258 LIFE AND HABIT. 



supposes to have been the case in this instance, by 

 "natural selection"? After attributing many of the 

 structural and instinctive differences of plants and 

 animals to the effects of use — as we may plainly do 

 with Mr. Darwin's own consent — after attributing a 

 good deal more to unknown causes, and a good deal 

 to changed conditions, which are bound, if at all im- 

 portant, to result either in sterility or variation — how 

 much of the work of originating species is left for 

 natural selection ? — which, as Mr. Darwin admits 

 ("Natural Selection," p. 63, ed. 1876), does not induce 

 variability, but * implies only the preservation of such 

 variations as arise, and are beneficial to the being under 

 its conditions of life?" An important part assuredly, 

 and one which we can never sufficiently thank Mr. 

 Darwin for having put so forcibly before us, but an 

 indirect part only, like the part played by time and 

 space, and not, I think, the one which Mr. Darwin 

 would assign to it. 



Mr. Darwin himself has admitted that in the 

 earlier editions of his " Origin of Species " he " under- 

 rated, as it now seems probable, the frequency and 

 importance of modifications due to spontaneous vari- 

 ability." And this involves the having over-rated the 

 action of * natural selection " as an agent in the evolution 

 of species. But one gathers that he still believes the 

 accumulation of small and fortuitous variations through 

 the agency of " natural selection " to be the main cause 

 of the present divergencies of structure and instinct. I 

 do not, however, think that Mr. Darwin is clear about 

 his own meaning. I think the prominence given to 



