320 THE PRINCIPLES OF SEXUAL SELECTION. Part II. 



or young, would produce them of greater size or vigour ; 

 and the adults reared from such eggs or young would 

 manifestly have the best chance of surviving:, and 

 would inherit a tendency towards lessened fertility. 

 The parents, moreover, which had to nourish or provide 

 for fewer offspring would themselves be exposed to a 

 less severe strain in the struggle for existence, and 

 would have a better chance of surviving. By these 

 steps, and by no others as far as I can see, natural 

 selection under the above conditions of severe com- 

 petition for food, would lead to the formation of a new 

 race less fertile, but better adapted for survival, than 

 the parent-race. 



