and heavily impregnated with iron oxide, surrounds the trichomes. Reproduction by motile swarm cells liberated from the tip and also by the emergence of the trichome from the sheath, with subsequent breaking up into individual, non-motile cells. Not acid-fast. Gram-negative. Gelatin not liquefied. Iron citrate and ammonium agar colonies: More or less rounded, with oily inclusions, filamentous border. Manganese acetate agar colonies: Fila- mentous growth, the filaments being rather large and showing false branching. Iron citrate and ammonium agar slant: Growth only in the water of condensation, rarely on the slant. Peptone and manganese acetate broth: Abundant growth in the form of loose flakes. Indole not produced. Hydrogen sulfide not produced. Acetylmethylcarbinol not produced. Nitrites produced from nitrates. Optimum temperature, between 25° and 28° C. Optimum pH, 8.5. Aerobic; growth not favored by the pres- ence of CO2 . Habitat : Found in fresh water; widely dis- tributed.
5. Leptothrix major Dorff, 1934. (Dorff Die Eisenorganismen, Pflanzenforschung, Heft 16, 1934, 35; also see Beger and Bring- mann,Zent. f.Bakt., IIAbt., 107, 1953,323.) ma'jor. L. comp.adj. major larger. Trichomes, up to 1 and more cm in length, attached by a holdfast, richly branched, forming tufts. Trichomes composed of rod- like cells, 1.4 by 5 to 10 microns, which con- tain small false vacuoles. Giant cells up to 75 microns in length. Two trichomes may be found in the same sheath. The sheath may be as much as 12 microns in thickness, taper- ing to the tip, storing manganese and iron. Resembles the sheath of Leptothrix disco- phora but is firmer in texture. Light to dark l)rown in color. Source: From the Spree River near Berlin. Habitat: Found in fresh- water streams.
6. Leptothrix lopholea Dorff, 1934. (Die Eisenorganismen, Pflanzenforschung, Heft 16, 1934, 33.) lo.pho'le.a. Gr. noun lophus a crest; M.L. dim. adj. lopholeus somewhat crested or tufted. Short, slender unbranched trichomes, uniform in diameter, attached to a sub- strate, 5 to 13 trichomes arising from a common holdfast. Trichomes 20 to 33 mi- crons long, cells 0.5 by 1.0 to 1.3 microns. Sheaths composed of iron oxide; dissolve completely in dilute hydrochloric acid. Trichomes slip out of the sheath as in Leptothrix: ochracea. Habitat: Water.
7. Leptothrix echinata Beger, 1935. (Zent. f. Bakt., II Abt., 92, 1935, 401.) e.chi.na'ta. Gr. noun echinus the hedge- hog; M.L. adj. echinatus like the hedgehog, bristly. Similar to the preceding species but oc- curring in larger colonies, 20 to 50 trichomes arising from a common holdfast. Trichomes are shorter (9 to 10 microns). Sheath is thicker at the base and tapers toward the free tip of the trichome, which is slightly spiral. The sheath contains an or- ganic matrix visible after treatment in di- lute hydrochloric acid. Habitat: Found in water, especially in manganese-bearing waters.
8. Leptothrix epiphytica (Migula, 1895) Schoenichen and Kalberlah, 1900. (Strepto- thrix epiphytica Migula, in Engler and Prantl, Die natiirl. Pflanzenfam., /, la, 1895, 36 and 38; Chlamydothrix epiphytica Migula, Syst. d. Bakt., 2, 1900, 1033; Schoe- nichen and Kalberlah, Eyferth's Einfachste Lebensformen, 3rd ed., 1900, 46.) e.pi.phy'ti.ca. Gr. prep, epi' upon; Gr. noun phytum plant; M.L. adj. epiphyticns epiphytic, growing on plants. Chains of cells enclosed in short, colorless trichomes which are surrounded by thick, gelatinous masses; the gelatinous masses are attached to algae, but never in groups or clusters. Habitat: Widely distributed in fresh water containing algae.
