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

DESCRIPTION OF THE SILK-WORM. 115
weigh many hundred thousand eggs, as well as follow out to
the ultimate result his inquiries respecting their produce. He
found that on an average sixty-eight sound silk-worm's eggs
weighed one grain. One ounce*, therefore, comprised, 39,168
eggs. But one twelfth part of this weight evaporates previous
to hatching, and the shells are equal to one fifth more. If,
therefore, from one ounce, composed of 576 grains, 48 grains be
deducted for evaporation, and 115 for the shells, 413 grains
will remain equal to the weight of 39,168 young worms ;
and,
at this rate, 54,526 of the insects when newly hatched, are
required to make up the ounce. After the first casting of the
skin, 3840 worms are found to have this weight, so that the
bulk and weight of the insects have in a few days been multi-
plied more than fourtee7i times. After the second change 610
worms weigh an ounce, their weight being increased in the in-
termediate time six fold. In the week passed between the sec-
ond and third ages, the number of insects required to make up
the same weight, decreases from 610 to 144, their weight be-
ing therefore more than quadrupled. During the fourth age,
thuty-five worms now
a similar rate of increase is maintained :
weigh an ounce. The fifth age of the caterpillar comprises
nearly a third part of its brief existence, and has been describ-
ed, by an enthusiastic writer on the subject, as the happiest
period of its hfe, during which it rapidly increases in size, preparing
and secreting the material it is about to spin. When
the silk-worms are fully grown, and have arrived at their period
of finally rejecting food, six of them make up the weight of
an ounce. They have, therefore, since their last change, again
added to their weight six fold.
It is thus seen that, in a few short weeks, the insect has
multiplied its weight more than nine thousand fold ! From
this period, and during the whole of its two succeeding states
of being, the worm imbibes no nourishment, and gradually di-
minishes in weight ; being supported by its own substance, and
* This ounce contains 576 grains ; 8.5325 of these grains equal seven grains
troy. One ounce avoirdupoise is therefore equal to about 533 grains, and between
11-12 and 11-13 ounce avoirdupoise equals one of the above ounces.