TOXrCTTY OF THK BLOOD OF VENOMOUS SNAKES 219 



vipers (Phisalix and l^ertrand'), and that the Cobra is relatively 

 little affected l)y inoculation with its own venom or with that 

 of other CoLUBRiD^, such as Bungarus, or even of Viperid^, 

 such as Vipera russellii. 



Tliis immunity, however, is far from being aljsolute ; I have 

 killed common snakes {Tropido)iotiis natrlx) with doses of viper- 

 venom ten times greater than the lethal one for the rabbit, and 

 Lachesis lanceolatus (from Martinique) with 0"0i2 gramme of the 

 venom of Naja tripudians. 



Phisalix,- on his part, has shown that, while it was necessary 

 to inject from 100 to 200 milligrammes of viper-w enoin into other 

 vipers or common snakes, beneath the skin or into the peritoneum, 

 in order to cause death, the introduction of only 2 to 4 milligrammes 

 of this venom into the brains of these reptiles vi^as sufficient to kill 

 them with the same symptoms of intoxication. This dose, how- 

 ever, is only twenty-five to thirty times greater than the lethal one 

 for the guinea-pig. 



The practical lesson to be learnt from the establishment of the 

 foregoing facts is that poisonous snakes of different species must 

 never be placed in the same cage, for these animals sometimes bite 

 each other, and may thus kill one another. 



Simon Flexner and Noguchi ^ have studied the action of the 

 serums of Crotalus, Ancistrodon, and a non-poisonous species, the 

 pine snake {Fituophis catenifer), on the venoms of Naja, Ancis- 

 trodon, and Crotalus. They found that the serum of Crotalus 

 rapidly dissolves the red corpuscles of man, the dog, rabbit, guinea- 

 pig, sheep, rat, pigeon, and horse. 



The serum of the pine snake affects the same red corpuscles, 

 but in a lesser degree. Heating to 58° C. suppresses the hj^emolytic 

 power of these serums, but they can be restored to activity by the 

 addition of a very small quantity of the same serum in a fresh 



' Archives de PJiysiolorjic, 1894. 



- Comjjtes rendics de la Societe de Biologic, July 25, 190H. 



^ Journal of Patlwlogy and Bacferiologi/, May, 1908. 



