HISTOLOGY OF THE LEAF. 



127 



which are loosely arranged on the lower side, leaving very large 

 intercellular spaces, but are closely packed, and leave few or no 

 intercellular spaces, on the upper (sunny) side. The cells have 

 very thin walls, contain protoplasm and a large central space 



FIG. 60. Epidermis from the under side of a leaflet, showing wavy cells ; elongated 

 (fjrosenchymatom) cells over the veins; and stomata with their guard-cells, st, 

 stomata and guard-cells; i\ veins covered by thick and prosenchymatous epi- 

 dermal cells. Intermediate stages between wavy and straight cells are also 

 shown. (Surface view.) 



(vacuole) filled with sap, and numerous chlorophyll-bodies im- 

 bedded in the protoplasm. These are especially numerous in 



