x INTRODUCTION 



They die, without they change, like golden pippins ; 

 it is a generation of species like generation of indi- 

 viduals" 



"If species generate other species their race is 

 not utterly cut off." 



These quotations show that he was struggling to 

 see in the origin of species a process just as scienti- 

 fically comprehensible as the birth of individuals. 

 They show, I think, that he recognised the two 

 things not merely as similar but as identical. 



It is impossible to know how soon the ferment 

 of uniformitarianism began to work, but it is fair to 

 suspect that in 1832 he had already begun to see 

 that mutability was the logical conclusion of Lyell's 

 doctrine, though this was not acknowledged by 

 Lyell himself. 



There were however other factors of change. In 

 his Autobiography 1 he wrote: "During the voyage 

 of the Beagle I had been deeply impressed by dis- 

 covering in the Pampean formation great fossil 

 animals covered with armour like that on the 

 existing armadillos; secondly, by the manner in 

 which closely allied animals replace one another 

 in proceeding southward over the Continent; and 

 thirdly, by the South American character of most 

 of the productions of the Galapagos archipelago, 

 and more especially by the manner in which they 

 differ slightly on each island of the group ; none 

 of the islands appearing to be very ancient in a 

 geological sense. It was evident that such facts as 

 these, as well as many others, could only be explained 

 on the supposition that species gradually become 

 modified; and the subject haunted me." 



Again we have to ask: how soon did any of 

 these influences produce an effect on Darwin's 

 mind? Different answers have been attempted. 

 Huxley 2 held that these facts could not have pro- 

 duced their essential effect until the voyage had 



1 Life and Letters, i. p. 82. 2 Obituary Notice, loc. cit. 



