AUTOTROPHIC BACTERIA 83 



curative muds. 55 According to Nadson, some of these organisms, like 

 Achromatium and Thiophysa, can accumulate in their cells sulfur as 

 well as oxalate crystals. Jegunow described two sulfur bacteria: 

 Thiobacterium a, a motile, colorless, slightly curved organism, 4.5 to 9ju 

 long and 1.4 to 2.3ju wide, containing a finely granulated plasma and 

 large sulfur granules, and Thiobacterium /3, motile, colorless, curved, 

 2.5 to 5 by 0.6 to 0.8/x, and containing a row of shining sulfur granules. 

 Various bacteria belonging to this group have been reported 56 to occur 

 in the soil, namely: Spirillum agilissimum filled with black sulfur granules, 

 measuring about 6 to 10 by 1.8 to 2.0^, having rapid motility, and 

 isolated from river mud in Gratz; Chromatium cuculliferum which is 

 round to slightly elliptical, 6 by 4/j, of a slow motility, with black, 

 shining, sulfur drops always found in one pole, with one flagellum on the 

 granule-free pole. This latter form was found in rotting mass of algae 

 in the garden basin at Gratz. However, since none of the forms has 

 been considered from the point of view of its role in soil transformations, 

 their importance in the soil is doubtful. A detailed study of the 

 morphology and biology of Achromatium oxalifcrum Schew., containing 

 granules of a calcium salt (oxalate, carbonate or thiosulfate) and sulfur 

 has been made by Nadson and Wislouch. 57 



Group III. This group consists of the sulfur oxidizing organisms 

 found among the purple bacteria. They are distinguished from the 

 sulfur bacteria described above by the production of a red, red violet 

 or red brown pigment which is unevenly distributed throughout the 

 cell; in addition to the red pigment (bacterio-purpurin), there is also 

 present in all these bacteria a green pigment (bacterio-chlorin). These 

 bacteria are found abundantly in sulfur springs and in mud waters. 

 Not all the purple bacteria are able to utilize hydrogen sulfide and not 

 all of them accumulate sulfur within their cells. Molisch 58 succeeded 

 in cultivating some of them in pure culture, but not the sulfur forms. 

 The role of sulfur in the metabolism of the purple bacteria is still an 

 open question, since, according to Molisch, the hydrogen sulfide is not 



66 Jegunow, M. Bakterien Gesellschaften. Centrbl. Bakt. II, 2: 11-21, 441- 

 449; 478^82; 739-752. 1896. 



56 Gicklehorn, J. Uber neue farblose Schwefelbakterien. Centrbl. Bakt. II, 

 50: 415-427. 1920. 



87 Nadson, G. A., and Wislouch, C. M. La structure et la vie de la bacterie 

 geante Achromatium oxalijerum Schew. Bull. Jard. Bot. Rep. Russe. 22: 1-24. 

 1923. 



68 Molisch, H. The Purpurbakterien nach neuen Untersuchungen. Jena. 

 G. Fischer. 1907. 



