12
Scientific Memoirs by
blood is fractionally minute. It is evident from the results of experiment VIII
that a unit of dried venom is capable of affecting a mass of blood weighing
at least 52,000 times as much to such an extent as to practically abolish its re
-spiratory property entirely, which, as we have already seen, is by no means neces
-sary in or der to induce death by asphyxia. A loss of 30 per cent. of respiratory
property is sufficient to do this, and, consequently, the experimental data go to
show that a unit of dried venom is capable of affecting at least 156,000 times
its weight of blood to such an extent as to interfere with its respiratory property
to a fatal extent. But the average amount of dried material to be obtained
from any individual cobra as the result of a single ejection of venom is 0.254
gramme, an amount sufficient according to these data to produce fatal change in
about 40 kilos of blood, and, consequently, on the ordinarily accepted estimate
that the blood of an animal contributes one thirteenth part of total body weight,
sufficient to cause the death of an animal weighing 520 kilos, or about seven
times the weight of any average human subject. This estimate, moreover, may
understate the potency of the venom very considerably, as the experimental
data do not necessarily indicate its maximal ferment-power.
The data go to show that cobra-venom, not only affects the respiratory
property of the blood, but likewise its coagulability, and at the same time acts on
the red blood corpuscles in solvent fashion. The observations which have been
frequently and quite correctly recorded regarding the absence of any apprecia
-ble change in the microscopical features of the blood of animals which have
died under the influence of cobra-venom, may appear to be in direct conflict with
these data, implying that it possesses a solvent property on the bodies of the red
corpuscles ; but it is very doubtful whether they really are so. There can be no
question that the presence of a solvent property appears very conspicuously
where a relatively large amount of venom acts on a limited bulk of blood, or
where smaller quantities are given full time to produce their ferment effects
upon relatively large bulks ; but it does not necessarily follow that they should
manifest themselves equally clearly in the blood of animals which have died
in consequence of the introduction of the venom into the system in ordinary
quantities and in the normal fashion, more especially in cases where the red
corpuscles are non-nucleated and where, consequently, free nuclei are not present
as an index to the occurrence of processes of solution. In the first place, death
must necessarily take place long before the blood has undergone such profound
alteration as that which is present when a limited amount of venom has been
allowed time to produce its full effects on it ; and, secondly, an amount of venom
quite capable of producing fatal changes in the respiratory properties of the
blood may be insufficient to occasion much solution of the red corpuscles, even
if it be allowed time to exert its ferment action to the utmost. The presence of a
solvent action may readily escape notice, because the examination of the blood has
been conducted ere sufficient time has elapsed to render its effects conspicuous,