DYSENTERY BACILLUS 179 



pellicle, but a sediment. Indol is not produced, and milk is first 

 mildly acid and then faintly alkaline, though not coagulated. On 

 potato it grows sparingly, often turning it brown. The Shiga 

 type ferments glucose, but no other sugar. The Flexner type 

 ferments glucose, dextrine, and mannite, but not lactose. The 

 latter type produces more acid than the former, and both are 

 best agglutinated with their corresponding serums. 



Habitat. In living bodies the organism is found solely in 

 mucous discharges from the bowels. In the dead it is found in 

 the lymph-glands. If it reaches the circulation, it appears to be 

 rapidly destroyed by the blood. It has been discovered, however, 

 in the body of a foetus delivered from a woman with the disease. 

 The organism must have passed the placenta of the mother. The 

 disease is spread by water, food and personal contact and by 

 carriers, and it may become epidemic in large institutions. 



Pathogenesis. The typical lesions caused by the organism 

 vary from a mere hyperaemia to a superficial necrosis of the lym- 

 phoid structures, which may be extensive. Peyer's patches are 

 slightly swollen but not ulcerated. The descending colon and 

 sigmoid are oftenest attacked. The necrotic masses separate, 

 leaving shallow ulcers. The lymph structures are engorged with 

 polynuclear leucocytes. No marked lesion is found in the 

 spleen. The liver and kidneys often undergo marked parenchy- 

 matous degeneration. The bacilli being possessed of a powerful 

 endotoxin, so that dead cultures, if injected under the skin cause 

 marked local and general reactions. Like the pyocyaneus bacillus, 

 this organism undergoes auto-digestion in bouillon, which leaves 

 the latter highly toxic owing to the liberation of the toxins. 

 Laboratory animals quickly succumb to injection of this organism, 

 injection producing a marked reaction in the colon, a phenomenon 

 suggesting that there is a predilection for the organ and that the 

 body uses it as an excretory organ for the poison. Dysentery 

 cannot be induced in animals by feeding cultures. Poorly 

 nourished subjects are easily infected and quickly die. Digestive 



