STUDIES IN THE DEVELOPMENT OF THE PIPERACEAE 717 
spore-mother-cells in the larger microsporangia (fig. 11). The 
development of the tapetum and tetrads of microspores shows no 
unusual features. The ripe microspores are spherical, 7-9m in 
diameter, with a smooth outer wall. They are at this time 
unicellular, but have two nuclei. When the nuclei are first 
formed, a delicate evanescent wall is visible between them. One 
of the cells thus formed is about twice as large as the other (figs. 
18, 19). 
The wall of the anther is three cells in thickness, except at the 
top, where it may be but two, outside the tapetum. The opening 
of the anther for the escape of the pollen is a slit or gap, which 
is terminal to the stamen and longitudinal to the spike (fig. 45). 
With the ripening of the microspores, the stalk of the stamen 
elongates considerably and pushes the opening anthers out beyond 
the bracts. The bracts, meantime, have been separated markedl}^ 
by the increase in thickness of the axis (figs. 33, 45). 
The most interesting peculiarity of the stamens of Piper betel 
is the variability in the degree of development attained by the 
stamen as a whole, and by its sporangia. This phenomenon 
occurs in Satureia, as is briefly noted by Correns ('08, p. 667). 
Often one of the two stamens of a male or hermaphrodite flower 
in P. betel, is much smaller than the other, as may be seen from 
a surface view, or section of the spike (fig. 13 at x). Not in- 
frequently one of the stamens of an hermaphrodite or male flower 
is reduced to a sterile stalked knob, or mere peg, without a trace 
of a microsporangium in it (figs. 32, 34). In all female flowers, 
of both female and hermaphrodite spikes, both stamens are re- 
duced to this latter condition (fig. 32). 
In the hermaphrodite flowers of Piper betel monoicum, the ap- 
pearance of the stamens and ovules in section indicates that both 
are functional in the same flower. If this be true, the plants 
should be spoken of as polygamous, rather than monoecious. 
If we now consider the stamens which do bear microsporangia, 
we find that the number and extent of these sporangia differ 
greatly in different stamens, or even in the same stamen. A count 
of the sporangia in 225 stamens, from five spikes with hermaph- 
rodite flowers and five with male flowers, showed that only 13^ 
