STUDIES IN THE DEVELOPMENT OF THE PIPERACEAE 725 
as it does in P. medium (Johnson '02, figs. 5, 11, 14). A striking 
feature in the rate of growth of the integuments in P. betel is 
the inequaUty in rate of growth on the different sides of the ovule. 
That this difference is very considerable is evident from many 
longitudinal sections of the ovule (figs. 44, 54). The minor irreg- 
ularities are still more clearly shown by the study of a series of 
successive transverse sections, such as are shown in figs. 38 to 
43. This series shows that the inner integument has two dis- 
tinct lobes, while the outer one has at least four. The longest 
lobe of the outer integument is pushed up tightly against the 
lower end of the stylar canal (figs. 44, 54). 
In the ripe seed, the outer integument is made up of four or 
five layers of thin-walled cells (fig. 61). The inner integument 
forms the chief seed coat. It consists of three or four layers of 
cells throughout most of its extent. The innermost of these is 
slightly thickened and brownish in color, while the outermost 
layer has its outer walls greatly thickened by a granular deposit 
against their inner surface (fig. 68). 
The escape of the seed from the fleshy spike, and the germina- 
tion have not been seen. It is hoped that these will be found in 
material to be collected this spring. 
The embryo-sac arises from the single, hypodermal, sporogen- 
ous cell in each ovule. This cell cuts off a thin parietal cell at 
the micropylar end, which may form six or seven layers of tapetal 
cells at the tip of the mature nucellus (figs. 52, 54, 57). The lower 
of the two descendants of the primary sporogenous cell enlarges, 
and finally develops directly into the embryo-sac (fig. 54). The 
first mitosis in the sac has not been seen, but when the two daugh- 
ter nuclei prepare for division (fig. 55), it is evident that only six- 
teen, the reduced number of chromosomes, is present. 
The four nuclei resulting from this second division of the em- 
bryo-sac may sometimes remain near the ends of the sac, where 
they are formed, or there may be a single nucleus at one end and 
three at the other (figs. 56, 58). Often, however, perhaps in half 
the cases seen, these nuclei may be closely grouped near the mid- 
dle of the embryo-sac (fig. 57). In these cases the nuclei are as 
closely grouped as the nuclei of a microspore tetrad. It is of 
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