BIRDS IN GENERAL. 13 



kind. Their gullet dilates just above the breast- 

 bone, and forms itself into a pouch or bag, called 

 the crop. This is replete with salivary glands, 

 which serve to moisten and soften the grain and 

 other food which it contains. These glands are 

 very numerous, with longitudinal openings, which 

 emit a whitish and a viscous substance. After 

 the dry food of the bird has been macerated for 

 a -convenient time, it then passes into the belly, 

 where, instead of a soft moist stomach, as in the 

 rapacious kind, it is ground between two pair of 

 muscles, commonly called the gizzard, covered 

 on the inside with a stony ridgy coat, and almost 

 cartilaginous. These coats rubbing against each 

 other, are capable of bruising and attenuating 

 the hardest substances, their action being often 

 compared to that of the grinding teeth in man 

 and other animals. Thus the organs of digestion 

 are in a manner reversed in birds. Beasts grind 

 their food with their teeth, and then it passes 

 into the stomach, where it is softened and digest- 

 ed. On the contrary, birds of this sort first ma- 

 cerate and soften it in the crop, and then it is 

 ground and comminuted in the stomach or gizzard. 

 Birds are also careful to pick up sand, gravel, 

 and other hard substances, not to grind their food, 

 as has been supposed, but to prevent the too vio- 

 lent action of the coats of the stomach against 

 each other. 



Most birds have two appendices, or blind guts, 

 which in quadrupeds are always found single. 

 Among such birds as are thus supplied, all carnivo- 

 rous fowl, and all birds of the sparrow kind, have 



