72 ' SPECIES OF LARGER GENERA. [Chap. II. 



species greater than the average are now manufactur- 

 ing, many of the species already manufactured still to 

 a certain extent resemble varieties, for they differ 

 from each other by less than the usual amount of differ- 

 ence. 



Moreover, the species of the larger genera are re- 

 lated to each other, in the same manner as the varieties 

 of any one species are related to each other. No nat- 

 uralist pretends that all the species of a genus are equal- 

 ly distinct from each other; they may generally be 

 divided into sub-genera, or sections, or lesser groups. 

 As Fries has well remarked, little groups of species 

 are generally clustered like satellites around other 

 species. And what are varieties but groups of forms, 

 unequally related to each other, and clustered round 

 certain forms — that is, round their parent-species. 

 Undoubtedly there is one most important point of dif- 

 ference between varieties and species; namely, that the 

 amount of difference between varieties, when compared 

 with each other or with their parent-species, is much 

 less than that between the species of the same genus. 

 But when we come to discuss the principle, as I call it, 

 of Divergence of Character, we shall see how this may be 

 explained, and how the lesser differences between varie- 

 ties tend to increase into the greater differences between 

 species. 



There is one other point which is worth notice. 

 Varieties generally have much restricted ranges: this 

 statement is indeed scarcely more than a truism, for, if 

 a variety were found to have a wider range than that 

 of its supposed parent-species, their denominations 

 would be reversed. But there is reason to believe that 

 the species which are very closely allied to other species. 



