Artificial immunity against toxins 347 



scale. Vaccination is commenced with toxins modified by heat or by 

 chemical substances. The diphtheria and tetanus toxins, those most 

 employed in the serotherapeutic industry, are subjected to various 

 degrees of heat. Frankel 1 was the first to make use of this method 

 for vaccination against diphtheria, and Vaillard 2 for vaccination 

 against tetanus. It consists in introducing large doses of filtered 

 cultures, heated to progressively lower degrees of temperature, 60, 

 55, 50 C., and then giving gradually increasing quantities of filtered 

 cultures whose toxicity is unaltered. This method is very convenient 

 for small animals, but for large mammals it is greatly simplified by in- 

 jecting for a certain period toxins heated to 60 C., and, later, replacing 

 these by unmodified toxin. 



Phisalix and Bertrand 3 applied an analogous method to the 

 vaccination of the guinea-pig against the venom of the viper. This 

 poison, which resists much higher temperatures than do the tetanus 

 and diphtheria toxins, received a preliminary heating to 80 C. in 

 order that it might be inoculated without danger into small animals. 

 Under these conditions it confers a certain immunity, but even when 

 heated to 80 C. it, in many cases, still remains sufficiently active to 

 produce fatal results. For this reason, in the vaccination of animals 

 for the preparation of antivenomous serum on a large scale, Calmette 

 had recourse to another method, that of attenuating the venom by [365] 

 means of chemical substances. 



Von Behring and Kitasato 4 were the first to make use of iodine 

 trichloride in the vaccination of animals against the toxins of tetanus 

 and diphtheria. In their early experiments this substance was injected 

 before the toxins were introduced. Later, the mixture was made 

 in vitro and then injected into the animals. Roux devised another 

 method which had the advantage of being simple, certain, and easily 

 employed, for which reason it was soon introduced into commercial 

 and scientific practice. It consists in the injection of mixtures of the 

 tetanus or diphtheria toxins with Lugol's iodo-ioduretted solution. 

 The iodine, in small doses, instantly neutralises or modifies these 

 poisons and is itself borne well, even by small animals. By employing 

 progressively increasing doses of these mixtures, in which the amount 



1 Berl. klin. Wclmschr., 1890, No. 49. 



2 Ann. de Ilnst. Pasteur, Paris, 1892, t. vi, p. 225. 



3 Compt. rend. Acad. d. sc., Paris, 1894, t. cvm, p. 283 ; Compt. rend. Soc. de 

 liol, Paris, 1894, p. 111. 



* Deutsche med. Wchnschr., Leipzig, 1890, SS. 1145, 1245. 



