8 Lawson . — The Gametophytes , Archegonia , Fertilization , 
time, and a section of the two together has the outline of an ellipse 
that has been cut in half. They are rounded on one side and flat 
on the other. They are of equal size, and, as we shall see later, are 
both functional. Just before the male cells separate from each other, 
the nucleus in each has increased to about twice its original size. The 
chromatin is in the form of a network which contains a large irregularly 
shaped nucleolus. 
At the time of fertilization the male cells become almost spherical, and 
are perfectly similar in regard to their size and structure. Arnoldi (1901) 
has reported that the male cells may become elongated, and he figures one 
that has a spirally twisted form. I was unable to find such conditions, and 
feel confident that they are abnormal or due to shrinkage by poor fixation. 
In all the cases I have examined the male cell was spherical, and, as we 
shall see later, its spherical form may persist for some time after its nucleus 
has been injected into the egg. 
As we shall point out later, under the head of fertilization, only the 
nucleus of the male cell enters the archegonium, the rest of the male cell 
remaining outside in the pollen-tube. The nucleus is first liberated and, 
with but a small film of protoplasm surrounding it, passes between the 
neck-cells of the archegonium and immediately fuses with the egg-nucleus. 
In all other Gymnosperms in which observations have been recorded, at 
least one male cell enters the archegonium, so that in this respect the 
spermatogenesis of Sequoia is unique. According to the following diagram, 
Coulter and Chamberlain have compared the spermatogenesis of the Cycads 
with that of Isoetes. 
Isoetes. Cycads . Sequoia sempervirens. 
0 Generative cell @ Generative cell . . a 
It will be observed that the male gametophyte is complete with the 
organization of the male cells, and this is true for all other gymnosperms 
where spermatogenesis has been worked out. If, however, we construct 
a similar diagram for Sequoia , the additional step of the discharge of the 
male cell-nucleus suggests more strongly the spermatogenesis of the 
Pteridophytes than even that of the Cycads, although the male cells of 
the later are ciliated. 
