232 



THE ORIGIN OF SPECIES 



or tbese same species may occasionally revert to some 

 of the characters of their ancient progenitors. Although 

 new and important modifications may not arise from re- 

 version 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. 



