334 Doran: ON THE GERMINATION OF FUNGOUS SPORES 
germinate in either light or darkness, when the other environ- 
mental conditions are between maximum and minimum limits. 
It is, however, probable that the germination of fungous spores 
in nature usually takes place in darkness, since it is in the night 
that conditions of temperatures and moisture nearer the opti- 
mum for germination usually prevail for a longer time. 
Water relation—An examination of the literature indicates 
that the moisture requirement of germinating spores is not 
uniform. Tulasne (57) was able to germinate teliospores of 
the Uredinales as well in a saturated atmosphere as in a drop 
of water. Patrigeon (20) found that for the germination of the 
conidia of Plasmopara viticola precipitated moisture is necessary 
and merely damp air is insufficient. According to DeBary 
(47) the spores of the Uredinales germinate better when they are 
merely in a moist atmosphere than when they are in water. 
Lesage (58) found that the spores of Penicillium glaucum can 
germinate in damp air so long as the humidity does not fall 
below 82 or 84 per cent. Taubenhaus (51) readily germinated 
the teliospores of Puccinia Malvacearum in a humid atmosphere. 
Levin (59) was able to infect tomatoes with Septoria Lycopersict 
by merely applying dry spores. Weimer (9) found the telio- 
spores of Gymnosporangium Juniperi-virginianae unable to 
germinate when they were in contact with no moisture except 
that in the atmosphere. These spores did not germinate until 
the air became super-saturated, so that small drops of water 
collected on the slides in contact with the spores. Anderson 
(11) states that the spores of Cylindrocladium scoparium never 
germinate except when they are directly in water, a moist 
atmosphere being insufficient. According to Melhus and Durrell 
(7) the urediniospores of Puccinia coronata germinate only when | 
they are in direct contact with water. Smiley (33) found that 
in the absence of a film of water, the spores of Phyllosticta 
Antirrhini do not germinate. Melhus, Durrell and Kirby 
found that the sporidia of Puccinia graminis germinate pro- 
fusely in drops of water, and but very poorly when their only 
moisture is obtained from the atmosphere. 
The writer tested the effect of moist air as compared with 
precipitated moisture on the germination of the spores named in 
TABLE V. The aeciospores of Gymnosporangium clavipes ger- 
minate perfectly i in moist air, as they do in water. The spores of 
Alternaria Solani and the conidia of Venturia inaequalis germinate 
