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

Id2 CULTIVATION AND MANUFACTURE OF SILK.
the line is attached to any black object, for the threads, being
whitish, are, in otherwise, not so easily perceived.
Shooting of the lines.—It has long been considered a
curious though difficult investigation, to determine in what
manner spiders, seeing that they are destitute of wing:^, trans-
port themselves from tree to tree, across brooks, and frecjuently
through the air itself, without any apparant starting point. Ou
looking into the authors who have treated upon this subject,
it is siuprising how Uttle there is to be met with that is new,
even in the most recent. Their conclusions, or rather their
conjectural opinions, are, however, worthy of notice ; for by
tinleaming error, we the more firmly establish truth.
1. One of the earhest notions upon this subject is that of
Blancanus, the commentator on Aristotle, which is partly
adopted by Redi, by Henricus Regius of Utrecht, by Swammerdam*.
l)y Lehmann, as well as by Kirby and Spencet. " The
spiders thread," says Swammerdam, '• is generally made up of
two or more parts, and after descending by such a thread, it as-
cends by one only, and is thus enabled to waft itself from one
height or tree to another, even across running waters ; the
thread it leaves loose behind it being driven about by the wind,
and so fixed to some other body." '-'I placed," says Kirby,
" the large garden spider (£^;jeira diadema) upon a stick about
a foot long, set upright in a vessel containing w^ater
It let itself drop, not by a single thread, but by two, each distant
from the other about the twelfth of an inch, guided, as usual,
by one of its hind feet, and that one apparently smaller than
the other. When it had suffered itself to descend nearly to the
surface of the water, it stopped short, and by some means,
which I could not distinctly see, broke off, close to the spinners,
the smallest thread, which still adliering by the other end to
the top of the stick, floated in the air, and was so hght as to be
carried about by the slightest breath. On approaching a pencil
to the loose end of this line, it did not adhere from mere con-
tact. I, therefore, twisted it once or twice round the pencil, and
then drew it tight. The spider, which had previously climbed
* Swammerdam, part i. p. 24. t Intr. vol. i. p. 415.