On the nature of snake-poison / [Sir Joseph Fayrer].

  • Fayrer, Joseph, Sir, 1824-1907.
Date:
[1884]
Catalogue details

Licence: Public Domain Mark

Credit: On the nature of snake-poison / [Sir Joseph Fayrer]. Source: Wellcome Collection.

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    small teeth, one outer or maxillary, and one inner or pala- tine row; in the majority, there are from 20 to 25 teeth in the outer row. In the venomous snakes, the outer row is represented by one or more large tubular fangs, firmly anchylosed to the maxillary bone, which is movable, and by its movement causes the erection or reclination of the fang which is so marked in viperidae. In the innocent snake, the maxillary bone is elongated, and gives insertion to a row of teeth ; in the poisonous colubrine, it is much shorter, giving insertion to only one or more teeth, the anterior and largest of which is the poison-fang. In the viperine snakes, the maxillary bone is reduced to a mere wedge, giving insertion to a long curved and tubular fang, which is a much more formidable weapon than the fang of the cobra, or other colubrine snake. These fangs, when reclined, are covered by a sheath of mucous membrane, in which lie also several loose reserve fangs, in different stages of growth. When the working fang is lost by accident, or is shed, one of the reserve fangs takes its place, becoming fixed to the maxillary bone, and placed in communication with the duct of the poison- gland. The teeth vary considerably in the different subdivisions of the order. They are described as being perforated. Though this is apparently the case, it is not really so. They are dense and compact, enclosing the usual pulp- cavity ; but being folded on themselves form either an open groove, as in the hydrophidae ; a complete canal, as in cobra ; or a more complete tube still, as in viperidae. During development, the laminated tooth folds like a leaf on itself, and so forms the channel along which the virus is conveyed ; and thus the tooth makes a most complete hypo- dermic syringe. The poison is secreted by a conglobate racemose gland situated in the temporal region behind the eye. It is of considerable size—about that of an almond in the cobra— and is furnished with a duct which opens into the capsule of mucous membrane enveloping the base of the fang ; the venom thence flows into the dental canal, and is injected into the wound when the tooth penetrates the bitten object. At the orifice of the duct it seems probable that there may be a sphincteral arrangement of muscular fibres which would enable the snake to control the ejaculation of the virus.