SYSTEMATIC AND DESCRIPTIVE. 247 



species have been isolated* from putrefying meat 

 infusion, and are stated to be intimately connected 

 with the process of putrefaction. In the history 

 of their development coccoid, bacterioid, spindle- 

 form, spirulinar, and involution forms have been 

 described. In Proteus vulgaris the bacteria vary in 

 size ; some measure 4 /x in length, and are almost 

 as broad as long, and others vary from '94 1*25 p, 

 long and -42 '63 wide. They are actively motile, 

 and cultivated on nutrient gelatine they convert it 

 into a turbid, greyish-white liquid. If cultivated in 

 a capsule containing 5 per cent of nutrient gelatine, 

 a few hours after inoculation the most characteristic 

 movements of the individual bacilli are observed 

 on the surface of the nutrient gelatine, although at 

 this early stage no superficial liquefaction can be 

 detected. Probably the movements depend upon 

 the existence of a thin liquid layer, as they are not 

 observed if the nutrient medium contains 10 per 

 cent, of gelatine. 



Proteus mirabilis. Cocci -4 //, -9 ft. They 

 occur singly and in zooglcea, and sometimes in 

 tetrads, pairs, chains, or as short rods in twos 

 resembling Bacterium termo, in fact, in all con- 

 ceivable transition-forms. Cultivated on nutrient 

 gelatine they form a thick, whitish layer in con- 

 centric circles, which in time liquefies the medium. 

 Similar movements are observed in capsule-cultiva- 

 tions as in Proteus vulgaris. 



* Hauser, Ueber Fdulniss-Bacterien. 1885. 



