148 
BASCOMBE BRITT HIGGINS 
Cultural Characters 
The conidia seem to lose their vitality very rapidly on drying. 
When they are taken from the dry masses which cover the acervuli 
only a small per cent of them germinate in nutrient agar or in tap 
water; and some taken from cherry leaves which had not been wet 
for about a month failed to produce infection on other leaves of the 
same plants. 
Fresh spores germinate very slowly in agar. For this reason and 
because of the large number which failed to germinate it was found 
very difficult to obtain pure cultures of the fungus by the dilution 
method. When leaves were placed in a moist chamber for a few hours 
so that fresh conidia were formed, pure cultures were readily obtained 
by picking up a quantity of them on the point of a needle and then 
dragging the needle across an agar plate. After four or five days 
there were usually spots on some of the streaks free from bacteria and 
other fungi where some of the Cylindrosporium conidia were beginning 
to germinate. Blocks of agar containing such germinating conidia 
were then transferred to tubes of agar or to sterilized bean pods. 
Comparison of the fungus isolated from the different hosts was 
made chiefly from growth on steamed bean pods; but the nature of 
the medium seemed to have very little effect on the nature of the 
growth, colonies very similar to those on bean pods being produced 
on agar dissolved in tap water; on agar to which had been added an 
extract of beans, potatoes, malt extract, prunes, or cherry leaves; 
on sterile slices of pear; or on steamed cherry leaves. 
Growth from the spores is always very slow, and is usually not 
apparent to the unaided eye until 10-15 days have passed. At this 
time it appears as a small whitish speck, which when examined 
microscopically is found to consist chiefly of a stroma covered with 
quantities of conidia similar to those produced on the host plant. 
This stroma grows slowly, enlarging until a hemispherical mass 0.5-1 
cm. in diameter is formed, which occurs in about two months. Before 
this time the stroma has turned coal black and has a carbonaceous, 
crust-like appearance in the fungus isolated from P. domestica and P. 
insititia. After the stroma has turned black few spores are produced 
even when transferred to new media. The stroma produced from the 
fungus isolated from P. avium, P. cerasus, and P. pennsylvanica some- 
times turns dark but never black and crust-like as in that from the 
plums. The stroma from the other three cherries, P. virginiana, P. 
