z8z DIGESTION. 



Composition of Gastric Juice. 



| Ferment, Pepsin (with 



a trace of Ammonia) 3-19 4-20 I 7'S 



Hydrochloric Acid . 0.20 1-55 2-70 



Solids Chloride of Calcium . 0-06 o- 1 1 I -66 



Sodium . 1-46 4-36 3-14 



Potassium 0-55 1-51 1-07 

 Phosphate of Lime, 



Magnesia, and Iron . O'I2 2-09 273 



In all the above analyses the amount of water given 

 must be reckoned as rather too much, inasmuch as a cer- 

 tain quantity of saliva was mixed with the gastric fluid. 

 The allowance, however, to be made on this account is 

 only very small. 



Considerable difference of opinion has existed concern- 

 ing the nature of the free acid contained in the gastric 

 juice, chiefly whether it is hydrochloric or lactic. The 

 weight of evidence, however, is in favour of free hydro- 

 chloric acid, being that to which, in thelmman subject, the 

 acidity of the gastric fluid is mainly due ; although there 

 is no doubt that others, as lactic, acetic, butyric, are not 

 unfrequently to be found therein. 



The animal matter mentioned in the analysis of the gas- 

 tric fluid is named pepsin, from its power in the process 

 of digestion. It is an azotised substance, and is best pro- 

 cured by digesting portions of the mucous membrane of 

 the stomach in cold water, after they have been macerated 

 for some time in water at a temperature between 80 and 

 1 00 F. The warm water dissolves various substances as 

 well as some of the pepsin, but the cold water takes up 

 little else than pepsin, which, on evaporating the cold 



