THE DYSENTERY BACILLI 



255 



APPEARANCE OF CULTURES.^OH gelatin the colonies appear more 

 like the typhoid than the colon bacilli. Gelatin is not liquefied. On 

 agar growth is somewhat more delicate than the average colon cultures. 



On Potato. A delicate growth just visible or distinctly brownish. 



In Bouillon Diffuse cloudiness with slight deposit and sometimes 

 a pellicle. Indol not produced or in a trace only. 



In glucose bouillon no production of acid or gas. 



Neutral red agar is not blanched. 



In Liimus Milk. After twenty-four to forty-eight hours this becomes 

 a pale lilac. Later, three to eight days, there is a return to the original 

 pale blue color. The milk is not otherwise altered in appearance. 



Animal Tests. No characteristic lesions have followed swallowing 

 large quantities of bacilli. Dogs at times have had diarrhoea with slimy 

 stools, but section showed merely a hypersemia of the small intestine. 



FIG. 86 FIG. 87 



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Dysentery bacillus. Colony of dysentery bacilli in gelatin. 



Many animals are very sensitive to bacilli injected in vein or peri- 

 toneum; 0.1 mg. of agar culture injected intravenously produced 

 diarrhoea, paralysis, and death; 0.2 mg. under the skin have killed, and 

 the same amount in the peritoneum has caused bloody peritonitis, with 

 lowered temperature and diarrhoea. Both small and large animals are 

 very sensitive to killed cultures. 



The autopsy of animals dying quickly from injection into the peri- 

 toneum of living or dead bacilli shows the peritoneum to be hyper- 

 aemic, the cavity more or less filled with serous or bloody serous exudate. 

 The liver is frequently covered with fibrinous masses. The spleen 

 is moderately or not at all swollen. The small intestine is filled with 

 fluid, the large intestine is usually empty. The mucous membrane of 

 both is hypersemic and sometimes contains hemorrhages. Conradi 

 found ulcer formation in one case. 



Subcutaneous injections of dead or living cultures are followed by 

 infiltration of tissues and frequently by abscess formation. The 

 dysentery bacilli produce both extracellular and cellular toxins, the 

 latter being the most abundant. The elimination of these toxins from 



