102 THE ELEMENTS OF VEGETABLE HISTOLOGY 



PLATE 39. Cork Tissue. 



1. Saigon Cinnamon. (Sectional view.) 2. Cascara Sagrada. (Sectional 

 view.) 3. Saigon Cinnamon. (Surface view.) 4. Cascara Sagrada. (Surface 

 view.) 5. Viburnum Qpulus. (Surface view.) 6. Euonymus, stem bark. (Sec- 

 tional view.) Formation of secondary periderm. A. Primary periderm. C. 

 Layers of phellogen. R. Parenchyma included in secondary periderm. 



