Tazewell Republican. [volume] (Tazewell, Va.) 1892-1919, 1899-08-10
WE ALL HAVE THEM.
Scientists Say Everybody Has
Blind and Dead Spots.
Small Places on the Skin That Are IN
sensible to Pain and Imper-
ceptibIe Defects in
Each Eye.

Each Eye.
Everybody has blind spot in each
eve. Every body has hundreds of blank
or nerveless spots on the skin in which
thereisno sensation, or in which, if SEN
sation does exist, it is so slight as to
communicate little to the faculties in
spired By the sense of touch.
The truth of blind and dead spots has
been learned through experiments
made at several of the colleges last
spring, following the lead of Cornell
university, and those who have delved
deepest into the matter aver that when
one concentrates his gaze ON anything,
which comes within common visual linn
its, he fails to see completely all at
once. This is because there is a point
directly opposite his particular blind
spotwhichis invisible to him. This is SO
of the best eyes in the world. Even
horses. cows, dogs, cats and many other
lower animals are in a similar fix.
Concerning these blank spaces on the
skin, the learned men assert that one
could be touched with hot iron on any
one of them, selected indiscriminately,
without a sensation of pain. The dead
spots are scattered oil over the body.
In most ms ances they are small. 10
locate them and make a sort of topo-
graphical map of persons dead spots,
the eXperimenters have applied boiling
hot water to the subjects anatomical
surface. In most places, of course, the
scalding water was too painful to be
borne, but ir other places it could not
be felt at az.
1t seems almost a revolution in the
natural order of things that these blind
spots should be caused by the optic
nerve itself; that those filaments which
give to the eyeball its most vital prinel-
ple should at this point neutralize 1t.
But this is only one of the many para
doxes encountered by the psychologist.
The eye is simply camera in which the
visual object is photographed on the
retina-a sensitive plate, so to speak
at the back. The optic nerve enters
through the retina, and this entrance
causes a rupture in the smooth, reflect
ing surface of the sensitive plate. OPP
tic nerves are of a "stringy" con-
sistency, but the strings are far from
round. and therefore the nerve finds its
way into the retina by means of an ir-
regularly shaped hole. This makes the
blind spot. Perfect sight is interfcred
with by the optic nerve to the extent OF
anirregularly formed spot in the retina,
which, when enlarged through the
natural and ordinary process of gazing
upon white wall few feet away, ap-
pears, if outlined in black, much like an
ink blot about the size of silver quar-
ter. Of course, the shape of the blind
spot varies in different persons, just as
does the size or shape of their heads.
In experimenting upon the dead and
sensitive spots some of the instruments
used are sharp-pointed, heated with
boiling water and passed forward and
backward over the skin, touching every
minute part of it in succession, and re-
producing by the aid of an instrument
like a paragraph, as the sensations Of
the subject indicate, a complete dia-
gram of his blank spaces.
One direct result of such experiments
has been to prove that we do not pos
sess varied sense of touch, after all.
If any part of the body is touched we
10 not become aware of the contact by
any sense of acute feeling in the affect
ed part, but by the mental picture of the
proceeding which we instantly form.
Thus the sense of touch, in normal per-
sons, is dominated wholly by the sense
of sight. For instance, when you are
touched in the dark, how do you know
where you are touched? Scientists as
sert that in majority of cases 1t Is
from the picture instantaneously COM
posed in the mind, and not by the touch
at ali, which would indicate that we pos
sess better idea of the appearance of
our anatomies than we generally be-
lieve, for if we have not an accurate
sense of the appearance of our bodies 1t
il a question whether or not we would
know precisely where any part of them
is touched on occasion. At best the
sense of touch is liable to quick dissipa-
ton, and unless mental pictures are
composed instantly we would not be
able to locate the sensation a minute
afterward.
The proof of this is learned easily.
Blindfold person, touch his hand with
the end of small stick and bid him find
the place of contact without looking at
it. This 1t will be found almost impos-
sible to do, and the hand being only
few inches wide, even the difference of
half an inch in finding the correct spot
would count enormously in favor of the
theory.
In the case of a blind man matters are
complicated still more. If stricken with
blindness he would have a memory pic
ture of the appearance of his body. If
born blind he could not have any visual
map, and, therefore, performs the curl
GUS operation of building up, bit by bit,
like mosaic, touch picture. By many
means independent of sight the blind
man has preconceived ideas of the gen
eral shape and appearance of his several
anatomical members, and when he is
touched this interpretive picture i'm
mediately looms up in his mind, and he
knows that it is his head, arm, hand, leg,
foot or other part of his body which is
affected.-St. Louis Globe-Democrat.
rY.. C.oox,I4u