58 THE FRUIT OF OPUNTIA FULGIDA. 



F^G. 12. Enlarged drawing of the areole shown at left in figure 11. It would probably 

 have developed a flower if it had been left on the plant. X 25. 



Fig. 13. Part of a longitudinal and radial section of an unopened flower, bearing the 

 very young bud of a secondary flower at right. X 5. 



Fig. 14. Longitudinal section of a young flower bud arising from the edge of the 

 perianth-scar on the fruit of the preceding season, showing leaves, very 

 prominent tubercles, and growing-points of the areoles on the adaxial 

 faces of the latter; showing also the shriveled nectaries developed in the 

 preceding season. X 12. 



Fig. 15. Longitudinal section of a slightly older flower than that shown in figure 14, 

 showing the depression of the growing-point and the initiation of the 

 stamens. X 18. 



Fig. 16. Longitudinal section of a still more advanced flower, showing the much 

 sunken growing-point and three series of stamens on each side of it. 

 X18. 



Fig. 17. Longitudinal section of flower with all stamens and carpels initiated. The 

 two upper areoles now face upward instead of axially. X 9. 



Fig. 18. Part of a longitudinal section of a young flower showing further closing in of 

 the carpels above the cavity of ovary to form stylar canal. X 24. 



Fig. 19. Longitudinal section of upper part of a slightly older flower, showing style 

 with free tips that are to form stigmas. X 17. 



Fig. 20. A section, similar to that in figure 19, of a flower in which the placenta are 

 just distinguishable; at base of nectary at left is a leaf -scar, and below 

 the nectary is the vascular bundle that led to leaf. X 8. 



Fig. 21. Longitudinal section of a half-matured flower, showing ovules just initiated, 

 stamens differentiated to anther and filament, etc. X 5. 



Fig. 22. Longitudinal section of a fiower nearly ready to open, showing ovules, style 

 with its conducting tissue, the papillose stigmas, and tightly over- 

 lapped sepals and petals. X 4.5. 



Plate 4. Dbawings of 0. fulgida. 



Fig. 23. Longitudinal section of a flower that has just commenced to open, showing 



ovules, papillose recurved stigma-lobes, etc. X 4. 

 Fig. 24. Longitudinal section of a young fruit from which the perianth and stamens 



have recently fallen, showing the funnel-shaped scar with its corky 



lining layer. X 3. 

 Fig. 25. Longitudinal section of a primary fruit with ripe seeds bearing a secondary 



fruit, showing relative size of fruits and degree of development of seeds, 



the connection of vascular systems, etc. X 1.5. 

 Fig. 26. Longitudinal section of two matured fruits, one or two years old, with 



aborted seeds of various sizes, though fruits are plump and normal in 



external form. X 1.25. 

 Fig. 27. Longitudinal section of a mature fruit, showing the usual shape of fruit, its 



perianth-scar, areoles, and vascular system, also ripe seeds, together with 



other seeds that have withered at various stages of development. X 1.25. 

 Fig. 28. Longitudinal section of a combination joint fruit, one or two years old, 



showing the relatively small portion of its length occupied by the 



ovarian cavity, which in this case contained only half-matured withered 



seeds; showing also the vascular system and the prominent tubercles, 



the one at the right with two spines. X 1.5. 

 Fig. 29. Transverse section of young flower bud showing petals, sepals, leaves, and at 



left one spine. X 10. 

 Fig. 30. Transverse section of same bud lower down, showing the six stigmas, petals, 



sepals, leaves, and the very prominent tubercles with their areoles; 



showing nectaries, spicules, etc. X 5. 

 Fig. 31. Transverse section of the bud shown in figure 29, at level of the styles and 



stamens. X 5. 

 Fig. 32. Transverse section of the bud shown in figure 29, at level of the ovarian 



cavity, showing first rudiments of ovules. X 5. 



