THE WALLFLOWER 



73 



xylem-plate were mature and lignified, the middle 

 part of the plate consisting of thin-walled cells still 

 in course of development. In other words, the 



ph. 



FIG. 28. Transverse section of a very young root of the 

 Wallflower, r.h, root-hairs; p. I, piliferous layer; c, 

 cortex ; e, endodermis ; pc, pericycle ; x, xylem-plate ; 

 the protoxylem is at its two ends ; ph,ph, the two phloem 

 groups. Magnified 110. (R. S.) 



protoxylem, or oldest wood, of the root is formed at 

 the outside, and development advances from without 

 inwards, just in the reverse order to that which ia 

 followed in the formation of xylem in the stem, 



