2. Microscilla flagellutn (Pringsheim, 1949) Pringsheim, 1951. (Vitreoscilla flagel- lum Pringsheim, Bact. Rev., 13, 1949, 72; Pringsheim, Jour. Gen. Microbiol., 5, 1951, 143.) fla.gel'lum. L. neut.dim.n. flagellum a whip, flagellum. Slender trichomes, about 0.3 to 0.4 mi- cron in diameter, varying greatly in length: the shortest do not exceed 10 microns, and the longest, so much curved and entangled so as not to be measurable, are at least 100 microns in length. The trichomes are at- tached at one end, the lively movements of the free ends giving the impression of a flagellum of Euglena. Gram-negative. Source: Found in fresh water containing filamentous Mijxophyceae such as Oscilla- tor ia amphibia. Habitat: Found in fresh water containing algae. 3. Microscilla agilis Pringsheim, 1949. (Jour. Gen. Microbiol., 5, 1951, 142.) a'gi.lis. L. adj. agilis agile. Slender trichomes, 0.6 to 0.8 by 12.0 to 70.0 microns, with no apparent septation. Motile by means of gliding movements. Motility and flexibility are extraordinary, reminiscent of that of Spirochaeta plicatilis Ehrenberg. The trichomes always seem at- tached to the substrate along their entire length, no free-swinging ends being evi- dent. Rotation is apparently lacking. Gram- negative. Source: Found in a ditch in Coldham Common near Cambridge, England, con- taining decaying plant residue, a great variety of flagellates, Cladophora and Chloro- hydra . Habitat : Found in fresh water containing decaying plant material and protozoa. FAMILY III. LEUCOTRICHACEAE BUCHANAN, Fam. Nov.* Leu.co.tri.cha'ce.ae. M.L. fem.n. Leucothrix type genus of the family; -aceae ending to denote a family; M.L. fern. pi. n. Leucotrichaceae the Leucothrix family. Short, cylindrical cells arranged in long, colorless, unbranched, non-motile trichomes tapering from the base to the apex. Sulfur granules may be found on the exterior of the cells under certain conditions. Trichomes commonly attached basally to solid substrates by an inconspicuous holdfast. Multiplication by means of gonidia (single, gliding cells which arise apically from the trichomes). The gonidia may aggregate to form rosettes containing up to 50 cells. The cells in the rosettes become non-motile, develop holdfasts and elongate to form trichomes; therefore mature trichomes are characteristically arranged in the form of radial colonies, although occasionally gonidia develop singly, forming isolated trichomes. Strictly aerobic. Resemble blue-green algae in many respects but differ from them in that they do not produce photosynthetic pigments. Found in fresh- and salt-water containing decomposing algal material. There is a single genus, Leucothrix Oersted. Germs I. Leucothrix Oersted, 1844, emend. Harold and Stanier, 1955. (Oersted, De regionibus marinis, elementa topographiae historiconaturalis freti Oeresund. J. C. Scharling, Copenhagen, 1844, 44; Pontothrix Nadson and Krassilnikov, Compt. rend. Acad. Sci. de U.R.S.S., A. No. 1, 1932, 243; Harold and Stanier, Bact. Rev., 19, 1955, 54.) Leu'co.thrix. Gr. adj. leucus clear, light; Gr. noun thrix, trichis hair; M.L. fem.n. Leuco- thrix colorless hair. Description as for the family. The type species is Leucothrix mucor Oersted. Prepared by Prof. R. E. Buchanan, Iowa State College, Ames, Iowa, October, 1955.
