M U S 
no injury, and could throw out their threads to 
as great diftances ? The experiment proved the 
truth of the conjedure ; for thofe whofe beards, 
or old threads, were amputated, fixed themfelves 
as foon as thofe in which they were left, and 
fpread their threads to as great diftances in every 
diredlion. 
The mechanifm of this manufafture being Jo 
far underrtood, it now became natural to enquire 
into the properties of the member by which it 
was performed; and it was difcovered, that 
though, from it's appearance, it might be con- 
fidered as the tongue or arm of the fifh, it was 
more properly denominated the organ by which 
the threads are fpun. 
Though this organ is flattened like a tongue 
for a confiderable part of it's length, it is never- 
thelefs rounded, or cylindric, at the bafe or in- 
fertion; and is much fmaller there than in any 
other part. Several mufcular ligaments are 
faftened to it about the bafe, which hold it 
firmly againft the middle of the back of the fhell ; 
and of thefe ligaments four are particularly per- 
ceptible, which ferve to move the body in any 
direction. Along this body there runs a flit or 
crack, which pierces very deeply into it's fub- 
ftance, and divides it into two longitudinal fec- 
tions: this is properly a canal, along which is 
thrown the liquor which ferves to form the threads; 
and it is in this paflage or flit that thefe threads 
are moulded into their proper form. This canal 
is regularly carried on from the tip of the organ 
to it's bafe, where it becomes cylindric; which 
cylinder, in this part, is no other than a clofe 
tube or pipe, in which the open canal termi- 
nates. The cylindric tube contains a round ob- 
long body, of the nature of the threads, except 
that it is much larger; and from the extremity 
of it all the threads are produced ; this ferving as 
a large cable to which all the other little cords, 
difperfed towards difi'erent parts, are affixed. 
The tube or pipe in which this large thread is 
lodged, feems to be the rcfervoir of the liquor 
from whence the other threads are formed; it's 
whole internal furface being furnifhed with glands 
for it's fecretion. 
The Mufcle, like many other marine fiflies, 
abounds with this liquor; and if at any time a 
perfon touches the' bafe of the fpinning organ 
with his finger, it draws away with it a vifcous 
liquor in form of the caterpillar's threads, Thefe 
threads fix themfelves with equal eafe to the mofl: 
fmooth and gloflTy as to rougher bodies ; for if 
Mufcles are kept in glafs jars of fea-water, they 
adhere to the glafs as firmly as to any other body. 
It is not as yet afcertained v/hether the Muf- 
cle poflTefles a power of difengaging it's threads 
from the body to which they are fixed, and of 
removing from the place where it originally took 
up it's refldence : however, it appears proba- 
ble, that it remains where it once faftened itfelf, 
though it's deftrudlion fliiould be the confequence. 
Reaumur tried this experiment in his jars : when 
the Mufcles had clolely adhered to their fides, 
he poured off part of the falt-water, fo that it then 
appeared neceflfary for the fifli to quit their hold, 
and defcend lower; but of efi^efting this they 
feemed not to pofl^efs any faculty. 
The Mufcle afib^'ds the curious obferver a 
very pleafing objed of microfcopical examina- 
tion. The tranfparent membrane, which imme- 
diately appears on opening the fliell, exhibits the 
Vol. IL 
MUS 
circulation of the blood, for a long time toge- 
ther, through an amazing number of veflTels. ^In 
feveral diflTedled by Lecwenhoeck, that naturalift 
difcovered numbers of eggs and embryos in the 
ovarium, all lying with their fl-iarp ends faftened 
to the ftrings of veffels by which they received 
nourifhment. The minute eggs, or embryos, 
are placed by the parent in very clofe arrange- 
ment on the outfide of the fliell, to which they 
adhere very firmly, continually increafing in fize, 
till becoming perfed Mufcles, they drop off^, 
and provide for themfelves by means of the in- 
ftinfts peculiar to the race. 
Muscle, Great. This fpecies has a ftrong 
fliell, blunt at the upper end; one fide angulated 
near the middle, and from hence dilating towards 
the end, which is rounded. It is the largeft of 
all Britifti Mufcles, often meafuring feven inches 
in length: it lies at great depths in the fea; and 
generally feizes the bait of the ground- lines, 
whereby it is often drawn up. 
Muscle, Duck. The fliell of this fpecies is 
lefs convex and more oblong than that of the 
common kind, very brittle, and femi-tranfpa- 
rent. It's length is about five inches, and it's 
breadth about two and a quarter. It is found 
in frefli waters ; and frequently affbrds a repaft 
to the crow; which, when the fliell proves too 
hard for it's bill, flies aloft, and drops it on fome 
rock, whereby it is fraftured ; and the meat is 
then picked out with facility. 
Muscle, Swan. This fpecies has a thin brittle 
fliell, very broad and convex, and marked with 
concentric ftrise. It is attenuated towards one 
end, and dilated towards the other. The colour 
is a dull green; the length is fix inches; and the 
breadth three and a half. It inhabits frefli waters ; 
and fometimes contains pearls. 
Muscle, Pellucid. The fhell of this fifli 
is delicately tranfparent, and longitudinally rayed 
in a very elegant manner with purple and blue. 
It feldom exceeds two inches in length; and is 
fometinaes found in oyfter-beds. 
Muscle, Horse. A common Englifli appel- 
lation for the frefli-water Mufcle, a large fpecies 
of fhell-fifli very common in our fifli-ponds. A 
member of the Academy of Paris, who has made 
a number of curious obfervations on this animal, 
remarks, that they are all hermaphrodites; and 
that, by a ftrange method of generation, each indi- 
vidual is capable of propagating it's kind, and an- 
nually does fo without the intercourfe of any other. 
The fliell of the frefli-water Mufcle is com- 
pofed of feveral laminse or beds of matter, and 
internally lined with an extremely delicate and 
thin membrane, not eafily perceptible while the 
fliell is recent ; but when it becomes dry, ufually 
feparates, and peels wholly off. The fiili opens 
and fhuts it's fhell by a very ftrong hinge, afllfted 
by two ftrong mufcles; the contradlion of thefe 
fliuts the fhells firmly together, and a powerful 
fpring or native force in the animal opens them 
again at pleafure. The part which performs this 
office is diftintfly feen on the back of thefiflij 
and is an inch and a half long, and about the 
flxth of an inch wide. 
MUSCULUS MYSTICATUS. A name 
given by Gefner, and fome other authors, to the 
common whale. Artedi diftinguiflries this from all 
other cetaceous fiflies, by the name of the Whale 
with thefiftule in the middle of the head, and with 
the back fharp towards the tail. 
a H MUSE. 
