mycelium. Coagulated, followed by lique- faction. Potato: Good, lichenoid growth, covered with gray to brownish aerial mycelium with white spots. The plug becomes covered gray to black. Starch is hj'droh'zed. Tyrosinase reaction: Negative. Nitrites produced from nitrates. Source: Isolated from a small, unruptured potato scab. Habitat : Found in potatoes so far as known. 121. Streptoniyces craterifer (Millard and Burr, 1926) Waksman, 1953. {Actino- myces craterifer Millard and Burr, Ann. Appl. Biol., 13, 1926, 601; Waksman, in Waksman and Lechevalier, Actinomycetes and Their Antibiotics, Baltimore, 1953, 105.) cra.te'ri.fer. Gr. mas.n. crater a cup- shaped hollow; L. V. fero to bear; M.L. adj. craterifer cup (crater) -bearing. Aerial mycelium: Much branched; termi- nal branches dichotomously forked. Spores rectangular, 0.8 to 1.0 bj' 0.9 to 1.3 microns. Gelatin: Wrinkled surface growth. Aerial mycelium white. No soluble pigment. Rapid liquefaction. Agar: Colorless growth; scant, white aerial mycelium. No soluble pigment. Synthetic agar: Lichenoid, abundant, colorless growth. Aerial mj'celium mouse- gray. Numerous guttation drops, which leave blackish craters behind. Starch: Spreading, thin, colorless growth. No aerial mycelium. Glycerol synthetic solution : Good growth on surface of medium; numerous star-like colonies throughout medium. Aerial mj^- celium scant, white to mouse-gray. Glucose broth: Limited growth. Aerial mycelium white to gray. Milk: Cream-colored surface growth. Not coagulated; rapidly peptonized. Potato: Good, cream-colored growth. Aerial m3'celium white to mouse-gray. Color of plug unchanged. Starch is hydroh'zed. Tyrosinase reaction: Negative. Nitrites produced from nitrates. Only slight growth at 37.5° C. Source: Isolated from a large, raised, smooth potato scab. Habitat: Found in potatoes so far as known. 122. Streptoniyces gracilis (Millard and Burr, 1926) Waksman, 1953. (Actino- myces gracilis Millard and Burr, Ann. Appl. Biol., 13, 1926, 601; Waksman, In Waksman and Lechevalier, Actinomycetes and Their Antibiotics, Baltimore, 1953, 106.) gra'ci.lis. L. adj. gracilis slender. Vegetative growth: On synthetic media, dark brown, producing a soluble brown substance. Aerial mycelium: Dark olive. Spiral- forming sporophores. Spores ellipsoidal or spherical, 0.8 by 0.8 to 0.9 micron. Gelatin: Gray growth, covered with white aerial mycelium. Soluble, pink to dark golden brown pigment. Rapid liquefaction. Synthetic sucrose agar: Fern-like, pale gray growth covered with scant, gray to buff aerial mycelium. Soluble cream-colored pigment. Synthetic glucose agar: Smooth, pale olive-gray grow^th. Aerial mycelium abun- dant, white, smooth. Soluble cream-colored pigment. Nutrient potato agar: Vinaceous, buff to dark brown or almost black growth. Aerial mycelium gra}^ Soluble light golden brown pigment. Glycerol synthetic solution: Good growth on surface and throughout medium. Abun- dant aerial mycelium, white to olive-buff. Glucose broth: Good growth on surface and on bottom. Aerial mycelium abundant, olive-buff. Soluble, light golden brown pig- ment. Milk: Good surface growth. Aerial my- celium white in the form of a ring and specks on surface. Slowly coagulated, followed b}^ rapid peptonization. Potato: Good, echinate growth covered with abundant olive-gray to buff aerial mycelium. Plug light brown. Starch is hydrolyzed. TjTOsinase reaction: Negative. Nitrites produced from nitrates. Good growth at 37.5° C. Comment: According to Krassilnikov,
