35

intravascular clotting. It will be sufficient to detail a single experiment, among
many made by us, which would seem to point towards this conclusion.

       Rabbit 20—Weight 1,500 grammes. Received intravenously 4.5 milli-
grammes of cobra venom. It died immediately the injection was completed.
A post-mortem examination made at once showed the heart to be beating vigor
ously. The blood throughout was quite liquid, and not a trace of clot could be
found. The blood when shed clotted solidly.

       Now this rabbit received an amount of cobra venom 45 times greater
than the quantity of daboia venom which can cause rapid death from extensive
intravascular clotting (vide, Table III), and still not a sign of clot was observed
on careful post-mortem examination.

       Although it has been shown by many observers, Cunningham,²⁵ Kanthack,²⁶
Stephens,²⁷ etc., that cobra venom "in vitro" has a considerable hæmolytic
action, as well as the power to cause a deficiency in the blood coagulability, this
experiment,—an experiment which we repeated many times with the same
result—would seem to show that this venom contains no element similar to the
constituent of daboia poison which can cause intravascular clotting, which, as we
have seen, is such a remarkable result of the injection of that poison.

       On this complicated and important question, however, experiments are at
present being carried on by one of us, the result of which will form the subject
of another paper.

Neutralising power of Calmette's serum tested with daboia venom.

       We have now, in conclusion, to present a few experiments made with the
object of directly controlling Calmette's statement, that his antivenomous serum
was protective against the venom of all snakes.²⁸ In a previous paper ²⁹ we
have shown that this serum possesses a considerable power of neutralising pure
cobra venom. We now tested it with pure daboia poison. When we consider
the method by which Calmette immunises his horses, along with the observa-
tions which we have detailed above, we would expect from à priori reasons to
find that the serum which is supplied from Lille would have little or no power
to neutralise pure daboia venom. For the venom which Calmette employs to
immunise his horses is a mixture of colubrine and viperine poisons, (80 per
cent. of the former), and the solution of this mixture is heated before injection for
half an hour at about 73° C. Such treatment, we have seen, destroys or greatly
weakens, according to the strength of solution heated, the principal element
to which daboia venom owes its toxicity, viz., the substance or substances
which cause intravascular coagulation or deficiency in the blood coagulability.
He is, therefore, injecting into his horses a poison which contains either none, or
very little, of the toxin for which he wishes to.procure an antitoxin, and we would

E2