(358) 
is entirely disorganized. The lower part appears quite nor- 
mal except for the breaking down of its cells along the 
median line. The ovule has now reached the dimensions of 
the ripe seed and the differentiation of its outer integument 
is well under way. 
Benincasa 
The formation of the archesporium proceeds in the usual 
way in Benincasa. ‘The ovules appear to be rounded eleva- 
tions upon the placental folds and when these lobes have be- 
come quite prominent the archesporium appears among the 
hypodermal cells at the apex of each lobe (jig. 108). The 
tapetal cells undergo few divisions before the sporogenous 
cell has become quite conspicuous (fg. z09). Divisions of 
the tapetal cells now follow until the spore-mother-cell be- 
comes deeply seated in the nucellus. The integuments make 
their first appearance about the time the sporogenous cell is 
formed and bear about the same relation to the other structures 
as in the previous cases. By the time the first division of the 
megaspore nucleus has been completed the conical nucellus 
is covered by the integuments. At this time the incipient 
embryo-sac may be found at the base of an axial row of from 
fifteen to twenty cells. 
The division of the spore-mother-cell was not observed. 
There is some evidence that such a division occurs in the 
appearance of what may be taken for the remains of non- 
functional spores. A black mass of what appears to be 
disorganized cells is plainly seen at the outer end of the 
young embryo-sac, but it soon disappears. It would seem 
also that it is again the lowermost of the series which becomes 
functional. 
n the same section of an ovary, if not upon the same 
placenta, there may be found embryo-sacs in various stages 
of development. Embryo-sacs of two, four and eight cells 
may be found. The appearance of some of these may be 
seen in figures 77o and zrz. In many cases the most con- 
spicuous element of the nucleus is its nucleolus which seems 
to embody all the chromatic substance present. Only in the 
