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
Some of the remaining seeds of both series, whether or not in a state of
germination, were thickly sown on the opposite sides of two very large
pots; and the six highest plants on each side of each pot were measured
after they had grown to nearly their full height. But their heights were
much less than in the former trials, owing to their extremely crowded
condition. Even whilst quite young, the crossed seedlings manifestly had
much broader and finer leaves than the self-fertilised seedlings.
TABLE 6/89. Nicotiana tabacum. Plants of the same parentage as those in
Table 6/88, but grown extremely crowded in two large pots.
Heights of plants measured in inches.
Column 1: Kew-crossed Plants, from pot 2, Table 6/87.
Column 2: Plants of the fourth Self-fertilised generation, from pot 2,
Table 6/87.
Column 3: Kew-crossed Plants, from pot 5, Table 6/87.
Column 4: Plants of the fourth Self-fertilised generation, from pot 5,
Table 6/87.
42 4/8 : 22 4/8 : 44 6/8 : 22 4/8.
34 : 19 2/8 : 42 4/8 : 21.
30 4/8 : 14 2/8 : 27 4/8 : 18.
23 4/8 : 16 : 31 2/8 : 15 2/8.
26 6/8 : 13 4/8 : 32 : 13 5/8.
18 3/8 : 16 : 24 6/8 : 14 6/8.
175.63 : 101.50 : 202.75 : 105.13.
The twelve tallest crossed plants in the two pots belonging to the two
series average here 31.53, and the twelve tallest self-fertilised plants
17.21 inches in height; or as 100 to 54. The plants on both sides, when
fully grown, some time after they had been measured, were cut down close
to the ground and weighed. The twelve crossed plants weighed 21.25
ounces; and the twelve self-fertilised plants only 7.83 ounces; or in
weight as 100 to 37.
The rest of the crossed and self-fertilised seeds from the two
parent-plants (the same as in the last experiment) was sown on the 1st
of July in four long parallel and separate rows in good soil in the open
ground; so that the seedlings were not subjected to any mutual
competition. The summer was wet and unfavourable for their growth.
Whilst the seedlings were very small the two crossed rows had a clear
advantage over the two self-fertilised rows. When fully grown the twenty
tallest crossed plants and the twenty tallest self-fertilised plants
were selected and measured on the 11th of November to the extremities of
their leaves, as shown in Table 6/90. Of the twenty crossed plants,
twelve had flowered; whilst of the twenty self-fertilised plants one
alone had flowered.
TABLE 6/90. Nicotiana tabacum. Plants raised from the same seeds as in
the last two experiments, but sown separately in the open ground, so as
not to compete together.
Heights of plants measured in inches.
Column 1: Kew-crossed Plants, from pot 2, Table 6/87.
Column 2: Plants of the fourth Self-fertilised generation, from pot 2,
Table 6/87.
Column 3: Kew-crossed Plants, from pot 5, Table 6/87.
Column 4: Plants of the fourth Self-fertilised generation, from pot 5,
Table 6/87.
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