8 
The Ohio Naturalist. 
[Vol. VII, No. 1 
Explanation 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 wasemployed 
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. 
3. Oospore dividing. 
8. 
Five-celled embryo. 
4. Two-celled embryo and svnergid. 
9. 
Incipient six-celled embryo 
5. Two-celled embryo. 
10. 
Six-celled embryo. 
11. Older six-celled embryo with the upper two tiers of cells stained 
much darker 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. 
16. Fifteen-celled embryo with octants at the tip and seven suspensor 
cells. 
17. Same stage as the preceding, the octants cutting off the primary 
dermatogen. 
18. Twenty-two-celled embryo with primary dermatogen complete, the 
normal embryo at this stage has twenty-three cells. 
19. Embryo with the 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 embryo with ten-celled suspensor. 
23. Somewhat later stage showing rapid multiplication of the upper der¬ 
matogen cells. 
24. Embryo showing division of the basal embryo cell and origin of the 
third tier in the embryonic sphere. 
25. Typical embryo at time when the lower two embryo cells are ready 
for further development. 
2(4. Same stage as the preceding but somewhat one-sided in develop¬ 
ment and with a different number 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 embryo 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 begin to curve. 
36. 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 embryo. 
