greatly in individual instances owing to want of uniformity in the ratio of venom
to blood, to variations in the temperatures to which the mixtures of venom and
blood were exposed, and, finally, to variations in the length of the period
intervening between the time at which the venom was introduced into the
vascular system and that at which the blood was examined. Where the ratio
of venom to blood was highest, evidences of reduction of respiratory property
were clearly recognisable at the time at which the blood was removed from the
body, even in those cases in which the removal was effected within a few
minutes after the experiment had been initiated. Where the ratio of venom was
lower, but still considerably in excess of that corresponding to a minimal lethal
dose of venom, appreciable evidences were either present or absent in the blood
when first removed from the vascular system; present in cases in which a
considerable time had elapsed since the beginning of the experiment, and in
which the temperature of the body had been artificially maintained after death;
absent where the examination was carried out shortly after the beginning of the
experiment, or where the temperature of the body had not been kept up after
death. Finally, where the ratio of venom to blood was very low, as it may
fairly be assumed to have been in all cases of subcutaneous injection, and as
it certainly was in all cases of the intravascular injection of minimal lethal doses
of venom, there was an entire absence of any appreciable reduction, even in
cases in which the examination was not made until after the lapse of a consider-
able time after the beginning of the experiment.
Taken as a whole, the results are such as to favour the belief that the
reductive changes in the respiratory property of specimens of blood under the
influence of contact with cobra-venom outside the body are also present in cases
in which the contact is established within the vascular system. Where the
amount of venom entering the latter is relatively great, evidences of the
occurrence of immediate and general reduction are present; where the amount
is smaller and conditions favouring the toxic action are present, evidences of
reduction, although primarily absent, soon make their appearance, and, under
these circumstances, the mere fact that appreciable reduction fails to manifest
itself where the ratio of venom to blood is reduced beyond certain limits cannot
be logically regarded as any conclusive evidence of an entire absence of
reduction, seeing that the effects of a certain amount of reduction may readily be
marked by those attending the presence of an excess of hæmoglobin retaining
its normal affinity for oxygen. We have the clearest evidence of the occurrence
of reduction in respiratory property under the influence of venom where the
ratio of the latter to blood reaches a certain level, and that such evidence
should cease to be appreciable when the ratio falls below this is only what
might have been reasonably expected to occur. There is nothing to warrant
the belief that any alterations in the specific properties of venom attend mere
reductions in its quantity, and, hence, when we find appreciable evidences of