PHYSIOLOGICAL ACTION OF VENOM OF BLACK SNAKE. 253 
Experiments to determine whether the venom affects the motor 
nerve terminations of mammals. 
Ragotzi came to the conclusion that the terminations of the 
phrenic nerves in the diaphragm were more sensitive both to the 
action of cobra venom and curari than the endings of the motor 
nerves in the muscles of the limbs. I accordingly chose the 
phrenics for the purpose of ascertaining whether Pseudechis venom 
in any way affected the passage of nervous impulses through 
motor-nerve terminations. 
When a dose of 005 to ‘01 gramme of venom per kilogramme 
of the animal’s weight is injected either subcutaneously, or into 
the peritoneal cavity of a rabbit, within a few hours the respiratory 
movements are much diminished both in rate and in extent The 
diaphragmetic contractions become progressively weaker, until 
they disappear altogether, and after a few feeble convulsions, the 
animal dies of asphyxia. If artificial respiration be resorted to, 
the convulsions speedily cease. Nevertheless, artificial inflation 
does not prevent the death of the animal, which occurs within a 
few minutes from circulatory failure. 
Thave already shown that this gradual failure of all respiratory 
movement is not essentially dependent upon any alteration in the 
circulation. It might however, be occasioned either by paralysis 
of the respiratory centre, or by interference with the passage of 
herve impulses along the phrenics to the diaphragm, as Ragotai 
maintained was the case in cobra poisoning. 
To test the latter alternative, I arranged a series of experiments 
m which I determined the least stimulus which, when applied to 
the Phrenic, would cause a contraction of the diaphragm, both 
i before injection of the poison and at intervals afterwards, until 
Spontaneous respiration had entirely disappeared. 
_ As the venosity of the blood from the failing respiration would 
Itself Produce a diminution in the excitability of the muscular 
mres of the diaphragm, the complete aeration of the blood was 
“cured by artificial inflation of the chest with warm air, and as 
