'- = “eee 
1907] CAROTHERS—GINKGO BILOBA 129 
Fic. 4. Vertical section of a single ovule; May 1, 1905. X12 
Fic. 5. kos section through sporogenous mass with spate mother cell; 
May 1, 1905. 
Fic. 6. Se ection through sporogenous mass with two mother cells; 
May 1, 1905. X325. 
Fic. 7. Young mother cell; May 1, 1905. 650. 
Fic. 8. Mature mother cell, showing vacuoles and kinoplasmic mass; May 
I, 1905. X650. 
Fic. 9. Mother cell in synapsis; May 1, 1905. X650. 
Fic. ro. Mother cell just after synapsis, showing the eight chromosomes 
already divided for the heterotypic division, aaa the spindle fibers in the cyto- 
plasm; May 1, 1905. 650. 
Fic. 11. Mother cell showing oblique spindle of heterotypic division; May;1, 
1905. 650. 
Fic. 12. Mother cell showing oblique division; May 1, 1905. 650. 
Fic. 13. First division of mother cell completed; May 1, 1905. 650. 
Fic. 14. Lower cell showing spindle of homotypic division; upper cell pre- 
paring for division; May 1, 1905. 650. 
15. Division of lower cell completed; May 1, 1905. 650. 
Fic. 16. Incomplete tetrad; upper cell failing to divide; May 1, 1905. X650. 
Fic. 17. Linear tetrad; lowest cell via May 1, 1905. 650. 
Fic. 18. Bilateral tetrad; May 1, 1905. 650. 
19. Combination linear and bilateral tetrad; wall failing to appear in 
upper cell after vertical division of nucleus; May 1, 1905. 650. 
Fic. 20. Vertical section of a sixteen-nucleate sac and tapetum; May 18, 
1905. X225. 
hry 
m 
- 
_ 
— 
i 
PLATE VI 
Fic. 21. Portion of sac showing spindles of free nuclear division in slightly 
different phases; May 18, 1905. 50. 
Fic. 22. Portion of embryo sac showing granular cytoplasm, free nuclei, and 
cE tapetal cells encroaching upon nucellus; June 5, 1905. 650. 
G. 23. Face view of plasmic sac with free nuclei; June 5, 1905. 650. 
a 24. Portion of embryo sac showing absorption of tapetum; free nuclei 
in different conditions; and a cell wall developed upon the outer surface of the 
plasmic sac; June 20, 1905. 650. 
Fic. 25. Section of nameeree? — 2a om walls fastened to outer 
membrane which sac; July in 1905. X325. 
Fic. 26. Peciliar case of wall formation; June ia 1905. x6 
Fic. 27. Open cell from inner end of centripetally pices row; July 19, 
1905. X325. 
Fic. 28. Open inner cell with two nuclei; July 28, 1905. 325. 
Fic. 29. Binucleate cell from prothallial tissue; July 28, 1905. X 325. 
