SNAKE TOXINES. 215 



minutes in a control experiment. The only organ that had an 

 energetic protective action was the brain. It retarded the death 

 of one animal for nineteen hours, while another survived twice 

 the amount of a lethal dose which killed an animal in five 

 hours in the control experiment. Extracts prepared from other 

 organs did no more than retard the action to some extent. The 

 hsemolysine did not enter into combination in the slightest 

 degree. 



Mode of Action of Snake Venoms. Snake venoms, as we shall 

 subsequently show more fully, contain, in addition to the two 

 agents that act specifically upon the corpuscles of the blood, two 

 poisonous constituents, neurotoxine and hwmorrhagine. Since 

 the latter component manifests its activity chiefly in crotalus 

 venom, and is almost entirely absent in the case of cobra venom, 

 the 'following description deals primarily with the neurotoxine of 

 the cobra and other snakes. 



This poison is extraordinarily virulent. One drop of CAL- 

 METTE'S first glycerin extract killed rats and pigeons in less than 

 an hour, and hens and rabbits in a somewhat longer time. 



MARTIN l found the lethal dose of the poison of Hoplouephalus 

 curtus (the tiger snake) for rabbits to be 0'03 mgrm. per kilo. 

 This poison is stated to be the most active. 



VALENTIN found the lethal dose of the poison of Vipera aspis 

 for the frog to be 0'5 mgrm. 



FLEXNEK and NOGUCHI (loc. cit.) found that guinea-pigs were 

 killed by a dose of 0*3 mgrm. of the venom of the copper-head 

 snake (Ancistrodon contortrix). 



CALMETTE 2 stated that in the case of a cobra that had not 

 taken any food for eight months the virulence of the venom had 

 considerably increased. While 0'7 mgrm. of the dry poison was 

 originally required to kill a rabbit of 1,700 grms., 0-25 mgrm. 

 was sufficient after two months, and 0*1 mgrm. after the death of 

 the snake (for a rabbit of 2,000 grms.). Similar results were 

 obtained in the case of another cobra during three months. 



A comparative determination of the toxicity of different snake 

 poisons gave the following values : 



1 Martin and Cherry, " The Nature of the Antagonism between Toxines 

 and Antitoxines," Proc. Roy. Soc., Ixiii., 420, 1898 ; Martin, "Relation of 

 the Toxine and Antitoxine of Snake Venom," ibid., Ixiv., 88, 1899. 



2 Calmette, " Contrib. a 1'etude des venins," Ann. Past., ix., 225, 1895. 



