Natural auxins 



these experiments show that an active substance which runs at Rf 0-4-0-5 in 

 wopropanol/ammonia Uberates a further active substance which runs at the 

 same R^ as IAN on further chromatography. The re-chromatography 

 involves heating to about 60°C and further treatment with weak alkali. 



Response to lAA 

 (mgAJ 



0-2 



O-f 



OB 



0-3 



7-0 



'f 



Figure 3{b). Active area from chromatogram of aqueous fraction of approximately 13 g excised roots 

 re-chromatographed in ammoniacal isopropanol. 



The experiment was repeated to examine the chromatogram with colour 

 sprays. No colour reactions could be obtained in the IAN region with 

 HNO2/HNO3, FeCl3/HC104, or with MeAB. There is thus no evidence, 

 apart from R^ value, that the activity near the solvent front is due to IAN. 



78 



16 



^ 

 -¥ 



■^ 7f 



I 



72 - 



Response fo lAA 

 (mg/l.: 



0-2 



04 



0-e 



70 



Figure 4. Aqueous fraction of approximately 13 g excised tomato roots developed in ammoniacal 

 n-butanol. 



On spraying with bromo-cresol green, a yellow area in the zone of activity 

 corresponding to the lAA region was obtained, suggesting that the second 

 active substance near the solvent front comes from an acidic precursor. 



Because of the poor separation in ijopropanol/ammonia, the experiment 

 was repeated using n-butanol/ammonia {Figure 4). Again separation was 

 poor, so the chromatogram was eluted and re-developed, when a good 



46 



