DorAN: ON THE GERMINATION OF FUNGOUS SPORES 329 
sary for their germination, five hours at 12° C. and twenty-four 
hours at 8° C. Tisdale (39) found that at 4° C., which is their 
minimum temperature for germination, the spores of Didymellina 
wridis germinate in twenty-one hours, but at their optimum 
temperature of 20° C. to 26° C. these spores germinate in two 
and one half hours, and at their maximum temperature which 
is 30° C. their germination requires eleven hours. 
The presence of a nutrient solution may hasten the germina- 
tion of some spores. Gardner (30) found that the spores of 
Colletotrichum lagenarium germinate in five hours in agar but 
require ten to twenty-four hours for their germination in dis- 
tilled water at the same temperature. 
It appears that immature spores and aged spores may germin- 
ate more slowly than mature spores. Melhus, Durrell, and 
Kirby (18) found that both before and after the teliospores of 
Puccinia graminis have completed their rest period, the time 
required for their germination is longer than that required just 
as they end their rest period in the spring. 
The results mentioned above indicate that all fungous spores 
germinate most rapidly when all environmental conditions are 
nearest to the optimum. 
TABLE III shows the time necessary for the germination of 
twenty-three representative fungous spores. After a study of 
this table it is possible to draw certain conclusions as follows: 
The average time required for the germination of fungous spores 
is about twelve hours; for the germination (indirect) of the conidia 
of the Phycomycetes it is four hours; for the ascospores of the 
Ascomycetes it is thirteen hours; for the germination of the 
chlamydospores of the Ustilaginales it is twenty-one hours; for 
the germination of the aeciospores of the Uredinales it is ten 
hours; for the germinations of the urediniospores of the Uredin- 
ales it is five hours; for the germination of the teliospores of the 
Uredinales it is three hours; and the average time required for the 
germination of the spores of the Fungi Imperfecti is seventeen 
hours. 
The writer has found that the length of time necessary for the 
germination of the fungous spores named in TABLE IV is: aecio- 
spores of Cronartium ribicola twelve hours; urediniospores of 
Cronartium ribicola five and one-half hours; for the production 
of basidia by the teliospores of Puccinia Malvacearum two hours; 
one hour more, a total of three hours are necessary for the 
