108 GENERAL SYSTEMATIC BACTERIOLOGY 



Key to the Families of the Thiobacteriales 



The keys to the subgroups and genera of this order are the same in general as 

 those of Buchanan (1917-18) q.v. 



Key to the Families of the Order Myxobacteriales 



One family only: Myxobacteriaceae. 



Key to the Genera of Family Myxobacteriaceae 



I. Rods transformed into coccus-like spores when encysted, sessile or stalked 



masses of coccus-like spores Myxococcus 



II. Cells not transformed into coccus-like spores when encysted. 



A. Rods forming large, rounded cysts, one or more within a gelatinous 



matrix raised above the substratum. . . . Polyangium 



B. Rods forming cysts in which they remain unmodified. Cysts various, 



sessile or borne on a more or less highly developed cystophore. 



Chondromyces 



Key to the Families of the Order Spirochaetales 



One family only: Spirochaetaceae. 



Key to the Genera of Family Spirochaetaceae 



A. Usually saprophytic, free-living in water. 



1, Protoplasm spirally wound around an elastic axis filament. 



Spirochaeta 



2. Cross section circular Saprospira 



B. Usually parasitic. 



1. Possessing a "crest" or ridge. Parasitic in mussels. 



Cristispira 



2. Without crest. Parasitic in warm blooded animals and in man. 



Spironema 

 Treponema 



3. Short, sharply twisted spirals. Parasitic in rodents and in man. 



Leptospira 



