Treatment of Cotton Seed 
69 
sufficient reduction in the water content of seeds to enable them to endure 
95° for 12 hours, but 50° for 36 hours or 60° for 18 hours gives fairly 
adequate protection. As shown in Part I of these studies on cotton seed 
treatment, the same kind of time and temperature relation holds for the 
death of the anthracnose fungus carried on diseased seed. Heating at 45° 
for 168 hours does not completely free the seed from anthracnose but this re¬ 
sult is fully accomplished by 12 hours of heating at 95°. 
When seeds have been adequately dehydrated before the application of the 
high temperature in the second stage of the anthracnose treatment described 
in Part I of these studies, germination is somewhat more prompt than in 
untreated seeds. This acceleration of germination of treated seeds is not 
conditioned by any wholesome effect of the treatment on the embryos but 
is due entirely to favorable changes in the seed coat which facilitate the 
passage of water to the embryo; for, when naked embryos of comparable lots 
of treated and untreated seeds are compared with respect to promptness of 
germination, the embryos of untreated seeds are seen to germinate more 
promptly than those of treated seeds. When the seed coats are intact, the 
less rapid germination of the embryos of treated seeds is completely masked 
and more than compensated for by the favorable changes which were pro¬ 
duced in the seed coats. The increased permeability of the coats of treated 
seed may be due to the formation of fissures or to the induction of chemical 
changes in the seed coat by the high temperatures used in the treatment. 
When the preliminary desiccation has not been sufficiently great to fully 
protect the seeds from the injurious effects of the higher temperatures used 
in the final stages of the treatment, the seeds show retardation in rate of 
growth and more or less marked reduction in total germination. Less 
severe injury may manifest itself only as an increase in the time required 
for germination. 
Desiccation itself is not responsible for the death of the anthracnose fungus 
carried on diseased cotton seed; for, when infected seeds are thoroughly 
dehydrated at room temperature over chemicals, the fungus actually lives 
longer than in seeds containing a normal amount of water. This increase 
in length of the life of the fungus appears to be conditioned by the pronounced 
loss of water from the seeds and is probably due fundamentally to a decided 
decrease in the already low oxidative and respiratory activities of the 
fungus and seed. This condition of prolonged viability in the uniformly 
dry atmosphere of the desiccators is in harmony with the findings of 
Duvel, 18 who reported that the climate, particularly moisture and tem¬ 
perature of the place where seeds were kept, exerted a marked influence 
on their length of life, and of Tillotson, 58 who reported that seeds of conifer¬ 
ous trees were little if any affected by geographic location and were better 
preserved when kept in air-tight glass jars than when stored in bags or 
other open containers. Moreover, this condition of prolonged viability in 
the desiccators shows that the death of the anthracnose fungus when dis¬ 
eased seeds are treated with dry heat is not due to desiccation, but is to be 
attributed to a more direct effect of the heat, which may act by irreversi¬ 
bly coagulating the fungus protoplasm. That the death of the fungus is not 
due primarily to oxidative changes induced in the fungus protoplasm 
