Lecture 4 



— 91 



Movement and Distribution 



place near the region of greatest metabolic activity 

 at the apex, which in the excised root is also the 

 region of most active salt accumulation. 



12 3 4 5 



DISTANCE IN CM. FROM APEX 



Textfigure 27. — Distribution of 

 absorbed rubidium in excised barley 

 roots with relation to distance from 

 root apex, at two different time 

 periods. (From Steward, Prevot, and 

 Harrison, 1942, redrawn). 



Another view advanced by Crafts and Broyer 

 (1938), although based, as far as anatomical factors 

 are concerned, on an earlier concept of Priestley, is 

 that salt may be carried by protoplasmic connections 

 from the well aerated cortex of the root into the less 

 aerated central cylinder, where decreased metabolic 

 activity causes loss of salt to the vessels of the xylem 

 system. Even so, the net result would represent 



