Snakes: Curiosities and Wonders of Serpent Life

by Catherine Cooper Hopley

These four classes, be it observed, are only designated ‘roughly speaking.’ Nicholson describes a close gradation in the development of the poison glands also to correspond with those almost imperceptible stages. The poison gland is after all only a modified salivary gland. It lies behind the eye, whence the venom is conveyed by a duct to the base of the fang, down along it, and sometimes through it, and is emitted at what we may for the present call the point, into the wound made by it, something on the principle of an insect’s sting. As when inserting the sting the pressure forces the poison out of a gland at its base, so does the pressure of certain muscles act upon the poison gland when a snake opens its mouth to strike. In some of the most venomous, viz. the viperine families, the largely developed glands give that peculiar breadth to the head. There is a hideous, repulsive look about some of these, that seems to announce their deadly character, even to those who see one for the first time. The evil expression of the eye, with its linear pupil; the peculiar curve of the mouth, with its very wide gape downwards, and then up again, are unmistakeably treacherous, venomous, vicious.

Like all other animal secretions, the poison is produced, expended, and renewed, but not always with equal rapidity; climate, season, and temperature, as well as the vigour of the reptile, influencing this secretion. The hotter the weather, the more active the serpent and all its functions. When the poison gland is full and the snake angry, you may see the venom exuding from the point of the fang, and by a forcible expiration the reptile can eject it. I have seen this in the little Echis carinata and its congener the Cerastes. I am not certain whether the Cerastes hisses or not, but under terror or excitement it moves itself about in ‘mystic coils’ as Echis does, producing a similar rustling noise with its scales; but both of them, if angry, will strike at you with a sound which may be compared with a sneeze or a spit, at the same time gnashing their mobile fangs and letting you see that they have plenty of venom at your service. They may almost be said to ‘spit’ at you, though literally it is the mouth ‘watering with poison,’ combined with the natural impulse to strike, which produces this effect. We can, however, by this judge of the force with which the venom is expelled, which in a large viper must be considerable.

Travellers have told us that a serpent ‘spouts poison into your eye.’ If an angry one strike, but miss its aim, the poison is then seen to fly from its mouth, sometimes to a distance of several feet. Whether a snake is so good a marksman as to take certain aim with this terrible projectile, or whether he possess sufficient intelligence to attempt it, we may doubt. Dr. Andrew Smith tells us that this belief prevails among the natives of South Africa.

A bright object always attracts snakes, and some victimized traveller’s eyes may have been remarkably brilliant, and in consequence smarted under the accident. Be that as it may, the poison is sometimes so abundant that you may see it flow from the mouth over the prey. The glands being excited, just as are the salivary glands of mammals, the mouth ‘waters’ with poison. In the Hamadryad I have seen it flow, or more correctly ‘dribble,’ down over the snake it was eating. This noxious secretion assists digestion in the same way that the ordinary saliva in the human mouth does. Says Dr. Carpenter, ‘The saliva prepares food for the business of the stomach; and if the ordinary operations of mastication and insalivation be neglected, the stomach has to do the whole work of preparation as well as its own especial duty of the digestion.’ That the digestive powers of snakes are strong, we know from the fact that nearly all animal substances are converted to nutriment in the stomach of a healthy snake. The abundant saliva must be a powerful agent in the process, because mastication takes no share in the work. This has become more than mere conjecture, since recent experiments have shown that snake venom possesses strong peptic qualities; that, like pancreatic juice, it will even dissolve raw meat and albuminous substances. Recent experiments have also shown that the salivary gland is the laboratory in which the poison of venomous serpents is elaborated; that ordinary saliva is there intensified, concentrated, and endowed with its toxic properties.

During the two hundred years that have witnessed the development of natural history into a science, many and various have been the methods of zoological and particularly of ophiological classification. A few of these methods are sketched out in chap. ii. It will be seen that the character of the teeth had not for a long while much weight in classifying snakes. According to Schlegel, Klein in 1755 was the first to separate the venomous from the non-venomous snakes in classification. But after him Linnæus, then the greatest naturalist of modern times, distinguished snakes chiefly by the form of the ventral and sub-caudal plates; so that in the six genera which he established (Amphisbæna, Cecilia, Crotalus, Boa, Coluber, and Anguis), rattlesnakes and boas, colubers and vipers, with others of the most opposite characters, were jumbled up together; and the little burrowing blindworm and the venomous sea snakes were supposed to be related, because they neither of them had ventral scales! On account of his vast researches and great reputation, subsequent naturalists were slow to entirely overthrow his system and to venture on reforms of their own, and our cyclopedias are suffering to the present day from the confusion of the various methods of classification adopted by so many naturalists, as a few quotations presently will show. Dandin, 1802, though his work was reckoned by Schlegel the most complete up to his time, comprehended all the venomous snakes under the head of ‘vipers.’ Cuvier divided the vipers (with crochets mobiles) from those with fixed fangs; but yet was unsound in many other respects, confounding the Elapidæ with the Viperidæ, although he professed to separate them. Another confusion arose out of the word cobra, Portuguese for snake, so that wherever the Portuguese settled most snakes were Cobras. In India the English have retained the name Cobra for the snakes with the hood, which name is now confined to the one group, Capella.

‘The characters of dentition offer in a great many cases a decisive method for distinguishing the species,’ says Günther; ‘but as regards the combination of species into genera and families, it is of no greater importance than any other external character by itself.... Still I am always glad to use the dentition as one of the characters of genera and species whenever possible—namely, whenever it corresponds with the mode of life, the general habits, and the physiology.’[93]

Since the publication of Dr. Günther’s work, The Reptiles of British India, 1864, the distinctions of the various types of dentition seem to have been more clearly comprehended; and as this work is the accepted authority among English ophiologists, and will best commend itself to the reader, it shall be our guide in the present attempt to simplify much complication.

The five groups of snakes described in chap. ii. are divided into three sub-orders of Ophidia as follows:—1. Ophidia colubriformes (the harmless snakes). 2. Ophidia colubriformes venenosi (those which, not having the viperine aspect just now described, are the more dangerous from their innocent appearance). 3. Ophidia viperiformes (the viperine snakes).

Although apparently named from their form only, it is the teeth which have chiefly to do with these latter distinctions, as will be seen on reference to the dotted examples of upper jaws. The first have the six rows of simple teeth (four above, as seen, and the lower jaw teeth), in all from 80 to 100 perhaps. The second have the two rows of palate teeth, the lower jaw teeth, and a fixed fang on each upper jaw, with one, two, or more simple teeth in addition. The Australian poisonous serpents are nearly all of this group, the only viperish-looking one, the ‘Death adder,’ having fixed fangs like the cobras. The sea snakes and the Elapidæ are included. The third have only four rows of simple teeth, viz. those of the lower jaws and those of the palate, with a solitary moveable fang in each upper jaw.