Key to the Genera 



Class i. SCHIZOMYCETES 



Typically one-celled fungi, dividing by fission in I, 2 or 3 planes, sometimes 

 forming true filaments, but then motile or sheathed, and without true branches ; 

 resting cells often developed; sexual reproduction lacking. 



Order 1. BACTERIALES 



Globose, rod-like or filamentous, single or in colonies, sometimes grouped 

 into a loose mass (zoogloea), but never forming pseudoplasmodia or sporangium-like 

 masses. 



Family 1. BEGGIATOACEAE 



MlGULA 40 



Filaments simple, free, motile, continuous or septate, sheathless, usually filled 

 with shining or yellowish sulphur granules. 

 A single genus Beggiatoa 8: 935 



Family 2. CHLAMYDOBACTERIACEAE 



Migula 35 



Filaments simple or false-branched, typically attached, non-motile, septate, with 

 a more or less conspicuous sheath ; propagation by ciliate, creeping or non-motile 

 conidia. 



I. Cells without sulphur granules 



1. Filaments simple 



a. Fission always in one plane Nocardia 8: 927 



b. Fission in 3 planes during conidia formation 



(1) Filaments marine, sheath very thin 



Phragmidiothrix 8: 935 



(2) Filaments fresh-water, sheath distinct 



Crenothrix 8: 925 



2. Filaments false-branched Cladothrix 8: 927 



II. Cells with sulphur granules Thiothrix 8: 934 



Family 3. SPIRILLACEAE 



Migula 30 



One-celled, more or less spirally twisted, rod-like or short-filamentous, usually 

 motile by means of one to many flagella. 

 I. Cells stiff or rigid 



