144 ARCHEGONIATES. 
after pollination each spore in the pollen chamber of the macrosporan- 
gium germinates, the tube cell developing gradually into a branched 
tube which penetrates the tissue of the nucellus. The tube-nucleus 
passes into the tube, maintaining a position near the growing region 
or end as long as the tube continues its growth into the tissue of the 
nucellus, while the two prothallial cells retain their former position. 
Contrary to the genus Pzzus and other higher Cozzfers the distal end 
of the tube does not grow directly toward the archegonia, but later- 
ally and downward, serving especially as an organ for the absorption 
of food (Fig. 65, A). The proximal end of the tube, carrying before 
it the cap of exine, or the remaining outer wall of the spore, finally 
grows toward the archegonium. The pollen tube has a similar beha- 
vior in Zamza (Webber, ’97) and Gzxkgo (Hirase, ’98). 
Soon after the germination of the spore the two prothallial cells 
increase in size, especially the antheridial cell, which becomes spherical 
(Fig. 57, B, Z,). Its nucleus is also correspondingly large, and the 
cytoplasm presents a looser structure. In the meantime the anthe- 
ridial cell divides, the daughter-nuclei being of equal size. According 
to Ikeno (’98, p. 172) a wall is not formed between these two nuclei 
in Cycas revoluta. One of them now increases rapidly in size, so that 
it occupies nearly the entire cavity of the mother-cell, while the other 
remains small and is crowded out as a naked nucleus (Fig. 57, C, D, 
st). The larger cell is known as the gexeratzve cell (Kérperzelle of 
the German literature) and gives rise to two spermatozoids ; the smaller 
cell is the stazk cell (Fig. 57, C, D, s2). 
As we shall see later Webber finds that the antheridial cell divides 
regularly into the stalk and generative cells, but the plasma membrane 
separating the two cells is delicate, and the stalk cell arches over the 
first prothallial cell in such a manner as to give the appearance of the 
latter being nearly enclosed by the former (Fig. 60, F,G). It is pos- 
sible that the same is true also for Cycas. The plasma membrane, 
being very delicate, may have been overlooked by Ikeno, for the posi- 
tion of the two cells is such as to make it appear that the stalk nucleus 
was forced out of the mother-cell. 
Soon after this stage of development two small bodies appear in the 
generative cell (body-cell), lying close to the nucleus and on opposite 
sides (Fig. 57, C, c). Ikeno seems to be of the opinion that the two 
bodies, which he calls centrosomes, are derived from the nucleus, for 
the reason that just prior to their appearance outside of the nucleus, 
objects staining similarly appear within the nucleus, These bodies, 
which are the primordia of the blepharoplasts, move away from the 
