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

four ffths of 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 cornea is
transparent and joined to the scle
rotic very much as a watch crystal is
set in watch. On casually look
ing at the eye the observer does not
notice it as the colored iris is seen
through it on account of its trans.
parency. The coat may be plainly
seen by taking a 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 q net
work of blood vessels and pigment
cells covering the inner side of the
sclerostic and posterior surface of the
iris. The use of this dark surface
is 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
gins of which it is attached, and con-
tains 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-
pressions at its marginal surface are
attached two sets of muscles-the
ciliary muscles-which contract or
dilate the pupil and determine the
amount of light admitted.
The internal or third coat of the
eve is known as the retina. This is
the most important membrane of the
eve, and in fact all the remainder Of
the eye is subservient to it. For 1t
is upon this that light impinges, aid
images are formed and we are said
to see.
This membrane is only one one
hundred -and-twentieth of an inch in
thickness, yet it has Dsen 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-
cipient layer that receive the sensa-
ton 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 fash of light, and one
may be made to ''see stars" when the
eve receives a severe blow. HOre
physiology and psychology are close
" >sllied. How can material sub
stance communicate an impression
to material brain and psychological
phenomena result?
We shall now speak of the three
humors of the eye. Thew are the
aqueous, crystalline and vitreous.
The aqueous humor is watery
fluid filing the anterior chamber of
the eye, between the cornea and the
crystalline or lens.
The crystalline humor, or leLs, is'
firm, transparent semi-solid sEo-
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 8 cushion for the
delicate retins, and preserve the
frmness 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 an 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 more than a photographers
camera, the act of seeing was yelled