
42 BOTANICAL GAZETTE [JANUARY 
results may be untrustworthy if any volatile or soluble substance 
besides the medium employed is used in connection with the 
cultures. As subsequently mentioned, even the purest vaseline 
may have an effect on sensitive forms. In all cell cultures in 
which full nutrient media were not employed, I have used a 
modified method. The cells were used in small Petri dishes. 
On the bottom of the Petri dish was placed filter paper with 
holes made for the insertion of the cells, thus securing them 
against movement. The covers were laid on without vaseline, 
and only in a few cases with volatile substances was any vase- 
line placed on the outer rim of the Petri dish. Dishes with 
ground-glass tops are preferable. All cultures were kept in 
moist chambers. The one difficulty remains of opening the cul- 
tures for examination, but as it is done only once, or at most 
twice during the continuance of the experiment, it is perhaps a 
matter of small significance. 
All cells, dishes, flasks, etc., used in these experiments were 
first cleaned with an alkali, then an acid, and finally, after 
thorough washing in distilled water, steamed for an hour or two 
before use. Particular care was taken with the covers, which 
were also boiled in the cleaning materials, and kept soaking 
either in distilled water, or in some cleaning agent when not 
in use. Cultures were kept in the warm room at a tempera- 
ture of about 25° C., this temperature being especially 
commendable on account of ease of examination at the same 
temperature. 
After considerable experience with vegetable decoctions for 
the growth of fungi, I] have generally adopted a decoction of 
green string beans or of sugar beets as the best culture medium 
for most readily culturable fungi. Any absolute standard of 
strength is impossible, but as a working basis, fifty grams of dry 
matter for each liter of water has been found convenient; thus 
for green beans, from an average of analyses, three hundred and 
ninety-two grams would be required per liter. 
The chemicals used have been the purest obtainable; and the 
sugar was recrystallized by the alcohol method, and subsequently 
