EFFECTS OF SNAKE VENOM ON COAGULABILITY OF THE BLOOD 135 
quantity of daboia venom in vitro. This finding threw an entirely different 
light on the mechanism of coagulation of the blood plasma in venom toxica- 
tion. The mere decalcification of the blood or blood plasma by means of 
sodium citrate brings about, as has been long known, a condition of non- 
coagulability of the blood so treated, and coagulation can easily be effected 
by simply adding a sufficient amount of calcium chloride to such fluid. 
Now, Lamb found that the addition of a small amount of daboia venom, in lieu 
of CaCl,, to such decalcified fluid plasma or blood suffices to produce coagu- 
lation. Here neither fibrinogen nor paraglobulin is lacking, but an active 
fibrin ferment is not present on account of the absence of activating salt, 
calcium chloride, in the mixture. Thus, the function performed by the 
venom in bringing about such mixture is that of a preformed fibrin ferment. 
In just what relation this fibrin ferment stands to that of the blood or proto- 
thrombins or thrombogens is not cleared up. But that it is not supplying 
these proto-enzymes with calcium chloride is evident from the minute quan- 
tity required to produce coagulation of the citrate plasmas. In fact, as 
Martin ' found later, no relation to the amount of anticoagulating salts con- 
tained in the blood exists. 
Lamb’s extensive paper appeared in 1903, in which this particular phe- 
nomenon has been dealt with on the ground of further experiments. 
Lamb and Hanna? found that the rapid death which follows an injection 
of daboia venom is invariably caused by extensive intravascular thrombosis, 
but if the amount of the venom injected is not sufficient to effect this change 
a negative phase of diminished coagulability results, sometimes amounting 
to complete inhibition of clotting, and that this diminished coagulability is 
probably an important factor in the production of some of the symptoms 
which are observed in these cases. 0.0001 gm. of daboia venom per kilo 
injected intravenously into a rabbit causes extensive intravascular thrombosis, 
where 0.0004 gm. is required for a pigeon, when injected subcutaneously. 
This thrombosis may be confined, if the quantity of venom injected has not 
been excessive, to the portal veins, the right heart, and the pulmonary arteries; 
in these cases the blood collected from the other veins, especially from the 
left heart, remains unclotted, or clots only after a long interval of time, when 
the clot is very loose and gelatinous. That it is impossible to produce in- 
creased coagulability and thrombosis by injecting any second quantity of the 
venom after the negative phase of diminished coagulability had once set in 
agrees with the observations made by Martin on the Australian snake venoms. 
Lamb? next tested the coagulating effect of daboia venom upon the citrated 
whole blood. While 1 c.c. of the citrate blood 1 : 100 required 0.0005 gm.., 
the same quantity of the citrate blood 1 : 50 required 0.002 gm. of daboia 
venom to produce coagulation in less than half an hour. 0.0000312 gm. was 

1C. J. Martin. Observations upon fibrin-ferments in the venoms of snakes and the time-relations 
of their action. Jour. of Physiol., 1905, XXXII, 207. 
2Lamb and Hanna. Journ. of Path. and Bact., 1902, VIII, r. 
3Lamb. On the action of the venoms of the cobra (Naja oo and of the daboia (Daboia russellit) 
on the red blood corpuscles and on the blood plasma. Sci. Mem. Officers, Med. and San. 
Depts. Gov. of India, 1903, new series, No. 4. 
