152 SULPHUR BACTERIA 



Found in marine and fresh waters containing sulphuretted 

 hydrogen in solution. 



Rhabdochromatium minus (Winogradsky). 



Literature. — Winogradsky (2), 1888. 



A smaller variety than the preceding, which it otherwise 

 resembles. Length, 5 — lO/x; maximum thickness, 2 — 9/m. 

 Colour, rose-red. 



Rhabdochromatium gracile (Warming), Migula. 



Literature. — Warming, 1875 ; Migula (3), 1900 ; Baven- 

 damm, 1924. 



This is the Monas gracile of Warming, which was changed 

 to its present name by Migula. 



Rod-shaped cells, in which one -end is frequently thicker 

 than the other. Length, up to 6o/x. Colour, rose-red. Found 

 in a fresh-water pond near Copenhagen. 



Rhabdochromatium linsbaueri (Gicklhorn). 



Literature. — Gicklhorn (2), 1921 ; Bavendamm (i), 1924. 



This species differs from Chromatium Linsbaueri in being 

 spindle-shaped, and in being destitute of the slime patches 

 which are characteristic of that organism. As in other 

 respects the two forms agree, and as the marks of difference are 

 probably of a fugitive and unstable character it is highly 

 probable that the two organisms are both varieties of the same 

 species. This variety is described as being 30yu, long and 3 — 4/x 

 broad ; it is propelled by a cilium 20 — 30/x long. The colour 

 is wine-red. The cell contains calcium carbonate as well as 

 sulphur granules. 



Habitat. — Found in a small pool near Graz (Austria). 



Genus 2. — Thioporphyra (Ellis). 



Literature. — Ellis (9), 1926. 



Genus with one species. Cells spherical, or ovoid, motile. 

 Movement by one large cilium which is probably compound. 

 Colour from violet to mauve. Reproduction by transverse 

 fission, by budding, and possibly by endospores. 



