Artificial immunity against toxins 377 



animals. We have already cited Roux and Vaillard's experiments 

 which demonstrated that even animals which have been previously 

 subjected to vaccinal inoculations against certain micro-organisms, 

 exhibit a hypersusceptibility to mixtures of toxins with antitoxins. 



In view, then, of this complexity of the phenomena of acquired im- 

 munity against toxins, it would be very important could we leani 

 something of the nature and origin of antitoxins. Unfortunately, 

 as we shall see, these questions are, as yet, far from having received 

 a satisfactory solution. 



Struck by the fact that antitoxins exert a specific action on the 

 toxin which has been employed in the treatment of the animals that 

 produce the serum, certain observers have sought an explanation on [396j 

 the hypothesis of a transformation of toxin into antitoxin. We have 

 already seen that antitoxic action is not always absolutely specific ; 

 we have serums which prevent intoxication by various kinds of 

 poisons, e.g. antitetanus serum, which is active against both tetanus 

 toxin and snake venom. There is, however, a great quantitative 

 difference between the influence of the antitoxin on the toxin with 

 which the animals have been prepared and on a difierent poison. 

 Thus, in the example just cited, in order to. neutralise snake, venom 

 it is necessary to use a much larger quantity of antitetanus serum 

 than against the toxin of tetanus. The classical example of the 

 specific influence of antitoxins is the absolute inactivity of anti- 

 diphtheria serum against tetanus and the same non-effect of anti- 

 tetanus serum against diphtheria intoxication. The most simple 

 explanation of this specificity of action appeared to be the sup- 

 position that each antitoxin contains a part of the corresponding 

 toxin, modified by the organism of the animal. H. Buchner^ advo- 

 cates this hypothesis. I myself^ said "that it is probable that 

 antitoxins, at least in great part, represent a modification of the 

 toxins prepared by certain cells in the animal body; this product 

 is then poured into the blood.'' This view was stated as a " pro- 

 bability" and consequently contains no affirmation in the least 

 definitive. I was, therefore, quite prepared to give it up under 

 the weight of the crushing criticism formulated by several very 

 distinguished observers. It was objected ; first, that antitoxin is 

 produced by animals in very great disproportion to the quantity of 

 toxin they have received ; secondly, that the animals which receive 



1 MUnchen. med. Wchnschr., 1893, S. 380. 



2 '' Immunitat " in Weyl's " Haiidbuch der Hygiene," Jena, 1897, Bd. ix, S. 43. 



