8 INFECTION AND RESISTANCE 



tion. Pfeiffer with Wassermann 30 had studied the pathogenicity of 

 cholera spirilla for guinea pigs, and had come to the conclusion that 

 the animals died of toxemia (and not of bacteriemia, as claimed by 

 Gruber and Wiener), and that this toxemia was due to the liberation 

 of poisons from the dead bodies of cholera vibrios, killed by the 

 serum of the infected animals. Pfeiffer 31 now showed that the in- 

 jection of cholera spirilla killed with chloroform brought about a tox- 

 emia identical with that following inoculation with living cultures. 

 He further determined that the resistance of animals against cholera 

 was due to the bactericidal effects of the serum, which killed the 

 injected cholera spirilla, and not to any poison-neutralizing property. 



Isaeff, 32 one of Pfeiffer's pupils, continuing this work, expresses 

 his own and Pfeiffer's conceptions as follows: a Guinea pigs vac- 

 cinated against cholera, in spite of high immunity to infection with 

 living spirilla, do not develop any immunity to cholera [endo] 33 

 toxins. The blood of immunized guinea pigs possesses no antitoxic 

 properties. The maximal dose of cholera 'toxin' which immunized 

 guinea pigs can withstand is not higher than that which can be borne 

 by normal animals, and but slightly higher than the maximal dose 

 of living spirilla, which they can survive. The blood of cholera-vac- 

 cinated guinea pigs possesses strong specific protective powers. The 

 same specific immunizing properties are demonstrable in the blood 

 of cholera convalescents toward the end of the third week of the 

 disease." 



The path was thus cleared for a definite conception of cholera 

 immunity, and this was formulated, in their next communication, 

 by Pfeiffer and Isaeff. 34 35 36 In this paper they showed that the 

 cholera spirilla injected into the peritoneum of a cholera-immune 

 guinea pig were subjected to a rapid dissolution, a process which 

 could be observed by taking small quantities of exudate out of the 

 peritoneum, at varying intervals, with capillary pipettes. ~No such 

 dissolution occurred in normal pigs or with normal serum. But the 

 same rapid swelling, granulation, and, finally, dissolution occurred 

 when the spirilla were injected into the peritoneal cavity of a nor- 

 mal guinea pig, together with the serum of an immunized animal. 

 The process took place apparently without the cooperation of the 

 leukocytes or other cells, and was absolutely specific. For instance, 

 no "lysis" occurred when the vibrios "Nordhafen," "Massauah," and 

 other cholera-like organisms were injected into cholera-immune pigs, 



30 Pfeiffer and Wassermann. Zeitschr. f. Hyg., Vol. 14, 1893; also 

 Pfeiffer, Zeitschr. f. Hyg., Vol. 16, 1894. 



31 Gruber and Wiener. Archiv f. Hyg., Vol. 15, 1893. 

 52 Isaeff. Zeitschr. f. Hyg., Vol. 16, 1894. 



33 Bracketed word our own. 



34 Pfeiffer and Isaeff. Zeitschr. f. Hyg., Vol. 17, 1894. 



35 Pfeiffer. Ibid., Vol. 18, 1894. 



36 Pfeiffer and Isaeff. Deutsche med. Woch., No. 13, 1894. 



