MUCUS. 
velocity being about 10 feet per second, its 
maximum action will be $ (420) = 1853, and it 
will move at the rate of P or 34rd feet per se- 
cond, being about 22 miles per hour. With 
the help of these formule the maximum forces 
of any other animals may be found. 
BIBLIOGRAPHY. —Aristotle, On the progressive 
motion of animals, by Taylor. Fabricius ab Aqua- 
pendente, De motu locali animalium, Opera ed. 
Bohnii, Lipsie, 1687, p. 332. %, De vi. 
motrice et motionibus animalium, Opera, tom. ii. 
lib. xi. Florentie. Borelli, De motu animalium, 
4to. Lugduni, 1685. Haller, Elementa physio- 
logiz, tom. iv. lib. xi. sect.1v. Barthez, Nouvelle 
mécanique des mouvemens de |’homme et des ani- 
maux, 4to. Par. 1798. Magendie, Precis élément. 
de physiol. tome i. Roulin, Recherches sur le 
isme des attitudes et des mouvemens de 
Vhomme, in Magendie’s Journal, tom. i. ii. 1821-2. 
Gerdy, Sur le mécanisme de la marche de l’homme, 
Magendie’s Journ. tom. ix, and Physiol. médicale 
didactique et critique, par P. N. Gerdy, Paris, 1833, 
tome i. partie 2. Krause, Handb. der menschl. 
Anat. Bd. 1. Poisson, Traité de mécanique, Paris, 
1833, tome ii. Weber, W. and E., Mechanik der 
menschl. Gehewerkzenge, Gott. 1836. Kirby and 
ate Introduction to entomology, 8vo. Miiller, 
lements of Physiology by Baly. Roget, Bridge- 
water Treatise. Paley, Natural theology, with notes 
by Brougham and Bell. Gregory, O., Treatise of 
mechanics. Chabrier, Mémoire de l’Acad. tom. ii. 
— Sur le vol des Insectes, et observations sur 
quelques parties de la mécanique des mouve- 
mens progressifs de l"homme et des animaux ver- 
tebrés, 4to. Paris, 1823. Straus Diirckheim, Con- 
_ sidérations générales sur l’anatomie comparée des 
animaux articulés, 4to.Paris, 1828. Cuvier, Régne 
Animal. Perrault, Mecanique des animaux. Pa- 
vent, On animal mechanics, A. P. 1702. Marian, 
On the position of the legs in walking, A. P 1721. 
, On the motions of the Horse. Bernou- 
illius, J. De motu musculorum, Lond. 4to. 1708. 
son’s Piinciples of mechanics, Lond. 4to. 
1800. Pinel, On animal mechanics, Roz. xxxi. 350, 
xxxiii. 12, xxxv. 457. Mayow, J. De motu mus- 
culari et spiritibus animalibus. 
(John Bishop.) 
MUCUS (from pvée, the secretion of the 
Schneiderian membrane). This word has been 
used in so very indefinite a sense by the 
members of the medical profession, that animal 
chemists have had great difficulty in fixing on 
any distinctive characters by which the sub- 
Stance might be identified. The great source 
of confusion appears to have been that phy- 
siologists and the profession generally have 
applied the adjective mucous or mucoid 
to certain forms of secreted matter; from 
which circumstance the term mucus has 
gradually advanced into substantive use as a 
medico-chemical word, embracing in its mean- 
ing the secretions from the mouth, nose, in- 
testines, &c. as though these were identical 
in their chemical characters. We shall pre- 
sently show, however, that such is not the case. 
In the Philosophical Transactions for 1800 
_ Mr. Hatchett published a paper, in which he 
_ endeavoured to show that such a principle 
__ as mucus really existed, characterised by pecu- 
| - Tiar properties; but considered it a modified 
form of gelatin. Dr. Bostock subsequently 
_ published a paper in Nicholson’s Journal, in 
_-which he showed that mucus differed from 
elatin; this he proved by demonstrating that 
VOL, III. 
481 
tanning did not precipitate mucus, though 
gelatin was immediately thrown down by it, 
whereas diacetate of lead precipitated mucus 
copiously, without affecting gelatin: bichloride 
of mercury and ferrocyanuret of potassa did 
not precipitate either mucus or gelatin. I shall 
show hereafter that these last-mentioned re- 
actions do not apply to every form of mucus: 
the ingenious experiments of Dr. Bostock can 
indeed no longer be considered pertinent, in- 
asmuch as the researches of modern chemists 
have gone far to prove that gelatin is rather 
a product than an educt of animal analysis. 
The experiments of Dr. Bostock were made 
on the saliva of the mouth, and some sub- 
sequent observations by Mr. Brande made on 
the same secretion showed that the precipitates 
obtained by the diacetate of lead and nitrate 
of silver consisted of the chlorides and phos- 
phates of those metals; a fact which inclined 
Mr. Brande to consider mucus as a compound 
substance rather than a proximate element, and 
induced him to apply electricity as a means of 
decomposition. From the results obtained 
in this inquiry, Mr. Brande was inclined to 
consider mucus as a compound of albumen 
either with pure soda or chloride of sodium. 
Dr. Marcet made some experiments on 
mucus which induced him to believe that 
several morbid secretions contained it as a 
constituent; he considered it to be present 
in dropsical effusions. Berzelius, though he 
allows the secretions of the mucous membranes 
to differ in chemical character, and to possess 
distinct properties according to the especial 
office they have to fulfil in lubricating par- 
ticular parts, still believes that such a proximate 
element as mucus really exists as one of the 
constituents of such secretions, and notices it 
in his analysis of mucus of the nose. In 
considering this subject it is, therefore, neces- 
sary to premise that the general term, as used 
by the medical profession, has no relation 
whatever to the chemistry of the question, 
the secretions of the different mucous mem- 
branes varying greatly in chemical composition, 
but, notwithstanding, presenting a physical 
character in common, in relation to which 
the term mucous has been applied to them. 
The inquiry of greatest interest consists in 
determining whether there exists a peculiar 
proximate element in virtue of which the 
mucous character is developed, or whether, on 
the other hand, the peculiar physical character 
can be traced to the presence of some combi- 
nation of albumen which is common to all 
mucous secretions, notwithstanding that they 
may differ greatly in other respects. We have 
already seen that the latter opinion is supported 
by Mr. Brande’s experiments, while Berzelius, 
on the contrary, seems to favour the former 
view of the case. Before entering upon this 
question I shall describe the chemical characters 
of several secretions from mucous surfaces, as 
the reader will then be better prepared for the 
inquiry. I shall commence with the secretion 
from the nose, since this may be regarded as 
the type of those viscous products to which 
the general name of mucus has been applied. 
21 
