CHAPTER XV 

 LYSINS, AGGLUTININS, PRECIPITINS, AND OTHER ANTIBODIES 



LYSINS 



IN the immediately preceding sections, we have dealt solely with 

 immunity as it occurs where soluble toxins play an important part 

 and in which antitoxins are developed in the immunized subject. There 

 are many species of pathogenic bacteria, however, which stimulate 

 the production of little or no 'antitoxic substance when introduced into 

 animals, and the resistance of the immunized animal can not, therefore, 

 be explained by the presence of antitoxin in the blood. 



v. Fodor, 1 Nuttall, 2 Buchner, 3 and others had in 1886 and the years 

 following carried on investigations which showed that normal blood 

 serum possessed the power of killing certain of the pathogenic bacteria. 

 Nuttall, working under the direction of Fliigge, made the important dis- 

 covery that this bactericidal power became gradually diminished with 

 time, and could be experimentally destroyed by exposure of the serum 

 to a temperature of 56 C. for one-half hour. Buchner, who confirmed 

 and extended the observations of Nuttall, called this thermolabile sub- 

 stance upon which the bactericidal character of the serum seemed to 

 depend "alexin." 



Our knowledge of the bactericidal action of serum was, soon there- 

 after, extensively increased by the discovery, by Pfeiffer and Isaeff, 4 

 that cholera spirilla injected into the peritoneal cavity of a cholera- 

 immune guinea-pig were promptly killed and almost completely dis- 

 solved. The same phenomenon could be observed when the spirilla, 

 mixed with fresh immune serum, were injected into the peritoneum of a 

 normal guinea-pig. 



The processes observed by Pfeiffer as taking place intraperitoneally 

 were soon shown by Metchnikoff, 5 Bordet, 6 and others to take place, 

 though to a lesser extent, in vitro. Bordet, furthermore, observed that 



v. Fodor, Deut. med. Woch., 1886. * Nuttall, Zeit. f. Hyg., 1886. 



Buchner, Cent, f . Bakt. , 1889. < Pfeiffer und Isaeff, Zeit. f . Hyg. , 1894. 



6 Metchnikoff, Ann. de Pinst. Pasteur, 1895. Bordet, ibid.* 1895. 



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