INTERNAL STRUCTURE 



117 



organs 



• the liver and the pancreas. The liver is a 

 large, dark-red, three-lobed organ that covers the ventral 

 (lower) surface of the stomach. The pancreas is a 

 whitish, small, irregularly shaped body attached between 

 the stomach and the intestine. Both of these glands 

 drain into the intestine just beyond the stomach. The 

 bile secreted by the liver is at first collected in a sac 

 called the gall bladder. 



All of these parts of the alimentary canal are held in 

 place by a thin membrane (the mesentery, mOVen-te'r-y), 

 one edge of which is attached to the dorsal wall along the 

 line of the backbone and the other to the stomach and 

 intestine. A small gland (the spleen') is found in this 

 mesentery. The spleen has no duct connecting it with 

 any other organ in the frog. Blood vessels run through 

 the spleen and scientists believe that it is important in 

 making new blood corpuscles. 



Lungs. — The lungs are hollow sacs that lie back of the 

 stomach, one on each side. In the freshly killed animal, 

 these can be filled with air by inserting a blow-pipe into 

 the windpipe and blowing air into them. The empty 

 lungs are about as large as the 

 blunt end of a lead pencil. 



Kidneys. — The kidneys are 

 small red bodies lying close to 

 the back. Each one is connected 

 with the cloaca by a minute duct 

 (ureter). The urinary bladder 

 is attached to the cloaca (Fig- 

 ure 116). 



Reproduction. — The male 

 frog has a pair of spermaries 

 (speYma-riz), one attached to 

 the front (anterior) end of each Figure 116. 



// fat bodies 



^•testis 



kidneu 



-unnogenital 

 duct 



cloaca 



