34

Scientific Memoirs by

of this group come out very clearly when they are stated, as below, in tabular
form :—

Table showing the course of intoxication following intravenous injections of various
amounts of venom.

     The dose of 0.0005 gramme in Experiment XL was just as certainly fatal
as that of 0.34 gramme in Experiment XLIII, and the only difference in the two
cases was that whilst in the former one a latent period of several hours inter-
vened between the entrance of the venom into the circulation and the manifesta-
tion of any specific symptoms of its action, in the latter there was no appreci-
able latent period whatever and symptoms manifested themselves at once. The
initial symptoms were in both cases alike, and alike indicative of defective
respiratory supply, but those dependent on the action of the large dose of venom
ran a rapid course and terminated in well-marked convulsions and death within
a few minutes, whilst those caused by the minimal lethal dose followed a slowly
cumulative course in which general convulsions were absent or, at all events,
were not conspicuous.

     It appears, thus, that cobra.venom is a material the action of which is in
no way essentially affected by the amount of it which enters the system. Large
quantities give rise to more rapid effects than small ones, and in the case of the
latter, a latent period intervenes between the period of access of the venom and
the manifestation of any appreciable symptoms of its action, whereas maximal
doses give rise to maximal affects.at once. The introduction of large quantities
of venom into the circulation gives rise to almost instantaneous death, preceded
by violent general convulsions; moderate doses are followed by the development
of a series of symptoms, which begin to appear after a brief latent period, and
culminate in general convulsions and death; fractional doses are incapable of
causing any appreciable symptoms until a prolonged latent period has intervened,
but the symptoms which then appear are identical in character with those induced
by moderate doses, save that general convulsions are neither so constant nor so
well marked. But these phenomena surely warrant the conclusion that the
essential principle of the venom is of the nature of a ferment and, consequently,
not only capable of producing certain effects instantaneously when it enters the
system in great excess, but of inducing them gradually and cumulatively when
it enters in fractional quantities only.