THE RABBIT 281 



Exercise 7. Draw a diagram showing the portal system so far as 

 observed; carefully label all its parts. 



The Digestive System {Continued). Lift up the intestines and 

 cut the mesenteries where they join them; cut also the bile duct. 

 Straighten out the intestines from the stomach to the anus, being 

 careful, however, not to injure the urinary bladder, which lies 

 ventral to the rectum. Carefully preserve also the two ureters, 

 which join the kidneys with the bladder and appear as white 

 cords, but are often concealed by fat; and in the male animal 

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

 ventral to the rectum. Find the anterior, or cardiac, end of 

 the stomach and cut the oesophagus where it joins it; cut also 

 the connections of the stomach and remove it and the intestines 

 from the body. 



Exercise 8. Make a drawing, on a reduced scale, of the stomach and 

 the extended intestines. 



Sever the rectum at the level of the bladder, and place the 

 stomach and intestines in a pan or bowl of water. Slit open the 

 stomach, duodenum, sacculus rotundus, caecum, and appendix, 

 and thoroughly wash them out. At the pylorus note the pyloric, 

 valve, a constriction caused by the thickening of the circular 

 muscles of the stomach at this point ; in the duodenum note its 

 velvety appearance, due to the presence of the villi,— delicate, 

 fingerlike projections of its mucous membrane ; in the caecum note 

 the spiral valve, a ridge which projects into the interior; in the 

 saculus rotundus note the ileocolic valve,— an elevation, at the 

 opening into the colon, projecting into the ileum. 



The Urogenital System. This system includes the urinary and 

 the genital organs. 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 being 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 ; 

 and around its sides, between the peritoneum and the muscles, 



