DARWIN AND WALLACE. 245 



In the struggle it would have a perfect adaptation. If any species 



better chance of surviving ; and should produce a variety having 



those of the offspring who inher- slightly increased powers of pre- 



ited the variation, be it ever so serving existence, that variety 



slight, would also have a better must inevitably in time acquire a 



chance. superiority in numbers. 



Remarkable as this parallelism 1 is, it is not com- 

 plete. The line of argument is the same, but the 

 point d'appui is different. Darwin dwells upon 

 variations in single characters, as taken hold of by 

 Selection ; Wallace mentions variations, but dwells 

 upon full-formed varieties, as favourably or unfavour- 

 ably adapted. It is perfectly clear that with Darwin 

 the struggle is so intense that the chance of sur- 

 vival of each individual turns upon a single and 

 even slight variation. With Wallace, Varieties are 

 already presupposed by causes which he does not 

 discuss, a change in the environment occurs, and 

 those varieties which happen to be adapted to it 

 survive. There is really a wide gap between these 

 two statements and applications of the theory. 



Unlike Darwin, Wallace has conserved his earlier 

 views entire ; he is still a rigid Natural Selection- 

 ist, and has incorporated the extreme views of Dar- 

 win upon the importance of variations in single 

 characters. As one of the leaders of thought in 

 contemporary Evolution, Wallace belongs chiefly 

 to the after-Darwin period. 



1 A further striking feature in this parallelism of thought is that Wallace, 

 like Darwin, first caught the suggestion of the struggle for existence from 

 reading Malthus. 



