FAMILY I. THIORHODACEAE 



51 



crude cultures, have been greatly strengthened by studies with pure cultures of species of 

 Chromatium. Thus van Niel (Arch. f. Mikrobiol., 3, 1931, 59) reported variations in width 

 from 1 to 4 microns, and in length from 2 to 10 microns or even up to 50 microns; Manten 

 (Antonie van Leeuwenhoek, 8, 1942, 164 S.) found size differences of 1 to 14 microns with a 

 pure culture of an organism that he identified as Chromatium okenii. Often the differences 

 in size of a pure culture can be related to special environmental conditions. On account of 

 such results a designation of species on the basis of size relations alone is manifest)}^ un- 

 satisfactory. Moreover, the available data do not suggest that differences in shape, color or 

 arrangement of sulfur globules can be used more effectively. Lack of adequate experimental 

 results with a sufficiently large number and variety of pure cultures prevents a more rational 

 classification at present. 



The previously proposed species have been listed below with their respective character- 

 istics and arranged as far as possible in the order of decreasing width. 



Two Chromatium species have been described as containing inclusions of calcium carbon- 

 ate in addition to sulfur globules. As in the case of Rhabdomonas linsbaueri, it is not known 

 w'hether this feature may be a direct consequence of the calcium ion content and pH of the 

 environment and thus fail to have taxonomic significance. 



The type species is Chromatium okenii Perty. 



1. Chromatium gobii Issatchenko, 1914. 

 (Recherches sur les microbes de I'oc^an 

 glacial arctique, Petrograd, 1914, 253.) 



go'bi.i. M.L. gen.noun gobii of Gobi; 

 named for Prof. X. Gobi. 



Cells 10 microns by 20 to 25 microns. 



Source: From sea water of the Arctic 

 Ocean. 



Habitat: Presumably ubiquitous in the 

 colder portions of the Ocean at least. 



Illustration: Issatchenko, loc. cit., PI. II, 

 fig. 12. 



2. Chromatium warmingii (Cohn, 1875) 

 Migula, 1900. (Monas warmingii Cohn, 

 Beitr. Biol. Pfl., i. Heft 3, 1875, 167; Migula, 

 Syst. d. Bakt., 2, 1900, 1048.) 



war.min'gi.i. Named for Eugene Warm- 

 ing, a Danish botanist; M.L. gen.noun 

 warmingii of Warming. 



Cells 8 by 15 to 20 microns, also smaller 

 (Cohn). 



Illustration: Cohn, op. cit., 1875. PI. VI, 

 fig. 11. 



3. Chromatium linsbaueri Gicklhorn, 

 1921. (Ber. d. deut. botan. Ges., 39, 1921, 

 312.) 



lins.bau'er.i. Named for K. Linsbauer, an 

 Austrian botanist; M.L. gen.noun linsbaueri 

 of Linsbauer. 



Cells 6 by up to 15 microns (Gickl- 

 horn) ; 6 to 8 microns in width (Ellis, Sul- 

 phur Bacteria, London and New York, 1932, 



147) . Special characteristic is the occurrence 

 of calcium carbonate inclusions. Otherwise 

 resembles Chromatium okenii. 



Source: From a pool in the Stiftingtal, 

 near Graz, Austria. 



Habitat: Fresh water. 



Illustrations: Gicklhorn, op. cit., 1921, 

 314, fig. 1; Ellis, op. cit., 1932, 148, fig. 31. 



4. Chromatium okenii (Ehrenberg, 

 1838) Perty, 1852. {Monas okenii Ehrenberg, 

 Infusionsthierchen, Leipzig, 1838; Perty, 

 Zur Kenntniss kleinster Lebensformen, 

 Bern, 1852, 174.) This is the type species of 

 genus Chromatium. 



o.ke'ni.i. Named for L. Oken, a German 

 naturalist; M.L. gen.noun okenii of Oken. 



Cells 5.6 to 6.3 by 7.5 to 15 microns 

 (Cohn) ; minimum width 4.5 microns (Issat- 

 chenko, Borodin Jubilee Vol., 1929?, 8); 

 with many transitions to Chromatium weis- 

 sei (Winogradsky, Schwefelbacterien, Leip- 

 zig, 1888, 92). Also: 3.5 by 8 to 12 microns 

 and varj'ing in size from 1 to 15 microns 

 (Manten, Antonie van Leeuwenhoek, 8, 1942, 

 164). 



Illustrations: Cohn, Beitr. Biol. Pfl., 1, 

 Heft 3, 1875, PI. VI, fig. 12; Winogradsky, 

 op. cit., 1888, PI. IV, fig. 3-4; Issatchenko, 

 Recherches sur les microbes de I'ocean 

 glacial arctique, Petrograd, 1914, PI. II, 

 fig. 9. 



5. Chromatium weissei Perty, 1852. 



