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. 



GROWTH OF H. No. 1 IN ALTERNATING TEMPERATURES 



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 



