2 9 4 
ON A NEW CANKER-DISEASE OF PRUNUS YEDOENSIS, etc. 
12. Systematic Position and Nomenclature of the Causal Fungus. 
From the morphological characters, we may easily recognize our fungus 
to be a species of Valsa. It has pyenidia of the Cytospora type. 
The genus Valsa was first described by Fkies(i849) 1f °; and then Nitschke 
( i 867) "°, who made a new family Valsaccac out of it, studied the genus ex- 
haustively in his work "Pyrenomycetes Germanici". In Engler and Prantl's 
"Die Natürlichen Pflanzenfamilien", Lindau (i897) lö) divided the genus into 
ten subgenera. Most of these subgenera were founded by Nitschke and 
endorsed by Winter (1887) ;in and Schröter (1908) '-' !) . They are distin- 
guished from one another chiefly by the construction of the stromata. In 
Saccardo's "Sylloge Fungorum", however, only two subgenera, Euvaha and 
Leucostoma, are treated as belonging to this genus and all other subgenera 
were raised to independent genera. On the ground of the morphological 
characters of the stromata, I have come to the conclusion that the present 
fungus is a species of Etivalsa. Nitschke divided this subgenus further into 
two groups, Monostichae and Circinatae, and our fungus belongs to the latter, 
which corresponds to Macrosporae in Saccardo's system. 
Up to the present time, more than fifteen Valsa and still more Cytospora 
were found both saprophytically and parasitically on the twigs and branches 
of the various species of Prunns in the world; but most of them differ in their 
systematic position and also in other essential characteristics from our fungus. 
With some of them, owing to the brevity of their descriptions, I could 
scarcely make any comparison with our causal fungus. 
Valsa leucostoma (Pers.) Fr. which causes the disease of many drupace- 
ous trees, known as "die back", throughout Europe, Australia and America, 
not only has the "conceptaculum" between the stroma and the host tissue, 
but differs also from our present fungus in many other essential points, as 
shown in the following table: — 
