BREATHING AND HISSING OF SNAKES.

FOLLOWING on the subject of the last chapter comes that of respiration; and in connection with breathing is the ‘voice,’ so far as this class of animals can be said to possess a voice.

As already seen in the description of the glottis, serpents do not breathe in the ordinary way, with short and regular inspirations, but when they do respire, they take in a supply of air to last them for some time. Their lungs, instead of occupying one particular portion of the body corresponding with the chest of the higher animals, are less developed. One lung—or what Professor Owen calls the long pulmonary bag—of snakes extends along more than half of their body; in some species nearly to the anus. Only one lung is normal, the other is rudimentary. The circulation is so arranged that on each contraction of the heart only a part of the blood is exposed to the influence of the air and becomes oxygenated, the rest returning to the parts without having undergone the action of respiration at all. The blood is, in consequence, poor in red corpuscles, its circulation is comparatively languid, the reptile becomes easily torpid, and its temperature is influenced by the surrounding atmosphere more than by the vigour of its own functions. This is why, when not excited to activity by external warmth, reptiles can pass a long time without food. Having no fixed temperature to maintain, one important source of demand for food is withdrawn.

The air enters their lungs chiefly in a direct course from the nostrils, only by the mouth when open. If you observe the flatness of the head, and the very short space that can exist between the nose and the mouth of snakes, you will readily trace the communication between the entrance to the trachea and the outer air through the nostrils when the glottis is not closed. Professor Owen, in his Anatomy of the Vertebrates, vol. i. p. 528, describes this process fully. In the foregoing description I have borrowed from him, as well as from Dr. Carpenter, Todd, and others; but as there is nothing like ‘seeing for oneself,’ I would persuade my readers to watch a snake for a few minutes. An inspiration at intervals will be easily discerned by the expansion of the body. You will also perceive partial or slighter breathings, and the trunk dilating and expanding gently through a sort of internal respiration which is going on; every now and then comes the deeper, fuller breath.

You may perceive that sometimes one short portion of the body expands, as if the lung in that part only were at work. This is more easily seen in the larger snakes. I have watched these for a quarter of an hour or more at a time, during which period only a comparatively short portion of the body showed any signs of breathing. Schlegel, who carefully studied this action, observed sometimes as many as thirty such partial dilatations of the trunk and lung between two full inspirations.

In the large reticulated python I once saw that about two feet of the body, viz. four to six feet from the head, dilated with occasional and irregular inspirations, and no other part. By and by slight indications of breathing were observable much lower down, many feet apart from the previous action, while during the whole time I was watching I saw not one full and entire inflation of the lungs. This was on a rather chilly September afternoon, and the python had partaken of a couple of ducks for dinner the previous day, and it was a time when inactivity is usual. In a rattlesnake, on the same day, similar partial and irregular respirations were observable, this serpent having caused four rats to disappear at his last night’s supper.

Sometimes you can discern no indication whatever of breathing for a very long time. When the reptiles are not in health, when they are about to cast their skin, or when in a half-torpid condition, you may observe this.

When a snake yawns—a long and leisurely proceeding—the lungs are doubtless greatly refreshed; otherwise these reptiles do not rest with their mouths open, and the only possible access of outer air by the lips being through the chink appropriated to the service of the tongue (and which is as exactly opposite the opening of the tongue-sheath as the nostrils are opposite to the glottis), they must breathe almost entirely through the nose, except when yawning.

From the elongated form of the pulmonary bag, and the large volume of air which it contains, we can understand not only how a temporary suspension of respiration can be supported, but we comprehend how it is that these reptiles can remain under water for long periods, as they often do,—not because they breathe in the water, but because they can for a while do without breathing.

Snakes have been seen to remain perfectly quiet at the bottom of a clear stream for half an hour or more. Sometimes in this totally quiescent state one has been supposed to be dead, until, on a stone being thrown, it has darted away like a fish. None of the aquatic birds or the cetaceous mammalia can remain so long under water without coming to the surface to breathe as serpents can.

At the Zoological Gardens they remain for hours at a time in their tanks. Often you will see a head peeping out—which, unfortunately, is all we can see—while the bath is being enjoyed, but as often the head is also immersed, though, of course, for a shorter interval, the snake lifting it to breathe occasionally.

We can imagine also the great assistance in swimming which this long air-receptacle must be, these reptiles deriving from it the same advantage, says Professor Owen, ‘as an eel from its swim-bladder.’ In chap. XII. is described the almost swimming motion of the more active snakes when gliding through long grass, or effecting progress over a very smooth surface. In the water the action is similar—that is, the progression is by lateral undulations, the tail being the chief propelling power. Whether through the resisting medium of water, or beating the air, so to speak, when skimming over smooth or unresisting surfaces, this swimming motion is ever easy and graceful. In the chapter on Tails, we shall see what an important agent in progression is this limb, whether by pressure, as in the burrowing snakes, or by its oar-like or paddle-like use in rapid motion.

To recapitulate the above in a few words—first, respiration warms the blood; snakes are cold-blooded because only a portion of the blood passes through the lungs to become oxygenated, and in proportion to the diminution of the quantity of blood transmitted to the lungs, so does respiration become weaker; therefore reptiles are less dependent on breathing.

Regarding the ‘voice’ of serpents, so surprising are the qualities attributed to it, that one would imagine the existence of varieties of snakes of widely differing organizations, if we were to believe all we read of the sounds they produce. ‘Hissing loudly,’ or ‘whistling,’ is the rule. No ordinary writer or traveller who says a word about a snake ever heard it hiss anything but ‘loudly,’ a statement traceable to the same sentiment which causes persons to talk of the ‘horrid forked tongue.’ A benevolently-disposed snake who would warn you away with that terrible tongue would also strengthen his argument by a prolonged hiss, and the louder the better.

But let us turn to the hard, cold, unpoetical, unimaginative language of science, and see what a snake can really do in the vocal expression of its feelings.

Says Dr. Carpenter: ‘In all air-breathing vertebrata the production of sound depends upon the passage of air through a certain portion of the respiratory tube, which is so constructed as to set the air in vibration. In reptiles and mammals it is at the point where the windpipe opens into the front of the pharynx, that this vibrating apparatus is situated. Few of the animals of the former class, however, can produce any other sound than a hiss, occasioned by the passage of air through the narrow chink by which the trachea communicates with the pharynx; but this sound, owing to the great capacity of their lungs, is often very much prolonged’ (Animal Physiology),—prolonged, but not powerful, be it observed.

Says Professor Owen: ‘The true “chordÆ vocales” are absent in serpents, and the voice is reduced to a hissing sound, produced by the action of the expired air upon the margins of the glottis’ (Anatomy of the Vertebrates).

Speaking of the escape of air from the lungs, Dumeril says: ‘Lorsqu’il est passÉ plus vivement il laisse entendre une sorte de vibration, qui le plus souvent, ne consiste que dans le bruit d’un soufflement.’[40]

Sometimes, according to the position of a snake, or when the passage is well open and uninterrupted, the hiss partakes somewhat of a whistling sound, like the blowing through a quill. I observed this particularly in a ‘tree boa’ (Epicratis cenchris), which hissed at me angrily one day because I took the liberty of touching it when the keeper opened its cage to arrange its blanket. The ‘hiss,’ not loud, or by any means musical, differed from the ordinary blowing only as a current of air passing through a round tube would differ from the same current passing through a narrow slit. A true ‘hiss,’ such as we produce with closed teeth in prolonging the sound of s, a serpent can never express. The nearest approach to it in the human voice is when the tongue is in the position as if we are about to say ye or he, and then prolong the breath; that is to say, breathe out while the tongue is so placed before the word is uttered.

Naturally the larger the snake the stronger the ‘hiss;’ the more rapid the expiration, the more powerful will be the volume of air with its attendant soufflement.

The sound and action, as well as degree, are easily seen in the ‘puff adder’ (Clotho, or Vipera arietans). When angry or alarmed, it draws in a full breath, and its body swells perceptibly; then you hear the escaping air like a prolonged sigh or blowing till the lungs are empty. This process is repeated as long as the provocation lasts.

These alternate inspirations and expirations, with their accompanying movements, the swelling and then diminishing of the trunk and the regular soufflants, are so precisely like those of a pair of bellows, that excepting in shape, we require no more complete comparison. The degree or strength of hiss is in this reptile very perceptible. When recently imported and easily excited, its violent ‘puffing’ corresponds with a very large pair of bellows; but in time it grows less alarmed at the appearance of the human beings who unceremoniously stare at it; and at length the puffing is very slight, ceasing altogether after the snake becomes accustomed to its surroundings. But if molested and alarmed, you then see the full play of the lungs, and the whole body alternately expanding and contracting as before.

We may almost compare this pulmonary action to the panting or full breathings of ourselves under alarm or agitation. Only, in comparison as the lung of snakes is elongated, and there is so much of it to fill with air, so is the sound prolonged, and the breathing a slower process.

There is another viper, the small Cape adder (Vipera atropos), a most deadly little reptile, in which a similar sound to that of the ‘puff adder’ may be heard. When this creature is disturbed, it draws in a long breath which expands its whole body in the same manner, and then in expelling the air, a long sort of wheeze or blowing is audible. Even in drawing the breath in, a slight sound is heard (as it also is in our native viper and some others); but instead of the prolonged hiss by which most snakes display their agitation, this little adder expresses itself in long successive blowings, like its larger relative arietans, only a little less regularly. In the present instance, I saw the lung inflated with an agitated undulating motion, as if the fluid air were entering in little waves. I do not state positively that this is invariably the case from having witnessed it in one specimen. This might be the normal process, or this viper’s lungs and health may have been impaired. I am thus precise because it is unsafe to establish as an invariable fact in natural history what may have been seen only occasionally, a habit which has so often led to the promulgation of erroneous impressions.

The prolonged sound of the hiss in snakes is due to the size of the lung, they having a large supply of air to draw upon. Some serpents expand their bodies under excitement without any perceptible hiss: the cobra both hisses and expands, so do some others; but all these movements are, no doubt, connected with respiration in some way, just as in human beings, sighing, sobbing, panting, etc., in which the ribs take part, are only modifications of the ordinary movements of respiration, and chiefly emotional.

Very similar also to the manner of the puff adder is that of Vipera rhinosceros, one of the largest African poisonous serpents, known as the ‘River Jack,’ being fond of water. One of these was in the London collection for several years, and I observed that whenever disturbed, its body swelled considerably, while the ‘hissing,’ or expulsion of breath, alternated with this expansion.

Snakes, like other animals, probably differ in temper or in nervousness; for while some are noted hissers, others hiss only on great provocation, and others, again, not at all. One remarkable example of a non-hissing snake, though from no amiability of temper, is the little carpet viper of India (Echis carinata). Unless you were positively assured by learned authorities that this exceedingly irritable little viper never hisses, you would scarcely believe your ears, so sibilant is the sound it causes by rustling its scales together.

Sir Joseph Fayrer, in the Thanatophidia, describes this as a very fierce and aggressive little viper, always ready to attack and be on the defensive. It throws itself into a double coil, and its agitated motion causes the rough, carinated scales to rub against each other, and make a sound like hissing, but ‘it does not hiss.’

This rustling is very much like the sound of the crotalus rattle, and the dry scales must be raised in a sort of way, or ruffled, as an alarmed hen ruffles her feathers. ‘The outer scales are prominent, and at a different angle to the rest,’ says Fayrer. It generally lies coiled in a compact form, often like a ‘w,’ as may be seen in the frontispiece, with its head in the centre, but always towards the point of supposed danger, which in a cage is facing the spectator.

Curious and wonderful is the agitation into which this carpet snake throws itself when disturbed, every inch of it, excepting the head, in motion. The head retains its fixed position, the eyes intently keeping guard, while the body moves in every conceivable curve, like wheels within wheels, yet retaining the same outline, or occupying the same place and space, though every muscle must be in activity.

One can liken this behaviour only to what is seen in the blending of liquids of different densities. As you look down into a glass containing one fluid while drop after drop of another is falling, you perceive fresh currents and curves in every direction. Watching one of these, it has changed places with another, you lose trace of it, each drop is lost in the commingling of the whole. So it is with this wonderful little echis. It is almost impossible to follow with the eye any one portion or coil of its moving length; but each inch changes places and mingles with the rest, like blending fluids.

Speaking of an American snake (Pituophis melanoleucus), in which a similar excitement is observable, Mr. Samuel Lockwood[41] likens it to a ‘mystic wheel.’ ‘The movement consists of numberless units of individual activities,’ he says, ‘and all regulated by and under the perfect control of one will that is felt in every curved line.’ There is some likeness to the ‘thousand personal activities of a regiment of soldiers on their winding way.’ He has watched the creature ‘melting into movements so intricate and delicate that the lithe and limbless thing looks like gossamer incarnate.’

This Pine snake is very smooth, and in the excited actions thus graphically described, it makes no noise like the little Indian viper; but Mr. Lockwood’s words are so appropriate to both snakes that the reader has only to add in imagination the rustling noise that accompanies the quivering echis.

Among other of the ophidians remarkable for their hissing is Psamophis sibilans, the ‘hissing sand snake,’ a very slender little creature. Several mentioned by the earlier naturalists as ‘the hissing snake,’ are evidently Heterodons. Catesby, Lawson, and others mention one as the ‘blowing viper;’ Blauser of the Dutch, also the ‘chequered’ or ‘spreading-adder,’ which leaves no difficulty in identifying Heterodon platyrhinos. An American writer indulges in a figure of speech while describing this little Coluber by saying, ‘It emits a succession of hisses, “sibilant sounds,” similar to letting off steam from a small steam engine.’ He at the same time admits that it is harmless and inoffensive in spite of its threatening aspect when flattening its head.’ This is the ‘spread head’ alluded to in chap. xxii., an unfortunate demonstration of alarm which has gained for it its venomous titles. Several of this species have from time to time been added to the collection at the Zoological Gardens, and the chief drawback to their anticipated attractions is that they so soon become tame and peaceful that you can scarcely provoke them to exhibit their reputed power. I have seen one flatten its head so slightly as to be barely noticeable, but I never heard it ‘hiss.’

‘Its spots become visibly brighter through rage,’ wrote Carver in 1796, ‘and at the same time it blows from its mouth with great force a subtle wind that is reported to be of a nauseous smell.’ Chateaubriand, of course, had something to say of ‘the hissing snake,’ frequent in the warmer States of America. ‘When approached it becomes flat, appears of different colours, and opens its mouth hissing. Great caution is necessary not to enter the atmosphere which surrounds it. It decomposes the air, which, imprudently inhaled, induces languor. The person wastes away, the lungs are affected, and in the course of four months he dies of consumption!’ Of another snake this author says, ‘He hisses like a mountain eagle, he bellows like a bull!’

It may be objected, ‘Why occupy space by quoting such old wives’ fables?’ I reply, because they have already been so abundantly quoted; and to such fables are in great part due the erroneous impressions which exist to the present day. Several members of the Heterodon family have from time to time been in our London collection. Friends of mine have had Heterodons in their keeping as pets; I have often handled them, and found them gentle and inoffensive in every way. They are indeed so popularly and peculiarly interesting that they will claim a page presently, the present chapter being devoted exclusively to ophidian lungs, not human lungs, supposed to be destroyed by them!

While admitting various degrees and qualities of hissing, we may give a passing mention to Du Chaillu’s snakes, all of which appear to be of the whistling, as well as of the ‘springing’ kind. He saw ‘an enormous black shining snake, loathsome and horrid.’ ... ‘Then the fellow gave a spring, and whistled in a most horrid manner.’ And when he was wounded, he again ‘gave a sharp whistle.’ On another occasion, while a Goree man was playing with a large Naja, ‘the air around seemed to be filled with the whistling sound of the creature,’ and so on.

Another African snake, the ‘Green Mamba,’ has such very bad manners that it not only hisses, but spits and darts at you. In this instance my informant was a young lady, who had ‘seen it!’

Somewhat more perplexing, because more deserving of notice, is what Livingstone tells us of a serpent called Nega-put-sane, or ‘serpent of a kid,’ which ‘utters a cry by night exactly like the bleating of that animal,’ and that he had ‘heard one at a spot where no kid could possibly have been.’[42]

‘Il canta como un gallo,’ said Albert Seba of an astonishing snake in Hayti and St. Domingo once.

‘Beyond a hissing and often a peculiar drumming noise, snakes emit no sound,’ says Krefft, one of our very able authorities.[43] This experienced writer does not positively affirm that the ‘drumming’ is produced by the voice, and it is more likely to proceed from the beating of an agitated tail, an action which may be frequently witnessed in excited snakes.

Dr. Otto Wucherer saw this in a South American snake, Xenodon colubrinus. ‘It has the habit of striking the ground rapidly with the tail when irritated’ (Zoo. Soc. Proc. 1861).

So do Spilotes variabilis, and some others. So also does the Pine snake, whose tail ends in a horny tip, ‘like a four-sided spike,’ and which vibrates like a crotalus in rudiment, or strikes the ground.

Several American naturalists have contributed interesting accounts of this last species, known as the ‘Bull’ or ‘Pine snake,’ or ‘Pilot snake,’ the largest of the N. American Colubers. It was this species (Pituophis melanoleucus) whose actions Mr. Sam. Lockwood described as mystic circles, and its activity as almost equal to that of the ‘Racer’ (American Naturalist, vol. ix. 1875). But it is called the Bull snake because it ‘roars like a bull.’ Bartram went so far as to say like thunder! ‘Said to hiss like thunder,’ or ‘resembling distant thunder,’ is the cautious testimony of Holbrooke, who adds, ‘but I never heard it, though well acquainted with it.’

Mr. Lockwood minutely described one in his possession. In reading his account we can but notice the similarity of action between this ‘Bull snake’ and the African vipers in ‘puffing,’ though regarding the nature of the sound, the writer positively affirms that ‘there is nothing sibilant in this blowing, not the slightest hiss about it.’ Mr. Lockwood records his experience of several that he had seen and heard, and of a fight between one and a rat. ‘Now began that fearful blowing. The snake slowly fills its lungs with air, and then expels it with a bellowing sound that is really formidable.’ And again, in the same volume, in reference to the former account, he says: ‘As there noted, the Pituophis, when alarmed or enraged, slowly inflates itself with air, thus nearly doubling its normal size along its entire length, except the tail. It then slowly expels the air with its own peculiar sound.’ He recalls his boyish terror on once hearing this sound, which came upon him suddenly in a field, ‘like the restrained roaring of a bull.’ This was in New Jersey; but the Pituophis family extends to the Western States, and to the Rocky Mountains, where ‘Bull snakes’ are frequently seen. In the reports of the United States Exploring Expeditions, mention has been made of the prairie Bull snake, and of others in Nebraska and as far west as California.

Some attain to seven feet in length; Holbrooke mentions one of nine feet, and ‘as thick as your arm,’ in common parlance. An angry snake of this size could, of course, blow with considerable force, and the term ‘bellowing’ might not unreasonably be applied to the sound; as it is also applied to the croaking of the ‘bull frog’ (Rana mugiens), the sound of which is really so like the lowing of cattle, that, on hearing one for the first time in the woods of Virginia, I looked round, quite expecting to see a young heifer in close proximity.[44] Probably, had the bovine lungs sounded at the same moment, the reptilian ‘bellow’ would have proved but a feeble imitation. A sound out of place, so to speak, or unanticipated, strikes upon the ear more forcibly than when expected. But if one reptile, and that a very small one, can so well imitate a bull as it is universally known the bull frog does, why may not another do the same?—an argument which I venture to use notwithstanding many herpetologists accept doubtfully the possibility of a snake producing such a sound. ‘Il est difficile À concevoir comment les serpents auraient la facultÉ de siffler, comme on pretend que peuvent le faire certaines espÈces de couleuvres, et comme les poËtes se plaisent À nous les representer. Jamais nous n’avons pu entendre qu’un soufflement trÈs sourd, provenant de l’air qui sortait avec plus ou moins de rapiditÉ de l’interieur de leur poumon que l’on voyait s’affaisser en trouvant une issue par la glotte, À travers les trous des narines ou directement par la bouche dont la mÂchoire superieure est naturellement echanchrÉe. Alors la bruit Était seulement comparable À celui qui resulterait du passage rapide et continue de l’air dans un tube ou par un tuyau sec et etroit, comme serait celui d’une plume.’[45]

This no doubt answers to the ordinary ‘hissing’ of the majority of snakes; but that the sound varies under certain conditions, and in the same serpent, cannot be denied. A. R. Wallace relates an incident which may well be introduced here, as affording both a proof of the length of time snakes can sustain a sort of half suffocation, and also the expression or power of ‘voice’ in breathing. A young boa was caught, and in order to prevent its escape, its captors, while preparing a box in which to convey it away, tied it tightly round the neck to a thick stick, which not only fettered its movements, but appeared to nearly stop its respiration. It lay writhing in much discomfort, sometimes opening its mouth with a suspicious yawn, as if trying hard to breathe. By and by, when relieved from its clog and safely consigned to a box with bars on the top, it began to make up for loss of time by breathing violently, ‘the expirations sounding like high-pressure steam escaping from a locomotive. This continued for some hours, of four and a half respirations a minute,’ when the breathing—in this case we may say panting—gradually subsided, and then the poor thing settled down into silence.[46]

The expression of feelings by the tail in so many snakes, producing a sibilant sound in rustling dead leaves, and in some which are supposed never to hiss, is a subject well worth the attention of scientific naturalists. It would be interesting to ascertain if any peculiarity of trachea or of glottis exist in these.