[648] “On the Difference of the Physiological Effects Produced by the Poison of Indian Venomous Snakes,” by A. T. Wall, M.D., Proc. Roy. Soc., 1881, vol. xxxii. p. 333.
There is often very little sign of external injury, merely a scratch or puncture being apparent, but the areolar tissue lying beneath is of a purple colour, and infiltrated with a large quantity of coagulable, purple, blood-like fluid. In addition, the whole of the neighbouring vessels are intensely injected, the injection gradually diminishing as the site of the poisoned part is receded from, so that a bright scarlet ring surrounds a purple area, and this in its turn fades into the normal colour of the neighbouring tissues. At the margin is also a purple blood-like fluid, replaced by a pinkish serum, which may often be traced up in the tissues surrounding the vessels that convey the poison to the system, and may extend a considerable distance. These appearances are to be accounted for in great part by the irritant properties of the cobra venom. The local hyperæmia and the local pain are the first symptoms. In man there follows an interval (which may be so short as a few minutes, or so long as four hours) before any fresh symptoms appear; the average duration of the interval is, according to Dr. Wall, about an hour. When once the symptoms are developed, then the course is rapid, and, as in the case quoted, a feeling like that of intoxication is first produced, and then loss of power over the legs. This is followed by a loss of power over the speech, over swallowing, and the movement of the lips; the tongue becomes motionless, and hangs out of the mouth; the saliva is secreted in large quantities, and runs down the face, the patient being equally unable to swallow it or to eject it, and the glosso-pharyngeal paralysis is complete.
§ 644. Antidotes and Treatment.—Professor Halford some years ago proposed ammonia, and M. Lacerda in recent times has declared potassic permanganate an antidote to the cobra poison. The ammonia theory has been long disproved, and before Lacerda had made his experiments I had published the chemical aspect of some researches,[649] which showed that mixing the cobra venom with an alkaline solution of potassic permanganate destroyed its poisonous properties. Other experiments were also made in every conceivable way with potassic permanganate, injecting it separately, yet simultaneously, into different parts of the same animal’s body, but so long as it does not come into actual contact with the poison it has no antidotal power whatever over the living subject. Other observers, previous to the researches mentioned and since, all agree that permanganate is no true antidote.[650] It only acts when it comes directly into contact with the venom, but when the venom is once absorbed into the circulation potassic permanganate, whether acid, alkaline, or neutral, is powerless. That it is of great use when applied to a bite is unquestionable, for it neutralises or changes any of the venom hanging about the wound, and which, if allowed to remain, might yet be absorbed; but here it is obvious that the venom is, so to speak, outside the body. A. Galmette (Annales de l’Institut Pasteur, 25th March 1892) has found that gold chloride forms an insoluble compound with the cobra poison, which is not poisonous, and that animal living tissues impregnated with gold chloride will not absorb the poison. He even advances some evidence tending to show that gold chloride may overtake, as it were, the venom in the circulation, and thus act as a true antidote. This is improbable, and, until confirmed, the general treatment most likely to be successful is the immediate sucking of the wound, followed by the application of an alkaline solution of permanganate; and lastly, if the symptoms should nevertheless develop, an attempt should be made to maintain the breathing by galvanism and artificial respiration.[651]
[649] Analyst, Feb. 28, 1877.
[650] See Note on the effect of various substances in destroying the activity of the cobra poison. By T. Lauder Brunton and Sir J. Fayrer, Proc. Roy. Soc., vol. xxvii. p. 17.
[651] Some of my experiments on the cobra poison may be briefly detailed, illustrating the general statement in the text:—
1. A quantity equal to 1 mgrm. of the dried venom was injected subcutaneously into a chicken. The symptoms began in two minutes with loss of power over both legs. In eight minutes the legs were perfectly paralysed. There were convulsive movements of the head and wings, slowing of the respiration, and death in ten minutes. The same quantity of poison was treated with a little tannin, and the clear liquid which separated from the precipitate injected into another chicken. The respiration became affected in ten minutes; in eighteen minutes the bird had become very quiet, and lay insensible; in twenty minutes it was dead, the respiration ceasing before the heart.
2. In seven experiments with cobra poison, first rendered feebly alkaline with an alkaline solution of potassic permanganate, no effect followed. Three of the experiments were on chickens, four on rabbits.