218 XVI. THE STEM APEX. 



leaf- whorl. Each individual vascular bundle is here common to 

 stem and leaf, and is therefore designated as leaf-trace. In each 

 internode just so many vascular bundles run outwards, as leaves- 

 are represented in the leaf- whorl. The leaf-traces, lying at first 

 separated from one another, are, in about the node underlying the 

 seventh internode from the apex, connected by side branches, 

 whereby a complete vascular system is formed. Approximately 

 n the tenth internode the pith begins to become hollow 7 , through 

 the breaking apart of its cells. In the node, on the other hand, 

 the pith cells undergo a corresponding augmentation, and remain 

 in union. The lateral buds are initiated by single cells in the 

 axils of the leaf-whorl (leaf-sheath). They stand in whorls, and, 

 as examination of the mature condition shows, alternate in posi- 

 tion with the free leaf-teeth of its leaf-sheath, the tissue of which 

 they finally break through at the base, in order to come outside .. 



