TENDENCY OF SPECIES TO FORM VARIETIES. 19 



ercise sight, hearing, and smell in seeking it, and in avoiding dangers, 

 in procuring shelter from the inclemency of the seasons, and in provid- 

 ing for the subsistence and safety of its offspring. There is no muscle 

 of its body that is not called into daily and hourly activity; there is 

 no sense or faculty that is not strengthened by continual exercise. The 

 domestic 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 assistance. Half of its senses and 

 faculties are quite useless; and the other half are but occasionally 

 called into feeble exercise, wliile even its muscular system is only irreg- 

 ularly called 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 existence, any increase becomes immediately available, is strength- 

 ened 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 inferior 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 domesticity. Our quickly 

 fattening pigs, short-legged sheep, pouter pigeons, and poodle dogs 

 could never have come into existence in a state of nature, because the 

 very first step towards such inferior forms would have led to the rapid 

 extinction of the race ; still less could they now exist in competition with 

 their wild allies. The great speed but slight endurance of the race 

 horse, the unwieldy strength of the ploughman's team, would both be 

 useless in a state of nature. If turned wild on the pampus, such animals 

 would probably soon become extinct, or under favourable circumstances 

 might each lose those extreme qualities which would never be called 

 into action, and in a few generations would revert to a common type, 

 which must be that in which the various powers and faculties are so 

 proportioned to each other as to be best adapted to procure food and 

 secure safety, — that in which by the full exercise of every part of his 

 organization the animal can alone continue to live. Domestic varieties, 

 when turned wild, must return to something near the type of the orig- 

 inal wild stock, or become altogether extinct. 



We see, then, that no inferences as to varieties in a state of nature 

 can be deduced from the observation of those occurring among domestic 



