Studies on the Binucleate Phase in the Plant-cell. 9 



Figs. 17-20. — Hippuris vulgaris L. Axis gathered May 8, 1916. 



Fig. 17.— Cortical cell, with nucleus preparing to divide. 



,, 18. — Cortical cell, with nuclear spindle, showing chromosomes at the poles. 



,, 19.— Cortical cell, with phragmosphere and paired nuclei. 



^, 20. — Endodermal cell, with phragmosphere and paired nuclei. 



Figs. 21-2i.—HeUa7ithus Nuttallii Torr. and Gray. 



Fig. 21.— One pith cell with two nuclei, one of which is degenerating, at 3 cm. 



from the apex of a shoot gathered June 9, 1915. (To economize 



space the outline of the cell is not completed.) 

 ^, 22. — The nucleus of a pith cell between 4 and 5 cm. from the apex. 

 „ 23. — A nucleus of a pith cell 1 cm, from the apex. 

 ,, 24. — Two nuclei from one pith cell between 5 and 6 cm. from the apex of a 



young shoot gathered May 23, 1916. 



Figs. 25, 26. — Polygonum cuspidatum Sieb. and Zucc. 



Fig. 25. — Nucleus of a stem parenchyma cell preparing to divide. 

 ,, 26. — Phragmosphere with paired nuclei in a stem parenchyma cell. 



Figs. 27, IQ'.^Asparagus officinalis L. 



Fig. 27. — Progressive wall formation in ground tissue cell. 

 „ 28. — Quadrinucleate ground tissue cell. 



Figs. 29-S2.—Elodea canadensis Michx. Gathered June 2, 1916. 



Fig. 29.— Cortical cell, with nucleus in process of division, showing chromo- 

 somes. 

 „ 30. — Cortical cell of stem, with phragmosphere. 

 ,, 31. — Epidermal cell of stem, with phragmosphere. 

 ,, 32. — Lobed nucleus from cortical cell. 



Figs, 33-37. — Hemerocallis fulva L. 



Fig. 33. — Cell of ground tissue, with one normal and one degenerating nucleus, 



from the axis just below a young inflorescence. Gathered May 24, 



1916. 

 ,, 34. — Cells of the outer epidermis of the basal part of a leaf gathered 



January 28, 1916 ; seen in tangential section, showing the lobed 



nuclei. 

 ,, 35. — Other lobed nuclei, from the same epidermis as fig, 34. 

 Figs. 36 A, B.— Pairs of nuclei, in each case one normal and one degenerating, 



from two adjacent ground tissue cells of the axis just below a young 



inflorescence, gathered May 24, 1916. 

 Fig. 37. — Pair of nuclei from one ground tissue cell of the axis just^ below 



another young inflorescence, gathered May 21, 1916. As in figs. 



36 A and B, one nucleus is. normal and the other degenerating. 



Fig. Z8.—Alisma Plantago L. 



Cell from the lacunate mesophyll of a young petiole, gathered 

 May 5, 1916, showing a phragmosphere with paired nuclei. 



Figs. 39 A, B.—Monstera deliciosa Liebm. 



Fig. 39 A,— Cell of inner cortex of aerial root, gathered October 20, 1916, showing 

 phragmosphere and paired nuclei. 

 „ 39 B.— Lobed nuclei from conjunctive tissue of stele of aerial root, gathered 

 November 26, 1915 ; 4 to 5 mms. from root apex. 



