CHAP. VI.] THE CAT'S ALIMENTARY SYSTEM. 



179 



o:c 



called its "lesser curvature (/c). Tlie opposite very convex side 

 is called its greater curvature {gc). 



Its structure is essentially similar to that of the oesophagus. Its 

 muscular coat, formed of organic fibres, consists of an outer radiating 

 layer, directly continuous with the more longitudinal layer of the 

 oesophagus. Within this is a 

 layer of circular fibres which 

 extends over the whole sto- 

 mach, and is especially thick 

 at the pylorus, where it forms 

 a sphincter which, project- 

 ing inwards, constitutes (with 

 areolar tissue and its mucous 

 lining) what is called the "py- 

 loric valve" (Fig. 90, V>,])v). 



Within the second muscular 

 layer is yet a third set of 

 obliquely disposed fibres. 



Immediately within the 

 muscular stratum is a layer 

 of submucous areolar tissue, 

 which directly supports the 

 mucous lining of the stomach. 

 This lining is soft, thick, and 

 smooth, and is so loosely 

 connected by the areolar layer 

 with the muscular coat, that 

 it is thrown into numerous, 

 regular, undulating efi'aceable 

 folds when the stomach is 

 not distended. The inner 

 surface of the stomach is 

 everywhere beset with small 

 pits, which are the orifices 

 of minute close-set gastric and 

 peptic glands, which may be simple tubes or more or less branching. 



At the lower end of the oesophagus the squamous epithelium ceases 

 and gives place to what is mostly of the columnar kind. 



The FUNCTION of the stomach is partly mechanical, since by their 

 contractions, its many muscular fibres rotate its contents, and so 

 expose all parts in turn to the action of its secreting waUs while they 

 drive it towards the pylorus, and send through that aperture such 

 portions of it as are sufiiciently dissolved or soft. Regurgitation of 

 food into the oesophagus is prevented by the contraction of the 

 circular fibres which surround its entrance into the stomach. The 

 main action of the stomach is digestive through the gastric juice. 

 This consists of water, with some two per cent, of saline matters, 

 a minute quantity of free hydrochloric acid and a little more 



than three per cent, of pepsin, a neutral, albuminoid substance. 



N 2 



Fig. 93. — The Intestinal Tube of the Cat, seen 



VENTRALLY, WITH ITS FOLDS SOMEWHAT SEPARATED. 



Ic. Lesser curvature. 

 p. Pylorus, 

 r. Rectum. 



a Anus. 



ac. Ascending colon. 



a. ffisojiliagus. 



c. Cardia. 

 CO',. Cificum. 



d. Duodenum. 



do. Descending colon. 



si. Small intestine. 

 St. Stomach. 

 tc. Transverse colon. 

 X. Greater curvature. 



