896 Journal of Agricultural Research voi. v, no . x 9 
exposed plates were brought into the laboratory as soon as possible after 
collection, were placed edgewise in a glass funnel, and the glycerin and 
contents washed off into a vial with a 2 c. c. pipetteful of 95 per cent 
alcohol. The stream of alcohol used in washing the plates was per¬ 
mitted to play slowly along the upper edge. The washings were then 
permitted to evaporate until only a few drops remained in the vials. By 
examination with the low-power lens of a microscope the number of 
conidia in these few drops could then be determined. 
This method is open to two serious objections. Many of the spores 
were not washed from the plate by this method, as evidenced by a test 
in which a plate washed according to the method described and found 
to have entrapped three conidia of Cercospora personata was afterwards 
washed, using a wash bottle as a means of driving a stream of 95 per cent 
alcohol forcibly against it, and was found to have nine additional conidia. 
The other objection, which was encountered by Heald, Gardner, and Stud- 
halter, 1 consists in the fact that it is practically impossible to spread a 
film of glycerin uniformly on a glass slide and have it remain so for three 
hours. The results shown in Table III are therefore not representa¬ 
tive of the number of conidia that were actually entrapped, but con¬ 
vincingly prove that the conidia of C. personata are wind borne. 
Table III .—Results of tests of glycerin plates exposed to air currents at Eutaw, Ala. 
Date of exposure. 
Number of plates 
exposed. 
Number of plates 
with adhering 
conidia. 
Rainfall. 
Maxi¬ 
mum 
number 
of co¬ 
nidia of 
Cercos¬ 
pora per¬ 
sonata 
on any 
plate. 
Total number of 
conidiaentrapped 
during the entire 
period. 
Day. 
Night. 
Day. 
Night. 
Day. 
Night. 
Inches. 
Aug. 9. 
X 2 
3 
5 
X 
0 
4 
15 
2 
10. 
12 
3 
4 
0 
1.58 
3 
10 
0 
xi. 
12 
3 
5 
0 
0 
4 
XI 
0 
12. 
12 
3 
5 
X 
o -43 
4 
15 
2 
13 . 
12 
3 
xo 
0 
0 
4 
24 
0 
14 . 
12 
3 
8 
I 
0.18 
4 
16 
2 
16. 
12 
9 
2 
0 
9 
17. 
12 1 
O 
S 
2 
0 
0. 
O 
2 
, 
18. 
12 
O 1 
3 
6 
I 
O 
3 
9 
X 
19 . 
12 
3 
5 
0 
0-04 
4 
12 
0 
20. 
8 
2 
2 
0 
0.13 
3 
4 
0 
21. 
8 
2 
4 
0 
0 
3 
7 
0 
23 . 
8 
2 
3 
0 
0.02 
2 
5 
0 
24 . 
8 
2 
3 
X 
X. 12 
3 
6 
1 
25 . 
8 
2 
3 
X 
0 
3 
s 
1 
26 . 
8 
2 
5 
0 
0 
2 
6 
0 
Total. 
168 
42 
72 
6 
x 
rt 
Tntfll dav otiH 
iuwu uay CVLLLL 
night . 
210 
*8 
T E 
ro 
>y 
It is not deemed necessary to give a detailed daily record of the actual 
routine pursued. It will be seen that only 78 of the 210 plates exposed 
1 Heald, F. D,, Gardner, M. W., and Studhalter, R. A. Air and wind dissemination of ascospores of the 
chestnut-blight fungus. In Jour. Agr. Research, v. 3, no. 6, p. 493-526.pl. 63-65. 1915. Literature cited, 
p. 525-5*6. 
