652 DR DICKSON ON DEVELOPMENT OF 



Fig. 6. Young flower. Ovary beginning to appear to the anterior side of receptacular centre as a 

 semilunar elevation alternate with the anterior (fertile) stamens. x 77. 



Fig. 7. Young flower. The extremities of the semilunar ovarian wall are now extending them- 

 selves round the receptacular centre. x 77. 



Fig. 8. Young flower. The ovarian wall is now completed by union of the extremities of the 

 semilunar elevation in the middle line posteriorly. The receptacular centre, hitherto 

 depressed, is becoming slightly elevated, forming the rudiment of the free central 

 placenta. x 77. 



Fig. 9. Young inflorescence. In the first flower the ovarian wall is completed, and begins to show a 

 tendency to bilabiation. The fertile anthers now show themselves to be 4-celled. 

 Leaf-spiral from right to left. x 77. 



Plate XXIX. 



Pviguicula vulgaris. 

 Fig. 10. Young pistil, showing larger or anterior (a) and smaller or posterior (p) lip of the 

 stigma. The disproportion between the lips is not yet very great. x 85. 



Fig. 11.* Young pistil, considerably further advanced, exhibiting nearly its adult form. Anterior 

 lip of stigma broadly expanded, the posterior narrow and strap-shaped. x 15. 



Fig. 12. Longitudinal section of young flower at about the stage represented in fig. 9, pst, pistil. The 

 placental elevation (pc) is now commencing to appear. x 30. 



Fig 13. Longitudinal section of young flower at a further advanced stage. The ovarian cavity is 

 becoming somewhat " inferior " posteriorly. As yet no ovules. x 30. 



Fig. 14. Longitudinal section of half-mature flower-bud. The corolla now extends beyond the 

 sepals, and its spur (c) is of considerable length. The ovarian cavity is now nearly 

 half-inferior posteriorly. x 30. 



Fig. 15. Young flower-bud, showing the aestivation of the sepals. x 15. 



Fig. 16. Young placenta, showing the basipetal succession of the ovules (ot), which have as yet 

 appeared only on its upper part. x 100. 



Fig. 17-22. Outline-sections (partly optical) of ovules at different stages of development. Nucleus 

 (n); integument (int). In fig. 22 the embryo-sac (es) appeal's to have wholly 

 replaced the nucleus. 



Plate XXX. 



Pinguecula vulgaris. 

 Fig. 23. Abnormality. Young flower with dimerous symmetry and regular, ; 2 sepals (s), 2 petals 

 (p), 2 stamens (st). The ovary is faintly indicated. x 77. 



Fig. 24. Abnormality. Young flower with hexamerous symmetry. Sepals — 1 anterior (sa\ 2 

 antero-lateral (sat), 2 postero-lateral (spl), and 1 posterior (sj>). Petals — 2 anterior (pa), 

 2 lateral {pi), and 2 posterior (pp). Two stamens (st), here antero-lateral; and three 

 staminodes (sf), 1 anterior and 2 postero-lateral. x 77. 



Fig. 25. Abnormal young pistil. Ovarian wall deficient posteriorly, exposing the placenta and 

 ovules, x, lappet of doubtful significance. x 15. 



Fig. 26. Abnormal young pistil, with bipartite posterior lip of the stigma, a, anterior lip of stigma ; 

 p p', the halves of the posterior lip. x 85. 



Fig. 27. Abnormal young pistil. Anterior lip of stigma tripartite, being divided into an antero- 

 median lobe (am), and two antero-lateral lobes, one right (rat), the other left (Jul.) . x 85. 



Fig. 28. Left antero-lateral view of the same pistil, showing a slightly-marked "lobule" (tbl) at the 

 left side of the base of the antero-median lobe. x 85. 



* In this figure, as also in fig. 31, the capitate hairs scattered over the surface of the ovary are 

 not represented. 



