3-12 
ILL LSTRAllOm 
Plate IX. 
FULLY DEVELOPED SECONDARY STRUCTURE IN ROOT. 
Fig. 6'-'. — Transverse section of root of pea at the end of the 
summer’s growth : (E), some epidermal cells with frag- 
ments of root hairs; (C), primary cortex; (EN), endo- 
dermis; (K), cork: (B), bast hirers; (SC), secondary 
cortex; (S), sieve; (T), ducts; (W), wood fibers; 
(WP), wood parenchyma: (PM), primary medullary 
rajs; (SM), secondary medullary rays; the arrange- 
ment of xylem and phloem forming collateral bundles. 
