nig'ra. L. adj. niger black. Colonies rough, folded, shiny, of dough- like consistency. Growth at first colorless or brownish, gradually beconiing darker and, after 10 to 15 days, dark brown and even black. Pigment, similar to melanin, not soluble in the medium. Hyphae are thread- like, breaking up into rods, 0.7 by 2.0 to 10.0 microns, and cocci, 0.6 to 0.8 micron. Aerial mycelium not formed. Gelatin: No growth or liquefaction. Agar: Poor growth. Synthetic agar: Poor growth. Many cells are swollen to 3.0 microns in diameter. Broth; Small sediment produced. Medium clear. Milk: No change. Potato: Good growth. Cellulose: No growth. Source : Isolated from soil. Habitat: Soil. Rarely found. Growth rapidly disappears on continued cultivation. 27. Nocardia lutea Christopherson and Archibald, 1918. (Lancet, 2, 1918, 847). lu'te.a. L. adj. luteus yellow. Description taken from Erikson (Med. Res. Council Spec. Rept. Ser. 203, 1935, 30). Initial elements swollen and segmented, giving rise to irregular, spreading, polymor- phous colonies composed of cells of all shapes and sizes with markedly granular contents; later more monomorphous, the filaments being arranged in angular apposi- tion. Sometimes (e.g., on synthetic glycerol agar) the segments are so granular as to ap- pear banded. On potato agar, small, fila- mentous colonies are formed with irregular, angular branching, and which bear a few isolated short straight aerial hyphae. Gelatin: Pale pink wrinkled growth on wall of tube; colorless, punctiform colonies and stellate colonies are in the medium; no liquefaction. Agar: Abundant, coherent, moist, pink, membranous growth with round, discrete colonies at margin; after 3 weeks, colorless, fringed margin, round confluent portion. Glucose agar: Scant, reddish, smeary growth. Glycerol agar: Yellowish pink, wrinkled membrane. Potato agar: Coherent, pink, moist growth, centrally embedded with small, round, discrete colonies at margin. Dorset's egg medium: Poor growth, dull pink, spreading. Serum agar: Confluent, granular, pink membrane. Broth: Pink flakes and surface growth. Inspissated serum: Raised, convoluted, pink mass; becoming orange and much wrinkled with a scalloped margin. Synthetic sucrose solution: Red granules and abundant, minute, colorless colonies at bottom; in 2 weeks a colorless, dust-like surface pellicle. Glucose broth: Abundant, pinkish, flaky surface growth, breaking up easily and sink- ing to bottom. Potato plug: Carrot-red, moist, thick, granular growth in bands, partly raised, and with discrete round colonies; sparse, colorless, very thin aerial mycelium at top of slant in 2 months. Litmus milk: Orange-red surface and bottom growth; liquid blue. Source: Isolated from actinomycosis of the lachrymal gland. Habitat: Unknown, 28. Nocardia blackwellii (Erikson, 1935) Waksman and Henrici, 1948. {Actinomyces blackwellii Erikson, Med. Res. Council Spec. Rept. Ser. 203, 1935, 37; Waksman and Henrici, in Manual, 6th ed., 1948, 910.) black. wel'li.i. M.L. gen. noun blackwellii of Blackwell; named for Blackwell. Description taken from Erikson (op. cit., 1935, 32). Initial elements short and rod-like, grow- ing out into sparsely branching longer forms; small, radiating colonies are pro- duced with short, straight aerial mycelia; frequently large, round or ovoid cells are interposed in the irregularly segmented chains of cells, being sometimes isolated in company with 2 or 3 short filaments and sometimes terminal. Gelatin: Few, colorless, minute colonies along line of inoculation; after 30 days abundant, colorless colonies to 10 mm be- low surface, larger pink-yellow surface colonies with white aerial mycelium; no liquefaction. Agar: Confluent, wrinkled growth with
