14 Campbell — The Development of the Flower and 
several layers of more compact parenchyma than that lying 
between the bundles and the epidermis. 
The ovule fills the ovarian cavity almost completely, and 
there is no development of conducting papillae such as occur 
in Naias , either at the top of the ovary where the conducting 
tissue of the style terminates, or at the base of the funiculus 
near the micropyle. This may be accounted for by the fact 
that a pollen-tube which has reached the ovary can hardly 
fail to reach the micropyle, as its course along the wall would 
almost certainly bring it to the opening of the ovule. 
The Embryo-Sac. 
Unfortunately, not a sufficient number of specimens of the 
earlier stages of the embryo-sac were found to make it certain 
just how uniform the course of development is. With few 
exceptions there was nothing to indicate any marked de- 
parture from the ordinary type. In the earliest stage in 
which the archesporial cells could be recognized with cer- 
tainty, there were two cells, evidently the product of the 
division of a primary hypodermal cell (Fig. 19). The outer 
of them was the larger, and is probably to be considered the 
real archesporium, and from it is apparently next cut off the 
primary tapetal cell (Fig. 18, t ). There is thus formed a row 
of three cells in the axis of the nucellus. The form of the 
primary tapetal cell was quite different in different specimens 
examined (Figs. 18, 20), but in all cases it undergoes repeated 
divisions so that the sporogenous cell becomes more deeply 
sunk in the nucellus (Fig. 22). 
The further history of the sporogenous cell must also be 
left somewhat incomplete, owing to the small number of 
satisfactory preparations of the next stage. It is extremely 
unlikely that the primary sporogenous cell ever develops at 
once into the embryo-sac, although such a form as that 
shown in Fig. 21 might possibly be so interpreted. In some- 
what later stages (Fig. 22) there were found two or three 
cells derived from transverse divisions of the primary sporo- 
