78 Lectures on Bacteria. [^ viii. 



coloured accordingly. The often striking accumulations 

 of ochre-coloured slime-masses in springs and small streams 

 which contain iron, the filamentous constituents of which are 

 known by the old name of Leptothrix ochracea, Kiitzing, 

 consist, according to Zopf, of this iron-containing Cladothrix. 



The filaments multiply by the abscision and further growth 

 of portions, which form longer or shorter rods according to 

 their size — a mode also very common among the allied Nos- 

 tocaceae — and also, according to Zopf, by means of spores or 

 ' Cocci,' that is, short rounded cells, which issue from the sheath 

 and develope into filaments. 



The filaments, or single branches of them, instead of retaining 

 the usual tolerably straight form, may become spiral with more 

 or less narrow or open coils, and these spiral forms also may 

 break up transversely into separate pieces. 



Both the longer and the shorter abscised rod-shaped and 

 spiral portions of filaments, and the round spores and Cocci 

 also, not unfrequently become motile, the longer ones 

 creeping or gliding with a slow movement, the short forms 

 displaying an active swarming motion, such as is described on 

 page 7. 



Lastly, the four forms, the filamentous, the rod-like, the spiral, 

 and the coccoid, whether mixed together or separate from one 

 another, may remain united by a jelly into Zoogloeae, which 

 sometimes appear as bodies of considerable size with shrub- 

 like branching. The short forms may again become motile, 

 and swarm out of a Zoogloea ; but they may also develope 

 again into the filamentous form, the typical form from which we 

 set out ; this has certainly not been directly observed in the case 

 of the spiral rods. 



If all these statements are correct, Cladothrix supplies the 

 most complete example of a pleomorphous course of develop- 

 ment. 



No more is known of injurious properties and decomposing 

 power in Cladothrix than in Crenothrix. 



