636 



CATALASE ACTION 



begin. The curves made on millimeter paper by the automatic 

 writer could be calculated immediately. The advantages of this 

 method are: (1) accurate determination of the beginning and the 

 end of the reaction and of the reaction time; (2) accurate determination 

 of the strength of the peroxide; (3) accurate and quick measurement 

 of reaction velocities in very short intervals; e.g., every 5 seconds. 



Fig. 1 is an autogram showing the effect of the action of 3 cc. of 

 3 per cent peroxide on 3 gm. of ground Ulva thallus in a slightly 

 alkaline medium. The ordinates are pressures in millimeters. The 

 abscissae are 14 seconds per millimeter. We used Braun-Knecht- 

 Heimann's c. P. 3 per cent peroxide which contains still acet^nilide 

 and acid. We neutralized the peroxide with 0.1 n sodium carbonate 

 solution. 



Seconds 



Fig. 1. Autographic record of the effect of 3 cc. of 3 per cent peroxide 

 on 3 gm. of fresh, ground thallu? of Ulva. 



The activity of the catalase in Ulva is not very great. If we 

 compare it with the activity of hemp leaves, we get 



3 gm. of ground Ulva 4 cc. of H2O2 + 0.4 cc. of 0.1 N Na2C03 



Average K = 521 X 10"^ 



3 gm. of ground hemp leaves. . .4 cc. of H2O2 + 0.4 cc. of 0.1 N Na2C03 

 Average K = 7,020 X 10"^ 



The hemp is about fourteen times stronger than the alga in its cata- 

 lytic activity. 



Before giving a detailed description of the experiments, we wish 

 to emphasize the fact that, however simple the method described 

 may seem, we met with great difficulty in carrying it out. We 

 discarded most of our experiments because we were not sure of their 



