270 LABORATORY EXERCISES IN\ BACTERIOLOGY. 



flfci 



(c) Cells without flagella ; division in three planes 



to form packets of eight or geometric mul- 

 tiples, Genus: Sarci-na. 



(d) Cells with flagella; division into separate 



individuals, Genus: Planococcus. 



(e) Cells with flagella; arranged in sarcina 



packets, Genus: Planosarcina. 



II. Cells short or long, straight, cylindric ; separate 



or in chains; without sheath surrounding 

 chains ; with or without endospores ; motile or 

 non-motile; with or without flagella, Family: Bacteriaceae. 



(a) Cells without flagella ; endospores present or 



absent, Genus : Bacterium. 



(b) Cells with flagella; peritrichous; endospores 



present or absent, Genus : Bacillus. 



(c) Cells with flagella, polar; endospores usually 



absent, Genus: Pseudomonas. 



III. Cells more or less spirally curved; division 

 transverse to long axis of cells ; usually without 

 endospores; with or without flagella, usually 



polar, Family : Spirillaceae. 



(a) Cells rigid, comma-shaped to spiral; non- 

 motile, without flagella ; without known endo- 

 spores; cells single or in zooglea, Genus: Spirosoma. 



(b) Cells rigid, usually weakly curved comma- 

 shaped or short spirals; each cell with one 

 (rarely two or three) polar flagellum ; endo- 

 spores unknown, Genus : Micros pira. 



(c) Cells rigid, comma-shaped or spiral, of vari- 

 able thickness; cells actively motile with a 

 bunch of four or more flagella at one or both 



poles ; a few forms with endospores, Genus : Spirillum. 



(d) Long, slender filaments; cells flexile; undu- 

 latory or snake-like movement not progressive 

 or about the long axis ; flagella not known ; 



endospores apparently absent, Genus: Spiroch&ta. 



IV. Cells either short or long, cylindric-clavate- 

 cuneate in form, sometimes showing true 

 branching, or as long, branched mycelial-like 

 filaments; filaments not surrounded by a 

 sheath; without endospores, but with forma- 

 tion of gonidia-like bodies by transverse seg- 

 mentation of rods or filaments, Family: Mycobacteriaceae. 



(a) Cells ordinarily short cylindric rods, often 

 bent, irregularly swollen, clavate or cuneate, 

 sometimes in Y-shaped forms or in longer 

 filaments with true branchings; without 

 flagella ; without endospores, but may present 

 short coccoid elements, perhaps gonidia, Genus: Mycobacterium. 



