(345 ) 
upper cells disorganize and may be seen in later stages as a 
dark mass overlying the young embryo-sac (jig. 47). The 
development of the parts of the ovule keeps pace with that 
of the internal structures and when the condition represented 
by figure 46 is reached, the inner and outer integuments have 
overtopped the nucellus, the former thin and composed mostly 
of two layers of cells, the latter thick and showing some dif- 
ferentiation of vascular tissue. 
An embryo-sac of two cells is shown in figure ¢7 and 
the subsequent stages, and as growth of the cell proceeds, 
vacuolization follows to a large extent. After the first 
division the two resulting nuclei are separated to opposite 
ends of the embryo-sac by the large vacuole (jg. 47), and 
the nuclei resulting from subsequent divisions are similarly 
disposed (jig. 78). Inthe preparation represented by figure 
48 the earlier steps in differentiation were visible. The syn- 
ergids, odsphere and upper polar nucleus were easily dis- 
cernible. In the antipodal region not so much difference 
was visible but the polar nucleus appears the most conspicu- 
ous of them all. The definitive embryo-sac has some charac- 
ters in common with those previously described. The syn- 
ergids are slender, pointed at the upper ends and vacuolated 
in the broader, lower portion. As in other cases the upper 
portion bears a hyaline striated aspect. The odsphere is 
somewhat more conspicuous than in many other cases and 
the polar nuclei less so. The antipodals remain quite evi- 
dent up to this time. Figure g9 represents a condition in 
which the polar nuclei are in contact but not united. The 
complete fusion of these was not observed. At the stage rep- 
resented by figure 79, which is prior to fertilization, the 
embryo-sac is packed with starch which persists until some 
time after fertilization (fig. 5 
The ovule at the time if Tie is eblong in form, 
its length being approximately three times its broadest diam- 
eter. Not until fertilization has been accomplished is the 
