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1900] BRIEFER ARTICLES 51 
mature conidia are set free. A true pycnidium is not developed. 
When first exposed the conidial mass is a delicate creamy tint, but 
with age its outer surface becomes dark colored or even black. The 
conidia (fg. 9) are continuous, hyaline or with a greenish tinge, ellipti- 
cal, curved, coarsely granular, and 
measure 5—7X 16-284. They average 
about 6X 24p. 
Late in July dilution cultures were 
made in neutral and in acid potato- 
agar from material that had been col- 
lected the last of June. In these cultures 
not a single colony developed. Octo- 
ber 4 similar cultures were made from 
material which was collected about the 
middle of July. In this but two conidia 
could be found that had germinated. 
In fact so few conidia had developed 
that it was difficult to obtain enough 
for satisfactory cultures without obtain- 
ing an extensive variety of contamina- 
ting growths. To obviate this difficulty, 
on October 6 conidia from a single 
acervulus were carefully removed with 
a flamed scalpel, teased out in a drop 
of sterilized water, and transferred with 
a sterilized camel-hair brush to marked 
Places on plates of acid potato-agar. 
These plates were examined daily, and although numerous spores were 
seen none were observed to germinate until October 10, when 
two which had made a feeble growth were transferred to tubes of 
sterilized bean stems. At the time the general failure of the spores 
to germinate was thought to be due to their loss of vitality through 
having been kept too long in the laboratory ; but it now appears to 
have been because the conidia used were not mature, since spores from 
material collected October 4 have continued to germinate readily up 
to the middle of November. 
In cell and in Petri dish cultures in potato-agar the conidia germi- 
nate readily in about twelve hours at a temperature of 22°C. At 29 
the §ermination is retarded indefinitely, although spores in cell-cultures 
FIG. 4. 
