160 Darwin, and after Darwin. 



those days the fact of evolution itself, as distin- 

 guished from its method, had to be proved ; and 

 that the whole proof had to stand or fall with 

 the evidence which could be adduced touching the 

 mutability of species. Therefore, without question, 

 Darwin was right in placing this issue as to the 

 stability or instability of species in the forefront of 

 his generalizations, and hence in constituting it the 

 title of his epoch-making book. But nowadays, when 

 the fact of evolution has been sufficiently established, 

 one would suppose it self-evident that the theory 

 of natural selection should be recognized as cover- 

 ing a very much larger field than that of explaining 

 the origin of species that it should be recognized 

 as embracing the whole area of organic nature in 

 respect of adaptations, whether these happen to be 

 distinctive of species only, or of genera, families, 

 orders, classes, and sub-kingdoms. For it follows 

 from the general fact of evolution that species are 

 merely arbitrary divisions, which present no deeper 

 significance from a philosophical point of view than 

 is presented by well-marked varieties, out of which 

 they are in all cases believed to have arisen, and 

 from which it is often a matter of mere individual 

 taste whether they shall be separated by receiving 

 the baptism of a specific name. Yet, although 

 naturalists are now unanimously agreed that what 

 they classify as species are nothing more than 

 pronounced and in some greater or less degree 

 permanent varieties, so forcible is the influence of 

 traditional modes of thought, that many zoologists 

 and botanists still continue to regard the origin of 

 species as a matter of more importance than the origin 



