Historical sketch on Immunity 529 



against the theory of the bactericidal power of the fluids of the 

 body. After the principal facts established by the partisans of this 

 theory had been confirmed, it was asked whether the phenomena 

 of the destruction of micro-organisms observed in vitro are really 

 equivalent to those produced in the refractory animal. A glance 

 at the data brought together with so much zeal was sufficient to 

 demonstrate that this parallelism does not exist The blood of 

 animals susceptible to certain micro-organisms was found to be 

 bactericidal for these organisms, whilst that of refractory animals was 

 incapable of destroying them. It is useless to cite examples, so 

 numerous are they. On the other hand, the bactericidal power of 

 the body fluids, so marked for certain pathogenic organisms such as 

 the anthrax bacillus and especially the cholera vibrio and the typhoid 

 coccobacillus, is insignificant or nil as regards many bacteria against 

 which refractory animals are not wanting. 



All these facts throw doubt on the predominating part played in 

 immunity by the bactericidal power of the body fluids. Lubarsch 1 

 attacked the humoral theory, showing by a great number of experi- 

 ments that animals whose fluids are very bactericidal in vitro are 

 very susceptible to a much smaller quantity of bacteria of the same 

 species introduced into the body. Thus, the defibrinated blood and 

 the blood serum of rabbits destroy a large number of bacteria in 

 a very short time, whilst the rabbits themselves contract fatal 

 anthrax after the introduction of a small number of these micro- 

 organisms into the blood vessels. This contradiction cannot be\[553] 

 explained except by the profound changes which the blood must] 

 undergo outside the body. Facts of the same nature have been| 

 shown for the anthrax of rats by Hankin, Roux, and ourselves, as 

 described in Chapter VL 



The International Congress of Medicine, assembled at Berlin in 

 1890, was the first occasion on which I spoke publicly of the 

 new theories of immunity. In the addresses given at the general 

 meetings, leaders of medical science in several countries summed up 

 their opinion on this question. Koch 2 , in his memorable report, 

 declared that the new acquisitions had destroyed the basis of the 

 theory of phagocytes, and that consequently it must give place 

 to the humoral theory of immunity. Bouchard took up a more 

 conciliatory position, but, according to him, the bactericidal power of 



1 Centralblf. Bakteriol. u. Parasitenk., Jena, 1889, Bd. vi, SS. 481, 529. 



2 " Ueber bacteriologische Forschung," Berlin, 1890. 



B. 34 



