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, o.ooi gm. of lachesis 

 venom can coagulate i c.c. of citrate plasma of rabbit in i minute. But if 

 o.ooi gm. of the venom of Cobra or of water-moccasin is previously added to 

 the plasma and then o.ooi gm. of lachesis venom, no coagulation takes place. 

 Such incoagulate mixture clots perfectly if i 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 g m - of lachesis venom and 

 0.007 g m - f 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. 



