SELECTION 179 



do not doubt," Darwin said, " that isolation 

 is of considerable importance in the forma- 

 tion of new species." It may be of some 

 importance in preventing intercrossing, but 

 it is much more likely that it works by bring- 

 ing about close inbreeding, which develops 

 prepotency or stability of type. 



In the human world, the manifold range 

 of individuality presented by regions favour- 

 able to family, village, and clan isolations, 

 such as Scotland or Norway, Greece or Pales- 

 tine, thus becomes intelligible. Again, in 

 that deterioration of the cities of the plain, 

 which is so frequent throughout history, so 

 evident to-day, we may increasingly fear an 

 organic factor underlying the obvious social 

 ones that of reversion through intercrossing; 

 as when the highly individualized races of 

 pigeon sink back to the comparative uni- 

 formity of the ancestral rock-dove. Yet from 

 this apparent regression, really a profound 

 and intimate panmixis, a thoroughgoing cross- 

 fertilization, who shall say what new variations 

 may arise, what new selections also even 

 what evolving guidance of these ? 



EUGENICS AS A RENEWAL OF EVOLUTION. 

 Thus we return to man as transformist, a 

 discussion already opened in Chapter II, 

 but this time appearing in a fresh perspec- 



