selection were 

 mutually sterile. Without going into the contro- 

 versy, it might be said that, according to Darwin, 

 Huxley's objection merely meant that the results 

 of an experiment prolonged for an immense 

 period were not in every respect the same as those 

 attained when it endured for a time compara- 

 tively brief. Students of living* nature felt a 

 confidence in natural selection which was not 

 shared by this great leader. Just as it required 

 the naturalist to discover the principle itself, so 



