becomes stratiform; liquid flaky; abundant sediment. Agar colonies: Circular, entire, creamy white, glistening, translucent, viscous. Agar slant: Growth filiform, flat, smooth, viscous, cream-colored, glistening with a copper sheen. Soil extract agar slant: Growth filiform, flat, smooth, cream-colored, glistening, slightly metallic, soft. Asparagine agar: Abundant, filiform, cream-colored, very viscous growth; edge wrinkled, surface smooth and glistening. Broth: Moderately turbid; no surface growth; whitish, viscous sediment. Potato: Pale brown, glistening, viscous. Milk: Slow clearing after 1 week without coagulation; abundant, white surface growth; reaction becoming alkaline. Indole not produced. Hydrogen sulfide produced in cysteine medium. Slight acid but no gas from glucose and sucrose. Acetylmethylcarbinol not produced. Starch is hydrolyzed. Nitrites produced from nitrates. Urease not produced. Utilizes nitrates and ammonium salts as nitrogen sources; citrates utilized as sole source of carbon. Catalase-positive. Aerobic, facultatively anaerobic. Temperature relations: Optimum, be- tween 20° C. and 26° C.; growth range, 10° to 35° C.; no growth at 37° C. Source: Isolated from soil. Habitat: Soil. 3. Arthrobacter simplex (Jensen, 1934) Lochhead, comb. nov. {Corynebactenum simplex Jensen, Proc. Linn. Soc. New So. Wales, 59, 1934, 43.) sim'plex. L. adj. simplex simple. Rods which vary in size with the culture medium, generally 0.4 to 0.5 by 1.0 to 3.0 microns; occasionally cells may attain a length of 6.0 microns. In older cultures the cells are shorter and become very small rods or cocci, measuring 0.4 to 0.5 by 0.5 to 0.8 micron. Though curved or swollen rods generally tend to be inconsistent in form, the tendency is less pronounced with this species. Generally non-motile; motile strains have been reported (Clark and Carr, Jour. Bact., 6£, 1951, 3 and 4). Gram-vari- able; coccoid cells are Gram-variable with a predominance of Gram-positive cells. Gelatin stab: Saccate liquefaction (2 to 4 days) becoming stratiform; slight surface growth; considerable sediment; liquid clear. Agar colonies: Circular, 1.0 to 1.5 mm in diameter, slightly raised, cream-colored, smooth, glistening. Agar slant: Growth filiform, cream-col- ored, smooth, glistening, soft; lobate edge. Soil extract agar slant: Growth filiform, flat, pale cream-colored, smooth, glistening, translucent, soft. Asparagine agar slant: Growth filiform, flat, pale cream-colored, smooth, glistening, soft. Broth: Moderately turbid; no surface growth; moderate, stringy sediment. Potato: Growth abundant, light brown, moist, glistening, membranous. Milk : Slow clearing (7 to 10 days) without coagulation, becoming alkaline. Indole not produced. Hydrogen sulfide produced in cysteine and thiosulfate media. Sugar media: Slight alkaline reaction; no gas produced. Acetylmethylcarbinol not produced. Starch not hydrolyzed. Nitrites produced from nitrates. Urease not produced. Utilizes nitrates and ammonium salts as nitrogen sources; citrates utilized as sole carbon source. Catalase-positive. Aerobic. Temperature relations: Optimum, be- tween 26° and 37° C; no growth at 10° or 45° C. Source: Isolated from Australian soil. Habitat: Soil. 4. Arthrobacter oxydans Sguros, 1954. (Proc. 54th Gen. Meeting, Soc. Amer. Bact., Pittsburgh, 1954, 21.) ox'y-dans. Gr. adj. oxys sharp; M.L. adj. oxydans oxidizing. Complete description furnished by Dr. P. L. Sguros.
