12 GUIDES FOR VERTEBRATE DISSECTION 



intestinal artery. Trace the first of these to stomach, spleen and 

 pancreas. What portion of the stomach does it supply? Also 

 trace the posterior intestinal to the dorsal surface of the intestine. 

 Does it send branches to the spiral valve like those of the 

 anterior intestinal? How far forward and backward does it 

 extend? 



The inferior mesenteric artery courses in the anterior margin 

 of the mesorectum. Trace it to the mid-dorsal line and to the 

 rectum and rectal gland. 



Sketch these arteries (in red) so far as made out on a sheet 

 large enough to accommodate the whole fish and put it aside for 

 later additions. 



Veins. The anterior intestinal vein runs on the anterior 

 surface of the large intestine parallel to the similarly named 

 artery. Does it receive branches from the spiral valve? Trace 

 it forward into the hepato-duodena-1 omentum, noting the point 

 at which it receives a splenic vein from the spleen. On the 

 dorsal side of the intestine the posterior intestinal vein can be 

 traced forward from the rectum and rectal gland to about the 

 middle of the spiral valve region. Thence it ascends in the 

 mesentery, passes directly to the spleen, where it receives several 

 splenic branches as well as some from the cardiac region of the 

 stomach. Follow the main trunk along from the spleen to the 

 pancreas, not overlooking the entrance of a gastric vein, to its 

 union with the anterior intestinal vein to form the hepatic-portal 

 vein which is to be traced to the liver. Just in front of the union 

 of the two intestinals the portal vein receives a duodenal vein, 

 the origin of which should be traced. 



Sketch these veins on a separate sheet (in blue) and put 

 aside for other additions. 



Alimentary Canal. Examine the cardiac portion of the 

 stomach more closely, noting the ramifications of the gastric 

 branch of the vagus nerve on its walls. 



In the hepatoduodenal omentum find the bile-duct. Where 

 does it connect with the intestine? Trace it forward into the 

 gall-bladder and into the liver. In which lobe of the liver is 

 the gall-bladder imbedded? Add bile-duct and bladder to the 

 drawing of the alimentary canal. 



Cut away about a quarter of the surface of the large intestine 

 with the scissors for three or four inches, making a 'window' 



