DEFENSIVE FACTORS OF THE ANIMAL ORGANISM 199 



used in the immunization. He called these bodies antitoxins. While 

 Behring's first conception of actual toxin destruction soon proved to 

 be erroneous, his discovery of the presence in immune sera of bodies 

 specifically antagonistic to toxins was soon confirmed and extended, 

 and stands to-day as an established fact. 



Ehrlich,^ soon after Behring's announcement, showed that specific 

 antitoxins could also be produced against the poisons of some of the 

 higher plants (antiricin, antikrotin, antirobin) , and Calmette ' produced 

 similar antitoxins against snake poison (antivenin) . Stimulated by these 

 researches, other observers have, since then, added extensively to the 

 list of poisons against which antitoxins can be produced. Kempner ' 

 has produced antitoxin against the poison of Bacillus botulinus, and 

 Wassermann,* against that of Bacillus pyocyaneus. Antitoxin has been 

 produced by Calmette ° against the poison of the scorpion, and by Sachs ° 

 against that of the spider. Thus a large number of poisons of animal, 

 plant, or bacterial origin have been found capable of causing the pro- 

 duction of specific antibodies in the sera of animals into which they are 

 injected. 



The formation of antitoxins directed against soluble poisons, how- 

 ever, did not explain the immunity acquired by animals against bacteria 

 like Bacillus anthracis, the cholera vibrio, and others which, unlike diph- 

 theria and tetanus, produced little or no soluble toxin. It was evident 

 that the antitoxic property of imiUune blood serum was by no means 

 the sole expression of its protective powers. Much light was shed upon 

 this phase of the subject by the discoveries of Pfeiffer in 1894, who 

 worked along the Hnes suggested by the investigations of Nuttall and 

 Buchner. Pfeiffer ' showed that when cholera spirilla were injected into 

 the peritoneal cavity of cholera-immune guinea-pigs, the microorganisms 

 rapidly swelled up, became granular, and often underwent complete 

 solution. The same phenomenon could be observed when the bacteria 

 were injected into a normal animal together with a sufficient quantity 

 of cholera-immune ' serum. 



1 Ehrlich, Deut. med. Woch., 1891. 



^ Calmette, Compt. rend, de la soc. de biol., 1894. 



* Kempner, Zeit. f. Hyg., 1897. 



^ Wassermann, Zeit. f. Hyg., xxii. 



^ Calmette, Ann. de I'inst. Pasteur, 1898. 



1^ Sachs, Hofm. Beit., 1902. 



' Pfeiffer, Zeit. f. Hyg., xviii, 1894. 



'Pfeiffer und Isaeff, ibid. 



