II. The Ovule of Stangeria paradox a. 291 
When pollination takes place the ovule is probably in the 
condition represented in Fig. 13. In normal ovules, as growth 
proceeds, the nucellus becomes reduced to the pollen-chamber 
in the centre of a thin cap of compressed tissue ; the stages in 
the absorption of tissue leading to this were not observed, the 
nucellus of the aborted ovules on the pollinated cone being 
in the former state, and that of the seeds in the latter. Pollen- 
grains were present in all the pollen-chambers. While some 
of the grains presented no alteration or were merely attached 
to the wall of the chamber by short tubes, others had under¬ 
gone great changes. The pollen-tubes had penetrated the 
tissue of the nucellus, and were found radiating on all sides 
from the pollen-chamber (Figs. 22, 23). Usually their course 
lay just beneath the surface of the nucellus, but in some of the 
aborting ovules, in which the more internal tissue of the 
nucellus was not absorbed, the tube had grown inwards 
through this ; this latter course was evidently abnormal. 
The pollen-tubes were of considerable length, and of a much 
greater diameter than the pollen - grain itself. The free 
portion of the tube to which the wall of the pollen-grain was 
attached bent downwards towards the base of the pollen- 
chamber, which, by the absorption of the internal tissue of 
the nucellus, offers a free passage towards the megaspore 
(Fig. 24). The free end of the tube did not appear to project 
much beyond the lower opening of the pollen-chamber, and 
was thus in the seed separated from the archegonium-neck by 
almost the whole depth of the archegonial depression. To 
what extent this depression is fully formed at the time of 
fertilization it is impossible to say, but there is sufficient 
evidence to show that the passage from the pollen-tube to 
the archegonium-neck is effected by the independent motility 
of the spermatozoid. The details of the development of the 
latter from the generative cell of the pollen-grain could not be 
followed, but in the free ends of pollen-tubes in the aborted 
ovules two fully developed spermatozoids were present. These 
had apparently died in the unopened pollen-tubes, and con¬ 
sequently stained very badly, but the spiral cilium-bearing 
x 
