Ii8 A GUIDE FOR THE STUDY OF ANIMALS 



Placing the frog on its back, with forceps firmly grasp 

 the skin of the abdomen and the muscles beneath, just in 

 front of the hind legs, and with the scissors cut straight 

 forward in the middle line until the floor of the mouth is 

 reached ; this will separate the arms. Care must be taken 

 not to cut too deeply, but this may be avoided by keeping 

 the skin uplifted. Now cut sidewise in front of each hind 

 leg in order that the body wall may be laid aside. Under 

 the arms the heart will be seen ; it will be studied as a part 

 of the circulatory system. 



Identify the following organs : — 



Liver, the large red or brown mass, consisting of several 

 divisions and lying close up under the arms. 



Bile sac, small, green, and between the liver lobes. 

 Alimentary canal. 



1. Mouth. 



2. Esophagus. 



3. Stomach, the elongated, light-colored, firm, 

 and muscular portion. 



4. Small intestine, a slender, more or less closely 

 coiled, tubular portion. 



5. Large intestine, a thin-walled enlargement at 

 the posterior end of the canal. 



6. Duodenum. This is a muscular portion of the 

 small intestine immediately following the stomach, 

 against which it is folded. 



Pancreas, a yellowish, pulpy mass lying in the fold 

 between the stomach and the duodenum. 



Spleen, a dark red globule, usually smaller than a pea, 

 lying nearly free among the folds of the small intestine. 



Fat bodies, yellow fringe-like structures, sometimes found 

 near the stomach. 



