186 BACILLUS COL1 COMMUNIS. 



that B. coli communior produces gas from saccharose and B. 

 coli com munis does not. 



Pathogenesis. Bouillon cultures of Bacillus coli com munis 

 injected intravenously or into the peritoneal cavity of a rabbit 

 cause death in less than twenty-four hours. On autopsy in- 

 tense hypersemia of the peritoneum, ecchymotic spots of the 

 intestines, swelling of Payer's patches, and enlargement of the 

 spleen are found. Subcutaneous inoculations are followed by 

 abscesses formed at the point of inoculation, and by internal 

 conditions similar to those produced by intravascular injec- 

 tions. Injected into the pleural cavity it gives rise in twenty- 

 four hours to a purulent pleurisy accompanied by a large 

 effusion in the cavity and the formation of false membrane. 

 Agglutinins, precipitins, and lysins against B. coli have been 

 demonstrated in immune sera. 



Bacillus Proteus Vulgaris. 



History. Described by Hauser in 1885. Its distribution is 

 wide in nature, and it is of interest chiefly on account of the 

 fact that it is a frequent source of contamination in cultures. 



Morphology and Staining. In appearance B. proteus re- 

 sembles the members of the typho-colon group, but varies 

 more in size. It stains by all the ordinary stains and not 

 by Gram's method. 



Biologic Characters. It forms no spores, and grows best in 

 an atmosphere at about room temperature. The optimum 

 temperature for its growth is 25 C. It grows readily on all 

 culture-media. Blood-serum is usually liquefied. The growth 

 on gelatine, however, is characteristic, the colonies being irreg- 

 ular (protean) and the gelatin liquefied. Milk is rendered 

 acid and coagulated at first with subsequent liquefaction. On 

 potato a dirty yellowish growth results. 



Pathogenesis. As the bacilli of this group have always 

 boon regarded as pure saprophytes, flourishing where putre- 

 faction existed, very little pathogen icity has been ascribed to 

 them. Some cases of meat poison have, however, been traced 

 to members of this group. The Bacillus liquefaciens septicus 

 of urine, which is a factor in the production of a cystitis, has 

 been described by Krogius and no doubt belongs to this group. 



