24 
Campbell.—Studies on the Araceae. 
Fig. 18. Section through an older pollen-sac, showing the young pollen-spores 
embedded in the nucleated protoplasm derived from the disintegration of the tapetum. 
Leitz, oc. i, obj. 7. 
Fig. 19. Section of a nearly ripe pollen-spore showing the generative cell, g., 
and the vegetative nucleus, v. Leitz, oc. 1, obj. 7. 
Fig. 20. Wall of the ripe pollen-sac. 
Fig. 21. a , Young embryo sac of Aglaonema sp., with four nuclei, two only of 
which appear in this section; b , one of the nuclei from the base of the sac. Leitz, 
oc. 1, obj. 7. 
PLATE II. 
Figs. 22-32 refer to Aglaonema sp., the others to Lysichiton Kamtschatcense , 
Schott. 
Fig. 22. Nearly median section of an ovule of Aglaonema ; two antipodal cells, 
ant., only could be distinguished. Leitz, oc. 1, obj. 3. 
Fig. 23. a, the egg; b, the synergidae from the same. Leitz, oc. 1, obj. 7. No 
polar nuclei could be detected. 
Fig. 24. The two antipodal nuclei from the same embryo-sac; these are in the 
prophases of division. 
Fig. 25. Upper end of the nucellus and embryo-sac with the endosperm already 
developed. No embryo was visible. 
Fig. 26. Nearly median section of an ovule shortly after fertilization ; the embryo- 
sac is already filled with a large-celled endosperm, and the embryo is three-celled. 
Leitz, oc. 1, obj. 3. 
Fig. 27. An older ovule, with the embryo-sac and embryo, em. 
Fig. 28. Two-celled embryo. Leitz, oc. 1, obj. 7. 
Fig. 29. Three-celled embryo. 
Fig. 30. Group of antipodal (?) cells from an older embryo-sac. 
Fig. 31. Longitudinal section of the embryo-sac from an older ovule, showing 
its bent form. 
Fig. 32. Peculiar group of antipodal (?) cells from an older embryo-sac. 
Fig. 33. Median longitudinal section of a young embryo of Lysichiton. 
Fig. 34. Longitudinal section of a young ovule of Lysichiton ; ma ., the embryo- 
sac. Leitz, oc. 1, obj. 3. 
Fig. 35. Nucellus and young embryo-sac of Lysichiton. Leitz, oc. r, obj. 7. 
i., tapetal (?) cells above the embryo-sac. 
Fig. 36- Nucellus and embryo-sac from an older ovule. 
Fig. 37. Nearly mature embryo-sac in longitudinal section, showing part of the 
egg-apparatus and one of the antipodal cells. Leitz, oc. 3, obj. 7. sy., a synergid; 
0., the egg. 
Fig. 38. The egg and one of the synergidae from a mature embryo-sac. 
Fig. 39. Transverse section of the antipodal cells from a mature embryo-sac. 
Leitz, oc. 3, obj. 7. 
Fig. 40. Two of the antipodal cells from the same sac; the nucleolus of the 
lower one has been displaced in sectioning. 
Fig. 41. The two polar nuclei in process of fusion. Leitz, oc. 3, obj. 7. 
Fhg. 42. Two longitudinal sections of a young embryo of Lysichiton. 
