VALVE OF niUDS TO MAN. 



41 



refuse is voided. This is disfestioii. The food is often manip- 

 ulated, crushed, or divdded by the beak. It then receives 

 saliva from the mouth, and i)ass('s through the pharvnx into 

 either the gullet (a nuiscular and membranous tube) or crop 

 (a pouch) , as the case may be, organs capable 

 of great distention, and connectino; with the 

 first division of the stomach. Here, then, 

 is the first receptacle of the food. Birds 

 of prey, Herons and some other large ])irds 

 sometimes till the gullet to the ver}' mouth, 

 while awaiting the digestion of the food in 

 a stomach already full. The Pelicans ha\e 

 also another great receptacle or pouch, ex- 

 ternal and beneath the beak, where a store 

 of food can be carried. ]\hiny of the smaller 

 liirds also are able, after filling the stomach, 

 to stow away a still larger supply of food 

 in the gullet. The stomach is large, and 

 usually ca})able, by distention, of contain- 

 ing a considerable quantity of food. The 

 food passes from the gullet or the crop to pj 

 the proventriculus or a'ljiudular ])ortion of '="> '^■•'""' "*^ ^'"°' 



. "" bird, reduced; after 



the stomach. This is where the process Audubon. rt,6,gui. 

 of digestion ])egins, ]Mixed with salivarv. 



ig. 17. — Aliinen- 



]et or oesophagus ; c, 

 proventriculus; d, 



ingluvial, and proventricular secretions, the gizzard; e,/, h, in- 



tcstiDG ' i clOticn.. 



food next passes to the gizzard or muscular 



division of the stomach, Avhere the food ijrist is OTound fine. 



Among seed-eating birds the heavy, powerful muscles of 

 this portion of the stomach are, with the rough, calloused 

 stomach lining, assisted in their work l)y sand and gravel 

 which are swallowed. This mineral matter takes the place 

 of teeth in grinding the food. 



In vegetable-feeding birds the intestine is verv lonof and 

 much coiled, while the digestive tract is generally shorter 

 and simpler in the flesh-eating and fish-eating species. All 

 the processes of digestion are remarkably ra})id. The sali- 

 vary glands, the liver and the pancreas all (juickly pour their 

 copious secretions into the alimentary canal : the food is 

 chylified after impregnation with the biliary and })anci'eatic 



