10 OUTLINES OF BACTERIOLOGY 



5. Leptothrix. Threads with very sharply defined stiff membranes 

 (Fig. 19). 



Fia. IS.— Phragmidiothrix. (Aftex- Migula.) 



6. Gallionella. In this genus the thread has the appearance of a 

 hairpin twisted on.itself (Fig. 20). 



Fig. 19.— Leptothrix. Fro. 20.— Gallionella. Fic. 21.— Spiropliyllum. 



7. Spirophyllum. The organism consists of a spirally twisted ilat 

 band (Fig. 21). 



