GENERAL SYSTEMATIC BACTERIOLOGY 67 



1. Cells cylindric-elliptic or elliptic. Moderately thick. Polar 



flagella Chromatium Perty 



2. Cells rod shaped or spindle form, flagella at poles. 



Rhabdochromatium Winogr. 



3. Cells spirally twisted Thiospirillum 



Beijerinck (1900) suggested the generic natne Aerohacter to include 

 the gram negative lactic acid and gas producing rods of the B. lactis 

 aerogenes and coli types. Hartleb (1900) designated an organism from 

 a root nodule as Pseudorhizobium, and Lagerheim named a bacterium 

 found parasitic upon certain sea weeds, Sarcinastrum. 



Chester (1901) in his Manual of Determinative Bacteriology used 

 the following family and generic keys: 



Chester's Key to the families of Bacteria (1901) 



I. Cells unbranched, or show only a false branching in Cladothrix: 



A. Cells in their free condition globular, becoming slightly elongated 



before division. Cell division in one, two, or three directions of 

 space Coccaceae 



B. Cells short or long, cylindrical, straight, curved, or spiral. Without a 



sheath surrounding the chain of individuals; motile or non-motile; 

 endospores present or absent Bacteriaceae 



C. Cells surrounded by a sheath, and arranged in elongated filaments. 



Chlamydobacteriaceae 



D. Cells not surrounded by a sheath, arranged in elongated filaments, and 



motile by means of undulating membrane. 



Beggiatoaceae 

 II. Cells short or long, cylindrical or filaments, often clavate; cuneate or irregu- 

 lar in form. Without endospores, but with the formation of gonidia-like 

 bodies due to the segmentation of the cells. Without flagella. Division 

 at right angles to the axis of a rod or filament. Filaments not surrounded 

 by a sheath as in Chlamydobacteriaceae. With true dichotomous branching. 



Mycobacteriaceae 



Key to Genera of the Coccaceae 



A. Cells without flagella : 



1. Division in one direction of space only. 



Streptococcus Billroth 



2. Division in two directions of space.il/icrococcws Hallier 



3. Division in three directions of space. 



Sarcina Goodsir 



B. Cells with flagella: 



1. Division in two directions of s'pa.ce . Planococcus Migula 



2. Division in three directions of space. 



Planosarcina Migula 



