IOO 
Journal of Argicultural Research 
Vol. XXI, No. a 
spores. The seeds were germinated in the laboratory in pans 8 inches 
square, covered with glass. Three different lots were always placed on 
the same blotter, one with uninjured seed coats, a second with seed coats 
broken bv a scratch about 2 mm. long over the endosperm, and a third 
with seed coats broken over the tip of the radicle. The latter type of 
injury corresponds to the usual thrashing injury, the protruding tip being 
easily broken off in rough handling of the wheat. There usually were 50 
seeds in each lot, but occasionally only 25. 
After a few days, those seeds injured over the endosperm invariably 
showed masses of fungous hyphae growing from the crack in the seed 
coat. Only a small percentage of such seeds ever germinated, and none 
ever produced a healthy plant. When they did germinate, a deformed, 
spindling plumule might reach a length of a few centimeters before suc¬ 
cumbing. The injury to the roots was less marked, though their devel¬ 
opment always was retarded. The other two lots of seed on the same 
blotter—that is, those with unbroken coats and those with coats broken 
over the embryo—invariably germinated and grew normally without a 
sign of fungous attack on either seed or seedling (PI. 13; 14, A). 
It seemed possible, however, that the apparently immune seeds might 
be susceptible if their germination was retarded, as occurs when seed is 
sown in cold, damp soil. To produce this retardation the experiments 
with Penicillium were repeated in the refrigerator at an average tem¬ 
perature of approximately io° C. In all these experiments the germi- 
nators were removed from the refrigerator to the laboratory after seven 
days. When this was not done the fungi did not develop visibly, on 
account of the low temperature. After being brought to the warmer 
temperature of the laboratory the mycelium developed promptly within 
six days or less. Any seedling growth which had started was quickly 
stopped. This occurred most rapidly and fatally in the seeds broken 
over the endosperm, and least in the unbroken seeds. The deformity 
of the seedlings was extreme. The sheaths broke prematurely and the 
leaves were curled and wrinkled and were brown spotted, especiallv along 
the edges. The roots were short, few in number, devoid of root hairs, 
and brown tipped (PI. 14, B). 
It was found repeatedly in germinations in connection with other 
experiments that seeds which have been injured or killed by treatment 
with opper sulphate, or formaldehyde followed by drying, were easily 
attacked by Penicillium and Rhizopus regardless of the condition of the 
seed coats. After death the embryo, whether protected by an uninjured 
testa or exposed by a broken one, no longe had the immunity it had 
while living. Seeds which were weakened by treatment but which ger¬ 
minated well when sterilized with mercuric cldorid were covered with 
masses of the white, fluffy Rhizopus mycelium whenever germinated 
without previous disinfection. Therefore, along with the experiments 
to determine the relation of seed-coat injury to fungous attack, other 
