STRUCTURE OF THE ROOT 



Si 



FIG. 63. 



a, b, Successively older sections of the root of the Bean (Vicia Faba), showing the 

 beginning of cambial activity. In (a) divisions appear (cb) in the conjunctive 

 parenchyma internally to the phloem, but the pericycle (per) is quiescent. In (b) the 

 cambium has already formed xylem internally (2nd #y),and phloem externally 

 (2nd phi), and cell division has spread to the pericycle, and is continuous outside the 

 protoxylem (pr.xy). ( x 100.) 



appear, as in the stem. Consequently an old root of a Dicotyledon 

 acquires a structure very like that of an old stem (Fig. 64). The 

 difference may be often observed even in old roots by looking for the 



B H. F 



