[Vor. S 
326 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
culture solutions, on the other hand, gave normal germination. 
For 10 hours at 23? and 27? C., the secondary spores were still at- 
tached; at 31? C., however, they were detached. When incu- 
bated for 20 hours at each of the temperatures, the spores were 
detached and numerous. According to Stoneman (798), “the 
formation of the so-called secondary spores or buds which are 
common to Gloeosporium, Colletotrichum, Volutella, and Vermic- 
ularia is not a constant character, but may be absent throughout 
the entire cycle of development of a species, or may be forced in 
the same species by a lack of nourishment. " 
The spores of Ustilago Avenae from the material available 
gave such relatively low percentages of germination with the 
E 4 = zo°%e 
'A LEE 
& 6o 
é A | 
v. /! N 
S T ks ia 
E e 1 I \ clin — lid 
N f I M aT - 
Fi Ns N 
e 3 4 M é 7 8 9 10 
Ņ 
Fig. 28. Lenzites saepiaria in Czapek's full nutrient solution. 
described method of technique that this organism was discarded. 
However, series were conducted in mannite solutions at 15°, 19°, 
and 25° C. In general, germination ranges from Py 2.4 to 8.2, 
with a maximum at Py 6.2. Sporidia occur most abundantly 
from Py 5.4 to 7.0 and decrease in number with increase in 
departure from either side of this zone. 
Repeated endeavors have also been made to study conidial 
germination with certain of the powdery mildews, but all attempts 
have been without avail No germination whatever has thus 
far been obtained with Sphaerotheca pannosa at different tem- 
peratures when the conidia were placed either in the hanging 
