tions, the violet organisms isolated from warm-blooded animals should be identified as C. janthinum not as C. violaceum. Key to the species of genus Chroniobacteriiim. I. Fresh-water and soil organisms that produce a violet chromogenesis. A. No growth at 37° C. 1. Gelatin stab may show violet ring or pellicle. 1. Chromohacterium violaceum. 2. Gelatin stab develops heavy membranous growth on liquefied gelatin. Usually violet in color. 2. Chromohacteniivi amethystinum. B. Growth at 37° C. 3. Chromohacterium janthinum. II. Optimum growth in media containing 12 per cent salt. Chromogenesis bluish to blue- brown or yellowish. 4. Chromohacterium marismortui. 1. Chroniobacterium violaceum (Schroeter, 1872) Bergonzini, 1881. {Bac- teridium violaceum Schroeter, Beitrage z. Biol. d. Pflanzen, 1, Heft 2, 1872, 126; Cro- mobacterium violaceum (sic) Bergonzini, Ann. Societa d. Naturalist! in Modena, Ser. 2, 14, 1881, 153.) vi.o.la'ce.um. L. adj. violaceus violet- colored. Slender rods, 0.8 to 1.0 by 2.0 to 5.0 mi- crons, occurring singlj^ and in chains. Mo- tile, usually by means of a single flagellum, but some cells show several flagella arranged peritrichously. Gram-negative. Gelatin colonies: Circular, gray, entire, sometimes with a violet center. Gelatin stab: Infundibuliform liquefac- tion, sometimes with violet ring or pellicle and sediment. Agar colonies: Whitish, fiat, glistening, moist, becoming violet. Agar slant: Violet, moist, sometimes gummy, shiny, spreading growth. Broth: Slightly turbid; violet ring; granu- lar to viscid sediment. Litmus milk: Violet ring or pellicle. Di- gestion slow. Alkaline. Potato: Growth yellow to dark violet. Loffier's blood serum: Slow liquefaction. Indole not produced. Acid from glucose and usually from mal- tose and sucrose. No acid from lactose. Nitrites produced from nitrates and fre- quently reduced further to a gas (N2). Aerobic, facultative. Temperature relations: Optimum, be- tween 25° and 30° C. Slight growth between 2° and 4° C. No growth at 37° C. Source: Isolated from slices of cooked potato which had been exposed to air con- tamination and then incubated at room temperature. Habitat: Soil and water. 2. Chroniobacterium amethystinvim (Chester, 1897) Holland, 1920. (Bacillus membranaceus amethystinus Eisenberg, Bakt. Diag., 1891, 421; Bacterium amethystinus (sic) Chester, Ann. Rept. Del. Col. Agr. Exp. Sta., 9, 1897, 117; Holland, Jour. Bact., 5, 1920, 222.) a.me.thj^s'ti.num. Gr. adj. amethystinus of amethyst. Rods, 0.5 to 0.8 by 1.0 to 1.4 microns, occurring singly. Motile with a single or occasionally with peritrichous flagella. Gram-negative. Gelatin colonies: Thin, bluish, becoming violet, crumpled. Gelatin stab: Heavy, violet-black pel- licle. Liquefied. Agar colonies : Deep violet, surface rugose. Agar slant: Thick, moist, gummy, rugose, yellowish white growth, becoming violet sometimes with a metallic luster. Broth: Pellicle; violet sediment; fluid becoming violet. Litmus milk: Violet pellicle. Digestion turning alkaline.
