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The Different Forms of Flowers on Plants of the Same Species by Charles Darwin
page 44 of 371 (11%)
fertile, five long-styled plants were protected by me from insects; and they
bore up to a given period 147 flowers which set 62 capsules; but many of these
soon fell off, showing that they had not been properly fertilised. At the same
time five short-styled plants were similarly treated, and they bore 116 flowers
which ultimately produced only seven capsules. On another occasion 13 protected
long-styled plants yielded by weight 25.9 grains of spontaneously self-
fertilised seeds. At the same time seven protected short-styled plants yielded
only half-a-grain weight of seeds. Therefore the long-styled plants yielded
nearly 24 times as many spontaneously self-fertilised seeds as did the same
number of short-styled plants. The chief cause of this great difference appears
to be, that when the corolla of a long-styled plant falls off, the anthers, from
being situated near the bottom of the tube are necessarily dragged over the
stigma and leave pollen on it, as I saw when I hastened the fall of nearly
withered flowers; whereas in the short-styled flowers, the stamens are seated at
the mouth of the corolla, and in falling off do not brush over the lowly-seated
stigmas. Hildebrand likewise protected some long-styled and short-styled plants,
but neither ever yielded a single capsule. He thinks that the difference in our
results may be accounted for by his plants having been kept in a room and never
having been shaken; but this explanation seems to me doubtful; his plants were
in a less fertile condition than mine, as shown by the difference in the number
of seeds produced, and it is highly probable that their lessened fertility would
have interfered with especial force with their capacity for producing self-
fertilised seeds.

[Primula auricula. (1/11. According to Kerner our garden auriculas are descended
from P. pubescens, Jacq., which is a hybrid between the true P. auricula and
hirsuta. This hybrid has now been propagated for about 300 years, and produces,
when legitimately fertilised, a large number of seeds; the long-styled forms
yielding an average number of 73, and the short-styled 98 seeds per capsule: see
his "Geschichte der Aurikel" 'Zeitschr. des Deutschen und Oest. Alpen-Vereins'
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