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

FIBRES, OR SILKEN MATERIAL OF THE PINNA. 177
takes of the form of the member and becomes cylindric, producing
there a tube or pipe in which the canal terminates. The
viscid substance is moulded ui this tube mto the shape of a cord,
similar to the threads produced from it, though much thicker,
and from which all the minute fibres issue and disperse. The
internal surface of the tube, wherein the large cord is formed, is
furnished with glands for the secretion of the peculiar substance
employed in its production, and which is always in gi'eat abun-
dance in this animal as well as in muscles.
Reaumur observed, " that although the workmanship of the
land and sea animals when completed is alike, the manner of
its production is very different. Spiders, caterpillars, &c., form
tlueads of any required length, by making the viscous liquor
of which the filament is formed pass through fine perforations
in the organ appomted for spinning. But the way in which
muscles form their thread is widely opposite ; as the former re-
sembles the work of the wire-drawer*, so does the latter that of
the founder who casts metals in a mould." The canal of the
organ destined for the muscle's spinning is the mould in which
its thread is cast, and gives to it its determinate length.
Reaumur learned the manner of the muscle performing the
operation of swimming by actually placing some of these fish
under his constant inspection. He kept them in his apartment
in a vessel filled with sea water, and distinctly saw them open
their shells and put forth their tongues. They extended and
contracted this organ several times, obtruding it in every direc-
tion, as if seeking the fittest place whereon to fix their threads.
After repeated trials of this kind, the tongue of one was ob-
served to remain for some time on the spot chosen, and being
then drawn back with great quickness, a thread was very
* This remark of M. Reaumur confirms the observations of M. H. Straus, quoted
m Chapter VII. that the thread of the silk-worm is not produced by a simple emis-
sion of liquid matter through the orifices of the spinner, or that it acquires solidity
at once from the drying influence of the air. Indeed, silk cannot be produced in
this manner, but is secreted in the form of silk in silk vessels, and the spinning
apparatus, so called, only unwinds it. Mr. Straus's obsen'ations on this head ad-
mit of no argument. The discovery reduces all that has been heretofore written
upon the subject to the character of old lumber.
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