II. The Ovule of Stangeria paradoxa. 305 
Fig. 7. General view, in median longitudinal section, of the whole ovule at the 
stage with uni-nucleate embryo-sac. ( x 50.) 
Fig. 8. Longitudinal section of nucellus of older ovule, showing the embryo-sac 
with numerous free nuclei in its cytoplasm. ( x 70.) 
Fig. 9. Transverse section of ovule of similar age passing through the sporo- 
genous tissue and megaspore. ( x 70.) 
Figs. 10-12. Series of photographs of the apex of the nucellus and micropyle 
from ovules of increasing age; in Fig. 12 the pointed projection of the nucellus 
destined to form the pollen-chamber is just apparent. ( x no.) 
Fig. 13. Median longitudinal section of older ovule; the sporogenous tissue is 
reduced to a single layer around the megaspore, which is filled with the prothallus • 
the pollen-chamber is fully formed. ( x 7.) 
Fig. 14. Micropylar region, from a similar section, showing the relation of the 
pollen-chamber to the micropyle. (x 25.) 
Fig. 15. Pollen-chamber from a similar section of an aborting ovule, showing 
the large thick-walled cells forming the wall. ( x 70.) 
Fig. 16. Part of a section through an ovule of the same age as that in Fig. 14. 
From left to right are seen the edge of the prothallus, the wall of the megaspore, 
the persistent layer of the sporogenous tissue, and the tissue of the integument, 
(x no.) 
PLATE XVIII. 
Fig. 17. Sporophyll from the fertilized cone bearing a seed and an aborted 
ovule; seen from above. (Natural size.) 
Fig. 18. Dissected seed, showing the succulent and woody layer of the seed- 
coat cut through, the inner layer with its system of vascular bundles covering the 
prothallus, and the remains of the nucellus on the micropylar end of the latter. 
(Natural size.) 
Fig. 19. View of the micropylar end of the prothallus from above, showing the 
apical depression with the necks of four archegonia at its base. ( x 2.) 
Fig. 20. Longitudinal section through an unfertilized archegonium. ( x 25.) 
Fig. 21. Archegonium-neck from the base of the archegonial depression, prob¬ 
ably representing an arrested archegonium. ( x 100.) 
Fig. 22. Surface view of the pollen-chamber and remains of the nucellus from 
a seed, showing the pollen tubes radiating out from the chamber. ( x 7.) 
Fig. 23. One half of a similar specimen viewed from the inside, showing the 
blind ends of the pollen-tubes. ( x 7.) 
Fig. 24. Median vertical section through the pollen-chamber and nucellus of 
a seed. ( x 35.) 
Fig. 25. Part of a vertical section through the pollen-chamber of an absorbed 
ovule showing a dead spermatozoid (spm) in a pollen-tube which has been cut 
obliquely, (x no.) 
Fig. 26. Spiral body of spermatozoid embedded in the upper part of the cyto¬ 
plasm of a young embryo. ( x no.) 
Fig. 27. Young embryo showing commencement of vacuolization, (x 25.) 
Fig. 28. Older embryo still enclosed in the archegonium-wall, showing the large 
central cavity. ( x 25.) 
