The Effects of Cross & Self-Fertilisation in the Vegetable KingdomDarwin, Charles
Science
The Effects of Cross & Self-Fertilisation in the Vegetable Kingdom
Darwin, Charles
Fertilization of plants; Plants -- Variation; Pollination
Heights of Plants in inches:
Column 1: Number (Name) of Pot.
Column 2: Crossed Plants.
Column 3: Self-fertilised Plants.
Pot 1 : 74 : 56 4/8.
Pot 1 : 72 : 51 4/8.
Pot 1 : 73 4/8 : 54.
Pot 2 : 82 : 59.
Pot 2 : 81 : 30.
Pot 2 : 82 : 66.
Total : 464.5 : 317.
Again all the crossed plants are higher than their antagonists: their
average height is 77.41 inches, whereas that of the self-fertilised is
52.83 inches, or as 100 to 68.
I attended closely to the fertility of the plants of this third
generation. Thirty flowers on the crossed plants were crossed with
pollen from other crossed plants of the same generation, and the
twenty-six capsules thus produced contained, on an average, 4.73 seeds;
whilst thirty flowers on the self-fertilised plants, fertilised with the
pollen from the same flower, produced twenty-three capsules, each
containing 4.43 seeds. Thus the average number of seeds in the crossed
capsules was to that in the self-fertilised capsules as 100 to 94. A
hundred of the crossed seeds weighed 43.27 grains, whilst a hundred of
the self-fertilised seeds weighed only 37.63 grains. Many of these
lighter self-fertilised seeds placed on damp sand germinated before the
crossed; thus thirty-six of the former germinated whilst only thirteen
of the latter or crossed seeds germinated. In Pot 1 the three crossed
plants produced spontaneously under the net (besides the twenty-six
artificially cross-fertilised capsules) seventy-seven self-fertilised
capsules containing on an average 4.41 seeds; whilst the three
self-fertilised plants produced spontaneously (besides the twenty-three
artificially self-fertilised capsules) only twenty-nine self-fertilised
capsules, containing on an average 4.14 seeds. Therefore the average
number of seeds in the two lots of spontaneously self-fertilised
capsules was as 100 to 94. Taking into consideration the number of
capsules together with the average number of seeds, the crossed plants
(spontaneously self-fertilised) produced seeds in comparison with the
self-fertilised plants (spontaneously self-fertilised) in the proportion
of 100 to 35. By whatever method the fertility of these plants is
compared, the crossed are more fertile than the self-fertilised plants.
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