18 Nebraska Agricultural Exp. Station Research Bul. 1(> 
appeared to be a solid frozen mass. The open spaces in and 
around the embryo also appeared to be enlarged by the ice 
formation. 
Usually where ice was formed in the kernels, and remained 
in a frozen condition for practically 2d hours, the vitality was 
destroyed or weakened. In a few cases, however, ice was noted 
and still the vitality of the kernel remained unimpaired. Ice 
formation within the kernel, therefore, even when a coat is 
formed around or partly around the embryo, does not neces- 
sarily mean death. The retention of life depends quite largely 
upon the duration of the frozen condition. Data regarding the 
relation between ice formation and injury are given in Tables 
5 to 12. In cases where the freezing was severe, frozen kernels 
were left in a soft, watery condition after thawing. The cells 
seemed to be unable to absorb the water which had been drawn 
from them during the freezing process. 
EFFECT OF FREEZING ON COLOR OF EMBRYO 
The embryo in a kernel of immature or moist corn usually 
changes from a light or creamy color before freezing to a dark 
or yellowish brown after freezing. The larger the percentage of 
moisture, the more sensitive the embryo to cold, and the more 
readily discoloration takes place. Corn containing 87 per can', 
moisture and frozen three days at 0° F. showed a slight embryo 
discoloration in three days and very pronounced darkening in 
six days after thawing. By looking over the notations regard- 
ing embryo color in Tables 5 to 12. it will be seen that the dark 
color is very closely correlated with loss of vitality. Generally 
where no loss of vitality resulted from the exposure to the cold, 
the embryo retained its normal color. The presence of both 
dark and light embryos on the same ear is associated usually 
with only a partial loss of vitality, and is frequently due to 
variation in moisture content of the kernels. 
The practice of judging the germinative power of seed 
corn bv the appearance of the embrvo therefore se°ms justified. 
Alien loss of vitality has resulted from freezing, this seems to 
be a fairlv safe guide. However, it seems possible that. :<n 
verv exceptional cases, a loss of vitality might result from some 
otluT source without causing a discoloration of the embrvo. The 
method, therefore, can hardly be said to take the place of a 
germination tost. 
EFFECT OF FREEZING ON EMBRYONIC TISSUES 
Since ice is formed in kernels of immature corn when 
exposed sufficiently to freezing temperatures, often resulting in 
