152 BOTANICAL GAZETTE [February 



less uniform diameter, and proliferating branches at relatively wide 

 intervals. 



Isolated twice from soil collected in Cambridge, Massachusetts. 



ACTINOMYCES V 



Cultural characters. — ^On glucose agar, nutritive mycelium 

 on reverse side slightly yellowish; the surface completely covered 

 with a luxuriant velvety or cottony weft of pinkish-yellow aerial 

 mycelium; guttation slight. On potato agar, nutritive mycehum 

 chocolate-colored, firm lichenoid, crimped around margin; aerial 

 mycelium, as on glucose agar, but less profuse; tyrosinase reaction 

 vigorous. 



Morphology. — The fertile hyphae, which are attached to 

 prostrate axial filaments at long intervals, are terminated by rela- 

 tively close sinistrorse spirals of 4-12 turns 2.0-4.0/^ in diameter, 

 developing spores (0.6-0.8X0.9-1.1 ju), like Actinomyces IV, by 

 the insertion of conspicuous septa, followed by their constriction 

 and conversion. A peculiar characteristic is found in the sterihza- 

 tion of the basal portion of the fertile hyphae, by an apparent 

 abortion of its lower potential spores. 



Isolated 3 times from soil collected in Cambridge, IVIassachusetts. 



ACTINOMYCES VI 



Cultural characters. — ^On glucose agar, nutritive mycelium 

 colorless, completely covered with a felty aerial mycelium, first 

 white, later assuming a deep smoky tinge. On potato agar, nutri- 

 tive mycelium excessively wrinkled, partially covered with a 

 slightly discolored aerial mycelium; tyrosinase reaction vigorous. 



Morphology.— The species appears closely allied to Actino- 

 myces V, differing from the latter chiefly in the absence of any 

 evidence of sterilization, and in the shorter length of its sinistrorse 

 sporogenous spirals, which consist of only 2-6 turns, 2.0-4.0 ju 

 in diameter. The spores are uninucleated, measure 0.7-0.8X0.9- 

 I . I /i, and are developed by the insertion and transformation of 

 conspicuous septa. Fertile hyphae are attached to the axial fila- 



