242 VENOMS 



means of successive inoculations with heated venoms, to confer on 

 animals a certain degree of resistance to doses invariably lethal to 

 the controls. 



From 1894 onwards, the investigations pursued simultaneously 

 at the Paris Natural History Museum, by Phisalix and Bertrand, 

 upon viper-venom, and at the Paris Pasteur Institute by myself, 

 upon that of the cobra, and subsequently upon other venoms of 

 various origins, led to much more definite results. These investi- 

 gations show, on the one hand, that by vaccinating guinea-pigs 

 or rabbits, and taking certain precautions, it is possible to confer 

 upon these small animals a really strong immunity to venom ; on 

 the other hand, that animals vaccinated against cobra-venom are 

 perfectly immune to doses of viper-venom or that of other snakes 

 {Bungarus, Cerastes, Naja haje, Pseudechis) certainly lethal to the 

 controls ; and lastly, that the serum of the vaccinated animals 

 contains antitoxic substances capable of transmitting the immunity 

 to other animals} 



According to Phisalix and Bertrand, who, as we have stated, 

 experimented only with viper-venom, the best method of vac- 

 cinating the guinea-pig consists in inoculating a dose of 0'4 milli- 

 gramme of this venom heated for five minutes at 75° C, and, 

 forty-eight hours afterwards, the same dose of non-heated venom. 

 The latter is always lethal to the control guinea-pigs in from six 

 to eight hours. 



Vaccination against cobra-venom, which is much more toxic, 

 is most surely effected by the method recommended by me, which 

 consists in at first injecting small doses of this venom mixed with 

 an equal quantity of a 1 per cent, solution of hypochlorite of 

 lime. By degrees the quantity of venom is increased and that of 

 the hypochlorite progressively diminished, and the injections are 



' Comptes rendus de I'Academie des Sciences, t. 118, February, 1894, p. 356; 

 March, 1694, p. 720; Comptes rendus dc la Socicie dc Biologic, February, 1894, 

 pp. Ill, 120 ; Archives de Physiologic, July, 1894 ; Annalcs de Vlnstitut Pasteur, 

 May, 1894, p. 275, April, 1895, p. 225. 



