VIII. KFFKCTS OF DEFICIENCY IN ANIM.VLS 



307 



Bonner and Bonner-" suggest a possible explanation for this discrepancy. 

 They foinid that certain \'arietics of peas with a naturally low concentration 

 of ascor])ic acid in the seedlings grew faster when additional vitamin was 

 supplied whereas those types with a higher content, resulting from an in- 

 herent capacity for more rapid synthesis, did not respond to an additional 

 supply. In studies with cowpea seedlings-^^ it was found that a rough paral- 

 lelism exists between growth and the ascorbic acid content of all the seedling 

 organs whether they were grown in light or in darkness. Suggestive evi- 

 dence of a relation of ascorbic acid to cell growth was obtained-**^ in studies 

 of some of the phj'sical and chemical changes occurring in successive zones 

 of the growing region of the primary root of cowpea seedlings. Determina- 



TABLE VIII 

 Relative Values in Cells of Different Ages in Root Tips of Cowpea 



Seedlings^"^ 



Region 



Volume 



Cell division 1 



Cell division and 3.2 



elongation 



Elongation 14.1 

 Elongation and mat- 35.1 



uration 



Maturation i 37.6 



Vitamin C 

 in fresh 

 weight 



1 



0.80 



0.55 

 0.33 



0.30 



These values are slightly high because no allowance was made for intercellular spaces. 



tions were made of the ascorbic acid, nitrogen, and phosphorous content 

 of the cells at different stages of development. It was observed that the 

 ascorbic acid of a cell increased greatly during the transition from the em- 

 bryonic state until approximately the time of completion of elongation. 

 No appreciable increase was found after elongation ceased and secondary 

 thickening of the wall began. Table VIII summarizes the results expressed 

 as relative values per cell, the average value for a cell in the embryonic 

 region being taken as unity. Continuous increases in \'olume, water, dry 

 matter, nitrogen, and phosphorus per cell occurred during the transition 

 from the embryonic to the mature condition. The change in surface area 

 was the only one of the various factors studied in which the increase closely 

 paralleled that of the \'itamin. The relatively high content of ascorbic acid 



="' J. Bonner and D. Bonner, Proc. Natl. Acad. Sci. 24, 70 (1938). 

 ='2 B. Lu.stig and H. Wachtel, Biochem. Z. 297, 386 (1938). 

 2'3 M. E. Reid, Am. J. Botany 25, 701 (1938). 



