Extraction and Measurement Techniques 51 



have been sought for in extracts of plant tissues by Pacheco (1951), 

 von Denffer et al (1952) and many others. 



When a growth substance extracted from plants is chromato- 

 graphed for detection and isolation, the Rf values of substances which 

 might appear in the extract must be determined by previous chroma- 

 tography of the synthetic materials for comparison. In table 1 Rf 

 values of a number of indole compounds and growth regulators are 

 given. 



Yamaki and Nakamura (1952) tried a large number of solvents for 

 chromatographic separation of indoleacetic acid — of which 70% eth- 



TABLE 1 



Rf Values of Some Plant Growth Regulators and Allied Comfounds 

 (Sen and Leopold, 1954) 



* Two spots are obtained. 



