THE DYSENTERY BACILLI 443 



its symptoms being referable almost entirely to the absorption of the 

 poisonous products of the bacillus from the intestine. 



The earliest investigations, carried on chiefly upon rabbits, which 

 are more susceptible to this poison than any other animals, showed that 

 even small doses of cultures of this bacillus administered intravenously 

 or subcutaneously would produce death within a very short time. 

 Conradi,' Vaillard^ and Dopter, and others, finding that toxic symptoms 

 were almost as pronounced when dead cultures were given as when the 

 living baciUi were administered, came to the conclusion that the poisons 

 of this bacillus were chiefly of the endotoxin type. More recently Todd,^ 

 Kraus,* and Rosenthal^ have claimed independently that they were 

 able to demonstrate strong soluble toxins, similar in every way to diph- 

 theria toxin. Kraus and Doerr," moreover, claim to have further cor- 

 roborated this by producing specific antitoxins with these substances. 



It is easy to obtain poisonous substances from dysentery cultures 

 in considerable strength, both by extracting the bacilli themselves 

 and by filtration of properly prepared cultures. It is therefore not 

 unlikely that both types of poison are produced by the bacilli. 

 Neisser and Shiga ' obtained toxins by emulsifying agar cultures in 

 sterile salt solution, killing the bacilli at 60° C, and allowing them to 

 extract at 37.5° 0. for three days or more. The filtrates from such emul- 

 sions were extremely toxic. The simplest method of obtaining poisons 

 from these bacilli is to cultivate them for a week or longer upon moder- 

 ately alkaline meat-infusion broth. At the end of this time, the micro- 

 organisms themselves may be killed by heating to 60° and the cultures 

 filtered. According to Doerr,* the toxins may be obtained in the dry 

 state by precipitation with ammonium sulphate and re-solution of the 

 precipitate in water. 



The action of the dysentery toxin upon animals is extremely 

 characteristic and throws much light upon the disease in man. The 

 injection of a large dose intravenously into rabbits causes a rapid 

 fall in temperature, marked respiratory embarrassment, and a violent 



1 Conradi, Deut. med. Woch., 1903. 



' Vaillard et Dopter, Ann. de I'inst. Pasteur, 1903. 



3 Todd, Brit. Med. Jour., Dec, 1903, and Jour, of Hyg., 4, 1904. 



^ Kraus, Monatschr. f. Gesundheit, Suppl. 11, 1904. 



' Rosenthal, Deut. med. Woch., 1904. 



• Kraus und Doerr, Wien. klin. Woch., xlii, 1905. 

 ' Neisser and Shiga, Deut. med. Woch., 1903. 



* Doerr, " Das Dysenterietoxin," Jena, 1907. 



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