THE STRUGGLE FOR EXISTENCE. 87 



Have they become fitter to continue the 

 struggle than the rabbits that were fittest 

 when the struggle began ? Or, should the 

 struggle develop into a conflict between in- 

 dividuals, will the half- starved rabbit be as 

 fit to fight as when he was well fed ? Were 

 that the case, it would follow that scarcity of 

 food is more favourable to life and vigour than 

 abundance ; but that is absurd, for we know 

 that insufficiency of food impairs constitution 

 and vitality and stunts growth. The differ- 

 ences between wild and domestic animals, 

 assuming both to be of the same species, 

 or between the same plant growing wild 

 and under cultivation, are obviously not the 

 effects of the struggle for existence, but of 

 protection from its effects. 



In the case of animals that live by preying 

 on other species, it may be argued that, 

 when food ceases to be abundant, increased 

 use would develop in exceptional individuals 

 increased speed of foot or wing, or keenness 

 of vision, as the case may be ; but the habits 

 of beasts or birds of prey do not support this 

 conclusion. The beast or bird of prey gorges 

 itself when it has the opportunity, and does 

 not again hunt its prey until impelled by 

 hunger. Habitual necessities thus provide 

 sufficient exercise for the full development of 



