Fig. 23.—The Common Adder (Pelias berus).
The Common Adder varies in length, from thirteen or fourteen inches to double that length; and from two to three or even four inches in girth.
Its general colour varies considerably: in some it is olive, in others reddish-brown, varying sometimes to an ashy-grey; at other times it is greyish-black. A waving brown or blackish line runs along the back. A row of unequal spots of the same colour is observable on the flanks; the belly is slate-coloured; the head nearly triangular, a little larger than the neck, obtuse and truncated in front, and covered with granulated scales. Six small plates cover the muzzle, two of which are perforated for the nostrils, which are lateral, forming a blackish spot. Above is a sort of V shape, formed by two black bands. The upper jaw is a white ground, spotted with black; the lower jaw is yellow. The eyes are small and sharp, edged with black. The tongue is long, grey, and forked.
Adders are met with in the wooded, stony, and mountainous regions of southern and temperate Europe—in France, Italy, England, Germany, Prussia, Sweden, Poland, and even Norway. They are met with in the heaths near London and in the neighbourhood of Paris; they are met with at Montmorency, and in the forest of Fontainebleau. They feed upon Lizards, Frogs, mollusks, worms, insects, and small mammalia, such as Field-mice, Shrews, and Moles. They pass the winter and early spring in a state of torpor in deep hollows, where they are sheltered from the cold. It is not unusual to find several Adders coiled up together in one heap, entwined and intimately interlaced together.
The movement of Adders is abrupt, slow, and irregular. They appear to be shy and timid creatures, shunning the day, and only seeking their food in the evening. The young come into the world naked and living: so long as they are maintained within the mother, they are enclosed in eggs with membranous shells. Soon after their birth the young Vipers, whose length does not exceed six or seven inches, are abandoned by the mother, and left to shift for themselves. They do not, however, acquire their full development till they are six or seven years old. Adders are justly considered objects of fear and horror both to Men and to other animals. They carry with them a formidable apparatus, of which it is important that both the structure and the mode of action should be known. This venemous apparatus is composed of three parts—the secreting glands, the canal, and the hooked fangs.
The gland is the organ which secretes the venom; it is situated upon the sides of the head, behind and a little beneath the globe of the eye; it is formed of a number of inflated bladders, composed of a granulous tissue, and disposed with great regularity along the excretory canal, not unlike the barbs of a pen-feather. This arrangement, however, is only visible through a microscope. The tube destined to conduct the secreted venom through the gland is straight and cylindrical; after being filled, in its short journey it ends in two peculiar hook-like teeth, called fangs, tapering to a point, and in shape horn-like. They are much longer than the others, and placed one to the right, the other to the left of the upper jaw. The Adder, then, is furnished with two of these poison-fangs; they are curved and sharp-pointed, convex anteriorly, and furnished with a straight duct which commences in one part by a slit placed at the anterior part of its base, terminating by a second and smaller cleft towards its point, and on the same side. This last cleft is like a little trench or fine furrow, which extends the whole length of the convexity. These hooked teeth are surrounded by a fold of the gums, which receives and partly hides them, like a sheath, when they are at rest or hidden. They are attached to the upper maxillary bones, which are small and very mobile, and are put in motion by two muscles. Behind them are dental germs, intended to replace them when they fall out. The other teeth in the roof of the mouth belong to the palate, where they form two rows.
Fig. 24.—Fangs and Tongue of a Poisonous Colubrine Snake.
Such are the terrible weapons of the Viper group. It is not, therefore, as many persons still believe, with the tongue that the Adder inflicts its wound; the forked, projecting tongue serves them as a feeler, and to drink with, but cannot inflict a wound. We have said that when in a state of repose the hooked teeth are hidden; when the animal wishes to use them, they issue from their fleshy sheath, somewhat in the same manner as a man draws his knife, when attacked, to defend himself, and in this case the knife is poisoned.
Adders use their fangs to seize the small animals which serve as their prey. They do not voluntarily attack a Man; on the contrary, they flee at his approach. But if he imprudently places his foot on or attempts to seize them, they defend themselves vigorously. Let us see how an Adder conducts itself when it hunts its prey and takes it. In this case it may be supposed to act without passion, merely seizing its prey for food; it simply bites, sinking its fangs into the body of its victim. In proportion as the fangs penetrate the body of the animal the poison flows into the canal, which again conducts it to the fangs under the influence of the contracting muscles, by which they are raised and made to press upon the gland; but this movement causes the Adder to close its mouth, and the venom is injected into the wound.