176 



The Ohio Naturalist. 



[Vol. IV, No. 8, 



Fig. 



14. Embryo-sac with fusion of the gametes and triple fusion below. 

 Below the sac appears the beginning of the cavity formed by the 

 breaking down of the ovular tissue, with axial row of glandular 

 cells. 



Fig. 15- 

 Fig. 16. 

 Fig. 17. 

 Fig. 18. 



Fig. 19. 

 Fig. 20. 



Fig. 21. 

 Fig. 22. 

 Fig. 23. 

 Fig. 24. 



Fig- 25. 

 Fig. 26. 

 Fig. 27. 



Fig. 2S. 



Fig. 29. 

 Fig. 30. 



PLATE XVII. 



Abnormal embryo-sac, showing three separate nuclear fusions. 

 Early stage in development of the axial row of cells. 

 Axial row of cells further developed. 



Perfectly developed axial row, surrounded b}- a cavity formed by 



the breaking down of the cells of the surrounding tissue. 

 The cavity below the sac, with irregularly developed axial row. 



Basal cavity below the etnbryo-sac, with irregularly developed axial 

 row. 



Basal cavity with groups of nuclei massed together. 



Three-celled embryo. 



Four-celled embryo and pollen tube. 



Four-celled embryo with pollen tube and early formation of endo- 

 sperm. 



Six-celled embryo with remains of pollen tube and one synergid. 



Section of young spherical embryo. 



Endosperm and embryo somewhat flattened by being in contact 

 with the wall of the ovule. 



Section of embryo, showing difference in staining between the 

 basal and outer parts. 



Section of spherical embryo. 



Section of embryo, showing the flattening due to the development 

 of the incipient " cotyledonary " ridge. 



Fig. 31 

 Fig. 32 



Fig. 33 

 Fig. 34 



PLATE XVIII. 



Section of the flattened embryo further developed. 



Section of embryo, showing the two sides of the cotyledonary 

 ridge. 



Section of embryo, showing the beginning of the dome-shaped 

 protuberance l^etween the cotyledonary lobes. 



Section of the dome-shaped protuberance, or the incipient plumule, 

 showing terminal origin, side by side, of first leaf and stem tip. 

 Outline section of embryo, showing incipient plumule. 

 Outline section of embryo, showing the plunmle further advanced. 

 Surface view of the incipient plumule a little older than in Fig. 36. 



Outline section of plumule, showing the beginning of the develop- 

 ment of the leaf blade. 



Surface view of a still older plumule than Fig. 38. 



Outline of section of embryo, showing the position of the first three 

 leaves. 



