BREEDING AND MATING 



87 



Atavism is another law of breeding which teaches us that 

 the characteristics of individuals may disappear for a genera- 

 tion or two, and then reappear in a subsequent generation. 

 For example, we sometimes get black birds from a pure 

 Barred Plymouth Rock mating. This black plumage doubt- 

 less comes from the Black Java, which is one of the original 

 ancestors of the Plymouth Rock. Atavism may be termed 

 a going back or reversion to an ancestral tjrpe or color. We 

 might call it postponed heredity. 



Prepotency is another term used in breeding. It means 

 simply the ability of the parent to stamp characteristics on 

 its progeny. Some parents who lack this power are said to 

 be non-prepotent. 



The term correlation, as used in poultry breeding, means 

 the relation which may exist between a part of the body 

 and the ability of the birds 

 to produce eggs. For exam- 

 ple, scientists are wonder- 

 ing to-day whether there is 

 any correlation between the 

 form of the body and egg 

 production. Should this be 

 proven, it will be a simple 

 matter to pick out birds that 

 are good layers. 



Sports are oddities, or ab- 

 normal individuals, and these 

 may illustrate a type of varia- 

 tion, which is spontaneous in 

 its nature. A sport is an ani- 

 mal which is different from the 

 normal type, and exhibits characteristics utterly imlike those 

 of its kind; for example, a tailless, a wingless, or a four- 

 legged chicken (Fig. 56). In studying these rules, the stu- 

 dent should fix in his mind the fact that in breeding we select 



Fig. 56. — A tailless Leghorn commonly 

 called a sport. 



