464 Oliver . — The Ovules of the older Gymnosperms. 
bundle ( hb\ ) which constitutes the nucellar supply in the 
regions adjacent to the principal plane. The nucellar ring 
of bundles is completed by the strands which originate from 
the central chalazal bundle. Fig. 4 is a section in the 
principal plane, Fig. 5, in the plane at right angles to the 
principal plane. The nucellus is thus invested in a system 
of bundles of double origin. One portion, and here the chief 
portion, of the bundles has its origin in the central chalazal 
cord ; whilst on the flanks, i. e. adjacent to the principal plane, 
a limited number of bundles is supplied from the strands 
of the integument. These relations are fully exposed in 
Fig. 6, which represents an ovule with the integument of 
one side dissected away so that the nucellar bundles are laid 
bare. The principal plane is indicated by the line /., conse- 
quently the relations shown by this dissection are those that 
would obtain if Fig. 5 be imagined built up into a solid figure 
and not merely a section. For the sake of clearness the 
main supply-bundle (sb.) and the two groups of nucellar 
bundles which arise directly from its continuation are drawn 
in black in this figure (the same holds in Figs. 7 and 8), whilst 
those nucellar bundles that take their origin from the integu- 
mental bundle on the exposed side are coloured red. The 
point of insertion of the integumental bundle on the main 
supply-bundle is shown as a red spot (lb.), but the intervening 
connexions with the nucellar bundles nb' . (readily understood 
from Fig. 4) are for obvious reasons not represented. The 
transverse sections cut at the levels A and B (in Fig. 6) show 
that the series of bundles from the central cord (black in 
Figs. 8 and 7) reach nearer the pollen-chamber than those 
inserted upon the integumentary bundles (red in those Figs.). 
This disparity in the upward extension of the nucellar bundles 
is correlated with the fact that the groove between the free 
nucellus and integument extends considerably further down 
in the neighbourhood of the principal plane than it does 
elsewhere (cf. Fig. 6). The significance of this peculiarity in 
the course of the groove (which recurs also in Torreya , , see 
p. 468) is obscure. 
