1908] BROWN—PEPEROMIA 449 
and that the second division completes the longitudinal separation 
begun in the first. 
The first two divisions differ from those in P. pellucida in that there 
are formed evanescent walls separating the daughter nuclei. When 
the daughter nuclei of the first division have begun to be organized, 
an equatorial plate is formed on the spindle (fig. 17). This grows 
until it becomes a wall stretching across the embryo sac (jig. 18). 
The plane of this wall is not constant, but it may extend longitudinally 
or transversely across the sac, or take any intermediate position, and 
may also separate the sac into equal or unequal parts (figs. 18-20). 
It persists only for a short time, disappearing before the next division 
or remaining as a remnant after it (fig. 21). There is no trace of it 
_ later in the four-nucleate stage. When the two nuclei divide to four, 
plates are formed on both spindles. One of these never becomes 
very prominent, but the other forms a wall separating one nucleus 
from the other three (fig. 22). The position of this wall is variable, 
as was the one in the two-nucleate stage. It may cut off a nucleus 
at either end or any side of the sac, but generally it appears at the 
lower end. This wall, like the first, persists for only a short time. 
It generally disappears before the next division (fig. 23), but may per- 
sist as a remnant after it. As in P. pellucida, the four nuclei assume 
the position of the nuclei of a tetrad of microspores. The walls just 
described are apparently megaspore walls. This, however, will be 
discussed later. 
In the next two divisions all of the nuclei divide simultaneously, 
giving eight, and then in the mature sac sixteen nuclei. The nuclei 
of the eight-nucleate stage and of the mature sac are arranged about 
the periphery of the sac (figs. 24-28). As in P. pellucida (JOHNSON 
00), one of the sixteen nuclei becomes an egg, another has the position 
of a synergid, six are cut off singly against the wall and finally degen- 
erate, while eight fuse to form the endosperm nucleus. Fig. 29 shows 
a sac in which fertilization is taking place. Four of the peripheral 
nuclei are shown, while five others are fusing to form the endosperm 
nucleus. One of these latter was probably formed by the fusion of 
two. The other two fusing nuclei, as well as two peripherals, are 
in another section. 
In the division of the four nuclei to eight no colt plates are formed. 
