234 Chapter VIII 



above summarised lie under the reproach that in them this rule 

 has not been adhered to. 



Since the discovery of Pfeiffer's phenomenon in animals that have 

 been vaccinated against the cholera vibrio, much greater care has 

 been taken to attend to the changes that occur in the animal that 

 enjoys acquired immunity. Wassermann 1 was the first to attempt 

 to apply Pfeifler's discovery to the Bacillus pyocyaneus. With a race 

 of this bacillus rendered more virulent he succeeded in producing a 

 fatal experimental malady in the guinea-pig against which he was 

 able by various methods to vaccinate these animals. 



He thus describes the phenomena observed in the peritoneal 

 cavity of immunised guinea-pigs. Soon after injection the bacilli 

 of blue pus become motionless, then " the rods swell up and melt, 

 like wax in hot water. The formation of granules, such as occur in 

 the cholera vibrio, has been observed but rarely. The process recalls 

 rather that which takes place in experimental typhoid fever, as 

 described by R Pfeiffer. In all cases the phenomenon of solution takes 

 place entirely in the fluid of the exudation, without any co-opera- 

 tion on the part of the leucocytes" (p. 284). We see that we have 

 still to do with a kind of attenuated Pfeiffer's phenomenon, without 

 any granular change, but with an immobilisation of the bacilli. As 

 Wassermann has remained satisfied with the examination of the 

 peritoneal content which, as we know, gives but an imperfect picture 

 of acquired immunity, Gheorghiewsky 2 set himself to study the 

 question more thoroughly under my direction. With this object he 

 vaccinated a series of guinea-pigs with living bacilli of blue pus, 

 a sure method of obtaining acquired immunity. On examining the 

 peritoneal fluid (withdrawn shortly after the injection of the bacilli) 

 of the vaccinated guinea-pigs, he found that the bacilli were motion- 

 less and had undergone a certain degree of agglutination. They were 

 [247] not transformed into granules but became thicker and somewhat more 

 dumpy. These changes are observed during the period of phago- 

 lysis, when only a few scattered leucocytes are to be found in the 

 fluid of the peritoneal cavity. About two hours after the injection 

 of the bacilli the leucocytes begin to reappear in the peritoneal 

 exudation, more especially the microphages, which lose no time in 

 seizing the bacilli, some of which become transformed into granules. 

 A few hours later the exudation, containing a multitude of leucocytes, 



1 Ztschr.f. Hyg., Leipzig, 1896, Bd. xxn, S. 263. 

 8 Ann. de FInst. Pasteur, Paris, 1899, t. xni, p. 298. 



