g
the suckers (_h_) by which the filaments are attached to the leaf.
_A_, surface view. _B_, vertical section of the leaf, x 300.]

The spore fruits, as already observed, are formed toward the end of
the season, and, in the species under consideration at least, appear
to be the result of a sexual process. The sexual organs (if they are
really such) are extremely simple, and, owing to their very small
size, are not easily found. They arise as short branches at a point
where two filaments cross; one of them (Fig. 39, _C_, _ar._), the
female cell, or "archicarp," is somewhat larger than the other and
nearly oval in form, and soon becomes separated by a partition from
the filament that bears it. The other branch (antheridium) grows up
in close contact with the archicarp, and like it is shut off by a
partition from its filament. It is more slender than the archicarp,
but otherwise differs little from it. No actual communication can be
shown to be present between the two cells, and it is therefore still
doubtful whether fertilization really takes place. Shortly after
these organs are full-grown, several short branches grow up about
them, and soon completely envelop them (_D_, _E_). These branches
soon grow together, and cross-walls are formed in them, so that the
young spore fruit appears surrounded by a single layer of cells,
sufficiently transparent, however, to allow a view of the interior.

The antheridium undergoes no further change, but the archicarp soon
divides into two cells,--a small basal one and a larger upper cell.
There next grow from the inner surface of the covering cells, short
filaments, that almost completely fill the space between the
archicarp and the wall. An optical section of such a stage (Fig. 39,
_F_) shows a double wall and the two cells of the archicarp. The
spore fruit now enlarges rapidly, and the outer cells become first
yellow and then dark brown, the walls becoming thicker and harder as
they change color. Sometimes special filaments or appendages grow
out from their outer surfaces, and these are also dark-colored.
Shortly before the fruit is ripe, the upper cell of the archicarp,
which has increased many times in size, shows a division of its
contents into eight parts, each of which develops a wall and becomes
an oval spore. By crushing the ripe spore fruit, these spores still
enclosed in the mother cell (ascus) may be forced