FAMILY I. MYCOBACTEKIACEAE 713 



lar to each other. It is noteworthy that two man and Henrici. This culture was secured 

 of the red chromogenic species of Mj/cococcws by Breed from the Krdl collection in 1923 

 described above show a tetrad arrangement and differs from a culture (No. 2682) carried 

 of cells. for a time in the Nat. Coll. Type Cultures 

 Gordon (personal communication, 195-4) in London that came from the Amer. Mus. 

 reports that she finds an apparently authen- Nat. Hist. Coll. (Culture 184), origin un- 

 tie culture of Rhodococcus rhodochrous Zopf known, 

 to be identical with Nocardia corallina Waks- Habitat : Water. 



FAMILY II. ACTINOMYCETACEAE BUCHANAN, 1918.* 

 (Jour. Bact., 3, 1918, 403.) 



Ac.ti.no.my.ce.ta'ce.ae. M.L. mas.n. Actinomyces type genus of the family; -aceae end- 

 ing to denote a family; M.L. pi. noun Actinomycetaceae the Actinomyces family. 



Mycelium is non-septate during the early stages of growth but later may become septate 

 and break up into short segments, rod-shaped or spherical in shape, or the mycelium may 

 remain non-septate and produce spores on aerial hyphae. The organisms in culture media 

 are either colorless or produce various pigments. Some species are partially acid-fast. This 

 family is distinguished from the previous one by the formation of a true mycelium. As com- 

 pared with the next family, it is characterized by the manner of .spore formation. 



Key to the genera of family Actinomycetaceae. 



I. Obligately aerobic. The colonies are bacteria-like in nature, smooth, rough or folded, 

 of a soft to a dough-like consistency, sometimes compact and leathery in young stages. 

 Most forms do not produce any aerial mycelium; a few produce a limited mycelium, the 

 branches of which also break up into oidiospores or segmentation spores. Some species 

 are partially acid-fast. 



Genus I. Nocardia, p. 713. 

 II. Anaerobic or microaerophilic; parasitic; non-acid-fast, non-proteolytic and non-dia- 

 static. 



Genus II. Actinomyces, p. 742. 



Genus I. Nocardia Trevisan, 1889. 



(Trevisan, I generi e le specie delle Batteriacee, 1889, 9; Proactinomyces Jensen, Proc. 

 Linn. Soc. New So. Wales, 56, 1931, 345; Asteroides Puntoni and Leonardi, Boll. e. Atti d. 

 R. Accad. Med., 61, 1935, 90.) 



No.car'di.a. M.L. fem.n. Nocardia named for Prof. Edmund Nocard, who first des- 

 cribed the type species of this genus. 



Slender filaments or rods, frequently swollen and occasionally branched, forming a my- 

 celium which, after reaching a certain size, assumes the appearance of bacterium-like 

 growths. Shorter rods and coccoid forms are found in older cultures. Conidia not formed. 

 Stain readily, occasionally showing a slight degree of acid-fastness. Non-motile. f No endo- 



* Completely revised by Prof. S. A. Waksman, Rutgers University, New Brunswick, New- 

 Jersey, March, 1953. 



t H. L. Jensen (Symposium on Actinomycetales, VI Internat. Cong. Microbiol., Rome, 

 1953, Istituto Superiore di Sanita) comments on motility in nocardias as follows (unimpor- 

 tant editorial changes have been made in the text, such as the use of the term "nocardias" 

 for "proactinomycetes") : 



"Motility in the nocardias seems first to have been alleged in Nocardia asteroides by Ep- 



