80 



ORDER I. PSEUDOMONADALES 



containing potassium sulfide (K2S) which 

 was inoculated with a handful of garden soil 

 from Graz, Austria. At the end of three 

 weeks, numerous, snow-white colonies de- 

 veloped on the surface of the water. 



Colonies which at first are of microscopic 

 size maj^ become 0.8 to 1.5 mm in diameter. 

 Sulfur crystals appear by transmitted light 

 as a black mass in the center of the smaller 

 colonies, but these crystals extend to the 

 margin in older colonies. 



Habitat: Garden soil. 



3. Thiobacteriuni retifornians (Gickl- 

 horn, 1920) Janke, 1924. (Bacterium retifor- 

 nians Gicklhorn, Cent. f. Bakt., II Abt., 50, 

 1920, 421; Janke, Allgem. Tech. Mikrobiol., 

 I Teil., 1924, 68.) 



re. ti. for 'mans. L. noun rete a net; L. v 

 formo to form; M.L. part. adj. retifonnans 

 net-forming. 



Rod-shaped bacteria, 0.5 to 1.0 by 2.0 to 

 4.5 microns. Globular sulfur granules found 

 among the cells. Non-motile. Forms pelli- 

 cles and zoogloeal masses. 



Developed in water containing potassium 

 sulfide (K2S) which was inoculated with the 

 decaying roots of nettle plants. This species 

 developed a delicate pellicle in the form of a 

 network on the surface of the water. It 

 also formed zoogloeal masses attached to 

 the wall of the culture flask. 



Source: Soil containing decaying roots, 

 Graz, Austria. 



Habitat: Presumably widely distributed. 



Gemis II. Macromonas Utermohl and Koppe, 1923.* 



(Utermohl and Koppe, Verhandl. Intern. Ver. f. Theoret. u. angew. Limnologie, 1923, 86; 

 Thiovibrio Janke, Allgem. Tech. Mikrobiol., I Teil, 1924, 68.) 



Mac.ro.mo'nas. Gr. adj. macrus large; Gr. noun monas a unit, monad; M.L. fem.n. Macro- 

 monas a large monad. 



Colorless, cylindrical to bean -shaped bacteria, actively motile by means of a single polar 

 flagellum. Cells large, 3.0 to 14.0 microns in diameter. Multiplication by constriction (fis- 

 sion). Chiefly characterized by the occurrence of calcium carbonate inclusions in the form 

 of large spherules. In their natural habitat they may also contain small sulfur globules. 



Two species have been distinguished, primarily on the basis of cell size. Whether this is 

 sufficiently constant to serve as a specific character has not been definitely established. 

 From studies on the organisms in their natural habitat, which are still limited in scope and 

 extent, it appears at present that the two species should be maintained, at least provi- 

 sionally. It is possible, however, that further observations, especially with cultures under 

 different environmental conditions, will show the occurrence of intermediate types and of a 

 greater range of variation in size of pure cultures than has previously been reported. 



The type species is Macromonas mobilis (Lauterborn) Utermohl and Koppe. 



Key to the species of genus Macromonas. 



I. Cells measure 12 microns or more in length and 8 microns or more in width. 



1. Macromonas mobilis. 



II. Cells measure less than 12 microns in length and 5 microns or less in width. 



2. Macromonas bipunctata. 



1. Macromonas mobilis (Lauterborn, 

 1915) Utermohl and Koppe, 1923. {Achro- 

 matiitm mobile Lauterborn, Verhandl. 

 Naturhist.-medizin. Vereins, Heidelberg, 

 N. F., IS, 1915, 413; Utermohl and Koppe, 



Verhandl. Intern. Ver. f. theoret. u. angew. 

 Limnologie, 1923, 86 and Utermohl and 

 Koppe, Arch. f. Hydrobiol., Suppl. Bd. 5, 

 1925, 234.) 

 mo'bi.lis. L. adj. mobilis movable, motile. 



* Prepared by Prof. Dr. Alexander Janke, Technische Hochschule, Vienna, Austi 

 December, 1954. 



