8 The Ohio Naturalist. [Vol. VII, No. 1, 



EXPLAXATIOX OF PlATES I, II, AND III. 



The drawings are all on the same scale and were reduced to 

 i of their original size. A combination of Zeiss 18 compensat- 

 ing ocular and Zeiss 8.0 mm. Apochromat objective was employed 

 with a magnification on the table of about 900. 



1. Egg apparatus with oosphere. 6. Three-celled embryo. 



2. Elongated oospore. 7. Four-celled embryo. 

 '.i. Oospore dividing. 8. Five-celled embryo. 



4. Two-celled embryo and synergid. 9. Incipient six-celled einbryo. 



5. Two-celled embryo. 10. Six-celled embryo. 



11. Older six-celled einbryo with the upper two tiers of cells stained 



muc'i c-arker than the rest. 



12. Eight-celled embryo; the tip in the quadrant stage. 



13. Nine-celled embryo with four-celled tip. 



14. Ten-celled embryo with four-celled tip. 



15. Eleven-celled embryo with four-celled tip. 



IG. Fifteen-celled embryo with octants at the tip and seven suspensor 



cells. 

 17. Satne stage as the preceding, the octants cutting off the primary 



dermatogen. 

 IS. Twenty-two-celled embryo with primary dermatogen complete, the 



nonnal embryo at this stage has twenty-three cells. 



19. Embryo with tie cell adjoining the embryonic sphere undergoing 



transverse division. 



20. 'Typical twenty-four-celled embryo. 



21. Embryo with longitudinal division beginning in the lower tier of the 



inner octants. 



22. Typical embrj'o with ten-celled suspensor. 



23. Somewi'at later stage showing rapid multiplication of the upper der- 



matogen cells. 



24. Embryo s':owing division of the basal embryo cell and origin of the 



t.iird tier in the embryonic sphere. 

 2.5. Typical embryo at time when the lower two embryo cells are ready 

 for further development. 



26. Same stage as the preceding but somewhat one-sided in develop- 



ment and with a different ntimber of cells in the suspensor. 



27. Embryo showing first division of the root tip cell. 



28. Embryo showing the outer tier of cells from which the cotyledons 



and plumule are derived with a much darker stain than the rest 

 of the tissues. 



29. Embryo showing origin of cotyledons, stem tip, hypocotyl, root tip, 



calyptrogen and calyptra. 



30. Somewhat older emliryo than the preceding showing further devel- 



opment. 



31. Median section of embryo cut in same plane as the cotyledons. 



32. Embryo showing cells of stem tip and second division of calyptrogen. 



33. Longitudinal section through one cotyledon of embryo somewhat 



older than the preceding. 



34. Embryo just before the beginning of the final rapid elongation of 



the radicle. 



35. Embryo showing the condition of the tissues at the stage when the 



cotyledons Vjegin to curve. r 



30. Cross section of embryo at same stage as the preceding showing 



dermatogen, periblem and plerome. 

 .37. Mature embryo showing the character of the embryonic tissues. 

 38. Cross section of mature embrvo. 



