58 
C. Experiment Station 
of 80 to 95°, which are ordinarily harmful but are necessary to kill the 
anthracnose fungus. The loss of moisture by the seeds has been determined 
for the different stages of the treatment. The resistance of the treated 
seeds increased with increase in temperature and time of desiccation and 
is correlated with and dependent upon the loss of water during the period 
of desiccation. The reduction of the water content of seeds to 3.19 per 
cent of their dry weight fully prepares them to survive the temperature of 
95° for 12 hours, such seeds germinating as completely and somewhat more 
promptly than untreated seeds. The acceleration in the rate of germination 
resulting from the treatment of properly desiccated seeds at 95° may be 
attributed to the effect of the treatment on the seed coats. When the pre¬ 
liminary desiccation has not been sufficiently great to fully protect the 
seeds from the injurious effects of the higher temperatures used in the final 
period of heating, the seeds show retardation in the rate of growth and more 
or less marked reduction in the total germination. Less severe injury may 
manifiest itself only as an increase in the time required for germination. 
This finding agrees with that of Nobbe, 44 Just, 39 Saillard, 47 Haberlandt 29 
Holinel, 34 Dixon, 16 , 17 Stormer, 55 , 56 Tapke, 37 and Crocker and Groves, 10 who found 
that temperatures near the maximum increase the time needed for germi¬ 
nation. 
EFFECT OF STORING DISEASED COTTON SEED OVER DESICCATING CHEMICALS 
When it was learned in the early part of these studies with diseased 
cotton seed that the percentage of seeds carrying viable elements of the 
anthracnose fungus can be greatly reduced by use of dry heat, the question 
was raised whether the death of the anthracnose fungus is a result of the 
excessive loss of water while the seeds are being treated or is due primarily 
to a direct effect of heat. Is the withdrawal of water during the treatment 
sufficiently great in itself to produce fatal disruption of vital organization 
in the fungus protoplasm or is this permanent loss of vitality to be at¬ 
tributed to a direct, perhaps coagulating, effect of the heat on the living 
substances of the fungus? In order to arrive at an answer to this question, 
certain experiments were performed to determine the effect of removal 
of water from the diseased seed by desiccation over chemicals. Diseased seed 
of the 1919, 1920 and 1921 crops were stored over concentrated H 2 S0 4 and 
dry Ca0 2 in desiccators. The lids of the dishes were sealed with pe¬ 
troleum jelly and clamped down to prevent entrance of air from the out¬ 
side. The dishes were kept at room temperature on a shelf of the general 
laboratory. Seeds were taken from these dishes from time to time and 
tested in the usual way for germination and anthracnose. In order to keep 
record of the degree of desiccation attained by the seeds, a small quantity 
of seed was sewed in a small cheese-cloth bag and stored in each desic¬ 
cator. The weight of the bag and of the seed enclosed by it were deter¬ 
mined at the beginning of the experiment. Each time seeds were removed 
from the desiccators for testing, the bag and seeds were again weighed 
and the amount of water lost by the seeds was recorded. 
