be unsatisfactory for flagellar studies. Two strains each of Azoto- 

 hacter agilis and A. vinckindii were received from Dr. Wilson. 

 The two strains of A. agilis showed good motihty, while one strain 

 of A. vinekindii was motile but the other not. Azotobacter in- 

 dicum 8597 was received from the National Collection of Industrial 

 Bacteria in England and also A. nmcrocijtogenes 8700. A. indicum 

 9037, 9038, 9039, and 9540 were received from ATCC. Of the 

 indicum strains onlv ATCC 9038 and 9039 were flagellated. (See 

 Fig. 27.) 



Flagellar Characteristics 



A. agilis was actively motile and showed good flagellation. 

 The flagella were peritrichously arranged and either normal, coiled, 

 or both coiled and normal on the same individual, A. vinelandii, 

 strain Wilson O, was actively motile with peritrichously arranged 

 flagella. Only normal flagella were observed. The four strains of 

 A. chroococcum which were motile showed peritrichously arranged 

 flagella. The best stains were obtained from mannitol agar slants 

 without peptone. When the four strains were stained from sus- 

 pensions made alkaline with dibasic potassium phosphate, prior to 

 the addition of formalin, all showed normal flagella only. However, 

 when stained from suspensions made shghtly acid with monobasic 

 potassium phosphate, strains E-2 and E-3 again showed only normal 

 flagella while strains E-7 and E-8 showed curly flagella only. This 

 change of flagellar curvature by change of pH is not common and it 

 is curious to find this difterence in strains of A. chroococcum which, 

 superficially at least, appear to be alike. A. indicum, ATCC strains 

 9038 and 9039, were slightly motile and some individuals showed 

 peritrichous flagellation. The flagella showed a strong polar tend- 

 ency, often appearing as a tuft of polar flagella. All the observed 

 flagella of these strains had a short wavelength comparable to the 

 curly type of A. chroococcum. Change of pH did not affect the 

 wavelength of these flagella. 



A. macrocijtogenes, NCIB 8700, showed polar flagellation. The 

 flagella were most frequently single, but occasionally multiple, and 

 this culture must be regarded as polar multitrichous. This or- 

 ganism should, therefore, not be classified in the genus Azoto- 

 bacter. If it is a nonsymbiotic nitrogen fixing organism it could 

 be classified in the genus Azofomonas. 



63 



