SELA G I NELL A CE^ 



43 



trie and closed. In the centre is the xylem, consisting chiefly of scalari- 

 form and reticulate tracheides ; this is completely surrounded by the 



Fig. 23.— Transverse section through leaf of 6". ina-qualifolia. ch, chlorophyll-bodies ; co, 

 upper epiderm ; ett, lower epiderm ; sp, stomates ; /, air-cavity surrounding vascular bundle 

 and traversed by trabecules. (After Goebel, magnified.) 



Fig. 24. — Transverse section of stem of ^. denticulata Lk. _ b, air-cavity 

 surrounding ' vascular ' bundle. (After Goebel, magnified.) 



thin-walled phloem. The primary elements of the xylem, very narrow- 

 spiral tracheides, are formed at the angles of the bundle, and from them 



