426 
The Ohio Naturalist. 
[Vol. VI, No. 3, 
The endosperm is continuous in the region of the embryo but 
in the lower end of the sac it forms only a thin layer. The later 
divisions of the embryo are irregular; an oval mass of cells is 
formed from the end of which the cotyledons develop. When 
the embrvo is about in the ten-celled stage walls begin to appear 
in the endosperm (Fig. 20). Kirkwood found in Lagenaria 
lagenaria and other species somewhat flask-shaped embryos with 
prominent end cells which correspond closely to those of the 
same age in Cucumis (Fig. 21). 
The endosperm is not abundant but there is a greater amount 
around the embryo than elsewhere, often the lower portion of the 
embryo sac is entirely destitute of it. The endosperm stains 
more deeply along the peripheral margin and around the embryo 
where the nuclei and starch grains are more abundant. The 
embrvo, however, takes the stain much more prominently than 
anv of the endosperm cells. 
The embryo develops a distinct layer of epidermal cells 
before any cotyledonary protuberances appear (Figs. 23-24). 
The embryo develops apically two cotyledons and distinctly 
shows the root tip before there is any sign of the appearance of 
the plumule (Fig. 25). The mature embryo sac contains only a 
small amount of scattered endosperm, the main food for the 
young plant being stored in the large cotyledons. In the 
mature embryo the plumule is two-lobed showing the incipient 
first leaf (Fig. 2G). 
The microsporangia appear to develop in the usual way from 
a plate of hypodermal cells. The cells of the sporogenous tissue 
are easily distinguished from the adjacent cells by their large 
size, and different reaction to stains. The young anther shows 
in cross section a single row of three microsporocytes in each 
microsporangium (Fig. 31) ; but in longitudinal section the plate 
shows a considerable length (Fig. 32). 
The mature pollen grain has a thick wall with a bulging at 
opposite sides. The tube nucleus and generative nucleus lie to 
one side of the grain near each other; the latter takes the stain 
more deeplv than the cytoplasm of the rest of the grain, due to 
its denser structure. 
The behavior of the pollen tube in this species is of special 
interest. It is large and distinct and with Delafield’s Haema- 
toxvlin stains an amber color while the surrounding cells are a 
purplish blue ; with other stains it is of a deeper color. It enters 
the micropyle through the opening at the tips of the integuments, 
pierces the beak of the nucellus and makes its way down to the 
embryo sac by following a central path of much elongated clear 
cells which seem to offer little resistance and serve as a definite 
conducting tissue. The tube sometimes makes its way with 
