96 



POULTRY PRODUCTION 



secreting portion again. This causes a new secretion of 

 albumen which surrounds the shell, and, normal action 

 restored, the egg again travels down the oviduct, is sur- 

 rounded by a second pair of membranes and another 

 shell. 



The so-called "liver spots" or "blood spots'' in eggs are 

 due to the rupture of bloodvessels in the follicle or walls 

 of the oviduct or by the sloughing off of tiny pieces of mem- 

 brane. The clot simply becomes surrounded along with the 

 yolk. The membrane is usually suspended in the albumen. 



Fig. 37 



Showing how bacillary white diarrhea perpetuates itself in the breeding stock. 



Inheritance of Disease. — While the statement that infectious 

 poultry diseases are heritable is technically incorrect, practi- 

 cally it has a substantial basis in fact. The most conspicuous 

 example is found in the life history of the organism causing 

 contagious white diarrhea. When a female chick is infected 

 with the disease and makes a recovery it becomes a bacillus 

 carrier. According to Rettger, Kirkpatrick, and Jones,' 

 the organisms may never be entirely eliminated from the 

 pullet's body, and as she develops, some of them migrate to 

 her ovary. They may also reacli the ovary from the ali- 



' Storr's Bulletin No. 77. 

 ' Ibid. 



