100 MASS. EXPERIMENT STATION BULLETIN 175. 



These results show that the catalase activity varies somewhat even in 

 healthy plants, dependent upon age and also, apparently, on the general 

 condition of the plant. It shows clearly, also, that in plants of approxi- 

 mately the same age the catalase activity varies somewhat between plants 

 with dark green leaves and those with light green leaves. 



Even on the same plant tliis holds true, as can be seen from the results 

 tabulated below. 



Table VII. — Catalase Activity of Light and Dark Leaves from Same Plant. 



[Plants nearly mature; procedure as in Table VI.] 



An, examination and determination of the catalase activity in diseased 

 leaves shows that the amount of oxygen developed is relatively much less 

 than in the case of healthy leaves. In the table below are given some of 

 the results obtained from diseased leaves. In these experiments the leaf 

 tissue was used without reference to the light and dark areas of the in- 

 dividual leaf. It is significant that the activity is very much less than in 

 healthy leaves. All the plants used in this series were badly diseased. It 

 should be stated that in apparently mild cases of the disease the variation 

 from the normal catalase content was not so great. The results shown 

 here can hardly be compared with those given in Table VII., as the plants 

 were not in some cases of the same age, nor were they grown at the same 

 time. 



Table VIII. — Catalase Activity in Diseased Leaves. 



[Plants badly diseased; procedure as in Table VI.] 



