220 Cook: DEVELOPMENT OF EMBRYO-SAC AND EMBRYO 
Fic, 2. One archesporial cell and one tapetal cell formed by a periclinal wall. 
Fic. 3. Archesporial cell and two tapetal eells formed by periclinal wall. 
Fic. 4. Archesporial cell and two tapetal cells formed by anticlinal wall. 
Fic. 5. Archesporial cell and four tapetal cells. 
Fic. 6. Functional megaspore and three dissolving megaspores and two tapetal 
cells 
Fic. 7. Functional megaspore and dissolving megaspores and tapetal cells. 
Fic. 8. Functional megaspore and dissolving macrospores and tapetal cells. 
Fic. 9. Functional megaspore and dissolving megaspore and tapetal cells. Starch 
in functional megaspores. 
Fic. 10. Two functional megaspores. (Missing nucleus was in next section. ) 
Fic. 11. Two-celled embryo-sac containing starch. 
Fic. 12. Four-celled embryo-sac containing starch. 
Fic. 13. Eight-celled embryo-sac Conjugating polar nuclei. Degenerating 
antipodals. 
Fics. 14, 15. Mature embryo-sac with egg apparatus and endosperm nuclei. 
Fic, 16. Fertilized egg and pollen tube. First division of the endosperm nuclei. 
The two nuclei separated by a wall. j 
Fic. 17. Separation of the two nuclei after division of the definitive nucleus. Fer- 
tilized egg and one synergid. : 
Fic. 18. Lower nucleus formed by division of definitive nucleus about one-third 
way down ovule. 
Fic. 19. Lower nucleus (from text figure 1). 
Fic. 20a. Lower nucleus in the enlarged end of the tube. Nucleus degenerating. 
Fic. 206. Same as 27a. 
PLATE 13 
Nymphaea advena (except Figs. 21-24, which are C. odorata). 
Fic, 21. Upper end of tube enlarged and containing embryo and endosperm. 
Age corresponds to Fig. 20. 
Fic. 22. Embryo of three cells. One synergid. 
Fic. 23. Embryo of four cells. One synergid. 
Fic. 24. Embryo of eight cells. 
Fic. 25. Embryo of twelve cells. (The other three cells were found in the next 
section. ) 
Fic. 26. Spherical embryo. 
Fic. 27. Double embryo. 
Fic. 28. Spherical embryo. One synergid. 
Fic. 29. Spherical embryo showing beginning of cotyledon (¢) and suspensor (s) 
Fic. 30. Embryo showing spherical part of embryo and the cotyledon. 
Fic. 31. Embryo showing cotyledon, two leaves of plumule (f/m. ) and root (7)- 
Fic. 32. Section from same embryo as 31 showing suspensor (5). 
