508 Shove.—On the Structure of the 
a short time in the superficial zone, takes part in the forma¬ 
tion of strands for leaves II, III, IV, V. The gap thus caused 
in the second zone is filled up in a similar way by a segment 
coming from the third zone. In Fig. 5 the dotted lines show 
the strands of the third zone; a portion of this passes into 
the second zone opposite leaf IV at E, F, G, H, and is here 
darkly shaded. Still continuing its course outwards, the 
segment passes into the superficial zone at M, N, and fills 
up the gap caused by the giving off of strands to leaf IV, 
and finally shares in the formation of strands destined for 
leaves V, VI, and VII. It probably shares also in the 
formation of a fourth leaf, not shown in the drawing, but 
indicated by the direction of the strand K. 
Compensation is thus carried on from zone to zone in the 
way described by Mettenius, who worked out the relative 
arrangement of the compensating segments in great detail. 
The regularity described by him is, however, not apparent in 
the stem now described. 
Fig. 6 shows the compensating segments from the second 
zone filling the gap in the first, but the large number of the 
roots and the irregular arrangement of the leaves make it 
impossible to trace the compensation to greater depths. As 
in Fig. 5, the shaded strands are those belonging to the second 
zone. 
In considering the foliar strands we find that at some level 
a transverse section of a leaf-base shows from four to six 
steles arranged along the convex side of the leaf-base, so 
that between them and the flattened side of the leaf there 
is a considerable mass of parenchyma. The strands of the 
meshed segment corresponding to these steles as seen in 
transverse section branch and anastomose freely, and soon 
assume the arrangement of a meshed cylindrical surface. 
Further anastomoses and divisions then take place, resulting 
in the formation of the fine stipular threads, and of the 
concentric zones occupying the higher part of the leaf-base. 
Figs. 9-12 show a series of transverse sections of a leaf- 
base. At its point of junction with the stem the leaf shows 
