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 the 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 
