1881.] and Proteolytic Activity of Pancreatic Extracts. 151 



Temperature. Achromic point reached in 



3—5° C 36 minutes. 



10 18 



15 12 



20 8 



25 6 



30 5 



40 5 



45 5 



50 7 



55 10 



60 40 



65 Very slow action. 



70 No action. 



These results, thrown into the form of a curve, are shown in the 

 subjoined diagram. The ordinates indicate the diastasic value, or D, 

 as calculated by a method to be presently explained ; the abscissae 

 represent the temperatures. 



Curve illustrating the effect of temperature on the action of pancreatic diastase, 



Mode of 'proceeding. — In testing the activity of a sample of pan- 

 creatic extract, it was found on the whole more convenient to operate 

 on a fixed quantity of the standard mucilage, and to vary the quantity 

 of extract added to it, than to proceed contrariwise. The bulk of 

 liquid operated on was thus kept constant. The ordinary proceeding 

 was as follows : 10 cub. centims. of the standard mucilage were mixed 

 in a beaker with 90 cub. centims. of water. The mixture was then 

 warmed to 40° C, or at least to some point well within the range 

 of indifferent temperature extending from 30° to 45°. This was done 

 in order to eliminate the disturbing influence of temperature. The 

 next step was to add the determined quantity of the extract to be 

 tested to the diluted mucilage, and to note the exact time. Then, at 

 short intervals, a drop of the enzymosing liquid was placed on a white 

 slab, or plate, with a drop of the iodine solution. The time and result 



VOL. XXXII. M 



