356 THE ALCALIGENES— DYSENTERY— TYPHOID GROUP 
antitoxic and protect laboratory animals against several times the 
fatal dose of the toxin. Olitsky and Kligler^ have succeeded in pro- 
ducing a very powerful toxin by cultivating the Shiga organism in a 
slightly alkaline egg broth medium. According to Kraus and Doerr,^ 
this toxin acts somewhat like that of the diphtheria bacillus; the lesions 
observed in the large intestine are comparable to the lesions of the 
diphtheria bacillus in the tonsils and pharynx. The nervous lesions are 
somewhat like those of poliomyelitis. Intravenous injection of large 
doses in rabbits causes death in from six to eight hours; smaller doses 
cause paresis, diarrhea, which is frequently bloody, paralysis of the 
bladder, hypothermia and death in one to four weeks. Postmortem 
there is a muco-hemorrhagic enteritis, usually localized in the cecum. 
It is stated that the entire intestinal tract is involved in dogs, with 
the duodenum particularly affected. Intraperitoneal and subcu- 
taneous injections give a much milder reaction with a prolonged 
incubation period. The toxin is inactivated by acids, but its potency 
may be partially restored when the acid is neutralized with alkali. 
Conradi^ and others find dead cultures almost as toxic as the living 
bacilli; they call attention to the toxic properties of autolysates (in 
sterile water) of the Shiga bacillus, a fact which was pointed out by 
Gay* some time before. It is probable that both soluble and autol\i:ic 
poisons are concerned in the toxicity of filtrates of broth cultures of 
the organism, although Olitsky and Kligler^ clearly differentiated 
between them in their experiments. The toxic substances'' may be 
obtained in dry form by saturating the broth (freed from bacilli by 
filtration through unglazed porcelain) with ammonium sulphate, 
dialyzing the precipitate to remove the ammonium salts, and evapora- 
tion of the 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. '^ 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 
antitoxin. The other members of the dysentery group do not produce 
soluble toxic substances in demonstrable amounts. 
(6) Endotoxin.— '^e'lsser and Shiga^ have found that autolysates 
of Shiga bacilli produce a muco-hemorrhagic enteritis in rabbits. 
Besredka,^ Conradi^" and others have also extracted substances from 
the organisms by grinding them with sodium chloride, sand, by 
alternate freezing and thawing (method of MacFadyen and Roland), 
1 Jour. Exp. Med., 1920, 31, 19. - Loc. cit. 
3 Deutsch. med. Wchnschr., 1903, 29, 2G. 
4 Pennsylvania Med. Bull., 1902. » Loc. cit. 
6 Besredka: Bull. Inst. Pasteur, 1914, 12, 193. 
^ Todd: Loc. cit. Kraus and Doerr: Loc. cit. 
8 Deut.sch. med. Wchnschr., 1903, 29, 61. 
9 Ann. Inst. Pasteur, 1906, 20, 304. i" Loc. cit. 
