Aves. 



215 



as a storing sac during the hasty gathering of food. In- 

 side of the body cavity is the stomach, which consists of 

 two very distinct parts ; the first part is the glandular 

 stomach, or proventriculus, and the second is known as the 

 gizzard. The gizzard is very strong, having thick muscular 

 walls. In it the seeds, only partially softened, are to be 

 ground. To aid this process small pebbles are swallowed. 

 It is clear, therefore, that its inner wall needs to be tough ; 



FIG. 129. INTERNAL ANATOMY OF A PIGEON. 



it will not do to have the soft glands here, hence they are 

 placed out of the way, a little higher up the digestive tube 

 where the secretion can trickle down upon the food in the 

 grinding stomach. The intestine arises from the gizzard ; 

 first there is a long loop, the duodenum, in which lies the 

 pancreas. Its secretion is poured into the duodenum. 

 The liver is adjacent and the bile duct also empties into the 

 duodenum. The transition from the small intestine to the 

 large intestine is marked by two small, blind side branches, 



