M e d i c a l O f f i c e r s o f t h e A r m y
o f I n d i a .
9
One of the most conspicuous of the phenomena attending the addition
of cobra-venom to blood is a very rapid alteration in the colour of the latter.
Normal specimens of blood do undergo a certain amount of change in colour
for a short time after leaving the vascular system, those portions of them which
are in direct relation to air, becoming vivid scarlet, and those which are not so
gradually acquiring a bright plum-colour, but subsequently they remain, unaltered
in tint until putrefactive change has been established for some time. This,
however, is not the case in specimens which have been treated with venom for
even very small ratios of the latter suffice to induce such rapid darkening, that,
within the course of a very short time, the substance of the mass becomes prac-
tically black and the surface of a very deep lake hue. Such changes and the
rapidity and extent to which they are carried out serve as indices to the rate and
degree of solution of the bodies of the erythrocytes, and, on examining any speci-
men of blood in which they may have been fully developed, it will be found to con-
sist of a homogeneous fluid, saturated with haemoglobin and containing the per-
sistent leucocytes and, where such bodies are normally present, crowds of ery-
throcytic nuclei. This alteration in colour is apparently quite independent of
the occurrence of any loss in the respiratory property of hæmoglobin and entirely
owing to effects produced on the refractive and reflective qualities of the fluid
by the solution of so great an amount of its particulate contents, for thin
films of specimens of blood, in which it has for sometime been fully developed,
rapidly acquire a vivid scarlet hue on free exposure to air.
The process of solution does not appear to be affected to any considerable
extent by conditions of temperature and thus differs from that which determines
reduction in the respiratory property of the hæmoglobin and which is unequivo-
cally accelerated by heat. The rate at which solution progresses and the degree
to which it attains vary with the ratio of venom to blood ; complete or almost
complete solution occurs almost immediately where the ratio of venom is rela-
tively high ; the process is more slowly but equally completely effected where
the ratio is lower, and still more slowly and imperfectly carried out where the
mass of blood to be acted upon becomes very excessive. The phenomena are
such as would seem to indicate the presence of a certain ferment-property in
the venom whereby, up to a certain point, small ratios of it are able gradually
but eventually to occasion the same effects as those which are suddenly and
explosively occasioned by the access of larger ones.
The solvent action of cobra-venom on mammalian blood is just as energetic
as it is on that of birds, but the blood of birds presents certain special advan-
tages in the study of the progress of the process, because the nucleation of the
erythrocytes and the fact that the nuclei escape solution, afford an index to the
occurrence of degrees of change which might otherwise readily escape notice.
In the case of mammalian blood extensive processes of solution may take place C