FAMILY ACHROMATIACEAE 



999 



1. Achromatiuni oxaliferum Schewia- 

 kofl". (Schewiakoff, Ub. einen neuen 

 bacterienahnlichen Organismus des Siiss- 

 wassers, Habilitationsschrift, Heidel- 

 berg, 1893; Modderula hartwicji Frenzel, 

 Biol. Centralbl., 17, 1897, 801; Hillhousia 

 mirabilis West and Griffiths, Proc. Roy. 

 See, B, 81, 1909, 389; Hillhousia paliis- 

 tris West and Griffiths, Ann. Bot., 27, 

 1913, 83; Achromatiuni gigas Nadson, 

 Bull. Jard. Imp. Bot., St. Petersb., 13, 

 1913, 106). From Latin oxalis, intended 

 to refer to the supposed presence of 

 oxalate crystals and/cro, to bear. 



Unicellular organisms, varying in 

 shape from spherical or ovoid to shortly 

 cylindrical with hemispherical extremi- 

 ties. Division by constriction in the 

 middle. Cells var}' in size from spheres 

 of about 7 microns or even less in diam- 

 eter to giant forms 100 microns long by 

 35 microns wide. The extremes are con- 

 nected by a continuous series of inter- 

 mediate sizes. 



Organisms maj- show motility of a 

 jerky and rotating kind, always very 

 slow, and dependent upon a substrate. 

 Typical organs of locomotion absent. 



Normally contain small sulfur glob- 

 ules, accompanied by much larger cal- 

 cium carbonate crj'stals, the latter in the 

 form of large highly refractile spherules. 

 Under favorable environmental condi- 

 tions these may disappear before the 

 sulfur globules. Cells with calcium car- 

 bonate inclusions have a very high 

 specific gravity. They are, therefore, 



found only in the bottom of pools, 

 streams, etc., usually in the mud. 



Strictly microaerophilic, and appar- 

 ently require hydrogen sulfide. 



Habitat : Fresh water and brackish mud 

 containing hydrogen sulfide and calcium 

 salts. According to Xadson and Wis- 

 louch (Bull, princip. Jard. bot., R^publ. 

 Russe, 22, 1923, Suppl. 1, 33) also in ma- 

 rine mud. 



2. Achromatium volutans (Hinze) comb. 

 710V. {Thiophysa volutans Hinze, Ber. d. 

 deut. bot. Ges., 21, 1903, 309; Thiophysa 

 macrophysa Xadson, Bull. Jard. Imp. 

 Bot., St. Petersb., 13, 1913, 106 and Jour. 

 :\Iicrob., St. Petersb., 1, 1914, 54; Thio- 

 sphaerella amylifera Nadson, Bull. Jard. 

 Imp. Bot., St. Petersb., 13, 1913, 106 and 

 Jour. INIicrob., St. Petersb., ;, 1914, 54.) 

 From Latin volutans, rolling. 



LTnicellular organisms, spherical to 

 ovoid in shape, dividing by constriction 

 in the middle. Size variable, ranging 

 from spheres about 5 microns in diameter 

 to ovoids up to 40 microns in length. 



Cells may show motility of a jerky and 

 rotating kind, always very slow, and 

 dependent upon a substrate. Typical 

 organs of locomotion absent. 



Normally contain sulfur globules, but 

 lack large internal calcium carbonate 

 deposits. 



Microaerophilic, apparently requiring 

 hydrogen sulfide. 



Habitat: Marine mud containing hy- 

 drogen sulfide; decaying seaweeds. 



Genus II. Thiovulum Hinze. 



(Ber. d. deut. bot. Ges., 31, 1913, 195.) From Greek Ihcion, sulfur and Latin 

 ovum, egg. 



Unicellular organisms, round to ovoid. Cytoplasm often concentrated at one end 

 of the cell, the remaining space being occupied by a large vacuole. Multiplication 

 by constriction which, in late stages, merges into fission. Actively motile; move- 

 ments accompanied by rapid rotation. Flagellation not definitely demonstrated, 

 but type of locomotion suggests polar flagellation. Normally contain sulfur globules 

 in the cytoplasm, hence, these are frequently concentrated at one end of the cell. 



The type species is Thiovulum ma jus Hinze. 



