158 Dr. W. Roberts. Estimation of the Amylolytic [May 5, 



gressively retarded rate. From the numerous experiments which were 

 performed with a view of elucidating this point, I arrived at the con- 

 clusion that when the onset point of the metacasein reaction fell 

 between 3 and 6 minutes the inverse time-rate gave a reliable basis of 

 calculation, but not beyond these limits. 



Temperature. — Tryptic enzymosis is exceedingly sensitive to tempera- 

 ture. The action of trypsin on milk increases in energy from zero to 

 60° 0. Above this point there is a rapid fall, and the action is finally 

 arrested between 75° and 80° C. There is not, as with diastase, any 

 range or platform of indifferent temperature. The following table 

 exhibits the degrees of activity from 10° to 80°. In order to obtain 

 the utmost uniformity of results, the quantities of pancreatic extract 

 employed were so adjusted as to bring the incidence of the metacasein 

 reaction within a period ranging from 4 to 6 minutes. 



Table VII. 



Showing the effects of temperature on tryptic enzymosis. 



The quantity of milk employed in each experiment was 50 cub. 

 centims. diluted with water up to 100 cub. centims. In the fourth 

 column the degree of tryptic activity, or T, is calculated by a method 

 to be presently explained. 



Temperature. 



Quantity of pancreatic 

 extract employed. 



Onset point of the 

 metacasein reaction. 



Tryptic value — 

 or T. 



10° C. 



6 '0 cub. centims. 



5 minutes. 



8 



15 



4-0 





12 



20 



3 



4 „ 



21 



30 



1-0 



H » 



45 



40 



0-6 



H „ 



76 



50 



0-4 





119 



60 



0-3 



H » 



150 



65 



0-4 



5 



125 



70 



0-8 



4 „ 



78 



75 



2-0 



6 



21 



80 



4-0 



No action. 







In the subjoined diagram these results are thrown into the form of 

 a, curve. The ordinates indicate the degrees of tryptic activity (or T), 

 and the abscissae indicate the temperatures. 



In another series of experiments the effect of temperature was 

 gauged by the length of time required to reach the onset or the 

 vanishing point of the metacasein reaction when constant quantities 

 of pancreatic extract were used. The results obtained in this series 

 are tabulated in Table VIII. In the first set the onset point of the re- 

 action was taken as the index of tryptic activity ; in the second set 



