THE DAILY EVENING TtLEGKArU rillLADELrillA, WEDNESDAY, AUGUST 21, 18G7.
MMRIil AMONU ANIMALS.
Mimicry d Olher Protective Resent.
Iilaucei Aimmii Animals.
From the M'rslmimtrr Jtt.virw.
. There ia bo more convincing proof of tbo
truth, of a comprehenMve theory thau its
power of absorbing ami finding a place for new
facts, and its capability of interpreting phe
nomena which had been previously looked
npoil as unaccountable anomalies. It is thus
that the law of universal gravitation and the
undulatory theory of light have become esta
blished and universally accepted by men of
science. Fact after fact has been brought for
ward as being apparently inconsistent with
them, and one alter another these very facta
have been shown to be the consequences of the
laws they were at first supposed to disprove.
A false theory will never utand this test.
Advancing knowledge brings to light whole
croups of facts which it oannot deal with,
and its advocates steadily decrease in mtm
bprs notwithstanding the ability and scien
tific Will with which it may have been sup
ported. The great name of Edward Forbes
did not prevent his theory of "Polarity in
the Distribution of Organic Heings in Time,"
from dying a natural death; but the most
striking illustration of the behavior of a
false theory is to be found in the "Circular
and Qniuarian System" of classification pro
pounded by MacLoay, and developed by
jSwaiuson, with an amount of knowledge
and ingenuity that have rarely been sur
passed. This theory was eminently attrac
tive, both from its symmetry and complete
ness, and from the interesting nature of the
varied analogies and affinities which it brought
to light aud made use of. The series of Na
tural History volumes in "Lardner's Cabinet
Cyclopsi'dia," in which Mr. Swrainson de
veloped it iu most departments of the animal
kingdom, made it widely known; and in fact
for a long time these were the best and almost
the only popular text-books for the rising
generation of naturalists. It was favorably
received too by the older school, which
w.as perhaps rather an indication of its
unsoundness. A considerable number of
well-known naturalists either spoke ap
provingly of it, or advocated similar princi
ples, and for a good many years it was de
cidedly in the ascendant. With such, a favor
able introduction, and with such talented ex
ponents, it must have become established if it
had had any germ of truth in it; yet it quite
died out in a few short years, its very exist
ence is now a matter of history, and so rapid
was its fall that its talented creator, Swainson,
perhaps lived to be the last man who believed
in it.
Such, is the course of a false theory. That
of a true one is very different, as may be well
seen by the progress of opinion on the subject
of Natural Selection. In less than eight years
'The Origin of Species" has produced convic
tion in the minds of a majority of the most
eminent living men of science. New facts,
new problems, new difficulties as they arise
aro accepted, solved, or removed by this
theory; and its principles are illustrated by
the progress and conclusions of every other
well established branch of human knowledge.
It is the object of the present article to show
how it has recently been applied to connect
together and explain a variety ef curious facts
which had long been considered as inexplica
ble anomalies.
Perhaps no principle has ever been an
nounced so fertile in results as that which Mr.
Parwin so earnestly impresses upon us, and
which is indeed a necessary deduction from
the theory of Natural Selection namely,
that none of the definite facta of organic
nature, no special organ, no characteristic
form or marking, no peculiarities of instinct
or of habit, no relations between species or
between group of species, can exist, but
which must now be or once have been use
ful to the individual or the races which
possess them. This great principle gives us
a clue which we can follow out in the study
of many recondite phenomena, and leads
as to seek a meaning and a purpose of some
definite character in minutiae which we should
be otherwise almost sure to pass over as in
significant or unimportant.
The adaptation of the external coloring of
animals to their conditions of life has long
been recognized, and has been imputed either
"to an eriginally created specific peculiarity or
to the direct action of climate, soil, or food.
"Where the former explanation has been ac
cepted, it has completely checked inquiry,
since we could never get any further than the
fact of the adaptation. There was nothing
more to be known about the matter. The
second explanation was soon found to be quite
inadequate to deal with all the varied phases
of the phenomena, and to be contradicted by
many well-known facts. For example, wild
rabbits are always of grey or brown tints
well suited for concealment among grass and
fern. But when these rabbits are domes
ticated, without any change of climate or
food, they vary into white or black,
and these varieties may be multiplied to
any extent, forming white or black
races. Exactly the same thing lias oc
curred with Tizeons: aul in the case of
rats and mice, the white variety has not been
Ebown to be at all dependent on alteration of
climate, food, or other external conditions. In
many cases the wings of an insect not only
assume the exact tint ot the bark or leaf it is
accustomed to reBt on, but the form and vein-
ing of the leaf or the exact rugosity ot the
, bark Is imitated; and these detailed inodinca
tions cannot be reasonably imputed to climate
or to food, since in many cases the speoies
aoes not leea ontlie substance it resembles,
and, when it does, no reasonable connection
can be shown to exist between the supposed
cause ana tue eiiect produced. It was re
served for the theory ot Natural Selection to
solve all these problems, and many others
which were not at first supposed to be directly
connected witn them. To make these latter
Intelligible, it will be necessary to cive
sketch of the whole series of phenomena which
may be classed under the head of useful or
protective resemblances.
Concealment more or less complete is use
ful to many animals, and absolutely essen-
tial to some, mose wnicu nave numerous
enemies from which they cannot escape . by
rapidity or motion, nua satoty in conceal
ment. Those which prey upon others must
also be bo constituted as not to alarm them
by their presence or their approach, or they
would soon die or Hunger, jnow h is re.
markable in how many cases nature gives
this boon to the animal, by coloring it with
euch tints as may best serve to enable it to
escape from its enemies or to entrap its prey.
Desert animals, as a rule, are desert-colored.
The lion is a typical example of this, and must
he almost invisible when crouched upon the
sand or among desert rocks and stones. Ante
lopes are all more or less sandy-oolored. The
camel ia preeminently so. The Egyptian cat
and the Pampas cat are sandy or earth
colored. The Austrian kangaroos are of the
8ame tints, and the original color of the wild
horse ia supposed to have been a bandy or clay
color. . , , ,
The desert birds are still more remarkably
protected by their assimilative hues. The
itonechats, the larks, the quails, the goat-
tnnkers, and the pronse, which abound in tlm
North African and Asiatic deserts,, are all
tinted and mottled, so as to resemble, with
wonderful accuracy, the average color
and ntpect of the soil In the district they in
Labit. The liev. II. Tristram, in bis account
of the ornithology of North Africa in the first
volnmeofthe "ibis," says: "In the desert,
where neither trees, brushwood, nor even un
dulation of the surface afford the slightest
protection from its foes, a modification of color
which shall be assimilated to that of the sur
rounding country is absolutely necessary.
Hence, without exception, the upper plumage
of every bird, whether lark, chat, Rylvian, or
sand grouse, and also the fur of all the smaller
mammals, and the skin of all the snakes and
lizards, is of one uniform isabelline or sand
color." After the testimony of so able an
obperver, it is unnecessary to adduce further
examples of the protective colors of desert
animals.
Almost equally striking are the cases of
arctic anima'i possessing the white color
that lest torcenls them upon snowlields
and icebergs. The polar bear is the only
bear that is white, and it lives constantly
among snow and ice. The arctic fox, the
ermine, and the alpine have change to white
in winter only, because in summer white
would be more conspicuous than auy other
color, and therefore a danger rather than
a protection; but the American uolar hare.
inhabiting regions of almost perpetual snow,
is white all the year round. Other animals
inhabiting the same Northern regions do not,
however, chance color. The sable is a eood
example, for throughout the severity of a
biberian winter it letains the rich brown fur.
But its habits are such that it does not need
the protection of color, for it is said to be able
to subset (in fruits and berries in winter, and to
bo so active upon the trees as to catch small
birds among the branches. So also the woo 1
cbuck of Canada has a dark-brown fur; but
then it lives in burrows, and frequents river
banks, catching fish and small animals that
live in or near the water.
Among birds the ptarmigan is a fine exam
ple of protective coloring. Its summer plumage
so exactly harmonizes with the lichen-colored
stones among which it delights to sit, that a
person may walk through a flock of them
without seeing a single bird; while in winter
its white plumage is an almost equal protec
tion. The snow-bunting, the jerfalcon, and
the snowy owl are also white-colored birds
inhabiting the arctic regions, and there can be
little doubt I nt that their coloring is, to some
extent, protective.
Nocturnal animals supply us with equally
good illustrations. Mice, rats, bats, and moles
possess the least conspicuous of hues, and
must be quite invisible at times when any
light color would be instantly seen. Owls and
goatsuckers are of those dark mottled tints
that will assimilate with bark and lichen, and
thus protect them during the day, and at the
same time be inconspicuous in the dusk.
It is only in the tropics, among forests
which never lose their foliage, that we find
whole groups of birds whose chief color is
green. The panots are the most striking
example, but we have also a group of green
pigeons in the East ; and the barbets, leaf
thrushes, bee-eaters, white-eyes, turacos, and
several smaller groups, have so much green in
their plumage as to tend greatly to conceal
them among the foliage.
The conformity of tint which has been so
far shown to exist between animals and their
habitations is of a somewhat general
character; we will now consider the cases
of more especial adaptation. ' If the lion is
enabled by his sandy color readily to con
ceal himself by merely crouching down
upon the desert, how, it may be asked, do
the elegant markings of the tiger, the
aguar, and the other large cats agree with
this theory? We reply that these are
generally cases of more or less special adapta
tion. The tiger is a jungle animal aud
hides himself among the tufts of grass or of
bamboos, and in these positions the vertical
stripes with which his body is adorned must
so assimilate with the vertical stems of the
bamboo, as to assist greatly in concealing
him from his approaching prey, llow re
markable it is, that, besides the lion aud
tiger, almoBt all the other largo cats are
arboreal in their habits, and almost all have
ocellated or spotted skins, which must cer
tainly tend to conceal them with a back,
ground ot foliage; while the one exception,
the puma, has an ashy brown uniform fur,
and has the habit of clinging so closely to a
limb of a tree while waiting for his prey to
pass beneath as to be hardly distinguishable
lrom the bark !
Among birds, the ptarmigan, already men
tioned, must be considered a remarkable case
of special adaptation. Another is a noutu
American goatsucke (Cuprimulgus rupextris),
which rests in tue bright sunsmne on little
bare locky islets iu the Upper Rio Negro,
where its unusually light colors so closely
resemble the rock and sand, that it can
Bcarcely be detected till trodden upon.
The Duke of Argyll, in his "Reign of Law,"
has pointed out the admirable adaptation of
the colors of the woodcock to its protection.
The various browns and yellows and pale ash
color that occur in fallen leaves are all repro
duced in its plumage, so that when, according
to its habit, it rests upon the ground under
trees, it is almost impossible to detect it. In
snipes the colors are modified so as to be
equally in hannony with the prevalent forms
and colors of marshy vegetation.
Reptiles offer us many similar examples.
The most arboreal lizards, the iguanas, are as
green as the leaves they feed upon, and the
slender whip-snakes are rendered almost in
visible as they glide among the foliage by a
similar coloration. How diiiioult it ia some
times to catch Bight of the little greun tree
frogs Bitting on the leaves of a small plant
enclosed in a glass case in the Zoological Har
dens I yet how much better concealed must
they be among the iresh green damp foliage of
a marshy forest 1 There is a North American
frog found on lichen-covered rocks and walls'
which is so colored as exactly to resemble
th em, and as long as it remains quiet would
certainly escape detection. Some of the geckos
which cling motionless on the trunks of trees
iu the tropics are of such curiously marbled
colors as to match exactly with the bark they
rest upon.
In every part of the tropics there are tree
snakes that twist among boughs and shrubs, or
lie coiled up on the dense masses of foliage.
These are of many distinct groups, and com
prise both venomous and harmless genera; but
almost all of them are of a beautiful green color,
sometimes more or less adorned with white or
dusky bands and spots. There can be no
doubt but that this color is doubly useful to
them, since it will tend to conceal them from
their enemies, and will lead their prey to ap
proach them Unconscious of danger. Dr. Guu-
ther informs us that there ia only one genus of
true arboreal snakes (.Jiipsas), whose colors
are rarely green; but are of various shades of
black, brown, and olive, and these are all noc
turnal reptiles, and, there can be little doubt.
conceal themselves during the day in holes, so
that the green protective tint would be useless
to them, and they accordingly retain the more
usual reptilian hues.
Fishes present similar Instances. Many flat
fish, as for examplfl the flounder and the skate,
ar exactly the color of the gravel or sand on
which they habitually rest. Among the ma
rine flower gardens of an Kastem coral reef,
the fishes present every variety of gorgeons
color, while the river lish even of the tropic
rarely, if ever, have gay or conspicuous mark
ings. A very curious case' of this kind of
adaptation occurs in the sea horses ( Uivpo
covipun) of Australia, some of which bear long
foliaceons appendages resembling seaweed,
and are of a brilliant red color; and they are
known to live among seaweed of the same hue;
so that when at rest they must be quite invisi
ble. They are now in the aquarium of the
Zoological Society some slender green pipe
fish which fasten themselves to any object at
the bottom by their prehensile tails, and float
about with the current, looking exactly like
some simple cylindrical alg.T.
It is, however, in the insect world that this
principle of the adaptation of animals to their
environment is most fully and strikingly de
veloped. In order to understand how general
this is, it is necessary to enter somewhat into
details, as we shall thereby be better able to
appreciate the significance of the still more
remarkable phenomena we shall presently
have to discuss. It seems to be in proportion
to their sluggish motions or the absence of
other means of defenfe, that insects possess
the protective coloring. In the tropics there
are thousands of species of insects which rest
during the day clinging to the bark of dead or
fallen trees; and the greater portion of these
are delicately mottled with grey and brown
tints, which though symmetrically disposed
and infinitely varied, yet blend so completely
the usual colors of the bark, that, at two or
three feet distance, they are quite undistin
guishable. In some cases, a species is known
to frequent only one species of tree. This
is the case with the 'common South Ameri
can long-horned beetle (Onschocerus Scor
pio), which, Mr. Bates informs us, is found
only on a rough-barked tree, called Tapi
riba, on the Amazon. It is very abundant,
but so exactly does it resemble the bark in
color and rugosity, and bo closely does it cling
to the branches, that until it moves it is abso
lutely invisible. An allied species (O. con
cetitricus) is found only at Pari on a distinct
species of tree, the bark of which it resembles
with equal accuracy. Both these insects are
abundant, and we may fairly conclude that
the protection they derive from this strange
concealment is at least one of the causes that
enables the. race to flourish.
Many of the species of Cicindela, or tiger
beetle, will illustrate this mode of protection.
Our common Cicindela campestris frequents
grassy banks, and is of a beautiful green color,
while C. maritima, which is found only on
sandy sea-shores, is of a pale bronzy yellow,
so as to be almost invisible. A great number
of the species found by Mr. Wallace in the
Malay islands are similarly protected. The
beautiful Cicindela gloriosa, of a very deep
velvety green color, was only taken upon wet
mossy stones in the bed of a mountain stream,
where it was with the greatest difficulty de
tected. A large brown species (C. Aeros)
was found chiefly on dead leaves in forest
paths; and one which was never seen, except
on the wet mud of salt marshes, was of a glossy
olive so exactly the color of the mud as
only to be distinguished when the sun shone,
by its shadow 1 Where the sandy beach was
coralline and nearly white, he found a very
pale Cicindela; wherever it was volcanic and
black, a dark species of the same genus wa3
sure to be met with.
There are in the East small beetles of
the family Buprestid;e which generally rest
on the midiib of a leaf; and the naturalist
often hesitates before picking them off, so
closely do they resemble pieces of bird's
dung. Kirby and Speuce mentien the
small beetle Onthophilus sulcatus as being
like the seed of an umbelliferous plant; and
another tinall weevil, which is much perse
cuted by predatory beetles of the genus
Harpalus, is of the exact color of loamy soil,
and was found to be particularly abundant
in loam pits. Mr. Bates mentions a small
beetle (Chlamys pitula) which was imdis
tinguishable by the eye from the dung of
caterpillars, while some of the CassiJ.e, from
their hemispherical forms and pearly gold
color", resemble glittering dew-drops upon the
leaves.
A number of our small brown and speckled
weevils, at the approach of any object,
roll off the leaf they are sitting on, at the
same time drawing in their legs and an
tenna1, which fit so perfectly into cavities for
their reception, that the insect becomes a mere
oval brownish lump, which it is hopeless to
look for among the similarly colored little
stones and earth pellets among which it lies
motionless.
The distribution of color in butterllies and
moths respectively is very instructive from
this point of view. The former have all their
brilliant coloring on the upper surface of all
lour wings, while the under surface is aimosi
always soberly colored, and often very dark
and obscure. The moths, ou the contrary,
have generally their chief color on the hind
wings only, the upper wings being of dull,
sombre, and often imitative tints, and these
generally conceal the hind wings when the
insects are in rerose. This arrangement oi
the colors is therefore eminently protective,
because the butterfiy always resta with his
wings raised so as to conceal the dangerous
brilliancy of his upper surface. It is probable
that if we watched their habits sufficiently
we should find the under surface of the
wings of butterllies very frequently imita
tive and protective. Mr. T. W. Wood has
pointed out that the little orange-tip butter-
lly olten rests in the evening on the greeu
and white llower heads of an umbelliferous
plant, and that, when observed in this posi
tion, the beautiful green and white mottling
of the under surface completely assimilates
with the llower heads, and renders the crea
ture very difficult to ls seen. It is pro
bable that the rich dark coloring of the
under side of our peacock, tortoise-shell, and
red-admiral butterllies answers a similar pur
pose. Two curious South American butterflies
that always settle on the trunks of trees
(Gyuecia Uirce and Callizona acesta) have the
under surface curiously striped and mottled,
and when viewed obliquely must closely
assimilate with the appearance of the furrowed
bark of many kinds of trees. Hut the most
wonderful and undoubted case of protective
resemblance in a butterfly which we have
ever seen is that of the common Indjau
Kallima inachis, and its Malayan ally, Kal
linia paralekta. The upper surface of these
insects is very striking and showy, as they
are of a large size, and are adorned with a
broad band of rich orange on a deep bluish
ground. The under side ia very variable in
color, eo that out of fifty specimens no two can
be found exactly alike, but every one of them
w ill be of some shade of ash or brown orochrt,
such, w are found among dead, dry, or decaying
lea. The apex of the upper wings ia pro
duo bto an acute point, a very common form
in tV leaves of tropical shrubs and trees, aud
the lower wings are also produced into a
short, narrow tail. Between these two points
runs a dark curved line exactly representing
the midrib of a leaf, and from, this radiate on
each Bide a few oblique lines, which serve to
indicate the lateral veins of a leaf. These
marks are more clearly seen on the outer por
tion of the base of the wings, and on the inner
side towards the middle and apex, aud it ia
very curious to observe how the usual margi
nal and transverse Btrinc of the group are here
modilied and strengthened so as to become
adapted for an imitation of the venation of a
leaf. e come now to a still more extraordi
nary part of the imitation, for we find repre
sentation of leaves in every stage of decay,
variously blotched and mildewed and pierced
with holes, and in many cases irregularly
covered with powdery black dots gathered
Into patches and spots, so closely resembling
the various kinds of minute fungi that grow
on dead leaves, that it ia impossible to avoid
thinking, at first sight, that the butterflies
themselves have been attacked by real fungi.
But this resemblance, close as it is, would
be of little URe if the habits of the insect did
not accord with it. If the butterfly sat upon
leaves or upon flowers, or opened its wings so
as to expose the upper surface, or exposed
and moved its head and antenme as many other
butterflies do, its disguise would be of little
avail. We might be sure, however, from the
analogy of many other cases, that the habits
of the insect are such as still further to aid its
deceptive garb; but we are not obliged to make
any such supposition, since the present writer
has himself bad the good fortune to observe
scores of Kalama paralekta, in Sumatra, and
to capture many of them, and can vouch for
the accuracy of the following details. These
butterllies frequent dry forests, and fly very
swiltly. They were never seen to settle on a
llower or a green leaf, but were many times
suddenly lost Bight of in a bush or tree of dead
learea. On such occasions they were gene
rally searched for in vain, for while gazing
intently at the very spot where one had dis
appeared, it would olten suddenly dart out,
and again vanish twenty or fitty yards further
on. On one or two occasions the insect was
detected reposing; and it could then be seen
how completely it assimilates itself to the sur
rounding leaves. It sits on a nearly upright
twig, the wings fitting closely back
to back, concealing the antenmc
and head, which are drawn up be
tween their bases. The little tails of the hind
wing touch the branch, and form a perfect
stalk to the leaf, which is supported in ita
place by the claws of the middle pair of feet,
which are slender and inconspicuous. The
rregular outline of the wings gives exactly
the perspective effect of a shrivelled leaf. We
thus have size, color, form, markings, and
nabits, all combining together to produce a
disguise which may be said to be absolutely
perfect; and the protection which it affords ia
sufficiently indicated by the abundance of the
individuals that possess it.
We need not adduce any more examples to
show how important are the details of form
and of coloring in animals, and that their very
existence may often depend upon their being
by these means concealed from their enemies.
This kind of protection is found apparently in
every class and order, for it has been noticed
wherever we can obtain sufficient knowledge
of the details of an animal's life-history. It
varies in degree from the mere absence of con
spicuous color or a general harmony with the
prevailing tints of nature, up to such a minute
and detailed, resemblance to inorganic or vege
table structures as to realize the talisman of the
fairy tale, and to give its possessor the power
of rendering itself invisible.
We will now endeavor to show how these
wonderful resemblances have most probably
been brought about. Returning to the higher
animals, let us consider the remarkable fact of
the rarity of white coloring in the mammalia
or birds of the temperate or tropical zones in a
state of nature. There is not a single white
land-bird or quadruped in Europe, except the
few arctic or alpine species to which white ia a
protective color. Yet in many of these crea
tures there seems to be no inherent tendency
to avoid white, for directly they are domesti
cated white varieties arise and appear to thrive
as well as others. We have white mice and
rats, white cats, horses, dogs, and cattle, white
poultry, pigeons, turkeys, and ducks, and
white rabbits. Some of these animals have
been domesticated for a long period, othera
only for a few centuries; but in almost
every case in which an animal ha3 been
thoroughly domesticated, parti-colored and
white varieties are produced and become per
manent. It is also well known that animals in a
state of nature produce white varieties
occasionally. Blackbirds, starlings, aud crowa
are occasionally seen white, as well aa ele
phants, deer, tigers, hares, moles, and many
other animals; but in no case ia a permanent
white race produced. Now there are no sta
tistics to show that the normal-colored pa
rents produce white offspring oftener under
domestication than in a Btate of nature, and
we have no right to make such an assumption
if the facts can be accounted for without it.
But if the colors of animals do really, in the
various instances already adduced, serve for
their concealment and preservation, then
white, or any other conspicuous color, must
be hurtful, and must in most cases shorten
an animal's life. A white rabbit would be
more surely the prey of hawk or buzzard
and the white mole, or field mouse, could
not long escape from the vigilant owl. So,
also, any deviation from those tints best
adapted to conceal a carnivorous animal
would render the pursuit of ita prey much
more difficult, would place it at a disadvan
tage among its fellows, aud in a time of
scarcity would probably cause it to starve
to death. Ou the other hand, if an animal
spreads from a temperate into an arctic
district, the conditions are changed. During
a large portion of the year, and just
v beu the struggle for existence is most severe,
white is the pievailing tint of nature, and
dark colors will be the most conspicuous. The
white varieties will now have an advantage;
they will escape from their enemies or will
secure food, while their brown companions
will be devoured or will starve: and, as "like
produces like" is the established rule iu
nature, the white race will become perma
nently established; and dark varieties, when
they occasionally appear, will soon die out
from their want of adaptation to their envi
ronment. In eac h case the fittest will survive,
and a race will be eventually produced
adapted to the conditions in which it lives.
We have here an illustration of the simple
and effectual means by which animals are
brought into harmony with the rest of nature.
That slight amount of variability in every
species which we olteu look upon as something
acc idental or abnormal, or so insignificant as
to be hardly worthy of notice, la yet the foun
dation of all those wonderful and harmonious
resemblances which play such an important
part in the economy of nature. Variation is
generally very nuall in amount, but it ia all
that is required, because the change in the
external conditions to which an animal is sub
ject ia generally very slow and intermittent..
When these changes have taken place too
rapidly, the result has often been the ex
tinction of species; but the general rule is,
that climatal and geological changes go on
Blowly. and the Blight but continual varia
tions, in the color, form, and Btruoture of all
animals, has furnished individuals adapted to
these chapges, aud who have become the pro
genitors of modified races. Iwipid multiplica
tion, Incessant slight variation, una survivmui
the flttf(4 these sr the laws which ever keep
the organic world iu harmony with the inor
ganic, and with itself. These are the laws
which we believe have produced all the cases
of protective resemblance already adduc e!, as
well as those still more curious examples we
have yet to bring before our readers.
It must always be borne in mind that the
more wonderful examples, iii which there ia
not only a general but a special resemblance
as in the walking leaf, the mossy phasma, and
the leaf-winged butterfly represent those few
instances in which the process of modification
has been going on during an immense
series of generations. They all occur in
the tropics, where the conditions of exist
ence are the most favorable, and where
climatic changes have for long p
riods been hardly perceptible. In most
of them, favorable variations both of
color, form, structure, and instinct or habit,
must have occurred to produce the perfect
adaptation we now behold. All these are
known to vary; and favorable variations,
when not accompanied by others that were
unfavorable, would certainly survive. At one
time a little step might be made in thi3 direc
tion, at another time in that a change of con
ditions might sometimes render nselesa that
which it had taken ages to produce great
and sodden physical modiflcatioua might often
produce the extinction of a race just aa it was
approaching perfection, and a huddred checks
of which we can know nothing may have re
tarded the rrocrss towards nerfect adaptation:
bo that we can hardly wonder at the few cases
in which a result has been attained which is
shown to be successful by the abundance
and wide diffusion of the creatures so pro
tected.
It ia as well here to reply to an objection
that will no doubt occur to many readers,
that if protection is so useful to all animals.
and so easily brought about by variation and
survival of the fittest, there ought to be no
conspicuously colored creatures: and they
will perhaps ask how we account for the bril
liant birds, and painted snakes, and gorgeous
insects that occur abundantly all over the
world. It will be advisable to answer this
question rather fully, in order that we may be
prepared to understand the phenomena of
mimicry," which, it is the special object of
this paper to illustrate and explain.
The slightest observation of the life of ani
mals will show us that they escape from their
enemies and obtain food in an infinite variety
or ways; ana mat their varied habits and in
stincts are in every case adapted to the condi
tions of their existence. The porcupine and
hedgehog have a defensive armor that save3
them from the attacks of most animals. The
tortoise isnot injured by the conspicuous colors
of his shell, because that shell is in most
cases an effectual protection to him. The
skunks of North America find safety in their
power ot emitting an unbearably offensive
odor; the beaver in ita aquatio habits and
solidly constructed abode. In some cases the
chief danger to an animal occurs at one par
ticular period of its existence, and if that is
guarded against, its numbers can easily be
maintained, lliis is the case with many birds,
the eggs and young of whicn are espe
pecially obnoxious to danger, and we find
accordingly a variety of curious con
trivances to protect them. We have nests
carefully concealed, hung from the slender ex
tremities of grass or boughs over water, or
placed in the hollow of a tree with a very
small opening. When these precautions are
successful, so many more individuals will be
reared than can possibly find food during the
least favorable seasons, that there will always
be a number of weakly and Inexperienced
youDg birds who will fall a prey to the
enemies of the race, and thus render necessary
for the stronger and healthier individuals no
other safeguard than their strength aud activ
ity. The instincts most favorable to the pro
duction and rearing of offspring will in these
cases be most important, and the survival of
the fittest will act so aa to keep up and ad
vance those instincts, while other causes which
tend to modify color and marking may continue
their action almost unchecked.
It is perhaps in insects that wo may best
Study the varied means by which animals are
defended or concealed. One of the uses of the
phosphorescence with which many insects are
furnished is probably to frighten away their
enemies; for Ky'by and Spence state that a
ground beetle (Carabus) has been observed
running round and round a luminous centipede
as if afraid to attack it. An immense number of
insects have stings, and some stingless ants of
thegenus Polyrachis aroarmed with strong and
sharp spines on the back, which must render
them unpalatable to many of the smaller in
sectivorous birds. Many beetles of the family
Curculionidaj have the wing cases and other
external parts so excessively hard, that they
cannot be pinned without first drilling a hole
to receive the pin, and it ia probable that all
such find a protection in this excessive hard
ness. Great numbers of insects hide them
selves among the petals of flowers, or in the
cracks of barks and timber; and finally, ex
tensive groups and even whole orders have a
more or less powerful and disgusting smell
and taste, which they either possess perma
nently, or can emit at pleasure. The atti
tudes of 6ome insects may protect them, as
the habit of turning up the tail by the harm
less rove-beetles (Staphylinid.T) no doubt
leads other animals, besides children, to the
belief that they can sting. The curious
attitude assumed by the sphinx cater
pillars is probably a safeguard, as well as
the blood-red tentacles which can sud
denly be thrown out from the neck, by the
caterpillars of all the true swallow-tailed but
terflies. It ia among the groups that possess some
of these varied kinds of protection in a
high degree, that we find the greatest
amount of conspicuous color, or at least the
most complete absence of protective imitation.
The stinging Hymenoptera, wasps, bees, and
hornets, are, as a rule, very showy and bril
liant insects, and there is not a siugle instance
recoeded in which any one of them ia colored
so as to resemble a vegetable or imitate sub
stance. TheChrysididie, or golden wasps, which
do not sting, possess as a substitute the power
of rolling themselves up into a ball, which is
almost as hard and polished aa if really made
of metal and they are all adorned with the
most gorgeous colors.
Here, then, with our very imperfect know
ledge of the life-history of animals, we are
able to see that there are widely varied modes
by which they may obtain protection from
their enemies or concealment from their prey.
Some of these seem to be so complete and
effectual aa to answer all the wants of the
race, and lead to the maintenance of the
largest possible population. When thia ia the
case, we can well understand that no further
protection derived from a modification of color
can be of the slightest use, and the most bril
liant hues may be developed without any pre
judicial effect upon the species. On some of
the laws that determine the development of
color something may be said presently. It is
now merely necessary to show that conceal
ment by obscure or imitative tints ia only one
out of very many ways by which- anunala
maintain their existence; and having done thia
we are prepared to cousider the phenomena of
"mimicry."
It bus been long known to entomologists
that certain insects bear a strange external
resemblance to others belonging to distinct
genera, families, or even orders, and with
which they have no real affinity whatever.
The fact, however, appears to have been
generally considered as dependent upon some
unknown law of "analogy" some system of
nature or "general plan" which had guided
the Creator in designing the myriads o'f in
sect forms, which we could never hope to
understand. In only one case does it appear
that the resemblance wa3 thought to be use
ful, and to have been designed as a means to
a definite and intelligible purpose. The flies
of the genus Volucella enter the newts of beea
to deposit their eggs, so that their larv.e
may leed upon the larva of the bees, and
these flies are each wonderfully like the bee
on which it is parasitic. Kirby aud Spence be
lieved that this resemblance or "miniicryf was
for the express purpose of protecting the flies
from the attacks of the bees, and the con
nection is bo evident that it was hardly possi
ble to avoid this conclusion. The resemblance,
however, of moths to butterflies or to bees, of
beetles to wasps, and of locusts to beetles, has
been many times noticed by eminent writers;
but Bcarcely ever till within the last few years
does it appear to have been considered ttiat
these resemblances had any special purpose,
or were of any direct benefit to the insects
themselves. In this respect they were looked
upon as accidental, as instances of the "curious
analogies" in nature which must be won
dered at but which could not be explained.
Recently, however, these instances have been
greatly multiplied; the nature of the resem
blances has been more carefully studied, and
it has been found that they are often carried
out into such detaila aa almost to imply a
purpose of deceiving the observer. The phe
nomena, moreover, have been shown to follow
certain definite laws, which again all indicate
their dependence on the more general law of
the "survival of the fittest," or "the preser
vation of favored races in the struggle for life."
It will, perhaps, be as well here to state what
these laws or general conclusions are, and then
to give some account of the facta which sup
port them.
The first law Is, that in an overwhelming
majority of cases of mimicry, the animals (or
the groups) which resemble each other in
habit the same country, the same district, and
in most cases are to be found together on the
very same spot.
The second law is, that these resem
blances are not indiscriminate, but are limited
to certain groups, which in every case are
abundant in species and individuals, , and
can often be ascertained to have some special
protection.
The third law is, that the species which re
seauble or "mimio" these dominant groups,
are comparatively less abundant in indivi
duals, and are oftener very rare. ' '
To he Continued.)
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