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Figure 5. Autoradiograph of leaves of three separate bean plants receiving radio- 

 iron while they were becoming chlorotic as a result of the pH and phosphorus con- 

 centration of the nutrient media. Left: Plant grown at pH 7.0 and 0.00 1 M P. The 

 leaves were chlorotic throughout. Middle: Plant grown at pH 7.0 and 0.0001 M P. The 

 leaves had green veins with chlorotic mesophyll. Right: Plant grown at pH 4.0 and 

 0.000 1 M P. The leaves were healthy and green throughout. 



