114 



SALTS OF GASTRIC JUICE. 



[BOOK ii. 



juice, which are quoted in this place because of the bearing of the 

 results of the analyses of the salts found, upon the views of the mode 

 of production of the acid of gastric juice: 



Variations in the Proportion of Pepsin and Acid in the 

 Gastric Juice. 



Pepsin. 



The proportion of pepsin in the gastric juice under- 

 goes considerable variation during the progress of 

 digestion, undergoing first of all a diminution and then an increase. 

 This variation is observed also in the case of the secretion of the 

 isolated fundus, as has been shewn by Heidenhain, see Fig. 8, p. 105. 



At the commencement of digestion the acidity of 

 the gastric juice is less than subsequently, but this is 

 not the case when the secretion of the isolated fundus is examined. 

 The comparatively low acidity in the early periods is probably due 

 to the acid reaction being neutralised by the alkaline saliva and by 

 the alkaline secretion of the pyloric glands (Heidenhain). We shall 

 return to this subject again. 



Acid. 



SECT. 10. THE ACTION OF THE GASTRIC JUICE, AND ITS 

 CONSTITUENTS, ON THE PROTEIDS. 



The Researches and Views of Meissner. 



The first of the systematic investigations on the products result- 

 ing from the digestion of proteids by pepsin and hydrochloric acid, 

 was carried out by Meissner and his pupils between the years 1859 

 and 1862, and as subsequent writers have all more or less referred to, 

 or employed certain of, the terms which he applied to the produc 



; 



