Iowa state bystander. [volume] (Des Moines, Iowa) 1894-1916, 1913-08-08
HABITS OF INSECTS NATURES SCHEME

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Why Differences In Animals Ara
Continually Perpetuated.
Color Proves Safeguard and e,hx
Seals, White In the North, Beeon.
Brown 40 They Drift Southwark
zebra's Stripes Protect Them.
Did It ever occur to you to wondo.
why. as between animals of much Tho
same general form and size-sav as
between the zebra, the horse and tho
mule-there should exist such marked
differences. and differences which are
perpetuated. generation after genera.
ton?
The problem which puzzled the earl,
scientists has come, within the las,
few decades. to be quite we'll under
stood. Felix J. Koch writes in On,
Dumb Animals. The answer is that
these changes are all part and parcel
Of natures great scheme for the pro.
lection and, In case of the wild crea.
lures, for enabling them to avoid their
enemies and to gain livelihood.
For example: There formerly
roamed the African deserts a litNa
creature much like the giraffe bn,
with just normal neck. Here and
there he cantered over the desert
feeding on the succulent leaves Of the
palms that we're within easy reach.
One year blight fell on the palm
trees; they withered and the leaves
dropped OF, beginning with the lowest
and gradually running up to the ton,
Along with their passing went the
food OF the short-neckeds giraires. By
and by there were ,only4the top leave,
left to eat. The smaller animals could
not reach these and so persisted for
want of food. Only those CRATES
whose necks we're long enough to
reach the leaves high up survived.
Now as provision for just that thing
It Is one Of natures inflexible laws
that not only does like produce like,
but individual characteristics are &C.
centuated. Here were only the extra
long-necked giraffes left to interbreed.
Naturally, only this sort would appear
among the young. and so the new
breed appeared with necks longer than
any CRATES had known before.
Throughout nature one finds, there
fore, the gradual adaptation to locality
and conditions. ~,
Every year on the coasts OF Labra-
dor and Newfoundland thousands Of
near-seal are slaughtered for their
hide, which is a substitute for shoe
leather. The baby seal or pups" as
they are called, are snow white with
a nothing that is grayish.
r. We're these baby seals the dull
brown or black of the adults and Ca
vorting here and there on the Ice
fields, don't you see, they would stand
out in relief Bears and other foes
would see them. make for them and
devour them. But against the white
ice the white seal pup is almost In.
visible even at a very close distance.
BY and by, though, the ice on which
these babies are born. has broken loose
and, caught In the currents, is drifting
southwark: It meets the gulf stream
aud melts. The baby seal must then
put to sea. II, there, 1t were snowy
white object such as 1t was before
TO be seen swimming in deep blue
waters, its. foes would spy 1t at once
and devour 1t forthwith. But by the
time the ice has come so far south
as the gulf stream the baby's coat has
turned brown and he's safe.
How does this happen? Here Is the
probable explanation. Once on time,
in herd of seal. some few were .
bit lighter colored than others. NOV
in the course Of time, the seals fell
afoul of their foes. The bear, let US
suppose, saw the darker skinned
babies and destroyed them, but the
lighter had the more chance to e.
cape. So the lighter, only, were lell
to interbreed, and this seeming fault
Of a white skin at birth became &C 4.
centuated. perpetuated.
The American buffalo Is notable
specimen. See how that great broao
forehead is built to- Withstand tne
gale that sweeps the prairies. ses
the shaggy growth just over the eyes Il
to protect, as he lowers the neao 4
from the sand and dust that drive ovel a
the plain. Verify mother NATURE
equipped this child to Withstand any
thing save the man-made bullet
Look at the zebra, and in MS mos
tied coat you see the shadows css.
by palm fronds on the sands OF y.
native desert, Set in the edge 9
the palms the baby and mother =
hard ito tell from the wayerlns oas.ns
ground Of shrubbery. And so na'u'0
protects. =. ,..-aor,
Throughout the animal kingdom "
these adaptations stare one ~ -. ~
face. SO to speak. The wonderful ~, .Da
Of the deer, white in winter man .ns
him almost invisible against a,ar
snow: the horns, in form ana coiv
like the branches Of trees-wna' w ~.
ter cloak could conceal him from =
friendly eyes? .nd II
Descend to the humber forms al, az
on our trees you will find, II you 10 :,
sharp, the walklng-stick, wee 1' :. !.
an insect that, for all the worlu I'M, !.
sembles a few twigs thrown tose.
on the bark, too, there may t ,s,in,s
butterfly or night moth. with ~ me-
so nearly the color OF the woou :, Ma 4
only when striped like shadows - ~ X