The Newberry herald and news. (Newberry, S.C.) 1884-1903, 1902-05-16

'ne VI this coat and the pos.
terror portion Of the ball is com.
monty known as the "white of the
eye"
The anterior one fifth or oornea is
transparent and joined to the sole
rotlo very much IS a watch crystal is
set IN watch. On casually look
ing at the eye the observer does not
notice it 40 the colored iris is seen
through it on account of it's trans
parenoy. The coat may be plainly
seen by taking side view of the
eyeball.
The second coat of the eyeball
from without is the vascular coat com
posed of the choroid behind and the
iris in front. The choroid is a net
work Of blood vessels and pigment
cells covering the inner side of the
scleroatic and posterior surface of the
iris. The use of this dark surface
ls to absorb the excess Of light that
may gain entrance into the eye. The
iris forms curtain behind the cor
nea, or front of the eye, to the mar.
guns of which it is attached, and con.
talns the pupil or window through
which light is transmitted to the re-
tina. 1t is the iris that gives to
the eye it's color and beauty of ex-
presslons at it's marginal surface are
| attached two sets of muscles the
clliary muscles which contract or
dilate the pupil and determine the
amount Of light admitted.
The internal or third coat of the
eye is known as the retina. This is
the most important membrane Of the
eye, and in fact all the remainder of
the eye is subservient to it. For IT
ID upon this that light impinges, and
| images are formed and we are suid
to see.
This membrane is only one one.
hundred and. twentieth of an inch in
thickness, yet it has been divided by
the microscope into nearly a dozen
layers, the most important of which
are the internal and external.
The internal is the conductive
layer, while the external is the per-
clpient layer that receive the sensa.
tion of light and communicates it to
the brain through the optic nerve.
This nerve can take cognizance only
OF the sensation of light, and hence
feels no pain. Any irritation of it
produces flash Of light, and one
may be made to "see stars" when the
eye receives severe blow. Hore
physiology and psychology are close
ly allied. How can material sub
stance communicate an impression
to a material brain and psychological
phenomena result?
We shall now speak of the three
humors of the eye. Thev are the
aqueous, crystalline and vitreous.
The aqueous humor is watery
fluid filling the anterior chamber of
the eye, between the cornea and the
crystalline or lens.
The crystalline humor, or leLs, is
a firm, Transparent semi solid sub
stance, held in transparent elastic
| capsule which maintains it's form
that of double convex lens. 1t is
upon the shape and density Of the
lens that accuracy of vision depends
The vitreous humor fills the poste
rior chamber of the eye. 1t is color
less and transparent and is we'll
adapted to form a cushion for the
delicate retina, and preserve the
firmness and elasticity Of the eyeball.
"The eye is wonderful example
OF skilful packing, combining firm.
ness, elasticity, compactness, mobility
and safety in degree of perfection
that can never be approached by art
and is perhaps scarcely equalled else.
where in nature"
| Having given al elementary de.
scription of the anatomy of the diff
ferent parts of the eye, we shall now
consider some of their functions or
physiology. Before the astronomer,
Kepler, discovered that the eye is
nothing moro than a photographers
camera, the act of seeing was veiled
in obscure mystery. In the camera
the images Of objects fall upon a
| chamicallv aensitjva plate in tho aVo