1897 | THE LIFE HISTORY OF SAGITTARIA VARIABILIS 271 
Fic. 31. A little later stage than fig. 70, the sexual nuclei are in con- 
tact, and two pairs of centrospheres appear above and below; one of the 
synergids lies in front of the tube, the other has disappeared. X 1125. 
FiG. 32. Upper end of embryo sac after fertilization, with large spherical 
oospore nucleus, and pollen tube containing the remaining sperm nucleus. < 
1125 
FIG. 33. Oospore beginning to descend; the pollen tube is beginning to 
disappear ; above the oospore lies the remaining synergid. X 600 
Fic. 34. A cell from the tip of a young embryo with nucleus in the 
daughter skein stage : two large centrospheres at each pole. X 850. 
PLATE XXII, 
Fic: 36. Upper end of embryo sac with oospore and synergid. 400. 
Fig. 36. Embryo sac with a two-celled pro-embryo; two endosperm nuclei 
separated by a distinct cell wall stretching across the sac, and three antipodal 
cells. X 400. 
Fic. 37. Lower end of embryo sac, a little later than fig. 76, showing 
the seas of the first two endosperm cells and the cell wall between them. 
x 4 
Fie. ae Embryo sac with a two-celled pro-embryo and two endosperm 
cells separated by a cell wall. « 400. 
Fig. 39. About the same stage as fig. 38; the upper endosperm nucleus 
is dividing. 260. 
Fic. 40, Lower end of an embryo sac which contains a nine-celled pro- 
embryo; the upper endosperm nucleus has divided into many free cells while 
the lower remains undivided ; at the base two antipodals. < 400. 
Fig. 41. Complete embryo sac with a nine-celled pro-embryo containing a 
number of comparatively small free endosperm nuclei; the endosperm 
nucleus below the partition wall has divided into two nuclei which have 
greatly enlarged; two antipodals appear at the lower end of the sac. X 66. 
Fig. 42. Lower end of an embryo sac containing a ten-celled pro-embryo ; 
the lower endosperm nucleus has divided into two; the antipodal — with 
very thick walls retaining its original size and contour. X 216. 
- Fre. 43. Lower end of an embryo sac in which the lower endosperm ee 
nucleus has divided into three. 400. 
FrG. 44. Lower end of an embryo sac with embryo at the stage repre- — 
sented i in Fg. Jas the antipodal region bed still ee —- the te : Z ie . 
a ee ine ans, for some ——e : 
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