156 BOTANICAL GAZETTE [February 



attributed this preponderance in the air to its omnivorous char- 

 acter, enabhng it to develop on a large variety of substrata, 

 "Questa Streptothrix cresce, si puo dire, dappertutto, tanto su ter- 

 reni di natura vegetale quanto su terreni di natura animale. E per 

 cio nonche la grande sua produzione di spore, che essa si trova cosi 

 diffusa nell'aria ed altrove. Pare che essa possa svilupparsi anche 

 nel terreno." In spite oif this fortunate and quite distinctive char- 

 acterization, the specific term "albus" subsequently came to be 

 used in a manner as miscellaneous as " chromogenus," being applied 

 generally to any type with a Hght mycelium showing no tyrosinase 

 reaction. 



The same species was treated in the publication of Waksman 

 and Curtis as Actinomyces griseus Krainsky. I have not been 

 able to satisfy myself fully about the identity of Krainsky's 

 organism; nor would it seem possible to reach any definite con- 

 clusion without an examination of authentic material. 



ACTINOMYCES XI 



Cultural characters. ^On glucose agar, nutritive mycelium 

 first colorless, becoming sHghtly reddened with increasing age; 

 aerial mycelium first white, rapidly changing to a bluish violet. 

 On potato agar, nutritive mycelium gradually becomes deep red 

 by the slow accumulation of a slightly diffusible pigment ; tyrosinase 

 reaction absent. 



Morphology. — More or less erect fructifications are developed 

 along the distal portions of long prostrate filaments. Branching 

 is abundant and only occasionally shows indications of a successive 

 sequence. The aerial hyphae in the dendroidic structures (figs. 64, 

 66) are often conspicuously vacuolate, especially in the inflated 

 distensions from which a number of fertile branches arise. The 

 latter terminate in sinistrorse spirals of 4-6 turns, 2.0-3.0 m in 

 diameter, from which, by the insertion of conspicuous septa and 

 their subsequent transformation to hyaline isthmuses, spores 

 o . 5-0 .7X1 .0-1 . 2 fj. are produced. 



Isolated once from soil collected in Cambridge, Massachusetts; identical 

 with an organism isolated by Mr. H. J. Conn from soil collected near Geneva, 

 New York. 



