45 8 Oliver . — The Ovules of the older Gymnosperms. 
amount of fusion obtained amongst the Platysperms, and that 
the internal vascular system was restricted approximately to 
that zone. But it would be interesting to know, should the 
preservation permit of it, whether, and if so to what extent, 
the tracheal elements passed beyond the line of separation of 
nucellus and integument. For the structure of the seeds and 
the relations of the bundles recall in a very marked degree 
Cycadean characters (cf. Figs. 4 and 6). It is known that 
in certain Cycads (e. g. Bowenia and Stangeria 1 ) the inner 
system of bundles does not lie quite in the plane of fusion of 
nucellus and integument, but that the bundles exhibit a centri- 
fugal tendency and actually lie outside the arbitrary province 
of the nucellus, as determined by the downward continuation 
of the plane of separation of the free regions of nucellus and 
integument. Renault has noticed this centrifugal tendency 
in Brongniart’s seed Cardiocarpus Angus todunensis, and in 
view of this point of contact with certain Cycads he has 
founded the new genus Cycadinocarpus for its reception 2 . 
In other respects, too, the Platysperms exhibit Cycadean 
features, among which may be mentioned the relatively small 
pollen-chamber as compared with the Radiosperms, whilst 
often, as W. H. Lang has pointed out, the cells of the beak of 
the nucellus are thickened in a corresponding manner 3 . The 
pollen in the pollen-chambers of these seeds is generally 
smaller in size than the elliptical multicellular pollen so 
frequently associated with the Radiosperms. Here, too, there 
is an internal cell-group, but it by no means fills the entire 
grain. That it was antheridial in nature, as suggested by 
D. H. Scott 4 , rather than a vegetative prothallium, seems 
very probable. Whether spermatozoids were liberated directly 
from these pollen-grains, as has been suggested in the case of 
Stephanospermum , or whether they were led part of the way 
to the archegonia in tubes, as in recent Cycads, is a question 
1 I am indebted to Dr. W. H. Lang for much information concerning these and 
other Cycadean ovules. 
2 Flore fossile d’Autun et d’ISpinac, pt. ii, p. 385. 
3 W. H. Lang, Annals of Botany, vol. xiv, p. 286. 
4 D. H. Scott, Studies in Fossil Botany, 1900, p. 436. 
