27 
seutellum entirely surrounds the remainder of the embryo, as may be 
seen in cross section or in the longitudinal section (fig. 1). There does 
not appear to be such a direct connection between the vaseular bundle 
of the scutellum and those of the plumule-sheath, as in Zizania (fig. 22, 
Pl. III), Homalocenchrus (fig. 28, Pl. IV), and other embryos. The vas- 
eular bundle of the scutellum, as in the other genera of the Maydec, 
branches into two, one traversing the upper and the other the lower 
part of the scutellum, and these again sending off lateral branches. 
The leaves of the plumule are arranged as in all grass embryos. 
Zea mays L. (figs. 3, 4 A-F, Pl. I).—The vascular system of Zea has 
already been described. The general structure of the embryo differs 
but little from that of Coix. Instead of four large lateral radicles it 
has one large main radicle (fig. 4 A) and two smaller secondary ones at 
the insertion of the scutellum bundle on the axis. The scutellum sur- 
rounds the remainder of the embryo like a mantle, the margins almost 
coming together, but separated by a long, narrow groove (figs. D and 
E). There is a deep cleft between the base of the scutellum and the 
coleorhiza (fig. 3). 
Tripsacum dactyloides L. (figs. 5, 6, T, A-B, Pl. I.—The embryo of 
Tripsacum is very similar to that of Zea and Coix, except that it has 
only one radicle. The axis is remarkably long and consists of à num- 
ber of vascular bundles, as in Coix. About halfway down the axis the 
bundles in the periphery increase toward the center, presenting the 
same condition as in Coix and Zea, again returning to the periphery 
and disappearing as they approach the radicle. The insertion of the 
scutellum-bundle is not as in Coiz, Zea, and Euchlena at some distance 
from the plumule but directly under it, where the plumule-sheath also 
branches off (fig. 6). The scutellum-bundle soon after leaving the axis 
divides, one branch traversing the lower, and the other the upper part 
of the seutellum, while these in turn have lateral branches (fig. 6). 
Aside from these bundles connected with the vascular system there are 
conducting vessels running irregularly through the seutellum, appar- 
ently nourishing organs for the plumule and radicle, as they can be 
traced to be directly connected through the epithelial layer with the 
other parts of the embryo (fig. 6). 
Euchlena mexicana Schrad. (fig. 8, Pl. II).—The structure of the 
embryo of Euchlena is almost identical with that of Zea mays, except 
thatit has no secondary radieles and the insertion of the scutellum- 
bundle is at some distance from the plumule. 
Tribe ANDROPOGONE. 
The fruits of the tribe Andropogonec have an embryo which is usually 
about half the size of the fruit itself. As in the Mayder, the seutellum 
almost completely surrounds the remainder of the embryo. By com- 
paring the embryo of Andropogon (fig. 9, Pl. II) with Zea (fig. 3, Pl. I) 
one notices a striking similarity. The scutellum-bundle is inserted on 
