264 LABORATORY EXERCISES IN BACTERIOLOGY. 



shaped, unbranched forms without definite envelope ; (III) Spirillacece, curved or spiral 

 rods, unbranched, without envelope; (IV) ^Iycobacteriace<s, rod forms, often with 

 irregularly clubbed ends, sometimes forming filaments, showing some individuals 

 with true branching, usually straight, but sometimes slightly curved ; and (V) Chlamido- 

 bacteriacea, filamentous bacteria composed of rod-shaped cells and surrounded by a 

 distinct sheath, without granules in the cell contents. 



The thiobacteria are divided by Migula into two families: (I) Beggiatoacea, fila- 

 mentous bacteria containing sulphur granules in the cell contents; and (II) Rhodo- 

 bacteriacefe, non-filamentous, with bacteriopurpurin or sulphur granules, red or violet 

 in color, in the cell contents. The latter family is further divided into five subfamilies : 

 (A) Thiocapsacece, cell division in three planes; (B) Lamprocystacea, cell division first 

 in three, then in two planes; (C) Thiopedacece, cell division in two planes; (D) Amebo- 

 bacteriacece, cell division in one plane; (E) Chromateaceos. 



The following synopsis of the order indicates the relations of the suborders, families, 

 and genera: 



Order: SCHIZOMYCETES. 



(A) Suborder: EUBACTERIACE^ (without colored granules in cell contents; un- 

 colored except in a very few species, then faintly, generally green). 



I. Family: Coccaceae (globular, becoming slightly elongated before cell division; 



cell division in one, two, or three directions). 



(a) Genus: Streptococcus (cell division in one direction, united in chains, 

 non -flagellated) . 



(b) Genus: Micrococcus (cell division in one, two, or three directions with 

 separation of cells; non-flagellated). 



(c) Genus: Sarcina (cell division in three directions, united in packets of 

 eight; non-flagellated). 



(d) Genus: Planococcus (cell division in one, two, or three directions, cells 

 separate; flagellated). 



(e) Genus: Piano sarcina (cell division in three directions, cells united in 



packets of eight; flagellated). 



II. Family: Bacteriaceae (cells straight, cylindric, short, oval to rods and fila- 



ments; without sheath; no true branching; with or without flagella). 



(a) Genus: Bacterium (cells straight, cylindric, oval to rods or filaments; 

 non-motile, without flagella; endospores present or absent). 



(b) Genus: Bacillus (cells straight, cylindric, oval to rods or filaments; motile, 



with flagella varying in number, peritrichous ; endospores present or 

 absent). 



(c) Genus: Pseudomonas (cells straight, cylindric, occasionally in short fila- 



ments; motile, flagella monotrichous or amphitrichous; endospores 

 known in only a few species). 



III. Family: Spirillaceae (cells more or less curved; cell division transverse to 



long axis of cells; usually without endospores; with or without flag- 

 ella; flagella few, monotrichous or amphitrichous). 



(a) Genus: Spirosoma (cells rigid, without flagella). 



(b) Genus: Microspira (cells rigid; one, rarely two or three polar flagella). 



(c) Genus: Spirillum (cells rigid; a bundle of polar flagella). 



(d) Genus: Spirochceta (cells flexile, sinuous). 



