MOSAIC DISEASE OF TOBACCO. 



101 



In the next table will be found a comparison of the results of catalase 

 activity in healthy and diseased leaves from plants grown at the same 

 time and under identical conditions. The plants were inoculated artificially 

 in as uniform a manner as possible. 



Table IX. — Catalase Activity in Leaves of Healthy and Diseased Plants 



of Same Age. 



[Procedure as in Table VI.] 



Leaves. 



Number of 

 Determina- 

 tions. 



Cubic Centi- 

 meters of 

 Oxygen 

 developed 

 (Average). 



Diseased, 

 Healthy, 



52.3 

 119.0 



The values here obtained simply substantiate those given in preceding 

 tables, but in addition allow of a direct comparison. 



The leaf tissue was used in the preceding experiments without regard 

 to the light and dark green patches on the individual leaf. 



It was thought that an examination of the light and dark green areas 

 of individual leaves of mosaicked plants might give a clue as to whether 

 the activities of the catalase were inhibited in one or both of these areas 

 in comparison with a leaf from a healthy plant of approximately the same 

 age and color. 



It was found that the catalase activity of the dark green areas ap- 

 proached that of the normal leaf of the same color, while the catalase 

 activity of the light green areas was much below normal, even in the case 

 of a Hght green normal leaf being used for comparison. The values 

 obtained are given in Table X. 



Table X. — Catalase Activity in Diseased Leaves. 



[Comparison of light and dark green areas; procedure as in Table VI.] 



Diastase. — It is a well-known fact that diastase is intimately con- 

 nected with metabolism in the leaf in practically all clilorophyll-bearing 

 plants, as well as in many of the fungi, and the relations of the activities 



