Venomous animals / by Sir J. Fayrer.

  • Joseph Fayrer
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: Venomous animals / by Sir J. Fayrer. Source: Wellcome Collection.

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    4 order Ophidia, which has three subdivisions: 0. colubriformes, in- nocuous, 0. colubriformes venenosi, and 0. viperiformes, venomous. These are distributed widely over the globe, land and sea. The most venomous are generally denizens of warm climates. The poison apparatus of a snake consists of a composite racemose gland, situated in the temporal region, which secretes a clear, slightly viscid fluid, that is poured through a duct into a grooved fang situated on a movable maxillary bone, capable of erection and reclination, to a greater extent in viperine than in colubriform snakes, by the action of muscles which push forward the ectopterygoid and maxillary bones, raise the fang, at the same time compress the gland and eject the poison through the duct into the groove in the fang; it is thus hypodermically injected into the bitten part. The fangs are longer, more curved, more movable, and more formidable in viperine than in colubrine -snakes—they are deciduous, and when lost by accident or by the process of shedding, are quickly replaced by reserve fangs that lie loose in a fold of mucous membrane. On the loss of a fang the most advanced of the reserves quickly takes its place, becoming anchylosed to, and moving with the maxillary bone. The groove is on the convex aspect of the fang, and opens near the point for emission of the venom. There is an opening at the base of the fang, into which the poison is shed from the papillary orifice of the poison duct. This at the time of emission becomes closed in by a fold of mucous membrane, so that the poison is directed into the groove in the tooth. Viperine snakes can recline or erect each fang independ- ently of the other. This power is limited in colubrine snakes. The difference may be well seen in ISTaja tripudians—cobra; and Cro- talus-horridus—rattlesnake. The poison is secreted in consider- able quantities; half a drachm may be collected from a fresh and vigorous cobra. It is a clear, slightly viscid fluid, and very deadly in its action, probably more active in some snakes, quan- tity for quantity, than in others, and varying in activity in the same species or individual, according to season, temperature, state of health, etc. It acts most rapidly when injected into the blood; but it can be absorbed through mucous and serous membranes, as seen by its poisonous effects when applied to the conjunctiva, the stomach, the peritoneum. It may neither be applied to the lips nor taken into the stomach with impunity, and sucking a snake bite is by no means free from danger, though if the saliva be quickly ejected and the mouth washed, the danger is probably small. It contains an active principle, which has been described as echidnine, viperine, crotaline. Analysis has shown the poison to be very nearly like albumen in composition. It is most active in its action on warm-blooded creatures, but it takes effect in all. It appears, however, that poisonous snakes are very insensible to
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