Falling in Love

4. Strictly Incog.

Among the reefs of rock upon the Australian coast, an explorer's dredge

often brings up to the surface some tangled tresses of reddish seaweed,

which, when placed for a while in a bucket of water, begin slowly to

uncoil themselves as if endowed with animal life, and finally to swim

about with a gentle tremulous motion in a mute inquiring way from side

to side of the pail that contains them. Looked at closely with an

attentive eye, the complex moving mass gradually resolves itself into

two parts: one a ruddy seaweed with long streaming fronds; the other, a

strangely misshapen and dishevelled pipe-fish, exactly imitating the

weed itself in form and colour. When removed from the water, this queer

pipe-fish proves in general outline somewhat to resemble the well-known

hippocampus or sea-horse of the aquariums, whose dried remains, in a

mummified state, form a standing wonder in many tiny domestic museums.

But the Australian species, instead of merely mimicking the knight on a

chess-board, looks rather like a hippocampus in the most advanced stage

of lunacy, with its tail and fins and the appendages of its spines

flattened out into long thin streaming filaments, utterly

indistinguishable in hue and shape from the fucus round which the

creature clings for support with its prehensile tail. Only a rude and

shapeless rough draught of a head, vaguely horse-like in contour, and

inconspicuously provided with an unobtrusive snout and a pair of very

unnoticeable eyes, at all suggests to the most microscopic observer its

animal nature. Taken as a whole, nobody could at first sight distinguish

it in any way from the waving weed among which it vegetates.

Clearly, this curious Australian cousin of the Mediterranean sea-horses

has acquired so marvellous a resemblance to a bit of fucus in order to

deceive the eyes of its ever-watchful enemies, and to become

indistinguishable from the uneatable weed whose colour and form it so

surprisingly imitates. Protective resemblances of the sort are extremely

common among the pipe-fish family, and the reason why they should be so

is no doubt sufficiently obvious at first sight to any reflecting

mind--such, for example, as the intelligent reader's. Pipe-fish, as

everybody knows, are far from giddy. They do not swim in the vortex of

piscine dissipation. Being mostly small and defenceless creatures,

lurking among the marine vegetation of the shoals and reefs, they are

usually accustomed to cling for support by their snake-like tails to the

stalks or leaves of those submerged forests. The omniscient schoolboy

must often have watched in aquariums the habits and manners of the

common sea-horses, twisted together by their long thin bodies into one

inextricable mass of living matwork, or anchored firmly with a treble

serpentine coil to some projecting branch of coralline or of quivering

sea-wrack. Bad swimmers by nature, utterly unarmed, and wholly

undefended by protective mail, the pipe-fish generally can neither fight

nor run away: and therefore they depend entirely for their lives upon

their peculiar skulking and lurking habits. Their one mode of defence is

not to show themselves; discretion is the better part of their valour;

they hide as much as possible among the thickest seaweed, and trust to

Providence to escape observation.

Now, with any animals thus constituted, cowards by hereditary

predilection, it must necessarily happen that the more brightly coloured

or obtrusive individuals will most readily be spotted and most

unceremoniously devoured by their sharp-sighted foes, the predatory

fishes. On the other hand, just in proportion as any particular

pipe-fish happens to display any chance resemblance in colour or

appearance to the special seaweed in whose folds it lurks, to that

extent will it be likely to escape detection, and to hand on its

peculiarities to its future descendants. A long-continued course of the

simple process thus roughly described must of necessity result at last

in the elimination of all the most conspicuous pipe-fish, and the

survival of all those unobtrusive and retiring individuals which in any

respect happen to resemble the fucus or coralline among which they

dwell. Hence, in many places, various kinds of pipe-fish exhibit an

extraordinary amount of imitative likeness to the sargasso or seaweed to

whose tags they cling; and in the three most highly developed Australian

species the likeness becomes so ridiculously close that it is with

difficulty one can persuade oneself one is really and truly looking at a

fish, and not at a piece of strangely animated and locomotive fucus.

Of course, the playful pipe-fish is by no means alone in his assumption

of so neat and effective a disguise. Protective resemblances of just the

same sort as that thus exhibited by this extraordinary little creature

are common throughout the whole range of nature; instances are to be

found in abundance, not only among beasts, birds, reptiles, and fishes,

but even among caterpillars, butterflies, and spiders, of species which

preserve the strictest incognito. Everywhere in the world, animals and

plants are perpetually masquerading in various assumed characters; and

sometimes their make-up is so exceedingly good as to take in for a while

not merely the uninstructed ordinary observer, but even the scientific

and systematic naturalist.

A few selected instances of such successful masquerading will perhaps

best serve to introduce the general principles upon which all animal

mimicry ultimately depends. Indeed, naturalists of late years have been

largely employed in fishing up examples from the ends of the earth and

from the depths of the sea for the elucidation of this very subject.

There is a certain butterfly in the islands of the Malay Archipelago

(its learned name, if anybody wishes to be formally introduced, is

_Kallima paralekta_) which always rests among dead or dry leaves, and

has itself leaf-like wings, all spotted over at intervals with wee

speckles to imitate the tiny spots of fungi on the foliage it resembles.

The well-known stick and leaf insects from the same rich neighbourhood

in like manner exactly mimic the twigs and leaves of the forest among

which they lurk: some of them look for all the world like little bits of

walking bamboo, while others appear in all varieties of hue, as if

opening buds and full-blown leaves and pieces of yellow foliage

sprinkled with the tints and moulds of decay had of a sudden raised

themselves erect upon six legs, and begun incontinently to perambulate

the Malayan woodlands like vegetable Frankensteins in all their glory.

The larva of one such deceptive insect, observed in Nicaragua by

sharp-eyed Mr. Belt, appeared at first sight like a mere fragment of the

moss on which it rested, its body being all prolonged into little

thread-like green filaments, precisely imitating the foliage around it.

Once more, there are common flies which secure protection for themselves

by growing into the counterfeit presentment of wasps or hornets, and so

obtaining immunity from the attacks of birds or animals. Many of these

curiously mimetic insects are banded with yellow and black in the very

image of their stinging originals, and have their tails sharpened, _in

terrorem_, into a pretended sting, to give point and verisimilitude to

the deceptive resemblance. More curious still, certain South American

butterflies of a perfectly inoffensive and edible family mimic in every

spot and line of colour sundry other butterflies of an utterly unrelated

and fundamentally dissimilar type, but of so disagreeable a taste as

never to be eaten by birds or lizards. The origin of these curious

resemblances I shall endeavour to explain (after Messrs. Bates and

Wallace) a little farther on: for the present it is enough to observe

that the extraordinary resemblances thus produced have often deceived

the very elect, and have caused experienced naturalists for a time to

stick some deceptive specimen of a fly among the wasps and hornets, or

some masquerading cricket into the midst of a cabinet full of saw-flies

or ichneumons.

Let us look briefly at the other instances of protective coloration in

nature generally which lead up to these final bizarre exemplifications

of the masquerading tendency.

Wherever all the world around is remarkably uniform in colour and

appearance, all the animals, birds, and insects alike necessarily

disguise themselves in its prevailing tint to escape observation. It

does not matter in the least whether they are predatory or defenceless,

the hunters or the hunted: if they are to escape destruction or

starvation, as the case may be, they must assume the hue of all the rest

of nature about them. In the arctic snows, for example, all animals,

without exception, must needs be snow-white. The polar bear, if he were

brown or black, would immediately be observed among the unvaried

ice-fields by his expected prey, and could never get a chance of

approaching his quarry unperceived at close quarters. On the other hand,

the arctic hare must equally be dressed in a snow-white coat, or the

arctic fox would too readily discover him and pounce down upon him

off-hand; while, conversely, the fox himself, if red or brown, could

never creep upon the unwary hare without previous detection, which would

defeat his purpose. For this reason, the ptarmigan and the willow grouse

become as white in winter as the vast snow-fields under which they

burrow; the ermine changes his dusky summer coat for the expensive

wintry suit beloved of British Themis; the snow-bunting acquires his

milk-white plumage; and even the weasel assimilates himself more or less

in hue to the unvarying garb of arctic nature. To be out of the fashion

is there quite literally to be out of the world: no half-measures will

suit the stern decree of polar biology; strict compliance with the law

of winter change is absolutely necessary to success in the struggle for

existence.

Now, how has this curious uniformity of dress in arctic animals been

brought about? Why, simply by that unyielding principle of Nature which

condemns the less adapted for ever to extinction, and exalts the better

adapted to the high places of her hierarchy in their stead. The

ptarmigan and the snow-buntings that look most like the snow have for

ages been least likely to attract the unfavourable attention of arctic

fox or prowling ermine; the fox or ermine that came most silently and

most unperceived across the shifting drifts has been most likely to

steal unawares upon the heedless flocks of ptarmigan and snow-bunting.

In the one case protective colouring preserves the animal from himself

being devoured; in the other case it enables him the more easily to

devour others. And since 'Eat or be eaten' is the shrill sentence of

Nature upon all animal life, the final result is the unbroken whiteness

of the arctic fauna in all its developments of fur or feather.

Where the colouring of nature is absolutely uniform, as among the arctic

snows or the chilly mountain tops, the colouring of the animals is

uniform too. Where it is slightly diversified from point to point, as in

the sands of the desert, the animals that imitate it are speckled or

diversified with various soft neutral tints. All the birds, reptiles,

and insects of Sahara, says Canon Tristram, copy closely the grey or

isabelline colour of the boundless sands that stretch around them. Lord

George Campbell, in his amusing 'Log Letters from the "Challenger,"'

mentions a butterfly on the shore at Amboyna which looked exactly like a

bit of the beach, until it spread its wings and fluttered away gaily to

leeward. Soles and other flat-fish similarly resemble the sands or banks

on which they lie, and accommodate themselves specifically to the

particular colour of their special bottom. Thus the flounder imitates

the muddy bars at the mouths of rivers, where he loves to half bury

himself in the congenial ooze; the sole, who rather affects clean hard

sand-banks, is simply sandy and speckled with grey; the plaice, who goes

in by preference for a bed of mixed pebbles, has red and yellow spots

scattered up and down irregularly among the brown, to look as much as

possible like agates and carnelians: the brill, who hugs a still rougher

ledge, has gone so far as to acquire raised lumps or tubercles on his

upper surface, which make him seem like a mere bit of the shingle-strewn

rock on which he reposes. In short, where the environment is most

uniform the colouring follows suit: just in proportion as the

environment varies from place to place, the colouring must vary in order

to simulate it. There is a deep biological joy in the term

'environment'; it almost rivals the well-known consolatory properties of

that sweet word 'Mesopotamia.' 'Surroundings,' perhaps, would equally

well express the meaning, but then, as Mr. Wordsworth justly observes,

'the difference to me!'

Between England and the West Indies, about the time when one begins to

recover from the first bout of sea-sickness, we come upon a certain

sluggish tract of ocean, uninvaded by either Gulf Stream or arctic

current, but slowly stagnating in a sort of endless eddy of its own, and

known to sailors and books of physical geography as the Sargasso Sea.

The sargasso or floating seaweed from which it takes its poetical name

is a pretty yellow rootless alga, swimming in vast quantities on the

surface of the water, and covered with tiny bladder-like bodies which at

first sight might easily be mistaken for amber berries. If you drop a

bucket over the ship's side and pull up a tangled mass of this beautiful

seaweed, it will seem at first to be all plant alike; but, when you come

to examine its tangles closely, you will find that it simply swarms with

tiny crabs, fishes, and shrimps, all coloured so precisely to shade that

they look exactly like the sargasso itself. Here the colour about is

less uniform than in the arctic snows, but, so far as the

sargasso-haunting animals are concerned, it comes pretty much to the

same thing. The floating mass of weed is their whole world, and they

have had to accommodate themselves to its tawny hue under pain of death,

immediate and violent.

Caterpillars and butterflies often show us a further step in advance in

the direction of minute imitation of ordinary surroundings. Dr. Weismann

has published a very long and learned memoir, fraught with the best

German erudition and prolixity, upon this highly interesting and obscure

subject. As English readers, however, not unnaturally object to trudging

through a stout volume on the larva of the sphinx moth, conceived in the

spirit of those patriarchal ages of Hilpa and Shalum, when man lived to

nine hundred and ninety-nine years, and devoted a stray century or so

without stint to the work of education, I shall not refer them to Dr.

Weismann's original treatise, as well translated and still further

enlarged by Mr. Raphael Meldola, but will present them instead with a

brief _r****, boiled down and condensed into a patent royal elixir of

learning. Your caterpillar, then, runs many serious risks in early life

from the annoying persistence of sundry evil-disposed birds, who insist

at inconvenient times in picking him off the leaves of gooseberry bushes

and other his chosen places of residence. His infant mortality, indeed,

is something simply appalling, and it is only by laying the eggs that

produce him in enormous quantities that his fond mother the butterfly

ever succeeds in rearing on an average two of her brood to replace the

imago generation just departed. Accordingly, the caterpillar has been

forced by adverse circumstances to assume the most ridiculous and

impossible disguises, appearing now in the shape of a leaf or stem, now

as a bundle of dark-green pine needles, and now again as a bud or

flower, all for the innocent purpose of concealing his whereabouts from

the inquisitive gaze of the birds his enemies.

When the caterpillar lives on a plant like a grass, the ribs or veins of

which run up and down longitudinally, he is usually striped or streaked

with darker lines in the same direction as those on his native foliage.

When, on the contrary, he lives upon broader leaves, provided with a

midrib and branching veins, his stripes and streaks (not to be out of

the fashion) run transversely and obliquely, at exactly the same angle

as those of his wonted food-plant. Very often, if you take a green

caterpillar of this sort away from his natural surroundings, you will be

surprised at the conspicuousness of his pale lilac or mauve markings;

surely, you will think to yourself, such very distinct variegation as

that must betray him instantly to his watchful enemies. But no; if you

replace him gently where you first found him, you will see that the

lines exactly harmonise with the joints and shading of his native leaf:

they are delicate representations of the soft shadow cast by a rib or

vein, and the local colour is precisely what a painter would have had to

use in order to produce the corresponding effect. The shadow of

yellowish green is, of course, always purplish or lilac. It may at first

sight seem surprising that a caterpillar should possess so much artistic

sense and dexterity; but then the penalty for bungling or inharmonious

work is so very severe as necessarily to stimulate his imitative genius.

Birds are for ever hunting him down among the green leaves, and only

those caterpillars which effectually deceive them by their admirable

imitations can ever hope to survive and become the butterflies who hand

on their larval peculiarities to after ages. Need I add that the

variations are, of course, unconscious, and that accident in the first

place is ultimately answerable for each fresh step in the direction of

still closer simulation?

The geometric moths have brown caterpillars, which generally stand erect

when at rest on the branches of trees and so resemble small twigs; and,

in order that the resemblance may be the more striking, they are often

covered with tiny warts which look like buds or knots upon the surface.

The larva of that familiar and much-dreaded insect, the death's-head

hawk-moth, feeds as a rule on the foliage of the potato, and its very

varied colouring, as Sir John Lubbock has pointed out, so beautifully

harmonises with the brown of the earth, the yellow and green of the

leaves, and the faint purplish blue of the lurid flowers, that it can

only be distinguished when the eye happens accidentally to focus itself

exactly upon the spot occupied by the unobtrusive caterpillar. Other

larv which frequent pine trees have their bodies covered with tufts of

green hairs that serve to imitate the peculiar pine foliage. One queer

little caterpillar, which lives upon the hoary foliage of the

sea-buckthorn, has a grey-green body, just like the buckthorn leaves,

relieved by a very conspicuous red spot which really represents in size

and colour one of the berries that grow around it. Finally the larva of

the elephant hawk-moth, which grows to a very large size, has a pair of

huge spots that seem like great eyes; and direct experiment establishes

the fact that small birds mistake it for a young snake, and stand in

terrible awe of it accordingly, though it is in reality a perfectly

harmless insect, and also, as I am credibly informed (for I cannot speak

upon the point from personal experience), a very tasty and

well-flavoured insect, and 'quite good to eat' too, says an eminent

authority. One of these big snake-like caterpillars once frightened Mr.

Bates himself on the banks of the sss.

Now, I know that cantankerous person, the universal objector, has all

along been bursting to interrupt me and declare that he himself

frequently finds no end of caterpillars, and has not the slightest

difficulty at all in distinguishing them with the naked eye from the

leaves and plants among which they are lurking. But observe how promptly

we crush and demolish this very inconvenient and disconcerting critic.

The caterpillars _he_ finds are almost all hairy ones, very conspicuous

and easy to discover--'woolly bears,' and such like common and unclean

creatures--and the reason they take no pains to conceal themselves from

his unobservant eyes is simply this: nobody on earth wants to discover

them. For either they are protectively encased in horrid hairs, which

get down your throat and choke you and bother you (I speak as a bird,

from the point of view of a confirmed caterpillar eater), or else they

are bitter and nasty to the taste, like the larva of the spurge moth and

the machaon butterfly. These are the ordinary brown and red and banded

caterpillars that the critical objector finds in hundreds on his

peregrinations about his own garden--commonplace things which the

experienced naturalist has long since got utterly tired of. But has

your rash objector ever lighted upon that rare larva which lives among

the periwinkles, and exactly imitates a periwinkle petal? Has he ever

discovered those deceptive creatures which pretend for all the world to

be leaves of lady's-bedstraw, or dress themselves up as flowers of

buttonweed? Has he ever hit upon those immoral caterpillars which

wriggle through life upon the false pretence that they are only the

shadows of projecting ribs on the under surface of a full-grown lime

leaf? No, not he; he passes them all by without one single glance of

recognition; and when the painstaking naturalist who has hunted them

every one down with lens and butterfly net ventures tentatively to

describe their personal appearance, he comes up smiling with his great

russet woolly bear comfortably nestling upon a green cabbage leaf, and

asks you in a voice of triumphant demonstration, where is the trace of

concealment or disguise in that amiable but very inedible insect? Go to,

Sir Critic, I will have none of you; I only use you for a metaphorical

marionette to set up and knock down again, as Mr. Punch in the street

show knocks down the policeman who comes to arrest him, and the grimy

black personage of sulphurous antecedents who pops up with a fizz

through the floor of his apartment.

Queerer still than the caterpillars which pretend to be leaves or

flowers for the sake of protection are those truly diabolical and

perfidious Brazilian spiders which, as Mr. Bates observed, are

brilliantly coloured with crimson and purple, but 'double themselves up

at the base of leaf-stalks, so as to resemble flower buds, and thus

deceive the insects upon which they prey.' There is something hideously

wicked and cruel in this lowest depth of imitative infamy. A flower-bud

is something so innocent and childlike; and to disguise oneself as such

for purposes of murder and rapine argues the final abyss of arachnoid

perfidy. It reminds one of that charming and amiable young lady in Mr.

Robert Louis Stevenson's 'Dynamiter,' who amused herself in moments of

temporary gaiety by blowing up inhabited houses, inmates and all, out of

pure lightness of heart and girlish frivolity. An Indian mantis or

praying insect, a little less wicked, though no less cruel than the

spiders, deceives the flies who come to his arms under the false

pretence of being a quiet leaf, upon which they may light in safety for

rest and refreshment. Yet another abandoned member of the same family,

relying boldly upon the resources of tropical nature, gets itself up as

a complete orchid, the head and fangs being moulded in the exact image

of the beautiful blossom, and the arms folding treacherously around the

unhappy insect which ventures to seek for honey in its deceptive jaws.

Happily, however, the tyrants and murderers do not always have things

all their own way. Sometimes the inoffensive prey turn the tables upon

their torturers with distinguished success. For example, Mr. Wallace

noticed a kind of sand-wasp, in Borneo, much given to devouring

crickets; but there was one species of cricket which exactly reproduced

the features of the sand-wasps, and mixed among them on equal terms

without fear of detection. Mr. Belt saw a green leaf-like locust in

Nicaragua, overrun by foraging ants in search of meat for dinner, but

remaining perfectly motionless all the time, and evidently mistaken by

the hungry foragers for a real piece of the foliage it mimicked. So

thoroughly did this innocent locust understand the necessity for

remaining still, and pretending to be a leaf under all advances, that

even when Mr. Belt took it up in his hands it never budged an inch, but

strenuously preserved its rigid leaf-like attitude. As other insects

'sham dead,' this ingenious creature shammed vegetable.

In order to understand how cases like these begin to arise, we must

remember that first of all they start of necessity from very slight and

indefinite resemblances, which succeed as it were by accident in

occasionally eluding the vigilance of enemies. Thus, there are stick

insects which only look like long round cylinders, not obviously

stick-shaped, but rudely resembling a bit of wood in outline only. These

imperfectly mimetic insects may often obtain a casual immunity from

attack by being mistaken for a twig by birds or lizards. There are

others, again, in which natural selection has gone a step further, so as

to produce upon their bodies bark-like colouring and rough patches which

imitate knots, wrinkles, and leaf-buds. In these cases the protection

given is far more marked, and the chances of detection are

proportionately lessened. But sharp-eyed birds, with senses quickened by

hunger, the true mother of invention, must learn at last to pierce such

flimsy disguises, and suspect a stick insect in the most

innocent-looking and apparently rigid twigs. The final step, therefore,

consists in the production of that extraordinary actor, the _Xeroxylus

laceratus_, whose formidable name means no more than 'ragged dry-stick,'

and which really mimics down to the minutest particular a broken twig,

overgrown with mosses, liverworts, and lichens.

Take, on the other hand, the well-known case of that predaceous mantis

which exactly imitates the white ants, and, mixing with them like one of

their own horde, quietly devours a stray fat termite or so, from time to

time, as occasion offers. Here we must suppose that the ancestral mantis

happened to be somewhat paler and smaller than most of its

fellow-tribesmen, and so at times managed unobserved to mingle with the

white ants, especially in the shade or under a dusky sky, much to the

advantage of its own appetite. But the termites would soon begin to

observe the visits of their suspicious friend, and to note their

coincidence with the frequent mysterious disappearance of a

fellow-townswoman, evaporated into space, like the missing young women

in neat cloth jackets who periodically vanish from the London suburbs.

In proportion as their reasonable suspicions increased, the termites

would carefully avoid all doubtful looking mantises; but, at the same

time, they would only succeed in making the mantises which survived

their inquisition grow more and more closely to resemble the termite

pattern in all particulars. For any mantis which happened to come a

little nearer the white ants in hue or shape would thereby be enabled to

make a more secure meal upon his unfortunate victims; and so the very

vigilance which the ants exerted against his vile deception would itself

react in time against their own kind, by leaving only the most ruthless

and indistinguishable of their foes to become the parents of future

generations of mantises.

Once more, the beetles and flies of Central America must have learned by

experience to get out of the way of the nimble Central American lizards

with great agility, cunning, and alertness. But green lizards are less

easy to notice beforehand than brown or red ones; and so the lizards of

tropical countries are almost always bright green, with complementary

shades of yellow, grey, and purple, just to fit them in with the foliage

they lurk among. Everybody who has ever hunted the green tree-toads on

the leaves of waterside plants on the Riviera must know how difficult it

is to discriminate these brilliant leaf-coloured creatures from the

almost identical background on which they rest. Now, just in proportion

as the beetles and flies grow still more cautious, even the green

lizards themselves fail to pick up a satisfactory livelihood; and so at

last we get that most remarkable Nicaraguan form, decked all round with

leaf-like expansions, and looking so like the foliage on which it rests

that no beetle on earth can possibly detect it. The more cunning you get

your detectives, the more cunning do the thieves become to outwit them.

Look, again, at the curious life-history of the flies which dwell as

unbidden guests or social parasites in the nests and hives of wild

honey-bees. These burglarious flies are belted and bearded in the very

self-same pattern as the bumble-bees themselves; but their larv live

upon the young grubs of the hive, and repay the unconscious hospitality

of the busy workers by devouring the future hope of their unwilling

hosts. Obviously, any fly which entered a bee-hive could only escape

detection and extermination at the hands (or stings) of its outraged

inhabitants, provided it so far resembled the real householders as to be

mistaken at a first glance by the invaded community for one of its own

numerous members. Thus any fly which showed the slightest superficial

resemblance to a bee might at first be enabled to rob honey for a time

with comparative impunity, and to lay its eggs among the cells of the

helpless larv. But when once the vile attempt was fairly discovered,

the burglars could only escape fatal detection from generation to

generation just in proportion as they more and more closely approximated

to the shape and colour of the bees themselves. For, as Mr. Belt has

well pointed out, while the mimicking species would become naturally

more numerous from age to age, the senses of the mimicked species would

grow sharper and sharper by constant practice in detecting and punishing

the unwelcome intruders.

It is only in external matters, however, that the appearance of such

mimetic species can ever be altered. Their underlying points of

structure and formative detail always show to the very end (if only one

happens to observe them) their proper place in a scientific

classification. For instance, these same parasitic flies which so

closely resemble bees in their shape and colour have only one pair of

wings apiece, like all the rest of the fly order, while the bees of

course have the full complement of two pairs, an upper and an under,

possessed by them in common with all other well-conducted members of the

hymenopterous family. So, too, there is a certain curious American

insect, belonging to the very unsavoury tribe which supplies London

lodging-houses with one of their most familiar entomological specimens;

and this cleverly disguised little creature is banded and striped in

every part exactly like a local hornet, for whom it evidently wishes

itself to be mistaken. If you were travelling in the wilder parts of

Colorado you would find a close resemblance to Buffalo Bill was no mean

personal protection. Hornets, in fact, are insects to which birds and

other insectivorous animals prefer to give a very wide berth, and the

reason why they should be imitated by a defenceless beetle must be

obvious to the intelligent student. But while the vibrating wing-cases

of this deceptive masquerader are made to look as thin and hornet-like

as possible, in all underlying points of structure any competent

naturalist would see at once that the creature must really be classed

among the noisome Hemiptera. I seldom trouble the public with a Greek or

Latin name, but on this occasion I trust I may be pardoned for not

indulging in all the ingenuous bluntness of the vernacular.

Sometimes this effective mimicry of stinging insects seems to be even

consciously performed by the tiny actors. Many creatures, which do not

themselves possess stings, nevertheless endeavour to frighten their

enemies by assuming the characteristic hostile attitudes of wasps or

hornets. Everybody in England must be well acquainted with those common

British earwig-looking insects, popularly known as the devil's

coach-horses, which, when irritated or interfered with, c**k up their

tails behind them in the most aggressive fashion, exactly reproducing

the threatening action of an angry scorpion. Now, as a matter of fact,

the devil's coach-horse is quite harmless, but I have often seen, not

only little boys and girls, but also chickens, small birds, and

shrew-mice, evidently alarmed at his minatory attitude. So, too, the

bumble-bee flies, which are inoffensive insects got up in sedulous

imitation of various species of wild bee, flit about and buzz angrily in

the sunlight, quite after the fashion of the insects they mimic; and

when disturbed they pretend to get excited, and seem as if they wished

to fly in their assailant's face and roundly sting him. This curious

instinct may be put side by side with the parallel instinct of shamming

dead, possessed by many beetles and other small defenceless species.

Certain beetles have also been modified so as exactly to imitate wasps;

and in these cases the beetle waist, usually so solid, thick, and

clumsy, grows as slender and graceful as if the insects had been

supplied with corsets by a fashionable West End house. But the greatest

refinement of all is perhaps that noticed in certain allied species

which mimic bees, and which have acquired useless little tufts of hair

on their hind shanks to represent the dilated and tufted

pollen-gathering apparatus of the true bees.

I have left to the last the most marvellous cases of mimicry of

all--those noticed among South American butterflies by Mr. Bates, who

found that certain edible kinds exactly resembled a handsome and

conspicuous but bitter-tasted species 'in every shade and stripe of

colour.' Several of these South American imitative insects long deceived

the very entomologists; and it was only by a close inspection of their

structural differences that the utter distinctness of the mimickers and

the mimicked was satisfactorily settled. Scarcely less curious is the

case of Mr. Wallace's Malayan orioles, two species of which exactly copy

two pugnacious honey-suckers in every detail of plumage and coloration.

As the honey-suckers are avoided by birds of prey, owing to their

surprising strength and pugnacity, the orioles gain immunity from attack

by their close resemblance to the protected species. When Dr. Sclater,

the distinguished ornithologist, was examining Mr. Forbes's collections

from Timorlaut, even his experienced eye was so taken in by another of

these deceptive bird-mimicries that he classified two birds of totally

distinct families as two different individuals of the same species.

Even among plants a few instances of true mimicry have been observed. In

the stony African Karoo, where every plant is eagerly sought out for

food by the scanty local fauna, there are tubers which exactly resemble

the pebbles around them; and I have little doubt that our perfectly

harmless English dead-nettle secures itself from the attacks of browsing

animals by its close likeness to the wholly unrelated, but

well-protected, stinging-nettle.

Finally, we must not forget the device of those animals which not merely

assimilate themselves in colour to the ordinary environment in a general

way, but have also the power of adapting themselves at will to whatever

object they may happen to lie against. Cases like that of the ptarmigan,

which in summer harmonises with the brown heather and grey rock, while

in winter it changes to the white of the snow-fields, lead us up

gradually to such ultimate results of the masquerading tendency. There

is a tiny crustacean, the chameleon shrimp, which can alter its hue to

that of any material on which it happens to rest. On a sandy bottom it

appears grey or sand-coloured; when lurking among seaweed it becomes

green, or red, or brown, according to the nature of its momentary

background. Probably the effect is quite unconscious, or at least

involuntary, like blushing with ourselves--and nobody ever blushes on

purpose, though they do say a distinguished poet once complained that an

eminent actor did not follow his stage directions because he omitted to

obey the rubrical remark, 'Here Harold purples with anger.' The change

is produced by certain automatic muscles which force up particular

pigment cells above the others, green coming to the top on a green

surface, red on a ruddy one, and brown or grey where the circumstances

demand them. Many kinds of fish similarly alter their colour to suit

their background by forcing forward or backward certain special

pigment-cells known as chromatophores, whose various combinations

produce at will almost any required tone or shade. Almost all reptiles

and amphibians possess the power of changing their hue in accordance

with their environment in a very high degree; and among certain

tree-toads and frogs it is difficult to say what is the normal

colouring, as they vary indefinitely from buff and dove-colour to

chocolate-brown, rose, and even lilac.

But of all the particoloured reptiles the chameleon is by far the best

known, and on the whole the most remarkable for his inconstancy of

coloration. Like a lacertine Vicar of Bray, he varies incontinently from

buff to blue, and from blue back to orange again, under stress of

circumstances. The mechanism of this curious change is extremely

complex. Tiny corpuscles of different pigments are sometimes hidden in

the depths of the chameleon's skin, and sometimes spread out on its

surface in an interlacing network of brown or purple. In addition to

this prime colouring matter, however, the animal also possesses a normal

yellow pigment, and a bluish layer in the skin which acts like the

iridium glass so largely employed by Dr. Salviati, being seen as

straw-coloured with a transmitted light, but assuming a faint lilac tint

against an opaque absorbent surface. While sleeping the chameleon

becomes almost white in the shade, but if light falls upon him he slowly

darkens by an automatic process. The movements of the corpuscles are

governed by opposite nerves and muscles, which either cause them to bury

themselves under the true skin, or to form an opaque ground behind the

blue layer, or to spread out in a ramifying mass on the outer surface,

and so produce as desired almost any necessary shade of grey, green,

black, or yellow. It is an interesting fact that many chrysalids undergo

precisely similar changes of colour in adaptation to the background

against which they suspend themselves, being grey on a grey surface,

green on a green one, and even half black and half red when hung up

against pieces of particoloured paper.

Nothing could more beautifully prove the noble superiority of the human

intellect than the fact that while our grouse are russet-brown to suit

the bracken and heather, and our caterpillars green to suit the lettuce

and the cabbage leaves, our British soldier should be wisely coated in

brilliant scarlet to form an effective mark for the rifles of an enemy.

Red is the easiest of all colours at which to aim from a great distance;

and its selection by authority for the uniform of unfortunate Tommy

Atkins reminds me of nothing so much as Mr. McClelland's exquisite

suggestion that the peculiar brilliancy of the Indian river carps makes

them serve 'as a better mark for kingfishers, terns, and other birds

which are destined to keep the number of these fishes in check.' The

idea of Providence and the Horse Guards conspiring to render any

creature an easier target for the attacks of enemies is worthy of the

decadent school of natural history, and cannot for a moment be

dispassionately considered by a judicious critic. Nowadays we all know

that the carp are decked in crimson and blue to please their partners,

and that soldiers are dressed in brilliant red to please the ******************** who command them from a distance.