But he has further shown, by the careful
examination of many flowers, that this power has not as yet been perfected; and,
consequently, that a certain proportion of the pollen is rendered useless,
namely, that from the anthers which do not rotate properly. It thus appears that
the development of the plant has not as yet been completed; the stamens have
indeed acquired their proper length, but not their full and perfect power of
rotation. (3/25. Fritz Muller gives another instance of the want of absolute
perfection in the flowers of another member of the Rubiaceae, namely, Posoqueria
fragrans, which is adapted in a most wonderful manner for cross-fertilisation by
the agency of moths. (See 'Botanische Zeitung' 1866 Number 17.) In accordance
with the nocturnal habits of these insects, most of the flowers open only during
the night; but some open in the day, and the pollen of such flowers is robbed,
as Fritz Muller has often seen, by humble-bees and other insects, without any
benefit being thus conferred on the plant.)
The several points of difference in structure between the two forms of Faramea
are highly remarkable. Until within a recent period, if any one had been shown
two plants which differed in a uniform manner in the length of their stamens and
pistils,--in the form of their stigmas,--in the manner of dehiscence and
slightly in the size of their anthers,--and to an extraordinary degree in the
diameter and structure of their pollen-grains, he would have declared it
impossible that the two could have belonged to one and the same species.
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