

276 BOTANICAL GAZETTE [april 



to be moving along the side of the sac toward the egg. The polar 





nuclei are at first not as large as the other nuclei of the sac, but 

 before their fusion (fig. 46) they increase in size, each becoming 

 larger than the egg nucleus. Fusion takes place below the egg in a 

 plane either at right angles to (fig. 46) or parallel with (fig. 47) the 

 long axis of the sac. The 2 nucleoles persist in the fusion nucleus 

 until fertilization takes place. 



The embryo sac of E. splendens differs from that of E. Preslii 

 chiefly in the history of the antipodal cells, which in the latter 

 species persist for some time after their formation; another differ- 

 ence is that in E*. Preslii the polar nuclei remain in their original 

 positions until after cell division occurs. 



If fertilization does not occur immediately after the fusion of 

 the polar nuclei, the synergids disintegrate, leaving the egg and the 

 fusion nucleus close together at the micropylar end of the sac. In 

 2 embryo sacs in which fertilization was observed, the synergids 

 were disintegrating, but their nuclei were still recognizable as 

 dark-staining masses. In the sac shown in fig. 48, the pollen tube 

 has destroyed one of the synergids and discharged one male nucleus, 

 which may be seen in contact with the nucleus formed by the 

 fusion of the polar nuclei. The latter nucleus still shows 2 nucleoles 

 and is considerably larger than the egg nucleus. It has already 

 moved a little way toward the antipodal end of the sac. The male 

 nucleus also possesses 2 nucleoles and is crescent- shaped. The 

 second male nucleus is a dark-staining mass still in the pollen tube 

 and little more than its nucleole can be distinguished. It is about 

 to pass down to the egg nucleus, the tip of the tube being within the 

 cell membrane of the egg. Fig. 49 shows another pollen tube 

 which has not yet discharged its male nuclei. It contains densely 

 staining material which seems to be aggregated into several masses, 

 but no nuclei are distinguishable. The polar nuclei in this case 

 have not completely fused and the egg nucleus is in a resting stage. 

 The pollen tube could not be traced back into the micropyle in 

 either case, for only its tip seems to contain material that stains 

 densely. With the triple stain, the contents of the tip of the tube 

 always take up the safranin. Fertilization does not take place 

 at the same time in the 3 ovules within the same pistil. A pollen 



