137 



6. Still later, the ovules (O) have appeared. X 125. 



7. Transverse section of a bud at about the time the embryo sac begins 



to enlarge; (S) calyx. (P) petals. (St)) stamens, (c) carpel, (PI) 

 placenta. (\'l vascular bundle. X 75. 



S. Longitudinal section <>f carpel, same stage as Fig. 9. The micro- 

 tome section included about the area between the lines a'b'. X 345. 



9. Section of carpel along the line ab. Fig. 8. The folding together of 

 the sides is nearly completed. X 345. 



10. Young flower showing nearly simultaneous appearance of petals, 



stamens and carpel. X 125. 



11. Young ovule, sporagenous tissue not yet differentiated. X 1460. 



12. Archesporial cell. X 1460. 



13. Spore mother cell and tapetum. X 1400. 

 15. Embryo sac, two-cell stage. X 1460. 

 Hi. Embryo sac, four-cell stage. X 14(10. 



17. Embryo sac. eight-cell stage. Cells of egg apparatus cut from the 



remainder of the sac. Antipodals beginning to degenerate. 

 X 140(1. 



18. Young egg apparatus before differentiation of egg. X 1400. 



19. Mature embryo sac. The egg cell lies back of the synergids. Polar 



nuclei fusing. X 1460. 



20. Same stage as Fig. 11) but showing the position of the egg lateral to 



the synergids. X 1400. 



21. Embryo sac immediately after fertilization. Neither the egg cell 



nor the primary endosperm nucleus has divided. (S) synergid. 

 X 610. 



22. First division of primary endosperm nucleus. Egg cell still un- 



divided. X 1400. 



23. First division of primary endosperm nucleus. Telephase. X 140<>. 



24. Proembryo of two cells. X 610. 



25. Proembryo of three cells; (s) synergid. X 610. 



20. Same stage as Fig. 25 showing endosperm with radiating character 

 of the protoplasm surrounding the nuclei. X 610. 



27. Embryo of two cells. X 010. 



28. Embryo of eight cells. X OK). 



29. Embryo composed of two layers of cells. X 610. 



30. Embryo at a little later stage when the dermatogen begins to be 



distinguished. X 010. 



