I70 The Ohio Naturalist. [Vol. IV, No. 8, 



compartments (Fig. 24), It seems that all three of the daughter 

 nuclei continue to divide until the whole sac is filled with endo- 

 sperm extending far down into the space formed by the dissolu- 

 tion of the tissue of the ovule below the base of the embryo-sac 

 (Fig, 27). The development of the endosperm, after the three- 

 celled stage, begins at the upper end, but there is no large vesicu- 

 lar cell developed at the lower end of the sac, as Cook reported 

 for Castalia odorata. At first the endosperm cells are quite 

 large, but as the division continues the cells become much smaller, 

 walls continue to be formed between the dividing nuclei until the 

 endosperm is fully developed, no free cell formation taking place, 

 so far as observed, at an}- stage of the process. 



The history of the embryo as followed is the same as reported 

 by Ivyon. After fertilization, the oospore continues to occupy 

 the same position as the oosphere and it enlarges somewhat before 

 it divides (Fig. 13). Although no two-celled embryo was ob- 

 served, it is evident that the first division of the oospore is b)' the 

 formation of a transverse wall. Then by the formation of a 

 longitudinal wall in each of the two cells, a quadrant is formed 

 (Fig. 23). Although this is the typical course of development, 

 very frequentl}^ the divisions are different. The lower cell often 

 divides by a transverse wall, thus forming a tier of three cells in 

 the proembryo (Fig. 22). By the formation of longitudinal walls 

 in the quadrant, the embr3-o passes into the octant stage. In 

 ca.se of a more irregular development, the three cells of the 

 embryo arranged in a row, divided by longitudinal walls, making 

 a .six-celled embryo (Fig. 25). Whether the early development 

 is typical or irregular, a series of divisions follows by which a 

 spherical embryo of .several hundred cells is formed (Figs. 26-29. ) 



No suspensor cell is present; so the j-oung embryo lies against 

 the nucellus at the micropylar end and is almost surrounded b}^ 

 endosperm tissue (Fig. 27). When the spherical embryo has 

 reached its maxinuun growth, it becomes flattened at the outer 

 end by the development of a collar-like ridge extending about 

 two-thirds of the way around (Figs. 30, 31 and 32). This is 

 followed by the outgrowth of a small protuberance from the flat- 

 tened side about parallel with the apex of the ovule. After the 

 formation of the crescent- shaped ridge, the development continues 

 at the opposite side, giving rise to the two "cotyledonar}' " lobes 

 of the embryo (Fig. 33 J. The two lobes grow downward very 

 rapidly outside the endo.sperm, the tissue of the ovule rapid]>- 

 disappearing before them. In the meanwhile, the endosperm has 

 formed a sac-like mass of tissue around the embryo and extends 

 down into the cavity of the embryo-sac to the disorganizing tissue 

 below. In the meantime the growth of the plumule has been 

 very slow, being a dome-shaped projection of tissue occupying a 

 central position between the lobes but to one side of the axis of 



