76 



PLANT LIFE 



cell becomes directly continuous with those 

 of longitudinally adjacent cells. Such tubes, 

 which have arisen by the disappearance of 



B 



Fig. 11. Diagrammatic section of young wood stem. B, B, 

 bast ; C, C, cambium ; E, epidermis ; M, later wood ; P, 

 the first wood formed (protoxylem) ; Pi, pith; B, rind; 

 S, stoma; V, V, vessel; WP, wood parenchyma. 



walls, are often called vessels. The water- 

 conducting cells which keep their walls intact 

 are termed tracheids. The tracheids and 

 vessels then form the special tissues in the 



