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THE MICROBIOLOGY OF THE ATMOSPHERE 



Spores brought down by thunder rain terminating 7-day dry 

 spell, Rothamsted ....... 



Mukiple-infection transformation : percentages to infections . 



'Probable flight range' based on Rombakis's modification of 

 Schmidt's theory ........ 



Effect of gradient on distance of horizon of infection . 



Pollen trapped on lightships in Gulf of Bothnia . 



Stakman & Hamilton's (1939) data on long-distance dissemina- 

 tion of Puccinia graminis ...... 



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