" A hundred years before, Nehemias Grew
had said that it was necessary for pollen to reach the stigma of
a flower in order that it might set fertile seed; and Linnaeus
had to come to his aid with conclusive evidence to convince a
doubting world that this was true. Sprengel made the next step
forward, but his writings lay neglected over seventy years
because he advanced the then incredible and only partially true
statement that a flower is fertilized by insects which carry its
pollen from its anthers to its stigma. In spite of his
discoveries that the hairs inside the geranium's corolla protect
its nectar from rain for the insect's benefit, just as eyebrows
keep perspiration from falling into the eye; that most flowers
which secrete nectar have what he termed "honey guides" - spots
of bright color, heavy veining, or some such pathfinder on the
petals - in spite of the most patient and scientific research
that shed great light on natural selection a half-century before
Darwin advanced the theory, he left it for the author of "The
Origin of Species" to show that cross-fertilization - the
transfer of pollen from one blossom to another, not from anthers
to stigma of the same flower - is the great end to which so much
marvelous mechanism is chiefly adapted.
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