The Washington times., 1903-02-14
MYRIAD-EYED INSECTS.
Adapted to the Wants of Their Pos
SCISSORS in Every Particular.

Adapted to the Wants Of Their Pos
SCISSORS in Every Particular.
We all understand that our eyes are
somewhat like little Photographic cam
eras, with sets OF lenses. with stope
TO cut off unnecessary light, and having
arrangements for focusing. and every
thing else that is needed TO form the
little colOred picture on the sensitive
retina at the back of the eye. The eyes
OF all backboned creatures are. indeed.
so much like cameras that photographs
nave actually been made through the eyes
of some OF the large domestic ANIMAL.
But anyone who has examined insects
at all must have noticed that their eyes
are very different from our own. For
IN the first place, each eye is often
larger than all the rest OF the head
There is no iris and no pupil. Then
too. an insect does not have TO turn his
head and look straight at anything, as
we do when we wish 10 see clearly. One
OF the first things that we notice about
, an insects eye is that Il is cut up into
hundreds OF little surfaces or facets. or
Is, as We say. "a compound eye" Now,
each of these facets is at the end of a
little tube with blackened sides, filed
with clear jelly, and the entire eve IS
built up OF these little tubes side by
side.
An insects eye is not camera eye"
like our own. but what is called a
mosaic eye after the pictures which
are made by putting together little bits
OF colored glass and stone. We can get
/ an Idea Of how this sort OF eve acts If
We look through a small roll OF paper.
/ When we do this We OF course, see only
the spot at which we point the tube
Now, the Insects eye is like a large
I q frsbe I'M.
ball. The insect looks out through
/ ali the tubes at once. and sees the spot
/ at the end of each. Thus the animal
/ with his two eyes looks in al directions
\ at the same time. and sees as many
spots OF color as there are tubes in both
I eyes-several thousand, perhaps. all
/ combined into single picture like the
pattern Of carpet. We may get some
/ idea OF an insects power of sight 81.
while looking straight at some object
we notice what there is al the sides
/ as far around as one can see. We can
then see shapes only dimly but we can
see colors perfectly we'll. and can even
/ detect anything moving almost behind
/ our heads An insect seems 20 see every
/ object as We see one thing when we
/ look al another. II sees shapes vaguely.
! but shades or color perfectly well. and
! knows at once If anything near il moves.
The compound eye appears 70 be good
only for seeing things at a distance. and
is not practically OF much use at short
range So nearly all insects have one,
two or three little eyes. which. so Tar
as can be made out, are 20 help them
see things near at hand. These Oceln.
as they are called. are somewhat like
our eyes. but much simpler. anc they
appear as minute dots on the front oil
! the head between the compound eyes
How much an insect sees with these
oceili. no one really knows. But IL We
watch one and notice how much he
seems to depend on the sense Of touch
IN his antennae IA will appear as though
he acts more like a partially blind man
feeling the ground with his stick than
Ike a being who sees clearly as We do
Science Strings