The morning news. [volume] (Savannah, Ga.) 1887-1900, 1897-04-04
USE OF COLOR IN ANIMALS.
Protection Against Enemies - En-
abIes Them to Hunt Successfully,
From the New York Times.

Protection Against Enemies - En-
ables Them to Hunt successfully.
From the New York Times.
Mimicry in color in animals, the use OF
color as a protection for animals, birds,
insects and fishes. and collateral matters
formed the subject for a-novel and inter-
esting talk by DR.. Benjamin Sharp before
the Philadelphia Academy of Natural Sci
ences. From that talk the following eX-
cerpts are taken:
Animal coloration is either structural or
useful. The brilliant colors of some of the
minnows are of no actual use, but due to
some structural peculiarities. Useful col
ors are such as cause an animal to re-
semble it's surroundings. escape its enc
mics, or enable it better to creep upon its
prey.
In the white hair of the head we have
the transparent shaft, and under the mi
croscope this shaft always appears black,
though the effect, as a whole, to the max
ed eye, is white.
History tells us of human hair turning
white in a night. Long ago this was as
signed to some acid secretion in the head,
arising through some tremendous nervous
strain. This is wrong. 1t is probably due
to the blood at the base of the hair fore
ing up air bubbles through the shaft. thus
producing disseminated light and the ef
feet of white hair. This power Of
changing the coloration of the hair is
utilized by arctic animals for a color pro
lection
Among structural colors we have the
iridescence SO commonly distributed
through nature. The iridescence of the
soap bubble arises from the fact that, the
bubble being very thin, some light is re-
1ected from the outside of the bubble and
some from the inside.
A microscope examination shows the
mother-of-pearl shell to be made up of
very fine lines so closely put together
that the white light is broken up into its
prismatic colors and we get the so-called
play of colors," or mother of pearl. TAX
ing a very careful cast of mother-of-pearl
shell with very fine lines, the wax will
yield the same iridescence as the mother
of pearl.
Some birds feathers owe their color to
this same cause as in the iridescent spots
on the peacock and the iridescent green
color of the trochilus, the humming bird.
The casting of the skin in the case Of
the snakes is done entire; in the case OF
other animals in large fakes or parts of
the skin In the reptilian casting the new
and the old skins are separated by very
fine layer of hairs called casting hairs"
that seem to push up the outer skin while
the lower one is forming.
Crabs in casting their shells exhibit the
same curious arrangements of casting
hairs which, under the microscope, APP
pear as really worn off.
The gecko has curiously lobed feet, cut
up into ridges, and each covered with mi
croscopic hairs. 1t Is an arrangement
that serves as a sucker and is quite com
mon in the animal kingdom. The fish that
attaches itself to the shark has the same
~principle, a series of Stats like Venetian
blind, that will pull up and cause suction
on the object to which 1t is applied, and
of great value in holding the feet fiat on
objects. or releasing them when it Is nee
essary to let go. Geckos are thus enabled
to crawl all over ceilings and smooth, YER
teal rocks.
The young gecko cannot hold on to up
right surfaces until 1t has shed its first
skin, prior TO which the casting hairs are
lacking.
In a number of cases. hillary salts are
deposited in the skin of the animal for
the deduction Of the distinctive color.
An interesting change of color is going
on In the Caucasian race Russians,
Danes, NorwegiGns, and other northern
tribes are characterized by light hair and
shores and In Southern Asia, people have
dark eyes All the light races are grad
ually going out Of existence-that Is to say,
there is a tendency for the Caucasian race
TO become dark, and this Is probably based
on the action Of the liver. A northerner
living in the tropics tends to torpidity Of
the liver; the hillary salts are not proper
Nv eliminated from tho body. and COM
mence 10 be deposited under the skin. on
the other hand. in cold climates the liver
Is very active and the hillary salts are car
ried off and not deposited in the skin, hair.
and eyes; so we have the light long hair,
and blue eyes.
Civilized races are producing tropical
climate throughout the year, aud even
when living In the extreme north, live in
a temperature Of 70 10 80 degrees all the
year round This acts upon the liver and
The liver upon the skin; and these modern
conditions are gradually driving out OF
existence the light-haired and blue-eyed
races.
Some animals change their color at will.
The color Itself rs always there. but by
contracting certain of these pigment cells
and allowing others 10 expand. temper
airy change can be effected. The chroma-
tOphores from the skin OF a frog represent
pigment cells Some contracted and ex-
banded In different degrees Of expansion
will grade the animal In color. making IL
az times dull-brown. al others green.
In the chameleon, the chromatophores