PLATE 56 
A. Cross-section of belladonna leaf (Atropa belladonna, L.). 1, 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. 1, 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:). 
1, 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. 
