WHEAT SEEDLING AND NUTRIENT SOLUTION 



895 



14 days the ^^P content of the "inactive" roots amounts to about ^j^^ 

 of the 32p content of the "active" roots. This result indicates a fairly 

 slow passage of the ^^P from the "active" into the "inactive" roots. The 

 activity values can clearly not become equal even after a very long time, 

 as the "inactive" roo1s are placed in an inactive solution A\hich is daily 

 replaced by another inactive solution. 



Percentage of ^^P Present in the Roots 



14 Days after Addition of Labelled 



Phosphate to the Inner Solution 



Plant 



Active roots 



Inactive roots 



The dry weight and the total phosphorus content of the active and the 

 inactive roots do not much differ, while the ^^P content of the "inactive" 

 roots makes out only Yso of the ^^P content of the "active" roots. 



The percentage of labelled phosphate migrating from the active 

 solution through the plant into the inactive solution in the course of 

 48 hours is seen in Table 4. Six weeks old seedlings were used, the active 

 phosphate being added 14 days before the experiment was carried out. 



Table 4. — Percentage of 

 Active Phcsphate Migrat- 

 ing IN THE Course of 1 Day 

 from THE Active into the 

 Inactive Solution 



Plant 



Percentage 

 migrated 



