I50 • BOTANICAL GAZETTE [February 



with spore production, and their insertion at distensions in the 

 sporogenous hyphae. A comparison of branch ci with the younger 

 branch C2 (fig. 5) corresponding to the conditions shown diagram- 

 matically in figs. Sb and 8c respectively, shows that the growth in 

 thickness of the hyphae takes place subsequent to the appearance 

 of the septa. After the filament has attained its growth, the septa 

 split along a median plane (figs. 5a, 5^7, M), and the 2 halves are 

 drawn apart by the contraction of the delimited protoplasts. 

 Further maturation occurs in the distribution of the deeply stain- 

 ing wall substance, in the strengthening of the peripheral wall, 

 and by an enlargement of the latter, the elimination of the median, 

 hourglass-like constriction of the spore, resulting finally in an 

 approximately cylindrical structure measuring o . 7-0 .9X0. 8-1 . i [x. 



The terminal and the basal spores of each chain retain a some- 

 what asymmetrical shape, owing to the absence of the massive 

 septum at one of their ends. By an apparently abnormal develop- 

 ment, metachromatic granules may be formed in the spores derived 

 from some hyphae, resulting in a condition illustrated in the lowest 

 spore in fig. 8/. 



The axial filaments are represented by long prostrate hyphae, 

 branching at irregular, long intervals. Septation is confined to the 

 fertile branches. The sterile hyphal portions below the spo- 

 rogenous terminations taper gradually toward their attenuated 

 attachments. Development and sporogenesis near the axial 

 terminations are successive, and involve the formation of close 

 sinistrorse spirals of 1-5 turns, 3 .5-6.0 ix in diameter. 



Isolated 3 times from soil collected in Cambridge, Massachusetts. 



ACTINOMYCES III 



A. lavendulae Waksman and Curtis 



Cultural characters. — On glucose agar, nutritive mycelium 

 slightly yellow on reverse side, central area completely covered with 

 velvety aerial mycelium, first white but gradually assuming a 

 beautiful lavender shade; no soluble stain. On potato agar, growth 

 very profuse; mycelium abundant, changing from white to laven- 

 der; guttation moderate to profuse; tyrosinase reaction vigorous. 



