8o Darwin, and after Darwin. 



such cases, at any rate we might well doubt the 

 importance or extent of selective fertility as a factor 

 in the origination of species. But the value of 

 Nageli's writings on the present subject consists in 

 showing that synoical species constitute so over- 

 whelming a majority of the vegetable kingdom, that 

 here, at all events, it appears impossible to rate too 

 highly the importance of the principle I have called 

 physiological selection. 



