Immunity against pathogenic micro-organisms 151 



is readily destroyed by defibrinated dog's blood. But, as this result 

 was not in accord with my observations 1 that the bacillus is easily 

 cultivated in dog's blood, and as several observers, especially 

 Lubarsch 2 , had arrived at conclusions opposed to those of Nuttall, 

 systematic researches were made for the purpose of solving this 

 complicated problem. Denys and Kaisin 3 sought to remove the 

 objections formulated against the explanation of the immunity of 

 the dog as due to the bactericidal property of its blood by affirm- 

 ing that this power, which is absent in the inoculated dog, develops 

 whilst the animal is under the influence of the bacillus. Immunity 

 is reduced, then, in this case to the establishment of a new 

 property in the fluids during the course of the struggle of the 

 organism against the inoculated bacillus. Xone of the observers, 

 however, who have repeated these experiments, e.g. Lubarsch 4 and 

 Bail 5 , were able to confirm the results of the Belgian observers. 

 Denys himself, indeed, having resumed this study with Havet 6 , 

 had to reject the conclusions of his former work executed in 

 collaboration with Kaisin. He is persuaded that their error was 

 due to the fact that in their experiments in vitro, the living leuco- 

 cytes ingested the bacilli and prevented their development. As the 

 result of these new researches Deuys and Havet have come to the 

 conclusion " that the main, the predominating part of the bactericidal 

 power of the dog's blood must be ascribed to the leucocytes acting as 

 phagocytic elements" (loc. cit. p. 15). 



As a result of the investigations I have summarised the conclusion 

 is forced upon us that the natural immunity of the dog from anthrax 

 is a function of the phagocytes. In presence of this uniformity of the 

 experimental results it becomes very important to make a more pro- 

 found study of the phenomena that manifest themselves during the 

 destruction of the bacilli by the phagocytes of the dog. What are the 

 phagocytic elements which play the principal part in this struggle, 

 and by what means do they attain this result ? Gengou 7 undertook a [161] 



1 Ann. de Vlnst. Pasteur, Paris, 1887, t. I, p. 43. 



2 " Untersuchimgen ii. die Ursachen der angeborenen u. erworbenen Immunitat," 

 Berlin, 1891, S. 111. 



3 La Cellule, Lierre et Lou vain, 1893, t. ix, p. 337. 



4 "Zur Lehre von den Geschswiilsten und Infectionskrankheiten," Wiesbaden, 1899. 



5 CentralU. f. Bacterial, u. Parasitenk., l te Abt., Jena, 1900, Bd. xxvn, SS. 10 

 und 517. 



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



7 Ann.de Vlnst. Pasteur, Paris, 1901, t. xv, p. 68. 



