1908.] 



PUBLIC DOCUMENT — No. 33. 



143 



Some leaves of a plant badly affected with the mosaic disease 

 were treated in the manner previously described. In appear- 

 ance the pulp and the filtrate were lighter in color than in the 

 case of the normal plants, due probably to the fact that there 

 was less chlorophyll in them than in the normal specimens. 



When allowed to react with hydrogen peroxide (H 2 2 ) it 

 was found that both forms of catalase « and /3 were present, as 

 oxygen was evolved from the solutions in sufficient amounts 

 to be measured. 



Since it was obvious that both a and /3 catalase were present 

 in healthy and diseased plants, it was decided to take a weighed 

 amount of healthy and diseased leaves and measure the oxygen 

 evolved in a given time from a solution containing a known 

 percentage of hydrogen peroxide. For this purpose 5 grams 

 of healthy leaves were treated in the manner previously de- 

 scribed, and the oxygen given off was carefully measured by 

 an ordinary water displacement method. The soluble catalase 

 was not precipitated, however, but the filtered juice was added 

 in each case directly to the solution of hydrogen peroxide. 

 The strength of solution used was as follows : — 



To 120 cubic centimeters of pure distilled water was added 20 

 cubic centimeters of commercial hydrogen peroxide, making a 

 solution in the proportion of 1:6. The pulp containing the 

 insoluble catalase was added to this solution, and the amount 

 of oxygen given off carefully measured. This was done both 

 for healthy and diseased plants. The results obtained for the 

 insoluble or « catalase are given below : — 



Table showing Oxygen developed by Catalase in Healthy and Diseased Leaves. 



From these results it may be safely stated that there is cer- 

 tainly a lack of insoluble catalase in leaves of the tomato which 

 are affected with the mosaic disease. 



To a w T atery solution of hydrogen peroxide of the same pro- 

 portion as used above, i.e., 1 : 6, was now added the soluble 



