1907] 



STEVENS— CHRYSANTHEMUM RAY BLIGHT 



247 



The growth both outdoors 

 n the cold, and in the in- 

 cubator, was exceedingly 

 irregular, stunted, or slow, 

 while that of room tempera- 

 ture was very much more 

 rapid. 



In addition to being an 

 unfavorable temperature for 



growth, the heat of the in- 

 cubator produced great irregu- 

 larity in the zonal development ; 

 threads started vigorously, 

 stopped suddenly, and growth 

 began in another direction, so 

 that all regularity of zone 

 formation was lost. Much of 

 the mycelium also became 

 incased in a dark coat, as 

 described under the effect of h 

 cow pea leaf 



agar 



below. 



The plates kept at outdoor 

 temperature, while they main- 

 tained a fair regularity in the 

 formation of zones, did not 



? 



make the same number of 



zones as the cultures kept at 

 room temperature, the number 

 of zones made in the room 

 temperature being six while 

 that outdoors was four. 



Acid relation. — Cultures in 

 lettuce agar in the dark at 

 room temperature in various 

 degrees of acidity gave the 

 record shown on Table II on 

 the following page : 



o 



CQ O 



< ^ 



06" 



o 



o 



o 



o 



d U 



00 



so 



»o 



to 



V 



Q 



O 



XT) 







I 



00 



m 10 



O 





00 



04 CC 00 



N 10 10 



00 



o 



M M 



N 



O 



1 



w 



I 



•* fO 



I 



M W 





S : 





10 



CI 





10 



00 



-g 



c 



6 

 I 



rO ro 



rn ro 



U 



o 



PI 



M 



3 

 o 



o 

 in 



I 

 O 



fO tn'-o 



I 



I 



o 



I 



I 



01 o^ 



^ 



o o 





M H M 







O 





vO 



^0 



<o 



^ 



00 



o< w 



> 



o o 



c 



e 



E 



p 4^ a> 



H-i - >? 



=3 C-*P^Ph 



o 



