142 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 
case, it may be mentioned, the cobra venom was allowed to act for 30 minutes 
upon the plasma before the latter venom was introduced. 
Calmette, who in great part confirms the observations already mentioned 
in this chapter, obtained somewhat different results in regard to a few facts. 
Thus, in speaking of the simultaneous action of an anticoagulating and a 
coagulation-inducing venom, he states that the action of each opposite-acting 
venom is entirely lost by their being mixed together. 0.001 gm. of lachesis 
venom can coagulate 1 c.c. of citrate plasma of rabbit in 1 minute. But if 
0.001 gm. of the venom of Cobra or of water-moccasin is previously added to 
the plasma and then 0.001 gm. of lachesis venom, no coagulation takes place. 
Such incoagulate mixture clots perfectly if 1 c.c. of a 0.5 per cent solution of 
calcium chloride is added. 
It was also stated by Calmette that even the most procoagulating venoms 
prevent coagulation of the blood in vitro when a sufficiently large quantity of 
these venoms is employed. For example, 0.004 gm. of lachesis venom and 
0.007 gm. of daboia venom prevent coagulation of citrate plasma of rabbit. 
This phenomenon was explained by the theory that these viperine venoms dis- 
play a powerful proteolytic action upon coagulated or dissolved fibrin. He 
refers also to the fact that even with a weaker coagulating dose the proteolytic 
action is manifest, for the coagulum once formed is gradually softened and 
finally dissolved, as is usually seen in an experiment with a cube of egg- 
albumin in a typtic digestion. 
In regard to the anticoagulating property of cobra venom and colubrine 
venom in general, Calmette states that it is due to destruction of the fibrin 
ferment by the venom, whereas the viperine venoms are said to attack chiefly 
fibrin itself. 
