Lecture 4 



— 99 — Movement and Distribution 



idea has been developed and the term "activated dif- 

 fusion", apphed to movement of solutes in the phloem 

 system. No direct experimental evidence is available 

 for this hypothesis, which meets some theoretical diffi- 

 culties. Indeed, one might well call attention to the 

 fact that there is no approach to general agreement 



Table 2. Oaln of phoipliorui in tectwnt of jeranivm after abiorption period of 6 hourt. 

 {Calculated at POf from radioactivity.) 



* 1 gamma is equal to .001 milligram. 



Textfigure 30. — Phosphate transport in garden geranium. 

 {See also figure 29). (From Stout and Hoagland, 1939). 



by investigators on any mechanistic explanation of 

 movement of solutes in the phloem. 



I have now presented the results of various types 

 of experiments bearing on the question of upward 

 movement of inorganic solutes. It would be gratify- 

 ing if these and other experiments could lead to a 

 completed picture of these aspects of movement of 

 solutes in plants. Unfortunately, our knowledge has 



