230 THE BIOLOGY OF THE ANIMAL 



To the liver? How is the oesophagus held in 

 place ? Carefully pinch the oesophagus with the 

 fine forceps. "What is the nature of the wall? 

 How do you distinguish the boundary between 

 the oesophagus and the stomach ? With the scis- 

 sors make on the ventral side of the oesophagus a 

 transverse slit, half severing it from the stomach, 

 then from this slit make a longitudinal cut ex- 

 tending towards the mouth, thus laying open the 

 oesophagus. Spread back the two flaps, remove 

 the contents, if any, and examine the wall of the 

 oesophagus. Do you find the lining membrane 

 or mucous membrane arranged at all differ- 

 ently from the outer wall ? 



c. The gtomach. — On which side of the body does 

 it lie ? "What is its shape ? What is its relation to 

 the liver? Note the membrane or mesentery 

 which holds the stomach in place. Lay open the 

 stomach by a cut extending along its left margin. 

 Does its wall differ in any way from that of the 

 oesophagus? Notice particularly the arrange- 

 ment of the lining or mucous coat. Does this 

 differ at aU in stomachs which are distended with 

 food and those which are empty ? 



Leading from the posterior end of the stomach 

 find the intestine, consisting of a coiled portion, 

 the small intestine, and a straight portion, the 

 large intestine. 



d. The small intestine. — What is its position? 

 Shape ? Color ? How is it arranged ? Are its 

 various coils connected ? If so, by what means ? 

 How does it compare in diameter with the oesoph- 

 agus? With the stomach? Is the wall of the 



