Facts bearing on acquired immunity 219 



and give rise to Pfeiffer's phenomenon. If this hypothesis be correct, 

 the suppression of phagolysis would result in the absence of the trans- 

 formation of the vibrios into granules. It is not a difficult matter 

 to verify this hypothesis as we have a means of preventing phago- 

 lysis or at least of reducing it very considerably. Issaeff 1 , in an 

 investigation carried out in Pfeifier's laboratory, demonstrated that 

 an intraperitoneal injection of physiological salt solution, broth, 

 urine, etc., reinforces the leucocytes and brings them up in large 

 numbers into the peritoneal cavity. It is easy to foresee that such 

 an injection would serve to diminish the intensity of the phagolysis. 

 In fact, if we first inject a few cubic centimetres of physiological salt 

 solution or of fresh broth into the peritoneal cavity of a guinea-pig, 

 and if, on the following day, we repeat the same operation, we shall 

 find that after the second injection phagolysis is much less powerful 

 than after the first. Pierallini, who repeated these experiments, 

 observed that the phagocytosis of the coloured granules is much 

 more complete in the guinea-pigs that were treated by a preliminary 

 injection into the peritoneal cavity. The amount of fibrin on the 

 omentum is in this case much less, and the phenomena as a whole 

 show that in these guinea-pigs the damage to the leucocytes is very [231] 

 considerably attenuated. 



We have been able to demonstrate that in the case where phago- 

 lysis is thus diminished, Pfeiffer's phenomenon is not produced or is 

 manifested in a very feeble degree. If the experiment succeeds, the 

 fluid taken from the peritoneal cavity of a guinea-pig prepared the 

 day before and then injected with a culture of cholera, is opaque 

 and thick, like pus. It contains a mass of leucocytes in good con- 

 dition, a large number of which gorge themselves in a few minutes 

 with a number of vibrios. The plasma of this exudation contains 

 few vibrios, and these retain their normal form and do not exhibit, 

 save exceptionally, a granular change. A little later there remain 

 no free vibrios ; they are all contained within leucocytes. Pfeiffer 2 

 declared himself against the facts I have just summarised, because he 

 was never able to prevent the granular transformation of the vibrios, 

 in spite of the preparatory injection of sodium chloride. Abel 3 , who 

 repeated the experiments, expressed an intermediate view: in guinea- 

 pigs prepared by injections the day before, he observed that one 



1 Ztschr.f. Hyg., Leipzig, 1894, Bd. xvi, S. 287. 



2 Deutsche med. Wchnschr., Leipzig, 1896, S. 120. 



3 Centralll. f. Bakteriol u. Parasitenk., I te Abt, Jena, 1896, Bd. xx, S. 761. 



