I.] THE FROG. 45 



the outer face of the eye-ball. The upper lid is 

 thick and fleshy; the lower (nictitating membrane] 

 is thin and transparent. 



e. The sub-cutaneous lymph spaces ; present only above 

 and below. 



D. The alimentary system. 



i. Obtain a male frog, and pin down upon its back 

 under water. Remove the whole of the ventral 

 integument and body-wall and dissect away the 

 heart. Next remove the dorso-lateral portion of the 

 body-wall, between the back of the head and the 

 level of the hinder third of the large intestine, and 

 with it the kidneys and testes. Carefully dissect 

 away the mesenteric folds which support the liver 

 and bladder, and wash clean. 



a. The general disposition of the parts. Cf. Sect. B. 



2-/ 



b. The pancreas : a Y-shaped compact yellow mass 

 lying in the mesentery between the stomach and 

 head of the intestine. 



c. The gall-bladder: a small green sac, lying between 

 the right lobe of the liver and the head of the 

 pancreas. 



d. The small intestine; of uniform calibre through- 

 out. It may be resolved into 



a. The duodenum; a short straight segment running 

 parallel with the stomach and related to the 

 pancreas. 



(3. The ileum; the terminal coiled portion, desti- 

 tute of connection with the pancreas. 



