ANTHRACNOSE OF CUCURBITS. 19 
Cellulose may also be utilized as a sole source of carbon. Pure 
cellulose jelly prepared from absorbent cotton and substituted for 
sucrose supported a growth of mycelium which yielded in several 
months a dry weight greater than that of the cellulose added. Fur- 
ther proof of the ability of Colletotrichum to dissolve cellulose was 
furnished by the clearing of the turbidity in an unslanted test tube 
of cellulose agar to a depth of 1 cm. beneath the colony. This sug- 
gests that a cellulose-dissolving enzym was secreted, which acted in 
advance of the mycelium. In a similar tube containing sucrose in 
addition to the cellulose, growth was more vigorous, but little or no 
visible disappearance of the cellulose was noted. This indicates that 
the presence of sucrose may have inhibited the utilization of cellu- 
lose. 
EFFECT OF COPPER SULPHATE, 
Using the full nutrient solution, the influence of very low concen- 
trations of copper sulphate upon the growth of Colletotrichum and 
Aspergillus was studied. Colletotrichum proved to be much more 
sensitive to copper sulphate. Whereas Aspergillus showed marked 
increase of yield in a concentration of molecular + 16,000, toxic effects 
in molecular + 1,000 and ability to grow in‘the presence of molecular 
+ 250, Colletotrichum was only stimulated slightly, if at all, by con- 
centrations of copper sulphate as low as molecular+128,000 and 
showed toxic effects in molecular +64,000 and total inhibition of 
growth in molecular + 2,000. 
SPORE GERMINATION. 
In poured plates of agar at room temperature, spores germinate 
within five hours. In drops of distilled water on slides at room tem- 
perature, germination usually occurs within 24 hours, although this 
time varies greatly. In some cases abundant germination occurred 
within 10 hours and appressorium formation within 20 hours. In 
pipette-dropper inoculations of leaves in the greenhouse, it has been 
found that abundant appressorium formation occurred within 24 
hours. 
In general, germination is favored by the presence of some nutrient 
material and a 2 per cent dextrose solution or a prune decoction made 
by steaming 10 grams of prune flesh in 1,000 c. c. of distilled water 
has proved very useful. An abundant oxygen supply seems quite 
essential. Germination is more prompt about the edge of drops con- 
taining spores and is more vigorous in exposed drops than in Var 
Tieghem cells. | 
To determine the effect of such factors as temperature, food supply, 
and aeration upon germination, a series of tests wasrun. This con- 
sisted of a quadruplicate series of hanging drops in Van Tieghem cells 
and exposed drops on flamed slides in prune decoction and in dis- 
