OriginaUy published Arkiv For Botanik, 33 A, (1945). 



92. INTERACTION BETWEEN THE PHOSPHORUS 

 ATOMS OF THE WHEAT SEEDLING AND THE NUTRIENT 



SOLUTION 



G. Hevesy 



From the Botanical Institute of the University of Stockholm 



The animal organism is bound to take up appreciable amounts of mineral 

 constituents with its daily food; correspondingly, appreciable amounts of 

 such constituents are daily excreted by the organism. In contradistinction 

 to the animal body, the uptake of mineral constituents by the plant is not 

 necessarily followed by a loss of such constituents. The application of 

 isotopic indicators, however, has shown that ions taken up by the plant 

 can be removed under the action of other ions present in the soil or in 

 the nutrient solution. At an early date^^\ it was shown that minute 

 amounts of lead labelled by the admixture of the lead isotope thorium B 

 taken up by the roots of Vicia faba to a large extent can be removed by 

 an excess of non-labelled lead added to the nutrient solution. Most other 

 ions were found, as shown in Table 1, to be much less effective in remov- 

 ing the labelled lead ions. 



The discovery of artificially radioactive isotopes made it possible to 

 study the removal of essential constituents from the plant organism as, 



Table 1. — Removal of Minute Amottnts of Labelled 

 Lead from the Roots of Vicia faba when Immersed 



IN A 10~2 N SoLtrxiON OF DIFFERENT SaLTS 



Solution used 



Per cent of tlie lead 



initially present in the 



root, which remained after 



treatment 



Lead nitrate (inactive) 



Cupric nitrate 



Cadmium nitrate 



Zinc nitrate 



Chromium nitrate .... 



Barium nitrate 



Sodium nitrate 



5 

 3 



34 

 38 

 43 



74 

 76 



<i)G. Hevesy, Biochem. J. 17, 439, 1923. 



