120 ACTINOMYCETES 



Glucose agar: Smooth, round, cream-colored colonies, margin depressed, 

 centers elevated, hollow on reverse side; later a coherent membranous 

 growth, piled up, yellowish. 



Gelatin: Abundant nocculent growth along streak, round cream-colored 

 colonies on surface. Partial liquefaction in 14 days; complete liquefaction 

 in 2 months. 



Glycerol agar: Small, round, cream-colored, glistening colonies, heavy 

 texture, margins submerged ; later, colonies umbilicated, tending to be piled 

 up; after 6 weeks, growth very much convoluted and raised, broad sub- 

 merged margin, slightly reddish medium. 



Calcium agar: Small colorless membranous growth with undulating mar- 

 gin; later, centrally depressed into medium. 



Potato agar: Growth poor, small, colorless blister colonies, medium 

 slightly discolored. 



Dorset's egg medium: Round, flat, colorless, scale-like colonies, some 

 marked by concentric rings and slightly hollowed in center; growth be- 

 comes yellow-brown. 



Blood agar: Large, drab, heavily textured colonies; no aerial mycelium; 

 no hemolysis. 



Serum agar: Large colonies (3 to 4 mm in diameter), colorless, granular, 

 centrally elevated, depressed at margin, resembling limpets. 



Nutrient broth: Large coherent mass composed of fluffy colonies. 



Carrot plug: Colorless, spreading, moist, wrinkled growth in 6 weeks; 

 later a dull greenish brown, moist, very much wrinkled and depressed skin. 



Source: From the spleen in a case of acholuric jaundice. 



Remarks: Slightly acid-fast. 



141. Streptomyces hortonensis (Erikson) Waksman and Henrici. 

 (Erikson, D., Med. Research Council Spec. Rept. Ser. 203, 1935, 36.) 



Vegetative growth: Typical germination into very slowly growing uni- 

 cellular mycelium composed of long slender straight branching filaments. 



Aerial mycelium: Very sparse, straight aerial mycelium produced only 

 once on potato. Non-acid-fast. 



Nutrient agar: Very slow growth, a few smooth, cream-colored, coiled 

 colonies in 19 days; after 2 months, liberal, irregular convoluted growth. 



Glucose agar: Coiled and heaped up cream-colored translucent masses; 

 after 2 months, growth rounded, elevated, ridged outward from hollow 

 center. 



Potato: After 3 weeks, abundant, colorless, umbilicated, round colonies, 

 some coiled in raised masses; later, liberal olive-green growth, piled up, 

 dense, velvety gray-green aerial mycelium at top of slant, small, round, 

 fluffy white colonies in liquid at base. 



