Pfeiffer's Phenomenon 



99 



Wassermann and Schiitze* found that when cows' milk 

 was repeatedly injected into rabbits, their serum acquired 

 the property of occasioning a precipitate when added to 

 cows' milk, but not when added to goats' or any other milk. 

 If, however, the rabbit had been repeatedly injected with 

 goats' milk or human milk, its serum would precipitate with 

 those milks, respectively, and not with cows' milk. The 

 reaction was thus shown to be specific. 



Meyersf found that the repeated intraperitoneal injec- 

 tion of egg-albumen into rabbits caused their serum to 

 give a dense precipitate when added to crystallized egg- 

 albumen. 



Tchis to witch J found that eels' serum injected into animals 

 produced a reaction in which immunity to its poisonous 

 action was associated with the ability of their serum to pro- 

 duce a precipitate when added to the eels' serum. 



Closely connected with these various reactions are certain 

 others variously spoken of as cytotoxic, cytolytic, hemolytic, 

 bacteriolytic, etc. The first observation bearing upon these 

 was made by R. PfeifTer, who found that when guinea-pigs 

 received frequent intraperitoneal injections of cholera spirilla 

 and became thoroughly immunized, their serum behaved 

 very peculiarly toward the bacteria in the peritoneal cavity 

 of freshly infected animals, in that it caused them to become 

 aggregated into granular masses and subsequently to dis- 

 appear. This became known as ^Pfeiffer's phenomenon." 

 The serum of the immunized animal was devoid of action 

 by itself, the serum of the infected animal was inactive, but 

 the combination of the two brought about dissolution of 

 the micro-organisms. Later it was shown by Metschnikoff || 

 that the living animal was not a factor in the process, but 

 that what was seen in the peritoneal cavity could be re- 

 produced in a test-tube, though not quite as well. 



Bordet** made frequent injections of defibrinated rabbits' 

 blood into guinea-pigs, and obtained a serum that had a 

 solvent action upon the rabbit's corpuscles in vitro, and 

 showed that the induced hemolysis resembled in all points 

 the bacteriolysis. 



* " Deutsche med. Woch.," 1900. f " Lancet," n, 1900. 



J " Ann. de 1'Inst. Pasteur," vol. 13. 

 " Zeitschrift fur Hygiene," xvm. 

 || "Ann. de 1'Inst. Pasteur," 1895. 

 ** "Ann. de 1'Inst. Pasteur," xn. 



