418 A. C. Leopold arid S. L. Lam 



SUMMARY 



The transport of indole-3-acetic, indole-3-«-butyric, and 1-naphtha- 

 leneacetic acid through sunflower stem sections has been examined. 

 Evidence is provided that the transport of each of these auxins is 

 polar in nature. The velocities of transport of indole-3-acetic acid 

 and of 1-naphthaleneacetic acid are closely similar, while a slower 

 apparent rate obtains for indole-3-n-butyric acid. The sensitivities of 

 transport of the three auxins to transport inhibitors were also meas- 

 ured, and no striking differences between the three auxins were 

 found. It is suggested that the three auxins move in the same trans- 

 port system, and the system is not exclusively specific for the com- 

 mon plant growth hormone, indole-3-acetic acid. 



LITERATURE CITED 



1. Fawcett, C. H., Wain, R. L., and Wightman, F. Beta-o\idation of omega- 

 (3-indolyl) alkanecarboxylic acids in plant tissues. Nature. 181: 1387-1389. 

 1958. 



2. Gustafson, F. G. Lack of inhibition of lateral buds by the growth-promoting 

 substance, phenylacetic acid. Plant Physiol. 16: 203-206. 1941. 



3. Keitt, G. W., Jr., and Skoog, F. Effect of some substituted benzoic acids and re- 

 lated compounds on the distribution of callus growth in tobacco stem explants. 

 Plant Physiol. 34: 117-122. 1959. 



4. Leopold, A. C. Auxins and Plant Growth. 354 pp. Lniv. Calif. Press, Berkeley. 

 1955. 



5. Niedergang, E. Chemical modification of polarity and auxin transport in 

 plants. Ph.D. Thesis, Univ. of Wis. 1954. 



6. Niedergang-Kamien, E., and Leopold, A. C. Inhibitors of polar auxin trans- 

 port. Physiol. Plant. 10: 29-38. 1957. 



7. , and Leopold, A. C. The inhibition of transport of indolcacctic acid 



by phenoxyacetic acids. Physiol. Plant. 12: 776-785. 1959. 



8. Thimann, K. V. On an analysis of the activity of two growth-promoting sub- 

 stances on plant tissues. Proc. Kon. Akad. Wet. Amsterdam. 38: 896-912. 1935. 



9. Weij, H. G. van der. Der Mechanismus des W^uchsstofftransportes. Rec. Trav. 

 Bot. \terl. 29: 379-196. 1932. 



10. Went, F. W., and White, R. Experiments on the transport of auxin. Bot. 

 Gaz. 100: 465-484. 1939. 



