on rich media, drop-like colonies, resembling those of many bacteria, are formed. Do not possess chlorophyll or phycocyanin. Closely resemble some of the Beggiaioaceae, differing primarily in that they never contain sulfur granules even when growing in an environment conducive to the development of such granules in Beggiatoa. The trichomes resemble those of Oscillatoria but do not possess the pigments characteristic of members of that genus. Do not hydrolyze genuine proteins. Found on dung, in soil, in water with decaying plant mate- rial and almost regularly in myxophycean scum on the surfaces of quiet waters. A number of the organisms in this family have been described from microscopic studies only, cultural investigations not having been made at the time. The true relationships of these organisms can be clarified only by further study. Key to the genera of family Vitreoscillaceae. I. Trichomes perceptibly septate. A. Trichomes divided into cells which are not separated by empty interspaces; the trichomes may bend anywhere along their length. Genus I. Vitreoscilla, p. 845. B. Trichomes divided into cells separated by empty interspaces; the trichomes bend only at these pliable joints. Genus II. Bactoscilla, p. 848. II. Trichomes not perceptibly septate. Genus III. Microscilla, p. 849. Genus I. Vitreoscilla Pringsheim, 1949. (Bad. Rev., 13, 1949, 70; also see Jour. Gen. Microbiol., 5, 1951, 127 and 147.) Vit.re.os.cil'la. L. adj. vitreus glassy, clear; L. noun oscillum a swing; M.L. fem.n. Vitre- oscilla transparent oscillator. Trichomes clearly divided into cells. Usually motile by means of gliding movements; one species is non-motile. Gram-negative. Reproduction is by hormogonium-like fragmentation of the trichomes. True proteins are not hydrolyzed. Found in fresh water, in soil and in de- composing organic materials. The type species is Vitreoscilla beggiatoides Pringsheim. Key to the species of genus Vitreoscilla. I. Trichomes relatively slender, measuring 2.5 microns or less in diameter. A. Trichomes 2.0 microns or less in diameter. 1. Trichomes motile. Cultivable on artificial media. a. Trichomes sluggishly motile. b. Trichomes about 2.0 microns in diameter. 1. Vitreoscilla beggiatoides. bb. Trichomes less than 1.6 microns in diameter. 2. Vitreoscilla stercoraria. aa. Trichomes actively motile. b. Trichomes 1.2 microns in diameter. 3. Vitreoscilla filif or mis. bb. Trichomes more than 1.2 microns in diameter. c. Cells of trichomes relatively short (3.0 to 4.0, sometimes 6.0, microns in length). 4. Vitreoscilla catenula. cc. Cells of trichomes relatively long (30 to 70 microns). 5. Vitreoscilla paludosa. 2. Trichomes non-motile. Not cultivated in pure culture. 6. Vitreoscilla stricta.
