276 



ESSENTIALS OF ZOOLOGY 



mouth, by a stratified epithelium resting on the connective- 

 tissue layer called the submucosa, and its movements are 

 brought about by strong layers of muscle, circular and longi- 

 tudinal. 



The stomach consists of cardiac and pyloric chambers, 

 but is practically a single chamber opening by the cardiac 

 orifice into the oesophagus and by the pyloric orifice into the 

 intestine, the latter opening being on the right side and guarded 

 by a sphincter muscle. The cardiac end of the stomach is 

 lined by a continuation of the stratified epithelium, but in the 



Lumb. 



Jacobsorts 

 organ 



Ur. Post, 

 mes. 



Tes. Prep., 



Bl. 



FIG. 134. General dissection of rabbit to show the relationship of the 



organs and arteries. 



Phr. = pharynx ; Ur. ureter ; M n. = mandible ; Hy. = hyoid ; Epi. = epiglottis ; 

 Lar. = larynx; Thy. = thyroid; Tr. = trachea ; St. = sternum. 



pyloric region it becomes replaced by a single- layered epi- 

 thelium which is produced into simple tubular gastric glands. 

 The gastric glands give rise to a fluid which is acid, certain 

 cells of the glands liberating hydrochloric acid, and the fluid 

 contains the ferment pepsin and in the young condition rennin. 

 The alkalinity of the food is not lost all at once, and thus a 

 continuation of the ptyalin digestion may take place for some 

 time. But the action of the pepsin, aided by ferments in 

 the food, the parboiling produced by the heat of the stomach, 

 and the churning action of the walls, splits up the food and 

 reduces it to a more fluid condition containing peptones and 

 liberates much of the material from the mass, and even the 

 cellulose may be split up. It is then passed into the intestine 

 as chyme. 



