INDEFINITELY FROM THE ORIGINAL TYPE. 39 



not strengthened by continual exercise. The domes- 

 tic animal, on the other hand, has food provided 

 for it, is sheltered, and often confined, to guard it 

 against the vicissitudes of thq seasons, is carefully 

 secured from the attacks of its natural enemies, and 

 seldom even rears its young without human assist- 

 ance. Half of its senses and faculties become quite 

 useless, and the other half are but occasionally 

 called into feeble exercise, while even its muscular 

 system is only irregularly brought into action. 



Now when a variety of such an animal occurs, 

 having increased power or capacity in any organ or 

 sense, such increase is totally useless, is never called 

 into action, and may even exist without the animal 

 ever becoming aware of it. In the wild animal, on 

 the contrary, all its faculties and powers being 

 brought into full action for the necessities of ex- 

 istence, any increase becomes immediately available, 

 is strengthened by exercise, and must even slightly 

 modify the food, the habits, and the whole economy 

 of the race. It creates as it were a new animal, 

 one of superior powers, and which will necessarily 

 increase in numbers and outlive those which are in- 

 ferior to it. 



Again, in the domesticated animal all variations 

 have an equal chance of continuance ; and those 

 which would decidedly render a wild animal unable 

 to compete with its fellows and continue its existence 

 are no disadvantage whatever in a state of domesti- 

 city. Our quickly fattening pigs, short-legged sheep 



