234 THE BREEDING OF ANIMALS 



the best rats from the standpoint of size, vigor, fecundity 

 and general quality were carefully selected. 



The actual results of this investigation after twenty- 

 two generations of in-breeding are that the male in-bred 

 rats are about fifteen per cent heavier and the female 

 in-bred rats about three per cent heavier than stock rats. 

 The size of litters among the stock rats has been seven, 

 while among the in-bred rats the litters have increased 

 and now average seven and four-tenths each. The thrift 

 and vigor of in-bred rats in these experiments was appar- 

 ently not injured by in-breeding. " The results so far 

 obtained with these rats," says Dr. King, " indicate 

 that close in-breeding does not necessarily lead to a loss 

 of size or of constitutional vigor or of fertility, if the 

 animals so mated come from sound stock in the beginning 

 and sufficient care is taken to breed only from the best 

 individuals." 



218. In-breeding Berkshires by Mr. Gentry. The 

 remarkable success which may follow the practice of 

 in-breeding when intelligently conducted by a skillful 

 breeder is shown in the experience of N. H. Gentry of 

 Sedalia, Missouri. Probably no American breeder has 

 been so successful in developing all those desirable qualities 

 in Berkshire swine which give this breed its great economic 

 value. At the Chicago World's Fair in 1893 Gentry's 

 Berkshires won twenty-three of the twenty-eight first 

 prizes offered, and many of the other winners were de- 

 scended from stock bred by him. At the St. Louis World's 

 Fair in 1903, all the Berkshires which came within the 

 five cash prizes offered, with three exceptions, were de- 

 scended from animals bred by Gentry. The entire 

 Gentry herd was strongly in-bred, carrying a very high 

 proportion of the blood of Longfellow. Describing his 



