430 The Ohio Naturalist. [Vol. VI, No. 3, 



EXPLANATION OF PLATES XXIX AND XXX. 



The drawings were made with the aid of an Abbe camera lucida and 

 various combinations of f , i, and j^t oil immersion objectives and No. 

 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. 6. 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 layer. 



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. 13. 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. 16. 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. Ovitline of mature embryo showing cotyledons, and jjlumule. 

 Fig. 27. Entrance of pollen tube into micropyle and course through 



nvicellar 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 jjrocesses, 



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. 



