28o 



U. SUZUKI. 



poisonous hydrogen peroxid that may be formed as a by- 

 product in the process of respiration. I thought it of some 

 interest to investigate whether there is an abnormal increase 

 of this enzym ir, the diseased mulberry leaves. I took at first 

 I gram of air dried and powdered leaves, mixed with 30C.C. 

 water and added 5 c.c. of freshly prepared hydrogen peroxid 

 of 2 — 5% strength. The development of oxygen gas was here 

 so energetic that I used in the following tests only o. 1 gram 

 of the dried leaves. Temperature and the reaction of the sample 

 have much influence upon the development of oxygen, 30 — 40 G C 

 and neutral or slightly acid reaction being preferable. 1 Great 

 care was taken to have exactly the same conditions in all tests. 

 The following table shows the results. 



1. Akagi leaves gathered on Oct. 5, 0.1 g. air dry. 



Minutes. 

 5 



10 



20 

 30 



Morning. 

 6 o'clock. 



Healthy. Diseased, 

 (c.c. Oxygen.) 



3-4 



6.8 



2.0 



42 



9.0 

 11. 2 



Noon. 

 12 o'clock. 



Healthy. Diseased, 

 (c.c. Oxygen.) 



27 

 40 

 8.0 

 10 7 



3-7 

 6.8 



"■5 

 14.5 



Evening. 

 6 o'clock. 



Healthy. Diseased, 

 (c.c. Oxygen.) 



2-5 

 4-7 

 9.2 

 1 1.1 



4.0 

 6.6 

 1 1.2 

 14.0 



2. Roso leaves, fresh 0.5 grams. Oct. 21. 



Minutes. 



Healthy. 



Diseased. 



5 



7.0 c c. 



2. 



10 



10.0 



4- 



20 



145 



62 



30 



16.0 



7-7 



1 It is to be mentioned that by frequent shaking, the development of oxygen is very 

 much accelerated. In this experiment, the mixture was shaken on the addition of 

 hydrogen peroxid and afterwards left fo itself. In some cases the mixture was shaken 



at the last reading. 



