Scutellum in Zea Mats . 
117 
parts of the embryo from the stores laid up in its own tissues, and from 
those of the endosperm. The contents of the endosperm are by degrees 
dissolved and absorbed by the scutellum, which transmits them in solution 
to the growing parts of the embryo. 
Epithelium and Glands. 
The epidermis of the embryo is of normal structure except on the 
dorsal face of the scutellum. Wherever this face is in contact with the 
endosperm, that is over the whole of it with the exception of the extreme 
base and a small area corresponding to the insertion of the pedicel, it is 
covered with a well-marked epithelium. This tissue has often been 
described, and is shown in our Figs. 16, 17, 18. 
The scutellum is always more or less wrinkled on its dorsal face. 
The outline of this face is marked in section by a nearly continuous dark 
line of varying thickness (Fig. 17), and the wrinkles are seen as depressions, 
sometimes filled with a dark mass. This appearance is no doubt due to 
a viscous secretion from the epithelium cells, which covers their free 
surface with a thin sticky layer and sometimes collects in the wrinkles 
like water in a furrow. We have seen it most clearly in preparations 
cut from an embryo which had been dissected from the ungerminated 
seed and fixed in methylated spirit (Fig. 13). In this specimen the 
secretion, whatever its nature, has been exposed to the solvent action 
of alcohol only, whereas all the other preparations figured are cut from 
germinating seeds, in which the tissues were of course thoroughly pene- 
trated with water before they were plunged in alcohol. The depressions 
in the dorsal outline of the scutellum are also deeper and more numerous 
in sections from the ungerminated embryo than in those cut from seedlings 
in which germination has begun. 
The epithelium is of course folded in on itself more or less sharply 
in each wrinkle, and the effect in section is that of a pit lined with 
epithelium cells and containing a dark mass of secretion (Fig. 13). But 
leading out of such furrows we sometimes find narrow clefts, also lined 
with epithelium and penetrating deeply into the tissues of the scutellum 
(Figs. 11 and 13). 
In the ungerminated seed these clefts are already fully formed. They 
always contain a layer of secretion, but they are often so narrow that 
it appears in section as a dark line of no great thickness separating one 
surface of epithelium from the other. 
The corresponding glands found in the scutellum of germinating 
embryos have commonly a very thin layer of secretion (Figs. 11 and 12), 
or it may be completely absent (Fig. 14). The two surfaces of epithelium 
then seem to be in contact. In such cases the secretion has no doubt been 
