[Vor. 1 
310 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
cellulose, and, strange to say, Sclerotinia is just as active in this 
respect as Penicillium. Іп many cases the growth was as good 
on the plum cellulose as on the filter-paper cellulose, yet the 
hydrolytie action of the fungi was very much weaker on the 
former medium. No cellulose hydrolysis oceurred where peach 
juice or some soluble carbohydrate, such as glucose, was added. 
It seemed probable at first that a very small amount of glucose, 
or peach juice, or sodium citrate would give the fungus a vigor- 
ous start and thus accelerate its eyto-hydrolytie activity, but 
the quantities of these substances employed was sufficient to 
exert a protective influence, there being a vigorous growth but 
no apparent cellulose hydrolysis. 
The fact that these fungi do not dissolve cellulose, derived 
either from the host or from paper, when other organie nutri- 
ents are supplied, verifies the writer's observation that Sclerotinia 
cinerea does not disintegrate the cell walls of the host tissues. 
Furthermore, the fact that the fungus dissolves paper cellulose 
very readily when it is the only carbohydrate supplied, leads 
one to conclude that the action of the fungus on paper cellu- 
lose in a nutrient solution low in carbohydrates is not neces- 
sarily a good criterion for judging the behavior of the fungus 
in the host tissue. In the host tissue there may be a form of 
cellulose different from that of paper, and it is furthermore 
very evident that there is present in the fruit an abundance of 
organie material evidently operating in a protective manner. 
The fungus fails to produce cytolytic enzymes when grown on 
plum or paper cellulose to which peach juice or even a very little 
sugar has been added, but acts vigorously on paper cellulose 
to which no organic nutrient has been added. It is rather | 
peculiar that both fungi aet much more readily on paper cellu- 
lose than on cellulose isolated from the fruits which are natural 
hosts for these organisms. 
Sclerotinia cinerea grows very slowly when first transferred 
to a nutrient medium poor in soluble carbohydrates, very few 
spores and no aérial mycelium being produced. At the expira- 
tion of a week or more one may observe that the fungous myce- 
lium has penetrated the surface layer of the agar, and at the 
expiration of two to three weeks, in ease the fungus is growing 
on paper-cellulose agar, a clear translucent ring may be observed 
