984 MANUAL OF DETERMINATIVE BACTERIOLOGY 



Saccardo, Sylloge P'ungorum, 6, 1889, 929; Chlatnydolhrix Migula, Syst. d. Bakt., 2, 

 1900, 1030; Conidiothrix Benecke, Bau u. Leben d. Bakt., 1912, 489; Megalothrix 

 Schwers, Cent. f. Bakt., II Abt., 33, 1912, 273; S7jncrotis Enderleiu, Sitzber. Gesell. 

 Naturf. Freunde, Berlin, 1917, 312.) From Greek leptos, small and thrix, hair. 



Filaments of cylindrical colorless cells, with a sheath at first thin and colorless, 

 later thicker, yellow or brown, encrusted with ferric hydroxide. The oxide may be 

 dissolved by dilute acid, whereupon the inner cells show up well. Multiplication is 

 by division and abstraction of cells and by motile cjiindrical swarmers. False 

 branching may occur. 



The tjqie species is Leptothrix ochracca Kiitzing. 



Key to tlic species of (jcnus Leptothrix. 



I. Filaments not spirally twisteil. 



A. Free swimming, not attached. 



1. Sheath homogeneous, cylindrical. 



1. Leptothrix ochracca. 



2. Sheath composed of a bundle of fine parallel filaments. 



2. Leptothrix trichocjeyxes. 



B. Attached to a substrate by a holdfast. 



1. .\rising singly, each filament from its own holdfast. 



a. Filaments show false branching. 



3. Leptothrix discophora. 

 aa. Filaments unbranched. 



4. Leptothrix sidcropous. 



2. Numerous filaments arising from a common holdfast. 



a. Filaments large, uniform in diameter. 



5. Leptothrix lopholea. 

 aa. Filaments smaller, tapering toward the tip. 



6. Leptothi ix echinatn. 

 II. Filaments spirally twisted. 



A. Epiphytic, growing twisted around filamentous algae. 



7. Leptothrix epiphylica. 



B. Not epiphytic, 



8. Leptothrix pseudoracuolata. 



1. Leptothrix ochracea Kiitzing. Sheath homogeneous, completely dis- 



(Ktitzing, Phycologia Generalis, 1843, solving in dilute hydrochloric acid. 



198; Lyngbya ochracea Thuret, Ann. When the sheath becomes vezy thick, 



Sci. Nat. Bot., VI, /, 1875, 279; Beggiatoa tlie filaments creej) out of the sheath and 



ochracea Gasperini, Ann. d'lgiene Sper., .spcrolc a new one, so that many emi)ty 



2, 1912, 000; Chlamydothrix ochracea .si„..iil,s arc found. Polar flagellate. 



Migula, Syst. d. Bakt., 2, 1900, 1031.) ,j^,,,j,^. swarm-cells have been observed. 



From Latin ochra, yellovv. ^^^.^^^ , Iron-l,earing waters. 



Long filaments, free-noating, never 



attached to a substrate, never branch- ^,, . ■ 



ing. Filaments 1 micron in thickness, " Leptothrix trichogenes Cholodny. 



composed of rod-like colorless cells, sur- (<^'l'<^l«Hlny, Gent. 1. Bakt., II Abt., 61, 



rounded in young filaments by a delicate 1924, 292 ; Toxothrix ferruginea Molisch , 



sheath which later becomes yellow to Die Ei.senbakterien in Japan, Sc. Report 



brown in color. Tohoku .J. Univ., 4 Ser. Biol., 1, 1925, 



