320  DoRAN: ON THE GERMINATION OF FUNGOUS SPORES 
the spores of Cylindrocladium scoparium live for several weeks 
but that in a dry atmosphere they die in fifteen days. 
Under no conditions did aeciospores of Cronartiwm ribicola 
germinate when more than eight weeks old. few cases are 
recorded in the literature of aeciospores of this fungus living 
longer, but it is probable that in such cases germination is reduced 
to a trace and that even that small germination occurs only 
when all environmental conditions are very close to the optimum 
for a time. 
The conidia of Venturia inaequalis produced on the leaves 
are somewhat shorter lived than those produced on the fruit. 
According to Aderhold (12) the conidia of this fungus retain 
their viability not more than eight weeks. The writer found 
none of the conidia of this fungus to live more than six weeks on 
the fruit and not more than four weeks on the leaf. With the 
aging of the leaves in the fall, the life of the conidia becomes even 
shorter. Difficulty was experienced in germinating conidia 
from fruit in storage. The scab lesions, however, were con- 
taminated with Cephalothecium roseum, the presence Of the 
conidia of which in the drops of water may bave been partly 
responsible for the failure of the conidia of Venturia inaequalis 
to germinate. As will be described later, the presence in a drop 
of water of the spores of several fungi prevents or retards the 
germination of all the spores as compared with germination in 
a drop of water containing only the spores of one fungus. 
One of the factors bearing upon the retention of viability by 
spores after their collection is their freedom from or connection 
with the fungus or each other. Anderson and Rankin (13) 
found that ascospores of Entothia parasitica which remained in 
the perithecia in the bark germinated after being stored dry for 
one year. But when ascospores were removed and separated 
for only five months they lost the power to germinate. According 
to Burrill (14) the spores of Glomerella rufomaculans remain 
viable for a long time when their soluble protective coating in 
which they are imbedded is present. But if it is washed away, 
the spores soon lose the power of germination. Anderson and 
Rankin (13) found that if the pycnospores of Entothia parasitica 
are stored in a dry place they live at least one year. But if the 
pycnospore horns are placed in water and the water allowed to | 
evaporate so as to leave the spores separated, they do not retain 
their viability more than one month. 
