The silver lance., 1898-02-18


aver, the eyes have been overgrown by
the skin. so that these eyes would be
useless for vision, even IL the animal
should come from Its subteranean
nome to the Tight of day. The same
Is true OF the mole and mouse tribes.
Indeed. all the vertebrate animals have
.Wo eyes, whether they use them or not.
Not all animals have these two eyes
numerically placed in tie 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
oue to a simple twist Of the head was
demonstrated by Professor Steenstrup
more than twenty years ago.
AL times, by what Is termed arrested
development, animals, and even human
beings, appear as cyclops. or having
one eye only. But W. , ever Leard of a
third eye in man or beast? And yci
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
sst1ng, but also remarkably instructive,
since che rudimentary third eye of man
nas' by one Of the most noted philoso-
pners OF modern days. been looked upon
~ being the seat of the soul.
AZ organs by proper use develop In
strength and perfection, 30 they be-
come weak by lack of use. If for many
generations an organ should remain
without use. Its structure in time be-
comes simpler and more imperfect II
such . process continues throughout
ages. tho organ. by constant disuse. will
become reduced to q mere rudiment of
Wnat It was in the species using the
same Thus. species of birds that only
Walk and run. but never fly, have only
Fudimentary 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.
an almost perfect eye exists. though no
ray OF light ever could reach IT,
This eye shows a crystalline lens, a
retina Of very complex structure, and
An ir nerve-in fact, all the essential
parts OF perfect eye. But being COW
cred BY the Opaque skin of the animal,
II is absolutely useless.
II thia optic nerve is t-sced 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
Al ta1, l.
respond to the corpora quadrigemina In
man.
This third eye of the spotted lizard Is
called the pineai eye. on account OF the
nerve connection of its retina with the
pineal gland.
Now, while in certain lizards this
highly developed wye is useless because
It Is covered by opaque skin, and in
others even deeply Embedded In bone.
1t would seem probable that in an
sarlier stage Of development this pineal
sye was not rudimentary, but in con-
slant use. 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 it is transparent
where 1t passes over the eye.
In the skulls of some of the gigantic
reptiles of the earlier age of this globe
paleontologists have long ago found
large. round perforation. Probably this
was the socket Of the third or pineaI
eye Of the ichthyosaurus, the plesiosau-
rus and the labyrinthodon.
But a much more important conclu-
sion must be drawn from this discoy-
sry-uamely. that in all vertebrates.
even including man. the traces of this
third eye remain to-day. The pineaI
Ve Of lizards being connected with the
large pineal gland of the same. il
gould seem that the pineal gland itself
le but the nerve center of optic thalmus
tor this third eye. In all reptiles ana
amphibia the pineal gland is large; SO
1t Is also IN fishes.