Historical sketch on Immunity 531 



means of microbial products. Later, having obtained a deeper know- 

 ledge of various facts concerning natural and acquired immunity, 

 he rallied to the cellular conception and developed it in his report 

 presented to the above Congress in London. Several microbiologists 

 took part in the discussion, and I myself^ was able to communicate 

 certain facts concerning the immunity of guinea-pigs, acquired as the 

 result of vaccination against Gamaleia's vibrio. I chose this example 

 because it presented, according to von Behring and Nissen, the 

 clearest case of a bactericidal property developed during the course 

 of immunisation. I was able to furnish the proof that, in the 

 vaccinated animal, the micro-organism in question, in spite of the 

 great bactericidal power of the blood serum in vitro, remains alive 

 in the animal body for a long time, and that its destruction is effected 

 by the phagocytes, which ingested it alive. In this example I showed 

 that the leucocytes of the exudation, that have ingested vibrios, may 

 still furnish cultures of this organism if they are taken from the body 

 and transferred in hanging drop to the incubator. 



The fact that, even in the case which appeared most to favour 

 the humoral conception of acquired immunity, phagocytes play the 

 principal part, must to many members of the Congress have appeared 

 sufficiently significant. Indeed, several observers who were present 

 at the debates, received the impression that the phagocytic theory 

 had not been overturned by its adversaries. At this period the [555] 

 question of the importance of antitoxins from the point of view 

 of immunity had scarcely been raised. The great discovery made by 

 von Behring and Kitasato was already accepted by everyone; but 

 there was no ground for attributing to it any general importance. 

 In fact, though proved for tetanus and diphtheria, and extended by 

 Ehrlich's beautiful experiments to the vegetable toxins (ricin, abrin, 

 and robin), the antitoxic property of the fluids of the body presented 

 itself rather as a special than as a general phenomenon. It is in this 

 sense that Roux had assigned to it its place in the chapter of 

 immunity. The two diseases, against which antitoxic serums had been 

 discovered, are certainly distinguished from the great majority of 

 infections by the localisation of the micro-organisms and the abundant 

 secretion of their toxins. 



It was only after the London Congress that this question came 

 prominently forward. Von Behring thought that the antitoxic power 

 of the body fluids is generally distributed in all cases of acquired 



^ Ann. de VInst. Pasteur, Paris, 1891, t. v, pp. 465, 634. 



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