d 



b • 



Jk V 



J^ 



f 



Fig. 68. a. A typical organism as seen in broth culture. Polar niono- 

 trichous flagella. 



b. This picture is from a mixed culture in a very dilute medium. The 

 curved soma is very characteristic under such conditions. 



c. The organism illustrated shows a short branch. Other and more 

 branched individuals were also observed in some media but most of these 

 were nonflagellated. 



d. e. The two organisms illustrated show the spined soma and the charac- 

 teristic polar flagellum. Both spines and flagella were only observed in the 

 mixed cultures obtained by adding small amounts of nutrients, such as yeast 

 extract, to the river water. 



f. The tvpical spined but nonflagellated form seen in river water. The 

 soma was typically curved, often in a semicircle. The nature and function of 

 the spines has not been determined. 



159 



