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

DESCRIPTION OF THE SILK-WORM. 105
a quarter of an inch in length. Its first indication of anima-
tion is the desire which it evinces for obtaining food, in search of
which, if not immediately supphed, it will exhibit more power
of locomotion than characterizes it at any other period. So
small is the desire of change on the part of these insects, that
of tlie generaUty it may be said, their own spontaneous will
seldom leads them to travel over a greater space than three
feet throughout the whole duration of their Mves. Even when
hungry, the worm still clings to the skeleton of the leaf from
which its nourishment was last derived. If, by the continued
cravings of its appetite, it should be at length incited to the ef-
fort necessary for changing its position, it will sometimes wander
as far as the edge of the tray wherein it is confined, and
some few have been found sufficiently adventvuous to cling to
its rim ; but the smell of fresh leaves will instantly aUure them
back. It would add incalculably to the labors and cares of
their attendants, if silk-worms were endowed with a more rain-
bhng disposition. So useful is this pecuharity of their nature,
that one is irresistibly tempted to consider it the result of design,
and a part of that beautiful system of the fitness of things,
wliich the student of natmal history has so many opportunities
of contemplating with delight and admiration.
In about eight days from its being hatched, its head becomes
perceptibly larger, and the worm is attacked by its first sickness.
This lasts for three days ; during which time it refuses food,
and remains motionless as in a kind of lethargy. Some have
thought this to be sleep, but the fatal termination wliich so
frequently attends these sicknesses seems to afford a denial to this
hypothesis. Tl>e silk-worm increases its size so considerably,
and in so short a space of time,—its weight being multiplied
many thousand fold in the course of one month,—that if only
one skin had been assigned to it, which should serve for its
whole caterpillar state, it would with difficulty have distended
itself sufficiently to keep pace with the insect's growth. The
economy of nature has therefore admirably provided the em-
bryos of other skins, destined to be successively called into use ;
and tliis sickness of the worm, and its disincUnation for food,
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