\ ^' /-■ ^ 



Fig. 4. a. Nitrosomonas europaea, Alexander strain. Polar monotrichou.s 

 flagellation. Note the very short wavelength. 



b. Nitrosomonas (?) sp., Alexander strain. Polar monotrichous flagellation. 

 Note the relatively long wavelength. This organism is not autotrophic and 

 probably not a Nitrosomonas sp. 



c, d. N. europaea (?), ATCC 12248. The organisms shown in c and d 

 are typical examples of the organisms in the culture studied. Since the 

 culture was not strictly autotrophic the organisms shown are probably not 

 Nitrosomonas. 



21 



