Snakes: Curiosities and Wonders of Serpent Life

by Catherine Cooper Hopley

One of them, the larger, on being touched with ink, revealed this open groove or incomplete involution so distinctly that I tried the other and was convinced at once. The loose one may be a first and only half-developed fang. They are almost as transparent as glass. I requested the keeper to look into the mouths of those subsequently dead, but he found no other loose fangs. Of the remaining forty-five deceased, let us hope those into whose hands they have fallen will be able to throw some further light on the development of fangs in very young vipers. Fayrer tells us that a young cobra is not venomous until it has cast its first skin, which is usually within a fortnight. White of Selborne found no trace of fangs in young vipers which he examined with a lens; but these had not yet been born. The possible cause of functional development in this little viper’s fangs may be found in chap. xxiv. of this work.

Another erroneous impression regarding fangs has been produced by confusing those that are ‘fixed’ and those that are ‘moveable.’ All truly are fixed firmly into the jaw; but in the viperine snakes the very short bone itself is moveable by a volitionary action, so that it partially ‘rotates,’ and with it the fang. The Elapidæ have fixed or ‘permanently erect’ fangs, and when the mouth is closed these fit into a depression in the lower jaw. Viperine fangs only can be erected or depressed at pleasure. It is those which spring into place for use like a pen-knife half opened, and which when at rest are folded back, like the knife shut up again. This action has been most lucidly described by Coues in connection with the Crotalidæ, under which head I will quote from his paper. Schlegel himself is not very clear in his distinctions between those serpents that have ‘moveable’ fangs and those which have not, but Cuvier had already described them as crochets mobiles. Indeed, it is since the date of Schlegel’s work that more complete investigations have revealed closer anatomical distinctions. We therefore find in some of our highest-class encyclopedias, if not of recent date, mis-statements regarding fangs which unfortunately have been quoted in many works. ‘Venomous serpents depress their fangs,’ says Schlegel’s translator, true to the text, but as if it were common to all. Describing deglutition, Schlegel says ‘the same in all’ ‘sans en excepter les venimeux, qui lors de cet acte redressent leur crochets et les cachent dans la gaine des gencives, pour ne point les exposer à des injures.’[96] This, however, is the case with the Viperina only. It is common, for the reasons just now assigned, to find the cobra classed among the vipers, in some popular encyclopedias; and in one, a valuable and generally trustworthy American edition of 1875, we read, ‘moveable fangs like the cobra, viper, and rattlesnake.’ A cobra has not moveable fangs. Another, an excellent English edition, but of not very recent date, includes all venomous snakes under the head of ‘vipers;’ a third in general terms states that ‘venomous snakes have no teeth in the upper jaws, excepting the fangs, and that the opening of the mouth brings these into position;’ whereas it is now known that a viper can open its mouth and yet keep its fangs depressed and sheathed. In several other encyclopedias the description of fangs is suited to vipers only.

It is not necessary to designate names, as these things will be set right in the new editions. They are mentioned more with a view to show that ophiology has advanced with rapid strides of late, rather than presumptuously to criticise our standard works. Perhaps in another twenty years my own poor efforts will be exposed as ‘old-time misconceptions.’

The renewal of poison fangs is another subject of interest to ophiologists: how the next supplementary fang becomes fixed, anchylosed to the jaw-bone; and how and when the connection with the poison duct is completed. Mr. Tombes, in a paper read before the Royal Society in 1875, describes a ‘scaffolding’ of bone thrown out to meet and grasp the new fang, to ‘interdigitate and fix it in its place; this soft bone rapidly developing and hardening.’ Sufficiently marvellous is the functional fang in itself; the insertion of the venom, a mode of subcutaneous injection invented long before the doctors thought of it. ‘A most perfect hypodermic syringe,’ Huxley calls it. Suddenly the hypodermic syringe is removed, say by accident, by force, or by gradual decay, and all connection with the gland is cut off; yet within a given period a second, a third, an unlimited number in turn replace it: the connection is restored and the hypodermic syringe is ready for action again. How the new one is brought into relation with the poison duct has afforded much speculation, and in the American scientific journals, as well as those of Europe, papers on this subject appear from time to time. Dr. Weir Mitchell of Philadelphia affirms that when the fang is lost by natural process it is replaced in a few days: when by violence, several weeks elapse before the next is firmly fixed.[97] He speaks of the rattlesnake chiefly. Fayrer gives the periods in several cobra experiments. In one cobra whose fangs were carefully drawn out on Oct. 7th, new fangs were ‘anchylosed’ to the bone in twenty-four days. In another, thirty-one days elapsed before the new ones were ready for use; and in two others, eighteen days. In all of these cases the new fangs were capable of inflicting deadly injury by the time stated.

But the perfection of mechanism culminates in the viper fangs; and reasoning from analogy, the intensity of poison in their glands also. When at rest, these lie supine along the jaw, but can be ‘erected,’ i.e. sprung down, for use by a special muscle. The two fangs above the dotted illustration of viperine dentition (p. 355) show both positions. Nicholson affirms that the Indian viper Daboia can inject as much poison in half a second as a cobra can in three seconds; ‘that whereas a cobra’s virus flows in small droplets, the viper’s runs in a fine stream.’ Though a much smaller snake than the cobra, Daboia’s fangs are nearly double the size, as may be observed by comparing the figs. C and D (p. 349). There seems reason to believe also that this viper (which in its features Fayrer considers a true Indian type) can inflict injury with more than the pair of functional fangs. ‘In reference to the connection of the poison fangs with the maxillary bones,’ says this learned experimentalist, ‘I would note that second or even third supplementary fangs may be anchylosed with the principal one to the maxillary bone. I have before me the skull of a Daboia, for which I am indebted to Mr. Sceva, in which this is the case; and where there are five well-developed poison fangs on each side, of which on one side two are anchylosed to the bone.’[98] (Described by Mr. Tombes, Phil. Trans. vol. clxvi. p. 146.)

This may explain what we so often read in the description of venomous snakes found with two, three, or more fangs on each side. In my Lachesis two were distinctly visible before I began to dig for those hidden in the loose membrane, of which there seemed an abundance, and I am nearly certain that the second one had its own particular sheath. The spirit in which the specimen had so long been immersed, as well as my awkward probings, forbid me to speak with certainty regarding this second sheath.

After one of his rattlesnake bites—twenty days after—Dr. Stradling informed me by letter: ‘My little durissus is shedding its skin; but when that is over, I shall certainly examine its mouth. Now that my arm is on the verge of ulceration, I find what I had not noticed before, that each puncture is double—two large ones and a tiny second one, about ¹/₁₂ inch behind each, standing out in black relief against the scarlet skin.’

Neither of these experimentalists stated positively that the reserve fangs were in connection with the duct, a phenomenon which I believe is still unexplained. Fayrer removed the functional fangs from an Echis carinata, and observed that there were no others fixed at the time, though there were others loose in the mucous membrane. On the fifth day another pair were anchylosed and ready for use! As will be presently seen, this little viper of sixteen or eighteen inches (almost too small to recognise near the great python in the frontispiece), displays corresponding vigour both in the potency of its venom and in the renewal of its weapons.

From the foregoing illustrations of numerous pointed teeth, the question might arise, ‘How are they disposed of when the mouth is closed? and from the narrow space which is apparent in the flat head of a snake, and the close fit of the jaws, how do the four or six rows meet without interfering with each other?’ This difficulty is obviated by the teeth not closing one upon the other as ours do. Nor are the palate teeth in the centre, or they would wound the upper part of the trachea and the tongue sheath, which occupy considerable space. They close down on each side of these organs. ‘Every relief on one surface fits into a corresponding depression on the other surface, and accurate apposition of every part is obtained,’ Nicholson explains to us. ‘The four upper rows of teeth divide the roof into three parts, and the lower jaw teeth fit between the upper maxillary and palatine teeth.’