10 OUTLINES OF BACTERIOLOGY 



5. Leptothrix. Threads with very sharply defined stiff membranes 

 (Fig. 19). 



FIG. IS. Phragmidiothrix. (After Migula.) 



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

 hairpin twisted on itself (Fig. 20). 



FIG. 19. Leptothrix. FIG. 20. Gallionella. Fie. 21. Spirophylluni. 



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

 band (Fig. 21). 



