Fig. 66.
Fig. 67.
The tongue, like the bill, however, is only an accessory to the digestive apparatus; for while the beak serves the purpose of prehension and trituration, the tongue assists in deglutition or swallowing. Digestion is so active in some birds, that they get fat in an excessively short space of time. The Ortolan Bunting, Emberiza hortulana, and some others, are fattened for the table in five or six days. In the swelling under the throat, called the crop, a ([Fig. 68]), or first stomach, which is largely developed in some of the granivorous or grain-eating birds, the food remains for a time, where it undergoes certain modifications which facilitate digestion; thence it passes into the succenteric ventricle, or second stomach, b ([Fig. 68]),—there it imbibes the necessary amount of gastric juice; being finally transformed into chyme in the gizzard, c ([Fig. 68]), or third stomach, which is possessed of great muscular power, being capable of acting upon the most solid bodies, triturating even the flints and gravel which the gallinaceous birds swallow to aid their digestion.
Fig. 68.
It is a curious fact that a grain of seed, introduced into the stomach, may be digested without alteration, and ejected where it will germinate, if it meets with no obstacle to its vegetation. In this manner trees are frequently found in regions where their species appear to have been previously unknown.
Chyle, which is a milky fluid formed from the junction of chyme and bile, is received by the small intestine, where the bile also flows from the liver and the saliva from the pancreas.
The urinary apparatus consists of the kidneys, two in number, thick and irregular, and distinct one from the other, abutting on the intestine, which terminates in a species of pouch, or cloaca, through which evacuation, alternately of urine, excrement, and eggs, takes place.