512 MICRO-ORGANISMS IN WATER 



Arthrosporus 



Single segments 



Common sheath sur- 

 roumling tlie sepa- 

 rate spores 



FIG. 24. CKENOTHRIX KUHKIANA 

 Magnified 600 times. (After Zopf.) 



CBENOTHKIX KUHNIANA (Crenothrix polyspora, Cohn) 



Authority. First discovered by Kiihn and investigated by Cohn, and later 

 by Zopf. 



"Where Found. Found very frequently in both stagnant and running waters 

 containing organic matter or iron. It occurs sometimes in such numbers in 

 water-pipes that the water is unusable. It produces a thick vegetative mass in 

 water, either brown or greenish in colour, which is due to the oxide of iron ; 

 it imparts a reddish tint to the liquid, also a disagreeable odour and a bad 

 taste, and is capable by its presence in reservoirs or conduits of deteriorating 

 large quantities of water at a time. 



Microscopic Appearance. It exhibits, according to Zopf, both cocci and rod 

 forms, as well as filaments. The cocci are from 1 to 6 p in diameter ; they become 

 invested with a gelatinous material and multiply by division, and in this 

 manner give rise to irregularly shaped zooglrea masses, sometimes of enormous 

 size. When cultivated in marsh- water the cocci grow into rods, which by con- 

 tinuous division form filaments which radiate out in all directions from the 

 zooglcea. When this growth has attained a certain age a sheath is produced, 

 which often contains ferric hydrate. Within the filamentous sheath the rods, 

 by transverse division, give rise to isodiametric pieces, which become rounded 

 and cocci-shaped. By this continuous process of division which takes place 

 inside the sheath, such a pressure is exerted against its top end that it is forced 

 open, and the cocci and rods escape. Sometimes the cocci and rods develop 

 within the sheath into rods and threads, and growing through the wall of the 

 sheath produce a number of threads, which make the original filament present 

 the appearance of a paint-brush. 



