DIGESTION. 151 



i? the gastric juice, produced by the glandular follicles of its mucous 

 membrane. 



The mucous membrane of the stomach is soft and vascular, about one- 

 half a millimetre thick in the cardiac portion, thence increasing in thick- 

 ness to one millimetre in the middle and two millimetres in the pyloric 

 portion. It presents an abundance of ridges or prominences about 

 one-tenth of a millimetre in height, which in the cardiac portion are 

 reticulated with each other, in the pyloric portion more isolated and 

 villus-like in form. Its free surface is covered with cylindrical epi- 

 thelium. 



Its substance consists mainly of tubular follicles, lined with glandu- 

 lar epithelium, closely packed side by side, their bases resting upon the 

 submucous layer, and their orifices opening upon its free surface. The 

 space between them is occupied by the capillary blood-vessels and lym- 

 phatics, the terminal nerve fibres, and a slight framework of connective 

 tissue. The gastric mucous membrane has therefore the character of a 

 gland spread out in the membranous form, and surrounding the sac-like 

 cavity of the organ. 



The epithelium cells lining the follicles are of two kinds. The most 

 abundant are pale, finely granular cells, about 13 mrnni. in diameter, 

 nearly or quite filling the cavity of the follicle in its middle and lower 

 portions. The cells of the other 

 variety are fewer in number, of FTG - 



larger size, measuring about 22 

 mmm. in diameter, with a dis- 

 tinct rounded form, often pro- 

 jecting from the mass of smaller 

 cells, and causing varicose-like 

 prominences of the contour of 

 the follicle (Fig. 24). These 

 cells are found in both the fun- 

 dus and middle portion of the 

 stomach, especially in its middle 

 portion ; but they do not exist 

 in the follicles of the pyloric 

 region, which contain cells of 

 the smaller variety alone. In 



. , . GASTRIC FOLLICLES, with large glandular cells : from 



preparations stained with car- middle portion of Pig's stomach, 



mine, if taken from the stomach 



during the intervals of digestion, the smaller cells are tinged but 

 slightly or not at all, while those of the larger variety exhibit a strong 

 pinkish hue, showing a difference in their organic substance. But in 

 specimens taken while digestion is going on, all the cells are turgid and 

 granular, and the smaller ones not only increased in size but so altered 

 in constitution as to be stained by the carmine solution. In prepa- 

 rations from the fasting animal, accordingly, the difference between the 



