rilK ORAL CWITY 21 



intestine. Tlie stomach is n;uT()\v(>r at its caudal ciui and is 

 demarcated from the intestine by the distinct circuhir pylorus 

 or pyloric valve. Beyond the pylorus is the small intestine, 

 consisting of the duodenum, that part of the intestine lying 

 parallel to the stomach, and the ileum, which is the slender con- 

 voluted portion of the small intestine continuous at its distal 

 end with the large intestine. This passes without noticeable 

 change of size into the cloaca which is the most caudal division 

 of the alimentary canal. Locate the urinary bladder which is 

 a thin-walled, bilobcd sac opening through the ventral walls 

 of the cloaca. 



The gall bladder is a small spherical green sac lying between 

 the right and left lobes of the liver. The pancreas is a pinkish 

 irregular mass Ij^ing in the loop between the stomach and the 

 duodenum and best seen by turning the whole loop toward the 

 head. The pancreatic ducts are numerous but too small to be 

 observed readily. They open into the slender bile duct which 

 passes through the pancreas on its way from the liver and gall 

 bladder to the duodenum. Bile secreted by the liver passes down 

 the hepatic ducts into the common bile duct and is stored in 

 the gall bladder until it is discharged into the intestine. Bring 

 gentle pressure to bear upon the gall bladder. This will force 

 bile into the common bile duct which may then be located. It is 

 about the size of a large thread and enters the duodenum at a 

 point about one-half inch beyond the pylorus and on the inner 

 or concave side of the loop formed by the stomach and duodenum. 



The spleen is a small, dark-red, ovoid body lying in the mesen- 

 tery, opposite the beginning of the large intestine. It is not a 

 part of the digestive system. 



After the above-mentioned organs of the digestive system 

 have been located, turn the alimentary canal and its appendages 

 over to the left side of the body cavity so that the structures 

 of the excretory and reproductive systems may be studied on the 

 right side. 



The kidneys are a pair of elongate, reddish-brown organs 

 attached to the dorsal bodj' wall, close to the middle line, one on 

 each side of the vertebral column. They lie in the large lymph 

 space dorsad of (outside) the peritoneum The vreter, or duct 

 of each kidney, is a light-colored tube appearing to arise from the 

 outer caudal margin. It extends caudad to open through the 

 dorsal wall of the cloaca. On the ventral surface and partly 



