Embryo and of that of the Grass in particular . 515 
Gartner’s view of the epiblast : 1 lacinula e scutello oriunda and van 
Tieghem’s former view : ■ line dependance des bords de l’^cusson ’ [scutellum], 
are really correct. Celakovsky adopts the natural and reasonable method of 
comparing the cotyledon with the foliage-leaf. Surely there could be no 
better plan than that ! As we have above seen, the developmental facts and 
anatomical structure of the mesocotyl show that the scutellum corresponds 
to the lamina of the foliage-leaf and the coleoptile to the ligule, the sheath 
of the foliage-leaf not being represented in the cotyledon except at the very 
earliest stage of all. The fact that scutellum and coleoptile are parts of the 
cotyledon is in itself sufficient to dispose of the idea that the epiblast 
represents a second cotyledon. The true nature of the epiblast is revealed 
by the following facts and deductions. The foliage-leaves of Hordenm 
(Fig. 6), Triticum , Secale , Lolium , and the larger leaves of Oryza possess 
peculiar sickle-shaped appendages to the base 
of the lamina. If these appendages were to 
become united on the opposite side of the axis, 
a structure would result comparable to the epi- 
blast. This last is, however, in many cases (not 
in all) quite separate and distinct from the 
scutellum, 1 existing as an independent outgrowth 
on the opposite side of the axis. Celakovsky 
found, however, in certain robust leaves of Oryza 
that the appendages were completely separated 
from the leaf-blade, 1 more linear or lanceolate 
in shape, hardly curved, directed upwards, and 
provided with long, bristle-like cilia on the edge 
nearest that of the leaf-blade. Now if the leaf- 
sheath and ligule were closed structures (as occurs 
in species of Melica) then the distal margins of the 
two appendages would, like those of the sheath 
and the ligule, become united, and a single appendage would result, 
situated opposite the leaf. Such a condition of things is realized in the 
seedling of Oryza , where the epiblast corresponds to the single appendage. 
The cause of the marked independence of scutellum and epiblast in many 
Grasses is that the latter, owing to the disappearance of the sheathing-base 
in the cotyledon, arises directly from the hypocotyl, so that its original 
connexion with the cotyledon could easily become obscured. 
Further light is thrown on the origin of the epiblast by the contempla- 
tion of that of Stipa , which is deeply bifid into two equal parts (Fig. 7, a), 
at once suggesting its composition from two originally separate organs. 
1 As in the case of the mesocotyl, so also in that of the area separating the scutellum-base from 
the epiblast, and the leaf-blade from the appendages, we can postulate a congenital fusion of the 
foliar parts concerned with the axis. 
Fig. 6 . Hordenm vulgar e. 
Base of lamina {Id) of foliage- 
leaf, showing auricles (a), li— 
ligule ; s = sheath. (After 
Celakovsky.) 
