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
Pot 8 : 34 5/8 : 29 : 26 6/8.
Pot 8 : 28 5/8 : 0 : +.
Pot 9 : 25 5/8 : 28 5/8 : +.
Pot 9 : 0 : + : 0.
Pot 10 : 38 : 28 4/8 : 22 7/8.
Pot 10 : 32 1/8 : + : 0.
Total : 525.13 : 420.00 : 265.50.
The average height of the sixteen London-crossed plants in Table 4/47 is
32.82 inches; that of the fifteen intercrossed plants, 28 inches; and
that of the ten self-fertilised plants, 26.55.
So that in height we have the following ratios:--
The London-crossed to the self-fertilised as 100 to 81.
The London-crossed to the intercrossed as 100 to 85.
The intercrossed to the self-fertilised as 100 to 95.
These three lots of plants, which it should be remembered were all
derived on the mother-side from plants of the third self-fertilised
generation, fertilised in three different ways, were left exposed to the
visits of insects, and their flowers were freely crossed by them. As the
capsules of each lot became ripe they were gathered and kept separate,
the empty or bad ones being thrown away. But towards the middle of
October, when the capsules could no longer ripen, all were gathered and
were counted, whether good or bad. The capsules were then crushed, and
the seed cleaned by sieves and weighed. For the sake of uniformity the
results are given from calculation, as if there had been twenty plants
in each lot.
The sixteen London-crossed plants actually produced 286 capsules;
therefore twenty such plants would have produced 357.5 capsules; and
from the actual weight of the seeds, the twenty plants would have
yielded 462 grains weight of seeds.
The fifteen intercrossed plants actually produced 157 capsules;
therefore twenty of them would have produced 209.3 capsules and the
seeds would have weighed 208.48 grains.
The ten self-fertilised plants actually produced 70 capsules, therefore
twenty of them would have produced 140 capsules; and the seeds would
have weighed 153.2 grains.
From these data we get the following ratios:--
NUMBER OF CAPSULES PRODUCED BY AN EQUAL NUMBER OF PLANTS OF THE THREE
LOTS.
NUMBER OF CAPSULES:
The London-crossed to the self-fertilised as 100 to 39.
The London-crossed to the intercrossed as 100 to 45.
The intercrossed to the self-fertilised as 100 to 67.
WEIGHT OF SEEDS PRODUCED BY AN EQUAL NUMBER OF PLANTS OF THE THREE LOTS.
WEIGHT OF SEED:
The London-crossed to the self-fertilised as 100 to 33.
The London-crossed to the intercrossed as 100 to 45.
The intercrossed to the self-fertilised as 100 to 73.
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