122 Marshall Ward ’ — On the Characters , 
A. Cocci and rodlets, or only rodlets known, and arranged in 
linear series or filaments. No spores known. 
Bacterium. 
B. Filaments spiral : segmented into rodlets (long or short), or 
into rodlets and cocci. No spores known. 
Spirillum. 
C. Filaments spiral, and forming spores in the long or short 
segments. 
Vibrio. 
D. Develope cocci and rodlets, the former containing spores. 
Leuconostoc. 
E. Rodlets, or rodlets and cocci, in linear or spiral filaments. 
Spores developed in the rodlets or in cocci. 
Bacillus. 
F. As Bacillus , excepting that the sporogenous rodlets are 
peculiarly swollen. 
Clostridium. 
III. Leptotricheae. 
Filaments, which are differentiated into base and apex, and may be 
linear or spirally curved, segmented into rodlets and cocci. Spores 
unknown. 
A. Filaments sheathed. Cells without sulphur-granules. Aquatic 
forms. 
Crenothrix. 
B. Filaments not sheathed. The segments with sulphur-granules. 
Aquatic. 
Beggiatoa. 
C. Filaments not sheathed, and much divided up by numerous 
successive septa. No sulphur granules. Aquatic. 
Phragmidothrix. 
D. Filaments sheathed or not; segmentation not remarkable. 
Cells devoid of sulphur granules. 
Leptothrix. 
IV. Cladotricheae. 
Filaments falsely branched. Breaking up into cocci, rodlets, and 
straight and coiled filamentous segments. No spores 1 known, 
Cladothrix. 
1 This is no longer the case according to Billet, 
