PLATE 64 



B 



A. Cross-section of bitter orange peel (Citrus aurantium, amara, L.). 

 1, Internal secretion cavity formed by the dissolution of the walls of the central 

 secreting cells; 2, Secretion cells. B. Cross-section of white pine leaf (Pinus 

 strobus, L.). I, Epidermal and hypodermal cells; 2, Parenchyma cells with 

 protuding inner walls; 3, Endodermis; 4, Secretion cavitv; 5, Secretion cells. 



