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MUSCLE. 
its station with the object of its aim. It 
is one of the most silent and' most familiar 
of summer birds. Its only note is a plain- 
tive sound on the approach of danger. In 
Kent it is called the cherry-sucker, being 
particularly fond of that fruit. 
M. atricapella, or the pied fly catcher, 
is not to be found in great numbers in any 
part of this island, but is most frequently 
to be met with in Yorkshire, and the con- 
tiguous counties. A nest belonging to 
two birds of this species was taken in 1803, 
in Axwell Park, with a great number of 
young, and also the parent birds. The 
assiduity of the latter which were almost 
itnremittedly employed in taking flies for 
their numerous family, was highly interest- 
ing. The dexterity and attention of the 
mate bird ap)>eared most conspicuous. See 
Aves, Plate X, fig. 3. 
MUSCLE, in anatomy, a part of the hu- 
man body, destined to move some other 
part, and tliat in general by a voluntary 
motion, or such as is dictated by the will; 
being composed principally of flesh and ten- 
dinous fibres, which have also vessels of all 
kinds, as arteries, veins, nerves, and lym- 
phatics ; all which are surrounded by, or 
enclosed in, one common membrane. See 
Anatomy. 
In a chemical vie w, the muscular parts of 
animats are known in common language by 
the name of flesh. They constitute a con- 
siderable proportion of the food of man. 
Muscular flesh is composed of a great num- 
ber of fibres and threads, of reddish or 
whitish colour ; these, after they have been 
acted on by water, in order to separate the 
extraneous matter from them, are left in 
the state of grey fibres, insoluble in wa- 
ter, and becoming brittle when dry. The 
substance possesses all the properties of 
Fibrin, which see. Besides fibrin, they 
are found to contain albumen, gelatine, 
extractive, phosphate of soda, of ammonia, 
and lime. 
The muscles of different animals differ 
exceedingly from each other in their ap- 
pearance and properties, at least as articles 
of food ; but we know little of their che- 
mical differences. The observations of 
Thouvenel alone were directed to that ob- 
ject, and they are imperfect. The flesh of 
the ox contains, according to him, the 
greatest quantity of insoluble matter, and , 
leaves the greatest residuum when dried ; 
llie flesh of the calf is more aqueous 
and mucous ; the land and water turtle 
yields more matter to water than the mus- 
cle of the ox ; but Thouvenel ascribe.s 
the difference to foreign bodies, as liga- 
ments, &c. mixed with the muscle of the 
turtle. Snails yield to water a quantity of 
matter intermediate between that given by 
beef and veal ; with them the muscles of 
frogs, Cray fish, and vipers, agree nearly in 
this respect ; but the muscles of fresh water 
fish, notwithstanding their softness, yield a 
considerably smaller proportion. When 
meat is boiled, it is obvious that the gela- 
tine, the extractive, and a portion ot the 
salts will be separated, while the coagulated 
albumen and fibrin will remain in a solid 
state. Hence the flavour and the nourish- 
ing nature of soups derived from the ex- 
tractive and gelatine. When meat is roast- 
ed, on the other hand, all these substances 
continue in it, and the taste and odour of 
the extractive is greatly heightened by the 
action of the fire. Hence the superior fla- 
vour of roasted meat. Fourcroy supposes, 
that the brown crust which forms on roasted 
meat is composed entirely of the extrac- 
tive. The cutis is a thick dense membrane, 
composed of fibres interwoven like the tex- 
ture of a hat. When it is macerated for 
some hours in water, and agitation and 
pressure are employed to accelerate the 
effect, the blood, and all the extraneous 
matter with which it was loaded, are sepa- 
rated from it, but its texture remains unal- 
tered. On evaporating the water employ- 
ed, a small quantity of gelatine may be 
obtained. No subsequent maceration in 
cold water has any further effect. When 
distilled, it yields the same products as 
fibrin. The concentrated alkalies dissolve 
it, converting it into oil and ammonia. 
Weak acids soften it, render it transparent, 
and at last dissolve it. Nitric acid converts 
it into oxalic acid and fat, while, at the 
same time, azotic gas and prussic acid are 
emitted. When heated it contracts, and 
then swells, exhales a fetid odour, and leaves 
a dense charcoal, difficult to incinerate. 
By spontaneous decomposition in water or 
moist earth, it is converted into a fatty 
matter, and into ammonia, which compose 
a kind of soap. When allowed to remain 
long in water, it softens and petrifies, being 
converted into a sort of jelly. When long 
boiled in water it becomes gelatinous, and 
dissolves completely, constituting a viscid 
liquor, which, by proper evaporation, is con- 
verted into glue.. Hence the cutis of animals 
is commonly employed in the manufacture 
of glue. From these facts the cutis appears 
to be a peculiar modification of gelatine, 
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