26 ECOLOGY AND ITS IMPORTANCE [CHAP. 



interesting and remarkable letter to Wagner; 

 which is in fact a refutation of his own theory 

 of natural selection. This complete change of 

 front in Darwin I would most strongly empha- 

 sise ; because, I repeat, it is precisely the view 

 now taken by ecologists. Indeed " now " is in- 

 correct. It was accepted by botanists twenty 

 years ago ; but Darwinians of to-day completely 

 ignore it. 



Having thus established a firm conviction by 

 induction, ecologists next proceed to look for 

 experimental verification. Of this there is an 

 abundance, both artificial and natural ; for 

 Nature is constantly making experiments ; as 

 e.g., with amphibious plants, which grow quite 

 differently when in water or air. Before giving 

 illustrations of inductive and experimental 

 evidence, it will be advisable to quote the 

 views of a few eminent ecologists as to the 

 conclusions arrived at. I have already alluded 

 to Mr J. Arthur Thomson's remarks in 

 1888 ; but he seems now to limit hereditary 

 variations to spontaneous origins in the germ- 

 cells. My own book on " The Origin of Floral 

 Structures by Insect and other Agencies " J also 

 appeared in 1888. 



Professor Warming of Copenhagen, in alluding 

 to adaptations in xerophytic, i.e., "drought" 

 plants, observes : 



1 International Scientific Series, vol. Ixiv. 



