322 BACTERIOLOGY. 



Genus III. Phragmidiotlirix. Threads jointless ; suc- 

 cessive subdivision of cells is continuous ; cells 

 sulphurless ; habitat water. 



Genus IV. Leptothrix. Threads articulated or unar- 

 ticulated ; successive subdivisions of cells not 

 continuous ; cells sulphurless. 



Genus I. Crenothrix. 



SPECIES. 



UNASSOCIATED WITH DISEASE : 



Crenothrix Kiihniana . . Simple saprophyte. 



Crenothrix Kiihniana, Rabenhorst. Cocci, 

 rods, and thread-forms. The cocci are globular, 

 i 6 p, in diam. The threads are colourless, 1^5 

 5 p. thick, and club-shaped at the extremity, reach- 

 ing a diam. of 6 9 /*. The threads form colonies 

 with a brick-red, olive-green, or dark-brown to 

 brown-black coloration caused by impregnation 

 with oxide of iron. The threads are distinctly ar- 

 ticulated, and ensheathed. The segments are set 

 free when the sheath bursts, and develop into new 

 threads. In other cases the segments remain en- 

 closed, and subdivide into discs, which, by vertical 

 fission, break up into globular forms (cocci). These 

 again develop into new threads, either within the 

 sheath eventually penetrating it, or after they are 

 set free (Fig. 125). 



The micro-organism appears in little whitish or 

 brownish tufts in wells and drain-pipes, and it not 

 only renders drinking-water foul, but may stop up 

 the narrower pipes. 



