The Baltimore County union., 1884-06-14
Correspondence Baltimore County Union.
THE MISSION OF THE HOUSE FLY.

Editors Union Il send you the following in
teresting scrap which came across in paper
few days ago:
"The fly when it alights rubs its hind legs to-
gether then each hind leg is passed over a wing;
then the operation is performed with the
fore legs, and then, if you observe closely, you
will see Mr.. Fly pass his proboscis over his legs
and about his body as far as he can reach. The
trunk terminates in two large lobes, which spread
out when the insect begins meal, and is capable
of being drawn back rapidly; but though thus
constituted it is not fitted for licking, but simply
for grasping and drawing up food. What the hy
does by flying around and then alighting and 60
ing through the maneuvres described has at length
been successfully investigated and decided by an
English chemist named Emerson, who carried out
his work by the aid of a powerful microscope
He relates that when he first conceived the idea of
making the investigation he captured fine speci-
men and glued its wings down to microscope
slide. On placing the slide under the instrument
he found to his disgust that the fly appeared to
be covered with vermin. He tried several others,
which were likewise covered with lice, and this
curious coincidence led him to q still further in
vestigation. Why were the flies thus afflicted
or was it an afliction? Watching one of the flies
fastened the slide more closely, he observed the
creature extend its proboscs and sweep it his
body as if he had just alighted. Wherever the
lice were the trunk went; they were disappearing
within its recesses; the fly was actually eating
them. At first he thought this vermn the fy's
progeny; but further investigation disproved
this. Mr.. Emerson took piece of white paper
on which the two flies had alighted and were lick
ing themselves, and putting it under the instru-
ment found some of the little creatures had fallen
off-crumbs from the table, so to speak. He then
took the paper, went into the kitchen and sweep
ing it through the air. taking care that no fly
touched it during the operation, went back to the
microscope and there found animalcules the same
as those found on the flies. Here he had some
thing definite. They were not the progeny of the
fly, but anmalcules floating in the air. The body
of the fly is covered with coarse long hair, and
| its quick motions serves to take them up, the
hairy mouth of the whale takes up the animal
cules of the sea. When he gets the net full he re-
tires to his favorite the window-sill, or
in quiet corner, and proceeds to devour his feast
of soft-shell crabs.
"Mr. Emerson continued his investigations in
a variety of places, and the more dirty and filthy
| the place and the more fetid the odor prevailing
! it the richer the harvest he found the flies had
| made in the animalcule line. While the flies cap
| tured in such places unusually fat and pie
| thoric and happy, the flies found in clean, we'll
| ventilated apartments were so lean and miserable
that where a spider caught of them in his
parlor' he Immediately kicked it out as not fit to
| eat Wherever filth existed, evolving germs that
might generate diseases, there Mr.. Emerson OBJ
served that flies were most attracted, and there
| they covered themselves with the minute organisms
| which they greedly devoured. From this can be
deduced the conclusion that while the mission of
the house fly is one of immense Importance to
man, their presence in large numbers, while it in
dicates unhealthy exhalations, also guarantees
| immunity from disease to some extent" c.