290 THE ORIGIN OF SPECIES 



supposed to have been produced by special acts of crea- 

 tion and varieties which are acknowledged to have been 

 produced by secondary laws. On this same view we can 

 understand how it is that in a region where many species 

 of a genus have been produced, and where they now 

 flourish, these same species should present many vari- 

 eties; for where the manufactory of species has been 

 active, we might expect, as a general rule, to find it 

 still in action; and this is the case if varieties be 

 incipient species. Moreover, the species of the larger 

 genera, which afford the greater number of varieties or 

 incipient species, retain to a certain degree the character 

 of varieties; for they differ from each other by a less 

 amount of difference than do the species of smaller 

 genera. The closely allied species also of the larger gen- 

 era apparently have restricted ranges, and in their 

 affinities they are clustered in little groups round other 

 species — in both respects resembling varieties. These are 

 strange relations on the view that each species was inde- 

 pendently created, but are intelligible if each existed first 

 as a variety. 



As each species tends by its geometrical rate of repro- 

 duction to increase inordinately in number; and as the 

 modified descendants of each species will be enabled to 

 increase by as much as they become more diversified in 

 habits and structure, so as to be able to seize on many 

 and widely different places in the economy of nature; 

 there will be a constant tendency in natural selection to 

 preserve the most divergent offspring of any one species. 

 Hence, during a long-continued course of modification, 

 the slight differences characteristic of varieties of the 

 same species tend to be augmented into the greater 



