Sept is, 1923 
Corticium vagum on the Pea and Bean 
443 
The results thus obtained agree essentially with those of previous 
workers. Growth occurred through a range of temperatures of from 
4.6° to 32.5 0 C., with an optimum both for linear and aerial mycelial 
growth for 96 hours of between 25 0 and 27 0 . It will be noted from the 
data tabulated, however, that at the higher temperatures the initial 
growth rate was not maintained; a progressive decrease with time was 
noted at all the different temperatures between 23.6° and 32.5 0 , inclusive, 
and only at the temperature of 22.4 0 was the rate of growth for the first 
24 hours maintained for the entire period of observation. 
Fig. 6 .—Showing the temperature range for the pathogenic action of Corticium vagum. on the three hosts— 
' pea, bean, and potato—in comparison with the temperature requirement for the growth of these three 
host plants ( 13, tables on p. 463-472 and 475) and for the growth of the fungus in pure culture. 
Table VIII .—Effect of temperature upon the growth of Corticium vagum on potato agar 
Increased growth in diameter of colony for consecutive periods of 24 
hours at different temperatures ( 6 C). 
4.6 
8.2 
10.9 
14.6 
16.3 
18.1 
19 
20.1 
22.4 
23.6 
25-7 
26.6 
29.8 
31.2 
32.6 
35 
Age of colony (hours): 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
24. 
a. 0 
0.0 
3 -o 
1 3 - 5 
16. 0 
17.0 
18. 0 
22.5 
28.5 
33 -o 
38.0 
39 -o 
36.0 
24. 0 
20.0 
0 
48. 
3.0 
3.0 
9-5 
16. s 
18.0 
18.0 
22. 0 
25. O 
31.0 
29.0 
37-0 
38.0 
26.0 
22.0 
15.0 
0 
72 . 
*•5 
3-5 
6. 0 
7 - 5 
16.0 
13 - 5 
22.0 
25. O 
25.0 
29.0 
36.0 
34-0 
23.0 
19.0 
10.0 
0 
96 . 
1.0 
4-5 
5 -o 
15.0 
12. s 
, , , . 
20.0 
24. O 
29.0 
29.0 
30.0 
29.0 
i 5 -o 
16.0 
7.0 
0 
Average increase in diameter of 
colony... 
1-5 
2-7 
5-6 
13.0 
IS-6 
16. 3 
20. s 
24. I 
28.3 
30.0 
35 - 2 
35 - 2 
25.0 
20. 2 
13.1 
0 
Average linear growth of myce¬ 
lium. 
•75 
1-35 
2.87 
6.5 
7.8 
8.1 
10. 25 
12. I 
14.1 
15.0 
17. 6 
17.6 
12.5 
xo. 1 
6.55 
0 
This decided falling off in the rate of growth with time at the higher 
temperatures is especially significant, in view of the low temperature of 
23 0 C. which was found by Balls (j) to be optimum for continued growth 
of the fungus. This would indicate that had the experiment continued, 
a much lower optimum temperature than that found for the 96 hours 
