26 
2°. The omission of cellwall formation and its consequences for 
the number of nuclei in the mature embryosac. — 
Omission of cell walls during megaspore-formation is of rather 
common occurrence in Angiosperms. It results in two, three 
or four megaspores lying in the same cell. Of course this omis- 
sion is not confined to those cases in which a “row of four* is 
formed (fig. 3 A). Megaspore-formation. of the type B and C may 
be affected as well. Fig. 4 presents a fully worked out scheme > 
of: all farther possibilities. : 
Four megaspores are formed (Type A), 
1°. Cell wall-formation is omitted in the second division only. — 
Thus two nuclei are met with in the same cell. Kither one of 
these may develop and the other desintegrate (fig. 4 Az) or both 
of them may function (fig. 4 AA). The first should be in accor- 
dance with the normal development, giving rise to an embryo- 
sac of eight nuclei at most. The second however is still far 
from improbable for both nuclei, lying in the same cell, have 
got almost equal: chances. 
2°. Cell wall-formation is omittéd in both divisions. Four me- 
gaspores are found in the same cell. For reasons just mentioned 
we might expect either one of these to develop (fig. 4 Ay) oF 
all four (fig. 4 AAAA), which whould mean a really “tetraspo- 
rical* sac capable of becoming 32-nucleate, when fully developed. 
For completeness’ sake two more possibilities are figured, 
resp. showing two functioning (fig. 4 AA #) and three functioning 
(fig.4 AAA @) megaspore nuclei. Their realisation however does 
not seem very probable. 
Three megaspores are formed (Type B). 
1°. Cell wall-formation is omitted in the second division only. 
Two nuclei in the same cell, either one (fig. 4 Ba) or both 
(fig. 4 BB) developing. : 
2°. Cell wall- -formation is omitted in both divisions. Three me- 
gaspores should be found in the same cell. This however must 
be considered utterly-improbable, for it can hardly be expected, 
