BIOLOGY OF HIGIIEll SEED PLANTS 



33 



elongating zone renewed when its cells become con- 

 verted into cells of the maturing and permanent 

 zones of the root above it ? Consult the text. 



FIG. 11. The growth of cells in a root tip 



a, main areas of the root tip, shaded ; b-e, camera drawings of cells from the 



various regions of the root as indicated in the figure. Note the changes in form 



and si/e of the cells as growth proceeds. The nuclei grow with the cells, hut they 



occupy a proportionately smaller part of the cell cavity as the cells enlarge 



Permanent zone. How do the cells above the elongating 

 zone differ from the cells below them in form and 

 in cell contents ? Explain the changes which have 

 taken place in these cells with their growth. 



