PLATE I 



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V # 



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3 





1. The bacteria grow in the soil, in the form of zooglea-like masses, upon the 

 colloidal material surrounding the inorganic soil particles, as shown by the 

 direct microscopic method, X 1200 (from Winogradsky) . 



2. Zooglea-like mass of bacteria in soil, as shown by the direct microscopic 

 method, X 1200 (from Winogradsky). 



3. Large cells of bacteria in Texas sandy soil (Azotobacter?), as shown by 

 direct microscopic examination, X 1200 (from Winogradsky). 



4. The distribution of organic matter and bacteria in the soil (Russian 

 tshernoziem) (after Winogradsky). 



