252 INFECTION AND IMMUNITY 



showed that precipitates were formed when filtrates of cultures of 

 cholera, typhoid, and plague bacilli were mixed with their specific 

 immune sera. He called the substances which bestowed this property 

 upon the sera precipitins. 



The treatment of the animal body, therefore, with bacteria or their 

 products gives rise to a variety of reactions which result in the 

 presence of the "antibodies" described above. Extensive investiga- 

 tion has shown, however, that the power of stimulating antibody 

 production is a phenomenon not limited to bacteria and their products 

 alone. Antitoxins, we have already seen, may be produced with a 

 variety of poisons of plant and animal origin. Sensitizing, agglu- 

 tinating and precipitating effects may, likewise, be produced by the 

 use of a large number of different substances. Chief among these, 

 because of the great aid they have given to the theoretical investiga- 

 tion of the phenomena of immunity, are the red blood cells. Bordet 40 

 and, independently of him, Belfanti and Carbone 41 showed in 1898 

 that the serum of animals repeatedly injected with the defibrinated 

 blood of another species exhibited the specific power of dissolving 

 the red blood corpuscles of this species. This was the first demonstra- 

 tion of "hemolysis" a phenomenon which, because of the ease with 

 which it can be observed in vitro, has much facilitated investigation. 



The knowledge that specific "cytotoxins" or cell-destroying anti-bodies 

 could be produced by injection of red blood cells naturally suggested the 

 possibility of analogous reactions for other tissue cells. It was not long, 

 therefore, before Metchnikoff 42 and, independently of him, Landsteiner 43 

 succeeded, by repeated injections of spermatozoa, in producing a serum 

 which would seriously injure these specialized cells. Von Dungern 44 ob- 

 tained similar results with the ciliated epithelium of the trachea. Since 

 then a host of cytotoxins have been produced with the cells of various 

 organs and tissues. Thus, Neisser and Wechsberg 45 produced leucotoxin 

 (leucocytes); Delezenne, 4G neurotoxin and hepatotoxin; Surmont, 47 pan- 

 creas cytotoxin; and Bogart and Bernard, 48 suprarenal cytotoxin. 



40 Bordet, Ann. de 1'inst. Pasteur, 1898. 



41 Belfanti et Carbone, Giornale della E. Acatl. di Torino, July, 1898. 



42 Metchnikoff, Ann. de I'inst. Pasteur, 189S. 



43 Landsteiner, Cent. f. Bakt., i, 25, 1899. 



44 v. Dungern, Munch, med. Woch., 1899. 

 4 *Neisser und Wechsberg, Zeit. f. Hyg., xxxvi, 1901. 



"Delezenne, Ann. de I'mst. Past. 1900; Compt. rend, de 1'acad. des sci., 1900. 

 " Surmont, Compt. rend, de la soc. de biol., 1901. 

 48 Bogart et Bernard, ibid., 1891. 



