xoMKXCLATrHK Axi) (;i:\i:hai, s^•sTl:Ms of classikicatiox 



65 



rat(\ Soini' of these must receixc (•;ii'el'itl 

 cousulcration, since they are hasi^l upon 

 t'uiulanuMital inorpholoj^ieal couceijts. Others 

 siiouKl l)e modifiod, at least for the present, 

 lu'cause the diiTerences observed are larjj;ely 

 quantitative rather than (lualitative. The 

 creation of new species on the basis of their 

 economic importance tends to create confu- 

 sion in the proper identification of the orj^an- 

 isms. 



On tiie basis of these and other modifica- 

 tions of the classification system of Waksman 

 and Henrici, the following classification of 

 th(> actinomycetes may be presented. 



ORDER ACTINOMYCETALES 



Organisms forming filamentous cells with a 

 definite tendency to branch. Hyphae do not ex- 

 ceed 1.5 M and are mostly about 1 ;u or less in di- 

 ameter. Usually producing a characteristic 

 l)ranching m3'celium. Multiplication by means of 

 special spores, oidiospores, conidia, or sporangio- 

 spores, or combinations of these spores. Special 

 spores are formed by fragmentation of the plasma 

 within straight or spiral-shaped spore-bearing 

 hyphae; the oidiospores are formed by segmenta- 

 tion, or by transverse division of hj-phae, similar 

 to the formation of oidia among the true fungi. 

 Conidia produced singly, at the end of simple or 

 branching conidiophores; these spores maj^ be 

 t)orne singly, in pairs, or in chains. Sporangiospores 

 are borne in spherical or variously shaped spor- 

 angia. These organisms grow readily on arti- 

 ficial media and form well-developed colonies. 

 The surface of the colony maj' become cov- 

 ered with a special aerial mycelium. Some of 

 the organisms are colorless or white, whereas 

 others form a variet^y of pigments. Thej^ are either 

 saprophytic or parasitic. In relation to tempera- 

 ture, most are mesophilic while some are ther- 

 mophilic. Certain forms are capable of growing at 

 low o.xygen tension. 



A. Mycelium rudimentary or al)sent, no spores 

 formed. 



Famih' I. M ycobacleriaceae Chester 

 I. Acid-fast organisms 



Mycobacterium Lehmann and Neumann 



B. True mycelium produced, spores formed, but 

 not in sporangia. 



I. Vegetative mycolium fragmenting into 

 bacillar}' or coccoid elements. 

 Famih' II. Aclinotnycelaceae Buchanan 



1. Aiiaciobic or niicrdacrDphiiic, parasitic, 

 iKiiiaciil last. 



1 . Arlinoin yccs Harz 



2. .Aerobic, parli;ill\ acid f;ist or non acid 

 fast. 



2. Socardia Trevisan 



11. X'egctativc niNccHum nonseptate, not 

 fragmenting into l)a<'illary or coccoid ele- 

 ments. 



i'.'unily 111. Slrc/tloui i/c<i(irc(ic Waksman 

 and Henrici 



1. Aerial mycciiuni not iircxhiccd. 



a. Spores formetl singly on short sporo- 

 phores. 

 a'. Mesophilic forms. 



3. M icioinonuspora ^rs- 



kov 

 b'. Thermophilic forms. 



4. Thermomotiospord 

 Henssen 



2. Aerial mycelium i)roduced. 



a. Spores formed in chains. 



5. Streplo)nyces Waksman 

 and Henrici 



b. Spores formed singly. 



6. Thernioaclinoniyces 

 Tsiklinsky 



c. Spores formed in pairs or in chains, 

 a'. Mesophilic forms, in pairs. 



7. Waksmania Lecheva- 

 licr and Lcchevalier 



(M iciohispora Xonomura and Ohara) 

 b'. Thermophilic forms, in pairs or in 

 chains. 



8. Thermopolyspora 

 Henssen 



C. True mycelium produced as in B above, spores 

 formed in sporangia. 



Family IV. Acdnoplanaceae. 

 I. Aerial mycelium usually not formed, coiled 

 conidiophores lacking, sporangiospores 

 motile. 



9. Aclinoplanes Couch 

 II. Aerial mycelium abundant, coiled coni- 

 diophores as well as sporangia formed in 

 some species, sporangiospores nonmotile. 



10. Streptosporanqium 

 Couch 



The true actinomycetes are thus shown to com- 

 ])rise 10 genera. 



Other Developments 



The a))o\-e system has been variously 

 modified and new .systems have been pro- 

 posed. Some of the modifications, especially 



