360 U. SUZUKI. THE MULBERRY DWARF TROUBLES. 



As the general result of these comparisons the following 

 inferences can be drawn : 



1) Oxidase and peroxidase are present in larger quantities 

 in the diseased leaves, which generally yielded a reaction 3-5 

 times more intense than the healthy ones. Only a few excep- 

 tions were observed with leaves collected at the beginning of 

 May. No exceptions, however, were found with the leaves of 

 the new shoots developed after cutting. Such leaves exhibited 

 a very pale and yellowish appearance, probably due to the 

 action of the larger amount of oxidizing enzymes on the 

 chlorophyll. 



As I have already shown, the diseased leaves of the new 

 shoots coming after cutting in the growing season, are always 

 poorer in nitrogenous compounds, compared with those leaves 

 gathered before cutting or in the late autumn. We may there- 

 fore infer that the production of oxidases has a very intimate 

 relation to the deficiency of nutrients, especially of nitrogenous 

 compounds in the plant cells. Further the fact that the diseased 

 plants very often recover when they are left without cutting, 

 naturally leads us to suppose a close relation of oxdizing enzymes 

 with the disease. 



2) Peroxidase is always much more prevalent than oxidase 

 in the diseased leaves. 



3) As to catalase no safe conclusion can be drawn, 

 although in the majority of cases it seemed to be present in 

 slightly greater quantities in the diseased leaves. 



