AND VELOCITY OF REACTION 89 



but rather that the length of albumin dissolved was nearly directly 

 proportional to the concentration in enzyme. On the other hand, 

 Borissow, using the Mett's method, found that pepsin in its action 

 in dissolving coagulated egg-white obeyed Schiitz's law. 



In the writer's own experience with the Mett's method, and 

 active preparations of commercial pepsin of various origin, the 

 Schiitz's law is by no means followed. With stronger solutions, 

 the length of egg-white dissolved off is approximately equal ; as 

 the concentration in enzyme is diminished, the intensity of action 

 falls off very slowly, much less than in direct linear proportion, 

 but there is no period at which the Schiitz law is closely obeyed, 

 and with very dilute solutions the length of egg-white is so little 

 as not to be accurately measurable, so that the method is useless 

 for testing very dilute solutions. Even in stronger solutions the 

 slowness of fluid diffusion in the narrow tubes tending to accumu- 

 lation of products of digestion at the active interface, and the 

 irregularity with which the column of egg-white is eaten away, 

 form grave objections to the employment of this oft-described 

 method. 



In the case of the experiments, such as those of J. Schiitz and 

 Huppert and Schiitz, in which the activity is determined from 

 the amount of secondary albumose formed in equal times with 

 varying concentration of enzyme, the objections of Bredig de- 

 scribed above must be taken, for here the concentration of the 

 substratum is altering all the time of the experiment, and the per- 

 centage of conversion and concentration of products of reaction 

 will be greater in the solutions containing more concentrated 

 enzyme, and hence there will be a greater factor of retardation 

 in the more concentrated solutions. 



That this is the case is seen from the extension of the Schiitz 

 law which is advocated by Huppert and J. Schiitz. These 

 authors give as a result of their experiments the formula, 

 S = Jc A ^/ 1 . p . s, in which S = the amount of secondary albumose 

 formed, Jc = the reaction constant, t = the time of experiment, 

 p = the concentration in pepsin, and s = the concentration in acid, 

 provided this does not exceed O2 per cent. Now such a formula 

 cannot express more than an empirical coincidence throughout 

 a certain short range of experiment, for apart from the impro- 

 bability of exactly the same law being followed in the case of three 

 such different factors as time, enzyme concentration, and acid 



