curved chains; in gelatin media filaments form which may subdivide into coccoid elements. Not encapsulated. Motile with peritrichous flagella. Gram-positive. Carbohydrates not attacked. Facultatively anaerobic. Found in decomposing materials. The type species is Kurthia zopfii (Kurth) Trevisan. Key to the species of genus Kurthia. I. Gelatin not liquefied. A. Hydrogen sulfide not produced; putrid odor produced in cultures. 1. Kurthia zopfii. B. Hydrogen sulfide produced; no putrid odor produced in cultures. 2. Kurthia variabilis. II. Gelatin rapidly liquefied. 3. Kurthia bessonii. 1. Kurthia zopfii (Kurth, 1883) Trevi- san, 1885. (Bacterium zopfii Kurth, Bericht. d. deutsch. Bot. Gesellschaft, 1, 1883, 97; Trevisan, Atti della Accad. Fisio-Medico- Statistica in Milano, Ser. 4, 3, 1885, 92.) zop'fi.i. M.L. gen. noun zopfii of Zopf; named for W. Zopf, a German botanist. Description based on original descriptions and that of Wenner and Rettger (Jour. Bact., 4, 1919, 350). Rods, 0.8 by 3.5 microns, with rounded 3nds. In liquid media, long, evenly curved chains are formed; in gelatin media the chains are twisted, braided and clumped into knots. From these knots filaments push out, laterally then anteriorly, which may subdivide into coccoid elements. Not en- capsulated. Motile by means of peritrichous flagella. Gram-positive. Gelatin colonies: Radiate, filamentous, gray. Gelatin stab: Arborescent growth in stab. No liquefaction. Agar colonies: Fimbriate. Agar slant: Spreading, gray, fimbriate growth. Broth: Slow, moderate growth; putrid, ammoniacal odor produced. Litmus milk: No change. Potato: Moderate, gray growth; medium becoming dark. Carbohydrates not attacked. Indole not produced. Hydrogen sulfide not produced. Nitrites not produced from nitrates. Aerobic, facultatively anaerobic. Optimum temperature, between 25° and 30° C. Comments: Some workers make a dis- tinction between Kurthia zopfii Trevisan and Kurthia zenkeri Bergey et al., mainly on their ability or inability to form an arbores- cent growth in a gelatin stab. However, according to Chester (Man. Determ. Bact., 1901, 249), division of these organisms into two species does not seem advisable: the formation of an arborescent growth is too variable a character on which to base species differentiation. This view is also shared by Wenner and Rettger (op. cit., 1919, 351). Source: Isolated from hen manure. Habitat: Foimd in decomposing mate- rials. 2. Kurthia variabilis Severi, 1946. (Giorn. di Batteriol. e Immunol., 46, 1946, 107.) va.ri.a'bi.lis. L. adj. variabilis variable. Rods, 0.7 by 1.5 to 2.0 microns, frequently curved, growing out into filaments 10 to 30 microns long; these filaments later divide in two or form short chains. Motile by means of peritrichous flagella. Gram-positive. Gelatin stab: No liquefaction. Grayish growth along the stab. Agar colonies: 1 to 2 mm in diameter, grayish white, glossy, smooth; regular mar- gins. Agar slant: Slender, grayish white, trans- lucent, slightly viscid. Broth: Moderate, uniform turbidity; thin membrane. Sediment at first slight, later abundant. Litmus milk unchanged. Methylene blue not reduced. Neutral red reduced.
