464 



HIGHER FISSION-FUNGI. 



thread (where it is fixed) is wider and stronger. Also the 

 height of the individual cells varies from one-half to four 

 times the thickness, square forms being most common 

 (Fig. 27, a and e). 



Sometimes the terminal cell of a thread is large and 

 oval (like a spore), in which case a deeper cell grows out 

 laterally. 



Propagation occurs through a peculiar breaking up of 

 the cells at the end of a thread into fragments. Cohn dis- 

 tinguishes two types: (a) Formation of microgonidia: 

 several individual cells in the thread break up by longi- 

 tudinal and transverse division into not less than 16 very 



Fig. 27. — Crenothrix polyspora. 



small plasma spheres, which later are freed from the some- 

 what swollen ends of the threads and grow out into new 

 threads (Fig. 27, d). (b) Formation of macrogonidia: 

 several of the cells in a thread near its end are transformed 

 by infrequent division into larger, roundish, oval or diplo- 

 cocci-like forms, which grow out into new threads (Fig. 

 27, b). One type passes over into the other. 



The plant is widely distributed (especially) in waters 

 containing iron (also in tap-water). A pure culture in the 

 bacteriologic sense has not been obtained. According to 

 Rossler, cultivation readily succeeds in well-water in which 

 pieces of brick are boiled and to which is added ' ' some ' ' 

 ferrous sulphate. (Compare Ferd. Cohn, Beitrage zur 



