CELL-CONTENTS AND FORMS OF CELLS. 293 



FIG. 158. Development of Cork: A, in epidermal cells of stem of Oleander; B, 

 development of cork in upper row of collenchymatous cells in the stem of Sambucus nigra; 

 C, development of cork meristem in cells of cortex immediately above the primary bast 

 fibers in Rubus fruticosus; D, development of primary cork In cells above the secondary 

 bast fibers of Clematis Vitalba; e, epidermal cells; k, cork; km, cork-meristem ; c, collen- 

 chyma; b, parenchyma; b, b, primary bast fibers; b', secondary bast fibers; K, young 

 cork cells. After Dippel in "Das Mikroskop." 



BORK. The cork cambium or phellogen develops before ma- 

 turity in the green stems of woody plants belonging to the dico- 

 tyledons. It may develop in the primary or secondary tissues 



