Natural auxins 



:^ zoo 



Si 



"I 



I 



100 



50 



Acid fraction 

 lAA IAN 



\ 



^ 250 

 % 



-^^ ZOO 



^ 150 



Hon -acid fraction 



% 



100 



50 



Figure _. uiuiugitui ujjuj uj 

 chromalograms of acid and non- 

 acid fractions from a solution con- 

 taining 1 jig lAA and 1 /(g IAN. 



Experiments with maize 



A preliminary experiment was carried out with maize, variety 'White 

 Horse Tooth.' Samples of 200 seeds were extracted and assayed at intervals 

 of 12 hours during 60 hours germination at 25°C in the dark. The results are 

 presented in Figure 3. It can be seen that most of the auxin extracted by this 



<^<?hrs 







ZVhrs 



(f(9>irs 



1-0 



2 Rf~ 



Figures. 'White Horse Tooth' maize. Preliminary experiment. 



procedure is in strip 2 of the chromatogram and it has been confirmed that 

 this is indolylacetic acid by colour reactions and by measurements of 7?^ in 

 different solvents. It seems that the amount of I AA extracted by this pro- 

 cedure increases rapidly in the early stages ofgermination, reaches a maximum 

 after about 24 hours, and then begins to decrease. 



34 



