EFFECTS OF SNAKE VENOM ON COAGULABILITY OF THE BLOOD 141 
blood vessels, and, if only a small fraction of such clotting dose be given, a 
total or partial loss of coagulability ensues. 
The anticoagulating effect of cobra venom upon the whole blood and blood 
plasma has been demonstrated by Lamb in a quite ingenious manner. The 
whole blood was made incoagulable by means of 1 per cent sodium citrate or 
0.2 per cent potassium oxalate. Then the quantity of solution of calcium 
chloride which, when added, brings about coagulation of the citrate or oxa- 
late blood in a few minutes was determined. Now varying amounts of cobra 
venom were mixed with these incoagulable bloods before adding the lime 
solution. It was found that even 0.02 to 0.03 gm. cobra venom did not pro- 
duce coagulation when added to 1 c.c. of the citrate blood. On the con- 
trary, 0.0004 gm. of this venom kept 1 c.c. of the citrate blood unclotted, when 
the amount of calcium chloride solution sufficient to produce coagulation in 
1 to 3 minutes in the venom-free control citrate blood was added. Distinct 
inhibiting effect was exerted even by as minute a quantity as o.ccoor gm. of 
the venom. Lamb mentions that heating cobra venom to 75° C. for half an 
hour diminishes its anticoagulating power, but does not destroy it. 
With the citrate and oxalate blood plasmas the results obtained were 
practically the same as with the whole blood. In the case of the citrate 
plasma 0.001 gm. of cobra venom prevented coagulation of 2 c.c. of the 
plasma. 
The experiment with hydrocele fluid seems to be of much significance in 
interpreting the action of cobra venom in bringing about incoagulability of 
the blood and plasma. As is well known, the hydrocele fluid requires fibrin 
ferment or at least protothrombin, but not calcium chloride, to become 
clotted. Lamb found that 0.1 gm. of the citrate donkey plasma (z per cent) 
was sufficient to clot 2 c.c. of the hydrocele fluid in 20 minutes. But, when 
the venom was allowed to act for 10 minutes upon the plasma before the addi- 
tion of the hydrocele fluid, no coagulation took place. The addition of a 
small quantity of lime solution did not affect this result in any way. 
Now, returning to the action of daboia venom as an anticoagulating agent, 
Lamb could not observe any inhibitory effect upon the whole blood or blood 
plasma in vitro. The venom of Daboia, like that of Pseudechis, Notechis, and 
Echis, is a powerful anticoagulating agent when allowed to act in vivo, but not 
at alli vitro. Every varying subclotting dose, even as small as 0.000000009 
gm. has been tried, but on every trial the coagulability increased more or 
less, without, however, any diminishing effect. Thus the negative phase of 
coagulability in vive produced by daboia venom is of an entirely different 
process from that observed with a large dose of cobra venom both in vivo 
and in vitro. 
Finally an interesting observation was made to ascertain whether the 
previous addition of a large dose of cobra venom to the citrate plasma would 
prevent coagulation by a later addition of daboia venom to such mixture. 
It was found that the presence of a large quantity of cobra venom does not 
inhibit im the slightest degree the clotting action of daboia venom. In this 
