276 M. K. Bach and J. Fellig 



material was extracted by homogenizing the stems twice in 70 per cent 

 aqueous ethanol in a Lourdes Multi-Mixer. The extracts were freed 

 from fibers by centrifugation, concentrated in vacuo, adjusted to a 

 small volume, and aliquots plated on copper planchets according to 

 the method of Bergmann et al. (5). Extraction of the radioactive ma- 

 terial was better than 99 per cent by this method. The samples were 

 counted under a thin-window Geiger counter to a reliability of at 

 least 5 per cent and the results corrected for the usual factors and 

 expressed as infinitely thick samples. For the analysis of the radio- 

 active products formed from 2,4-D, the solvent of Jaworski et al. (18) 

 and Whatman No. 1 paper were used. The radioactivity of the 1 -inch- 

 wide chromatogram strips was detected with the aid of a Micromil 

 window Geiger counter tube on a Nuclear Chicago Corp. Actigraph 

 II. All scans were counted with a full scale reading of 1,000 counts per 

 min. or less, a resolution time of 50 sec, a slit of Vs inch, and a scan- 

 ning speed of 3 to 6 inches per hr. The distribution of the radio- 

 activity in the various regions of the chromatograms was calculated 

 from the average of three determinations of their areas with a plani- 

 meter. Preliminary experiments had shown a linear correlation be- 

 tween radioactivity and area without need of corrections for the self 

 absorption of the paper. 



The same scanning instrument was used for the determination 

 of the distribution of radioactivity in the bean stems after various 

 conditions and periods of exposure to l-Ci^-2,4-D. Sections 10 mm. 

 long were exposed to undiluted radioactive 2,4-D applied at their 

 apical ends. They were harvested and washed as described, and then 

 mounted on glass slides with rubber cement. They were frozen by 

 immersion in liquid nitrogen and dried in vacuo. The dried stems, 

 which resembled hollow cylinders, were slit open longitudinally and 

 mounted side by side on 34-inch-wide strips of "Scotch" brand cello- 

 phane tape, making sure that all the apical ends were perfectly aligned. 

 Marker spots were prepared by cutting 1/16-inch-wide strips of filter 

 paper impregnated with a C^-^-containing ink. Markers ^\ere mounted 

 at known distances ahead of the apical end of the stems and after 

 the basal end. The rest of the tape was covered with filter paper, and 

 the assembly pressed briefly between two metal plates. The strips 

 were then passed through the Actigraph at a rate of % inch per hr. 

 while the recorder was run at 6 inches per hr. In this manner an eight- 

 fold scale expansion was achieved. An especially narrow (0.5 mm.) 

 slit-width was used for maximum resolution. Experiments were 

 scanned in triplicate and the averages of the three results determined 

 graphically. 



Carbohydrate material was detected on the chromatograms with 



