Star.
London, England, 1829-01-09 00:00:00

PHYSIOLOGY OF THE EAR.

Main Mr. Coasts's Lecture ao the Physiology and Zoology of the
Bar in man and Animals, claimed at the Royai Institution of
Great Britain].
Many circumstances have hitherto deterred the Pro-
fession from the investigation of this important organ
of sense. These are chiefly its complicated mechanism
—its internal situation, which renders it inviable in the
living state—and lastly, the few opportunities of dis-
section after diseases cf this part of the body. It is,
:therefore, from the cultivation and improvement of
Comparative Anatomy that a knowledge of the strut'
tine and functions of the different organs of sense, par
titularly of the Ear, has been acquired. In the same
manner, I may remark, that it was only by patient and
persevering application that the immortal Harvey ar-
rivtd 'at the units in the discovery of the circulation of
the blood. Hence, in this investigation, we should be
stimulated with the same laudable seal; and, although
a long neglected subject, we should not sit down in
hopeless apathy, but pra•ecute our inquiries with the
most,sealous ardour, until our knowledge is equally
complete of the Ear as of the other organs of sense.
• In entering oa the subject of this Lecture, I shall give a sookr
gical definition of Man (according to the arrangement of Cuvier
Inumenbach, &c. to wbom I am indebted for many observations
introduced on this occasion)—via. Order, lissonson r genus, hems/
the species single, with several varieties; characters, elect stature,
having two bands, teeth approximated and of equal length, the in-
.fezior incisors perpendicular, prominent chin, rational, endowed
with speech, unarmed, defenceless.

Cuvier, in his Reflections on the Progress of the
Sciences, read at the Ruyal Institute of France ob-
serves—

That the first savages collected la the forests a few nourishing
fruits, a few salutary roots, and thus supplied their most immediate
wants. The first shepherds observed that the stars moved in a re-
Filar coons, and made use of them to guide their journeys across
the plains of the desert. Such was the origin of the mathematical
and physical, sciences. Once convinced that it could combat Nature
by the means which she herself afforded, genius reposed no more ;
k watched her without relaxation, it Incessantly made new coo-
Vests over her, all of them distinguished by some improvement in
Oho situation of our race. • From that time, a succession of enfl-
aming minds, faithful depositories of the attainments already
made, constantly occupied in connecting them, In vivifying them by
Moans of each other, have conducted us, in Mss than forty ages,
'from the first essays of rude observers to the profound cakulations
of Newton and La Place, to the learned classifications of Linnaeus
and Amiss. This precious inheritance, perpetually increasing,
Monk from amides into Egypt, from Egypt into Greece, con-
flated during ages of disaster and of darkness, recovered in moss'
fortunate times, unequally spread among the nations of Europe, has
ovary where been followed by wealth and power; the nations
wit'ch have reaped it are become the mistresses of the world; such
as have neglected it, are fallen into weakness and obscurity.
In estimating the senses, the great importance to man of the
sense of hearing wUI never be denied; it is the medium which con-
nects him with society, that admits of social Intercourse, of an un-
limited interchange of ideas ; and it extends information and intel-
ligence, in a ratio and mode capable of exciting interest, beyond the.
powers even of the eye. Through this great medium, man is enabled
to conduct the complicated business of life; through it his reason-
ings are best enforced in the senate, and his commands in the field.
Where sound is required to be distinctly heard, and from a low
situation, as the ground, for example slow hounds and others, have
either ng ears hanging down,. or have them flexible, as they
ono* the bead with more difficulty than man. Fowls' again,
differ from ciadrupeds, in having no external Ear; but is
place of it, there is a tuft of very an* feathers, which covers
the passage to the Ear; this covering easily admits sound, and k
also prevents any bluets or external matters, which might pretties
source of injury, from getting into it. To them an external Ear
would have been inconvenient, as causing an obstruction to the
course of their light, in passing through thickets, and other neatly
impervious places. In the auricular passage of the fowl, as of man,
there is separated a liquor, to lubricate it, and from its adhe.lveness
and disagreeable pungency, to prevent the entrance of insects.—
When compared with the Ears of other animals, theirs is also a.
.more artUaginous consistence than composed of real bone ; hence
any tremulous motions Impressed on the air are communicated
;this class merely by the spring and elasticity of these cartilaginous
parts, which do not require, in order to render the membrane of
the Ear tight, the same power or action of the muscles, as in man.'
In the internal Rear of this class the semicircular canals appear
very distinctly, and can be demonstrated with facility.
In the different classes we find that &beg have a complete
organ of hearing, and equally perfect as that of the other classes;
the element also in which they rain is proved to be one of
the beat mediums for the tranamisiun of sound (1). It is well)
known that the Ear of the whale kind strongly resembles in its
structure that of man. In the skate, on dissecting the brad, we
find a bag placed behind the eyes—it contains a fluid, and also a
soft cretaceous substance; these are the vestibule and cochlea of
this fish, similar to the internal parts of the ear of man: there is
also distributed upon this bag a part of she auditory nerve, similar
to what is termed the portio monis, or branch of the seventh pair
of nerves in the human subject ; there are likewise semicircular
Clink, which form an important part of the internal Ear, and ars
filled with a fluid. In the cod species, instead of this soft creta-
ceous substance, there is found a bard crustaceous stone ; but there
seems no appearance of an external passe'', as in the skate.
In prosecating our inquiries farther, we find that, in articulated
animals. the nervous system is reduced to a knotted cord, and the,
organs of sense pre gradually extinguished; the sympathetic nerve
belongs only to this department, and in the class of articulated,
the true spinal marrow is to be found only in the musician° and
more perfect animals: This nerve is the most general, and the
original of all nerves, but it is variously modified la the different
,classes. In worms and insects it consists merely of vertebral
ganglia, without the aullac ganglia of mammalta and birds. In the
.uepbalous maltose.% there are the latter without the former. In
snails there are single ganglia of both kinds ; aU these lower ani-
mals have no spinal marrow. On the whole, the organ of hearing,
as I formerly observed, is so constructed in every class as to be
peculiarly adapted to the mode of life and other circumstances con-
nected with the situation of the animal. Man, who is the noblest
of all, and must bear sounds equally from all quarters, has his ex-
ternal Ear both large and placed in a vertical manner, turned some-
what forwards ; animals, however, have in general a greater power
of motion in the external Ear than Man; hence it is furnished
with a greaser number of muscles, and they can direct or apply the
cone of. the Ear readily to the sonoions body, without moving the
bead. From this, it would appear that in them it is necessary to
Olivet sound more strongly, and that the internal Ear does not
receive the isnpresaions with the sonic facility as that of the buns
race.

earing. In the words of a celebrated French physiologist, may
delved the function intended to acquaint us with the vibratory
motions of bodice; hearing lathe exercise of tis it (acuity, or sense,
• y Which we appreciate and estimate all vibrations from sonorous
ks, and these vibrations are termed. sounds; sound is conveyed
6y the atmosphere in straight lines to an incredible extent. which
lines keviiieceived the appellation of ssnoroos rays, and are in.
mimed in proportion to the elasticity of the body through wbkh
they pass, while the denser the body is the more they become di.
tatinished in strength. The true wet of bearing is in that part of
the organ which is formed by the portin mollis of the seventh pair
'of nerves, and its pulp is beau:ltaly distributed upon the ampulla
of the membranous semicircular canals, also upon the barbula, and
the sons moUis of the cochlea (2). The manner in which bearing
tikes place may be thus simply explained—the rays emanating
from a sonorous body are directed to, and irrive at the Ear, where
they !temp, concentrated, in consequence of its peculiarly-elastic
structure; and in this soocentrated state they pass along the eater-
nal -auditory foramen to the membrane tympani, on which they
excite a vibration; this vibration of the tympanum is communi-
cated to the mallets, in immediate contact with it, the action of
the useless conveys them to the locus, and the latter again to the
a sibladon, whence they next reach the stapes (3). The bads of
dullest bone is extended within the vestibulum, in that part where,
paged as a centre, it faces the common channel of the membranous
wiskisaslar. cassis, as well as the orifice of the scale vestibuli: in
ion one of this situation, the vibrations on the stapes ate ea-
eesdsd the waive of the labyrinth, and the undulations directed
from this part, from a centre to a circumference, strike first the
Ovens ananumis, and are next extended throughout the liquor of
the labyrinth surrounding the membranous semicircular canals,
agitating by theft undeladons their whole surface, and this of course
effects the nervous expansion spreading over all these parts (4).
(Mescals of the /*dike opens late diti vestibulum, and the other
iteginalreqa the (contra ovals; and being both filled with' water
of the labyrinth, and communicating with each other at the apex
of the cochlea. the sonorous vibrations are ia this atanow•coes•
latunkated:also to the scab of the cochlea ; besides this, between
the scale g the cochlea, in a middle point as it were, is placed the
Seas monis, where the awe is also extended and the sonorous
en-
delstions take place (S). •Itis by these varied actions of the di(-
' (I) Vide Edinburgh Philosophical Journal.
(s) William Hunter, M.D. (3) Si. &Mk, M.D.
(4) ilobbi. (3) Haw.

firent parts on the auditory nete.s, that the tatter is enabled to
convey the vibrations to the sensorium, by which the mind Is in.
formed d the existence of sound, and Is enabled to edentate its
import. and judge of its difference or degree ; for gravity, or acute-
ness of sound, depends only on the number of vibrations given at
the same time. The sittaition of the Ear 1 may isti.erve, is met*
internal, and its powers mine concentrated, than those of the Eye;
its nervous expansion is more limited, and the ondies which act
upon it are denser, and more solid, than those of light ; hence the
sensations conveyed by it are limited, though more numerous and
durable than those of the Rye.
In estimating the value of the different *rose., the hest &teflon,
as I conceive, to be ruled by is the opinion of persons who have
been partially deprived of any sense. A Nina man, who had been
for years in that state, when 'dud if he would accept of the re-
notation of sight on condition of the loss of hearing? answered,
that be considered himself happy, though blind, being able to con.
verse with his friends. The organs of voice are, as it is wen
known, useless, unless their powers are excited through the agency
of the sense of hearing; and when bearing is detective in early life
dumbness is the consequence (6). According to Blumenhaeb, no-
thing is so strong a picture of the social necessity of man as a person
dumb, because born deaf. It is the Rar which connects man with
the moral world—the sonditie fiat tea non of his progressiveness—
that which distinguishes a society front a herd. Hobbes accord.
ingiy remarks, that the most noble and profitable invention of all
others is that of speech, whereby men declare their thoughts one
to another, for mutual utility and conversation, without which
there bad been, mono men, neither commonwealth nor society,
no more than amongst lions, bears, :or wolves. Though bearing
is more perfect in nun than in any other animal, it is not so at the
period of birth. An infant bears at first hut very imperfectly ;
this tutees In part front the passage, or meatus emeritus, being
covered with a viscid mucus, or discharge from the ceruminous
glands of the Ear, in a similar manner as in other cavities. On
the removal of this original layer, or deposition, the sense NM
appears equally perfect as at any future period of life Much ad-
wants', may be taken of this circumstance in the treatment of
deaf and climb citildren in early infancy.
(6) Curties Treatise on the Physiology and Diseases of the Ear.
See also PorteL