PLATE 56 



A. Cross-section of belladonna leaf (Atropa belladonna, L.). I, Epidermal 

 cells; 2, Guard cells even with the leaf surface; 3, Surrounding cells; 4, Air 

 space below the guard cells; 5, Palisade cells; 6, Mesophyll cells. B. Cross- 

 section of deer tongue leaf, i. Epidermal cells; 2, Guard cells above the sur- 

 face of the leaf; 3, Surrounding cells; 4, Air space below the guard cells; 

 5, Hypodermal cells. C. Cross-section of white pine leaf (Pinus strobus, L.l. 

 I, Epidermal and hypodermal cells; 2, Guard cells below the leaf surface; 

 3, Surrounding cells; 4, Air space below the guard cells; 5, Parenchyma cells 

 with projecting inner walls. 



