26 



THE ACTINOMYCETES, Vol. II 



Figure 10. A 7 , rubra: (above) 24 hr, glycerol 

 nutrient agar, methylene blue; (below) same, 

 stained with Sudan black B, X 1600 (Reproduced 

 from: McClung, N. M. Lloydia 12: 165, 1040). 



bacterium, Gordon and Smith (1955) exam- 

 ined 152 cultures labelled Streptomyces and 

 99 cultures labelled Nocardia; those strains 

 of the latter that formed soft, fragmenting, 

 vegetative mycelium were excluded. Of the 

 cultures designated as Streptomyces, 83 per 

 cent produced an aerial mycelium typical of 

 this genus; 13 per cent failed to produce 

 aerial mycelium, although a few formed rudi- 

 mentary aerial hyphae; inability to form 

 spores was considered as a lost property, 

 since the physiological reactions of the 

 strains were the same as in the previous 

 group of sporulating cultures; only five 

 strains, or 4 per cent of the cultures possessed 

 nocardia] properties. Of the cultures desig- 

 nated as Nocardia, 68 produced aerial hy- 

 phae, varying from rudimentary to luxuri- 

 ant, some even forming chains of spores. 

 According to their physiological properties, 

 24 nt these cultures should have been desig- 

 nated as Streptomyces. A few of the strains 



could be considered as intermediate between 

 the two genera. 



Gordon and Mihm (1957) further reported 

 the results of an examination of 219 cultures 

 labelled Streptomyces, 214 Nocardia, and 243 



Table 2 



Certain physiological and biochemical characteris 



tics of various strains of two species of Nocardia 



(Gordon and Mihm, 1050) 



