DNA Synthesis 



143 



some distance above the meristem, and then falls away (in 

 the 48-hour root) with a slope similar to that seen in the 

 cortical cells. (In the 24-hour root, sections were not cut 

 above 3 cm. from the tip.) 



5 loor 



4. 



O 



o 



Cortical Cells 





 < 







i 



o 



z 



% 



o 



I 



80 



60- 



40- 



-I 

 ui 

 O 20 



u 

 O 



X 24Hrs.^^P 

 O 48 Hrs. " P 



O o 



X 

 X 



->e 



-x^ 



-L 



A. 



2 '^ '" 3 4- 5 



Distance from Tip (cms) 



6 



'Vascular*' Cells 



I 

 a 



< 



o 



o 

 < 



o 



»- 

 D 

 4 



lOOr 



80 



60- 



X 24 Hrs ^^ P 



22, 



o 4.8 HRS "^ p 



O 



5 



I 40|- 



Ui 



U 20 



o 



X 

 X 



J. 



-L 



2 3 



Distance 



4 5 



FROM Tip (cms.) 



Fig. 6. Percentage of cells shoAving autoradiograph in relation to 



distance from the tip of the root. (Permission has been obtained 



by the authors from the Jotirnal for Experimental Cell Research 



for this figure to be reproduced). 



