82 PRINCIPLES OF SOIL MICROBIOLOGY 



in the work of Omeliansky, 45 Duggeli, 46 Bavendamm, 47 and others. 48 

 The Thioploca has been studied in detail by Wislouch 49 and Kolkwitz. 50 

 Group II. The second group of the sulfur oxidizing bacteria is 

 heterogeneous in nature and consists of all colorless organisms, ivhich 

 form no threads and which contain sulfur within their cells. These also 

 act only on H 2 S (Nos. 17-20, PI. IV). This group includes organisms 

 of various forms. They may be obtained by placing the cut rhizomes 

 of water plants, together with the mud, into tall glass cylinders with 

 some river or canal water and a few grams of calcium sulfate. When 

 placed in the dark, H 2 S will be produced in 5 to 10 days, and the color- 

 less non-thread-forming sulfur bacteria are found in 3 to 6 weeks. The 

 nature of the plant or animal material, nature of the mud and quantity 

 of H 2 S produced, determine which species will predominate. Among the 

 organisms described at various times we might mention : Monas mulleri 

 and Monas fallax Hinze, 48 Thiophysa volutans Hinze, 51 Thiospirillum wi~ 

 nogradskii Omeliansky, 52 Thiovulum Hinze, Spirillum Molisch, Bacterium 

 bovista (2 to 4 by 0.6 by l.Oju), Bacillus thiogenes (2 to 6 by 0.9 to 1.34;u), 

 and Achromatium. 53M Most organisms belonging to this group have 

 been found in water and in mud; few of them have been obtained in 

 pure cultures. They play an important part in the formation of the 



46 Omeliansky, W. L. Der Kreislauf des Schwefels. Lafar's Handb. techn. 

 Mykol. 3: 214-244. 1904. 



46 Duggeli, M. Die Schwefelbakterien. Neujahrsbl. Naturf. Gesell. Zurich. 

 1919, No. 121, 43 p. 



47 Bavendamm, W. Die farblosen und roten Schwefelbakterien des Siisz- und 

 Salzwassers. G. Fischer. Jena. 1924. 



4S Hinze, G. Beitrage zur Kenntnis der farblosen Schwefelbakterien. Ber. 

 deut. bot. Gesell. 31: 189-202. 1913. Molisch, H. Neue farblose Schwefel- 

 bakterien. Centrbl. Bakt. II, 33: 55-62. 1912. 



49 Wislouch, S. M. Thioploca ingrica nov. spez. Ber. deut. bot. Gesell. 30: 

 470-473. 1912. 



60 Kolkwitz, R. t)ber die Schwefelbakterie Thioploca ingrica Wislouch. 

 Per. deut. bot. Gesell. 30: 662-666. 1912. 



61 Hinze, G. Thiophysa volutans, ein neues Schwefelbakterium. Ber. deut. 

 bot. Gesell. 21: 309-316. 1903. 



62 Omeliansky, W. L. Tiber eine neue Art farbloser Thiospirillen. Centrbl. 

 Bakt. II, 14: 769-772. 1905. 



63 Nadson, G. A. On the sulfur bacteria of the sea of Hapsala. Bull. Jard. 

 Bot. St. Petersburg, 13: 106-112. 1913; On the sulfur bacteria Thiophysa and 

 Thiosphaerella. Jour. Microb. (Russian) 1: 52-72. 1914. 



64 West, G. S., and Griffith, B. M. The lime-sulfur bacteria of the genus Hil- 

 lowia. Ann. Bot. 27: 83-91. 1913. 



