528 Chapter XVI 



presence of a special substance of albuminoid nature, to which he gave 

 the name of alexin. Buchner 1 combatted with success the idea that 

 I had expressed, according to which the bactericidal power of the 

 body fluids is reduced in great part to a plasmolytic action of the 

 blood serum upon certain micro-organisms. It cannot be denied that 

 my hypothesis is only very partially applicable, and that the larger 

 share in the bactericidal action of the body fluids belongs to the 

 alexins. Buchner also made the study of this action more easy by 

 the demonstration that the red blood corpuscles of a foreign species 

 undergo, under the action of the blood and of the serums, a globu- 

 licidal action comparable to that which occurs in the case of micro- 

 organisms. 



Whilst Fliigge, von Behring and many others of the old partisans 

 of the bactericidal theory of the body fluids abandoned it more or 

 less completely as an explanation of immunity, Buchner remained 

 faithful to it and tried, aided by the collaboration of his pupils, as far 

 as possible to defend it. 



In France this humoral theory was adopted chiefly by Bouchard 2 

 and his pupils, amongst whom I must cite more particularly Charrin 

 and Roger. They sought to confirm it by personal researches, the 

 greater part of which were carried out upon the bacillus of blue 

 pus. These investigators studied it especially in relation to acquired 

 immunity. A comparison of the mode of development of the pyo- 

 cyanic bacillus in the serum of susceptible animals and of vaccinated 

 animals of the same species, convinced them of the great importance 

 of the action of the body fluids. In cases where these fluids were 

 found to be incapable of killing the micro-organisms they exerted 

 over them an injurious influence, either by attenuating their virulence, 

 [552] or by producing more or less important modifications in their forms 

 and functions. The essential cause of natural or acquired immunity 

 was always attributed by Bouchard's school to the property of the 

 body fluids. The phagocytes were said to intervene only secondarily, 

 either to carry off the dead bodies of the micro-organisms, or to 

 ingest the bacteria, rendered inoffensive by the humoral action. 



The humoral theory of immunity, with some slight modifications, 

 spread very generally into every country, and many investigators 

 accepted it without reserve. But certain observers ventured to run 

 counter to the general current and raised objections of principle 



1 CentralU.f. Bakteriol. u. Parasitenk., Jena, 1890, Bd. vni, S. 65. 

 1 "Les microbes pathogenes," Paris, 1892. 



