320 THE ALCALIGENES DYSENTERY TYPHOID 



dialyzed solution to dryness in vacuo. The dried residue is very toxic 

 for rabbits; 0.002 to 0.005 grams dissolved in a small amount of 

 sterile salt solution will usually kill these animals when injected 

 intravenously. Smaller amounts gradually increased stimulate anti- 

 body formation. 1 The antitoxin, however, has little curative value, 

 for the toxin appears to have a greater affinity for the epithelium of the 

 intestinal mucosa and central nervous system than it has for the anti- 

 toxin. The other members of the dysentery group do not produce 

 soluble toxic substances in demonstrable amounts. 



(6) Endotoxin. Neisser and Shiga 2 have found that autolysates 

 of Shiga bacilli produce a mucohemorrhagic enteritis in rabbits. 

 Besredka, 3 Conradi 4 and others have also extracted substances from 

 the organisms by grinding them with sand, by alternate freezing and 

 thawing (method of MacFadyen and Roland), or by autolysis, which 

 in small amounts will kill ^experimental animals when injected intra- 

 venously, intraperitoneally, or subcutaneously. Administration by 

 mouth is without noteworthy effect. The potency of the endotoxin 

 is not appreciably impaired by an exposure to 70 C. for an hour; an 

 exposure to 80 C. renders it inactive. Conradi 5 has shown that 

 occasional strains of dysentery bacilli (Shiga type) produce small 

 amounts of soluble hemotoxin. 



Pathogenesis. Experimental. Direct experimental evidence of the 

 etiological relationship of the dysentery bacillus to bacillary dysentery 

 is afforded by a few laboratory accidents in which the clinical disease 

 has followed the accidental ingestion of cultures of dysentery bacilli. 

 The most conclusive experiment, however, is that reported by Strong 

 and Musgrave. 6 A forty-eight-hour broth culture of B. dysenteriae 

 (Shiga type) was swallowed by a condemned criminal after a dose of 

 sodium hydrogen carbonate was given to neutralize the gastric acidity. 

 The initial symptoms of a typical attack of bacillary dysentery fol- 

 lowed after an incubation period of thirty-six hours. The organisms 

 were isolated from the mucopurulent, bloody feces. Ravant and 

 Dopter 7 produced clinical dysentery in an ape by feeding it Shiga 

 bacilli. 



Human. Infection with the Shiga bacillus is somewhat less com- 

 mon in the United States than infection with the Flexner and other 



1 Todd, loc. cit. ; Kraus and Doerr, loc. cit. 



2 Deutsch. med. Wchnschr., 1903, No. 4. 3 Ann. Inst. Past., April, 1906, vol. xxv. 

 4 Loc. cit. 6 Loc. cit. 



6 Report of the Surgeon-General, United States Army, 1900. 



7 Quoted by Kolle and Hetsch, Die experimentelle Bakt., II. Aufl., i, 304. 



