Oliver . — The Ovules of the older Gy mno sperms. 475 
EXPLANATION OF THE FIGURES IN 
PLATE XXIV. 
Illustrating Professor F. W. Oliver’s paper on the Ovules of Gymnosperms. 
In all cases red colour indicates tracheal tissues. 
Fig. 1. A conjectural synthetic type of seed embodying the characters of such 
a seed as Stepkanospermum with those of a Cardiocarpus. 
Fig. 2. Hypothetic stage connecting the Cycadean ovule with the palaeozoic 
type, b., the supposed intercalated younger zone. 
Fig- 3 - Ovule of Cycas Rumphii , cut in the principal plane. The dotted lines 
beneath the pollen -chamber indicate the shrinkage of the original nucellar 
strands. 
Fig. 4. Section of ovule of Cycas Rumphii cut in the principal plane. sb. } 
main supply-bundle; nb., insertion of nucellar bundles on the main strand; nb'., 
nucellar bundle inserted on an integumental bundle ; ib., integumental bundle ; si., 
stone or sclerotesta. 
Fig. 5. The same ovule cut in the plane at right angles to the principal plane. 
References as in Fig. 4. 
Fig. 6. Ovule of Cycas Rumphii dissected so as to show the vascular system of 
the nucellus. The dotted line p. indicates the position of the principal plane of the 
ovule. The nucellar bundles (nb'.) that arise from an integumental bundle are 
alone coloured red, ib ., place of insertion of integumental bundle on the main 
supply-bundle. AA., B.B. , heights at which the transverse sections represented 
in Figs. 8 and 7 respectively were cut. Other references as in Fig. 4. 
Figs. 7 and 8. Transverse sections of the ovule represented in Fig. 6 at the 
heights B and A. The red dots in the nucellar circle of bundles in Fig. 7 are 
those which are inserted upon the integumental bundles. They have died out at 
the height at which Fig. 8 is cut. 
Fig. 9. Diagrammatic median longitudinal section of Lagenostoma. pc pollen- 
chamber containing pollen-grains; pew., wall of pollen-chamber; cc., the central 
cone of nucellar tissue in the pollen-chamber ; g., space between pollen-chamber 
wall and canopy; c., canopy ; v., tracheal strand here running in a chamber of 
the canopy ; t., testa ; a ., archegonium. The unshaded cavity of the chambers 
contained a soft parenchyma ; the tissue within the shaded layer of the testa in the 
body of the seed was probably of the same character. 
Fig. 10. Median longitudinal section of palaeozoic seed type for comparison 
with Torreya. The light red shade on the nucellus is to indicate a continuous 
tracheal mantle. Beneath the nucellus is the tracheal plate (dark red), and two 
supply-bundles each of which originates an integumental bundle. 
Fig. 11. Transitional type connecting with Torreya. At b. the broken lines 
indicate the position of the supposed intercalated zone. The dark red horizontal 
stripe across the nucellus is the stretched tracheal plate, now a ring. The arrows 
show the downward extension of the nucellus and embryo-sac. 
Fig. 12. Median longitudinal section of seed of Torreya through the principal 
plane, a ., arillus ; i., integument becoming hardened ; it is continued as a dark 
shaded layer right round the seed ; /, foramen perforating sclerotesta and allowing 
