316 Darwin, and after Darwin. 



So much, then, by way of generalities. But perhaps 

 the proof of natural selection as an agency of the first 

 importance in the transmutation of species may be best 

 brought home to us by considering a few of its 

 applications in detail. I will therefore devote the rest 

 of the present chapter to considering a few cases of this 

 kind. 



There are so many large fields from which such 

 special illustrations may be supplied, that it is difficult 

 to decide which of them to draw upon. For instance, 

 the innumerable always interesting, and often aston- 

 ishing adaptations on the part of flowers to the 

 fertilising agency of insects, has alone given rise to an 

 extensive literature since the time when Darwin him- 

 self was led to investigate the subject by the guidance 

 of his own theory. The same may be said of the 

 structures and movements of climbing plants, and, in 

 short, of all the other departments of natural history 

 where the theory of natural selection has led to the 

 study of the phenomena of adaptation. For in all these 

 cases the theory of natural selection, which first led to 

 their discovery, still remains the only scientific theory 

 by which they can be explained. But among all the 

 possible fields from which evidences of this kind may 

 be drawn, I think the best is that which may be 

 generically termed defensive colouring. To this field, 

 therefore, I will restrict myself. But, even so, the 

 cases to be mentioned are but mere samples taken 

 from different divisions of this field ; and therefore it 

 must be understood at the outset that they could 

 easily be multiplied a hundred-iold. 



