358 Miyake . — On the Development of the Sexual 
The smaller cell soon divides into two cells by an anticlinal 
wall ; these two cells then divide several times by both 
anticlinal and periclinal walls and form the neck of the 
archegonium. The neck of the full-grown archegonium 
usually consists of four to eight rows of cells, with two to 
four cells in each row (Figs. 27-36, 41). Strasburger made 
a similar observation in 1869 , and stated that the neck consists 
of two to four tiers of cells. 
The rapid growth of the central cell takes place soon after 
its formation. The cytoplasm presents a very vacuolate 
appearance in the early stage of development (Figs. 27-31). 
But as the central cell continues to grow the cytoplasmic 
contents become more dense, and the number and size of the 
vacuoles gradually decrease. When the archegonium reaches 
its full size only a few small vacuoles are found in the more 
or less finely granular cytoplasm, and now a few so-called 
proteid-vacuoles begin to appear (Fig. 32). The nucleus is, 
from the first, always situated at the apex of the cell just 
beneath the neck. It has one prominent nucleolus, and some- 
times one or two smaller ones may be present (Figs. 26-36). 
Enveloping the central cell is a layer of cells rich in proto- 
plasm and with large nuclei ; these are the sheath- or wall-cells 
of the archegonium, and correspond to the follicle-cells of the 
animal egg in their function. These cells are differentiated 
from the adjacent endosperm-cells very early in the develop- 
ment of the archegonium. 
The number of archegonia in each ovule varies from two 
to seven, the most common number being four. Of over four 
hundred ovules studied, I kept an account of the number of 
archegonia in about three hundred of them, and found that 
about one-half had four archegonia ; about one-fourth had 
three, and about one-fifth had five archegonia, while eight 
cases were met in which each ovule contained six archegonia. 
In four cases an ovule was found with two archegonia, and 
but a single ovule with seven archegonia was met with. This 
agrees in the main with the observation of Strasburger (’ 69 ), 
who found three to five archegonia in each ovule of Picea excelsa. 
