THE DIGESTIVE SYSTEM 73 



Open the abdominal cavity by a median incision from 

 the diaphragm to the pelvis. 



The stomach lies on the left side in the abdominal cavity, 

 in contact with the concave posterior side of the liver. It 

 resembles a half of a doughnut in shape. The long axis 

 forms approximately a right angle with the long axis of 

 the body. The greater curvature which corresponds to 

 the outer edge of the doughnut, is ventral. The lesser 

 curvature y analogous to the rim of the doughnut's hole, is 

 dorsal. The esophagus enters the stomach on its dorsal 

 side, through the cardiac orifice, or cardia, near the center 

 of the lesser curvature. The esophagus is closer to the 

 right half of the lesser curvature than to the left, thus 

 entering the stomach obliquely. External inspection of a 

 full stomach reveals two distinct regions. The wall of 

 somewhat more than the left half, the cardiac sac, is flexible, 

 thin, and in a preserved specimen sufficiently transparent 

 to permit the food it contains to be seen from the outside. 

 The wall of the right region of the stomach, on the other 

 hand, is opaque and relatively firm. This part decreases 

 in size dorsally and communicates with the small intes- 

 tine through the pylorus. The inner surface of the stomach 

 comprises two areas corresponding to the two regions 

 seen from the outside. These may be seen to good advan- 

 tage by opening the distended organ with an incision ex- 

 tending throughout the length of the greater curvature. 

 The inner surface of the cardiac sac at the left is hard, 

 smooth, and glossy. The wall is tough. If the stomach was 

 distended with food when the animal died, the wall is 

 slightly transparent, the transparency increasing as the 

 tissue dries. In the region at the right the inner surface 

 is yellowish in color, opaque, brittle in a preserved ani- 

 mal, and more or less prominently folded, especially near 

 the pylorus and on the greater curvature. The two re- 



