COMPOSITION OF HUMAN GASTRIC JUICE, 195 



daily secreted is difficult of determination, and it is not surprising 

 that authorities should differ so much on this point. Dr. Beau- 

 mont estimated it to be 180 grams in the case of St. Martin, while 

 others place it as high as 7 liters, or one-tenth of the weight of 

 the body. The gastric juice is never in large quantity in the 

 stomach at any one time. It is secreted gradually by the glands, 

 is poured out into the cavity of the stomach, where it permeates 

 the food, is passed on into the small intestine, where it is absorbed 

 by the blood-vessels, and is then returned to the circulation, from 

 which its constituents were derived. It has the following proper- 

 ties : it is clear, nearly colorless, and strongly acid. Its specific 

 gravity is about 1002. 



Composition of Human Gastric Juice Mixed with 

 Saliva. As can readily be understood, it is impossible to obtain 

 gastric juice unmixed with particles of food or saliva or other 

 foreign substances, hence an accurate analysis cannot be given. 

 The analysis by Schmidt of gastric juice from a woman having a 

 gastric fistula, which is the only complete analysis on record, is as 

 follows : 



Water 99.4400 



Organic substances (pepsin, peptones, and rennin) ... .3195 



Free hydrochloric acid 0200 



Calcium chlorid 0061 



Sodium " 1464 



Potassium " 0550 



Calcium "| 



Magnesium I phosphates 0125 



Ferrum J 



Loss . _, . .0005 



100.0000 



The constituents of the gastric juice of special physiologic 

 interest are hydrochloric acid, pepsin, and rennin. It was at 

 one time a matter of dispute whether the acidity of this fluid was 

 due to hydrochloric or to lactic acid, but there is now a unanimity 

 of .opinion that it is the former. If lactic acid is present, it is 

 probably due to lactic fermentation which has taken place in the 

 carbohydrates of the food when these are in excess. This fermen- 

 tation may go on to the formation of acetic and butyric acids, 

 these changes being doubtless due to the presence of micro- 

 organisms. 



Hydrochloric Acid. The amount of free hydrochloric acid in 

 human gastric juice varies from 0.05 to 0.3 per cent. Several of 

 the best authorities give the average as between 0.2 and 0.3 per 

 cent. 



Although the only possible source of hydrochloric acid is the 

 chlorids of the blood, which decomposing yield chlorin, and this 

 uniting with hydrogen forms the acid, yet the manner of its for- 



