Windows of Love

Happily, however, the tyrants and murderers do not always have thingsall their own way. Sometimes the inoffensive prey turn the tables upontheir torturers with distinguished success. For example, Mr. Wallacenoticed a kind of sand-wasp, in Borneo, much given to devouringcrickets; but there was one species of cricket which exactly reproducedthe features of the sand-wasps, and mixed among them on equal termswithout fear of detection. Mr. Belt saw a green leaf-like locust inNicaragua, overrun by foraging ants in search of meat for dinner, butremaining perfectly motionless all the time, and evidently mistaken bythe hungry foragers for a real piece of the foliage it mimicked. Sothoroughly did this innocent locust understand the necessity forremaining still, and pretending to be a leaf under all advances, thateven when Mr. Belt took it up in his hands it never budged an inch, butstrenuously 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 mustremember that first of all they start of necessity from very slight andindefinite resemblances, which succeed as it were by accident inoccasionally eluding the vigilance of enemies. Thus, there are stickinsects which only look like long round cylinders, not obviouslystick-shaped, but rudely resembling a bit of wood in outline only. Theseimperfectly mimetic insects may often obtain a casual immunity fromattack by being mistaken for a twig by birds or lizards. There areothers, again, in which natural selection has gone a step further, so asto produce upon their bodies bark-like colouring and rough patches whichimitate knots, wrinkles, and leaf-buds. In these cases the protectiongiven is far more marked, and the chances of detection areproportionately lessened. But sharp-eyed birds, with senses quickened byhunger, the true mother of invention, must learn at last to pierce suchflimsy disguises, and suspect a stick insect in the mostinnocent-looking and apparently rigid twigs. The final step, therefore,consists in the production of that extraordinary actor, the _Xeroxyluslaceratus_, 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 mantiswhich exactly imitates the white ants, and, mixing with them like one oftheir own horde, quietly devours a stray fat termite or so, from time totime, as occasion offers. Here we must suppose that the ancestral mantishappened to be somewhat paler and smaller than most of itsfellow-tribesmen, and so at times managed unobserved to mingle with thewhite ants, especially in the shade or under a dusky sky, much to theadvantage of its own appetite. But the termites would soon begin toobserve the visits of their suspicious friend, and to note theircoincidence with the frequent mysterious disappearance of afellow-townswoman, evaporated into space, like the missing young womenin neat cloth jackets who periodically vanish from the London suburbs.

In proportion as their reasonable suspicions increased, the termiteswould carefully avoid all doubtful looking mantises; but, at the sametime, they would only succeed in making the mantises which survivedtheir inquisition grow more and more closely to resemble the termitepattern in all particulars. For any mantis which happened to come alittle nearer the white ants in hue or shape would thereby be enabled tomake a more secure meal upon his unfortunate victims; and so the veryvigilance which the ants exerted against his vile deception would itselfreact in time against their own kind, by leaving only the most ruthlessand indistinguishable of their foes to become the parents of futuregenerations of mantises.

Once more, the beetles and flies of Central America must have learned byexperience to get out of the way of the nimble Central American lizardswith great agility, cunning, and alertness. But green lizards are lesseasy to notice beforehand than brown or red ones; and so the lizards oftropical countries are almost always bright green, with complementaryshades of yellow, grey, and purple, just to fit them in with the foliagethey lurk among. Everybody who has ever hunted the green tree-toads onthe leaves of waterside plants on the Riviera must know how difficult itis to discriminate these brilliant leaf-coloured creatures from thealmost identical background on which they rest. Now, just in proportionas the beetles and flies grow still more cautious, even the greenlizards themselves fail to pick up a satisfactory livelihood; and so atlast we get that most remarkable Nicaraguan form, decked all round withleaf-like expansions, and looking so like the foliage on which it reststhat no beetle on earth can possibly detect it. The more cunning you getyour detectives, the more cunning do the thieves become to outwit them.

Look, again, at the curious life-history of the flies which dwell asunbidden guests or social parasites in the nests and hives of wildhoney-bees. These burglarious flies are belted and bearded in the veryself-same pattern as the bumble-bees themselves; but their larvae liveupon the young grubs of the hive, and repay the unconscious hospitalityof the busy workers by devouring the future hope of their unwillinghosts. Obviously, any fly which entered a bee-hive could only escapedetection and extermination at the hands (or stings) of its outragedinhabitants, provided it so far resembled the real householders as to bemistaken at a first glance by the invaded community for one of its ownnumerous members. Thus any fly which showed the slightest superficialresemblance to a bee might at first be enabled to rob honey for a timewith comparative impunity, and to lay its eggs among the cells of thehelpless larvae. But when once the vile attempt was fairly discovered,the burglars could only escape fatal detection from generation togeneration just in proportion as they more and more closely approximatedto the shape and colour of the bees themselves. For, as Mr. Belt haswell pointed out, while the mimicking species would become naturallymore numerous from age to age, the senses of the mimicked species wouldgrow sharper and sharper by constant practice in detecting and punishingthe unwelcome intruders.

It is only in external matters, however, that the appearance of suchmimetic species can ever be altered. Their underlying points ofstructure and formative detail always show to the very end (if only onehappens to observe them) their proper place in a scientificclassification. For instance, these same parasitic flies which soclosely resemble bees in their shape and colour have only one pair ofwings apiece, like all the rest of the fly order, while the bees ofcourse have the full complement of two pairs, an upper and an under,possessed by them in common with all other well-conducted members of thehymenopterous family. So, too, there is a certain curious Americaninsect, belonging to the very unsavoury tribe which supplies Londonlodging-houses with one of their most familiar entomological specimens;and this cleverly disguised little creature is banded and striped inevery part exactly like a local hornet, for whom it evidently wishesitself to be mistaken. If you were travelling in the wilder parts ofColorado you would find a close resemblance to Buffalo Bill was no meanpersonal protection. Hornets, in fact, are insects to which birds andother insectivorous animals prefer to give a very wide berth, and thereason why they should be imitated by a defenceless beetle must beobvious to the intelligent student. But while the vibrating wing-casesof this deceptive masquerader are made to look as thin and hornet-likeas possible, in all underlying points of structure any competentnaturalist would see at once that the creature must really be classedamong the noisome Hemiptera. I seldom trouble the public with a Greek orLatin name, but on this occasion I trust I may be pardoned for notindulging in all the ingenuous bluntness of the vernacular.

Sometimes this effective mimicry of stinging insects seems to be evenconsciously performed by the tiny actors. Many creatures, which do notthemselves possess stings, nevertheless endeavour to frighten theirenemies by assuming the characteristic hostile attitudes of wasps orhornets. Everybody in England must be well acquainted with those commonBritish earwig-looking insects, popularly known as the devil’scoach-horses, which, when irritated or interfered with, cock up theirtails behind them in the most aggressive fashion, exactly reproducingthe 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, notonly little boys and girls, but also chickens, small birds, andshrew-mice, evidently alarmed at his minatory attitude. So, too, thebumble-bee flies, which are inoffensive insects got up in sedulousimitation of various species of wild bee, flit about and buzz angrily inthe sunlight, quite after the fashion of the insects they mimic; andwhen disturbed they pretend to get excited, and seem as if they wishedto fly in their assailant’s face and roundly sting him. This curiousinstinct may be put side by side with the parallel instinct of shammingdead, 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 beensupplied with corsets by a fashionable West End house. But the greatestrefinement of all is perhaps that noticed in certain allied specieswhich mimic bees, and which have acquired useless little tufts of hairon their hind shanks to represent the dilated and tuftedpollen-gathering apparatus of the true bees.

I have left to the last the most marvellous cases of mimicry ofall–those noticed among South American butterflies by Mr. Bates, whofound that certain edible kinds exactly resembled a handsome andconspicuous but bitter-tasted species ‘in every shade and stripe ofcolour.’ Several of these South American imitative insects long deceivedthe very entomologists; and it was only by a close inspection of theirstructural differences that the utter distinctness of the mimickers andthe mimicked was satisfactorily settled. Scarcely less curious is thecase of Mr. Wallace’s Malayan orioles, two species of which exactly copytwo pugnacious honey-suckers in every detail of plumage and coloration.As the honey-suckers are avoided by birds of prey, owing to theirsurprising strength and pugnacity, the orioles gain immunity from attackby their close resemblance to the protected species. When Dr. Sclater,the distinguished ornithologist, was examining Mr. Forbes’s collectionsfrom Timorlaut, even his experienced eye was so taken in by another ofthese deceptive bird-mimicries that he classified two birds of totallydistinct families as two different individuals of the same species.

Even among plants a few instances of true mimicry have been observed. Inthe stony African Karoo, where every plant is eagerly sought out forfood by the scanty local fauna, there are tubers which exactly resemblethe pebbles around them; and I have little doubt that our perfectlyharmless English dead-nettle secures itself from the attacks of browsinganimals by its close likeness to the wholly unrelated, butwell-protected, stinging-nettle.

Finally, we must not forget the device of those animals which not merelyassimilate themselves in colour to the ordinary environment in a generalway, but have also the power of adapting themselves at will to whateverobject they may happen to lie against. Cases like that of the ptarmigan,which in summer harmonises with the brown heather and grey rock, whilein winter it changes to the white of the snow-fields, lead us upgradually to such ultimate results of the masquerading tendency. Thereis a tiny crustacean, the chameleon shrimp, which can alter its hue tothat of any material on which it happens to rest. On a sandy bottom itappears grey or sand-coloured; when lurking among seaweed it becomesgreen, or red, or brown, according to the nature of its momentarybackground. Probably the effect is quite unconscious, or at leastinvoluntary, like blushing with ourselves–and nobody ever blushes onpurpose, though they do say a distinguished poet once complained that aneminent actor did not follow his stage directions because he omitted toobey the rubrical remark, ‘Here Harold purples with anger.’ The changeis produced by certain automatic muscles which force up particular

pigment cells above the others, green coming to the top on a greensurface, red on a ruddy one, and brown or grey where the circumstancesdemand them. Many kinds of fish similarly alter their colour to suittheir background by forcing forward or backward certain specialpigment-cells known as chromatophores, whose various combinationsproduce at will almost any required tone or shade. Almost all reptilesand amphibians possess the power of changing their hue in accordancewith their environment in a very high degree; and among certaintree-toads and frogs it is difficult to say what is the normalcolouring, as they vary indefinitely from buff and dove-colour tochocolate-brown, rose, and even lilac.

But of all the particoloured reptiles the chameleon is by far the bestknown, and on the whole the most remarkable for his inconstancy ofcoloration. Like a lacertine Vicar of Bray, he varies incontinently frombuff to blue, and from blue back to orange again, under stress ofcircumstances. The mechanism of this curious change is extremelycomplex. Tiny corpuscles of different pigments are sometimes hidden inthe depths of the chameleon’s skin, and sometimes spread out on itssurface in an interlacing network of brown or purple. In addition tothis prime colouring matter, however, the animal also possesses a normalyellow pigment, and a bluish layer in the skin which acts like theiridium glass so largely employed by Dr. Salviati, being seen asstraw-coloured with a transmitted light, but assuming a faint lilac tintagainst an opaque absorbent surface. While sleeping the chameleonbecomes almost white in the shade, but if light falls upon him he slowlydarkens by an automatic process. The movements of the corpuscles aregoverned by opposite nerves and muscles, which either cause them to burythemselves under the true skin, or to form an opaque ground behind theblue 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 undergoprecisely similar changes of colour in adaptation to the backgroundagainst which they suspend themselves, being grey on a grey surface,green on a green one, and even half black and half red when hung upagainst pieces of particoloured paper.

Nothing could more beautifully prove the noble superiority of the humanintellect than the fact that while our grouse are russet-brown to suitthe bracken and heather, and our caterpillars green to suit the lettuceand the cabbage leaves, our British soldier should be wisely coated inbrilliant 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 TommyAtkins reminds me of nothing so much as Mr. McClelland’s exquisitesuggestion that the peculiar brilliancy of the Indian river carps makesthem serve ‘as a better mark for kingfishers, terns, and other birdswhich are destined to keep the number of these fishes in check.’ Theidea of Providence and the Horse Guards conspiring to render anycreature an easier target for the attacks of enemies is worthy of the

decadent school of natural history, and cannot for a moment bedispassionately considered by a judicious critic. Nowadays we all knowthat the carp are decked in crimson and blue to please their partners,and that soldiers are dressed in brilliant red to please the aestheticauthorities who command them from a distance.

SEVEN-YEAR SLEEPERS

For many generations past that problematical animal, the toad-in-a-hole(literal, not culinary) has been one of the most familiar andinteresting personages of contemporary folk-lore and popular naturalhistory. From time to time he turns up afresh, with his own wontedperennial vigour, on paper at least, in company with the greatsea-serpent, the big gooseberry, the shower of frogs, the two-headedcalf, and all the other common objects of the country or the seaside inthe silly season. No extraordinary natural phenomenon on earth was everbetter vouched for–in the fashion rendered familiar to us by theTichborne claimant–that is to say, no other could ever get a largernumber of unprejudiced witnesses to swear positively and unreservedly inits favour. Unfortunately, however, swearing alone no longer settlescauses off-hand, as if by show of hands, ‘the Ayes have it,’ after thefashion prevalent in the good old days when the whole Hundred used totestify that of its certain knowledge John Nokes did not commit such andsuch a murder; whereupon John Nokes was forthwith acquitted accordingly.Nowadays, both justice and science have become more exacting; theyinsist upon the unpleasant and discourteous habit of cross-examiningtheir witnesses (as if they doubted them, forsooth!), instead ofaccepting the witnesses’ own simple assertion that it’s all right, andthere’s no need for making a fuss about it. Did you yourself see theblock of stone in which the toad is said to have been found, before thetoad himself was actually extracted? Did you examine it all round tomake quite sure there was no hole, or crack, or passage in it anywhere?Did you satisfy yourself after the toad was released from his closequarters that no such hole, or crack, or passage had been dexterouslyclosed up, with intent to deceive, by plaster, cement, or otherartificial composition? Did you ever offer the workmen who found it anominal reward–say five shillings–for the first perfectly unanswerablespecimen of a genuine unadulterated antediluvian toad? Have you got thetoad now present, and can you produce him here in court (on writ of_habeas corpus_ or otherwise), together with all the fragments of thestone or tree from which he was extracted? These are the disagreeable,prying, inquisitorial, I may even say insulting, questions with which amodern man of science is ready to assail the truthful and reputablegentlemen who venture to assert their discovery, in these degeneratedays, of the ancient and unsophisticated toad-in-a-hole.

Now, the worst of it is that the gentlemen in question, being unfamiliarwith what is technically described as scientific methods ofinvestigation, are very apt to lose their temper when thuscross-questioned, and to reply, after the fashion usually attributed tothe female mind, with another question, whether the scientific personwishes to accuse them of downright lying. And as nothing on earth couldbe further from the scientific person’s mind than such an imputation, heis usually fain in the end to give up the social pursuit of postprandialnatural history (the subject generally crops up about the same time asthe after-dinner coffee), and to let the prehistoric toad go on his owntriumphant way, unheeded.

As a matter of fact, nobody ever makes larger allowances for otherpeople, in the estimate of their veracity, than the scientificinquirer. Knowing himself, by painful experience, how extremelydifficult a matter it is to make perfectly sure you have observedanything on earth quite correctly, and have eliminated all possiblechances of error, he acquires the fixed habit of doubting about one-halfof whatever his fellow-creatures tell him in ordinary conversation,without for a single moment venturing to suspect them of deliberateuntruthfulness. Children and servants, if they find that anything theyhave been told is erroneous, immediately jump at the conclusion that theperson who told them meant deliberately to deceive them; in their ownsimple and categorical fashion they answer plumply, ‘That’s a lie.’ Butthe man of science is only too well acquainted in his own person withthe exceeding difficulty of ever getting at the exact truth. He hasspent hours of toil, himself, in watching and observing the behaviour ofsome plant, or animal, or gas, or metal; and after repeated experiments,carefully designed to exclude all possibility of mistake, so far as hecan foresee it, he at last believes he has really settled some mootpoint, and triumphantly publishes his final conclusions in a scientificjournal. Ten to one, the very next number of that same journal containsa dozen supercilious letters from a dozen learned and high-salariedprofessors, each pointing out a dozen distinct and separate precautionswhich the painstaking observer neglected to take, and any one of whichwould be quite sufficient to vitiate the whole body of his observations.There might have been germs in the tube in which he boiled the water(germs are very fashionable just at present); or some of the germs mighthave survived and rather enjoyed the boiling; or they might have adheredto the under surface of the cork; or the mixture might have beentampered with during the experimenter’s temporary absence by his son,aged ten years (scientific observers have no right, apparently, to havesons of ten years old, except perhaps for purposes of psychologicalresearch); and so forth, _ad infinitum_. And the worst of it all is thatthe unhappy experimenter is bound himself to admit that every one of theobjections is perfectly valid, and that he very likely never really sawwhat with perfect confidence he thought and said he had seen.

This being an unbelieving age, then, when even the book of Deuteronomyis ‘critically examined,’ let us see how much can really be said for and

against our old friend, the toad-in-a-hole; and first let us begin withthe antecedent probability, or otherwise, of any animal being able tolive in a more or less torpid condition, without air or food, for anyconsiderable period of time together.

A certain famous historical desert snail was brought from Egypt toEngland as a conchological specimen in the year 1846. This particularmollusk (the only one of his race, probably, who ever attained toindividual distinction), at the time of his arrival in London, wasreally alive and vigorous; but as the authorities of the British Museum,to whose tender care he was consigned, were ignorant of this importantfact in his economy, he was gummed, mouth downward, on to a piece ofcardboard, and duly labelled and dated with scientific accuracy, ‘_Helixdesertorum_, March 25, 1846.’ Being a snail of a retiring and contenteddisposition, however, accustomed to long droughts and corresponding napsin his native sand-wastes, our mollusk thereupon simply curled himselfup into the topmost recesses of his own whorls, and went placidly tosleep in perfect contentment for an unlimited period. Every conchologisttakes it for granted, of course, that the shells which he receives fromforeign parts have had their inhabitants properly boiled and extractedbefore being exported; for it is only the mere outer shell or skeletonof the animal that we preserve in our cabinets, leaving the actual fleshand muscles of the creature himself to wither unobserved upon itsnative shores. At the British Museum the desert snail might have snoozedaway his inglorious existence unsuspected, but for a happy accidentwhich attracted public attention to his remarkable case in a mostextraordinary manner. On March 7, 1850, nearly four years later, it wascasually observed that the card on which he reposed was slightlydiscoloured; and this discovery led to the suspicion that perhaps aliving animal might be temporarily immured within that papery tomb. TheMuseum authorities accordingly ordered our friend a warm bath (who shallsay hereafter that science is unfeeling!), upon which the gratefulsnail, waking up at the touch of the familiar moisture, put his headcautiously out of his shell, walked up to the top of the basin, andbegan to take a cursory survey of British institutions with his foureye-bearing tentacles. So strange a recovery from a long torpidcondition, only equalled by that of the Seven Sleepers of Ephesus,deserved an exceptional amount of scientific recognition. The desertsnail at once awoke and found himself famous. Nay, he actually sat forhis portrait to an eminent zoological artist, Mr. Waterhouse; and awoodcut from the sketch thus procured, with a history of his life andadventures, may be found even unto this day in Dr. Woodward’s ‘Manual ofthe Mollusca,’ to witness if I lie.

I mention this curious instance first, because it is the bestauthenticated case on record (so far as my knowledge goes) of any animalexisting in a state of suspended animation for any long period of timetogether. But there are other cases of encysted or immured animalswhich, though less striking as regards the length of time during whichtorpidity has been observed, are much more closely analogous to the real

or mythical conditions of the toad-in-a-hole. That curious West Africanmud-fish, the Lepidosiren (familiar to all readers of evolutionaryliterature as one of the most singular existing links between fish andamphibians), lives among the shallow pools and broads of the Gambia,which are dried up during the greater part of the tropical summer. Toprovide against this annual contingency, the mud-fish retires into thesoft clay at the bottom of the pools, where it forms itself a sort ofnest, and there hibernates, or rather aestivates, for months together, ina torpid condition. The surrounding mud then hardens into a dry ball;and these balls are dug out of the soil of the rice-fields by thenatives, with the fish inside them, by which means many specimens oflepidosiren have been sent alive to Europe, embedded in their naturalcovering. Here the strange fish is chiefly prized as a zoologicalcuriosity for aquariums, because of its possessing gills and lungstogether, to fit it for its double existence; but the unsophisticatedWest Africans grub it up on their own account as a delicacy, regardlessof its claims to scientific consideration as the earliest known ancestorof all existing terrestrial animals. Now, the torpid state of themud-fish in his hardened ball of clay closely resembles the real orsupposed condition of the toad-in-a-hole; but with one importantexception. The mud-fish leaves a small canal or pipe open in his cell ateither end to admit the air for breathing, though he breathes (as Ishall proceed to explain) in a very slight degree during his aestivation;whereas every proper toad-in-a-hole ought by all accounts to liveentirely without either feeding or breathing in any way. However, thisis a mere detail; and indeed, if toads-in-a-hole do really exist at all,we must in all probability ultimately admit that they breathe to someextent, though perhaps very slightly, during their long immurement.

And this leads us on to consider what in reality hibernation is.Everybody knows nowadays, I suppose, that there is a very close analogybetween an animal and a steam-engine. Food is the fuel that makes theanimal engine go; and this food acts almost exactly as coal does in theartificial machine. But coal alone will not drive an engine; a freedraught of open air is also required in order to produce combustion.Just in like manner the food we eat cannot be utilised to drive ourmuscles and other organs unless it is supplied with oxygen from the airto burn it slowly inside our bodies. This oxygen is taken into thesystem, in all higher animals, by means of lungs or gills. Now, when weare working at all hard, we require a great deal of oxygen, as most ofus have familiarly discovered (especially if we are somewhat stout) inthe act of climbing hills or running to catch a train. But when we aredoing very little work indeed, as in our sleeping hours, during whichmuscular movement is suspended, and only the general organic lifecontinues, we breathe much more slowly and at longer intervals. However,there is this important difference (generally speaking) between ananimal and a steam-engine. You can let the engine run short of coals andcome to a dead standstill, without impairing its future possibilities ofsimilar motion; you have only to get fresh coals, after weeks or monthsof inaction, and light up a fresh fire, when your engine will

immediately begin to work again, exactly the same as before. But if ananimal organism once fairly runs down, either from want of food or anyother cause–in short, if it dies–it very seldom comes to life again.

I say ‘very seldom’ on purpose, because there are a few cases among theextreme lower animals where a water-haunting creature can be taken outof the water and can be thoroughly dried and desiccated, or even keptfor an apparently unlimited period wrapped up in paper or on the slideof a microscope; and yet, the moment a drop of water is placed on top ofit, it begins to move and live again exactly as before. This sort ofthorough-going suspended animation is the kind we ought to expect fromany well-constituted and proper-minded toad-in-a-hole. Whether anythinglike it ever really occurs in the higher ranks of animal life, however,is a different question; but there can be no doubt that to some slightextent a body to all intents and purposes quite dead (physicallyspeaking) by long immersion in water–a drowned man, for example–mayreally be resuscitated by heat and stimulants, applied immediately,provided no part of the working organism has been seriously injured ordecomposed. Such people may be said to be _pro tem._ functionally,though not structurally, dead. The heart has practically ceased to beat,the lungs have ceased to breathe, and physical life in the body istemporarily extinct. The fire, in short, has gone out. But if only itcan be lighted again before any serious change in the system takesplace, all may still go on precisely as of old.

Many animals, however, find it convenient to assume a state of lesscomplete suspended animation during certain special periods of the year,according to the circumstances of their peculiar climate and mode oflife. Among the very highest animals, the most familiar example of thissort of semi-torpidity is to be found among the bears and the dormice.The common European brown bear is a carnivore by descent, who has becomea vegetarian in practice, though whether from conscientious scruples ormere practical considerations of expediency, does not appear. He feedschiefly on roots, berries, fruits, vegetables, and honey, all of whichhe finds it comparatively difficult to procure during winter weather.Accordingly, as everyone knows, he eats immoderately in the summerseason, till he has grown fat enough to supply bear’s grease to allChristendom. Then he hunts himself out a hollow tree or rock-shelter,curls himself up quietly to sleep, and snores away the whole livelongwinter. During this period of hibernation, the action of the heart isreduced to a minimum, and the bear breathes but very slowly. Still, hedoes breathe, and his heart does beat; and in performing thoseindispensable functions, all his store of accumulated fat is graduallyused up, so that he wakes in spring as thin as a lath and as hungry as ahunter. The machine has been working at very low pressure all thewinter: but it _has_ been working for all that, and the continuity ofits action has never once for a moment been interrupted. This is thecentral principle of all hibernation; it consists essentially of a verylong and profound sleep, during which all muscular motion, except thatof the heart and lungs, is completely suspended, while even these last