THE FROG 29 



2. Liver. A large, dark red mass, dorsal to the heart. 

 What is its size and shape? Of how many lobes is it com- 

 posed? Between the lobes is the bile sac, .or gall bladder. 

 The cystic ducts are tubes which lead from the liver to the 

 bile sac and the bile duct extends from the bile sac through 

 the pancreas to the digestive tube, which it enters about 

 half an inch posterior to the stomach. Turn the liver for- 

 ward and trace the bile duct to its opening into the intestine. 



Make a drawing of this region. 



(If the specimen is a female take up, at this point, the 

 study of the reproductive organs. Having shown their 

 position, size and structure in a drawing, remove them and 

 study further the other organs of the body cavity.) 



3. Lungs. Two thin-walled sacs dorsal to the liver and 

 at the sides of the esophagus. Note the texture pf the walls 

 and the character of the lining. The lungs may be expanded 

 by blowing air into them. 



4. Stomach. Note the shape, size and position. How 7 

 is the stomach held in place? Slit the stomach longitudi- 

 nally, and determine the character of its walls and its lining. 



5. Intestine. Is it straight or coiled? How is it held in 

 position? Compare the walls with those of the stomach. 

 Near the posterior end note an enlargement, the large intestine. 



6. Pancreas. A pale mass lying in the loop made by 

 stomach and intestine. Show its position in the drawing 

 made of the liver. 



7. Spleen. A small round body lying in the posterior 

 part of the body. Does it appear to be joined to, or connected 

 with any other organ? 



8. Bladder. A thin walled sac in the extreme posterior 

 part of the body cavity. What is its shape? With what 

 organs does it communicate? 



Make a drawing to show the organs so far studied. 



