350 
Journal of Agricultural Research 
Vol. XXIV, No. 4 
Lima bkan agar.—^T his was made in the same way as the oat agar 
except that the decoction was made by heating loo gm. of broken pieces 
of lima beans in i,ooo cc. of water. 
Potato glucose agar. —^This medium was made in the same way 
as the oat agar except that the decoction was made from loo gm. of 
sliced potato tubers, and just before the mixture was tubed 50 gm. 
of glucose (T. J. Baker’s c. p.) was added. 
Rice.—^A bout 3 gm. of rice were put into each tube, 10 cc. of tap 
water were added, and the tubes were plugged and autoclaved. 
Potato peug.— Cylinders cut from potato tubers were slanted and 
placed in tubes with enough water added to about cover the cylinder. 
The tubes were plugged and autoclaved. 
Sweet ceover stems. —^Stems of sweet clover {Melilotus alba) were 
cut into convenient pieces. If the stems were large enough only one 
was placed in a tube. Most of them, however, were small and two to 
four pieces were used. The stems were dry, so water enough to cover 
them was added. The tubes were plugged and autoclaved. 
Tomato stems. —^Sterns and leaves of young tomato plants {Lycopersi- 
cum esculentum) were cut into convenient pieces, put into tubes with 
distilled water added to within about % inch of the top of the stems. 
The tubes were plugged and autoclaved. 
Five series of cultures were grown on oat agar, five on potato glucose 
agar, three on lima bean agar, two on^ potato tuber plug and one each 
on the other media mentioned above. 
TEMPERATURE AND EIGHT CONDITIONS USED 
By far the greater number of the series of cultures were grown in the 
dark in an incubator regulated between 20° and 2 2^^ C. This temperature, 
according to data of various investigations, seemed to be nearest the 
optimum for the greater number of species. 
In all cases where the “dark” incubator is mentioned it refers to one 
the temperature of which was regulated by burning a 20-watt carbon 
light automatically controlled by a thermostat in the lower portion of 
the incubator. The cultures were kept in cans on wire screen shelves, 
and the light given off from this bulb should possibly be considered 
as influencing the results, though it does not seem probable that it did 
as the temperature of the room was such that the bulb was lighted but 
a small portion of the time. 
One series of cultures grown on potato glucose agar was kept in dif¬ 
fused light and incubated at room temperature whidi varies from about 
18° to 25° C. 
Another series grown on potato glucose agar was inoculated in quad¬ 
ruplicate, and two tubes of each culture were grown in the “dark” 
incubator at 20° C. and two similar tubes grown in an incubator with 
glass doors, designated as the “light” incubator, which was in the 
greenhouse so placed that the cultures were in strong diffused light 
during the day. The tubes were kept in glass beakers and only a few 
in eadi beaker. The temperature of the “light” incubator was kept 
at 21.5° C. 
Still another comparison between cultures grown in light and darkness 
was made with lima bean agar. In this case two tubes of each culture 
were kept in the dark incubator at 20° C. and two each were kept in 
diffused light in a room at a temperature which varied between 18° 
and 25°. 
