448 BACTERIOLOGY. 



a bouillon culture were dried upon thin glass covers 

 they failed to grow after twenty-four hours (Weisser). 

 Waliczek found that when dried upon pieces of sterile 

 filter-paper they failed to grow at the end of eighteen 

 hours. These results give confirmation to the view 

 that the colon bacillus does not form spores. 



Pathogenesis. The colon bacillus is pathogenic in 

 varying degrees for test animals, though the results of 

 the inoculations, as with the typhoid bacillus, cannot 

 always be predicted with certainty. Intraperitoneal 

 injections of from 0.1 to 1 c.c. of fresh, virulent cul- 

 tures usually produce death in mice at the end of from 

 one to eight days, but death does not invariably follow. 

 The more rapidly death ensues the greater the number 

 of bacilli found in the body; they are always more 

 abundant in the abdominal cavity than in the blood; 

 in other words, the result is to be attributed to the 

 toxic rather than to the infective properties of the 

 culture used. But the fact that the bacilli are found 

 in the blood and internal organs when death rapidly 

 follows inoculation proves that they do multiply to 

 some extent in the body. When less virulent cultures, 

 however, are injected and death results, this is due to 

 the poisonous products formed by the bacilli and given 

 up at their death. The lesions produced are those of 

 enteritis : the duodenum and jejunum are found to con- 

 tain fluid, the spleen is somewhat enlarged, and there 

 is marked hypersemia and ecchymosis of the small in- 

 testines, together with swelling of Peyer's patches. 



Intraperitoneal and intravenous inoculation of guinea- 

 pigs and rabbits may also produce death, which, when 

 it follows, usually takes place within the first forty-eight 

 hours, accompanied by a decided fall of temperature, 



