206 LAWS OP VARIATION. [Chap. V. 



in giving a fixed character to the organ, in however 

 extraordinary a manner it may have been developed. 

 Species inheriting nearly the same constitution from 

 a common parent, and exposed to similar influences, 

 naturally tend to present analogous variations, or these 

 same species may occasionally revert to some of the 

 characters of their ancient progenitors. Although 

 new and important modifications may not arise from 

 reversion and analogous variation, such modifications 

 will add to the beautiful and harmonious diversity of 

 nature. 



Whatever the cause may be of each slight difference 

 between the offspring and their parents — and a cause 

 for each must exist — we have reason to believe that it 

 is the steady accumulation of beneficial differences which 

 has given rise to all the more important modifications 

 of structure in relation to the habits of each species. 



