74 EESEMBLE VAEIETIES. [Chap. II. 



other species. Species very closely allied to other 

 species apparently have restricted ranges. In all these 

 respects the species of large genera present a strong 

 analogy with varieties. And we can clearly understand 

 these analogies, if species once existed as varieties, and 

 thus originated ; whereas, these analogies are utterly 

 inexplicable if species are independent creations. 



"We have, also, seen that it is the most nourishing or 

 dominant species of the larger genera within each class 

 which on an average yield the greatest number of 

 varieties ; and varieties, as we shall hereafter see, tend 

 to become converted into new and distinct species. 

 Thus the larger genera tend to become larger ; and 

 throughout nature the forms of life which are now 

 dominant tend to become still more dominant by 

 leaving many modified and dominant descendants. 

 But by steps hereafter to be explained, the larger 

 genera also tend to break up into smaller genera. And 

 thus, the forms of life throughout the universe become 

 divided into groups subordinate to groups. 



