58 GENERAL SYSTEMATIC BACTERIOLOGY 



Key to the Genera of the Bacteriaceae 



A. Flagella absent, endospores present or absent 



Bacterium Ehr. 



B. Flagella present : 



1. Flagella arising from any part of the body, peritrichic 



Bacillus Cohn 



2. Flagella attached to one or both poles. 



Pseudomonas Migula 



Key to the Genera of the Spirillaceae 



I. Cells stiff, not flexile: 



A. Without flagella Spirosoma Migula 



B. With flagella. 



1. With 1, rarely with 2 or 3 polar flagella. 



Microspira Schroeter 



2. With a bundle of polar flagella Spirillum Ehr. 



II. Cells flexile Spirochaeta Ehr. 



Key to the Genera of Mycobacteriaceae 



Cells either short or long, cylindrical — clavate — cuneate in form, which at times 

 may show true branching, or as long-branched mycelial-like filaments. Fila- 

 ments not surrounded by a sheath as in Chlamydohacteriaceae. Without 

 endospores, but with the formation of gonidia-like bodies due to a segmentation 

 of the cells. Division at right angles to the axis of a rod or filament. 



A. Cells in their ordinary form short cylindrical rods, often bent and 



irregularly swollen, clavate or cuneate. At times Y-shaped forms 

 or longer filaments with true branchings. May produce short 

 coccoid elements, perhaps gonidia Mycobacterium (Lehmann-Neu- 

 mann), including Corynebacterium (Lehmann-Neumann). 



B. Cells in their ordinary form as long-branched filaments. Produce 



gonidia-like bodies. Cultures generally have a mouldy appearance 

 due to the development of aerial hyphae. Streptothrix (Cohn); 

 Oospora (Lehmann-Neumann). 



Key to the Genera of Chlamydobacteriaceae, 



Filamentous bacteria composed of rod-shaped cells, and surrounded by a distinct 

 sheath. Division of the cells at right angles to the axis of the filaments. In 

 Phragmidiothrix and Crenothrix, however, in the formation of gonidia, a division 

 of the cells in three directions of space takes place. Reproduction by means 

 of gonidia, which are either motile or non-motile: 

 I. Cell contents without sulfur granules: 

 A. Filaments unbranched: 



1. Cell division takes place in one direction of space. 



Leptothrix 



