ENDOTOXINS 125 



soluble and highly poisonous, and it is undoubtedly through 

 their action that the characteristic diseases are produced by the 

 bacteria that contain them. Presumably the endotoxins are 

 liberated in the body either by autolysis, or, more probably, by 

 heterolysis by the enzymes of the body cells and fluids. 



Endotoxins differ from the true toxins, however, in one 

 important respect : namely, no antitoxin has been obtained for 

 endotoxins by immunization of animals. 1 Animals immunized 

 against endotoxins develop in their serum substances that are 

 bactericidal and agglutinative to the bacteria from which the 

 poisons are derived, but the serum will not neutralize the endo- 

 toxins, 2 As a result, we are unable to perform experiments 

 indicating whether endotoxins have the same structure as the true 

 toxins, i. e. } a haptophore and a toxophore group, but presumably 

 their nature is different in some essential particular. The chemi- 

 cal nature of the endotoxins is also unknown, for they are always 

 obtained mixed with the other constituents of the bacteria. 



Since far more bacterial diseases are brought about by endo- 

 toxins than by true toxins, the failure to secure antitoxins for 

 these substances has been a great check in the progress of serum 

 therapy, and the problem of the endotoxins is one of the most 

 important in the entire field of immunity. 



POISONOUS BACTERIAL PROTEIDS 



If we filter a bouillon culture of diphtheria bacilli through 

 porcelain, wash thoroughly the bacteria remaining with salt solu- 

 tion, and collect them thus freed from their secretion products, 

 it will be found that extracts of the bacterial substance or the 

 bodies of the killed bacteria themselves are quite free from the 

 typical toxin. This indicates that the toxin is eliminated from 

 the bacteria as fast as it is formed, and no considerable quantity 

 is retained within the cell. The bacterial substance, however, 

 or proteids isolated from it, is found to produce severe local 

 changes when injected into the bodies of animals, necrosis and 

 a strong inflammatory reaction with pus-formation being the 

 chief features. This local effect is not a specific property of the 

 diphtheria bacillus, for other bacterial proteids, including proteids 

 from non-pathogenic bacteria, will produce the same changes ; 

 indeed, many proteids that are derived from vegetable and ani- 

 mal sources have equally marked pyogenic properties. All 

 foreign proteids when introduced into the circulation of animals 



1 Positive results are claimed by Besredka, (Ann. Inst. Pasteur, 1906 (20), 

 304), and a few others; see Kraus, Wien. klin. Woch., 1906 (19), No. 22. 



2 See resume* by F. Schmidt, Zeit. f. Infektionskr. der Haustiere, 1906 (1), 

 238, and Hahn, Munch, med. Woch., 1906 (53), No. 23. 



