REGULATION OF GASTRIC SECRETION. 195 



chloric acid never varies. TVws applies, however, only to the 

 gastric juice as it is poured out by the glands. Once the juice 

 has left the, crypts of the gastric mucosa, its acidity may be 

 reduced through various agencies, and it is to these that the 

 fluctuations in the acidity of the gastric juice under various 

 physiological and pathological conditions must be attributed. 

 The mucus secreted by the stomach-wall has the power of 

 neutralizing the acid of the gastric juice. For this reason 



45 



71 2345678 



FIG. 22. Digestive power of hourly portions of gastric juice after a 



meal of 400 gms. of meat. 



(Copied from PAWLOW: Work of the Digestive Glands. Trans, by 

 THOMPSON, London, 1902, p. 28.) 



the first juice collected from the stomach of a fasting dog 

 always has a lower acidity than later specimens, for the 

 empty stomach is covered with a layer of mucus. Also, the 

 more rapidly gastric juice is secreted the higher is its acidity, 

 for in this way less time is allowed for the neutralization of 

 the hydrochloric acid through the gastric mucus. Finally, 

 the power of the saliva which enters the stomach to neu- 

 tralize the acid secreted there must also be borne in mind. 



The gastric juice poured out upon different kinds of food 

 varies not only in quantity but also in quality. The ex- 

 periments of some of the older observers lend support to 

 this idea, but their results cannot be looked upon as en- 

 tirely free from criticism. The results of PAWLOW and his 



