Sharp County record., 1881-08-25

lection, they say, can hardly WorA on
such petty differences. But to talk Sc
is really to show a misrepresentation OIL
what natural selection rightly means
Every butterfly which is "spotted" oy
a bird and so devoured, is wiped out ol
existence forever, with all its possible
progeny. Every butterfly which eS-
capes, bv however slight peculiarly,
is enabled to lay its eggs in peace and
to hand on its peculiaritieS to its poster
ity. This sort of selection is going on
every day around us, and no difference
is too slight for it to select, no reSem'
blance is too clumsy, provided it once
for a moment aids the insect in avoiding
destruction. Now, we all know that the
eyes of birds are very sharp and keen
indeed. A hawk soaring so high IN the
air that human sight fails to perceive
it will vet discriminate and pounce down
upon a lark in the field below small
brown bird seated upon a brown clQu
of earth exactly like itself in color In
Just the same way the insectiyorous
birds keep sharp look out for moths
and butterflies, upon which they sWoop
at once. whenever they distinguish them
upon the ground beneath. Every day
these insects whose color bctrayS them
get thinned out by their watchtul enc
mics. while those whose color protects
manage to lay their eggs in peace ana
hand on their own peculiar spots ana
lines to their descendants.
The consequence, in the long run, IS
that the butterflies get better protected
from generation to generation, as the
chances Of interbreeding with badly pro-
tected individuals are eliminated by the
action of the birds, while only the most
imitatively colored individuals are leIt
70 mate with one another to and become
the parents of future swains. Thus the
hostile birds are themselves the instru-
ments through which the insects have
been armed defensively against their
depredations. For the various indlyldu-
ais tend always to vary little in mark
ing-no two plants or animals OF the
same species are ever exactly alike
but the picking off of the brightly col
ored individuals by the birds help to
preserve the protected specific type
intact. And, of course, the same causes
which now preserve it originally pro-
duced it. Ever since birds and butter
flies have existed the process must con-
have been at work. and the
birds and butterflies themselves in the
forms that we know them are the final
of this perpetual interaction.
This sufficiently accounts for the imt
.ative coloring Of the under surface, but
it does not sufficiently account for the
brilliant and attractive hues OF the upper
side. These hues were probably pro-
luced in a very different manner. 1t
his exact moment | saw two red ad-
nirals above the hedge yonder engaged
n their pretty rythmlcal cOdrtship, Iy-
no round and round one another, now
IN TOP and now beneath, chasing each
,ther in graceful curves, and seeming
o be engaged for ten minutes at time
n sort of aerial quadrille. These two
butterflies are helping in their small de-
,ree to keep up and intensity the beau
iful colOrs of their race. They are CO.
uetting and flirting together, each
sger TO display all its charms to the
est advantage, and to attract the other
Y its own beauty. If a third and
rettier butterfly happens to sail up,
he belle will bestOw her affections
pon the new comer, and the van
uished beau will slink away disgraced,
,aving her to her chosen mate. This
9cond sort of selection is going on for
yer, side by side with the first; the
rettest, freshest and most daintlly
larked insects being always preferred
l the pairing over duller, dingier OF
lore battered rivals. 1t is interesting
D note how the two kinds Of selection
I'm parallel with one another. While
be butterflies are poised mOtionIess
pom twigs or flowers they are in the
reatest danger from birds; butin such
they close their wings and dis
.lay only the outer surface, which is
and protectively cOlored.
The constant picking off of all those
which can be distinguished when at rest.
uiiices to keep the protective colorS
.lways true. On the other hand, when
he insects are on the wing, lowering
bout flowers or rising in the air to
,irouette and gambol with their mates,
hey run comparatively little risk
rom the birds.
They are too nimble for their pursu-
ers, and they seem fairly secure by their
power of doubling as they fit rapidly
along from spray to spray. The birds
are bad marksmen at a moving target;
thew can not double like their prey, and
they prefer to aim at their butterflies
sitting, as French sportsmen are said to
do at partridges. On the other hand,
with butterflies as with men, faint
heart never won fair lady. If the in
sect did not venture out into the open
to seek their mates and to charm them
with their painted pinions, some holder
rival would carry of the prize, and so
leave the towards unrepresented in
future ages. Thus in the course of gen.
erations, a great many butterflies have
come to have two sets of colors-the
one set attractive for their own kind
and the other set protective against
their enemies. Pail Mall Gazette.