42 



VASCULAR CRYPTOGAMS 



the cells of which these, trabecules are composed are rouhd, they form a 

 loose spongy parenchyma surrounding the bundle, and sharply differ- 

 entiated from the firm compact fundamental tissue. The stem has 

 one or more cauline ' vascular ' bundles, which may be traced m the 



-Sela^ineUa intsqualifplia Spr. A , branch (natural size); B^ microsporange ; C, megasporange 

 (greatly magnified). 



procambial condition to the apex of the stem close beneath the apical 

 cell and above the youngest leaves ; the separate bundles which descend 

 from the leaves (leaf-trace-bundles) only unite with the cauline ones at a 

 later period. The bundles are usually ribbon-shaped, and are. concen- 



