43 ° 
The Ohio Naturalist. 
LVol. VI, No. 3, 
EXPL.\XAT!OX OF PLATES XXIX AND XXX. 
The drawings were made with the aid of an Abbe camera lucida and 
various combinations of and oil immersion objectives and Xo. 
2, 1, and % oculars. 
Fig. 1. Cross section of young ovulary showing incipient ovules. 
Figs. 2-5. Series of outlines showing development of integuments and 
degree of curvature of ovule at different stages. 
Fig. (i. Nucellus with archesporial cell. 
Fig. 7. Primary parietal cell and megasporocyte. 
Fig. 8. Transverse and longitudinal division of parietal layer. 
Fig. 9. Further division of parietal laj^er. 
Fig. 10. Second division of megasporocyte producing the four mega- 
spores. 
Fig. 11. Potential megaspores beginning to dissolve. 
Fig. 12. Enlargement of functional megaspore and further dissolution 
of three upper megaspores. 
Fig. 1.3. Two-celled embryo sac showing remains of third megaspore. 
Fig. 14. Four-celled embryo sac showing large vacuole in center. 
Fig. 15. Younger eight-celled embryo sac. 
Fig. 10. Older eight-celled embryo sac, showing polar nuclei in contact. 
Fig. 17. Upper end of embryo sac just before fertilization, showing large 
sac-like synergids, and polar nuclei fusing. 
Fig. 18. Two-celled embryo, and definitive nucleus. 
Fig. 19. Four-celled embryo with endosperm, and remains of two 
synergids, also pollen tube. 
Fig. 20. Young embryo of about ten cells showing irregular division. 
Fig. 21. Young embryo and scattered endosperm. 
Fig. 22. Outline of eight-celled embryo sac stage, showing micropyle 
with long beak of nucellus. 
Fig. 23. Section of young somewhat spherical embryo. 
Fig. 24. Embryo slightly older than that in preceding figure. 
Fig. 25. Section of embryo showing cotyledons. 
Fig. 26. Outline of mature embryo showing cotyledons, and plumule. 
Fig. 27. Entrance of pollen tube into micropyle and course through 
nucellar beak. 
Fig. 28. Entrance of pollen tube into embryo sac, showing peculiar 
widening near the tip. 
Fig. 29. Pollen tube showing enlargement with haustoria-like processes, 
and bending to one side after entrance into the sac. 
Fig. 30. Pollen tube showing the haustoria-like processes extending 
through inner integument. 
Fig. 31. Cross section of anther showing microsporangia and micro- 
sporocytes. 
Fig. 32. Longitudinal section of anther. 
Fig. 33. Mature pollen grain with two nuclei. 
