40 MOSTLY MAMMALS 



ment ; while the goat can obtain a living on ground where 

 a sheep would starve. Moreover, the ass and the mule 

 replace the horse in arid and mountainous countries, where 

 they thrive on a much less luxuriant diet than is necessary 

 to the well-being of the latter animal. 



Then there are climates in which many of the domesti- 

 cated animals of Europe will not flourish, dying either 

 from the general effects of the climate itself, or succumbing 

 to the attacks of insect-pests, as in the familiar instance 

 of the African tsetse-fly. 



As regards the supplementing of the existing domesti- 

 cated animals of Europe — whether they be used for labour 

 or for food — by newly domesticated wild species, I venture 

 to think that, in the main, there is very little chance of 

 success. In the first place, the species we now possess in 

 this condition are amply sufficient to serve all needs, and 

 are capable of indefinite multiplication. And in the second 

 place, it has to be borne in mind that it would probably 

 take scores of generations to make a wild animal equal in 

 point of utility to the old-established domestic breeds — 

 that is to say, it would take an immensely long period 

 of time in order to make any wild animal as immune to 

 the effects of in-and-in breeding as is the case with our 

 domesticated species ; while it is quite likely that the time 

 would be still longer before the former would approach 

 many of the latter in flesh-forming power or in the capacity 

 for early maturity. And in this connection it is most 

 important to bear in mind that the great majority of our 

 domesticated animals are very different in physical characters 

 from their wild ancestors ; and that, in most instances, it 

 is these highly modified breeds that are of the greatest 

 economic importance to mankind. To produce an animal 

 like the sheep, for instance, which differs from all its wild 



