90 



GENERAL BACTERIOLOGY 



2. Cells with polar fla- 



gella- tufts, - -11. Spirillum EHRENB. 



B. Cells flexuous, - - 12. Spirochaeta EHRENB. 



(3) Cells inclosed in a sheath. CHLAMYDOBACTERIACEAE 



MlGULA. 



A. Cell contents without gran- 

 ules of sulphur. 



a. Cell threads unbranched. 

 1). Cell division always 



only in one plane, - 13. Streptothrix COHN. 



2 ) . Cell division in three 

 planes previous to 

 the formation of co- 

 nidia. 



i). Cells surrounded 

 by very delicate, 

 scarcely visible 

 sheath (marine). 



ii). Sheath clearly 

 visible ( fresh wa- 

 ter), - 



&. Cell threads branched, 



B. Cell contents containing sul- 

 phur granules. 



14. Phragmidiothrix ENG- 

 LER. 



15. Crenothrix COHN. 



16. Cladothrix COHN. 



17. Thiothrix WINOGRAD- 



SKY. 



(4) Cells destitute of a sheath, 

 united into threads mo- 

 tile by means of an un- 

 dulating membrane. BEGGIATOACEAE TREVISAN. 



Only one genus, - - - 18. Beggiatoa TREVISAN. 



