(357) 
hence it is evident that its formation must take place quickly 
as the time of fertilization approaches. The process of fer- 
tilization brings about the usual changes in the appearance 
of the endosperm (/g. zor) which loses its starch and forms 
a hollow sac. In this case as in others the nucellus breaks 
down rapidly in the vicinity of the embryo-sac and especially 
in the direction of the chalaza. The coenocytic character of 
the endosperm is not maintained in Lagenarza so late as in 
the other forms. The nuclei soon become separated by cell- 
walls (figs. 103, rog), and the endosperm becomes a solid 
mass. Where the surrounding cells of the nucellus are in 
immediate contact with the endosperm they break down, and 
even in the direction of the chalaza where they are not in 
contact with it. But a certain zone of tissue for some dis- 
tance from the endosperm takes a darker stain and shows a 
denser cytoplasmic substance. The growth of the mass of 
endosperm is principally in length from this time on. The 
relation which it bears to the nucellus can be seen in figure ros, 
which represents the upper one-fourth of that organ. The 
cleft extends to the base of the nucellus. The condition of 
the endosperm at this time is represented by figure ro6. The 
cellular structure on the outside is more compact and increases 
in thickness as growth advances, though the central portion 
of the mass remains more open in structure. The hardening 
of the endosperm begins in the upper portion and extends 
over the upper half of its surface at the stage indicated by 
figure zos. The first divisions in the embryo are transverse 
(figs. ror, 102). In some cases the early cleavages are some- 
what irregular (fig. ro2) and the tendency is early towards 
an oval or pear-shape (jg. 103), with no regularity of cleav- 
age-planes. As growth proceeds the embryo assumes a more 
oblong shape (fg. 206), and it is only at a much later stage 
that the beginnings of internal differentiation can be seen 
(fg. r07). Then the periclinal divisions in the proximal end 
indicate the initial stages in the formation of the root-cap. 
At this stage (fg. ru7) the endosperm reaches about one-third 
the distance to the chalaza and the upper part of the nucellus 
