12 Nebraska Agricultural Exp. Station, Research Bui. 12 
above a group of stromata placed on moist blotting paper in 
a covered vessel caught and held large numbers of spores. 
Tulasne^^ stated that the spores are expelled in March or 
April. The writer has found spores being expelled during 
every part of the growing season depending upon weather con- 
ditions. Stromata kept in the laboratory for over three years 
expelled spores in large quantities within a few hours after 
being placed in contact with wet blotting paper. It is very 
common to find ascospores being expelled thru masses of 
conidiophores and conidia on the surface of the stroma. 
The spores are hyaline until they attain full size when they 
assume a dark brown or black color with a lighter line ex- 
tending along one side. Hasselbring^^ gave a very accurate 
description of their germination. He stated : "In germination 
the exospore cracks along the lines previously described. Two 
germ tubes originate from the endospore. These turn away 
from each other and remain at first closely appressed to the 
* spore. Then they grow out in opposite directions." 
Hasselbring found that oxygen is necessary to spore ger- 
mination. The writer also found this to be true. Spores deeply 
embedded in poured plates did not germinate at all while the 
percentage of germination was high at or near the surface. 
Ascospores retain their vitality for a long period of time. 
A large number of stromata were secured in the spring of 
1914 and the spores tested for germination at intervals of 
three months. After three months the per cent of germina- 
tion was 91.8. This was nearly 20 per cent higher than when 
the spores were first taken. This was probably due to the 
presence of a large number of immature spores when the 
stromata were gathered. After three years the per cent of 
germination was 31.9. It was found, however, that a great 
number of these spores were so reduced in vitality that the 
germ tubes grew to be only a few mm. in length and died. 
As was the case with conidia, few spores germinated when 
they were exposed in a moist atmosphere for several hours 
and then allowed to dry before the test was made. 
MYCELIUM 
Mycelial growth in artificial media is relatively slow from 
both conidia and ascospores. For this reason it was very dif- 
ficult to secure pure cultures from conidia unless the spores 
were taken from those first matured on the stroma before the 
bark became ruptured. Later, spores of Macrosporium and 
Fusarium were often found intermingled with the conidia. 
