444 
Vol. XXV, No. II 
Journal of Agricultural Research 
would have been shown. In fact, a study of the growth reactions of the 
fungus at temperatures of 23.6°, 25.7°, and 26.7° would suggest a possible 
optimum of 23.6° at the end of 120 hours. Balls noted the effect of the 
time element in his studies on the sterile stage of Corticium vagum , or 
“sore-shin'’ fungus, and studied the phenomenon in detail. He showed 
that the stopping point for the apical growth of the hyphae was lowered 
with increase of time. Again, this author points out that the “time 
element’’ varies with the different media on which the fungus is grown. 
On hard agar, he states, the growth was considerably inhibited by high 
temperature; on soft agar at the higher temperatures, inhibition of rate 
of growth became evident with increase of time; while in liquid media 
this slowing up of the rate of growth was delayed, the delay being greater 
with increase of volume. From considerable experimental evidence, 
Balls (3) concludes that this inhibitive effect of high temperature is 
occasioned entirely by the by-products from the metabolic process which 
accumulate at these temperatures, both within and without the cell, to 
such an extent that growth is limited by them, and he further suggests 
that the accumulation of such substances may play an important part 
in limiting the pathogenic power of the fungus at these higher tempera¬ 
tures. It is interesting to note that a similar decreased rate of growth 
with increase of time was found by Lehenbauer (9) to be an important 
factor in the growth of the com plant at the temperature of 32 0 C. and 
above. The observations of this writer, however, were not continued 
over a sufficient period to give definite data on this point. 
From a study of the data in Table VIII, it is clear that the tempera¬ 
tures shown to be most favorable for the growth of the fungus may be 
considered as optimum for a period of 96 hours only. Furthermore, as has 
been pointed out by Blackman (5), Lehenbauer (9), Leitch (10), and 
others, the optimum temperature value for growth under any specific set 
of conditions is quite without meaning unless the time limits for the 
period of the observations are accurately stated. Likewise, we are 
forced to conclude from these studies and from the work of Balls ( 3) 
that the actual optimum temperature for the growth of any strain of 
Corticium vagum will depend upon a large number of factors relating to 
the condition and history of the fungus, as well as to its specific environ¬ 
ment. 
Table IX .—Ratio of increased temperature to rate of growth of the fungus Corticium 
vagum over a period of g 6 hours 
Temperature range. 
Comparative 
increase growth 
for each io° C. 
Coefficient. 
°C. 
4.6 to 14.6. 
Cm. 
0. 76 to 6. 5 
1. 35 to 8.1 
2. 87 to 12.1 
6. 50 to 15. 0 
7.80 to 17. 5 
8.10 to 12. 5 
10. 25 to 12. 5 
12.10 to 10. 0 
8.50 
6. 00 
g.2 to l8.I . 
IO.9 tO 20.1. 
A. 20 
14.6 tO 22.1 .. . 
«f. 
2. 30 
2. 24 
i* 54 
1. 21 
16.2 to 2<.2 . *. . 
18. i to 29.8. 
19.8 to 29.8 . 
20.1 tO 3I.2 . 
0. 82 
O. 42 
22.6 tO 22.6 . 
15. 00 to 6. 5 
17. 50 to 0 
2 C .2 tO 2 tf.O. 
v ' TJ 
O 
- j*o Oj ,v ... . 
