THE OAK. 



Then, inside this periderm we shall find the phloem 

 forming an almost continuous ring (Fig. 24, se.ph), and 



ep~ 



FIG. 24. Transverse sections (semi-diagrammatic) of roots of oak, to bo 

 compared with Fig. 7. The smaller figure, above, shows the cambium 

 ring, com, now developed as a continuous layer running inside the 

 primary phloem, pr.pli, and outside the primary xylem, pr.x ; and 

 the larger figure shows the results of its activity in the formation of 

 secondary phloem, se.ph, inside the primary, and secondary xylem, 

 ee.x, between the primary xylem groups. In both cases, fp., piliferous 

 layer; c, cortex; P, pith ; A, endodermis. Within the latter lies the 

 pericycle, in which the cork cambium, c.cam, is now developed. 



consisting chiefly of the sieve-tubes and cells developed 

 from the cambium cylinder, the small primary phloem 



