416 PATHOGENIC MICROORGANISMS 



Pfeiffer/ who first advanced the opinion that the poisonous substances 

 are products of the bacterial body set free by destruction of the bacteria 

 by the lytic substances of the invaded animal or human being. These 

 poisons, when injected into animals for purposes of immunization, in 

 Pfeiffer's experiments, did not incite the production of neutralizing or 

 antitoxic bodies, but of bactericidal and lytic substances. That these 

 endotoxins constitute by far the greater part of the toxic products of 

 the typhoid bacillus can be easily demonstrated in the laboratory, by 

 the simple experiment of filtering a young typhoid culture (eight or 

 nine days old) and injecting into separate animals the residue of bacilli 

 and the clear filtrate respectively. In such an experiment there will be 

 little question as to the overwhelmingly greater toxicity of the bacillary 

 bodies as compared with that of the culture filtrate. On the other 

 hand, if such cultures, especially in alkaline media, are allowed to 

 stand for several months and the bacilli thus thoroughly extracted by 

 the broth, the toxicity of the filtrate is found to be greatly increased. 



Nevertheless, more recent experiments by Besredka,^ Macfadyen,^ 

 Kraus and Stenitzer,* and others have tended to show that, together 

 with such endotoxic substances, typhoid bacilli may produce a true 

 toxin which is not only obtainable by proper methods from compara- 

 tively young typhoid cultures, but which fulfils the necessary require- 

 ment of this class of poisons by producing in treated animals a true 

 antitoxic neutralizing body. 



The typhoid endotoxins may be obtained by a variety of methods. 

 Hahn''' has obtained what he calls " typhoplasmin " by subjecting them 

 to a pressure of about four hundred atmospheres in a Buchner press. 

 The cell juices so obtained are cleared by filtration. Macfadyen has 

 obtained typhoid endotoxins by triturating the bacilli after freezing 

 them with liquid air and extracting in 1 : 1,000 potassium hydrate. 

 Besredka obtained toxic substances by emulsifying agar cultures of 

 bacilli in salt solution, sterilizing them by heating to 60° C. for about 

 one hour, and drying in vacuo. The dried bacillary mass was then 

 ground in a mortar and washed in sterile salt solution which was 

 again heated to 60° C. for two hours. The remnants of the bacterial 



' Pfeiffer/DBXit. med.Woch., xlviii, 1894; Pfeiffer und KoUe, Zeit. f. Hyg., xxi, 1896. 

 2 Besredka, Ann. de I'inst. Pasteur, 1895, 1896. 



'Macfadyen and Rowland, Cent. f. Bakt., I, xxx, 1901; Macfadyen, Cent. f. 

 Bakt., I, 1906. 



* Kraits und Stenitzer, Quoted from "Handb. d. Tech., "etc., 1, Fischer, Jena, 1907. 

 = Hahn, Munch, med. Woch., xxiii, 1906. 



