CHAPTER XXV 



Pfeiffer's experiments, 1895 — The Buda-Pest Congress — Extracellular 

 destruction of microbes — ^Reaction of the organism against toxins 

 — T)t. Besredka's researches — ^Macrophages — ^The Moscow Con- 

 gress, 1897 — Bordet's experiments. 



Metchnikoff had scarcely recovered from all the 

 emotions caused by his experiments on cholera, which 

 he was stiU studying, when, in 1894, a work appeared 

 by a weU-known German scientist, PfeifEer, bringing 

 out new facts in favour of the extracellular destruc- 

 tion of microbes. 



Whilst studying the influence of the blood serum 

 within the organism and not outside it as his pre- 

 decessors had done, he had found that cholera 

 vibriones, injected into the peritoneum of a guinea- 

 pig vaccinated against cholera, were nearly aU killed 

 in a few minutes and that they then presented the 

 form of motionless granules in the peritoneal liquid. 

 This granular degenescence, said PfeifEer, took place 

 apart from the phagocytes and therefore without 

 their intervention. Metchnikoff repeated the experi- 

 ment at once and ascertained that it was perfectly 

 accurate. 



The complexity of biological phenomena being 

 very great, he fully admitted the possibility of other 

 means of defence in the organism besides that of 

 the phagocytic reaction. However, this new fact 

 disagreed so much with his own observation, and 



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