190 VENOMS 



phenomenon may be that the doses, which are, weak but sufficient 

 to produce the disintegration of the leucocytes, injure the red 

 corpuscle in only a slight degree, while the stronger doses are 

 equally destructive to the two kinds of blood corpuscles. 



It follows that we must understand that there are two phases 

 in the action of venoms : one negative, when the dose absorbed 

 does not injure the leucocytes ; the othev positive, when the leuco- 

 cytes are destroyed. 



If the blood of the dog remains non-coagulable when mixed 

 with doses of venom which, on the contrary, are actively coagulant 

 for the blood of the rabbit, the reason would be that the leucocytes 

 of these animals are not equally resistant to venom. 



This conception, however, does not conform to the facts that 

 I have myself observed. I have always found that viper-venom, 

 mixed with citrate- or oxalate-plasma of the dog, rabbit, or horse, 

 coagulates these various plasmas when the venom is in weak doses, 

 while with strong doses coagulation is not produced. To be quite 

 accurate, it should be stated that the quantity of venom necessary 

 to render the plasma of the dog, or of the horse, non-coagulable 

 is less than that which must be employed in the case of the plasma 

 of the rabbit. 



I have caused Noc to take up anew the study of this question 

 in my laboratory, with venoms of nine different origins, and 

 I here give a resumA of the results of his researches.^ 



I. Coagulant Venoms. 



The venoms of VipbriDjE studied range themselves as follows 

 according to their coagulant power : — 



Crotalin-e : Lachesis lanceolatus (Fer-de-lance, Martinique). 



Lachesis neuwiedii (Urutu, Brazil). 



Lachesis mutus (Bushmaster, or Surucucu, Brazil). 



Lachesis flavoviridis (Japan). 

 ViPBRiN^ : Vipera russelUi (Daboia, India). 



' 4^ivnales de I'Institui, Pasteur, June, 1904, 



