\\ 



r 



32 THE FACTORS OF ORGANIC EVOLUTION. 



&quot; I may take this opportunity of remarking that my critics frequently 

 assume that I attribute all changes of corporeal structure and mental power 

 exclusively to the natural selection of such variations as are often called 

 spontaneous ; whereas, even in the first edition of the Origin of Species, I 

 distinctly stated that great weight must be attributed to the inherited effects 

 of use and disuse, with respect both to the body and mind.&quot; 



Nor is this all. There is evidence that Mr. Darwin s 

 belief in the efficiency of this factor, became stronger as he 

 grew older and accumulated more evidence. The first of 

 the extracts above given, taken from the sixth edition of the 

 Origin of Species, runs thus : 



&quot;I think there can be no doubt that use in our domestic animals bas 

 strengthened and enlarged certain parts, and disuse diminished them ; and 

 that such modifications are inherited.&quot; 



Now on turning to the first edition, p. 134, it will be 

 found that instead of the words &quot; I think there can be no 

 doubt,&quot; the words originally used were &quot;I think there 

 can be little doubt.&quot; That this deliberate erasure of 

 a qualifying word and substitution of a word implying 

 unqualified belief, was due to a more decided recognition of 

 a factor originally under-estimated, is clearly implied by the 

 wording of the above-quoted passage from the preface to 

 the Descent of Han ; where he says that &quot; even in the first 

 edition of the Origin of Species/ &quot; &c. : the implication 

 being that much more in subsequent editions, and subsequent 

 works, had he insisted on this factor. The change thus 

 indicated is especially significant as having occurred at 

 a time of life when the natural tendency is towards fixity 

 of opinion. 



During that earlier period when he was discovering the 

 multitudinous cases in which his own hypothesis afforded 

 solutions, and simultaneously observing how utterly futile 

 in these multitudinous cases was the hypothesis pro 

 pounded by his grandfather and Lamarck, Mr. Darwin 

 was, not unnaturally, almost betrayed into the belief that 

 the one is all-sufficient and the other inoperative. But 

 in the mind of one so candid and ever open to more 

 evidence, there naturally came a reaction. The inheritance 



