35S THE ALCALIGENES-DYSENTERY— TYPHOID GROUP 
membrane of the large intestine with some necrosis of the epitheUum, 
associated with hyperemia of the mucosa of the small intestine as well. 
The mesenteric glands are usually swollen and hyperemic. Later the 
inflammation may become very severe; a pseudomembrane may form 
in the large intestine with extensive superficial ulceration of the 
mucosa. The ulcers do not extend, as a rule, to the submucosa; con- 
sequently, perforation is rare in uncomplicated cases. The submucosa, 
however, may be swollen and somewhat edematous. 
The nervous symptoms which are a feature of se\ere dysentery 
infections w^ould suggest that in addition to the intestinal lesions there 
may be involvement of the nervous system. Southard, McGaffin 
anfl Richards^ have shown that in addition to lesions of the intes- 
tinal tract, the Shiga toxin has a special affinity for the anterior horn 
ganglion cells, thus explaining on a definite anatomical basis the ner- 
vous symptoms which are a feature of fatal cases of bacillary dysentery. 
Dopter- has expressed the same opinion. He believes the toxin of the 
Shiga bacillus has an elective affinity for the intestinal mucosa of 
the large intestine, and it is the toxin secreted by the dysentery bacilli 
during their multiplication in the intestinal mucous membrane which 
induces the anatomical and nervous lesions characteristic of the disease. 
Ajiimals.—Typicsd bacillary dysentery has not been produced in 
laboratory animals by feeding the organisms. The intravenous 
inoculation or intraperitoneal injection of living or killed broth cultures 
of Shiga or Flexner bacilli, however, are usually fatal, particularly to 
rabbits. Vaillard and Dopter,'' and Flexner and Sweet ^ have shown 
that small amounts of forty-eight-hour broth cultures of Shiga bacilli 
introduced intravenously into young rabbits frequently lead to diar- 
rhea, which at first is mucous in character; later it becomes muco- 
sanguineous. After two or three days symptoms of paraplegia develop. 
At autopsy the large intestine is swollen and frequently edematous. 
The mesentery is hyperemic with enlarged glands. The intestinal 
contents are muco-sanguineous in character and the intestinal wall is 
considerably thickened. If the animal survives for several days, more 
advanced lesions are sometimes seen, particularly beginning ulceration 
and necrosis. Flexner states that the intestinal lesions of bacillary 
dysentery in man and in animals are probably due, in part at least, to 
the direct action of the dysentery toxin. 
Immunity and Immunization. — Shiga"" and others have succeeded in 
immunizing laboratory animals, particularly rabbits, guinea-pigs and 
horses, with dysentery bacilli, beginning by injecting killed cultures 
of these organisms, first with very small amounts which are slowly 
and cautiously increased, finally with living bacilli. Formalin-killed 
Shiga bacilli are preferable to heat-killed cultm-es. It is difficult to 
immunize animals because of the toxicity of the organism. The sera 
1 Boston Med. and Surg. Jour., 1909, 161, 65, 108. 
2 Loc. cit., p. 77. 3 Ann. Inst. Pasteur, 1903, 17, 46.3. 
* Jour. Exp. Med., 1906, 8, 514. ' Ztschr. f. Hyg., 1902, 41, 355. 
