The Brookhaven leader., 1884-02-07
Wonderful Insect Eyes.

Physicians call attention to the in
creasing instances of defective or imper-
feet sight occurring in civilized coun-
tries, and attribute it to various condi-
tions of modern life-the overwork of
books in small print, the habit of read
ing by imperfect light, and many other
causes. 1t appears certain that in mat
ter of eyeSight the savage has usually
the advantage of the civilized man. The
gift of sight is one very unequally dis
tributed among the animal world. Some
creatures enjoy it in excess, like the
eagle; others are totally deprived of it,
like the earthworm. In many other in
stances the sense of sight, if not actu-
ally lacking is extremely imperfect, as
in the case of the mole. Insects are in
many cases far more richly endowed
with eyes than even birds or beasts.
The little creature called whirlwig
(GVrinuS nTtdiOr) which skins about
on the surface of standing water, is
furnished with double set of optics,
the upper portion of the eyes Gifted for
seeing in the air) being placed in the
upper POI ton of the head, and the low
er portion of the eyes (fitted for seeing
in the wate") in the lower portion of
the head. a thin division separating the
two. Spiders possess six eyes-some
species eight. centipedes twenty, while
the eyes of many insects (bees, butter
flies, dragon tlies) are composed of a
number of facets, each eye being, in
fact, cluster of eyes. DR.. Hook
counted $4,000 of these facets in the
eye of dragon-hy, and Lceuwen-
hoek found as many as l2,j44
in another specimen of the same
species. The latter naturalist adapted
one of the eyes of dragon-tly so as to
be able to see objects through it by
means of a microscope, and found that
he could view the steeple of q church
299 feet high and 80 feet from the
place where he stood; he could also dis
tinguish if the door of a house, at the
same distance, was open or shut. Fleas'
ewes diminish as well as multiply OBJ
jects; as Puget discovered by perform
ING a similar experiment to that of
Leeuwenhoek, "a soldier viewed
through it represented an army of pig
mics. the fame of a candle
seemed the illumination of thousand
IpIlui vi
human beings NAV think with envy of
the beautiful provision of visual organs
bestowed by Nature on some of her
children; and yet many creatures live
happily with but small share of the
blessings of sight. In some of the in
Sc is who possess the largest share of
visual organs, some other sense-taste,
hearing or touch-is deficient. Huber
believes their sense of both hearing and
taste to be imperfect. On the other
hand, the blind earthworm will retreat
rapidly into its hole if the light of a
candle is thrown upon it, its sense of
hearing or smell warning it of the ap-
proach of the danger it can not see. A
bats senses of touch, hearing and smell
are so acute that it depends little on the
aid of its eyes. Spallanzani tested this
by the cruel experiment of destroying
the sight of several bats, and then set
ting them free. In their flight through
the room they avoided even the smallest
thread placed to obstruct their way.
Latrelle, the French naturalist, states
that there is a species of ants which are
entirely blind, but pursue the same
mode of life as their sighted brethren.
-LondOn Globe.