234 DARWIN. 



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 became modified ; and the subject haunted me. 

 But it was equally evident that neither the action of the surround- 

 ing conditions,^ nor the will of the organisms ^ (especially in the 

 case of plants), could account for the innumerable cases in which 

 organisms of every kind are beautifully adapted to their habits of 

 life ; for instance, the woodpecker or the tree frog to climb trees, 

 or a seed for dispersal, by hooks or plumes. I had always been 

 much struck by such adaptations ; and until these could be ex- 

 plained, it seemed to me almost useless to endeavour to prove by 

 indirect evidence that species have been modified." 



It was after his return In 1837 that Darwin 

 opened his first note-book for the collection of facts 

 which bore in any way on variation in animals and 

 plants under domestication and in Nature. He 

 says : " I worked on true Baconian principles, and 

 without any theory collected facts on a wholesale 

 scale, more especially with respect to domesticated 

 products, by printed inquiries, by conversation with 

 skilful breeders and gardeners, and by extensive 

 reading." This is the most deliberate and rigid 

 instance of the application of the inductive method 

 which we have met with In our whole study of the 

 contributors to the Evolution theory. Darwin soon 

 saw the force of Selection as the secret of man's 

 success In forming useful races of animals and 

 plants; and in October, 1838, while reading Mal- 

 thus on population, the idea of Selection in a state 

 of Nature first occurred to him as the result of the 



1 He here refers to Buffon's factor. 



2 He here refers to and misconceives Lamarck's factor. 



