Doran: ON THE GERMINATION OF FUNGOUS SPORES 333. 
one under consideration, and there should not be present an 
excessive number of spores of that one fungus. 
There are a few references which have come to the attention 
of the writer on the deleterious effect of competition or crowding 
on germinating spores. Edgerton (50) noticed that when more 
than twelve or fifteen spores of Colletotrichum Lindemuthianum 
are present in one cubic millimeter of water, they germinate 
more poorly than when a smaller number of spores are present. 
Taubenhaus (51) found it advisable to wash hollyhock leaves 
in water to remove the spores of saprophytic fungi preparatory 
to studying the germination of the teliospores of Puccinia 
Malvacearum. He does not indicate in what manner the pres- 
ence of the spores of other fungi interfere with the germination 
tests. 
Light relation.—Opinion in the literature is not unanimous 
as to the effect of light on spore germination. According to 
DeBary (52) and Farlow (53) light inhibits the germination 
of the spores of the Oomycetes. Cuboni (54) concluded that 
intense light interferes with the germination of the conidia of 
Plasmopara viticola. Ward (55) found that the spores of the 
brome rust germinate as readily in light as in darkness. Melhus 
(22) observed no difference in the percentage of conidia of 
‘ystopus canididus germinating, nor in the time required for 
their germination, whether germination took place in light or 
darkness. Melhus (23) found that light does not interfere 
with the germination of the conidia of Phytophthora infestans 
if the optimum temperature for their germination is not exceeded. 
Duff (17) found that exposure to glass filtered sunlight is not 
injurious to the urediniospores of Cronartium ribicola, providing 
the temperature does not rise too high. He found that exposure 
to the ultra-violet rays from an electric arc completely inhibited 
spore germination. Lauritzen (56) concluded from his invest- 
igations that light is not a limited factor in the infection of 
plants by fungi. 
The writer tested the effect of sunlight on the germination of 
the spores of Aliernaria Solani and the conidia of Sclerotinia. 
fructigena. The spores of both of these fungi germinate quite as 
well in sunlight, whether it be direct, diffuse, glass filtered or 
not glass filtered, as they do in darkness, provided that the 
conditions of temperature and moisture meanwhile remain near 
the optimum. The indications are that the spores of fungi 
