248 BACTERIOLOGY. 



Proteus Zenkeri. Cocci, -4 ^ in twos like 

 Bacterium termo, and short rods 1*65 ju long. Cul- 

 tivated on nutrient gelatine no liquefaction results, 

 but a thick, whitish-grey layer is formed. The 

 bacilli are motile, and the same phenomena are 

 observed on the solid medium as in the other forms. 

 In * cover-glass impressions most varied groupings 

 of the bacilli are seen, and also developmental and 

 involution-forms. 



The two following forms are only provisionally re- 

 garded as distinct species. They are both probably 

 phase- forms of protean species. 



Bacterium terrno, Dujardin. Short cylindrical 

 or oblong cells, 1*5 //, long, '5 7 broad, generally occurring 

 as dumb-bells. The cells have dark contents, invested by 

 a thick membrane, and are provided with flagella, to which 

 the characteristic movements are due (Plate I., Fig. 8). 

 They are associated with putrefaction, invariably appear- 

 ing in decomposing albuminous substances and liquids. A 

 growth can be readily started by placing a piece of meat 

 in water in a warm place. Cultivated in broth, they pro- 

 duce a turbidity, and on sterilised potatoes a slimy grey 

 layer. 



Bacterium lineola. Cells 3-8 p 5-2 //, long, 1-5 ^ 

 wide. They occur singly or in pairs, occasionally in 

 zoogloea, but never in chains. The cells are provided with 

 flagella, and contain strongly refringent contents. They 

 resemble Bacterium termo in form and in movement, but 

 are considerably larger. They occur in well water and 

 stagnant water, and form slimy heaps on rotting potatoes, 

 and zoogloea and pellicles on various infusions. Cultivated 

 on nutrient agar-agar they form a semi-transparent growth 

 (Plate XXIV., Fig. i). 



