120 Sargant and Robertson . — The Anatomy of the 
polygonal in transverse section (x, Fig. 15), and thickened in a rather 
irregular scalariform way. 
Longitudinal sections through the phloem show the elements marked 
set. in Fig. 15 to be rather long cells with scanty contents and pitted walls 
not yet lignified. They clearly correspond to the sclerenchyma of the 
mature bundle. 
The structure of the soft bast is shown in Fig. 19. The section drawn 
is one of a series cut longitudinally through a seedling only a few days 
after germination. Within the endodermis (end) lie rows of long elements 
with much elongated nuclei ( s , s, Fig. 19), which alternate — not very 
regularly — with rows of shorter elements having round or oval nuclei. The 
cell contents are very dense in both. To bring out the structure of these 
elements more clearly some microtome sections, cut transversely through 
the scutellum of an eight-days* seedling and passing through its main 
bundle almost longitudinally, were treated with Schultze’s solution. No 
sieve-plates could be found in the elements marked s, s , but we have little 
doubt that they represent young sieve-tubes. As the conducting system of 
the scutellum must be most active early in the life of the seedling, that is 
during the period when it depends on the endosperm for the whole of 
its food-supply, perhaps the differentiation of the sieve-tubes may never 
proceed further. The shorter elements may represent companion-cells. 
Ramifications of various size are given off from the main bundle 
throughout its course, except for a short distance above the junction 
with the plumular bundles. In following the bundle-system upwards 
we find that branches are given off much more freely as we approach 
the apex. Even the largest are slender as compared with the trunk. 
The position of the latter shifts somewhat as it nears the apex. It moves 
from the ventral to the dorsal side of the scutellum, but never approaches 
the dorsal surface very closely (Fig. 16). 
The longer branches are commonly inserted on the lateral faces of the 
bundle-trunk and extend into the wings of the scutellum. They give off 
short branchlets towards its dorsal surface. 
The shorter branches are inserted on the dorsal face of the bundle- 
trunk and spread out towards the dorsal epithelium, showing in transverse 
section like the sticks of a fan (Figs. 16, 17). As the scutellum narrows 
towards the apex these short branches become more numerous, and a fairly 
thick radial section through the scutellum shows the main bundle feathered 
on its dorsal face by a close crop of vascular branchlets, all bending out- 
wards (cf. Fig. 1). The bundle-trunk terminates in a tuft of such branchlets, 
which reach almost to the very tip of the scutellum. 
Branches and branchlets alike terminate beneath the epithelium of the 
dorsal surface, generally ending two or three cell-rows below it (Figs. 17, 18). 
Their insertion on the dorsal and lateral faces of the bundle-trunk modifies 
