174 



P. E. Pilet 



the criterion used, (1) auxin concentration is greater in the meristem 

 than in the root tip, and (2) auxin destruction has a higher value 

 for the tissues of the root tip than for those of the meristem. 



BIOCHROMATOGRAPHIC ANALYSES 



The study of the active factors has been undertaken on the acid 

 fractions of free auxins extracted by peroxide-free ether (8) . For the 

 two types of tissues, the biological measurements (21) were obtained 

 by two different tests: sections of Lens root (R) and fragments of 

 Leyis stem (T) (25). It seemed best to use equivalent material and, 

 thus, the roots utilized for the measurements (the 5 mm. root tips 

 from the 18 mm. roots) were identical to those which were used to 

 prepare the extracts. Examination of the resulting histograms (Fig- 

 ure 6) clearly shows the existence of lAA in a concentration which 

 produces an inhibition of the R test and a stimulation of the T test. 

 Further, the level of lAA is, according to the previous results, greater 

 in the meristem than in the root tip. Additionally, it shows the pres- 

 ence of two factors already described (2, 3, 9, 21) and discussed (1) 

 elsewhere: an inhibitor and an accelerator (probably an artifact) (7). 



120 



80 



40 



I AA 



^ ^X^^-B^-^ 



1^=°^ : 



li- -40 "— 

 O 



S^ 40 



T TEST 



L "T TEST 



OLD CELLS 



-40 



-80 



^ 



^ 



^^J~Lp 



L R TEST 



I AA 



ftp 



YOUNG CELLS 



'''''' I I ' I I I I I I I I I I I I I I I I I I I I I . I , I I I I 



° 0-5 10 0.5 I 



Rf 



Fig. 6. Histograms [biochromatograms: root (R) and stem (T) tests] for two types 

 of fragments. 



