JOHN H. NORTHROP 



491 



albumin solution has been followed by means of the conductivity. 

 The total change was no reciprocal ohms. The figures have been 

 calculated to the basis of 1,000. The results show that the equations 



TABLE VII. 

 Rate of Hydrolysis. 

 Substrate = 2.0 per cent egg albumin solution, pH 2.0, = 10.0 units of pep- 

 tone per cc. when completely hydrolyzed (from Table III). 

 Pepsin = 0.02 per cent = 0.2 units per cc. 

 Temperature 38°C. A = 1,000. 



fit the experimental results almost exactly as was predicted from the 

 derivation. The decline in the value of the constant near the end of 

 the reaction of equation (6) is due to the fact that the changes in 

 conductivity of the solution do not accurately represent the digestion 

 at the end of the experiment.^^ It will be shown later that, when 



^^ It has been shown in another paper in this Journal (Northrop, J. H., J. 

 Gen. Physiol., 1919-20, ii, 475) that the destruction of pepsin under the condi- 

 tions of this experiment is so slight as to be negligible. The decrease in the 

 rate of reaction cannot be ascribed to this cause. 



