STRUCTURE OF THE ROOT 



8i 



Fig. 63. 

 a, fe, Successively older sections of the root of the Bean (I'icia Faba), showing the 

 beginning of cambial activity. In [a] divisions appear {cb) in the conjunrtive 

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

 cambium has already formed xylem internally (2n(l xy),3ind phloem externally 

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

 protoxylem (/jr.:*;^) . ( >; 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 In' looking for the 



