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Scientific Memoirs by

   Symptoms of intoxication appeared after an interval of 4½ hours, and death
occurred 5½ hours later.

   Experiment III. —A monkey (Macacus rhesus ) received by the mouth
a dose of 0.2 gramme, i.e. , 80 times the amount of a minimal lethal dose when
administered subcutaneously, and on the following day a subcutaneous injection
of 0.0025, or a minimal lethal dose of dried cobra-venom.

   Symptoms of intoxication appeared within 2 hours after the injection of
the venom, and death occurred 5½ hours later.

   These experimental results are again in conflict with those which Professor
Fraser seems to have obtained, and which have led him to adopt the view,
which has been habitually entertained by the serpent-charmers of this country,
that the ingestion of venom is a means of securing immunity against its action
when directly introduced into the system. The result in Experiment III certainly
shows that the ingestion of an amount of venom 80 times as great as that
constituting a lethal dose when entering the system directly is incapable of
producing any appreciable effect on the action of a minimal lethal dose
administered subcutaneously 24 hours later, and that of Experiment 11, that the
prolonged and habitual ingestion of smaller quantities of venom is equally
inefficacious. The fact that the ingestion of even very large quantities of
venom is certainly not necessarily followed by the occurrence of any appre-
ciable symptoms of intoxication, and that neither the habitual ingestion of
venom nor a single ingestion of a very large quantity of venom is necessarily
in any way protective, cannot but suggest the possibility that in those cases in
which protective effects do seem to follow such treatment they have arisen in
connection with the presence of breaches of continuity or other abnormalities
in the surface of the mucous membrane of the alimentary tract allowing of the
absorption of a certain amount of crude venom, rather than with any analysis
of the venom by the normal digestive apparatus, such as Professor Fraser
supposes to occur, in the course of which those constituents giving rise to
intoxication are separated from those which cause the reactive formation of anti-
venene and which alone are subsequently absorbed.

   Had there been any evidence conclusively indicating that the immunity
against the action of their own venom, which is enjoyed by cobras, is necessarily
dependent on the constant presence of a material of the nature of antivenene
in their blood, there might have been some ground for anticipating that a
chronic habitual ingestion of venom, such as must take place in their case,
would lead to the establishment of immunity. But, as on the one hand there
is nothing to show that cobrine blood habitually contains antivenene, and on
the other there is conclusive evidence that an excessively high relative immu-
nity against the toxic action of cobra-venom may be present in perfectly harm-
less snakes such as Zamenis mucosus, in which no habitual ingestion of venom