TOXICITY OF THE BLOOD OF VENOMOUS SNAKES 219 



vipers (Phisalix and Bertrand^), and that the Cobra is relatively 

 little affected by inoculation w^ith its own venom or with that 

 of other GolubriDjE, such as Bungarus, or even of Vipeeid^, 

 such as Vipera russellii. 



This immunity, however, is far from being absolute ; I have 

 killed common snakes [Tropidonotus natrix) with doses of viper- 

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

 Lachesis lanceolatus (from Martinique) with 0'02 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-venom 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 was 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 (Pituophis 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 hssmolytic 

 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 Physiologie, 1894. 



^ Comptes rendus de la Societe de Biologie, July 25, 1903. 



' Journal of Pathology and Bacteriology, May, 1903. 



