A. J. HAAGEN-SMIT 



II 



A — 



-C COH 

 OH /OH 

 COOH 



Q 



6 COH 



Y 







-A 



c 

 



AUXIN- a AUXIN-a LACTONE LUMI AUXONE 



Figure 3. Conversion of auxin-a to lumiauxone. 



coleoptile cylinder test, and especially the pea test, does not require 

 the transportability characteristic of substances which are active in the 

 Avena test (57). When these tests are used in the isolation, substances 

 will be found which do not possess all the qualities necessary for a true 

 auxin, but which show the primary growth activity. Using the pea test 

 as a guide, indican could have been isolated from urine. In plants 

 substances like phenylacetic acid, occurring free and esterified in pepper- 

 mint oil and in oil of neroli, would have been recognized as growth 

 substances. The same is true for m-cinnamic acid, which occurs free 

 and esterified in numerous plants, the most abundant sources being 

 Peru and Tolu balsam. These substances could well be included in the 

 list of naturally occurring growth substances since they show the primary 

 growth activity. Their presence in the plant could hardly fail to cause 

 some response from the neighboring cells. In some cases where they occur 

 in oil glands and resin ducts, we could speculate that they played a role 

 in the cell proliferation during the formation of the glands. 



As a result of the chemical investigations several substances occurring 

 in plants and fulfilling the requirements for activity in the Avena test 

 have been identified. The next question, therefore, is: which auxin 



c-c- 



9 A 9 



c-c c-c 



I I I I 



C=f=C-j-C 

 AUXIN-a ' 



C- 



-c- 



•C 

 -C 



■C— C 



CHa 



CH3 CH2 

 \ / \ 

 CH3-CH2CH-CH CH-CH-CHj-CHa 



COOH COOH 

 AUXIN-tf aUTARIGACiO 



Figure 4. Formulae for auxin-a and auxin-a glutaric acid. 



