Page:Bergey's manual of determinative bacteriology.djvu/291

 Trichomes, 85 to 250 microns in length, Cells rounded at the ends, thin-walled, unbranched, spirally wound, occasionally granular, 1.7 to 2.8 by 3.5 to 30 microns, straight. Strongly encrusted with ferric Apparently heterotrophic, hydroxide. Spirals 20 to 24 microns from Habitat: Found in bottom muds of deep crest to crest. lakes with very low oxygen content.

(Molisch, Sci. Rept. Tahoku Imp. Univ., 4 Ser., Biol., 1925, 144; Cryptothrix Perfiliev, Zur Mikroflora des Sapropels, Nachrichten des Sapropelkomitees Leningrad, 1, 1922.)

Tox'o.thrix. Gr. noun toxum a bow; Gr. noun thrix, trichis a thread; M.L. fem.n. Toxothrix bent thread.

Trichomes composed of cylindrical, colorless cells with a thin primary sheath; the latter soon becomes impregnated with iron oxide. The trichomes lie loosely, longitudinally together, in slightly spirally twisted rolls. The continued repetition of this process leads to the development of a thick, secondary sheath from which parallel bundles may separate. False branching may occur. The sheaths do not completely dissolve in weak acids. Cells may slip out of the sheath and may become motile swarm spores.

The type species is Toxothrix trichogenes (Molisch) Beger.

I. Long, unattached trichomes not in a gelatinous layer.

II. Short trichomes lying in a gelatinous layer.

1. Toxothrix trichogenes (Cholodny, 1924) Beger, 1953. (Leptothrix trichogenes Cholodny, Cent. f. Bakt., II Abt., 61, 1924, 296; T'oxo^Arz.T/e/TMgrmea Molisch, Sci. Rept. Tahoku Imp. Univ., 4 Ser., Biol., 1925, 13; Chlamydothrix trichogenes Naumann, Zent. f. Bakt., II Abt., 78, 1929, 513; Sphaerotilus trichogenes Pringsheim, Biol. Reviews, Cambridge, 24, 1949, 234; Beger, in Beger and Bringmann, Zent. f. Bakt., II Abt., 107, 1953, 332.)

tri.cho'ge.nes. Gr. noun thrix, trichis hair; Gr. v. gennao to bear; M.L. adj. trichogenes hair-producing.

Found in trichomes up to 400 microns in length; composed of rod-shaped cells which are 0.5 by 1.0 to 2.0 microns. Surrounded by a tubular sheath which splits later so that arched, fan-shaped groups of threads or irregular groups are formed as the trichomes grow in length. Do not lie in a gelatinous layer. The tubular sheath is longitudinally and somewhat spirally striated with lines about 0.2 micron apart. No false branching. Iron oxide is deposited in the sheaths. The number and diameters of the longitudinally placed trichomes are variable. Giant cells are frequently present. The sheaths, when empty, decay rapidly. The trichomes may slip out of their sheaths.

This species has been cultivated by Teichmann (Vergleichende Untersuchungen iiber die Kultur und Morphologie einiger Eisenorganismen, Inaug. Diss., Prague, 1935).

Beger and Bringmann (op. cit., 1953, 332) report a form of this species in which the sheaths do not split; the cells are 0.5 by 2.0 to 4.0 microns.

Source: This species has been described from springs, wells, small rivers, water works and rice fields.

Habitat: Found in cool, fresh, iron-bearing waters.

2. Toxothrix gelatinosa Beger, 1953. (Beger, in Beger and Bringmann, Zent. f. Bakt., II Abt., 107, 1953, 333.)

ge.la.ti.no'sa. L. part. adj. gelatus con gealed; M.L. adj. gelatinosus gelatinous. The trichomes are up to 22 microns in