80 THE GASTRIC JUICE. 



194. VALUATION OF PEPSIN (U. S. P., 1900). Mix 9 cubic 

 centimeters of 10 per cent, hydrochloric acid with 291 cubic centi- 

 meters of distilled water, and in 150 cubic centimeters of this liquid 

 dissolve 0.1 gramme of pepsin. Immerse and keep a hen's egg, 

 which should be fresh, in boiling water during 15 minutes. Then 

 remove it and place in cold water. Separate the coagulated 

 albumin from the pellicle and yelk and rub it through a clean 

 sieve having 40 meshes to the linear inch. Reject the first portion 

 passing through the sieve. Weigh 10 grammes of the second, 

 cleaner portion, place it in a flask of a capacity of about 100 cubic 

 centimeters, then add 20 cubic centimeters of the diluted acid and 

 with a glass rod disintegrate the albumin. Rinse the rod with 15 

 cubic centimeters of the dilute acid, add 5 cubic centimeters of the 

 pepsin solution, cork and shake. Place the flask in a water -bath 

 kept at a temperature of 52 C. for two and one-half hours, shaking 

 every ten minutes, then remove and add 50 cubic centimeters of 

 cold, distilled water. Transfer to a narrow glass cylinder and 

 allow to stand half an hour. The deposit of undissolved albumin 

 should not be more than 1 cubic centimeter. Trustworthy results, 

 particularly in comparative trials will be obtained only if the 

 temperature be strictly maintained and if the contents of the 

 flasks be agitated uniformly and in equal intervals of time. 



The relative proteolytic power of pepsin stronger or weaker 

 than that described above may be determined by ascertaining, 

 through repeated trials, how much of the above pepsin solution 

 will be required exactly to dissolve 10 grammes of coagulated and 

 disintegrated albumin under the conditions given above. Divide 

 15,000 by this quantity expressed in cubic centimeters to ascertain 

 how many parts of egg albumin one part of pepsin will digest. 



In recent years the composition of the gastric juice and 

 its variations in disease are being more and more thoroughly 

 studied and the results of the observations made use of in 

 clinical work. The only obstacle to the general adoption 

 of these tests is probably the difficulty of obtaining the 

 fluid from the stomach. 



With a little experience, the collection of the gastric juice 

 for testing can be easily accomplished. In order to excite the flow 



