172 SULPHUR BACTERIA 



warrant the removal of both these organisms from a general 

 scheme of classification. 



The Thiopolycoccus ruber of Winograclsky is composed of 

 small cells closely pressed together and non-motile. They are 

 spherical, l-2/x in diameter, and intensely red in colour. 



Family 7. — Thiopediace.e (Winogradsky). 



Literature. — Oerstedt (i), 1840 and 1841 ; Rabenhorst 



(2), 1865; Warming, 1875; Winogradsky (i), 1887; 



Utermohl (i), Migula (3), 1900 ; Kolkwitz (3), 1909; 



Bavendamm, 1924. 



Description. — The single species of which this family is 

 composed has been known for ninety years. Oerstedt named 

 it Erythroconis littoralis, but its best-known earlier name was 

 Merismopedia littoralis. Warming was of the opinion that it 

 was either a variety of Bacterium sulfuratum, or a small colony 

 of Clathrocystis. In Migula's classification Merismopedia 

 littoralis was placed among the sulphur bacteria. It was 

 regarded as identical with the Thiopedia rosea described by 

 Winogradsky, and so the term Merismopedia was dropped 

 and the term Thiopedia took its place. The genus Merismo- 

 pedia of to-day belongs to the Cyanophycece. The American 

 Society of Bacteriologists has rejected Thiopedia as an in- 

 dependent genus. Its rejection is not justified, because the 

 regularity of formation of the plates of cells is a striking 

 feature, which is absent from all the other genera of the sulphur 

 bacteria, and the regularity indicates a first step towards the 

 colonial habit. This organism is thus essentially different 

 from the other slime-enclosed bacteria in which the association 

 of the component cells is accidental and in which the cells 

 behave as independent units. 



Genus i. — Thiopedia (Winooradsky). 



Literature. — As for family. 



Thiopedia rosea. 



Globular cells, i-i — 2/x in diameter, and arranged in 

 the slime in regular plates. Later, the regular arrangement 



