218 VERTEBRATE ZOOLOGY 



bladder with the kidneys and appear as white cords, and in the 

 male the vasa deferentia, which also appear as white cords lying 

 ventral to the rectum, must be carefully preserved. Find the 

 anterior, or cardiac, end of the stomach and note the oesophagus, 

 which comes through the diaphragm from the thoracic cavity 

 and joins it. With scissors cut the oesophagus ; cut the connec- 

 tions of the stomach and take it and the intestine from the body. 



Exercise 10. Draw an outline of the stomach and duodenum, the 

 hinder part of the ileum, and the large intestine. Label all 

 carefully. 



Cut the rectum at the level of the bladder, taking care not to 

 injure the ureters and, in the male, the vasa deferentia. Slit open 

 the stomach and note the longitudinal folds of its mucous mem- 

 brane; at its pyloric end note the pyloric valve, a constriction 

 caused by the thickening of the circular muscles of the stomach 

 at this point. Slit open the duodenum and note its velvety appear- 

 ance, caused by the presence of the villi,— delicate, fingerlike 

 projections of the mucous membrane. Slit open the hinder end 

 of the ileum, together with the caecum and the forward portion 

 of the colon, and note the ileocolic valve, a projection of the inner 

 wall of the ileum into the colon permitting substances to pass 

 in one direction only. 



Exercise 11. Make a drawing showing the ileocolic valve. 



The Urogenital System. This system includes the urinary and 

 the genital organs. Although these two groups of organs are quite 

 different in function, they bear a close topographical relation to 

 each other and will be studied together. 



The urinary system consists of a pair of kidneys, a pair of 

 ureters, a urinary bladder, and a urethra. The kidneys are large, 

 reniform bodies, which lie against the dorsal body wall on each 

 side of the spinal column, in the middle of the abdominal cavity ; 

 the right kidney lies somewhat in advance of the left one. The 

 peritoneum stretches over the ventral surface of the kidney and 

 holds it tightly against the muscles of the body wall; around 

 its sides, between the peritoneum and the muscles, is a great 



