1897 ] STAMENS AND CARPELS OF TYPHA LATIFOLIA 95 
g). While the pollen mother cells are growing and forming the 
tetrads, the tapetal cells increase greatly in size, and the nucleus 
of each cell usually divides into two. Toward the end of this 
process the layer between the tapetum and the endothecium 
breaks down, and the enlarged endothecial cells are multi- 
nucleate (fig. ro). ’ 
The multinucleate condition is also quite normal in the 
peculiar stellate cells of the leaves (fig. zz). From such 
appearances it might be inferred that the multinucleate con- 
dition stands in some relation to the increase in the volume of 
the cell. 
After the tetrads are formed, the tapetal cells disintegrate, 
and at the same time the endothecial cells begin to acquire 
their characteristic thickenings (jigs. 12-14). At the points 
where dehiscence is to take place no thickenings are developed 
(jig. 73). As appears from the mode of development, the 
stamen clusters do not represent a coalescence of filaments, 
but are cauline in origin. Sometimes as many as five or more 
stamens branch thus from a common axis. The hairs of the 
staminate spike are not situated on the stamen clusters, but 
directly on the axis (fig. r5). They are multicellular, and ina 
cross section usually from fifteen to twenty cells can be counted 
(figs. 16, 7%. 
DEVELOPMENT OF THE MALE. GAMETOPHYTE. 
After the pollen mother cells have separated, the tetrads 
are formed by three usually successive divisions (figs. 28-20). 
The microspores, as is well known, do not separate, but begin 
immediately to develop very thick cell walls (fig. 27). The 
tetrad pollen grains are often irregular in shape, and do not 
form a typical tetrad (fig. 22). Such forms are no doubt pro- 
duced by a partial separation of the spores. When the spores 
germinate the two nuclei are about the same size (fig. 22), but 
later the vegetative nucleus increases in size and the generative 
nucleus sinks to one end of the pollen grain and organizes a 
definite cell, being cut off from the rest of the grain by a very 
