DONALD G. CROSBY 



Union Carbide Chemicals Company 



A. J. VLITOSi 



Boyce Thompson Institute 



New Auxins From 'Maryland Mammoth.' 



Tobacco 



Indole derivatives have held a position of pre-eminence in the field 

 of natural auxins for many years. In fact, they have been regarded 

 by many workers to constitute probably the only group of growth 

 regulators to occur in nature. At the present time, the only two in- 

 dole derivatives possessing pronounced growth-promoting activity to 

 have been isolated from plants are indole-3-acetic acid (lAA) and in- 

 dole-3-acetonitrile (IAN), although there is evidence for the occurrence 

 of a variety of other 3-substittited indoles. 



Paper chromatography has emerged as a versatile method for the 

 resolution of the complex chemical mixtures occurring in plant ex- 

 tracts. With the development of sensitive and rapid techniques for 

 the bioassay of growth substances, this has resulted in our ability 

 to measure "hormone profiles" which present an indication of 

 the extent to which different growth-regulating substances occur 

 in extracts of plant material. Considerable effort has been made to 

 ascribe the areas of growth stimulation of such profiles to lAA, IAN, 

 and the other indoles. 



An increasing number of hormone profiles has been determined 

 for different plant species growing under a wide variety of conditions. 

 However, continued refinement of technique has caused their inter- 

 pretation in terms of the known indolic growth substances to become 

 increasingly difficult. Many investigations have failed to show the 

 presence of the known indoles, while others have revealed growth 

 activity in chromatogram areas which do not correspond to classical 

 growth substances (1). The work described in this paper, which started 

 with an investigation of one such case, has led to the discovery of two 



^ Subsequently: Central Agricultural Research Station, Caroni, Ltd., and Ste. 

 Madeline Sugar Company, Ltd., Waterloo Estate, Carapichaima, Trinidad, W.I. 



[57] 



