158 
Journal of Agricultural Research 
Vol. VIII, No. 4 
Some of the fungi that furnished little temperature contrast on the 
apples gave quite striking ones on agar. This is especially noticeable 
with Cephalothecium roseum , but it also occurs with Alternaria sp. and 
Botrytis drier a . On the other hand, the species of Sclerotinia, Peni- 
cillium, and Sphaeropsis used have given relatively less temperature 
contrast on corn-meal agar than on apples. (See figs, i, 2, 25.) A 
medium favorable to the fungus apparently intensifies the temperature 
contrasts. 
While there are the differences already pointed out in the temperature 
responses of the various fungi on the two media, the curves plotted for 
growth on corn-meal agar are on the whole in quite close agreement with 
those for growth on the fruit, showing that the temperature response is 
largely determined by the organism itself. 
Sphaeropsis malorum on corn-meal agar in 
petri dishes. 
Fig. 23.—Graph showing the growth of Volu- 
tella/ructi on corn-meal agar in petri dishes. 
It will be noted that the curves for the petri-dish experiments, like 
those for the apple rots, have been plotted on the basis of the diameter 
rather than the area, thus giving relatively low values to the growth in 
the larger colonies and making the contrasts too small between the high 
and low temperatures and between the early and late stages of the 
experiment. 
GERMINATION AT TOW TEMPERATURES 
The above experiments with petri dishes furnish data as to the growth 
of the fungi at various temperatures when the cultures had been exposed 
for 24 hours in the laboratory before being placed at the temperatures 
of the experiment. A later test was made on corn-meal agar in which 
the petri dishes were inoculated as already described but were placed 
at the desired temperatures immediately. Notes were taken at the times 
indicated in Table IV. 
