T. C. Broyer 



199 



medium 



r 



3< 



4 

 5 



binding 



V 



6 inward 



7 diffusion <. 

 outward 



8 binding 



r 



1 efflux < i 



> 



cortex 



endo- ' 



dermis stele wood- 

 tissue 



b J. 



i = 



I b 



-r 



1 



eel with 

 vacuole 



„.JT. 



V 



JL 



.<?. 



'< '■ i >. ''A 

 ■ '///'/<. 

 yy-A ■■■ 



H 



if 



-y" ; 'v < 



■■■//■y / '///4 



m 



* ■ ■ / 



■■;■'■ 



W6 



=fr polar.active transfer 

 > passive movement. diffusion 



Figure 6. Scheme illustrating the theoretical considerations con- 

 cerning lateral transport through living root tissues.— Wiersum (92) 



