THE PHYSIOLOGY OF POISONING 187 
(0°1 milligramme for the guinea-pig) as when the injection is made 
in the peritoneum or beneath the skin. 
With the venom of Crotalus heated for half an hour at 75° C., 
which contains but very little neurotoxin and has lost all its 
hemorrhagic properties, 0°5 milligramme introduced directly into 
the brain 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 hemorrhagic 
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-venom, is not the neurotoxin, but an altogether different 
substance, termed by Flexner and Noguchi hemorrhagin, 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 VIPERINE 
venoms, and shall study it further on. 
