416 DR. OTTO STAPF ON THE 
structure of the radicle or of the scutellum up to which they may continue. I 
have no explanation to offer at present with respect to these appendages and furrows, 
but they seem to point toa certain plasticity of the coleorrhiza, and throw, perhaps, 
some light on the nature of the epiblast as an appendage of the coleorrhiza. 
3. The Seutellum.—The scutellum (Pl. 45. figs. 3, 5, 7, sc.; Pl. 47. figs. 36-38, 51) is a 
large fleshy body, 20 to almost 40 mm. long, and 12 to 16 mm. in diameter where widest. 
It is oblong-ellipsoid, terete or slightly compressed at a right angle to the median plane. 
Its surface may be regularly curved, or slightly constricted about the middle, or faintly 
indented on one side. "This indentation (Pl. 47. figs. 36, 37) corresponds to the upper 
end of the ovarial cavity, which in the mature seed is completely obliterated, but leaves 
occasionally traces in the moulding of the scutellum which fills up the cavity. At the 
base, the scutellum is slightly produced into a rim, so as to cover a part of the radicle 
and the plumule. The rim (Pl. 47. figs. 36, 37, 38, 40) may be two-lipped, as shown in 
Pl. 47. figs. 36 & 40, or it may be interrupted where the coleorrhiza scale overlaps the 
base of the scutellum (fig. 40). The epidermis of the scutellum is developed almost 
entirely as haustorial epithelium (Pl. 46. fig. 29, ep//.), and agrees exactly with that of 
Triticum and other grasses. "The cells are about twice as high as wide, thin-walled, not 
at all euticularized, and full of plasma and proteids. "Their outer walls, as a rule, bulge 
very little, although sometimes cells, or groups of cells, may be seen projecting beyond 
their neighbours; but they do not seem to grow out into papille, as is the case in certain 
other grasses. An exception to this epithelial modification of the epidermis, however, 
is to be found at the very base of the scutellum, mainly where it overlies the embryo 
proper. Here, over the edge as well as on the inner side of the reflexed rim, the 
epidermal cells are comparatively shallow, their outer walls thickened and covered by 
a delicate cuticle. They contain plasma, but only in moderate quantities. The bulk 
of the tissue of the scutellum consists of thin-walled parenchyma (Pl. 46. fig. 35) with 
plenty of interstices, the cells decreasing near the periphery. It is only in the basal rim 
that the parenchyma assumes a collenchymatie character. The cells are pitted, the 
pits being circular or oblong, and, owing to the thinness of the walls, of course very 
shallow. The cell-walls are of pure cellulose. The scutellum is traversed throughout 
its length and breadth by numerous vascular strands (Pl. 45. fig. 5, Pl. 47. fig. 51), 
which, entering at its base from the axis, spread like the halms of a loose sheaf, 
branehing freely towards the periphery, and terminating in innumerable branchlets 
close to the epithelial surface, separated from it by not more than 2-3 layers of small 
parenchyma. They consist mainly of a delicate cambiform tissue, with slender strands of 
tracheids (Pl. 46. figs. 33, 34), and appear to possess no solid contents with the exception 
e of some scanty starch in the outer parts. The tracheids disappear just below the ends 
of the strands, which terminate with a cap of cambiform tissue. 
The Hypocotyl.—If we remove the radicle, plumule, and scutellum from the embryo, à 
portion of the latter is left which has approximately the shape of a piece cut out of a 
. cylinder with an elliptical base by two oblique sections intersecting at an angle of 90—. 
100° just within one of the poles of the short axis. The line of intersection would 
