ing cultures. Glucose and usually various other carbohydrates, but not lactose, are fer- mented with the production of acid and usually visible gas; one species usually produces only acid. Phenylpyruvic acid is produced from phenylalanine bj^ an oxidative deamination, and leucine is rendered alkaline by an oxidative decarboxylation. Urea may or may not be decomposed. Trimethylamine oxide is reduced. Primarily from fecal matter and other putrefj'ing materials. The type species is Proteus vulgaris Hauser. Key to the species of genus Proteus. I. Urea hydrolyzed. A. No acid or gas from mannitol. 1. Acid and gas from maltose. 2. No acid or gas from maltose. a. Indole not produced. 1. Proteus vulgaris. 2. Proteus mirabilis. aa. Indole is produced. 3. Proteus morganii. B. Acid and sometimes gas from mannitol. 4. Proteus rettgeri. II. Urea not hj'drolyzed. 5. Proteus inconstans. 1. Proteus vulgaris Hauser, 1885. (Hau- ser, Sitzungsber. d. phj^s.-mediz. Sozietat zu Erlangen, 1885, 156; Bacterium vulgare Leh- mann and Neumann, Bakt. Diag., 1 Aufl., 2, 1896, 243.) vul.ga'ris. L. adj. vulgaris common. Rods, 0.5 to 1.0 by 1.0 to 3.0 microns, oc- curring singly, in pairs and frequently in long chains. Actively motile by means of peritrichous flagella. Gram-negative. Gelatin colonies: Irregular, swarming; rapid liquefaction. Gelatin stab: Rapid, stratiform liquefac- tion. Agar colonies: Opaque, graj', swarming. Agar slant: Thin, bluish gray growth, spreading over the entire surface. Broth: Markedly turbid, usually with a thin pellicle. Litmus milk: Rlightl}' acid, becoming markedly alkaline; quick peptonization. Potato: Abundant, creamy to yellowish gray growth, becoming brown. Putrefactive odor produced. Indole is produced. Hydrogen sulfide produced from cysteine, cystine or organic sulfur compounds con- taining either of these molecules; also pro- duced from sulfur and thiosulfates (Tarr, Biochem. Jour., 27, 1933, 1869; 28, 1934, 192). Lead acetate turned brown. Acid and gas from glucose, fructose, ga- lactose, maltose and sucrose. No acid or gas from dextrin, lactose or mannitol. See Moltke (Contributions to the Characteriza- tion and Systematic Classification of Bac. proteus vulgaris (Hauser) . Levin and Munks- gaard, Copenhagen, 1927, 156) for other fermentation characters. The ratio of H2 to CO2 is 1:1 (Speck and Stark, Jour. Bact., U, 1942, 687). Acetylmethylcarbinol not produced. Sodium citrate may be utilized as a sole source of carbon. Nitrites produced from nitrates. Phenylpyruvic acid is produced from phenylalanine, and leucine is rendered alka- line. Aerobic, facultatively anaerobic. Optimum temperature, 37° C. Pathogenic for fish and other animals such as dogs, guinea pigs and mice (Wyss, Ztschr. f. Hyg., 27, 1898, 143). Distinctive characters : X-strains of Weil and Felix. Lehmann-Neumann-Breed, De- terminative Bact., Eng. Trans., 7th Ed., 2, 1931, 493: "The discovery of proteus strains which may be agglutinated by ty-
