68 DISEASES OF POUETRY. 



compared witli tbe Ttimen or paunch of cattle and 

 sheep. The food which is eaten and other substances 

 which are swallowed drop first into the crop where 

 they are macerated and softened in the liquids secreted 

 by this organ. The contents of this crop are under 

 normal conditions soon forced by the contractions of 

 its muscular walls into the lower part of the oesophagus^ 

 which carries thetn on into the second or true stomach,, 

 the proventriculus or succentric ventricle, where they 

 are mixed with the gastric juice and rapidly passed 

 onward to the gizzard. 



In the grain -eating birds, the gizzard is a remark- 

 ably firm, thick muscular organ which takes the food 

 that has been softened and mixed with digestive 

 liquids, and grinds it by pressing and rubbing it 

 against pebbles that the bird has swallowed. Even 

 the hardest grains and seeds are reduced in this manner 

 to a paste upon which the digestive liquids can readily 

 exert their dissolving action. This paste is pressed 

 onward into the small intestine where it is mixed with 

 the secretions of the liver, pancreas, and intestines, 

 which complete the solution of the nutritive principles 

 and render them proper for assimilation. 



Under natural conditions birds are compelled to 

 hunt their food, they find and eat but a small quantity 

 at a time, and the crop, while designed by nature as a 

 reservoir for storing food, is not overloaded by receiv- 

 ing a day's ration in a few minutes. In the domesti- 

 cated state, these conditions are more or less changed, 

 the birds are fed only once or twice a day and from 

 lack of gravel, indigestion, and insufficient exercise, 

 acquire abnormal appetites and eat feathers, straw, dry 

 leaves and other indigestible substances. Diseases 



