Re ee ee, er 
Igor] GERMINATION OF SPORES 59 
nation later than August of the following year, and the optimum 
germination occurs during the spring of the latter year. Eriksson 
and Henning’ are of the opinion that a passage through the 
animal body will not act as a substitute for the dormant period, 
Such lines of work have not been systematically followed out, and 
even for the Uredineae, which are very variable in their disposi- 
tion toward the resting period, the limitations are not sufficiently 
known. According to Kihn, Brefeld, and others, as previously 
mentioned, germination of certain smuts in water can only be 
induced after a period of rest, while immediate germination may 
result from the addition of food material. My own results also 
show that the per cent. of germination with Ustilago Avenae and 
U. perennans increases considerably from summer to autumn, 
even though the material is kept in dry condition. 
In other experiments, Sterigmatocystis nigra kept dry in the 
laboratory for five years gave no germination, while material one 
and two years old gave good germination in nutrient media. 
This age of the material did not act asa stimulus to germina- 
tion, however, since only a fraction of 1 per cent. germinated 
when sown on distilled water. After drying out for four days 
on slide at 25° C. neither Aspergillus flavus, Penicillium glaucum, 
nor Sterigmatocystis nigra. showed any germination as tested by 
distilled water. 
SUBMERGENCE OF SPORES. 
Ordinarily the spores of such molds as Aspergillus flavus and 
Sterigmatocystis nigra float on the surface of solutions; and, 
depending upon the solution, they may or may not tend to collect 
at the line of attachment to the glass in drop cultures. The 
spores of Phycomyces and other Phycomycetes, as well as many 
Hymenomycetes, however, very readily sink beneath the surface. 
To test the capacity of Aspergillus for submerged germination, 
Spores were sown in bean infusion between the parts of a strip of 
mica lightly separated. The mica was then dropped into a flask 
of bean decoction. After two days the removal and examina- 
tion of the mica showed that all spores were germinated, those 
*S ERIKSSON and HENNING: Op. c. 54. 
