450 BOTANICAL GAZETTE [December 



Figs. 5, 6. — -Parts in fig. 4 at an older stage. 



Fig. 7. — Ovary cavity and stigma being differentiated. 



Figs. 8, 9. — Showing comrnon origin of stamens and petals, differentiation 

 of ovary, and relation of floral parts. 



Fig. 10. — Section showing pistil and ovules on axile placenta. 



Fig. II. — Young ovule showing archesporial mother cell and nucellus, 

 also integument. 



Fig. 12. — Young ovule showing megaspore mother cell. 



Fig. 13. — Axial row of 4 megaspores; nucellus, tapetum, and integument 

 also shown. 



Fig. 14. — Axial row of 4 megaspores; 3 micropylar ones degenerating. 



Fig. 15. — Two-nucleate embryo sac. 



Fig. 16. — Four-nucleate embryo sac' 



Fig. 17. — Micropylar end of mature embryo sac. 



Fig. 18. — Chalazal end of mature embryo sac. 



Fig. 19. — Embryo sac showing antipodal polar nucleus, two synergids, 

 egg, and micropylar polar nucleus. 



Fig. 20. — Two synergids and egg. 



Fig. 21. — Fusion of 2 polar nuclei. 



Fig. 22. — Ovule just before fertilization and its relation to nucellus, 

 tapetum, and nutritive tissue; funiculus also indicated. 



Fig. 23. — First division of endosperm nucleus forming 2 cells. 



Fig. 24. — Four cells of endosperm; 2 chalazal ones later form haustoria. 



Fig. 25. — Two chalazal haustoria; the 4 micropylar haustoria and the 8 

 endosperm cells separating the haustoria. 



Fig. 26. — The 3-ceUed embryo in surrounding endosperm cells in longi- 

 tudinal section. 



Fig. 27. — The 3-celled embryo; single cell later forms suspensor, while 

 the 2 cells later form embryo. 



Fig. 28. — Cells dividing to form quadrant stage; 2 suspensor cells shown. 



Fig. 29. — Relation of chalazal haustoria to nutritive tissue; tapetum and 

 endosperm cells. 



Fig. 30. — Relation of micropylar haustoria to tapetum. 



Fig. 31. — Cross-section through central region of embryo sac showing 

 endosperm division into 2 rows of cells throughout the sac. 



Fig. 32. — Outline drawing showing micropyle, funiculus, and relation of the 

 2 rows of endosperm to rest of ovule. 



Fig. 33. — ^Later stage showing increase of endosperm in proportion to rest 

 of ovule. 



Fig. 34. — Young embryo showing the 4 cells in suspensor. 



Fig. 35. — Cross-section through mature seed showing embryo, thickened 

 endosperm cells filled with protein, and remains of integument which now 

 functions as the testa. 



Fig. 36. — Enlarged drawing of thick-walled protein-filled endosperm cells. 



