Nitrites not produced from nitrates. Anaerobic. Temperature relations: Optimum, 37° C; growth range, 31° to 43° C. (Hoffman, Oral Surg., 5, 1952, 1088). Survives 50° C. for 15 minutes, 52° C. for 10 minutes and 56° C. for 5 minutes (Hine and Berry) . Optimum pH, between 7.0 and 8.2 (Hau- duroy et al., Diet. d. Bact. Path., 1953, 259); between 6.9 and 7.7 (Hoffman, op. cit., 1952, 1088). Non-pathogenic for guinea pigs and mice. Source : One strain was isolated from a de- posit on teeth in a case of gingivitis (Knorr) ; also isolated from gingival crevices in nor- mal mouths, from cases with deep caries, inflamed areas around crowns and fillings, pyorrhetic pockets, Vincent's infection and from the mouths of three monkeys and two rabbits (Hine and Berry) ; also found in a case of acute appendicitis (Prevot and Peyre). Habitat: Presumably the buccal cavity. 3. Fusobacteriuin praeacutum (Tis- sier, 1908) Hoffman, comh. nov. {Coccobacil- lus praeacutus Tissier, Ann. Inst. Past., 22, 1908, 189; Zuberella praeacuta Prevot, Ann. Inst. Past., 60, 1938, 293.) prae.a.cu'tum. L. pref. prae very, quite; L. adj. acuiiis sharp; ]M.L. adj. praeacutus quite sharp. Short rods, with pointed ends, occurring singly and in chains. Sw^ollen forms present in old cultures. Motile by means of peri- trichous flagella. Gram-negative. Gelatin: No liquefaction. Agar: Deep colonies lenticular. Abun- dant gas production. Broth: Turbid with powdery precipitate. Milk: Unchanged. Coagulated egg white: Not digested. Milk fats are saponified. Indole not produced. Acid from glucose. No acid or gas from lactose or sucrose. Anaerobic. Optimum temperature, between 22° and 37° C. Not pathogenic. Source: Isolated from the intestines of infants. Habitat: Found in the intestinal tract of man. 4. Fusobacteriuni nucleatum Knorr, 1923. (Cent. f. Bakt., I Abt., Orig., 89, 1923, 17.) nu.cle.a'tum. L. adj. nucleatus having a kernel, nucleated. Original description supplemented by material taken from Hine and Berry (Jour. Bact., 34, 1937, 520) and from Robin (Ann. Inst. Past., 74, 1948, 259). Spindle-shaped rods, 1 by 4 microns, occurring singly and often in pairs. One or two granules are present. Non-motile. Gram-negative. Disagreeable odor produced on cultiva- tion; no gas is produced. Gelatin: No liquefaction. Plain agar: Scant growth. Meat infusion agar: Good growth. Serum agar plate: Deep colonies lens- shaped with offshoots. Rabbit blood (5 per cent) agar colonies: Round, 0.5 to 1.0 mm in diameter, convex, grayish white, smooth, glistening, entire. Ascitic fluid agar: No growth by most strains. Peptone broth: No growth. Plain liver broth: No growth. Liver broth with serum: After 1 to 3 days, flocculent deposit on the pieces of liver. Douglas' broth: Good growth at bottom of tube under anaerobic conditions ; uniform turbidity on shaking. Milk: No coagulation. Indole not produced (Knorr) ; indole produced (Hine and Berry, and Robin). Hydrogen sulfide not produced (Knorr); hydrogen sulfide is produced (Robin). Acid from glucose, usually from fructose and sometimes from sucrose and lactose. No acid from maltose, inulin or mannitol (Hine and Berry). Glucose, fructose, galac- tose and sucrose are fermented, lactose only feebly (Robin) . Neutral red reduced. Nitrites produced from nitrates. Proteins not digested. Pathogenic for mice. Anaerobic. Temperature relations: Optimum, be- tween 35° and 37° C. (Hauduroy et al.,
