THE SEEDLING AND YOUNG PLANT. 



69 



come thinner (Fig. 21), and the same is found as it tails 

 off below ; changes in structure also appear in the leaves. 



FIG. 18. Longitudinal radial section of the cortex and phloem of oak. 

 References as in Fig. 17. (Luerssen.) 



The first noticeable change is the diminution in 

 the number of wood fibers and the presence of narrow 



