bacteriologist who first studied this organ- ism. Common name: Morgan's bacillus, type 1. Rods, 0.4 to 0.6 by 1.0 to 2.0 microns, oc- curring singlj'. Motile by means of peri- trichous flagella. See Rauss (loc. cit.) for a discussion of flagellation and its relation to the swarming characteristic. Gram-nega- tive. Gelatin colonies: Bluish gray, homogene- ous, smooth, entire. Gelatin stab: No liquefaction. Agar colonies: Grayish white, smooth, glistening growth. May show a tendency to spread somewhat on moist agar. Broth: Turbid. Litmus milk: Neutral or becoming alka- line. Potato: Dirty white, limited growth. Indole is produced. Hydrogen sulfide not produced. Acid and a small amount of gas from glucose, fructose, galactose and mannose; rarely from xylose. Does not attack lactose, sucrose, maltose, arabinose, raffinose, dex- trin, salicin, mannitol, dulcitol, sorbitol, adonitol or inositol. Acetylmethylcarbinol not produced. Sodium citrate not utilized as a sole source of carbon. Nitrites are produced from nitrates. Phenylpyruvic acid is produced from phenylalanine, and leucine is rendered alka- line. Aerobic, facultatively anaerobic. Optimum temperature, 37° C. Source: Isolated from the feces of infants with summer diarrhoea. Habitat: Found in the intestinal canal and in normal or diarrhoeal stools. 4. Proteus rettgeri (Hadley et al., 1918) Rustigian and Stuart, 1943. {Bacterium rettgeri Hadley, Elkins and Caldwell, Rhode Island Agr. Exp. Sta. Bull. 174, 1918, 169; Shigella rettgeri Weldin, Iowa State Coll. Jour. Sci., 1, 1927, 181; Proteus entericus Rustigian and Stuart, Jour. Bact., 45, 1943, 198; Rustigian and Stuart, Proc. Soc. Exp. Biol, and Med., 53, 1943, 241.) rett'ge.ri. M.L. gen. noun rettgeri of Rettger; named for L. F. Rettger, the Amer- ican bacteriologist who, in 1904, isolated this species. Rods, 0.5 to 0.8 micron long, occurring singly, in pairs and occasionally in chains. Usually non-motile at 37° C, but actively motile variants possessing peritrichous flagella can be obtained at 25° C. Gram- negative. Gelatin colonies: Small, grayish, trans- lucent, entire. Gelatin stab: No liquefaction. Agar colonies: Small, grayish, trans- lucent, entire. May show a tendency to spread on moist agar. Agar slant: Filiform to echinulate, gray- ish, thin, moist, translucent growth. Broth: Turbid; flocculent to viscid sedi- ment. Litmus milk: Alkaline in eight days, be- coming tran.slucent. Potato: Luxuriant, grayish growth. Indole is produced. Hydrogen sulfide not produced. Acid and occasionally slight gas from glucose, fructose, galactose, adonitol and mannitol. Salicin, inositol and rhamnose may or may not be fermented. Slow and sometimes weak acid from sucrose. Lactose and maltose are not fermented. Acetylmethylcarbinol is not produced. Sodium citrate is utilized as a sole source of carbon. Nitrites are produced from nitrates. Phenylpyruvic acid is produced from phenylalanine, and leucine is rendered alka- line. Aerobic, facultatively anaerobic. Optimum temperature, 37° C. Source : Originally isolated from a cholera- like epidemic among chickens; recently isolated from sporadic and epidemic gastro- enteritis patients. Habitat: Found in fecal matter. 5. Proteus inconstans (Ornstein, 1921) Shaw and Clarke, 1955. (Bacillus inconstans Ornstein, Ztschr. f. Hyg., 91, 1921, 152; Anaerogenic paracolon, type 29911, Stuart, Wheeler, Rustigian and Zimmerman, Jour. Bact., 45, 1943, 111; also see Stuart, Wheeler and McGann, Jour. Bact., 53, 1946, 431; Providence Group, Kauffmann, Entero- bacteriaceae. Munksgaard, Copenhagen,
