Idaho semi-weekly world. [volume] (Idaho City, Idaho Territory) 1875-1908, 1889-04-05
MiMiCRY ir NATURE.


variation One Of the Results of the Una-
versai Struggle for Existence.
1o 10 the sea-sioFe and observe the
grasshoppers among the beach grass
ihey fly up at your approach. whiz on
q rod or 50, and aIight. Can you see
them9 They are colored SO nearly like
the sands they live upon that detec-
tlon OF one at rest is almost irnpossi-
Die. On yonder grassy bluff, stones
throw away, you will find none Of
them, but other kinds equally. or al
most equally. lost to sight by their
harmony with their surroundings.
What chance Of life for either
II they suddenly changed places?
They would be so conspicu-
GUS that every passing bird or
other lnsectivorous creature would
sight them. OF course these pro-
tective coiors have been gained by
slow steps. Every grasshopper that
found its preferred food among the
sands was liable to be eaten In the
long run just those would be eaten
which were most easily seen. One
which varied in coloring in never so
small degree, 30 as to be less easily
seen than his brother. would live to
| perpetuate his kind, and his brother
| come to an untimely end; the progeny
! would show the fortunate variation,
and be more likely to be spared
to transmit in increased volume
the probability of the happy coll
oring- Given, then, a brood OF grass
hoppers that find their preferred food
In sandy spots, and unless other and
more powerful forces act upon them it
must result, from their liability to be
eaten by creatures fond OF grasshop-
Ders, that in time they will resemble
in coloring the sand on which they
live; it is impossible that they should
not Any creature not specially pro-
tected by nauseousness, or habit,
or special device OF some sort,
must in the very nature of things, if it
is to live at all, have some other pro-
lection, and that afforded by color and
pattern is by far the most common.
The world is made up of eaters and
eaten, of devices to catch and devices
to avoid being caught.
We may apply the same reasoning
to two kinds of butterflies subject nat
urally to the same class of enemies
that is, living in the same region an6
flying at the same time. II one has tn.
slightest advantage over the other il
the fight for life, by being, for instance
distasteful to one class of common enc
mics, so that these forbear to attack /
after experiment Or by instinct 9TH
result of ancestral experiments), ant
there be among the less favored flock
under circumstances favoring ii
such as distance or shadow, ma
more often than its fellows be mis-
= taken by the enemy for one of it
distasteful neighbors through 1t
! possessions of little more than usua
+ of a certain tint on a part of the wing
9 a little larger spot here, or more {
: the semblance of a band there-ho'
q small soever this difference may be,
Y must, by the very laws Of nature
: selection. be cherished, perpetuatet
g increased, by slow but sure step
e Nor is there any limit to its increas
s except its absolute deception of Ii
IS enemy. So long as there is the Sigh
9 est advantage in variation in deinit
h possible direction, the struggle for e,
g istence will compel that variation
1t Knowing what we now know of Il
laws of life. mimicry of favored rac'
Il might even have been predicted.
o Atlantic.