THE FRACTIONAL METHOD OF GASTRIC ANALYSIS 223 



series of six tubes; 1.0, 0.9, 0.7, 0.5, 0.2, 0.0. Make the measure- 

 ments by means of a 1 c.c. pipette graduated in 0.01 c.c. Now 

 rapidly introduce the unboiled, diluted juice in the following 

 increasing volumes (c.c.) in order: 0.0, 0.1, 0.3, 0.5, 0.8, 1.0. 

 Each tube now contains a total volurne of 3 c.c. and a total acidity 

 of 0.2 per cent hydrochloric acid. Shake each tube thoroughly 

 and place them at 50 to 52 C. for fifteen minutes or at 35 to 36 C. 

 for one hour. Examine the series of tubes at the end of the diges- 

 tion period and select that tube which contains the smallest quan- 

 tity of gastric juice and which shows no turbidity. The volume 

 of the juice used in this tube is taken as the basis for the calcula- 

 tion of the peptic activity. 



Calculation. The peptic activity is expressed in terms of 1 

 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 

 1 c.c. of the globulin solution in the proper experimental time 

 interval (fifteen minutes or one hour according to temperature) 

 the peptic activity would be expressed as follows: 



(1^0.5)X5=10 (peptic activity). 



According to this scale of pepsin units 10 may be considered 

 as " normal " peptic activity. These units are about 1/10 as 

 large as those expressed by the Jacoby-Solms scale. 



(3) Givens' Modification of Rose's Method. 1 The gastric 

 contents are strained through cheesecloth. Two c.c. are measured 

 by means of an Ostwald pipette into a 25 c.c. stoppered volumetric 

 cylinder, and diluted to the mark with distilled water. Into 

 each of seven small test-tubes (1X10 cm.) is measured, with an 

 Ostwald pipette, 1 c.c. of a 0.25 per cent filtered pea globulin in 

 10 per cent sodium chloride solution. To each tube is added 1 c.c. 

 of 0.6 per cent hydrochloric acid, also by means of an Ostwald 

 pipette. The tubes are allowed to stand about five minutes, until 

 the maximum turbidity develops. To the first five, distilled 

 water is added as follows: To the first, 0.9 c.c.; to the second, 

 0.8 c.c.; to the third, 0.7 c.c.; to the fourth, 0.6 c.c.; and to the fifth, 

 0.2 c.c.; to the sixth and seventh, none. Then there are rapidly 

 added to each test-tube the following amounts of the diluted 

 (1:12.5) gastric juice; to the first, 0.1 c.c.; to the second, 0.2 c.c.; 

 to the third, 0.3 c.c.; to the fourth, 0.5 c.c.; to the fifth, 0.8 c.c.; 

 1 Givens: Hygienic Lab. Bull., August, 1915, 101, 71. 



