CREXOTHRIX KUHNIANA. 



437 



irregular masses of zooglsea of very various sizes are 

 formed ; these masses often form very large clumps, and 

 may have a red, green, or brownish-black colour, from 

 the deposit in them of oxide of iron. When cultivated 

 in marsh water 

 the cocci grow 

 to form rods, 

 which again 

 form threads by 

 continued fis- 

 sion, these 

 threads project- 

 ing from the 

 surface of the 

 zooglaea mass in 

 all directions. 

 At a certain 

 stage they show 

 u distinct forma- 

 tion of sheaths, 

 and the oxide 

 of iron is often 

 deposited in 

 these sheaths. 

 Within the 

 sheaths the rods 

 continue to di- 

 vide transverse- 

 ly, and isodia- 

 metric pieces 

 are formed which 

 become rounded 

 at the ends and 

 then represent 

 the cocci, which 

 are, as a rule, 

 fairly large (ma- 

 crococci). In the broad threads, however, the transverse 

 division ma} T go still further, so that the isodia metric 

 portions are split up into quite small cylindrical 



Fig. 135. Crenothrix Kiihniana X 600. 



Thread forms with cylindrical discs and 

 (a) cocci. (After Zopf.) 



