ARTIFICIAL IMMUNIZATION 225 
Phisalix ' altered the venom of viper by alternating currents of high fre- 
quency and found the modified venom to act as a protective vaccine. 
Phisalix and Bertrand next succeeded in separating the toxic and the 
immunizing principles of the venom of viper by passing a 1 : 5,000 solution 
through the porcelain filter. ‘Toxicity was almost completely absent from 
the filtrate, but the echidno-vaccine was still contained in it, as the injec- 
tion of the filtrate into guinea-pigs rendered the animals refractory to 
the effects of two minimal lethal doses of fresh unfiltered venom given 48 
hours later. 
Calmette,? later, dissented from the above statement, as he found that 
filtration simply reduced the toxicity of venom to two-fifths of its original 
power, but if proteins were removed by heat-coagulation before the filtration, 
practically all passed through. The vaccination reported by Phisalix and 
Bertrand he looks upon as merely an early stage of the usual form of experi- 
mental immunity. 
PASSIVE IMMUNITY — ANTIVENINS. 
Since the successful therapeutic application of the diphtheria antitoxin the 
future of the problem of immunity has assumed quite a new aspect. The 
discovery of Behring and Kitasato, that the protective principle developed 
in the animal successfully immunized against a particular toxin can be trans- 
mitted into a normal animal and confer upon the latter the power to resist 
the otherwise lethal action of the toxin in question has now been brought 
into the study of venom immunity. Naturally the basis of such possibility 
in venom is dependent on whether or not the animals can be made actively 
immune by the sublethal inoculation of venom. This has been established 
affirmatively by Sewall, Kaufmann, Phisalix, and Bertrand in their pre- 
ventive inoculation, either with unmodified or heated venoms. 
The first observation upon the antitoxic property of the blood of animals 
immunized to venom was made by Phisalix and Bertrand.* They found 
that when guinea-pigs were killed 48 hours after vaccination with the echidno- 
vaccine, their serum or defibrinated blood mixed with the venom and injected 
into the peritoneal cavity of other guinea-pigs enabled them perfectly to resist 
the action of the venom. 
In the meanwhile Calmette commenced to install the results of his famous 
series of studies bearing on the production of antivenin, with such progress 
that he finally succeeded in introducing the antivenin to preventive and 
therapeutic applications in the treatment of snake bite. He‘ first employed 
the usual laboratory animals, such as rabbits and guinea-pigs, to immunize 
with cobra venom. 

1 Phisalix. Atténuation du venin de vipére par les courants 4 haute fréquence; nouvelle méthode de 
vaccination contre le venin. Compt. rend. d. 1. Soc. d. Biol., 1896, 10 série, III, 233. 
2 Calmette. Serpents’ venom and antivenomous serum. Brit. Med. Jour., 1896, II, 1025. 
8 Phisalix and Bertrand. Sur la propriété antitoxique du sang des animaux vaccinés contre le venin 
de vipére. Compt. rend. d. l’Acad. d. Sci., Paris, 1894, CXVIII, 356. 
* Calmette. L’immunisation artificielle des animaux contre le venin des serpents, et la thérapeutique 
expérimentale des morsures venimeuses. Compt. rend. d. 1. Soc. d. Biol., 1894, 10 série, I, 120. 
