THE GASTRIC JUICE. 141 



of time serves as a measure of the digestive power of the specimen 

 examined. The calculation of the corresponding amount of ferment 

 is based upon the law of Schiitz and Borissow, viz., that correspond- 

 ing amounts of ferment in two solutions bear the same ratio to each 

 other as the square of the number of millimetres of the column of 

 egg-albumin which has been dissolved in the same length of time. 



Example. The gastric juice of a normal individual is procured 

 at the height of digestion after giving Ewald's test breakfast. The 

 tube is digested for thirty minutes ; at the end of this time the 

 height of the column of albumin digested measures 3 mm. Then 

 the stomach contents of a second individual are obtained (the 

 patient's) and similarly treated ; in this case the column of digested 

 albumin measures 2 mm. The corresponding amounts of ferment 

 are then as 9 is to 4. 



Pepsinogen. The presence of pepsinogen in the gastric juice 

 can be ascertained only when hydrochloric acid is absent, as it is 

 otherwise transformed into the active enzyme. Its occurrence, as 

 such, is hence essentially a pathologic phenomenon, and indicates the 

 absence of free hydrochloric acid. But while the latter may be 

 absent in many diseases which are not associated with structural 

 abnormalities of the gastric mucous membrane, pepsinogen, and con- 

 sequently also pepsin, are found lacking only in disease of the 

 stomach itself, and when complete atrophy of the glandular struct- 

 ures has occurred. 



Test for Pepsinogen. Specimens of gastric juice in which pepsin- 

 ogen only is present are incapable of digesting albumins. In such 

 cases, as I have just said, hydrochloric acid is absent. If then 

 the solution is acidified to the extent of from 0.1 to 0.3 per 

 cent., and the dissolution of a flake of boiled beef-fibrin now occurs, 

 the presence of the zymogen may be inferred. 



Quantitative Estimation of Pepsinogen. The determination of the 

 absolute quantity of pepsinogen in the gastric juice, as that of pep- 

 sin, is not possible. Relative values, however, may be obtained by 

 the following method, as suggested by Boas : To this end, specimens 

 of the gastric juice are variously diluted with distilled water in the 

 proportion of 1 : 5, 1 : 10, 1 : 20, etc. A known quantity of coagu- 

 lated egg-albumin or serum-albumin is then added to each tube, 

 as also 1 or 2 drops of a 0.3 per cent, solution of hydrochloric acid, 

 for every 10 c.c. The tubes are kept at a temperature of about 

 40 C., when the degree of dilution is noted at which the albumin is 

 still dissolved. The greater the degree of dilution at which this 

 occurs, of course the greater is the amount of pepsinogen that is, 

 of pepsin present. 



Chymosin. Chymosin, or rennin, according to the researches of 

 Glassner, is formed only in the glands of the fund us, and, as in 

 the case of pepsin, is secreted in the form of a pro-enzyme, which, 

 like the pepsinogen, is then transformed into the corresponding fer- 

 ment by the hydrochloric acid of the gastric juice. It is to be 



