172 
Journal of Agriculutral Research 
Vol. XXXI, No. 2 
to assume that the lower the temperature of the cooling chamber 
the more heat will be absorbed by radiation when the insect rebounds. 
The lower the insect supercools the lower will be the point to which 
the heat of crystallization available to the thermocouple will enable 
the temperature to rise, or, in other words, the lower will be the 
point of rebound. If this is true the correlation between supercool¬ 
ing and rebound points is simply due to the amounts of radiation 
being related to the temperature of the cooling chamber. What¬ 
ever the explanation may be, the fact of the existence of this corre¬ 
lation seems to have been demonstrated. 
RELATION BETWEEN SUPERCOOLING AND THE RATE AT WHICH THE INSECT WAS 
COOLED 
Bachmetjew expressed the belief that possibly there may be a 
relationship between the rate at which the insect is cooled and the 
supercooling point. His “ abkuhlunggeswindigkeit ” is described as 
a “shadow in the background.” 
Figure 3, A, B, and C, are dot charts wherein the supercooling 
points have been plotted against the rate at which the insect was 
cooled. In computing these rates the time taken to bring the insect 
from 0° C. to the supercooling point was used in order that the rates 
could all be calculated from a common starting point, as the initial 
temperature of the bath varied. The coefficients of correlation and 
the probable errors for the three stages are as follows: 
Coeffi¬ 
cients 
Probable 
errors 
Adults__ 
-0.095 
- .190 
+ .015 
0.138 
.129 
.134 
Pupae_ 
Larvae____ 
It is thus seen that the rate of supercooling has no part in estab¬ 
lishing the temperature of supercooling; the coefficient is less in 
each case than the figure required to establish even a bare relation¬ 
ship. It might be added here that the data for larvae offer the best 
opportunity for verifying this phase of the question. Previous to 
obtaining the latter half of these data the suction of an ordinary tap 
pump was used to cool the ether, and differences in rate were slight. 
Later, a suction pump was obtained which reduced temperature very 
rapidly, so that there is a much greater variation in the rates. 
EXPERIMENTS ON THE UPPER LIMITS OF LOW TEMPERATURES 
FATAL TO BRUCHUS OBTECTUS SAY 
HISTORICAL 
Garman (6) subjected weevils to outside temperatures. These 
are presumably mean temperatures for the periods stated. His 
general conclusion was that a temperature of about 0° F. for a period 
of 24 hours was a complete control. According to the data of this 
paper the eggs are most resistant and the larvae least resistant. This 
writer suggests that the reason for the freedom of Canadian-grown 
seed from infestation is due to the inability of the weevils to survive 
the rigor of the winter. Sanderson (15, 16) discusses this subject 
in some detail for insects generally. 
