PHYSIOLOGICAL ACTION OF VENOM OF BLACK SNAKE. 241 
the stupor and drowsiness which were sometimes noticed, might 
have been caused indirectly. 
According to Wall,’ the principal action of cobra poison on the 
nervous system, consists of an extinction of functions extending 
from below vpwards, of the various nerve-centres constituting the 
cerebro-spinal system ; and though, no doubt, other parts of the 
nervous system suffer, this poison acts especially on the respiratory 
centre, and on those other ganglia allied to it in the medulla 
oblongata, which are in connection with the vagus, the spinal 
accessory, and the hypo-glossal nerves, and it is directly to this 
destructive action that we have to attribute death in most cases 
of cobra poisoning. 
Wall found, however, that there were marked differences 
between the actions of the poison of the cobra, and Daboia 
russelii, (a viperine snake) upon the nervous system. The poison 
of the latter almost always occasioned violent convulsions, which 
were not due as in cobra poisoning to failure of the respiration. 
They occurred quite suddenly, and were in no way obviated by 
artificial inflation of the lungs. Sometimes the animal died at 
Once, sometimes after a partial recovery. Wall thought these 
convulsions were caused by the direct operation of the poison on 
the nervous system and not by asphyxia. Nevertheless, I feel 
convinced that they were in reality asphyxial convulsions, and due 
to intravascular clotting, whereby the circulation was impeded, or 
altogether stopped. 
Another very interesting fact discovered by Wall was that if 
Daboia venoin was heated to 100° C. its power of producing these 
convulsions was abolished. Injection of the boiled poison caused 
@ gradual cessation of the respiration, followed by a few convul- 
sions, due to respiratory failure. 
Exactly the same result is obtained by heating Pseudechis 
venom to 85° C., and I have already shown that this is because 
its capacity to occasion intravascular clotting has thereby been 
aimost destroyed. 
1 “Indian Snake Poisons.” 
P—July 3, 1895, 
