l68 U. SUZUKI. 



having left for Europe, Prof. M. Miyoshi and Mr. K. Fujii were 

 appointed to fill the vacancies. Mr. Ichikawa having recent- 

 ly returned was again added to the board. 



From the beginning the writer took up the chemical side of 

 the question. And as a preliminary step, comparative chemical 

 analyses of healthy and attacked plants were made to ascertain 

 the differential character of the latter, and as the writer believes 

 himself to have been fortunate enough to discover the cause 

 which induces the disease, he has decided to publish the result 

 in order that others engaged in seeking for a remedy may avail 

 themselves of it. The present paper is reproduced with the per- 

 mission of the board from a report originally presented to it, and 

 contains only the results obtained by myself. It must, however, 

 be stated that most of the field experiments cited in this paper 

 were conducted by Mr. Ichikawa for several years, either alone 

 or in conjunction with the other members of the board. I must 

 also note my indebtedness to other members of the board for 

 supplying me with informations regarding the parasites, by 

 which my view has directly or indirectly been strengthened. 



There is no means of ascertaining the first origin of the 

 disease in question, but it is probably not older than twenty or 

 thirty years. As stated before, the disease has become especial- 

 ly malignant since over ten years ; and up to the present time, it 

 has been reported from nearly all parts of the country. The 

 damage has been particularly great in Oita, Fukuoka, Kuma- 

 moto, Tottori, Shimane, Aichi, Shizuoka, Yamanashi, Tokyo, 

 Saitama, Fukushima, and Gumma, and in some localities entire 

 farms have been attacked by the disease, and the owners have 

 been compelled to give up the cultivation of the mulberry. Lo- 

 calities where silkworm culture has recently come into practice 

 appear to have a special propensity to the disease, and the newly 

 started industry is very apt to receive a serious check from it. 

 The entire annual damage for the whole country would doubtless 

 amount to several millions of yen ; no wonder that the public has 

 been awakened to it. 



The different varieties of the mulberry are unequally liable 

 to the disease. Generally speaking, those varieties which are 

 esteemed for the quality of the leaves, large crop, and rapid 

 growth have a greater propensity to the disease, while those 

 which are charactarized by hard leaves, less sap, and slow 



