Artificial Immunity against toxins 351 



vibrio, but these animals, even when most thoroughly vaccinated, were 

 completely non-resistant to the cholera toxin. Von Behring suggested 

 to his pupil Ransom 1 the idea of immunising guinea-pigs, not with 

 microbial cultures living or dead, as had usually been done previously, 

 but exclusively with the fluids of the cultures, deprived of the 

 vibrios by filtration. In order, however, to attain the desired object, 

 it was necessary to prepare fluids sufficiently active to poison the 

 unvaccinated control guinea-pigs with certainty. The results of these 

 investigations confirmed his anticipation, and Ransom soon found 

 himself in possession of guinea-pigs well vaccinated against the 

 cholera poison. He was mistaken, however, in supposing that, in all 

 cases of immunity acquired against Koch's vibrio, we have to do, in 

 the main, with a purely antitoxic immunity. An investigation carried 

 out in the Pasteur Institute 2 , whilst confirming the facts discovered 

 by Ransom, lead to different results as regards their interpretation. 

 It was demonstrated that the immunity against the vibrio is in no [369] 

 way founded on a resistance against its toxin and that we have to 

 do with two very different acquired immunities. The vaccination 

 obtained with the bodies of the micro-organisms induced a refractory 

 condition against infection by the living vibrio, but not the slightest 

 resistance against the toxin. The immunity, on the other hand, 

 which is conferred by the injection of soluble products, deprived of 

 the micro-organisms, is effective not only against the toxin of cholera, 

 but also against infection by the vibrio. When an animal is vac- 

 cinated with cultures, or even with the bodies only of the vibrios, 

 cholera toxin is introduced, but the toxin, under these conditions, is 

 incapable of setting up antitoxic immunity. It would appear that 

 the presence of the vibrios may constitute some obstacle to the pro- 

 duction of this immunity. 



Soon afterwards, Wassermann 3 pointed out that the same rule 

 applies in the case of the Bacillus pyocyaneus. With whole cultures 

 of this bacillus he obtained in guinea-pigs an immunity exclusively 

 against infection, whilst with cultures in a fluid medium, deprived of the 

 bacilli, he was able to vaccinate his animals both against the pyocy- 

 anic toxin and against the infective peritonitis produced by the living 

 micro-organism. The same double immunity could also be obtained 



1 Deutsche med. Wchnschr., Leipzig, 1895, S. 457. 



2 Ann. de Flnst. Pasteur, Paris, 1896, t. x, p. 257. 



3 Ztschr.f. Hyg., Leipzig, 1896, Bd. XXH, S. 312. 



