Pee ORT TE: 
EXPERIMENTS UPON THE EFFECT OF COLD APPLIED TO CHRYS- 
ALIDS OF BUTTERFLIES. 
BY WILLIAM HENRY EDWARDS, COALBURGH, W. VA. 
(Continued from p. 6.) 
With every experiment, however similar 
the conditions seem to be, and are intended 
to be, there is a difference in results, and 
at present the reason therefor does not ap- 
pear. For example, in 1878, the first but- 
terfly emerged on 14th day after removal 
from the ice, the period being exactly what 
it is at its longest in this species in nature, 
with an occasional exception. Others 
emerged at 19 days and several at inter- 
vals up to the 96th day after ice. In 
1879, the emergence began at 8 days, and 
by 12 days all which came out this year 
had appeared, except three belated indi- 
viduals at 22,40 and 50 days. In previous 
experiments, no matter what the species, 
the butterflies had not emerged till after 
the natural period of the chrysalis had 
passed, after removal from the ice. In 
this one, either the cold had not fully sus- 
pended the changes which the pupa under- 
goes in the chrysalis, or these changes 
were hastened by some other cause after 
the chrysalids were taken from the ice. 
In the first experiment, apparently, the 
changes were absolutely suspended as long 
as the cold remained. 
It might be supposed that the application 
of heat to the overwintering chrysalids 
would precipitate the appearance of the 
summer form of P. ajaz, or change the 
butterflies suv that while they had the shape 
of telamonides they should have the color- 
ation of marcellus. But I have not found 
I have been in the habit, 
for several years, of placing the chrysalids 
this to occur. 
in a warm room or in the greenhouse, early 
in the winter, so causing the butterflies to 
emerge in February, instead of in March 
and April, as they would otherwise do. But 
the winter form has invariably emerged 
from such chrysalids. 
3. In June 1879, I obtained eggs of 
Grapta interrogationis, laid by form wm- 
brosa, in confinement. As the chrysalids 
formed, and at intervals of from 6 to 24 
hours after pupation, they were placed in 
the ice box. After 14 days I removed all 
but five, which were left 6 days longer. 
Several were dead at the end of the 14 
days. ‘Temperature most of the time about 
35° F. [1°.7 C.], but a little higher for a 
few hours each day, as the ice melted, reach- 
