GENERAL SYSTEMATIC BACTERIOLOGY 349 



ing. The contents of the filaments become segmented, forming round or ovoid 

 gonidia, which escape from the sheath and develop into filaments. Gonidia non- 

 motile. 



In this he is followed by Allen J. Smith (1902, p. 272). Erwin F. 

 Smith (1905) rejects the name as a generic designation. 



Petruschky (1913, p. 270) includes this as one of the genera of the 

 trichobacteria which never shows branching, is never wavy, with 

 stiff filaments in which stages of division are to be recognized with 

 difEcultJ^ 



ElHs (1907, p. 515) uses the L. ochracea as the type of the genus, 

 defining the genus as consisting of organisms with sharply defined 

 stiff membranes. Following are some of the principal characteristics 

 of the organism. Usually associated with Gallionella ferruginea, 

 over which it preponderates to the extent of about 20 to 1. Organism 

 consists of a number of straight filaments free at both ends. Ends 

 often unsjonmetrical. Membrane very sharply contoured, internally 

 as well as externally. Breadth varies from 1| to 2/i, but when covered 

 with ferric hj^droxide often reaches 3^ and more. Length reaches up 

 to 200;Li and possibly more. Formation of conidia takes place bj^ means 

 of a process of budding, constriction taking place as soon as the requi- 

 site length has been obtained. Sometimes the constriction is prolonged 

 so that a number of quill-like structures are seen protruding from the 

 organism. Eventually these also are abstricted and elongate to form 

 new threads. The conidia are oval in shape and measure about l/z 

 in breadth and about Ijn in length. Each has a single membrane. 

 Multiplication also takes place by cell-division. At various unequal 

 distances along both sides of the membranes, small nodules are formed. 

 Each nodule divides into two, the split taking place between the two 

 daughter-nodules. As the pairs of nodules are not exactly opposite 

 the pairs on the other side of the membrane the daughter-cells are not 

 symmetrical at the ends. The cell- and conidium-contents are per- 

 fectly homogeneous. In no stage of its life-history is any motility 

 observ^able. 



Jordan (1908) includes in the genus those trichobacteria with un- 

 branched filaments. 



Schwers (1908) used the name Leptothrix ochracea. 



West (1904, p. 334) lists L. ochracea as a synonjnn of Lyngbya och- 

 racea among the Myxophyceae. 



Orla-Jensen (1909, p. 331) includes Leptothrix as the fifth genus of 

 his Trichobacteriaceae in which the cells are unattached, not spiral, 



