99 
Ravn (91) places the upper limit for growth at 33°—34°; the optimum 
at 25°—30°; the lower limit at 3°—5°. 
Plates prepared in a similar manner to the above were kept for 4 days 
at 15° and then transferred to the 25° case. Similarly, transfers were 
made from the 25° to the 15° case. The data of colony-growth from this 
trial are shown in the following table. 
GrowrTH OF H. No. 1 IN ALTERNATING TEMPERATURES 
Change of 
Temperature | 2 da. | 3 da. | 4 da. | temperature | 5 da. | 6 da. | 7 da. | 9 da. | 13 da. 
to 
15° 8 18 31 ae 44 58 72 90 
9 19 28 os 39 55 69 90 
Average...... SESS Som 29 oa aMe nae ae 41.5 | 56.5 | 70.5 | 90 
Ree 17 32 48 15° 55 64 69 77 90 
or 18 31 47 . 54 63 71 78 90 
EXVCLALC leis lets CESS Ilan ciscneh seco 54.5 | 63.5 | 70 77.5 | 90 
The transfer to different temperatures made no perceptible difference 
in colony-character other than differences dependent on the rate of growth. 
To ascertain the relation of temperature to the growth of H. No. 1 
on live wheat shoots, this organism was planted as under standard conditions 
(App., page 180), except, of course, that the shoots were not autoclaved. 
Three temperatures, 15°, 20°, and 30° were used. When growth had pro- 
ceeded to completion conidial length was found to be as shown in graphs of 
Fig. G. Conidia-production was scant at 30°, permitting only a few meas- 
urements. At the other temperatures it appeared to be normal. On these 
live shoots there was a marked shifting from the mean to the lower length 
as we passed from 15° to 20°, and a still,more marked shifting at 30° (see 
Fig. G). 
LIGHT 
Two Petri dishes of corn-meal agar were inoculated with H. No. 1 and 
kept in the dark at 25°. In the following table the resulting growth is 
compared with that of similar plates kept in the light. 
In darkness there was slightly less zonation and less aerial mycelium 
than in the light, but the difference was only slight and is probably insig- 
nificant. 
To ascertain whether plate-position is an environmental factor of 
importance, numerous corn-meal agar plates were placed top up, others 
