162 THE BIOLOGY OF THE ANIMAL 



Examine the opening between the cardiac and 

 pyloric portions of the stomach guarded by the 

 median cardio - pyloric valve. How is it 

 formed ? What is the nature of its surface ? 

 Which way does it open ? Do you find other 

 valves, the lateral cardio - pyloric valves? 

 If so, compare with the median valve. Note 

 the opening into the intestine. Is it also guard- 

 ed by valves and setae ? 



c. The intestine. ^ — If necessary, distend the intestine 



with water injected with a pipette into the anus. 

 What is its general direction through the body ? 

 At what point does it leave the stomach ? What 

 is its length ? How is it held in place ? On the 

 dorsal surface of the intestine, near the posterior 

 end, find a sac-shaped outgrowth, the coeciun. 

 How does it compare with the intestine in diam- 

 eter? Split the intestine open by a cut made 

 lengthwise along the dorsal surface from the 

 anus to the pyloric portion of the stomach. Is 

 the intestine wrinkled or folded ? If so, in what 

 direction? Is the lining membrane anterior to 

 the coecum similar to that posterior to the same 

 part? Is that part posterior to the coecum con- 

 tinuous with the exoskeleton ? Compare with the 

 lining membrane of the stomach. 



Find a lobulated mass lying on each side of the 

 stomach, 



d. The digestive glands or "liver." — How much 



of the cephalothorax does it occupy? What is 

 its color? Look for the duct by means of which 

 the gland connects with the intestine. Where 

 does the duct enter the intestine % 



