APPLICATION OF PRINCIPLES OF BREEDING 495 



repeatedly been found by 

 breeders who had made 

 marked increase in egg 

 production by simple selec- 

 tion and good care, and 

 by close breeding for a 

 term of years, that when 

 they went outside of their 

 stock for new blood, the 

 introduction of males of 

 different breeding was im- 

 mediately followed by a 

 sharp decline in egg pro- 

 duction. This fact has 

 been one of the strong 

 arguments in favor of the 

 theory that the number of 

 elementary eggs was rela- 

 tively small and was pro- 

 gressively increased by 

 individual variation and 

 selection. Such results are 

 often attributed to the use 

 of males not of heavy- 

 laying strains. Within heavy-laying stocks the lack of uniformity in results 

 of breeding shows that the sons of 

 heavy-laying hens reproduce that 

 quality in the same manner as the 

 daughters. Some males do unques- 

 tionably have a strong influence on 

 the laying capacity of their daughters, 

 but it seems to be due to transmission 

 of the characters that give capacity to 

 develop eggs. 



Mating for table poultry. In the 

 development of poultry for food pur- 

 poses, more than in any other line of 

 poultry breeding, the conditions of 

 production tend constantly toward an 

 undesirable modification of form and 



1 These birds won prizes for best- 

 shaped Light Brahmas at the Boston 

 Show when this variety was one of the 

 big classes there. They are birds of a 

 good utility type. 



Fig. 484. Light Brahma cock 1 



Fig. 485. Light Brahma heni 



