144. Fisuer: SEED DEVELOPMENT IN THE GENUS PEPEROMIA 
of the endosperm nucleus, and consequently the number of 
peripheral nuclei left over, may vary to a greater extent than to 
the limits observed. The endosperm nucleus is formed in essen- 
tially the same manner as that of P. pellucida (Johnson, 30). 
The embryo sac evidently enters upon a resting stage after 
four nuclei are formed and before these divide into eight. This is 
indicated by the fact that a much larger proportion of four-nucleate 
sacs were found in the preparations than of two-nucleate or eight- 
nucleate sacs. A number of slides, containing all stages from the 
definitive archesporial cell to the mature embryo sac, were carefully 
examined, and an accurate count made to determine this propor- 
tion, with the following result: six two-nucleate sacs, thirty-five 
four-nucleate sacs, and seven eight-nucleate sacs. The significance 
of this relation will be considered in the general discussion. 
In nearly all the cases which were at a stage where this could 
be determined, it was observed that the endosperm nucleus divides 
before the male nucleus actually fuses with the nucleus of the egg 
(Fics. 13, 14). In most instances, however, the male nucleus 
was present in the egg, where it usually remained for a consider- 
able time before fusing with the egg nucleus. The presence of 
the male nucleus in the embryo sac may produce a stimulus which 
causes the endosperm nucleus to begin its development. This 
would seem to be in accord with Czapek’s (15, p. 127) statement 
that the swelling of the ovary, in plants, after pollination, is 
caused by certain soluble substances (hormones) emanating from 
the pollen. The first division of the endosperm nucleus and all 
subsequent divisions of the resulting endosperm nuclei are mitotic, 
as is shown by the presence of typical spindles, etc. It is true 
that the equatorial plate is very broad in these spindles, a condi- 
tion probably correlated with the presence of the large number of 
chromosomes contributed by the six or eight constituent nuclei 
fusing to form the endosperm nucleus, but this was not determined 
by counting. 
Each division of the endosperm nucleus is followed by a cell- 
wall from the start, the first wall being parallel with the long 
axis of the fruit or nearly so (Fic. 13). The endosperm continues 
its development until, in the mature fruit, there is a mass showing 
about twenty-five cells in median longitudinal section (FIG. 16), 
