110 THE POISONOUS SNAKES OF INDIA. 



(&) A depressor to nerve cells generally (Lamb and Martin), 

 but insTiflScient to cause paralysis other than that of 

 the vasomotor centre, 



■(2) Agents affecting the constitution of the blood. 



(ft) An anti-clotting ferment. (Fraser and Grunn.) 



(6) ' Hsemolysin," destructive to red blood cells. (Fraser 

 and Gunn.) 



(3) " Hssmorrhagin," damaging the lining membrane of blood 



vessels, is probably present. 



(4) A depressor to cardiac muscle. (Fraser and Gunn.) 



Lamb estimates the virulence of the venom as from three to five 

 -times less than that of cobra venom. Fatalities in the human 

 subject are much more frequent than used to be supposed. Pro- 

 "bably about 20 per cent, of bitten subjects receive a lethal dose in a 

 single bite, but this is largely a matter of conjecture. 



Analysis of the Action of Echis Toxins. 



(1) (ft) A depressor to the vasomotor centre is probably present 

 to explain the reduced blood pressure, and cardiac 

 weakness noted by Fraser and Gunn. The same 

 phenomena are seen in Daboia poisoning which 

 Rogers demonstrated were due to a paralysis of the 

 vasomotor centre, early death from heart failure 

 ensuing. 

 (h) This toxic element accounts for the great depression of 

 vitality seen in l<JcMs poisoning. It is insufficient 

 to cause paralysis. 



[j2) (ft) The anti-clotting ferment accounts for the defective 

 clotting capabilities produced in blood, and in con- 

 junction with (3) for the hasmorrhages ^^'hich are so 

 frequently seen. 



(b) " Hsemolysin in this venom is relatively potent, and 

 hence destruction of red blood cells is a prominent 

 feature. This produces some respiratory embarrass- 

 ment, and contributes to the depression of vitality 

 produced by 1 (6)- 



