PLATE IX 



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47 





47. Life cycle of Azotobacter chroococcum: a, formation of symplasm by 

 regenerative bodies on potato, in 9 days; b, regenerative units starting to grow, 

 on beef gelatin, in 4 weeks; c, regenerative bodies growing from symplasm, on 

 beef agar, in 4 weeks; d, formation of new cells by agglomeration of regenerative 

 units on mannite soil extract, in 4 days; X 600 (from Lohnis and Smith). 



48. Influence of composition of medium upon the morphology of Bact. 

 ■pneumoniae: A, on beef agar, 1 day at 37°C; B, on egg agar, 1 day at 19°C; C, on 

 starch agar, 1 day at 19°C; X 660 (from Scales). 



49. Some typical soil bacteria, as shown by the India Ink method" A, short 

 non-spore forming rods (bacteria); B, long, non-spore forming rods (bacteria); 

 C, spore-forming rods (bacilli) (from Kursteiner). 



