INTRODUCTORY 



This volume deals exclusively with the well recognized genera of the actino 

 mycetes. No consideral ion is given here to the various closely related genera thai 

 are often included in the order Actinomycetales, notably the genus Mycobacterium 

 Lehmann and Neumann, 1896. 



The actinomycetes comprise three families, which are further subdivided into 

 10 genera. 



A. Spores formed, bu1 not in sporangia. 



I. Vegetative mycelium fragmenting into bacillary or coccoid elements. 

 Family I. Actinomycetaceae Buchanan. 



1. Anaerobic or microaerophilic, nonacid-fast. 



1 . ActinomyC( s I larz 



2. Aerobic, partially acid-fasl or nonacid-fast. 



2. Xocarrfia Trevisan 



11. Vegetative mycelium nonseptate, not fragmenting into bacillary or coc- 

 coid elements. 



Family II. Streptomycetacecu Waksman and Henrici. 

 1 . Aerial mycelium produced. 



a. Spores formed in chains. 



3. Streptomyces Waksman and Henrici 



b. Spores formed singly. 



4. Thermoactinomyces Tsiklinsky 



c. Spores occurring in pairs or in chains. 

 a 1 . Mesophilic forms, in pairs. 



."). Waksmania Lechevalier and Lechevalier 

 b 1 . Thermophilic forms, in pairs or in chains, 

 ti. Thermopolyspora Henssen 

 •_'. Aerial mycelium not produced. 



a. Spores occurring singly on short sporophores. 

 a 1 . Mesophilic forms. 



7. Micromonospora j )rskov 

 b 1 . Thermophilic forms. 



s. Thermomonospora Henssen 



B. Spore.- occurring in sporangia. 

 Family III. Actinoplanacecu Couch 



I. Aerial mycelium usually not formed, coiled conidial chain- lacking, spor- 

 angiospores mot ile. 



!t. Actinoplam s Couch 

 II. Aerial mycelium abundant, coiled conidial chains ;i- well ;i> sporangia 

 formed in some species, sporangiospores nonmotile. 

 10. stn ptosporangium Couch 



