plants the ovules stand erect, and in others
they are suspended; and within the same ovarium of some few plants, one
ovule holds the former and a second ovule the latter position. These
positions seem at first purely morphological, or of no physiological
signification; but Dr. Hooker informs me that within the same ovarium
the upper ovules alone in some cases, and in others the lower ones
alone are fertilised; and he suggests that this probably depends on
the direction in which the pollen-tubes enter the ovarium. If so, the
position of the ovules, even when one is erect and the other suspended
within the same ovarium, would follow the selection of any slight
deviations in position which favoured their fertilisation, and the
production of seed.

Several plants belonging to distinct orders habitually produce flowers
of two kinds--the one open, of the ordinary structure, the other closed
and imperfect. These two kinds of flowers sometimes differ wonderfully
in structure, yet may be seen to graduate into each other on the same
plant. The ordinary and open flowers can be intercrossed; and the
benefits which certainly are derived from this process are thus secured.
The closed and imperfect flowers are, however, manifestly of high
importance, as they yield with the utmost safety a large stock of seed,
with the expenditure of wonderfully little pollen. The two kinds of
flowers often differ much, as just stated, in structure. The petals in
the imperfect flowers almost always consist of mere rudiments, and the
pollen-grains are reduced in diameter. In Ononis columnae five of the
alternate stamens are rudimentary; and in some species of Viola three
stamens are in this state, two retaining their proper function, but
being of very small size. In six out of thirty of the closed flowers in
an Indian violet (name unknown, for the plants have never produced with
me perfect flowers), the sepals are reduced from the normal number of
five to three. In one section of the Malpighiaceae the closed flowers,
according to A. de Jussieu, are still further modified, for the five
stamens which stand opposite to the sepals are all aborted, a sixth
stamen standing opposite to a petal being alone developed; and this
stamen is not present in the ordinary flowers of this species; the style
is aborted; and the ovaria are reduced from three to two. Now although
natural selection may well have had the power to prevent some of
the flowers from expanding, an