9

the venoms of several other species and have found that all viperine venoms and
some colubrine poisons have a similar action to that of daboia venom. On the
other hand, the venoms of the cobra and of the king cobra have a direct anti-
ferment action, diminishing the blood coagulability in vivo and delaying or
completely inhibiting the clotting of citrate or oxalate plasma in vitro. The
venoms of the following snakes with which I have worked increase the coagula-
bility of the blood plasma, which action can be easily demonstrated with citrate
plasma in vitro: (1) Daboia Russellii, (2) Echis carinata, (3) Trimeresurus
gramineus, (4) Crotalus adamanteus and (5) Hoplocephalus curtus. If a suitable
amount of any of these poisons be added to citrate plasma clotting takes place,
in the case of the last four almost instantaneously. The action of daboia venom
in this respect is not so marked nor so energetic as that of the others: it takes
a larger quantity and a much longer time to bring about clotting than any of the
other four poisons.

       Daboia venom anti-serum was now tested against this action of this group
of poisons. The test dose of each venom used was such an one as caused solid
clotting of 2 c.c. of citrate plasma within a short time. The following was the
method employed in all instances. The test dose of venom was mixed with
varying amounts of serum. The mixtures were allowed to stand at laboratory
temperature for half an hour. To each tube were then added 2 c.c. of citrate
horse plasma (1 per cent.). The results were noted at short intervals. From
table IX of the protocols it will be seen that, while the serum in small amount
had a complete hindering effect on this action of its homologous venom, it had
no neutralising effect on the other poisons against which it was tested. In this
respect it appears to be specific. As regards the venom of Crotalus adamanteus
this result appears to be in contradiction to the result obtained in the experiments
made in vivo. It is, however, to be noted that the test dose of this poison used
in the animal experiments did not produce an intravascular thumbosis: death was
due to other causes.

      The following conclusions may now be drawn:—

      1. By injecting a horse with pure unheated daboia venom an anti-serum for
this poison has been obtained. This serum is of considerable strength and has
a marked neutralising effect on all the actions of daboia venom both in vivo and
in vitro. It should be of considerable therapeutic value in cases of bites from
this snake.

      2. The serum thus obtained is markedly but not strictly specific in vivo;
it has no action on the poisons of five colubrine snakes against which
it was tested: it has a certain neutralising action on the venom of Crotalus
adamanteus, but has no effect on the venoms of two other vipers, namely, Echis
carinata and Trimeresurus gramineus.

C