FIFTY YEARS OF DARWINISM 43 



spread among animals and probably among plants 

 also, a power of producing a definite individual 

 adaptation in response to a definite stimulus. 

 To stereotype the result would be to convert a 

 benefit to the individual into an injury to the 

 species. The beech in a very shady place would 

 presumably develop the maximum of the shade j 

 f ohage. How disadvantageous would the hered- 

 itary bias be to its oif spring that happened toi 

 grow in more exposed situations. But, it is I 

 argued, in plants subject to the fixed condition 

 we do meet with the fixed structure, just as if 

 repetition had at length produced an hereditary 

 result. The answer to this argvunent seems to 

 me to be complete. When conditions are uni- 

 form and no power of individual adaptation is j 

 required. Natural Selection, without attaining 

 the power, would produce the fixed result in the 

 usual way. If, however, a species already pos- 

 sessing the power, ultimately came to live perma- 

 nently in one set of conditions and thus ceased 

 to need it, the power itself, no longer sustained 

 by selection, would sooner or later be lost. 



DARWIN'S VIEWS ON EVOLUTION BY 

 " MUTATION " 



It is interesting to note that the term " Muta- 

 tion " appears at one time to have suggested itself 

 to Darwin ' in order to express the evolution or 



^ This seems clear from the following passage in a letter 

 written February H, 1846, to Rev. L. Blomefleld (Jenyns): 

 "Thanks for your hint about terms of 'mutation,' etc.; I had 



