THE CLASSIFICATION OF BACTERIA 379 



2. Thiothrix nivea (Rabenhorst) Winogradsky 



Beggiatoa nivea Rabenhorst : Kryptogamen flora, I. 

 Thiotrix nivea Winogradsky : I.e. 



Filaments with a thin sheath, 2-2.5 f- broad at the base, and 1 .4-1.5 fi broad 

 at the apex; often 100 fi long, segmented at the apex, producing motile 

 gonidia 8-9 /u. long. 



Habitat. Found in sulphur and stagnant water. 



3. Thiothrix tenuis Winogradsky 



Filaments very long, and about 1 .0 in diameter. 

 Habitat. Found in sulphur water. 



BEGGIATOACEjE Migula 



Filamentous bacteria. Filaments without sheaths, but with motility like Os- 

 cillatoria by means of an undulating membrane. The cell contents show 

 the presence of sulphur granules. The formation of gonidia not known. 



BEGGIATOA Trevisan 



Prospetto della Flora Euganea, 1842, 76. 



Filaments apparently not segmented except when stained with iodine. Color- 

 less, or faintly rose-colored. 

 I. Filaments colorless. 



A. Filaments 3-4 microns thick. 



1. Beggiatoa alba (Vaucher) Trevisan. 



B. Filaments 7 microns thick. 



2. Beggiatoa arachnoidea (Agardh) Regensburger. - 



C. Filaments 16 microns thick. 



3. Beggiatoa tnirabilis Cohn. 

 II. Filaments colored reddish-violet. 



4. Beggiatoa roseopersicina Cohn. 



1. Beggiatoa alba (Vaucher) Trevisan 



Flora Euganea, 1842. 



Filaments long, 3-4 \x. thick, containing numerous strongly refracting granules 

 of sulphur. Filaments break up into short segments, which then grow 

 out into longer threads. Sulphates reduced to HS and to free sulphur. 



