sulfur globules. Color of protoplasm not recorded.
Habitat: Mud and stagnant water containing hj'-drogen sulfide and exposed to light. Probably widely distributed, but less frequently recorded as the organism is not so spectacular as the large Thiospirillum jenense and Thiospirillum sanguineum.
Illustration: Warming, op. cit., 1876, Pl. X, fig. 12.
5. Thiospirillum rufum (Perty, 1852) Migula, 1900. (Spirillum rufum Perty, Bern, 1852, 179; Migula, Syst. d. Bakt. 2, 1900, 1050.)
ru′fum. L. adj. rujus red, reddish.
General characteristics presumably those of the genus, although it does not appear either from Perty's description or from that of Migula (loc. cit.), Bavendamm (Die farb losen und roten Schwefelbakterien Jena, 1924, 132) or Huber-Pestalozzi (Die Binnengewässer, 16, Heft 1, Das Phytoplankton des Süsswassers, Stuttgart, 1938, 304) that the cells ever contain sulfur globules. Only the red color is emphasized. Consequently, it is quite possible that this organism belongs in the genus Rhodospirillum.
Cells 1.0 by 8 to 18 microns; coiled to occupy 1½ to 4 turns, the latter commonly 4 microns wide by 4 microns long. These dimensions agree with those of Rhodospirillum ruhrum (Esmarch) Molisch, and it seems probable that the two organisms are identical.
Habitat: Found in red slime spots on the side of a well. Mud and stagnant bodies of water.
Illustration: Migula, Syst. d. Bakt., 1, 1897, Pl. III, fig. 7.
Genus XI. Rhabdomonas Cohn, 1875.
(Cohn, Beitr. Biol. Pfl., 1, Heft 3, 1875, 167; Rhabdochromatium Winogradsky, Schwefelbacterien, Leipzig, 1888, 100.)
Rhab.do.mo′nas. Gr. noun rhabdus a rod; Gr. noun monas a unit, monad; M.L. noun Monas a protozoan genus; M.L. fem. n. Rhabdomonas the rod monad.
Sulfur purple bacteria, as a rule occurring singly in the form of rather irregular, long rods to filaments, exhibiting more or less pronounced swellings, or club and spindle shapes. Filamentous structures, sometimes with constrictions, giving the filament the appearance of a string of beads. These may be surrounded by a relatively inconspicuous slime capsule which can be rendered visible by India ink. The less distorted cell types are frequently motile by means of polar flagella. Produce bacteriochlorophyll and carotenoid pigments, coloring the cells pinkish to purplish red. Capable of photosynthesis in the presence of hydrogen sulfide and then storing sulfur globules as an intermediate oxidation product inside the cells.
The status of this genus is doubtful. Winogradsky (loc. cit.) recognized the similarity of its members to species of Chromatium and the occurrence of many intermediate forms which make a sharp distinction between the two genera impossible. He preferred the designation of Rhabdochromatium as a sub-genus. Warming (Videnskab. Meddel. naturhist. Foren., Kjöbenhavn, 1876, 320 ff.), Nadson (Bull. Jard. Impér. Bot. St. Pétersb., 3, 1903, 116), van Niel (Arch. f. Mikrobiol., 3, 1931, 61) and Ellis (Sulphur Bacteria, London and New York, 1932, 151) considered the species of Rhabdochromatium as abnormal growth forms (involution forms) of corresponding species of Chromatium, while Lauterborn (Verhandl. natur-histor.-medizin. Vereins, Heidelberg, N.F., 13, 1915, 424), Buder (Jahrb. wiss. Bot., 58, 1919, 534) and Bavendamm (Die farblosen und roten Schwefelbakterien, Pflanzenforschung, Heft 2, 1924, 129) favor generic rank.
The type species is Rhahdomonas rosea Cohn.
Key to the species of genus Rhabdomonas.
I. Cells not containing calcium carbonate inclusions in addition to sulfur globules.
- A. Cells more than 3 microns in width.
1. Rhabdomonas rosea.
