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it confers is a very transitory one, and therefore cannot be dependent on any
persistent, reactive, systemic change such as that which is induced under the
influence of the habitual introduction of venom into the system. The immunity
which is established by the habitual introduction of venom persists almost
unaltered for periods of months, whereas that connected with the access of
antivenene to the circulation appears to disappear entirely within the course of
a few days. The phenomena in the former case appear to indicate the estab-
lishment of a persistent systemic manufacture of an antidotal material, those of
the latter the action of an extraneous antidote, which is capable of remaining
for some time unaltered after entering the circulation because it is a blood
derivative, but which does not induce any reactive, systemic manufacture of
material of like nature to itself, and undergoes total expenditure within a com-
paratively short time.
The above conclusions in regard to the action of antivenene differ from
those at which Professor Fraser has arrived* He finds that the results of
treatment with antivenene are most satisfactory in cases in which the antidote
forms the vehicle in which the venom is dissolved, less satisfactory where they
are introduced simultaneously but in distinct sites, and least satisfactory where
the introduction of the venom precedes that of the antidote, and argues from
this that the antidotal property of antivenene must necessarily be owing to its
exerting a direct action on the venom. Here, however, there can be no ques-
tion whatever that the antecedent administration of antivenene gave by far the
greatest ratio of recoveries ; and, taking Professor Fraser's data as they stand,
it appears that they may be interpreted in a fashion quite distinct from that in
which he has interpreted them. In dealing with them, he apparently has omitted
to take into account that the outcome in any case must be liable to be modified
by conditions affecting the relative rates at which the venom and the antidote are
absorbed into the circulation. To any one familiar with the characters of watery
solutions, containing at the utmost a few milligrammes of dried venom per C.C.
of water, it must be clear that they are likely to be much more rapidly absorbed
than viscid solutions of antivenene containing 0.1 gramme of dried serum per C.C.
of water, and, consequently, that the antidote must be placed at a disadvantage
in cases where it has to conflict with antecedent or simultaneous but independent
injections of aqueous solutions of venom as compared with cases in which it forms
the vehicle in which the venom is dissolved, and in which, therefore, differences
in rate of absorption no longer come into play. In cases in which the venom and
the antidote are mixed with one another, their absorption must necessarily go on
si mul t aneousl y and al i ke ; i n cases where t he aqueous sol ut i ons of ant i venene
and venom are introduced at the same time, but at distinct sites, the absorption
* Immunisation against Serpents' Venom : an Address delivered by Professor Fraser, M.D., LL.D.,
F.R.S., at the Royal Institution of Great Britain, on Friday, March 20,1896.