292 BOTANICAL GAZETTE [NOVEMBER 
molds were obtained and renewed from week to week. The 
spores used in inoculating the cultures in the experimental work 
were taken from fresh tubes in which the fungus had been grow- 
ing seven to fourteen days. A solid medium made by adding 
128" of agar to a liter of sugar beet infusion was found tobe 
very satisfactory for stock cultures. 
Selection of medium.—The object being to test the effect of 
the deleterious agents on the fungi under as nearly normal con- 
ditions of development as possible, the selection of a suitable 
medium was of primary importance. Many preliminary cultures 
were made with various media, including distilled water, infusions 
of potato, celery, sugar beet, prune, and bean (stems, pods, and 
mature seeds), besides various others compounded from inors 
ganic salts, sugars, asparagin, etc. The results in germination 
and development were very varied. In distilled water Sterig- 
matocystis and Penicillium failed to germinate in 24 hours at 
28° C., and of Botrytis, which did the best of the five forms, but 
40 per cent. germinated in that time. Mycelial development ® 
all was meager, and fruiting generally mil. Very minute Linge 
tities of the deleterious agents were found to inhibit germin® 
tion, but the death-point of the spore was found in the ae 
dichloracetic acid, potassium hydroxid, and cobaltous oe 4 
to be the same as in the medium finally selected. The ge a 
compounded from salts, sugars, etc., were more satisfactory » 
vegetable infusions, however, were superior to all others. ib 
infusion of sugar beet was ultimately chosen as The fe 
whole the medium best suited for the forms used. 4d above 
that, in the case of the three typical poison tione 
the concentration causing the death of the J age pre wa 4 
same, whether the agent was dissolved in distilled " 
beet infusion, is very important in that it shows that pied a 
which was used throughout the study, does not <e os 
change the toxic properties of these agents oe ye hs 
spores. The infusion of sugar beet was prepared Ke we 
450 grams of the root in a liter of water for 3 house ee of t¥O 
was then strained, cooled, and stirred “up with the vias : : 
