152 MINNESOTA BOTANICAL STUDIES. 



Plate X. 



12. EmbiTO sac of Riimex salicifoUus showing the two nuclei as 

 above and the lower one also slightly larger. 



13. Embryo sac of Rumex salicifoUus showing the four nuclei de- 

 rived from division of two corresponding to those figured in 1 1 and 12, 

 and also showing the persistent spindle in the anterior end of the sac. 



14. Embryo sac of Rumex salicifoUus showing the corresponding 

 four nuclei in a somewhat older sac. 



15. Embryo sac of Rumex salicifoUus showing eight nuclei derived 

 from four corresponding to those figured in 13 and 14. The polar 

 nuclei are approaching each other. The three anterior nuclei are of 

 about equal size and not enclosed in walls. Only the nucleoli of the 

 antipodals could be seen. 



16. Embryo sac of Polygonutn erectum showing the earlier forma- 

 tion of cell walls about the anterior nuclei, one of which was lying be- 

 low the other two. The polar nuclei are approaching each other, and 

 the cellular structure in the antipodal area is distinct, one cell here also 

 lying below the other two. 



17. Embryo sac of Rumex salicifoUus showing the ^^^ yet free, 

 cell walls forming about the synergida;, the polar nuclei fusing and 

 three distinct nucleated antipodal cells. 



18. Embryo sac showing the sister nuclei which form the synergidte 

 yet free and the wall forming about the g.^^ after the definitive nucleus 

 is formed. 



19. Anterior end of a mature embryo sac showing the synergidae 

 and the q^%. 



20. Embryo sac of Ru7nex salicifoUus showing all of the nuclei of 

 the mature sac, except the antipodals and at about the same stage as 

 the corresponding nuclei in 17. 



21. Posterior end of a mature embryo sac showing three antipodal 

 cells. 



22. Anterior end of the embryo sac of Rumex salicifoUus showing 

 walls forming about the egg after the definitive nucleus is formed. 



23. Mature embryo sac showing more than three nuclei in the anti- 

 podal end. 



24. Mature embryo sac of Rzcmex salicifoUus^ with the antipodal 

 region perhaps not distinctly seen. 



Plate XI. 



25. Anterior end of embryo sac showing one synergid degenerated, 

 the pollen tube entering and showing two nuclei very indistinctly. 

 The &^'g and definitive nucleus are also shown. 



26. Anterior end of embryo sac showing a pollen tube discharged 

 and containing an undischarged sperm-nucleus. The two synergidae 



