170 PHYSIOLOGICAL CHEMISTRY 



same gastric juice. One of these tubes should show a digestibility equal to that 

 of the standard tubes. For example the tube coagulated at 88 C. may show the 

 proper digestibility. Then the new series of tubes should be made in the same man- 

 ner as this one, that is introduced at 88 C. The tubes thus prepared should be 

 again checked up with the standard to see that no mistake has been made. 



(2) Rose's Modification 1 of the Jacoby-Solms Method. 2 Dissolve 0.25 gram of 

 the globulin of the ordinary garden pea, 3 Pisum sativum, in 100 c.c. of 10 per cent 

 sodium chloride solution, warming slightly if necessary. 4 Filter and introduce i c.c. 

 of the clear nitrate into each of a series of six 6 test-tubes about i cm. in diameter. 

 Introduce into each tube i c.c. of 0.6 per cent hydrochloric acid and permit a period 

 of about five minutes to elapse for the development of the turbidity. Make a 

 known volume of the gastric juice (5-10 c.c. is sufficient) exactly neutral to litmus 

 paper with dilute alkali; and record the volume of the alkali so used. If acid 

 metaprotein precipitates, filter it off; if there is no precipitate proceed without 

 filtration. Dilute the clear neutral solution with a known quantity of distilled 

 water (usually 5 volumes) making proper allowance for the volume of alkali used in 

 the neutralization. Boil 5-10 c.c. of the diluted juice, filter and add the following 

 decreasing volumes (c.c.) to the series of six tubes: i.o, 0.9, 0.7, 0.5, 0.2, o.o. Make 

 the measurements by means of a i c.c. pipette graduated in o.oi c.c. Now rapidly 

 introduce the unboiled, diluted juice in the following increasing volumes (c.c.) in 

 order: o.o, o.i, 0.3, 0.5, 0.8, i.o. Each tube now contains a total volume of 3 c.c. 

 and a total acidity of 0.2 per cent hydrochloric acid. Shake each tube thoroughly 

 and place them at 5o-52C. for 15 minutes or at 35-36C. for one hour. Examine 

 the series of tubes at the end of the digestion period and select that tube which 

 contains the smallest quantity of gastric juice and which shows no turbidity. The 

 volume of the juice used in this tube is taken as the basis for the calculation of the 

 peptic activity. 



Calculation. The peptic activity is expressed in terms of i c.c. of the undiluted 

 juice. For example, if it requires 0.5 c.c. of the diluted juice (five-fold dilution) to 

 clear up the turbidity in i c.c. of the globulin solution in the proper experimental 

 time interval (15 minutes or one hour according to temperature) the peptic activity 

 would be expressed as follows: 



(i-5-o.s)X5 = i (peptic activity). 



1 Rose: Archives of Internal Medicine, 5, 459, 1910. 

 2 Solms: Zeitschriftfur klinische Medizin, 64, 159, 1907. 



3 The globulin may be prepared as follows: "The finely ground peas, freed as much as 

 possible from the outer coating, are repeatedly extracted with large quantities of 10 per cent 

 sodium chloride solution, the extracts combined, strained through fine bolting-cloth, and 

 allowed to stand over night in large cylinders to deposit insoluble matter. The supernatant 

 fluid is siphoned off and saturated with ammonium sulphate. The precipitate of albumin 

 and globulin is filtered off, suspended in a little water, and dialyzed in running water for 

 three days, until the salt has been removed, and the albumins have been dissolved. The 

 globulins are filtered off and washed two or three times to remove the last trace of albumins. 

 To purify further, the precipitate is extracted with 10 per cent sodium chloride solution, and 

 filtered until perfectly clear. The resulting solution is neutralized to litmus paper by the 

 cautious addition of dilute sodium hydroxide, and again dialyzed in running water for three 

 days to remove the salts completely. The precipitated globulins are then filtered off and 

 dried on a water-bath at 4oC. During the entire process of separation the proteins should 

 be preserved with a mixture of alcoholic thymol and toluol." This dried globulin is used in 

 the clinical procedure. 



4 This solution may be preserved at least two months under toluene. 



6 A longer series of tubes may be used if desired. However, experience has shown that 

 a series of six ordinarily affords sufficient range for all diagnostic purposes. 



