SYSTEMATIC AND DESCRIPTIVE. 131 



GROUP II. BACTERIACE^E. 



Genus I. Bacterium. Cocci and rods, or only rods, 

 which are joined together to form threads. Spore- 

 formation absent or unknown. 



Genus II. Spirillum. Threads screw-form, made up 

 of rods (long or short) only, or of rods and 

 cocci. Spore-formation absent or unknown. 



Genus III. Leuconostoc. Cocci and rods. Spore- 

 formation present in cocci. 



Genus IV. Bacillus. Cocci and rods, or rods only, 

 forming straight or twisted threads. Spore-for- 

 mation present either in rods or cocci. 



Genus V. Vibrio. Threads screw-form in long or 

 short links. Spore-formation present. 



Genus VI. Clostridium. Same as bacillus, but spore- 

 formation takes place in charactreistically enlarged 

 rods. 



Genus I. Bacterium. 



Bacterium ureae (Micrococcus urea, Cohn). 

 Cocci 1*25 2 p. in diam., singly or in chains, and 

 rods. The rods split up by division into chains of 

 cocci, and the latter are finally set free. The cocci 

 increase further by subdivision, and a jelly-like mem- 

 brane develops around them. Masses of cocci exist 

 in the form of irregular or roundish lumps. Culti- 

 vations, after twenty-four hours, consist exclusively 

 of rods, after forty-eight hours, of cocci-chains, 

 and, in fourteen days, of zooglcea ; the cocci trans- 

 planted into fresh nourishing solution again grow 



