Medical Officers of the Army of India.
85
(a) and ( b)—were now treated—(a) with an injection of 0.5 C.C. of the, solution,
or an equivalent of somewhat more than a minimal lethal dose of venom, and ( b)
with one of 0.75 C.C., or a double minimal lethal dose. The normal symptoms
of intoxication manifested themselves in due course, and death occurred 5½
hours after the injection in the case of ( b), and 16 hours after the injection in
that of ( a). In this case, then, there was conclusive evidence of excessive im
- m u n i t y o n t h e p a r t o f a s n a k e , a n d n o e v i d e n c e w h a t e v e r t o s h o w t h a t i t s b l o o d
contained any appreciable quantity of antivenene either as the result of previous
auto-inoculation or in connection with the sudden artificial introduction of a
relatively enormous dose of venom into the system.
The next experiment yielded very curious and unlooked-for results. A
cobra, weighing somewhat less than half a kilo, received a subcutaneous injec-
tion of 0.75 gramme of dry cobra-venom, or a dose which would have sufficed
t o pr ov e f a t a l t o 1, 000 f owl s of 1 ki l o e a c h i n we i ght . No a ppr e c i a bl e s ympt oms
of illness followed, and after an interval of a week the snake was decapitated
and its blood allowed to coagulate. When the serum had separated, two fowls
(a) and (b )—were treated—(a) with a subcutaneous injection of 0.001 gramme, or
a little over a minimal lethal dose of dried cobra-venom dissolved in 0.6 C.C. of
serum, and ( b) with a subcutaneous injection of 3 C.C. of serum alone. In the
case of (a ) the normal symptoms of intoxication rapidly developed and ran on
to a fatal termination. In the case of ( b ) a considerable amount of drowsiness
immediately followed the injection of the serum, but it soon wore off, and in
the evening the bird appeared to be quite well. During the course of the
following forenoon, however, unequivocal and characteristic symptoms of
cobrine intoxication manifested themselves and continued to be present,
although not in a very high degree, during the rest of the day. On the follow-
ing morning the bird was profoundly affected, and death occurred about 60
hours after the injection of the serum had been effected.
Now in this experiment the phenomena not only failed to supply any evi-
dence whatever of the occurrence of any reactive manufacture of antivenene
within the system of the cobra in connection with the introduction of a
relatively enormous dose of venom, but showed that, after the lapse of a week,
the blood, in place of containing a very high percentage of antivenene, actually
contained enough unaltered venom to give rise to fatal intoxication when the
serum gained access to the circulation of a susceptible animal, and this although
the snake itself had shown no appreciable symptoms of being affected by it.
This cannot fail to suggest the possibility that in those cases in which treat-
ment with cobrine serum has appeared to be attended by the establishment of
a certain degree of immunity, the result is not to be ascribed to the presence of
antivenene, but of a certain amount of venom in the blood. Cobrine serum, as
the data recorded in the experiments specially dealing with it clearly show,