aos cell divides into several neck cells, all in the tangential plane, ser serv- 
1917] DUPLER—TAXUS CANADENSIS 127 
Growth of the endosperm goes on rapidly, the greater meristematic 
activity being in the central portion, especially in the basal region. 
In the early history of the endosperm the cells are uninucleate, but 
as the embryo develops they become multinucleate, while in the 
central portion of the endosperm, below the growing tip of the 
embryo, the cells become elongated, forming a conducting tract for 
the food from the basal region of the ovule to the growing embryo. 
This elongation ceases to show after the embryo reaches maturity. 
In the mature endosperm, with the exception of the extreme 
micropylar portion, an abundance of food material is stored, this 
being the food supply of the seedling in the early stages of its 
germination. 
A comparison of the size of the endosperm at different times mn 
its development may be of interest. In fig. 52 there are shown 3 
outline drawings, to the same scale, showing the comparative size 
of the endosperm at the time of wall formation (as in fig. 51), at 
the time of fertilization, and at the maturity of the seed. It is 
readily seen that the greatest growth of the endosperm takes place 
after fertilization. 
Archegonia.—The archegonium initial arises ba the outer- 
most layer of cells and is recognizable very shortly after periclinal — 
walls come in. The initials appear a short distance behind the 
“point” of the endosperm, but always occur in the micropylar end 
if the gametophyte is one which has developed from an inner — oS 
megaspore; in case of a gametophyte from an outer megaspore the 
archegonia will be on the side of the gametophyte toward the — 
center of the ovule. The initials can be recognized by their slightly 
larger size and by the size of their nuclei (fig. 53). The surrounding 
cells form the archegonial jacket. The initial divides into the — 
_ primary neck cell and the central cell (fig. 54). The primary yneck 
ng merely Il, a “neck” hardly being 
: = of the maturity. of the a are mere sane usually wi ith 
able. These neck cells become flattened, and by the time 
