Embryo of Cep halo tax us drupacea. 19 
up the space occupied by the sap of the vacuole. Before the vacuole is 
completely closed however, numerous cross-walls are formed. 
As soon as the prothallial tissue is organized the archegonial initials 
make their appearance in the form of superficial cells at the apex. There 
are generally two, but frequently three, cells formed in the neck of the 
archegonium. The sterile tissue around the necks of the archegonia grows 
forward leaving the archegonia behind, thus forming four distinct cavities 
or archegonial chambers. There are four archegonia organized, and each 
is surrounded by a single layer of jacket-cells. There was no evidence 
to show any migration of the jacket-cell nuclei into the archegonium. 
A distinct ventral canal-nucleus is organized, which in size, shape, and 
chromatin contents resembles that of the egg. It degenerates before 
fertilization takes place. 
The entire contents of the pollen-tube enter the egg. The two 
sperm-nuclei are not released from the membrane of the body-cell until the 
interior of the archegonium has been reached. The sperm-nuclei are 
perfectly similar, and it is impossible to say which one will function until 
one of them moves towards the egg-nucleus. The second male nucleus 
remains behind in the neck region of the archegonium. 
The fusion of the sex nuclei takes place in the middle of the arche- 
gonium, and at this time the male is about one-third the size of the female. 
If a resting fertilized nucleus is formed, its resting period is very brief, for 
the first cleavage spindle is organized immediately after fusion. 
The first division of the fusion nucleus takes place in the middle 
of the archegonium. The first division is immediately followed by a 
second which results in the formation of four free nuclei in the pro-embryo. 
After the second division, all of the starch c proteid vacuoles’ and 
other cytoplasmic granules sink to the lower part of the egg, and the arche- 
gonium thus becomes sharply differentiated into two distinct regions. The 
lower dense region becomes occupied by the free nuclei of the pro-embryo. 
By repeated free nuclear division there are sixteen nuclei organized 
before the formation of cell-walls. The cells eventually become arranged 
in four tiers. The end tier develops into a penetrating cap, the second tier 
forms the embryo proper, the third the suspensors, and the uppermost the 
rosette. 
There may be as many as sixteen or thirty-two cells in the embryo 
before there is any perceptible elongation of the suspensors. This early 
merismatic activity of the embryo-cells may account for the necessity 
of organizing a penetrating cap from the terminal cells. Soon after the 
suspensors have developed the penetrating cap is thrown off. 
When the primary suspensors have reached their full length their 
function is continued by a series of long embryonal tubes or secondary 
suspensors which are developed from the proximal cells of the embryo. 
