EFFECTS OF SNAKE VENOM ON COAGULABILITY OF THE BLOOD 137 



the quickest and firmest coagulation, while the doses above these quantities 

 reduced or annihilated the coagulability. Thus 0.003 g^- stiU produced 

 a loose coagulation, while 0.004 gn^- doses and upwards (tried up to o.oi 

 gm.) did not produce further coagulation. 



The venoms of the following snakes possess coagulating power in the 

 order given: 



Crotalin^: Lachesis lanceolatus (Bothrops), Martinique; L. urutsu (neu- 

 wiedii), Brazil; L. jararaca, Brazil; L. jararacussu, Brazil; 

 L. flavoviridis s. Trimeresurus riukiuanus, Japan. 



ViPERiN^: Vipera russellii (daboia), Burma. 



As to the mechanism of the coagulating action of the venom, Noc is inclined 

 to consider it to be a part of activation of the plasmase (or fibrin ferment) by 

 venom. Thus, venom may act something like some organ extracts in bring- 

 ing the zymogenic form of fibrin ferment (protothrombin or thrombogen) 

 into an active state, although no definite processes are yet known. He does 

 not, however, exclude the possibility that venom contains a veritable fibrin 

 ferment. 



The rapidity with which coagulation of the citrate or oxalate blood takes 

 place under the influence of these venoms renders it improbable that the 

 destruction of the red corpuscles has any relation to this phenomenon. At 

 any rate, the venoms of Lachesis do not alter the corpuscles for some time 

 after they are mixed. 



Noc also found that the venoms of Naja tripudians, Naja nigricollis, and 

 Bungarus cosruleus were devoid of coagulating property on the whole blood 

 or the plasmas which were rendered incoagulable by these anti-clotting salts 

 or leech extract. This agrees with the negative observations of Lamb with 

 the venoms of Cobra and kraits. 



The peculiar phenomenon that a too large amount of lachesis venom, 

 when mixed in vitro, produces incoagulabihty of the blood is attributed by 

 Noc to the fibrin-dissolving property of the venom. That crotalus venom 

 in a strong concentration in vitro results in the same fluidity of the blood 

 has been shown by S. Weir Mitchell and Reichert. 



Martin found that the coagulating property of the Australian snake venoms 

 disappeared after heating to 80° C.^ for half an hour, and Lamb found the 

 same result for daboia venom after heating to 75° C. during half an hour; 

 finally, Noc, for the lachesis venom, found that there was much weakening 

 at 58° C, and complete destruction at 80° C. maintained for the same period 

 in a sealed tube. Noc further found that alcohol precipitates, but does not 

 destroy, the coagulating principle of the lachesis venom. 



In 1905 Martin ^ made further contributions to our knowledge of the 

 coagulating constituents of the venoms of Pseudechis porphyriacus, Notechis 

 scutatus, Echis carinata, and Daboia russellii. Of these four venoms that of 



' A weaker solution, viz, o.i per cent, is completely destroyed at 75° C. for 10 to 15 minutes. 

 2 C. J. Martin. Observations upon fibrin ferments in the venoms of snakes and the time-relation of 

 their action. Jour, of Physiol., 1905, XXXII, 207. 



