PLANT CELL GROWTH AND NUTRITION 



467 



Indeed, the demonstrably perforate nature of the nuclear membrane 

 (Figure 6) and the possibility of direct communication between nu- 

 cleus and cytoplasm via the endoplasmatic reticulum suggest an inti- 

 mate association between the nucleus and the cytoplasm in the deter- 

 mination of cell metabolism and behavior. 



When respiratory data are calculated on a "per cell" basis, Brown 

 et al. (1951), do not now regard the most actively dividing cells in the 

 apical meristem of the root as the most active in respiration. On the 

 contrary, the respiration and protein nitrogen per cell both increase to 

 a maximum at about that point along the axis of the root ( 5 mm. from 



Figure 6. Portions of cells in the pro-meristem region, showing well-defined 

 vacuoles and other cytoplasmic inclusions. Note the endoplasmatic reticulum. 

 (From Whaley et al, 19-.) 



