VIPERINE FANGS.

THOUGH the ensuing chapter will be devoted more exclusively to the CrotalidÆ or rattlesnakes, it were well to repeat here that the two families ViperidÆ and CrotalidÆ comprise the sub-order of Ophidia ‘VIPERINA,’—those that have the isolated, moveable fangs, the term isolated having reference to the functional fang only. It may appear incongruous to present the illustration of a viperine jaw with a whole cluster of fangs, while affirming that there is the one pair only; but the pair in use are ‘solitary,’ because the jaw bears no simple teeth, as in those with fixed or permanently erect fangs.

The first observation of the mobility of the viperine fang and its peculiar structure is ascribed to Felix Fontana,[99] an eminent naturalist and Professor of Philosophy at Pisa, in the eighteenth century. He formed the cabinet of Natural History at Florence, and died 1805, in his 75th year. But the mobility or action of rattlesnake fangs was known long prior to Fontana, and he probably borrowed the expression ‘dog-teeth’ from the old Virginia writers who thus called the fangs. Purchas (1614), quoted in chap. xvi., describes ‘venomous Serpentes, one ten Spannes long, with great Tuskes, which they hide and stretch out at pleasure.’[100] And again, in describing ‘foure kinds of venomous Snakes. The first is greatest, Jararacucu, that is great Jararaca, and they are ten Spannes long: they have great Tuskes hidden in the Mouth along their Gummes, and when they bite they stretch them like a Finger of the Hand; they have their Poyson in their Gummes, their Teeth crooked, and a Stroake vpon them whereby the Poison runneth. Others say they have it within the Tooth which is hollow within. It hath so vehement a Poison that in foure-and-twentie Houres and lesse it killeth a Man.’[101]

There can be no doubt but that viperine fangs are here described, those belonging to the South American CrotalidÆ, under their vernacular but then their only names. Dr. Ed. Tyson, who dissected the first rattlesnake that was handed over to science (p. 275), quite understood the mobility of the fangs, and of the existence of supplementary teeth, though not fully comprehending the nature of these latter; which ‘I could not perceive were fastened to any Bone, but to Muscles or Tendons there. These Fangs were not to be perceived upon first opening the Mouth, they lying couched under a strong Membrane or Sheath, but so as did make a large Riseing there on the Outside of the lesser Teeth of the Maxilla’ (meaning the reserve fangs), ‘but at Pleasure when alive they could raise them to do Execution with, not unlike as a Lyon or a Cat does its Claws.’[102]

He found seven reserve fangs on each side; and though they were not, as he tells us, ‘fastened to any bone,’ the illustration represents them growing in regular order according to size in the jaw.

In another paper read before the Royal Society in 1726, also anterior to Fontana, on the ‘Fangs of the Rattlesnake,’ the writer, Captain Hall, describes the dissection, which was under the direction of Sir Hans Sloane; and ‘then the Muscles that raise the poisonous Fangs appear.’ This anatomist also found reserve fangs. ‘Putting by this Membrane, the fatal Fangs appear, which on first View seemed only one on each Side, till searching further there appeared four more. The first and largest is fixed in a Bone;’ four others were loose in the membrane.[103]

Several of the old authors quoted in the chapter on Rattlesnake History of the Seventeenth Century were quite aware of the action of the ‘Springing Teeth,’ ‘Master Teeth,’ or ‘Canine Teeth,’ as the fangs were variously called; and Lawson, 1707, describes ‘the Teeth which poison are two on each side of the Upper Jaws. These are bent like a Sickle, and hang loose as if by a Joint.’ Fontana’s observations were possibly of greater scientific importance, otherwise it is singular that his equally thoughtful predecessors, from whom he no doubt culled much important information, should have been overlooked.

In these viperine fangs there is an analogy between the vipers and the lophius, a fish with moveable teeth; only in the fish, as Owen tells us, the action is not volitional,—the teeth bend back to admit food, and then by elastic muscles spring up again to retain it.

The true nature of the reserve fangs was surmised by Mr. John Bartram, who in 1734 wrote from German Town, in the American colonies, to a F.R.S., ‘On a Cluster of Small Teeth at the Root of each Fang or Great Tooth.’[104] He had a rattlesnake, ‘now a Rarity near our Settlements,’ and dissected it, when he ‘found in the Head what has not been observed before by any that I can remember; i.e. a Cluster of Teeth on each side of the Upper Jaw at the Root of the Great Fangs through which the Poison is ejected. In the same Case that the two main Teeth were sheathed in, lay four others at the Root of each Tooth in a Cluster of the same Shape and Figure as the great ones, and I am apt to think for the same Use and Purposes, if by an Accident the main Teeth happen to be broken. May not these be placed to supply a Defect successively, for the Support of this Creature?’

Mr. Bartram was singularly correct in his diffidently-offered surmises; nor is it likely that in such a remote district as German Town then was, he had ready access to foreign publications, or would have claimed originality had he been cognisant of the work of M. Moyse Charas, New Experiments upon Vipers, translated from the original French in 1673. Charas, after describing the ‘Great Teeth,’ refers to the ‘smaller teeth’ (reserve fangs) ‘that are there in a Nursery, and are, if we may say so, in expectation to serve instead of the many Teeth, whether these come to fail of their force, or fall out of themselves.’ The author, to add weight to conclusions evidently originating from personal investigations, tells us that he had ‘taken Pains to grovel with a good deal of Patience in the Gums of innumerable Vipers.’

The Italian Redi, even prior to Charas, had also ‘grovelled’ in the gums of Vipers, and observed the canal or slit in the fang, ‘si fendono per lo lungo dalla radice alla punta,’ and that these canaliculated teeth in the moveable jaws (ossi mobili) were for the conveyance of the venom.[105]

Thus, one hundred years prior to the work of Fontana, the structure of the viperine jaw was understood and described by several—we may almost say many—anatomists, to whom let due honour be rendered for their individual and independent researches; from all of which Fontana had doubtless benefited.

And so from numerous sources we might go on culling and quoting; Philosophical Transactions of France, Florence, Germany, and America, as well as of England, showing us that little by little the scientific workers examine, compare, correspond, till out of their life’s labours a fact is established that may be printed and learned in six lines, but which—as is well worth remembering—often represents the brain and eyes and time of ages of scientists.

Next to engage attention was the structure of the fang and the ‘involution’ described in the last chapter. A paper on this subject by Thos. Smith, Esq., F.R.S., was read before the Royal Society in 1818. Mr. Smith claims to have been the first to observe this involution as being altogether different from the perforation of the pulp originally supposed to be the case. He first noticed the slit in a cobra’s fang (he being in India), and afterwards in a Hydrus (sea snake), and it led him to further investigations. With a microscope the slit was perceptible in a rattlesnake fang (which was also observed by the present writer before reading this account).

One more paper in the Philosophical Transactions on this subject must be commended to the interested student. It is the one already quoted (p. 363), ‘On the Succession of Poison Fangs,’ by Charles Tombes, M.A., vol. clxvi. p. 470, 1876. In this paper is presented the result of all the most recent investigations, enriched by still deeper researches, but of too scientific a character to be introduced in this simple narrative of the progress of ophiology. We may, however, say that Mr. Tombes finds the character or function of succession differs in the vipers from that of the venomous colubrines; and this, as the construction of their fangs and maxillary jaw differs, is what we might look for.

A few more words descriptive of the external aspect of the ViperidÆ may summarize what has already been said of them. Schlegel suggests that their ‘noxious character is expressed in all their parts.’ With the exception of brilliant colouring, this may be accepted as a rule. The broad, flat, angular head, rendering the ‘neck’ thin and conspicuous, has gained for many of them the generic, sometimes specific name of Trigonocephalus. From their deadly qualities, Clotho, Severa Atrox, Lachesis, and Atropos are among their names; while caudalis and brachyura describe the short, thin tail as opposed to the long and tapering tails of most colubrines. The true vipers—those that have not the nasal fosse—belong particularly to Africa, the CrotalidÆ proper to America, the chief distinction being that the CrotalidÆ have and the ViperidÆ have not the ‘pit’ (see p. 277), of which more in the next chapter. The rigid, lanceolate scales covering the head are another viperine characteristic; also thick, heavy bodies, tapering at each end, and rough, carinated scales. They inhabit for the most part dry, arid deserts and sandy uncultivated places of the Old World, Africa being their most congenial habitat. The coloured viper and young one convey a good idea of their general aspect.

Ophiologists do not agree in the arrangement of genera and species, on account of the forms running so much into each other. Gray gives nine genera and twenty species; Wallace, three genera and twenty-two species; and Dumeril, six genera and seventeen species. The Death adder of Australia (p. 172) is a heterogeneous species. Its aspect is viperine, yet it has not viperine fangs, and does not therefore belong to this chapter. Schlegel thinks it ought not to be separated from the true vipers, but Krefft does not state positively that it is viviparous, so it is altogether anomalous.

The researches of Dr. Weir Mitchel of Philadelphia have been of great value to ophiologists. For two whole years he gave the best portion of his time to the study of rattlesnakes, having a number of them under constant observation. An exhaustive paper by him was published in the Smithsonian Contributions, Washington, D.C., in 1860, giving details of experiments with the venom and the treatments adopted. But of especial interest here are his observations on the fangs and their volitional action, it having previously been supposed that the mere opening of the mouth brought the fangs into position, which is not the case. As the Crotalus can move each side of its mouth independently, so it can use one or both fangs. ‘When the mouth is opened widely, it still has perfect control over the fang, raising or depressing it at will.’ Dr. Mitchel saw that though both fangs were present, both were not always used. When a viperine snake yawns extensively, as it so often does, you may sometimes perceive the fangs partially erected or entirely so, or the ‘vibratile motion’ in them observed by Fayrer. When the snake is angry, this vibratile action is much like that of a cat gnashing the teeth; but when only in a yawn, the partial and unequal erection of one or both fangs has the appearance of being involuntary. In this I speak from observation. The effect is similar to that seen about a person’s mouth in trying to suppress a yawn—a sort of convulsive, nervous twitching. Whatever the cause, you perceive the fangs moving, but not moving always in accord.

The shedding or replacement of the fangs is, Dr. Mitchel thinks, a regular process, as in the teeth of some fishes, though not regular as to time. Sometimes, but not always, they are shed with the casting of the cuticle. He ‘cannot suppose that the almost mature secondaries are awaiting an accident;’ which agrees precisely with the opinions of Dr. Edward Nicholson and other physiologists quoted in the last chapter: ‘A crop of young teeth’ (or of fangs) ‘work their way into the intervals of the old teeth, and gradually expel these latter.’ When lost by accident or by violence, therefore, the process of replacement is slower, as we can readily conceive, the ‘secondary’ next in turn not being as yet ready for duty.

Though the American scientific journals devoted to zoology are rich in ophidian literature, there are few available to English students; and I regret I am unable to ascertain from across the Atlantic the latest researches and conclusions regarding this and several other correlative points. To Professor Martin Duncan I am indebted for the loan of a volume which forms one of the ‘Bulletins’ of the United States Geological Surveys, containing a valuable ‘Report’ on the Crotalus by Dr. Elliot Coues, of the United States army, late surgeon and naturalist to the United States Northern Boundary Commission, 1878.

It is these frequent Exploring Expeditions of America that have done so much to enrich science in all its branches; as to them are appointed efficient geologists, botanists, naturalists, and other scientists, who send in their ‘Reports’ to Government, to be soon reproduced in the form of large, handsomely-illustrated volumes. Copies of these (often consisting of ten to eighteen thick quartos) are presented to the members of Congress, governors of States, and to many others in office, also to literary institutions. You may have access to them in almost every large town in America; and there is no information connected with the history and natural productions of the nation (including the aborigines) that cannot be found in their pages. And as our Transatlantic cousins are always exploring some new territory, and have still untold square miles of mountain and valley to explore, their scientific ‘Reports’ in huge quarto tomes can be more easily imagined than counted.

This little digression from the viperine fangs is by way of introducing Dr. Elliot Coues. The volume in question was not forthcoming at the British Museum, therefore I ventured to trouble Professor Duncan with some inquiries, which were kindly responded to by the sight of the work itself.

There is in Dr. Coues’ paper a good deal of what has been here already described; but there is also so much that is of additional interest, that for the benefit of those students who are not within reach of the British Museum (where, no doubt, the fast arriving quartos will get catalogued in due time), I will transcribe from the text some of the passages as relating to viperine fangs generally.

‘The active instruments are a pair of fangs.’ ... They are ‘somewhat conical and scythe shaped, with an extremely fine point; the convexity looks forward, the front downward and backward’ (referring to the slight double curve in the Crotalus fang as shown in the illustration, p. 360). They are hollow by folding, ‘till they meet, converting an exterior surface first into a groove, finally into a tube.’ ... The fang is ‘moveable, and was formerly supposed to be hinged in its socket. But it is firmly socketed, and the maxillary itself moves, which rocks to and fro by a singular contrivance. The maxillary is a small, stout, triangular bone, moveably articulated above with a smaller bone, the lachrymal, which is itself hinged upon the frontal.... This forward impulse of the palatal and pterygoid is communicated to the maxillary, against which they abut, causing the latter to rotate upon the lachrymal. In this rocking forward of the maxillary, the socket of the fang, and with it the tooth itself, rotates in such a manner that the apex of the tooth describes the arc of a circle, and finally points downward instead of backward. This protrusion of the fang is not an automatic motion, consequent upon the mere opening of the mouth, as formerly supposed, but a volitional act, as the reverse motion, viz. the folding back of the fang, also is; so that in simply feeding the fangs are not erected.’ (But I think I may affirm positively that sometimes the vipers do use their fangs in feeding. When they open their mouths—or rather the jaws alternately very wide—I have seen first one and then the other fang occasionally engaged in the food and again disengaged unsheathed. On other occasions the fangs have been folded. In some large African vipers, the ‘River Jack’ and others that were in the Society’s Gardens a few years ago, I was able to observe this easily.)

The fang is folded back ‘with an action comparable to the shutting of the blade of a pocket-knife; ... one set of muscles prepares the fangs for action, the other set stows them away when not wanted.... The fangs are further protected by a contrivance for sheathing them, like a sword in its scabbard. A fold of mucous membrane envelops the tooth like a hood.... The erection causes the sheath to slip, like the finger of a glove, and gather in folds round its base.... It can be examined without dissection.’ (And with the naked eye in a large viper, even during life, you may sometimes perceive this sheath or hood half off.) ‘Each developing fang is enclosed in a separate capsule,’ says Dr. Mitchel, which is just what I thought I saw in ‘grovelling’ up the poor Bushmaster’s reserve fangs. There was an immense deal of loose skin to remove, which under skilful manipulation would doubtless have presented the form of sheaths of various sizes. At last I came to a great deep cavity as big as a bean or a hazel nut, and this I left neat and uninjured for some one else to explore. It might have been the poison gland! The young Jararaca’s mouth is too small to reveal its mysteries.

But now we come to the most amazing of all the wondrous detail of this living hypodermic syringe. Those who have seen a viper or a rattlesnake strike its prey, are cognisant of the lightning-like rapidity of the action. So swift is it that often a spectator is not sure whether the snake touched the victim or not. A flicker, a flash, and the bite has been given. Dr. Mitchel, describing the singular inactivity of rattlesnakes in confinement, points out the striking contrast between this repose and the perilous rapidity of their stroke. Now let us look at the amount of business transacted in that flash of time. Says Dr. Elliot Coues: ‘The train of action is first reaching the object; secondly, the blow; thirdly, the penetration; fourthly, the injection; and fifthly, the enlargement of the wound (the latter by dragging upon it the whole weight of the body by the contraction of certain muscles, which cause the fangs to be buried deeper and thus enlarge the puncture); and all these five actions accomplished in that instantaneous stroke!’ This is what Fayrer means when explaining that ‘the real bite is when the snake seizes, retains its hold, and thoroughly imbeds its fangs.’ ‘Sometimes the lower teeth and the palatine become entangled (and sometimes a fang is left in the wound).... The force of ejection may be seen when a serpent striking violently misses its aim, and the stream has been seen to spirt five or six feet. A blow given in anger is always accompanied by the spirt of venom, even if the fangs fail to engage.’ ... Another curious piece of mechanism, and one not previously described that I am aware of, is a provision for the fangs when they fail to bite. ‘A serpent always snaps his jaws together, and thoroughly closes them when he strikes; therefore, if the fangs failed to engage, they would penetrate the lower jaw. But there is a certain movement among the loose bones of the skull (perhaps not yet thoroughly made out), the result of which is to spread the points of the fangs apart, so that they clear the inner sides of the under jaw, instead of injuring them.’ Coues here describes rattlesnakes particularly, but no doubt the same extends throughout the viperines.... ‘In a large snake the entire gland may be an inch long and one-fourth as wide, having the capacity of ten or fifteen drops of fluid. There is no special reservoir for the venom other than the central cavity of the gland. Formerly there was thought to be such a storehouse; but when the tooth is folded back, certain muscles press or compress the canal to prevent a wasteful flow: in other words, the communication is shut off!’

In this wonderful exhibition of the ivory hypodermic syringe there has not, I trust, been so much repetition as to render the subject tedious. Presented in such graphic language and from such a source, it must attract almost every intelligent reader, while the viperine fang is absolutely acting before his eyes. On this subject, then, no more need be said; though on the Crotalus family generally some interesting matter still remains to be told.