3 20 Sampson . — The Morphology of 
the smaller stele one passes off from each edge of the gap. This stele 
is also connected with the vascular supply of a root. In the same sec- 
tion (sect. 6) the strand of the tuber, t, is seen, closely associated with 
the compact central stele. Higher up the two are united, forming a solid 
mass of xylene which is surrounded by the three leaf-traces, which 
emerged lower down, and a fourth, which is just being given off (sect. 5). 
