88 Oliver . — On the Structure , Development , 
give rise to two cells, one above the other. The very thick 
integument now closes over the free end of the nucellus. 
There is, as is customary in Monopetalae, only one integument 
formed. The closure of the integument is very complete, and 
the micropyle is reduced to a mere line (m in Fig. 27). 
Indeed in some cases I could detect no trace of this even (as 
in Fig. 26), and without proper developmental stages, the 
ovule might easily have been judged to be a naked one. 
The cell which is cut off from the archesporal cell lies, not, 
be it noted, as is usual, at the micropylar, but at the 
opposite end of the embryo-sac mother-cell. This first cell (c 
in Fig. 24) is sister- cell to the embryo-sac mother-cell, and 
divides by a horizontal wall into two cap-cells ( c 2 and c 3 in 
Figs. 25-28). The embryo-sac mother-cell itself also divides, 
and a new cap-cell (c 1 in Figs. 25-28) is cut off, lying between 
the embryo-sac and the two lower cap-cells. There is now a 
row of four cells, the uppermost of which is the embryo-sac (as 
in Fig. 25). In one case only did I find an exception to this 
state of things. In this, not the top, but the second cell of the 
row, became the embryo-sac ; it thus had one cap-cell above 
and two below it. 
By the succeeding growth of the ovule, the embryo-sac 
comes to lie very deeply, approaching very nearly the lower- 
most tip of the ovule (Fig. 19). No raphe whatever is 
developed ; the vascular bundle ends abruptly at the insertion 
of the ovule (Figs. 19, 31, 32, 36). There can, however, be no 
doubt as to the base of the embryo-sac being, theoretically, 
the chalazal end. 
In early flowering stages are found, the three cap-cells (e 1 , 
c 2 , c 3 , Fig. 25) of fairly equal height, and the embryo-sac, 
above, fairly rectangular in form ; in slightly older stages the 
topmost (Fig. 26) of the three cap-cells (c 1 ) becomes partially 
absorbed, and then the second of them (c 2 , Fig. 27). The 
terminal cell (e 3 ) always increases in length, at first at the 
expense of c 1 and c 2 . The walls of the embryo-sac and of 
these cap-cells are highly refringent and deliquescent, as is 
usually the case. In each cap-cell is a large, round nucleus. 
