622 Wisconsin Academy of Sciences, Arts , and Letters. 
In many preparations, in which the cytoplasm of the embryo- 
sac had shrunken away from the nucellar wall at the outer end 
a fairly accurate distinction could be made between the cells of 
the embryo-sac proper and those of. the nucellus (Figs. 46 
and 47). From these preparations it seems clear that part or 
all of the three micropylar embryo-sac nuclei undergo an early 
degeneration. Occasionally a larger cell persists in the cyto¬ 
plasm of the embryo-sac which may possibly be the egg. Other 
preparations show all three cells degenerated which may indi¬ 
cate that a large cell persisting in the embryo-sac is simply 
one which has resisted degeneration longer than the other two 
(Figs. 48 and 49). 
As above mentioned some of the rounded isolated nucellar 
cells at the micropylar end of the nucellar cavity become gradu¬ 
ally absorbed. Others retain their plumpness and increase in 
size, some of them becoming considerably vacuolated. These 
proceed to form adventitious embryos. At a period before the 
fusion of the polar nuclei some of these rounded cells which are 
of undoubted nucellar origin, are seen to be dividing (Fig. 48). 
Apparently not all of these nuclei divide at such an early stage 
but certainly some divide before there is any possibility of fer¬ 
tilization having occurred. The nuclei of others of these nu¬ 
cellar cells seem to remain undivided often until after the fu¬ 
sion of the polar nuclei and the first division of the resulting 
endosperm nucleus. 
Commonly these divisions take place in isolated cells, or at 
least in rounded cells which though lying near one another, 
seem to remain perfectly independent. The cell masses re¬ 
sulting from the division of these neighboring rounded cells 
seem to remain separate from one another, suggesting that each 
mass may ultimately form an embryo. Still in cases where 
some of a mass of cells were observed to be dividing it was of 
course impossible to determine whether the mass had resulted 
from the division of one or more than one cell. The frequent 
large solitary dividing nucellar cells suggest very strongly that 
in many instances at least, these adventitious embryos are de¬ 
rived from a single sporophytic cell. 
