Mechanism of immunity against micro-organisms 185 



papers, we 1 expressed the opinion that a portion at least of the bacteri- 

 cidal power might come from substances that had escaped from the 

 leucocytes during the preparation of the defibriuated blood and of 

 the blood serum. This hypothesis remained for several years un- 

 noticed, but later several observers have, quite independently, arrived 

 at the conclusion that alexine is nothing but a leucocytic product. 

 Denys and Havet 2 were the first to show that exudations rich in 

 white corpuscles exhibited a bactericidal power much higher than that 

 of the corresponding blood serums. Shortly afterwards H. Buchner 3 

 showed the same thing on comparing the bactericidal power of 

 exudations rich in leucocytes with the blood serum of the same 

 animals. As this property disappeared from both fluids after they 

 had been heated to 55 C., Buchner concluded that the bacteri- 

 cidal substance of the exudations must be identical with the alexine 

 of the blood serum. Several other observers, amongst whom Bail, 

 Schattenfroh, Jacob and Lowit, may be cited, obtained results more 

 or less in accord with the above, though obtained by different 

 methods, so that it has now for some time come to be recognised 

 that the leucocytic origin of the alexines is generally accepted, 

 especially since Jules Bordet 4 , in an investigation carried out in my [196] 

 laboratory, arrived at the same result from various very demon- 

 strative experiments. 



Nevertheless several authoritative voices have been raised against 

 this interpretation of the facts. R. Pfeiffer especially, with his school, 

 has pronounced against the leucocytic origin of the bactericidal sub- 

 stance found in the blood serum. Pfeiffer and Marx 5 and Moxter 6 

 have insisted on the fact that the fluids of exudations rich in leuco- 

 cytes are often much less bactericidal than is the serum of the blood 

 of the same animals. 



For some years, struck by the marked difference between the 

 phagocytic function of the macrophages and that of the microphages, 

 I have thought that the contradictory results of the observers cited 

 might be explained by some difference in the nature of the leucocytes 

 of the various exudations and of the blood which served for the 



Ann. de llnst. Pasteur, Paris, 1889, t. m, p. 670. 



2 La Cellule, Lierre et Louvain, 1894, t. x, p. 7. 



3 Milnchen. med. Wchnschr., 1894, S. 717. 



4 Ann. de VInst. Pasteur, Paris, 1895, t. ix, p. 462. 

 6 Ztschr.f. Hyg., Leipzig, 1898, Bd. xxvn, S. 272. 



6 Deutsche med. Wchnschr., Leipzig, 1899, S. 687. 



