60 _ PHYSIOLOGY OF THE EGGS 
to hatch them in less than a month, by carrying 
the eggs in their bosoms. 
Kirby and Spence assert, that “ to retard their 
hatching with particular views is in any cireum- 
stances impossible. When the heat of the atmo- 
sphere has reached a certain point, the hatching 
cannot be retarded by cellars; and M. Faujas has 
remarked, that in time the Silkworm’s eggs would 
hatch in an ice-house.” * 
Contrary to the above assertion, in one instance, — 
and indeed the only time I ever tried the experiment, 
—I found that, by placing the eggs of a Silkworm 
Moth in a cold damp cellar, they were kept from 
hatching from the year 1818 till the year 1820, 
when they were exposed to the sun’s heat, which 
speedily brought them to the larva state. Young, 
in his History of France, states, that no art will 
hatch the eggs of the common Silkworms the first 
year, or that in which they are laid; but that 
there is a species brought from Persia, which are 
hatched three times a-year, and which will break 
from the egg in fifteen days, under a proper tem- 
perature. But it is stated, as a circumstance out 
of the ordinary laws of Nature, that in the year 
1765, the common sort hatched in the first year. 
In some species, the caterpillar is some hours in 
extricating itself from the shell at hatching. In the 
“ Introduction to Entomology, iii. p. 102. 
