Motile. Gram-positive, quickly becoming Gram-negative. Gelatin: No liquefaction. Plain agar surface colonies (anaerobic) : Small, circular, entire, whitish translucent, becoming yellowish opaque with age. Glucose agar surface colonies (anaerobic) : Two forms are produced: a) circular, entire, opaque; b) diffuse, spreading, irregular and translucent. Plain broth: Moderately turbid; clears by sedimentation in 3 to 4 days. Glucose broth: Abundantly turbid; slight gas production. Milk: Slowly acidified but not clotted. No further change. Acid and gas from glucose, maltose, lac- tose and mannitol. Sucrose not fermented. Coagulated albumin: No digestion or blackening. Blood serum: No digestion or blackening. Meat medium: No digestion or blacken- ing. Brain medium: No digestion or blacken- ing. Anaerobic. Grows well at 37° C. Not pathogenic (Prevot, loc. cit.). Source: Isolated from septic and gan- grenous war wounds. Habitat: Not determined. 45. Clostridium inicrosporum Spray, 1947. (Jour. Bact., 5^, 1947, 15; also see ihid., 55, 1948, 840.) mic.ro'spo.rum. Gr. adj. micrus small; Gr. noun sporus seed; M.L. noun spora a spore; M.L. adj. microsporus small-spored. Rods, 0.8 by 2.0 to 4.0 microns, occurring singly and in pairs but not in long chains, occasionally long, pleomorphic filaments, distinctly vacuolate, especially in old cul- tures. Organisms navicular and sharply pointed at both ends. Spores tiny, spherical, central to slightly eccentric, slightly swell- ing the cells. Actively motile, particularly by means of a spinning movement with little progressive motion. Presence, number and position of flagella not detected. Gelatin (or iron-gelatin) : No liquefaction or blackening. Agar surface colonies (anaerobic) : Tiny, almost imperceptible, transparent dew-drop colonies, very slightly raised, with entire edges; visible only after some 48 hours' incu- bation. Agar deep colonies: Tiny, 0.5 to 1.0 mm; lenticular with smooth, entire edges; whit- ish translucent (smaller and less opaque than those of Clostridium tertium Bergey et al.). Growth perceptible only after some 72 hours' incubation. Milk (with iron strip) : Fine and constant evolution of gas bubbles for many days, but no coagulation after 22 days' incubation. Medium slowly graj^ed but not blackened. Indole not produced. Lead acetate agar or peptone iron agar: No blackening. Acid and gas from glucose, maltose and galactose. Lactose, trehalose, rhamnose, raffinose, dulcitol and inositol are not at- tacked. Nitrites not produced from nitrates. Coagulated albumin: No liquefaction. Blood agar: No hemolysis. Blood serum: No liquefaction. Brain medium (Hibler) : No blackening or digestion, even in the presence of an iron strip. Anaerobic. Optimum temperature not determined. Growth better at 37° C. than at room tem- perature. Not pathogenic for white mice, guinea pigs or rabbits. Distinctive characters: Minute size and navicular pointed form of the cells, and the tiny, spherical, central to eccentric spores. Source: Isolated only once from the ab- dominal contents of a fatal case of peritoni- tis. Habitat: From human sources, so far as known. 46. Clostridium filiforme Bergey et al., 1923. {Bacillus regularis filiformis Debono, Cent. f. Bakt., I Abt., Orig., 62, 1912, 234; Bergey et al.. Manual, 1st ed., 1923, 331.) fi.li.for'me. L. adj. filiformis thread-like. Slender rods, 0.5 to 0.8 by 3.0 to 5.0 mi- crons, occurring singly, in pairs, in chains and in filaments. Spores very small, spher- ical, subterminal or occasionally terminal, not swelling the cells. Non-motile. Gram- positive.
