CLASSIFICATION 35 



Genus . SPIROCHAETE Ehrenberg. Cells long and 

 attenuated, spirally twisted with numerous turns ; cilia un- 

 known; the cell membrane is perhaps yielding. Spirochaete 

 Obermaieri (remittent fever). 



ORDER 2. TRICHOBACTERINAE. 



Vegetative phase an unbranched or branched fila- 

 ment or chain of cells, the individual members of which 

 break off as swarm-spores (gonidia). 



FAMILY 1. TRICHOBACTERIACEAE. 



(a) Filaments non-motile, rigid, enclosed in a sheath. 

 Genus CRENOTHRIX Cohn. Filaments unbranched and 



devoid of sulphur granules. 



Genus THIOTHRIX Winogradsky. The same, but con- 

 taining sulphur granules. 



Genus CLADOTHRIX Cohn. Filaments branched, false 

 dichotomy (includes Sphaerotilus). 



(b) Filaments motile, with oscillating and gliding 

 movements, and devoid of a sheath. 



Genus BEGGIATOA Trevisan. Containing sulphur. 



Grouping of bacteria according to their habitat and 

 properties. Bacteria are often referred to by names indi- 

 cative of their habitat or some property which they possess 

 or the nature of their special activities. The more com- 

 monly used of these group names are as follows : 



Saprophytic bacteria. These are bacteria which nor- 

 mally live on dead organic matter and which do not pos- 

 sess the power of multiplying in living tissues. They are 

 the organisms ordinarily found in the soil, decaying vegeta- 

 tion or decomposing animal tissues. 



Parasitic bacteria. These are bacteria which have their 

 natural habitat on or in the living body. As the line of de- 

 marcation between pathogenesis and parasitism is not 



