146 Chapter VI 



he kept his tubes containing blood and serum sown with bacilli. As 

 Wagner kept his at 42 43 C., a temperature which corresponds to 

 that of the body of the fowl, I asked M. Gengou to make a series of 

 experiments on the bactericidal power of the plasma and blood 

 serum of fowls on the anthrax bacillus, keeping his tubes at 37 C. 

 [155] The result of his experiments was in complete accord with those of 

 Wagner. Under the conditions that I have just stated the fluids 

 of the fowl are no more bactericidal than they are under the con- 

 ditions maintained in Wagner's experiments. 



In summing up these data on the natural immunity of fowls 

 against anthrax, we are certainly justified in concluding that it is 

 due to the phagocytosis and not to any bactericidal property of the 

 "humours." 



The pigeon is more susceptible than the fowl to the action of 

 the anthrax bacillus, still it manifests a certain degree of resistance 

 against the microbe. After what we have said on the subject of 

 the fowl we need make but few remarks on the pigeon, in spite of 

 the very animated discussions that have taken place on the mechan- 

 ism of its immunity. When Baumgarten was offering a systematic 

 opposition to the part played by phagocytic reaction in immunity, 

 he set his pupil Czaplewski 1 to investigate the resistance of pigeons 

 against anthrax. The results of this investigation were absolutely 

 negative as regards phagocytosis. The latter was said to have no 

 importance in the defence of the organism, which resisted simply 

 because it was impossible for the bacillus to live in the body of 

 the pigeon. I then set myself to study this question 2 , and I was 

 able to demonstrate that the anthrax bacillus is quite capable of 

 keeping alive in the pigeon, that it can develop in its fluids, but 

 that it is unable to defend itself against the aggression of the phago- 

 cytes which ingest it and completely digest it. By isolating the 

 phagocytes that had ingested the bacilli injected into the body of the 

 pigeon, I was able to prove that a number of these bacilli were still 

 alive. The enfeeblement and death of the phagocytes when outside 

 the body allowed the anthrax bacilli again to get the upper hand 

 in this struggle, to develop and to give virulent cultures. The part 

 played by phagocytes in this example of natural immunity was thus 

 placed beyond doubt. 



1 " Untersuchungen ii die Immunitat d. Tauben," Konigsberg, 1889; Ziegler's 

 Beitr. z. path. Anat., Jena, 1890, Bd. vn, S. 49. 



2 Ann. de VInst. Pasteur, Paris, 1890, t. iv, p. 38 ; p. 65. 



