52 INTRODUCTION, 



doubt, by the seusation of the stomach ; but in domesticated 

 animals this faculty is sometimes deranged. Young Ducks 

 have been known to take so much gravel as to produce 

 death. 



On the contrary to those Birds that are carnivorous or 

 piscivorous, a membranaceous stomach is given, which 

 more resembles that of carnivorous quadrupeds; the di- 

 gestion of such Birds being more accelerated by the gastric 

 juice than by the action of the stomach itself. 



Those Birds belonging to the first class digest or retain 

 every substance taken in ; and those which eject or disgorge 

 innutricious matter unavoidably taken in, such as feathers, 

 fur, bones, &c. belong to the second class, conspicuous in the 

 Eagle and Owl tribes, and those also that feed on fish. 

 The innutricious matter, termed CastingSy which is ejected 

 by Eagles, Owls, &c. descends most probably no farther 

 than the crop in which the nutritive from the innutritive 

 portion of the food is separated. 



It ought also be mentioned, as a remarkable fact, that 

 the rapacious birds seldom or never drink. Eagles, Hawks, 

 and Owls, were kept by Colonel Montagu for years 

 without tasting water. 



Besides the stomach, most Birds have a membranous 

 sac, capable of considerable distension ; it is usually called 

 a Crop, (by the scientific Ingluvies,) into which the food 

 first descends after being swallowed. This bag is very con- 

 spicuous in the granivorous tribes immediately after 

 eating. Its chief use seems to be to soften the food before 

 it is admitted into the gizzard. In young fowls it becomes 

 sometimes preternaturally distended, while the Bird pines 

 for want of nourishment. This is produced by something in 

 the crop, such as straw, or other obstructing matter, whTcti 

 prevents the descent of the food into the gizzard. In suoli 



