19i VENOMS 



as that of the Lachesis, with anticoagulant venoms such as that of 

 the Cobra or of Ancisirodon, it is found that these mixtures, when 

 properly effected, become neutral, so that the respective effects of 

 the component venoms are entirely destroyed. Assuming, for 

 instance, that 1 milligramme of Lachesis-\enom coagulates in two 

 minutes 1 c.c. of 1 per cent, citrate rabbit-plasma, if we add to the 

 plasma firstly 1 milligramme of Ancistrodon-, or 1 milligramme of 

 Co&?a-venom, and then 1 milligramme of Lachesis-\enom, the 

 plasma remains non -coagulated, yet coagulates perfectly on the 

 subsequent addition of 1 c.c. of a ^ per cent, solution of chloride 

 of calcium. 



There is, therefore, a real antagonism between the actively 

 coagulant substance contained in certain Viperine venoms and 

 the anticoagulant substance comprised in the venoms of certain 

 other ViPERiD^ {Ancistrodon), belonging to the subfamily Cro- 

 TALIN^, and in those of all the Coltjbrid^. 



The conclusion to be deduced from the foregoing facts is that 

 the venoms of CoLUBRiDiE and those of certain Viperid^ are 

 decidedly anticoagulant, while the majority of the venoms of 

 ViPERiD^, on the contrary, possess strong coagulant properties, 

 even when mixed with blood in infinitesimal doses. 



The question therefore arises why these coagulant Viperine 



venoms suppress the coagulability of the blood when mixed with it 



■in vitro in strong doses (for example, in doses beginning from 



4 milligrammes of Lachesis-wenom., or 7 milligrammes of the venom 



of Vipera russellii for 1 c.c. of 1 per cent, citrate rabbit-plasma). 



The explanation of this apparently contradictory phenomenon 

 is furnished by the intense proteolysis that these Viperine venoms 

 exert upon fibrin, in solution or coagulated. This proteolysis 

 actually manifests itself with weak coagulant doses, for the compact 

 clots formed at the outset soon become soft and then dissolve, 

 like a cube of egg-albumen in an experiment in artificial digestion 

 by trypsin. We shall revert to the subject later on. 



