RHODO-THIOBA CTERIA 



i6i 



necessary to conform to the system which has been adopted 

 in this book. Hence the term Thiospirillum is restricted to 

 uncoloured organisms, whilst the term Rhodothiospirilhim is 

 reserved for the coloured ones. Winogradsky's genus includes 

 the spirilla described by Perty, 1852, and by Warming, 

 1875 ; and also Ehrenberg's two species Ophido7nonas jenensis 

 and Ophidomonas sangidnea (1838) (Fig. 37). 



Rhodothiospirillum jenense (Ehrenberg), Ellis. 



Literature. — Ehrenberg (2), 1838; Cohn (7), 1872; Biitschli 

 (i), 1890, and (4), 1892; Zettnow (2), 1897; Zopf (2), 

 1885; Migula (3), 1900; Buder (2), 1915; Metzner, 

 1920 ; Bavendamm, 1924. 



Description. — Ehrenberg gave the name Ophidomonas 

 jenense to this organism, but it was changed by Winogradsky 

 to Thiospirillum jenense, and 

 for the reasons which are 

 given above it is now again 

 changed to Rhodothiospiril- 

 lum. Possibly some, if not 

 all, of the coloured spirilla 

 may be phases in the life- 

 history of some pleomorphic 

 organismlike Beggiatoa roseo- 

 persicina, for practically all 

 the spirilla have been named 

 from observations of the 

 adult specimens, without 

 reference to their life- 

 history. 



Fig. 38. — Rhodothiospiyillum jenense. 



Family 4. — Rhodocaps.acem. 



Free cells, spiral, rod-shaped, or globular, surrounded by 

 a capsule of slime. On Hberation from slime the cells may 

 become motile. One genus with aerosomes. 



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