TAKEWO HEMMI 287 
(1) The fungi can use tannic acid, at least in a small amount, as food, — 
shown by the blackening of the media through oxidation, and by a more 
luxuriant growth, with a low percentage of the tannic acid added, than in 
the case without it. 
(2) Higher percentages of tannic acid (1.2 °j 0 and above) are detri- 
mental to a vigorous growth of the causal fungus, and finally (8 to 14 %) 
entirely inhibit its growth. 
(3) Different species of the same genus may vary in power of resistance. 
The resistant power of the causal fungus against tannic acid is the highest 
among our three species of Valsa. I agree, therefore, with Cook's opinion 6) 
that some species of fungi are much more resistant to tannin than others, and 
the species which attack the high tannin-bearing plants no doubt possess this 
quality. 
(4) High percentages of tannin have the tendency to retard or inhibit 
the growth of fungi. But the growth of the fungi is frequently increased by 
the use of low percentages of tannin, and in this case the hyphal growth is 
closer than without it. 
(5) In some cases the growth was at first retarded by certain percent- 
ages of tannin, but later became as good or better than on the medium without 
it. 
(6) The formation of spores was stimulated, at least in the case of the 
causal fungus, by low percentages of tannin. 
(7) Citric acid also stimulates the spore formation of this fungus, pro- 
bably rather more than tannic acid. But on the cultures containing tannic 
acid, the time required for fruiting was shorter than on the cultures contain- 
ing citric acid. 
(8) The fruiting of this fungus is not determined by the acidity of the 
medium alone, but it seems to me to be due to a combination of various 
factors that constitute the real cause of the stimulation. 
