Eagle River review. [volume] (Eagle River, Wis.) 1890-1927, 1903-03-28
vidual have ever me, who cou,d 70.
slst mushroomi"-New York News
MOSAIC EYES OF INSECTS.
adapted to the Wants of the Posses.
sors in Every Particular.

~ Every Particular,
We all understand that orr ovas arc
somewhat like little Photographic cam
eias' with sets of lenses, with stops
~ cut on unnecessary light, and hav-
Ing arrangements for focusing. and
everything else that is needed to forpe
tne little colored picture on the sensi-
tive retlna at the back of the eye. The
eyes OF all backboned creatures are.
lndeed, SO much like cameras that
Photographs have actually been made
through the eyes of some of the large
domestic animals. But any one who
mas examined insects at all must have
noticed that their eyes are very diff
ferent 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 to see clearly. One
OF the first things that we notice about
an insects eyes is that it 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 little tube with blackened
sides, filled with clear jelly, and the
entire eye 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 eye 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 number of such
tubes put together into a ball The
insect looks out through all the tubes
at once, and sees the spot atJthe end of
each. Thus the animal with his two
eyes looks in all directions at the same
time, and sees as many spot OF color
as there are cubes in both eyes-sev-
eral thousand, perhaps, all combined
into single picture like the pattern
of a carpet. We may get some idea
of an insects power of sight if, while
looking straight at some object, we
around as one can see. We can then
see shapes only dimIy, but we can
see colors perfectly well, and can
even detect anything moving almost
behind our heads. An insect seems
to see every object as we see one
thing when we look at another. 1t
sees shapes vaguely but shades or
color perfectly WELL and knows at once
if anything near it moves.
The compound eye appears to be
good only for seeing things at dis
lance, and is not practically Of much
use at short range. So nearly all in
sects have one, two or three little
eyes, which, so far as can be made
out, are to help them see things near
at hand. These ocelli, as they are
called, are somewhat like our eyes,
but much simpler, and they appear as
minutes dots on the front Of the head
between the compound eyes. How
much an insect sees with these Oce1H
no one really knows. But if We watch
one and notice how much he seems to
depend on the sense of touch in his
antennae it will appear as though he
acts more like a partially blind man
feeling the ground with his stick than
like a being who sees clearly as we
do.-Science Siftings.