iQig] DRECHSLER— ACTINOMYCES 153 



merits with considerably greater frequency, and secondary branch- 

 ing, characterized by the successive type of development, is com- 

 mon. 



Isolated once from soil collected in Cambridge, IMassachusetts. 



ACTINOMYCES VII 



Cultural characters. — On glucose agar, nutritive mycelium 

 colorless, early developing an aerial mycelium from the center 

 outward, the latter changing from white to light gray with increas- 

 ing age. On potato agar, nutritive mycelium luxuriant, developing 

 rapidly; aerial mycelium represented by a slight cretaceous develop- 

 ment toward the top of the slant; tyrosinase reaction vigorous. 



Morphology. — This species departs from the main trend of the 

 3 preceding forms in the relatively close arrangement of its branches 

 on the axial filament, and in the elaboration of these branches by 

 further ramifications in a typically successive order. Nearly 

 spherical to elKpsoidal spores, 0.6-0.8X0.7-1 .0 )u, are produced 

 from moderately close sinistrorse spirals of 3-8 turns 2 . 0-3 . o /x 

 in diameter, by the development represented in fig. yoa-e, but the 

 septa are relatively thin, and occasionally fall below the limit of 

 clear visibility. 



Isolated twice from soil collected in Cambridge, Massachusetts. 



ACTINOMYCES VIII 



Cultural characters. — ^On glucose agar, nutritive mycelium 

 nearly colorless, secreting a difi'usible yellow pigment; aerial my- 

 celium moderately profuse, velvety, first white, later changing to 

 a light bluish color. On potato agar, growth similar, but soluble 

 pigment absent; no tyrosinase reaction. 



Morphology. — ^The fertile hyphae of this species may be 

 attached to the axial filaments in a diffuse racemose arrangement 

 (fig. 46), or crowded in a compact capitate system. The swellings 

 in the axial filaments in figs. 43, 44, 45, and 46 at the bases of 

 sporogenous branches indicate the mode of origin of the Leptomitus- 

 like distensions shown in figs. 47 and 48. 



