GASTRIC CONTENTS. 85 



Qi) Test for pepsin by determining the digestive 

 powers of the juice. In the absence of free HCl no 

 pepsin will be found and tests must be directed towards 

 its zymogen, pepsinogen. 



Add a small, shaving 1 cm. square and 1 mm. thick, 

 of coagulated egg albumin to 10 cc. of the filtrate, and 

 keep at 37°C, one to two hours. If there- is no free HCl 

 present, add 3 or 4 drops of a 25% solution of HCl, so 

 as to transform any pepsinogen into pepsin. After two 

 hours the shaving ought to be digested. 



Quantitative estimation of the pepsin is carried out 

 by making a series of dilutions and testing the digestive 

 powers of these dilutions. This procedure is rarely 

 called, for in clinical practice. 



(i) Tests for the milk curdling ferment, "rennet" 

 and its zymogen. 



1. In testing for rennet add 3 to 5 drops of the fil- 

 trate to 10 cc. milk and keep at 37°C. If rennet is 

 present the milk clots in 10 to 15 minutes. 



(2) If no coagulation occurs, test for the rennet 

 zymogen, by neutralizing some of the gastric contents 

 with lime water, and then adding 3 to 5 drops, to the 

 milk, when if the zymogen is present, coagulation 

 occurs in 10 to 15 minutes. Quantitative tests can be 

 carried out by a series of dilutions as is done for pepsin, 

 but are rarely required clinically. 



(j ) Tests for the condition of the various food con- 

 stituents of the test meal, may also be carried out. 

 Practically, tests are required only for presence of pep- 

 tone, propeptones, and the stage of starch digestion. 



