ANATOMY OF BIRDS 13 
The pancreatic juice acts on the starchy material while the secre- 
tion of the proventriculus acts on the proteins in the food. Suc- 
ceeding the duodenum are, according to some writers, the other two 
divisions of the small intestine, the jejunum and ileum. These form 
several convolutions and are continued by the rectum to the cloaca. 
At the point of juncture of the small intestine and rectum, in 
certain species of birds, are found two elongated diverticula lead- 
ing from the intestine. These are the ceca or blind pouches. In 
grown fowls and turkeys they are from 4 to 7 inches in length and 
may be distended to a diameter of 14 to 34 of an inch. Especial 
importance is attached to them because of the fact that they are the 
seat of marked lesions in coccidiosis of chickens, and of turkeys, and 
in infectious entero-hepatitis of turkeys. In some species of wild 
birds, the ceca may reach a length of 10 inches while in others they 
are absent or merely rudimentary. Their function is apparently the 
retention of food material which has not been absorbed in passage 
through the small intestine. 
The cloaca serves as a common cavity for the entrance of the 
intestine, ureters, oviduct in the female, and vasa deferentize in 
the male. It is divided into three parts. The rectum enters the 
first part, the ureters and genital canals open on the lateral faces of 
the second and the bursa of Fabricus, a blind sac or glandular cavity, 
opens on the dorsal wall of the third or outer division. The bursa of 
Fabricus may disappear in adults. The one oviduct in the female 
opens on the left side of the second division. The material from the 
intestine and ureters is held in the cloaca to form the character- 
istic droppings and is then passed out through the anus or vent. 
Mucosa of the alimentary canal. The alimentary canal is 
lined internally by a mucous membrane which is thick, and com- 
posed of many layers of cells in the mouth, pharynx, esophagus 
and crop. The mucosa is thin, and composed of one layer of 
columnar epithelial cells in the proventriculus, gizzard and intestine. 
In the gizzard the membrane is covered by a horny surface layer. 
In the submucous tissue of the mouth and pharynx are found 
several pairs of glands. These, however, are not considered as 
true salivary glands but produce a mucous secretion. The esoph- 
agus exhibits numerous alveolar secretory glands in the submucous 
tissue. The glandular stomach is conspicuous for the layer of 
tubular secretory glands which are set perpendicularly to the mu- 
cous m~™brane and which pour their secretion of gastric juice into 
the interior of the stomach. Over the mucous membrane of the 
