ro Campbell . — The Development of the Flower and 
to nourish the developing spores. A similar disintegration 
of part of the sporogenous tissue has been observed by the 
writer in Z annichellia , and is very much like what takes place 
in Equisetum. 
The sporogenous cells after separation are imbedded in a 
nucleated mass of protoplasm derived from the tapetal cells 
and the imperfect sporogenous ones (Fig. n). As in most 
Monocotyledons the spores are of the bilateral type, i. e. there 
are two complete successive cell-divisions of the pollen- 
mother- cell. The spores do not long remain united in tetrads, 
but separate completely and assume an almost perfectly 
globular form. The young spore contains but a single nucleus, 
but there is later a division into two cells of very unequal size. 
The ripe spore (Figs. 12-14) shows a double wall, the outer 
one marked with fine reticulations, the inner one being 
the delicate endospore. The spore before maturity contains 
very little granular contents, but these increase rapidly as the 
spore ripens. The exact nature of the reserve substances 
in the ripe spore was not investigated. The structure of the 
anther-wall (Fig. 13) is of the usual type. 
The nuclei of the two cells in the germinating spore are 
very different in appearance. That of the large vegetative 
cell (Fig. 12, v) is large, with but little chromatin and a large 
nucleolus. The nucleus of the small generative or antheridial 
cell (g), on the other hand, is small, staining strongly and 
having an inconspicuous nucleolus. No indication of a further 
division of the antheridial cell, such as occurs in many Mono- 
cotyledons, was seen, although it is almost certain that this 
does occur in the pollen-tube after germination. 
The Female Flower. 
The homologies of the two pistillate flowers which usually 
occur near the base of the shaft of the inflorescence are not 
entirely clear, but they probably represent shoots of the same 
nature as the innovations which occur in the larger plants, 
in addition to the shoots formed in the axils of the leaves. 
