FAMILY I. CHLAMYDOBACTERIACEAE 269 



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 verj' low oxygen content. 



Genus III. Toxothrix MoUsch, 1925. 



(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. Toxo- 

 thrix 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 to- 

 gether, 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 maj^ 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 irichogenes (Molisch) Beger. 



Key to the species of genus Toxothrix. 



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



1. Toxothrix trichogenes. 

 II. Short trichomes lying in a gelatinous layer. 



2. Toxothrix gelatinosa. 



1. Toxothrix trichogenes (Cholodny, the sheaths. The number and diameters of 



1924) Beger, 1953. (Leptothrix trichogenes the longitudinally placed trichomes are 



Cholodny, Cent. f. Bakt., II Abt., 61, 1924, variable. Giant cells are frequently present. 



296; T'oxo^Arz.T/e/TMgrmea Molisch, Sci. Rept. The sheaths, when empty, decay rapidly. 



Tahoku Imp. Univ., 4 Ser., Biol., 1925, 13; The trichomes may slip out of their sheaths. 



Chlamydothrix trichogenes Naumann, Zent. This species has been cultivated by Teich- 



f. Bakt., II Abt., 78, 1929, 513; Sphaerotilus mann (Vergleichende Untersuchungen iiber 



trichogenes Pringsheim, Biol. Reviews, die Kultur und Morphologie einiger Eisen- 



Cambridge, 24, 1949, 234; Beger, in Beger organismen, Inaug. Diss., Prague, 1935). 



and Bringmann, Zent. f. Bakt., II Abt., Beger and Bringmann (op. cit., 1953, 332) 



107, 1953, 332.) report a form of this species in which the 



tri.cho'ge.nes. Gr. noun thrix, trichis sheaths do not split; the cells are 0.5 by 2.0 



hair; Gr. v. gennao to bear; M.L. adj. tri- to 4.0 microns. 



chogenes hair-producing. Source: This species has been described 



Found in trichomes up to 400 microns in from springs, wells, small rivers, water 



length; composed of rod-shaped cells works and rice fields. 



which are 0.5 by 1.0 to 2.0 microns. Sur- Habitat: Found in cool, fresh, iron-bear- 

 rounded by a tubular sheath which splits ing waters, 

 later so that arched, fan-shaped groups of 



threads or irregular groups are formed as 2. Toxothrix gelatinosa Beger, 1953. 



the trichomes grow in length. Do not lie in (Beger, in Beger and Bringmann, Zent. f. 



a gelatinous layer. The tubular sheath is Bakt., II Abt., 107, 1953, 333.) 



longitudinally and somewhat spirally stri- ge.la.ti.no'sa. L. part. adj. gelatus con- 



ated with lines about 0.2 micron apart. No gealed; M.L. adj. gelatinosus gelatinous, 



false branching. Iron oxide is deposited in The trichomes are up to 22 microns in 



