6
Daboia Russellii. In the series of experiments Which were first undertaken with
this end in view the test dose of venom used was 0.5 milligramme per kilo. of
rabbit. It was found by experiment that this amount of the sample of venom
employed did not cause intravascular clotting, but killed after about 18 hours
from other causes. 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 the rabbit.
A glance at the protocols (series No. VII A) will show that 4 c. c. of serum
did not in the least delay the fatal result.
A single experiment was made using a sample of daboia venom, of which
0.2 milligramme per kilo. killed a rabbit in a few minutes from intravascular
thrombosis. Three times this amount, viz., 0.6 milligramme per kilo., was used
as a test dose: 5 c. c. of serum were first injected into the marginal vein of one
ear : five minutes afterwards the test dose of venom was injected into the margi-
nal vein of the other ear. It will be seen from the protocols (series No. VII B)
that even this large quantity of serum had no effect on the toxic action of the
poison, the animal dying in one and a half minutes.
This observation completes the experiments which were made with a serum
prepared with the pure venom of a single snake, viz., Hoplocephalus curtus. It
is perhaps to be regretted that this serum was not tested with the poisons of
some of the other Indian snakes. Unfortunately, however, several of the phials
had got broken in transit from Australia, and there remained only sufficient for
the experiments which I have detailed above. A priori, however, it is almost
certain that this serum would have had no neutralising power for other venoms.
These results completely confirm and extend Tidswell's observations. This
observer found that the serum prepared with the unmixed venom of the tiger
snake was strongly antitoxic to that particular venom, but had no antitoxic
effect for the poisons of three other Australian snakes, viz., the brown snake,
the black snake, and the death adder. I have now further shown that this
serum has no neutralising power for the venoms of three of our Indian snakes,
viz., Naia tripudians (cobra), Bungarus fasciatus (banded krait), and Daboia
Russellii (chain viper). Now, we have seen that the Australian snakes belong
to the same sub-family, but to different genera, as the cobra and the banded
krait. These results, therefore, taken along with the results collated above, got
with Calmette's serum, show conclusively that the serum prepared with the
venom of any one genus of poisonous snake is specific for the venom of that
genus and is inactive for the poisons of other genera. It still remains to be
shown, if a serum prepared with a single venom would be specific for the
venom of that species, that is to say, inactive for the poisons of other species of
the same genus. Thus, for example, it still remains to be shown whether a
serum prepared with cobra venom is active or inactive for the venom of. the king
cobra and whether a serum prepared with the venom of Bungarus fasciatus is
active or inactive for the poisons of the other species of the genus Bungarus.