146 Farm Poultry 



a superior animal in the descendants of this valu- 

 able individual. To make use of an illustration, 

 it may be supposed that A and B represent two 

 animals of the same breed and that A is of su- 

 perior merit. If these animals are mated, the 

 blood of the progeny will be represented by one- 

 half A and one-half B. If A be bred to one of 

 the progeny, the blood of the offspring of the last 

 union will be represented by three-fourths A and 

 one-fourth B. This practice may be repeated in 

 succeeding generations and would be accepted 

 by all as in -and -in -breeding. As the percentage 

 of blood is increased the chances that the im- 

 provement will be perpetuated are also increased. 



While in -and -in -breeding serves a most useful 

 purpose, under certain conditions, it should not 

 be forgotten that it may also cause deterioration 

 in various ways. A commonly accepted belief is, 

 that the practice of in- and -in -breeding may re- 

 sult in a reduced constitution, may weaken the 

 mental vigor, reduce the size of the individuals 

 and make them less prolific. Many instances 

 might be cited to show that any one or all of 

 these evils may accrue from in-and-in-breeding, 

 and it is also true that any one or all of these 

 evils will not be produced to a certainty by this 

 practice. 



It is recognized that both good and evil re- 

 sults may follow the practice of in-breeding, 



