Page:Bergey's manual of determinative bacteriology.djvu/102

 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 developed on the surface of the water.

Colonies which at first are of microscopic size may 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 (Gicklhorn, 1920) Janke, 1924. (Bacterium retiformans 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. retifornans 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 pellicles 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.

Mac.ro.mo′nas. Gr. adj. macrus large; Gr. noun monas a unit, monad; M.L. fem. n. Macromonas 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 (fission). 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 provisionally. 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) Utermöhl and Koppe.

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

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

1. Macromonas mobilis (Lauterborn, 1915) Utermöhl and Koppe, 1923. (Achromatium mobile Lauterborn, Verhandl. Naturhist.-medizin. Vereins, Heidelberg, N. F., 13, 1915, 413; Utermöhl and Koppe, Verhandl. Intern. Ver. f. theoret. u. angew. Limnologie, 1923, 86 and Utermöhl and Koppe, Arch. f. Hydrobiol., Suppl. Bd. 5, 1925, 234.)

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