The history of silk, cotton, linen, wool, and other fibrous ... - Cd3wd.com

114 CULTIVATION AND MANUFACTURE OF SILK.
close channels through the apartment, where it continually
gives off its heat by radiation ; and the degree of this being
far below the point which is injurious to the vital quality of
air, the evil before alluded to is avoided. If the expense of fuel
be not too great, as compared with that of the labor which
would be saved by this invention, the adoption in silk countries
of such a mode of raising and regulating the temperature
might, probably, prove advantageous.
The silk-worm remains in the form of a chrysalis for periods
which, according to the climate or the temperature wherein it
may be placed, vary from fifteen to thirty days. In India, the
time is much shorter (See Chapter VIII.) ; in Spain and Italy,
eighteen to twenty days. In France three weeks ; and in the
climate of England, when unaccelerated by artificial means,
thirty days wiU elapse from the time the insect begins to spin
until it emerges in its last and perfect form. It then throws off
the shroud which had confined it in seeming l>feless7iess, and
appears as a large moth of a grayish-white color, furnished with
four wings, two eyes, and two black horns or antlers which
present a feathery appearance (See Figure 6. plate III.).
If left until this period within the cocoon, the moth takes
immediate measures for its extrication : ejecting from its mouth
a liquor with which it moistens and lessens tlie adhesiveness
of the gum wherewith it had lined the interior surface of its
dwelling, and the insect is enabled, by frequent motions of its
head, to loosen, without breaking, the texture of the ball ; then
using its hooked feet, it pushes aside the filaments and makes
a passage for itself into light and freedom. It is erroneously
said that the moth recovers its liberty by gnawing the silken
threads ; but it is found, on the contrary, that if carefully un-
wound, their continuity is by this means rarely broken.
One of the most remarkable circumstances connected witli
the natural history of silk-worms, is the degree in which their
bulk and weight is increased, and the limited time wherein
that increase is attained. Count Dandolo, who appears to
have neglected nothing that could tend to the right under-
standing of the subject, and to the consequent improvement
of the processes employed, had patience enough to count and