Sept.. liur..] T. lU:MMI.— I)n:-HAi'K IHSEASIC OF VAULOWNIA. :\\?, 



Cultural Characters and Parasitism of the Fungus. 



In a saprophytic condition, the fungus in question seems to 

 be ahnost omnivorous. On the sterilized twigs of the host plant, 

 and on the agar and gelatin media containing a fruit-juice, or 

 the decoction of the hostbark, or oat or corn meal, the stromata 

 and the pycnospores are generally produced. But I have not 

 succeeded in producing the ascospore stage in all my cultures. 

 The colour of the pycnospores in masses, produced on cultural 

 media, is greenish black; and it is the most conspicuous charac- 

 teristic of our species by which we can easily distinguish it from 

 other very closely related species of Valsa. 



Speaking generally, the present fungus has a tendency to 

 form the aerial m^-celium rather than the creeping one. The 

 mj'celial growth of Valsa Mali Miyabe et Yamada,^^''^ which 

 is one of the causal fungi of the canker disease of the apple tree 

 in Hokkaido and in the northern Honshu, is comparatively 

 poor in artificial cultures, while the growth of the present fungus 

 is most vigorous. In Valsa japonica Miyabe et Hemmi/^-' which 

 is parasitic on the branches of Prunus yedoensis, the mj'celial 

 growth is intermediate in vigor between the above two species. 

 The mj'celium of the present fungus on the surface of solid 

 cultures turns gradualh' light flesh or light pink in colour with 

 age, conspicuously on a fruit slice and on a fruit juice agar. 



The resistant power of the present fungus against tannic 

 acid is the weakest among the three species of Valsa used in 

 my experiments {Valsa Paulowniae, Valsa AI all, Valsa japonica). 

 In the case of the present fungus, the cultures containing 0.1 9^ 

 or more of tannic acid have the tendenc}' to retard or inhibit 

 the growth of the mycelium and even the formation of the 

 pycnospores. On the contrary, the cultures containing \.2°/o or 

 less of citric acid stimulate to a marked degree the growth of 

 the mycelium. The formation of the pycnospores is stimulated 

 by the addition of 0.8 to 2% of citric acid to the cultures of 

 potato juice agar, in the non-acidulated media of which no 

 p\'cnospores have ever been formed. 



From our observations and experiments, we can conclude 



