Investigation of natural auxins and growth inhibitors 



as above and assayed with oat coleoptile segments. The results shown in 

 Figure 2 were obtained. 



It is clear from Figure 2 that for bean seed tissue methanol seems to be a 

 better solvent than ethanol, since the peaks of growth, especially the one in the 

 indole-3-acetonitrile (IAN) region, are higher. It seems also that ethyl 

 acetate extracts a still higher amount of auxins, although the peak in the IAN 

 region is less marked ; in addition, ethyl acetate appears to extract a substance 

 having a /?^ higher than lAA but lower than IAN. 



To find out whether ethyl acetate was a better solvent than methanol, the 

 following experiment was performed. Lyophilized immature bean seeds were 

 first extracted for one and a half hours with absolute methanol at 0°C, then 

 with anhydrous ethyl acetate for another one and a half hours, also at 0°C. 



Figure 2. Histograms made under conditions similar to those of Figure 1 . except that the three extracts are 

 of 15 mg {dry weight) each of lyophilized bean seeds {var. Dwarf Shell Red Kidney), dissected out of the 

 immature pods about one week after /lowering. The extractions were made at C during 5 hours with 

 absolute methanol, absolute ethanol. and ethyl acetate respectively. The material extracted with ethyl acetate 

 ivas washed with absolute ethanol and the two extracts were combined. 



The two extracts were chromatographed separately in our new /j-obutanol 

 (80)+methanol (5) +H2O (15) (v/v) solvent which has been substituted for 

 the previous one for reasons which will be discussed below. The results 

 obtained when the chromatograms were assayed with oat coleoptile segments 

 (see Figure 3) show clearly that after the methanol extraction, which yields 

 large quantities of auxins, ethyl acetate extracts only very small amounts. 

 In addition, no indication of auxins different from those extracted with meth- 

 anol can be seen on the diagram corresponding to ethyl acetate, since the small 

 peaks obtained correspond in general with those of the other diagram. It may 

 be noted in passing that the chromatographic solvent used in the present 

 instance reveals the existence of substances which were not found with the 

 fj^opropanol-ammonia solvent (compare with Figure 2). These substances 

 either are not separated or are transformed into other substances during 



