DISEASES OF POULTRY. 147 



membrane of the uterus. The appearance of pores on 

 the surface of the shell is due to the impressions of 

 the villi of the formative membrane ; but the permea - 

 bility of the shell by the atmosphere depends upon a 

 more minutely porous texture. The shell consists in great 

 part of carbonate of lime , with a little carbonate of mag - 

 nesia and phosphate of lime and magnesia (Owen). 



The oviduct is a whitish tube somewhat larger than 

 the large intestine and shows many branching blood 

 vessels upon its surface. It begins near the ovary by 

 an enlarged portion called the infundibulum, and 

 after being bent upon itself several times and forming 

 three principal convolutions, it reaches the cloaca in 

 which it opens. In the non -breeding season, when 

 the parts are in repose, the ovary and oviduct are re- 

 duced in size and almost disappear. 



ATROPHY OF THE OVARY. 



The ovaries, like the testicles of the male, are great- 

 ly reduced in size and atrophied during the non -breed- 

 ing season. This, however, is a physiological atrophy 

 and not a disease. In the same manner, the ovaries 

 become atrophied in old hens which have ceased lay- 

 ing. This is sometimes, but not always, accompan- 

 ied by remarkable changes in other parts of the body. 

 The spurs develop, the feathers become longer and 

 more brilliant, resembling those of the cock, or usual- 

 ly approaching more closely to the plumage of the 

 capon. Such birds, also, assume to a certain extent 

 the voice and habits of ]the male. 



The complete atrophy of the ovaries is sometimes 

 congenital, or, more strictly speaking, these organs 

 fail to develop. In other cases, rudimentary organs 

 of both sexes are found in the same individual. Birds 

 in which this condition exists, also, have a resem- 



