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U. SUZUKI. 



materials in the roots is not only the result of the disease but 

 also the principal cause of its further development. 



Abnormal increase of oxidase and peroxidase in the diseased 

 leaves is one of the most striking phenomena. At the same 

 time, we observe that the migrationof starch and nitrogen- 

 ous compounds is remarkably retardedin the diseased trees. 

 According to the investigation of Woods, it is very 

 probable that the oxidizing enzymes not only destroy chloro- 

 phyll but also exert an inhibiting action upon the diastatic 

 and proteolytic enzyme and thus may become one of the prin- 

 cipal causes of the retardation of migration power and consequ- 

 ently of the retardation of growth in the diseased plants. A second 

 cause has been found recently by Prof, Miyoshi in the insufficient 

 development of the transportation tissues. These phenomena 

 are closely analogous to those of the mosaic disease of tobacco 

 and the variegation or albinism of other plants, and further 

 with the parasitic diseases caused by fungi and insects. In the 

 latter case also the abnormal production of oxidizing enzyms and 

 the retardation of starch migration are the principal phenomena. 

 Although we have no definite opinion on the cause why oxidizing 

 enzyms are produced in such abnormal quantities in the diseased 

 plants, yet the partial starvation of the cells seems to be the 

 probable cause of it. As the cutting of mulberry plants in the 

 growing season causes deficiency of nutriments for the new 

 developing shoots, this seems to afford a new and strong support 

 for the above assumption. 



Further investigations on this mulberry disease are intended. 



