tg2t] HARRINGTON—GERMINATION 351 
than at 17.5°C. Exposure to 30° for only a few hours each day, 
therefore, had a retarding effect on germination even during the 
early days of the test. 
A few cases of apparent influence of temperature upon germina- 
tion require special mention. California poppy seeds germinated 
much more rapidly and somewhat more completely when the 
chamber was heated to 30° and allowed to cool very slowly to 
room temperature than with any of the other conditions of either 
—#00 ) 
20 : 150°C 
cane 
kK 70 me 
YAS C 
, 60 RY, ——_ 977 sav te boa RB 
& 50 yA poae 
. ¢ 
© 20 &/ 
2age 
eae ¥ bs 
Ss I 
Fic. 8.—Average rate of germination of three lots of larkspur seeds 
constant or alternating temperatures used in the series of tests 
made in 1912. 
The cypress seeds were infected with a “‘damping-off’’ organism, « 
which destroyed some of the germinated seeds almost as soon 
as germination began in the tests which were conducted at high 
temperatures. Some of the nasturtium seeds were badly infected 
with organisms of decay and with parasitic nematodes, which 
affected germination more seriously at the higher than at lower 
temperatures. To avoid difficulties of this kind, so far as possible 
all sorts of seeds should be tested at temperatures as low as are 
