RECEPTACLES FOR RETAINING FOOD. 



17.9 



Analogous in design to these pouches are 

 the dilatations of the oesophagus of birds, deno- 

 minated crops. In most birds which feed on 

 grain, the crop is a capacious globular sac, 

 placed in front of the throat, and resting on the 

 furcular bone. The crop of the Parrot is repre- 

 sented at c. Fig. 299 ; where, also, s indicates 



the cardiac portion of the 

 stomach, and g the giz- 

 zard, of that bird. The 

 inner coat of the crop is 

 furnished with numerous 

 glands, supplying consi- 

 derable quantities of fluid 

 for macerating and sof- 

 tening the dry and hard 

 texture of the grain, 

 which, for that purpose, 

 remains there for a considerable time. Many 

 birds feed their young from the contents of 

 the crop ; and, at those seasons, its glands are 

 much enlarged, and very active in preparing 

 their peculiar secretions : this is remarkably 

 the case in the Pigeon, which, instead of a 

 single sac, is provided with two, (seen at c, c. 

 Fig. 300), one on each side of the oesophagus (o). 

 The pouting pigeon has the faculty of filling 

 these cavities with air ; producing that dis- 

 tended appearance of the throat from which it 

 derives its name. Birds of prey have, in general. 



