CLASSIFICATION OF THE BACTERIA 31 



the surface of cider or wine in the process of vinegar 

 manufacture. 



FIG. 7. ACETOBACTER. A. Normal cells. B. Involution forms. 



Nitrosomonas. 1 Bacteria belonging to this genus have 

 cells either rod-shaped or spherical, motile or nonmotile. 

 These organisms are soil forms securing their growth 

 energy by the oxidation of ammonia to nitrous acid. They 

 do not require organic compounds for growth. They are 



V 



a 



FIG. 8. NITBOSOMONAS. .A. FIG. 9. NITBOBACTEB. 



Non-motile spherical type. 

 B. Motile, rod-shaped type. 



responsible in the soil for initiating the changes later to be 

 discussed under the heading of * * nitrification. ' ' 



Nitrobacter. The organisms belonging to this genus are 

 rod-shaped, nonmotile, and do not require the presence of 

 organic matter for growth. They are commonly present 

 in the soil and secure the energy for growth by the oxida- 

 tion of nitrites to nitrates. They complete the process of 



i This genus includes the organisms sometimes described as 

 \itrosococcu8. 



