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

FIBRES, OR SILKEN MATERIAL OF THE PINNA. 175
The Pinna is a bivalve* shell-fish, which, when full grown,
is IS inches long, and G wide at its broad end. It is found
near the shores of South Italy, Sicily, Corsica, and Sardinia
also in the Bay of Smyrna, and in the Indian Ocean, It does
not fasten itself to rocks in the same position as the muscle, but
sticks its sharp end into the mud or sand, while the rest of the
shell is at Uberty to open in the water. In common with the
muscle, it has the power of spinning a viscid matter from its
body, conformably with that of the spider and caterpillar. Al-
though the pinna is vastly larger than the muscle, its shell be-
ing sometimes found two feet long, the threads which it produ-
ces are more dehcate and slender than those of the muscle, be-
ing in fineness and beauty scarcely inferior to the single filament
of the comparatively minute silk-worm. Threads so delicately
thin, as may readily be imagined, do not singly possess much
strength ;
but the httle power of each is made up by the aggre-
gate of the almost infinite number which each fish puts forth
to secure itself in a fixed situation, and preserve it against the
rolling of the waves. The threads are, however, similar in
their nature to those of the muscle, differing only in their supe-
rior fineness and greater length. These fish have, therefore,
been distinguished by some naturalists, the one as the silk-
worm, the other as caterpillar of the sea.
It has been from a very remote period well known, that mus-
cles have the power of affixing themselves either to rocks or the
shells of one another, in a very firm manner ;
yet their method
of effecting this was not understood until explained by the accu-
rate observations of M. Reaumur, the first naturalist who as-
certained that if, by any accident, the animals were torn from
their hold, they possessed the power of substituting other threads
for those which had been broken or injured. It was found by
him, that if muscles, detached from each other, were placed in
any kind of vessel and then plunged into the sea, they con-
trived in a very short time to fasten themselves both to the
vessel's side and one another's shells : in this process, the ex-
* An animal having two valves, or a shell consisting of two parts which open
and tsliut.
;