GASTRIC DIGESTION. 



Pure mixed gastric juice such as is obtained from a gastric 

 fistula forms a clear, colorless, and odorless solution with 

 an acid reaction and low specific gravity (1.004). The 

 total solids amount to only 2 per cent, of which the following 

 are the chief. 



Inorganic: hydrochloric acid, the chlorides of sodium, 

 potassium, and calcium, with traces of the phosphates of 

 magnesium and iron. 



Organic: pepsin, rennin or chymosin, mucin, traces of 

 other proteins, and sometimes lactic acid. 



HYDROCHLORIC ACID. 



In all probability the most important function of the 

 hydrochloric acid is that of a germicide preventing putrefac- 

 tion and the formation of obnoxious gases. Secondarily, it 

 gives to the gastric contents a more favorable condition for 

 the action of the pepsin, although the establishment of an 

 acid reaction is not absolutely necessary for peptic digestion. 

 The hydrochloric acid also seems to possess some power of 

 inverting cane-sugar. 



The following experiments are intended to simulate possi- 

 ble gastric mixtures which may be encountered in testing 

 stomach contents for HC1. The acid may appear alone or 

 together with lactic acid and digestive products. The relia- 

 bility and sensitiveness of the various indicators employed 

 under the different conditions will also be shown. 



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