348 GENERAL SYSTEMATIC BACTERIOLOGY 



Schroter (1886, p. 170) used the following generic description: 

 "Faden sehr zart, mit dimnen Scheiden, unbeweglich, Gliederung an- 

 fangs undeutlich. Vermehrung diirch Zerfall des Fadens in Glieder." 

 He includes three species onty, L. ochracea, L. parasitica and L. buc- 

 calis. It may be noted that this definitely excludes from the genus 

 the more strictly algal forms. He furthermore emphasizes a possible 

 relationship of L. ochracea to Gallionella ferruginea. 



Hansgirg (1888, p. 230) recognized this as the only genus of his sub- 

 family Leptothricheae. He described one new species, Leptothrix 

 cellaris and listed two others, L. ochracea and L. Thuretiana. 



De Toni and Trevisan (1889, p. 930) removed L. buccalis to a new 

 genus Rasmussenia to include five species, all of them forms from the 

 mouth and related to L. buccalis. The genus Leptotrichia was re- 

 served for some of them excluding L. ochracea. This species together 

 with two others are included in still another genus, Detoniella. 



Billet (1890, p. 23) says "Leptothrix, Element filamenteux dout la 

 longueur depasse 10 fois la largeur." 



Hueppe (1891, p. 30) states "Leptothrix unterscheidet sich von den 

 arthrosporen Bakteriuaceen dadurch, dass die Faden einem Gegensatz 

 von Basis und Spitze zeigen." 



Leptothrix according to Ludwig (1892) includes bacteria which occur 

 in long filaments, are unbranched, are without spores and are non- 

 motile. 



The tendency of those interested primarily in medical bacteriology 

 to limit the term Leptothrix to filamentous bacteria from the mouth 

 is well shown in the following statement from Mace (1897, p. 1020). 



Le genre Leptothrix n'est peut-etre pas a distinguer due genre Bacillus. Beau- 

 coup de Bacilles, en effet, possedent la propri^te, dans des conditions particu- 

 lieres de milieu, de croitre en tres longs filaments dont la composition en baton- 

 nets n'est visible que lorsqu 'on les traite par des reactifs coagulants ou coiorants. 

 Or, c'est ce qui arrive pour le seul Leptothrix dont la morphologie est un peu con- 

 nue, celui de la bouche. Plusieurs especes de Bacteries en batonnets, habitant 

 normalement la cavite buccale, peuvent peutetre contribuer, k cause des condi- 

 tions de milieu, k donner ces touffes de longs filaments; on s'expliquerait alors 

 facilement la divergence des caracteres exposes par les divers auteurs, surtout la 

 difference des dimensions. 



Chester (1901, p. 369) gives the following generic description. 



Filaments unbranched, non-motile, enclosed in very delicate or rather thick 

 sheaths, either fixed or associated in slimy masses. The separation of the fila- 

 ments and the presence of a sheath is demonstrated by special methods of stain- 



