70 Psyche [April 
All four boxes were sunk into the ground about three centimeters 
deep in an entirely open and unprotected place where they were al- 
lowed to remain. Snow and water were allowed free admittance to 
the eggs, but care was taken to allow the water to run off to a slight 
extent by means of a few very small holes which were cut in the bottom 
of the boxes. 
A self-registering thermometer used recorded —21.5° C. as the 
lowest temperature of the winter 1908-09. 
During the latter part of May, 1909, the caterpillars from the eggs of 
all the series began to hatch simultaneously. An examination made of 
all eggs which failed to hatch showed that all parts of the individual 
egg clusters presented about the same very small proportion of empty, 
dead or dried eggs, in each case a percentage of 5-S%. 
The first result obtained which deserves notice, is the fact that the 
series of eggs which were deprived of their protecting hairs and passed 
the whole winter in glass dishes, withstood the cold just as successfully 
as those which had overwintered on a piece of wood covered with 
hairs in the normal way. If in Kulagin’s experiment, the depilated 
eggs died which were exposed to the winter temperature for only one 
month in a glass dish probably the stated maximum temperature of 
-15° R. was more frequently reached, as Kulagin says himself, and 
perhaps also the temperature remained more constant. A continuous 
low temperature, however, did not occur in this locality during the 
winter of 1908-09, during which the temperature often fell very low 
but always rose again. It appears from this that the dispar eggs, 
from which the woolly covering has been removed, can withstand quite 
severe cold without injury, provided that this temperature does not 
endure too long. Or perhaps may it be that the woolly covering of the 
eggs laid by the female dispar, which withstand the very cold winter 
of Russia is stronger and thicker than we find here? If this be the 
case, the depilated eggs of Russian masses should exhibit a slighter 
resistance, for the eggs on account of the thick covering should be less 
accustomed to cold. 
How very resistant the dispar eggs may be to the various influencing 
factors of the winter, is shown by the last two series of experiments, 
in which even depilated eggs withstood snow and water as well as low 
temperature without damage. ‘lo consider the practical application 
of these experiments, it appears that dispar eggs which have been 
removed from their normal location through some accident and have 
