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CHAPTER V. 



THE ACCUMULATION OF BENEFICIAL 

 DIFFERENCES. 



WE fully recognise differences among in- 

 dividuals of the same race, and also that 

 such differences are specially noticeable 

 amongst domestic animals under selective 

 breeding. Some individuals, compared with 

 their fellows, develop what we consider bene- 

 ficial differences ; and the assumption by 

 Darwin that these beneficial differences ac- 

 cumulate indefinitely, become specific varia- 

 tions, and give rise to new species, is a main 

 prop of his theory. 



The hypothesis seems at first sight plaus- 

 ible enough, and, had evolution been brought 

 about by secondary causes, it is possible that 

 the accumulation of beneficial differences 

 might have been an effectual means of de- 

 veloping new species. 



But, unfortunately for Darwin's hypothesis, 

 the beneficial differences that arise under 



