No. 506] DARWIN AND MUTATION THEOHY 



85 



of the whole evolutionary process. H( 

 ever, that the cause of variation was to 

 and, like all beginnings, it remains to 

 mystery. Darwin said of it: 



In another plac( 



He never definitely undertook to solve this mystery, 

 though he reflected and reasoned on it much. The near- 

 est he came to formulating a law concerning it was the 

 expression of his conviction that variability was more 

 a matter of organic constitution than a result of external 

 agencies. Thus he declares : 



been cultivated by tens of thousands during many years in many coun- 

 tries, and after having annually produced millions of buds, all of which 

 have apparently been exposed' to precisely the same conditions, yet 



stands in no direct relation to the conditions of life. 43 



From examples like this Mr. Darwin deduced a "gen- 

 eral rule that conspicuous variations occur rarely, and in 

 one individual alone out of millions, though all may have 

 been exposed, as far as we can judge, to nearly the same 

 conditions" 44 and while this is, in a general \w\\. m 

 accordance with the admission of De Vries that althoug 1 

 mutations are "not so very rare in nature, "**J he 

 bers ' ' under observation are as yet very rare, w f • 

 see a little later that Mr. Darwin's deduction is no 



