212 DIGESTION. 



stream of water, the membrane will be found marked with 

 innumerable polygonal pits or depressions, enclosed by 

 ridges, which in some parts of the organ are quite regular. 

 These are best seen with the aid of a simple lens, as many 

 of them are quite small. The size of the pits is very va- 

 riable, but the average is about ^ of an inch. This ap- 

 pearance is not distinct toward the pylorus ; the membrane 

 here presenting irregular conical projections, and some well- 

 marked villi resembling those found in the small intestine. 

 The surface of the mucous membrane is covered with co- 

 lumnar or prismoidal epithelium ; the cells being tolerably 

 regular in shape, with a clear nucleus and a distinct nucleolus. 

 The thickness of the mucous membrane of the stomach 

 varies in different parts. It is usually thinnest near the 

 oesophagus, and thickest near the pylorus. Its thinnest 

 portion measures from -f-% to -$ of an inch ; its thickest por- 

 tion from y 1 ^ to y 1 ^ of an inch ; and the intermediate portion 

 about ^4- of an inch. 



Glandular Apparatus of the Stomach. Extending from 

 the bottoms of the pits in the mucous membrane of the stom- 

 ach to the submucous areolar tissue, are immense numbers 

 of tubular glands. These are generally arranged in tolera- 

 bly distinct groups surrounded by fibrous tissue ; each group 

 belonging to one of the polygonal depressions. The tissue 

 which connects the tubes is dense, but not abundant. The 

 researches of Wasmann, Todd and Bowman, Kolliker, Bon- 

 ders, Brinton, and others have shown marked differences in 

 the anatomy of the glands and follicles of the stomach in 

 different parts of the organ, which are particularly interest- 

 ing, as they are supposed to correspond with differences in 

 the function of various parts of the mucous membrane. 

 There are, indeed, two distinct varieties of follicular glands : 

 the gastric tubules, found throughout the organ, except in 

 the pyloric portion ; and the mucous follicles, found in the 

 pyloric portion. These demand special consideration, as the 



