The Caldwell tribune. [volume] (Caldwell, Idaho Territory [Idaho]) 1883-1928, 1897-01-16
ABOUT THE EYES OF ANIMALS

Human beings have six muscles to each eye,
that they may with facility move 1t on either
side; but horses, COWS, sheep and other quad
rupeds, which habitually incline their heads
to the earth In search Of food, have a muscle
by which the eyeballs are suspended and sup
ported, and which we do not need, says the
Providence Journal. This Is a wonderful adap-
tation to the circumstances in which the crea-
ture is placed. ror example, the eyes of am
phibious animals partly agree with those of
the fish and the quadruped. The cat and the
tiger, which prowl by night, have a peculiar
power Of expanding the pupil. The eyes Of
| fsh have no apparatus to molsten them,
II would be obviously unnecessary. The eye
is adapted to the properties of light, so that
II refracts the light and brings 1t to a focus on
| the retina Our best and most perfect glasses
are by no means equal to the human eye
/ Gnats and files have a great number of eyes;
| they can see on every side without any move
/ ment Of the organs of vision. Fish have a
crystalline, almost round, to At the eyes to
/ the strong refraction Of light in the element
in which they live; and although they have
] no eyelids, their cornea is horny to defend
/ their sight. The mole has two very small
/ eyes, hid under its velvet coat these are
/ admirably suited to his mode OF living chief
/ ly under the ground. The adaptation of the
faculties of animals to their mode of life
strikingly displays the wisdom of the Gre
ator.
chameleon Can Move One Eye.
Spiders have four, six or even eight :yes:
| they are transparent, like SO many gems The
| lizard called the chameleon can move one eye
| while the other is still: he fix one on the
say and the other the ground. He can
glance at all that is behind him and before
| him at once. Lord Brougham remarks of the
eyes of birds that they require to have them
sometimes fiat as possible for protection.
/ and at other times round as possible that
they may see flies and other Insects which thew
chase through the air. and which they pursue
with the most unerring certainty. This could
only he accomplished by giving them a pow
er Of suddenly changing the form Of their
eyes. Accordingly, there is a set Of hard
| scales placed on the outer coat of their eye
round the place where the light enters; and
over these scales are drawn the muscles or
ibres by which motion is communicated so
that, by acting with these muscles, the bird
can press the scales and squeeze the natural
magniher of the eye into a round shape when
1t wishes to follow an insect through the air;
and can relax the scales in order to hatten
the eye again when 1t would see distant OBJ
ject, or move safely through leaves or twfgs"
Design of the EyeIid.
This power Of altering the shape Of the eve
is possessed by birds Of prey in a very re-
maFkabie degree. They see the smallest
objects close to them, and can yet discern lar
ger bodies at a vast distance, as a carcass
stretched upon the plain, or a dying fish ahoat
upon the water. The eyelid Is designed to
moisten the eye and to keep It clean A sin
gular provision is made for keeping the sur
face Of the birds eye clean-for wiping as it
were, the glass of the instrument-and also
for protecting 1t while rapidly flying through
the air and through thickets, without him
dering the sight. Birds are for these rur-
poses, furnished with a third eyelid-a fine
membrane or skin, which is constantly moved
very rapidly over the eyebaIl by two muscles
placed In the back Of the eye. One OF these
muscles ends in loop, the other in a string
which goes through the loop and is hxad in
the corner Of the membrane, to pull It back
ward and forward. II you wish to draw any-
thing toward place with the least force you
must pull directly in the line between the
thing and the place; but If you wish to draw
1t as quickly as possible, and do not regard
/ the loss Of force, you must pull 1t obliuuely
Tie string to stone and draw it straight
I toward you; then make a loop of another
string, and, running the first through It. draw
one string in each hand sideways till both are
/ stretched in straight line; you will see how
much swifter the stone moves that it did be-
fore.