224 METHODS FOR THE ANALYSIS OF GASTRIC JUICE 



to the sixth, 1.0 c.c.; and to the seventh, 1.0 c.c. of the diluted 

 juice boiled. These measurements can be accurately made with 

 a 1 c.c. pipette graduated in 0.01 c.c. All tubes are then immersed 

 for fifteen minutes in a water-bath at 50-52 C. At the end of 

 this time, the tube is selected which is clear and contains the least 

 amount of diluted gastric juice. Upon this basis, the peptic activity 

 is calculated as the number of cubic centimeters of 0.25 per cent 

 globulin digested by 1 c.c. of undiluted gastric juice. For example, 

 if tube 2 containing 0.3 c.c. of a 12.5 times diluted juice be clear, 

 then the result would be expressed : 



Peptic activity = (1 -^ 0.3) X 12.5 =41.2. 



Ordinarily this scheme of seven tubes is used, though it is not 

 a rule. If the free acidity be high, sometimes a dilution of 1/25 

 is made. The number of tubes used will depend upon the accuracy 

 desired. 



(d) Determination of Tryptic Activity. Trypsin is not a 

 gastric enzyme, but occurs in the pancreatic juice. In case of 

 regurgitation of intestinal contents through the pylorus trypsin 

 would be passed into the stomach. This regurgitation is doubtless 

 of frequent occurrence and may even be a normal mechanism by 

 which gastric acidity is regulated. Trypsin is, therefore, generally 

 present in the contents of the normal human stomach. Inasmuch, 

 however, as trypsin is destroyed by the pepsin-hydrochloric acid 

 of the gastric juice, determinations of this enzyme must be carried 

 out immediately after aspirations of the gastric contents, particu- 

 larly where the acidity of the latter is* high. 



Spencer's Method. 1 (a) Prepare five reagent tubes, Nos. 

 1, 2, 3, 4, and 5; more if desired., 



To tubes 1 and 2 add 0.5 c.c. of gastric contents (filter if cloudy). 



(6) To tubes 2, 3, 4, and 5 add 0.5 c.c. of distilled water. 



(c) From tube 2 remove 0.5 c.c. of its mixed contents and add 

 to tube 3. Mix thoroughly and add 0.5 c.c. from tube 3 to tube 4. 

 Ptepeat for tube 5. 



We now have dilutions of gastric contents of 1, 1/2, 1/4, 1/8, 

 and 1/16. 



(d) To each tube add one drop of phenolphthalein solution 

 (phenolphthalein 1 gm., alcohol (95 per cent) 100 c.c.); then add 



1 Spencer: Jour. Biol. Chem., 1915, 21, 165. 



