The Aye-Aye.—Page 269.
This wonderful animal derives its name from the exclamations of surprise uttered by some natives of Madagascar when the creature was first shown to them. It is eminently nocturnal in its habits, and on account of its dark fur and quiet movements is not likely to attract observation. It was first discovered by Sonnerat, who kept a couple of specimens for some time, feeding them upon boiled rice. They fed themselves in a very curious manner, using the long slender fingers of the fore paws for the purpose of conveying the food to the mouth.
A single dead specimen was brought to France by the discoverer, and the stuffed skin placed in the splendid museum in Paris; and for many years this was the only specimen in Europe. The accounts of the habits of the animal were exceedingly meagre; nothing was known of its customs when in a state of freedom, and the only trustworthy information which could be obtained was that which described the colour of the fur.
We hope now to gain more extended knowledge respecting the Aye Aye.
On the 12th of August, 1862, a fine female Aye Aye landed in England. She was in a delicate state of health, for on the voyage she had produced a young one, which only survived its birth for a short time. However, by means of careful treatment she soon improved in health, and is now in very fine condition.
By day she does not appear to the best advantage. She hates daylight, and very much resents its unwelcome intrusion upon her privacy, curling herself up in the darkest corner of the cage, and shading her face with her magnificent black tail. She is a stronger creature than might be supposed from her dimensions, and displays much muscular power in pushing her way into her house.
As she lies in repose the enormous bushy tail is curled round and laid over the face, so that barely any outline is perceptible. It is curious to see how, even in this condition, the large ears are gently moved at every sound, and when the creature is roused from her torpor the brilliancy with which the eyes gleam from among the heavy fur of the tail is really remarkable.
At night, however, the Aye Aye becomes a different being. She moves about with ease and agility, making no rapid or sudden rushes, but quietly walking about the cage, being perfectly indifferent as to the position in which the body may be. She can walk steadily upon the smooth floor, she can walk upon the rough branches of the tree which is laid across her cage, or she can walk along the roof of her house, hanging suspended like the sloth. And she appears to be equally at ease in either attitude, and walks with equal adroitness.
As to the food of the Aye Aye, it may safely be pronounced to be of a mixed animal and vegetable character. Until this specimen was brought to England, the Aye Aye was thought to feed only on insects, the long third finger being supposed to be used in taking them out of the recesses of the rough bark. The specimen, however, which is at present living in the Zoological Gardens totally rejects insects of every kind, and feeds only on a mixture of honey, milk, and the yolk of hard-boiled eggs, beaten up into the consistence of thick cream.
The mode of feeding is very peculiar. Mr. Bartlett, who has paid much attention to this zoological treasure, has published in the Proceedings of the Zoological Society a very interesting paper on the habits of the animal, and gives the following description of its mode of feeding:—
“In feeding, the left hand only is used, although she has the full use of her right one. The mode of taking her food requires careful attention, in consequence of the very rapid movement of the hand during the process. The fourth finger, which is the longest and largest, is thrust forwards into the food, the slender third finger is raised upwards and backwards above the rest, while the first finger or thumb is lowered so as to be seen below and behind the chin. In this position the hand is drawn backwards and forwards rapidly, the inner side of the fourth finger passing between the lips, the head of the animal being held sideways, thus depositing the food in the mouth at each movement; the tongue, jaws, and lips are kept in full motion all the time. Sometimes the animal will advance towards, and lap from, the dish like a cat; but this is unusual.” The keeper tells me, however, that, though she generally prefers the left paw for feeding herself, she frequently employs the right hand for that purpose.
These observations are very valuable, and, when taken in connection with certain habits of the animal, lead us to suppose that in the wild state its mode of feeding is as unique as its appearance.
The observer will see that the branches within its cage are cut about as if they had been exposed to the fire of a rifle company, the boughs being deeply wounded and grooved, with splinters projecting in various directions. These wounds are made by the teeth of the Aye Aye, which, though no larger than a fine cat, possess strength of jaw and sharpness of tooth sufficient to inflict such wounds. It has been suggested that the creature partially feeds on the sap of certain trees, and that by wounding their substance with its teeth it causes the juices to flow, and then conveys them into its mouth by means of the long fourth finger.
As Mr. Bartlett well observes, “I observe that our specimen returns frequently to the same spot on the tree which she had previously injured. I am also strengthened in my opinion by noticing the little attention paid by the animal to the food. It does not watch or look after it; for I have on several occasions removed the vessel containing its food during the time the animal was feeding, and the creature continued to thrust its hand forward as before on the same spot; though, after awhile, finding no more food, she discontinued, and moved off in search for more elsewhere. This apparently stupid act is so unlike the habits of an animal intended to capture or feed on living creatures, that I am inclined to believe that the Aye Aye feeds upon inanimate substances. I have frequently seen it eat a portion of the bark and wood, after taking a quantity of the fluid food.”
She also uses her slender fingers in cleaning her face and ears, and in combing out the long hairs of her beautiful tail.
The animal nature of its food is proved by the observations of the Hon. H. Sandwith, M.D., &c., who kept a fine male Aye Aye for some time, and carefully watched its habits.
Seeing that the animal was constantly using its powerful teeth for the purpose of gnawing its way out of the cage, Dr. Sandwith thought that he would put some branches in the cage, so that it might eat them instead of gnawing the woodwork of its habitation. After the sun had set, the Aye Aye came from his darkened nest, and straightway proceeded to examine the branches, which happened to have been bored by a large grub.
Then was seen the use of the strange second finger, which is not half as thick as any of the others, and, indeed, looks more like a piece of bent wire than a jointed member. With this finger the animal tapped rapidly on the bough, and then listened, as if to judge by the sound whether the branch was tenanted. Having satisfied himself on this point, and having several times thrust his finger, probe fashion, into the holes, he began to bite away the wood with great energy, and in a few minutes succeeded in exposing a large grub, which was picked out of its hole by the same useful finger, and so put into the mouth.
The animal would also eat mangoes, dates, and similar fruit, biting a hole in the rind, and scooping out the interior with the ever-useful finger.
The visitor should, if possible, obtain a view of the teeth, which are sufficiently powerful to bite through the hardest woods, such as ebony or teak—woods which woefully try the temper of our steel-made tools. In the front of the jaw there are four incisor teeth, chisel-shaped, like those of the rabbit and other rodents, but of enormous depth and thickness. Like the rodent teeth, they are furnished with a pulpy substance at their root, from which fresh tooth-substance is developed, so as to supply new tooth from behind as fast as it is worn away in front. They are arranged in a rather curious fashion, so that, when seen directly in front, they look like four rounded points converging towards each other, and really give no conception of their formidable powers.
Between the incisor and the grinder teeth there is a large gap, just as in the rodent tribes, and the skull is arched exactly like that of a rat or rabbit, in order to afford room for the large incisor teeth. There are no canine teeth, and altogether the number of teeth is only eighteen. The muscles which move the jaws are powerful in proportion to the work which they have to perform, and, to a considerable extent, cause the peculiar width of the head.
Those who are unable to see the animal itself will be able to form a very correct idea from Mr. Wolfe’s admirable drawing, which is hung by the cage. No previous figures gave a true idea of the animal’s real shape, as they were necessarily sketched from the stuffed specimen, and, of course, looked shrivelled and death-like.
The Aye Aye is about the size of a large cat, and its face is full, wide, and rather destitute of hair. The upper part of the face is dull flesh-colour, which changes to pink upon the muzzle. The general colour is dull black, the hair being very long, rather scanty, and decidedly coarse. Upon the back many of the hairs become quite white towards the extremities, and have a very fine effect when contrasted with the sober black of the general fur. The tail is deep black and large, like that of a fox, but the hairs are arranged in a different manner, as may be seen from the illustration. Whenever the animal is angry, and spreads its tail, the hairs are seen to be grey at the base, and black as they approach the tips.
The ears are very large, black, and nearly hairless, but studded with little knobs; and the eyes are very large, very full, and of a beautiful chestnut colour. The fingers are very long and slender, and are held in a curious kind of clutching attitude, as is shown in the illustration. When the face is seen directly in front, two of the teeth gleam whitely between the lips, and if the animal should chance to yawn their formidable arrangement becomes visible, and it is easy to see how deeply they can bite into the tree.
The keeper seems to be on very good terms with the animal, which he calls “Jack” in bold defiance of her sex.
It is possible that we may obtain a male specimen of the Aye Aye, and that they may breed in this country, as has been the case with many rare animals, inhabitants of hotter climes. There is, however, a considerable difficulty in obtaining specimens, even when we know where to look for them; for the Aye Aye can only be detected by the watchful eye of the native, who has from his childhood been taught to reverence the Aye Aye as something supernatural, and to fancy that, if he should touch one of these animals, even by chance, he will die within a year. There are but few natives who are strong-minded enough to put themselves in such danger, and even those who are daring enough to seize an Aye Aye require to have their courage stimulated by a very large bribe—enough, in fact, to maintain them through the entire year of peril.
I have written at some length of this wonderful animal, because it is the first living specimen which has ever touched the European shores, and no one can say how long it will live. There are, however, many curious and interesting details of its structure which I cannot mention for lack of space. If the reader should desire to make himself master of the anatomy of the Aye Aye, he will find a vast fund of information in Professor Owen’s monograph upon this creature.
ANOTHER ACCOUNT OF THE AYE AYE.
“Aye Aye!” So exclaimed the natives of the east coast of Madagascar, when first shown the little animal described above. But the exclamation was not of affirmation, but astonishment; for they had never seen it before, and indeed there are reasons for thinking it is confined to the other side of that great continental island, which is so little known, yet in which Christianity has long numbered its devotees, its martyrs, and its apostates.
“But,” says some reader, whose tastes lead him to politics, poetry, or fiction, rather than to Nature, and whose acquaintance with the latter is limited to the creatures which he may eat or be eaten by—“even if I did care to know anything at all about this little beast, with the head of a cat, the tail of a squirrel, the hands of a miser, and the feet of a monkey, all I have to do is to glance at my Beeton’s Dictionary, and find in a nutshell all about the Aye Aye.”
But there is more to be said about the Aye Aye than can be contained in a scientific dictionary, and as to Webster’s Unabridged Dictionary, we pray our readers to listen for a single moment to the following statement, which is made with great regret, since we too once had equal faith in the magnificent work above mentioned. The figure named Aye Aye, upon page 99, would answer equally well for at least a dozen other mammiferous vertebrates, and no one who has ever seen a correct picture of the Aye Aye would recognise this as meant for one; the description of its appearance and habits, though equal in length to that of the elephant, is incorrect in several important points, and neither the figure nor the description affords any information respecting the real peculiarities which distinguish the Aye Aye from all known animals. It is true that similar defects exist in the account given in Wood’s Illustrated Natural History of Mammalia; and there is some excuse for this as in the dictionary, since both were issued before the appearance of Professor Owen’s splendid Monograph of the Aye Aye, in 1866; but neither this nor any other excuse can be urged for the deficiencies and misstatements of certain late text-books of zoology.
We trust this is sufficient reason for offering now some further account of the Aye Aye.
One word as to the name. Its origin is as stated above, and not from any sound made by the creature itself; for, although one observer states that it sometimes utters a low grunt, another, the Superintendent of the Zoological Gardens in London, says he has never heard it make any sound whatever. Now it could not be expected that scientific naturalists would rest content with so brief a title as Aye Aye for so wonderful an animal. It must have two names at the least—the first to designate its genus, the second to signify the species, just as we say sugar (genus), white or brown, &c., (species); so in 1790 the Aye Aye was called Sciurus (squirrel) Madagascariensis (native of Madagascar). In 1800 it was rechristened as Lemur (ghost) psilodactylus (long-fingered). But it is now generally known by the title bestowed by Cuvier—Chiromys Madagascariensis—which signifies “a rat-like animal with hands, and living in Madagascar.”
The scientific title of the Aye Aye, then, fully atones for the brevity of its common name; and it must be further remembered that the technical names of animals and plants bear no definite relation to their own size or importance; for example, the elephant is simply Elephas Indicus or Africanus, according to the species, while the little changeable mole of the Cape of Good Hope is called Chrysochloris holosericea, and a microscopic rhizopod shell rejoices in the high-sounding title of Quinquenoculina meridionalis. Even this, however, would not be so bad if each species bore but a single name instead of a dozen, as often happens, and if, on the other hand, the same names were not sometimes by mistake applied to totally distinct species. It has been well said that the zeal of zoologists to give names to species and groups is the greatest bane of Natural History, a constant hindrance to our own progress, and a subject of well-deserved reproach from the public; if we would all make it a rule not to publish the name of a supposed new species for a year after its discovery, and until a thorough search had been made for previous records, our own glory might be less apparent, but we should be more considerate of our fellows, and more surely, though more slowly, advance the knowledge of natural objects.
The Aye Aye is about the size of a cat, but the head is rather larger, the ears are wider and less pointed, the limbs project more freely from the trunk, and the bushy tail forms rather more than half the total length of three feet. This tail, moreover, has a gentle downward curve, instead of an upward tendency, as with the cat and the dog. The trunk is clothed with a silky coat of short greyish hair; but the colour is given by the longer hairs, which are dark brown or nearly black, although along the spine some of them are tipped with white.
So far the Aye Aye has presented nothing very wonderful; but a glance at our illustration will detect its most striking feature. The Aye Aye’s hand is unlike that of any other known animal. Its medius or middle digit is about as long as the annularis or ring finger, but only half as thick. It is skinny and bony, as if stricken with palsy, and has been aptly compared to a crooked nail. Its knuckle-joint is projected beyond those of the other digits; its first phalanx is longer than that of any excepting the annularis, and its terminal phalanges very slender. But the tendon of the medius is quite as large as those of the other digits; and we are told that the tendons and muscles are so arranged that great power may be exerted upon this one slender digit, for a purpose we shall presently describe. The pollex, or thumb, is the shortest and thickest of all—has one less phalanx, as is usual among the mammalia, and is armed with a claw like the others. The acute angle which it forms with the palm does not indicate any great degree of opposability.
The hinder foot (pes) reminds us at once of that of a monkey; for the primus, or great toe, stands out boldly from the side of the foot, and is evidently opposed in grasping to the other four dactyls, as is our thumb. It bears a small nail, whereas the four smaller dactyls are armed with curved and pointed claws. Both digits and dactyls, moreover, are a little thickened at the tip, so as to form fleshy pads. That of the primus is most apparent.
The Aye Aye has strange teeth, too; for some of them suggest the squirrel, and others the monkey. In the first place, it has only two front or incisor teeth, above and below, and these are narrow, but deep, and bevelled off to a cutting edge, like the incisor teeth of the beaver, the squirrel, the rabbit, and other “rodentia” or gnawing animals, which have a hard case of enamel upon the front surface, the rest of the tooth being softer and more easily worn away by use. These teeth are like chisels in this respect; but they have two very decided advantages over the best steel instrument of human contrivance. The first is, that their very use keeps them sharp and in perfect order, since the edge of the lower tooth strikes just behind the edge of the upper, and both are continually worn away behind by the attrition of the hard wood which they attack. The second peculiarity is, that this constant loss of substance at the free end of the tooth is constantly repaired by new growth at the opposite extremity. The tooth grows during the life of the animal; and as the crown is worn away, the addition of fresh material to the root pushes the whole tooth slowly forward in its long socket, and it is thus ever ready for use. These ever-growing teeth are organic chisels which are for ever in use, yet never in need of the grindstone—for ever wearing away, yet never worn out.
But while the scalpriform incisors so nearly resemble those of the real rodent mammals, and while this resemblance is further increased by the absence of any canine or eye-teeth, and by the provision for a sliding forward and backward movement of the lower jaw, yet the molar or grinding teeth differ from those of the typical rodents; their crowns are rounded and slightly tuberculous, like those of the pigs, the monkeys, and man, and do not seem adapted to a strictly vegetable diet; add to this the peculiar character of the ears, which are large and naked, like the bat’s, and are inclined forward as if for offensive purposes, rather than backward, like the hare’s, in order to warn it of pursuit, and we must evidently be cautious in drawing conclusions as to the manner of life and the zoological affinities of this singular animal. The limbs show that it climbs trees like a monkey, the eyes that it is active at dusk like the owl and the cat, the teeth that it gnaws wood like the squirrel, while the internal organs of digestion would lead us to suppose that it feeds upon insects; and the extraordinary middle digit is so utterly unlike anything we have seen before, that conjecture as to its purpose seems to be in vain.
Deferring a discussion as to the Aye Aye’s place in a system of animals, and confining ourselves to what we have learned of its structure, let us see how nearly correct the reader has been in any surmises as to its mode of existence by consulting the statements of those who have observed the Aye Aye in life.
The first of these was the traveller Sonnerat, whose Voyage aux Indes Orientales et à la Chine, depuis 1774 jusqu’en 1781, was published at Paris in 1782. He appears to have been the first civilised discoverer of the Aye Aye, and states, either from his own observation or from the reports of the natives, that “it makes use of the long, slender and naked middle digit to draw out of holes in trees the worms which form its food.” Sonnerat had a male and a female Aye Aye which lived for two months on board ship, being fed with rice.
The next recorded observation upon the habits of the Aye Aye was communicated to the French Academy of Sciences in 1855, by M. Liénard, of the Mauritius. He states that when a mango-fruit was offered, the Aye Aye first made a hole in the rind with his strong front teeth, inserted therein his slender middle digit, and then, lowering his mouth to the hole, put into it the pulp which the finger had scooped out of the fruit. A third observer, M. A. Vinson, states that in the same year an Aye Aye drank café au lait or eau sucrée by passing its long and slender digit from the vessel to its mouth with incredible rapidity.
But in 1859 Dr. H. Sandwith, the Colonial Secretary from England to the Mauritius, wrote to Professor Owen that he had secured a fine, healthy adult male Aye Aye from Madagascar, which, after having once escaped and been recaptured, was put into spirit and sent to England. This specimen formed the subject of a most complete and suggestive work of the learned Professor. But a long communication from Dr. Sandwith himself is printed in the Society’s Proceedings for 1859, and some observations upon the habits of a female Aye Aye which reached the Society’s collection in August, 1862, are printed in the Society’s Proceedings for that year, and in the Annals of Natural History, vol. xii.
From these various sources we learn the following as to the Aye Aye’s mode of life:—
During the day the Aye Aye sleeps; it then lies upon one side, with the body curved and nearly covered by the great bushy tail. It is sensitive to cold, and sometimes covers itself with a piece of flannel, even in warm weather.
At dusk it awakes and climbs about, securely grasping the branches with its prehensile feet, and often hanging suspended by them, and using its fingers as a comb for its long tail. In this operation the middle digit is especially serviceable, and it is also used in clearing dust from its face and other parts, the other digits being then often partially closed. It was found that the captive Aye Aye in the Zoological Gardens used only the left hand in feeding from a dish, although the right seemed equally at its command.
The fourth digit (annularis), which is the longest and largest, is thrust forward into the food, the slender medius raised upward and backward above the rest, while the pollex is lowered so as to be seen below and behind the chin. In this position (an almost impossible one, by the way, for men or monkeys) the hand is drawn backward and forward rapidly, the inner side of the finger passing between the lips, the head of the animal being held sideways, thus depositing the food in the mouth at each movement; the tongue, jaws, and lips are kept in full motion all the time. Sometimes the animal will lap from the dish like a cat, but this is unusual. During all the hours in which the Superintendent of the Gardens watched it, no sound was made, nor was there any manifestation of anger or shyness.
This specimen seemed to care nothing for insects, but fed freely upon a mixture of milk, honey, eggs, and such sweet and glutinous things, and the observer concluded, therefore, that its natural food is rather fruit than insects; but this only indicated that the Aye Aye did not like British meal-worms, grasshoppers, wasp-larvæ, and the like, and no more proved that it was not insectivorous than a man’s refusal to eat turnips would show that he cared nothing for potatoes. And surely nothing can be more conclusive than the following account which Dr. Sandwith gives of the proceedings of his specimen:—
“I found he would eat bananas and dates; and he drank by dipping a finger into the water and drawing it through his mouth so rapidly that the water seemed to flow in a stream; after a while he lapped like a cat, but the former was the more usual method, and seemed to be his way of reaching water in the clefts of the trees.
“I happened to put into his cage some thick sticks, which were bored in all directions by a large and destructive grub called the ‘Moutouk.’ Just at sunset the Aye Aye crept from under his blanket, yawned, stretched, and betook himself to his tree, where his movements are lively and graceful, though by no means so quick as those of a squirrel. Presently he came to one of the worm-eaten branches, which he began to examine most attentively; and, bending forward his ears and applying his nose close to the bark, he rapidly tapped the surface with the curious middle digit, as a woodpecker taps a tree, though with much less noise, from time to time inserting the end of the slender finger into the wormholes, as a surgeon would a probe. At length he came to a part of the branch which evidently gave out an interesting sound, for he began to tear it with his strong teeth; he rapidly stripped off the bark, cut into the wood, and exposed the nest of a grub, which he daintily picked out of its bed with the slender, tapering finger, and conveyed to his mouth.”
This medius, then, can be used in turn as a pleximeter, a probe, and a scoop; and not the least remarkable circumstance is the coincidence between the diameter of the hole made in the wood by the incisor teeth and the width of this digit; for although we cannot say that the size and power of the head are such as to limit the width of the teeth, yet, granting that their size is so limited, it is evident that none of the ordinary digits would be of the least service as an instrument of either discovery or extraction; and whatever view we may adopt as to the means by which these structures were produced, we must surely, with the great anatomist, recognise not only “the direct adaptation of instruments to functions, of feet to grasp, of teeth to erode, of a digit to feel and to extract, but we discern a correlation of these several modifications with each other, and with modifications of the nervous system and sense-organs—of eyes to catch the least glimmer of light, and of ears to detect the feeblest grating of sound—the whole forming a compound mechanism to the perfect performance of a particular kind of work.” The Aye Aye obviously belongs to the branch of Vertebrates and the class of Mammalia; but some zoologists have placed it with the squirrels in the order Rodentia, and others with the Lemurs, in the order Quadrumana or Cheiropoda; there is also a certain superficial resemblance to a cat; but the real issue has been between those who follow Buffon and Cuvier in giving prominence to the ever-growing incisor teeth, which agree with those of the rodents, and those who, like Schreber and De Blainville, regard the limbs as of more importance, and point out their resemblance to those of monkeys.
It is now generally conceded that Professor Owen’s researches have decided the question in favour of the latter view, for he shows that the only rodent features are the teeth, and similar ever-growing incisors are found in at least one other mammal, the marsupial wombat, which no one has thought of calling a rodent: on the contrary, the hair, the tail, the form of the head and body, the length of the intestines, the heart and blood-vessels, the brain, and the limbs tend to separate the Aye Aye from the rodents, and to join it with the Cheiropoda; and although the extraordinary middle digit has no fellow in the whole animal kingdom, yet this modification of the terminal segment of a limb is another link between the Aye Aye and that lowest family of the Cheiropoda, the Lemuridæ, which, like it, are mostly natives of Madagascar, and, besides being nocturnal in their habits, whence the name Lemures (ghosts), are also distinguished from all other mammals and from each other by peculiar, and, at present, unaccountable modifications of the fingers and the toes. In one species the forefinger is as if amputated; in another a single toe bears a claw, while the others bear nails; and in a third, two toes are thus provided with claws.