GENERAL SYSTEMATIC BACTERIOLOGY 41 



c. Filaments fixed. Cell division transverse and longitudinal. 



Phragmidiothrix Engler. 

 cc. Filaments free, division transverse only. 



Beggiatoa Trev. 



Key to Tribes and Genera of the Subfamily Baculogenae Trev. 



a. Bacilli and cocci naked, never with a tegument. 



Tribe I. Bacilleae Trev. 

 b. Producing endospores: 



c. Division longitudinal .. Subtribe I. Pasteurieae Trev. 



One genus only Pasteuria Metch. 



cc. Divisions transverse: 



d. Rods united in a reticulate coenobium: 



Subtribe II. Thiodictyeae 



One genus only Thiodictyon Winogradsky 



dd. Rods not united in reticulate coenobium. 



e. Rods straight or slightly bent, never spiral. 

 Subtribe III. Eubacilleae Trev. 

 f . Spores not greater in diameter than normal vegeta- 

 tive rods, 

 g. Spores forming in unchanged rods : 



h. Plasma uniformly diffused in rods: 

 i. Rods fusiform. 



Mantagazzaea Trev. 

 ii. Rods cylindrical or cylindraceous. 

 Bacillus Cohn 

 hh. Plasma bipolar in distribution. 

 Pasteurella Trev. 

 gg. Spores with special integuments, cells be- 

 coming ellipsoid-fusiform : 



Clostridium Praz. 

 ff . Spores greater in diameter than the normal vegeta- 

 tive rods. 



g. Spores median in unchanged rods. 

 Cornilia Trev. 

 gg. Spores apical in clavate rods. 

 Vibrio Zopf. 

 ee. Rods spirally bent. 



Subtribe IV. Spirilleae Trev. 

 f. Rods circular in cross section. 



Spirillum Ehr. 

 ff. Rods compressed in cross section. 



Spiromonas Perty 

 bb. Producing arthrospores : 



c. Cylindrical, straight or slightly curved. Filaments undulate — 

 flexuous or irregularly pseudospiral. 



Pacinia Trev. 



