15 
Observing a cross section of any embryo, one sees that the scutellum 
surrounds the plumule like a sheath. In Zea (figs. 4 A-F, Pl. I), 
Andropogon (figs. 10 A and B, Pl. II), and others the plumule is almost 
completely surrounded by the scutellum, so that only a narrow opening 
may be seen. A longitudinal section of Andropogon saccharatus (fig. 9, 
Pl. II) shows the scutellum so completely surrounding the plumule that 
it appears as if an epiblast was present. By observing a cross section, 
however, it is seen that the margins of the scutellum surround the 
plumule with the exception of a small slit (fig. 10 B, Pl. II). At a point 
toward the apex of the plumule sheath the scutellum bears a protuber- 
ance which projects over the plumule. This is especially distinct in 
Lygeum (fig. 25, Pl. IV), Lolium (fig. 75, Pl. VII, and Ammophila (fig. 
42, Pl. V). This part has been called the cotyledonary sheath (e. 8.) to 
distinguish it from the plumule-sheath (pl. sh.). 
At the base of the scutellum there is another protuberance in many 
embryos, such as Avena (fig. 44, Pl. V), Triticum (fig. 69, Pl. VIL), 
Anthoxanthum (fig. 29, Pl. IV), Uniola (fig. 61, Pl. VII), Bulbilis (fig. 
58, Pl. VI), and Beckmannia (fig. 60, Pl. VI). Sometimes a deep cleft 
occurs, appearing as a separation of the radicle. In some embryos the 
scutellum has a distinct sheath and a blade. A striking example of 
this may be seen in Avena (fig. 44, Pl. V), Spartina (fig. 53, Pl. VI), and 
Zizania (fig. 22, Pl. III). 
The attachment of the scutellum to the axis varies considerably in 
different embryos. Desmazeria (fig. 63, Pl. VII) and Anthoxanthum 
odoratum (fig. 29, Pl. IV) have the attaehment directly at the base 
of the plumule. In others there is a lengthening of the axis with the 
attachment at the base, leaving a very small proportion of the embryo 
to represent the hypocotyl: Zizania (fig. 22, Pl. III), Homalocenchrus 
(fig. 28, Pl. IV), and Spartina gracilis (fig. 53, Pl. VI). 
The scutellum has at every point where it comes in contact with the 
endosperm a layer of peculiar oblong cells called the epithelial layer. 
Sachs regards it as corresponding to the somewhat similar layer found 
in the cotyledons of the palms, and to the young epidermis of Ricinus 
and many other seeds. The scutellum, therefore, may be regarded as 
part of the cotyledon. 
THE EPIBLAST. 
The peculiar organ, the epiblast of Richard, situated opposite to the 
scutellum, is not very well understood. Its occurrence in the Graminee 
is of much greater frequency than is generally supposed. Warming! 
. describes the fruit of the grasses, but does not mention the epiblast. 
He figures a fruit of Avena sativa, but does not represent the epiblast, 
which is always present and quite distinct. Van Tieghem" speaks of 
the existence of a second cotyledon in a dozen or less of the genera of 
Warming and Potter. 1895. i 
2Comptes Rendus heb. Lean. l'Acad. des Sei. 124: 1896 and 1897. 
