272 ON A ^' EW CANKER-DISEASE OF PRUNUS YEDOENSIS, etc. 
ascospores of this causal fungus with cultures of the sterilized twigs. Speak- 
ing generally, the present fungus has the tendency to form the creeping 
mycelium rather than the aerial one. I can advocate, therefore, the cultural 
characters, such as the color of the mycelium and of the spore-masses, or 
the characteristic hyphal growth, as a means of distinguishing this species 
from the other very closely related species of Valsa. The chief cultural 
differences of our three species of Valsa are as follows : 
fi) In general, the mycelial growth of Valsa Mali is comparatively 
poor in artificial cultures, while the growth of Valsa Paulowniae is most 
vigorous, and our present fungus shows an intermediate growth between the 
above two species. 
(2) For most cases the growth of the aerial mycelium is most vigorous 
in cultures of Valsa Paulowniae, compared with cultures of the other two. 
(3) The mycelium of the present fungus on cultures turns yellow, green- 
ish yellow or light brown in color with age, especially on fruits-juice-agar 
or fruits-juice-gelatine. But the white color of mycelium is retained for a 
long time in Valsa Mali. In Valsa Paulowniae the mycelium shows, after a 
while, light flesh or light pink color on the same medium. 
(4) The color of the masses of pyenospores is a most conspicuous 
characteristic to distinguish our species from the others. The color of the 
spore masses in the three fungi is as follows: — 
Valsa Mali Mivabe et Yamada Yellow. 
Valsa Paulowniae Miyabe et Hemmi Greenish black. 
Valsa sp. on Prunus Red or flesh color. 
c. Cultural Characters on Different Media. 
(1) Sterilized Twigs. 
On all sterilized twigs of Prunus ycdoensis, Prunus Mumc, Prunus Per sica 
and Pirns Malus, the causal fungus seems to grow. On the twigs of Pirns 
Malus, however, the growth of the hyphae was rather poor, and only a few 
stromata and spores had developed in most cases. On all of them, the fungus 
