Oliver . — The Ovules of the older Gym no sperms. 469 
and below. The semicircular gaps (g.) on either side owe 
their existence to the fact that the nucellus is not at this level 
wholly merged in the integument. The bundle (red) is seen 
(below) traversing a foramen. The subsequent forking of 
the strand and the direction taken by its two branches are 
shown as though happening in one plane. On the other 
side (above) the section is so drawn as to show what happens 
at a slightly lower level. The integumental bundle is cut 
below the foramen of that side, whilst within the stone the 
descending branches of the strand that has penetrated the 
foramen (in a higher plane) are represented as red dots ( x ) 
in contact with the furrow between nucellus and integument. 
It has been explained that the groove corresponding to the 
line of separation of nucellus and integument is highest opposite 
the foramen, lowest in the plane at right angles to the principal 
plane k Here in the nearly ripe seed the bundle seems to lose 
itself in the curious hypoderm of the nucellus. Though the 
bundle at this stage cannot be traced further, in a younger 
seed (May of the second year), when only desmogen is present 
and tracheides are as yet not differentiated in the upper part 
of the seed, the desmogen-strands may be traced close to the 
angle of the groove right across till they meet the correspond- 
ing branches from the opposite side. The course followed by 
these desmogen-strands may be compared to that of the side 
ropes of a hammock, the two poles from which the hammock 
is suspended standing for the two main bundles of the seed 
which run outside the stone. In other words the strands from 
the foramina encircle the base of the free apex of the nucel- 
lus (cf. Fig. 12, the horizontal red line passing across). But 
true lignified tracheides do not seem to differentiate in these 
strands much beyond the point of forking of the primary 
strand, i. e. only quite a short distance within the interior 
aperture of the foramen. And in development differentiation 
comes late in the region of the foramen — coinciding with the 
hardening of the stone. As the summer advances there 
comes a period when tracheides are well shown in the bundle 
1 In Cycas this groove dips in the principal plane, see Fig. 6. 
K k 2 
