THE PROTEUS GROUP OF BACTERIA 127 



Spore Formation absent. 



Staining Reactions. Easily stained with the ordinary agents, but 

 not by the Gram method. 



Biological Characters. The developing colonies resemble those of 

 the Coli commune, but are more granular. 



In Stab Cultures and on Agar media greyish-white tufts. 



On Potatoes a moist yellow coating which never becomes brown. 



Bouillon is clouded, a film forming on the surface. 



Milk is not coagulated. 



Grape Sugar is slightly fermented, but Cane Sugar remains unchanged. 



Vitality. Cultures are killed when heated one minute at 70 C. 



Pathogenesis. Mice, rats, guinea-pigs, and rabbits are very 

 susceptible to infection by subcutaneous and intraperitoneal inocu- 

 lation, also by feeding. Dogs and cats are immune. The above 

 bacillus is also probably pathogenic for man, as many cases of sickness 

 have been observed to follow the consumption of the flesh of animals 

 affected with puerperal fever (Ostertag). 



THE PROTEUS GROUP OF BACTERIA. 



This group of organisms discovered by Hauser in 1885 consists of 

 three species 



1. Proteus Vulgaris. 



2. Mirabilis. 



3. Zenkeri. 



(1) PROTEUS VULGARIS. 



Microscopical Appearances. Small rods of various sizes, generally 

 occurring in pairs, but sometimes arranged in filaments. Involution 

 forms frequently occur, the most common being spherical bodies about 

 1*6 /x in diameter. 



Motility. Strongly motile, possessing numerous flagella (see Photo- 

 micrograph, Plate II., Fig. 12). 



Spore Formation is absent, and the bacilli are killed by five 

 minutes' exposure to a temperature of 55 C. 



Staining Reactions. The bacilli are easily stained with fuchsin, 

 not so easily with the ordinary watery solutions of the dyes. By the 

 Gram method the reaction is negative. 



Biological Characters. It is a facultative anaerobe, and at ordinary 

 room and incubator temperature the growth is equally luxuriant, the 

 optimum temperature being 20 to 25 C. 



On Gelatine Plates small round yellowish colonies with thick centres 



