JOHN H. NORTHROP 



493 



trj^sin used. The table also shows that this ratio is constant if the 

 first part of the curve is used but later decreases {i.e., the 5 per cent 

 gelatin is hydrolyzed relatively more and more rapidly), as would be 

 expected, since after any appreciable amount of the gelatin is hydro- 



TABLE I. 



Time Required for Eqtial Percentage Hydrolysis of 1 and 5 Per Cent Gelatin Solu- 

 tions When Compared with (o) 1 Unit of Trypsin, and {b) 10 Units of Trypsin. 



Complete hydrolysis of 1 per cent gelatin = increase in conductivity of 0.5 X 

 10"^ reciprocal ohms. 



TABLE n. 



Change in Conductivity after Equal Time Intervals. 



lyzed the two concentrations are no longer as 5:1 but as 5-a:l-a. 

 As soon as a becomes appreciably large compared to 1, the ratio 

 will evidently increase, as a increases. The ratio of the time required 

 to cause a given change will therefore decrease. This method may, 



