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DR. J. D. HOOKER ON WELWITSCHIA. 45 
Fig. 27. Apex of endosperm-mass and embryo-sac, surmounted by and dissected away from the cone of 
the nucleus, showing the stretched tubular ends of the secondary embryo-sacs between them. 
Fig. 28. Another cone of a nucleus, with three rudimentary suspensors, which sheath as many tubular 
ends of secondary embryo-sacs. 
Fig. 29. Longitudinal section of cone of nucleus, traversed with canals, and one suspensor descending 
into the cavity of the endosperm ; the membrane of the sac still remaining. 
Fig. 30. Secondary embryo-sacs of the usual clavate form, but without bulbous bases. 
Fig. 31. Another secondary embryo-sac attenuated at both ends. 
Fig. 32. Longitudinal section of a half-ripened endosperm-mass, showing its constriction above into an 
annular fleshy neck, its cavity containing the rudimentary embryo, and its suspensor attached 
by the tubular base of the secondary sac to the cone above. 
Fig. 33. Very young embryo; its cotyledons formed at the base, the radicle very short, and above it 
the large cellular fleshy end of the suspensor; the whole covered with endosperm-cells. 
Fig. 34. Apex of a nucleus, covered with pollen-grains. 
Fig. 35. Portion of another, more magnified. 
Figs. 36 & 37. Pollen-tubes of the ordinary form. 
Fig. 38. Branching pollen-tube. 
(All the above, except figs. 10, 13, 14, 15, more or less highly magnified.) 
Puats X. Embryogeny, continued (p. 31). 
Fig. 1. Longitudinal section of an ovule on the first disappearance of the summit of the embryo-sac over 
the endosperm. 
Fig. 2, An embryo-sac very loosely investing the endosperm. 
Fig. 3. Endosperm with the secondary embryo-sacs appearing above its apex. 
Fig. 4, Longitudinal section of an ovule, when the endosperm has elongated, and dark lines appeared in 
the cone of the nucleus. | 
Fig. 5. Embryo-sac from the same, with the secondary embryo-sac protruding. The figure above repre- 
sents the tissues torn away from the summit of the endosperm. 
Fig. 6. Another embryo-sac, with the secondary sacs still further advanced. 
Fig. 7. Apex of another embryo-sac and endosperm-mass, with secondary sacs protruding. 
Fig. 8, Endosperm-cells and secondary embryo-sacs in a very early condition. 
Fig. 9. Longitudinal section of an ovule, after the embryo-sacs have taken a position above the endo- 
sperm, in the base of the cone of the nucleus. 
Fig. 10. Part of another, more highly magnified, showing the bases of the secondary sacs. 
Fig. 11. Secondary embryo-sacs, in rather a younger state, in situ. 
Fig. 12. A young secondary embryo-sac, showing the transparent globules and rudimentary germinal 
vesicle in its base. 
Fig. 13. An older secondary embryo-sac (unimpregnated), with a hooked projection at the side. 
Fig. 14. A mature secondary embryo-sac (unimpregnated), with a branching base, and appearance of two 
erminal vesicles. 
Fig. 15. A pollen-tube, having penetrated the nucleary tissue of the ovule, is in contact with the apex of 
a secondary embryo-sac. 
Fig. 16. Another secondary embryo-sac, with the pollen-tube at its apex, and its base sheathed by the 
suspensor, 
Fig. 17. Apex of another, with base of pollen-tube applied to its side. 
Fig. 18. End of pollen-tube, attached to a secondary embryo-sac, of which the terminal cell is free, 
and the lower end above it sheathed by the first series of cells of the suspensor. 
