DARWIN, AND AFTER DARWIN. 



CHAPTER I. 

 Isolation. 



This treatise will now draw to a close by considering 

 what, in my opinion, is one of the most important 

 principles that are concerned in the process of organic 

 evolution — namely, Isolation. I say in tny opinion 

 such is the case, because, although the importance of 

 isolation is more or less recognized by every naturalist, 

 I know of only one other who has perceived all that 

 the principle involves. This naturalist is the Rev. J. 

 Gulick, and to his essays on the subject I attribute 

 a higher value than fo any other work in the field of 

 Darwinian thought since the date of Darwin's death ^. 

 For it is now my matured conviction that a new point 

 of departure has here been taken in the philosophy of 

 Darwinism, and one which opens up new territories 

 for scientific exploration of an endlessly wide and 

 varied character. Indeed I believe, with Mr. Gulick, 



' It will be remembered that I regard Weismann's theory of heredity, 

 with all its deductive consequences, as still subjudice. 

 III. B 



