Artificial immunity against toxins 357 



med. WchnscJir., Leipzig, 1890, S. 1113) formulates his first thesis as 

 follows : " the blood of a rabbit immunised against tetanus possesses 

 the property of destroying tetanus toxin/' This idea of destruction, 

 which would remove all toxic power from the poison, would naturally 

 present itself to the mind and w r as at once accepted by a great many 

 observers, but the numerous facts now accumulated on the subject [375] 

 will not allow us to accept a real destruction of toxins by antitoxins. 

 Tizzoni 1 was one of the first to point out certain contradictions 

 between the theory of destruction and the phenomena produced in 

 animals injected with tetanus toxin and antitoxin. Buchner 2 also 

 brought forward new facts w r hich led him to conclude that antitoxin, 

 instead of acting directly on the toxin, exerts its influence exclu- 

 sively on the living elements, thus protecting the animal against 

 intoxication. Amongst the arguments advanced by the Munich 

 observer, the principal one is drawn from the different action of 

 mixtures of tetanus toxin and antitetanus serum on various species 

 of animals. It has been clearly shown that the guinea-pig is more 

 susceptible to tetanus than is the mouse. In poisoning with tetanus 

 toxin it requires an absolutely larger quantity of toxin to kill the 

 guinea-pig than to kill the mouse. But if we take into account the 

 weight of these animals, the conditions change completely. Thus, to 

 cause a fatal tetanus in a guinea-pig, which weighs twenty times more 

 than a mouse, we need only inject into the former a dose at most ten 

 times greater than that necessary to produce fatal intoxication in the 

 mouse. Buchner prepared a mixture of tetanus toxin and anti- 

 tetanus serum which, in the mouse, produces no tetanic phenomenon 

 or only sets up feeble and transient symptoms. According to the 

 theory of direct action, we must assume that in this mixture the 

 toxin is completely or almost completely neutralised by the antitoxin 

 of the serum. But when Buchner injected the same quantity of mix- 

 ture into guinea-pigs, without increasing it in proportion to the greater 

 weight of these animals, he produced a tetanus of the most marked 

 character. There has, consequently, remained in the mixture a 

 sufficient amount of free toxin, whose tetanigenic action is mani- 

 fested in the guinea-pig, an animal, as we have seen, more susceptible 

 than the mouse. Buclmer's experiment has been verified by several 

 observers. Roux and Yaillard 3 carried out others which afford 



1 JBerl. klin. Wchnschr., 1893, S. 1266. 



2 Miinchen. med. Wchnschr., 1893, S. 480. 



3 Ann. de VInst. Pasteur, Paris, 1894, t vin, p. 725. 



