no 



MORPHOLOGY AND CULTURE OF MICROORGANISMS 



formed by the germination of conidia while they are still in the parent 

 threads. The large threads, b, c, d, and e, show more details. In e a 

 uniform thread is shown with the separate vegetative cells; in d these 

 have broken up into conidia. The flaring form of the threads are shown 

 in c and b where the conidia are formed in large numbers. These 

 figures also show the sheath which is indicated by the double line in c 

 and by the extension of the lines -beyond the cell contents. 



Chlamydothrix ochracea Migula is composed of filamentous, cylindri- 

 cal, colorless threads. The sheath is at first thin and colorless but later 

 becomes thicker, yellow or brown due to encrustations of iron oxide. 

 Multiplication is by means of cell division and swarm cells. These 

 latter may sometimes germinate in the sheath, giving the appearance of 

 branching (Fig. 89, c). 



FIG. 89. A, Spirophyllum ferrugineum; B, Gallionella ferruginea; C, Leptothrix 

 ochracea. X about 1080. (After Harder.) 



Gallionella ferruginea Ehr., in its typical form, consists of spiral 

 threads coiled together in double or quadruple coils like a rope. The 

 threads are cylindrical but comparatively thin. Individual cells have 

 not been distinguished in the threads (Fig. 89, B}. 



Spirophyllum ferrugineum Ellis is very similar to and associated 

 with the above. It differs principally in the shape of the threads 

 which are flat or ribbon-like. The threads are always twisted but may 

 occur singly ^or be coiled into ropes (Fig. 89, A). 



