24
Scientific Memoirs by
As regards the question of relative susceptibility to intoxication, the data
show that, with cobra-venom of a given stock, 0.00075 gramme per kilo ; 0.04
gramme per kilo ; 0.5 gramme per kilo ; and 1.5 gramme per kilo constituted
approximately minimal lethal doses respectively for fowls, water-lizards,
dhamins, and cobras. In other words, they show that fowls are about 50 times
more susceptible to cobrine intoxication than water-lizards are, and about 700
and 2,000 times more susceptible than dhamins and cobras, respectively, are.
On turning to Table V it will be seen that the phenomena presented by
portions of reptilian blood, or, more correctly, of the blood of the reptiles used for
experiment, are essentially of the same nature as those characteristic of speci-
mens of fowls' blood, as illustrated in Table I, save in so far as the normal rate
of coagulation comes into play as a modifying factor. In respect to solution of
erythrocytes, and reduction of the respiratory property of hæmoglobin, no
differences are present, solution taking place very slowly and reduction not
setting in appreciably until putrefactive changes are already far advanced.
But, whilst in the case of fowls' blood, the rapid incidence of coagulation leads
to the formation of a homogeneous clot, in that of reptilian blood, the incidence
of the process is so much delayed as to allow of full time for the subsidence
of the erythrocytes and the consequent differentiation of the clot into an upper
transparent, pale yellowish or opalescent stratum, resting on a dense, deep red
one crowded with erythrocytes.
When we come to deal with Table VI, we encounter a series of data
showing that like amounts of cobra-venom acting on like quantities of blood
(9 to 11 c.c.) produced very different effects according to the nature of the
animals from which the latter was derived. Where 0.01 gramme of venom was
added to 10 to 10.5 c.c. of blood, in the case of fowls' blood complete solution
of the bodies of all the erythrocytes had taken place within 1¼ hours ; in that of
varanus' blood a like result had very nearly occurred within 48 hours ; in that
of the blood of dhamins solution was very incomplete after the lapse of 48
hours ; and, in that of cobrine blood, no appreciable indications of solution were
present even after the lapse of 96 hours subsequent to the beginning of the
experiment. In experiments in which the amount of venom was increased to
0.116 gramme, the amount of blood remaining almost as before, very nearly com-
plete solution had occurred in varanus' blood within 24 hours ; complete solu-
tion in dhamins' blood within 48 hours ; and partial solution in cobra blood
within a like period. Finally, where the venom amounted to 0.2 gramme per
9 c . c . o f b l o o d , a l m o s t c o m p l e t e s o l u t i o n h a d t a k e n p l a c e i n v a r a n u s ' b l o o d
within 30 minutes ; complete solution in that of dhamins within 2½ hours ; and
only partial solution in that of cobras within 120 hours after the beginning of the
experiment. The phenomena present in such comparative experiments are
illustrated in figs. 6-7, 9 - 15 and 17-19 of Plate I, and clearly indicate that,
in so far as solution of the bodies of erythrocytes is concerned, the power of