rarely producing an aerial mycelium, though in certain strains it may occur frequently. Retains the mycelium form for long periods. Not acid-fast. Gelatin: Liquefaction. In the young colony an orange-yellow to orange-red, intercellular pigment is pro- duced on all media, which may or may not change to black as the culture ages. Milk: No digestion. Starch is hydrolyzed. Paraffin not utilized. Source: Isolated from soil. Habitat: Soil. 40. Nocardia rhodnii (Erikson, 1935) Waksman and Henrici, 1948. (Actinomyces rhodnii Erikson, Med. Res. Council Spec. Rept. Ser. 203, 1935, 37; Waksman and Hen- rici, in Manual, 6th ed., 1948, 914.) rhod'ni.i. M.L. mas.n. Rhodnius generic name of an insect; M.L. gen.noun rhodnii of Rhodnius. In early stages, the minute colonies are composed of hyphal segments arranged in angular apposition, the aerial mycelium being short and straight. Later the growth becomes extensive and spreading, made up partly of long, genuinely branching fila- ments and partly of short segments exhibit- ing slipping branching, each giving rise to aerial hyphae. After 2 weeks the angular branching is very marked, delicate spread- ing herring-bone patterns being formed. Gelatin: Rapid liquefaction; pale pink colonies in superficial pellicle and sediment. Coon's agar: Colorless, pinpoint colonies. Czapek's agar: Minute, colorless, round colonies. Glucose agar: Abundant, coral -pink, con- voluted, piled-up growth. Glycerol agar: Extensive growth, dull pink colonies round and umbilicated, be- coming piled-up and deeper coral; later partly submerged. Dorset's egg medium: Salmon-pink, granular membrane; later piled up. Serum agar: Extensive, reddish, confluent mass, granular, tending to be piled up; the medium around the growth shows reddish coloration in 2 weeks. Inspissated serum: Smooth, round, pale pink colonies, centrally depressed and ir- regularly coiled larger mass; no liquefac- tion. Broth: Salmon-pink flakes in sediment and colonies on surface; after 2 weeks, abundant growth and discoloration of medium. Glucose broth: Thin, pink, superflcial pellicle, easily breaking up, and small flakes in sediment; after 2 weeks abundant growth extending up tube. Synthetic sucrose solution: Colorless to pink colonies in superficial pellicle and minute, round, white colonies coherent in loosely branching mass in sediment. Milk: Bright orange growth; medium un- changed. Potato agar: Abundant, pink growth, piled up; scant stiff white aerial mycelium at top of slant. Source: Isolated from the reduvid bug, Rhodnius prolixus. Habitat: Presumably insects. 41. Nocardia gardneri (Waksman, 1942) Waksman and Henrici, 1948. (Actinomycete, Gardner and Chain, Brit. Jour. Exp. Path., £3, 1942, 123; Proactinomyces gardneri Waks- man, in Waksman, Horning, Welsch and Woodruff, Soil Sci., 54, 1942, 289; Waksman and Henrici, in Manual, 6th ed., 1948, 914.) gard'ne.ri. M.L. gen.noun gardneri of Gardner; named for Prof. A. D. Gardner, one of the two who first isolated this or- ganism. Branching mycelium. Gram-positive. Gelatin: Cream-colored surface ring. Rapid liquefaction. Green to greenish brown soluble pigment gradually diffuses through the liquefied portion. Nutrient agar: Cream-colored, elevated, lichenoid growth, soft, not leathery; no aerial mycelium; very faint brownish pig- ment. Glucose agar: Brownish, lichenoid growth, with wide, cream-colored edge; white to grayish aerial mycelium gradually covering surface. Reverse of growth yellow- ish; no soluble pigment. Glucose-asparagine agar: Aerial mycelium develops slowly. Tr3'ptone broth: Growth occurs as small pellets at the base of the flask; later, a thin surface pellicle appears which consists of a
