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
Twelve flowers on the crossed plants of the last generation growing in
the four large pots just mentioned, were crossed with pollen from a
crossed plant growing in one of the other pots; and twelve flowers on
the self-fertilised plants were fertilised with their own pollen. All
these flowers of both lots produced fine capsules. Ten of the crossed
capsules contained by weight 38.92 grains of seeds, and ten of the
self-fertilised capsules 37.74 grains; or as 100 to 97. Some of these
seeds in an equal state of germination were planted in pairs on the
opposite sides of five large pots. A good many of the crossed seeds
germinated before the self-fertilised, and were of course rejected. The
plants thus raised were measured when several of them were in full
flower.
TABLE 6/85. Nicotiana tabacum (second generation).
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Crossed Plants.
Column 3: Self-fertilised Plants.
Pot 1 : 14 4/8 : 27 6/8.
Pot 1 : 78 4/8 : 8 6/8.
Pot 1 : 9 : 56.
Pot 2 : 60 4/8 : 16 6/8.
Pot 2 : 44 6/8 : 7.
Pot 2 : 10 : 50 4/8.
Pot 3 : 57 1/8 : 87 (A).
Pot 3 : 1 2/8 : 81 2/8 (B).
Pot 4 : 6 6/8 : 19.
Pot 4 : 31 : 43 2/8.
Pot 4 : 69 4/8 : 4.
Pot 5 : 99 4/8 : 9 4/8.
Pot 5 : 29 2/8 : 3.
Total : 511.63 : 413.75.
The thirteen crossed plants here average 39.35, and the thirteen
self-fertilised plants 31.82 inches in height; or as 100 to 81. But it
would be a very much fairer plan to exclude all the starved plants of
only 10 inches and under in height; and in this case the nine remaining
crossed plants average 53.84, and the seven remaining self-fertilised
plants 51.78 inches in height, or as 100 to 96; and this difference is
so small that the crossed and self-fertilised plants may be considered
as of equal heights.
In addition to these plants, three crossed plants were planted
separately in three large pots, and three self-fertilised plants in
three other large pots, so that they were not exposed to any
competition; and now the self-fertilised plants exceeded the crossed in
height by a little, for the three crossed averaged 55.91, and the three
self-fertilised 59.16 inches; or as 100 to 106.
CROSSED AND SELF-FERTILISED PLANTS OF THE THIRD GENERATION.
TABLE 6/86. Nicotiana tabacum (third generation). Seedlings from the
self-fertilised plant A in pot 3, Table 6/85, of the last or second
generation.
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: From Self-fertilised Plant, crossed by a Crossed Plant.
Column 3: From Self-fertilised Plant again self-fertilised, forming the
third Self-fertilised generation.
Pot 1 : 100 2/8 : 98.
Pot 1 : 91 : 79.
Pot 2 : 110 2/8 : 59 1/8.
Pot 2 : 100 4/8 : 66 6/8.
Pot 3 : 104 : 79 6/8.
Pot 4 : 84 2/8 : 110 4/8.
Pot 4 : 76 4/8 : 64 1/8.
Total : 666.75 : 557.25.
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