110 
Journal of Agricultural Research 
Vol. XXIX, No. 3 
The temperature curves for Winesap 
apples packed in a barrel are presented 
in Figure 2. The room temperature 
was kept as near 25° F. as possible 
although some unavoidable variations 
occurred. It will be seen that the 
temperatures in all parts of the barrel 
drop rather rapidly at first, and when 
freezing begins the curves flatten out 
and the temperatures remain fairly 
constant for considerable periods of 
time with wholly insignificant varia¬ 
tions. Undoubtedly this is the freez¬ 
ing point of the apples, not only a 
somewhat composite one for the par¬ 
ticular fruit in which the thermocouple 
is inserted, but one influenced by the 
fact that adjacent apples are also 
The visual injury to the fruit used in 
these experiments was not quantita¬ 
tively determined; but apples with 
severe visual injury were found through¬ 
out different parts of the barrel. Proba¬ 
bly these apples froze comparatively 
early in the period of exposure, since 
it has been shown that in general there 
must be a rather considerable tempera¬ 
ture difference between their freezing 
point and the temperature at which 
injury commences. It is suggested 
that the heat of fusion given off by the 
early ice crystallization in these scat¬ 
tered apples may be sufficient to raise 
the temperature of any particular barrel 
location so as to delay the time of ice 
formation in other apples. In other 
freezing. The heat of fusion produced 
by ice crystallization in these apples 
diffuses into the air spaces between 
them, mutually affecting the heat 
gradients existing between the exterior 
and interior tissues. Upon this heat 
gradient, which is itself a complex of 
other factors, depend the rate of further 
crystallization, the path of temperature 
curves, and even the injury and death 
of the tissues. It is a problem of great 
complexity and can be but briefly con¬ 
sidered here. 
It should be noted that there is no 
evidence of undercooling in the path 
of the temperature curves for the apples 
in the barrel. This does not mean that 
individual apples do not undercool 
under such conditions, for there is 
much reason to assume that they do. 
words, some apples may be frozen, 
and the heat they give off during the 
process tends to delay the freezing of 
others. 
The paths of the temperature curves 
for apples exposed in packages to low 
temperature generally show compara¬ 
tively little undercooling before freez¬ 
ing commences. At any rate it has 
not been possible to carry the under¬ 
cooling to the degree to which it has 
been shown to occur in isolated apples, 
surrounded on all sides by cold air, 
when these are not disturbed. 
The data show further that the bot¬ 
tom and sides of the barrel cool most 
quickly, the top remains warm longest, 
and the center fruit in the barrel is 
intermediate in the rate of cooling. 
This is logical, since the heated air 
