t 20 Marshall Ward . — On the Characters , 
(y) Filaments straight or undulate, and with endospores. 
(i) Rodlets not altered in shape during sporification. 
Bacillus. 
(ii) Rodlets fusiform, or undergo some changes in 
shape as spores form. 
Clostridium. 
B. No filaments, but spindle-shaped rods which undergo division 
in the longitudinal direction, and develope endospores. 
Pasteuria. 
C. Filaments, differentiated into base (usually fixed) and apex. 
(a) Filaments not distinctly septate or divided, and without 
sheath. 
(i) Devoid of sulphur granules. 
Leptothrix. 
(ii) Containing sulphur granules. 
Beggiatoa. 
(0) Filaments segmented and sheathed. 
(i) Unbranched. 
Crenothrix . 
(ii) Branched (false branches). 
Cladothrix. 
III. Vegetative stage consisting of spiral filaments or segments, flexile 
or rigid. 
(a) Arthrosporous only. 
Spirochaete . 
(0) Endosporous. 
(i) No alteration in form of the sporogenous cells. 
Spirillum. 
(ii) The cell changes in shape as the spores are 
developed. 
Vibrio. 
The main advances in the De Bary-Hueppe scheme are, 
besides the distinct one of the employment of the spore- 
characters, the much clearer rendering of the diagnoses derived 
from the vegetative forms, and the embracing of the new types 
Clostridium of Prazmowsky, and (subsequently) Pasteuria of 
Metschnikoff. There is also a much more thorough analysis 
of the various forms allied to Micrococctis , though the diffi- 
