\()Mi;N(i.\'i'ri!i: and (;i;\i:i{ai, s^s'l"I:^Is of ci.Assii-icA'rioN 



;>/ 



sporos. Without uraiHiU's of t'roo siilt'ur and willioiil 

 l)Mct(>rioi)uri)uriii. N'cvcr producing a psciido- 

 plasmodiwm. Al\\a\s iKniinotilc. 



Ttic order Actinoniycotalos coutaiiis a single 

 tainilv , AcHnoiin/cctaceae. 



I''amil\ I. Aclinoiiii/ccldCKii 

 A. No ('\id('iit aerial tlireads or eoiiidia t'orined. 

 I'suallx parasitic. ()rt(Mi aiiatM(il)ic oi- iiiicio 

 aer()|)luli('. 



1. Threads usually uot hrauclied. 



Threads disjointiufi very readily; lonn my- 

 celial threads uiu'ommon. 



(lenus I. Actinolxtrilliis 



1). Tiweads longer, not disjointing into short 

 rods (Jenus 2. Lfplotrichia 



2. Thr(\'ids more or less branched, t're(|uently 

 cluhixMl in tissues (lenus 'A. Adinonii/rcs 



H. Aerial threads and conidia evident on culture 

 media ( ienus 4. Xocardici 



CJenus 3. Actinonii/ces Harz 

 Branched filaments, resembling mycelium, 

 breaking up into segments which may function as 

 conidia. Usually parasitic. Clubbed ends conspic- 

 uous in lesions. Not producing aerial hyphae or 

 conidia. 



The tyi)e species is Actinoini/ces horis Harz, the 

 cause of bovine actinomycosis. 



(ienus 4. Nocardia Trevisan 

 Branched filaments, resembling a mycelium, 

 readily breaking up into segments. Usually sapro- 

 phytic. Aerial threads and conidia commonly pro- 

 duced. 



Ill the preliminary report of the Com- 

 mittee of the Societ}^ of American Bacteriol- 

 ogist.^^ (Winslow et al., 1917), the genera 

 Actinomijccs and Nocardia were placed in the 

 family M i/cobacteriaceae , in the order Eulxic- 

 t(n"iales. The difference between the two 

 genera was based on the assumption that 

 members of the genus Actinomyces do not 

 produce an\' aerial mycelium and are usually 

 parasitic. 



Castellani and Chalmers (1919) included 

 the actinomycetes among the Hyphomycetes, 

 in the order Microsiphonales, created by 

 A'uillemin in 1912. This order was divided 

 into two families, 1. N ocardiaceae , forming a 

 mycelium (Hyn. Actinomycetes Lachner- 

 Sandoval, 1898; Trichomycetes Petruschky, 



I '.)().')); 2. M firohdctiriacKU, witlidiil ;i iiiyce- 

 liinn. 



riic .\()c(tii/i(ic< (K were di\i(l('(l ;is lollows: 



I . ( Irow ;i('r(il»ic;illy, easy to cull i\;it(', ;ind 

 produce ;irt hrospores. 



(lenus 1. Xorardid I )e 'j'oni and Tre- 

 visan, 1889. 



II. (Irow best anaerobically, but can often 

 grow aerobically; diflicult to cultivate and 

 do not produce art hrospores. 



C.enus'J. Cohnistrcptothn'.r Pinoy, l*.)l 1. 



Ill the final report of the Committee of the 

 Society of American l^acteriologists (Wins- 

 low ('/ fl/., \\)20) the family M ijcohactcriaceae 

 was ele\'ated to the order Actinomycetales, 

 which was divided into two families: Aciino- 

 mycctaccac and M ycobacfcn'aceac. The genus 

 Actinomyces was placed in the first family. 

 The genus Nocardia was dropped (see also 

 Breed and (Vnin, 1919). 



The following description of the order 

 Actinomycetales was given in the first edi- 

 tion of Bergey (1923, p. 3:^7): "Cells usually 

 elongated, freciuently filamentous and with 

 a decided tendency to the development of 

 branches in some genera giving rise to the 

 formation of a definite branched mycelium. 

 Cells fre(iuently show swellings, clubbed or 

 irregular shapes. Some species are parasitic 

 in animals or plants. As a rule strongly 

 aerobic (except for some species of Actino- 

 myces and the genera Fusiformis and Lepto- 

 trichia) and oxidati\'e. Growth on culture 

 media often slow; some genera .show mold- 

 like colonies." The order was divided into 

 two families: 1. The Actinomycetaceae, con- 

 taining, in addition to the first three genera 

 included l)y Buchanan (the genus Nocardia 

 having been dropped), also the genus Erysi- 

 pclothrix. 2. The M ycohacteriaceae w'ith three 

 geiuM'a : Proactinomyces, Corynehacterium , 

 and M yrobacterium. 



Lehmann and Neumann, in their later 

 editions, divided the actinomycetes into 

 two families: Proactinomycetaceae with two 



