OPHIDIAN ACROBATS: CONSTRUCTION AND CONSTRICTION.

BEFORE discussing the most remarkable of all ophidian caudal appendages, the Crotalus rattle, and the many speculations regarding it, we will enumerate some other acrobatic achievements of which snakes are capable; as, in accounting for these, some interesting facts appertaining to their anatomical structure can be described.

A humorous journalist has said, ‘There is apparently nothing that a snake can not do, except swallow a porcupine.’[63] Presuming that he alludes to physical feats, he is not far from wrong. For all that, the Western pioneers of America tell us of yet one more thing that these reptiles cannot accomplish, and that is, cross over a rope of horse-hair. Having by accident discovered that they turn aside from this, some Western settlers, when camping out, have effectually entrenched themselves within a circle of horse-hair rope as a barrier to rattlesnakes while sleeping.

Let us try to account for this.

Many of my readers have seen the cast-off coat of a snake. Those who have not can have the pleasure of examining one or several the next time they go to the Zoological Gardens, where the obliging keeper will cheerfully exhibit them. Others at a distance may not enjoy this facility, and for these the accompanying diagrams may be a slight compensation.

The whole cuticle or epidermis of a serpent is composed of these overlapping scales, of which the above illustrations are only fragments. Thus when we speak of their scales, we do not mean distinct and separable laminÆ, like the scales of some fishes, each of which may be scraped or plucked off, and which overlie each other like the feathers of birds. The covering of a snake is one entire piece, loose-fitting, and so arranged as to lie in those scale-like folds which accommodate themselves to every movement of the body. The ventral or under scales are, in fact, a regular kilting, as may be seen by the section; and the upper ones correspond somewhat with what our lady friends call the shell or the leaf pattern in knitting work. The outer or exposed folds are stronger, thicker, and more hardened than the inner parts, just as the knitter ‘throws up’ her pattern with a coarser wool or larger needles, and knits the less conspicuous parts in a softer material. The naked space of thinner skin between these scales being very considerable, one can therefore easily understand how, when a snake would attempt to pass over a horse-hair rope, the sharp, prickly hairs, standing out chevaux-de-frise fashion, would insinuate themselves unpleasantly in those softer and more vulnerable interstices which become exposed by the sinuations of the body. Probably, if we knew it, or had an opportunity of observing, we should ascertain that snakes do not crawl over furze bushes, or thistles, or the prickly pear (opuntia), or any similar vegetation of tropical climates, and for the same reason. The close-scaled burrowing snakes, with their hard and strong cuirass all round them, might have nothing to fear from a furze bush; but this is mere speculation. That fine, sharp spines or prickles, and therefore a horse-hair rope, would incommode the tender intermediate epidermal folds of other snakes, we can well suppose. Had they sense enough to leap the obstacle, this they could easily do, after the manner of ‘leaping’ already described; but the ‘leap’ is only an instinctive action used in pursuit or escape; and it may be equally instinctive to turn aside from uncomfortable obstacles, whether prickly pears or horse-hair ropes.

Mr. Ruskin, in his highly-entertaining lecture on ‘Snakes,’ at the London Institution, March 1880 (a lecture which, by the way, was artistic, poetic, figurative, imaginative—‘Snakes’ from a Ruskin, but not a zoological, point of view), remarked ‘that no scientific book tells us why the reptile is a “serpent,” i.e. serpentine in its motions, and why it cannot go straight.’ Now, may not the fact that snakes have acquired these ever-varying sinuations arise from their sensitiveness to the slightest, and what would be to other creatures almost impalpable, obstructions in their path?—mere inequalities which in their lazy nature it is easier, they know not why, to circumvent than to surmount; because they can go straight, and do go straight when the way is plain.

Rymer Jones, in his Organization of the Animal Kingdom, thinks that their sense of touch from the nature of their integument must be extremely imperfect; they being ‘deprived of any limbs which can be regarded as tactile organs,’ p. 753. But close observation leads one to agree rather with a much older writer, Roget, who, in his Animal Physiology, intimates that the peculiar conformation of serpents must be exceedingly favourable to the acquisition of correct perceptions of touch, and that these perceptions which lead to a perfect acquaintance with the tangible properties of surrounding bodies must contribute much to the sagacity of snakes;—that their whole body is a hand, conferring some of the advantages of that instrument.

That this latter faculty is strictly and marvellously the case, we shall presently see, owing to the flexibility of the spine, and its capability of grasping and twining round objects of almost any shape, and of taking, as Roget says, ‘their exact measure.’ For this grasping power is not confined to the constricting snakes only. In all snakes a great flexibility is abundantly provided for in the construction of ‘these lithe and elegant beings,’ as Rymer Jones in unprejudiced language calls them (p. 724 of the book above quoted); ‘the spinal column admits the utmost pliancy of motion in any required direction.’

Though snakes have no limbs externally, ‘the work of hands, feet, and fins is performed by a modification of the vertebral column.’[64] ‘Except flying, there is no limit to their locomotion,’ said Professor Huxley in his lecture on ‘Snakes,’ a few weeks previously to that of Ruskin, and under the same roof. To both these lectures we shall again refer, as the reader will feel sure that all coming from such sources must add value to the present writer’s arguments.

As ‘flying,’ the swift motions of many snakes have been described by ancient writers, as, for example, the ‘flying serpents’ of Scripture, though these are by many supposed to be the Dracunculi, the earliest known of human parasites. The astonishing movements of serpents were, however, in superstitious ages ascribed to supernatural agency. Says Pliny: ‘The Jaculus darts from trees, flies through the air as if it were hurled from an engine.’ The ‘wisest of men’ admitted that the actions of serpents were beyond his comprehension; ‘the way of a serpent on a rock’ was ‘too wonderful’ for him.

Even in intermediate ages, when travellers and naturalists began to confront fiction with fact, even in the days of Buffon and LacepÈde, a serpent was regarded as a living allegory rather than a zoological reality by many intelligent, albeit unscientific persons. Of such was Chateaubriand, whose contemplation of the serpent partook of religious awe. ‘Everything is mysterious, secret, astonishing in this incomprehensible reptile. His movements differ from those of all other animals. It is impossible to say where his locomotive principle lies, for he has neither fins, nor feet, nor wings; and yet he flits like a shadow, he vanishes as if by magic, he reappears, and is gone again like a light azure vapour on the gleams of a sabre in the dark. Now he curls himself into a circle, and projects a tongue of fire; now standing erect upon the extremity of his tail he moves as if by enchantment. He rolls himself into a ball, rises and falls like a spiral line, gives to his rings the undulations of a wave, twines round the branches of trees, glides under the grass of the meadow, or skims along the surface of the water,’ and so forth.[65]

Excepting the ‘tongue of fire,’ the whole of this poetic description is so far true and unexaggerated, that Chateaubriand has not attributed to the reptile one action of which it is not capable, and which, to the untutored mind, might well seem supernatural. Roget, Schlegel, Huxley, and others tell us the same things in the language of science. To quote them all is impossible; the reader will be content with one scientific assurance of ophidian capabilities, not less poetic than Chateaubriand’s.

Professor Owen, in describing the bony structure of the Ophidia, and in allusion to the scriptural text—‘Upon thy belly shalt thou go’—affirms that so far from the reptiles being degraded from a higher type, their whole organization demonstrates how exquisitely their parts are adapted to their necessities, and thus proceeds: ‘They can outclimb the monkey, outswim the fish, outleap the jerboa, and suddenly loosing the coils of their crouching spiral, they can spring into the air and seize the bird upon its wing.’

The active snakes can always ‘leap’ their own length, whether upwards to seize a bird, or horizontally, and, as in the case of the Jamaica boa (described p. 186), can leap much farther from a similar impetus when the direction is downwards. Indeed, they can let themselves fall from a certain elevation with an additional impetus to progress, as a boy first runs in order to leap a ditch.

‘With neither hands nor talons, they can out-wrestle the athlete, and crush their prey in the embrace of their ponderous, overlapping folds.... Instead of licking up its food as it glides along, the serpent uplifts its crushed prey, and presents it grasped in its death-like coil, as in a hand, to its gaping mouth.’[66]

A similarly graphic account is given by Rymer Jones, p. 718 of his work,[67] that will be read with interest by those who wish to pursue the study scientifically.

In watching the larger constricting snakes while feeding, you see how dexterously they manage.—(One may use this word here, because those above quoted, ‘as in a hand,’ are literally, scientifically true; therefore we may suppose fingers as well as a hand, and say how dexterously the creatures bring their coils to their aid.)

They have quickly strangled and begun to eat, say an opossum or a turkey buzzard, when a part of the prey not swallowed offers some impediment to the expanded jaws; the wings or legs may be inconveniently extended, or have become wedged between some immoveable obstacles—a log, a narrow space, or under a portion of themselves. Their mouth, the only apparent grasping agent, is already occupied, and a strain sufficiently powerful, while the jaws are thus retaining the prey, would be painful to the feeder, might even drag back the food, to the injury of the engaged teeth. How does the reptile proceed in this emergency? With the lightness and deftness of enormous strength, it applies two folds of its body, two loops of its own coils, and with them drags forth, lifts up, or otherwise adjusts its prey in a more convenient position—in fact, ‘presents it as in a hand’ to its own mouth.

A very remarkable instance of a constricting snake thus using its coils is related by Dr. Elliott Coues, of the United States army, late surgeon and naturalist to the United States Northern Boundary Commission. He witnessed one of those frequent combats between the Racer and the Rattlesnake, in which the former—and in far less time than it takes to read one line of this page—threw two folds or coils round his adversary, one coil of the anterior portion of his own body round one part, and a second coil of the posterior portion of his own body round another part, and then, by a sudden extension of himself, tore the rattlesnake in halves. And this was done with greater ease and swiftness than we could snap a thread which we must first secure round the fingers of our two hands. As if indeed possessed of two hands, the constrictor snapped his foe in twain. This is Lawson’s ‘Whipster,’ p. 182.

The coiling of the constricting snakes is like lightning; you cannot follow the movements. In this case death must have been instantaneous, and indeed it is doubtful whether any beast or bird of prey puts his victim to a more speedy and less torturing death than the constrictors when following their own instincts.

Repairing to the Zoological Gardens in the hope of witnessing the wonderful adaptation of coils to manual uses, after reading what Roget and Owen had affirmed, one soon had a favourable opportunity in watching a python. It was, I think, in June 1874, and the poor python had a ruptured side. In spite of which—as my zoological notes record—‘it helped by the folds of its body to get the wings of the duck down flat and close, so as to swallow it more easily. With reason does Roget say, “Its whole body is a hand,” for it used its loops to hold and to push and to flatten in a manner truly intelligent.’

Such was my first entry and observation. Subsequently, and indeed almost on every feeding day, the same kind of thing was to be seen at the Gardens. Many such examples are recorded in my notebook; but of these one or two later notes will suffice to illustrate the subject.

A young python was hanging from a branch, more than half its body curved as in the accompanying sketch, remaining motionless and quiescent, watching some sparrows which the keeper had just put into the cage. The birds, eyeing certain insects among the gravel, seemed all unconscious of the pair of glistening eyes looking down upon them. Suddenly a movement, a flicker, like the flash of a whip, and the snake had changed its position. Too quick for us to follow the motion, but in that flash of time it now hung like a pendulum, with a sparrow almost hidden in its coils. The snake had precisely measured its distance, reached down, and recoiled with the swiftness of an elastic spring. After a few minutes, feeling that its prey was dead, it prepared to swallow it, holding it encircled in a portion of its body, while the head was free to commence the usual examination. Still hanging there, it held and devoured the bird.

On another occasion, one of the larger pythons caught a guinea-pig in the same manner. This also was so quick in its movements that one scarcely knew what had happened until the snake was seen to have changed its position, some of the anterior coils had embraced a something, and a quadruped was missing. This snake also still hung while eating its meal, the whole process occupying less than ten minutes. In both these cases we saw the prehensile tail in its natural use, while the rest of the body was free for action.

One of the most remarkable cases of what we may call independent constricting powers, that is, two or more parts of the reptile being engaged at the same time, was in some very hungry, or very greedy, or very sagacious little constrictors, the ‘four-rayed snakes,’ Elaphis quater-radiatus.

They are slender for their length, which may be from three to five feet, of an inconspicuous colour, but with two black lines on each side, running the whole length of their body; hence their name, ‘four-lined,’ or ‘four-rayed.’ In the present instance, there were in the same cage three of these, also one young royal python, one small common boa, and one ‘thick-necked tree boa’ (Epicratis cenchris), all constrictors. The day was close and warm for April, and the snakes, reviving from their winter torpor, seemed particularly active and lively. Probably they had not fed much of late, and thought now was their opportunity, for the keeper no sooner threw the birds—finches, and plenty of them for all—into the cage, than there was a general scuffle. Each of the six snakes seized its bird and entwined it, then on the part of the reptiles all was comparatively still. The rest of the poor little birds, fluttering hither and thither, were, however, not disregarded, for although each snake was constricting its captive, several of them captured another bird by pressing it beneath them, and holding it down with a disengaged part of themselves. One of the four-rayed snakes felt its held-down victim struggling, and instantaneously a second coil was thrown round it. Then another caught a second bird in its mouth, for its head and neck were not occupied with the bird already held, and in order to have coils at its disposal, slipped down its first captive, or rather passed itself onwards to constrict the second, the earlier coils not changing in form in the slightest degree, any more than a ring passed down a cord would change its form. The next moment I saw one of those two hungry ones with three birds under its control. It had already begun to eat the first, a second was coiled about eight inches behind, and a good deal of the posterior portion of the reptile was still disengaged when a bird passed across its tail, and instantly that was captured. All this was done by a sense of feeling only, as the snakes did not once turn their heads. Two of these ‘four-rayed’ snakes were so close together, so rapid in their movements, so excited and eager for their prey, that which of them first began his bird, and which one caught the third, it is impossible to affirm confidently.

Whenever either of them was in the same position for one quiet minute, a few hurried strokes of the pencil fixed them in my notebook, and of the hasty though faithful sketches thus made, I present three to the reader on the opposite page.

April 1st, 1881.—After this date nothing more was to be seen! Henceforth visitors were to be excluded, and the reptiles were to be fed after sunset.

Now, however painfully and sympathetically we may regard those poor little birds so unceremoniously seized, crushed, and devoured, we can but reverently, and almost with awe, admire the astonishing facility with which these limbless, toolless reptiles provide themselves with food. With still deeper awe and reverence we shall admire when we examine their anatomical structure, and see by what marvellous development it has been adapted to their necessities.

We feel sadly for the finches, it is true; because finches are often our pets, and are sweet songsters. Were a toad or a rat thus treated, we should care less, perhaps; because there is as much repugnance towards toads and ‘vermin,’ as towards snakes.