480 SYSTEMATIC. 



ZOPF'S CLASSIFICATION. 



Group I. Coccace^. — Possessing (so far as our knowledge at present 



reaches) only cocci, and thread-forms resulting from the juxtaposition of 



cocci. The fission occurs in one or more directions. 



Genus I. Streptococcus (Chain-cocci). — Division in one or more direc- 

 tions. Individual cocci remain united together to form chains. 



Genus II. Merismopedia (Plate-cocci). — Divisions in two directions, 

 forming lamellae or plates. 



Genus III. Sarcina (Packet-cocci). — Division in three directions, form- 

 ing colonies in cubes or packets. 



Genus IV. Micrococcus (Mass-cocci). — Division in one direction, cocci 

 after division remain aggregated in irregular clusters, or singly, or 

 in pairs or in chains of three or four elements. 



Genus V. Ascococcus (Pellicle-cocci). — Like micrococcus, but the cocci 

 grow in characteristic gelatinous pellicles. 



Group II. Bacteriace^. — Possessing mostly cocci, rods (straight 

 or bent), and thread-forms (straight or spiral). The first may be absent, 

 and the last possess no distinction between base and apex. Division (as 

 far as is known) occurs only in one direction. 

 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-formation present either in rods or cocci. 

 Genus V. Vihrio. — Threads screw-form in long or short links. Spore- 

 formation present. 

 Genus VI. Clostridium. — Same as bacillus, but spore-formation takes 



place in characteristically enlarged rods. 



Group III. Leptotriche^. — Possessing cocci, rods, and thread- 

 forms (which show a distinction between base and apex). The last 

 straight or spiral. 

 Genus I. Crenothrix. — Threads articulated ; cells sulphurless ; habitat 



water. 

 Genus II. Beggiatoa. — Threads unarticulated ; cells with sulphur 



granules ; habitat water. 

 Genus III. Phragmidiothrix. — Threads jointless ; successive subdivision 



of cells is continuous ; cells sulphurless ; habitat water. 

 Genus IV. Leptothrix.^-HhTeadis articulated or unarticulated ; successive 



subdivisions of cells not continuous ; cells sulphurless. 



Group IV. CLADOTRiCH.ffiE. — Possessing cocci, rods, threads, and 

 spirals. Thread-forms provided with false branchings. 

 Genus : — Cladothrix. 



