THE PHYSIOLOGY OF POISONING 187 



(0"1 milligramme for the guinea-pig) as when the injection is made 

 in the peritoneum or heneath the skin. 



With the venom of Crotalus heated for half an hour at 75° C, 

 which contains hut very little neurotoxm and has lost all its 

 haemorrhagic properties, 0"5 milligramme introduced directly into 

 the hrain of the guinea-pig only produces transitory and non-lethal 

 effects ; while, if fresh venom be employed, 0"05 milligramme is 

 sufficient to cause death in three hours, with severe haemorrhagic 

 lesions. Now this dose is twenty times smaller than the minimal 

 lethal dose for a subcutaneous injection. 



It is evident that the harmful matter, in the particular case 

 of Crotalus-Yenom, is not the neurotoxin, but an altogether different 

 substance, termed by Flexner and Noguchi hcmnorrliagin, which 

 acts upon the elements of the blood and upon the endothelium 

 of the blood-vessels. 



We shall meet with this substance again in almost all Vipeeine 

 venoms, and shall study it further on. 



