A New Species of Hymenomycetous 



Fungus Injurious to the 



Mulberry Tree. 



by 



Nobujirö Tanaka. 



With Plates XXIV— XXVII, 



In Japan the mulberry tree has been widely cultivated, from time 

 immemorial, for rearing: silkworms. Althouo'Ii the methods of its 

 culture have much improved, yet its diseases, especially those caused 

 by fungus parasites, have been overlooked even by skilful cultivators. 

 The chief reason f )r general neglect ivgarding these points is the 

 want of accurate knowledge of the nature and biology of fungi. 

 One of the most serious diseases of this kind is that which is known 

 under the name of " Mompa-byö."* This disease has produced much 

 distress at various intervids for about eight years, in the experimental 

 farm of the Agricultural College at Komaba, Tokyo. Some dis- 

 tin^fuished biologists and au'riculturists have investifrated its nature, 

 and stated that it was due to the ravages of a sterile mycelial stage 

 of a fungus of some other form, but its true nature has never yet been 

 fully explained. I have lately had the good opportunity to study 

 this disease under the direction of Prof. R. Yatabe. The object of 

 this paper is to deal with one or two of the unsettled questions 

 regarding it, namely, the morphology of the perfect condition of the 

 fungus which causes the disease, and its systematic position. 



* Mompa, a kind of nappy cotton-cloth ; byö, disease. 



