THE TONGUE OF A SNAKE.

PART III.—ITS USES.

ONE more function in which the tongue has no part it is important first to mention. ‘It is supposed to be concerned in the function of voice, that is, hissing,’ says Mr. Frank Buckland in his Curiosities of Natural History, 1860. Now, as this is an extremely popular book, and as Mr. Buckland was a very popular writer, and much quoted and believed in from his pleasant and genial style, and his many opportunities, it is necessary to explain that the tongue is often or generally in its sheath while the snake hisses, and therefore has no part whatever in the ‘function of voice.’

More recently still, a writer in 1876 is under the same impression. It is well known that the contributors to that excellent magazine, the Leisure Hour, are for the most part persons of good literary standing. However, in the matter of snakes we are all only learners.

There are in the magazine referred to, three chapters ‘On Snakes,’ occupying, with the illustrations, about eight pages, in which the general subject is treated.

‘It is a very general belief that the sting of a poisonous snake is in its tongue,’ says this writer, ‘and to any one who has seen an adder ready for attack, with its body coiled, its head and neck reared aloft, and its long, narrow tongue, split for a considerable distance from the point inwards, and thus resembling a two-pronged fork, vibrating rapidly, accompanied by a hissing sound, the needle-like points of the tongue have a decidedly stinging aspect. It need hardly be said that the tongue is only responsible for the hissing.’ The hissing is from the lungs (see chap. ix.), and, as may be repeated, often while the tongue is within its sheath, the opening of which is forward in the mouth.

The tongue of a snake occupies much the same place in the lower jaw as that of other animals; only being, while passive, within its sheath, which opens at the tip, the tongue can move but in one direction, namely, forwards.

The illustration in the Leisure Hour which accompanies the above writer’s explanation, displays a rattlesnake with widely-extended jaws, and a tongue which, by comparison, must be from root to tip half a foot in length, and represented as coming from far back in the throat, as if no sheath existed.

The tongue of a snake not being so planted, and not by any possibility intercepting the breath, it is needless to repeat that it can never be any agent of the voice, i.e. ‘hissing,’ nor is it every snake that does hiss (see chap. ix.). Illustrations conveying an entirely erroneous impression are very much to be regretted, and unfortunately this misplacing of the snake’s tongue is an extremely common error, and we recognise the familiar woodcut again and again in a number of different publications, misconceptions thus being seriously multiplied. Bad illustrations, even more than printed errors, are responsible, because more persons turn the leaves of a book to look at these, than those who read the page, and a glance either instructs or misinforms the eye.

The hissing of a snake, as we may here add, is merely an escape or expulsion of air from the lungs, more or less quick or ‘loud,’ as the reptile is more or less alarmed or angry. Conjecturally, one may suppose this hissing to correspond with the agitated breathing or panting of other animals, or of an excited person.

In the seventeenth century, when travellers were visiting for the first time the newly-settled colonies in America and Africa, and when the early explorers in various parts of the world were sending home stuffed specimens of animals (in the days when taxidermy, like other sciences, was in its infancy), a stuffed snake was furnished with a huge, broad, fleshy tongue, big enough to crowd its entire mouth, minus teeth and gums.[33] Whether this broad tongue was to favour the delusion of ‘licking,’ or whether the licking was presupposed from the look of the tongue, we cannot say, but that the stuffed specimens did encourage the delusion is clear.

Our Philosophical Society, founded about the middle of that century, and the ‘Philosophical Transactions’ of those days record the first arrival of tropical serpents in England, and the marvellous beliefs concerning them. From them we learn, nevertheless, that many things said to be ‘new to science’ in our own time, were not unknown two centuries ago.

Passing by a large number of writers on snakes, who, being convinced that the tongue neither ‘stings’ nor ‘licks’ nor ‘aids in hissing,’ and who, therefore, cursorily dismiss it with, ‘the use of the tongue is not known,’ let us thoroughly examine for ourselves this mysterious organ; and this we can do with the assistance of those who have devoted careful attention to the subject.

Quoting first our English authorities, Dr. J. E. Gray tells us: ‘Tongue very long, retractile into a sheath at its base. Apex forked, very long, slender, and tapering.’

Says Dr. GÜnther: ‘Tongue long, vermiform, forked; an organ of touch; frequently and rapidly exserted to examine an object. The slightest provocation brings the tongue into play.’

Rymer Jones, in his Organization of the Animal Kingdom, tells us that ‘in snakes the bulk of the tongue is reduced to the utmost extent. The whole organ seems converted into a slender, bifid instrument of touch, and is covered with a delicate membrane.’ Again, in Todd’s Cyclopedia of Anatomy, the same writer says that ‘the tongue of a snake seems to perform functions, the nature of which is not so obvious’ (as that of some other reptiles).

Der Hoeven (Clark’s translation) tells us ‘the tongue of a snake is an organ of feeling or tact, and much used, as the antennÆ of insects.’

It will be observed that while no two of the above writers use precisely the same words, each helps us to picture the tongue more accurately, and we glean from each some new particular. The Encyclopedia Britannica, after telling us ‘the use of the tongue is not exactly known,’ adds, ‘they (the snakes) are continually lancing it into the air, and may possibly in this way gather moisture from grass or herbage’ (alluding to the question of ‘drinking,’ see chap. iv.).

Professor Owen still further defines it as a pair of muscles, or a double muscle partly connected and partly free. The reader will prefer the learned Professor’s own words, notwithstanding the slight repetition.

In his Anatomy of the Vertebrates, p. 463, after describing the prehensile character of the tongue in some reptiles, notably the toad and the chameleon, he says: ‘In serpents the tongue takes no other share in the prehension of food than by the degree in which it may assist in the art of drinking. It is very long, slender, cylindrical, protractile, consisting of a pair of muscular cylinders in close connection along the two basal thirds, but liberated from each other, and tapering each to a point at the anterior third; these are in constant vibration when the tongue is protruded, and are in great part withdrawn with the undivided body of the tongue into a sheath when the organ is retracted.’ The pair of parallel muscles can be distinguished in the largest of the accompanying illustrations, viz. the tongue of a Jamaica boa of about 8 feet long. It was cut out and given me immediately after the death of the reptile, and while soft and flexible was carefully copied. The hair-like points diminish to an almost invisible fineness impossible to represent with pen or pencil. The slender little tongue is that of the young Jararaca; and the shortest is that of the African viperling. I have drawn only as much as is usually exserted when in use. The entire tongues are much longer, of a pale flesh tint, and somewhat thicker towards the root. It is observable that the organs, like their possessors, are either shorter and stouter, or longer and more slender.

The reader will concur with Mr. P. H. Gosse and the Penny Cyclopedia, that ‘no instrument is less adapted for licking.’

There is yet one more of our English scientific writers who must be quoted, and who, though he wrote so far back as 1834, shows us that even then this tongue was far better understood by the French and German zoologists than ourselves. Roget, in his Animal Physiology (one of the Bridgewater Treatises), says: ‘Hellmann has shown us that the slender, bifurcated tongue of snakes is used for the purposes of touch.’

It is to be regretted that we have no translation of this and of several other German ophiologists of whom mention is made by Roget and others. Lenz gives us to understand that in 1817 Hellmann had decided that a snake uses its tongue as an insect does its antennÆ. And in watching with unprejudiced eyes the varying play of the organ, the similarity of action will at once be recognised.

After all, how little can we ever know of these organs beyond conjecture! Who shall say whether each or both may not possess a sense of which we ourselves have no true perception? Close observers are convinced that the tongue of a snake is endowed with peculiar sensibilities; and it is the more astonishing, therefore, that reason and observation have so long been blinded and enslaved by prejudice regarding it.

Some naturalists think that the sense of smell lies in antennÆ. The sense of smell itself is dull in snakes; yet they have means of ascertaining what other animals learn by smell. Says Huxley, ‘The great majority of the sensations we call taste are in reality complex sensations, into which smell and even touch largely enter.’[34] It is certain that the snake’s tongue is in constant use for some purpose or other, though beyond what we see of its form and actions we can only speculate, or, at best, draw conclusions from observation.

Both Dumeril and Lenz give the result of their own observations. The former, however, devotes so many pages to the tongue and its functions under the various headings of ‘touch,’ ‘nutrition,’ ‘the senses,’ etc., that it will be necessary to curtail a good deal, particularly as this great author has been quoted by those other physiologists whose words were given above. Of the sheath into which the tongue is received he says:—‘Une gaÎne cylindrique, charnue; mais l’extrÉmitÉ de cette langue est fourchue, ou divisÉe en deux pointes mobiles, vibrantes, susceptible de se mouvoir indÉpendamment l’une de l’autre, de s’Écarter et d’Être lancÉes, pour ainsi dire: ce que la fait regarder par le vulgaire comme une sorte de darte, auquel mÊme quelques peintres ont donnÉ dans leurs tableaux la forme d’un fer de flÊche. Le vrai est que cette langue est molle, humide, trÈs faible, et que l’on a fait des conjectures, plutÔt sur les usages auquels on l’a cru destinÉe, que sur l’utilitÉ rÉelle dont elle peut Être aux serpents dans l’acte de la deglutition; car les serpents ne mÂchent jamais leurs alimens.’[35] ‘Quoiqu’on ignore le vÉritable usage de la langue humide et charnue que les serpents brandissent et font continuellement sortir de la bouche et vibrer dans l’air, il est facile de concevoir qu’À cause de la forme cylindrique et de son etroitesse elle ne pourrait faciliter la mastication, quand mÊme les dents seraient propres de cet usage.’[36]

This first volume of ErpÉtologie gÉnÉrale treats of all reptiles inclusively; but in the sixth volume, where the ophidia particularly are introduced, the tongue is, with the rest of the organs, more minutely described. Some repetition necessarily occurs; but there is still a good deal that will repay perusal.

After stating that in serpents the sense of touch is dull, on account of the integument, and the absence of what may be regarded as tactile organs, and that the sense of smell is dull, the nostrils being feebly developed, Dumeril adds: ‘The tongue, though fleshy, very mobile, and constantly moist, is rather an especial instrument for touch, for the action of lapping, and for other functions, than to perceive the nature of liquids;’ in other words, than as an organ of taste. ‘It is, however, very remarkable; though smooth and even above, it is furnished with little fringes or papillÆ along the sides. Notwithstanding its length and narrowness, it is singularly protractile and retractile; and in its exceedingly rapid vibrations has impressed the vulgar with the idea that it is formed with the two spear-like points. It is clothed with a delicate skin.’[37]

Lenz made many interesting experiments. In his work he gives us the result of these, and also what some other German ophiologists had seen and done. He observed how entirely the snake trusted to its tongue in any unusual circumstances; the all-important member was then in ceaseless activity. Confined in a glass jar containing wine or any liquid that the snake did not like, the tongue was ever agitated. Crawling up the side, the tongue was in constant request to feel the glass (as may be often seen at the Zoological Gardens); and on arriving at the top, the head was turned this way and that, and then bent over the edge, as if to make certain that no further obstacle existed; the tongue not for one instant quiet, but exserted sometimes as far forward as the whole length of the head, telling to its owner all that the other senses could not discover.

Permitting it to touch his hand, he felt it like the sweep of a thread, so light and delicate. Too fine and flexible to injure any surface, the slightest touch of one or both the tips suffices for intelligence. Nay, sometimes without even touching—that is, without positive contact, but by some subtle sense, it seems to act as guide.

When the snake is excited by fear or alarm, or when in a strange place, the activity of the tongue is so great, the vibrations are so rapid, that the eye cannot follow them. It is like the play of electricity.

So far from participating in deglutition, the snake withdraws the slender instrument into its sheath, which, while feeding, is safely closed. For this highly-endowed organ is so guarded against injury, that the reptile has not only a place of safety provided, but power to close the mouth of its scabbard, lest dust or other irritating particles should enter.

We have only to reflect upon and to observe the habits of snakes to perceive the importance of their tongue to them. For the most part nocturnal, winding their way under tangled masses of vegetation, often in dark caves, holes, crevices, and obscure retreats, with their eyes so placed that they can see neither before nor under them, and with other senses only feebly developed, the tongue with its sensitive papillÆ feels its way, and conveys impressions to its owner.

Cats have their whiskers to help them in the dark; moles and mice have their quick sense of smell to guide them; all nocturnal animals are gifted in some manner or another, but snakes have only their tongue.

We can now imagine the helpless condition of the reptile if deprived of the tongue! Rudolph Effeldt, of whom Lenz speaks as the ‘most eminent observer of living snakes,’ found that when deprived of the tongue, they would neither eat nor drink, and, of course, died after a while. But Lenz had some snakes sent him which had been deprived of their tongues, and he observed that though for a time dull and declining, they did recover, and by and by ate as usual. From which we can only conclude that snakes, like other animals, differ in their powers of endurance. Some survive mutilation and suffering, some do not.

Another error in illustrations is to represent the tongue far extended while the mouth is wide open. Snakes very rarely open their mouths and use their tongues at the same time. Indeed, excepting to gape, the snake does not generally open its mouth; nor invariably keep it open while advancing on its prey, as illustrations often represent.

Nature has further provided for the safety of the tongue by leaving a small opening in the upper lip, or at the point of the muzzle, just where no teeth are in the way, so that the snake can use its tongue without exposing the sheath and mouth to injury. This ‘chink in the rostral shield,’ to use technical language, permits the free exit of the tongue and the independent actions of the two muscles of which it is formed, enabling the reptile to hold the two fine tips close together as one tip, while passing the tongue through the narrow chink, and to expand them afterwards.

Lenz never observed any dust or small particles adhering to the tongue; but Mr. Arthur Nicols, the author of Zoological Notes, informs me that he has noticed little fragments of rubbish cling to the tongue and carried into the mouth. Dr. Cantor also says: ‘Sea snakes make no use of the tongue while in the water, but considerable use of it as a feeler when out of the water.’ He has noticed ‘several Indian land snakes use it to bring into the mouth various small bodies, as stones, sand, twigs, which they swallow to stimulate digestion.’

This is curious and noteworthy. The power or volition which can control the sheath and close the valve can, no doubt, exclude these foreign particles; as, while lapping, the mouth must be moistened as well as the interior of the sheath, both it and the tongue requiring frequent lubrication.

But we have now reached the confines of speculation. There is enough of real fact about this ‘horrid forked tongue’ to interest and astonish us. We find it guarded, aided, especially provided for, and especially constructed and endowed; especially harmless also. To the owner its importance ranks not second even to the eyes.

The importance of the antennÆ to insects is evident to all who have ever watched the play of those active and beautifully-elaborate organs, their infinitely varying forms (often many times the length of the insect itself), their ceaseless play and independent action. Constantly waving, they lightly touch every contiguous object; investigating on all sides, they convey to insect intelligence all it requires to know regarding its environments. Like a herald or a scout, they literally ‘spy out the land,’ and thus become a guide and a guard to the tiny feeble creature which possesses them. Through them the owner learns all that is needful for its well-being.

Much as an insect uses these exquisitely-constructed antennÆ, so does a snake its long, slender, pliant, bifurcate, and highly-sensitive tongue. Ever busy, ever vigilant, exploring while barely touching each surface within reach, yet by night and by day conveying with that slight contact all necessary information to its owner. Sent out with the speed of a flash, it telegraphs back with like quickness the result of its discoveries.

If we may assign intelligence to any single organ, we might affirm that there is more of what we consider rational intelligence in the tongue of a snake than in any other of its perceptive faculties. Probably the most important knowledge demanded by the reptile is conveyed, or, at least, confirmed by this organ.

‘ColorÉe,’ says Dumeril of the tongue, as botanists say of the part of a plant ordinarily green, as, for instance, a calyx; ‘coloured,’ but not what colour. This is precisely as we may describe the colour of a snake’s tongue. My attention was first drawn to this on reading one of Dr. Arthur Stradling’s communications to Land and Water, April 2, 1881. ‘It would be interesting to know why some snakes have red tongues and others black,’ he writes. ‘Here beside me, in a glass case, are two little snakes, both belonging to the same genus (Tropidonotus)—a seven-banded (T. leberis), and a moccasin (T. fasciatus), both hailing from the United States, and both alike in their habits and choice of food; yet it is a case of rouge et noir with their lingual appendages.’

After reading this, I noticed the varieties of colour in all the ‘forked tongues’ that exhibited themselves at the Zoological Gardens. Black or very dark tongues, I think, predominate; and next to black, brownish or olive tints, resembling those of the snake itself. But not as a rule; for some very light snakes have dark tongues, and the converse. In two small green tree snakes of distinct genera, one had a pale pink or flesh-coloured tongue, and the other a black one. Some tongues are almost white, while a few are red. There seems to be as much caprice as in the colour of the human hair and eyes; and as physiologists have traced some sort of connection or relationship with complexions and constitutions in these, so ophiologists may, after a time, discover a similar relation or sympathy between the colour of a snake’s tongue and its integument or eyes. At present, I have observed only so far as that two entirely black and two entirely green snakes may present four distinct colours as regards their four tongues, and that many tints of brown, black, and pink may be seen in the tongues of as many snakes.