158 BACTERIA 



Vital Properties. It is killed by i percent carbolic solution 

 in thirty minutes. Lives for twelve to seventeen days when dried. 

 Direct sunlight kills it in thirty minutes. Its thermal death-point 

 is 58 C. in thirty minutes. It is a facultative aerobe; grows at 

 ordinary temperature, but better at 37 C. 



Cultures. Grows on all the common culture media, but more 

 slowly than the colon bacilli. Gelatine cultures resemble typhoid. 

 The growth in this media (which it does not liquefy) produces no 

 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, 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 lymphoid 

 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 parenchymatous degeneration. 

 The bacilli being possessed of a powerful endo-toxin, so that dead 

 cultures, if injected under the skin cause marked local and general 

 reactions. Like the pyocyaneus bacillus, this organism undergoes 



