5
into the marginal vein of the ear of a rabbit. The rabbit died in two minutes. In
the second experiment 5 c. c. of serum were injected into the marginal vein of
one ear. A. few minutes afterwards the test dose of venom, viz., a single lethal
dose, was injected into the marginal vein of the other ear. This animal likewise
died in about two minutes. From these two observations we can at once conclude
that Calmette's serum is quite inactive against the venom of Echis carinata.
The outcome, then, of all these observations is to prove conclusively that,
while the serum prepared by Calmette at Lille is of considerable value as a
therapeutic measure in cases of cobra bite, if injected sufficiently early and in
sufficient quantity, it is of no value whatever in the treatment of cases of bites
from Daboia Russellii, Bungarus fasciatus, or Echis carinata.
We may now pass on to consider the experiments which were made to
test the serum got from a horse immunised with the venom of the Australian
tiger snake, against the venoms of some of the Indian snakes. This serum was,
as I have mentioned above, prepared by Dr. Tidswell of Sydney, to whom I am
greatly indebted for his kindness in sending me a considerable quantity. I have
also stated above that Tidswell found this serum to be strongly antitoxic to the
venom with which it was prepared, but to be quite inactive towards the venoms
of three other Australian snakes. The results, therefore, of the observations
which I have now to record, made with this serum and the poisons of three
Indian snakes, are of the greatest theoretical interest.
The serum was first tested with the venom of the cobra. For these
experiments rats were the animals employed. The test dose of venom used
was ten lethal doses, viz., 0.7 milligramme.12 This test dose and different
quantities of serum were mixed in vitro . The mixture was allowed to stand
at laboratory temperature for half an hour. It was then injected subcutaneously
into the inner side of the thigh. A reference to the protocols (series No. V)
will show that the rat which received 4 c. c. of serum along with the test dose
died after practically the same interval of time as one of the controls. The
serum, therefore, had failed to neutralise any of the venom.
Tidswell's hoplocephalus serum was next tested with the venom of
Bungarus fasciatus. For this series of experiments rabbits were the animals
employed. I have already stated that the minimum lethal dose of this poison for a
rabbit is 0.7 milligramme per kilo. when injected intravenously. The test dose of
venom now used was 4 milligrammes per kilo., viz., about 6 lethal doses. This
test dose and different quantities of serum were mixed in vitro. The mixture
was allowed to stand at laboratory temperature for half an hour. It was then
injected into the marginal vein of the ear of a rabbit. It will be seen from the
protocols (series No. VI) that the rabbit which received 5 c. c. of serum along
with the test dose died in even a shorter time than the control which received
no serum. We have, therefore, to conclude that the serum failed to neutralise
even a modicum of the venom.
Lastly, the serum prepared by Dr. Tidswell was tested with the venom of