58 THE FRUIT OF OPUNTIA FULGIDA. 



Fig. 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. 

 X 18. 



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 placentae 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 flower 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. Drawings 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. 



