The silver lance., 1898-07-22

eyes. In many Of such animals, how
sver, the eyes have been overgrown by
the skin, 30 that these eyes would be
useless for vision, even II the animal
should come from it's subterranean
home to the light Of day. The same
Il true Of the mole and mouse tribes
Indeed, all the vertebrate animals have
two eyes, whether they use them or not.
Not all animals have these two eyes
Symmetrically placed IN the head. one
on each side. Certain fishes which ap-
parently swim on the side, such as the
turbot, have both eyes on the side-the
dark side Of the head. That this Is not
due to a simple twist Of the head was
demonstrated by Professor Steenstrup
more than twenty years ago.
At times, by what is termed arrested
development, animals. and even human
beings. appear as cyclops, or having
one eye only. But W. ever heard of a
third eye in man or beast? And YET
recent researches prove that man and
all vertebrates seem to possess the ru-
diments Of a third eye.
This discovery is not only very inter
esting. but also remarkably instructive.
since the rudimentary third eye OF man
has, by one Of the most noted philoso-
piers Of modern days, been looked upon
rs being the seat OF the soul.
AS organs by proper use develop In
strength and perfection. so they be-
come weak by lack of use. II for many
generations an organ should remain
without use, its structure in time be-
comes simpler and more imperfect. II
such q process continues throughout
ages, the organ. by constant disuse, will
become reduced to a mere rudiment Of
what 1t was In the species using the
same. Thus. species of birds that only
walk and run. but never fly, have only
rudimentary wings, as the ostrich.
while In the eagle and the albatross
the wings are seen In q state of per
fection.
Now. In closely examining the skulls
Of certain lizards. 1t was found that near
the top Of the head, under the dark,
opaque skin, and often In the very bone.
ray Of light ever could reach IL.
This eye shows a crystalline lens, a
retina Of very complex structure and
an nerve-in fact, all the essential
parts OF a perfect eye. But being cov-
oIcu ny Tie OpdVut SIKH OI lHe animal,
It Is absolutely useless.
II this optic nerve is traced to the
brain. 1t Is found to connect the eye
with the so-called pineal gland of the
brain. This pineal gland is, of course
In no sense OF the word a real gland,
but a definite portion Of the nervous
tissue of the brain. Invariably located
just back and partly over the cerebrum,
and In front Of the rounded brain-mass
which generally Is considered to cor
respond to the corpora quadrigemina In
man.
This third eye Of the spotted lizard Is
called the pineal eye. on account Of tho
nerve connection of its retina with the
pineal gland.
Now. while In certain lizards this
highly developed we is useless because
It Is covered by opaque skin. and In
others even deeply imbedded in bone.
II would seem probable that in an
earlier stage Of development this pineal
eye was not rudimentary but in con-
stant use. A very slight modification
would accomplish this namely. the
transparency Of the skin covering of the
eye. This is exactly the condition of
the normal eyes In reptiles to-day; the
skin covers them, but 1t Ia transparent
where 1t passes over the eye.
In the skulls Of some Of the gigantic
reptiles Of the earlier age Of this globe
psychologists have long ago found a
large, round perforation. Probably this
was the socket Of the third or pineaI
aye of the ichthyosaurus. the plesiosau-
rus and the labyrinthodon.
put n much mora
sion must be drawn from this discov-
sfy-namely, that In all vertebrates
even including man. the traces of this
third eye remain to-day. The pineal
Ve Of lizards being connected with the
large pineal gland of the same. n
would seem that the pineal gland itself
is but the nnrve center of optic thalmus
tor this third eye. In all reptiles and
smphibia the pineal gland is large: so
It 10 also in fishes.