32 MAMMALS 



mals, adults and young, were allowed to run together indis- 

 criminately, can lead to no good result. It is comparable 

 to the flock of poultry or pigeons roaming unrestrained 

 and breeding in a haphazard way. 



Line breeding, as outlined later in this work, is the only 

 means by which success in this field may be obtained, and 

 careful observation of its principles will result in rapid 

 gains by the breeder. If some particular breed or color has 

 been selected, with the idea of producing standard speci- 

 mens, the very best stock should be secured in the first 

 place, and rigid selection used in future matings. Only 

 strong, vigorous individuals should be chosen for the breed- 

 ing-pen. 



In mating, two or three sows may be run with a boar at 

 once, and after sufficient time has elapsed he should be re- 

 moved. While some boars are quiet enough to leave with 

 thefyoung, many are not to be trusted. The period of gesta- 

 tion is about sixty-three days, but may vary considerably 

 with individuals. The advantage of this procedure is that 

 all of the young will appear at about the same time, and 

 as cavy mothers are not particular as to their young, all 

 will be sure of sufficient attention. If any are particularly 

 quarrelsome, they should be removed to separate hutches 

 before the birth of the young. 



The common belief that cavies are extremely prolific is 

 entirely without foundation. The fact is quite the oppo- 

 site. Litters average in number from one to four, two 

 being perhaps the most usual. Five or six sometimes occur, 

 but this is very uncommon. Since at least two months must 

 separate the litters, it will be seen that the caviary will not 

 be flooded with youngsters for some time. This error in 

 regard to prolificacy is curiously persistent, and is con- 

 stantly appearing in the literature of the subject. 



The young at birth are the most precocious of mammals, 



