DOMESTIC ANIMALS 3 



bred them, and to the slight differences in the individuals 

 selected in consequence for breeding purposes generation 

 after generation. 



The contrast between cats and dogs is also instructive. 

 The cat's nature leads it to wander out at night, and its 

 habits make control over its breeding very difficult ; and 

 such breeding is, therefore, but little attended to. In 

 consequence, as compared with dogs, fewer different 

 breeds of cats have been produced, with less marked 

 differences between them. Then, again, cats are chiefly 

 useful for killing mice at home. This they can do in their 

 master 's absence, because he does not want to eat the mice 

 himself. Hence obedience to a call has not been bred into 

 them. Lastly, what brings the cat home in the morning 

 after its wanderings in the dark is the desire for shelter 

 and warmth. It was those cats which felt this desire for 

 comfort most strongly who least often deserted the camp 

 to become wild animals. The result of this unpremeditated 

 selection going on for ages has been the production of the 

 comfort-loving, unsympathetic animal we all know so well. 



The effects of selection in bygone times are also seen 

 clearly .in our cattle of to-day. In the days of our ances- 

 tors of long ago, the poor milker was often killed for food, 

 while the cow producing more milk was retained to supply 

 the family. It was only the better milkers, therefore, who 

 had calves; and these calves passed on to their descen- 

 dants their powers of producing milk in bigger quantities. 

 No doubt this kind of unintentional selection in some 

 degree improved the breed in regard to milk-giving. In 

 our day, however, deliberate selection is being carried on 

 with the greatest forethought and care. A bull is valued 

 for breeding purposes in accordance with the milking 

 qualities, not only of its female ancestors, but also of the 

 cows which he has already produced as his offspring. 

 African savages have tame cows which are known to have 

 produced not more than two or three pints of milk a day ; 

 and this may be more than that produced by wild cattle. 

 A good milker may now produce forty pints a day, this 



