124 PATHOGENIC BACTERIA. 



mals to ricin and abrin, and found that in the blood 

 serum a protective substance appeared, which was potent 

 to save animals into which it was injected, from fatal doses 

 of the respective toxalbumins. Calmette, 1 Phisalix, and 

 Bertrand 2 also begun experimenting with the venom of 

 serpents, and found that in the blood serum of animals 

 immunized to this poison a protective substance made its 

 appearance. Behring called the protective substances in 

 the blood "antikorper" (anti-bodies). As the majority 

 of them combated the activity of the toxins, it seemed 

 natural to adopt the word antitoxin, and now scarcely 

 any other term is applied to them. 



From the observations mentioned, Behring contrived 

 to work out the details of the "Blood-serum Therapy," 

 and after immense difficulty in overcoming the obstacles 

 iu the way, proposed methods of preparing the necessary 

 toxins, immunizing the animals, and preparing and 

 using the serum. These methods were so satisfactory 

 that the flood-tide of investigation which succeeded his 

 publications has not made any essential changes. 



It has already been shown that the antitoxins are of 

 questionable occurrence in ordinary forms of immunity. 

 In some of the illustrations given the protective power 

 may have depended upon entirely different entities, and 

 surely after the experiments of Wassermann and Takaki 

 with comminuted brain and spinal cord tissue, and those 

 of Staudensky with carmin, we should be prepared to 

 expect that there may be numerous other protective 

 influences. 



The occurrence of antitoxin in the blood serum is to 

 be considered as a phenomenon of forced immunization. 

 During the immunization process it does not seem to 

 develop in proportion to the toxic endurance of the ani- 

 mal, but, as Roux has pointed out, is rather suddenly 

 developed after the immunization has attained a high de- 

 gree. During the continuance of the immunization it is 



1 Annales de r Inst. Pasteur, 1894, viii., p. 275. 

 * Compte-rendu Acad, des Sciences, cxviii., p. 556. 



