434 
F. D. HEALD AND R. A. STUDHALTER 
1. Temperature below the optimum for expulsion. 
2. Insufficient rainfall. 
3. Location of the trap with reference to the direction of the rain. 
4. Condition of the perithecia (not in proper stage to expel spores). 
Table III 
Ascospore Trap Tests, Records for West Chester, Pa., Winter and Spring, igij-14 
Rainfall 
Temperature 
Percentage of 
Traps Showing 
Date 
Amount, Inches 
Max. 
Min. 
Expulsion 
Nov. 8-9 
1. 00 
60 
37 
" 15-16 
0.96 
58 
28 
0 
" 28 
0.62 
44-5 
33-5 
Dec. 7 
0.53 
52 
41 
0 
" 21 
0.05 
47 
27 
0 
" 23-5 
1-95 
50 
32 
0 
Jan. 3-5 
39 
25 
0 
" 24 
1-35 
50 
40 
0 
" 31 
0.88 
63 
36 
0 
Feb. 6-7 
0.62 
48 
27 
0 
" 13-14 
4.5 (snow) 
32 
0 
" 16 
1-5 
25 
0 
" 19 
0.68 
34 
29 
0 
Mar. 1-2 
4.50 (snow) 
38 
15 
0 
" 5-6 
6.00 " 
33 
29 
0 
" II 
traces " 
29 
20 
0 
" 18 
O.IO 
43 
29 
0 
" 20-22 
3.5 (snow) 
34 
II 
0 
" 28 
0.35 
58 
37 
0 
April I 
0.25 
48 
37 
0 
8 
0.60 
67 
41 
0 
" 15 
0.49 
45 
41 
0 
" 20 
0.44 
68 
45 
0 
" 25 
1-57 
50 
44 
0 
" 30 
O.IO 
50 
45 
0 
May 5 
0.71 
65 
59 
II.8 
There was a marked example of the influence of the temperature 
following a rain of 1.57 inches on April 13-16, 1913, when only 4 per- 
cent of the traps showed expulsion. The maximum rainfall following 
which there was no expulsion of ascospores when temperature con- 
ditions were favorable was 0.12 inches on June 7, 1913. A small 
percentage of traps sometimes showed expulsion when the rainfall 
was less than 0.12 inches. (See Tables I-IV.) The number of 
rains for the entire period covered by our investigations following 
which there was expulsion of ascospores is shown in Table V. 
Perithecial activity in 191 3 began in the spring as soon as tempera- 
ture conditions became favorable, but since the temperatures at this 
