364 THE ALCALIGENES— DYSENTERY— TYPHOID GROUP 
phenols are not formed in ordinary media, but Peckliam^ has shown 
that indol may be produced in protein me(Ha of special composition. 
Bull and Pritchett- also ha\'e described an indol-producing strain. 
The essential cultural characters of B. typhosus are indicated in 
the table on page 353. Culturally B. typhosus is relatively inert; it 
does not produce proteolytic enzymes which liquefy gelatin, blood 
serum or fibrin. A f.at-si)litting ferment has been demonstrated in 
autolyzed typhoid ])acilli l)y Wells and Corper.^ An esterase which 
liberates butyric acid from ethyl butyrate is detectable in sterile 
filtrates of plain and glucose broth cultures of the organism.'' 
Typliohemolysin {Typhalysin).—Caste\\am,^ and E. Levy and P. 
Levy*^ have found that filtrates of (sugar-free) broth cultures of 
typhoid bacilli are hemolytic. They appear to have demonstrated 
specific antihemolytic properties in the blood of animals injected 
with hemolytic filtrates, thus meeting the objection that the hemo- 
lysis might be due to the alkalinity of the medium itself. There is 
no evidence at present which would suggest that this hemolysin plays 
any important part in typhoid infections of man. The typholysin is 
relatively thermostabile. 
Toxins.— A soluble toxin has never been satisfactorily demon- 
strated among the products of growth of the typhoid bacillus, and 
the consensus of opinion at the present time is in favor of the view 
that the principal toxic substance of the organism is an endotoxin. 
The endotoxin has been studied with special thoroughness by Mac- 
Fadyen and Roland,^ and Besredka.'^ It has been obtained in various 
ways: By grinding the organism with sodium chloride crystals, with 
sand, by freezing in liquid air and triturating, or by autolysis of 
the bacilli in sterile distilled water. Relatively small amounts of 
endotoxin obtained by any of these methods will usually kill guinea- 
pigs. No antitoxin has been produced in the sera of animals inoculated 
with gradually increasing amounts of this endotoxin. Recently 
Sogen^ has shown that typhoid autolysates will increase tonus and 
cause pendular movements in strips of excised rabbit intestine. It is 
stated that the action is upon the vagus endings in the gut. 
Typhoid Fever.— Pathogenesis.— ^A>7jm7/;e/?to/.— Typhoid fever is a 
disease of man only, and imtil recently rigorous experimental proof 
that the typhoid bacillus is the specific cause of this infection has been 
lacking. The evidence of the etiological relationship of the typhoid 
bacillus is of two kinds: (1) A few cases where laboratory attendants 
have accidentally or purposely swallow-ed cultures of typhoid bacilli 
1 Jour. Exp. Med., 1897, 2, 549. '- Ibid., 1916, 24, 55. 
3 Jour. Infec. Dis., 1912, 11, 388. 
* Kendall and Simonds: Jour. Inf. Dis., 1914, 15, 354. 
5 Lancet, 1902, i, 440. ^ Centralbl. f. Bakteriol., 1901, 30, 405. 
■ Ibid., orig., 1903, 34, 618, 765. MacFayden: Ibid., 1903, 35, 415. 
8 Ann. Inst. Pasteur, 1905, 19, 477; 1906, 20, 149, 304; Bull. Inst. Pasteur, 1914, 12, 
145. 
9 Tohoku .Jour. Exp. Med., 1920, 1, 211. 
