THE CHLAMYDOBACTERIALES 305 



Genus 3. Crenothrix Cohn, 1870, p. 130 



Filaments unbranched, showing differentiation of base and tip, 

 attached, usually thicker toward the tip. Sheaths plainly visible 

 usually colorless, brownish from iron oxid in old filarnents. Cells 

 cyclindric to spherical. Multiplication by non-motile, spherical, 

 conidia; cells dividing in 3 planes to form conidia. 



The type (and only) species is Crenothrix polyspora Cohn. 



Genus 4. Sphaerotilus Kuetzing, 1833, p. 385 



Synonyms : 



Cladothrix Cohn, 1875, p. 185 



Attached colorless threads showing false branching, making a 

 psuedodichotomy . Filaments consist of rod or oval cells, surrounded 

 by a thin, firm sheath. Multiplication occurs both by non-motile 

 and motile gonidia, the latter with a clump of flagella near one end. 



Sphaerotilus natans Kuetzing is the type. 



Genus 5. Cionothrix Schorler, 1904, p. 689 



Filaments with false dichotomous or irregular branching, attached, 

 with contrast of base and tip, tapering to the tip. Sheath always 

 present, thin on young filaments, later becoming thicker and en- 

 crusted with iron or manganese. Multiplication by small non- 

 motile gonidia of spherical form, formed from the disk shaped cells 

 near tip by longitudinal division on rounding up. 



The type species is Cionothrix fusca Schorler. 



REFERENCES 



Benecke, Wilhelm 1912 Bau und Leben der Bakterien. 



Billroth, Theodor 1874 Coccobacteria septica. 



BoRY DE St. Vincent 1823 Diet. Classique d'hist. nat. according to Ehrenberg. 



Cohn, Ferdinand 1872 Untersuchungen liber Bakterien. Beitriige zur 



Biologie der Pflanzen. 1 (Heft 1), 127-224. 

 Cohn, Ferdinand 1875 Untersuchungen iiber Bakterien. II. Beitrage zur 



Biologie der Pflanzen. 1 (Heft 3): 141-208. 

 DeToni, J. B. and Trevisan, V. 1889 Schizomycetaceae Naeg. in Saccardo's 



Sylloge Fungorum. 8, 923-1087. 



