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to answer it. And just as Father Wasmann 

 imagines that the agency by which evolution 

 operates is what he calls "the jnterior factors," 

 so Darwin imagined that the agency was an 

 external factor which he called "natural selec 

 tion"; but it would be just as reasonable to 

 undertake to read Father Wasmann out of the 

 school of evolution by saying that his evolution 

 is not evolution at all, but a principle of inter 

 ior factors, as to exclude Darwin because nat 

 ural selection was the agency in which he be 

 lieved. The fact is that in seeking for an ex 

 planation of the modification and coadaptation 

 which he believed he had discovered Darwin 

 imagined he had found the key to it in the 

 action of breeders who artificially selected. 

 This suggested to him the notion of a principle 

 of selection in nature which might be the 

 agency at work in evolution and the instru 

 ment of modification. Thus we see that nat 

 ural selection, while it is all-important in Dar 

 win's theory, nevertheless holds only a subor 

 dinate place, although the chief agency by 

 which evolution is supposed to be effected. 

 With Darwin evolution is the great result; 



