Metabolism and mode of action 



Water 



lAA 



I A Am 



IAN 



lAMe 



-f- 



W 



Figure 4. Histograms showing the activities in the wheat cylinder test of chromatograms of extracts 

 from solutions treated with wheat tissue. 



The chromatograms. developed in n-butarwljammoniajwater (100 : 3 : 18), were divided into strips 

 corresponding to one-tenth of the solvent flow. 



chromatogram previously noted. The results of the pea tests {Figure 5) show 

 activity only in those regions where lAA, lAAm, or lAMe formed spots 

 visible on the colour chromatograms. 



Solutions treated with pea stem tissue 



Examination of the colour chromatograms obtained from this treatment 

 {Figure 6) showed that, as with wheat tissue, lAA gave rise to a pink area 

 below the acid at R^ 0-2-0-35. The amide, however, behaved quite differently 

 in this instance, giving rise to a well-marked lAA spot, whereas the nitrile 

 gave no lAA and only a small amount of ICA. lAMe gave a distinct blue 

 spot of lAA and a pink-staining degradation product running at Rf 0-2-0-3. 



The histograms showing the results obtained in the coleoptile elongation 

 test {Figure 7) indicate the presence of a small amount of lAA in the water 

 extract. This loss of lAA from pea stem tissue is substantiated by the fact 



238 



