56 BA CTERIOLOG Y. 



of variable thickness and length, frequently 

 forming long spirals. Endospore formation 

 has been observed in a few species. The 

 cells are motile and possess flagella at one 

 or both poles. 



4. Genus: Spirochceta. Cells of spiral form, 

 thin but usually quite long, motile and flexi- 

 ble, snake-like but also screw-like in motion. 

 Motile organs are unknown. Endospo re- 

 formation has not been observed. 

 4. Family: Chlamydobacteriacexje. 



Cells cylindrical and thread forms, surrounded 

 with a sheath. Multiplication results through 

 motile and non-motile gonidia which arise 

 directly from vegetative cells and develop into 

 threads. 



1. Genus: Chlamydothrlx. Cells cylindrical, 



non-motile, enclosed in a sheath. Fre- 

 quently the sheath is only apparent upon 

 applying reagents. Multiplication through 

 non-motile round or ovoid gonidia that are 

 derived directly from the vegetative cells. 

 Synonyms : Streptothrix (Cohn, Migula) ; 

 Leptothrix (Kiitzing). 



2. Genus: Grenothrix (Cohn). Thread-form 



bacteria without branching, attached at one 

 end, showing a differentiation of base and 

 apex, and increasing in thickness toward 

 the free end. Sheath rather thick. The 

 sheaths of old threads in waters containing 

 iron are saturated with oxide of iron. The 

 cells are cylindrical, sometimes flattened. 

 Multiplication through non-motile gonidia, 



