Metabolism and mode of action 



General . 

 meristem 



Roof cap 



Proepidermis p/o'^ascu/ar \ Procorfex\ Prbfoxy/em 

 ■J.Q _ Profophloem Pith 



OS 



0-6 



0-V- 



>3 



S 0-8 



i 0-6 



to 



S 0-2 



v> 

 O 



§ 0-8 



Intact seedling 



__j \ \ \ 



Excised tip 



Control 



J \ I 



0-6 



0-V- 



0-2 



Sections 



XJ \ \ L 



\s^10-'V[ 

 10'^W 

 Control 



_L 



J \ L 



J I 



Control 



^lAA 



01 5 9 13 17 21 25 29 



Distance from tip in 100 p. 



Pro to xy I em 



Figure 13. The effect of lAA pretreatment on the peroxidase activity of successive 200 /< sections of 

 Vicia roots. The lAA was applied to the roots either as the intact seedling {upper graph) , as excised roots 

 {middle graph) or as cut sections {lower graph). The figures at the right refer to the middle graph. 

 They indicate relative peroxidase activity of sections cut at each of the 7 regions of the root shown by the 

 numbers at the upper left. The darker the colouring, the greater is the peroxidase activity. Section 1 

 has only root cap ; section 2 has root cap surrounding the meristem : the successive sections show root cap, 

 cortex, and vascular tissues. 



230 



