Short rods, 0.5 by 0.6 micron, occurring in pairs, sometimes in fours or, in broth, in long filaments. Actively motile. Gram-nega- tive. Gelatin colonies: Small, j-ellowish gray becoming pink, very slimy. Carmine-red pellicle. Liquefaction. Gelatin stab: Rapid liquefaction. Grajdsh pellicle which becomes red after 24 hours and later precipitates. Slimy. Agar colonies: Dull, white to pinkish growth. Broth: Rapid turbidity; thick, slimy, white pellicle which later turns red; purplish sediment; liquid becomes pink and syrupy; in old cultures the broth is brown. Potato: At 37° to 39° C., red pigment visi- ble after 8 hours. At room temperatures growth is at first white and slimy, later red. Strong odor of trimethylamine. Distinctive characters: Pigment soluble in alcohol. Good pigment production at 37° to 39° C. The original cultures were heavily pigmented, and thus the pigment showed some solubility in water as does that of Serratia tnarcescens Bizio under similar conditions. The original cultures were slimy, but slimy (mucoid) cultures also occur in S. marcescens. Comments: In recent years cultures of Serratia have been isolated from various human infections (Gurevitch and Weber, loc. cit.; Wheat, Zuckerman and Rantz, Arch. Internal Med., 88, 1951, 461; Vernon and Hepler, Quart. Bull., Northwestern Univ. Med. School, 28, 1954, 366). In some of these cases, new names have been given to the organisms isolated without adequate justification, for these organisms seem to possess the same characters as do those that were originally isolated from felons on the hands of men handling fish. Source: Isolated in 1893 from a box of oil-packed sardines at a canning factory in France. Also found in the red pus from fish- ermen and sardine-factory workers suffering from felons. In these lesions this organism is associated with an anaerobe, but by itself it is not pathogenic. Habitat: Presumably widely distributed. TRIBE IV. PROTEEAE CASTELLANI AND CHALMERS, 1919. (Manual of Trop. Med., 3rd ed., 1919, 932.) Pro.te'e.ae. Gr. noun Proteus type genus of the tribe; -eae ending to denote a tribe; M.L. fem.pl.n. Proteeae the Proteus tribe. Characters as for the genus. There is a single genus. Genus VIII. Proteus Hauser, 1885.* (Hauser, Sitzber. d. phys.-med. Sozietat zu Erlangen, 1885, 156; Liquidohacterium Orla- Jensen,' Cent. f. Bakt., II Abt., 22, 1909, 337; Spirilina Hueppe, Wiesbaden, 1886, 146; Eisenbergia Enderlein, Sitzber. Ges. Naturf. Freunde, Berlin, 1917, 315.) Pro'te.us. Gr. noun Proteus an ocean god who took many shapes. Straight rods. Motile by means of peritrichous, occasionally very numerous, flagella; generally actively motile at 25° C, but at 37° C. motility may be weak or absent. f Gram- negative. Two species (Proteus vulgaris and P. mirabilis) produce amoeboid colonies which show a swarming phenomenon on solid media devoid of bile salts. On moist agar the re- maining species produce colonies which spread to some extent. Spreading colonies can usually be induced to swarm. Pleomorphism is characteristic only of young, actively swarm- Revised by Prof. C. A. Stuart, Brown University, Providence, Rhode Island, July, 1955. t See Leifson, Carhart and Fulton (Jour. Bact. the type of flagellation found in this genus. 1955, 73) for a recent discussion of
