2 The Ohio Naturalist. [Vol. VII, No. 1, 



The egg apparatus of Bursa is well organized and after fer- 

 tilization the oospore elongates considerably and divides 

 by a transverse wall into two cells of unequal size (Figs. 1-5). 

 The basal cell does not divide again but begins to enlarge 

 rapidly, finally developing into a large vesicular cell which is 

 closely surrounded by the upper part of the wall of the ovule 

 and continues in an active condition until the seed ripens. 

 The upper cell divides by a transverse wall giving rise to a 

 proembryo of three cells, the terminal cell, an intermediate 

 cell, and the basal vesicular cell (Fig. 6). The next division is 

 again transverse and probably takes place in the intermediate 

 cell (Fig. 7 ) . After a filament of four cells is produced, the apical 

 or terminal embryo cell divides by a longitudinal wall, giving 

 rise to the typical five-celled embryo (Fig. 8). The following 

 division occurs in the suspensor cell next to the vesicular cell, 

 resulting in a six-celled embryo with five tiers (Figs. 9-11). 

 Often the cell below the two terminal embryo cells stains dark 

 like them while the three suspensor cells take a much lighter 

 stain (Figs. 10,11). This would indicate that this cell is the 

 second cell of the embryo proper and that it does not contribute 

 to the further development of the filamentous suspensor until 

 its division at a much later stage. This point was, however, 

 not determined. The two terminal cells now divide by longitu- 

 dinal walls at right angles to the previous division giving rise to 

 the terminal quadrants while further transverse divisions occur 

 in the suspensor (Figs. 12-15). 



At the time when the terminal quadrants divide by transverse 

 walls to form the octants, the suspensor usually consists of the 

 vesicular cell and six intermediate cells (Figs. 16-20) and this is 

 frequently the extent of this organ though more commonly there 

 are seven or eight intermediate suspensor cells developed. The 

 cotyledonary and hypocotyledonary rgeions of the embryo are 

 definitely separated by the divisions which give rise to the oc- 

 tants. The octants soon cut off dermatogen cells by periclinal 

 walls thus producing a nearly spherical body of sixteen cells 

 (Figs. 17, 18). The periclinal divisions which give rise to the 

 dermatogen appear first in the terminal octants (Fig. 17). At 

 this stage the proembryo consists typically of twenty-two or 

 twenty-three cells. While the deraiatogen cells are continuing 

 their divisions by anticlinal walls the eight inner cells divide by 

 longitudinal walls and the cell between the suspensor pro]XM- and 

 the terminal sphere divides by a transverse wall into the basal 

 embrvo cell and a very flat disk-like suspensor cell which takes 

 no part in the development of the embryonic tissues (Fig. 19). 



The primary dermatogen begins its further development in 

 the outer quadrants of cells and as would be expected the divi- 

 sion in these cells is more active during the further growth of 



