136 BOTANICAL GAZETTE [AUGUST 
Fic. 19. Generative cell immediately after division. X 800. 
Fic. 20. Pollen tube with three nuclei. X 280. 
1G. 21. Central and stalk cell of same tube more magnified ; stalk cell 
protoplasm beginning to merge into that of pollen tube. x 800 
Fic. 22. All three nuclei moving down, and close ewethiex 
Fic. 23. Pollen tube slightly older; stalk nucleus has ee central 
cell and lies by tube nucleus from which it differs in its smaller size; May 15, 
Igoo. X 400, 
PLATE 11. 
Fic. 24. More developed pollen tube; stalk and tube nuclei alike. x 
Fig. 25. Tip of ovule; ne tube has reached megaspore in which no 
cell walls have yet formed. 
Fic. 26. Tip of pollen en that has reached the prothallium ; nuclei in 
usual position, x 400 
Fic. 27. Central oail of pollen tube shortly before division; one free 
nucleus shown. X 800 
Fig. 28. Central cell (cone to divide; free nuclei and protoplasm of 
pollen tube disorganizing. x 
FG. 29. Spindle of dees of central cell. x 800. 
Fic. 30. Telophase of the same. X 400. 
Fig. 31. Sperm cells separated from each other. X 400. 
PLATE fil. 
Fig. 32. Megasporophyll with the axillary megasporangium rudiment 
just esi dl to show; Oct. 3, 1899. X 
The same; integument beginning to appear; Jan. 4, 1990. 
X 95. 
Fic, 34. Little older megasporophyll and ovule; March 11, 1900, Balti- 
more, X 95. 
Fic. 35. The same; ready for pollination; megaspore mother-cell not 
yet divided; March 31, 1900. x 80. 
G. 36. Longitudinal section of sporangia and sporophyll ten days after 
maces placenta now beginning to appear above the ovule; April 3, 
Igol. 
— 37. renee and ovule about three weeks after pollination; 
pyle cl and placenta becoming prominent; ie ae 22, I9gQ0. X 30. 
Fig. 38. Megaspore mother-cell before division. x 800 
Fic. 39. The same; in synapsis. X 1030. 
Fic. 40, The same; spindle of first division. X 950. 
Fic. 41, The same; older spindle of first division. x 950. 
Fig, 42. The same; wall being formed. Xx 9 
Fic. 43. The same; spindle of second aa sti * 950. 
Fic. 44. Megaspore with the two disorganizing spores above. X 950. 
