ordinary parenchyma cell. D, sieve plate and companion cell 

 as seen in cross-section. E, epidermal cell with large vacuole, 

 but large conspicuous nucleus in contact with local thickening 

 of outer cell wall which is being formed ; p, pit in lateral wall. 

 F, large water bladder representing a single much swollen cell 

 of the epidermis, with little cytoplasm but large nucleus ; ep., 

 ordinary epidermal cells ; mes., mesophyll. 



l8 



