Anaerobic. Non-pathogenic for white mice or rabbits. Source : Two strains were isolated from human feces. Habitat: Probably the intestinal canals of mammals. 5. Bacteroides insolitvis Eggerth and Gagnon, 1933. (Eggerth and Gagnon, Jour. Bact., 25, 1933, 408; Ristella insolita Prevot, Ann. Inst. Past., 60, 1938, 291.) in.so.li'ta. L. adj. insolitus unusual. Short, thick rods, 1 to 2 microns long, often occurring as slender, curved cells, 2 to 3 microns long. Non-motile. Gram- negative. Gelatin: No liquefaction in 45 days. Blood agar colonies: Minute, transparent. Broth: Heavy, diffuse growth. Milk: Acidified and coagulated in 30 to 35 days. Indole is produced. Hydrogen sulfide is produced. Acid but no gas from fructose, galactose, glucose, glycerol, lactose, maltose and niannose. No acid or gas from esculin, amygdalin, arabinose, cellobiose, dextrin, glycogen, inulin, mannitol, melezitose, raffinose, rhamnose, salicin, sorbitol, starch, sucrose, trehalose or xylose. Nitrites not produced from nitrates. Anaerobic. Non-pathogenic for white mice or rabbits. Distinctive characters: Brom cresol purple and phenol red are rapidly decolor- ized in a meat infusion broth. A small amount of gas is produced from peptone. Source: One strain was isolated from hu- man feces. Habitat: Probably the intestinal canals of mammals. 6. Bacteroides thetaiotaomicron (Dis- taso, 1912) Kelly, comb. nov. {Bacillus thetaiotaomicron Distaso, Cent. f. Bakt., I Abt., Orig., 62, 1912, 444; Bacteroides tethai- otaomicron (sic) Castellani and Chalmers, Man. Trop. Med., 3rd ed., 1919, 960;/SpAae/'o- cillus thetaiotaomicron Prevot, Ann. Inst. Past., 60, 1938, 300.) the.ta.i.o.ta.o'mi.cron. M.L. noun the- taiotaomicron a combination of the Greek letters theta, iota and omicron, so used because the pleomorphic rods of this species have the shapes of these letters. Description taken from Distaso (op. cit., 1912, 444) ; a more complete description will be found in Eggerth and Gagnon (Jour. Bact., 25, 1933, 399). Short, plump to elliptical rods which sometimes have a bar across them, thus causing the organism to resemble the Greek letter theta. Motile (Distaso). Non-motile (Eggerth and Gagnon). Stain solidly or only at the poles. Gram-negative. Gelatin: No liquefaction. Glucose agar colonies : Large, transparent, entire; sometimes gas bubbles are produced. Broth: Turbid. Egg albumen broth: Albumen not at- tacked. Litmus milk: Acid, coagulated. Curd shrinks with expulsion of turbid whey. Indole is produced. Hydrogen sulfide produced (Eggerth and Gagnon) . Acid and gas from esculin, amygdalin, arabinose, fructose, inulin, lactose, cello- biose, dextrin, galactose, glucose, glycogen, maltose, mannose, melezitose, raffinose, rhamnose, salicin, starch, sucrose, trehalose and xylose. Four strains fail to produce gas from any sugar. No acid or gas from glyc- erol, mannitol or sorbitol (Eggerth and Gagnon) . Nitrate reduction not recorded (Distaso). Nitrites not produced from nitrates (Eg- gerth and Gagnon). Peptone: No gas (Eggerth and Gagnon). Anaerobic. Distinctive characters: Resembles Bac- teroides variabilis but is not encapsulated, does not liquefy gelatin, usually produces gas from sugars and ferments melezitose and trehalose. Differs from Bacteroides uniformis in morphology, in producing gas from sugars and in fermenting rhamnose (Eggerth and Gagnon) . Source: Isolated frequently from human feces. Habitat: Intestinal canals of mammals (common). 7. Bacteroides trichoides (Potez and Compagnon, 1922) Hauduroy et al., 1937. {Bacillus trichoides Potez and Compagnon,
