4 8 



MANUAL OF ELEMENTARY ZOOLOGY 



bladder, and dorsally the ducts of the kidneys and in the 

 female those which bear the eggs. 



Besides numerous small glands in the mucous membrane, 

 the alimentary canal receives the secretions of two large 

 glands, the liver and the pancreas. The liver is a large, 

 reddish-brown structure in the forepart of the belly. It 

 consists of a right and a left lobe and a small' median lobe 



pn.s. a.ch.p. 



m.ob. 



Fig. 24. — A longitudinal median section through the head of a frog. 



Taq., Aquaeductus cerebri; a.ch.p., anterior choroid plexus; br., bronchus; c.c, 

 central canal of spinal cord ; cb., cerebellum ; cer.h., left cerebral hemisphere ; 

 e.n., nostril; Eu., Eustachian tube ;,/*.Af., foramen of Monro ; gls., glottis; 

 i.n., internal narial opening; in/., infundibulum ; lar, larynx: Q., left lung ; 

 m.ob., medulla oblongata ; o.L, optic lobe ; ass., oesophagus ; olf.l., olfactory 

 lobe; p.ch.p., posterior choroid plexus ; pit., pituitary body; pn.s., pineal 

 stalk ; III.v., third ventricle ; IV.v., fourth ventricle. 



which unites them. The left lobe is the larger and is itself 

 deeply cleft into two. Between the right and left lobes lies 

 the gall-bladder, which receives the green bile secreted by 

 the liver and passes it by the bile-duct into the duodenum. 

 The pancreas is an oblong, creamy-white structure lying 

 between the stomach and duodenum. It is traversed by 

 the bile-duct, into which it passes the pancreatic juice which 

 it secretes. 



The food is not chewed, but is swallowed whole, the 

 only use of the teeth being to prevent the escape of the 



