ANATOMY. 
internal and external canthus, or angle of 
the eye. 
They are opened by the levator palpebrm 
lifting up the upper lid ; and this muscle 
is in a state of constant action so long as we 
keep our eyes open. They are closed by the 
circular orbicularis palpebrarum. 
The cilia, or eye-laslies, are two rows of 
strong curved hairs implanted in the opposed 
edges of the two eye-lids, and admirably 
calculated for protecting the eye from dust 
or other foreign bodies. 
The hairy prominences above the eye-lids 
are the supercilia, or eye-brows ; these are 
very moveable ; they serve as a protection 
to the eyes, and are much concerned in ex- 
pressing the passions. 
In order to facilitate the motions of the 
eye-lids and eye-balls on each other, the 
surface of the conjunctiva is constantly 
moistened by a watery and mucilaginous 
fluid poured out by the arteries of the part. 
The incrustations of the mucilage in the 
night would glue the eye-lids together ; but 
this effect is obviated by a natural ointment 
formed in a very elegant glandular appara- 
tus on the inner surface of the tarsi. We 
there find about 16 or IT longitudinal paral- 
lel rows of very minute glandular bodies ; 
and these pour out their sebaceous secretion 
from a series of apertures on the edges of 
the eye-lids. They are called the meibo- 
mian glands, and ciliary ducts. 
The fluid just described is constantly 
formed on the surface of the conjunctiva ; 
but on extraordinary occasions, as when an 
irritating foreign body is in the eye, or in 
consequence of affections of the mind, a fluid 
is poured out in greater abundance, which 
has the name of tears, and is secreted by 
the lacrymal gland. This is a small conglo- 
merate gland, situated in the orbit, near the 
upper eye-lid, and having ducts which ter- 
minate on the surface of the conjunctiva ; 
but which, on account of their minuteness, 
are hardly demonstrable in the human sub- 
ject. The utility of this secretion in wash- 
ing away any foreign substance must be suf- 
ficiently obvious. 
The superfluous part of the lacrymal secre- 
tion is conveyed through two very fine tubes 
to a small bag, situated at the internal angle 
of the eye. These tubes commence by open 
mouths, called the puncta lacrymalia, from 
the inner extremities of the eye-lids, and 
are about equal in size to admit a hog’s 
bristle. 
There is a little fleshy projection at the 
corner of the eye, and between the two 
puncta, called camncula lacrymalis. 
The lacrymal sac is a small membranous 
bag, placed in the hollow formed at the in- 
ner edge of the orbit. The tendon of the 
orbicularis palpebrarum, which generally 
forms a slight eminence visible through the 
skin, crosses the middle of this bag. 
A canal, called the ductus nasalis, and 
lodged in a groove of the superior maxillary 
bone, conveys the tears into the nose, where 
it terminates by an open orifice within the 
inferior turbinated bone. 
ORGAN OF HEARING. 
This organ is divided into two parts, the 
external and internal ear, by the membrana 
tympani. The situation of the former on 
the outside of the head is well known ; the 
latter is contained in the petrous portion of 
the temporal bone. 
The external ear consists of two parts, 
viz. the pinna, or ear popularly so called, 
and a tube called meatus auditorius exter- 
nus, leading from the pinna to the membrana 
tympani. These parts serve for collecting 
sounds, and conveying them to the membra- 
na tympani. 
The pinna consists of a convoluted carti- 
lage inclosed by common integuments. The 
lower part, which is pierced for ear-rings, 
has no cartilage, and is called the lobulus. 
The helix is the fold forming the external 
circumference of the ear ; the next eminence 
to this, which forms the margin of the great 
cavity of the external ear, is called anthelix ; 
it separates at its upper and anterior end 
into two processes, named crura. The 
projection immediately in front of the mea- 
tus is the tragus, and that immediately op- 
posite, the antitragus. The great cavity 
within the anthelix, and leading to the mea- 
tus, is called the concha. Several sebaceous 
glands are situated in the folds of the ear. 
The meatus externus is formed first by a 
portion of cartilage, continued from the 
pinna, and more interiorly it consists of a 
canal in the substance of the bone. This 
bony part does not exist in the foetus, where 
the meatus is wholly cartilaginous. Tiie com- 
mon integuments continued from the pinna 
line the meatus externus, and the cuticle is 
produced over the membrana tympani. 
The surface of the meatus at its com- 
mencement is furnished with numerous fine 
hairs, and the canal is moistened by a secre- 
tion of an oily and inflammable nature, call- 
ed cerumen. This is produced by numer- 
ous small glands, visible on the external sur- 
face of the meatus, and distinguishable by 
their yellowish colour. The cerumen con- 
cretes, and is collected sometimes in such 
