44 VELOCITY OF REACTIONS 



acid. Its optimum lies at a hydrogen-ion concentra- 

 tion of about io" 2 at the beginning and 6-io" 2 after 

 forty-eight hours. This probably depends upon the 

 binding of the hydrochloric acid by the formation of 

 peptone. The action of the acid probably depends 

 upon the circumstance that the salt of albumen with 

 an acid is more easily digested than the albumen 

 itself. A great excess of acid diminishes the activity 

 of the enzyme, probably by its decomposition. In 

 this way the presence of an optimum is easily 

 understood. 



Bayliss has investigated the process of tryptic 

 digestion. In this case an excess of base is 

 necessary for the reaction. His figures indicate 

 that digestion by means of trypsin proceeds in a 

 manner analogous to the peptic one ; the process 

 is therefore probably a monomolecular one. The 

 following little table from Madsen's and Walbum's 

 investigations prove the validity of the ^/-law in 

 this case as well as for peptic digestion. Here t is 

 the time which, at a given temperature, is necessary 

 for reaching a certain degree of digestion, charac- 

 terized by a corresponding degree of liquefaction of 

 the gelatinous jelly, when the concentration q of the 

 enzyme is used. 



According to the ^/-rule, the half quantity of 

 enzyme needs the double time for producing the 

 same effect as the whole quantity, and so forth. 



"Table 



