362 BOTANICAL GAZETTE [NOVEMBER 
parenchymatous, and the general structure is shown in jigs. 2-6, 8, 
9; 29-35. 
The epidermis (ep) consists of large, regular, isodiametric cells 
with large nuclei. That of the cotyledons is abundantly supplied 
with stomata on the exterior surface of the tubular part and a small 
portion of the lobes. No stomata occur on the part of the cotyledons 
remaining in the endosperm, on the interior surface of the cotyledons, 
or on the primordia. The epidermis of the petioles and bases of the 
leaf primordia is covered densely with long, unicellular hairs, with 
well-defined nuclei (figs. 28, 29). 
The ground tissue is composed of long, regular, prismatic cells, 
much longer than wide in the cotyledons, but shorter and more isodia- 
metric in the stem proper (figs. 3, 8). At the lower extremity of the 
embryo the cells lose their nuclei, become filled with a dense material, 
and form a hard capping tissue (cp, figs. 3, 28, 29)- Distributed 
irregularly in all parts of the ground tissue are many cells, cavities, 
and canals filled with mucilage (m, fig. 8; black spots in jigs. 28-35). 
The cavities are found most abundantly in the cotyledons and are 
formed by the disorganization of several neighboring cells. The 
canals, which are formed by the disorganization of the cells end to 
end, forming tubes of limited length, are most abundant in the 
petioles of both cotyledons and leaves. 
The vascular cylinder is very short, the length being much le 
the diameter, and hence it is usually called the vascular plate (P ) 
It is squarish, one diagonal diameter being approximately at right 
angles to the inner faces of the cotyledons, and the other parallel 
with them. The xylem (figs. 32, 33, *), consisting at this stage 
probably of protoxylem only, is surrounded by a zone of phloem (ph). 
The xylem is compact and well developed where it borders the phloem, 
but toward the center it is gradually mixed more and more with 
pith cells, till in the center the xylem elements lie scattered among the 
pith cells, these scattered cells being very short and irregular. ©" 
condition varies in different specimens, in some the xylem being se 
Coppers the center, while in others it is entirely wanting a 
Tegion (fig. 32). 
The protoxylem groups——At each corner of the sq 
Plate there is a group of protoxylem elements (P%), 
ss than 
uarish vascular 3 
which in cross- 
