Coagulant of the Venom of Echis carinatus. 



189 



Even when, after the injection of a lethal dose of viper venom, clotting- 

 occurs in the heart and great blood-vessels, the ease with which fibrin masses 

 can be recognised in the smaller pulmonary vessels renders it possible 

 readily to distinguish between the effect of injection of thrombin or viper 

 venom and that of a relatively large amount of thrombokinase contained in 

 red-cell stromata or peptone. It is obvious from the effect of injection of 

 viper venom into the blood stream that the coagulant in the venom is a 

 thrombin and not a thrombokinase. 



The Effect of Heat upon Viper Venom. 



The blood coagulant of the venom of the Indian viper, Echis carinatus, is 

 completely destroyed by heating to 75° C. for 10 to 15 minutes.* The 

 following experiments exhibit the coagulant activity of this venom before 

 and after heating : — 



Fibrinogen 

 solution. 



Solution of 

 riper venom 

 1 in 300,000 of 

 - 85-per-cent. 

 NaCl. 



•6-per-cent. 

 CaCL 

 solution. 



- 85-per-cent. 

 NaCl 

 solution. 



"SS-per-cent. 



solution 

 of potassium 

 oxalate. 



Coagulation 

 time (30° C). 



c.c. 



c.c. 



e.c. 



c.c. 



c.c. 





0-2 





0-03 



0-27 





90 minutes. 



0-2 



0-01 



0-03 



0-26 





10 



0-2 



03 



0-03 



-24 







2 



o-io 



0-03 



17 





■* 



0-2 



30 



0-03 







3 



0-2 



0-30* 



0-05 







53-60 „ 



0-2 







0-27 



03 



3 hours. 



2 



o-oi 





0-26 



0-03 



16 minutes. 



2 



-03 





0-24 



0-03 



10 



0-2 



o-io 





0-17 



0-03 



7 



0-2 



0-30 







0-03 



•* 



2 



0-30* 







03 



60 



* Heated to 75° for 10 minutes. 



It will be seen that viper venom, even when present to the extent of only 

 1 part in 15,000,000, is capable of coagulating in ten minutes at 30° G. a 

 liquid containing approximately the same concentration of fibrinogen as- 

 normal rabbit's plasma. When heated, however, its coagulant action rapidly 

 disappears. 



It is obvious from the effect of heating that the coagulant of viper venom 

 cannot be regarded as thrombokinase as Mellanbyf has suggested. Its 

 behaviour in respect of heat shows it to be a thrombin. 



VOL. LXXXVII. — )!. 



* C. J. Martin, 1905, loc. cit. 

 t J. Mellanby, loc. cit., p. 467. 



A 1914 I 



