COBRA POISON. 
509 
§ 667 .] 
1. A direct action on the muscular fibres or on the nerve endings. 
2. An action on the intra-cardial vagal mechanism. 
Concentrated solutions cause irregular and extreme cardiac excita¬ 
tion, with early death in systole ; with less concentrated solutions, the 
early stage of excitement yields to a prolonged phase in which the 
tonic action of the poison in the heart is most pronounced, the beat is 
regular, steady, and strong. 
When given subcutaneously in low lethal doses, death occurs from 
paralysis of the respiratory centre ; there is a gradually increasing 
venosity of the blood, and if life is prolonged beyond the usual term 
(five hours) the phrenic and other motor nerves may become paralysed. 
If a large dose be given intravenously, the respiration may cease almost 
at once. By applying cobra venom direct to the exposed medulla 
oblongata of the rabbit, Elliott has shown that the respiratory centre 
can be paralysed without the phrenic nerve ends or the heart being 
appreciably affected. 
If very large doses be given, the direct action of the poison on the 
heart may produce death by cardiac failure. Such large doses cause (u) 
a sudden fall of blood-pressure ; ( b) a subsequent rise, if the dose has 
not been too large ; (c) a final fall to zero. 
Cobra poison, in common with that of most of the Colubridce, prevents 
the coagulation of the blood, in contradistinction to the viper poisons, 
which strongly coagulate blood ; both classes of poison appear to dis¬ 
solve out the red colouring-matter of the blood. 
The post-mortem appearances are not very distinctive ; at the point 
of injection, there is often a slight haemorrhagic oedema. The liver and 
the spleen show on their surfaces circumscribed haemorrhagic spots ; 
the peritoneum, the meninges, endocardium, pleura, and mucous mem¬ 
branes show frequently ecchymoses, and the blood is fluid and dark. 
§ 667. Effects on Man. —By far the best account hitherto published 
of the effects of the cobra poison is a paper by Dr Wall, 1 in which he 
points out the very close similarity between the symptoms produced 
and those of glosso-pharyngeal paralysis. This is well shown in the 
following typical case :—A coolie was bitten on the shoulder about 
twelve at midnight by a cobra ; he immediately felt burning pain at 
the spot bitten, which increased. In fifteen minutes afterwards he 
began, he said, to feel intoxicated, but he seemed rational, and 
answered questions intelligently. The pupils were natural, and the 
pulse normal; the respirations were also not accelerated. He next 
began to lose power over his legs, and staggered. In thirty minutes 
after the bite his lower jaw began to fall, and frothy, viscid mucous 
saliva ran from his mouth ; he spoke indistinctly, like a man under 
1 “ On the Difference of the Physiological Effects produced by the Poison of 
Indian Venomous Snakes,” by A. T. Wall, M.D., Proc. Roy. Soc., xxxii. 333, 1881. 
