176 



REPTILES AND BIRDS. 



The tongue, like the bill, however, is only an accessory to the 

 digestive apparatus ; for while the beak serves the purpose of pre- 

 hension 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, and some others, are 

 fattened for the table in five or six days. In 

 the swelling under the throat called the crop 

 (a, Fig. 67), 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 faci- 

 litate digestion ; thence it passes into the suc- 

 centeric ventricle, or second stomach, (I?, Fig. 

 67), there it imbibes the necessary amount of 

 gastric juice ; being finally transformed into 

 chyme in the gizzard (c, Fig. 67), 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. 



It is a curious fact that a grain of seed, 

 introduced into the stomach, may be digested 

 without alteration, and when ejected 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. Such is the general internal anatomy of Birds (Fig. 68). 



The senses of touch, of smell, of taste, and hearing are only slightly 



developed in Birds. Some have spoken of great delicacy of scent 



in Birds of Prey, which are observed to assemble in great numbers 



on fields of battle and other places where carcases are exposed. 



But the opinions of naturalists such as Audubon and Levaillant 



Fig. 67. 

 Crop and digestive organs. 



