86 
EFFECT OF EXTERNAL CONDITIONS. 
The influence of vaiying temperatures on the 'length of the pupal 
stage is exceedingl}^ interesting and instructive, the pupa being appar- 
ently much more uniformly aflected than the other stages. This is 
evident from the close agreement between the sums of effective tem- 
peratures given in the preceding table. 
On July 20, 190^, three recently formed pupa^ were placed in the 
laboratory ice box and left there for thirty-tive days at a temperature 
averaging about oT'^ F. They then showed no signs of emerging and 
were removed to the temperature of the laborator}^ where the moths 
appeared after from five to eight days. They must have been develop- 
ing slowly in the refrigerator, as the seven da3's during which they had 
been at normal temperatures would not otherwise have been sufficient 
-fordevelopment. Calculations based on this experiment compared 
with several other lots of pupa? that developed at normal temperatures 
show that development is apparentlj^ almost prevented by low tem- 
peratures and suggests that the growth of the pupa is determined with 
reference to a higher temperature than the i3^ F. usualh" chosen. 
This is shown as follows: 
Table XXXIII. — Effective temperatures for pajxd development. 
Length of stage. 
Sums of effective temperatures. 
Above 43°. Above 58°. Above 60°. 
Mav 9 to 13 
June 10 to 24... 
September 29 to October 23 
Ice-box experiment 
662 
530 
724 
1.341 
317 
349 
359 
271 
275 
300 
308 
It will be noted that the sums are more nearly equal when 58° or 60° 
are assumed to mark the inception of metabolic activity. 
During September, 1904, the influence of extreme cold was tried in 
two cold-storage vaults at temperatures of 34:^, 27°, and 18°, respec- 
tivel}'. The results obtained are tabulated below: • 
Table XXXIV. — Effect of low temperature on pup x. 
Larvae in cells. 
Pupse in loose earth. 
Temperature conditions. 
Total. 
Moths 
emerged. 
Re- 
mahi- 
ed— 
live 
pup0e. 
Mor- 
tality. 
Total. 
Moths 
emerged. 
Re- 
main- 
ed- 
live 
pupse. 
Mor- 
Per- 
fect. 
De- 
formed. 
Per- 
fect. 
De- 
formed. 
tality. 
A. Placed at 34° for 48 
hours 
19 
23 
21 
4 
4 
12 
1 

4 
1 
3 
Percent. 
58 
74 
29 
14 1 2 
14 
14 0' 
1 





Percent. 
79 
B. Placed at 34° for 24 
hours, then at 27° 
for 96 hours 
100 
C. Placed at 34° for 24 
hours, 27° for' 24 
hours, then 34° for 
72 hours 
100 
