50 



STOMACH FOLLICLES. 



The preceding table, from Hublbenet, shows that nearly two thirds of 

 Pro erties of ^ ie s0 ^ matcr ^ ^ ^ e gastric juice is pepsin. Exposure 



the gastric 

 juice. 



to a very low temperature does not deteriorate the properties 

 of this substance, for it will resume its activity even after be- 

 ing frozen. But, on the contrary, a temperature approaching ebullition 

 destroys its solvent power, and the same effect ensues when it is neutral- 

 ized by an alkali. 



The gastric juice acts on iron or zinc with evolution of hydrogen, an 

 effect which the acid phosphate of lime can not produce. This seems 

 to be decisive against the views of those physiologists who have imputed 

 its reaction to the latter substance. 



The digestive power of this juice is impeded by the presence of almost 

 any alkaline salt. To this remark common salt offers no exception. It 

 is owing to its alkalinity that saliva injures the digesting power of gas- 

 tric juice. On the contrary, that power is very much increased by the 

 Fig. 4 presence of fat, which promotes the conversion 



of protein bodies into peptones. 



The mucous membrane of the stomach pre- 

 sents a reticulated appearance, as shown in Fig. 

 Stomach foiii- 4. At the bottom of each compart- 



Mucous membrane of the stomach 

 magnified TO diameters. 



and functions ' foUideS, the size and depth of wllidl 



increase toward the pylorus. Their exterior is 

 partly covered with columnar epithelium, which extends over the inter- 

 vening ridges ; the residue is glandular, and continu- 

 ally gives origin to granules. The upper part of 

 each follicle, as well as the entire surface of the mu- 

 cous membrane, is usually covered with mucus. 



In Fig. 5 is a representation, given by Todd and 

 Bowman, of stomach follicles and their tubes in a 

 vertical section. The specimen is from the dog after 

 twelve hours fasting. A represents these structures 

 in the middle region of the stomach ; B in the pylor- 

 ic region ; a a, orifices of the follicles on the inner 

 surface* of the stomach ; b b, different depths at which 

 the columnar epithelium is exchanged for glandular ; 

 d, pyloric tubes terminating variously, and lined to 

 their extremities with columnar epithelium. 



Fig. 6, A, horizontal section of a stomach folli- 

 cle a little way within its orifice ; <z, basement mem- 

 brane ; b y columnar epithelium. All but the centre 

 of the cavity of the cell is occupied by a transparent mucus, which seems 

 to have oozed from the open extremities of the epithelial particles ; c, 



Vertical section of stomach 

 follicles and tubes magni- 

 fied 150 diameters. 



