506 Shove .— On the Structure of the 
e belong to leaf I, the bundles marked c to leaf IV, and so on. 
The sets of leaf-trace bundles are arranged in an irregular 
spiral round the stem, but the actual phyllotaxis could not be 
determined owing to the apparent discontinuity of the spiral 
on the under side of the stem. 
Only a few roots are produced by the vascular strands 
occupying the upper surface of the stem; these come 
sometimes from the outermost, sometimes from an inner 
zone. 
In Fig. 5 only five roots (r) have been shown, since the 
position of the remainder was uncertain owing to their 
removal during the dissection of the stem, but probably about 
double the number given in the drawing should have been 
represented. 
On the lower surface of the stem the meshes of the network 
are much drawn out, and there are few anastomoses between 
the strands; further, the step-like arrangement of the leaf- 
bundles as seen in the upper side of the stem is here missing, 
and the strands going to the leaves are much more parallel 
with the outermost zone. 
The whole tissue of the under side of the stem is thickly 
penetrated with roots, as is seen in Fig. 6 ; the circular out¬ 
line of the roots indicates their passage outwards in a direction 
perpendicular to the longitudinal axis of the plant. The 
sections of the roots represented in the drawing do not all 
lie in the same plane, but those in the neighbourhood of the 
shaded bundles are nearest the axis of the stem, as here 
the parenchymatous tissue has been removed to the greatest 
extent. The shaded strands are those belonging to the 
second vascular zone. 
The roots originate, a few in the outer, the majority in the 
inner zones, but some actually arise from stelar tissue nearer 
the upper than the under side of the stem, and from there 
make their way to the lower surface through almost the whole 
thickness of the stem. 
The roots emerge in general at right angles to the surface, 
or less frequently in an obliquely descending direction. The 
