Hormones and hormone precursors 



be resolved into two zones of activity when chromatographed in n-butanol/ 

 ammonia. These zones appear to be interconvertible. 



3. A further zone of activity was obtained between the starting line and 

 lAA controls in aqueous fractions of maize seeds. Synthetic 3-indolyl- 

 pyruvic acid (IPyA) was examined to determine whether it could be 

 responsible for this activity, but results showed that it appears to be destroyed 

 under conditions of ammoniacal chromatography and cannot therefore be 

 demonstrated in plant extracts by this technique. From an examination of 

 its effect on root growth, IPyA cannot be identical with the accelerator-a 

 of Bennet-Clark and Kefford. 



ACKNOWLEDGEMENTS 



The authors wish to thank Professor S. C. Harland, F.R.S., and Professor 

 E. R. H. Jones, F.R.S., for facilities for this work in the Departments of 

 Botany and Chemistry, the Agricultural Research Council for grants which 

 hav'e assisted the botanical work, and Mrs. V. Shaw for technical assistance. 

 The work described in this lecture will be reported in greater detail in the 

 Journal of Experimental Botany (cabbage and tomato) and the Biochemical 

 Journal (IPyA). 



We are indebted to Professor H. E. Street for sugsfesting the examination 

 of hormones in excised roots and for providing help and facilities for growing 

 this material. 



REFERENCES 



Bennet-Clark, T. A., and Kefford, N. P. (1953). Chromatography of the growth 



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 Bentley, J. A. (1950). An examination of a method of auxin assay using the growth 



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 Bentley, J. A., Farrar, K.R., Housley, S., Smith, G. F., and Taylor, W. (1956). 



Some chemical and physiological properties of indole-3-pyruvic acid. Biochem. J. 



(in the press). 

 Bentley, J. A., and Housley, S. (1954). Bio-assay of plant growth hormones. 



Physiol. Plant. 7, 405. 

 Bonde, E. K. (1953). Auxins and auxin precursors in acid and nonacidic fractions 



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 MoEwus, F. (1949a). Die Wirkung von Wuchs- und Hemmstoffen auf die Kresse- 



wurzel. Biol. Zbl- 68, 58. 

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Biol. Zbl. 68, 118. 

 Street, H. E. (1954). Growing roots without plants. Discovery, 15, 7. 

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764. 

 Stowe, B. B., and Thimann, K. V. (1954). The paper chromatography of indole 



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51 



